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WO2019009145A1 - Liquid crystal display device - Google Patents

Liquid crystal display device Download PDF

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Publication number
WO2019009145A1
WO2019009145A1 PCT/JP2018/024264 JP2018024264W WO2019009145A1 WO 2019009145 A1 WO2019009145 A1 WO 2019009145A1 JP 2018024264 W JP2018024264 W JP 2018024264W WO 2019009145 A1 WO2019009145 A1 WO 2019009145A1
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WO
WIPO (PCT)
Prior art keywords
optical compensation
compensation layer
liquid crystal
polarizer
display device
Prior art date
Application number
PCT/JP2018/024264
Other languages
French (fr)
Japanese (ja)
Inventor
健治 藤田
全亮 齊藤
隆行 夏目
Original Assignee
シャープ株式会社
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Publication date
Application filed by シャープ株式会社 filed Critical シャープ株式会社
Publication of WO2019009145A1 publication Critical patent/WO2019009145A1/en

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    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B5/00—Optical elements other than lenses
    • G02B5/30—Polarising elements
    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
    • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
    • G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells
    • G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
    • G02F1/1333—Constructional arrangements; Manufacturing methods
    • G02F1/1335—Structural association of cells with optical devices, e.g. polarisers or reflectors
    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
    • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
    • G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells
    • G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
    • G02F1/1333—Constructional arrangements; Manufacturing methods
    • G02F1/1335—Structural association of cells with optical devices, e.g. polarisers or reflectors
    • G02F1/13363—Birefringent elements, e.g. for optical compensation

Definitions

  • the present invention relates to a liquid crystal display device. More specifically, the present invention relates to a liquid crystal display device suitable for a liquid crystal display device in a vertical alignment mode provided with a pair of circularly polarizing plates.
  • a liquid crystal display device generally includes a pair of linear polarizing plates as polarizing plates and a liquid crystal cell provided between the pair of linear polarizing plates, and various types such as vertical alignment (VA) mode and horizontal alignment mode. Display modes have been developed.
  • VA vertical alignment
  • a VA mode liquid crystal display device using a pair of circularly polarizing plates instead of a pair of linear polarizing plates as a polarizing plate has been developed.
  • a circularly polarizing plate is typically constituted by a combination of a linear polarizing plate and a ⁇ / 4 retardation plate.
  • a VA mode liquid crystal display device using a pair of circularly polarizing plates is also referred to as a VA circularly polarizing panel.
  • the VA circularly polarizing panel has room for improvement in that the contrast ratio at an oblique viewing angle is low and a sufficient viewing angle characteristic can not be obtained.
  • various techniques for improving the viewing angle characteristics using an optical compensation film have been proposed.
  • a pair of polarizers consisting of polarizer A and polarizer B and a pair of polarizers are disclosed.
  • the liquid crystal display device is provided with a liquid crystal cell of the vertical alignment type disposed in the above, and Nz represented by the following formula (1) between the liquid crystal cell and the polarizer A and between the liquid crystal cell and the polarizer B: Retarders each having a value of more than 2.0, and the in-plane slow axis of the quarter-wave retarder has a positional relationship of approximately 45 ° with the transmission axis of the adjacent polarizer, At least one of A and the adjacent 1 ⁇ 4 ⁇ retardation plate and / or between the polarizer B and the adjacent 1 ⁇ 4 ⁇ retardation plate comprises a material layer having a negative intrinsic birefringence value, And the in-plane slow axis is in a positional relationship substantially parallel or nearly orthogonal to the absorption
  • the first polarizer functions as a first polarizer and a ⁇ / 4 plate as a liquid crystal display device in which light leakage in an oblique direction is suppressed in the circular polarization mode and a viewing angle is accurately compensated.
  • a liquid crystal cell, a second optical compensation layer functioning as a ⁇ / 4 plate, a third optical compensation layer having a refractive index relationship of nz>nx> ny, and a second polarizer Of the first optical compensation layer and the second optical compensation layer, with the retardation wavelength dispersion value (Re cell [450] / Re cell [550]) of the liquid crystal cell as ⁇ cell.
  • the ⁇ ⁇ / 4 / ⁇ cell is 0.95 to 1.02.
  • a liquid crystal display device having a liquid crystal panel is disclosed.
  • the circular polarizer structure constituting the liquid crystal display element is the first for its optical compensation.
  • the circular analyzer structure has an anisotropy of refractive index nx ny ny ⁇ between the second polarizing plate and the second retardation plate for optical compensation.
  • variable retarder structure includes the uniaxial sixth retardation plate and the eighth retardation plate with nz and the uniaxial seventh retardation plate with the refractive index anisotropy of nx> ny ⁇ nz
  • a liquid crystal display device comprising a ninth retardation plate having a refractive index anisotropy of nxnxny> nz between the first retardation plate and the second retardation plate for compensation It has been disclosed.
  • Patent Document 4 wide viewing angle compensation can be performed on a liquid crystal cell, and circularly polarized light of a wide band can be obtained, which contributes to thinning, prevents thermal unevenness, and leaks light in black display.
  • the retardation Rth 2 in the thickness direction is 30 to 400 nm
  • the angle between the absorption axis of the polarizer and the slow axis of the first optical compensation layer is “+” or “ ⁇ ” 25 to 65 °
  • a polarizing plate with an optical compensation layer is disclosed.
  • Patent Document 5 as a liquid crystal display device which can be manufactured at low cost and simply and which can realize a high contrast ratio in a wide viewing angle range, a first polarizer, a first birefringence, and the like are disclosed.
  • Layer, first ⁇ / 4 plate, liquid crystal cell, second ⁇ / 4 plate, second birefringent layer, and second absorption axis orthogonal to absorption axis of first polarizer A liquid crystal display device having a polarizer in this order, wherein the first birefringent layer satisfies Nz> 0.9, and the in-plane slow axis is orthogonal to the absorption axis of the first polarizer, In the first ⁇ / 4 plate, the in-plane slow axis forms an angle of about 45 ° with the absorption axis of the first polarizer, and the liquid crystal cell makes liquid crystal molecules in the liquid crystal cell perpendicular to the substrate surface
  • the second ⁇ / 4 plate has the in-plane
  • Patent Document 6 discloses that a long polymer film continuously supplied is conveyed while being held at both ends.
  • a method for producing a retardation film which transports a molecular film while stretching it in a transverse direction orthogonal to the transport direction, in which the polymer film is stretched in the transverse direction with the polymer film slackened in the transport direction.
  • a method of making a retardation film is disclosed.
  • the characteristic change of the optical compensation layer is large in an environment such as a low temperature, a high temperature, a high temperature and high humidity environment, and a drop in display quality such as a drop in contrast or display unevenness may occur.
  • a solvent adheres to the polarizing plate peeling of the optical compensation layer from the polarizer and breakage of the optical compensation layer may occur.
  • the thickness of the polarizing plate becomes large and it is not suitable for mobile applications.
  • a third optical compensation layer having a refractive index relationship of nz> nx> ny is used, but such an optical compensation layer has a viewing angle improving effect.
  • the required optical parameters are narrow and the materials and processes that can be selected are limited. Furthermore, when materials that can be mass-produced are selected from the viewpoint of cost and production tact, the occurrence of the problems as described in (1) to (3) above can not be avoided.
  • the liquid crystal display element of patent document 3 uses many retardation plates for optical compensation, when the number of optical compensation layers increases, the thickness of the liquid crystal panel containing a polarizing plate becomes like said (3). With the increase, the manufacturing cost will increase.
  • the present invention has been made in view of the above-mentioned present situation, and can suppress deterioration of display quality even under severe environment, can suppress peeling and breakage at the time of solvent adhesion to a polarizing plate, and liquid crystal
  • An object of the present invention is to provide a liquid crystal display device capable of thinning a panel.
  • the inventors of the present invention can suppress deterioration in display quality even under severe environments, can suppress peeling and breakage at the time of solvent adhesion to a polarizing plate, and can make a liquid crystal panel thinner.
  • the first optical compensation layer having an in-plane retardation Re of 15 nm or less and a thickness direction retardation Rth of ⁇ 60 nm or less, and Two layers with a second optical compensation layer having an internal retardation Re of 40 to 120 nm and satisfying 1 ⁇ Nz ⁇ 4 are provided, and the in-plane slow axis of the second optical compensation layer is a liquid crystal cell.
  • the first polarizer, the first optical compensation layer, the second optical compensation layer, and the third optical compensation layer functioning as a ⁇ / 4 retardation plate are opposed to each other.
  • a liquid crystal cell including a pair of substrates and a liquid crystal layer between the pair of substrates, a fourth optical compensation layer functioning as a ⁇ / 4 retardation plate, and a second polarizer in this order;
  • the first polarizer has an absorption axis at an angle of substantially 90 ° to the absorption axis of the second polarizer, and the first optical compensation layer has an in-plane retardation Re of 15 nm or less
  • the thickness direction retardation Rth is ⁇ 60 nm or less
  • the second optical compensation layer has an in-plane retardation Re of 40 to 120 nm, satisfies 1 ⁇ Nz ⁇ 4, and an in-plane retardation
  • the phase axis is substantially parallel to the absorption axis of the first polarizer
  • the third optical compensation layer has an in-plan
  • the third and fourth optical compensation layers may each satisfy 1 ⁇ Nz ⁇ 2.4.
  • the liquid crystal display device does not include an optical compensation layer other than the first to third optical compensation layers between the first polarizer and the liquid crystal cell, and the liquid crystal cell and the second polarizer And the optical compensation layer other than the fourth optical compensation layer.
  • the first optical compensation layer has a thickness direction retardation Rth of ⁇ 200 to ⁇ 100 nm
  • the second optical compensation layer has an in-plane retardation Re of 60 to 110 nm, and 1 ⁇ Nz ⁇
  • the third optical compensation layer may satisfy 1.4 ⁇ Nz ⁇ 2.4
  • the fourth optical compensation layer may satisfy 1.4 ⁇ Nz ⁇ 2.4. .
  • the liquid crystal display device has an in-plane retardation Re of 40 to 120 nm, satisfies 1 ⁇ Nz ⁇ 4, and an in-plane slow axis is substantially parallel to the absorption axis of the second polarizer.
  • a fifth optical compensation layer, and a sixth optical compensation layer having an in-plane retardation Re of 15 nm or less and a thickness direction retardation Rth of -60 nm or less, the first polarizer,
  • the layer and the second polarizer may be arranged in this order.
  • the first and sixth optical compensation layers each have a thickness direction retardation Rth of -150 to -80 nm
  • the second and fifth optical compensation layers each have an in-plane retardation Re of 40 to 90 nm and satisfy 1 ⁇ Nz ⁇ 1.4
  • the third optical compensation layer satisfies 1.4 ⁇ Nz ⁇ 2.4
  • the fourth optical compensation layer satisfies 1.4 ⁇ It may satisfy Nz ⁇ 2.4.
  • the liquid crystal display device has a seventh optical compensation layer having an in-plane retardation Re of 15 nm or less, a thickness direction retardation Rth of 50 to 300 nm, and Nz> 1, and an in-plane retardation Re of And an eighth optical compensation layer having a thickness direction retardation Rth of 50 to 300 nm and Nz> 1 and having a thickness of 15 nm or less, the first polarizer, the first optical compensation layer, The second optical compensation layer, the third optical compensation layer, the seventh optical compensation layer, the liquid crystal cell, the eighth optical compensation layer, the fourth optical compensation layer, the fifth optical compensation
  • the layer, the sixth optical compensation layer, and the second polarizer may be arranged in this order.
  • the first and sixth optical compensation layers each have a thickness direction retardation Rth of -150 to -80 nm, and the second and fifth optical compensation layers each have an in-plane retardation Re of 40 to
  • the third and fourth optical compensation layers may be 90 nm and satisfy 1 ⁇ Nz ⁇ 1.4, and each of the third and fourth optical compensation layers may satisfy 1 ⁇ Nz ⁇ 1.4.
  • the in-plane retardation Re of the third optical compensation layer may be substantially the same as the in-plane retardation Re of the fourth optical compensation layer.
  • Each of the third and fourth optical compensation layers may have an in-plane retardation Re of 100 to 175 nm.
  • the present invention it is possible to suppress deterioration in display quality even when placed under a severe environment, to suppress peeling and breakage at the time of solvent adhesion to a polarizing plate, and to reduce the thickness of the liquid crystal panel.
  • the device can be realized.
  • FIG. 1 is a schematic plan view of a liquid crystal display device according to Embodiment 1.
  • FIG. 1 is a schematic cross-sectional view of a liquid crystal display device according to Embodiment 1.
  • FIG. 1 is a schematic perspective view of a liquid crystal display device according to Embodiment 1.
  • FIG. 1 is a schematic cross-sectional view of a liquid crystal display device according to a lamination structure 1-1 of Embodiment 1.
  • FIG. 1 is a schematic cross-sectional view of a liquid crystal display device according to laminated structure 1-2 in embodiment 1.
  • FIG. 1 is a schematic perspective view of a liquid crystal display device according to a laminated structure 1-2 of Embodiment 1.
  • FIG. 1 is a schematic plan view of a liquid crystal display device according to Embodiment 1.
  • FIG. 1 is a schematic cross-sectional view of a liquid crystal display device according to Embodiment 1.
  • FIG. 1 is a schematic perspective view of a liquid crystal display device according to Embodiment 1.
  • FIG. 1 is a schematic cross-sectional view of a liquid crystal display device according to laminated structure 1-3 of embodiment 1.
  • FIG. 1 is a schematic perspective view of a liquid crystal display device according to laminated structure 1-3 of embodiment 1.
  • FIG. 1 is a schematic cross-sectional view of a liquid crystal display device according to Example 1.
  • FIG. 5 is a schematic cross-sectional view of a liquid crystal display device according to Comparative Example 1;
  • FIG. 7 is an iso-contrast ratio contour line of the liquid crystal display device according to Example 1.
  • FIG. It is an iso-contrast ratio contour line of the liquid crystal display device which concerns on the comparative example 1.
  • FIG. It is an iso-contrast ratio contour line of the liquid crystal display device which concerns on the reference example 1.
  • FIG. 6 is a schematic cross-sectional view of a liquid crystal display device according to Example 2.
  • FIG. 10 is an iso-contrast ratio contour line of the liquid crystal display device according to Example 2.
  • FIG. 7 is a schematic cross-sectional view of a liquid crystal display device according to Example 3.
  • FIG. 16 is an iso-contrast ratio contour line of the liquid crystal display device according to Example 3.
  • Refractive index (nx, ny, nz) “Nx” is the refractive index in the direction in which the in-plane refractive index is maximum (ie, the slow axis direction), and “ny” is the refractive index in the in-plane direction orthogonal to the slow axis "Nz” is the refractive index in the thickness direction.
  • Refractive index (nx, ny, nz) “Nx” is the refractive index in the direction in which the in-plane refractive index is maximum (ie, the slow axis direction), and “ny” is the refractive index in the in-plane direction orthogonal to the slow axis "Nz” is the refractive index in the thickness direction.
  • In-plane retardation (Re) refers to the in-plane retardation value of a layer (film) at a wavelength of 550 nm at 23 ° C., unless otherwise specified.
  • Re (nx ⁇ ny) ⁇ d, where d (nm) is the thickness of the layer (film).
  • the optical compensation layer has an in-plane retardation Re of 15 nm or more and a retardation Rth in the thickness direction of +55 nm or more or -15 nm or less for light of wavelength 550 nm unless otherwise specified. And the function and optical performance thereof are not particularly limited. That is, the optical compensation layer is a layer satisfying 15 nm ⁇ Re and Rth ⁇ ⁇ 15 nm or +55 nm ⁇ Rth.
  • the viewing surface side and the rear surface viewing surface side mean the side closer to the screen (display surface) of the liquid crystal display device, and the rear surface side is more about the screen (display surface) of the liquid crystal display device It means the far side.
  • a member (for example, an optical compensation layer) adjacent to another member (for example, an optical compensation layer) means that an optical compensation layer is not provided between both members, for example, A form in which a layer having no optical anisotropy is disposed between the two members is included.
  • the layer having no optical anisotropy means a layer satisfying Re ⁇ 15 nm and ⁇ 15 nm ⁇ Rth ⁇ +55 nm.
  • FIG. 1 is a schematic plan view of the liquid crystal display device according to the first embodiment.
  • FIG. 2 is a schematic cross-sectional view of the liquid crystal display device according to the first embodiment.
  • the liquid crystal display device 1 according to the present embodiment includes a liquid crystal panel 2, and the liquid crystal panel 2 has a display area 2 a corresponding to the shape.
  • a plurality of pixels (not shown) are arranged in a matrix in the display area 2a, and an image is displayed in the display area 2a.
  • the liquid crystal display device 1 is a transmissive or semi-transmissive liquid crystal display device, and includes a liquid crystal panel 2 and a backlight (not shown) disposed on the back side of the liquid crystal panel 2 as shown in FIG.
  • the liquid crystal panel 2 includes a first polarizer 11, a first optical compensation layer 21, a second optical compensation layer 22, and a third optical compensation layer 23 functioning as a ⁇ / 4 retardation plate.
  • a liquid crystal cell 30, a fourth optical compensation layer 24 functioning as a ⁇ / 4 retardation plate, and a second polarizer 12 are provided in this order.
  • the first circularly polarizing plate 3 including the first polarizer 11, the first optical compensation layer 21, the second optical compensation layer 22, and the third optical compensation layer 23, and the fourth optical compensation
  • a second circularly polarizing plate 4 including a layer 24 and a second polarizer 12 is provided on both sides of the liquid crystal panel 2.
  • the liquid crystal cell 30 also includes a pair of substrates 31 and 32 facing each other, and a liquid crystal layer 33 between the pair of substrates 31 and 32.
  • FIG. 3 is a schematic perspective view of the liquid crystal display device according to the first embodiment.
  • the absorption axis 11a forms an angle of substantially 90 ° with the absorption axis 12a of the second polarizer 12, and the second optical compensation layer 22
  • the in-plane slow axis 22 a is substantially parallel to the absorption axis 11 a of the first polarizer 11, and the third optical compensation layer 23 has an in-plane slow axis 23 a of the absorption of the first polarizer 11.
  • the fourth optical compensation layer 24 has an in-plane slow axis 24 a relative to the in-plane slow axis 23 a of the third optical compensation layer 23 at an angle of substantially 45 ° or 135 ° with respect to the axis 11 a.
  • the angle is substantially 90 degrees.
  • the liquid crystal cell 30 aligns liquid crystal molecules in the liquid crystal layer 33 substantially perpendicularly to the pair of substrates 31 and 32 in black display.
  • the first optical compensation layer 21 has an in-plane retardation Re of 15 nm or less, and a thickness direction retardation Rth of ⁇ 60 nm or less, and the second optical compensation layer 22 has an in-plane retardation Re of Is 40 to 120 nm, and 1 ⁇ Nz ⁇ 4 is satisfied.
  • the first to fourth optical compensation layers 21 to 24 have relatively many options for their materials.
  • the optical compensation layer 24 to 24 it is possible to use an optical compensation layer having a relatively small change in characteristics such as optical parameters even under severe environments such as low temperature, high temperature, high temperature and high humidity environment. Therefore, even after the liquid crystal display device 1 is left in a severe environment such as a low temperature, a high temperature, a high temperature and high humidity environment, it is possible to suppress a decrease in display quality (for example, contrast, display unevenness).
  • a material having high durability to a solvent can be selected as the material of the first to fourth optical compensation layers 21 to 24, so that the solvent to the polarizing plate (circularly polarizing plates 3 and 4) Of the first to fourth optical compensation layers 21 to 24 can be suppressed from peeling from the first or second polarizer 11 or 12 and the first to fourth optical compensation layers 21 to 24 The occurrence of 24 fractures can be suppressed. Furthermore, according to the liquid crystal display device 1, the number of optical compensation layers can be reduced to a minimum of four (first to fourth optical compensation layers 21 to 24), thereby improving productivity (that is, reducing manufacturing costs). At the same time, the overall thickness of the liquid crystal display device 1 can be reduced.
  • the liquid crystal display device 1 can further include an optical compensation layer in addition to the first to fourth optical compensation layers 21 to 24 as described later, but the second optical compensation layer 22 is a first optical
  • the third optical compensation layer 23 is preferably disposed adjacent to the second optical compensation layer 22.
  • each member may be disposed such that the first polarizer 11 and the second polarizer 12 are on the viewing surface side and the back surface, respectively.
  • the respective members may be arranged such that the second polarizer 12 and the first polarizer 11 are on the viewing surface side and the back surface side, respectively.
  • the liquid crystal display device 1 is a normally black mode liquid crystal display device which performs black display when no voltage is applied.
  • the polarizers 11 and 12 are arranged in crossed nicols, and as described above
  • One polarizer 11 has an absorption axis 11 a substantially at an angle of 90 ° with respect to the absorption axis 12 a of the second polarizer 12.
  • the fact that the absorption axis 11a forms an angle of substantially 90 ° with respect to the absorption axis 12a means that, more specifically, the angle (absolute value) between the two axes is within a range of 90 ⁇ 2 °. This is preferably within the range of 90 ⁇ 0.6 °, and particularly preferably 90 ° (perfectly orthogonal).
  • the in-plane slow axis 22 a is substantially parallel to the absorption axis 11 a of the first polarizer 11.
  • that the in-plane slow axis 22a is substantially parallel to the absorption axis 11a more specifically means that the angle x between the two axes satisfies -5 ° ⁇ x ⁇ 5 °.
  • Preferably satisfies -3 ° ⁇ x ⁇ 3 °, more preferably satisfies ⁇ 1 ° ⁇ x ⁇ 1 °, still more preferably satisfies ⁇ 0.5 ° ⁇ x ⁇ 0.5 °, particularly preferably x 0 (perfectly parallel). If the angle x satisfies x ⁇ ⁇ 5 ° or 5 ° ⁇ x, the normal contrast and the viewing angle characteristics may be degraded.
  • the in-plane slow axis 23a forms an angle of substantially 45 ° or 135 ° with the absorption axis 11a of the first polarizer 11.
  • that the in-plane slow axis 23a makes an angle of substantially 45 ° or 135 ° with the absorption axis 11a means that the angle (absolute value) between the two axes is 45 ⁇ 5 ° or 135 ⁇ 5.
  • the in-plane slow axis 24a forms an angle of substantially 90 ° with the in-plane slow axis 23a of the third optical compensation layer 23.
  • the fact that the in-plane slow axis 24a forms an angle of substantially 90 ° with the in-plane slow axis 23a means that the angle (absolute value) between the two axes is 90 ⁇ , more specifically. It means within the range of 2 °, preferably within the range of 90 ⁇ 0.6 °, and particularly preferably 90 ° (completely orthogonal).
  • polarizer Any appropriate polarizer may be employed as the first polarizer 11 and the second polarizer 12 depending on the purpose.
  • a hydrophilic polymer film such as a polyvinyl alcohol-based film (hereinafter, also referred to as a PVA film), a partially formalized polyvinyl alcohol-based film, or an ethylene / vinyl acetate copolymer-based partially saponified film
  • a dichromatic substance dichroic dye
  • a polarizer obtained by adsorbing a dichroic substance (dichroic dye) such as iodine to a polyvinyl alcohol-based film and uniaxially stretching it is particularly preferable because the polarization dichroic ratio is high.
  • the thickness of these polarizers is not particularly limited, but in general, it is about 5 to 30 ⁇ m.
  • a polarizer obtained by adsorbing iodine to a polyvinyl alcohol-based film and uniaxially stretching it can be produced, for example, by dyeing polyvinyl alcohol by immersing it in an aqueous solution of iodine and stretching it to 3 to 7 times its original length. . If necessary, it may contain boric acid, zinc sulfate, zinc chloride or the like, or it may be immersed in an aqueous solution such as potassium iodide. Furthermore, if necessary, the polyvinyl alcohol-based film may be dipped in water and rinsed before dyeing.
  • Stretching may be carried out after dyeing with iodine, may be stretched while dyeing, or may be dyed with iodine after being stretched. It can also be stretched in an aqueous solution of boric acid or potassium iodide or in a water bath.
  • the first polarizer 11 and the second polarizer 12 may each be provided with a protective layer on the viewing surface side and the back surface side.
  • the protective layer is formed of any suitable film that can be used as a protective layer of a polarizer.
  • Specific examples of the material that is the main component of the film include, for example, cellulose resins such as triacetyl cellulose (TAC), and transparent resins such as cycloolefin resins. The cycloolefin resin will be described in detail later.
  • a film having triacetyl cellulose as a main component is also referred to as a TAC film
  • a film having a cycloolefin resin, in particular, a cycloolefin polymer (COP) as a main component is also referred to as a COP film.
  • COP cycloolefin polymer
  • the protective layer when a protective layer is provided on the liquid crystal cell 30 side of the first polarizer 11 and / or the second polarizer 12, the protective layer (inner protective layer) preferably has optical isotropy.
  • the retardation Rth in the thickness direction of the inner protective layer is preferably more than -15 nm and less than +15 nm, more preferably -10 nm or more and +10 nm or less, still more preferably -6 nm or more and +6 nm or less, particularly preferably -3 nm or more and +3 nm or less.
  • the in-plane retardation Re of the inner protective layer is preferably 0 nm or more and less than 15 nm, more preferably 0 nm or more and 10 nm or less, still more preferably 0 nm or more and 6 nm or less, and particularly preferably 0 nm or more and 3 nm or less.
  • an optical compensation layer for example, the first optical compensation layer 21 or the fourth optical compensation layer 21 immediately adjacent to the liquid crystal cell 30 side of the first polarizer 11 and the second polarizer 12.
  • the optical compensation layer 24 or the like may be used as a protective layer.
  • the first optical compensation layer 21 satisfies Re ⁇ 15 nm and Rth ⁇ ⁇ 60 nm.
  • the in-plane retardation Re of the first optical compensation layer 21 is preferably 0 to 10 nm, more preferably 0 to 5 nm, still more preferably 0 to 3 nm, and still more preferably 0 to 1 nm. Is particularly preferred.
  • the thickness direction retardation Rth of the first optical compensation layer 21 can be appropriately set within the above range according to the optical parameters of the other members.
  • the first optical compensation layer 21 can be regarded as substantially optically isotropic in the plane when the in-plane retardation Re is sufficiently small, such as 15 nm or less, so the surface of the first optical compensation layer 21 is
  • the arrangement direction in the inside is not particularly limited.
  • the second optical compensation layer 22 satisfies 40 nm ⁇ Re ⁇ 120 nm and 1 ⁇ Nz ⁇ 4.
  • the in-plane retardation Re of the second optical compensation layer 22 can be appropriately set within the above range according to the optical parameters of the other members.
  • the third optical compensation layer 23 and the fourth optical compensation layer 24 function as ⁇ / 4 retardation plates as described above.
  • the ⁇ / 4 retardation plate is an electron optical birefringence plate that serves to rotate the polarization plane of the light beam, and has an optical path of 1 ⁇ 4 wavelength between linearly polarized light vibrating in directions perpendicular to each other.
  • the phase between the ordinary ray component and the extraordinary ray component acts so as to be shifted by a quarter cycle, and circularly polarized light is converted to linearly polarized light (or linearly polarized light to circularly polarized light). Therefore, the first polarizer 11 and the third optical compensation layer 23, and the second polarizer 12 and the fourth optical compensation layer 24 function as left and right circularly polarizing plates orthogonal to each other.
  • the third optical compensation layer 23 and the fourth optical compensation layer 24 each have an in-plane retardation Re of approximately 137.5 nm, but may be 100 to 175 nm, and 110 to 165 nm. Is preferable, and 130 to 145 nm is more preferable. From the viewpoint of maintaining high contrast, the in-plane retardation Re of the third optical compensation layer 23 is preferably substantially the same as the in-plane retardation Re of the fourth optical compensation layer 24.
  • the in-plane retardation Re of the third optical compensation layer 23 and the fourth optical compensation layer 24 is substantially the same, more specifically, the difference between the two in-plane retardations Re ( It means that the absolute value) is 7.64 nm or less, preferably 2 nm or less, more preferably 1 nm or less, and particularly preferably 0 nm (completely the same).
  • the third optical compensation layer 23 and the fourth optical compensation layer 24 each satisfy 1 ⁇ Nz ⁇ 2.4.
  • the material and formation method of the first to fourth optical compensation layers 21 to 24 there is no particular limitation on the material and formation method of the first to fourth optical compensation layers 21 to 24.
  • the polymer film is processed by stretching or the like, the orientation of the liquid crystalline material is fixed, and it is composed of an inorganic material.
  • thin plates or the like to be used can be used, among them, one obtained by processing a polymer film by drawing or the like and one obtained by fixing the orientation of a liquid crystalline material are preferable.
  • the liquid crystal compound is preferably a polymerizable liquid crystal.
  • the first to fourth optical compensation layers 21 to 24 in the case of a polymer film, for example, a solvent cast method, a melt extrusion method or the like can be used. It may be a method of simultaneously forming a plurality of birefringent layers by a co-extrusion method. As long as the desired retardation is developed, it may be non-stretching or may be stretched.
  • the stretching method is also not particularly limited, and it is a special stretching in which stretching is performed under the action of the shrinking force of the heat shrinkable film, in addition to the inter-roll tensile stretching method, inter-roll compression stretching method, tenter transverse uniaxial stretching method, longitudinal and transverse biaxial stretching method. A law etc. can be used.
  • a method of applying a liquid crystalline material on a substrate film subjected to alignment treatment, and orienting and fixing can be used. Even if there is a method in which the substrate film is not subjected to special orientation processing as long as the desired phase difference is expressed, or a method in which the film is peeled off from the substrate film and transferred to another film after orientation fixation. Good. Furthermore, a method in which the orientation of the liquid crystal material is not fixed may be used. Also in the case of a non-liquid crystal material, the same formation method as the liquid crystal material may be used.
  • the liquid crystalline material may be coated on the second optical compensation layer 22.
  • transparent resin such as cycloolefin system resin, cellulose system resin, (meth) acrylic resin
  • (meth) acrylic resin is mentioned, for example.
  • (meth) acrylic-type resin represents at least 1 sort (s) chosen from the group which consists of acrylic resin and methacrylic resin. The same applies to other terms with "(meth)”.
  • the above cycloolefin resin is not particularly limited as long as it is a resin having a monomer unit consisting of cyclic olefin (cycloolefin), and may be any of cycloolefin polymer (COP) or cycloolefin copolymer (COC) .
  • the cycloolefin copolymer refers to a non-crystalline cyclic olefin resin which is a copolymer of a cyclic olefin and an olefin such as ethylene.
  • polycyclic cyclic olefin examples include norbornenes such as norbornene, methyl norbornene, dimethyl norbornene, ethyl norbornene, ethylidene norbornene and butyl norbornene, dicyclopentadiene, dihydrodicyclopentadiene, methyldicyclopentadiene, dimethyldicyclopentadiene and the like
  • Examples include tetracyclododecenes such as dicyclopentadienes, tetracyclododecene, methyltetracyclododecene and dimethyltetracyclododecene, and polymers of cyclopentadienes such as tricyclopentadiene and tetracyclopentadiene.
  • examples of monocyclic cyclic olefins include cyclobutene, cyclopentene, cyclooctene, cyclooctadiene, cyclooctatriene and cyclododecatriene.
  • norbornenes are preferable in terms of transparency, moisture resistance, and retardation control.
  • cellulose resin part or all of hydrogen atoms in hydroxyl groups of cellulose obtained from raw material cellulose such as cotton linta and wood pulp (hardwood pulp and softwood pulp) are substituted with acetyl group, propionyl group and / or butyryl group
  • Cellulose organic acid ester or cellulose mixed organic acid ester For example, those composed of cellulose acetate, propionate, butyrate, mixed esters thereof and the like can be mentioned. Among them, triacetyl cellulose, diacetyl cellulose, cellulose acetate propionate and cellulose acetate butyrate are preferable.
  • the (meth) acrylic resin is a polymer containing a structural unit derived from a (meth) acrylic monomer.
  • the polymer is typically a polymer containing a methacrylic acid ester.
  • the proportion of constituent units derived from methacrylic acid ester is a polymer containing 50% by weight or more based on all constituent units.
  • the (meth) acrylic resin may be a homopolymer of methacrylic acid ester, or may be a copolymer containing a structural unit derived from another polymerizable monomer. In this case, the proportion of constituent units derived from other polymerizable monomers is preferably 50% or less based on all constituent units.
  • methacrylic acid alkyl ester which can comprise the said (meth) acrylic-type resin
  • methacrylic acid alkyl ester is preferable.
  • alkyl methacrylate methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, t-butyl methacrylate, 2-ethylhexyl methacrylate, cyclohexyl methacrylate
  • methacrylic acid alkyl esters having 1 to 8 carbon atoms in the alkyl group such as 2-hydroxyethyl methacrylate.
  • the carbon number of the alkyl group contained in the methacrylic acid alkyl ester is preferably 1 to 4.
  • the (meth) acrylic resin only one kind of methacrylic acid ester may be used alone, or two or more kinds thereof may be used in combination.
  • Examples of the other polymerizable monomer which can constitute the (meth) acrylic resin include acrylic acid esters and compounds having a polymerizable carbon-carbon double bond in another molecule.
  • the other polymerizable monomers may be used alone or in combination of two or more.
  • acrylic acid ester acrylic acid alkyl ester is preferable.
  • alkyl acrylate methyl acrylate, ethyl acrylate, n-propyl acrylate, isopropyl acrylate, n-butyl acrylate, isobutyl acrylate, t-butyl acrylate, 2-ethylhexyl acrylate, cyclohexyl acrylate
  • alkyl acrylates having 1 to 8 carbon atoms in the alkyl group such as 2-hydroxyethyl acrylate.
  • the carbon number of the alkyl group contained in the acrylic acid alkyl ester is preferably 1 to 4. In the (meth) acrylic resin, only one acrylic ester may be used alone, or two or more acrylic esters may be used in combination.
  • Examples of the other compound having a polymerizable carbon-carbon double bond in the molecule include vinyl compounds such as ethylene, propylene and styrene, and vinyl cyan compounds such as acrylonitrile.
  • vinyl compounds such as ethylene, propylene and styrene
  • vinyl cyan compounds such as acrylonitrile.
  • the compound having a polymerizable carbon-carbon double bond in the other molecule one type may be used alone, or two or more types may be used in combination.
  • the polymerizable liquid crystal is a compound having a polymerizable group and having liquid crystallinity.
  • the polymerizable group means a group involved in the polymerization reaction, and is preferably a photopolymerizable group.
  • the photopolymerizable group refers to a group capable of participating in the polymerization reaction by active radicals or acids generated from the photopolymerization initiator.
  • Examples of the polymerizable group include vinyl group, vinyloxy group, 1-chlorovinyl group, isopropenyl group, 4-vinylphenyl group, acryloyloxy group, methacryloyloxy group, oxiranyl group, oxetanyl group and the like.
  • the liquid crystallinity may be a thermotropic liquid crystal or a lyotropic liquid crystal. If the thermotropic liquid crystals are classified according to the degree of order, they may be nematic liquid crystals or smectic liquid crystals, but from the viewpoint of easiness of film formation, thermotropic nematic liquid crystals are preferred. .
  • polymerizable liquid crystal examples include “3.8.6 Network (fully cross-linked type)”, “6. .5.1 Liquid Crystal Materials b. Compounds Having a Polymerizable Group Among the Compounds Described in the Polymerizable Nematic Liquid Crystal Material], compounds disclosed in JP 2010-31223 A, JP 2010-270108 A, JP 2011-6360 A And polymerizable liquid crystals described in JP-A-2011-207765.
  • All of these materials are materials in which the problems as described in the above (1) to (3) are solved or the influence is small, but among them, as the first optical compensation layer 21, a polymerizable liquid crystal It is preferable that the polymer is oriented in parallel to the base material (substrate) and polymerized, and as the second to fourth optical compensation layers 22 to 24, those obtained by drawing a cycloolefin resin, It is preferable to use one obtained by stretching acetyl cellulose, one obtained by stretching a (meth) acrylic resin, and one obtained by orientating and polymerizing a polymerizable liquid crystal in parallel to a substrate (substrate).
  • optical compensation layer formed by the above-mentioned material and forming method as the first to fourth optical compensation layers 21 to 24, occurrence of peeling and breakage even if the solvent adheres to the circularly polarizing plates 3 and 4 Can be suppressed.
  • the liquid crystal cell 30 includes the pair of substrates 31 and 32 facing each other, and the liquid crystal layer 33 between the pair of substrates 31 and 32.
  • a color filter substrate On one of the substrates 31 and 32 (color filter substrate), a color filter, a black matrix and a common electrode are provided.
  • a switching element typically, a TFT for controlling the electro-optical characteristics of liquid crystal, and a scanning line for applying a gate signal to the switching element And a pixel electrode.
  • the color filter may have a thickness direction retardation Rth of about 10 to 50 nm.
  • the color filter may be provided on the active matrix substrate side. The distance between the substrates 31 and 32 (cell gap) is controlled by the spacer.
  • an alignment film made of polyimide is provided on the side of each of the substrates 31 and 32 in contact with the liquid crystal layer 33.
  • the liquid crystal molecules in the liquid crystal layer 33 are substantially perpendicular to the pair of substrates 31 and 32 during black display (black display of the liquid crystal display device 1). Orientation in the normal direction).
  • substantially perpendicular also includes the case where the alignment vector of the liquid crystal molecules is tilted with respect to the normal direction of each substrate 31, 32, that is, the case where the liquid crystal molecules have a tilt angle.
  • the tilt angle (angle from the normal) is at least 0 ° and preferably at all positions of the displayable portion of the liquid crystal panel 2 (the modulatable portion of the light except for the light shielding portion in the display area 2a).
  • the liquid crystal molecules are aligned substantially perpendicular (normal direction) to the surfaces of the substrates 31 and 32 when no voltage is applied.
  • Such alignment can be realized, for example, by arranging a nematic liquid crystal having negative dielectric anisotropy between substrates on which a vertical alignment film is formed as an alignment film.
  • the major axes of the liquid crystal molecules are aligned parallel to the surface of each substrate.
  • the liquid crystal molecules in this state exhibit birefringence with respect to linearly polarized light that has entered the liquid crystal layer through the polarizer on the back side, and the polarization state of the incident light changes in accordance with the inclination of the liquid crystal molecules.
  • a predetermined maximum voltage is applied, light passing through the liquid crystal layer becomes, for example, linearly polarized light whose polarization direction is rotated by 90 °. Therefore, light passing through the polarizer on the viewing surface side is displayed in a bright state (white display) Is obtained.
  • gradation display can be performed by changing the applied voltage to control the inclination of the liquid crystal molecules and changing the transmitted light intensity from the polarizer on the observation surface side.
  • the polarizer axis orientation and the tilt orientation of liquid crystal molecules at the time of voltage application are set to form an angle of 45 °.
  • the transmittance when a birefringent medium is sandwiched between crossed Nicol polarizers is sin 2 (2 ⁇ ), where the angle between the axis of the polarizer and the slow axis of the birefringent medium is ⁇ (unit: rad)
  • ⁇ unit: rad
  • the tilt orientation of liquid crystal molecules can be divided into four domains of 45 °, 135 °, 225 °, and 315 °. Even in the MVA mode divided into such four domains, Schlieren orientation or orientation in an unintended direction is often observed in the vicinity of domain boundaries or orientation control means, which causes transmittance loss. There is.
  • the transmittance when the birefringent medium is sandwiched between the left and right circularly polarizing plates 3 and 4 orthogonal to each other is Because it does not depend on the angle between the axes of the polarizers 11 and 12 and the slow axis of the birefringent medium, the liquid crystal molecules are not inclined at 45 °, 135 °, 225 °, 315 °, If the inclination can be controlled, the desired transmittance can be secured. Therefore, for example, a circular protrusion may be disposed at the center of the pixel, and liquid crystal molecules may be inclined in all directions, or may be inclined in random directions without controlling the inclination direction at all. May be
  • the retardation (panel retardation) ⁇ n ⁇ d of the liquid crystal layer 33 represented by the product of ⁇ n and cell thickness (cell gap, ie, thickness of the liquid crystal layer 33) d of the liquid crystal material is not particularly limited. Usually, it is 200 to 500 nm, preferably 250 to 450 nm, and more preferably 300 to 400 nm.
  • FIG. 4 is a schematic cross-sectional view of the liquid crystal display device according to the multilayer structure 1-1 of the first embodiment.
  • the liquid crystal display device 1 of this embodiment does not include an optical compensation layer other than the first to third optical compensation layers 21 to 23 between the first polarizer 11 and the liquid crystal cell 30.
  • an optical compensation layer other than the fourth optical compensation layer 24 may not be provided between the liquid crystal cell 30 and the second polarizer 12.
  • the first optical compensation layer 21 has a thickness direction retardation Rth of -200 to -100 nm (more preferably -180 to -120 nm), and the second optical compensation layer 22 has an in-plane position.
  • the third optical compensation layer 23 has a phase difference Re of 60 to 110 nm (more preferably 70 to 100 nm) and satisfies 1 ⁇ Nz ⁇ 1.4 (more preferably 1 ⁇ Nz ⁇ 1.2).
  • the fourth optical compensation layer 24 satisfies 1.4 ⁇ Nz ⁇ 2.4 (more preferably 1.5 ⁇ Nz ⁇ 1.8), and 1.4 ⁇ Nz ⁇ 2.4 (more preferably 2 ⁇ ). It is preferable to satisfy Nz ⁇ 2.3).
  • the first polarizer 11 may be disposed adjacent to the first optical compensation layer 21, and the third optical compensation layer 23 and the fourth optical compensation layer 24 may be disposed in the liquid crystal cell 30.
  • the second polarizer 12 may be disposed adjacent to the fourth optical compensation layer 24.
  • FIG. 5 is a schematic cross-sectional view of the liquid crystal display device according to the multilayer structure 1-2 in the first embodiment.
  • FIG. 6 is a schematic perspective view of the liquid crystal display device according to the layered structure 1-2 of the first embodiment.
  • the liquid crystal display device 1 of the present embodiment further includes a fifth optical compensation layer 25 and a sixth optical compensation layer 26, and the first polarizer 11 and the first optical compensation.
  • the two polarizers 12 may be arranged in this order.
  • the fifth optical compensation layer 25 has an in-plane retardation Re of 40 to 120 nm and satisfies 1 ⁇ Nz ⁇ 4.
  • the fifth optical compensation layer 25 has the in-plane slow axis 25 a substantially parallel to the absorption axis 12 a of the second polarizer 12.
  • the sixth optical compensation layer 26 has an in-plane retardation Re of 15 nm or less and a thickness direction retardation Rth of -60 nm or less.
  • the laminated structure 1-1 it is possible to exhibit more excellent viewing angle characteristics than the laminated structure 1-1.
  • the laminated structure 1-1 is more preferable than the present laminated structure.
  • the material having high durability to the solvent can be selected as the material of the fifth to sixth optical compensation layers 25 to 26, the solvent is attached to the polarizing plates (circularly polarizing plates 3 and 4)
  • peeling of the first to sixth optical compensation layers 21 to 26 from the first or second polarizer 11 or 12 can be suppressed, and peeling and the first to sixth optical compensation layers 21 can be suppressed. It is possible to suppress the occurrence of breakage of ⁇ 26.
  • the first and sixth optical compensation layers 21 and 26 each have a thickness direction retardation Rth of ⁇ 150 to ⁇ 80 nm (more preferably ⁇ 120 to ⁇ 90 nm), and
  • the fifth optical compensation layers 22 and 25 each have an in-plane retardation Re of 40 to 90 nm (more preferably 40 to 60 nm), and 1 ⁇ Nz ⁇ 1.4 (more preferably 1 ⁇ Nz ⁇ ).
  • the third optical compensation layer 23 satisfies 1.4 ⁇ Nz ⁇ 2.4 (more preferably 1.5 ⁇ Nz ⁇ 1.8), and the fourth optical compensation layer 24 It is preferable to satisfy 1.4 ⁇ Nz ⁇ 2.4 (more preferably 2 ⁇ Nz ⁇ 2.3).
  • the fifth optical compensation layer 25 is preferably disposed adjacent to the sixth optical compensation layer 26, and the fourth optical compensation layer 24 is disposed adjacent to the fifth optical compensation layer 25.
  • the first polarizer 11 may be disposed adjacent to the first optical compensation layer 21, and the third optical compensation layer 23 and the fourth optical compensation layer 24 are disposed adjacent to the liquid crystal cell 30.
  • the second polarizer 12 may be disposed adjacent to the sixth optical compensation layer 26.
  • the in-plane slow axis 25 a is substantially parallel to the absorption axis 12 a of the second polarizer 12.
  • that the in-plane slow axis 25a is substantially parallel to the absorption axis 12a more specifically means that the angle between the two axes is in the range of 0 ⁇ 3 °, It is preferably in the range of 0 ⁇ 1 °, more preferably in the range of 0 ⁇ 0.5 °, and particularly preferably 0 ° (perfectly parallel).
  • the fifth optical compensation layer 25 satisfies 40 nm ⁇ Re ⁇ 120 nm and 1 ⁇ Nz ⁇ 4.
  • the in-plane retardation Re of the fifth optical compensation layer 25 can be appropriately set within the above range according to the optical parameters of the other members.
  • the sixth optical compensation layer 26 satisfies Re ⁇ 15 nm and Rth ⁇ ⁇ 60 nm.
  • the in-plane retardation Re of the sixth optical compensation layer 26 is preferably 0 to 10 nm, more preferably 0 to 5 nm, still more preferably 0 to 3 nm, and further preferably 0 to 1 nm. Is particularly preferred.
  • the thickness direction retardation Rth of the sixth optical compensation layer 26 can be appropriately set within the above range according to the optical parameters of the other members.
  • the sixth optical compensation layer 26 can be regarded as substantially optically isotropic in the plane when the in-plane retardation Re is sufficiently small, such as 15 nm or less, so the surface of the sixth optical compensation layer 26 is
  • the arrangement direction in the inside is not particularly limited.
  • Examples of materials and formation methods of the fifth to sixth optical compensation layers 25 to 26 include the same ones as those of the first to fourth optical compensation layers 21 to 24 described above.
  • the fifth optical compensation layer 25 one obtained by drawing a cycloolefin resin, one obtained by drawing a cellulose resin, particularly triacetyl cellulose, one obtained by drawing a (meth) acrylic resin, and It is preferable that the liquid crystal is aligned and parallel to the base material (substrate) and polymerized
  • the sixth optical compensation layer 26 one obtained by aligning and polymerizing the polymerizable liquid crystal parallel to the base material (substrate) It is suitable.
  • FIG. 7 is a schematic cross-sectional view of the liquid crystal display device according to the layered structure 1-3 of the first embodiment.
  • FIG. 8 is a schematic perspective view of the liquid crystal display device according to the layered structure 1-3 of the first embodiment.
  • the liquid crystal display device 1 of the present embodiment further includes a seventh optical compensation layer 27 and an eighth optical compensation layer 28, and the first polarizer 11, the first optical compensation.
  • the optical compensation layer 25, the sixth optical compensation layer 26, and the second polarizer 12 may be disposed in this order.
  • the seventh optical compensation layer 27 and the eighth optical compensation layer 28 each have an in-plane retardation Re of 15 nm or less, a thickness direction retardation Rth of 50 to 300 nm, and satisfy Nz> 1.
  • the laminated structure 1-1 compared to the laminated structure 1-1, it is possible to exhibit viewing angle characteristics with less omnidirectional bias.
  • the laminated structure 1-1 is more preferable than the present laminated structure.
  • the material having high durability to the solvent can be selected as the material of the seventh to eighth optical compensation layers 27 to 28, the solvent is attached to the polarizing plates (circularly polarizing plates 3 and 4)
  • peeling of the first to eighth optical compensation layers 21 to 28 from the first or second polarizer 11 or 12 can be suppressed, and peeling and the first to eighth optical compensation layers 21 can be suppressed. It is possible to suppress the occurrence of breakage of ⁇ 28.
  • the first and sixth optical compensation layers 21 and 26 each have a thickness direction retardation Rth of ⁇ 150 to ⁇ 80 nm (more preferably ⁇ 120 to ⁇ 90 nm), and
  • the fifth optical compensation layers 22 and 25 each have an in-plane retardation Re of 40 to 90 nm (more preferably 45 to 60 nm), and 1 ⁇ Nz ⁇ 1.4 (more preferably 1 ⁇ Nz ⁇ ). It is preferable to satisfy 1.2), and the third and fourth optical compensation layers 23 and 24 each satisfy 1 ⁇ Nz ⁇ 1.4 (more preferably 1 ⁇ Nz ⁇ 1.2).
  • the fifth optical compensation layer 25 is preferably disposed adjacent to the sixth optical compensation layer 26, and the fourth optical compensation layer 24 is disposed adjacent to the fifth optical compensation layer 25.
  • the seventh optical compensation layer 27 is preferably disposed adjacent to the third optical compensation layer 23, and the eighth optical compensation layer 28 is disposed adjacent to the fourth optical compensation layer 24. Is preferred.
  • the first polarizer 11 may be disposed adjacent to the first optical compensation layer 21, and the seventh and eighth optical compensation layers 27 and 28 may be disposed adjacent to the liquid crystal cell 30.
  • the second polarizer 12 may be disposed adjacent to the sixth optical compensation layer 26.
  • the seventh and eighth optical compensation layers 27 and 28 satisfy Re ⁇ 15 nm, 50 nm ⁇ Rth ⁇ 300 nm, and Nz> 1.
  • the in-plane retardation Re of each of the seventh and eighth optical compensation layers 27 and 28 is preferably 0 to 10 nm, more preferably 0 to 5 nm, and still more preferably 0 to 3 nm. Particularly preferred is 0 to 1 nm.
  • the thickness direction retardation Rth of the seventh and eighth optical compensation layers 27 and 28 can be appropriately set within the above range according to the optical parameters of the other members.
  • the seventh and eighth optical compensation layers 27 and 28 can be regarded as substantially optically isotropic in the plane when the in-plane retardation Re is sufficiently small, such as 15 nm or less.
  • the arrangement direction of the eight optical compensation layers 27 and 28 in the plane is not particularly limited.
  • the thickness direction retardations Rth of the seventh and eighth optical compensation layers 27 and 28 may be different from each other or may be the same, and in any case, the sum of the thickness direction retardations Rth of the both is the same. It can function as well.
  • the total of the thickness direction retardations Rth of the seventh and eighth optical compensation layers 27 and 28 is preferably 100 nm or more and 300 nm or less, and more preferably 150 nm or more and 250 nm or less.
  • Examples of materials and forming methods of the seventh to eighth optical compensation layers 27 to 28 include the same ones as those of the first to fourth optical compensation layers 21 to 24 described above. Among them, as the seventh to eighth optical compensation layers 27 to 28, those obtained by stretching a cycloolefin resin, and those obtained by stretching a cellulose resin, particularly triacetyl cellulose, and a (meth) acrylic resin are preferred.
  • each axial direction is represented by an angle when the right direction of the display area of the liquid crystal panel is 0 ° and the counterclockwise direction is positive when viewed from the viewing surface side. .
  • FIG. 9 is a schematic cross-sectional view of the liquid crystal display device according to the first embodiment.
  • a front polarizer a first optical compensation layer as a positive C plate, a second optical compensation layer as a positive A plate, a third optical compensation layer as a ⁇ / 4 retardation plate, A liquid crystal cell, a fourth optical compensation layer as a ⁇ / 4 retardation plate, a liquid crystal panel in which a back polarizer is disposed in this order from the observation surface side, and a backlight (not shown) of the liquid crystal panel
  • the optical parameters of the respective members and the axial directions of the respective polarizers and the respective optical compensation layers are as shown in FIG.
  • the front polarizer corresponds to the first polarizer
  • the back polarizer corresponds to the second polarizer.
  • the liquid crystal cell As the liquid crystal cell, a VA mode liquid crystal cell was used.
  • the dielectric anisotropy ⁇ n of the liquid crystal material is 0.113, and the cell thickness (cell gap) d is 3.2 ⁇ m. That is, the retardation ⁇ n ⁇ d of the liquid crystal layer was 360 nm.
  • the second to fourth optical compensation layers films in which predetermined optical parameters shown in FIG. 9 were obtained by biaxially stretching a COP film were used.
  • the first optical compensation layer a film having a predetermined optical parameter shown in FIG. 9 obtained by applying a liquid crystalline material on the second optical compensation layer was used.
  • the COP film used did not contain cycloolefin copolymer (COC).
  • a front polarizer and a back polarizer what laminated
  • the COP films of the front polarizer and the back polarizer were produced so as not to have optical anisotropy.
  • the front polarizer and the back polarizer were disposed such that the COP film was on the liquid crystal cell side and the TAC film was on the opposite side to the liquid crystal cell.
  • a PVA film of a front polarizer and a back polarizer what has a polarization performance by adding iodine after extending
  • a TAC film is widely used as a support body of a PVA film, adhere
  • a COP film is widely used as a broad-band retardation film or as a support of a PVA film, and has birefringence by stretching.
  • first and second optical compensation layers are disposed on the viewing surface side in the first embodiment, they may be disposed on the back surface side.
  • each polarizer and each optical compensation layer may be rotated while maintaining the relative angle of the axes, or may be moved in line symmetry.
  • FIG. 10 is a schematic cross-sectional view of a liquid crystal display device according to Comparative Example 1.
  • a ninth optical compensation layer as a positive B plate was used instead of the first and second optical compensation layers.
  • a liquid crystal display was produced.
  • the ninth optical compensation layer a film having predetermined optical parameters shown in FIG. 10 by stretching and relaxing the COP film was used.
  • Example 1 and Comparative Example 1 The dark room contrast of the liquid crystal display of Example 1 and Comparative Example 1 was measured.
  • the dark room contrast is obtained by measuring the luminance of white display and black display without external light, and dividing the white display luminance by the black display luminance. The higher the display device, the better. Furthermore, from the viewpoint of durability, it is preferable that the change in this numerical value be as small as possible when exposed to a severe environment such as high temperature.
  • Table 1 below shows dark room contrast at the center of the screen before and after aging for 12 hours at 85 ° C. for Example 1 and Comparative Example 1. Although there is not much difference with the value before the aging, the value in Comparative Example 1 is greatly reduced by the aging. On the other hand, in Example 1, the change was small and it was shown that the durability was improved.
  • the black display uniformity of the liquid crystal display devices of Example 1 and Comparative Example 1 was measured.
  • the black display uniformity is an index indicating the intensity of so-called unevenness of black display, which is obtained by dividing the minimum luminance by the maximum luminance by scanning the luminance of the display area when a black solid screen is displayed. As this value is closer to 100%, there is no luminance distribution, that is, the unevenness is weak, which is preferable as a display device. The lower the value, the stronger the unevenness and the lower the quality as a display device.
  • Table 2 below shows black display uniformity before and after aging for 12 hours at 85 ° C. for Example 1 and Comparative Example 1. Although there is not much difference with the value before the aging, the value in Comparative Example 1 is greatly reduced by the aging. On the other hand, in Example 1, the change was small and it was shown that the durability was improved.
  • FIGS. 11 and 12 show the simulation results (isocontrast ratio contour lines) of the viewing angle characteristics of the liquid crystal display according to Example 1 and Comparative Example 1, respectively.
  • portions where the contrast is 100 or 1000 are indicated by solid lines.
  • FIGS. 11 and 12 although the direction in which the viewing angle characteristics are excellent is different, it can be adjusted by, for example, the rotation of the axis of the polarizer. In consideration of that, it is shown that Example 1 has a viewing angle characteristic which is almost equal to or slightly superior to Comparative Example 1.
  • FIG. 13 is an iso-contrast ratio contour line of the liquid crystal display device according to the first reference example.
  • the reference example 1 has the same configuration as that of the example 1 except that the slow axis of the second optical compensation layer is disposed in a direction forming an angle of 90 ° with the absorption axis of the front polarizer.
  • the relative angle is 0 ° (or 180 °)
  • the viewing angle characteristics will be good, but as shown in FIG. 13, if the relative angle is 90 °, the viewing angle Properties are not suitable for practical use because of deterioration.
  • the angle X between the slow axis of the second optical compensation layer and the absorption axis of the front polarizer (first polarizer) is -5. It is preferable to set the range of ° ⁇ X ⁇ 5 °.
  • FIG. 14 is a schematic cross-sectional view of the liquid crystal display device according to the second embodiment.
  • a front polarizer a first optical compensation layer as a positive C plate, a second optical compensation layer as a positive A plate, a third optical compensation layer as a ⁇ / 4 retardation plate, Liquid crystal cell, fourth optical compensation layer as ⁇ / 4 retardation plate, fifth optical compensation layer as positive A plate, sixth optical compensation layer as positive C plate, and back polarizer
  • a liquid crystal display device of Example 2 provided with a liquid crystal panel arranged in this order from the side and a back light (not shown) on the back side of the liquid crystal panel was produced.
  • the optical parameters of the respective members and the axial directions of the respective polarizers and the respective optical compensation layers are as shown in FIG.
  • the front polarizer corresponds to the first polarizer
  • the back polarizer corresponds to the second polarizer.
  • the present embodiment is substantially the same as the first embodiment, but in the present embodiment, the viewing angle characteristics are further enhanced by similarly arranging the optical compensation layer on the viewing surface side and the back surface side. Can.
  • the liquid crystal cell As the liquid crystal cell, a VA mode liquid crystal cell was used.
  • the dielectric anisotropy ⁇ n of the liquid crystal material is 0.113, and the cell thickness (cell gap) d is 3.2 ⁇ m. That is, the retardation ⁇ n ⁇ d of the liquid crystal layer was 360 nm.
  • films in which predetermined optical parameters shown in FIG. 14 were obtained by biaxially stretching a COP film were used.
  • films obtained by applying the liquid crystalline material on the second and fifth optical compensation layers and using the predetermined optical parameters shown in FIG. 14 were used. .
  • a front polarizer and a back polarizer what laminated
  • the COP films of the front polarizer and the back polarizer were produced so as not to have optical anisotropy.
  • the front polarizer and the back polarizer were disposed such that the COP film was on the liquid crystal cell side and the TAC film was on the opposite side to the liquid crystal cell.
  • a PVA film of a front polarizer and a back polarizer what has a polarization performance by adding iodine after extending
  • first and second optical compensation layers are disposed on the viewing surface side in the second embodiment, they may be disposed on the back surface side.
  • each polarizer and each optical compensation layer may be rotated while maintaining the relative angle of the axes, or may be moved in line symmetry.
  • Example 2 and Comparative Example 1 The same thing as in the above ⁇ Comparison of Example 1 and Comparative Example 1> applies to Example 2 and Comparative Example 1.
  • Table 5 below shows black display uniformity before and after aging for 12 hours at 85 ° C. for Example 2 and Comparative Example 1.
  • Example 1 the change in dark room contrast and black display uniformity before and after aging is also smaller in Example 2 than in Comparative Example 1, indicating that the durability is excellent.
  • the change is larger than in the first embodiment, it is presumed that the layer structure is increased and the characteristic change is more likely to occur.
  • FIG. 15 shows the simulation results (isocontrast ratio contour lines) of the viewing angle characteristics of the liquid crystal display device according to the second embodiment.
  • the present embodiment is greatly improved as compared with the embodiment 1 and the comparative example 1, and it is possible to select the present embodiment depending on the requirement of the viewing angle characteristics. It is possible. However, with regard to the manufacturing cost, this embodiment is expected to be higher than the first embodiment.
  • FIG. 16 is a schematic cross-sectional view of the liquid crystal display device according to the third embodiment.
  • a front polarizer a first optical compensation layer as a positive C plate, a second optical compensation layer as a positive A plate, a third optical compensation layer as a ⁇ / 4 retardation plate, Seventh optical compensation layer as negative C plate, liquid crystal cell, eighth optical compensation layer as negative C plate, fourth optical compensation layer as ⁇ / 4 retardation plate, fifth as positive A plate
  • the viewing angle characteristics of the liquid crystal display device of Example 3 including the above were simulated.
  • the optical parameters of the respective members and the axial directions of the respective polarizers and the respective optical compensation layers are as shown in FIG.
  • the front polarizer corresponds to the first polarizer
  • the back polarizer corresponds to the second polarizer.
  • FIG. 17 shows the simulation results (isocontrast ratio contour lines) of the viewing angle characteristics of the liquid crystal display device according to the third embodiment.
  • the present embodiment has viewing angle characteristics with less omnidirectional bias as compared to Embodiment 1 and Comparative Example 1, and this embodiment can be used depending on the requirement of the viewing angle characteristics. It is also possible to choose However, with regard to the manufacturing cost, this embodiment is expected to be higher than the first embodiment.
  • One aspect of the present invention is a third polarizer functioning as a first polarizer (11), a first optical compensation layer (21), a second optical compensation layer (22), and a ⁇ / 4 retardation plate.
  • a fourth optical compensation layer (24) functioning as a four-retardation plate and a second polarizer (12) are provided in this order, and the first polarizer (11) has an absorption axis (11a)
  • the first optical compensation layer (21) has an in-plane retardation Re of 15 nm or less at an angle of substantially 90 ° to the absorption axis (12a) of the second polarizer (12).
  • the thickness direction retardation Rth is ⁇ 60 nm or less
  • the second optical compensation layer (22) has an in-plane retardation Re of 40 to 12 nm, satisfying 1 ⁇ Nz ⁇ 4, and the in-plane slow axis (22a) is substantially parallel to the absorption axis (11a) of the first polarizer (11), and the third In the optical compensation layer (23), the in-plane slow axis (23a) forms an angle of substantially 45 ° or 135 ° with the absorption axis (11a) of the first polarizer (11), and the liquid crystal
  • the cell (30) aligns liquid crystal molecules in the liquid crystal layer (33) substantially perpendicularly to the pair of substrates (31, 32) during black display
  • the fourth optical compensation layer ( 24) is a liquid crystal display in which the in-plane slow axis (24a) makes an angle of substantially 90 ° with the in-plane slow axis (23a) of the third optical compensation layer (23); It is also good.
  • Patent Document 3 may disclose a circularly polarizing plate using a positive C plate and a positive A plate
  • the slow axis of the positive A plate is a polarizer close to it. It is orthogonal to the absorption axis.
  • the first optical compensation layer (21) satisfying 1 ⁇ Nz ⁇ 4 has the in-plane slow axis (22a) of the first polarizer ( It is substantially parallel to the absorption axis (11a) of 11), and the design concept is different. The difference in the design concept makes it possible to reduce the number of used optical compensation layers in the liquid crystal display device (1).
  • the third and fourth optical compensation layers (23, 24) may each satisfy 1 ⁇ Nz ⁇ 2.4.
  • the liquid crystal display (1) includes an optical compensation layer other than the first to third optical compensation layers (21 to 23) between the first polarizer (11) and the liquid crystal cell (30).
  • an optical compensation layer other than the fourth optical compensation layer (24) may not be provided between the liquid crystal cell (30) and the second polarizer (12).
  • the first optical compensation layer (21) has a thickness direction retardation Rth of -200 to -100 nm
  • the second optical compensation layer (22) has an in-plane retardation Re of 60 to 110 nm.
  • 1 ⁇ Nz ⁇ 1.4 is satisfied
  • the third optical compensation layer (23) satisfies 1.4 ⁇ Nz ⁇ 2.4
  • the in-plane retardation Re is 40 to 120 nm, 1 ⁇ Nz ⁇ 4 is satisfied, and the in-plane slow axis (25a) substantially corresponds to the absorption axis (12a) of the second polarizer (12)
  • the first and sixth optical compensation layers (21, 26) each have a thickness direction retardation Rth of -150 to -80 nm, and the second and fifth optical compensation layers (22, 25) have The in-plane retardation Re is 40 to 90 nm, and 1 ⁇ Nz ⁇ 1.4, and the third optical compensation layer (23) satisfies 1.4 ⁇ Nz ⁇ 2.4, The fourth optical compensation layer (24) may satisfy 1.4 ⁇ Nz ⁇ 2.4.
  • the liquid crystal display device (1) can exhibit viewing angle characteristics with less omnidirectional bias.
  • the first and sixth optical compensation layers (21, 26) each have a thickness direction retardation Rth of -150 to -80 nm, and the second and fifth optical compensation layers (22, 25) have The in-plane retardation Re is 40 to 90 nm, and 1 ⁇ Nz ⁇ 1.4 is satisfied, and the third and fourth optical compensation layers (23, 24) are each 1 ⁇ Nz ⁇ 1. .4 may be satisfied.
  • the in-plane retardation Re of the third optical compensation layer (23) may be substantially the same as the in-plane retardation Re of the fourth optical compensation layer (24). Thereby, the liquid crystal display device (1) can maintain high contrast.
  • Each of the third and fourth optical compensation layers (23, 24) may have an in-plane retardation Re of 100 to 175 nm.
  • Liquid crystal display 2 Liquid crystal panel 2a: Display area 3: First circularly polarizing plate 4: Second circularly polarizing plate 11: First polarizer 11a: Absorption axis 12: Second polarizer 12a: Absorption Axis 21: first optical compensation layer 22: second optical compensation layer 22a: in-plane slow axis 23: third optical compensation layer ( ⁇ / 4 retardation plate) 23a: in-plane slow axis 24: fourth optical compensation layer ( ⁇ / 4 retardation plate) 24a: in-plane slow axis 25: fifth optical compensation layer 25a: in-plane slow axis 26: sixth optical compensation layer 27: seventh optical compensation layer 28: eighth optical compensation layer 30: liquid crystal cell 31, 32: substrate 33: liquid crystal layer

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Abstract

The present invention provides a liquid crystal display device that is capable of suppressing a deterioration in display quality under severe environmental conditions and suppressing the peeling and breaking of a solvent when the same is bonded to a polarization plate, and with which a thinner liquid crystal panel can be obtained. This liquid crystal display device comprises a first polarizer, a first optical compensation layer, a second optical compensation layer, a third optical compensation layer functioning as a λ/4 phase-difference plate, a liquid crystal cell, a fourth optical compensation layer functioning as a λ/4 phase-difference plate, and a second polarizer in this order. The first optical compensation layer is configured such that the in-plane phase difference Re is 15 nm or less and the phase difference Rth in a thickness direction is −60 nm or less. The second optical compensation layer is configured such that the in-plane phase difference Re is 40 to 120 nm, 1 ≤ Nz ≤ 4 is satisfied, and the in-plane slow axis is substantially parallel to the absorption axis of the first polarizer. The liquid crystal cell aligns liquid crystal molecules substantially vertical to a pair of substrate surfaces while displaying black.

Description

液晶表示装置Liquid crystal display
本発明は、液晶表示装置に関する。より詳しくは、一対の円偏光板を備える垂直配向モードの液晶表示装置に好適な液晶表示装置に関するものである。 The present invention relates to a liquid crystal display device. More specifically, the present invention relates to a liquid crystal display device suitable for a liquid crystal display device in a vertical alignment mode provided with a pair of circularly polarizing plates.
液晶表示装置は、薄型、軽量及び低消費電力といった特長を活かし、幅広い分野で用いられている。液晶表示装置は、通常、偏光板としての一対の直線偏光板と、一対の直線偏光板間に設けられた液晶セルとを備えており、垂直配向（ＶＡ）モードや水平配向モード等の種々の表示モードが開発されている。 Liquid crystal display devices are used in a wide range of fields, taking advantage of features such as thinness, lightness, and low power consumption. A liquid crystal display device generally includes a pair of linear polarizing plates as polarizing plates and a liquid crystal cell provided between the pair of linear polarizing plates, and various types such as vertical alignment (VA) mode and horizontal alignment mode. Display modes have been developed.
また、近年、偏光板として、一対の直線偏光板の代わりに一対の円偏光板を用いたＶＡモードの液晶表示装置が開発されている。円偏光板は、よく知られているように、典型的には直線偏光板とλ／４位相差板との組み合わせによって構成される。以下、一対の円偏光板を用いたＶＡモードの液晶表示装置を、ＶＡ円偏光パネルとも言う。しかしながら、ＶＡ円偏光パネルでは斜め視角でのコントラスト比が低く、充分な視野角特性が得られないという点で改善の余地があった。これに対して光学補償フィルムを用いた視野角特性の改良技術が種々提案されている。 Also, in recent years, a VA mode liquid crystal display device using a pair of circularly polarizing plates instead of a pair of linear polarizing plates as a polarizing plate has been developed. As well known, a circularly polarizing plate is typically constituted by a combination of a linear polarizing plate and a λ / 4 retardation plate. Hereinafter, a VA mode liquid crystal display device using a pair of circularly polarizing plates is also referred to as a VA circularly polarizing panel. However, the VA circularly polarizing panel has room for improvement in that the contrast ratio at an oblique viewing angle is low and a sufficient viewing angle characteristic can not be obtained. On the other hand, various techniques for improving the viewing angle characteristics using an optical compensation film have been proposed.
例えば、特許文献１には、様々な方向から見ても均質で高いコントラストを得ることができる液晶表示装置として、偏光子Ａ及び偏光子Ｂからなる一対の偏光子と、一対の偏光子の間に配置される垂直配向型の液晶セルとを備える液晶表示装置であって、液晶セルと偏光子Ａとの間及び液晶セルと偏光子Ｂとの間に下記式（１）で表されるＮｚの値が２．０を超える１／４λ位相差板をそれぞれ備え、１／４λ位相差板の面内遅相軸は近接する偏光子の透過軸と略４５°の位置関係にあり、偏光子Ａとそれに近接する１／４λ位相差板との間及び偏光子Ｂとそれに近接する１／４λ位相差板との間の少なくとも一方には、固有複屈折値が負である材料層からなり、かつその面内遅相軸が、近接する偏光子の吸収軸と略平行又は略直交の位置関係にある光学異方体を備える液晶表示装置が開示されている。
Ｎｚ＝（ｎｘ－ｎｚ）／（ｎｘ－ｎｙ）・・・（１） For example, in Patent Document 1, as a liquid crystal display device capable of obtaining uniform high contrast even when viewed from various directions, a pair of polarizers consisting of polarizer A and polarizer B and a pair of polarizers are disclosed. The liquid crystal display device is provided with a liquid crystal cell of the vertical alignment type disposed in the above, and Nz represented by the following formula (1) between the liquid crystal cell and the polarizer A and between the liquid crystal cell and the polarizer B: Retarders each having a value of more than 2.0, and the in-plane slow axis of the quarter-wave retarder has a positional relationship of approximately 45 ° with the transmission axis of the adjacent polarizer, At least one of A and the adjacent 1⁄4 λ retardation plate and / or between the polarizer B and the adjacent 1⁄4 λ retardation plate comprises a material layer having a negative intrinsic birefringence value, And the in-plane slow axis is in a positional relationship substantially parallel or nearly orthogonal to the absorption axis of the adjacent polarizer A liquid crystal display device comprising an optical anisotropic body is disclosed.
Nz = (nx-nz) / (nx-ny) (1)
また、特許文献２には、円偏光モードにおいて斜め方向の光漏れが抑制され、視野角が精度よく補償された液晶表示装置として、第１の偏光子と、λ／４板として機能する第１の光学補償層と、液晶セルと、λ／４板として機能する第２の光学補償層と、ｎｚ＞ｎｘ＞ｎｙの屈折率の関係を有する第３の光学補償層と、第２の偏光子とを、視認側からこの順に有し、液晶セルの位相差波長分散値（Ｒｅｃｅｌｌ［４５０］／Ｒｅｃｅｌｌ［５５０］）をαｃｅｌｌとし、第１の光学補償層及び第２の光学補償層の平均位相差波長分散値（Ｒｅλ／４［４５０］／Ｒｅλ／４［５５０］）をαλ／４としたときに、αλ／４／αｃｅｌｌが０．９５～１．０２である液晶パネルを有する液晶表示装置が開示されている。 Further, according to Patent Document 2, the first polarizer functions as a first polarizer and a λ / 4 plate as a liquid crystal display device in which light leakage in an oblique direction is suppressed in the circular polarization mode and a viewing angle is accurately compensated. , A liquid crystal cell, a second optical compensation layer functioning as a λ / 4 plate, a third optical compensation layer having a refractive index relationship of nz>nx> ny, and a second polarizer Of the first optical compensation layer and the second optical compensation layer, with the retardation wavelength dispersion value (Re cell [450] / Re cell [550]) of the liquid crystal cell as α cell. When the average retardation wavelength dispersion value (Re λ / 4 [450] / Re λ / 4 [550]) of the above is α λ / 4 , the α λ / 4 / α cell is 0.95 to 1.02. A liquid crystal display device having a liquid crystal panel is disclosed.
また、特許文献３には、視野角特性を改善することができ、かつ、コストの低減が可能な液晶表示素子として、液晶表示素子を構成する円偏光子構成体はその光学補償用に第１偏光板と第１位相差板との間に屈折率異方性がｎｘ≒ｎｙ＜ｎｚとなる１軸の第３位相差板及び第５位相差板と屈折率異方性がｎｘ＞ｎｙ≒ｎｚとなる１軸の第４位相差板とを備え、円検光子構成体はその光学補償用に第２偏光板と第２位相差板との間に屈折率異方性がｎｘ≒ｎｙ＜ｎｚとなる１軸の第６位相差板及び第８位相差板と屈折率異方性がｎｘ＞ｎｙ≒ｎｚとなる１軸の第７位相差板とを備え、可変リターダー構成体はその光学補償用に第１位相差板と第２位相差板との間に屈折率異方性がｎｘ≒ｎｙ＞ｎｚとなる第９位相差板を備えている液晶表示素子が開示されている。 Further, according to Patent Document 3, as a liquid crystal display element capable of improving the viewing angle characteristics and reducing the cost, the circular polarizer structure constituting the liquid crystal display element is the first for its optical compensation. Between the polarizing plate and the first retardation plate, uniaxial uniaxial third retardation plate and fifth retardation plate with refractive index anisotropy nx <ny <nz and refractive index anisotropy nx> ny ≒ The circular analyzer structure has an anisotropy of refractive index nx ny ny <between the second polarizing plate and the second retardation plate for optical compensation. The variable retarder structure includes the uniaxial sixth retardation plate and the eighth retardation plate with nz and the uniaxial seventh retardation plate with the refractive index anisotropy of nx> ny ≒ nz A liquid crystal display device comprising a ninth retardation plate having a refractive index anisotropy of nxnxny> nz between the first retardation plate and the second retardation plate for compensation It has been disclosed.
また、特許文献４には、液晶セルに対して広視野角補償を行うとともに、広帯域の円偏光を得ることができ、薄型化に寄与し、熱ムラを防止し、かつ、黒表示における光漏れを良好に防止し得る光学補償層付偏光板として、偏光子と、第１の光学補償層と、第２の光学補償層とが、この順序で積層され、第１の光学補償層が、液晶化合物から形成され、ｎｘ＞ｎｙ＝ｎｚの関係を有し、かつ、その面内位相差Ｒｅ１が１００～１７０ｎｍであり、第２の光学補償層が、ｎｘ＝ｎｙ＞ｎｚの関係を有し、かつ、その厚み方向の位相差Ｒｔｈ２が３０～４００ｎｍであり、偏光子の吸収軸と第１の光学補償層の遅相軸とのなす角度が「＋」又は「－」２５～６５°の範囲である光学補償層付偏光板が開示されている。 Further, in Patent Document 4, wide viewing angle compensation can be performed on a liquid crystal cell, and circularly polarized light of a wide band can be obtained, which contributes to thinning, prevents thermal unevenness, and leaks light in black display. The polarizer, the first optical compensation layer, and the second optical compensation layer are laminated in this order as a polarizing plate with an optical compensation layer that can prevent the liquid crystal layer well, and the first optical compensation layer is a liquid crystal It is formed of a compound, has a relationship of nx> ny = nz, and has an in-plane retardation Re 1 of 100 to 170 nm, and the second optical compensation layer has a relationship of nx = ny> nz. And, the retardation Rth 2 in the thickness direction is 30 to 400 nm, and the angle between the absorption axis of the polarizer and the slow axis of the first optical compensation layer is “+” or “−” 25 to 65 ° A polarizing plate with an optical compensation layer is disclosed.
また、特許文献５には、低コストかつ簡便に製造することができるとともに、広い視角範囲において高いコントスラト比を実現することができる液晶表示装置として、第一の偏光子、第一種の複屈折層、第一のλ／４板、液晶セル、第二のλ／４板、第二種の複屈折層、及び、第一の偏光子の吸収軸に対して吸収軸が直交する第二の偏光子をこの順に有する液晶表示装置であって、第一種の複屈折層は、Ｎｚ＞０．９を満たし、面内遅相軸が第一の偏光子の吸収軸に対して直交し、第一のλ／４板は、面内遅相軸が第一の偏光子の吸収軸に対して略４５°の角度をなし、液晶セルは、液晶セル中の液晶分子を基板面に垂直に配向させることで黒表示を行い、第二のλ／４板は、面内遅相軸が第一のλ／４板の面内遅相軸に対して直交し、二種の複屈折層は、Ｎｚ＜０．１を満たし、面内遅相軸が第二の偏光子の吸収軸と平行である液晶表示装置が開示されている。 In addition, in Patent Document 5, as a liquid crystal display device which can be manufactured at low cost and simply and which can realize a high contrast ratio in a wide viewing angle range, a first polarizer, a first birefringence, and the like are disclosed. Layer, first λ / 4 plate, liquid crystal cell, second λ / 4 plate, second birefringent layer, and second absorption axis orthogonal to absorption axis of first polarizer A liquid crystal display device having a polarizer in this order, wherein the first birefringent layer satisfies Nz> 0.9, and the in-plane slow axis is orthogonal to the absorption axis of the first polarizer, In the first λ / 4 plate, the in-plane slow axis forms an angle of about 45 ° with the absorption axis of the first polarizer, and the liquid crystal cell makes liquid crystal molecules in the liquid crystal cell perpendicular to the substrate surface The second λ / 4 plate has the in-plane slow axis orthogonal to the in-plane slow axis of the first λ / 4 plate by orientating to give a black display. Oriso satisfies Nz <0.1, the liquid crystal display device is disclosed an in-plane slow axis is parallel to the absorption axis of the second polarizer.
また、０．１≦Ｎｚ≦０．９を満たす位相差フィルムの製造方法として、特許文献６には、連続的に供給される長尺状の高分子フィルムの両端を保持しながら搬送し、高分子フィルムを搬送しつつ搬送方向に対して直交する横方向に延伸する位相差フィルムの製造方法であって、高分子フィルムが搬送方向に弛んだ状態で、高分子フィルムを横方向に延伸する位相差フィルムの製造方法が開示されている。 In addition, as a method for producing a retardation film satisfying 0.1 ≦ Nz ≦ 0.9, Patent Document 6 discloses that a long polymer film continuously supplied is conveyed while being held at both ends. A method for producing a retardation film, which transports a molecular film while stretching it in a transverse direction orthogonal to the transport direction, in which the polymer film is stretched in the transverse direction with the polymer film slackened in the transport direction. A method of making a retardation film is disclosed.
特開２００９－３７０４９号公報JP, 2009-37049, A 特開２０１１－１５８５２０号公報JP 2011-158520 A 特開２００６－３３７６７６号公報Japanese Patent Application Publication No. 2006-337676 特開２００８－４０４８７号公報JP 2008-40487 A 特開２０１０－２１１２３０号公報JP, 2010-211230, A 特許第５６０６３３０号公報Patent No. 5606330
しかしながら、近年、液晶表示装置における耐久性要求が高くなっており、光学補償層を用いたＶＡ円偏光パネルでは、下記のような点で改善の余地があった。
（１）低温、高温、高温高湿環境等の環境において光学補償層の特性変化が大きく、コントラスト低下や表示ムラ等の表示品位の低下が発生することがある。
（２）偏光板に溶剤が付着したときに光学補償層と偏光子との剥離や、光学補償層の破断を生じることがある。
（３）偏光板の厚みが大きくなり、モバイル用途に適さない。 However, in recent years, the demand for durability in liquid crystal display devices has been increased, and in the case of a VA circularly polarizing panel using an optical compensation layer, there is room for improvement in the following points.
(1) The characteristic change of the optical compensation layer is large in an environment such as a low temperature, a high temperature, a high temperature and high humidity environment, and a drop in display quality such as a drop in contrast or display unevenness may occur.
(2) When a solvent adheres to the polarizing plate, peeling of the optical compensation layer from the polarizer and breakage of the optical compensation layer may occur.
(3) The thickness of the polarizing plate becomes large and it is not suitable for mobile applications.
例えば、特許文献２の液晶表示装置では、ｎｚ＞ｎｘ＞ｎｙの屈折率の関係を有する第３の光学補償層が用いられるが、このような光学補償層は、視野角改善効果を得るために要求される光学パラメータが狭く、選択できる材料及び製法が限られる。更に、コスト及び生産タクトの観点から量産可能な材料を選択する場合、上記（１）～（３）のような課題の発生が避けられない。 For example, in the liquid crystal display device of Patent Document 2, a third optical compensation layer having a refractive index relationship of nz> nx> ny is used, but such an optical compensation layer has a viewing angle improving effect. The required optical parameters are narrow and the materials and processes that can be selected are limited. Furthermore, when materials that can be mass-produced are selected from the viewpoint of cost and production tact, the occurrence of the problems as described in (1) to (3) above can not be avoided.
また、特許文献３の液晶表示素子は、光学補償用に多くの位相差板を用いているが、光学補償層が多くなると、上記（３）のように、偏光板を含む液晶パネルの厚みが増加するとともに、製造コストが増加してしまう。 Moreover, although the liquid crystal display element of patent document 3 uses many retardation plates for optical compensation, when the number of optical compensation layers increases, the thickness of the liquid crystal panel containing a polarizing plate becomes like said (3). With the increase, the manufacturing cost will increase.
本発明は、上記現状に鑑みてなされたものであり、過酷な環境下に置かれても表示品位の低下を抑制でき、偏光板への溶剤付着時の剥離及び破断を抑制でき、かつ、液晶パネルの薄型化が可能な液晶表示装置を提供することを目的とするものである。 The present invention has been made in view of the above-mentioned present situation, and can suppress deterioration of display quality even under severe environment, can suppress peeling and breakage at the time of solvent adhesion to a polarizing plate, and liquid crystal An object of the present invention is to provide a liquid crystal display device capable of thinning a panel.
本発明者らは、過酷な環境下に置かれても表示品位の低下を抑制でき、偏光板への溶剤付着時の剥離及び破断を抑制でき、かつ、液晶パネルの薄型化が可能な液晶表示装置について種々検討したところ、光学補償層の組み合わせに着目した。そして、λ／４位相差板の液晶セルとは反対側に、面内位相差Ｒｅが１５ｎｍ以下であり、かつ、厚み方向位相差Ｒｔｈが－６０ｎｍ以下である第１の光学補償層と、面内位相差Ｒｅが４０～１２０ｎｍであり、かつ、１≦Ｎｚ≦４を満たす第２の光学補償層との２層を設け、第２の光学補償層の面内遅相軸を、液晶セルに対して第２の光学補償層と同じ側に設けられた第１の偏光子の吸収軸と実質的に平行とすることにより、過酷な環境下に置かれても特性変化が比較的小さい光学補償層を用いることができ、また、溶剤に対する偏光板の耐久性を向上でき、更に、光学補償層の数を削減可能であることを見いだし、上記課題をみごとに解決することができることに想到し、本発明に到達したものである。 The inventors of the present invention can suppress deterioration in display quality even under severe environments, can suppress peeling and breakage at the time of solvent adhesion to a polarizing plate, and can make a liquid crystal panel thinner. When various examinations were made about the device, attention was focused on the combination of the optical compensation layer. Then, on the opposite side to the liquid crystal cell of the λ / 4 retardation plate, the first optical compensation layer having an in-plane retardation Re of 15 nm or less and a thickness direction retardation Rth of −60 nm or less, and Two layers with a second optical compensation layer having an internal retardation Re of 40 to 120 nm and satisfying 1 ≦ Nz ≦ 4 are provided, and the in-plane slow axis of the second optical compensation layer is a liquid crystal cell. On the other hand, by making it substantially parallel to the absorption axis of the first polarizer provided on the same side as the second optical compensation layer, optical compensation with relatively small characteristic change even under severe environment It has been found that a layer can be used, the durability of the polarizing plate to a solvent can be improved, and furthermore, the number of optical compensation layers can be reduced, and it is possible to solve the above problems clearly. The present invention has been achieved.
本発明の一態様は、第１の偏光子と、第１の光学補償層と、第２の光学補償層と、λ／４位相差板として機能する第３の光学補償層と、互いに対向する一対の基板、及び、前記一対の基板間の液晶層を含む液晶セルと、λ／４位相差板として機能する第４の光学補償層と、第２の偏光子と、をこの順に備え、前記第１の偏光子は、吸収軸が前記第２の偏光子の吸収軸に対して実質的に９０°の角度をなし、前記第１の光学補償層は、面内位相差Ｒｅが１５ｎｍ以下であり、かつ、厚み方向位相差Ｒｔｈが－６０ｎｍ以下であり、前記第２の光学補償層は、面内位相差Ｒｅが４０～１２０ｎｍであり、１≦Ｎｚ≦４を満たし、かつ、面内遅相軸が前記第１の偏光子の吸収軸と実質的に平行であり、前記第３の光学補償層は、面内遅相軸が前記第１の偏光子の吸収軸に対して実質的に４５°又は１３５°の角度をなし、前記液晶セルは、黒表示時に、前記液晶層中の液晶分子を前記一対の基板面に対して実質的に垂直に配向し、前記第４の光学補償層は、面内遅相軸が前記第３の光学補償層の面内遅相軸に対して実質的に９０°の角度をなす液晶表示装置であってもよい。 In one aspect of the present invention, the first polarizer, the first optical compensation layer, the second optical compensation layer, and the third optical compensation layer functioning as a λ / 4 retardation plate are opposed to each other. A liquid crystal cell including a pair of substrates and a liquid crystal layer between the pair of substrates, a fourth optical compensation layer functioning as a λ / 4 retardation plate, and a second polarizer in this order; The first polarizer has an absorption axis at an angle of substantially 90 ° to the absorption axis of the second polarizer, and the first optical compensation layer has an in-plane retardation Re of 15 nm or less And the thickness direction retardation Rth is −60 nm or less, the second optical compensation layer has an in-plane retardation Re of 40 to 120 nm, satisfies 1 ≦ Nz ≦ 4, and an in-plane retardation The phase axis is substantially parallel to the absorption axis of the first polarizer, and the third optical compensation layer has an in-plane slow axis of the first The liquid crystal cell makes an angle of substantially 45 ° or 135 ° with respect to the absorption axis of the polarizer, and the liquid crystal cell displays liquid crystal molecules in the liquid crystal layer substantially perpendicular to the pair of substrate surfaces during black display. The fourth optical compensation layer is a liquid crystal display device in which the in-plane slow axis forms an angle of substantially 90 ° with the in-plane slow axis of the third optical compensation layer, It is also good.
前記第３及び第４の光学補償層は、各々、１≦Ｎｚ≦２．４を満たしてもよい。 The third and fourth optical compensation layers may each satisfy 1 ≦ Nz ≦ 2.4.
前記液晶表示装置は、前記第１の偏光子及び前記液晶セルの間に前記第１～第３の光学補償層以外の光学補償層を備えず、かつ、前記液晶セル及び前記第２の偏光子の間に前記第４の光学補償層以外の光学補償層を備えなくてもよい。 The liquid crystal display device does not include an optical compensation layer other than the first to third optical compensation layers between the first polarizer and the liquid crystal cell, and the liquid crystal cell and the second polarizer And the optical compensation layer other than the fourth optical compensation layer.
前記第１の光学補償層は、厚み方向位相差Ｒｔｈが－２００～－１００ｎｍであり、前記第２の光学補償層は、面内位相差Ｒｅが６０～１１０ｎｍであり、かつ、１≦Ｎｚ≦１．４を満たし、前記第３の光学補償層は、１．４≦Ｎｚ≦２．４を満たし、前記第４の光学補償層は、１．４≦Ｎｚ≦２．４を満たしてもよい。 The first optical compensation layer has a thickness direction retardation Rth of −200 to −100 nm, and the second optical compensation layer has an in-plane retardation Re of 60 to 110 nm, and 1 ≦ Nz ≦ And the third optical compensation layer may satisfy 1.4 ≦ Nz ≦ 2.4, and the fourth optical compensation layer may satisfy 1.4 ≦ Nz ≦ 2.4. .
前記液晶表示装置は、面内位相差Ｒｅが４０～１２０ｎｍであり、１≦Ｎｚ≦４を満たし、かつ、面内遅相軸が前記第２の偏光子の吸収軸と実質的に平行である第５の光学補償層と、面内位相差Ｒｅが１５ｎｍ以下であり、かつ、厚み方向位相差Ｒｔｈが－６０ｎｍ以下である第６の光学補償層とを更に備え、前記第１の偏光子、前記第１の光学補償層、前記第２の光学補償層、前記第３の光学補償層、前記液晶セル、前記第４の光学補償層、前記第５の光学補償層、前記第６の光学補償層、及び、前記第２の偏光子は、この順に配置されてもよい。 The liquid crystal display device has an in-plane retardation Re of 40 to 120 nm, satisfies 1 ≦ Nz ≦ 4, and an in-plane slow axis is substantially parallel to the absorption axis of the second polarizer. A fifth optical compensation layer, and a sixth optical compensation layer having an in-plane retardation Re of 15 nm or less and a thickness direction retardation Rth of -60 nm or less, the first polarizer, The first optical compensation layer, the second optical compensation layer, the third optical compensation layer, the liquid crystal cell, the fourth optical compensation layer, the fifth optical compensation layer, and the sixth optical compensation The layer and the second polarizer may be arranged in this order.
前記第１及び第６の光学補償層は、各々、厚み方向位相差Ｒｔｈが－１５０～－８０ｎｍであり、前記第２及び第５の光学補償層は、各々、面内位相差Ｒｅが４０～９０ｎｍであり、かつ、１≦Ｎｚ≦１．４を満たし、前記第３の光学補償層は、１．４≦Ｎｚ≦２．４を満たし、前記第４の光学補償層は、１．４≦Ｎｚ≦２．４を満たしてもよい。 The first and sixth optical compensation layers each have a thickness direction retardation Rth of -150 to -80 nm, and the second and fifth optical compensation layers each have an in-plane retardation Re of 40 to 90 nm and satisfy 1 ≦ Nz ≦ 1.4, the third optical compensation layer satisfies 1.4 ≦ Nz ≦ 2.4, and the fourth optical compensation layer satisfies 1.4 ≦ It may satisfy Nz ≦ 2.4.
前記第５の光学補償層は、実質的にＮｚ＝１を満たしてもよい。 The fifth optical compensation layer may substantially satisfy Nz = 1.
前記液晶表示装置は、面内位相差Ｒｅが１５ｎｍ以下であり、厚み方向位相差Ｒｔｈが５０～３００ｎｍであり、かつ、Ｎｚ＞１を満たす第７の光学補償層と、面内位相差Ｒｅが１５ｎｍ以下であり、厚み方向位相差Ｒｔｈが５０～３００ｎｍであり、かつ、Ｎｚ＞１を満たす第８の光学補償層とを更に備え、前記第１の偏光子、前記第１の光学補償層、前記第２の光学補償層、前記第３の光学補償層、前記第７の光学補償層、前記液晶セル、前記第８の光学補償層、前記第４の光学補償層、前記第５の光学補償層、前記第６の光学補償層、及び、前記第２の偏光子は、この順に配置されてもよい。 The liquid crystal display device has a seventh optical compensation layer having an in-plane retardation Re of 15 nm or less, a thickness direction retardation Rth of 50 to 300 nm, and Nz> 1, and an in-plane retardation Re of And an eighth optical compensation layer having a thickness direction retardation Rth of 50 to 300 nm and Nz> 1 and having a thickness of 15 nm or less, the first polarizer, the first optical compensation layer, The second optical compensation layer, the third optical compensation layer, the seventh optical compensation layer, the liquid crystal cell, the eighth optical compensation layer, the fourth optical compensation layer, the fifth optical compensation The layer, the sixth optical compensation layer, and the second polarizer may be arranged in this order.
前記第１及び第６の光学補償層は、各々、厚み方向位相差Ｒｔｈが－１５０～－８０ｎｍであり、前記第２及び第５の光学補償層は、各々、面内位相差Ｒｅが４０～９０ｎｍであり、かつ、１≦Ｎｚ≦１．４を満たし、前記第３及び第４の光学補償層は、各々、１≦Ｎｚ≦１．４を満たしてもよい。 The first and sixth optical compensation layers each have a thickness direction retardation Rth of -150 to -80 nm, and the second and fifth optical compensation layers each have an in-plane retardation Re of 40 to The third and fourth optical compensation layers may be 90 nm and satisfy 1 ≦ Nz ≦ 1.4, and each of the third and fourth optical compensation layers may satisfy 1 ≦ Nz ≦ 1.4.
前記第２の光学補償層は、実質的にＮｚ＝１を満たしてもよい。 The second optical compensation layer may substantially satisfy Nz = 1.
前記第３の光学補償層の面内位相差Ｒｅは、前記第４の光学補償層の面内位相差Ｒｅと実質的に同じであってもよい。 The in-plane retardation Re of the third optical compensation layer may be substantially the same as the in-plane retardation Re of the fourth optical compensation layer.
前記第３及び第４の光学補償層は、各々、面内位相差Ｒｅが１００～１７５ｎｍであってもよい。 Each of the third and fourth optical compensation layers may have an in-plane retardation Re of 100 to 175 nm.
以上に示した本発明の各態様は、本発明の要旨を逸脱しない範囲において適宜組み合わされてもよい。 Each aspect of the present invention shown above may be combined suitably in the range which does not deviate from the gist of the present invention.
本発明によれば、過酷な環境下に置かれても表示品位の低下を抑制でき、偏光板への溶剤付着時の剥離及び破断を抑制でき、かつ、液晶パネルの薄型化が可能な液晶表示装置を実現することができる。 According to the present invention, it is possible to suppress deterioration in display quality even when placed under a severe environment, to suppress peeling and breakage at the time of solvent adhesion to a polarizing plate, and to reduce the thickness of the liquid crystal panel. The device can be realized.
実施形態１に係る液晶表示装置の平面模式図である。FIG. 1 is a schematic plan view of a liquid crystal display device according to Embodiment 1. 実施形態１に係る液晶表示装置の断面模式図である。FIG. 1 is a schematic cross-sectional view of a liquid crystal display device according to Embodiment 1. 実施形態１に係る液晶表示装置の斜視模式図である。FIG. 1 is a schematic perspective view of a liquid crystal display device according to Embodiment 1. 実施形態１の積層構造１－１に係る液晶表示装置の断面模式図である。FIG. 1 is a schematic cross-sectional view of a liquid crystal display device according to a lamination structure 1-1 of Embodiment 1. 実施形態１の積層構造１－２に係る液晶表示装置の断面模式図である。FIG. 1 is a schematic cross-sectional view of a liquid crystal display device according to laminated structure 1-2 in embodiment 1. 実施形態１の積層構造１－２に係る液晶表示装置の斜視模式図である。FIG. 1 is a schematic perspective view of a liquid crystal display device according to a laminated structure 1-2 of Embodiment 1. 実施形態１の積層構造１－３に係る液晶表示装置の断面模式図である。FIG. 1 is a schematic cross-sectional view of a liquid crystal display device according to laminated structure 1-3 of embodiment 1. 実施形態１の積層構造１－３に係る液晶表示装置の斜視模式図である。FIG. 1 is a schematic perspective view of a liquid crystal display device according to laminated structure 1-3 of embodiment 1. 実施例１に係る液晶表示装置の断面模式図である。FIG. 1 is a schematic cross-sectional view of a liquid crystal display device according to Example 1. 比較例１に係る液晶表示装置の断面模式図である。FIG. 5 is a schematic cross-sectional view of a liquid crystal display device according to Comparative Example 1; 実施例１に係る液晶表示装置の等コントラスト比等高線である。FIG. 7 is an iso-contrast ratio contour line of the liquid crystal display device according to Example 1. FIG. 比較例１に係る液晶表示装置の等コントラスト比等高線である。It is an iso-contrast ratio contour line of the liquid crystal display device which concerns on the comparative example 1. FIG. 参考例１に係る液晶表示装置の等コントラスト比等高線である。It is an iso-contrast ratio contour line of the liquid crystal display device which concerns on the reference example 1. FIG. 実施例２に係る液晶表示装置の断面模式図である。FIG. 6 is a schematic cross-sectional view of a liquid crystal display device according to Example 2. 実施例２に係る液晶表示装置の等コントラスト比等高線である。FIG. 10 is an iso-contrast ratio contour line of the liquid crystal display device according to Example 2. FIG. 実施例３に係る液晶表示装置の断面模式図である。FIG. 7 is a schematic cross-sectional view of a liquid crystal display device according to Example 3. 実施例３に係る液晶表示装置の等コントラスト比等高線である。FIG. 16 is an iso-contrast ratio contour line of the liquid crystal display device according to Example 3. FIG.
以下、本発明の実施形態について説明する。本発明は、以下の実施形態に記載された内容に限定されるものではなく、本発明の構成を充足する範囲内で、適宜設計変更を行うことが可能である。 Hereinafter, embodiments of the present invention will be described. The present invention is not limited to the contents described in the following embodiments, and design changes can be made as appropriate as long as the configuration of the present invention is satisfied.
＜用語および記号の定義＞
本明細書における用語及び記号の定義は下記の通りである。
（１）屈折率（ｎｘ、ｎｙ、ｎｚ）
「ｎｘ」は、面内の屈折率が最大になる方向（すなわち、遅相軸方向）の屈折率であり、「ｎｙ」は、面内で遅相軸と直交する方向の屈折率であり、「ｎｚ」は、厚み方向の屈折率である。
（２）面内位相差（Ｒｅ）
面内位相差（Ｒｅ）は、２３℃、特に明記しなければ波長５５０ｎｍにおける層（フィルム）の面内位相差値を言う。Ｒｅは、層（フィルム）の厚みをｄ（ｎｍ）としたとき、Ｒｅ＝（ｎｘ－ｎｙ）×ｄによって求められる。
（３）厚み方向の位相差（Ｒｔｈ）
厚み方向の位相差（Ｒｔｈ）は、２３℃、特に明記しなければ波長５５０ｎｍにおける層（フィルム）の厚み方向の位相差値を言う。Ｒｔｈは、層（フィルム）の厚みをｄ（ｎｍ）としたとき、Ｒｔｈ＝｛（ｎｘ＋ｎｙ）／２－ｎｚ｝×ｄによって求められる。
（４）Ｎｚ係数
Ｎｚ係数は、Ｎｚ＝（ｎｘ－ｎｚ）／（ｎｘ－ｎｙ）によって求められる。
（５）光学補償層
光学補償層は、２３℃、特に明記しなければ波長５５０ｎｍの光に対して、１５ｎｍ以上の面内位相差Ｒｅと、＋５５ｎｍ以上又は－１５ｎｍ以下の厚み方向の位相差Ｒｔｈとの少なくとも一方を付与する層を言い、その機能及び光学的性能は、特に限定されない。すなわち、光学補償層とは、１５ｎｍ≦Ｒｅ、かつ、Ｒｔｈ≦－１５ｎｍ又は＋５５ｎｍ≦Ｒｔｈを満たす層を言う。
（６）観察面側及び背面側
観察面側は、液晶表示装置の画面（表示面）に対してより近い側を意味し、背面側は、液晶表示装置の画面（表示面）に対してより遠い側を意味する。
（７）隣接配置
ある部材（例えば光学補償層）に他の部材（例えば光学補償層）が隣接配置されるとは、両部材の間に光学補償層が設けられないことを意味し、例えば、両部材の間に光学異方性を持たない層が配置された形態は含まれる。なお、光学異方性を持たない層とは、Ｒｅ＜１５ｎｍ、かつ、－１５ｎｍ＜Ｒｔｈ＜＋５５ｎｍを満たす層を言う。 <Definition of terms and symbols>
The definitions of terms and symbols in the present specification are as follows.
(1) Refractive index (nx, ny, nz)
“Nx” is the refractive index in the direction in which the in-plane refractive index is maximum (ie, the slow axis direction), and “ny” is the refractive index in the in-plane direction orthogonal to the slow axis "Nz" is the refractive index in the thickness direction.
(2) In-plane retardation (Re)
The in-plane retardation (Re) refers to the in-plane retardation value of a layer (film) at a wavelength of 550 nm at 23 ° C., unless otherwise specified. Re is obtained by Re = (nx−ny) × d, where d (nm) is the thickness of the layer (film).
(3) Retardation in the thickness direction (Rth)
The thickness direction retardation (Rth) refers to the thickness direction retardation value of a layer (film) at a wavelength of 550 nm unless otherwise specified. Rth is determined by Rth = {(nx + ny) / 2−nz} × d, where d (nm) is the thickness of the layer (film).
(4) Nz Coefficient The Nz coefficient is obtained by Nz = (nx−nz) / (nx−ny).
(5) Optical compensation layer The optical compensation layer has an in-plane retardation Re of 15 nm or more and a retardation Rth in the thickness direction of +55 nm or more or -15 nm or less for light of wavelength 550 nm unless otherwise specified. And the function and optical performance thereof are not particularly limited. That is, the optical compensation layer is a layer satisfying 15 nm ≦ Re and Rth ≦ −15 nm or +55 nm ≦ Rth.
(6) The viewing surface side and the rear surface viewing surface side mean the side closer to the screen (display surface) of the liquid crystal display device, and the rear surface side is more about the screen (display surface) of the liquid crystal display device It means the far side.
(7) Adjacent Arrangement A member (for example, an optical compensation layer) adjacent to another member (for example, an optical compensation layer) means that an optical compensation layer is not provided between both members, for example, A form in which a layer having no optical anisotropy is disposed between the two members is included. Here, the layer having no optical anisotropy means a layer satisfying Re <15 nm and −15 nm <Rth <+55 nm.
＜実施形態１＞
図１は、実施形態１に係る液晶表示装置の平面模式図である。図２は、実施形態１に係る液晶表示装置の断面模式図である。
図１に示すように、本実施形態に係る液晶表示装置１は、液晶パネル２を備えており、液晶パネル２は、その形状に対応した表示領域２ａを有している。表示領域２ａには複数の画素（図示せず）がマトリクス状に配列されており、表示領域２ａにて画像が表示される。 First Embodiment
FIG. 1 is a schematic plan view of the liquid crystal display device according to the first embodiment. FIG. 2 is a schematic cross-sectional view of the liquid crystal display device according to the first embodiment.
As shown in FIG. 1, the liquid crystal display device 1 according to the present embodiment includes a liquid crystal panel 2, and the liquid crystal panel 2 has a display area 2 a corresponding to the shape. A plurality of pixels (not shown) are arranged in a matrix in the display area 2a, and an image is displayed in the display area 2a.
液晶表示装置１は、透過型又は半透過型の液晶表示装置であり、図２に示すように、液晶パネル２と、液晶パネル２の背面側に配置されたバックライト（図示せず）とを備え、液晶パネル２は、第１の偏光子１１と、第１の光学補償層２１と、第２の光学補償層２２と、λ／４位相差板として機能する第３の光学補償層２３と、液晶セル３０と、λ／４位相差板として機能する第４の光学補償層２４と、第２の偏光子１２とをこの順に備えている。このように、第１の偏光子１１、第１の光学補償層２１、第２の光学補償層２２及び第３の光学補償層２３を含む第１の円偏光板３と、第４の光学補償層２４及び第２の偏光子１２を含む第２の円偏光板４とが液晶パネル２の両側にそれぞれ設けられている。また、液晶セル３０は、互いに対向する一対の基板３１及び３２と、一対の基板３１及び３２間の液晶層３３とを含んでいる。 The liquid crystal display device 1 is a transmissive or semi-transmissive liquid crystal display device, and includes a liquid crystal panel 2 and a backlight (not shown) disposed on the back side of the liquid crystal panel 2 as shown in FIG. The liquid crystal panel 2 includes a first polarizer 11, a first optical compensation layer 21, a second optical compensation layer 22, and a third optical compensation layer 23 functioning as a λ / 4 retardation plate. A liquid crystal cell 30, a fourth optical compensation layer 24 functioning as a λ / 4 retardation plate, and a second polarizer 12 are provided in this order. Thus, the first circularly polarizing plate 3 including the first polarizer 11, the first optical compensation layer 21, the second optical compensation layer 22, and the third optical compensation layer 23, and the fourth optical compensation A second circularly polarizing plate 4 including a layer 24 and a second polarizer 12 is provided on both sides of the liquid crystal panel 2. The liquid crystal cell 30 also includes a pair of substrates 31 and 32 facing each other, and a liquid crystal layer 33 between the pair of substrates 31 and 32.
図３は、実施形態１に係る液晶表示装置の斜視模式図である。
図３に示すように、第１の偏光子１１は、吸収軸１１ａが第２の偏光子１２の吸収軸１２ａに対して実質的に９０°の角度をなし、第２の光学補償層２２は、面内遅相軸２２ａが第１の偏光子１１の吸収軸１１ａと実質的に平行であり、第３の光学補償層２３は、面内遅相軸２３ａが第１の偏光子１１の吸収軸１１ａに対して実質的に４５°又は１３５°の角度をなし、第４の光学補償層２４は、面内遅相軸２４ａが第３の光学補償層２３の面内遅相軸２３ａに対して実質的に９０°の角度をなしている。また、液晶セル３０は、黒表示時に、液晶層３３中の液晶分子を一対の基板３１及び３２面に対して実質的に垂直に配向させている。 FIG. 3 is a schematic perspective view of the liquid crystal display device according to the first embodiment.
As shown in FIG. 3, in the first polarizer 11, the absorption axis 11a forms an angle of substantially 90 ° with the absorption axis 12a of the second polarizer 12, and the second optical compensation layer 22 The in-plane slow axis 22 a is substantially parallel to the absorption axis 11 a of the first polarizer 11, and the third optical compensation layer 23 has an in-plane slow axis 23 a of the absorption of the first polarizer 11. The fourth optical compensation layer 24 has an in-plane slow axis 24 a relative to the in-plane slow axis 23 a of the third optical compensation layer 23 at an angle of substantially 45 ° or 135 ° with respect to the axis 11 a. The angle is substantially 90 degrees. The liquid crystal cell 30 aligns liquid crystal molecules in the liquid crystal layer 33 substantially perpendicularly to the pair of substrates 31 and 32 in black display.
そして、第１の光学補償層２１は、面内位相差Ｒｅが１５ｎｍ以下であり、かつ、厚み方向位相差Ｒｔｈが－６０ｎｍ以下であり、第２の光学補償層２２は、面内位相差Ｒｅが４０～１２０ｎｍであり、かつ、１≦Ｎｚ≦４を満たしている。 The first optical compensation layer 21 has an in-plane retardation Re of 15 nm or less, and a thickness direction retardation Rth of −60 nm or less, and the second optical compensation layer 22 has an in-plane retardation Re of Is 40 to 120 nm, and 1 ≦ Nz ≦ 4 is satisfied.
このような構成を有する液晶表示装置１によれば、第１～第４の光学補償層２１～２４は、それらの材料の選択肢が比較的多いことから、第１～第４の光学補償層２１～２４として、低温、高温、高温高湿環境等の過酷な環境下に置かれても光学パラメータ等の特性変化が比較的小さい光学補償層を用いることができる。したがって、液晶表示装置１を低温、高温、高温高湿環境等の過酷な環境下に放置した後であっても、その表示品位（例えば、コントラスト、表示ムラ）が低下することを抑制できる。また、液晶表示装置１によれば、第１～第４の光学補償層２１～２４の材料として、溶剤に対する耐久性が高い材料を選択できることから、偏光板（円偏光板３及び４）へ溶剤が付着したとしても、第１～第４の光学補償層２１～２４が第１又は第２の偏光子１１又は１２から剥離することを抑制できるとともに、第１～第４の光学補償層２１～２４の破断の発生を抑制することができる。更に、液晶表示装置１によれば、光学補償層の数を最小４枚（第１～第４の光学補償層２１～２４）まで削減できることから、生産性を向上（すなわち製造コストを削減）しつつ、液晶表示装置１全体の厚みを薄くすることができる。 According to the liquid crystal display device 1 having such a configuration, the first to fourth optical compensation layers 21 to 24 have relatively many options for their materials. As the optical compensation layer 24 to 24, it is possible to use an optical compensation layer having a relatively small change in characteristics such as optical parameters even under severe environments such as low temperature, high temperature, high temperature and high humidity environment. Therefore, even after the liquid crystal display device 1 is left in a severe environment such as a low temperature, a high temperature, a high temperature and high humidity environment, it is possible to suppress a decrease in display quality (for example, contrast, display unevenness). Further, according to the liquid crystal display device 1, a material having high durability to a solvent can be selected as the material of the first to fourth optical compensation layers 21 to 24, so that the solvent to the polarizing plate (circularly polarizing plates 3 and 4) Of the first to fourth optical compensation layers 21 to 24 can be suppressed from peeling from the first or second polarizer 11 or 12 and the first to fourth optical compensation layers 21 to 24 The occurrence of 24 fractures can be suppressed. Furthermore, according to the liquid crystal display device 1, the number of optical compensation layers can be reduced to a minimum of four (first to fourth optical compensation layers 21 to 24), thereby improving productivity (that is, reducing manufacturing costs). At the same time, the overall thickness of the liquid crystal display device 1 can be reduced.
液晶表示装置１は、後述するように第１～第４の光学補償層２１～２４の他に、光学補償層を更に備えることができるが、第２の光学補償層２２は、第１の光学補償層２１に隣接配置されることが好ましく、第３の光学補償層２３は、第２の光学補償層２２に隣接配置されることが好ましい。 The liquid crystal display device 1 can further include an optical compensation layer in addition to the first to fourth optical compensation layers 21 to 24 as described later, but the second optical compensation layer 22 is a first optical The third optical compensation layer 23 is preferably disposed adjacent to the second optical compensation layer 22.
なお、液晶パネル２の表裏は特に限定されず、第１の偏光子１１及び第２の偏光子１２がそれぞれ観察面側及び背面側となるように各部材が配置されてもよいし、反対に、第２の偏光子１２及び第１の偏光子１１がそれぞれ観察面側及び背面側となるように各部材が配置されてもよい。 The front and back of the liquid crystal panel 2 is not particularly limited, and each member may be disposed such that the first polarizer 11 and the second polarizer 12 are on the viewing surface side and the back surface, respectively. The respective members may be arranged such that the second polarizer 12 and the first polarizer 11 are on the viewing surface side and the back surface side, respectively.
液晶表示装置１は、電圧無印加時に黒表示を行うノーマリブラックモードの液晶表示装置であり、コントラストの観点から、偏光子１１及び１２は、クロスニコルに配置されており、上述のように第１の偏光子１１は、吸収軸１１ａが第２の偏光子１２の吸収軸１２ａに対して実質的に９０°の角度をなしている。ここで、吸収軸１１ａが吸収軸１２ａに対して実質的に９０°の角度をなすとは、より具体的には、２つの軸のなす角度（絶対値）が９０±２°の範囲内であることを意味し、好ましくは９０±０．６°の範囲内であり、特に好ましくは９０°（完全に直交）である。 The liquid crystal display device 1 is a normally black mode liquid crystal display device which performs black display when no voltage is applied. From the viewpoint of contrast, the polarizers 11 and 12 are arranged in crossed nicols, and as described above One polarizer 11 has an absorption axis 11 a substantially at an angle of 90 ° with respect to the absorption axis 12 a of the second polarizer 12. Here, the fact that the absorption axis 11a forms an angle of substantially 90 ° with respect to the absorption axis 12a means that, more specifically, the angle (absolute value) between the two axes is within a range of 90 ± 2 °. This is preferably within the range of 90 ± 0.6 °, and particularly preferably 90 ° (perfectly orthogonal).
第２の光学補償層２２は、上述のように、面内遅相軸２２ａが第１の偏光子１１の吸収軸１１ａと実質的に平行である。ここで、面内遅相軸２２ａが吸収軸１１ａと実質的に平行であるとは、より具体的には、２つの軸のなす角度ｘが－５°＜ｘ＜５°を満たすことを意味し、好ましくは－３°≦ｘ≦３°を満たし、より好ましくは－１°≦ｘ≦１°を満たし、更に好ましくは－０．５°≦ｘ≦０．５°を満たし、特に好ましくはｘ＝０°（完全に平行）である。角度ｘがｘ≦－５°又は５°≦ｘを満たすと、法線コントラスト及び視野角特性が悪化するおそれがある。 As described above, in the second optical compensation layer 22, the in-plane slow axis 22 a is substantially parallel to the absorption axis 11 a of the first polarizer 11. Here, that the in-plane slow axis 22a is substantially parallel to the absorption axis 11a more specifically means that the angle x between the two axes satisfies -5 ° <x <5 °. Preferably satisfies -3 ° ≦ x ≦ 3 °, more preferably satisfies −1 ° ≦ x ≦ 1 °, still more preferably satisfies −0.5 ° ≦ x ≦ 0.5 °, particularly preferably x = 0 (perfectly parallel). If the angle x satisfies x ≦ −5 ° or 5 ° ≦ x, the normal contrast and the viewing angle characteristics may be degraded.
第３の光学補償層２３は、上述のように、面内遅相軸２３ａが第１の偏光子１１の吸収軸１１ａに対して実質的に４５°又は１３５°の角度をなしている。ここで、面内遅相軸２３ａが吸収軸１１ａに対して実質的に４５°又は１３５°の角度をなすとは、２つの軸のなす角度（絶対値）が４５±５°又は１３５±５°の範囲内であることを意味し、好ましくは４５±２°又は１３５±２°の範囲内であり、より好ましくは４５±０．６°又は１３５±０．６°の範囲内であり、特に好ましくは４５°又は１３５°（完全に４５°又は１３５°）である。 As described above, in the third optical compensation layer 23, the in-plane slow axis 23a forms an angle of substantially 45 ° or 135 ° with the absorption axis 11a of the first polarizer 11. Here, that the in-plane slow axis 23a makes an angle of substantially 45 ° or 135 ° with the absorption axis 11a means that the angle (absolute value) between the two axes is 45 ± 5 ° or 135 ± 5. Meaning within the range of 45 °, preferably within the range of 45 ± 2 ° or 135 ± 2 °, more preferably within the range of 45 ± 0.6 ° or 135 ± 0.6 °, Particularly preferred is 45 ° or 135 ° (completely 45 ° or 135 °).
第４の光学補償層２４は、上述のように、面内遅相軸２４ａが第３の光学補償層２３の面内遅相軸２３ａに対して実質的に９０°の角度をなしている。ここで、面内遅相軸２４ａが面内遅相軸２３ａに対して実質的に９０°の角度をなすとは、より具体的には、２つの軸のなす角度（絶対値）が９０±２°の範囲内であることを意味し、好ましくは９０±０．６°の範囲内であり、特に好ましくは９０°（完全に直交）である。
以下、各構成について更に説明する。 As described above, in the fourth optical compensation layer 24, the in-plane slow axis 24a forms an angle of substantially 90 ° with the in-plane slow axis 23a of the third optical compensation layer 23. Here, the fact that the in-plane slow axis 24a forms an angle of substantially 90 ° with the in-plane slow axis 23a means that the angle (absolute value) between the two axes is 90 ±, more specifically. It means within the range of 2 °, preferably within the range of 90 ± 0.6 °, and particularly preferably 90 ° (completely orthogonal).
Each configuration will be further described below.
＜偏光子＞
第１の偏光子１１及び第２の偏光子１２としては、目的に応じて任意の適切な偏光子が採用され得る。例えば、ポリビニルアルコール系フィルム（以下、ＰＶＡフィルムとも言う。）、部分ホルマール化ポリビニルアルコール系フィルム、エチレン・酢酸ビニル共重合体系部分ケン化フィルム等の親水性ポリマーフィルムに、ヨウ素や二色性染料等の二色性物質（二色性色素）を吸着させて一軸延伸したもの、ポリビニルアルコールの脱水処理物やポリ塩化ビニルの脱塩酸処理物等ポリエン系配向フィルム等が挙げられる。これらのなかでも、ポリビニルアルコール系フィルムにヨウ素等の二色性物質（二色性色素）を吸着させて一軸延伸した偏光子が、偏光二色比が高く特に好ましい。これら偏光子の厚さは特に制限されないが、一般的に、５～３０μｍ程度である。 <Polarizer>
Any appropriate polarizer may be employed as the first polarizer 11 and the second polarizer 12 depending on the purpose. For example, a hydrophilic polymer film such as a polyvinyl alcohol-based film (hereinafter, also referred to as a PVA film), a partially formalized polyvinyl alcohol-based film, or an ethylene / vinyl acetate copolymer-based partially saponified film A film obtained by adsorbing a dichromatic substance (dichroic dye) of the above and uniaxially stretched, a dehydrated product of polyvinyl alcohol, a dehydrochlorinated product of polyvinyl chloride, and the like, and a polyene-based oriented film and the like. Among these, a polarizer obtained by adsorbing a dichroic substance (dichroic dye) such as iodine to a polyvinyl alcohol-based film and uniaxially stretching it is particularly preferable because the polarization dichroic ratio is high. The thickness of these polarizers is not particularly limited, but in general, it is about 5 to 30 μm.
ポリビニルアルコール系フィルムにヨウ素を吸着させて一軸延伸した偏光子は、例えば、ポリビニルアルコールをヨウ素の水溶液に浸漬することによって染色し、元長の３～７倍に延伸することで作製することができる。必要に応じてホウ酸や硫酸亜鉛、塩化亜鉛等を含んでいても良いし、ヨウ化カリウム等の水溶液に浸漬することもできる。更に必要に応じて染色の前にポリビニルアルコール系フィルムを水に浸漬して水洗しても良い。延伸は、ヨウ素で染色した後に行ってもよいし、染色しながら延伸してもよいし、延伸してからヨウ素で染色してもよい。ホウ酸やヨウ化カリウム等の水溶液中や水浴中でも延伸することができる。 A polarizer obtained by adsorbing iodine to a polyvinyl alcohol-based film and uniaxially stretching it can be produced, for example, by dyeing polyvinyl alcohol by immersing it in an aqueous solution of iodine and stretching it to 3 to 7 times its original length. . If necessary, it may contain boric acid, zinc sulfate, zinc chloride or the like, or it may be immersed in an aqueous solution such as potassium iodide. Furthermore, if necessary, the polyvinyl alcohol-based film may be dipped in water and rinsed before dyeing. Stretching may be carried out after dyeing with iodine, may be stretched while dyeing, or may be dyed with iodine after being stretched. It can also be stretched in an aqueous solution of boric acid or potassium iodide or in a water bath.
第１の偏光子１１及び第２の偏光子１２は、各々、観察面側及び背面側に保護層が設けられていてもよい。上記保護層は、偏光子の保護層として使用できる任意の適切なフィルムで形成される。当該フィルムの主成分となる材料の具体例としては、例えば、トリアセチルセルロース（ＴＡＣ）等のセルロース系樹脂や、シクロオレフィン系樹脂等の透明樹脂等が挙げられる。なお、シクロオレフィン系樹脂については、後で詳述する。以下、トリアセチルセルロースを主成分とするフィルムをＴＡＣフィルムとも言い、シクロオレフィン系樹脂、なかでもシクロオレフィンポリマー（ＣＯＰ）を主成分とするフィルムをＣＯＰフィルムとも言う。 The first polarizer 11 and the second polarizer 12 may each be provided with a protective layer on the viewing surface side and the back surface side. The protective layer is formed of any suitable film that can be used as a protective layer of a polarizer. Specific examples of the material that is the main component of the film include, for example, cellulose resins such as triacetyl cellulose (TAC), and transparent resins such as cycloolefin resins. The cycloolefin resin will be described in detail later. Hereinafter, a film having triacetyl cellulose as a main component is also referred to as a TAC film, and a film having a cycloolefin resin, in particular, a cycloolefin polymer (COP) as a main component is also referred to as a COP film.
第１の偏光子１１及び／又は第２の偏光子１２の液晶セル３０側に保護層を設ける場合、該保護層（内側保護層）は、光学的に等方性を有することが好ましい。具体的には、内側保護層の厚み方向の位相差Ｒｔｈは、好ましくは－１５ｎｍより大きく、＋１５ｎｍ未満、より好ましくは－１０ｎｍ以上、＋１０ｎｍ以下、更に好ましくは－６ｎｍ以上、＋６ｎｍ以下、特に好ましくは－３ｎｍ以上、＋３ｎｍ以下である。内側保護層の面内位相差Ｒｅは、好ましくは０ｎｍ以上、１５ｎｍ未満、より好ましくは０ｎｍ以上、１０ｎｍ以下、更に好ましくは０ｎｍ以上、６ｎｍ以下、特に好ましくは０ｎｍ以上、３ｎｍ以下である。 When a protective layer is provided on the liquid crystal cell 30 side of the first polarizer 11 and / or the second polarizer 12, the protective layer (inner protective layer) preferably has optical isotropy. Specifically, the retardation Rth in the thickness direction of the inner protective layer is preferably more than -15 nm and less than +15 nm, more preferably -10 nm or more and +10 nm or less, still more preferably -6 nm or more and +6 nm or less, particularly preferably -3 nm or more and +3 nm or less. The in-plane retardation Re of the inner protective layer is preferably 0 nm or more and less than 15 nm, more preferably 0 nm or more and 10 nm or less, still more preferably 0 nm or more and 6 nm or less, and particularly preferably 0 nm or more and 3 nm or less.
また、内側保護層を別途設ける代わりに、第１の偏光子１１及び第２の偏光子１２の液晶セル３０側の直ぐ隣の光学補償層（例えば、第１の光学補償層２１、第４の光学補償層２４等）をそれぞれ保護層として用いてもよい。 In addition, instead of separately providing the inner protective layer, an optical compensation layer (for example, the first optical compensation layer 21 or the fourth optical compensation layer 21 immediately adjacent to the liquid crystal cell 30 side of the first polarizer 11 and the second polarizer 12). The optical compensation layer 24 or the like may be used as a protective layer.
＜第１の光学補償層＞
第１の光学補償層２１は、上述のように、Ｒｅ≦１５ｎｍ、かつ、Ｒｔｈ≦－６０ｎｍを満たす。第１の光学補償層２１の面内位相差Ｒｅは、０～１０ｎｍであることが好ましく、０～５ｎｍであることがより好ましく、０～３ｎｍであることが更に好ましく、０～１ｎｍであることが特に好ましい。このように、第１の光学補償層２１は、ｎｚ＞ｎｘ＝ｎｙの屈折率の関係を有する光学補償層（所謂ポジティブＣプレート）であることが好ましい。なお、第１の光学補償層２１の厚み方向位相差Ｒｔｈについては、他の部材の光学パラメータに応じて上記範囲内において適宜設定可能である。また、第１の光学補償層２１は、面内位相差Ｒｅが１５ｎｍ以下等、充分小さい場合、面内では実質的に光学的に等方性と見なせるため、第１の光学補償層２１の面内における配置方向は特に限定されない。 <First optical compensation layer>
As described above, the first optical compensation layer 21 satisfies Re ≦ 15 nm and Rth ≦ −60 nm. The in-plane retardation Re of the first optical compensation layer 21 is preferably 0 to 10 nm, more preferably 0 to 5 nm, still more preferably 0 to 3 nm, and still more preferably 0 to 1 nm. Is particularly preferred. Thus, the first optical compensation layer 21 is preferably an optical compensation layer (so-called positive C plate) having a refractive index relationship of nz> nx = ny. The thickness direction retardation Rth of the first optical compensation layer 21 can be appropriately set within the above range according to the optical parameters of the other members. The first optical compensation layer 21 can be regarded as substantially optically isotropic in the plane when the in-plane retardation Re is sufficiently small, such as 15 nm or less, so the surface of the first optical compensation layer 21 is The arrangement direction in the inside is not particularly limited.
＜第２の光学補償層＞
第２の光学補償層２２は、上述のように、４０ｎｍ≦Ｒｅ≦１２０ｎｍ、かつ、１≦Ｎｚ≦４を満たす。第２の光学補償層２２は、１≦Ｎｚ≦１．４を満たすことが好ましく、１≦Ｎｚ≦１．１５を満たすことがより好ましく、実質的にＮｚ＝１を満たすことが特に好ましい。ここで、実質的にＮｚ＝１を満たすとは、より具体的には、１≦Ｎｚ≦１．０５を満たすことを意味する。このように、第２の光学補償層２２は、ｎｘ＞ｎｚ＞ｎｙの屈折率の関係を有する光学補償層（所謂ポジティブＢプレート）、又は、ｎｘ＞ｎｚ＝ｎｙの屈折率の関係を有する光学補償層（所謂ポジティブＡプレート）であってもよいが、後者（ポジティブＡプレート）であることが好ましい。第２の光学補償層２２の面内位相差Ｒｅについては、他の部材の光学パラメータ応じて上記範囲内において適宜設定可能である。 <Second optical compensation layer>
As described above, the second optical compensation layer 22 satisfies 40 nm ≦ Re ≦ 120 nm and 1 ≦ Nz ≦ 4. The second optical compensation layer 22 preferably satisfies 1 ≦ Nz ≦ 1.4, more preferably 1 ≦ Nz ≦ 1.15, and particularly preferably substantially satisfying Nz = 1. Here, substantially satisfying Nz = 1 means, more specifically, satisfying 1 ≦ Nz ≦ 1.05. Thus, the second optical compensation layer 22 is an optical compensation layer (so-called positive B plate) having a refractive index relationship of nx>nz> ny, or an optical component having a refractive index relationship of nx> nz = ny. It may be a compensation layer (so-called positive A plate), but is preferably the latter (positive A plate). The in-plane retardation Re of the second optical compensation layer 22 can be appropriately set within the above range according to the optical parameters of the other members.
＜第３及び第４の光学補償層＞
第３の光学補償層２３及び第４の光学補償層２４は、上述のように、λ／４位相差板として機能する。ここで、λ／４位相差板とは、光ビームの偏光面を回転させる役目をする電子光学的な複屈折板であり、互いに直角な方向に振動する直線偏光間に１／４波長の光路差を生じさせる機能を有するものを言う。すなわち、常光線成分と異常光線成分との間の位相が４分の１サイクルずれるように作用し、円偏光を直線偏光に（又は直線偏光を円偏光に）変換するものを言う。したがって、第１の偏光子１１及び第３の光学補償層２３と、第２の偏光子１２及び第４の光学補償層２４とが、互いに直交する左右円偏光板として機能する。 <Third and Fourth Optical Compensation Layers>
The third optical compensation layer 23 and the fourth optical compensation layer 24 function as λ / 4 retardation plates as described above. Here, the λ / 4 retardation plate is an electron optical birefringence plate that serves to rotate the polarization plane of the light beam, and has an optical path of 1⁄4 wavelength between linearly polarized light vibrating in directions perpendicular to each other. We say what has function to make difference. That is, it means that the phase between the ordinary ray component and the extraordinary ray component acts so as to be shifted by a quarter cycle, and circularly polarized light is converted to linearly polarized light (or linearly polarized light to circularly polarized light). Therefore, the first polarizer 11 and the third optical compensation layer 23, and the second polarizer 12 and the fourth optical compensation layer 24 function as left and right circularly polarizing plates orthogonal to each other.
第３の光学補償層２３及び第４の光学補償層２４は、各々、面内位相差Ｒｅが正確には１３７．５ｎｍ付近であるが、１００～１７５ｎｍであればよく、１１０～１６５ｎｍであることが好ましく、１３０～１４５ｎｍであることがより好ましい。高コントラストを保つ観点から、第３の光学補償層２３の面内位相差Ｒｅは、第４の光学補償層２４の面内位相差Ｒｅと実質的に同じであることが好ましい。ここで、第３の光学補償層２３及び第４の光学補償層２４の面内位相差Ｒｅが実質的に同じであるとは、より具体的には、２つの面内位相差Ｒｅの差（絶対値）が７．６４ｎｍ以下であることを意味し、好ましくは２ｎｍ以下であり、より好ましくは１ｎｍ以下であり、特に好ましくは０ｎｍ（完全に同じ）である。なお、７．６４ｎｍの面内位相差Ｒｅの差とは、面内位相差Ｒｅをラジアン（ｒａｄ）で表したΓ（＝２π×Ｒｅ／λ）が５°であることを意味し、第３及び第４の光学補償層２３及び２４の面内位相差Ｒｅの差がこれより大きくなると、急激にコントラストが悪化することが経験上分かっている。また、第３の光学補償層２３及び第４の光学補償層２４は、各々、１≦Ｎｚ≦２．４を満たすことが好ましい。 The third optical compensation layer 23 and the fourth optical compensation layer 24 each have an in-plane retardation Re of approximately 137.5 nm, but may be 100 to 175 nm, and 110 to 165 nm. Is preferable, and 130 to 145 nm is more preferable. From the viewpoint of maintaining high contrast, the in-plane retardation Re of the third optical compensation layer 23 is preferably substantially the same as the in-plane retardation Re of the fourth optical compensation layer 24. Here, the in-plane retardation Re of the third optical compensation layer 23 and the fourth optical compensation layer 24 is substantially the same, more specifically, the difference between the two in-plane retardations Re ( It means that the absolute value) is 7.64 nm or less, preferably 2 nm or less, more preferably 1 nm or less, and particularly preferably 0 nm (completely the same). The difference of the in-plane retardation Re of 7.64 nm means that Γ (= 2π × Re / λ), which represents the in-plane retardation Re in radians (rad), is 5 °, and the third difference It is empirically known that when the difference between the in-plane retardations Re of the fourth optical compensation layers 23 and 24 becomes larger than this, the contrast is rapidly deteriorated. Preferably, the third optical compensation layer 23 and the fourth optical compensation layer 24 each satisfy 1 ≦ Nz ≦ 2.4.
＜第１～第４の光学補償層の材料及び形成方法＞
第１～第４の光学補償層２１～２４の材料及び形成方法については特に限定されず、例えば、ポリマーフィルムを延伸等の加工したもの、液晶性材料の配向を固定したもの、無機材料から構成される薄板等を用いることができるが、なかでもポリマーフィルムを延伸等の加工したもの及び液晶性材料の配向を固定したものが好適である。液晶化合物としては、重合性液晶が好適である。 <Material and Method of Forming First to Fourth Optical Compensation Layers>
There is no particular limitation on the material and formation method of the first to fourth optical compensation layers 21 to 24. For example, the polymer film is processed by stretching or the like, the orientation of the liquid crystalline material is fixed, and it is composed of an inorganic material. Although thin plates or the like to be used can be used, among them, one obtained by processing a polymer film by drawing or the like and one obtained by fixing the orientation of a liquid crystalline material are preferable. The liquid crystal compound is preferably a polymerizable liquid crystal.
第１～第４の光学補償層２１～２４の形成方法としては、ポリマーフィルムの場合、例えば溶剤キャスト法、溶融押出し法等を用いることができる。共押出し法により、複数の複屈折層を同時に形成する方法であってもよい。所望の位相差が発現してさえいれば、無延伸であってもよいし、延伸が施されていてもよい。延伸方法も特に限定されず、ロール間引張り延伸法、ロール間圧縮延伸法、テンター横一軸延伸法、縦横二軸延伸法の他、熱収縮性フィルムの収縮力の作用下に延伸を行う特殊延伸法等を用いることができる。また、液晶性材料の場合、例えば、配向処理を施した基材フィルムの上に液晶性材料を塗布し、配向固定する方法等を用いることができる。所望の位相差が発現してさえいれば、基材フィルムに特別な配向処理を行わない方法や、配向固定した後、基材フィルムから剥がして別のフィルムに転写加工する方法等であってもよい。更に、液晶性材料の配向を固定しない方法を用いてもよい。また、非液晶性材料の場合も、液晶性材料と同様の形成方法を用いてもよい。 As a method of forming the first to fourth optical compensation layers 21 to 24, in the case of a polymer film, for example, a solvent cast method, a melt extrusion method or the like can be used. It may be a method of simultaneously forming a plurality of birefringent layers by a co-extrusion method. As long as the desired retardation is developed, it may be non-stretching or may be stretched. The stretching method is also not particularly limited, and it is a special stretching in which stretching is performed under the action of the shrinking force of the heat shrinkable film, in addition to the inter-roll tensile stretching method, inter-roll compression stretching method, tenter transverse uniaxial stretching method, longitudinal and transverse biaxial stretching method. A law etc. can be used. Moreover, in the case of a liquid crystalline material, for example, a method of applying a liquid crystalline material on a substrate film subjected to alignment treatment, and orienting and fixing can be used. Even if there is a method in which the substrate film is not subjected to special orientation processing as long as the desired phase difference is expressed, or a method in which the film is peeled off from the substrate film and transferred to another film after orientation fixation. Good. Furthermore, a method in which the orientation of the liquid crystal material is not fixed may be used. Also in the case of a non-liquid crystal material, the same formation method as the liquid crystal material may be used.
第１の光学補償層２１を液晶性材料から形成する場合、第２の光学補償層２２上に液晶性材料を塗布してもよい。 When the first optical compensation layer 21 is formed of a liquid crystalline material, the liquid crystalline material may be coated on the second optical compensation layer 22.
上記ポリマーフィルムの主成分となる材料の具体例としては、例えば、シクロオレフィン系樹脂、セルロース系樹脂、（メタ）アクリル系樹脂等の透明樹脂が挙げられる。なお、本明細書において「（メタ）アクリル系樹脂」とは、アクリル系樹脂及びメタクリル系樹脂よりなる群から選ばれる少なくとも１種を表す。その他の「（メタ）」を付した用語においても同様である。 As a specific example of the material used as the main ingredients of the above-mentioned polymer film, transparent resin, such as cycloolefin system resin, cellulose system resin, (meth) acrylic resin, is mentioned, for example. In addition, in this specification, "(meth) acrylic-type resin" represents at least 1 sort (s) chosen from the group which consists of acrylic resin and methacrylic resin. The same applies to other terms with "(meth)".
上記シクロオレフィン系樹脂としては、環状オレフィン（シクロオレフィン）からなるモノマーのユニットを有する樹脂であれば特に限定されず、シクロオレフィンポリマー（ＣＯＰ）又はシクロオレフィンコポリマー（ＣＯＣ）のいずれであってもよい。シクロオレフィンコポリマーとは、環状オレフィンとエチレン等のオレフィンとの共重合体である非結晶性の環状オレフィン系樹脂のことをいう。 The above cycloolefin resin is not particularly limited as long as it is a resin having a monomer unit consisting of cyclic olefin (cycloolefin), and may be any of cycloolefin polymer (COP) or cycloolefin copolymer (COC) . The cycloolefin copolymer refers to a non-crystalline cyclic olefin resin which is a copolymer of a cyclic olefin and an olefin such as ethylene.
上記環状オレフィンとしては、多環式の環状オレフィンと単環式の環状オレフィンとが挙げられる。多環式の環状オレフィンとしては、ノルボルネン、メチルノルボルネン、ジメチルノルボルネン、エチルノルボルネン、エチリデンノルボルネン、ブチルノルボルネン等のノルボルネン類、ジシクロペンタジエン、ジヒドロジシクロペンタジエン、メチルジシクロペンタジエン、ジメチルジシクロペンタジエン等のジシクロペンタジエン類、テトラシクロドデセン、メチルテトラシクロドデセン、ジメチルテトラシクロドデセン等のテトラシクロドデセン類、トリシクロペンタジエン、テトラシクロペンタジエン等のシクロペンタジエンの多量体類が挙げられる。また、単環式の環状オレフィンとしては、シクロブテン、シクロペンテン、シクロオクテン、シクロオクタジエン、シクロオクタトリエン、シクロドデカトリエンが挙げられる。なかでも、透明性、耐湿性、位相差制御の点から、ノルボルネン類が好ましい。 As said cyclic olefin, polycyclic cyclic olefin and monocyclic cyclic olefin are mentioned. Examples of polycyclic cyclic olefins include norbornenes such as norbornene, methyl norbornene, dimethyl norbornene, ethyl norbornene, ethylidene norbornene and butyl norbornene, dicyclopentadiene, dihydrodicyclopentadiene, methyldicyclopentadiene, dimethyldicyclopentadiene and the like Examples include tetracyclododecenes such as dicyclopentadienes, tetracyclododecene, methyltetracyclododecene and dimethyltetracyclododecene, and polymers of cyclopentadienes such as tricyclopentadiene and tetracyclopentadiene. Furthermore, examples of monocyclic cyclic olefins include cyclobutene, cyclopentene, cyclooctene, cyclooctadiene, cyclooctatriene and cyclododecatriene. Among them, norbornenes are preferable in terms of transparency, moisture resistance, and retardation control.
上記セルロース系樹脂とは、綿花リンタや木材パルプ（広葉樹パルプ、針葉樹パルプ）等の原料セルロースから得られるセルロースの水酸基における水素原子の一部又は全部がアセチル基、プロピオニル基及び／又はブチリル基で置換された、セルロース有機酸エステル又はセルロース混合有機酸エステルをいう。例えば、セルロースの酢酸エステル、プロピオン酸エステル、酪酸エステル、及びそれらの混合エステル等からなるものが挙げられる。なかでも、トリアセチルセルロース、ジアセチルセルロース、セルロースアセテートプロピオネート、セルロースアセテートブチレートが好ましい。 With the above-mentioned cellulose resin, part or all of hydrogen atoms in hydroxyl groups of cellulose obtained from raw material cellulose such as cotton linta and wood pulp (hardwood pulp and softwood pulp) are substituted with acetyl group, propionyl group and / or butyryl group Cellulose organic acid ester or cellulose mixed organic acid ester. For example, those composed of cellulose acetate, propionate, butyrate, mixed esters thereof and the like can be mentioned. Among them, triacetyl cellulose, diacetyl cellulose, cellulose acetate propionate and cellulose acetate butyrate are preferable.
上記（メタ）アクリル系樹脂は、（メタ）アクリル系モノマー由来の構成単位を含む重合体である。該重合体は、典型的にはメタクリル酸エステルを含む重合体である。好ましくはメタクリル酸エステルに由来する構成単位の割合が、全構成単位に対して、５０重量％以上含む重合体である。（メタ）アクリル系樹脂は、メタクリル酸エステルの単独重合体であってもよいし、他の重合性モノマー由来の構成単位を含む共重合体であってもよい。この場合、他の重合性モノマー由来の構成単位の割合は、好ましくは全構成単位に対して、５０％以下である。 The (meth) acrylic resin is a polymer containing a structural unit derived from a (meth) acrylic monomer. The polymer is typically a polymer containing a methacrylic acid ester. Preferably, the proportion of constituent units derived from methacrylic acid ester is a polymer containing 50% by weight or more based on all constituent units. The (meth) acrylic resin may be a homopolymer of methacrylic acid ester, or may be a copolymer containing a structural unit derived from another polymerizable monomer. In this case, the proportion of constituent units derived from other polymerizable monomers is preferably 50% or less based on all constituent units.
上記（メタ）アクリル系樹脂を構成し得るメタクリル酸エステルとしては、メタクリル酸アルキルエステルが好ましい。メタクリル酸アルキルエステルとしては、メタクリル酸メチル、メタクリル酸エチル、メタクリル酸ｎ－プロピル、メタクリル酸イソプロピル、メタクリル酸ｎ－ブチル、メタクリル酸イソブチル、メタクリル酸ｔ－ブチル、メタクリル酸２－エチルヘキシル、メタクリル酸シクロヘキシル、メタクリル酸２－ヒドロキシエチルのようなアルキル基の炭素数が１～８であるメタクリル酸アルキルエステルが挙げられる。メタクリル酸アルキルエステルに含まれるアルキル基の炭素数は、好ましくは１～４である。（メタ）アクリル系樹脂において、メタクリル酸エステルは、１種のみを単独で用いてもよいし２種以上を併用してもよい。 As a methacrylic acid ester which can comprise the said (meth) acrylic-type resin, methacrylic acid alkyl ester is preferable. As alkyl methacrylate, methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, t-butyl methacrylate, 2-ethylhexyl methacrylate, cyclohexyl methacrylate And methacrylic acid alkyl esters having 1 to 8 carbon atoms in the alkyl group such as 2-hydroxyethyl methacrylate. The carbon number of the alkyl group contained in the methacrylic acid alkyl ester is preferably 1 to 4. In the (meth) acrylic resin, only one kind of methacrylic acid ester may be used alone, or two or more kinds thereof may be used in combination.
上記（メタ）アクリル系樹脂を構成し得る上記他の重合性モノマーとしては、アクリル酸エステル、その他の分子内に重合性炭素－炭素二重結合を有する化合物を挙げることができる。他の重合性モノマーは、１種のみを単独で用いてもよいし２種以上を併用してもよい。アクリル酸エステルとしては、アクリル酸アルキルエステルが好ましい。アクリル酸アルキルエステルとしては、アクリル酸メチル、アクリル酸エチル、アクリル酸ｎ－プロピル、アクリル酸イソプロピル、アクリル酸ｎ－ブチル、アクリル酸イソブチル、アクリル酸ｔ－ブチル、アクリル酸２－エチルヘキシル、アクリル酸シクロヘキシル、アクリル酸２－ヒドロキシエチルのようなアルキル基の炭素数が１～８であるアクリル酸アルキルエステル等が挙げられる。アクリル酸アルキルエステルに含まれるアルキル基の炭素数は、好ましくは１～４である。（メタ）アクリル系樹脂において、アクリル酸エステルは、１種のみを単独で用いてもよいし２種以上を併用してもよい。 Examples of the other polymerizable monomer which can constitute the (meth) acrylic resin include acrylic acid esters and compounds having a polymerizable carbon-carbon double bond in another molecule. The other polymerizable monomers may be used alone or in combination of two or more. As acrylic acid ester, acrylic acid alkyl ester is preferable. As alkyl acrylate, methyl acrylate, ethyl acrylate, n-propyl acrylate, isopropyl acrylate, n-butyl acrylate, isobutyl acrylate, t-butyl acrylate, 2-ethylhexyl acrylate, cyclohexyl acrylate And alkyl acrylates having 1 to 8 carbon atoms in the alkyl group such as 2-hydroxyethyl acrylate. The carbon number of the alkyl group contained in the acrylic acid alkyl ester is preferably 1 to 4. In the (meth) acrylic resin, only one acrylic ester may be used alone, or two or more acrylic esters may be used in combination.
上記その他の分子内に重合性炭素－炭素二重結合を有する化合物としては、エチレン、プロピレン、スチレン等のビニル系化合物や、アクリロニトリルのようなビニルシアン化合物が挙げられる。その他の分子内に重合性炭素－炭素二重結合を有する化合物は、１種のみを単独で用いてもよいし２種以上を併用してもよい。 Examples of the other compound having a polymerizable carbon-carbon double bond in the molecule include vinyl compounds such as ethylene, propylene and styrene, and vinyl cyan compounds such as acrylonitrile. As the compound having a polymerizable carbon-carbon double bond in the other molecule, one type may be used alone, or two or more types may be used in combination.
上記重合性液晶とは、重合性基を有し、かつ、液晶性を有する化合物である。重合性基は、重合反応に関与する基を意味し、光重合性基であることが好ましい。ここで、光重合性基とは、光重合開始剤から発生した活性ラジカルや酸等によって重合反応に関与し得る基のことをいう。重合性基としては、ビニル基、ビニルオキシ基、１－クロロビニル基、イソプロペニル基、４－ビニルフェニル基、アクリロイルオキシ基、メタクリロイルオキシ基、オキシラニル基、オキセタニル基等が挙げられる。なかでも、アクリロイルオキシ基、メタクリロイルオキシ基、ビニルオキシ基、オキシラニル基及びオキセタニル基が好ましく、アクリロイルオキシ基がより好ましい。液晶性はサーモトロピック性液晶でもリオトロピック液晶でもよく、サーモトロピック液晶を秩序度で分類すると、ネマチック液晶でもスメクチック液晶でもよいが、成膜の容易さという観点からは、サーモトロピック性のネマチック液晶が好ましい。 The polymerizable liquid crystal is a compound having a polymerizable group and having liquid crystallinity. The polymerizable group means a group involved in the polymerization reaction, and is preferably a photopolymerizable group. Here, the photopolymerizable group refers to a group capable of participating in the polymerization reaction by active radicals or acids generated from the photopolymerization initiator. Examples of the polymerizable group include vinyl group, vinyloxy group, 1-chlorovinyl group, isopropenyl group, 4-vinylphenyl group, acryloyloxy group, methacryloyloxy group, oxiranyl group, oxetanyl group and the like. Among them, acryloyloxy group, methacryloyloxy group, vinyloxy group, oxiranyl group and oxetanyl group are preferable, and acryloyloxy group is more preferable. The liquid crystallinity may be a thermotropic liquid crystal or a lyotropic liquid crystal. If the thermotropic liquid crystals are classified according to the degree of order, they may be nematic liquid crystals or smectic liquid crystals, but from the viewpoint of easiness of film formation, thermotropic nematic liquid crystals are preferred. .
上記重合性液晶の具体例としては、液晶便覧（液晶便覧編集委員会編、丸善（株）平成１２年１０月３０日発行）の「３．８．６ ネットワーク（完全架橋型）」、「６．５．１ 液晶材料 ｂ．重合性ネマチック液晶材料」に記載された化合物の中で重合性基を有する化合物、特開２０１０－３１２２３号公報、特開２０１０－２７０１０８号公報、特開２０１１－６３６０号公報および特開２０１１－２０７７６５号公報記載の重合性液晶が挙げられる。 Specific examples of the above-mentioned polymerizable liquid crystal include “3.8.6 Network (fully cross-linked type)”, “6. .5.1 Liquid Crystal Materials b. Compounds Having a Polymerizable Group Among the Compounds Described in the Polymerizable Nematic Liquid Crystal Material], compounds disclosed in JP 2010-31223 A, JP 2010-270108 A, JP 2011-6360 A And polymerizable liquid crystals described in JP-A-2011-207765.
これらの材料は、いずれも、上記（１）～（３）のような課題が解決された、あるいは影響が小さい材料であるが、なかでも、第１の光学補償層２１としては、重合性液晶を基材（基板）と平行に配向させて重合したものが好適であり、第２～第４の光学補償層２２～２４としては、シクロオレフィン系樹脂を延伸したもの、セルロース系樹脂、特にトリアセチルセルロースを延伸したもの、（メタ）アクリル系樹脂を延伸したもの、及び、重合性液晶を基材（基板）と平行に配向させて重合したものが好適である。 All of these materials are materials in which the problems as described in the above (1) to (3) are solved or the influence is small, but among them, as the first optical compensation layer 21, a polymerizable liquid crystal It is preferable that the polymer is oriented in parallel to the base material (substrate) and polymerized, and as the second to fourth optical compensation layers 22 to 24, those obtained by drawing a cycloolefin resin, It is preferable to use one obtained by stretching acetyl cellulose, one obtained by stretching a (meth) acrylic resin, and one obtained by orientating and polymerizing a polymerizable liquid crystal in parallel to a substrate (substrate).
第１～第４の光学補償層２１～２４として、上述の材料及び形成方法により形成された光学補償層を用いることによって、円偏光板３、４に溶剤が付着したとしても剥離及び破断の発生を抑制することができる。 By using the optical compensation layer formed by the above-mentioned material and forming method as the first to fourth optical compensation layers 21 to 24, occurrence of peeling and breakage even if the solvent adheres to the circularly polarizing plates 3 and 4 Can be suppressed.
＜液晶セル＞
液晶セル３０は、上述のように、互いに対向する一対の基板３１及び３２と、一対の基板３１及び３２間の液晶層３３とを含む。基板３１及び３２の一方（カラーフィルター基板）には、カラーフィルターと、ブラックマトリクスと、共通電極とが設けられている。基板３１及び３２の他方（アクティブマトリクス基板）には、液晶の電気光学特性を制御するスイッチング素子（代表的にはＴＦＴ）と、このスイッチング素子にゲート信号を与える走査線及びソース信号を与える信号線と、画素電極とが設けられている。なお、カラーフィルターは、１０～５０ｎｍ程度の厚み方向の位相差Ｒｔｈを持っていてもよい。また、カラーフィルターは、アクティブマトリクス基板側に設けてもよい。基板３１及び３２の間隔（セルギャップ）は、スペーサーによって制御されている。各基板３１、３２の液晶層３３と接する側には、例えば、ポリイミドからなる配向膜が設けられている。 <Liquid crystal cell>
As described above, the liquid crystal cell 30 includes the pair of substrates 31 and 32 facing each other, and the liquid crystal layer 33 between the pair of substrates 31 and 32. On one of the substrates 31 and 32 (color filter substrate), a color filter, a black matrix and a common electrode are provided. On the other of the substrates 31 and 32 (active matrix substrate), a switching element (typically, a TFT) for controlling the electro-optical characteristics of liquid crystal, and a scanning line for applying a gate signal to the switching element And a pixel electrode. The color filter may have a thickness direction retardation Rth of about 10 to 50 nm. In addition, the color filter may be provided on the active matrix substrate side. The distance between the substrates 31 and 32 (cell gap) is controlled by the spacer. On the side of each of the substrates 31 and 32 in contact with the liquid crystal layer 33, for example, an alignment film made of polyimide is provided.
また、液晶セル３０は、上述のように、黒表示時（液晶表示装置１の黒表示時）に、液晶層３３中の液晶分子を一対の基板３１及び３２面に対して実質的に垂直（法線方向）に配向する。ここで、「実質的に垂直」とは、液晶分子の配向ベクトルが各基板３１、３２の法線方向に対して傾いている場合、すなわち、液晶分子がチルト角を有する場合も包含する。当該チルト角（法線からの角度）は、液晶パネル２の表示可能部分（表示領域２ａ内における遮光部を除く光の変調可能な部分）の全ての位置で、０°以上、かつ、好ましくは１０°以下、より好ましくは５°以下、更に好ましくは１°以下である。通常、液晶分子は、電圧無印加時に、各基板３１、３２面に略垂直（法線方向）に配向する。このような配向は、例えば、配向膜として垂直配向膜を形成した基板間に負の誘電率異方性を有するネマチック液晶を配することにより実現され得る。 Further, as described above, in the liquid crystal cell 30, the liquid crystal molecules in the liquid crystal layer 33 are substantially perpendicular to the pair of substrates 31 and 32 during black display (black display of the liquid crystal display device 1). Orientation in the normal direction). Here, "substantially perpendicular" also includes the case where the alignment vector of the liquid crystal molecules is tilted with respect to the normal direction of each substrate 31, 32, that is, the case where the liquid crystal molecules have a tilt angle. The tilt angle (angle from the normal) is at least 0 ° and preferably at all positions of the displayable portion of the liquid crystal panel 2 (the modulatable portion of the light except for the light shielding portion in the display area 2a). It is 10 ° or less, more preferably 5 ° or less, and still more preferably 1 ° or less. Usually, the liquid crystal molecules are aligned substantially perpendicular (normal direction) to the surfaces of the substrates 31 and 32 when no voltage is applied. Such alignment can be realized, for example, by arranging a nematic liquid crystal having negative dielectric anisotropy between substrates on which a vertical alignment film is formed as an alignment film.
一対の直線偏光板を用いたＶＡモードでは、バックライトにより背面側の基板に光を照射すると、背面側の偏光子を通過して液晶層に入射した直線偏光の光は、略垂直配向している液晶分子の長軸の方向に沿って進む。液晶分子の長軸方向には実質的に複屈折が生じないため入射光は偏光方位を変えずに進み、背面側の偏光子と実質的に直交する吸収軸を有する観察面側の偏光子で吸収される。これにより電圧無印加時において暗状態の表示（黒表示）が得られる（ノーマリブラックモード）。画素電極及び共通電極間に電圧が印加されると、液晶分子の長軸が各基板面に平行に配向する。この状態の液晶分子は、背面側の偏光子を通過して液晶層に入射した直線偏光の光に対して複屈折性を示し、入射光の偏光状態は液晶分子の傾きに応じて変化する。所定の最大電圧印加時において液晶層を通過する光は、例えばその偏光方位が９０°回転させられた直線偏光となるので、観察面側の偏光子を透過して明状態の表示（白表示）が得られる。再び電圧無印加状態にすると配向規制力により暗状態の表示に戻すことができる。また、印加電圧を変化させて液晶分子の傾きを制御して観察面側の偏光子からの透過光強度を変化させることにより階調表示が可能となる。 In the VA mode using a pair of linear polarizing plates, when light is irradiated to the substrate on the back side by back light, linearly polarized light passing through the polarizer on the back side and entering the liquid crystal layer is approximately vertically aligned. Travel along the direction of the long axis of the liquid crystal molecules. Since substantially no birefringence occurs in the long axis direction of liquid crystal molecules, incident light travels without changing the polarization direction, and is a polarizer on the viewing surface side having an absorption axis substantially orthogonal to the polarizer on the back surface side. Absorbed As a result, a dark state display (black display) can be obtained when no voltage is applied (normally black mode). When a voltage is applied between the pixel electrode and the common electrode, the major axes of the liquid crystal molecules are aligned parallel to the surface of each substrate. The liquid crystal molecules in this state exhibit birefringence with respect to linearly polarized light that has entered the liquid crystal layer through the polarizer on the back side, and the polarization state of the incident light changes in accordance with the inclination of the liquid crystal molecules. When a predetermined maximum voltage is applied, light passing through the liquid crystal layer becomes, for example, linearly polarized light whose polarization direction is rotated by 90 °. Therefore, light passing through the polarizer on the viewing surface side is displayed in a bright state (white display) Is obtained. When the voltage is not applied again, the display can be returned to the dark state by the alignment control force. In addition, gradation display can be performed by changing the applied voltage to control the inclination of the liquid crystal molecules and changing the transmitted light intensity from the polarizer on the observation surface side.
このような一対の直線偏光板を用いたＶＡモードでは、電圧印加時の液晶分子の傾斜方向が一方向であると視野角特性に非対称性が発生してしまうため、例えば画素電極構造の工夫や、画素内に突起物等の配向制御手段を設ける方法により、液晶分子の傾斜方向を複数に分割した配向分割型のＶＡモード、いわゆるＭＶＡモード（マルチドメイン型ＶＡモード）が広く用いられている。白表示状態の透過率を最大化する観点から、通常は偏光子軸方位と電圧印加時の液晶分子の傾斜方位とが４５°の角度をなすように設定される。クロスニコル偏光子間に複屈折媒体を挟んだときの透過率は、偏光子の軸と複屈折媒体の遅相軸とのなす角度をβ（単位：ｒａｄ）とするとき、ｓｉｎ２（２β）に比例するためである。典型的なＭＶＡモードでは、液晶分子の傾斜方位が４５°、１３５°、２２５°、３１５°の４つのドメインに分割され得る。このような４つのドメインに分割されたＭＶＡモードにおいても、ドメイン境界や配向制御手段の近傍で、シュリーレン配向や意図しない方向への配向が観察されることが多く、透過率ロスの原因となっている。 In the VA mode using such a pair of linear polarizing plates, asymmetry is generated in the viewing angle characteristics if the tilt direction of the liquid crystal molecules is one direction at the time of voltage application, for example, the device of the pixel electrode structure or A so-called MVA mode (multi-domain type VA mode), which is an alignment division type VA mode in which the tilt direction of liquid crystal molecules is divided into a plurality, is widely used by providing alignment control means such as protrusions in pixels. From the viewpoint of maximizing the transmittance in the white display state, usually, the polarizer axis orientation and the tilt orientation of liquid crystal molecules at the time of voltage application are set to form an angle of 45 °. The transmittance when a birefringent medium is sandwiched between crossed Nicol polarizers is sin 2 (2β), where the angle between the axis of the polarizer and the slow axis of the birefringent medium is β (unit: rad) To be proportional to In a typical MVA mode, the tilt orientation of liquid crystal molecules can be divided into four domains of 45 °, 135 °, 225 °, and 315 °. Even in the MVA mode divided into such four domains, Schlieren orientation or orientation in an unintended direction is often observed in the vicinity of domain boundaries or orientation control means, which causes transmittance loss. There is.
それに対して、本実施形態の一対の円偏光板３及び４を用いたＶＡモードによれば、互いに直交する左右円偏光板３及び４間に複屈折媒体を挟んだときの透過率は、各偏光子１１、１２の軸と複屈折媒体の遅相軸とのなす角度に依存しないため、液晶分子の傾斜方位が４５°、１３５°、２２５°、３１５°以外であっても、液晶分子の傾きさえ制御できれば所望の透過率が確保できる。したがって、例えば、画素中央に円形の突起物を配置し、液晶分子を全方位に傾斜させるものであってもよいし、又は、傾斜方位を全く制御せずにランダムな方位に傾斜させるものであってもよい。 On the other hand, according to the VA mode using the pair of circularly polarizing plates 3 and 4 of the present embodiment, the transmittance when the birefringent medium is sandwiched between the left and right circularly polarizing plates 3 and 4 orthogonal to each other is Because it does not depend on the angle between the axes of the polarizers 11 and 12 and the slow axis of the birefringent medium, the liquid crystal molecules are not inclined at 45 °, 135 °, 225 °, 315 °, If the inclination can be controlled, the desired transmittance can be secured. Therefore, for example, a circular protrusion may be disposed at the center of the pixel, and liquid crystal molecules may be inclined in all directions, or may be inclined in random directions without controlling the inclination direction at all. May be
液晶材料の屈折率異方性をΔｎとセル厚み（セルギャップ、すなわち液晶層３３の厚み）ｄとの積で表される液晶層３３のリタデーション（パネルリタデーション）Δｎ・ｄは、特に限定されないが、通常、２００～５００ｎｍであり、２５０～４５０ｎｍであることが好ましく、３００～４００ｎｍであることがより好ましい。 The retardation (panel retardation) Δn · d of the liquid crystal layer 33 represented by the product of Δn and cell thickness (cell gap, ie, thickness of the liquid crystal layer 33) d of the liquid crystal material is not particularly limited. Usually, it is 200 to 500 nm, preferably 250 to 450 nm, and more preferably 300 to 400 nm.
以下、本実施形態のより具体的かつ好適な積層構造について説明する。 Hereinafter, a more specific and preferable laminated structure of the present embodiment will be described.
＜積層構造１－１＞
図４は、実施形態１の積層構造１－１に係る液晶表示装置の断面模式図である。
図４に示すように、本実施形態の液晶表示装置１は、第１の偏光子１１及び液晶セル３０の間に第１～第３の光学補償層２１～２３以外の光学補償層を備えず、かつ、液晶セル３０及び第２の偏光子１２の間に第４の光学補償層２４以外の光学補償層を備えていなくてもよい。これにより、過酷な環境に対する液晶表示装置１の耐久性をより優れたものにすることができるとともに、液晶パネル２を特に薄くすることができる。 <Laminated structure 1-1>
FIG. 4 is a schematic cross-sectional view of the liquid crystal display device according to the multilayer structure 1-1 of the first embodiment.
As shown in FIG. 4, the liquid crystal display device 1 of this embodiment does not include an optical compensation layer other than the first to third optical compensation layers 21 to 23 between the first polarizer 11 and the liquid crystal cell 30. In addition, an optical compensation layer other than the fourth optical compensation layer 24 may not be provided between the liquid crystal cell 30 and the second polarizer 12. Thus, the durability of the liquid crystal display device 1 against severe environments can be made more excellent, and the liquid crystal panel 2 can be made particularly thin.
本積層構造では、第１の光学補償層２１は、厚み方向位相差Ｒｔｈが－２００～－１００ｎｍ（より好ましくは－１８０～－１２０ｎｍ）であり、第２の光学補償層２２は、面内位相差Ｒｅが６０～１１０ｎｍ（より好ましくは７０～１００ｎｍ）であり、かつ、１≦Ｎｚ≦１．４（より好ましくは１≦Ｎｚ≦１．２）を満たし、第３の光学補償層２３は、１．４≦Ｎｚ≦２．４（より好ましくは１．５≦Ｎｚ≦１．８）を満たし、第４の光学補償層２４は、１．４≦Ｎｚ≦２．４（より好ましくは２≦Ｎｚ≦２．３）を満たすことが好ましい。 In the present laminated structure, the first optical compensation layer 21 has a thickness direction retardation Rth of -200 to -100 nm (more preferably -180 to -120 nm), and the second optical compensation layer 22 has an in-plane position. The third optical compensation layer 23 has a phase difference Re of 60 to 110 nm (more preferably 70 to 100 nm) and satisfies 1 ≦ Nz ≦ 1.4 (more preferably 1 ≦ Nz ≦ 1.2). The fourth optical compensation layer 24 satisfies 1.4 ≦ Nz ≦ 2.4 (more preferably 1.5 ≦ Nz ≦ 1.8), and 1.4 ≦ Nz ≦ 2.4 (more preferably 2 ≦). It is preferable to satisfy Nz ≦ 2.3).
本積層構造では、第１の偏光子１１は、第１の光学補償層２１に隣接配置されていてもよく、第３の光学補償層２３及び第４の光学補償層２４は、液晶セル３０に隣接配置されていてもよく、第２の偏光子１２は、第４の光学補償層２４に隣接配置されていてもよい。 In the present laminated structure, the first polarizer 11 may be disposed adjacent to the first optical compensation layer 21, and the third optical compensation layer 23 and the fourth optical compensation layer 24 may be disposed in the liquid crystal cell 30. The second polarizer 12 may be disposed adjacent to the fourth optical compensation layer 24.
＜積層構造１－２＞
図５は、実施形態１の積層構造１－２に係る液晶表示装置の断面模式図である。図６は、実施形態１の積層構造１－２に係る液晶表示装置の斜視模式図である。
図５及び６に示すように、本実施形態の液晶表示装置１は、第５の光学補償層２５及び第６の光学補償層２６を更に備え、第１の偏光子１１、第１の光学補償層２１、第２の光学補償層２２、第３の光学補償層２３、液晶セル３０、第４の光学補償層２４、第５の光学補償層２５、第６の光学補償層２６、及び、第２の偏光子１２は、この順に配置されてもよい。第５の光学補償層２５は、第２の光学補償層２２と同様に、面内位相差Ｒｅが４０～１２０ｎｍであり、１≦Ｎｚ≦４を満たす。第５の光学補償層２５は、面内遅相軸２５ａが第２の偏光子１２の吸収軸１２ａと実質的に平行である。第６の光学補償層２６は、第１の光学補償層２１と同様に、面内位相差Ｒｅが１５ｎｍ以下であり、かつ、厚み方向位相差Ｒｔｈが－６０ｎｍ以下である。 <Laminated structure 1-2>
FIG. 5 is a schematic cross-sectional view of the liquid crystal display device according to the multilayer structure 1-2 in the first embodiment. FIG. 6 is a schematic perspective view of the liquid crystal display device according to the layered structure 1-2 of the first embodiment.
As shown in FIGS. 5 and 6, the liquid crystal display device 1 of the present embodiment further includes a fifth optical compensation layer 25 and a sixth optical compensation layer 26, and the first polarizer 11 and the first optical compensation. Layer 21, second optical compensation layer 22, third optical compensation layer 23, liquid crystal cell 30, fourth optical compensation layer 24, fifth optical compensation layer 25, sixth optical compensation layer 26, and The two polarizers 12 may be arranged in this order. Like the second optical compensation layer 22, the fifth optical compensation layer 25 has an in-plane retardation Re of 40 to 120 nm and satisfies 1 ≦ Nz ≦ 4. The fifth optical compensation layer 25 has the in-plane slow axis 25 a substantially parallel to the absorption axis 12 a of the second polarizer 12. Similar to the first optical compensation layer 21, the sixth optical compensation layer 26 has an in-plane retardation Re of 15 nm or less and a thickness direction retardation Rth of -60 nm or less.
本積層構造によれば、積層構造１－１に比べて、より優れた視野角特性を発揮することができる。他方、液晶表示装置１の薄型化及び製造コストの観点からは、本積層構造に比べて、積層構造１－１の方が好ましい。また、本積層構造では、第５～第６の光学補償層２５～２６の材料として、溶剤に対する耐久性が高い材料を選択できることから、偏光板（円偏光板３及び４）へ溶剤が付着した時のとしても、第１～第６の光学補償層２１～２６が第１又は第２の偏光子１１又は１２から剥離することを抑制できるとともに、剥離及び第１～第６の光学補償層２１～２６の破断の発生を抑制することができる。 According to the present laminated structure, it is possible to exhibit more excellent viewing angle characteristics than the laminated structure 1-1. On the other hand, from the viewpoint of thinning of the liquid crystal display device 1 and the manufacturing cost, the laminated structure 1-1 is more preferable than the present laminated structure. Further, in the present laminated structure, since the material having high durability to the solvent can be selected as the material of the fifth to sixth optical compensation layers 25 to 26, the solvent is attached to the polarizing plates (circularly polarizing plates 3 and 4) At the same time, peeling of the first to sixth optical compensation layers 21 to 26 from the first or second polarizer 11 or 12 can be suppressed, and peeling and the first to sixth optical compensation layers 21 can be suppressed. It is possible to suppress the occurrence of breakage of ̃26.
積層構造１－２では、第１及び第６の光学補償層２１及び２６は、各々、厚み方向位相差Ｒｔｈが－１５０～－８０ｎｍ（より好ましくは－１２０～－９０ｎｍ）であり、第２及び第５の光学補償層２２及び２５は、各々、面内位相差Ｒｅが４０～９０ｎｍ（より好ましくは４０～６０ｎｍ）であり、かつ、１≦Ｎｚ≦１．４（より好ましくは１≦Ｎｚ≦１．２）を満たし、第３の光学補償層２３は、１．４≦Ｎｚ≦２．４（より好ましくは１．５≦Ｎｚ≦１．８）を満たし、第４の光学補償層２４は、１．４≦Ｎｚ≦２．４（より好ましくは２≦Ｎｚ≦２．３）を満たすことが好ましい。 In the laminated structure 1-2, the first and sixth optical compensation layers 21 and 26 each have a thickness direction retardation Rth of −150 to −80 nm (more preferably −120 to −90 nm), and The fifth optical compensation layers 22 and 25 each have an in-plane retardation Re of 40 to 90 nm (more preferably 40 to 60 nm), and 1 ≦ Nz ≦ 1.4 (more preferably 1 ≦ Nz ≦). 1.2, the third optical compensation layer 23 satisfies 1.4 ≦ Nz ≦ 2.4 (more preferably 1.5 ≦ Nz ≦ 1.8), and the fourth optical compensation layer 24 It is preferable to satisfy 1.4 ≦ Nz ≦ 2.4 (more preferably 2 ≦ Nz ≦ 2.3).
本積層構造では、第５の光学補償層２５は、第６の光学補償層２６に隣接配置されることが好ましく、第４の光学補償層２４は、第５の光学補償層２５に隣接配置されることが好ましい。また、第１の偏光子１１は、第１の光学補償層２１に隣接配置されていてもよく、第３の光学補償層２３及び第４の光学補償層２４は、液晶セル３０に隣接配置されていてもよく、第２の偏光子１２は、第６の光学補償層２６に隣接配置されていてもよい。 In the present laminated structure, the fifth optical compensation layer 25 is preferably disposed adjacent to the sixth optical compensation layer 26, and the fourth optical compensation layer 24 is disposed adjacent to the fifth optical compensation layer 25. Is preferred. Further, the first polarizer 11 may be disposed adjacent to the first optical compensation layer 21, and the third optical compensation layer 23 and the fourth optical compensation layer 24 are disposed adjacent to the liquid crystal cell 30. The second polarizer 12 may be disposed adjacent to the sixth optical compensation layer 26.
第５の光学補償層２５は、上述のように、面内遅相軸２５ａが第２の偏光子１２の吸収軸１２ａと実質的に平行である。ここで、面内遅相軸２５ａが吸収軸１２ａと実質的に平行であるとは、より具体的には、２つの軸のなす角度が０±３°の範囲内であることを意味し、好ましくは０±１°の範囲内であり、より好ましくは０±０．５°の範囲内であり、特に好ましくは０°（完全に平行）である。 As described above, in the fifth optical compensation layer 25, the in-plane slow axis 25 a is substantially parallel to the absorption axis 12 a of the second polarizer 12. Here, that the in-plane slow axis 25a is substantially parallel to the absorption axis 12a more specifically means that the angle between the two axes is in the range of 0 ± 3 °, It is preferably in the range of 0 ± 1 °, more preferably in the range of 0 ± 0.5 °, and particularly preferably 0 ° (perfectly parallel).
＜第５の光学補償層＞
第５の光学補償層２５は、上述のように、４０ｎｍ≦Ｒｅ≦１２０ｎｍ、かつ、１≦Ｎｚ≦４を満たす。第５の光学補償層２５は、１≦Ｎｚ≦１．４を満たすことが好ましく、１≦Ｎｚ≦１．１５を満たすことがより好ましく、実質的にＮｚ＝１を満たすことが特に好ましい。ここで、実質的にＮｚ＝１を満たすとは、より具体的には、１≦Ｎｚ≦１．０５を満たすことを意味する。このように、第５の光学補償層２５は、ｎｘ＞ｎｚ＞ｎｙの屈折率の関係を有する光学補償層（所謂ポジティブＢプレート）、又は、ｎｘ＞ｎｚ＝ｎｙの屈折率の関係を有する光学補償層（所謂ポジティブＡプレート）であってもよいが、後者（ポジティブＡプレート）であることが好ましい。第５の光学補償層２５の面内位相差Ｒｅについては、他の部材の光学パラメータ応じて上記範囲内において適宜設定可能である。 <Fifth Optical Compensation Layer>
As described above, the fifth optical compensation layer 25 satisfies 40 nm ≦ Re ≦ 120 nm and 1 ≦ Nz ≦ 4. The fifth optical compensation layer 25 preferably satisfies 1 ≦ Nz ≦ 1.4, more preferably 1 ≦ Nz ≦ 1.15, and particularly preferably substantially satisfying Nz = 1. Here, substantially satisfying Nz = 1 means, more specifically, satisfying 1 ≦ Nz ≦ 1.05. Thus, the fifth optical compensation layer 25 is an optical compensation layer (so-called positive B plate) having a refractive index relationship of nx>nz> ny, or an optical component having a refractive index relationship of nx> nz = ny. It may be a compensation layer (so-called positive A plate), but is preferably the latter (positive A plate). The in-plane retardation Re of the fifth optical compensation layer 25 can be appropriately set within the above range according to the optical parameters of the other members.
＜第６の光学補償層＞
第６の光学補償層２６は、上述のように、Ｒｅ≦１５ｎｍ、かつ、Ｒｔｈ≦－６０ｎｍを満たす。第６の光学補償層２６の面内位相差Ｒｅは、０～１０ｎｍであることが好ましく、０～５ｎｍであることがより好ましく、０～３ｎｍであることが更に好ましく、０～１ｎｍであることが特に好ましい。このように、第６の光学補償層２６は、ｎｚ＞ｎｘ＝ｎｙの屈折率の関係を有する光学補償層（所謂ポジティブＣプレート）であることが好ましい。なお、第６の光学補償層２６の厚み方向位相差Ｒｔｈについては、他の部材の光学パラメータに応じて上記範囲内において適宜設定可能である。また、第６の光学補償層２６は、面内位相差Ｒｅが１５ｎｍ以下等、充分小さい場合、面内では実質的に光学的に等方性と見なせるため、第６の光学補償層２６の面内における配置方向は特に限定されない。 <Sixth optical compensation layer>
As described above, the sixth optical compensation layer 26 satisfies Re ≦ 15 nm and Rth ≦ −60 nm. The in-plane retardation Re of the sixth optical compensation layer 26 is preferably 0 to 10 nm, more preferably 0 to 5 nm, still more preferably 0 to 3 nm, and further preferably 0 to 1 nm. Is particularly preferred. Thus, the sixth optical compensation layer 26 is preferably an optical compensation layer (so-called positive C plate) having a refractive index relationship of nz> nx = ny. The thickness direction retardation Rth of the sixth optical compensation layer 26 can be appropriately set within the above range according to the optical parameters of the other members. The sixth optical compensation layer 26 can be regarded as substantially optically isotropic in the plane when the in-plane retardation Re is sufficiently small, such as 15 nm or less, so the surface of the sixth optical compensation layer 26 is The arrangement direction in the inside is not particularly limited.
＜第５～第６の光学補償層の材料及び形成方法＞
第５～第６の光学補償層２５～２６の材料及び形成方法としては、上述の第１～第４の光学補償層２１～２４と同様のものが挙げられる。なかでも、第５の光学補償層２５としては、シクロオレフィン系樹脂を延伸したもの、セルロース系樹脂、特にトリアセチルセルロースを延伸したもの、（メタ）アクリル系樹脂を延伸したもの、及び、重合性液晶を基材（基板）と平行に配向させて重合したものが好適であり、第６の光学補償層２６としては、重合性液晶を基材（基板）と平行に配向させて重合したものが好適である。
＜積層構造１－３＞
図７は、実施形態１の積層構造１－３に係る液晶表示装置の断面模式図である。図８は、実施形態１の積層構造１－３に係る液晶表示装置の斜視模式図である。
図７及び８に示すように、本実施形態の液晶表示装置１は、第７の光学補償層２７及び第８の光学補償層２８を更に備え、第１の偏光子１１、第１の光学補償層２１、第２の光学補償層２２、第３の光学補償層２３、第７の光学補償層２７、液晶セル３０、第８の光学補償層２８、第４の光学補償層２４、第５の光学補償層２５、第６の光学補償層２６、及び、第２の偏光子１２は、この順に配置されてもよい。第７の光学補償層２７及び第８の光学補償層２８は、各々、面内位相差Ｒｅが１５ｎｍ以下であり、厚み方向位相差Ｒｔｈが５０～３００ｎｍであり、かつ、Ｎｚ＞１を満たす。 <Material and Method of Forming Fifth to Sixth Optical Compensation Layers>
Examples of materials and formation methods of the fifth to sixth optical compensation layers 25 to 26 include the same ones as those of the first to fourth optical compensation layers 21 to 24 described above. Among them, as the fifth optical compensation layer 25, one obtained by drawing a cycloolefin resin, one obtained by drawing a cellulose resin, particularly triacetyl cellulose, one obtained by drawing a (meth) acrylic resin, and It is preferable that the liquid crystal is aligned and parallel to the base material (substrate) and polymerized, and as the sixth optical compensation layer 26, one obtained by aligning and polymerizing the polymerizable liquid crystal parallel to the base material (substrate) It is suitable.
<Laminated structure 1-3>
FIG. 7 is a schematic cross-sectional view of the liquid crystal display device according to the layered structure 1-3 of the first embodiment. FIG. 8 is a schematic perspective view of the liquid crystal display device according to the layered structure 1-3 of the first embodiment.
As shown in FIGS. 7 and 8, the liquid crystal display device 1 of the present embodiment further includes a seventh optical compensation layer 27 and an eighth optical compensation layer 28, and the first polarizer 11, the first optical compensation. Layer 21, second optical compensation layer 22, third optical compensation layer 23, seventh optical compensation layer 27, liquid crystal cell 30, eighth optical compensation layer 28, fourth optical compensation layer 24, fifth The optical compensation layer 25, the sixth optical compensation layer 26, and the second polarizer 12 may be disposed in this order. The seventh optical compensation layer 27 and the eighth optical compensation layer 28 each have an in-plane retardation Re of 15 nm or less, a thickness direction retardation Rth of 50 to 300 nm, and satisfy Nz> 1.
本積層構造によれば、積層構造１－１に比べて、全方位的な偏りの少ない視野角特性を発揮することができる。他方、液晶表示装置１の薄型化及び製造コストの観点からは、本積層構造に比べて、積層構造１－１の方が好ましい。また、本積層構造では、第７～第８の光学補償層２７～２８の材料として、溶剤に対する耐久性が高い材料を選択できることから、偏光板（円偏光板３及び４）へ溶剤が付着した時のとしても、第１～第８の光学補償層２１～２８が第１又は第２の偏光子１１又は１２から剥離することを抑制できるとともに、剥離及び第１～第８の光学補償層２１～２８の破断の発生を抑制することができる。 According to the present laminated structure, compared to the laminated structure 1-1, it is possible to exhibit viewing angle characteristics with less omnidirectional bias. On the other hand, from the viewpoint of thinning of the liquid crystal display device 1 and the manufacturing cost, the laminated structure 1-1 is more preferable than the present laminated structure. Further, in the present laminated structure, since the material having high durability to the solvent can be selected as the material of the seventh to eighth optical compensation layers 27 to 28, the solvent is attached to the polarizing plates (circularly polarizing plates 3 and 4) At the same time, peeling of the first to eighth optical compensation layers 21 to 28 from the first or second polarizer 11 or 12 can be suppressed, and peeling and the first to eighth optical compensation layers 21 can be suppressed. It is possible to suppress the occurrence of breakage of ̃28.
積層構造１－３では、第１及び第６の光学補償層２１及び２６は、各々、厚み方向位相差Ｒｔｈが－１５０～－８０ｎｍ（より好ましくは－１２０～－９０ｎｍ）であり、第２及び第５の光学補償層２２及び２５は、各々、面内位相差Ｒｅが４０～９０ｎｍ（より好ましくは４５～６０ｎｍ）であり、かつ、１≦Ｎｚ≦１．４（より好ましくは１≦Ｎｚ≦１．２）を満たし、第３及び第４の光学補償層２３及び２４は、各々、１≦Ｎｚ≦１．４（より好ましくは１≦Ｎｚ≦１．２）を満たすことが好ましい。 In the layered structure 1-3, the first and sixth optical compensation layers 21 and 26 each have a thickness direction retardation Rth of −150 to −80 nm (more preferably −120 to −90 nm), and The fifth optical compensation layers 22 and 25 each have an in-plane retardation Re of 40 to 90 nm (more preferably 45 to 60 nm), and 1 ≦ Nz ≦ 1.4 (more preferably 1 ≦ Nz ≦). It is preferable to satisfy 1.2), and the third and fourth optical compensation layers 23 and 24 each satisfy 1 ≦ Nz ≦ 1.4 (more preferably 1 ≦ Nz ≦ 1.2).
本積層構造では、第５の光学補償層２５は、第６の光学補償層２６に隣接配置されることが好ましく、第４の光学補償層２４は、第５の光学補償層２５に隣接配置されることが好ましく、第７の光学補償層２７は、第３の光学補償層２３に隣接配置されることが好ましく、第８の光学補償層２８は、第４の光学補償層２４に隣接配置されることが好ましい。また、第１の偏光子１１は、第１の光学補償層２１に隣接配置されていてもよく、第７及び第８の光学補償層２７及び２８は、液晶セル３０に隣接配置されていてもよく、第２の偏光子１２は、第６の光学補償層２６に隣接配置されていてもよい。 In the present laminated structure, the fifth optical compensation layer 25 is preferably disposed adjacent to the sixth optical compensation layer 26, and the fourth optical compensation layer 24 is disposed adjacent to the fifth optical compensation layer 25. The seventh optical compensation layer 27 is preferably disposed adjacent to the third optical compensation layer 23, and the eighth optical compensation layer 28 is disposed adjacent to the fourth optical compensation layer 24. Is preferred. The first polarizer 11 may be disposed adjacent to the first optical compensation layer 21, and the seventh and eighth optical compensation layers 27 and 28 may be disposed adjacent to the liquid crystal cell 30. The second polarizer 12 may be disposed adjacent to the sixth optical compensation layer 26.
＜第７及び第８の光学補償層＞
第７及び第８の光学補償層２７及び２８は、上述のように、各々、Ｒｅ≦１５ｎｍ、５０ｎｍ≦Ｒｔｈ≦３００ｎｍ、かつ、Ｎｚ＞１を満たす。第７及び第８の光学補償層２７及び２８の各面内位相差Ｒｅは、０～１０ｎｍであることが好ましく、０～５ｎｍであることがより好ましく、０～３ｎｍであることが更に好ましく、０～１ｎｍであることが特に好ましい。このように、第７及び第８の光学補償層２７及び２８は、ｎｘ＝ｎｙ＞ｎｚの屈折率の関係を有する光学補償層（所謂ネガティブＣプレート）であることが好ましい。なお、第７及び第８の光学補償層２７及び２８の各厚み方向位相差Ｒｔｈについては、他の部材の光学パラメータに応じて上記範囲内において適宜設定可能である。また、第７及び第８の光学補償層２７及び２８は、面内位相差Ｒｅが１５ｎｍ以下等、充分小さい場合、面内では実質的に光学的に等方性と見なせるため、第７及び第８の光学補償層２７及び２８の面内における配置方向は特に限定されない。 <Seventh and Eighth Optical Compensation Layers>
As described above, the seventh and eighth optical compensation layers 27 and 28 satisfy Re ≦ 15 nm, 50 nm ≦ Rth ≦ 300 nm, and Nz> 1. The in-plane retardation Re of each of the seventh and eighth optical compensation layers 27 and 28 is preferably 0 to 10 nm, more preferably 0 to 5 nm, and still more preferably 0 to 3 nm. Particularly preferred is 0 to 1 nm. Thus, the seventh and eighth optical compensation layers 27 and 28 are preferably optical compensation layers (so-called negative C plates) having a refractive index relationship of nx = ny> nz. The thickness direction retardation Rth of the seventh and eighth optical compensation layers 27 and 28 can be appropriately set within the above range according to the optical parameters of the other members. The seventh and eighth optical compensation layers 27 and 28 can be regarded as substantially optically isotropic in the plane when the in-plane retardation Re is sufficiently small, such as 15 nm or less. The arrangement direction of the eight optical compensation layers 27 and 28 in the plane is not particularly limited.
第７及び第８の光学補償層２７及び２８の厚み方向位相差Ｒｔｈは、互いに異なっていても同じであってもよく、いずれの場合も両者の厚み方向位相差Ｒｔｈの合計が同じであれば同様に機能することができる。第７及び第８の光学補償層２７及び２８の厚み方向位相差Ｒｔｈの合計は、１００ｎｍ以上、３００ｎｍ以下であることが好ましく、１５０ｎｍ以上、２５０ｎｍ以下であることがより好ましい。 The thickness direction retardations Rth of the seventh and eighth optical compensation layers 27 and 28 may be different from each other or may be the same, and in any case, the sum of the thickness direction retardations Rth of the both is the same. It can function as well. The total of the thickness direction retardations Rth of the seventh and eighth optical compensation layers 27 and 28 is preferably 100 nm or more and 300 nm or less, and more preferably 150 nm or more and 250 nm or less.
＜第７～第８の光学補償層の材料及び形成方法＞
第７～第８の光学補償層２７～２８の材料及び形成方法としては、上述の第１～第４の光学補償層２１～２４と同様のものが挙げられる。なかでも、第７～第８の光学補償層２７～２８としては、シクロオレフィン系樹脂を延伸したもの、及び、セルロース系樹脂、特にトリアセチルセルロースを延伸したもの、（メタ）アクリル系樹脂を延伸したものが好適である。 <Materials and Forming Methods of Seventh to Eighth Optical Compensation Layers>
Examples of materials and forming methods of the seventh to eighth optical compensation layers 27 to 28 include the same ones as those of the first to fourth optical compensation layers 21 to 24 described above. Among them, as the seventh to eighth optical compensation layers 27 to 28, those obtained by stretching a cycloolefin resin, and those obtained by stretching a cellulose resin, particularly triacetyl cellulose, and a (meth) acrylic resin Are preferred.
以上、本発明の実施形態について説明したが、説明された個々の事項は、すべて本発明全般に対して適用され得るものである。 Although the embodiments of the present invention have been described above, all the individual matters described can be applied to the whole of the present invention.
以下に実施例及び比較例を掲げて本発明を更に詳細に説明するが、本発明はこれらの実施例のみに限定されるものではない。なお、以下の各実施例及び比較例では、各軸方向は、液晶パネルの表示領域の右方向を０°とし、観察面側から見て反時計回りを正としたときの角度で表している。 EXAMPLES The present invention will be described in more detail by way of the following Examples and Comparative Examples, but the present invention is not limited to these Examples. In each of the following Examples and Comparative Examples, each axial direction is represented by an angle when the right direction of the display area of the liquid crystal panel is 0 ° and the counterclockwise direction is positive when viewed from the viewing surface side. .
＜実施例１＞
図９は、実施例１に係る液晶表示装置の断面模式図である。
図９に示すように、表偏光子、ポジティブＣプレートとしての第１の光学補償層、ポジティブＡプレートとしての第２の光学補償層、λ／４位相差板としての第３の光学補償層、液晶セル、λ／４位相差板としての第４の光学補償層、及び、裏偏光子が観察面側からこの順の配置された液晶パネルと、液晶パネルの背面側のバックライト（図示せず）とを備える実施例１の液晶表示装置を作製した。各部材の光学パラメータと、各偏光子及び各光学補償層の軸方向とは、図９に示した通りである。本実施例では、表偏光子が上記第１の偏光子に対応し、裏偏光子が上記第２の偏光子に対応する。 Example 1
FIG. 9 is a schematic cross-sectional view of the liquid crystal display device according to the first embodiment.
As shown in FIG. 9, a front polarizer, a first optical compensation layer as a positive C plate, a second optical compensation layer as a positive A plate, a third optical compensation layer as a λ / 4 retardation plate, A liquid crystal cell, a fourth optical compensation layer as a λ / 4 retardation plate, a liquid crystal panel in which a back polarizer is disposed in this order from the observation surface side, and a backlight (not shown) of the liquid crystal panel And the liquid crystal display device of Example 1 is provided. The optical parameters of the respective members and the axial directions of the respective polarizers and the respective optical compensation layers are as shown in FIG. In this embodiment, the front polarizer corresponds to the first polarizer, and the back polarizer corresponds to the second polarizer.
液晶セルとしては、ＶＡモードの液晶セルを用いた。液晶材料の誘電率異方性Δｎは、０．１１３、セル厚み（セルギャップ）ｄは、３．２μｍとした。すなわち、液晶層のリタデーションΔｎ・ｄは、３６０ｎｍとした。 As the liquid crystal cell, a VA mode liquid crystal cell was used. The dielectric anisotropy Δn of the liquid crystal material is 0.113, and the cell thickness (cell gap) d is 3.2 μm. That is, the retardation Δn · d of the liquid crystal layer was 360 nm.
第２～第４の光学補償層としては、ＣＯＰフィルムを２軸延伸することによって図９に記載の所定の光学パラメータが得られたフィルムを用いた。第１の光学補償層としては、第２の光学補償層上に液晶性材料を塗布することによって図９に記載の所定の光学パラメータが得られたフィルムを用いた。なお、各実施例及び比較例において、ＣＯＰフィルムは、シクロオレフィンコポリマー（ＣＯＣ）を含まないものを用いた。 As the second to fourth optical compensation layers, films in which predetermined optical parameters shown in FIG. 9 were obtained by biaxially stretching a COP film were used. As the first optical compensation layer, a film having a predetermined optical parameter shown in FIG. 9 obtained by applying a liquid crystalline material on the second optical compensation layer was used. In each of the examples and the comparative examples, the COP film used did not contain cycloolefin copolymer (COC).
表偏光子及び裏偏光子としては、ＴＡＣフィルム、ＰＶＡフィルム及びＣＯＰフィルムを、接着剤を介してこの順に積層したものを用いた。表偏光子及び裏偏光子のＣＯＰフィルムは、光学異方性を持たないように作製した。表偏光子及び裏偏光子は、ＣＯＰフィルムが液晶セル側、ＴＡＣフィルムが液晶セルと反対側になるように配置した。表偏光子及び裏偏光子のＰＶＡフィルムとしては、延伸後にヨウ素を添加することで偏光性能を持つものを用いた。このフィルムは、延伸方向に吸収軸を持つ。 As a front polarizer and a back polarizer, what laminated | stacked the TAC film, the PVA film, and the COP film in this order through the adhesive agent was used. The COP films of the front polarizer and the back polarizer were produced so as not to have optical anisotropy. The front polarizer and the back polarizer were disposed such that the COP film was on the liquid crystal cell side and the TAC film was on the opposite side to the liquid crystal cell. As a PVA film of a front polarizer and a back polarizer, what has a polarization performance by adding iodine after extending | stretching was used. This film has an absorption axis in the stretching direction.
なお、ＴＡＣフィルムは、ＰＶＡフィルムの支持体として広く使われており、ＰＶＡフィルムと接着し、フィルムとしての強度を保つ。また、ＣＯＰフィルムは、広帯域の位相差フィルムとして、また、ＰＶＡフィルムの支持体としても広く使われており、延伸することで複屈折性を持つ。 In addition, a TAC film is widely used as a support body of a PVA film, adhere | attaches with a PVA film, and maintains the intensity | strength as a film. In addition, a COP film is widely used as a broad-band retardation film or as a support of a PVA film, and has birefringence by stretching.
また、図９では省略しているが、表偏光子と第１の光学補償層の間、第２の光学補償層と第３の光学補償層の間、第３の光学補償層と液晶セルの間、液晶セルと第４の光学補償層の間、及び、第４の光学補償層と裏偏光子の間は、それぞれ、大きな光学異方性を持たない感圧接着剤（粘着材）で満たした。このような粘着材等、大きな光学異方性を持たない材料は、その材料から形成された層が光学異方性を持たない層である限り、製法上の必要に応じて加えることも、省くこともできる。 Further, although not shown in FIG. 9, between the front polarizer and the first optical compensation layer, between the second optical compensation layer and the third optical compensation layer, and between the third optical compensation layer and the liquid crystal cell. Between the liquid crystal cell and the fourth optical compensation layer, and between the fourth optical compensation layer and the back polarizer, respectively, with a pressure sensitive adhesive (adhesive material) having no large optical anisotropy. The Such materials that do not have large optical anisotropy, such as adhesive materials, are also omitted from the process of adding them as needed in the manufacturing process as long as the layer formed from the material is a layer without optical anisotropy. It can also be done.
なお、実施例１は観察面側に第１及び第２の光学補償層を配置しているが、これらは背面側に配置されてもよい。また、各偏光子と各光学補償層は、軸の相対角度を保ったまま回転してもよく、線対称に移動してもよい。 Although the first and second optical compensation layers are disposed on the viewing surface side in the first embodiment, they may be disposed on the back surface side. In addition, each polarizer and each optical compensation layer may be rotated while maintaining the relative angle of the axes, or may be moved in line symmetry.
＜比較例１＞
図１０は、比較例１に係る液晶表示装置の断面模式図である。
図１０に示すように、第１及び第２の光学補償層の代わりに、ポジティブＢプレートとしての第９の光学補償層を用いたことを除いて、実施例１と同様にして本比較例の液晶表示装置を作製した。第９の光学補償層としては、ＣＯＰフィルムを延伸後緩和することによって図１０に記載の所定の光学パラメータが得られたフィルムを用いた。 Comparative Example 1
FIG. 10 is a schematic cross-sectional view of a liquid crystal display device according to Comparative Example 1.
As shown in FIG. 10, in the same manner as in Example 1 except that a ninth optical compensation layer as a positive B plate was used instead of the first and second optical compensation layers. A liquid crystal display was produced. As the ninth optical compensation layer, a film having predetermined optical parameters shown in FIG. 10 by stretching and relaxing the COP film was used.
＜実施例１及び比較例１の比較＞
比較例１の構成とする場合、第９の光学補償層として、ｎｚ＞ｎｘ＞ｎｙ、すなわちＮｚ＜１となるフィルムが必要になるが、その材料及び製法は限られる。例えば、Ｎｚ＜１のフィルムの製造方法として、特許文献６に開示されるような、延伸と緩和を組み合わせた製法が提案されている。しかしながら、近年、特に車載の液晶表示装置において、高温や高温高湿、低温といった過酷な環境に対する高い耐久性を求められている。また、溶剤に対する耐久性や、パネルの薄型化を求められるようになっているが、このような製法で作製されたフィルムを用いる場合、上記（１）～（３）のような課題を解決し、かつ、コスト面でも有利な材料を選定することが難しいと考えられる。それに対して、位相差フィルムの作製方法として一般的な、延伸方向に１軸、又は、延伸方向と、延伸方向とは異なる方向との２軸で延伸する方法であれば、上記（１）～（３）のような課題が解決された、あるいは影響が小さい材料を選択することができる。実施例１で使用した第２の光学補償層のように、Ｒｅ＝８５ｎｍ、Ｒｔｈ＝４２ｎｍかつＮｚ＝１．０を満たすフィルムは、例えばシクロオレフィン系樹脂により実現可能であり、上記（１）～（３）のような問題が小さいことがわかっている。 Comparison of Example 1 and Comparative Example 1
In the case of the configuration of Comparative Example 1, a film satisfying nz>nx> ny, that is, Nz <1 is required as the ninth optical compensation layer, but the material and manufacturing method thereof are limited. For example, as a method of producing a film of Nz <1, a method of combining stretching and relaxation as disclosed in Patent Document 6 has been proposed. However, in recent years, high durability to severe environments such as high temperature, high temperature and high humidity, and low temperature has been required particularly for liquid crystal display devices mounted in vehicles. In addition, durability against solvents and thinning of panels are required, but when using a film produced by such a method, the problems as described in (1) to (3) above are solved. And, it is considered difficult to select an advantageous material also in terms of cost. On the other hand, if it is a method of uniaxially stretching in a stretching direction, or biaxially stretching in a stretching direction and a direction different from the stretching direction as a method for producing a retardation film, the above (1) to It is possible to select a material which has solved the problem such as (3) or has less influence. A film satisfying Re = 85 nm, Rth = 42 nm, and Nz = 1.0 as in the second optical compensation layer used in Example 1 can be realized by, for example, a cycloolefin resin, and It is known that the problem like (3) is small.
＜実施例１及び比較例１の評価結果＞
実施例１及び比較例１の液晶表示装置の暗室コントラストを測定した。暗室コントラストは、外光が無い状態で白表示と黒表示の輝度を測定し、白表示輝度を黒表示輝度で割ったものであり、表示装置としては高いほど好ましい。更に、耐久性の観点から言えば、高温等の過酷な環境に晒されたときにこの数値の変化が小さいほど好ましい。 <Evaluation Results of Example 1 and Comparative Example 1>
The dark room contrast of the liquid crystal display of Example 1 and Comparative Example 1 was measured. The dark room contrast is obtained by measuring the luminance of white display and black display without external light, and dividing the white display luminance by the black display luminance. The higher the display device, the better. Furthermore, from the viewpoint of durability, it is preferable that the change in this numerical value be as small as possible when exposed to a severe environment such as high temperature.
下記表１に、実施例１及び比較例１について、８５℃で１２時間のエージングを行った前後での画面中央部での暗室コントラストを示す。エージング前の値には大差ないものの、エージングにより比較例１は大きく数値が低下している。一方、実施例１は変化が小さくなっており、耐久性が向上したことが示された。 Table 1 below shows dark room contrast at the center of the screen before and after aging for 12 hours at 85 ° C. for Example 1 and Comparative Example 1. Although there is not much difference with the value before the aging, the value in Comparative Example 1 is greatly reduced by the aging. On the other hand, in Example 1, the change was small and it was shown that the durability was improved.
Figure JPOXMLDOC01-appb-T000001
Figure JPOXMLDOC01-appb-T000001
実施例１及び比較例１の液晶表示装置の黒表示均一性（Ｂｌａｃｋ　Ｄｉｓｐｌａｙ　Ｕｎｉｆｏｒｍｉｔｙ）を測定した。黒表示均一性とは、黒表示の所謂ムラの強さを示す指標であり、黒ベタ画面を表示したときの表示領域の輝度をスキャンして最小輝度を最大輝度で割ったものである。この値が１００％に近いほど輝度分布が無い、すなわちムラが弱く、表示装置として好ましい。低いほどムラが強く、表示装置としての品位が低いということになる。 The black display uniformity of the liquid crystal display devices of Example 1 and Comparative Example 1 was measured. The black display uniformity is an index indicating the intensity of so-called unevenness of black display, which is obtained by dividing the minimum luminance by the maximum luminance by scanning the luminance of the display area when a black solid screen is displayed. As this value is closer to 100%, there is no luminance distribution, that is, the unevenness is weak, which is preferable as a display device. The lower the value, the stronger the unevenness and the lower the quality as a display device.
下記表２に、実施例１及び比較例１について、８５℃で１２時間のエージングを行った前後での黒表示均一性を示す。エージング前の値には大差ないものの、エージングにより比較例１は大きく数値が低下している。一方、実施例１は変化が小さくなっており、耐久性が向上したことが示された。 Table 2 below shows black display uniformity before and after aging for 12 hours at 85 ° C. for Example 1 and Comparative Example 1. Although there is not much difference with the value before the aging, the value in Comparative Example 1 is greatly reduced by the aging. On the other hand, in Example 1, the change was small and it was shown that the durability was improved.
Figure JPOXMLDOC01-appb-T000002
Figure JPOXMLDOC01-appb-T000002
図１１及び１２に、それぞれ、実施例１及び比較例１に係る液晶表示装置の視野角特性をシミュレーションした結果（等コントラスト比等高線）を示す。なお、各等コントラスト比等高線ではコントラストが１００又は１０００である箇所をそれぞれ実線で示している。図１１及び１２に示されるように、視野角特性に優れる方向が異なるが、それについては偏光子の軸の回転等により調整可能である。それを考慮すれば実施例１は比較例１とほぼ同等か、やや優勢な視野角特性を持つことが示されている。 FIGS. 11 and 12 show the simulation results (isocontrast ratio contour lines) of the viewing angle characteristics of the liquid crystal display according to Example 1 and Comparative Example 1, respectively. In each of the equal contrast ratio contour lines, portions where the contrast is 100 or 1000 are indicated by solid lines. As shown in FIGS. 11 and 12, although the direction in which the viewing angle characteristics are excellent is different, it can be adjusted by, for example, the rotation of the axis of the polarizer. In consideration of that, it is shown that Example 1 has a viewing angle characteristic which is almost equal to or slightly superior to Comparative Example 1.
＜表偏光子の吸収軸と第２の光学補償層の遅相軸との関係＞
実施例１と同じ構成において、第２の光学補償層の遅相軸の方向を変えて法線コントラスト及び視野角特性をシミュレーションした結果を示す。下記表３に、相対角度を変えて算出した法線コントラストを示す。相対角度とは、表偏光子の吸収軸に対する第２の光学補償層の遅相軸のなす角度であり、上記角度ｘに相当する。表偏光子の吸収軸は固定し、第２の光学補償層の遅相軸を変更した。表３に示すように、相対角度が９０°及び０°又は１８０°から外れるとコントラストが低下するが、９０°でも０°又は１８０°でも法線コントラストは高くなっている。 <Relationship between the absorption axis of the front polarizer and the slow axis of the second optical compensation layer>
In the same structure as Example 1, the result of having simulated the direction of the slow axis of the 2nd optical compensation layer, and simulated normal contrast and viewing angle characteristics is shown. Table 3 below shows the normal contrast calculated by changing the relative angle. The relative angle is an angle formed by the slow axis of the second optical compensation layer with respect to the absorption axis of the front polarizer, and corresponds to the above-mentioned angle x. The absorption axis of the front polarizer was fixed, and the slow axis of the second optical compensation layer was changed. As shown in Table 3, when the relative angle deviates from 90 ° and 0 ° or 180 °, the contrast decreases, but the normal contrast becomes high at 90 ° or 0 ° or 180 °.
Figure JPOXMLDOC01-appb-T000003
Figure JPOXMLDOC01-appb-T000003
図１３は、参考例１に係る液晶表示装置の等コントラスト比等高線である。参考例１は、第２の光学補償層の遅相軸を表偏光子の吸収軸に対して９０°をなす方向に配置したことを除いて、実施例１と同じ構成を有する。図１１に示したように、相対角度が０°（又は１８０°）であれば、視野角特性は良好になるが、図１３に示されるように、相対角度が９０°であれば、視野角特性は悪化するため実用に適さない。 FIG. 13 is an iso-contrast ratio contour line of the liquid crystal display device according to the first reference example. The reference example 1 has the same configuration as that of the example 1 except that the slow axis of the second optical compensation layer is disposed in a direction forming an angle of 90 ° with the absorption axis of the front polarizer. As shown in FIG. 11, if the relative angle is 0 ° (or 180 °), the viewing angle characteristics will be good, but as shown in FIG. 13, if the relative angle is 90 °, the viewing angle Properties are not suitable for practical use because of deterioration.
以上より、法線コントラスト及び視野角特性を良好に保つためには、表偏光子（第１の偏光子）の吸収軸に対する第２の光学補償層の遅相軸のなす角度Ｘは、－５°＜Ｘ＜５°の範囲にすることが好ましい。 From the above, in order to maintain the normal contrast and the viewing angle characteristics well, the angle X between the slow axis of the second optical compensation layer and the absorption axis of the front polarizer (first polarizer) is -5. It is preferable to set the range of ° <X <5 °.
＜実施例２＞
図１４は、実施例２に係る液晶表示装置の断面模式図である。
図１４に示すように、表偏光子、ポジティブＣプレートとしての第１の光学補償層、ポジティブＡプレートとしての第２の光学補償層、λ／４位相差板としての第３の光学補償層、液晶セル、λ／４位相差板としての第４の光学補償層、ポジティブＡプレートとしての第５の光学補償層、ポジティブＣプレートとしての第６の光学補償層、及び、裏偏光子が観察面側からこの順の配置された液晶パネルと、液晶パネルの背面側のバックライト（図示せず）とを備える実施例２の液晶表示装置を作製した。各部材の光学パラメータと、各偏光子及び各光学補償層の軸方向とは、図１４に示した通りである。本実施例では、表偏光子が上記第１の偏光子に対応し、裏偏光子が上記第２の偏光子に対応する。 Example 2
FIG. 14 is a schematic cross-sectional view of the liquid crystal display device according to the second embodiment.
As shown in FIG. 14, a front polarizer, a first optical compensation layer as a positive C plate, a second optical compensation layer as a positive A plate, a third optical compensation layer as a λ / 4 retardation plate, Liquid crystal cell, fourth optical compensation layer as λ / 4 retardation plate, fifth optical compensation layer as positive A plate, sixth optical compensation layer as positive C plate, and back polarizer A liquid crystal display device of Example 2 provided with a liquid crystal panel arranged in this order from the side and a back light (not shown) on the back side of the liquid crystal panel was produced. The optical parameters of the respective members and the axial directions of the respective polarizers and the respective optical compensation layers are as shown in FIG. In this embodiment, the front polarizer corresponds to the first polarizer, and the back polarizer corresponds to the second polarizer.
図１４に示したように、本実施例は、実施例１とほぼ同様だが、本実施例では観察面側と背面側とに同様に光学補償層を配置することで更に視野角特性を高めることができる。 As shown in FIG. 14, the present embodiment is substantially the same as the first embodiment, but in the present embodiment, the viewing angle characteristics are further enhanced by similarly arranging the optical compensation layer on the viewing surface side and the back surface side. Can.
液晶セルとしては、ＶＡモードの液晶セルを用いた。液晶材料の誘電率異方性Δｎは、０．１１３、セル厚み（セルギャップ）ｄは、３．２μｍとした。すなわち、液晶層のリタデーションΔｎ・ｄは、３６０ｎｍとした。 As the liquid crystal cell, a VA mode liquid crystal cell was used. The dielectric anisotropy Δn of the liquid crystal material is 0.113, and the cell thickness (cell gap) d is 3.2 μm. That is, the retardation Δn · d of the liquid crystal layer was 360 nm.
第２～第５の光学補償層としては、ＣＯＰフィルムを２軸延伸することによって図１４に記載の所定の光学パラメータが得られたフィルムを用いた。第１及び第６の光学補償層としては、それぞれ、第２及び第５の光学補償層上に液晶性材料を塗布することによって図１４に記載の所定の光学パラメータが得られたフィルムを用いた。 As the second to fifth optical compensation layers, films in which predetermined optical parameters shown in FIG. 14 were obtained by biaxially stretching a COP film were used. As the first and sixth optical compensation layers, films obtained by applying the liquid crystalline material on the second and fifth optical compensation layers and using the predetermined optical parameters shown in FIG. 14 were used. .
表偏光子及び裏偏光子としては、ＴＡＣフィルム、ＰＶＡフィルム及びＣＯＰフィルムを、接着剤を介してこの順に積層したものを用いた。表偏光子及び裏偏光子のＣＯＰフィルムは、光学異方性を持たないように作製した。表偏光子及び裏偏光子は、ＣＯＰフィルムが液晶セル側、ＴＡＣフィルムが液晶セルと反対側になるように配置した。表偏光子及び裏偏光子のＰＶＡフィルムとしては、延伸後にヨウ素を添加することで偏光性能を持つものを用いた。このフィルムは、延伸方向に吸収軸を持つ。 As a front polarizer and a back polarizer, what laminated | stacked the TAC film, the PVA film, and the COP film in this order through the adhesive agent was used. The COP films of the front polarizer and the back polarizer were produced so as not to have optical anisotropy. The front polarizer and the back polarizer were disposed such that the COP film was on the liquid crystal cell side and the TAC film was on the opposite side to the liquid crystal cell. As a PVA film of a front polarizer and a back polarizer, what has a polarization performance by adding iodine after extending | stretching was used. This film has an absorption axis in the stretching direction.
また、図１４では省略しているが、表偏光子と第１の光学補償層の間、第２の光学補償層と第３の光学補償層の間、第３の光学補償層と液晶セルの間、液晶セルと第４の光学補償層の間、第４の光学補償層と第５の光学補償層の間、及び、第６の光学補償層と裏偏光子の間は、それぞれ、大きな光学異方性を持たない感圧接着剤（粘着材）で満たした。このような粘着材等、大きな光学異方性を持たない材料は、その材料から形成された層が光学異方性を持たない層である限り、製法上の必要に応じて加えることも、省くこともできる。 In addition, although omitted in FIG. 14, between the front polarizer and the first optical compensation layer, between the second optical compensation layer and the third optical compensation layer, and between the third optical compensation layer and the liquid crystal cell. Between the liquid crystal cell and the fourth optical compensation layer, between the fourth optical compensation layer and the fifth optical compensation layer, and between the sixth optical compensation layer and the back polarizer, respectively. It filled with the pressure sensitive adhesive (adhesive material) which does not have anisotropy. Such materials that do not have large optical anisotropy, such as adhesive materials, are also omitted from the process of adding them as needed in the manufacturing process as long as the layer formed from the material is a layer without optical anisotropy. It can also be done.
なお、実施例２は観察面側に第１及び第２の光学補償層を配置しているが、これらは背面側に配置されてもよい。また、各偏光子と各光学補償層は、軸の相対角度を保ったまま回転してもよく、線対称に移動してもよい。 Although the first and second optical compensation layers are disposed on the viewing surface side in the second embodiment, they may be disposed on the back surface side. In addition, each polarizer and each optical compensation layer may be rotated while maintaining the relative angle of the axes, or may be moved in line symmetry.
＜実施例２及び比較例１の比較＞
実施例２及び比較例１についても、上記＜実施例１及び比較例１の比較＞と同様のことが言える。 Comparison of Example 2 and Comparative Example 1
The same thing as in the above <Comparison of Example 1 and Comparative Example 1> applies to Example 2 and Comparative Example 1.
＜実施例２及び比較例１の評価結果＞
下記表４に、実施例２及び比較例１について、８５℃で１２時間のエージングを行った前後での画面中央部での暗室コントラストを示す。 <Evaluation Results of Example 2 and Comparative Example 1>
Table 4 below shows dark room contrast at the center of the screen before and after aging for 12 hours at 85 ° C. for Example 2 and Comparative Example 1.
Figure JPOXMLDOC01-appb-T000004
Figure JPOXMLDOC01-appb-T000004
下記表５に、実施例２及び比較例１について、８５℃で１２時間のエージングを行った前後での黒表示均一性を示す。 Table 5 below shows black display uniformity before and after aging for 12 hours at 85 ° C. for Example 2 and Comparative Example 1.
Figure JPOXMLDOC01-appb-T000005
Figure JPOXMLDOC01-appb-T000005
これらの結果、実施例１と同様に、実施例２においても暗室コントラスト及び黒表示均一性のエージング前後の変化は比較例１よりも小さく、耐久性が優れていることを示している。実施例１よりは変化が大きいが、層構成が増えて特性変化が生じやすくなったと推測される。 As a result, as in Example 1, the change in dark room contrast and black display uniformity before and after aging is also smaller in Example 2 than in Comparative Example 1, indicating that the durability is excellent. Although the change is larger than in the first embodiment, it is presumed that the layer structure is increased and the characteristic change is more likely to occur.
図１５に実施例２に係る液晶表示装置の視野角特性をシミュレーションした結果（等コントラスト比等高線）を示す。図１５に示されるように、視野角特性については、本実施例は、実施例１及び比較例１と比べて大きく向上しており、視野角特性の要求によっては本実施例を選択することも可能である。ただし、製造コストについては、本実施例は、実施例１より高くなることが予想される。 FIG. 15 shows the simulation results (isocontrast ratio contour lines) of the viewing angle characteristics of the liquid crystal display device according to the second embodiment. As shown in FIG. 15, regarding the viewing angle characteristics, the present embodiment is greatly improved as compared with the embodiment 1 and the comparative example 1, and it is possible to select the present embodiment depending on the requirement of the viewing angle characteristics. It is possible. However, with regard to the manufacturing cost, this embodiment is expected to be higher than the first embodiment.
＜実施例３＞
図１６は、実施例３に係る液晶表示装置の断面模式図である。
図１６に示すように、表偏光子、ポジティブＣプレートとしての第１の光学補償層、ポジティブＡプレートとしての第２の光学補償層、λ／４位相差板としての第３の光学補償層、ネガティブＣプレートとしての第７の光学補償層、液晶セル、ネガティブＣプレートとしての第８の光学補償層、λ／４位相差板としての第４の光学補償層、ポジティブＡプレートとしての第５の光学補償層、ポジティブＣプレートとしての第６の光学補償層、及び、裏偏光子が観察面側からこの順の配置された液晶パネルと、液晶パネルの背面側のバックライト（図示せず）とを備える実施例３の液晶表示装置について、視野角特性をシミュレーションした。各部材の光学パラメータと、各偏光子及び各光学補償層の軸方向とは、図１６に示した通りである。本実施例では、表偏光子が上記第１の偏光子に対応し、裏偏光子が上記第２の偏光子に対応する。 Example 3
FIG. 16 is a schematic cross-sectional view of the liquid crystal display device according to the third embodiment.
As shown in FIG. 16, a front polarizer, a first optical compensation layer as a positive C plate, a second optical compensation layer as a positive A plate, a third optical compensation layer as a λ / 4 retardation plate, Seventh optical compensation layer as negative C plate, liquid crystal cell, eighth optical compensation layer as negative C plate, fourth optical compensation layer as λ / 4 retardation plate, fifth as positive A plate An optical compensation layer, a sixth optical compensation layer as a positive C plate, a liquid crystal panel in which a back polarizer is disposed in this order from the viewing surface side, and a backlight (not shown) on the back surface of the liquid crystal panel The viewing angle characteristics of the liquid crystal display device of Example 3 including the above were simulated. The optical parameters of the respective members and the axial directions of the respective polarizers and the respective optical compensation layers are as shown in FIG. In this embodiment, the front polarizer corresponds to the first polarizer, and the back polarizer corresponds to the second polarizer.
図１７に実施例３に係る液晶表示装置の視野角特性をシミュレーションした結果（等コントラスト比等高線）を示す。図１７に示されるように、本実施例は、実施例１及び比較例１と比べて、全方位的な偏りの少ない視野角特性を有しており、視野角特性の要求によっては本実施例を選択することも可能である。ただし、製造コストについては、本実施例は、実施例１より高くなることが予想される。 FIG. 17 shows the simulation results (isocontrast ratio contour lines) of the viewing angle characteristics of the liquid crystal display device according to the third embodiment. As shown in FIG. 17, the present embodiment has viewing angle characteristics with less omnidirectional bias as compared to Embodiment 1 and Comparative Example 1, and this embodiment can be used depending on the requirement of the viewing angle characteristics. It is also possible to choose However, with regard to the manufacturing cost, this embodiment is expected to be higher than the first embodiment.
［付記］
本発明の一態様は、第１の偏光子（１１）と、第１の光学補償層（２１）と、第２の光学補償層（２２）と、λ／４位相差板として機能する第３の光学補償層（２３）と、互いに対向する一対の基板（３１、３２）、及び、前記一対の基板（３１、３２）間の液晶層（３３）を含む液晶セル（３０）と、λ／４位相差板として機能する第４の光学補償層（２４）と、第２の偏光子（１２）と、をこの順に備え、前記第１の偏光子（１１）は、吸収軸（１１ａ）が前記第２の偏光子（１２）の吸収軸（１２ａ）に対して実質的に９０°の角度をなし、前記第１の光学補償層（２１）は、面内位相差Ｒｅが１５ｎｍ以下であり、かつ、厚み方向位相差Ｒｔｈが－６０ｎｍ以下であり、前記第２の光学補償層（２２）は、面内位相差Ｒｅが４０～１２０ｎｍであり、１≦Ｎｚ≦４を満たし、かつ、面内遅相軸（２２ａ）が前記第１の偏光子（１１）の吸収軸（１１ａ）と実質的に平行であり、前記第３の光学補償層（２３）は、面内遅相軸（２３ａ）が前記第１の偏光子（１１）の吸収軸（１１ａ）に対して実質的に４５°又は１３５°の角度をなし、前記液晶セル（３０）は、黒表示時に、前記液晶層（３３）中の液晶分子を前記一対の基板（３１、３２）面に対して実質的に垂直に配向し、前記第４の光学補償層（２４）は、面内遅相軸（２４ａ）が前記第３の光学補償層（２３）の面内遅相軸（２３ａ）に対して実質的に９０°の角度をなす液晶表示装置であってもよい。これにより、過酷な環境下に置かれても表示品位の低下を抑制でき、偏光板への溶剤付着時の剥離及び破断を抑制でき、かつ、液晶パネル（２）の薄型化が可能である。 [Supplementary note]
One aspect of the present invention is a third polarizer functioning as a first polarizer (11), a first optical compensation layer (21), a second optical compensation layer (22), and a λ / 4 retardation plate. A liquid crystal cell (30) including a liquid crystal layer (33) between the pair of substrates (31, 32) and the pair of substrates (31, 32) facing each other; A fourth optical compensation layer (24) functioning as a four-retardation plate and a second polarizer (12) are provided in this order, and the first polarizer (11) has an absorption axis (11a) The first optical compensation layer (21) has an in-plane retardation Re of 15 nm or less at an angle of substantially 90 ° to the absorption axis (12a) of the second polarizer (12). And the thickness direction retardation Rth is −60 nm or less, and the second optical compensation layer (22) has an in-plane retardation Re of 40 to 12 nm, satisfying 1 ≦ Nz ≦ 4, and the in-plane slow axis (22a) is substantially parallel to the absorption axis (11a) of the first polarizer (11), and the third In the optical compensation layer (23), the in-plane slow axis (23a) forms an angle of substantially 45 ° or 135 ° with the absorption axis (11a) of the first polarizer (11), and the liquid crystal The cell (30) aligns liquid crystal molecules in the liquid crystal layer (33) substantially perpendicularly to the pair of substrates (31, 32) during black display, and the fourth optical compensation layer ( 24) is a liquid crystal display in which the in-plane slow axis (24a) makes an angle of substantially 90 ° with the in-plane slow axis (23a) of the third optical compensation layer (23); It is also good. This makes it possible to suppress deterioration in display quality even when placed under a severe environment, to suppress peeling and breakage when the solvent is attached to the polarizing plate, and to make the liquid crystal panel (2) thinner.
なお、特許文献３は、ポジティブＣプレートとポジティブＡプレートとを用いた円偏光板を開示しているかもしれないが、特許文献３では、ポジティブＡプレートの遅相軸は、それに近い偏光子の吸収軸に対して直交している。それに対して、上記態様の液晶表示装置（１）では、１≦Ｎｚ≦４を満たす前記第１の光学補償層（２１）は、面内遅相軸（２２ａ）が前記第１の偏光子（１１）の吸収軸（１１ａ）と実質的に平行であり、設計思想が異なる。この設計思想の相違により、液晶表示装置（１）では、光学補償層の使用枚数の削減が可能となる。 Although Patent Document 3 may disclose a circularly polarizing plate using a positive C plate and a positive A plate, in Patent Document 3, the slow axis of the positive A plate is a polarizer close to it. It is orthogonal to the absorption axis. On the other hand, in the liquid crystal display device (1) of the above aspect, the first optical compensation layer (21) satisfying 1 ≦ Nz ≦ 4 has the in-plane slow axis (22a) of the first polarizer ( It is substantially parallel to the absorption axis (11a) of 11), and the design concept is different. The difference in the design concept makes it possible to reduce the number of used optical compensation layers in the liquid crystal display device (1).
前記第３及び第４の光学補償層（２３、２４）は、各々、１≦Ｎｚ≦２．４を満たしてもよい。 The third and fourth optical compensation layers (23, 24) may each satisfy 1 ≦ Nz ≦ 2.4.
前記液晶表示装置（１）は、前記第１の偏光子（１１）及び前記液晶セル（３０）の間に前記第１～第３の光学補償層（２１～２３）以外の光学補償層を備えず、かつ、前記液晶セル（３０）及び前記第２の偏光子（１２）の間に前記第４の光学補償層（２４）以外の光学補償層を備えなくてもよい。これにより、過酷な環境に対する液晶表示装置（１）の耐久性をより優れたものにすることができるとともに、液晶パネル（２）を特に薄くすることができる。 The liquid crystal display (1) includes an optical compensation layer other than the first to third optical compensation layers (21 to 23) between the first polarizer (11) and the liquid crystal cell (30). In addition, an optical compensation layer other than the fourth optical compensation layer (24) may not be provided between the liquid crystal cell (30) and the second polarizer (12). Thereby, the durability of the liquid crystal display device (1) against severe environments can be made more excellent, and the liquid crystal panel (2) can be made particularly thin.
前記第１の光学補償層（２１）は、厚み方向位相差Ｒｔｈが－２００～－１００ｎｍであり、前記第２の光学補償層（２２）は、面内位相差Ｒｅが６０～１１０ｎｍであり、かつ、１≦Ｎｚ≦１．４を満たし、前記第３の光学補償層（２３）は、１．４≦Ｎｚ≦２．４を満たし、前記第４の光学補償層（２４）は、１．４≦Ｎｚ≦２．４を満たしてもよい。 The first optical compensation layer (21) has a thickness direction retardation Rth of -200 to -100 nm, and the second optical compensation layer (22) has an in-plane retardation Re of 60 to 110 nm. And, 1 ≦ Nz ≦ 1.4 is satisfied, the third optical compensation layer (23) satisfies 1.4 ≦ Nz ≦ 2.4, and the fourth optical compensation layer (24) is obtained by You may satisfy 4 <= Nz <= 2.4.
面内位相差Ｒｅが４０～１２０ｎｍであり、１≦Ｎｚ≦４を満たし、かつ、面内遅相軸（２５ａ）が前記第２の偏光子（１２）の吸収軸（１２ａ）と実質的に平行である第５の光学補償層（２５）と、面内位相差Ｒｅが１５ｎｍ以下であり、かつ、厚み方向位相差Ｒｔｈが－６０ｎｍ以下である第６の光学補償層（２６）とを更に備え、前記第１の偏光子（１１）、前記第１の光学補償層（２１）、前記第２の光学補償層（２２）、前記第３の光学補償層（２３）、前記液晶セル（３０）、前記第４の光学補償層（２４）、前記第５の光学補償層（２５）、前記第６の光学補償層（２６）、及び、前記第２の偏光子（１２）は、この順に配置されてもよい。これにより、液晶表示装置（１）は、より優れた視野角特性を発揮することができる。 The in-plane retardation Re is 40 to 120 nm, 1 ≦ Nz ≦ 4 is satisfied, and the in-plane slow axis (25a) substantially corresponds to the absorption axis (12a) of the second polarizer (12) A fifth optical compensation layer (25) in parallel, and a sixth optical compensation layer (26) having an in-plane retardation Re of 15 nm or less and a thickness direction retardation Rth of -60 nm or less. The first polarizer (11), the first optical compensation layer (21), the second optical compensation layer (22), the third optical compensation layer (23), the liquid crystal cell (30) , The fourth optical compensation layer (24), the fifth optical compensation layer (25), the sixth optical compensation layer (26), and the second polarizer (12) in this order It may be arranged. Thereby, the liquid crystal display device (1) can exhibit more excellent viewing angle characteristics.
前記第１及び第６の光学補償層（２１、２６）は、各々、厚み方向位相差Ｒｔｈが－１５０～－８０ｎｍであり、前記第２及び第５の光学補償層（２２、２５）は、各々、面内位相差Ｒｅが４０～９０ｎｍであり、かつ、１≦Ｎｚ≦１．４を満たし、前記第３の光学補償層（２３）は、１．４≦Ｎｚ≦２．４を満たし、前記第４の光学補償層（２４）は、１．４≦Ｎｚ≦２．４を満たしてもよい。 The first and sixth optical compensation layers (21, 26) each have a thickness direction retardation Rth of -150 to -80 nm, and the second and fifth optical compensation layers (22, 25) have The in-plane retardation Re is 40 to 90 nm, and 1 ≦ Nz ≦ 1.4, and the third optical compensation layer (23) satisfies 1.4 ≦ Nz ≦ 2.4, The fourth optical compensation layer (24) may satisfy 1.4 ≦ Nz ≦ 2.4.
前記第５の光学補償層（２５）は、実質的にＮｚ＝１を満たしてもよい。 The fifth optical compensation layer (25) may substantially satisfy Nz = 1.
面内位相差Ｒｅが１５ｎｍ以下であり、厚み方向位相差Ｒｔｈが５０～３００ｎｍであり、かつ、Ｎｚ＞１を満たす第７の光学補償層（２７）と、面内位相差Ｒｅが１５ｎｍ以下であり、厚み方向位相差Ｒｔｈが５０～３００ｎｍであり、かつ、Ｎｚ＞１を満たす第８の光学補償層（２８）とを更に備え、前記第１の偏光子（１１）、前記第１の光学補償層（２１）、前記第２の光学補償層（２２）、前記第３の光学補償層（２３）、前記第７の光学補償層（２７）、前記液晶セル（３０）、前記第８の光学補償層（２８）、前記第４の光学補償層（２４）、前記第５の光学補償層（２５）、前記第６の光学補償層（２６）、及び、前記第２の偏光子（１２）は、この順に配置されてもよい。これにより、液晶表示装置（１）は、全方位的な偏りの少ない視野角特性を発揮することができる。 A seventh optical compensation layer (27) having an in-plane retardation Re of 15 nm or less, a thickness direction retardation Rth of 50 to 300 nm, and Nz> 1, and an in-plane retardation Re of 15 nm or less And an eighth optical compensation layer (28) having a thickness direction retardation Rth of 50 to 300 nm and satisfying Nz> 1, and the first polarizer (11), the first optical Compensation layer (21), the second optical compensation layer (22), the third optical compensation layer (23), the seventh optical compensation layer (27), the liquid crystal cell (30), the eighth Optical compensation layer (28), the fourth optical compensation layer (24), the fifth optical compensation layer (25), the sixth optical compensation layer (26), and the second polarizer (12 ) May be arranged in this order. Thus, the liquid crystal display device (1) can exhibit viewing angle characteristics with less omnidirectional bias.
前記第１及び第６の光学補償層（２１、２６）は、各々、厚み方向位相差Ｒｔｈが－１５０～－８０ｎｍであり、前記第２及び第５の光学補償層（２２、２５）は、各々、面内位相差Ｒｅが４０～９０ｎｍであり、かつ、１≦Ｎｚ≦１．４を満たし、前記第３及び第４の光学補償層（２３、２４）は、各々、１≦Ｎｚ≦１．４を満たしてもよい。 The first and sixth optical compensation layers (21, 26) each have a thickness direction retardation Rth of -150 to -80 nm, and the second and fifth optical compensation layers (22, 25) have The in-plane retardation Re is 40 to 90 nm, and 1 ≦ Nz ≦ 1.4 is satisfied, and the third and fourth optical compensation layers (23, 24) are each 1 ≦ Nz ≦ 1. .4 may be satisfied.
前記第２の光学補償層（２２）は、実質的にＮｚ＝１を満たしてもよい。 The second optical compensation layer (22) may substantially satisfy Nz = 1.
前記第３の光学補償層（２３）の面内位相差Ｒｅは、前記第４の光学補償層（２４）の面内位相差Ｒｅと実質的に同じであってもよい。これにより、液晶表示装置（１）は、高コントラストを保つことができる。 The in-plane retardation Re of the third optical compensation layer (23) may be substantially the same as the in-plane retardation Re of the fourth optical compensation layer (24). Thereby, the liquid crystal display device (1) can maintain high contrast.
前記第３及び第４の光学補償層（２３、２４）は、各々、面内位相差Ｒｅが１００～１７５ｎｍであってもよい。 Each of the third and fourth optical compensation layers (23, 24) may have an in-plane retardation Re of 100 to 175 nm.
以上に示した本発明の各態様は、本発明の要旨を逸脱しない範囲において適宜組み合わされてもよい。 Each aspect of the present invention shown above may be combined suitably in the range which does not deviate from the gist of the present invention.
１：液晶表示装置
２：液晶パネル
２ａ：表示領域
３：第１の円偏光板
４：第２の円偏光板
１１：第１の偏光子
１１ａ：吸収軸
１２：第２の偏光子
１２ａ：吸収軸
２１：第１の光学補償層
２２：第２の光学補償層
２２ａ：面内遅相軸
２３：第３の光学補償層（λ／４位相差板）
２３ａ：面内遅相軸
２４：第４の光学補償層（λ／４位相差板）
２４ａ：面内遅相軸
２５：第５の光学補償層
２５ａ：面内遅相軸
２６：第６の光学補償層
２７：第７の光学補償層
２８：第８の光学補償層
３０：液晶セル
３１、３２：基板
３３：液晶層 1: Liquid crystal display 2: Liquid crystal panel 2a: Display area 3: First circularly polarizing plate 4: Second circularly polarizing plate 11: First polarizer 11a: Absorption axis 12: Second polarizer 12a: Absorption Axis 21: first optical compensation layer 22: second optical compensation layer 22a: in-plane slow axis 23: third optical compensation layer (λ / 4 retardation plate)
23a: in-plane slow axis 24: fourth optical compensation layer (λ / 4 retardation plate)
24a: in-plane slow axis 25: fifth optical compensation layer 25a: in-plane slow axis 26: sixth optical compensation layer 27: seventh optical compensation layer 28: eighth optical compensation layer 30: liquid crystal cell 31, 32: substrate 33: liquid crystal layer

Claims (12)

  1. 第１の偏光子と、
    第１の光学補償層と、
    第２の光学補償層と、
    λ／４位相差板として機能する第３の光学補償層と、
    互いに対向する一対の基板、及び、前記一対の基板間の液晶層を含む液晶セルと、
    λ／４位相差板として機能する第４の光学補償層と、
    第２の偏光子と、をこの順に備え、
    前記第１の偏光子は、吸収軸が前記第２の偏光子の吸収軸に対して実質的に９０°の角度をなし、
    前記第１の光学補償層は、面内位相差Ｒｅが１５ｎｍ以下であり、かつ、厚み方向位相差Ｒｔｈが－６０ｎｍ以下であり、
    前記第２の光学補償層は、面内位相差Ｒｅが４０～１２０ｎｍであり、１≦Ｎｚ≦４を満たし、かつ、面内遅相軸が前記第１の偏光子の吸収軸と実質的に平行であり、
    前記第３の光学補償層は、面内遅相軸が前記第１の偏光子の吸収軸に対して実質的に４５°又は１３５°の角度をなし、
    前記液晶セルは、黒表示時に、前記液晶層中の液晶分子を前記一対の基板面に対して実質的に垂直に配向し、
    前記第４の光学補償層は、面内遅相軸が前記第３の光学補償層の面内遅相軸に対して実質的に９０°の角度をなす液晶表示装置。     A first polarizer,
    A first optical compensation layer,
    A second optical compensation layer,
    a third optical compensation layer functioning as a λ / 4 retardation plate,
    A liquid crystal cell including a pair of substrates facing each other, and a liquid crystal layer between the pair of substrates;
    a fourth optical compensation layer functioning as a λ / 4 retardation plate,
    And a second polarizer in this order,
    The first polarizer has an absorption axis substantially at an angle of 90 ° with respect to the absorption axis of the second polarizer,
    The first optical compensation layer has an in-plane retardation Re of 15 nm or less and a thickness direction retardation Rth of −60 nm or less,
    The second optical compensation layer has an in-plane retardation Re of 40 to 120 nm, satisfies 1 ≦ Nz ≦ 4, and the in-plane slow axis substantially corresponds to the absorption axis of the first polarizer. Parallel and
    The third optical compensation layer has an in-plane slow axis at an angle of substantially 45 ° or 135 ° with respect to the absorption axis of the first polarizer,
    The liquid crystal cell aligns liquid crystal molecules in the liquid crystal layer substantially perpendicularly to the pair of substrate surfaces during black display.
    The fourth optical compensation layer is a liquid crystal display device in which the in-plane slow axis forms an angle of substantially 90 ° with the in-plane slow axis of the third optical compensation layer.
  2. 前記第３及び第４の光学補償層は、各々、１≦Ｎｚ≦２．４を満たす請求項１記載の液晶表示装置。 The liquid crystal display according to claim 1, wherein the third and fourth optical compensation layers each satisfy 1 ≦ Nz ≦ 2.4.
  3. 前記第１の偏光子及び前記液晶セルの間に前記第１～第３の光学補償層以外の光学補償層を備えず、かつ、前記液晶セル及び前記第２の偏光子の間に前記第４の光学補償層以外の光学補償層を備えない請求項１又は２記載の液晶表示装置。 An optical compensation layer other than the first to third optical compensation layers is not provided between the first polarizer and the liquid crystal cell, and the fourth between the liquid crystal cell and the second polarizer. The liquid crystal display device according to claim 1 or 2, wherein no optical compensation layer other than the optical compensation layer is provided.
  4. 前記第１の光学補償層は、厚み方向位相差Ｒｔｈが－２００～－１００ｎｍであり、
    前記第２の光学補償層は、面内位相差Ｒｅが６０～１１０ｎｍであり、かつ、１≦Ｎｚ≦１．４を満たし、
    前記第３の光学補償層は、１．４≦Ｎｚ≦２．４を満たし、
    前記第４の光学補償層は、１．４≦Ｎｚ≦２．４を満たす請求項３記載の液晶表示装置。     The first optical compensation layer has a thickness direction retardation Rth of -200 to -100 nm,
    The second optical compensation layer has an in-plane retardation Re of 60 to 110 nm and satisfies 1 ≦ Nz ≦ 1.4,
    The third optical compensation layer satisfies 1.4 ≦ Nz ≦ 2.4,
    4. The liquid crystal display device according to claim 3, wherein the fourth optical compensation layer satisfies 1.4 ≦ Nz ≦ 2.4.
  5. 面内位相差Ｒｅが４０～１２０ｎｍであり、１≦Ｎｚ≦４を満たし、かつ、面内遅相軸が前記第２の偏光子の吸収軸と実質的に平行である第５の光学補償層と、
    面内位相差Ｒｅが１５ｎｍ以下であり、かつ、厚み方向位相差Ｒｔｈが－６０ｎｍ以下である第６の光学補償層とを更に備え、
    前記第１の偏光子、前記第１の光学補償層、前記第２の光学補償層、前記第３の光学補償層、前記液晶セル、前記第４の光学補償層、前記第５の光学補償層、前記第６の光学補償層、及び、前記第２の偏光子は、この順に配置される請求項１又は２記載の液晶表示装置。     A fifth optical compensation layer having an in-plane retardation Re of 40 to 120 nm, satisfying 1 ≦ Nz ≦ 4, and having an in-plane slow axis substantially parallel to the absorption axis of the second polarizer. When,
    And a sixth optical compensation layer having an in-plane retardation Re of 15 nm or less and a thickness direction retardation Rth of −60 nm or less,
    The first polarizer, the first optical compensation layer, the second optical compensation layer, the third optical compensation layer, the liquid crystal cell, the fourth optical compensation layer, the fifth optical compensation layer The liquid crystal display device according to claim 1, wherein the sixth optical compensation layer and the second polarizer are disposed in this order.
  6. 前記第１及び第６の光学補償層は、各々、厚み方向位相差Ｒｔｈが－１５０～－８０ｎｍであり、
    前記第２及び第５の光学補償層は、各々、面内位相差Ｒｅが４０～９０ｎｍであり、かつ、１≦Ｎｚ≦１．４を満たし、
    前記第３の光学補償層は、１．４≦Ｎｚ≦２．４を満たし、
    前記第４の光学補償層は、１．４≦Ｎｚ≦２．４を満たす請求項５記載の液晶表示装置。     The first and sixth optical compensation layers each have a thickness direction retardation Rth of −150 to −80 nm,
    The second and fifth optical compensation layers each have an in-plane retardation Re of 40 to 90 nm, and satisfy 1 ≦ Nz ≦ 1.4,
    The third optical compensation layer satisfies 1.4 ≦ Nz ≦ 2.4,
    The liquid crystal display device according to claim 5, wherein the fourth optical compensation layer satisfies 1.4 ≦ Nz ≦ 2.4.
  7. 前記第５の光学補償層は、実質的にＮｚ＝１を満たす請求項５又は６記載の液晶表示装置。 7. The liquid crystal display device according to claim 5, wherein the fifth optical compensation layer substantially satisfies Nz = 1.
  8. 面内位相差Ｒｅが１５ｎｍ以下であり、厚み方向位相差Ｒｔｈが５０～３００ｎｍであり、かつ、Ｎｚ＞１を満たす第７の光学補償層と、
    面内位相差Ｒｅが１５ｎｍ以下であり、厚み方向位相差Ｒｔｈが５０～３００ｎｍであり、かつ、Ｎｚ＞１を満たす第８の光学補償層とを更に備え、
    前記第１の偏光子、前記第１の光学補償層、前記第２の光学補償層、前記第３の光学補償層、前記第７の光学補償層、前記液晶セル、前記第８の光学補償層、前記第４の光学補償層、前記第５の光学補償層、前記第６の光学補償層、及び、前記第２の偏光子は、この順に配置される請求項５記載の液晶表示装置。     A seventh optical compensation layer having an in-plane retardation Re of 15 nm or less, a thickness direction retardation Rth of 50 to 300 nm, and Nz>1;
    And an eighth optical compensation layer having an in-plane retardation Re of 15 nm or less, a thickness direction retardation Rth of 50 to 300 nm, and Nz> 1.
    The first polarizer, the first optical compensation layer, the second optical compensation layer, the third optical compensation layer, the seventh optical compensation layer, the liquid crystal cell, and the eighth optical compensation layer The liquid crystal display device according to claim 5, wherein the fourth optical compensation layer, the fifth optical compensation layer, the sixth optical compensation layer, and the second polarizer are arranged in this order.
  9. 前記第１及び第６の光学補償層は、各々、厚み方向位相差Ｒｔｈが－１５０～－８０ｎｍであり、
    前記第２及び第５の光学補償層は、各々、面内位相差Ｒｅが４０～９０ｎｍであり、かつ、１≦Ｎｚ≦１．４を満たし、
    前記第３及び第４の光学補償層は、各々、１≦Ｎｚ≦１．４を満たす請求項８記載の液晶表示装置。     The first and sixth optical compensation layers each have a thickness direction retardation Rth of −150 to −80 nm,
    The second and fifth optical compensation layers each have an in-plane retardation Re of 40 to 90 nm, and satisfy 1 ≦ Nz ≦ 1.4,
    9. The liquid crystal display device according to claim 8, wherein the third and fourth optical compensation layers each satisfy 1 ≦ Nz ≦ 1.4.
  10. 前記第２の光学補償層は、実質的にＮｚ＝１を満たす請求項１～９のいずれかに記載の液晶表示装置。 The liquid crystal display device according to any one of claims 1 to 9, wherein the second optical compensation layer substantially satisfies Nz = 1.
  11. 前記第３の光学補償層の面内位相差Ｒｅは、前記第４の光学補償層の面内位相差Ｒｅと実質的に同じである請求項１～１０のいずれかに記載の液晶表示装置。 The liquid crystal display device according to any one of claims 1 to 10, wherein the in-plane retardation Re of the third optical compensation layer is substantially the same as the in-plane retardation Re of the fourth optical compensation layer.
  12. 前記第３及び第４の光学補償層は、各々、面内位相差Ｒｅが１００～１７５ｎｍである請求項１～１１のいずれかに記載の液晶表示装置。 The liquid crystal display device according to any one of claims 1 to 11, wherein each of the third and fourth optical compensation layers has an in-plane retardation Re of 100 to 175 nm.
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