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WO2007018361A1 - Lcd light guiding plate and back light unit and lcd using a thereof - Google Patents

Lcd light guiding plate and back light unit and lcd using a thereof Download PDF

Info

Publication number
WO2007018361A1
WO2007018361A1 PCT/KR2006/003027 KR2006003027W WO2007018361A1 WO 2007018361 A1 WO2007018361 A1 WO 2007018361A1 KR 2006003027 W KR2006003027 W KR 2006003027W WO 2007018361 A1 WO2007018361 A1 WO 2007018361A1
Authority
WO
WIPO (PCT)
Prior art keywords
light
lens unit
incident
liquid crystal
guiding plate
Prior art date
Application number
PCT/KR2006/003027
Other languages
French (fr)
Inventor
Janghwan Hwang
Jungju Kim
Gisik Eom
Original Assignee
Namotek Co., Ltd.
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Namotek Co., Ltd. filed Critical Namotek Co., Ltd.
Publication of WO2007018361A1 publication Critical patent/WO2007018361A1/en

Links

Classifications

    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
    • G02B6/0001—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings specially adapted for lighting devices or systems
    • G02B6/0011—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings specially adapted for lighting devices or systems the light guides being planar or of plate-like form
    • G02B6/0033—Means for improving the coupling-out of light from the light guide
    • G02B6/005—Means for improving the coupling-out of light from the light guide provided by one optical element, or plurality thereof, placed on the light output side of the light guide
    • G02B6/0051—Diffusing sheet or layer
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
    • G02B6/0001—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings specially adapted for lighting devices or systems
    • G02B6/0011—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings specially adapted for lighting devices or systems the light guides being planar or of plate-like form
    • G02B6/0013—Means for improving the coupling-in of light from the light source into the light guide
    • G02B6/0015—Means for improving the coupling-in of light from the light source into the light guide provided on the surface of the light guide or in the bulk of it
    • G02B6/0016—Grooves, prisms, gratings, scattering particles or rough surfaces
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
    • G02B6/0001—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings specially adapted for lighting devices or systems
    • G02B6/0011—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings specially adapted for lighting devices or systems the light guides being planar or of plate-like form
    • G02B6/0013—Means for improving the coupling-in of light from the light source into the light guide
    • G02B6/0015—Means for improving the coupling-in of light from the light source into the light guide provided on the surface of the light guide or in the bulk of it
    • G02B6/0018—Redirecting means on the surface of the light guide
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
    • G02B6/0001—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings specially adapted for lighting devices or systems
    • G02B6/0011—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings specially adapted for lighting devices or systems the light guides being planar or of plate-like form
    • G02B6/0066—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings specially adapted for lighting devices or systems the light guides being planar or of plate-like form characterised by the light source being coupled to the light guide
    • G02B6/0068—Arrangements of plural sources, e.g. multi-colour light sources
    • 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
    • G02F1/133526—Lenses, e.g. microlenses or Fresnel lenses
    • 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
    • G02F1/1336—Illuminating devices
    • G02F1/133602—Direct backlight
    • G02F1/133611—Direct backlight including means for improving the brightness uniformity
    • 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
    • G02F1/136—Liquid crystal cells structurally associated with a semi-conducting layer or substrate, e.g. cells forming part of an integrated circuit
    • G02F1/1362—Active matrix addressed cells

Definitions

  • the present invention relates to a light guiding plate for a liquid crystal display
  • LCD which is capable of improving light condensing efficiency of the LCD and brightness by distributing an incident light through optical diffusion, reflection and refraction, and also improving optical uniformity of the light advancing toward the LCD so that loss of the light can be minimized, and a backlight unit and an LCD using the same.
  • a liquid crystal display one of flat panel displays, is superior to a cathode ray tube(CRT) in luminance, and more power-saving than the CRT for the same screen size. Furthermore, the LCD generates less heat than the CRT. Therefore, the LCD has been being spotlighted as a next-generation display for a mobile phone, a computer monitor, and a TV, together with a plasma display panel (PDP) and a field emission display (FED).
  • PDP plasma display panel
  • FED field emission display
  • the LCD comprises a liquid crystal panel, a backlight unit, color filters, and a black matrix layer.
  • the liquid crystal panel comprises liquid crystal cells for adjusting optical transmittance of light projected from a lower part thereof, being arranged in an active matrix form.
  • the backlight unit projects the light from the lower part of the liquid crystal panel.
  • the color filters comprising red, green, and blue filters are disposed on an upper surface of each of the liquid crystal panels, separately for each liquid crystal cell.
  • the black matrix film discriminates among pixels.
  • a side-lit type backlight unit can reduce the whole thickness of an apparatus by being disposed on a lateral side of the liquid crystal panel and supplying light to a liquid crystal layer through a reflection plate and a light guiding plate.
  • the side-lit type backlight unit is used generally for a mobile phone, a personal digital assistant (PDA), a vehicle navigator, and a laptop.
  • PDA personal digital assistant
  • vehicle navigator a vehicle navigator
  • laptop a laptop
  • the side-lit type backlight unit having a light emitting diode (LED) lamp on the lateral side of the liquid crystal panel is inferior in lighting efficiency and therefore inappropriate for a wide-area liquid crystal panel.
  • LED light emitting diode
  • a bottom surface of a light guiding plate 11 is arranged in a circular or oval reflection pattern 1 Ia.
  • another light guiding plate 12 has a bottom surface arranged in a pyramided reflection pattern 12a.
  • these are not only limited to obtain high brightness as desired but also complicated in structure. Therefore, manufacture and production of such light guiding plates are difficult and uneconomical.
  • FIG. 3 shows yet another light guiding plate 13 having a prism array unit 13a linearly arranged on a bottom surface thereof.
  • This light guiding plate 13 is effective in obtaining the high brightness; however, can not achieve optical uniformity on the whole, thereby causing bright lines.
  • the bright lines deteriorate quality of a surface light source with respect to the light guiding plate.
  • the backlight unit adopting the conventional light guiding plate comprises an LED lamp for emitting light, the light guiding plate for diffusing the light generated from the LED lamp and guiding the light toward the surface light source, a reflection plate for reflecting the light from a lower part of the light guiding plate to an upper part where the liquid crystal panel is disposed, and a diffusion plate and a prism sheet for controlling diffusion and an advancing direction of the light passed through the light guiding plate.
  • the light passed through the light guiding plate is diffused in all directions by the diffusion plate, and then controlled by the prism sheet to advance perpendicularly to the liquid crystal panel.
  • the light passed through the prism sheet is thus incident on the liquid crystal panel.
  • the present invention has been made in view of the above-mentioned problems, and it is an object of the present invention to provide a light guiding plate for a liquid crystal display (LCD) comprising an incident light lens unit and a light guide plate (LGP) upper surface, the incident light lens unit having a serrated fresnel part and a space part for total reflection, so that generation of bright lines caused while light from the incident light lens unit is incident on the LGP upper surface can be minimized, and accordingly the light straightly advancing can be distributed planarly and favorably projected in a vertical direction, and a backlight unit and a LCD using the same.
  • LCD liquid crystal display
  • LGP light guide plate
  • a light guiding plate of a liquid crystal panel for a liquid crystal display the liquid crystal panel having liquid crystal cells arranged in an active matrix form to adjust optical transmittance of light projected from a lower part thereof, comprising an incident light lens unit having a fresnel part serrated for diffusion and reflection of light, in order to project the light which is a surface light source toward the liquid crystal panel.
  • a light guiding plate of a liquid crystal panel for an LCD the liquid crystal panel having liquid crystal cells arranged in an active matrix form to adjust optical transmittance of light projected from a lower part thereof, comprising an incident light lens unit having a fresnel part serrated for diffusion and reflection of light to project the light which is a surface light source toward the liquid crystal panel, and a space part having a trigonal or other polygonal prism form for performing internal total reflection of the light; and a light guiding plate (LGP) upper surface having a protrusion end inserted and mounted in part of the space part of the incident light lens unit.
  • incident light lens unit having a fresnel part serrated for diffusion and reflection of light to project the light which is a surface light source toward the liquid crystal panel
  • a space part having a trigonal or other polygonal prism form for performing internal total reflection of the light
  • LGP light guiding plate
  • a light guiding plate of a liquid crystal panel for an LCD the liquid crystal panel having liquid crystal cells arranged in an active matrix form to adjust optical transmittance of light projected from a lower part thereof, comprising an incident light lens unit having a fresnel part serrated for diffusion and reflection of light to project the light which is a surface light source toward the liquid crystal panel, and a space part having a trigonal or other polygonal prism form for performing internal total reflection of the light; and an LGP upper surface having a protrusion end inserted and mounted in part of the space part of the incident light lens unit, and wherein a connection area of the incident light lens unit with the LGP upper surface is unevenly formed for diffusion of the light.
  • the incident light lens unit includes a light-incident part that directly receives the light from the luminous lamp such as a light emitting diode (LED) and is formed as one of a concave lens, a convex lens, a plane, and a plane rounded at both side edges.
  • the luminous lamp such as a light emitting diode (LED)
  • LED light emitting diode
  • the plane has unevenness thereon.
  • the space part formed in the incident light lens unit has an isosceles shape having two fresnel reflection surfaces symmetrical with respect to a vertex thereof.
  • angles of a prism constituting the reflection surface have ranges as follows: 5° ⁇ 60°, 55° ⁇ 95°, 5° ⁇ 60°.
  • the light-incident part of the incident light lens unit is rounded by the approximately 0.01 ⁇ 10mm of radius of curvature V.
  • the unevenness at the connection area of the incident light lens unit has one of a prism form, a rounded groove form, and a wave form.
  • Another aspect of the present invention is to provide a backlight unit applied to an
  • LCD for projecting white light from a rear side of a liquid crystal panel, comprising a luminous lamp such as an LED for generating and emitting light; a light guiding plate including an incident light lens unit having a fresnel part serrated for diffusion and reflection of light to project the light which is a surface light source toward the liquid crystal panel and a space part having a trigonal or other polygonal prism form for performing internal total reflection of the light, and an LGP upper surface having a protrusion end inserted and mounted in part of the space part of the incident light lens unit; a diffusion plate and a prism sheet for adjusting diffusion and an advancing direction of the light passed through the light guiding plate; and a reflection plate for reflecting the light generated from the luminous lamp and the light directed from the light guiding plate.
  • a luminous lamp such as an LED for generating and emitting light
  • a light guiding plate including an incident light lens unit having a fresnel part serrated for diffusion and reflection of light to project the light which is
  • a connection area of the incident light lens unit with the LGP upper surface is unevenly formed for diffusion of the light.
  • the incident light lens unit includes a light-incident part that directly receives the light from the luminous lamp such as a light emitting diode (LED) and is formed as one of a concave lens, a convex lens, a plane, and a plane rounded at both side edges.
  • the luminous lamp such as a light emitting diode (LED)
  • LED light emitting diode
  • the space part formed in the incident light lens unit has an isosceles shape having two fresnel reflection surfaces symmetrical with respect to a vertex thereof.
  • a plurality of the protrusion ends are formed at one side or both sides of the incident light lens unit, and a plurality of the incident light lens units for mounting the protrusion ends therein are correspondingly formed.
  • Yet another aspect of the present invention is to provide an LCD comprising a backlight unit that includes a light guiding plate having an incident light lens unit having a fresnel part serrated for diffusion and reflection of light and a space part having a trigonal or other polygonal prism form for performing internal total reflection of the light, and an LGP upper surface having a protrusion end mounted in part of the space part of the incident light lens unit; and a liquid crystal panel connected with the backlight unit and comprising liquid crystal cells that adjust optical transmittance, being arranged in an active matrix form, thereby displaying an image by the light projected from the backlight unit.
  • a connection area of the incident light lens unit with the LGP upper surface is unevenly formed for diffusion of the light.
  • the incident light lens unit includes a light-incident part that directly receives the light from the luminous lamp such as a light emitting diode (LED) and is formed as one of a concave lens, a convex lens, a plane, and a plane rounded at both side edges.
  • the luminous lamp such as a light emitting diode (LED)
  • LED light emitting diode
  • FIGS. 1 through 3 are sectional views showing examples of a reflection pattern of a bottom surface of conventional light guiding plates;
  • FIG. 4 is a schematic view for explaining an incident light lens unit of a light guiding plate according to an embodiment of the present invention;
  • FIG. 5 shows shape of a vertex of a space part of the incident light lens unit according to an embodiment of the present invention;
  • FIG. 6 shows an embodiment of the present invention wherein a light-incident part of the incident light lens unit has a convex lens form;
  • FIG. 7 shows another embodiment of the present invention wherein a light-incident part of the incident light lens unit has a concave lens form;
  • FIG. 8 shows yet another embodiment of the present invention wherein a light- incident part of the incident light lens unit is plane;
  • FIGS. 9 through 13 show examples of the light- incident part of the incident light lens unit of FIG. 8, having an uneven surface;
  • FIG. 14 shows yet another embodiment of the present invention wherein the light- incident part of the incident light lens unit is formed as a plane rounded on both side edges;
  • FIGS. 15 through 19 show various types of the light-incident part of the light guiding plate according to the present invention;
  • FIG. 20 shows the incident light lens unit of the light guiding plate connected with a light guiding plate (LGP) upper surface, according to the present invention;
  • FIG. 21 is a side view showing the connection state between the incident light lens unit and the LGP upper surface according to the present invention;
  • FIG. 22 shows an example wherein the light guiding plate according to the present invention is applied to a backlight unit;
  • FIG. 23 shows diffusion and refraction operations of the incident light lens unit of the light guiding plate according to the present invention; and
  • FIG. 24 shows the structure of a liquid crystal display (LCD) applying the backlight unit according to the present invention.
  • LCD liquid crystal display
  • FIG. 4 schematically shows an embodiment of an incident light lens unit of a light guiding plate.
  • FIG. 5 shows an exemplary shape of a vertex of a space part of the incident light lens unit, according to the present invention.
  • FIGS. 6 through 14 show embodiments regarding a light-incident part of the incident light lens unit according to the present invention.
  • a liquid crystal panel (not shown) for a liquid crystal display (LCD) comprises liquid crystal cells for adjusting transmittance of light projected from a lower part thereof, being arranged in an active matrix form.
  • a light guiding plate 20 for projecting light, which is a surface light source, toward the liquid crystal panel includes an incident light lens unit 21.
  • the incident light lens unit comprises a serrated fresnel part 21a for diffusion of the light.
  • the fresnel part 21a of the incident light lens unit 21 is formed as a plurality of sawlike teeth to enhance efficiency of diffusion and refraction for the incident light.
  • a light- incident part is formed at the incident light lens unit 21 in the form of a convex lens as shown in FIG. 6, a concave lens in FIG. 7, a plane in FIGS. 8 through 13, or a plane rounded at both side edges in FIG. 14.
  • the light from a luminous lamp such as a light emitting diode (LED) is directly incident on the light- incident part.
  • the incident light lens unit 21 further comprises a space part 21b for total reflection of the light therein.
  • the plane light- incident part of FIG. 8 has an uneven surface in various types as shown in FIGS. 9 through 13.
  • the space part 21b of the incident light lens unit 21 includes an entry end 21-1 so that a dedicated member can be facilely inserted and mounted.
  • the space part 21b of the incident light lens unit 21 is formed in an isosceles shape having two fresnel reflection surfaces symmetrical with respect to a vertex thereof.
  • angles of a prism constituting the reflection surface have ranges as follows: 5° ⁇ 60°, 55° ⁇ 95°, 5° ⁇ 60°.
  • a corner of the space part 21b provided for internal total reflection forms a right angle.
  • the radius of curvature V of the convex portion is approximately 0.01-lOmm.
  • an unevenness may be formed at a connection area between the incident light lens unit 21 and a light guiding plate (LGP) upper surface 22 in various forms, such that the light can be advanced as uniformly as possible toward the liquid crystal panel.
  • LGP light guiding plate
  • FIGS. 15 through 19 show various types of the unevenness formed at the connection area in the structure where the light-incident part is convex on the right and concave on the left.
  • other types of the unevenness can be applied as shown in FIGS. 8 through 14.
  • rounded corrugation is formed at a connection area 23 where the incident light lens unit 21 is contacted with the LGP upper surface 22. Therefore, the light can be advanced more uniformly through the fresnel part 21a for diffusion of the light and the space part 21b for the internal total reflection.
  • prismatic corrugation is formed at the connection area 23 between the incident light lens unit 21 and the LGP upper surface 22.
  • FIG. 20 shows the incident light lens unit 21 and the LGP upper surface 22 being connected to each other.
  • FIG. 21 is a side view showing the connected state of the incident light lens unit 21 and the LGP upper surface 22.
  • FIG. 20 shows the incident light lens unit 21 and the LGP upper surface 22 being connected to each other.
  • FIG. 21 is a side view showing the connected state of the incident light lens unit 21 and the LGP upper surface 22.
  • FIG. 20 shows the incident light lens unit 21 and the LGP upper surface 22 being connected to each other.
  • FIG. 21 is a side view showing the connected state of the incident light lens unit 21 and the LGP upper surface 22.
  • a reflection pattern is formed on a bottom surface of the LGP upper surface 22. Various types can be applied for the reflection pattern.
  • the light guiding plate 20 in the liquid crystal panel for an LCD wherein the liquid crystal cells for adjusting optical transmittance are arranged in the matrix form comprises the incident light lens unit 21 and the LGP upper surface 22.
  • the incident light lens unit 21 comprises the fresnel part 21a serrated for diffusion of the light, and the space part 21b for internal total reflection of the light.
  • the LGP upper surface 22 comprises a protrusion end 22a to be inserted and mounted in part of the space part 21b of the incident light lens unit 21.
  • the incident light lens unit 21 and the LGP upper surface 22 are integrally formed with each other, rather than being separated.
  • a plurality of the protrusion ends 22a are formed at one side of the LGP upper surface 22.
  • a plurality of the incident light lens units 21 are provided for mounting of the respective protrusion ends 22a.
  • a plurality of the protrusion ends 22a are formed at one side and the other side of the LGP upper surface 22, respectively. Also, a plurality of the incident light lens units 21 are formed corresponding to the respective protrusion ends 22a.
  • the protrusion ends 22a of the LGP upper surface 22 are formed incompactly near a light-incident surface and compactly toward the center, so that the incident light can be projected uniformly in a direction of a viewing angle.
  • the incident light passed through the incident light lens unit 21 is compacter at the center. More particularly, the incident light becomes compacter as being moved to the center.
  • FIG. 22 shows an example of the backlight unit applying the light guiding plate according to an embodiment of the present invention.
  • FIG. 23 shows diffusion and refraction operations of the incident light lens unit 21 of the light guiding plate according to an embodiment of the present invention.
  • FIG. 24 shows an example of the LCD applying the backlight unit according to an embodiment of the present invention.
  • the backlight unit of FIG. 22 is structured to uniformly project white light from a rear side of the liquid crystal panel, being applied to the LCD.
  • the backlight unit comprises a luminous lamp 100, a light guiding plate 200, a diffusion plate 300 and a prism sheet 400, and a reflection plate 500.
  • the luminous lamp 100 such as an LED generates and emits light.
  • the light guiding plate 200 includes the incident light lens unit 21 and the LGP upper surface 22 to facilitate vertical projection of the light generated from the luminous lamp 100.
  • the diffusion plate 300 and the prism sheet 400 control diffusion and an advancing direction of the light passed through the light guiding plate 200.
  • the reflection plate 500 reflects the light generated from the luminous lamp 100 and the light directed from the light guiding plate 200.
  • the light guiding plate 200 comprises the incident light lens unit 21 and the LGP upper surface 22.
  • the incident light lens unit 21 comprises the fresnel part 21a serrated for diffusion of the light, and the space part 21b for internal total reflection of the light.
  • the LGP upper surface 22 comprises the protrusion end 22a to be inserted and mounted in part of the space part 21b of the incident light lens unit 21.
  • a plurality of the protrusion ends 22a are formed at one side of the LGP upper surface 22.
  • a plurality of the incident light lens units 21 are provided for mounting of the respective protrusion ends 22a.
  • a plurality of the protrusion ends 22a are formed at one side and the other side of the LGP upper surface 22, respectively. Also, a plurality of the incident light lens units 21 are formed corresponding to the respective protrusion ends 22a.
  • the object of the present invention is in minimizing bright lines caused while the light is being incident on the incident light lens unit 21 and in facilely projecting the light in a vertical direction, by planarly distributing the light straightly advancing to the LGP upper surface 22.
  • the light guiding plate 200 is provided with the incident light lens unit
  • the fresnel part 21a having a serrated form is disposed on a side of the incident light lens unit 21, the light projected from the luminous lamp 100 such as the LED is diffused by the serration structure, and facilely distributed planarly as shown in FIG. 16.
  • FIG. 23 shows diffusion and refraction operations of the light guiding plate 20 through simulation.
  • the incident light lens unit 21 provided to the light guiding plate 200 of the backlight unit can variably diffuse and refract the light and as a result, brightness and optical uniformity are considerably improved in the liquid crystal panel. Accordingly, the bright lines can be prevented.
  • the space part 21b having a prism pattern and provided to the incident light lens unit 21 internally generates total reflection, thereby inducing diffusion and refraction of the light. Therefore, the light can be distributed more planarly, and the optical uniformity can be enhanced.
  • the light- incident part directly receiving the light from the luminous lamp 100 has a concave form or a convex form, the light can be distributed more planarly through diffusion, refraction and reflection.
  • connection area 23 between the incident light lens unit 21 and the LGP upper surface 22 of the light guiding plate can be applied, in order to enhance more uniform advance of the light that has been advancing through the serrated fresnel part 21a and the space part 21b.
  • the prismatic space part 21b of the incident light lens unit 21 includes the entry end
  • the incident light lens unit 21-1 which is opened. Therefore, when the incident light lens unit 21 is connected with another dedicated member, the member can be easily inserted and mounted into the incident light lens unit 21.
  • the space part 21b formed in the incident light lens unit 21 has an isosceles shape having two fresnel reflection surfaces symmetrical with respect to a vertex thereof.
  • a corner of the space part 21b for internal total reflection forms a right angle.
  • the radius of curvature V of the convex portion is approximately 0.01 ⁇ 10mm.
  • the light guiding plate 20 is dedicatedly provided with the LGP upper surface 22 for engagement with the incident light lens unit 21.
  • the LGP upper surface 22 includes the protrusion end 22a inserted and mounted in part of the space part 21b of the incident light lens unit 21.
  • the incident light lens unit 21 and the LGP upper surface 22 of the light guiding plate 200 are integrated, not being separated.
  • a plurality of the protrusion ends 22a are formed at one side of the LGP upper surface 22 and inserted in the entry ends 21-1 of the space part 21b formed at the incident light lens unit 21.
  • the efficiency of optical diffusion and refraction can be enhanced.
  • the brightness and the optical uniformity can be enhanced overall.
  • the reflection plate 500 is disposed at a lower end of the backlight unit.
  • the reflection plate 500 reflects the light upward to the liquid crystal panel.
  • the light guiding plate 200 is disposed at an upper part of the reflection plate 500 in order to favorably diffuse the light generated from the luminous lamp 100 and project the light toward the surface light source.
  • the diffusion plate 300 and the prism sheet 400 are respectively provided on the upper part of the light guiding plate 200, to control the diffusion and the advancing direction of the light that is passed through the incident light lens unit 21.
  • the light is planarly distributed through the light guiding plate 200 applied to the backlight unit. Consequently, the brightness and the optical uniformity with respect to the liquid crystal panel are improved.
  • a plurality of the protrusion ends 22a formed at one side of the LGP upper surface 22 are inserted and mounted in the entry ends 21-1 of the space part 21b formed at the incident light lens unit 21.
  • the light from the luminous lamp 100 can be vertically projected and furthermore, the brightness and the optical uniformity can be improved by preventing the bright lines.
  • the light guiding plate 20 and the light guiding plate 200 applied to the backlight unit may be structured in various ways according to size of the liquid crystal panel.
  • the size of the liquid crystal panel can be varied by connecting a plurality of the incident light lens units 21 and the LGP upper surfaces 22, in the same manner of connecting a single incident light lens unit 21 on both sides of a single LGP upper surface 22. Therefore, such modified structure is still within the scope of the present invention.
  • the light guiding plate 20 and the light guiding plate 200 of the backlight unit are implemented by a transparent material such as plastic and resin, so that the light can be favorably diffused and refracted.
  • a transparent material such as plastic and resin
  • PC polycarbonate
  • PMMA polymethylmethacrylate
  • the luminous lamp 100 may comprise red, green and blue LEDs, or a white LED.
  • FIG. 24 shows the structure of an LCD applying the backlight unit having the light guiding plate 200 according to the present invention.
  • the LCD comprises the luminous lamp 100 such as the LED for generating and emitting light, the light guiding plate 200 including the incident light lens unit 21 and the LGP upper surface 22 to facilitate vertical projection of the light, the diffusion plate 300 and the prism sheet 400 for controlling diffusion and the advancing direction of the light passed through the light guiding plate 200, and the reflection plate 500 for reflecting the light generated from the luminous lamp 100 and the light directed from the light guiding plate 200.
  • the luminous lamp 100 such as the LED for generating and emitting light
  • the light guiding plate 200 including the incident light lens unit 21 and the LGP upper surface 22 to facilitate vertical projection of the light
  • the diffusion plate 300 and the prism sheet 400 for controlling diffusion and the advancing direction of the light passed through the light guiding plate 200
  • the reflection plate 500 for reflecting the light generated from the luminous lamp 100 and the light directed from the light guiding plate 200.
  • a liquid crystal panel 600 is further comprised, being connected with the backlight unit. Comprising the liquid crystal cells arranged in the active matrix form to adjust transmittance of the incident light, the liquid crystal panel 600 displays an image by the light transmitted through the backlight unit.
  • the light guiding plate according to the present invention comprises an incident light lens unit and an LGP upper surface.
  • the incident light lens unit includes a fresnel part having a serrated form for optical diffusion and refraction, and a space part for internally performing total reflection with respect to the light source.
  • the LGP upper surface includes a protrusion end to be inserted and mounted in the space part.
  • the light guiding plate planarly distributes the light incident thereon by variably diffusing, reflecting and refracting the light. As a result, light-condensing efficiency and brightness of the liquid crystal panel can be enhanced.
  • the light guiding plate, and the backlight unit and the LCD using the same are provided to minimize loss of the light, by improving optical uniformity of the light advancing to the liquid crystal panel.

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Abstract

Disclosed are a light guiding plate for a liquid crystal display (LCD), and a backlight unit and an LCD using the same. The light guiding plate comprises an incident light lens unit and an LGP upper surface. The incident light lens unit comprises a fresnel part serrated for diffusion of light, and a space part for internal total reflection of the light. The LGP upper surface comprises a protrusion end to be mounted in part of the space part. According to the above structure, bright lines occurring while the light is passed through the incident light lens unit and incident on the LGP upper surface can be minimized. As a result, the light advancing to the LGP upper surface can be planarly distributed and vertically projected more facilely. Eventually, light condensing efficiency of the liquid crystal panel is improved. Also, brightness and optical uniformity are enhanced, thereby minimizing loss of the light.

Description

Description
LCD LIGHT GUIDING PLATE AND BACK LIGHT UNIT AND
LCD USING A THEREOF
Technical Field
[1] The present invention relates to a light guiding plate for a liquid crystal display
(LCD), which is capable of improving light condensing efficiency of the LCD and brightness by distributing an incident light through optical diffusion, reflection and refraction, and also improving optical uniformity of the light advancing toward the LCD so that loss of the light can be minimized, and a backlight unit and an LCD using the same. Background Art
[2] Generally, a liquid crystal display (LCD), one of flat panel displays, is superior to a cathode ray tube(CRT) in luminance, and more power-saving than the CRT for the same screen size. Furthermore, the LCD generates less heat than the CRT. Therefore, the LCD has been being spotlighted as a next-generation display for a mobile phone, a computer monitor, and a TV, together with a plasma display panel (PDP) and a field emission display (FED).
[3] The LCD comprises a liquid crystal panel, a backlight unit, color filters, and a black matrix layer. The liquid crystal panel comprises liquid crystal cells for adjusting optical transmittance of light projected from a lower part thereof, being arranged in an active matrix form. The backlight unit projects the light from the lower part of the liquid crystal panel. The color filters comprising red, green, and blue filters are disposed on an upper surface of each of the liquid crystal panels, separately for each liquid crystal cell. The black matrix film discriminates among pixels.
[4] A side-lit type backlight unit can reduce the whole thickness of an apparatus by being disposed on a lateral side of the liquid crystal panel and supplying light to a liquid crystal layer through a reflection plate and a light guiding plate.
[5] Therefore, the side-lit type backlight unit is used generally for a mobile phone, a personal digital assistant (PDA), a vehicle navigator, and a laptop.
[6] However, the side-lit type backlight unit having a light emitting diode (LED) lamp on the lateral side of the liquid crystal panel is inferior in lighting efficiency and therefore inappropriate for a wide-area liquid crystal panel.
[7] In addition, since the side-lit backlight unit supplies the light through the light guiding plate, a lot of LEDs are required to obtain high brightness. This also deteriorates applicability of the side-lit type backlight unit to the wide-area liquid crystal panel. [8] As shown in FIGS. 1 through 3, various conventional configurations of a bottom surface of the light guiding plate for improving brightness of the side-slit type backlight unit have been suggested.
[9] In FIG. 1, a bottom surface of a light guiding plate 11 is arranged in a circular or oval reflection pattern 1 Ia. In FIG. 2, another light guiding plate 12 has a bottom surface arranged in a pyramided reflection pattern 12a. However, these are not only limited to obtain high brightness as desired but also complicated in structure. Therefore, manufacture and production of such light guiding plates are difficult and uneconomical.
[10] FIG. 3 shows yet another light guiding plate 13 having a prism array unit 13a linearly arranged on a bottom surface thereof. This light guiding plate 13 is effective in obtaining the high brightness; however, can not achieve optical uniformity on the whole, thereby causing bright lines. The bright lines deteriorate quality of a surface light source with respect to the light guiding plate.
[11] Consequently, the backlight unit adopting the conventional light guiding plate comprises an LED lamp for emitting light, the light guiding plate for diffusing the light generated from the LED lamp and guiding the light toward the surface light source, a reflection plate for reflecting the light from a lower part of the light guiding plate to an upper part where the liquid crystal panel is disposed, and a diffusion plate and a prism sheet for controlling diffusion and an advancing direction of the light passed through the light guiding plate.
[12] The light passed through the light guiding plate is diffused in all directions by the diffusion plate, and then controlled by the prism sheet to advance perpendicularly to the liquid crystal panel. The light passed through the prism sheet is thus incident on the liquid crystal panel.
[13] However, such conventional light guiding plates of the backlight unit for high brightness induce the bright lines since most of the light generated from the LED lamp is straightly incident. The bright lines disturb favorable diffusion of the light and cause loss of the light in the liquid crystal panel. Finally, brightness and optical uniformity are deteriorated.
[14] The bright lines caused by unevenly formed light, especially appearing where the light is strong, are shown as thick lines on a screen of the liquid crystal panel.
[15] Since such uneven light is incident on the liquid crystal panel, high brightness is hard to be achieved in the conventional light guiding plates. Therefore, the conventional light guiding plates are not appropriate for wide-area liquid crystal panels.
[16] In other words, the conventional light guiding plates for high brightness, and the backlight unit using the same having poor brightness and optical uniformity can not be reliably applied to the liquid crystal panel. Disclosure of Invention
Technical Problem
[17] Therefore, the present invention has been made in view of the above-mentioned problems, and it is an object of the present invention to provide a light guiding plate for a liquid crystal display (LCD) comprising an incident light lens unit and a light guide plate (LGP) upper surface, the incident light lens unit having a serrated fresnel part and a space part for total reflection, so that generation of bright lines caused while light from the incident light lens unit is incident on the LGP upper surface can be minimized, and accordingly the light straightly advancing can be distributed planarly and favorably projected in a vertical direction, and a backlight unit and a LCD using the same.
[18] It is another object of the present invention to provide a light guiding plate capable of improving light condensing efficiency and brightness by variably refracting the incident light and diffusing the light planarly, and minimizing loss of the light by improving optical uniformity, and a backlight unit and an LCD using the same. Technical Solution
[19] According to an aspect of the present invention, there is provided a light guiding plate of a liquid crystal panel for a liquid crystal display (LCD), the liquid crystal panel having liquid crystal cells arranged in an active matrix form to adjust optical transmittance of light projected from a lower part thereof, comprising an incident light lens unit having a fresnel part serrated for diffusion and reflection of light, in order to project the light which is a surface light source toward the liquid crystal panel.
[20] According to another embodiment, there is provided a light guiding plate of a liquid crystal panel for an LCD, the liquid crystal panel having liquid crystal cells arranged in an active matrix form to adjust optical transmittance of light projected from a lower part thereof, comprising an incident light lens unit having a fresnel part serrated for diffusion and reflection of light to project the light which is a surface light source toward the liquid crystal panel, and a space part having a trigonal or other polygonal prism form for performing internal total reflection of the light; and a light guiding plate (LGP) upper surface having a protrusion end inserted and mounted in part of the space part of the incident light lens unit.
[21] According to yet another embodiment, there is provided a light guiding plate of a liquid crystal panel for an LCD, the liquid crystal panel having liquid crystal cells arranged in an active matrix form to adjust optical transmittance of light projected from a lower part thereof, comprising an incident light lens unit having a fresnel part serrated for diffusion and reflection of light to project the light which is a surface light source toward the liquid crystal panel, and a space part having a trigonal or other polygonal prism form for performing internal total reflection of the light; and an LGP upper surface having a protrusion end inserted and mounted in part of the space part of the incident light lens unit, and wherein a connection area of the incident light lens unit with the LGP upper surface is unevenly formed for diffusion of the light.
[22] The incident light lens unit includes a light-incident part that directly receives the light from the luminous lamp such as a light emitting diode (LED) and is formed as one of a concave lens, a convex lens, a plane, and a plane rounded at both side edges.
[23] When the light-incident part of the incident light lens unit has the plane form, the plane has unevenness thereon.
[24] The space part formed in the incident light lens unit has an isosceles shape having two fresnel reflection surfaces symmetrical with respect to a vertex thereof.
[25] In the serrated fresnel part formed in the incident light lens unit, angles of a prism constituting the reflection surface have ranges as follows: 5°<α<60°, 55°<β<95°, 5°<ω<60°.
[26] The light-incident part of the incident light lens unit is rounded by the approximately 0.01~10mm of radius of curvature V.
[27] The unevenness at the connection area of the incident light lens unit has one of a prism form, a rounded groove form, and a wave form.
[28] Another aspect of the present invention is to provide a backlight unit applied to an
LCD for projecting white light from a rear side of a liquid crystal panel, comprising a luminous lamp such as an LED for generating and emitting light; a light guiding plate including an incident light lens unit having a fresnel part serrated for diffusion and reflection of light to project the light which is a surface light source toward the liquid crystal panel and a space part having a trigonal or other polygonal prism form for performing internal total reflection of the light, and an LGP upper surface having a protrusion end inserted and mounted in part of the space part of the incident light lens unit; a diffusion plate and a prism sheet for adjusting diffusion and an advancing direction of the light passed through the light guiding plate; and a reflection plate for reflecting the light generated from the luminous lamp and the light directed from the light guiding plate.
[29] A connection area of the incident light lens unit with the LGP upper surface is unevenly formed for diffusion of the light.
[30] The incident light lens unit includes a light-incident part that directly receives the light from the luminous lamp such as a light emitting diode (LED) and is formed as one of a concave lens, a convex lens, a plane, and a plane rounded at both side edges.
[31] The space part formed in the incident light lens unit has an isosceles shape having two fresnel reflection surfaces symmetrical with respect to a vertex thereof.
[32] A plurality of the protrusion ends are formed at one side or both sides of the incident light lens unit, and a plurality of the incident light lens units for mounting the protrusion ends therein are correspondingly formed.
[33] Yet another aspect of the present invention is to provide an LCD comprising a backlight unit that includes a light guiding plate having an incident light lens unit having a fresnel part serrated for diffusion and reflection of light and a space part having a trigonal or other polygonal prism form for performing internal total reflection of the light, and an LGP upper surface having a protrusion end mounted in part of the space part of the incident light lens unit; and a liquid crystal panel connected with the backlight unit and comprising liquid crystal cells that adjust optical transmittance, being arranged in an active matrix form, thereby displaying an image by the light projected from the backlight unit.
[34] A connection area of the incident light lens unit with the LGP upper surface is unevenly formed for diffusion of the light.
[35] The incident light lens unit includes a light-incident part that directly receives the light from the luminous lamp such as a light emitting diode (LED) and is formed as one of a concave lens, a convex lens, a plane, and a plane rounded at both side edges.
Advantageous Effects
[36] According to the present invention, bright lines that used to be generated while the light is incident from an incident light lens unit to a light guiding plate (LGP) upper surface can be minimized. As a result, the light straightly advancing toward the LGP upper surface can be distributed planarly and projected vertically. [37] Furthermore, since the light being incident on the light guiding plate can be variably refracted and distributed planarly, light condensing efficiency and brightness in a liquid crystal panel can be improved. Also, optical uniformity is improved, thereby minimizing loss of the light. [38] Eventually, by applying such a light guiding plate and a backlight unit using the same, consumer's satisfaction with the product such as a huge liquid crystal panel can be maximized.
Brief Description of the Drawings [39] The foregoing and other objects, features and advantages of the present invention will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings in which: [40] FIGS. 1 through 3 are sectional views showing examples of a reflection pattern of a bottom surface of conventional light guiding plates; [41] FIG. 4 is a schematic view for explaining an incident light lens unit of a light guiding plate according to an embodiment of the present invention; [42] FIG. 5 shows shape of a vertex of a space part of the incident light lens unit according to an embodiment of the present invention; [43] FIG. 6 shows an embodiment of the present invention wherein a light-incident part of the incident light lens unit has a convex lens form; [44] FIG. 7 shows another embodiment of the present invention wherein a light-incident part of the incident light lens unit has a concave lens form;
[45] FIG. 8 shows yet another embodiment of the present invention wherein a light- incident part of the incident light lens unit is plane; [46] FIGS. 9 through 13 show examples of the light- incident part of the incident light lens unit of FIG. 8, having an uneven surface;
[47] FIG. 14 shows yet another embodiment of the present invention wherein the light- incident part of the incident light lens unit is formed as a plane rounded on both side edges; [48] FIGS. 15 through 19 show various types of the light-incident part of the light guiding plate according to the present invention; [49] FIG. 20 shows the incident light lens unit of the light guiding plate connected with a light guiding plate (LGP) upper surface, according to the present invention; [50] FIG. 21 is a side view showing the connection state between the incident light lens unit and the LGP upper surface according to the present invention; [51] FIG. 22 shows an example wherein the light guiding plate according to the present invention is applied to a backlight unit; [52] FIG. 23 shows diffusion and refraction operations of the incident light lens unit of the light guiding plate according to the present invention; and [53] FIG. 24 shows the structure of a liquid crystal display (LCD) applying the backlight unit according to the present invention.
Best Mode for Carrying Out the Invention [54] Reference will now be made in detail to the preferred embodiments of the present invention with reference to the accompanying drawings. [55] In the following description, well-known functions or constructions are not described in detail since they would obscure the invention in unnecessary detail. The terms hereinafter are selected in consideration of functions in the present invention.
Therefore, the terms can be varied according to custom or intentions of users, operators and producers. [56] FIG. 4 schematically shows an embodiment of an incident light lens unit of a light guiding plate. FIG. 5 shows an exemplary shape of a vertex of a space part of the incident light lens unit, according to the present invention. [57] FIGS. 6 through 14 show embodiments regarding a light-incident part of the incident light lens unit according to the present invention. [58] According to the present invention, a liquid crystal panel (not shown) for a liquid crystal display (LCD) comprises liquid crystal cells for adjusting transmittance of light projected from a lower part thereof, being arranged in an active matrix form. In the liquid crystal panel, a light guiding plate 20 for projecting light, which is a surface light source, toward the liquid crystal panel includes an incident light lens unit 21. The incident light lens unit comprises a serrated fresnel part 21a for diffusion of the light.
[59] The fresnel part 21a of the incident light lens unit 21 is formed as a plurality of sawlike teeth to enhance efficiency of diffusion and refraction for the incident light.
[60] A light- incident part is formed at the incident light lens unit 21 in the form of a convex lens as shown in FIG. 6, a concave lens in FIG. 7, a plane in FIGS. 8 through 13, or a plane rounded at both side edges in FIG. 14. The light from a luminous lamp such as a light emitting diode (LED) is directly incident on the light- incident part. The incident light lens unit 21 further comprises a space part 21b for total reflection of the light therein.
[61] The plane light- incident part of FIG. 8 has an uneven surface in various types as shown in FIGS. 9 through 13.
[62] The space part 21b of the incident light lens unit 21 includes an entry end 21-1 so that a dedicated member can be facilely inserted and mounted.
[63] The space part 21b of the incident light lens unit 21 is formed in an isosceles shape having two fresnel reflection surfaces symmetrical with respect to a vertex thereof. In the fresnel part 21a formed at the incident light lens unit 21, angles of a prism constituting the reflection surface have ranges as follows: 5°<α<60°, 55°<β<95°, 5°<ω<60°.
[64] In an exemplary incident light lens unit 21, a corner of the space part 21b provided for internal total reflection forms a right angle.
[65] When the light-incident part of the incident light lens unit 21 has a convex lens form as shown in FIG. 6, the radius of curvature V of the convex portion is approximately 0.01-lOmm.
[66] According to the light guiding plate 20 for an LCD of the present invention, an unevenness may be formed at a connection area between the incident light lens unit 21 and a light guiding plate (LGP) upper surface 22 in various forms, such that the light can be advanced as uniformly as possible toward the liquid crystal panel.
[67] Although diverse embodiments of the incident light lens unit 21 of the light guiding plate 20 are suggested in FIGS. 15 through 19, it is apparent that the present invention is not limited to the embodiments.
[68] More specifically, FIGS. 15 through 19 show various types of the unevenness formed at the connection area in the structure where the light-incident part is convex on the right and concave on the left. However, other types of the unevenness can be applied as shown in FIGS. 8 through 14. [69] Referring to FIG. 15, rounded corrugation is formed at a connection area 23 where the incident light lens unit 21 is contacted with the LGP upper surface 22. Therefore, the light can be advanced more uniformly through the fresnel part 21a for diffusion of the light and the space part 21b for the internal total reflection. [70] Referring to FIG. 16, prismatic corrugation is formed at the connection area 23 between the incident light lens unit 21 and the LGP upper surface 22. This also helps the light advance more uniformly through the fresnel part 21a and the space part 21b. [71] Referring to FIG. 17, semicircular grooves are formed parallel at the connection area 23 between the incident light lens unit 21 and the LGP upper surface 22, such that the light can be advanced more uniformly through the fresnel part 21a and the space part 21b. [72] Referring to FIG. 18, semicircular cylinders are formed parallel at the connection area 23 between the incident light lens unit 21 and the LGP upper surface 22 for the same purpose. [73] Referring to FIG. 19, waves are formed at the connection area 23 between the incident light lens unit 21 and the LGP upper surface 22 for the same purpose. [74] The connection structure between the incident light lens unit 21 and the LGP upper surface 22 of the light guiding plate 20 according to the present invention will be explained hereinafter. [75] FIG. 20 shows the incident light lens unit 21 and the LGP upper surface 22 being connected to each other. FIG. 21 is a side view showing the connected state of the incident light lens unit 21 and the LGP upper surface 22. [76] Although not shown in FIG. 20, it is apparent that the unevenness at the connection area 23 between the incident light lens unit 21 and the LGP upper surface 22 can still be applied. [77] In addition, a reflection pattern is formed on a bottom surface of the LGP upper surface 22. Various types can be applied for the reflection pattern. [78] The light guiding plate 20 in the liquid crystal panel for an LCD wherein the liquid crystal cells for adjusting optical transmittance are arranged in the matrix form comprises the incident light lens unit 21 and the LGP upper surface 22. The incident light lens unit 21 comprises the fresnel part 21a serrated for diffusion of the light, and the space part 21b for internal total reflection of the light. The LGP upper surface 22 comprises a protrusion end 22a to be inserted and mounted in part of the space part 21b of the incident light lens unit 21. [79] The incident light lens unit 21 and the LGP upper surface 22 are integrally formed with each other, rather than being separated. A plurality of the protrusion ends 22a are formed at one side of the LGP upper surface 22. Correspondingly, a plurality of the incident light lens units 21 are provided for mounting of the respective protrusion ends 22a.
[80] Alternatively, a plurality of the protrusion ends 22a are formed at one side and the other side of the LGP upper surface 22, respectively. Also, a plurality of the incident light lens units 21 are formed corresponding to the respective protrusion ends 22a.
[81] The protrusion ends 22a of the LGP upper surface 22 are formed incompactly near a light-incident surface and compactly toward the center, so that the incident light can be projected uniformly in a direction of a viewing angle.
[82] The incident light passed through the incident light lens unit 21 is compacter at the center. More particularly, the incident light becomes compacter as being moved to the center.
[83] Hereinafter, description will be made about the structures of a backlight unit applying the light guiding plate 20 as described above and an LCD applying the backlight unit.
[84] FIG. 22 shows an example of the backlight unit applying the light guiding plate according to an embodiment of the present invention. FIG. 23 shows diffusion and refraction operations of the incident light lens unit 21 of the light guiding plate according to an embodiment of the present invention.
[85] FIG. 24 shows an example of the LCD applying the backlight unit according to an embodiment of the present invention.
[86] The backlight unit of FIG. 22 is structured to uniformly project white light from a rear side of the liquid crystal panel, being applied to the LCD.
[87] The backlight unit comprises a luminous lamp 100, a light guiding plate 200, a diffusion plate 300 and a prism sheet 400, and a reflection plate 500. The luminous lamp 100 such as an LED generates and emits light. The light guiding plate 200 includes the incident light lens unit 21 and the LGP upper surface 22 to facilitate vertical projection of the light generated from the luminous lamp 100. The diffusion plate 300 and the prism sheet 400 control diffusion and an advancing direction of the light passed through the light guiding plate 200. The reflection plate 500 reflects the light generated from the luminous lamp 100 and the light directed from the light guiding plate 200.
[88] The light guiding plate 200 comprises the incident light lens unit 21 and the LGP upper surface 22. The incident light lens unit 21 comprises the fresnel part 21a serrated for diffusion of the light, and the space part 21b for internal total reflection of the light. The LGP upper surface 22 comprises the protrusion end 22a to be inserted and mounted in part of the space part 21b of the incident light lens unit 21. A plurality of the protrusion ends 22a are formed at one side of the LGP upper surface 22. Correspondingly, a plurality of the incident light lens units 21 are provided for mounting of the respective protrusion ends 22a.
[89] In an alternative structure, a plurality of the protrusion ends 22a are formed at one side and the other side of the LGP upper surface 22, respectively. Also, a plurality of the incident light lens units 21 are formed corresponding to the respective protrusion ends 22a.
[90] First of all, the object of the present invention is in minimizing bright lines caused while the light is being incident on the incident light lens unit 21 and in facilely projecting the light in a vertical direction, by planarly distributing the light straightly advancing to the LGP upper surface 22.
[91] To this end, the light guiding plate 200 is provided with the incident light lens unit
21 as described above. Since the fresnel part 21a having a serrated form is disposed on a side of the incident light lens unit 21, the light projected from the luminous lamp 100 such as the LED is diffused by the serration structure, and facilely distributed planarly as shown in FIG. 16.
[92] FIG. 23 shows diffusion and refraction operations of the light guiding plate 20 through simulation. Referring to the drawing, the incident light lens unit 21 provided to the light guiding plate 200 of the backlight unit can variably diffuse and refract the light and as a result, brightness and optical uniformity are considerably improved in the liquid crystal panel. Accordingly, the bright lines can be prevented.
[93] Additionally, the space part 21b having a prism pattern and provided to the incident light lens unit 21 internally generates total reflection, thereby inducing diffusion and refraction of the light. Therefore, the light can be distributed more planarly, and the optical uniformity can be enhanced.
[94] Furthermore, because the light- incident part directly receiving the light from the luminous lamp 100 has a concave form or a convex form, the light can be distributed more planarly through diffusion, refraction and reflection.
[95] It will be sure understood that various structures for the connection area 23 between the incident light lens unit 21 and the LGP upper surface 22 of the light guiding plate can be applied, in order to enhance more uniform advance of the light that has been advancing through the serrated fresnel part 21a and the space part 21b.
[96] The prismatic space part 21b of the incident light lens unit 21 includes the entry end
21-1 which is opened. Therefore, when the incident light lens unit 21 is connected with another dedicated member, the member can be easily inserted and mounted into the incident light lens unit 21.
[97] The space part 21b formed in the incident light lens unit 21 has an isosceles shape having two fresnel reflection surfaces symmetrical with respect to a vertex thereof.
[98] In an exemplary incident light lens unit 21, a corner of the space part 21b for internal total reflection forms a right angle. [99] In addition, when the light- incident part of the incident light lens unit 21 has a convex lens form as shown in FIG. 6, the radius of curvature V of the convex portion is approximately 0.01~10mm.
[100] The light guiding plate 20 is dedicatedly provided with the LGP upper surface 22 for engagement with the incident light lens unit 21. The LGP upper surface 22 includes the protrusion end 22a inserted and mounted in part of the space part 21b of the incident light lens unit 21.
[101] When the protrusion end 22a of the LGP upper surface 22 is insertedly connected with the entry end 21-1 of the space part 21b of the incident light lens unit 21, the light incident on the serrated fresnel part 21a and the space part 21b of the incident light lens unit 21 is distributed more planarly and projected at the LGP upper surface 22 more vertically because the bright lines caused by straightness of the incident light can be prevented.
[102] The incident light lens unit 21 and the LGP upper surface 22 of the light guiding plate 200 are integrated, not being separated. A plurality of the protrusion ends 22a are formed at one side of the LGP upper surface 22 and inserted in the entry ends 21-1 of the space part 21b formed at the incident light lens unit 21. As a result, the efficiency of optical diffusion and refraction can be enhanced. Also, since the light is vertically projected as being almost completely distributed, the brightness and the optical uniformity can be enhanced overall.
[103] In a state where the incident light lens unit 21 is connected to both sides of the LGP upper surface 22, as described above, as the light from the luminous lamp 100 such as the LED passes through the incident light lens unit 21, the incident light becomes compacter as being moved from periphery of the LGP upper surface 22, neighboring the incident light lens unit 21, toward the center.
[104] When the backlight unit is applied to the LCD to uniformly project white light from the rear side of the liquid crystal panel, the reflection plate 500 is disposed at a lower end of the backlight unit. The reflection plate 500 reflects the light upward to the liquid crystal panel. The light guiding plate 200 is disposed at an upper part of the reflection plate 500 in order to favorably diffuse the light generated from the luminous lamp 100 and project the light toward the surface light source.
[105] The diffusion plate 300 and the prism sheet 400 are respectively provided on the upper part of the light guiding plate 200, to control the diffusion and the advancing direction of the light that is passed through the incident light lens unit 21.
[106] The light is planarly distributed through the light guiding plate 200 applied to the backlight unit. Consequently, the brightness and the optical uniformity with respect to the liquid crystal panel are improved.
[107] A plurality of the protrusion ends 22a formed at one side of the LGP upper surface 22 are inserted and mounted in the entry ends 21-1 of the space part 21b formed at the incident light lens unit 21.
[108] Also, when the protrusion ends 22a are formed at both one side and the other side of the LGP upper surface 22, the respective protrusion ends 22a are inserted and mounted in the entry ends 21-1 of the space part 21b.
[109] According to the above, the light from the luminous lamp 100 can be vertically projected and furthermore, the brightness and the optical uniformity can be improved by preventing the bright lines.
[110] The light guiding plate 20 and the light guiding plate 200 applied to the backlight unit may be structured in various ways according to size of the liquid crystal panel.
[I l l] More specifically, the size of the liquid crystal panel can be varied by connecting a plurality of the incident light lens units 21 and the LGP upper surfaces 22, in the same manner of connecting a single incident light lens unit 21 on both sides of a single LGP upper surface 22. Therefore, such modified structure is still within the scope of the present invention.
[112] The light guiding plate 20 and the light guiding plate 200 of the backlight unit are implemented by a transparent material such as plastic and resin, so that the light can be favorably diffused and refracted. For example, polycarbonate (PC) and polymethylmethacrylate (PMMA) can be applied for the transparent material.
[113] The luminous lamp 100 may comprise red, green and blue LEDs, or a white LED.
[114] FIG. 24 shows the structure of an LCD applying the backlight unit having the light guiding plate 200 according to the present invention.
[115] The LCD comprises the luminous lamp 100 such as the LED for generating and emitting light, the light guiding plate 200 including the incident light lens unit 21 and the LGP upper surface 22 to facilitate vertical projection of the light, the diffusion plate 300 and the prism sheet 400 for controlling diffusion and the advancing direction of the light passed through the light guiding plate 200, and the reflection plate 500 for reflecting the light generated from the luminous lamp 100 and the light directed from the light guiding plate 200.
[116] A liquid crystal panel 600 is further comprised, being connected with the backlight unit. Comprising the liquid crystal cells arranged in the active matrix form to adjust transmittance of the incident light, the liquid crystal panel 600 displays an image by the light transmitted through the backlight unit.
[117] The light guiding plate 20 for an LCD, and the backlight unit and the LCD using the same can be modified in various structures and shapes. The matters and elements defined in the above description are nothing but the ones provided to assist in a comprehensive understanding of the invention. It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims. Industrial Applicability
[118] The light guiding plate according to the present invention comprises an incident light lens unit and an LGP upper surface. The incident light lens unit includes a fresnel part having a serrated form for optical diffusion and refraction, and a space part for internally performing total reflection with respect to the light source. The LGP upper surface includes a protrusion end to be inserted and mounted in the space part.
[119] The light guiding plate planarly distributes the light incident thereon by variably diffusing, reflecting and refracting the light. As a result, light-condensing efficiency and brightness of the liquid crystal panel can be enhanced.
[120] Moreover, the light guiding plate, and the backlight unit and the LCD using the same are provided to minimize loss of the light, by improving optical uniformity of the light advancing to the liquid crystal panel.

Claims

Claims
[1] A light guiding plate of a liquid crystal panel for a liquid crystal display (LCD), the liquid crystal panel having liquid crystal cells arranged in an active matrix form to adjust optical transmittance of light projected from a lower part thereof, comprising an incident light lens unit having a fresnel part serrated for diffusion and reflection of light, in order to project the light which is a surface light source toward the liquid crystal panel.
[2] A light guiding plate of a liquid crystal panel for an LCD, the liquid crystal panel having liquid crystal cells arranged in an active matrix form to adjust optical transmittance of light projected from a lower part thereof, comprising: an incident light lens unit having a fresnel part serrated for diffusion and reflection of light to project the light which is a surface light source toward the liquid crystal panel, and a space part having a trigonal or other polygonal prism form for performing internal total reflection of the light; and a light guiding plate (LGP) upper surface having a protrusion end inserted and mounted in part of the space part of the incident light lens unit.
[3] A light guiding plate of a liquid crystal panel for an LCD, the liquid crystal panel having liquid crystal cells arranged in an active matrix form to adjust optical transmittance of light projected from a lower part thereof, comprising: an incident light lens unit having a fresnel part serrated for diffusion and reflection of light to project the light which is a surface light source toward the liquid crystal panel, and a space part having a trigonal or other polygonal prism form for performing internal total reflection of the light; and an LGP upper surface having a protrusion end inserted and mounted in part of the space part of the incident light lens unit, and wherein a connection area of the incident light lens unit with the LGP upper surface is unevenly formed for diffusion of the light.
[4] The light guiding plate for an LCD of one of claim 1, claim 2 and claim 3, wherein the incident light lens unit includes a light-incident part that directly receives the light from the luminous lamp such as a light emitting diode (LED) and is formed as one of a concave lens, a convex lens, a plane, and a plane rounded at both side edges.
[5] The light guiding plate for an LCD of claim 4, wherein, when the light-incident part of the incident light lens unit has the plane form, the plane has unevenness thereon.
[6] The light guiding plate for an LCD of one of claim 1, claim 2, and claim 3, wherein the space part formed in the incident light lens unit has an isosceles shape having two fresnel reflection surfaces symmetrical with respect to a vertex thereof.
[7] The light guiding plate for an LCD of one of claim 1, claim 2, and claim 3, wherein, in the serrated fresnel part formed in the incident light lens unit, angles of a prism constituting the reflection surface have ranges as follows: 5°<α<60°, 55°<β<95°, 5°<ω<60°.
[8] The light guiding plate for an LCD of one of claim 1, claim 2, and claim 3, wherein the light-incident part of the incident light lens unit is rounded by the approximately 0.01~10mm of radius of curvature V.
[9] The light guiding plate for an LCD of claim 3, wherein the unevenness at the connection area of the incident light lens unit has one of a prism form, a rounded groove form, and a wave form.
[10] A backlight unit applied to an LCD for projecting white light from a rear side of a liquid crystal panel, comprising: a luminous lamp such as an LED for generating and emitting light; a light guiding plate including an incident light lens unit having a fresnel part serrated for diffusion and reflection of light to project the light which is a surface light source toward the liquid crystal panel and a space part having a trigonal or other polygonal prism form for performing internal total reflection of the light, and an LGP upper surface having a protrusion end inserted and mounted in part of the space part of the incident light lens unit; a diffusion plate and a prism sheet for adjusting diffusion and an advancing direction of the light passed through the light guiding plate; and a reflection plate for reflecting the light generated from the luminous lamp and the light directed from the light guiding plate.
[11] The backlight unit of claim 10, wherein a connection area of the incident light lens unit with the LGP upper surface is unevenly formed for diffusion of the light.
[12] The backlight unit of claim 10, wherein the incident light lens unit includes a light- incident part that directly receives the light from the luminous lamp such as a light emitting diode (LED) and is formed as one of a concave lens, a convex lens, a plane, and a plane rounded at both side edges.
[13] The backlight unit of claim 10, wherein the space part formed in the incident light lens unit has an isosceles shape having two fresnel reflection surfaces symmetrical with respect to a vertex thereof.
[14] The backlight unit of claim 10, wherein a plurality of the protrusion ends are formed at one side or both sides of the incident light lens unit, and a plurality of the incident light lens units for mounting the protrusion ends therein are corre- spondingly formed.
[15] An LCD comprising: a backlight unit that includes a light guiding plate having an incident light lens unit having a fresnel part serrated for diffusion and reflection of light and a space part having a trigonal or other polygonal prism form for performing internal total reflection of the light, and an LGP upper surface having a protrusion end mounted in part of the space part of the incident light lens unit; and a liquid crystal panel connected with the backlight unit and comprising liquid crystal cells that adjust optical transmittance, being arranged in an active matrix form, thereby displaying an image by the light projected from the backlight unit.
[16] The LCD of claim 15, wherein a connection area of the incident light lens unit with the LGP upper surface is unevenly formed for diffusion of the light.
[17] The LCD of claim 15, wherein the incident light lens unit includes a light- incident part that directly receives the light from the luminous lamp such as a light emitting diode (LED) and is formed as one of a concave lens, a convex lens, a plane, and a plane rounded at both side edges.
PCT/KR2006/003027 2005-08-05 2006-08-01 Lcd light guiding plate and back light unit and lcd using a thereof WO2007018361A1 (en)

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