WO2012056660A1

WO2012056660A1 - Liquid crystal display device and method for manufacturing same

Info

Publication number: WO2012056660A1
Application number: PCT/JP2011/005889
Authority: WO
Inventors: 昌紀景山
Original assignee: シャープ株式会社
Priority date: 2010-10-25
Filing date: 2011-10-20
Publication date: 2012-05-03

Abstract

The present liquid crystal display device is provided with: a liquid crystal display panel (10); and a backlight unit (11) which is a lighting device disposed on the opposite side of the liquid crystal display panel (10) from the viewer. The backlight unit (11) has a light guide plate (13) and light sources (24) for inputting light into the side surfaces of the light guide plate. The light sources (24) are mounted on the surface of the liquid crystal display panel (10) which is located on the side where the backlight unit is located. The configuration can facilitate the assembly of the liquid crystal display device and, in addition, can improve the positional accuracy of the light sources.

Description

Liquid crystal display device and manufacturing method thereof

The present invention relates to a liquid crystal display device that performs transmissive display and a manufacturing method thereof.

Generally, a liquid crystal display device that performs transmissive display includes a liquid crystal display panel and a backlight unit that is a light source disposed on the back side (opposite to the observer) of the liquid crystal display panel.

As shown in FIG. 7, the liquid crystal display device 101 described in Patent Document 1 includes a liquid crystal display panel 102, an FPC (flexible として printed circuit) 105 as a light source substrate, and a backlight unit 104. Yes.

The backlight unit 104 includes a light guide plate 111, an LED (Light Emitting Diode) 106 serving as a light source disposed to face the light incident surface 111a of the light guide plate 111, a reflection sheet 113, and a diffusion sheet as an optical sheet. 114.

The reflection sheet 113 is disposed on the back side of the light guide plate 111, while the diffusion sheet 114 is disposed on the viewer side of the light guide plate 111. The light guide plate 111 is fitted inside the frame 131. The frame 131 is made of plastic, for example. An adhesive member 132 is interposed between the light guide plate 111 and the liquid crystal display panel 102.

The liquid crystal display panel 102 includes a TFT substrate 122 in which a plurality of pixels are formed and a TFT (Thin-Film-Transistor) is formed for each pixel, and a counter substrate 121 that faces the TFT substrate 122. . The driving IC 103 is mounted on the TFT substrate 122 by COG (Chip On On Glass) technology using, for example, ACF (Anisotropic Conductive Film) 133. The driving IC 103 drives the liquid crystal display panel 102 by outputting scanning signals and data signals to the electrodes of the liquid crystal display panel 102.

A plurality of external connection terminals 134 are formed on the side edges of the TFT substrate 122. These external connection terminals 134 are connected to the input terminals of the driving IC 103 by the ACF 133. Further, one end of the FPC 105 which is a flexible wiring board is connected to these external connection terminals 134 by an ACF 133.

The other end side of the FPC 105 is folded back to the back side of the backlight unit 104, and a plurality of circuit components 135 necessary for driving the liquid crystal display panel 102 are mounted thereon. The LED 106 is mounted on the FPC 105 by solder. A gap is provided between the LED 106 and the liquid crystal display panel 102.

As described above, in the conventional liquid crystal display device 101, the LED 106 is mounted on the surface of the FPC 105 with the surface of the FPC 105 folded back on the back side of the backlight unit 104 as the assembly reference surface of the LED 106.

JP 2006-92985 A

However, in the above conventional liquid crystal display device, the surface of the FPC disposed on the back side of the backlight unit is used as the assembly reference surface of the LED, so that the LED is positioned in the vertical direction that is perpendicular to the surface of the liquid crystal display panel. It is difficult to shift and it is difficult to improve the positional accuracy of the light source that is an LED.

Furthermore, the conventional liquid crystal display device requires a separate process of mounting the FPC on the liquid crystal display panel after the process of mounting the LED on the FPC, which poses a problem of assembling the liquid crystal display device.

The present invention has been made in view of such various points, and an object of the present invention is to improve the positional accuracy of the light source and facilitate the assembly of the liquid crystal display device in a liquid crystal display device that performs transmissive display. There is to do.

In order to achieve the above object, a liquid crystal display device according to the present invention includes a liquid crystal display panel and a backlight unit that is a lighting device disposed on the opposite side of the observer of the liquid crystal display panel. The backlight unit includes a light guide plate and a light source that makes light incident on a side surface of the light guide plate, and the light source is directly mounted on a surface of the liquid crystal display panel opposite to the observer. Has been.

In addition, a method for manufacturing a liquid crystal display device according to the present invention includes a liquid crystal display panel and a back light source that is disposed on the opposite side of the liquid crystal display panel from the observer and that makes light incident on the side surface of the light guide plate. A method of manufacturing a liquid crystal display device including a light unit, the method including a step of directly mounting the light source on a surface of the liquid crystal display panel opposite to the observer.

-Action-
In the liquid crystal display device, since the light source of the backlight unit is mounted on the surface of the liquid crystal display panel on the backlight unit side, a substrate for mounting a light source such as an FPC is independent of the liquid crystal display panel. There is no need to provide it. Therefore, since the light source can be assembled at the same time in the assembly process of the liquid crystal display panel, the assembly of the liquid crystal display device can be facilitated. Furthermore, since the light source is fixed to the liquid crystal display panel, the positional accuracy of the light source can be increased.

According to the present invention, for a liquid crystal display device having a liquid crystal display panel and a backlight unit, a light source such as an FPC is mounted by mounting the light source of the backlight unit on the surface of the liquid crystal display panel on the backlight unit side. Therefore, it is not necessary to provide a separate substrate separately from the liquid crystal display panel, so that the light source can also be assembled at the same time in the assembly process of the liquid crystal display panel. As a result, the assembly of the liquid crystal display device can be facilitated. In addition, since the light source is fixed to the liquid crystal display panel, the positional accuracy of the light source can be increased.

FIG. 1 is a cross-sectional view showing the main structure of the liquid crystal display device according to the first embodiment. FIG. 2 is a perspective view showing the LED package. FIG. 3 is a side view showing an LED package mounted on the liquid crystal display panel by ACF. FIG. 4 is a cross-sectional view showing the main structure of the liquid crystal display device according to the second embodiment. FIG. 5 is an enlarged cross-sectional view of a part of FIG. FIG. 6 is a cross-sectional view showing the main structure of the liquid crystal display device according to the third embodiment. FIG. 7 is a cross-sectional view showing the main structure of a conventional liquid crystal display device.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The present invention is not limited to the following embodiment.

Embodiment 1 of the Invention
1 to 3 show Embodiment 1 of the present invention.

FIG. 1 is a cross-sectional view showing the main structure of the liquid crystal display device 1 according to the first embodiment. FIG. 2 is a perspective view showing the LED package 24. FIG. 3 is a side view showing the LED package 24 mounted on the liquid crystal display panel 10 by the ACF 36.

As shown in FIG. 1, the liquid crystal display device 1 according to the first embodiment includes a liquid crystal display panel 10 and an illuminating device arranged on the opposite side of the liquid crystal display panel 10 from the observer (hereinafter also referred to as a back side). As a backlight unit 11. Thus, the liquid crystal display device 1 is configured such that the liquid crystal display panel 10 selectively transmits the light of the backlight unit 11 to perform transmissive display.

Although the detailed illustration of the liquid crystal display panel 10 is omitted, for example, a TFT substrate 31 in which a plurality of TFTs (Thin-Film Transistors) and pixel electrodes are formed for each of a plurality of pixels, and the TFT substrate 31 The liquid crystal layer (not shown) sealed between the TFT substrate 31 and the counter substrate 32 is provided.

Although not shown, the counter substrate 32 is provided with a color filter, a common electrode, and the like on a transparent substrate such as a glass substrate. The liquid crystal layer is sealed by a sealing member (not shown) provided between the TFT substrate 31 and the counter substrate 32. A polarizing plate 33 is attached to the surface of the counter substrate 32 opposite to the TFT substrate 31.

On the other hand, the TFT substrate 31 is formed with a plurality of source wirings extending in parallel to each other and a plurality of gate wirings extending perpendicularly to them on a transparent substrate such as a glass substrate, although not shown. Yes. That is, the wiring group composed of the gate wiring and the source wiring is formed in a lattice shape as a whole. Pixels are formed in the lattice area. Although not shown, each pixel is formed with a TFT serving as a switching element and a pixel electrode connected to the TFT. The TFT is connected to the source wiring and the gate wiring. A polarizing plate 34 is attached to the surface of the TFT substrate 31 opposite to the counter substrate 32.

The backlight unit 11 is configured in a so-called edge light system. As shown in FIG. 1, the backlight unit 11 includes a light guide plate 13 and an LED package 24 that is a light source for making light incident on a side surface (incident surface) 13a of the light guide plate 13. Have. The backlight unit 11 and the liquid crystal display panel 10 are held by a frame 20 and a chassis 21.

Hereinafter, the configuration of the backlight unit 11 will be described in detail.

<Light guide plate>
The light guide plate 13 is made of a transparent resin such as an acrylic resin and has a rectangular flat plate shape. The light guide plate 13 has a side surface 13a on which the light of the LED package 24 is incident, and an output surface 13b that is a surface perpendicular to the side surface 13a and that emits light.

The light guide plate 13 has a multilayer structure, and has a diffusion function for diffusing outgoing light emitted from the light guide plate 13 and a lens function for adjusting the outgoing direction of the outgoing light. Accordingly, the backlight unit 11 in the present embodiment has a seatless structure. For this reason, an optical sheet becomes unnecessary, the manufacturing cost can be reduced, and the liquid crystal display device 1 can be thinned.

The light guide plate 13 is stuck and fixed to the surface of the liquid crystal display panel 10 on which the LED package 24 is mounted. That is, as shown in FIG. 1, the surface on the liquid crystal display panel 10 side at the side end of the light guide plate 13 is attached to the surface opposite to the counter substrate 32 of the TFT substrate 31 via the adhesive layer 35. ing. The adhesive material layer 35 is made of, for example, a double-sided tape, and is disposed on the side of the polarizing plate 34.

Thus, the light guide plate 13 guides the light of the LED package 24 incident from the side surface 13a and emits the light to the liquid crystal display panel 10 as uniform light from the entire emission surface 13b.

<LED package>
The LED package 24 is directly mounted on the surface of the liquid crystal display panel opposite to the observer. For example, the LED package 24 is mounted on the liquid crystal display panel 10 by an ACF (anisotropic conductive film) 36. That is, the LED package 24 is mounted on the surface of the TFT substrate 31 opposite to the counter substrate 32.

2 and 3, the LED package 24 includes a box-shaped LED main body 24a and terminal portions 24b extending on the left and right sides of the LED main body 24a. The mounting surface of the terminal portion 24b forms one plane with the mounting surface of the LED main body 24a. The LED package 24 is mounted on the TFT substrate 31 by thermocompression bonding of the terminal portion 24b to a terminal (not shown) formed on the surface of the TFT substrate 31 via the ACF 36.

A predetermined gap is provided between the LED package 24 and the light guide plate 13. An LED drive circuit 37 for driving and controlling the LED package 24 is formed on the surface of the TFT substrate 31 on which the LED package 24 is mounted. The LED drive circuit 37 is connected to the terminal portion 24 b of the LED package 24 via the terminal (not shown) of the TFT substrate 31 and the ACF 36.

<Frame and chassis>
As shown in FIG. 1, the chassis 21 is disposed on the opposite side of the light guide plate 13 from the liquid crystal display panel 10 and is formed by, for example, a rectangular metal plate. The frame 20 is formed in a rectangular frame shape made of, for example, a resin material, and supports the four sides of the liquid crystal display panel 10 and the four sides of the chassis 21. The light guide plate 13 is supported by the chassis 21. Accordingly, the liquid crystal display panel 10 and the backlight unit 11 are held by the frame 20 and the chassis 21.

With the above configuration, in the liquid crystal display device 1, the light of the LED package 24 that is driven and controlled by the LED drive circuit 37 enters the light guide plate 13 from the side surface 13 a. The light guided in the light guide plate 13 is emitted from the emission surface 13b of the light guide plate 13 to the liquid crystal display panel 10 side. At this time, the emitted light is diffused by the multilayer structure of the light guide plate 13 and the emission direction is adjusted in a direction perpendicular to the liquid crystal display panel 10.

The light emitted from the light guide plate 13 enters the liquid crystal layer through the polarizing plate 34 and the TFT substrate 31. Then, the light selectively transmitted through the liquid crystal layer is transmitted through the counter substrate 32 and the polarizing plate 33 and emitted to the viewer side, thereby performing image display.

And when manufacturing the said liquid crystal display device 1, the LED package 24 as a light source is directly mounted by ACF36 etc. on the surface on the opposite side to the observer in the liquid crystal display panel 10. FIG. Further, the light guide plate 13 is adhered and fixed to the surface of the liquid crystal display panel 10 opposite to the observer by the adhesive material layer 35. That is, the LED package 24 and the light guide plate 13 are respectively attached and fixed to the surface of the liquid crystal display panel 10 that is the assembly reference surface opposite to the viewer.

-Effect of Embodiment 1-
Therefore, according to the first embodiment, the liquid crystal display device 1 includes, for example, an LED such as an FPC because the LED package 24 of the backlight unit 11 is mounted on the surface of the liquid crystal display panel 10 on the backlight unit 11 side. It is not necessary to provide a substrate for mounting the package 24 separately from the liquid crystal display panel 10. Therefore, the LED package 24 can be assembled at the same time in the assembly process of the liquid crystal display panel 10, and the assembly of the liquid crystal display device 1 can be greatly facilitated. In addition, since the LED package 24 is fixed to the liquid crystal display panel 10, the LED package 24 is not easily displaced in the vertical direction, which is a direction perpendicular to the surface of the liquid crystal display panel 10, and the positional accuracy of the LED package 24 is greatly improved. Can also be increased.

Furthermore, since the light guide plate 13 is stuck and fixed to the surface of the liquid crystal display panel 10 on which the LED package 24 is mounted, the surface of the liquid crystal display panel 10 is used as an assembly reference plane for the light guide plate 13 and the LED package 24. Can do. As a result, the positional accuracy between the light guide plate 13 and the LED package 24 can be further increased.

Furthermore, since the light guide plate 13 has a diffusing function and a lens function, it is not necessary to provide an optical sheet. As a result, the thickness of the liquid crystal display device 1 can be easily reduced.

<< Embodiment 2 of the Invention >>
4 and 5 show Embodiment 2 of the present invention.

FIG. 4 is a cross-sectional view showing the main structure of the liquid crystal display device 1 according to the second embodiment. FIG. 5 is an enlarged cross-sectional view of a part of FIG. In the following embodiments, the same parts as those in FIGS. 1 to 3 are denoted by the same reference numerals, and detailed description thereof will be omitted.

The second embodiment is different from the first embodiment in the configuration of the backlight unit 11. In the backlight unit 11 of this embodiment, the light guide plate 13 does not have a diffusion function and a lens function, and an optical sheet 38 is provided between the liquid crystal display panel 10 and the light guide plate 13 as shown in FIG. It has been. The optical sheet 38 includes a diffusion sheet and a lens sheet.

The light guide plate 13 has a first surface 15 on the liquid crystal display panel side at a side end portion of the light guide plate 13 and a second surface 16 on which the optical sheet 38 in the light guide plate 13 is provided. The first surface 15 is arranged closer to the liquid crystal display panel 10 than the second surface 16. That is, as shown in FIG. 5, the light guide plate 13 is formed with a stepped portion 17 including the first surface 15 and the second surface 16. In the stepped portion 17, the thickness of the light guide plate 13 on the first surface 15 is larger than the thickness of the light guide plate 13 on the second surface 16.

In the liquid crystal display device 1, the light of the LED package 24 enters the light guide plate 13 from the side surface 13a. The light guided in the light guide plate 13 is emitted from the emission surface 13b of the light guide plate 13 to the liquid crystal display panel 10 side. The light emitted from the emission surface 13b is diffused by the diffusion sheet of the optical sheet 38, and the emission direction is adjusted in a direction perpendicular to the liquid crystal display panel 10 by the lens sheet of the optical sheet 38.

-Effect of Embodiment 2-
Therefore, since the LED package 24 is directly mounted on the liquid crystal display panel 10 according to the second embodiment, the LED package 24 can be assembled at the same time in the assembly process of the liquid crystal display panel 10. Assembly can be greatly facilitated. In addition, since the LED package 24 is fixed to the liquid crystal display panel 10, the positional accuracy of the LED package 24 can be dramatically increased.

In addition, even if the optical sheet 38 is provided, the first surface 15 at the side end portion of the light guide plate 13 is more liquid crystal display than the second surface 16 provided with the optical sheet 38 in the light guide plate 13. Since the light guide plate 13 is disposed on the panel 10 side, the light guide plate 13 can be easily attached and fixed to the surface of the liquid crystal display panel 10 on the first surface 15.

<< Embodiment 3 of the Invention >>
FIG. 6 shows Embodiment 3 of the present invention.

FIG. 6 is a cross-sectional view showing the main structure of the liquid crystal display device 1 according to the third embodiment.

The liquid crystal display device 1 according to the third embodiment is obtained by eliminating the gap between the LED package 24 and the light guide plate 13 in the first embodiment. That is, the LED package 24 is disposed in contact with the side surface 13 a of the light guide plate 13. On the other hand, a gap is provided between the LED package 24 and the chassis 21 as in the first and second embodiments.

The light guide plate 13 is attached to the TFT substrate 31 by mounting the LED package 24 on the liquid crystal display panel 10 and then bringing the LED package 24 into contact with the LED package 24. That is, the light guide plate 13 can be easily positioned by using the LED package 24 as a reference.

Therefore, also according to the third embodiment, the LED package 24 can be assembled at the same time in the assembly process of the liquid crystal display panel 10, and the assembly of the liquid crystal display device 1 can be greatly facilitated. In addition, since the LED package 24 is fixed to the liquid crystal display panel 10, the positional accuracy of the LED package 24 can be dramatically increased.

In addition, since the LED package 24 is disposed in contact with the side surface 13a of the light guide plate 13, the light of the LED package 24 can be efficiently incident on the light guide plate 13. As a result, the light use efficiency of the LED package 24 can be increased.

<< Other Embodiments >>
In the first embodiment, the light guide plate 13 has been described as having both a diffusion function and a lens function. However, the present invention is not limited to this, and the light guide plate 13 has at least one of a diffusion function and a lens function. It is good also as a structure.

Further, a light source other than the LED package 24 may be applied as the light source of the backlight unit 11.

Further, the present invention is not limited to the above-described first to third embodiments, and the present invention includes a configuration in which these first to third embodiments are appropriately combined.

As described above, the present invention is useful for a liquid crystal display device that performs transmissive display and a manufacturing method thereof.

1 Liquid crystal display device
10 Liquid crystal display panel
11 Backlight unit
13 Light guide plate
13a side
13b Output surface
15 First surface
16 Second surface
17 Stepped part
24 LED package (light source)
35 Adhesive layer
36 ACF
38 Optical sheet

Claims

A liquid crystal display panel;
A liquid crystal display device comprising a backlight unit, which is a lighting device arranged on the opposite side of the viewer of the liquid crystal display panel,
The backlight unit includes a light guide plate and a light source that makes light incident on a side surface of the light guide plate,
The liquid crystal display device, wherein the light source is directly mounted on a surface of the liquid crystal display panel opposite to the observer.
The liquid crystal display device according to claim 1,
The liquid crystal display device, wherein the light guide plate is fixed to a surface of a liquid crystal display panel on which the light source is mounted.
The liquid crystal display device according to claim 1 or 2,
The liquid crystal display device, wherein the light guide plate has at least one of a diffusing function for diffusing outgoing light emitted from the light guide plate and a lens function for adjusting an outgoing direction of the outgoing light.
The liquid crystal display device according to claim 2,
An optical sheet is provided between the liquid crystal display panel and the light guide plate,
The light guide plate has a first surface on the liquid crystal display panel side at a side end portion of the light guide plate, and a second surface on which the optical sheet is provided in the light guide plate,
The liquid crystal display device, wherein the first surface is disposed closer to the liquid crystal display panel than the second surface.
The liquid crystal display device according to any one of claims 1 to 4,
The liquid crystal display device, wherein the light source is disposed in contact with a side surface of the light guide plate.
The liquid crystal display device according to any one of claims 1 to 5,
The light source is constituted by an LED package and mounted on a liquid crystal display panel by an ACF.
A method of manufacturing a liquid crystal display device comprising: a liquid crystal display panel; and a backlight unit that is disposed on the opposite side of the viewer from the liquid crystal display panel and has a light guide plate and a light source that makes light incident on a side surface of the light guide plate. There,
A method of manufacturing a liquid crystal display device comprising a step of directly mounting the light source on a surface of the liquid crystal display panel opposite to the observer.
In the manufacturing method of the liquid crystal display device described in Claim 7,
A method of manufacturing a liquid crystal display device, comprising a step of attaching and fixing the light guide plate on a surface of the liquid crystal display panel opposite to the observer.
In the manufacturing method of the liquid crystal display device according to claim 7 or 8,
In the step of mounting the light source on the liquid crystal display panel, an LED package as the light source is mounted on the liquid crystal display panel by ACF.