JP2000089222A - Liquid crystal display - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To reduce the overall thickness of a liquid crystal display device without lowering the display luminance of the device. SOLUTION: A cold cathode fluorescent tube 5 is provided as a back light source of a liquid crystal panel 7, and this light beam is reflected by a reflection plate 6 and made incident from an end face of a light guide 1B. Further, the reflection sheet 2 is attached to the back surface of the light guide 1B, and the diffusion sheet 3 and the prism sheet 4 are attached to the emission light side. Since the light emitting surface of the light guide 1B is concave, even if the light guide 1B is curved, it does not hit the rear surface of the liquid crystal panel 7. Further, since the area of the end face of the light guide 1B is large, the light rays of the cold cathode fluorescent tube 5 can be sufficiently captured.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display mainly for improving a backlight.

[0002]

2. Description of the Related Art A liquid crystal display device is provided with a backlight unless it is a reflection type. As an example, there is a liquid crystal display device having a side light type back light source as shown in FIG. As shown in the cross-sectional view of FIG. 3, the liquid crystal display device includes a light guide 1A, a diffusion sheet 3, a prism sheet 4, a cold cathode fluorescent tube 5, which is a rod-shaped light source, a liquid crystal panel 7, and a fixing member for fixing these. It is configured to include a first frame 8 and a second frame 9 which are fixing members.

In order to provide a backlight to the liquid crystal panel 7, the cold-cathode fluorescent tube 5 is turned on, and a light beam therefrom is guided to the back of the liquid crystal panel 7 by using the light guide 1A to form a flat light source. . The illumination light obtained here is passed through the diffusion sheet 3 and the prism sheet 4 to be converted into back light (backlight) having desired emission light characteristics. This back light is incident on the liquid crystal panel 7 to display an image by transmitted light.

[0004]

In the liquid crystal display device configured as described above, the surface of the back light source and the liquid crystal panel 7 are held with a certain gap as shown in FIG. The reason for providing such a gap is as follows. That is, when the light guide plate 1A is warped due to storage or use environment (temperature) of the liquid crystal display device, the back light source hits the back surface of the liquid crystal panel 7, and the liquid crystal panel 7 is distorted. In such a state, the liquid crystal panel 7 cannot perform normal display.

Recently, the size of a display screen has been remarkably increased, and the demand for a thinner liquid crystal display device has been increasing. In order to fulfill these requirements, it is necessary to reduce the thickness of each member. However, in a liquid crystal panel, when the size of the glass substrate is increased, it is difficult in terms of strength to reduce the thickness of the glass substrate itself. Further, it is difficult to further reduce the thickness of the frames from the viewpoint of the strength of the housing of the liquid crystal display device. Therefore, it is considered that the method of making the light guide thinner is the easiest method. However, reducing the thickness of the light guide is
There is a problem that the incidence efficiency of the light beam from the rod-shaped light source is reduced and the brightness of the rear light source is reduced.

The present invention has been made in view of such conventional problems, and has as its object to realize a liquid crystal display device capable of reducing the thickness of a rear light source without lowering the luminance of the rear light source. .

[0007]

Means for Solving the Problems To solve this problem, the invention of claim 1 of the present application is directed to a transmission type liquid crystal panel,
A liquid crystal display device having a back light source that provides irradiation light from the back of the liquid crystal panel, wherein the back light source is formed in a rectangular plate shape using a rod-shaped light source having a rod-shaped light emitting source and a transparent resin, The back surface of the plate is formed in a flat shape, the surface of the plate is formed in a concave shape, one end surface of the plate is formed thicker than the thickness of the other end surface on the opposite side, and the concave surface of the plate is formed of the liquid crystal panel. A light guide attached so as to face the back surface, and attached such that one end surface of the plate faces the rod-shaped light source.

According to a second aspect of the present invention, there is provided a liquid crystal display comprising a transmissive liquid crystal panel, a back light source for providing irradiation light from the back of the liquid crystal panel, and a fixing member for fixing the liquid crystal panel and the back light source. In the device, the back light source is a rod-shaped light source having a rod-shaped light emitting source, formed in a rectangular plate using a transparent resin, the back surface of the plate is formed in a flat shape, the surface of the plate is formed in a concave shape, One end surface of the plate is formed to be thicker than the other end surface on the opposite side, the concave surface of the plate is mounted so as to face the back surface of the liquid crystal panel, and one end surface of the plate is the rod-shaped light source. And a light guide attached by the fixing member so as to face the light guide.

The invention of claim 3 of the present application is directed to claim 1 or 2
In the liquid crystal display device, a reflection sheet attached to the back surface of the light guide and reflecting the scattered light of the light guide, and light emitted from the front surface of the light guide attached to the back surface of the liquid crystal panel. And a diffusion sheet for scattering.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A liquid crystal display according to an embodiment of the present invention will be described with reference to FIGS. FIG.
FIG. 2 is a structural sectional view centering on a back light source of the liquid crystal display device of the present embodiment. As shown in FIG.
The MMA resin is molded into a substantially rectangular plate shape, the light emitting surface is formed in a gentle concave shape, and the back surface is formed in a flat shape. The cold cathode fluorescent tube 5 is arranged on one side of the long side of the light guide 1B. Then, in order to improve the efficiency of incidence on the light guide 1B, a reflector 6 is attached so as to surround the cold cathode fluorescent tube 5. A reflection sheet 2 made of a white resin sheet is provided on the back surface of the light guide 1B. Then, a diffusion sheet 3 is provided on the outgoing light side of the light guide 1B in order to diffuse light rays and reduce luminance unevenness. Furthermore, a prism sheet 4 is provided thereon to condense light rays and improve the front luminance. Then, the liquid crystal panel 7 is disposed so as to be in contact with the prism sheet 4. Finally, frames 8 and 9 are provided at the edges of the liquid crystal panel 7 and the light guide 1B as fixing members for holding each member.

FIG. 2 is a partial sectional view showing a sectional shape of the light guide 1B. (A) shows the cross-sectional shape of the light guide 1B in a portion adjacent to the cold cathode fluorescent tube 5, (b) shows
4 is a cross-sectional shape of the light guide 1B at a portion farthest from the light guide 1B. In each of the portions, a flat portion 1a is formed at an end on the emission light side in parallel with the back surface of the liquid crystal panel 7. The other light emitting surface is formed with a gentle concave surface 1b. The flat portions 1a at both ends are in contact with the back surface of the liquid crystal panel 7 via the diffusion sheet 3 and the prism sheet 4. FIG. 2
As shown in (a), the area of the end face for capturing the light beam from the cold cathode fluorescent tube 5 is formed larger than other portions, so that the light collection efficiency does not decrease.

With the back light source having such a structure, the gap between the liquid crystal panel 7 and the light guide plate 1B can be substantially eliminated, and the thickness of the liquid crystal display device can be made smaller than the conventional example. Further, the light exit surface of the light guide 1B is concave, and even if the light guide 1B is warped, the light guide 1B does not hit the back surface of the liquid crystal panel 7. Further, light guide 1B
Since the light incident surface has a sufficient thickness, no decrease in luminance occurs.

[0013]

According to the present invention, it is possible to realize a liquid crystal display device in which the overall thickness is reduced and the influence of warpage of the light guide is eliminated without lowering the display brightness of the liquid crystal panel.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating a structure of a liquid crystal display device according to an embodiment of the present invention.

FIG. 2 is a sectional view of a light guide used in the liquid crystal display device of the present embodiment.

FIG. 3 is a sectional view of a conventional liquid crystal display device.

[Explanation of symbols]

 1B Light guide 2 Reflection sheet 3 Diffusion sheet 4 Prism sheet 5 Cold cathode fluorescent tube 6 Reflector 7 Liquid crystal panel 8, 9 Frame

Claims (3)

[Claims] 1. A liquid crystal display device comprising: a transmissive liquid crystal panel; and a back light source for irradiating light from the back of the liquid crystal panel, wherein the back light source comprises: a rod-shaped light source having a rod-shaped light emitting source; It is formed in a rectangular plate shape using resin, the back surface of the plate is formed in a flat shape, the surface of the plate is formed in a concave shape, and one end surface of the plate is formed thicker than the thickness of the other end surface on the opposite side, A light guide attached so that the concave surface of the plate faces the back surface of the liquid crystal panel, and one end surface of the plate is attached to face the rod-shaped light source. Characteristic liquid crystal display device. 2. A liquid crystal display device comprising: a transmissive liquid crystal panel; a back light source for irradiating light from the back of the liquid crystal panel; and a fixing member for fixing the liquid crystal panel and the back light source. The light source is a rod-shaped light source having a rod-shaped light-emitting source, and is formed in a rectangular plate shape using a transparent resin, the back surface of the plate is formed in a flat shape, the surface of the plate is formed in a concave shape, and one end surface of the plate is It is formed so as to be thicker than the thickness of the other end surface on the opposite side, is mounted so that the concave surface of the plate faces the back surface of the liquid crystal panel, and the fixed so that one end surface of the plate faces the rod-shaped light source. A liquid crystal display device comprising: a light guide attached by a member. 3. A reflection sheet attached to a back surface of the light guide and reflecting scattered light of the light guide; and a reflection sheet attached to a back surface of the liquid crystal panel and scattering light emitted from the surface of the light guide. The liquid crystal display device according to claim 1, further comprising: a diffusion sheet for causing the liquid crystal device to emit light.