JPH0862427A - Liquid crystal display - Google Patents

Abstract

PURPOSE: To provide uniform distribution of brightness on a display surface by forming a coating film having a large diffractive index on a main surface of a light guide plate and increasing the area of the coating film per unit area in a corner section. CONSTITUTION: In a liquid crystal display which is provided with a liquid crystal display substrate 7, a light guide plate 1 arranged on a back face of the liquid crystal display substrate 7, and a light emitter 2 arranged on a side at one end of the light guide plate 1 and in which light from the light emitter 2 is radiated onto the liquid crystal display substrate 7 through the main surface from the side at one end of the light guide plate 1, coating films having larger diffractive index than that of the light guide plate 1 are formed like dots on the main surface of the light guide plate 1. As for the coating films like dots, the area of the film per unit area is larger in a corner section at one side opposing to the other side of the light guide plate 1 on the side where the light emitter 2 is arranged.

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 device,
In particular, it relates to a so-called backlight type liquid crystal display device.

[0002]

2. Description of the Related Art A liquid crystal display device, which is a so-called backlight system, is provided with a light emitting body made of hot and cold cathode rays, which is called a CFL, and the light emitting body is arranged on the back surface of a liquid crystal display substrate. It is positioned at one end side of the light guide plate.

This light guide plate is adapted to take in light from the light emitting body from its end side surface and to emit it from the main surface facing the liquid crystal display substrate.

Then, in order to make the emission of the light guided into the light guide plate from the main surface sufficient, a coating film having a larger light refractive index than the light guide plate is formed in a dot shape on the main surface of the light guide plate. They are arranged and formed.

By doing so, the light guided into the light guide plate is refracted to the main surface side.

As a result, a so-called backlight having a uniform light intensity distribution is provided on the back side of the liquid crystal display substrate.

Note that such a technique is described in, for example, “Akio Ohara,“ Backlight for Liquid Crystal Display ”, Journal of the Lighting Society, No. 73.
Volume 12, No. 12, 1989).

[0008]

However, in the liquid crystal display device having such a structure, a corner away from the position where the light emitting body is positioned on the display surface has been accompanied by the tendency of the display surface to become larger in recent years. It has been pointed out that the brightness is not sufficient in some parts, resulting in uneven brightness of the light.

Therefore, the present invention has been made under such circumstances, and the object of the present invention is to provide a uniform distribution of brightness on the display surface of a liquid crystal display substrate. Another object of the present invention is to provide the liquid crystal display device.

[0010]

In order to achieve such an object, the present invention basically provides a liquid crystal display substrate, a light guide plate disposed on the back side of the liquid crystal display substrate, and a light guide plate. A light-emitting body disposed on one side surface of the light plate, wherein light from the light-emitting body is radiated from the one side surface of the light-guide plate through the main surface toward the liquid crystal display substrate side. A dot-shaped coating having a larger optical refractive index than the photoconductive plate is formed on the main surface of, and the dot-shaped coating faces one side of the light guide plate on the side where the light emitter is arranged. The coating area per unit area is large in the corner portion on the other side.

[0011]

In the liquid crystal display device having such a structure, the dot-shaped coating formed on the main surface of the light guide plate, that is, the surface for irradiating the liquid crystal display substrate side with light, is provided in the corner portion far from the light emitter. In particular, the coating area per unit area is large.

By increasing the coating area in this way, the light guided into the light guide plate is refracted more by that amount and emitted to the main surface side.

Therefore, it is possible to eliminate the disadvantage that the amount of light irradiation to the liquid crystal display substrate side in the conventional corner portion is small, and to make the amount of light irradiation to the liquid crystal display substrate on the main surface of the light guide plate uniform. become able to.

[0014]

FIG. 2 is an exploded perspective view of a liquid crystal display module which is an embodiment of the liquid crystal display device according to the present invention.

In FIG. 1, first, there is a light guide plate 1 made of, for example, an acrylic plate. A light emitting body made of CFL 2 is arranged on one end side surface of the light guide plate 1.

The CFL 2 is attached to the light guide plate 1 at both ends thereof via rubber bushes 3.

There is a light-shielding sheet 4 covering the CFL 2 so that the light of the CFL 2 is entirely irradiated into the light-guide plate 1. Both ends of the light-shielding sheet 4 are attached to the front and back surfaces of the light-guide plate 1, respectively. There is.

Above the CFL2 is the CFL2.
The CFL protective cover 5 arranged so as to cover the light guide plate 1 is attached to the light guide plate 1 by using, for example, a screw.

A liquid crystal display substrate 7 is arranged on the surface of the light guide plate 1 with a diffusion sheet 6 interposed therebetween. Thereby, the light from the CFL 2 is irradiated into the light guide plate 1 from the end side surface of the light guide plate 1, diffused and emitted by the diffusion sheet 6 arranged on the main surface thereof, and transmitted through the liquid crystal display substrate 7. It is like this.

Although not shown in detail in FIG. 2, the liquid crystal display substrate 7 is composed of two glass substrates with a liquid crystal interposed, and an electrode (not shown) is provided on a part of the periphery thereof.

On the other hand, a printed wiring board 8 is arranged on the back surface side of the light guide plate 1, and the wiring on the surface of the printed wiring board 8 is connected to the electrodes on the liquid crystal display board 7 via a connector 9. It has become so.

Further, the printed wiring board 8 also serves as a base for mounting the frame 10. This frame 10 is a metal plate having an opening provided in a portion corresponding to the display area of the liquid crystal display substrate 7, and by caulking a claw portion 10A formed on a side surface thereof on the printed wiring board 8, The liquid crystal display substrate 7, the light guide plate 1 and the printed wiring board 8 are integrated.

The liquid crystal module thus integrated has a cross section as shown in FIG. 3, which is a cross sectional view taken along line III-III in FIG.

Here, the light guide plate 1 is provided on the surface of the light guide plate 1 on the liquid crystal display substrate 7 side, that is, on the main surface in contact with the diffusion plate 6.
A film having a larger optical refractive index than that is formed in a dot shape. As a material of this coating, for example, titanium oxide, styrene, glass, or the like, that is, a material having a large equal refractive index and a light diffusion effect is used.

In this embodiment, in particular, the area per unit area of the film formed in a dot shape is different depending on the area of the main surface of the light guide plate 1.

FIG. 1 is an explanatory view schematically showing that the area of the coating film per unit area is different depending on each area.

In FIG. 1, there is a light guide plate 1 and a light emitting body 1
Are arranged at the positions shown in the figure.

First, the above-mentioned region has a parabolic line a which has an axis that bisects the side on which the light-emitting body 1 is arranged and which has an apex on the side facing the side and has a slightly narrower spread. , From the side where the light emitter 1 is arranged to the side opposite to the side,
The parabolic line b, the straight line c, the parabolic line d, and the parabolic line e are framed. Here, the parabolic line b has an axis that bisects the side on which the light-emitting body 1 is arranged, and has a large spread with its apex on the side, whereas the parabolic line d and In each case, e has an axis that bisects the side on which the light-emitting body 1 is arranged, and has a large spread with the apex on the side facing the side.

As a result, in the parabolic line a, regions (1), (2) and (3) defined by the lines b, c and d are arranged from the side where the light emitting body 1 is arranged. Outside the parabolic line a, which is sequentially formed, a region (5) defined by the lines b, c, d, and e from the side on which the light emitting body 1 is arranged,
(6), (7), and (8) are sequentially formed.

The respective areas (1) to (8) are
When the coating is uniformly formed on the main surface of the light guide plate 1, it is determined from the result of simulating how much light is emitted to the main surface of the light guide plate 1 in which the arrangement of the light emitters 2 is specified. The simulation diagram is as shown in FIG. This figure shows the light irradiation amount in contour lines, and shows that the central part has a relatively large light amount.

The film is formed in each of the areas (1) to (8) in the pattern shown in FIG.

That is, in the area (1) in the figure, the coating area per unit area of the dot-shaped coating is the smallest, in the area (8) it is the largest, and in the other areas, It is formed by the coating area between them.

According to such an embodiment, the light guide plate 1 is
The dot-shaped coating formed on the main surface of, i.e., the surface that irradiates light on the liquid crystal display substrate side, has a particularly large coating area per unit area at the corner portion far from the light emitting body 2.

By increasing the coating area in this way, the light guided into the light guide plate is refracted more by that amount and emitted to the main surface side.

Therefore, it is possible to eliminate the disadvantage that the light irradiation amount to the liquid crystal display substrate 7 side in the conventional corner portion is small, and to make the light irradiation amount to the liquid crystal display substrate 7 uniform on the main surface of the light guide plate 1. You will be able to plan.

[0036]

As is apparent from the above description,
The liquid crystal display device according to the present invention can be configured so as to provide a uniform distribution of brightness on its display surface.

[Brief description of drawings]

FIG. 1 is a main part configuration diagram showing an example of a liquid crystal display device according to the present invention, and is a diagram showing an example of a distribution state of a coating film on a light guide plate.

FIG. 2 is an exploded perspective view of a liquid crystal display module which is an embodiment of the liquid crystal display device according to the present invention.

FIG. 3 is a sectional view taken along line III-III in FIG.

FIG. 4 is a simulation diagram on which the present invention is based.

[Explanation of symbols]

 1 ... Light guide plate, 2 ... Light emitter, 7 ... Liquid crystal display substrate.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Toshio Hirayama, 3673 Hayano, Mobara, Chiba Prefecture, Hitachi Nisshin Electronics Co., Ltd. (72) Inventor Shin Fujita, 3681, Hayano, Mobara, Chiba Hitachi Device Engineering Co., Ltd. (72 ) Inventor Makoto Ibashi 3300 Hayano, Mobara-shi, Chiba Hitachi, Ltd. Electronic Devices Division (72) Inventor Hirotsugu Muramatsu 3673 Hayano, Mobara-shi, Chiba Hitachi Nisshin Electronics Co., Ltd.

Claims (1)

[Claims] 1. A liquid crystal display substrate, a light guide plate arranged on the back side of the liquid crystal display substrate, and a light emitter arranged on one end side surface of the light guide plate, wherein the light from the light emitter is In a liquid crystal display device in which the liquid crystal display substrate side is irradiated from the one end side surface of the light guide plate through the main surface, a film having a large optical refractive index is formed in dots on the main surface of the light guide plate. In addition, the dot-shaped coating is characterized in that the coating area per unit area is large at the corner portion on the other side facing the one side of the light guide plate on the side where the light emitter is arranged. Liquid crystal display device.