JPS5981683A - Liquid crystal display - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a liquid crystal display device, and more particularly to a liquid crystal display device equipped with a light source.

[Technical background of the invention and its problems]

A liquid crystal display element is a so-called light-receiving type display element that does not emit light by itself but uses external light to display images. Therefore, when there is sufficient external light, the image displayed on the liquid crystal display element can be visually readable, but when there is insufficient or no external light, the displayed image becomes unreadable. Therefore, when there is no outside light, such as at night, it is necessary to read the image displayed on the liquid crystal display element by eye.

Traditionally, incandescent lamps, fluorescent lamps, etc. have been used as light sources for such liquid crystal display elements, but these light sources are usually placed at a certain distance from the back of the liquid crystal display element and emit light uniformly. Therefore, a light diffusing plate was placed in the middle.

An example of this is illustrated in Figure 1.Liquid crystal display system (1)
A lamp (2) is provided at a certain distance from the back of the lamp (2), and a light diffusing plate (3) is placed between the liquid crystal display element (1) and the lamp (2) in order to uniformize the light from the lamp (2).
) are provided.

As can be seen from the figure, in such a liquid crystal display device, the liquid crystal display element (1) and the second sensor (2) are provided at a certain distance, so the overall thickness of the liquid crystal display device is large. However, there is a problem in that the advantage of thinness, which is one of the characteristics of liquid crystal display devices, is lost and there are restrictions in terms of application.

In order to solve this problem, as shown in FIG. A lamp (2) provided on the end face of the light guide plate (4), and a white paint coated surface and a light guide plate (4) on the opposite side of the light guide plate (4) from the liquid crystal display element.
A light diffusion means (5) made of chopped hot water or the like is provided,
In addition, a light diffusing plate (
There are liquid crystal display devices that are fully equipped with 3).

However, although such a liquid crystal display device has the advantage of being able to be made thinner, the light is not sufficiently transmitted to the middle heat part because the diffused light is strong near the lamp (2), and the lamp (2) is attached to both end faces. ), there are 9 problems in that the peripheral area is bright and the central area is dark.

[Purpose of the invention]

The present invention was made in view of the above-mentioned 6f'i problem, and it is an object of the present invention to provide a highly practical liquid crystal display device that is thin but capable of displaying images with uniform brightness. The purpose is

[Summary of the invention]

That is, the present invention provides a liquid crystal display device j, :i: comprising a liquid crystal display element, a light guide plate provided on the back surface of the liquid crystal display element, and a light source provided on the end surface of the light guide plate. A light diffusing means is provided on at least one main surface of the light guide plate, and the light diffusing property of the light diffusing means becomes stronger as the distance from the light source provided at the end face of the light guide plate increases, and further, The present invention is a liquid crystal display device characterized in that a reflecting plate is provided on the opposite side of the Noah light guide plate from the liquid crystal display element to reflect almost all the light u'+i.

[Embodiments of the invention]

Next, a part of the liquid crystal display device of the present invention will be explained with reference to FIGS. 3 and 4.

That is, a light guide plate u4) made of a transparent plastic plate with a thickness of 10 polygons is provided on the back surface of the liquid crystal display element 01) via a light diffusion plate o, 9, and a lamp as a light source is installed on the end surface of this light guide plate ((,0). The uJ provided is almost the same as that in Fig. 2, but in this example, the 24-light plate ←
There is a lamp a4 on the opposite side from the liquid crystal display element αυ in a.
Light diffusing means (15
1 is provided, and furthermore, light is emitted to the back surface of this light diffusing means u9.
is characterized by a reflective plate (Ie) that provides specular reflection.

As this light diffusion means, a light guide plate u4 is used as shown in FIG.
The simplest method is 414, in which white pigment is applied thinly to the back of the lamp near the lamp, and thickly as it moves away from the lamp.

By doing this, the light is not sufficiently diffused toward the liquid crystal display element in the area near the lamp circle, and some of the light is transmitted toward the reflection plate tte, but this light is specularly reflected by the reflection plate 1e. The light is reflected by the light diffusing means and is again diffused toward the liquid crystal display element 0.

By making the above-mentioned shell structure, a thin liquid crystal display device with less light loss from the υ lamp, which can provide uniform light, and can display a bright and uniform display can be obtained.

The reason why the reflector plate 11 is provided in the embodiment is that without the reflector plate 4, the light would pass through the light guide plate and escape to the outside, causing loss of the blade base. Then, the light diffusing means (one effect of the light guide plate t1.4) fades and uniformity cannot be realized.

Also, be careful about the material of the light guide plate I.) Any material with a good cover refractive index may be used, and a clear plastic plate such as an acrylic plate may be used.The higher the refractive index, the better, and the thicker the plate.

In addition, the light diffusing means u9 provided on the back of the light guide plate u4) can be printed with white pigment K 1.4J by printing 4 shades continuously from the near a to the central part of the lamp (iJ) by halftone printing, or by sanding. You can think of something similar to 4J, such as attaching the pins closer together as you move toward the center.

〔Effect of the invention〕

As mentioned above, the liquid crystal display device of this invention [take note of the light source 7)'
A combination of a light diffuser 1λ whose light diffusivity becomes stronger as it moves away from the light guide plate, and a reflector that specularly reflects the light from the light source provided on the end face of the light guide plate is compared to J'' and I- and displayed on the liquid crystal display. Since it can be applied to the element, it is thin and has the effect of making the displayed image extremely easy to see, and its industrial value (directly) is extremely large.

[Brief explanation of drawings]

1 and 2 are explanatory diagrams showing different conventional liquid crystal display devices, and FIGS. 3 and 4 are illustrations of the liquid crystal display device of the present invention.
FIG. 3 is a diagram illustrating the overall situation, and FIG. 4 is an explanatory diagram showing the light diffusivity of the original diffusion means. 1.11...Liquid crystal display element 2,12...Lamp 3.
13...Light diffusing plate 4,14...Light guiding plate 5.15.
・Yuken Seiko Establishment 16・・Reflector Agent Patent Attorney I
Top - Male Figure 1 3 Figure 3 Figure 1? Figure 2 Figure 4 Figure f Spreadability

Claims (1)

[Claims] In a liquid crystal display device comprising a liquid crystal display element, a light guide plate provided on the back surface of the liquid crystal display element, and a light source provided on an end surface of the light guide plate, a light diffusion layer is provided on at least one main surface of the light guide plate. means is provided, and the light diffusing means is arranged such that the light diffusing property becomes stronger as the distance from the light source provided on the end surface of the light guide plate increases, and further, the light diffusing means is arranged opposite to the liquid crystal display element of the light guide plate. A liquid crystal display device characterized in that a reflecting plate that reflects light almost specularly is disposed on the side of the liquid crystal display device.