JPH02201316A - Color liquid crystal display device - Google Patents

Abstract

PURPOSE:To improve the light utilizing efficiency of a light source and the brightness of colors and to thin the thickness of the device by disposing colored filters and photoconductive plastic substrate between a liquid crystal cell and a polarizing plate with a reflecting plate and disposing the light source on the side face of the photoconductive plastic substrate. CONSTITUTION:The polarizing plate 4 is provided on the upper substrate 1 side of the liquid crystal cell 3 constituted by crimping a liquid crystal 2 between the upper substrate 1 and the lower substrate 1' and the photoconductive plastic plate 6 formed with a fluorescent light emittable colored layer 5 is provided on the lower substrate 1' side. Further, the polarizing plate plate 4' with the reflecting plate is provided on the rear surface side of the photoconductive plastic plate 6 and the light source 7 is provided in the side face part of the photoconductive plastic plate 6. The light form the light source is effectively used in this way and the color display with the high brightness is executed. In addition, the decrease of the light quantity is lessened and the thin structure is possible as the light source is provided on the side face and the photoconductive plastic plate is used.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a liquid crystal display device that displays characters, figures, etc. in color.

[Conventional technology]

Conventionally, there are devices of this type having the following configurations, for example.

■A color filter and a semi-transparent reflector are provided on the back of the liquid crystal cell, and a light source is also provided on the back of the cell, and the color can be changed by irradiating the light from the light source onto the color filter through the semi-transparent reflector. What you see through the liquid crystal.

■A semi-transparent reflector is provided on the back of the liquid crystal cell, and a light source is placed on the back of the liquid crystal cell.A colored layer containing fluorescent dye is formed between the liquid crystal cell and the semi-transparent reflector to reflect light from the light source. The colored layer is irradiated with light through a semi-transparent reflector to emit light (Japanese Unexamined Patent Publication No. 142681/1981).

■A light guide plate is provided on the back of the liquid crystal cell, and a light source lamp with a cylindrical color filter around it is provided on the side of the light guide plate, and the colored light that has passed through the color filter is irradiated to the liquid crystal cell through the light guide plate. Things to do (1987)
-30106 Publication).

[Problem to be solved by the invention]

However, the conventional liquid crystal display device described above has the following problems.

In the devices of types (2) and (2) above, the light from the light source placed on the back of the liquid crystal cell passes through a semi-transmissive reflector and then hits a color filter or a colored layer containing fluorescent dyes, so the light cannot be used effectively. It becomes less efficient. In addition, liquid crystal elements are usually equipped with two polarizing plates, which prevent light from being emitted from the light source.
Since the emitted light passes through a color filter or a colored layer and enters a polarizing plate, there is a drawback that absorption of the light by the polarizing plate further deteriorates the light utilization efficiency of the light source and reduces the brightness of the color.

On the other hand, in the device of the type (2) above, colored light is irradiated onto the liquid crystal cell through a single cylindrical color filter, but this color is a single color and has the disadvantage that it is not possible to perform a color display corresponding to the display pattern.

An object of the present invention is to improve the disadvantages of the prior art and provide a color liquid crystal display device that has good light utilization efficiency of a light source, high brightness of color, and can be made thinner. With the goal.

[Means to solve the problem]

In order to achieve the above object, the present invention includes a liquid crystal cell, a light guiding plastic plate disposed on the back side of the liquid crystal cell, and a light guiding plastic plate disposed on the surface of the light guiding plastic plate on the liquid crystal cell side. a colored filter made of a fluorescent colorant and formed in a shape corresponding to the display pattern; a polarizing plate with a reflector provided on the back side of the light-guiding plastic plate; Provided is a color liquid crystal display device characterized by comprising a light source disposed on the side.

[Effect]

With the configuration in which colored filters are disposed between the liquid crystal cell and the polarizing plate with a reflector, the colored light emitted from the colored filters passes through only one polarizing plate, which reduces the decrease in the amount of light and increases the brightness of the colored colors. Further, by using a light-guiding plastic substrate and arranging a light source on the side surface of the light-guiding plastic substrate, the device can be made thinner.

〔Example〕

The present invention will be explained in detail below with reference to Examples.

FIG. 1 is a partial sectional view showing the configuration of a color liquid crystal display device of this embodiment. This device includes a liquid crystal cell 3 having a liquid crystal 2 sandwiched between an upper substrate 1 and a lower substrate 1', a polarizing plate 4 provided on the upper substrate 1 side, and a fluorescent colored layer on the lower substrate 1' side. 5, a polarizing plate 4' with a reflective plate is provided on the back side of the light-guiding plastic plate 6, and a light source 7 is provided on the side surface of the light-guiding plastic plate 6. It is configured.

In the liquid crystal cell 3, the lower substrate 1' is preferably as thin as possible, and is made of a flexible polymer film with a thickness of 0.5 m+a or less,
Thin film glass or the like is preferably used. If the lower substrate 1' is thick, parallax will occur when viewing from above the liquid crystal cell, resulting in misalignment of colors and display patterns, resulting in a narrow display viewing angle. As for the upper substrate l, the same one as the lower substrate 1' may be used, or a glass plate or the like which is somewhat thicker than the lower substrate 1' may be used.

As the polarizing plate 4' with a reflecting plate, for example, a polarizing plate with a metal thin film such as AQ deposited on the back surface is used.

The fluorescent coloring layer 5 is formed on the liquid crystal cell side surface of the light-guiding plastic plate 6 using a fluorescent colorant in accordance with the display pattern. A fluorescent dye can be used as the fluorescent colorant, and it is preferable that the fluorescent dye has as good a light transmittance as possible when forming the colored M5.

The larger the refractive index n of the light-guiding plastic plate 6, the better.
It is preferable that it is >1.45. The material is
For example, acrylic resin, polycarbonate, etc. are used. Further, a thickness of about 1 to 21 mm is preferable because light can be used effectively. In the illustrated example, light source 7
In order to improve the convergence of light, the end face of the light-guiding plastic plate 6 is concave.

The light source 7 is provided on the side surface of the light-guiding plastic plate 6, and this configuration allows the device to be made thinner.

In the device configured as described above, the light from the light source 7 illuminates the side surface of the light-guiding plastic plate 6, and a portion of the light is transmitted through the light-guiding plastic plate 6 while being totally reflected, and a portion of the light is transmitted through the light-guiding plastic plate 6 while being totally reflected. The fluorescent colored layer 5 is irradiated with colored light to form colored light. Further, the light transmitted to the back side of the light-guiding plastic plate 6 is reflected by the polarizing plate 4' with a reflective plate, passes through the light-guiding plastic plate 6 again, reaches the fluorescent coloring layer 5, and then first fluoresces. The light passes through the luminescent colored layer 5 and reaches the liquid crystal cell 3 together. Color display is then performed by turning the liquid crystal cell 3 on and off in accordance with the color information.

In conventional devices, the polarizing plate on the back side is placed between the liquid crystal cell and the colored layer, so the emitted light from the colored layer passes through the polarizing plate twice, and the amount of light is reduced accordingly. Get dark. However, in the device of this embodiment, the color emitted from the color colored layer (fluorescent colored layer 5) passes only through the polarizing plate 4 disposed in front of the liquid crystal cell 3, so the decrease in light amount is different from that in the conventional device. The brightness of the color becomes higher.

Although the present invention has been described above based on one embodiment, the present invention is not limited to the above embodiment, and various modifications and polarizations are possible.

For example, in order to effectively transmit the light from the light source 7 to the reflective side of the light guiding plastic plate 6, the refractive index of the light guiding plastic plate 6 may be distributed such that it gradually decreases from the light source side. .

Furthermore, in order to effectively focus the light from the light source 7 on the light-guiding plastic plate 6, a configuration as shown in FIG. 2 or 3 may be used. In FIG.
3, a lens 9 is provided between the light source 7 and the end surface of the light-guiding plastic plate 6. In FIG. In the example shown here, the light source 7 is arranged on one side of the translucent plastic plate 6, but the light source may be arranged on the other side in a similar manner. .

〔Effect of the invention〕

As described above in detail, according to the present invention, with the above configuration, the light from the light source can be used effectively, and color display with even higher brightness is possible. Also,
Since the light source is disposed on the side surface and a light-guiding plastic plate is used, it is possible to provide a thin color liquid crystal display device with less reduction in the amount of light.

[Brief explanation of the drawing]

FIG. 1 is a partial cross-sectional view showing the configuration of a color liquid crystal display device according to an embodiment of the present invention, and FIGS. FIG. 3 is a diagram showing the configuration. 1...Top substrate 1'--Lower substrate 2...Liquid crystal 3...Liquid crystal cell 4...Polarizing plate
4'... Polarizing plate with reflector 5... Fluorescent colored layer 6... Light-guiding plastic plate 7... Light source
8...Reflector 9...Lens Figure 2 Patent Applicant Rico Co., Ltd.

Claims (1)

[Claims] (1) A liquid crystal cell, a light-guiding plastic plate disposed on the back side of the liquid crystal cell, and a light-guiding plastic plate provided on the surface of the light-guiding plastic plate facing the liquid crystal cell in a shape corresponding to the display pattern. A colored filter made of a formed fluorescent colorant, a polarizing plate with a reflective plate provided on the back side of the light-guiding plastic plate, and a light source disposed on the side surface of the light-guiding plastic plate. A color liquid crystal display device characterized by: