JPH06301032A - Light emitting device and liquid crystal display device formed by using this light source device - Google Patents

Abstract

PURPOSE:To provide a light emitting device for colors which is easily produced, is high in response speed for switching and can emit light rays of arbitrary colors and to provide a color liquid crystal display device of a simple type capable of arbitrarily changing the colors of a display screen. CONSTITUTION:This liquid crystal display device consists of a liquid crystal display panel 3 and a back light disposed behind this liquid crystal display panel 3. The light emitting device consisting of the plural color light emitting sources 21a, 21b, 21c and liquid crystal shutters 1a, 1b, 1c disposed near these color light emitting sources 21a, 21b, 21c is used as the back light for this liquid crystal display device.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light emitting device and a liquid crystal display device using the light emitting device. More specifically, in a light emitting device used for a traffic signal, a color backlight of a liquid crystal display device, etc., the means for controlling the light source for switching for blinking and adjusting the brightness is improved to prolong the life of the light emitting source. The present invention relates to a light emitting device that can emit light of any color while being designed.

[0002]

2. Description of the Related Art Conventionally, a vacuum tube such as a tungsten lamp, a fluorescent lamp or a cold cathode tube (hereinafter referred to as CFL) has been used in a light emitting device such as a backlight of a liquid crystal display device. These light-emitting sources are subject to intense blinking and control of the amount of light, but are advantageously used in terms of amount of light and cost. In order to produce colored colors with these light emitting devices, it is possible to cover them with a color filter around the vacuum tube.
It is necessary to provide vacuum tubes of three colors of blue and to emit light of a desired color by blinking the vacuum tubes of each color. However, since the response speed of blinking the vacuum tube is slow, it has not been put to practical use as a color backlight for a liquid crystal display device using a vacuum tube such as a fluorescent lamp.

When a conventional liquid crystal display device is used for color display, color filters of three primary colors of red, green and blue are provided in each pixel, and a different color is displayed for each pixel depending on the combination of the colors. There are a display system and a simple color display system in which a certain part of the display screen is displayed in a constant color. Since the full-color method is difficult to manufacture and very expensive, a simple color display method is often used.
The conventional method of performing a simple color display in which the entire screen is displayed in the same or a partially different color on a liquid crystal display device is a liquid crystal layer side or outside of the transparent substrate of the liquid crystal display panel or the surface of the polarizing plate. Color display is performed by attaching a film-like color filter or directly applying a color paint.

[0004]

However, in the conventional simple type liquid crystal display device for color display, a color filter must be attached to the liquid crystal layer of the transparent substrate or the outside or the surface of the polarizing plate. The number of steps for providing the filter is required, which causes a cost increase. Moreover, since the display screen can display only the colors of the color filters provided in advance, there is a problem that the color of the image on the display surface cannot be changed.

On the other hand, as a color light source, for example, a large number of LEDs having various emission colors are provided, and by controlling blinking of each color LED, a color light source of various colors can be obtained. A light source with a small amount of light emission, such as a fluorescent lamp or a tungsten lamp, which is inexpensive and has a large amount of light cannot be obtained.

The present invention solves such a problem, provides a color light emitting device which can be easily manufactured, has a fast response speed, and has a large amount of light, and also can easily change the color of the display screen. An object of the present invention is to provide a color liquid crystal display device.

[0007]

According to the present invention, a liquid crystal shutter is provided in front of each of a plurality of color light emitting sources, and the liquid crystal shutter is switched, so that a light source with a large amount of light such as a fluorescent lamp is used for various colors. The present invention realizes a color light emitting device having a fast response speed. The use of a liquid crystal shutter as a color light emitting device is novel.

The light emitting device of the present invention comprises a plurality of color light emitting sources and a liquid crystal shutter arranged near the color light emitting sources.

The liquid crystal display device of the present invention comprises a liquid crystal display panel and a backlight disposed behind the liquid crystal display panel, and the backlight is constituted by the light emitting device. .

[0010]

According to the light emitting device of the present invention, since the liquid crystal shutter is arranged in the vicinity of the plurality of color light emitting sources, only the light of any color among the lights of different emission colors emitted from the respective color light sources is emitted. The amount of light of the other color that is transmitted is adjusted or blocked by controlling the voltage applied to the electrodes on both ends of the liquid crystal shutter. Therefore, set the color emission source to O
By turning on and off the liquid crystal shutter while N is kept as it is, the response speed is fast, and the light amount and the emission color can be adjusted.

According to the liquid crystal display device of the present invention, the liquid crystal shutters provided in the vicinity of the plurality of color light emission sources are arranged on the back side of the liquid crystal display panel, and the light emission sources arranged on the back side by the liquid crystal shutters are arranged. Since the light can be turned on and off,
There is no need to directly turn the light source on and off. Moreover, even if a fluorescent lamp or the like is used as the light source, the entire screen can be made to have an arbitrary color by blinking each color while the light source remains ON. Further, by mixing the colors of a plurality of light emitting sources or changing the transmittance of each pixel of the liquid crystal shutter to change the intensity of the light of each color, it is possible to display an arbitrary mixed color.

[0012]

The present invention will be described in detail with reference to the drawings. 1 is an enlarged cross-sectional explanatory view of an essential part showing an embodiment of a light emitting device of the present invention, and FIG. 2 is an exploded partial cutaway perspective view of a liquid crystal display device using the light emitting device of FIG. 1 as a backlight.

As shown in FIG. 1, the liquid crystal shutter 1 serves as a color light source 21 as a constituent unit for emitting each color of the light emitting device.
Is arranged on the front surface of. LCD shutter 1
Are arranged so that transparent substrates 13a and 13b on which transparent electrodes 11a and 11b and alignment layers 12a and 12b for forming a molecular alignment of liquid crystals are formed are opposed to each other.
A liquid crystal material is filled in the gap 13b to form a liquid crystal layer 14. The transparent electrodes 11a and 11b may be continuous electrodes on both sides. Further, polarizing plates 15a and 15b are provided outside the transparent substrates 13a and 13b, respectively. In addition,
16 is a sealant for preventing liquid crystal leakage.

As the color light source 21, for example, a fluorescent lamp, a tungsten lamp, a CFL tube or the like is used, and in the case of a white light source, a colored filter or the like is coated on the surface thereof to form a color light source. As a result, turn on fluorescent lights,
Turns off (in severe cases, turns on about 3 times per second, O
FF) shortens the life of the fluorescent lamp, but by turning it on and off using the liquid crystal shutter, it is sufficient to turn on the fluorescent lamp with a constant amount of light, and the life can be extended. . Further, it is preferable to provide a reflection plate 22 behind the color light emission source 21 in order to efficiently guide light forward, but it is not always necessary. The reflection plate 22 is formed by depositing a metal film of aluminum or the like on the surface of a plate made of polyester or the like by vapor deposition, or by using a metal plate or the like.

In the light emitting device having the above-described structure, the color of the light emitted from the color light emitting source 21 can be changed at a high response speed by turning on and off the applied voltage of the liquid crystal shutter 1 and adjusting the amount of transmission. It can be adjusted.

A liquid crystal display device using the light emitting device of the above embodiment as a backlight is constructed as shown in FIG.
That is, on the opposite side of the display surface of the normally used liquid crystal display panel 3 for image display, a backlight case 4 whose inside is divided into, for example, three space portions 4a, 4b and 4c by a partition plate is arranged. Inside the portions 4a, 4b and 4c, color light emitting sources of different light emitting colors, for example, three color light emitting sources 21a, 21b and 21c of red, green and blue are provided. Liquid crystal shutters 1a, 1b and 1c are provided on the front surfaces of the spaces 4a, 4b and 4c on the liquid crystal display panel 3 side. Further, the color light sources 21a, 21b and 21c
Reflecting plates 22a, 22b, and 22c are provided on the rear side of each.

According to the liquid crystal display device of the present embodiment, the color light emitting sources 21a, 21b and 21c emit red, green and blue light, respectively, and the respective color light emitting sources are emitted.
Liquid crystal shutters 1a, 1b, and 1c provided on the front surfaces of 21a, 21b, and 21c selectively guide the light of any one of the color light emission sources to the liquid crystal display panel 3 side to control the brightness of each light. By adjusting, it can be displayed in any color. Moreover, during use, the color is adjusted by blocking the light with the liquid crystal shutter while the color light sources 21a, 21b, and 21c are turned on. Therefore, even if a fluorescent lamp is used as a backlight, any desired color can be maintained while maintaining fast response characteristics. The display can be done. The above-mentioned liquid crystal display panel is used for a normal liquid crystal display device, in which a liquid crystal layer is sandwiched by a transparent substrate provided with electrodes and an alignment film, and polarizing plates are provided on both sides.

[0018]

According to the present invention, since the color can be easily changed only by changing the light-shielding pattern of the liquid crystal shutter, a simple color display can be performed with any color.

Further, even if a fluorescent lamp or the like having a large response delay at the time of lighting is used as a color light emitting source, good response characteristics can be obtained, so that a high quality image can be obtained even on a large display screen.

[Brief description of drawings]

FIG. 1 is an enlarged cross-sectional explanatory view of an essential part showing an embodiment of a light emitting device of the present invention.

FIG. 2 is an exploded partial cutaway perspective view of a liquid crystal display device using the light emitting device of FIG. 1 as a backlight.

[Explanation of symbols]

 1a, 1b, 1c Liquid crystal shutters 21a, 21b, 21c Color light source 3 Liquid crystal display panel

Claims (2)

[Claims] 1. A color light emitting device comprising a plurality of color light emitting sources and a liquid crystal shutter arranged in the vicinity of the color light emitting sources. 2. A liquid crystal display device comprising a liquid crystal display panel and a backlight disposed behind the liquid crystal display panel, wherein the backlight is the light emitting device according to claim 1.