JPH0318888A - Projection type liquid crystal display device - Google Patents

Abstract

PURPOSE:To obtain a display device which has a bright and large screen and also is reduced in weight and whose portability at the time of movement is satisfactory by using three pieces of panels used exclusively for red, green and blue for a liquid crystal display panel, synthesizing light beams of three colors and executing a color display. CONSTITUTION:By an illuminating light emitted from a light source 1, the whole surface of liquid crystal display panels 11 - 13 is illuminated, and the illuminating light transmits through the liquid crystal display panels 11 - 13 and is reflected by a back reflecting mirror 4, passes through the liquid crystal display panels 11 - 13 once again and becomes a projection light, is condensed to a projection lens 5, reflected by a reflecting mirror 6 for projection and projected to a screen 9. Subsequently, three pieces of liquid crystal display panels 11 - 13 used exclusively for red, green and blue are used, and after transmitting through the liquid crystal display panels 11 - 13, light beams of three colors are synthesized and a color display is executed. Since three pieces of liquid crystal display panels 11 - 13 are illuminated by dispersing the light beam of the light source 1, the temperature of the liquid crystal display panels 11 - 13 and polarizing plates 3, 7 is not allowed to rise and an image can be projected brightly. In such a manner, the projection type liquid crystal display device which has a bright and large screen, and also, is reduced in weight and whose portability at the time of movement is satisfactory is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a reflective projection type liquid crystal display device that uses a Fresnel type reflector or the like to display images and characters.

[Prior Art] A conventional device for displaying images and characters is a CRT. Recently, there are liquid crystal display panels, EL panels, and even projection-type liquid crystal display devices that allow light to pass through the liquid crystal display panel only once in one direction.

For example, there is published patent publication (A) 1986-9396.

These devices have drawbacks such as large-scale construction and difficulty in handling, and are only put into practical use for extremely limited purposes. In other words, a basic example of the prior art as shown in FIG. 3 is a projection type liquid crystal display device in which light is transmitted through the liquid crystal display panel only once in one direction. The basic configuration of a transmission type projection type liquid crystal display device will be explained below with reference to FIG.

A condensing lens 51, a liquid crystal display panel 52, and a projection lens 53 are installed near the light source l of the illumination optical system as shown in FIG. Polarizing plates 54 were installed on the back and front of the liquid crystal display panel 62. A large-scale cooling device 55 was always installed on the liquid crystal display panel and the two polarizing plates. The image on the liquid crystal display panel 52 was projected onto the screen 9 by the light source l of the illumination optical system. This method also includes a method of combining three colors of light: red, green, and blue.

Furthermore, there are other conventional techniques for avoiding temperature increases in the liquid crystal display panel and the two polarizing plates. The basic configuration of a reflective projection type liquid crystal display device will be explained below with reference to FIG.

As shown in FIG. 4, a back reflector 4 is installed in close contact with the back electrode side of the liquid crystal display panel 2, which is the side opposite to the light source 1 of the illumination optical system. After the illumination light from the illumination optical system passes through the liquid crystal display panel 2, it is reflected by the rear reflector 4, and an image of the projection light that passes through the liquid crystal display panel 2 again is enlarged and projected onto the screen 9. The light shielding plate 56 surrounds the light source of the illumination optical system and the illumination light, and blocks leakage light.

[Problems to be Solved by the Invention] However, in the conventional CRT described above, the large screen makes the device large and difficult to move and carry, making it an expensive product.

Furthermore, in liquid crystal display panels and EL panels, large screens are difficult to manufacture.

Furthermore, there is a transmission type projection type liquid crystal display device that combines the three colors of red, green, and blue light and allows the light to pass through the liquid crystal display panel only once in one direction. The temperature of the display panel increases, causing malfunction of the liquid crystal display panel. In addition, since a large-scale cooling device is required to lower the temperature of the liquid crystal display panel, the device becomes large, difficult to move and carry, and becomes an expensive product.

Furthermore, a back reflector is installed closely on the back electrode side of the liquid crystal display panel, which is the opposite side of the light source of the illumination optical system, so that the illumination light from the illumination optical system is reflected back onto the back reflector after passing through the liquid crystal display panel. The image of the projected light transmitted through the liquid crystal display panel,
There is a reflective projection type liquid crystal display device that enlarges and projects images. However, [2] In this method, each pixel of the liquid crystal display panel is provided with red, green, and blue color filters, so when the light passes through the liquid crystal display panel once, the light is reduced to one-third, and the amount of light that passes through the liquid crystal display panel is reduced to one-third. The disadvantage is that the projected image becomes dark because it passes through the screen several times. Therefore, the present invention is intended to solve these problems, and its purpose is to provide a bright and large screen, but because it is lightweight, it has good portability when moving.
The purpose of the present invention is to provide an inexpensive projection type liquid crystal display device.

[Means for solving the problem] A liquid crystal display panel for displaying an image, two polarizing plates, a light source for projection, an illumination optical system for illuminating the liquid crystal display panel, and an enlarged projection of the display on the liquid crystal display panel. In a reflective projection type liquid crystal display device equipped with a projection optical system and a Fresnel reflector for reflecting light that has passed through the liquid crystal display panel and condensing the light after passing through the liquid crystal display panel, the liquid crystal display It is characterized by a structure in which three dedicated panels for red, green, and blue are used to synthesize three colors of light to display color.

[Function] According to the above configuration of the present invention, the entire surface of the liquid crystal display panel is illuminated with the illumination light emitted from the light source and the illumination light collected by the condensing mirror. Then, the illumination light passes through the liquid crystal display panel, is reflected by the rear reflector, and passes through the liquid crystal display panel again to become projection light. The projection light is focused onto a projection lens by a rear reflector, reflected by the projection reflector, and projected onto a screen.

In the prior art, each pixel of the liquid crystal display panel is provided with red, green, and blue color filters, so that when the light passes through the liquid crystal display panel once, the light is reduced to one-third. but,
It uses three dedicated liquid crystal display panels for red, green, and blue, and is configured to display color by combining the three colors of light after passing through the liquid crystal display panel.

As a result, the brightness has improved dramatically.

Furthermore, because the light from the light source is distributed and illuminated on three dedicated liquid crystal display panels for red, green, and blue, images can be projected brightly without increasing the temperature of the liquid crystal display panel and two polarizing plates. .

[Embodiment 1] In Embodiment 1 of the specific application field of the present invention, the light source is separated from the red, green and front panel liquid crystal display panels, and a single polarizing plate for illumination light and a single Fresnel-type concave rear reflector are used. was placed in close contact with the liquid crystal display panel on the opposite side of the light source. This is a case in which three colors of light are combined on a screen and a color display is performed using a reflective projection type liquid crystal display device for red, green, and front light.

The basic configuration of a reflective projection type liquid crystal display device according to a first embodiment of the present invention is shown in FIG. 1 and will be described in detail.

The light source 1 of the illumination optical system and the liquid crystal display panel 11 for last spring are the first
As shown in the figure, it is installed at a distance of about 300 mm 1 ltl, and a single polarizing plate 3 for illumination light is installed on the back electrode side opposite to the light source 1 with respect to the liquid crystal display panel 11 for last spring, and a single Fresnel type concave back reflection Mirror 4 was installed closely. Further, a projection lens 5 was installed in line with the light source 1 of the illumination optical system. Furthermore, a flat projection reflector 6 was installed above it so that the image could be projected onto a screen 9. The projection polarizing plate 7 was installed after the flat projection reflecting mirror 6. In addition, a concave condenser mirror 8 was installed in order to efficiently illuminate the liquid crystal display panel 11 with the light source 1.

Similarly, liquid crystal display panels 12 and 13 for green and youth,
Polarizing plates etc. were installed as shown in Figure 1.

The entire surface of the spring liquid crystal display panel 11 is illuminated by the illumination light emitted from the light source 1 and the illumination light collected by the concave condenser mirror 8. Then, the illumination light passes through the liquid crystal display panel 11 for last spring, passes through the polarizing plate 3 for illumination light, is reflected on the back reflector 4, and then passes through the polarizing plate 3 for anti-illumination light and the liquid crystal display panel 11 for last spring. and becomes projected light.

The projection light is focused on a projection lens 5 by a back reflector 4, reflected on a projection reflector 6, transmitted through a projection light polarizing plate 7, and projected onto a screen 9.

Similarly, the images on the liquid crystal display panels 12 and 13 for green and youth are also projected onto the screen 9 and combined.

[Embodiment 2] In Embodiment 1 of the specific application field of the present invention, the light source is separated from the red, green and foreshock liquid crystal display panels, and a single polarizing plate for illumination light and a single Fresnel type concave rear reflector are used. was placed in close contact with the liquid crystal display panel on the opposite side of the light source. In the case where the reflective projection type liquid crystal display device for red, green, and youth is configured to synthesize three colors of light on the screen and display the color, there is also a liquid crystal display panel for red, green, and youth. 11 and 1
This is a case where the illumination light source 10 for illuminating the lights 2 and 13 is shared.

The basic configuration of a reflective projection type liquid crystal display device according to a second embodiment of the present invention is shown in FIG. 2 and will be described in detail. However, in FIG. 2 of Example 2, only the red and green dedicated liquid crystal display panels 11 and 12 and the display structure are shown, and the foreshock liquid crystal display panel 13 and the display structure are omitted.

The light source 10 of the present invention of the illumination optical system and the spring liquid crystal display panel 11 were installed at a location with an IL of about 300 mm% as shown in FIG.
A single illumination light polarizing plate 3 and a single Fresnel-type concave rear reflecting mirror 4 were installed closely on the back electrode side opposite to the light source 10 with respect to the liquid crystal display panel 11 for last spring. Also, a light source i of the illumination optical system.

A projection lens 5 was installed in parallel with the. Furthermore, a flat projection reflector 6 was installed above it so that the image could be projected onto a screen 9. The projection light polarizing plate 7 was installed after the flat projection reflecting mirror 6. In addition, a concave condenser mirror 8 was installed in order to efficiently illuminate the red, green, and foreshock liquid crystal display panels 11, 12, and 13 with the light source IO.

Similarly, liquid crystal display panels 12 and 13 for green and youth, polarizing plates, etc. were installed as shown in Figure 2.

With the illumination light emitted from the light source 10 and the illumination light collected by the condenser mirror 8,
The entire surface of the liquid crystal display panel 11 for last spring is illuminated. Then, the illumination light passes through the liquid crystal display panel 11 for last spring, passes through the polarizing plate 3 for illumination light, is reflected on the back reflector 4, and then passes through the polarizing plate 3 for illumination and the liquid crystal display panel 11 for last spring. becomes the projected light.

The projection light is focused on a projection lens 5 by a back reflector 4, reflected on a projection reflector 6, transmitted through a projection light polarizing plate 7, and projected onto a screen 9.

Similarly, images on the green and foreshock liquid crystal display panels 12 and 13 are also projected onto the screen 9 by the light source 10.

In addition, in the second embodiment of the present invention, the illumination light source 10 is shared, but the three-color light of red, green, and youth liquid crystal display panels is combined, then focused on a projection lens, and projected onto a screen. However, the effect is the same even if it is displayed in color.

In the present invention, a flat projection mirror 6 is installed, but the projection mirror 6 can be omitted if the main body is laid down.

Note that this projection type liquid crystal display device can not only be enlarged by freely changing the distance to the screen, but also can be applied to a device in which the distance to the screen is fixed.

[Effects of the Invention] As described above, according to the present description, in a reflective projection display device that uses a reflector to display images and characters, the back reflector is installed closely to the back electrode side and enlarged projection can be performed. This greatly simplified the optical system on the light source side. The liquid crystal display panel uses three panels (red, green, and front panel) to synthesize three colors of light and display color, so the temperature of the liquid crystal display panel and two polarizing plates does not rise. They succeeded in increasing the brightness of the light source and brightening the image. This results in
It has become possible to provide a display device that is bright, has a large screen, is lightweight, has good portability when moving, and is inexpensive.

Another effect is that if a Fresnel-type concave mirror, convex mirror, or plane mirror is used as a reflecting mirror, an assembly type becomes possible.
It is a compact device.

[Brief explanation of drawings]

FIG. 1 is a basic schematic diagram of a reflective projection type liquid crystal display device according to a first embodiment of the present invention. FIG. 2 is a basic schematic diagram of a reflective projection type liquid crystal display device according to a second embodiment of the present invention. FIG. 3 is a basic schematic diagram of a basic transmission type projection type liquid crystal display device of the prior art. FIG. 4 is a basic schematic diagram of a conventional reflective projection type liquid crystal display device. 1... Light source 2... Liquid crystal display panel of conventional technology 3... Polarizing plate for illumination light 4... Fresnel type concave back reflector 5... Projection lens 6... Projection reflector 7 ...Polarizing plate for projection light 8...Concave condenser mirror 9...Screen lO...Light source 11 of Example 2 of the present invention...Last spring liquid crystal display panel 12 of the present invention...Green of the present invention Dedicated liquid crystal display panel 3 1 2 3 4 5 6 Liquid crystal display panel for front end of the present invention Condensing lens of the prior art Liquid crystal display panel of the prior art Projection lens of the prior art Polarizing plate of the prior art Cooling device of the prior art More than a light shielding plate

Claims (1)

[Claims] A liquid crystal display panel for displaying an image, two polarizing plates, a light source for projection, an illumination optical system for illuminating the liquid crystal display panel, a projection optical system for enlarging and projecting the display on the liquid crystal display panel, and the liquid crystal display panel. In a reflective projection type liquid crystal display device equipped with a Fresnel reflector for reflecting the light that has passed through the liquid crystal display panel and condensing the light, the liquid crystal display panel is used exclusively for red, green, and blue. A projection type liquid crystal display device characterized in that it is configured to use three panels to synthesize three colors of light and display a color display.