JPH0336588A - Projection type liquid crystal display device - 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 [Field of Industrial Application] The present invention relates to a reflective projection type liquid crystal display device that uses a Fresnel type rear reflector or the like to display images and characters.

[Prior Art] A CRT is a conventional device for displaying images and characters. Recently, there are manufactured 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. 5 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 product display panel 52, and a projection lens 53 are installed near the light source 1 of the illumination optical system as shown in FIG. Polarizing plates 54 were installed on the back and front sides of the liquid crystal display panel 52. 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 10 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. 6, a back reflecting mirror 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 1i 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 10. The light shielding plate 9 surrounds the light source of the illumination optical system and the illumination light, and blocks leakage light. The image of the light source 5 is on the screen.
6 is projected.

[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. And rei.

Since a large-scale cooling device is required to lower the temperature of the high display panel and polarizing plate, 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, in this method, if the illumination optical system for illuminating the liquid crystal display panel is simplified, such as with only a light source and a concave condenser mirror, the image of the light source will be directly reflected and projected onto the surface of the liquid crystal display panel. Therefore, the brightest part of the Fresnel type rear reflector must be avoided and the liquid crystal display panel must be made smaller, which has the disadvantage that the projected image becomes dark.

The present invention is intended to solve these problems, and its purpose is to provide a projection-type liquid crystal display device that is lightweight and has good portability when moving, is inexpensive, and has a bright and large screen. It's there.

[Means for Solving the Problems] (1) The projection type liquid crystal display device of the present invention includes a liquid crystal display panel for displaying an image, two polarizing plates, a light source for projection, and illumination for illuminating the liquid crystal display panel. A reflection device comprising an optical system, a projection optical system for enlarging and projecting the display on the liquid crystal display panel, and a Fresnel back reflector for reflecting the light that has passed through the liquid crystal display panel, passing it through the liquid crystal display panel again, and condensing the light. This projection type liquid crystal display device is characterized in that the image of the light source is directly reflected on the surface of the liquid crystal display panel and is not projected.

(2) A concave condenser mirror for efficiently illuminating the liquid crystal display panel with the light source, and the light source is tilted to illuminate only half from the center of the Fresnel back reflector, and only half from the center of the Fresnel back reflector is used. characterized by things.

(3) The liquid crystal display panel is inclined from 0 degrees to 45 degrees with respect to the Fresnel back reflector.

(4) A non-reflective film is formed on the surface of the liquid crystal display panel.

(5) A brightness averaging plate is installed in front of the light source and the concave condenser mirror to illuminate the liquid crystal display panel.

[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 concave condenser 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, if the illumination optical system for illuminating the liquid crystal display panel is simplified by just a light source and a concave condenser mirror, the image of the light source will be directly reflected and projected onto the surface of the liquid crystal display panel. Therefore, we adopted the following configuration in which the light source does not directly reflect and project onto the surface of the liquid crystal display panel.

For example, by tilting the light source and concave condenser mirror to illuminate only half of the Fresnel back reflector from the center, and using only half of the Fresnel back reflector from the center, the part where the image of the light source is reflected on the surface of the LCD panel can be reduced. I made the configuration without it.

Furthermore, the liquid crystal display panel is tilted from 0 degrees to 45 degrees with respect to the reflecting mirror.
The image of the light source is reflected on the surface of the liquid crystal display panel, and the reflected projection light does not enter the projection lens.

Furthermore, a non-reflective film such as MgF2 is coated on the surface of the liquid crystal display panel to prevent the image of the light source from being reflected on the surface of the liquid crystal display panel.

A brightness averaging plate was installed in front of the light source and the concave condenser mirror to scatter the image of the light source.

As a result, the image of the light source is directly reflected and not projected onto the surface of the liquid crystal display panel.

[Embodiment 1] In Embodiment 1 of the specific application field of the present invention, the light source and the liquid crystal display panel are separated, and a single illumination polarizing plate and a single Fresnel type concave rear reflecting mirror are used to connect the liquid crystal display panel to the opposite side of the light source. It was installed closely to the display panel. In order to efficiently illuminate the liquid crystal display panel with a light source, a concave condenser mirror and a light source are tilted to illuminate only half of the center of the Fresnel back reflector, and only half of the Fresnel back reflector is used from the center. be.

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 11 of the illumination optical system and the liquid crystal display panel 13 were placed approximately 300 mm apart as shown in FIG.

Then, a single illumination light polarizing plate 14 and a single planel type concave back reflecting mirror 15 were installed in close contact with the liquid crystal display panel 13 on the back electrode side opposite to the light [11]. Further, a projection lens 5 was installed in line with the light source 11 of the illumination optical system. Furthermore, a flat projection reflector 6 was installed above it so that the image could be projected onto the screen IO. Polarizing plate 7 for projection light
was installed after the projection lens 5. In addition, in order to efficiently illuminate the liquid crystal display panel 13 with the light source 11, a concave condenser mirror 1 is used.
2 was installed. In order to efficiently illuminate the liquid crystal display panel with a light source, the concave condenser mirror 12 and the light source 11 are tilted so that only half of the center of the Fresnel back reflector can be illuminated.

The entire surface of the liquid crystal display panel 13 is illuminated by the illumination light emitted from the light source 11 and the illumination light collected by the concave collector mirror 12. Then, the illumination light passes through the liquid crystal display panel 13, and the illumination light polarizing plate 1
4, is reflected by the rear reflecting mirror 15, and then passes through the anti-illumination light polarizing plate 14 and the liquid crystal display panel 13 to become projection light. The projection light is focused on the projection lens 5 by the rear reflector 15, transmitted through the projection light polarizing plate 7, reflected by the projection reflector 6, and projected onto the screen IO.

Since there is no part on the surface of the liquid crystal display panel from which the image of the light source is directly reflected, the image of the light source is not directly reflected and projected onto the surface of the liquid crystal display panel.

[Embodiment 2] In Embodiment 2 of the specific application field of the present invention, the light source and the liquid crystal display panel are separated, and a single polarizing plate for illumination light and a single Fresnel type concave rear reflecting mirror are installed on the opposite side from the light source. It was installed in close contact with the liquid crystal display panel. This is a case in which the liquid crystal display panel is inclined at 20 degrees with respect to the rear reflecting mirror.

Embodiment 2 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.

The liquid crystal display panel 16, which is inclined at 20 degrees with respect to the rear reflector, is approximately 300 mm away from the light source 1 of the illumination optical system as shown in Figure 2.
It was placed in a separate location. - Then, a single illumination polarizing plate 3 and a single Fresnel-type concave rear reflecting mirror 4 were installed in close contact with each other on the back electrode side opposite to the light source 1 with respect to the liquid crystal display panel 16. Further, a projection lens 5 was installed in line with the light source l of the illumination optical system. Furthermore, a flat projection reflector 6 was installed above it so that the image could be projected onto the screen IO.

The projection light polarizing plate 7 was installed after the projection lens 5.

In addition, a concave condenser mirror 8 was installed in order to efficiently illuminate the liquid crystal display panel 16 with the light source 1.

The entire surface of the liquid crystal display panel 16 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 16, passes through the illumination light polarizing plate 3, is reflected on the back reflector 4, and then passes through the anti-illumination light polarizing plate 3 and the liquid crystal display panel 16 to become projection light. becomes. The projection light is focused on the projection lens 5 by the rear reflector 4, transmitted through the projection light polarizing plate 7, reflected by the projection reflector 6, and projected onto the screen IO.

Then, the liquid crystal display panel 16 is 2
Since it is tilted at 0 degrees, the projection light reflected on the surface of the liquid crystal display panel does not enter the projection lens.

In the present invention, the liquid crystal display panel 16 is inclined at 20 degrees with respect to the rear reflector 4, but the angle of inclination is determined by the size of the liquid crystal display panel 16 and the size of the rear reflector 4, and the angle can vary from 0 degrees. The effect is the same even if adjusted up to 45 degrees.

[Embodiment 3] In Embodiment 3 of the specific application field of the present invention, the light source and the display panel are separated, and a single polarizing plate for illumination light and a single Fresnel-type concave rear reflecting mirror are placed on the opposite side from the light source. It was installed in close contact with the liquid crystal display panel. This is a case where a non-reflective film is formed on the surface of the liquid crystal display panel.

The basic configuration of a reflective projection type liquid crystal display device according to a third embodiment of the present invention is shown in FIG. 3 and will be described in detail.

A 0.05 micron non-reflection film 17 of MgF2 was formed on the surface of the liquid crystal display panel 2, and was placed approximately 300 mm away from the light source 1 of the illumination optical system as shown in FIG. A single illumination light polarizing plate 3 and a single Fresnel-type concave rear reflecting mirror 4 were installed in close contact with the liquid crystal display panel 2 on the back electrode side opposite to the light source 1. Further, a projection lens 5 was installed in line with the light source l of the illumination optical system. Furthermore, above it, a flat projection reflector 6 is provided so as to be able to project onto the screen 10.
was installed. The projection light polarizing plate 7 was installed after the projection lens 5. In addition, a concave condenser mirror 8 was installed to efficiently illuminate the product display panel 2 with the light source 1.

The entire surface of the liquid crystal display panel 2 is illuminated with 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 non-reflection film 17 and the liquid crystal display panel 2, passes through the illumination polarizing plate 3, is reflected on the back reflector 4, and then passes through the anti-illumination light polarizing plate 3, the liquid crystal display panel 2, and the non-illumination light polarizing plate 3. The light passes through the reflective film 17 and becomes projection light. The projection light is focused on the projection lens 5 by the rear reflector 4, transmitted through the projection light polarizing plate 7, reflected by the projection reflector 6, and projected onto the screen 10.

Since the non-reflective film 17 is formed on the surface of the liquid crystal display panel, the image of the light source is not reflected on the surface of the liquid crystal display panel.

Further, in the present invention, the non-reflective film 17 is formed on the entire surface of the liquid crystal display panel, but the effect is the same even if the film is formed only on the center of the Fresnel-type concave back reflector where the image of the light source is reflected. It is.

In the present invention, the non-reflective film 17 is entirely formed with MgF2 to a thickness of 0.05 microns on the surface of the liquid crystal display panel.
Even if it is not F2, the thickness is o.

Even if a film is formed from 0.05 to 1.000 microns, the effect will be the same if the purpose is achieved.

[Embodiment 4] In Embodiment 4 of a specific application field of the present invention, the light source and the liquid crystal display panel are separated, and a single polarizing plate for illumination light and a single Fresnel type concave rear reflecting mirror are installed on the side opposite to the light source. It was installed in close contact with the liquid crystal display panel. This is a case in which a brightness averaging plate is installed in front of the light source and the concave condensing mirror to illuminate the liquid crystal display panel.

The basic configuration of a reflective projection type liquid crystal display device according to a fourth embodiment of the present invention is shown in FIG. 4 and will be described in detail.

The light #l of the illumination optical system and the product display panel 2 were installed at a distance of about 300 mm from each other as shown in FIG. A single illumination light polarizing plate 3 and a single Fresnel-type concave rear reflecting mirror 4 were installed in close contact with the liquid crystal display panel 2 on the back electrode side opposite to the light source 1.

Further, a projection lens 5 was installed in line with the light source l of the illumination optical system. Furthermore, a flat projection reflector 6 was installed above it so that the image could be projected onto the screen 10. The projection light polarizing plate 7 was installed after the projection lens 5. In addition, in order to efficiently illuminate the liquid crystal display panel 2 with the light source 1, a concave condenser mirror 8 is used.
was installed. Further, a brightness averaging plate 18 is installed in front of the light source and the concave condenser mirror 8.

The entire surface of a liquid crystal display panel 2 is illuminated with illumination light emitted from a light source 1 and illumination light collected by a concave condenser mirror 8.

Then, the illumination light passes through the liquid crystal display panel 2, passes through the illumination light polarizing plate 3, is reflected on the back reflector 4, and then passes through the anti-illumination light polarizing plate 3 and the liquid crystal display panel 2 to become projection light. becomes. The projection light is focused on the projection lens 5 by the rear reflector 4, transmitted through the projection light polarizing plate 7, reflected by the projection reflector 6, and projected onto the screen 10.

Since the brightness averaging plate 18 is installed in front of the light source and the concave condenser mirror, the image of the light source reflected on the surface of the liquid crystal display panel 2 is scattered.

Further, in the present invention, a combination of Example 1 and Example 2 provides a great effect. Furthermore, even if the first embodiment, the second embodiment, the third embodiment, and the fourth embodiment are combined, the effect becomes greater.

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 be enlarged by freely changing the distance to the screen, and can also be applied to devices 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 enabled the optical system on the light source side to be significantly simplified, and also succeeded in increasing the brightness of the light source and brightening images without increasing the temperature of the liquid crystal display panel and two polarizing plates.

By adopting a structure in which the light source does not directly reflect and project onto the surface of the liquid crystal display panel, we succeeded in making the finished product display panel larger and brightening the image.

This makes it possible to provide a display device that has a bright, 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 DESCRIPTION OF THE DRAWINGS FIG. 1 is a basic schematic diagram of a reflective projection 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 reflective projection type liquid crystal display device according to a third embodiment of the present invention. FIG. 4 is a basic schematic diagram of a reflective projection type liquid crystal display device according to a fourth embodiment of the present invention. FIG. 5 is a basic schematic diagram of a basic transmission type projection type liquid crystal display device of the prior art. FIG. 6 is a basic schematic diagram of a conventional reflective projection type liquid crystal display device. l...Light source 2...Prior art liquid crystal display panel 3...Polarizing plate for illumination light 4...Back reflector 5...Projection lens 6...Projection reflector 7... Polarizing plate for projection light 8... Concave condenser mirror 9... Light blocking plate 10... Screen 11... Light source 12 of Embodiment 1 of the present invention... Concave condenser mirror 13 of Embodiment 1 of the present invention ...Liquid crystal display panel of Embodiment 1 of the present invention Polarizing plate for illumination of Embodiment 1 of the present invention Rear reflector of Embodiment 1 of the present invention Liquid crystal display panel of Embodiment 2 of the present invention Non-reflective film Luminance averaging plate of Embodiment 4 of the present invention Conventional technology condensing lens Conventional technology liquid crystal display panel Conventional technology projection lens Conventional technology polarizing plate Conventional technology cooling device Conventional technology image of light source

Claims (5)

[Claims] (1) 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 back reflector for reflecting light that has passed through a display panel, passing through the liquid crystal display panel again, and condensing the light, the image of the light source is displayed on the liquid crystal display. A projection type liquid crystal display device characterized by having a structure in which no projection is reflected directly onto the surface of a panel. (2) A concave condenser mirror for efficiently illuminating the liquid crystal display panel with the light source, and the light source is tilted to illuminate only half from the center of the Fresnel back reflector, and only half from the center of the Fresnel back reflector is used. The projection type liquid crystal display device according to claim 1, characterized in that: (3) The projection type liquid crystal display device according to claim 1, wherein the liquid crystal display panel is inclined from 0 degrees to 45 degrees with respect to the Fresnel back reflector. (4) The projection type liquid crystal display device according to claim 1, wherein a non-reflective film is formed on the surface of the liquid crystal display panel. (5) The projection type liquid crystal display device according to claim 1, characterized in that a brightness averaging plate is installed in front of the light source and the concave condenser mirror to illuminate the liquid crystal display panel.