JPH0318887A - 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 [Industrial Application Field] 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 CRT is a conventional device for displaying images and characters. 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, as a basic example of the prior art as shown in FIG. 4, there is a projection type liquid crystal display device in which light is transmitted through the liquid crystal display panel only once in one direction. This 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 1 of the illumination optical system as shown in FIG. Polarizing plates 54 were installed on the front and back 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 9 by the light source 1 of the illumination optical system. This method also includes a method that combines three colors of light: red, green, and blue.

Additionally, there are other prior art methods to avoid temperature increases in the liquid crystal display panel and the two polarizers. This will be explained below with reference to FIG. As shown in FIG. 5, 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. Then, the illumination light from the illumination optical system passes through the liquid crystal display panel 2, 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. There is.

The light shielding plate 56 surrounds the light source of the illumination optical system and the illumination light, and the inside is painted black.

[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 are projection-type liquid crystal display devices that combine the three colors of red, green, and blue light, allowing the light to pass through the liquid crystal display panel only once in one direction. The temperature rises and the LCD panel malfunctions. In order to lower the temperature of the liquid crystal display panel, a large-scale cooling device is required, making the device large, difficult to move and carry, and 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. There is a method of enlarging and projecting an image of projection light transmitted through a liquid crystal display/f channel. However, this method has the disadvantage that the projected image becomes dark because it passes through polarizers and color filters several times. SUMMARY OF THE INVENTION 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, has good portability when moving, is inexpensive, and has a bright and large screen. There it is.

[Means for solving the problem] (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, and a display on the liquid crystal display panel. In a reflective projection type liquid crystal display device equipped with a projection optical system for enlarging projection 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 present invention is characterized in that the light source of the illumination optical system and the inside of the light shielding plate surrounding the illumination light are reflective mirrors, so that the liquid crystal display panel can be illuminated with the illumination light without waste.

(2) The inside of the light shielding plate is comprised of a reflecting mirror having an angle to reflect the illumination light incident on the light shielding plate from the light source back to the light source.

(3) The inside of the light shielding plate is comprised of a reflecting mirror having an angle to reflect the illumination light incident on the light shielding plate from the light source back onto the liquid crystal display panel.

(4) The inside of the light shielding plate is composed of a reflecting mirror and a diffused reflecting mirror.

[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 on the projection lens by the rear reflector,
The light is reflected by the projection mirror and projected onto the screen.

However, the light that hits some of the light shielding plates turns into heat,
It does not contribute to the illumination of the liquid crystal display panel in any way. Therefore, by installing a reflective mirror or a diffused reflection mirror inside the light shielding plate, the light from the light source can be effectively used by reflecting the light that has come from the light source to the light shielding plate and returning it to the light source, or directly reflecting it to the liquid crystal display panel. You can make the image brighter.

[Example 1] In Example 1 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 placed on the side opposite to the light source. It was installed in close contact with the liquid crystal display panel. Furthermore, the light source of the illumination optical system and the inside of the light-shielding plate surrounding the illumination light are reflective mirrors, making it possible to illuminate the liquid crystal display panel without wasting illumination light. Therefore, the light shielding plate is a collection of reflecting mirrors with an angle that reflects the light coming from the light source to the light shielding plate so as to return to the light source.

The basic configuration of Embodiment 1 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 2 are about 300 mm 1lt as shown in Figure 1! A single polarizing plate 3 for illumination light and a single Fresnel-type concave rear reflecting mirror 4 are installed at the L position, 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 2.
were installed closely together. 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 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 liquid crystal display panel 2 with the light source 1. Furthermore, a light shielding plate 10 was installed around the light source, illumination light, and projection light. The inside of the light shielding plate is composed of a reflecting mirror having an angle to reflect the light that has come from the light source l to the light shielding plate so as to return to the light source.

The entire surface of a liquid crystal display panel 2 is illuminated by the illumination light emitted from a light source 1 and the illumination light collected by a condensing mirror 8. Then, the illumination light passes through the liquid crystal display panel 2, passes through the illumination polarizing plate 3, is reflected on the back reflector 4, and passes through the illumination polarizing plate 3 and the liquid crystal display panel 2 again to become projection light. . The projection light is focused on a projection lens 5 by a rear reflecting mirror 2, reflected on a projection reflecting mirror 6, transmitted through a projection polarizing plate 7, and projected onto a screen 9.

Further, the light that has entered the light shielding plate 10 from the light source 1 returns to the light source 1 again, is reflected by the condenser mirror 8, and illuminates the entire surface of the liquid crystal display panel 2.

[Embodiment 2] In Embodiment 2 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 placed on the side opposite to the light source. It was installed in close contact with the LCD panel. Furthermore, the light source of the illumination optical system and the light shielding plate that surrounds the illumination light have a reflector on the inside, so that the illumination light can be used to illuminate the LCD panel without wasting the light. The setup is a collection of reflecting mirrors with angles that reflect the light that has come from the light source to the light shielding plate and illuminates the liquid crystal display panel again.

The basic configuration of Embodiment 2 of the present invention is shown in FIG. 2 and will be described in detail.

The basic configuration is the same as the first embodiment, so a description thereof will be omitted.

However, a light-shielding plate 11 is installed around the light source, illumination light, and projection light, and inside the light-shielding plate is a reflecting mirror with an angle that reflects the light that has come from the light source 1 to the light-shielding plate and illuminates the liquid crystal display panel 2 again. It is made up of.

The entire surface of the liquid crystal display panel 2 is illuminated by the illumination light emitted from the light source 1 and the illumination light collected by the condenser mirror 8. Then, the illumination light passes through 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 and the liquid crystal display panel 2 to become projection light. Become. The projection light is focused on a projection lens 5 by a rear reflecting mirror 2, reflected on a projection reflecting mirror 6, transmitted through a projection light polarizing plate 7, and projected onto a screen 9.

Further, the light incident on the light shielding plate 11 from the light source 1 directly illuminates the liquid crystal display panel 2.

[Embodiment 3] In Embodiment 3 of a specific field of application 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 placed on the side opposite to the light source. It was installed in close contact with the LCD panel. Furthermore, the light source of the illumination optical system and the inside of the light shielding plate surrounding the illumination light are a reflecting mirror and a diffused reflecting mirror, so that the liquid crystal display panel can be illuminated without wasting the illumination light.

The basic configuration of Embodiment 30 of the present invention is shown in FIG. 3 and will be described in detail.

The basic configuration is the same as the first embodiment, so a description thereof will be omitted.

However, a light-shielding plate 12 is installed around the light source, illumination light, and projection light, and the inside of the light-shielding plate is composed of a reflecting mirror and a diffused reflecting mirror that reflects the light that has come from the light source 1 to the light-shielding plate and illuminates the liquid crystal display panel again. has been done.

The entire surface of a liquid crystal display panel 2 is illuminated by the illumination light emitted from a light source 1 and the illumination light collected by a condensing 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 projected light. becomes. The projection light is focused on a projection lens 5 by a rear reflecting mirror 2, reflected on a projection reflecting mirror 6, transmitted through a projection light polarizing plate 7, and projected onto a screen 9.

Further, the light incident on the light shielding plate 12 from the light source 1 returns to the light source 1 again, is reflected by the condenser mirror 8, and illuminates the entire surface of the liquid crystal display panel 2, or directly illuminates the liquid crystal display panel 2.

In the present invention, a flat projection reflector 6 is installed, but
If the main body is placed horizontally, the projection reflector 6 can be omitted.

[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. Then, by installing a reflective mirror or a diffused reflection mirror inside the light shielding plate, the light from the light source can be effectively used by reflecting the light that has come from the light source to the light shielding plate and returning it to the light source, or directly reflecting it to the liquid crystal display panel. We succeeded in increasing the brightness of the light source and brightening the image without increasing the temperature of the Tα crystal display panel. This makes it possible to provide a display device that is bright, has a large screen, is lightweight, has good flatness during transportation, 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 display device in Example 1 of the present invention. FIG. 2 is a basic schematic diagram of a reflective projection display device according to a second embodiment of the present invention. FIG. 3 is a basic schematic diagram of a reflective projection display device according to a third embodiment of the present invention. FIG. 4 is a schematic diagram of a basic transmission type projection display device of the prior art. FIG. 5 is a schematic diagram of another prior art transmissive projection display device. l...Light source 2...Liquid crystal display panel 3...Polarizing plate for illumination light 4...Fresnel type concave reflecting mirror 5...Projection lens 6...Reflecting mirror for projection Polarizing plate for projection light Concave condensing mirror screen Light-shielding plate of Embodiment 1 of the present invention Light-shielding plate of Embodiment 2 of the present invention Light-shielding plate of Embodiment 3 of the present invention Concentrating lens of prior art Liquid crystal display panel of prior art For projection Lens Conventional technology polarizing plate Conventional technology cooling device Conventional technology light shielding plate or higher

Claims (4)

[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 reflector for reflecting light that has passed through a display panel, passing through the liquid crystal display panel again, and condensing the light, the light source of the illumination optical system and the 1. A projection type liquid crystal display device characterized in that the liquid crystal display panel can be illuminated with the illumination light without waste by having a reflective mirror on the inside of a light-shielding plate that surrounds the illumination light. (2) The inside of the light shielding plate is comprised of a reflecting mirror having an angle to reflect the illumination light incident on the light shielding plate from the light source back to the light source. Projection type liquid crystal display device. (3) The inside of the light shielding plate is comprised of a reflecting mirror having an angle to reflect the illumination light incident on the light shielding plate from the light source back onto the liquid crystal display panel. projection type liquid crystal display device. (4) The projection type liquid crystal display device according to claim 1, wherein the inside of the light shielding plate is composed of a reflecting mirror and a diffused reflecting mirror.