JPH01246588A - Light guiding system for projection type display device - Google Patents

Abstract

PURPOSE:To obtain a video of uniform brightness by diffusing the light in the central part of collimated beans of light where the luminous flux density is high to diffused light by a reflecting mirror with a convex face and a filter with a concave lens and illuminating this light to the entire surface of a transmission type panel. CONSTITUTION:The reflecting mirror 10 with the convex face is provided just before a blue display liquid crystal panel 12 and a red display liquid crystal panel 14 and the filter 11 with the concave face is provided just before a green display liquid crystal panel 13. The collimated beams 2 of light in the central part of the collimated beams 1 of light where the luminous flux density is high are, therefore, reflected by the convex face part of the mirror 10, by which said beams are spread as the diffused light. The collimated beams 2 of light of the high luminous flux density transmitting the filter 11 are transmitted through the concave lens parts of the filter 11, by which said beams are spread as the diffused light. The video which is bright to the peripheral part is thereby obtd.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a light guiding method for a projection display device.

[Conventional technology]

As shown in the conventional example diagram in FIG.
As a result, collimated light is obtained, which is transmitted or reflected through the flat guichroic mirror 55 and the reflecting mirror 54, and is guided to the transmission panel 55.

[Problem to be solved by the invention]

However, the luminous flux distribution of the collimated light obtained by the conventional light guiding method is dense in the center and sparse in the periphery, so that the display on the transmissive panel is bright only in the center and dark in the periphery. Therefore, the projected image also has the problem that only the center part is bright and the peripheral part is dark (difficult to see).

SUMMARY OF THE INVENTION The present invention is intended to solve these problems, and its purpose is to provide a light guide method that makes the luminous flux distribution of collimated light illuminating a transmissive panel more uniform.

[Means to solve the problem]

The light guide system of the projection display device of the present invention has three transmissive panels, each of which is illuminated with light of the three primary colors of red, green, and blue, and images from the three transmissive panels are combined and projected. The display device is characterized by having a reflecting means having a convex surface only at the center and a filter having a concave lens only at the center.

[Effect]

According to the above configuration of the present invention, the collimated light with a dense luminous flux density in the central part becomes diffused light by the reflection means having a convex surface only in the central part, and thus illuminates the entire panel. More uniform illumination can be obtained.

In addition, the frimate light that passes through the filter, which has a concave lens only in the center, becomes diffused light only in the central part where the luminous flux density is high, illuminating the entire panel, so more uniform illumination can be obtained.

As a result, the projected image is bright even to the periphery.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a principle diagram of the light guide system, and FIG. 2 is an internal perspective view of the light guide unit.

A light beam emitted from a light source 3 such as a halogen lamp or a xenon lamp becomes collimated light 1 by a lens 4, and after the heat rays are absorbed by a heat absorption filter 5, it enters a housing 6 of a light guiding unit. Collimated light 1 entering the housing 6
Only the blue component of the collimated light 1 is reflected by the blue reflecting dichroic mirror 7, and illuminates the blue display liquid crystal panel 12 via the convex reflecting mirror 1o.

The orange light transmitted through the blue reflecting dichroic mirror 7 is reflected by the green reflecting dichroic mirror 8, where only the green component of the collimated light 1 is reflected, and passes through a filter with a concave lens to illuminate the green display liquid crystal panel 13.

The red collimated light 1 transmitted through the green reflecting dichroic mirror 8 is reflected by the reflecting mirror 9. A red display liquid crystal panel 14 is illuminated through a convex reflecting mirror 10. As the reflection mirror 9, a red reflection gichroic mirror may be used to improve color purity.

The luminous flux distribution of the collimated light 1 is normally dense in the center and sparse in the periphery. It is clear that if the liquid crystal panel is illuminated with the collimated light 1 having such a luminous flux distribution, the display on the liquid crystal panel will be bright at the center and dark at the periphery. In order to achieve a display with more uniform brightness from the center to the periphery, in this embodiment, a convex reflecting mirror 10 is provided immediately before the blue display liquid crystal panel 12 and the red display liquid crystal panel 14, and the green display liquid crystal panel 13 Just before the filter 11 with concave lens
has been established.

The collimated light 2, which has a dense luminous flux density at the center of the collimated light 1, is reflected by the convex surface of the convex reflecting mirror 10 to become diffused light and spread, thereby illuminating the entire liquid crystal panel. Therefore, the luminous flux density of the illumination on the surface of the liquid crystal panel is more averaged, so that the difference in brightness between the center and the periphery of the displayed image is equalized, and a display with -like brightness can be obtained.

Further, the collimated light 2 having a high luminous flux density that passes through the filter 11 with a concave lens is transmitted through the concave lens part of the filter 11 with a concave lens, and becomes diffused light and spreads, thereby illuminating the entire liquid crystal panel. Therefore, the display on the liquid crystal panel can have a negative brightness.

The images displayed on the blue display liquid crystal panel 12 and the red display liquid crystal panel 14 are reflected by the cube prism 15 and reach the projection lens 16, and the images displayed on the green display liquid crystal panel 15 are transmitted through the cube prism 15 and projected. Leading to the lens.

The cube prism 15 is made by laminating four rectangular prisms each having a dichroic layer that reflects red or blue light, and combines the images of three H-crystal panels by reflecting or transmitting them. By projecting the combined color image onto a screen using the projection lens 16, a projected image with uniform brightness can be obtained.

FIG. 3 is a layout diagram of another embodiment, and is an example in which the cube prism 15 is not used.

In the embodiment described above, two convex reflective mirrors of 1° are used.
Although the purpose was achieved by using one filter 11 with a concave lens, in the other embodiment shown in FIG. 3, the purpose was achieved by using one reflective mirror 10 with a convex surface and two filters 11 with concave lenses. .

That is, a convex reflecting mirror 10 is provided immediately before the blue display liquid crystal panel 12, and a filter with a concave lens is provided immediately before the green display liquid crystal panel 15 and the red display liquid crystal panel 14 to obtain uniform illumination.

The images displayed on the three liquid crystal panels are reflected or transmitted through the green reflective dichroic mirror 8 and the red reflective dichroic mirror 17, combined, and projected by the projection lens 16.

Note that the filter 11 with a concave lens is not just a transparent filter, but may be a color filter or the like that improves color purity.

〔Effect of the invention〕

As described above, according to the present invention, the light in the central part where the luminous flux density of the collimated light is high is converted into diffused light by the convex reflective mirror and the concave lens filter, and the entire surface of the transmissive panel is illuminated. There is no difference in brightness between the center and the periphery of the display, making it possible to obtain a good image.

Therefore, it is possible to obtain a projected image with varying brightness up to the periphery of the screen.

[Brief explanation of the drawing]

Figure 1 is a diagram of the principle of the light guiding method. FIG. 2 is an internal perspective view of the light guide unit. FIG. 5 is a layout diagram of another embodiment. FIG. 4 is a diagram of a conventional example. 1...Collimated light 2...Dense collimated light 5...
...Light source 4...Lens 5...Heat absorption filter 6...
... Housing 7 ... Blue reflective dichroic mirror 8.
...Green reflective dichroic mirror 9...
...Reflection mirror 10 ...Reflection mirror with convex surface 11 ...Filter with concave lens 12 ...
-Blue display liquid crystal panel 15...Green display liquid crystal panel 14...Red display liquid crystal panel 15...Cube prism 16...Projection lens 17... ...Red reflective dichroic mirror and above Applicant Seiko Epson Co., Ltd. agent Tsutomu Mogami, patent attorney (and 1 other person) 11th! I Figure 3

Claims (1)

[Claims] In a display device that has three transmissive panels, each illuminated with light of the three primary colors of red, green, and blue, and that synthesizes and projects images from the three transmissive panels, a reflecting means in which only the central portion is convex. and a light guide system for a projection display device, characterized by having a filter with a concave lens only in the center.