JP2737688B2 - Color display - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a color display device using a light valve for forming an image.

[0002]

2. Description of the Related Art A conventional color display device is disclosed in
As disclosed in Japanese Patent Publication No. 150937, a monochromatic image is synthesized by a reflective light valve and a dichroic mirror.

[0003]

However, the prior art has the following problems.

First, a light valve is a cathode ray tube (CRT).
It is a large-scale device because it is controlled by the light. Second, heat was generated in the light valve by infrared light included in the light source light.

Accordingly, the present invention is to solve such a problem, and an object of the present invention is to provide a compact projection type color display device which is excellent in contrast and high in light source light use efficiency.

[0006]

According to the present invention, there is provided a color display device comprising a light source and three colors formed by separating light from the light source.
Three liquid crystal light valves that respectively modulate light;
Color light modulated by two transmissive liquid crystal light valves
Color synthesizing means, and light synthesized by the color synthesizing means.
A color display device having projection optical means for projecting light.
And the color synthesizing means comprises a right-angle portion of four right-angle prisms.
Face each other to form a cross
Along the inner surface of the cross shape
To form two different types of color light selective reflection layers into a cross shape.
Consisting of optical prisms arranged like
The liquid crystal light valve has four outer surfaces of the optical prism.
Are arranged adjacent to the three outer surfaces that are the incident surfaces, respectively.
The light source is arranged on a light emitting part and a rear side of the light emitting part.
A mirror disposed to reflect the light emitted from the light emitting portion;
The mirror has the property of transmitting infrared light,
The light reflected by the mirror is the three transmission type liquid crystal lasers.
It is characterized by being modulated by a light valve.

[0007]

FIG. 1 is a view showing the principle of a projection display apparatus according to an embodiment of the present invention.

The light diverging from the light source 1 is recollimated by the condenser lens 2, irradiates the light to the light valve 3, is enlarged and projected by the projection lens 4, and forms an image on the streen 5.

FIG. 2 is a detailed view of the light source of the present invention, wherein a is a horizontal view of the illumination system, and b is a graph showing the spectral characteristics of the reflector.

The lamp 10 is a high color rendering lamp such as a halogen lamp, a metal halide lamp, a xenon lamp, etc.
And the light is focused on the second focal point F2, and the light beam 14 by the condenser lens 13 is collimated. The elliptical mirror 11 is made of a cold mirror, and as shown in a graph b, transmits heat so that heat is hardly transmitted to the front of the illumination system in order to transmit infrared rays.

FIGS. 3A and 3B are diagrams showing the construction of a cube prism used for separating and synthesizing color light, wherein a is a perspective view of a right-angle prism, and b is a diagram showing a method of assembling the cube prism.

The right-angle prism 20 has red and blue reflection layers of a dichroic mirror on two sides narrowing the right angle, respectively.
Created by vapor deposition or sputtering, four prisms b
, The refractive indices of the pulsum and the synthetic adhesive are n = 1.52 to 1.5.
Optical bonding is performed with about 4 adhesives, and a cube prism is assembled.

FIG. 4 is a diagram showing the color separation of the cube prism shown in FIG. 3, wherein a shows a conceptual diagram and b shows a spectral characteristic.

When white light 31 is made to enter the cube prism 30 almost perpendicularly to the prism surface, color separation into three primary colors of red, blue and green is performed by the respective selective reflection films. As shown by b, the filter characteristics of each color have a steep characteristic, and the characteristics of color light separation are extremely good. Further, the incident surface, further allows the effective utilization of light by coating the MgF _2, Zr0 _2, etc. multilayer antireflection film. 5A and 5B show an overall configuration diagram of a projection type color display device according to the present invention, wherein a is a front view, b
Is a plan view and C is a side view.

The white light emitted from the light source 40 is recollimated by the condenser lens 41, enters the first cube prism 42, and is separated into three colors of red, blue and green.
The direction of the decomposed color light is bent by the mirror 43,
The light enters the transmission type light valve 44. Light valve 44
Is arranged at a position where an image is formed by the projection lens 46.

Each of the three light valves 44 is red,
The second cube prism 45 performs color light synthesis by additive color mixing so that the respective display images are synthesized on a screen. Projected on the screen.

The driving method of the light valve 44 conforms to the method described in Nikkei Electronics No. 351 (1984) P211.

FIGS. 6A and 6B show the overall configuration of another embodiment of the projection type color display device according to the present invention, wherein a is a front view, b is a plan view, and c is a side view.

The white light emitted from the light source 50 is recollimated by the condenser lens 51, enters the first cube prism 52, and is separated into three colors of red, blue and green. The direction of the decomposed color light is bent by a mirror 53 and is incident on a transmission type light valve 54. The light valve is arranged at a position where an image is formed by the projection lens 56.

The second cube prism 55 combines the transmission of the light valve with a color combining prism.

In the present invention, the first through third light valves corresponding to the first through third color lights, respectively.
An image is formed by the transmission type light valve, and each color light is modulated. Since the transmissive light valve is used as described above, the influence of the reflected light on the light valve surface can be removed from the modulated light, and the image contrast is improved. Further, when an image display panel using the electro-optical effect of liquid crystal is adopted for the light valve, and particularly when an active matrix type is used, contrast: 1:
30th place is easily obtained. Further, if an optical switch element such as PLZT or electrophoresis is used, the device becomes compact because it is a thin light valve. The optical prism combines red, green, and blue image color lights modulated by the light valve. The color light selective reflection film layer of the optical prism is
It is only necessary to synthesize the color light from the light valve, and the performance of limiting the polarization component, which has been required conventionally, is unnecessary.

According to this embodiment, the following effects can be obtained.

(A) Since a transmission type light valve is used, non-modulated light reflected on the surface of the light valve can be removed, so that the contrast is good. In addition, a polarization beam splitter for separating incident light and reflected light Is unnecessary and the optical system can be made compact.

(B) Since each of the three light beams is combined into one light beam, focus adjustment and the like need only be performed on the one light beam, and adjustment for each of the three colors is unnecessary, and adjustment is easy. become.

(C) Since the color light selective reflection layer according to the incident light can be used, any combination of colors can be synthesized by opening and closing each light valve arbitrarily.

(D) By using an optical element in which two types of color light selective reflection films are arranged in a cross shape (cross arrangement) as the color synthesizing means, the two types of color light selective reflection films are formed in a mountain shape. The distance between the light valve and the outlet of the color synthesizing means can be reduced as compared with the arrangement in which the arrangement is made (a chevron arrangement). Therefore, the distance to the optical element to be combined in the subsequent stage of the color display device of the present invention can be shortened, and the degree of freedom in design increases.

(E) In addition, the use of an optical prism (prism type) as the cross-arranged optical element makes it possible to obtain a difference in the refractive index of the medium as compared with the case where mirrors are combined in a cross shape (mirror type). Therefore, the distance between the light valve and the exit of the color synthesizing means can be further reduced.

(F) By disposing a light valve on each outer surface of the optical prism, the optical prism and the
The positional relationship between the color light valves is simplified, and the number of parts is reduced. Therefore, it is possible to easily adjust the optical position shift of the three color light valves.

(G) Since the light transmitted through the light valve enters the optical prism almost perpendicularly to the outer surface of the optical prism by employing the prism system in which the light valve is disposed outside each of the optical prisms, Element (mirror)
Light reflected on the element surface can be reduced as compared with the mirror type which is incident on the surface at an angle of approximately 45 degrees. Therefore, light use efficiency is high and stray light is reduced. In addition, the influence of multiple reflection inside the mirror plate and refraction on the mirror plate surface is eliminated, and the image of the light valve is not deteriorated.

[0030]

As described above, according to the color display device of the present invention, the following remarkable effects can be obtained. (A) As a color synthesizing means for synthesizing the color lights modulated by the three liquid crystal light valves, the right angle portions of the four right angle prisms are made to face each other so as to form a cross shape by the surfaces sandwiching the right angle portions. Since the optical prism in which two different kinds of color light selective reflection layers are arranged in a cross shape along the cross-shaped inner surface is used, the following effects can be obtained. Since the three color lights are combined into one light beam, the focus adjustment needs to be performed only for the one light beam, and the focus adjustment for each of the three colors is unnecessary, and the focus adjustment is simplified. Since the two types of color light selective reflection films are arranged in a cross shape, the distance from the light valve to the projection optical means is shorter than that in which color light is synthesized by a plurality of separated color light selective reflection layer mirrors that do not intersect each other, The device can be downsized. Since the optical prism having a high refractive index is disposed between the projection optical unit and the light valve, the focal position (back focus) of the projection optical unit is shortened, so that the image projected from the projection optical unit is enlarged and projected. Can be.
Therefore, the distance from the light valve to the projection optical means is shortened, so that not only the device can be downsized, but also the enlarged projection can be performed by the small device. If the light valve is arranged at a position far from the projection optical means, the amount of movement in adjusting the alignment between the light valves increases, but the light valve is arranged adjacent to the outside of the optical prism, and the projection optical means is arranged. Since the light valve is arranged at a position that is not farther away, the adjustment amount of the alignment between the light valves can be reduced, and the adjustment can be simplified. (B) In the present invention, in a light source that emits color light modulated by three light valves, a mirror that reflects light from the light emitting unit has a characteristic of transmitting infrared light. In a transmissive liquid crystal light valve that modulates separated color light, light from a light source is transmitted and modulated, so that light components that do not pass through the light valve are converted into heat. The heat in the liquid crystal light valve degrades the characteristics of the liquid crystal, whose characteristics tend to fluctuate in response to a change in temperature, resulting in deterioration of the contrast of the projected image. In particular, in the present invention, since the transmissive liquid crystal light valves are adjacent to the three outsides of the optical prism, the distance between the light valves is short, and the flow of air that exhausts heat due to the presence of the optical prism. Therefore, the liquid crystal light valve has a structure that is easily affected by heat. However, according to the present invention, as described above, the reflection mirror of the light source is provided with infrared transmission characteristics to make it difficult for the infrared component of the light source light, which causes heat generation, to reach the liquid crystal light valve side. The temperature rise of the light valve can be suppressed, and the characteristics of the transmission type liquid crystal light valve can be stabilized.

[Brief description of the drawings]

FIG. 1 is a principle diagram of a projection display device according to the present invention.

FIGS. 2A and 2B are diagrams illustrating a configuration of an illumination system, and FIG. 2B is a diagram illustrating a spectral characteristic of a reflector;

3A and 3B are configuration diagrams of a cube prism, wherein a is a perspective view of a right-angle prism and b is an assembly method diagram of the cube prism.

FIGS. 4A and 4B show color separation cones of a cube prism, a is a conceptual diagram of color separation of a cube prism, and b is a spectral characteristic diagram of color separation of a cube prism.

FIGS. 5A and 5B are overall configuration diagrams of a projection-type color display device of the present invention, wherein a is a front view, b is a plan view, and c is a side view.

6 is a configuration diagram of another embodiment of the projection type color display device of the present invention, wherein a is a front view, b is a plan view, and c is a side view. FIG.

[Explanation of symbols]

 1. Light source 2. Condenser lens 3. Light valve 4. Projection lens 5. Screen 42 First cube prism 43 Mirror 45 Second cube prism

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Tomio Sonehara 3-5-3 Yamato, Suwa-shi, Nagano Inside Suwa Seikosha Co., Ltd. (72) Inventor Shunichi Nakamura 3-5-2-5, Yamato, Suwa-shi, Nagano Inside Suwa Seikosha Co., Ltd. (72) Inventor Shuji Ariga 3-3-5 Yamato, Suwa City, Nagano Prefecture Inside Suwa Seikosha Co., Ltd. (56) References JP-A-50-10019 (JP, A) JP-A-55 -74283 (JP, A) JP-A-58-97983 (JP, A) JP-A-53-4539 (JP, A) JP-B-39-20049 (JP, B1)

Claims (1)

(57) [Claims] A light source and light from the light source are not separated.
Three transmissive liquid crystal lines that respectively modulate three color lights
And the three transmissive liquid crystal light valves.
Color synthesizing means for synthesizing the adjusted color light;
Projection optical means for projecting the combined light.
In the color display device, the color synthesizing unit connects the right-angle portions of the four right-angle prisms to each other.
To form a cross by the surface sandwiching the right angle part
Along the cross-shaped inner surface.
Arrange the colored light selective reflection layers in a cross shape
The three transmission type liquid crystal light valves are composed of an optical prism.
Out of the four outer surfaces of the
The light sources are disposed adjacent to each other , and the light source is disposed on a rear side of the light emitting unit.
A mirror for reflecting the light emitted from the light emitting section.
The mirror has the property of transmitting infrared light,
The light reflected by the three liquid crystal light bars
A color display device characterized by being modulated by a lube .