JPH046543A - Projection type display device and optical color separation device used for the same device - Google Patents

Abstract

PURPOSE:To make a projected image have high brightness and also to make the uniformity of the color in a good condition by making the length of optical paths of three colors from a light source to each liquid crystal panel the same. CONSTITUTION:Plane mirrors 28 - 31 arranged on the optical path of each color light after branching from an incident light axis 32 in an optical color separation system are provided with the degree of freedom for adjusting the length of the optical paths from the light source 21 to the respective liquid crystal panels 39 - 41. Then, the length of the optical paths of the three colors from the light source 21 to the liquid crystal panels 39 - 41 can be made equal. Since light using efficiency and the illuminance distribution on the liquid crystal panels 39 - 41 are made nearly the same in the three colors, the projected image having high brightness can be obtained, and the uniformity of the color can be made in a good condition.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a projection type display device that irradiates an optical image formed on a light valve with light and projects the optical image in an enlarged manner onto a screen using a projection lens, and is used for the device. This invention relates to a color separation optical device.

Conventional technology In order to obtain large-screen images, the conventional method is to form an optical image on a light valve according to the video signal, irradiate the optical image with light, and enlarge and project the optical image onto a screen using a projection lens. well known.

Recently, projection-type display devices that use three liquid crystal panels for red, green, and blue as light valves have been attracting attention (for example, SID 86 Digest, P. 37
5). Furthermore, a projection-type display device has been proposed in which the screen is a transmissive type and all optical systems are housed in a cabinet, making the entire set extremely compact (Television Society Technical Report, CE"89- 17,
P, 55. October 1989).

A conventional example of the basic configuration of the optical system of this rear type projection display device is shown in FIG. The light source 1 is composed of a lamp, a condensing lens, a concave mirror, and a heat absorption filter, and emits nearly parallel light containing color components of three primary colors. The light emitted from light source 1 is
Blue, green, and red colored lights are extracted in a direction perpendicular to the optical axis 5 of the light source 1 by a blue reflecting dichroic mirror 2, a green reflecting dichroic mirror 3, and a red reflecting dichroic mirror 4 arranged in parallel. Each color light is displayed on the LCD panel 6.
After passing through the lens 7.8, it enters the projection lens 9.1011. Optical images according to the video signals are formed on the liquid crystal panel 6.7.8, and these optical images are transmitted to the corresponding projection lens 9.
10.11, the image is enlarged and projected onto the screen.

A projection display device like the one shown in Figure 6 can increase the light output by increasing the light source, and increase the resolution of the projected image by increasing the number of pixels on the LCD panel. By using a lamp, a projection display device with high resolution and large light output can be realized. Therefore, even if the liquid crystal panel is made smaller, it is possible to achieve both brightness and resolution.

As liquid crystal panels become smaller, optical components such as projection lenses also become smaller, so the optical components from the lamp to the projection lens become smaller.
The projector that consists of the system becomes smaller, and in the case of the rear type, the set also becomes very compact.

Problems to be Solved by the Invention In the configuration shown in FIG. 6, from the light source 1 to each liquid crystal panel 6.
The optical path length up to 7.8 differs depending on each color of red, green, and blue light. Generally, the longer the optical path of the light emitted from the light source 1, the more the light spreads, and the illuminance on the liquid boundary panel decreases, so green light has lower light utilization efficiency than blue light, and red light Light usage efficiency is lower than that of green light. When considering the white balance of a projected image, it is necessary to insert attenuation filters into the blue and green optical paths, for example, to ensure an optimal red, green, and blue illuminance ratio. Therefore, the configuration shown in FIG. 6 has a problem in that the light utilization efficiency of the entire device is low and the light output is small.

It is also possible to use a concave mirror for light source 1 to increase the light output of light #1, but when using a concave mirror, it is common to form the image of the lamp light emitter near the liquid crystal panel, and the concave mirror As the optical path length from the liquid crystal panel to the liquid crystal panel deviates from a predetermined distance, the illuminance distribution on the liquid crystal panel 6.7.8 changes greatly. In the case of the configuration shown in FIG.
Since the optical path lengths from to each liquid crystal panel 6, 7, 8 are different for the three colors, the illuminance distribution of the projected image is different for the three colors, making it difficult to ensure color uniformity of the projected image.

The present invention has been made in view of the above, and is a projection type display device in which the optical path length from the light source to each liquid crystal panel is the same for all three colors, and as a result, the projected image is of high brightness and has good color uniformity. The present invention also aims to provide a color separation optical device for use in the device.

Means for Solving the Problems A color separation optical device of the present invention includes a first dichroic mirror, a second dichroic mirror into which light transmitted from the first dichroic mirror is incident, and five plane mirrors. , the transmitted light of the second dichroic mirror enters the first plane mirror, the reflected light of the first dichroic mirror is sequentially reflected by the second and third plane mirrors and exits, The reflected light from the second dichroic mirror is reflected by the fourth plane mirror and emitted, and the reflected light from the first plane mirror is reflected by the fifth plane mirror and emitted, and the three colors of the emitted light are are different from each other, and the optical path lengths from the first dichroic mirror to an arbitrary plane perpendicular to the central output optical axis are substantially the same for the three colored lights.

Further, the projection display device of the present invention includes a light source that emits light containing each color component of three primary colors, a color separation means that separates the light emitted from the light source into the three primary colors, three light valves, and three light valves. a projection lens, the color separation means is the color separation optical device described above, each optical image of the three light valves is on substantially the same plane, and the light emitted from the light source is divided into three by the color separation means. Each of the primary color lights enters the corresponding light valve, and the optical image formed on the light valve is enlarged and projected onto the screen by the projection lens.

Another projection type display device of the present invention includes a light source that emits light containing each of three primary color components, a first dichroic mirror, and a second dichroic mirror into which light transmitted from the first dichroic mirror enters. , five plane mirrors,
It is equipped with three light valves and three projection lenses, and the light emitted from the light source is separated into three primary color lights by the first and second dichroic mirrors, and the transmitted light of the second dichroic mirror is divided into three primary color lights. The reflected light of the first dichroic mirror is reflected by the second plane mirror and then enters the third plane mirror, and the reflected light of the second dichroic mirror is reflected by the second plane mirror. The reflected light from the first plane mirror is incident on the fourth plane mirror, and the reflected light from the first plane mirror is incident on the fifth plane mirror. The reflected light from the fourth and fifth plane mirrors enters the corresponding light valves, and the optical images formed on the light valves are enlarged and projected onto the screen by the projection lens. The optical images of the three light valves are located on substantially the same plane, and the optical path length of each color from the light source to the light valve is set such that color unevenness in the projected image is minimized.

According to the above structure, at least two light reflecting means are used in the optical path of each color of the color separation optical device, and the optical path length between the two light reflecting means can be adjusted. The optical path length to the bulb can be made the same for all three colors. As a result, the light utilization efficiency and the illuminance distribution on the light valve can be made the same for all three colors, and the projected image can have high brightness and good color uniformity.

Furthermore, according to the above configuration, by adjusting the optical path length between the two light reflecting means, the optical path length from the light source to the light valve can be shifted, and in addition, the illuminance distribution on the light valve can be changed. Therefore, the illuminance distribution on the light valve can be made the same for all three colors.

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

FIG. 1 shows the configuration of an embodiment of the projection type display device of the present invention, in which 21 is a light source, 25 is a blue reflection guichroic mirror, 26 is a green reflection guichroic mirror, 27.2B,
29.30.31 is a plane mirror, 39.40°41 is a liquid crystal panel, and 42.43.44 is a projection lens.

As shown in FIG. 2, the light source 21 is composed of a lamp 22, a concave mirror 23, and an interference filter 24, and the lamp 22 reflects light containing components of each of the three primary colors. The light emitted from the lamp 22 is reflected by the concave mirror 23 and converted into nearly parallel light,
The infrared rays and ultraviolet rays are removed by the interference filter 24 and emitted, and then enter the color separation optical system.

The color separation optical system includes a blue reflection dichroic mirror 25, a green reflection dichroic mirror 26.5 plane mirrors 27
．． Consists of 28.29.30.31. Incident optical axis 32
Above, a blue reflective dichroic mirror 25, a green reflective dichroic mirror 26, and a plane mirror 27 are arranged in order from the light source 21o. When the light emitted from the light source 21 enters the color separation optical system, two dichroic mirrors 25.
26 and a plane mirror 27, the blue, green and red colored lights are bent in the horizontal direction and taken out.The blue light is sequentially reflected by two plane mirrors 28 and 29, and the green and red lights are reflected in the corresponding plane. The light is reflected by mirrors 30 and 31 and exits the color separation optical system. The output optical axis 33, 34, 35 of each color is
They are on the same plane, parallel to each other, and both are at right angles to the incident optical axis 32 and the torsion.

The three colored lights emitted from the color separation optical system are reflected by the corresponding plane mirrors 36, 37, and 38, and are displayed on the liquid crystal panels 39, 4.
0.41 and enters the projection lens 42, 43, 44. The liquid crystal panel 39, 40, 41 forms an optical image as a change in transmittance according to the video signal, and the optical image of each color is enlarged and projected onto the screen by the projection lens 42, 43, 44. The optical images formed on the three liquid crystal panels 39, 40, and 41 have the same dimensions and are on the same plane. The optical axes 45.46.47 of the projection lenses 42.43.44 are parallel to each other, and the optical image of the liquid crystal panel 39.40.41 and the screen are perpendicular to the optical axes 45.46.47.

Further, the distortion aberration of the projection lenses 42, 43, 44 is very small, and the chromatic aberration is also very small, so the size of the projected image of each color on the screen is the same.

In the configuration shown in FIG. 1, the incident optical axis 32 of the color separation optical system
The plane mirrors 2B, 29.30.31 arranged in the optical path of each color light after branching from the light source 21 have a degree of freedom to adjust the optical path length from the light source 21 to each liquid crystal panel 39.40.41. From LCD panel 39°40,4
The optical path length up to 1 can be made equal for all three colors. As a result, the light utilization efficiency and the illuminance distribution on the liquid crystal panels 39, 40, 41 are almost the same for all three colors, so that the projected image can have high brightness and good color uniformity. Furthermore, when a concave mirror is used as the light source 21, as mentioned above, it is necessary to set the optical path length from the second light source to the liquid crystal panels 39, 40, 41 to a predetermined distance, but in the configuration shown in FIG. As a result, the color uniformity of the projected image can be improved.

Note that even if the optical path lengths from the light source 21 to the liquid crystal panels 39, 40, and 41 are made equal for all three colors, color unevenness may occur in the projected image. This occurs when the color unevenness of the lamp light emitter is large, but in this case, the optical path length from the light source 21 to each liquid crystal panel 39, 40, 41 is appropriately shifted to minimize the color unevenness. It's good to do that.

Although the color separation optical system shown in Figure 1 appears to have a complicated structure,
If the three output optical axes 33, 34, and 35 are made parallel to each other, or if the output optical axes 33.35 at both ends are made symmetrical about the central output optical axis 34, the components used in the color separation optical system can be compared. It has a relatively simple structure.

FIG. 3 shows a configuration in which the optical system shown in FIG. 1 and a transmission screen are housed in one cabinet.A transmission screen 49 is placed at the upper front of the cabinet 48, and a light source 21 is placed at the rear of the lower part. From the projection lens 42.43.
A projector 50 consisting of up to 44 optical systems is arranged, and a first mirror 51 and a second mirror 52 are arranged at the lower front side and the upper part, respectively. Three projection lenses 42.4 of projector 5o
The light emitted from 3.44 reaches the screen 49 after its optical path is bent by the first mirror 51 and the second mirror 52.

To make the set compact, use a projection lens of 42°43
, 44 to the center of the screen 49 (projection distance) and to make the projector 5o compact. To shorten the projection distance, the projection lenses 42, 43, and 44 may be wide-angle lenses. In order to make the projector 50 compact, as shown in FIG.
The optical path in the middle is bent by plane mirrors 36, 37, 38 so that the incident optical axis 32 is above the projection lenses 42, 43, 44, and the three output optical axes 3 of the color separation optical system are
3.34.35 should be made parallel to each other, and each optical component should be placed close to each other within a range where the effective light beam is not blocked. In this way, the projector 50 can be placed without creating wasted space at the rear of the lower part of the cabinet 48.
It is also very compact.

Next, other embodiments of the present invention will be described.

In the configuration shown in FIG. 1, plane mirrors 36, 37, 38 are connected to liquid crystal panels 39, 40, 41, projection lenses 42, 43, .
44, and can be configured as shown in FIG. It is also possible to arrange the plane mirrors 36, 37, 38 inside the projection lens to create a configuration as shown in FIG. Each projection lens shown in FIG. 5 consists of a main lens 53, 54, 55, a lens 56, 57, 58 placed immediately after the liquid crystal panel 39, 40° 41, and a plane mirror 59. It consists of 60.61.

Similar to the case shown in FIG. 3, the configuration shown in FIGS. 4 and 5 can be arranged without creating wasted space at the lower rear of the cabinet 48.
It also becomes more compact.

In the configurations shown in FIGS. 1, 4, and 5, if one of the plane mirrors 28 and 29 is a blue-reflecting dichroic mirror, the color purity of the blue light incident on the liquid crystal panel 39 is improved, and the plane If the mirror 30 is a green reflecting dichroic mirror, the color purity of the green light incident on the liquid crystal panel 40 will be improved. Moreover, if one of the plane mirrors 27 and 31 is a red-reflecting dichroic mirror, the color purity of the red light incident on the liquid crystal panel 41 will be improved. In this way, by using a plane mirror whose reflectance in a given wavelength band is higher than that in other wavelength bands, components in unnecessary wavelength bands are removed, so in any case, the color reproduction range of the projected image can be widened. can do.

In the configuration shown in FIGS. 1, 4, and 5, a positive lens is placed as a field lens just before the liquid crystal panel 39.40.41, and the light beams incident on the peripheral part of the liquid crystal panel 39.40.41 By concentrating the light on the pupil of the projection lens 42, 43, 44, the periphery of the projected image can be brightened.

The color separation optical device of the present invention is shown in FIGS. 1, 4, and 5.
The configuration shown in the figure can be applied to a projection display device in which the projector and screen are separated. Furthermore, if the depth of the projector does not need to be increased, the plane mirrors 36, 37, and 38 may be omitted from the configuration shown in FIG.

In the above embodiment, the color of the emitted light from the color separation optical system is determined by the light source 2.
Starting from 1o, the colors are blue, green, and red, but there is no particular restriction on the order of the colors. In other words, if the light distribution characteristics of the screen cause noticeable changes in chromaticity when changing the viewing angle of the projected image, it is better to change the center color to green. Also,
Although we showed an example of using a liquid crystal panel as a light valve,
Anything that can form an optical image by changing its optical properties in response to a video signal, such as an electro-optic crystal, can be used as a light valve.

Effects of the Invention As explained above, according to the present invention, since the color separation means has the degree of freedom of adjusting the optical path length from the light source to each light valve, this optical path length can be adjusted to blue.

By making the three colors green and red the same, or by shifting the optical path length between the three colors, the illuminance distribution on the light valve can be made uniform for the three colors, and thereby,
It can improve the brightness and color uniformity of the projected image,
It has amazing industrial effects.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing the configuration of a projection type display device of the present invention;
2 is a schematic configuration diagram showing the configuration of a light source, FIG. 3 is a sectional view showing the configuration inside the cabinet, FIGS. 4 and 5 are perspective views showing the configuration of another embodiment of the present invention, and FIG. The figure is a schematic configuration diagram showing the basic configuration of an optical system of a conventional projection display device. 21... Light source, 25.26... Guicroic mirror 27, 28.29.30.31...
...Flat mirror, 39.40.41...Liquid crystal panel, 42.43.44...Projection lens. Agent's name: Patent attorney Shigetaka Awano Haka 1 Me Zetsuzu 40 Sei 1 Shi C Ne 9 42.47.44 Copy of the first page of the book.

Claims (20)

[Claims] (1) A first dichroic mirror, a second dichroic mirror into which the light transmitted from the first dichroic mirror is incident, and five plane mirrors, wherein the light transmitted from the second dichroic mirror is transmitted from the first dichroic mirror. The reflected light from the first dichroic mirror is sequentially reflected by the second and third plane mirrors and exits, and the reflected light from the second dichroic mirror is incident on the fourth plane mirror. The reflected light from the first plane mirror is reflected by the fifth plane mirror and is emitted. The three emitted lights have different colors, and the light emitted from the first dichroic mirror is emitted from the central dichroic mirror. A color separation optical device in which the optical path length to an arbitrary plane perpendicular to the output optical axis is approximately the same for three colored lights. (2) Claim (1) that the three output optical axes are substantially on the same plane.
Color separation optical device as described. (3) The color separation optical device according to claim 1, wherein the second or third plane mirror has a higher reflectance in a predetermined wavelength band than in other wavelength bands. (4) The color separation optical device according to claim (3), wherein the second or third plane mirror is a dichroic mirror. (5) The color separation optical device according to claim 1, wherein the fourth plane mirror has a higher reflectance in a predetermined wavelength band than in other wavelength bands. (6) The color separation optical device according to claim (5), wherein the fourth plane mirror is a dichroic mirror. (7) The color separation optical device according to (1), wherein the first or fifth plane mirror has a higher reflectance in a predetermined wavelength band than in other wavelength bands. (8) The color separation optical device according to claim (7), wherein the first or fifth plane mirror is a dichroic mirror. (9) a light source that emits light containing color components of each of the three primary colors; and color separation means that separates the light emitted from the light source into the three primary colors;
one light valve and three projection lenses, the color separation means is constituted by the color separation optical device according to any one of claims (1) to (8); Each optical image is on substantially the same plane, the light emitted from the light source is separated into three primary color lights by the color separation means, and each of the primary color lights is incident on the corresponding light valve,
A projection type display device in which an optical image formed on the light valve is enlarged and projected onto a screen by the projection lens. (10) a light source that emits light containing each of the three primary color components;
color separation means for separating the light emitted from the light source into three primary colors;
A color separation optical device according to any one of claims (1) to (8), comprising three light valves, three projection lenses, a transmission screen, and a cabinet, wherein the color separation means The optical images of the three light valves are substantially on the same plane, the light emitted from the light source is separated into three primary color lights by the color separation means, and each of the primary color lights is separated from the corresponding light valve. and an optical image formed on the light valve is enlarged and projected onto the screen by the projection lens, and an optical system from the light source to the screen is housed in the cabinet. A projection display device. (11) Claim (9) or claim (10) wherein a plane mirror is disposed between the color separation means and each light valve.
) projection type display device. (12) Claim (9) or claim (10) wherein a plane mirror is arranged between each light valve and the projection lens.
)) The projection type display device described above. (13) The projection type display device according to claim (9) or claim (10), wherein the projection lens has a built-in plane mirror. (14) a light source that emits light containing each of the three primary color components;
a first dichroic mirror, a second dichroic mirror into which the transmitted light of the first dichroic mirror is incident, five plane mirrors, and three light valves;
The light emitted from the light source is separated into three primary color lights by the first and second dichroic mirrors, and the light transmitted by the second dichroic mirror is transmitted to the first plane mirror. The reflected light of the first dichroic mirror is reflected by the second plane mirror, and then enters the third plane mirror,
The reflected light of the dichroic mirror is incident on the fourth plane mirror, and the reflected light of the first plane mirror is incident on the fifth plane mirror.
The reflected light from the third, fourth, and fifth plane mirrors enters the corresponding light valves, and the optical images formed on the light valves are projected onto the screen by the projection lens. The optical images of the three light valves are on substantially the same plane, and the optical path length of each color from the light source to the light valve is adjusted so that the color unevenness of the projected image is A projection display device designed to minimize (15) The projection type display device according to (14), wherein the output optical axes of the third, fourth, and fifth plane mirrors are substantially on the same plane. (16) a light source that emits light containing each of the three primary color components;
a first dichroic mirror, a second dichroic mirror into which the transmitted light of the first dichroic mirror is incident, five plane mirrors, and three light valves;
It is equipped with three projection lenses, a transmission type screen, and a cabinet, and the light emitted from the light source is transmitted to the first and second light sources.
The light transmitted through the second dichroic mirror is separated into three primary color lights by the dichroic mirror, and the light transmitted through the second dichroic mirror is divided into three primary color lights.
The reflected light of the first dichroic mirror is reflected by the second plane mirror and then enters the third plane mirror, and the reflected light of the second dichroic mirror is reflected by the second plane mirror. The reflected light of the first plane mirror is incident on the fifth plane mirror, and the reflected light of the third, fourth and fifth plane mirrors is reflected by each of the corresponding light valves. and an optical image formed on each of the light valves is enlarged and projected onto the screen by the projection lens, and each optical image of the three light valves is on substantially the same plane. , the optical path length of each color from the light source to the light valve is set such that color unevenness in the projected image is minimized;
A projection type display device, wherein an optical system from the light source to the screen is housed in the cabinet. (17) The projection type display device according to claim (16), wherein the output optical axes of the third, fourth, and fifth plane mirrors are substantially on the same plane. (18) The projection display device according to any one of claims (14) to (17), wherein a plane mirror is arranged between each of the third, fourth, and fifth plane mirrors and the corresponding light valves. . (19) The projection type display device according to any one of claims o to (17), wherein a plane mirror is disposed between each light valve and each corresponding projection lens. (20) The projection display device according to any one of claims (14) to (17), wherein the projection lens has a built-in plane mirror.