JPH046542A - Projection type display device and color separation optical device used in the 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 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, sewing, 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 has a liquid crystal panel 6,
．． After passing through the lens 7.8, it enters the projection lens 9.1011. Optical images according to video signals are formed on the liquid crystal panel 6.7.8, and these optical images are projected onto 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 LCD panels become smaller, optical components such as projection lenses also become smaller, so the projector, which consists of the optical system from the lamp to the projection lens, 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 separation tool panel decreases, so green light has lower light utilization efficiency than blue light, and red The light utilization efficiency of green light 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 the light source 1 to increase the light output of the light source 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 from the concave mirror. As the optical path length 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 the transmitted light of the first dichroic mirror is incident, and four plane mirrors, The transmitted light of the second dichroic mirror enters the first plane mirror, the reflected light of the first dichroic mirror is reflected by the second plane mirror and exits, and the light of the second dichroic mirror enters the first plane mirror. The reflected light is reflected by the third plane mirror and emitted, and the reflected light of the first plane mirror is reflected by the fourth plane mirror and emitted, and the colors of the three emitted lights are different from each other. 1st
The optical path length from the dichroic mirror to an arbitrary plane perpendicular to the central output optical axis is approximately 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. and 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. The light is separated into primary color lights, each of the primary color lights is incident on 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. , four 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 enters the second plane mirror, the reflected light of the second dichroic mirror enters the third plane mirror, and the reflected light of the first dichroic mirror enters the third plane mirror; The reflected light from the first plane mirror is incident on the fourth plane mirror, and the reflected light from the second, third and fourth plane mirrors is incident on each of the corresponding light valves. The optical image formed by the light valve is enlarged and projected onto the screen by the projection lens, and the optical images of the three light valves are substantially on the same plane, and the distance from the light source to the light valve is The optical path length of each color is set such that the color unevenness of the projected image is minimized.

Effects According to the above configuration, 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, so that the distance from the light source to the light valve can be adjusted. The optical path length 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, thereby changing the illuminance distribution on the light valve. 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-reflecting dichroic mirror, 26 is a green-reflecting dichroic mirror, 27.28.
29.30 is a plane mirror, 38.39.40 is a liquid crystal panel, and 41.42.43 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 reflective dichroic mirror 25, a green reflective dichroic mirror 26, and four flat mirrors 27.
．． 2B, consisting of 29.30. A blue reflective dichroic mirror 25 is arranged on the incident optical axis 31 in order from the light source 21 side.
, a green reflecting dichroic mirror 26, and a plane mirror 27 are arranged. When the light emitted from the light source 21 enters the color separation optical system, the two dichroic mirrors 25 and 26 and the plane mirror 27 bend the blue, green and red colored lights in the horizontal direction and take them out. The light is reflected by mirrors 28, 29, and 30 and exits the color separation optical system. The output optical axes 32, 33, 34 of each color are on the same plane, are parallel to each other, and are perpendicular to the input optical axis 31 in terms of twist.

The three colored lights emitted from the color separation optical system are reflected by the corresponding plane mirrors 35, 36, and 37, and are displayed on the liquid crystal panels 38, 3.
9.40 and enters the projection lens 41.42.43. The liquid crystal panels 38, 39, 40 form optical images as changes in transmittance in response to video signals, and the optical images of each color are enlarged and projected onto the screen by projection lenses 41, 42, 43. The optical images formed on the three liquid crystal panels 3B, 39.40 have the same dimensions and are on the same plane.

The optical axes 44.45.46 of the projection lenses 41.42.43 are parallel to each other, and the optical images and screens of the liquid crystal panels 3B, 39.40 are perpendicular to the optical axes 44.45.46. Further, the distortion aberration of the projection lenses 41, 42, 43 is very small, and the chromatic aberration is also very small. Therefore, the sizes of the projected images of each color on the screen are the same.

In the configuration shown in FIG. 1, the incident optical axis 31 of the color separation optical system
A plane mirror 2B, 29.30 arranged in the optical path of each color light after branching from the light source 21 to each liquid crystal panel 3
B. Since there is a degree of freedom in which the optical path length can be adjusted up to 39.40°, the optical path length from the light source 21 to the liquid crystal panel 38.39°40 can be made equal for all three colors. As a result, the light utilization efficiency and the illuminance distribution on the liquid crystal panels 3B and 39.degree. 40 are almost the same for all three colors, so that the projected image can have high brightness and good color uniformity. Also,
When using a concave mirror for the light source 21, as described above, the light source 2
It is necessary to set the optical path length from 1 to the liquid crystal panel 38.39°40 to a predetermined distance, but this can be achieved with the configuration shown in Figure 1, and as a result, the color uniformity of the projected image is improved. can do.

Note that even if the optical path lengths from the light source 21 to the liquid crystal panels 38, 39, and 40 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 3B, 39.40 is appropriately shifted to minimize 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 31, 33, and 34 are made parallel to each other, or if the output optical axes 32, 34 at both ends are made symmetrical about the central output optical axis 33, 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 the transmission screen are housed in one cabinet. A transmissive screen 48 is arranged at the upper front of the cabinet 47, and projection lenses 41, 42, .
A projector 49 consisting of up to 43 optical systems is piped, and a first mirror 50 and a second mirror 51 are arranged at the lower front side and the upper part, respectively. Three projection lenses 41.4 of projector 49
The light emitted from 2.43 reaches the screen 48 after its optical path is bent by the first mirror 50 and the second mirror 51.

To make the set compact, use a projection lens of 41°42
, 43 to the center of the screen 48 (projector #) and to make the projector 49 more compact. To shorten the projection distance, the projection lenses 41, 42, and 43 may be wide-angle lenses. In order to make the projector 49 compact, as shown in FIG.
The optical path in the middle is bent by plane mirrors 35, 36, 37 so that the incident optical axis 31 is above the projection lens 4L 42, 43, and the three output optical axes 3 of the color separation optical system are
2.33.34 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 49 can be placed without creating wasted space at the rear of the lower part of the cabinet 47.
It is also very compact.

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

In the configuration shown in FIG.
．． 43, and can be configured as shown in FIG. It is also possible to arrange the plane mirrors 35, 36, 37 inside the projection lens to create a configuration as shown in FIG. Each projection lens shown in FIG. 5 includes a main lens 52, 53, 54, a lens 55, 56, 57 placed immediately after the liquid crystal panel 38, 39° 40, a plane mirror 5B placed between them, It consists of 59.60.

The configurations shown in FIGS. 4 and 5 can be disposed at the rear of the lower part of the cabinet 47 without wasting space, and the cabinet 47 can also be made compact, as in the case shown in FIG. 3.

In the configurations shown in FIGS. 1, 4, and 5, if the plane mirror 28 is a blue-reflecting gicchroic mirror, the color purity of the blue light incident on the liquid crystal panel 38 is improved, and the plane mirror 29 By using a green reflective dichroic mirror, the color purity of the green light incident on the liquid crystal panel 39 will be improved. Moreover, if one of the plane mirrors 27 and 30 is a red-reflecting gicchroic mirror, the color purity of the red light incident on the liquid crystal panel 40 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 is Can be made wider.

In the configuration shown in FIG. 1, FIG. 4, and FIG. 5, a positive lens is placed as a field lens just before the liquid crystal panel 38, 39, 40, and the light beams incident on the periphery of the liquid crystal panel 38, 39, 40 are By concentrating the light on the pupil of the projection lens 41, 42, 43, 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 35, 36, and 37 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.
Although the colors are blue, green, and red in order from the first side, 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. Furthermore, although an example is shown in which a liquid crystal panel is used as the light valve, any material that can form an optical image as a change in optical characteristics in response to a video signal, such as an electro-optic crystal, can be used as the 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.
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... Flat mirror, 38.39.40... Liquid crystal panel,
41.42.43...Projection lens. Name of agent: Patent attorney Shigetaka Awano Daotsu 43 NIL's Diagram Diagram Diagram Atsushi Diagram

Claims (18)

[Claims] (1) A first dichroic mirror, a second dichroic mirror into which the light transmitted from the first dichroic mirror is incident, and four plane mirrors, wherein the light transmitted from the second dichroic mirror is transmitted from the first dichroic mirror. The reflected light of the first dichroic mirror is reflected by the second plane mirror and exits, and the reflected light of the second dichroic mirror is reflected by the third plane mirror. The reflected light of the first plane mirror is reflected by the fourth plane mirror and output, and the colors of the three output lights are different from each other, and the light is perpendicular to the central output optical axis from the first dichroic mirror. A color separation optical device in which the optical path length to an arbitrary plane 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 first or 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 first or fourth plane mirror is a dichroic mirror. (7) a light source that emits light containing each color component of the three primary colors; and a 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 (6); 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. (8) a light source that emits light containing each color component of the three primary colors; and a color separation means that separates the light emitted from the light source into the three primary colors;
The color separation means is a color separation optical device according to any one of claims (1) to (6), comprising: one light valve, three projection lenses, a transmission screen, and a cabinet. 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 transmitted to the corresponding light valve. 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. Projection type display device. (9) A projection type display device according to claim (7) or claim (8), wherein a plane mirror is disposed between the color separation means and each light valve. (10) Claim (7) or Claim (8), wherein a plane mirror is arranged between each light valve and the projection lens.
The projection type display device described above. (11) The projection type display device according to claim (7) or claim (8), wherein the projection lens has a built-in plane mirror. (12) 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, four 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 enters the second plane mirror, the reflected light of the second dichroic mirror enters the third plane mirror, and the reflected light of the first plane mirror enters the second plane mirror. The reflected light enters the fourth plane mirror, and the reflected light enters the second and third plane mirrors.
The reflected light from the fourth plane mirror is incident on each of the corresponding light valves, and the optical image formed on each of the light valves is enlarged and projected onto the screen by the projection lens. . A projection type display device in which each optical image of the three light valves is 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 of the projected image is minimized. (13) The projection type display device according to claim (12), wherein the output optical axes of the second, third, and fourth plane mirrors are substantially on the same plane. (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, four 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 incident on the second plane mirror, and the reflected light of the first dichroic mirror is incident on the second plane mirror.
The reflected light of the dichroic mirror is incident on the third plane mirror, and the reflected light of the first plane mirror is incident on the fourth plane mirror.
The light reflected from the second, third and fourth plane mirrors enters the corresponding light valve, and the optical image formed on each light valve is projected by the projection lens into the light reflected by the second, third and fourth plane mirrors. The optical images of the three light valves are projected on a screen in an enlarged manner, and each optical image of the three light valves is on substantially the same plane, and the optical path length of each color from the light source to the light valve is calculated based on the color unevenness of the projected image. 2. A projection type display device in which an optical system from the light source to the screen is housed in the cabinet so that the amount of light is minimized. (15) The projection type display device according to claim (14), wherein the output optical axes of the second, third, and fourth plane mirrors are substantially on the same plane. (16) The projection type display according to any one of claims (12) to (15), wherein a plane mirror is arranged between the second, third, and fourth plane mirrors and each corresponding light valve. Device. (17) The projection display device according to any one of claims (12) to (15), wherein a plane mirror is disposed between each light valve and each corresponding projection lens. (18) The projection display device according to any one of claims (12) to (15), wherein the projection lens has a built-in plane mirror.