JPH09329761A - Projection type display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the color irregularity of a projected picture from occurring caused by structure even when a cross dichroic mirror or the like is used as a color separation optical system. SOLUTION: Light beams emitted from a light source 1 are separated to the first and the second polarized light beams by a polarizing beam splitter 3. The color separation of the first polarized light beams is executed by the cross dichroic mirror 5. The light beams of every color obtained by the above- mentioned color separation are modulated by light valves 8R, 8G and 8B and color-synthesized by a cross dichroic prism 9. The second polarized light is modulated by a luminance signal by a light valve 13, polarized and synthesized with the color synthesized light beams by a polarizing beam splitter 14 and projected by a projection lens 107. The splitter 3 and the mirror 5 are arranged between a front-group illumination lens 101 and a rear-group illumination lens 102R, 102G, 102B constituting a relay optical system for illumination having telecentric property with respect to a front side and a back side.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a projection type display device for projecting an image formed on a liquid crystal light valve onto a screen, and more particularly, to a method for displaying images formed on a plurality of color component liquid crystal light valves on a plurality of screens. The present invention relates to a projection display device that illuminates with illumination light of a color component, combines these images, and projects the combined image with a projection optical system.

[0002]

2. Description of the Related Art It has already been known that white light from a light source is split into P-polarized light and S-polarized light by a polarizing beam splitter (PBS), and both polarized lights are incident on a liquid crystal panel to improve the brightness of the projected light. Are known. For example, JP-A-4-185
FIG. 1 of Japanese Patent Application Publication No. 54-54204 discloses a configuration of a liquid crystal projector as a basic principle, and FIG. 2 of the same application discloses a configuration of a full-color projector using the same principle. The configuration of this full-color projector will be briefly described. In this projector, the light source light emitted from the light source is PB
The light is separated into P-polarized light transmitted by S (which is S-polarized light in the publication, but an error of P-polarized light) and S-polarized light reflected by the PBS. Both the separated P-polarized light and S-polarized light are separated into red light (R light), green light (G light) and blue light (B light) by a dichroic mirror. Each of the color-separated color lights is modulated by a transmission-type liquid crystal panel, and the incident-side polarizing plate transmits P-polarized light when the polarizing plate on the output side of the panel is arranged orthogonal to the polarizing plate on the incident side. When the incident side polarizer is configured to transmit S-polarized light, the light is converted into P-polarized light and emitted. Each polarized light emitted from the liquid crystal panel is combined for each polarized light by a combining dichroic mirror, further combined by a combining polarizing beam splitter, and projected by a projection lens.

However, in this method, the projected image is certainly brighter than the method of discarding one of the polarized lights separated by the separating polarizing beam splitter. In addition to the necessity of the same number of dichroic mirrors as that of one polarized light, in order to improve the resolution, six expensive high-resolution liquid crystal panels must be prepared.

As another conventional example, a projection type display device using three light valves for color signals and one light valve for luminance signals is disclosed in Japanese Patent Laid-Open Publication No. Hei 3-296030. The embodiment shown in FIG. 1 of the same publication is shown in FIG. 3 as a conventional example. According to the publication, the light source light from the light source 201 is polarized and separated by the polarization beam splitter 202,
One of the transmitted P-polarized lights is converted to a dichroic mirror 2
The color separation optical system composed of the color separation optical systems 10 and 215 separates the color-separated R, G, and B lights into light valves 20 for respective color signals.
6,207,208, and each light valve 20
The light is modulated by the color signals 6, 207 and 208 and emitted from the light valves 206, 207 and 208. On the other hand, the other S-polarized light is supplied to the light valve 20 for luminance signal.
4 and is modulated by a luminance signal and emitted from the luminance signal light valve 204 as modulated light. The dichroic mirrors 213 and 21 for color synthesis use the color signal modulated light.
4 is a device that performs color synthesis at 4, and combines the color-combined light and the luminance signal modulated light with the combining polarizing beam splitter 209, and then projects the combined light with the projection lens 219. In addition,
In FIG. 3, 203, 211 and 218 are mirrors, 205 is a terminal for supplying a luminance signal Y, 212, 216 and 217 are terminals for supplying color difference signals R-Y, G-Y and B-Y as color signals, respectively. Is. According to this device, the number of light valves to be used can be reduced to four, and high luminance can be achieved because the modulated light by the luminance signal is superimposed on the modulated light by the chrominance signal. By setting the resolution, a high-resolution projected image can be obtained.

[0005]

In order to reduce the cost by using a small number of liquid crystal light valves and to obtain a projected image with high brightness and high resolution, the polarization splitting optical system is used in the same manner as the conventional projection type display device. It is conceivable to configure a projection display device with a system, a color separation optical system, a plurality of color signal light valves, a color combining optical system, a luminance signal light valve, a polarization combining optical system, and a projection optical system. In this case, it is conceivable to adopt a cross dichroic mirror or the like as the color separation optical system. However, since the cross dichroic mirror has a structure in which two dichroic mirrors are arranged in an X shape, the crossing portion of the two dichroic mirrors affects the projected image, resulting in color unevenness.

Further, the conventional example has the following problems. That is, in the dichroic mirror used as the color synthesizing optical system or the multilayer film filter used in the dichroic prism, the spectral characteristics thereof have angle dependence. Therefore, if the angle of incidence of the chief ray determined by the aperture stop of the projection lens with respect to the multilayer filter varies depending on the location, the spectral characteristics of the multilayer filter differ for each principal ray, and color shading occurs on the screen. There was a problem. In addition, there is angular dependence in the performance of the polarization beam splitter used as the polarization combining optical system, and if the incident angle of the chief ray with respect to the polarization splitting surface of the polarization beam splitter differs depending on the location, this causes Contrast unevenness also occurs. Further, even in the liquid crystal light valve, since the performance depends on the angle, if the incident angle of the chief ray with respect to the light valve varies depending on the place, uneven contrast of the projected image occurs due to this.

The present invention has been made in view of the above circumstances, and it is possible to reduce the cost by using a small number of liquid crystal light valves and obtain a projected image with high brightness and high resolution. An object of the present invention is to provide a projection display device capable of preventing color unevenness of a projected image due to its structure even when a cross dichroic mirror or the like is used as a color separation optical system.

Another object of the present invention is to provide a projection type display device capable of obtaining a projected image with less color shading.

Another object of the present invention is to provide a projection type display device capable of obtaining a good projected image without uneven contrast.

[0010]

In order to solve the above-mentioned problems, a projection display according to a first aspect of the present invention comprises: a light-emitting element for separating a light from a light source into a first polarized light and a second polarized light; A polarization separation optical system, a color separation optical system that performs color separation of the first polarized light separated by the polarization separation optical system into a plurality of color lights, and the plurality of colors separated by the color separation optical system. A plurality of color signal light valves that respectively modulate color light based on a predetermined color signal; and a light beam that is modulated by the plurality of color signal light valves and emitted from the plurality of color signal light valves, respectively. A color synthesizing optical system, a light valve for a luminance signal that modulates the second polarized light that has been polarization-separated by the polarization separation optical system based on a predetermined luminance signal, and color synthesized by the color synthesizing optical system. Light and the shine Projection having a polarization combining optical system for combining the light modulated by the signal light valve and emitted from the brightness signal light valve, and a projection optical system for projecting the light combined by the polarization combining optical system In a type display device, an illumination relay optical system that guides light from the light source toward the plurality of color signal light valves, the illumination relay optical system including a front group and a rear group, The polarization separation optical system and the color separation optical system are arranged between the front group of the illumination relay optical system and the rear group of the illumination relay optical system, the illumination relay optical system, With respect to the front side and the rear side of the illumination relay optical system, the chief ray determined by the aperture stop of the projection optical system is parallel to the optical axis and has telecentricity.

According to the first aspect, similar to the conventional projection type display device, the polarization splitting optical system, the color separation optical system,
Since it is equipped with multiple color signal light valves, color combining optical system, brightness signal light valve, polarization combining optical system and projection optical system, cost reduction and high brightness can be achieved by using a small number of liquid crystal light valves. Moreover, a high-resolution projection image can be obtained. Further, in the first aspect, an illumination relay optical system is further provided, and a polarization separation optical system and a color separation optical system are arranged between the front group and the rear group of the illumination relay optical system, and the illumination relay optical system is provided. The optical system has telecentricity on its front and rear sides. If such a configuration is adopted, even when a cross dichroic mirror or the like is used as the color separation optical system, the light flux passing through the intersection of the two mirrors spreads on the light valve. It is possible to prevent the color unevenness of the projected image caused by it. However, in the first aspect, the color separation optical system is not limited to the cross dichroic mirror, and may be a cross dichroic prism or the like.

A projection type display device according to a second aspect of the present invention is the projection type display device according to the first aspect, wherein the color combining optical system is arranged at a position where the principal ray has telecentricity. Is.

According to the second aspect, the color synthesizing optical system is arranged at a position where the chief ray determined by the aperture stop of the projection optical system maintains the telecentricity, so that the color synthesizing optical system is arranged. It is possible to eliminate the color shading of the projected image due to the angle characteristic of.

A projection type display device according to a third aspect of the present invention is the projection type display device according to the first or second aspect, wherein the polarization combining optical system is arranged at a position where the principal ray has telecentricity. It was done.

According to the third aspect, the polarized light combining optical system is arranged at a position where the chief ray determined by the aperture stop of the projection optical system maintains the telecentricity. It is possible to eliminate the unevenness in the contrast of the projected image due to the angle characteristic of.

A projection type display device according to a fourth aspect of the present invention is the projection type display device according to any one of the first to third aspects, wherein an integrator is provided between the light source and the polarization separation optical system. Is provided, the front group of the illumination relay optical system is provided so as to guide the light from the integrator to the polarization splitting optical system, and the rear group of the illumination relay optical system is the color separation optical system. It is provided for each color light color-separated by the system.

A projection type display device according to a fifth aspect of the present invention is the projection type display device according to the fourth aspect, wherein the integrator forms a surface light source, and the illumination relay optical system includes the color separation optical system. An image of the surface light source is formed by each color light that has been color-separated by a system, and each of the plurality of color lights is provided between the image of the surface light source by each color light and the plurality of color signal light valves. A color signal relay optical system for guiding each of the color signal light valves is provided for each color, and is a brightness signal relay optical system for guiding the light from the light source to the brightness signal light valve. Further comprising a relay optical system for brightness signal configured with a group, between the polarization splitting optical system and the light valve for brightness signal, the rear group of the relay optical system for brightness signal is provided, For luminance signal It said front group of laser optical system and said front group of the illumination relay optical system is one that is shared by the same optical system.

A projection type display device according to a sixth aspect of the present invention is the projection type display device according to the fifth aspect, wherein the illumination relay optical system is an optical system telecentric to the image side of the surface light source. The plurality of color signal relay optical systems respectively form secondary images of the surface light source by each color light on the plurality of color signal light valves, and
It is a telecentric optical system on the next image side, and the luminance signal relay optical system forms an image of the surface light source on the luminance signal light valve, and is a telecentric optical system on the image side of the surface light source. Is what is.

According to the sixth aspect, each light valve is arranged at a position where the chief ray maintains the telecentricity, so that each light valve is provided with telecentric illumination. The unevenness of the contrast of the projected image due to the angle characteristic of each light valve does not occur.

A projection display device according to a seventh aspect of the present invention is the projection display device according to the fifth or sixth aspect, wherein the plurality of color signal light valves are R light light valves and G light light valves. A relay optical system for R light having a light valve and a light valve for B light, wherein the color signal relay optical system guides R light from the primary image of the surface light source by the R light to the R light light valve. A system, a G light relay optical system that guides G light from the primary image of the surface light source by the G light to the G light light valve, and 1 of the surface light source by the B light.
And a B light relay optical system for guiding the B light from the next image to the B light light valve.

[0021]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A projection type display device according to an embodiment of the present invention will be described below with reference to FIGS.

FIG. 1 is a schematic perspective view showing the overall structure of a projection type display device according to an embodiment of the present invention. For simplification of explanation, X, Y, and Z coordinate systems shown in the figure and orthogonal to each other are defined. FIG. 2 is a ray diagram in the YZ section of the projection type display device shown in FIG. FIG.
The solid line in the drawing indicates the outermost marginal ray of the off-axis light beam, and the broken line in FIG. 2 indicates the principal ray of this off-axis light beam (the principal ray determined by the aperture stop 107a of the projection lens 107). The coordinate system in FIG. 2 corresponds to that in FIG.

In the projection type display device according to this embodiment,
As shown in FIG. 1, light from a light source 1 including a lamp (not shown) and an elliptical mirror in which the lamp is placed at a first focus passes through an infrared absorption filter (not shown) and an ultraviolet absorption filter (not shown) and then has a prismatic shape. The light is focused on the incident end surface (the end surface on the side close to the light source 1) of the rod integrator 2 made of the transparent optical member. The light that has entered the rod integrator 2 is repeatedly reflected on the inner surface of the rod integrator 2 and is emitted from the emission end surface that faces the incidence end surface. Here, a surface light source having a uniform light intensity distribution is formed on the emission end surface. In other words, the output end face is illuminated in a superimposed manner with light from virtual images of a plurality of light sources formed at the position of the incident end face by internal reflection of the rod integrator 2.

Next, the light from the exit surface of the rod integrator 2 travels in the -Z direction in the figure, and the first illumination lens 101 in the front group and the second illumination lens 102 in the rear group.
First, the light is incident on the first illumination lens 101 of the illumination relay optical system including R, 102G, and 102B.

The illuminating relay optical system includes a first illuminating lens 101 having a focal length f1 as a front group and second illuminating lenses 102R, 102G having a focal length f2 as a rear group.
And 102B. First illumination lens 101
The distance between the second illumination lens 102R, 102G, and 102B is f1 + f2. That is, the rear focus position of the first illumination lens 101 and the second illumination lens 102R,
The front focus positions of 102G and 102B match.

First illumination lens 101 and second illumination lens 1
A polarization beam splitter 3 as a polarization separation optical system and a cross dichroic mirror 5 as a color separation optical system are arranged between the first and second illumination lenses 101 and 02R, 102G, 102B. Further, a half-wave plate 4 is arranged between the polarization beam splitter 3 and the cross dichroic mirror 5.

The light transmitted through the first illumination lens 101 is incident on the polarization beam splitter 3, is transmitted through the polarization splitting portion of the polarization beam splitter 3, and is emitted in the −Z direction as the first polarized light (P polarized light). (Linear polarized light whose vibration direction is ± Y direction in the figure) and second polarized light (S-polarized light (vibration direction is ± Y in the figure) which is reflected by the polarization splitting portion and is emitted in the −Y direction.
Direction linearly polarized light)) and polarized light is separated. The first polarized light emitted from the polarization beam splitter 3 in the −Z direction is 1 /
It is incident on a cross dichroic mirror 5 which is a color separation optical system in a state of polarized light which has passed through the two-wavelength plate 4 and whose polarization direction has been rotated by 90 degrees (linear polarization whose vibration direction is ± X directions). The cross dichroic mirror 5 has a structure in which an R light reflection dichroic mirror 5R and a B light reflection dichroic mirror 5B are combined in an X type, and the light incident on the cross dichroic mirror 5 is separated into R, G, and B lights. To do. That is, R light of the light incident on the cross dichroic mirror 5 in the -Z direction is reflected in the -X direction by the R light reflection dichroic mirror 5R, and B light is reflected in the X direction by the B light reflection dichroic mirror 5B. The G light passes through the dichroic mirrors 5R and 5B and travels in the -Z direction.

The R light color-separated by the cross dichroic mirror 5 enters the second illumination lens 102R of the rear group of the illumination relay optical system, and the B light is the second group of the rear group of the illumination relay optical system. It enters the illumination lens 102B, and G
The light is the second illumination lens 1 in the rear group of the illumination relay optical system.
02G respectively. This color separated R light, G
The light and the B light are the second illumination lens 10 in the optical path of each light.
An image of the emission end face of the rod integrator 2 (image of a surface light source) is formed for each color at the rear focal position of 2R, 102G, 102B.

Here, the G light component of each color component light will be described with reference to FIG. The G light emitted from the cross dichroic mirror 5, which is a color separation optical system, passes through the second illumination lens 102G that forms the rear group of the illumination relay optical system, is reflected by the bending mirror 6G, and is -Y in the figure.
The optical path length f from the second illumination lens 102G.
A real image (primary image) IG of G light on the exit end face of the rod integrator 2 is formed at a position separated by two. The G light from the image IG is an illumination lens 103 having a focal length f2 arranged at a position away from the image IG by an optical path length of f2.
G is transmitted, is reflected by the bending mirror 7G,
Traveling in the Z direction, the optical path length f1 + from the illumination lens 103G
The illumination lens 10 having the focal length f1 arranged at the position f2
Pass 4G. The illumination lenses 103G and 104G are color light relay optical systems for G light (G light relay optical system).
As described above, the rear focal point of the illumination lens 103G and the front focal point of the illumination lens 104G are arranged so as to coincide with each other. The G light emitted from the G light relay optical system travels in the Z direction and reaches the G light liquid crystal light valve 8G as the G light color signal light valve. The G-light liquid crystal light valve 8G is arranged at a distance f1 from the illumination lens 104G of the G-light relay optical system, and the emission end surface (surface light source) G of the rod integrator 2 is arranged on the liquid crystal light valve 8G. A real image (secondary image) is formed by light.

Referring again to FIG. 1, the R light reflected by the cross dichroic mirror 5 in the -X direction is reflected by the bending mirror 6R and travels along the -Y direction in the figure. This R light is similar to the case of the G light described above,
Illumination lens 102 forming the rear group of the illumination relay optical system
After passing through R, R on the emission end face of the rod integrator 2
A real image (primary image) formed by light is formed at a position at a distance f2 from the rear group illumination lens 102R. The R light from this image passes through the illumination lens 103R, is then reflected by the bending mirror 7R, is deflected in the X direction in the drawing, and is illuminated by the illumination lens 10.
Pass 4R. The illumination lenses 103R and 104R are color light relay optical systems for R light (relay optical systems for R light).
Is composed. The illumination lens 103R has a focal length f2.
And is arranged at a distance of the optical path length f2 from the image. The illumination lens 104R has a focal length f1, and the distance between the illumination lens 104R and the illumination lens 103R is f1 + f2, that is, the rear focus of the illumination lens 103R and the illumination lens 10R.
It is arranged so that the front focus of the 4R matches. The R light from the R light relay optical system travels in the X direction, and
The liquid crystal light valve for R light 8R as a light valve for light color signals is reached. This R light liquid crystal light valve 8R
Are arranged at a distance f1 from the illumination lens 104R of the relay optical system for R light.
A real image (secondary image) by the R light on the emission end face of the rod integrator 2 is formed on the upper side.

The B light reflected in the X direction by the cross dichroic mirror 5 is reflected by the bending mirror 6B and travels along the -Y direction in the figure. As in the case of the G light described above, the B light passes through the illumination lens 102B forming the rear group of the illumination relay optical system, and an image of the B end of the emission end surface of the rod integrator 2 is formed by the rear group illumination lens. It is formed at a position of a distance f2 from 102B. The B light from this image is reflected by the folding mirror 7B that has passed through the illumination lens 103B, is deflected in the -X direction in the drawing, and passes through the illumination lens 104B. The illumination lenses 103B and 104B described above configure a color signal relay optical system for B light (B light relay optical system). Lighting lens 1
03B has a focal length f2, and from the image, the optical path length f2
It is located in the distance. The illumination lens 104B has a focal length f1, and the distance from the illumination lens 103B is f1 +.
It is arranged so as to be f2, that is, the rear focus of the illumination lens 103B and the front focus of the illumination lens 104B match. The B light from the B light relay optical system travels in the -X direction and reaches the B light liquid crystal light valve 8B as the B light color signal light valve. This B
The liquid crystal light valve 8B for light is arranged at a distance f1 from the illumination lens 104B of the relay optical system for B light, and on the light valve 8B, a real image (secondary image) of B light on the emission end face of the rod integrator 2 is formed. Image) is formed.

In this way, the liquid crystal light valve 8 for each color light is used.
An image of the emission end face of the rod integrator 2 having a uniform light intensity is formed on the R, 8G, and 8B. That is,
The light valve for each color is critically illuminated by a uniform surface light source. In addition, in the present embodiment, the illumination lens 101 and the illumination lens 1 that configure the illumination relay optics.
02R, 102G, and 102B form the output image of the output surface of the rod integrator 2 at f2 / f1 times, and the relay optical system for each color light reproduces this image at f1 / f2 times on the liquid crystal light valves 8R, 8G, and 8B. Form an image. That is, an equal-magnification image of the exit end face of the rod integrator 2 is formed on each of the liquid crystal light valves 8R, 8G, and 8B. Thus, in the present embodiment, the rod integrator 2
Emission end face and liquid crystal light valves 8R, 8G, 8B for each color
Since and are conjugate arrangements, and their magnifications are also equal,
The emission end surface of the prismatic rod integrator 2 is determined in vertical and horizontal sizes so as to have the same size and shape as the image display surface of each liquid crystal light valve.

In the projection display apparatus according to the present embodiment shown in FIGS. 1 and 2, the R light illumination lens 102R and the B light illumination lens 102B, which form the rear group of the illumination relay optical system, are The lens having the same focal length f2 as the G light illumination lens 102G, and the R light relay optical system illumination lens 103R and the B light relay optical system illumination lens 103B are G light relay optical system illumination lenses. 1
03G has the same focal length f2, and the illumination lens 104R of the R light relay optical system and the illumination lens 104B of the B light relay optical system have the same focal length f1 as the illumination lens 104G of the G light relay optical system. Is the lens.

Further, liquid crystal light valves 8R, 8R for respective colors are formed from the cross dichroic mirror 5 which is a color separation optical system.
The optical path lengths up to G and 8B are substantially the same.

Here, the liquid crystal light valves 8R, 8 for each color
G and 8B will be described. Each liquid crystal light valve 8R,
8G and 8B form a crossed Nicols liquid crystal panel 2
The structure is sandwiched between two polarizing plates. Although not shown in the drawing, the liquid crystal panel includes, in order from the incident light side, a transparent glass substrate, an active non-linear element (for example, a TFT) that selectively switches lattice-shaped pixels formed on the glass substrate, and a combination thereof. The liquid crystal layer, the counter electrode, and the transparent glass substrate are included in the pixel. A voltage is applied between the pixel electrode and a counter electrode facing the pixel by the active element switched by the color signal for each color, so that the electric field causes liquid crystal molecules to be parallel to each other and perpendicular to the substrate. Arranged in. Therefore, the linearly polarized light that has passed through the incident-side polarizing plate passes through the liquid crystal panel as it is, and is absorbed by the exit-side polarizing plate that constitutes crossed Nicols. On the other hand, in a portion not selected by the active element, the liquid crystal molecules maintain a twisted structure, and in this case, the polarized light passing through the incident side polarization plate has a polarization direction of 90 degrees following the twist of the liquid crystal molecules. After being rotated and converted, the liquid crystal panel is emitted and passes through a polarizing plate on the emission side. In this manner, the liquid crystal light valves for each color are switched by each color signal, so that an image corresponding to each color signal is formed on the light valve. That is, the light passing through each liquid crystal light valve is modulated.

Now, liquid crystal light valves 8R, 8 for each color light
On the output side of G and 8B, as a color combining optical system, a reflection dichroic film 9R for R light and a B light reflection dichroic film 9 are provided.
A cross dichroic prism 9 in which four right-angled prisms are combined is arranged so that B and X are X-shaped. The G light modulated by the G light liquid crystal light valve 8G and emitted from the liquid crystal light valve 8G travels in the Z direction in FIG.
It passes through the light reflection dichroic film 9R and the B light reflection dichroic film 9B. Also, a liquid crystal light valve 8 for R light
The R light modulated by R and emitted from the R travels in the X direction, is reflected by the R light reflecting dichroic film 9R, and is reflected in the Z direction in the drawing. The B light which is modulated by the B light liquid crystal light valve 8B and is emitted therefrom travels in the -X direction and is reflected in the Z direction by the B light reflecting dichroic film 9B. That is, the cross dichroic mirror 5
3 directions (R light is -X direction, G light light is -Z direction,
The respective color lights separated into the B light in the X direction pass through the liquid crystal light valves 8R, 8G, 8B and then in the opposite directions (R light is the X direction, G light is the Z direction). B light is incident on the cross dichroic prism 9 in the −X direction), and color combination is performed by the cross dichroic prism 9.
The color combined light is emitted from the cross dichroic prism 9 in the opposite direction (Z direction) to the incident direction (-Z direction) to the cross dichroic mirror 5. At this time, the R light emitted from the R light liquid crystal light valve 8R is linearly polarized light vibrating in the ± Y directions, and the G light liquid crystal light valve 8R
The G light emitted from G is a linearly polarized light vibrating in the ± Y directions, and the B light emitted from the liquid crystal light valve for B light 8B is a linearly polarized light vibrating in the ± Y directions. As described above, in the present embodiment, since the half-wave plate 4 is arranged between the polarization beam splitter 3 and the cross dichroic mirror 5, the liquid crystal light valves 8R, 8G, and 8B of the respective colors are emitted and crossed. The vibration direction of the linearly polarized light incident on the dichroic prism 9 can be S-polarized with respect to the film surface of the dichroic film of the cross dichroic prism 9. As a result, the spectral characteristics of each dichroic film can be improved. That is, when the incident light to the color synthesizing optical system is S-polarized light with respect to the color synthesizing film surface of the color synthesizing optical system as described above, the S-polarized light has the spectral characteristic of the color synthesizing film as compared with the case of the P polarized light. Since light is superior, light loss can be reduced, which is preferable.

On the exit side (Z direction) of the cross dichroic prism 9, a combining relay optical system including a lens 105 and a lens 106 is provided. The light passing through the combining relay optical system travels in the Z direction, is reflected by the bending mirror 10, travels in the Y direction, and is a composite image I of the light valves 8R, 8G, 8B for the respective color lights.
To form That is, as the combining relay optical system, for example, as shown in FIG. 2, the lens 1 having the focal length f3 is used.
05 and the lens 106 having the focal length f4 are separated by a distance f3 + f4.
It is possible to use the one arranged in. In this case, the composite image I is f4 / of the emission end face of the rod integrator 2.
f3 times.

Now, the second polarized light reflected by the polarization beam splitter 3 (linearly polarized light whose vibration direction is ± X direction in the figure) proceeds along the -Y direction in the figure and has a focal length f2. After passing through the third illumination lens 102, the folding mirror 1
It is reflected at 2 and travels in the Z direction. Third illumination lens 1
02 has an optical path length f1 + with the first illumination lens 101.
It is arranged so as to be f2, that is, the rear focus of the first illumination lens 101 and the front focus of the third illumination lens 102 match. A brightness signal liquid crystal light valve 13 is disposed at the rear focal position of the third illumination lens 102. In the present embodiment, the illumination lens 101,
Reference numeral 102 constitutes a luminance signal relay optical system that forms an image of the exit end face of the rod integrator 2 on the luminance signal liquid crystal light valve 13, and the illumination lens 101 is a front group of the luminance signal relay optical system. The illumination lens 102 constitutes the rear group of the relay optical system for luminance signals. The first illumination lens 101 is shared by the front group of the illumination relay optical system and the front group of the luminance signal relay optical system.

The brightness liquid crystal light valve 13 is structurally similar to the color signal liquid crystal light valves 8R, 8G, and 8B, but its size is larger than that of the color signal liquid crystal light valve, and the number of pixels is large. Is also configured to increase. An enlarged image of the emission end face of the rod integrator 2 is formed on the luminance signal light valve 13 by the luminance signal relay optical system including the illumination lens 101 as the front group and the illumination lens 102 as the rear group. At this time, the magnification of the enlarged image on the brightness signal liquid crystal light valve 13 is given by f2 / f1. On the other hand, as mentioned above,
The composite image I is f4 / f3 times as large as the emission end face of the rod integrator 2. Therefore, the focal lengths of the first to third illumination lenses 101, 102R, 102G, 102B, and 102 and the illumination lens 10 of the relay optical system for each color light.
3R, 104R, 103G, 104G, 103B, 10
The values of f1 and f2, which are the focal lengths of 4B, and f, which are the focal lengths of the lenses 105 and 106 of the combining relay optical system.
The values of 3, f4 may be determined according to the size ratio of the brightness signal light valve 13 and the color signal light valves 8R, 8G, 8B.

The emission side of the light valve 13 for brightness signal (Z
A polarization beam splitter 14 as a synthesizing optical system is arranged on the direction side). Luminance signal light valve 13
The light emitted from the polarization beam splitter 1 is linearly polarized light having vibrations in the ± Y directions and is P polarized light with respect to the polarization splitting portion of the polarization beam splitter 14.
4, the projection lens 107 which is located on the exit side of the projection lens 107.
Incident on.

From the combined image I formed by the combining relay optical system composed of the lenses 105 and 106, ±
Linearly polarized light having vibrations in the Z direction travels along the Y direction. The linearly polarized light passes through the half-wave plate 11 and the polarization direction is rotated by 90 degrees to generate vibrations in the ± X directions. Therefore, the polarization beam splitter 14 as a polarization combining optical system is used.
The S-polarized light becomes the S-polarized light, is reflected by the polarized-light separating unit, travels in the Z direction in the drawing, and is incident on the projection lens 107. Here, the light valve 13 for luminance signal and the composite image I are in a conjugate position with respect to the projection lens 107.

In this way, the color-combined light and the light from the brightness signal light valve 13 are combined by the polarization beam splitter 14, and the combined light is projected by the projection lens 107.
Is projected on a screen (not shown) by the.

This projection lens 107 has an aperture stop 107.
a, and the rear focal point of the lens group (aperture stop 1 that is located closer to the polarization beam splitter 14 than the aperture stop 107a).
The 07a side is the rear side. ), The aperture stop 107a is arranged at the position. This aperture stop 107a determines the principal ray of the optical system that constitutes the projection display device, and the principal ray becomes parallel to the optical axis between the polarization beam splitter 14 and the projection lens 107. That is, the projection lens 107 is an optical system that is telecentric on the polarization beam splitter 14 side.

As shown in FIG. 2, in the projection display apparatus according to this embodiment, the optical path between the emission end face of the rod integrator 2 and the first illumination lens 101, the second illumination lenses 102G and G for G light are used. Lighting lens 1 for optical relay optical system
03G, an optical path between the illumination lens 104G of the G light relay optical system and the lens 105 of the combining relay optical system, an optical path between the lens 106 of the combining relay optical system and the projection lens 107, And the projection lens 107 in the optical path between the third illumination lens 102 and the projection lens 107.
The chief ray determined by the aperture stop 107a of is parallel to the optical axis.

Although not shown in FIG. 2, an optical path between the second illumination lens 102R for R light and the illumination lens 103R of the relay optical system for R light, and the illumination lens 104R of the relay optical system for R light. 105 of the relay optical system for synthesis
Between the second illumination lens 102B for B light and the illumination lens 103B of the relay optical system for B light, and the illumination lens 104B of the relay optical system for B light and the combination relay optical system. Also between the lens 105 and the lens 105, the principal ray determined by the aperture stop 107a of the projection lens 107 becomes parallel to the optical axis. In other words, the illumination relay optical system 101 and 102R, 101 and 102G, 101 and 10
2B, luminance signal relay optical systems 101 and 102, R light relay optical systems 103R and 104R, B light relay optical systems 103B and 104B, G light relay optical systems 103G and 1
The 04G and combining relay optical systems 105 and 106 are optical systems that are telecentric on both sides.

Furthermore, the synthesizing relay optical system including the illumination lenses 105 and 106 also includes the light valves 8R and 8R for the respective color lights.
A telecentric optical system in which the principal ray is parallel to the optical axis between 8G and 8B and the combining relay optical system and between the combining relay optical system and the brightness signal light valve 13 to the illumination lens 102. .

With the above optical system, the light valves 8R, 8G, 8B for the respective color lights and the light valve 13 for the luminance signal are provided.
However, the chief ray is configured to maintain telecentricity. Therefore, the liquid crystal light valve 8R,
It is possible to eliminate the contrast unevenness depending on the characteristics due to the incident angles of the principal rays of 8G, 8B, and 13.

Furthermore, since the telecentricity of the chief ray is ensured for the color synthesizing optical system, it is possible to eliminate the color shading that occurs depending on the incident angle of the chief ray.

Further, in this embodiment, the cross dichroic mirror 5 is used as the color separation optical system, but the cross dichroic mirror 5 is a plane mirror in which an R light reflecting dichroic film is formed on a transparent glass substrate. (R light reflection dichroic mirror) 5R and a plane mirror (B light reflection dichroic mirror) having a B light reflection dichroic film formed on the same glass substrate are orthogonal to each other and are combined in an X-shape. From the point of having this structure, R light reflection mirror 5R and B light reflection mirror 5B
It is unavoidable that an intersection of the two will occur. In the case of the projection type display device of the conventional example shown in FIG. 3 described above, the R light reflection dichroic mirror 210 and the G light reflection dichroic mirror 215 are not combined in the X type but are arranged separately for each one. However, in the present embodiment, one intersection runs in the Y direction in the figure at the center of the optical path. For this reason, when the cross dichroic mirror 5 is used as the color separation optical system as in the present embodiment, this crossing portion causes vertical color unevenness in the central portion of the projected image unless any consideration is made. Occurs. In the case of the cross dichroic prism 9 used as the color synthesizing optical system, the crossing portion runs in the same way vertically in the optical path. However, in the cross dichroic prism, right-angle prisms are closely attached to each other. Therefore, there is almost no influence (occurrence of color unevenness) due to the intersection.

In the present embodiment, the cross dichroic mirror 5 includes the front group illumination lens 101 and the rear group illumination lenses 102R, 102G, 102 of the illumination relay optical system.
By being arranged between B and B, the influence of color unevenness on the projected image at the intersection of the cross dichroic mirror 5 is eliminated.

The reason is as follows. Considering the light fluxes that travel backward from the screen to the projection lens 107 and travel from the color signal light valves 8R, 8G, 8B to the light source 1, the light fluxes from the points on the light valves 8R, 8G, 8B are substantially uniform. It can be seen that the cross dichroic mirror 5 is passed through. Therefore, the influence of the crossing portion of the cross dichroic mirror 5 spreads uniformly on the light valve, so that the crossing portion does not appear as uneven color on the screen. In particular, it is preferable to arrange the intersection of the cross dichroic mirrors 5 at the focal position on the rear side (light valve side) of the illumination lens 101, since the effect of preventing the color unevenness is maximized.

In this embodiment, the liquid crystal light valves 8R, 8G for the respective color lights are displayed on the screen (not shown).
The image of 8B and the image of the light valve for brightness signal 13 are formed in a combined state, but the liquid crystal light valves for each color light 8R, 8G, 8B are arranged so that the directions of the images on the screen are aligned.
It goes without saying that the liquid crystal light valve 13 for luminance signal is driven.

Although one embodiment of the present invention has been described above, the present invention is not limited to this embodiment.

For example, in the projection type display device according to the embodiment shown in FIGS. 1 and 2, it has been explained that the combining relay optical system is composed of two lens groups of the lens 105 and the lens 106. In addition, for example, a field lens arranged near the exit side of the cross dichroic prism 9, a field lens arranged near the combined image, and a relay lens having a positive refractive power arranged between these two field lenses. You may.

Although the half-wave plate 11 is arranged between the combined image I and the combining polarized light beam splitter 14, it is not limited to this location, and the dichroic prism 9 and the combined polarized light beam splitter 14 are not necessary. It does not matter where it is placed between 14 and 14.

Sheet type 1/2 wave plates can be used as the 1/2 wave plates 4 and 11, and in that case, they are attached to the surfaces of the polarization beam splitters 3 and 14 and prism members such as the dichroic prism 9. It should be attached.

Although the rod integrator 2 is used as the integrator in the above embodiment, a fly-eye lens or the like may be used instead. Further, instead of using a lamp and an elliptical mirror as the light source 1, for example, a lamp and a parabolic mirror or a spherical mirror can be used.

Further, the field stop may be arranged at a position conjugate with the exit surface of the rod integrator 2. By doing so, it is possible to remove internal reflection and scattered light in the optical system of the projection type display device, thereby improving the contrast of the projected image and preventing the liquid crystal light valve from being heated.

[0059]

As described above, according to the present invention,
The cost can be reduced by using a small number of liquid crystal light valves, a high-intensity and high-resolution projected image can be obtained, and even if a cross dichroic mirror or the like is used as a color separation optical system, its structure It is possible to prevent the color unevenness of the projected image due to.

Further, according to the present invention, the color synthesizing optical system is
By disposing the chief ray determined by the aperture stop of the projection optical system at a position having telecentricity parallel to the optical axis, it is possible to eliminate color shading due to the angular characteristic of the color combining optical system.

Further, according to the present invention, by arranging the polarization synthesizing optical system at a position where the chief ray determined by the aperture stop of the projection optical system has telecentricity, the polarization synthesizing optical system has an angular characteristic. It is possible to eliminate the uneven contrast of the projected image.

Furthermore, according to the present invention, since each light valve is arranged at a position where the chief ray determined by the aperture stop of the projection optical system maintains the telecentricity, The unevenness of the contrast of the projected image due to the angle characteristic can be eliminated.

[Brief description of drawings]

FIG. 1 is a schematic perspective view showing an overall configuration of a projection type display device according to an embodiment of the present invention.

FIG. 2 is an optical path diagram in the YZ section in FIG. 1 of the projection type display device shown in FIG.

FIG. 3 is a schematic configuration diagram showing a conventional projection display device.

[Explanation of symbols]

1 Light Source 2 Rod Integrator 3 Polarizing Beam Splitter (Polarization Separation Optical System) 4,11 1/2 Wave Plate 5 Cross Dichroic Mirror (Color Separation Optical System) 5RR R Light Reflecting Dichroic Mirror 5B B Light Reflecting Dichroic Mirror 8R, 8G, 8B Liquid crystal light valve for color signal 9 Cross dichroic prism (color combining optical system) 13 Liquid crystal light valve for luminance signal 14 Polarization beam splitter (polarization combining optical system) 101 First illumination lens 102R, 102G, 102B Second illumination lens 102 Third Illumination lens 103R, 104R, 103G, 104G, 103B,
104B illumination lens 105, 106 lens 107 projection lens

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display location G09F 9/00 360 G09F 9/00 360D

Claims (7)

[Claims] 1. A polarization separation optical system that separates light from a light source into a first polarization light and a second polarization light, and a plurality of the first polarization lights separated by the polarization separation optical system. A color separation optical system that separates the color lights into color lights, a plurality of color signal light valves that respectively modulate the plurality of color lights separated by the color separation optical system based on predetermined color signals, and the plurality of colors. A color synthesizing optical system for color synthesizing the light modulated by the signal light valve and emitted from each of the plurality of color signal light valves; and the second polarization light polarized and separated by the polarization separation optical system. A light signal for a luminance signal that is modulated based on the luminance signal of light, light that is color-synthesized by the color synthesizing optical system, and light that is modulated by the light signal for a luminance signal and emitted from the light valve for a luminance signal. In a projection display device having a polarized light combining optical system that combines the polarized light combining optical system and a projection optical system that projects the light combined by the polarized light combining optical system, the light from the light source is transmitted to the plurality of color signal light valves. An illumination relay optical system guided toward, comprising an illumination relay optical system composed of a front group and a rear group, wherein the polarization splitting optical system and the color separation optical system are the illumination relay optical system. It is arranged between the front group and the rear group of the illumination relay optical system, and the illumination relay optical system is an opening of the projection optical system with respect to the front side and the rear side of the illumination relay optical system. A projection-type display device characterized in that a chief ray determined by a diaphragm has a telecentric property parallel to an optical axis. 2. The projection display device according to claim 1, wherein the color combining optical system is arranged at a position where the chief ray has telecentricity. 3. The projection display apparatus according to claim 1, wherein the polarized light combining optical system is arranged at a position where the chief ray has telecentricity. 4. An integrator is provided between the light source and the polarization splitting optical system, and the front group of the illumination relay optical system is configured to guide light from the integrator to the polarization splitting optical system. 4. The projection according to claim 1, wherein the rear group of the illumination relay optical system is provided for each color light color-separated by the color separation optical system. Type display device. 5. The integrator forms a surface light source, and the illumination relay optical system forms an image of the surface light source by each color light separated by the color separation optical system, and the surface formed by each color light. Between the image of the light source and the plurality of color signal light valves, a color signal relay optical system for guiding the respective color light to the plurality of color signal light valves is provided for each color. Is a brightness signal relay optical system for guiding light from the brightness signal light valve to the brightness signal light valve, further comprising a brightness signal relay optical system composed of a front group and a rear group, wherein the polarization splitting optical system and the brightness The rear group of the relay optical system for luminance signals is provided between the signal light valve and the front group of the relay optical system for luminance signals and the front group of the relay optical system for illumination are the same. Shared by the optical system of Projection display device according to claim 4, wherein a. 6. The illumination relay optical system is an optical system that is telecentric to the image side of the surface light source, and the plurality of color signal relay optical systems generate a secondary image of the surface light source by each color light. An optical system which is formed on each of the plurality of color signal light valves and is telecentric to the secondary image side, wherein the luminance signal relay optical system forms an image of the surface light source on the luminance signal light valve. 6. The projection type display device according to claim 5, wherein the projection type display device is an optical system which is formed on the surface of the surface light source and is telecentric to the image side of the surface light source. 7. The plurality of color signal light valves include an R light light valve, a G light light valve, and a B light light valve, and the color signal relay optical system includes the surface based on the R light. A relay optical system for R light for guiding the R light from the primary image of the light source to the light valve for R light, and 1 of the surface light source by the G light.
A G light relay optical system for guiding the G light from the next image to the G light light valve, and a B light for guiding the B light from the primary image of the surface light source by the B light to the B light light valve. 7. The projection type display device according to claim 5, further comprising a relay optical system.