JPH10274820A - Three-color separation optical system and projection type display device using it - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the contrast of a projected picture from being deteriorated because an excellent polarized light separation characteristic cannot be obtained with respect to the light of all wavelength are as by a polarizing beam splitter(PBS). SOLUTION: The light from a light source 1 is color-separated to the R light and the mixed light of the G light and the B light. The R light is polarized and separated by the PBS 5R and the S polarized light thereof is made incident on a light valve 6R. The mixed light is polarized and separated by the PBS 5G and the P polarized light thereof is transmitted through a filter 7 for transmitting G light fitted to the emitting surface of the PBS 5G and it becomes the G light. Then, the G light is made incident on a light valve 6G. The S polarized light of the mixed light is color-separated by a dichroie mirror 10 and it becomes the B light. Then, the B light is reflected on the PBS 5B and made incident on a light valve 7B. The respective color light modulated by the valves 6B, 6G and 6R are detected by the PBSs 5B, 5G and 5R, color- synthesized by a cross dichroic prism 13 and projected by a projection lens 14.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a three-color separation optical system used for a projection type display device and the like, and a projection type display device using the same.

[0002]

2. Description of the Related Art As a conventional example of a projection type display apparatus using a three-color separation optical system, an apparatus described in Japanese Patent Application Laid-Open No. 63-39294 is known. FIG. 6 shows a configuration diagram of this conventional projection type display device. The projection type display device will be described with reference to FIG.

In FIG. 6, reference numeral 211 denotes a three-color separation optical system which also serves as a color combining optical system.
Is a first prism 211 arranged as shown in FIG.
A, a second prism 211B and a third prism 211C. On the surface 211e of the first prism 211A,
A dichroic thin film that reflects blue light and transmits light in a longer wavelength range than that is deposited. First prism 211
A gap is formed between A and the second prism 211B. A dichroic thin film that reflects red light and transmits green light is deposited on a surface 211f between the second prism 211B and the third prism 211C. Therefore, when white light is incident on the surface 211a, blue light is reflected on the surface 211e, and the blue light is further totally internally reflected on the surface 211a and travels toward the emission surface 211b. Surface 211e
The red light of the light transmitted through the surface 211f is reflected by the surface 211f, and the inner surface is totally reflected by the surface in contact with the gap, so that the emission surface 211f
Head to c. Of the light transmitted through the surface 211e, green light is transmitted through the surface 211f and travels toward the emission surface 211d. In FIG. 6, 212, 213, and 214 display a blue component video, a red component video, and a green component video, respectively.
It is a two-dimensional reflective liquid crystal element (light valve). In addition,
These light valves 212, 213 and 214 are respectively provided on the back surface of the transmission type light valve with a reflective layer 2 made of a dielectric material.
15, 216, and 217 are formed, respectively, and are configured as reflective light valves. In FIG. 6, reference numeral 221 denotes a polarization beam splitter, which is arranged on the setting optical axis O of the three-color separation optical system 211.
Reference numeral 222 denotes a collimation lens, and a white light source 223 such as a halogen lamp is arranged almost on the focal point of the collimation lens 222. 218, 219, 2
Reference numeral 20 denotes a drive circuit that drives the light valves 212, 213, and 214, respectively.

In the conventional projection display apparatus having the above-described configuration, the light beam emitted from the white light source 223 enters the collimation lens 222 to become a parallel light beam, and the S-polarized light reflected by the polarization beam splitter of the polarization beam splitter 221. Is incident on the three-color separation optical system 211. The linearly polarized light (S-polarized light) that has entered the three-color separation optical system 211 is color-separated into each color light, and the light valves 212, 213, and 2 for each color light.
14 and is spatially modulated by the video signal of each color light, reflected by changing the polarization direction by 90 degrees, going backwards in the optical path, color-combined by the three-color separation optical system 211, and emitted from the surface 211a. The component (P-polarized component) whose polarization direction has been converted is detected by the polarization beam splitter 221 and transmitted therethrough, and is projected on the screen 225 by the projection lens 224.

[0005]

However, the conventional projection display device has the following problems. That is, in the conventional projection display device, the white light source 2
Polarization beam splitter 22 for separating the light from
1 is that, since the wavelength region that needs to be polarized light separation is white light, polarization separation must be achieved for all wavelength regions. However, it is practical to perform good polarization separation in all wavelength regions. However, there is a problem that the contrast of the projected image is degraded in a certain wavelength range.

In the conventional projection display device, the light from the light source is polarized and separated by the polarization beam splitter 221, and one of the separated lights is subjected to color separation and color synthesis, thereby obtaining the color synthesized light. Is analyzed by the polarization beam splitter 221, the polarization plane is rotated in the prisms 211A, 211B, and 211C for performing color separation and color synthesis, and there is a problem that the contrast of the projected image is deteriorated. In order to prevent the polarization plane from rotating in the prism, it is necessary to use a material that minimizes birefringence (distortion) as the optical glass constituting the prism. Could not be avoided. And even if you use this material,
The birefringence cannot be completely eliminated, resulting in a decrease in the contrast of the projected image.

The present invention has been made in view of such circumstances, and the contrast of a projected image caused by the inability of a polarizing beam splitter to obtain good polarization separation characteristics with respect to light in all wavelength ranges has been developed. It is an object of the present invention to provide a projection display device that can prevent deterioration and a three-color separation optical system that can be used in the projection display device.

Further, the present invention provides a projection display device capable of preventing deterioration of the contrast of a projected image due to birefringence of an optical system for performing color synthesis, and a three-color separation optical system which can be used for the display device. The purpose is to provide.

[0009]

In order to solve the above-mentioned problems, a three-color separation optical system according to a first aspect of the present invention comprises a light source that mixes light from a light source with first and second and third color lights. A first dichroic mirror for color separation into light and light,
A polarized light beam splitter that separates the mixed light color-separated by the dichroic mirror into two polarized light beams, and transmits the second colored light beam through the exit surface of one polarized light beam of the polarized beam splitter. A polarizing beam splitter having a color filter or a dichroic film, and the other polarized light that has been polarized and separated by the polarizing beam splitter and is emitted from an exit surface of the polarizing beam splitter where the color filter and the dichroic film are not arranged. And a second dichroic mirror for color-separating the third color light from the other polarized light.

According to the first aspect, the light from the light source is color-separated by the first dichroic mirror into the first color light and the mixed light of the second and third color lights. The mixed light is separated into two polarized lights by the polarization beam splitter, and one of the polarized lights passes through a color filter or a dichroic film disposed on one of the exit surfaces of the polarized beam splitter, and is mixed with a second color light. Become. The other polarized light of the mixed light that has been polarized and separated by the polarizing beam splitter is color-separated by a second dichroic mirror to be a third color light. According to the first aspect, the light from the light source is color-separated into the first, second, and third color lights in this manner.

Therefore, according to the first aspect, for example, the first color light color-separated by the first dichroic mirror is polarization-separated by the polarization beam splitter provided for the first color light. The polarized light of the first color light is modulated by the light valve for the first color light, and the polarized light of the second color light transmitted through the color filter or the dichroic film of the polarization beam splitter is modulated by the light valve for the second color light. And
The polarized light of the third color light, which has been color-separated by the second dichroic mirror, is reflected or transmitted by a polarization beam splitter provided for the third color light (that is, is again polarized and separated), and the third color light is separated. If the polarized light is modulated by the light valve for the third color light, the polarization beam splitter in which a color filter or a dichroic film is disposed on one of the exit surfaces is sufficient only for light in the wavelength range of the second color light. The polarization beam splitter for the first color light and the polarization beam splitter for the second color light need only be able to obtain the polarization separation characteristic, respectively, and can be used for the light in the wavelength range of the first color light and the light in the wavelength range of the second color light, respectively. It is sufficient that sufficient polarization separation characteristics can be obtained only for this. As described above, since each polarization beam splitter only needs to obtain sufficient polarization separation characteristics for light in a narrow band wavelength range, the polarization separation characteristics of each polarization beam splitter can be improved, and as a result, the projected image Can be improved.

A three-color separation optical system according to a second aspect of the present invention forms first, second, and third color lights, which are respectively incident on first, second, and third light valves, from light from a light source. A first dichroic mirror for color-separating light from the light source into the first color light and a mixed light of the second and third color lights. A first polarization beam splitter that separates the first color light that has been color-separated by the dichroic mirror into two polarized lights, and two polarized lights that mix the mixed light that is color-separated by the first dichroic mirror. 2nd polarization separation into light
A second polarizing beam splitter having a color filter or a dichroic film that transmits the second color light on an emission surface of one of the polarized lights of the second polarizing beam splitter; From the other polarized light that has been polarized and separated by the second polarized beam splitter and is emitted from the exit surface of the second polarized beam splitter where the color filter and the dichroic film are not disposed. A second dichroic mirror for color-separating the third color light, and a third polarization beam splitter for reflecting or transmitting the third color light color-separated by the second dichroic mirror, One polarized light separated by the polarization beam splitter, and polarized by the second polarization beam splitter Isolated the color filter or the said one of the polarized light dichroic film has passed through the, and,
The polarized light reflected or transmitted by the third polarizing beam splitter is used as each color light to be incident on the first, second, and third light valves, respectively.

According to the second aspect, the light from the light source is color-separated into the first color light and the mixed light of the second and third color lights by the first dichroic mirror. The first color light is polarized and separated by the first polarization beam splitter into two polarized lights, and one polarized light of the first color light is incident on the first light valve. The mixed light color-separated by the first dichroic mirror is separated into two polarized lights by a second polarizing beam splitter, and one of the polarized lights is arranged on one exit surface of the second polarizing beam splitter. The second light passes through the color filter or the dichroic film and becomes the second color light, and the polarized light that has become the second color light is incident on the second light valve. The other polarized light of the mixed light that has been polarized and separated by the second polarizing beam splitter is color-separated by a second dichroic mirror to become a third colored light. The polarized light that has become the third color light is reflected or transmitted by the third polarizing beam splitter (that is, is again polarized and separated), and is incident on the third light valve. According to the second aspect, in this manner, the light from the light source is color-separated into the first, second, and third color lights that have become polarized lights, and the respective color lights are first, second, and third, respectively. The light is incident on the third light valve.

Therefore, according to the second aspect, the first, second, and third polarization beam splitters only need to obtain sufficient polarization separation characteristics only for light in the wavelength range of each color light. Since it is sufficient to obtain sufficient polarization separation characteristics only for light in a narrow wavelength band, the polarization separation characteristics of each polarization beam splitter can be improved, and as a result, the contrast of a projected image can be improved. Can be.

According to the second aspect, if a reflection type light valve is used as the first, second, and third light valves, the light is modulated by the first, second, and third light valves. The first, second, and third color lights
Can be analyzed by the polarization beam splitter described above, and the analyzed light of each of these color lights can be synthesized by a separate color synthesis optical system. Therefore, even when the polarization direction of each color light changes due to the birefringence due to distortion or the like of the prism member or the like when each color light passes through the prism member or the like constituting the color synthesis optical system, However, the contrast is not deteriorated after the color synthesis as in the projection type display device described above, so that the contrast of the projected image does not deteriorate. As described above, the birefringence of the prism member or the like constituting the color combining optical system does not affect the contrast of the projected image at all. It is not necessary to use a simple material, and cost can be reduced.

According to a third aspect of the present invention, there is provided a projection type display device comprising: a first dichroic mirror for color-separating light from a light source into a first color light and a mixed light of the second and third color lights; A first polarization beam splitter that separates the first color light that has been color-separated by the first dichroic mirror into two polarized lights, and the mixed light that is color-separated by the first dichroic mirror; A second polarization beam splitter that separates the polarized light into two polarized lights,
A second polarizing beam splitter having a color filter or a dichroic film that transmits the second color light on the exit surface of one polarized light of the polarizing beam splitter, and the other polarized light separated by the second polarizing beam splitter. A second polarized light that separates the third color light from the other polarized light emitted from the emission surface of the second polarization beam splitter where the color filter and the dichroic film are not disposed. A dichroic mirror, a third polarization beam splitter that reflects or transmits the third color light that has been color-separated by the second dichroic mirror, and one of the polarization lights separated by the first polarization beam splitter And the color filter or the dichroic separated by the second polarization beam splitter. The first, second, and third reflections respectively modulate the one polarized light transmitted through and the polarized light reflected or transmitted by the third polarization beam splitter based on signals for respective colors. Type light valve,
A color combining optical system, and a projection optical system, wherein the first, second, and third polarizing beam splitters convert each color light modulated by the first, second, and third reflective light valves. The color synthesis optical system performs color synthesis on each color light detected by the first, second, and third polarization beam splitters, and the projection optical system performs color synthesis on the color synthesis optical system. This is to project the synthesized light.

The projection type display device according to the third aspect,
A projection display device using the three-color separation optical system according to the second aspect. According to the third aspect, the advantages described in relation to the second aspect are obtained. That is, according to the third aspect, the first, second, and third polarization beam splitters only need to obtain sufficient polarization separation characteristics for light in the wavelength range of each color light. Since it is sufficient to obtain sufficient polarization separation characteristics only for light in the wavelength range of, the polarization separation characteristics of each polarization beam splitter can be improved, and as a result, the contrast of the projected image can be improved. According to the third aspect,
When each color light passes through a prism member or the like constituting a color combining optical system, even if the polarization direction of each color light changes due to birefringence due to distortion or the like of the prism member or the like, the conventional projection is performed. Since the light is not analyzed after the color combination unlike the type display device, the contrast of the projected image does not deteriorate. As described above, the birefringence of the prism member or the like constituting the color combining optical system does not affect the contrast of the projected image at all. It is not necessary to use a simple material, and cost can be reduced.

In a projection type display according to a fourth aspect of the present invention, in the projection type display according to the third aspect, the color combining optical system is a cross dichroic prism or a cross dichroic mirror.

The projection display apparatus according to a fifth aspect of the present invention is the projection display apparatus according to the third or fourth aspect, wherein the first, second, and third polarizing beam splitters, The second and third reflective light valves and the color synthesizing optical system are arranged at a position where a principal ray determined by an aperture stop of the projection optical system has telecentricity.

By the way, since the performance of the light valve has an angle dependence, if the incident angle of the principal ray to the light valve differs depending on the place, the unevenness of the contrast of the projected image occurs due to this. In addition, the performance of the polarization beam splitter used for polarization and analysis also has an angle dependence, and if the angle of incidence of the principal ray on the polarization splitting surface of the polarization beam splitter varies depending on the location, this causes Contrast unevenness also occurs. Further, in a dichroic film used in a dichroic mirror or a dichroic prism used as a color synthesizing optical system, its spectral characteristics have an angle dependence. Therefore, if the incident angle of the principal ray to the dichroic film determined by the aperture stop of the projection optical system differs depending on the location, the spectral characteristics of the dichroic film differ for each principal ray, and color shading occurs on the screen.

In this regard, according to the fifth aspect, the first, second, and third polarization beam splitters,
Since the second and third reflective light valves and the color synthesizing optical system are arranged at positions where the chief ray determined by the aperture stop of the projection optical system has telecentricity, the chief ray of the light valve is Contrast unevenness of the projected image caused by the incident angle characteristic, unevenness of the projected image caused by the incident angle characteristic of the principal ray of the polarizing beam splitter, and color shading caused by the incident angle characteristic of the principal ray of the color combining optical system. Can be eliminated.

The projection display apparatus according to a sixth aspect of the present invention is the projection display apparatus according to any one of the third to fifth aspects, wherein the light source and the first dichroic mirror are provided between the light source and the first dichroic mirror. The fly-eye integrator is arranged.

As in the sixth aspect, when a fly's eye integrator is arranged between the light source and the first dichroic mirror, the first, second and third light valves can be arranged with respect to the first, second and third light valves. This is preferable because uniformity of illumination by the second and third color lights can be improved.

A three-color separation optical system according to a seventh aspect of the present invention comprises a first dichroic mirror for color-separating light from a light source into first color light and mixed light of second and third color lights;
A polarizing beam splitter for polarizing and separating the mixed light color-separated by the first dichroic mirror into two polarized lights, wherein the second colored light is provided on an exit surface of one polarized light of the polarized beam splitter; A first color filter or a first dichroic film that transmits light, and a second color filter or a second dichroic that transmits the third color light on the other polarized light exit surface of the polarizing beam splitter. A polarizing beam splitter having a film.

The three-color separation optical system according to the eighth aspect of the present invention forms the first, second and third color lights respectively incident on the first, second and third light valves from light from a light source. A first dichroic mirror for color-separating light from the light source into the first color light and a mixed light of the second and third color lights. A first polarization beam splitter that separates the first color light that has been color-separated by the dichroic mirror into two polarized lights, and two polarized lights that mix the mixed light that is color-separated by the first dichroic mirror. 2nd polarization separation into light
A polarizing beam splitter having a first color filter or a first dichroic film that transmits the second color light on an exit surface of one of the polarized lights of the second polarizing beam splitter. A second polarization beam splitter having a second color filter or a second dichroic film for transmitting the third color light on the exit surface of the other polarization light of the second polarization beam splitter, and the second polarization beam A third polarization beam splitter that reflects or transmits the other polarized light that is polarized and separated by the splitter and that has passed through the second color filter or the second dichroic film, wherein the first polarized beam is One of the polarized lights separated by the splitter,
The one polarized light that has been polarized and separated by the polarization beam splitter and has passed through the first color filter or the second dichroic film, and the polarized light that has been reflected or transmitted by the third polarization beam splitter Are the respective color lights to be incident on the first, second and third light valves, respectively.

According to a ninth aspect of the present invention, there is provided a projection type display device comprising: a first dichroic mirror for color-separating light from a light source into a first color light and a mixed light of second and third color lights;
A first polarization beam splitter that separates the first color light that has been color-separated by the first dichroic mirror into two polarized lights, and the mixed light that is color-separated by the first dichroic mirror; A second polarization beam splitter that separates the polarized light into two polarized lights, and a first color filter or a second color filter that transmits the second color light on an exit surface of one polarized light of the second polarized beam splitter. A second dichroic film and a second polarization filter having a second color filter or a second dichroic film for transmitting the third color light on the other polarized light exit surface of the second polarization beam splitter. A beam splitter,
A third polarizing beam splitter that reflects or transmits the other polarized light that is polarized and separated by the second polarizing beam splitter and that has passed through the second color filter or the second dichroic film; and One of the polarized lights separated by the polarizing beam splitter, the one of the polarized lights separated by the second polarizing beam splitter and transmitted through the first color filter or the first dichroic film, and First, second and third modulating the polarized light reflected or transmitted by the third polarization beam splitter based on signals for respective colors.
, A color combining optical system, and a projection optical system, wherein the first, second, and third polarizing beam splitters are provided in the first, second, and third reflective light valves. The color combining optical system performs color synthesis on each of the color lights detected by the first, second, and third polarizing beam splitters, and the projection optical system includes The light that is color-combined by the color-combining optical system is projected.

According to a tenth aspect of the present invention, there is provided the projection type display according to the ninth aspect, wherein:
The color combining optical system is a cross dichroic prism or a cross dichroic mirror.

The projection display apparatus according to an eleventh aspect of the present invention is the projection display apparatus according to the ninth or tenth aspect, wherein the first, second, and third polarization beam splitters, Second and third reflective light valves,
The color synthesizing optical system is arranged such that a principal ray determined by an aperture stop of the projection optical system has telecentricity.

The projection display apparatus according to a twelfth aspect of the present invention is the projection display apparatus according to any one of the ninth to eleventh aspects, wherein the light source and the first dichroic mirror are provided between the light source and the first dichroic mirror. The fly-eye integrator is arranged.

A three-color separation optical system according to a thirteenth aspect of the present invention is a first dichroic mirror for color-separating light from a light source into a first color light and a mixed light of the second and third color lights. And a first polarization beam splitter for polarization-separating the mixed light color-separated by the first dichroic mirror into two polarization lights, and the emission of one polarization light of the first polarization beam splitter. A first polarizing beam splitter having a first color filter or a first dichroic film transmitting the second color light on a surface thereof;
The other polarized light that has been polarized and separated by the polarized beam splitter, and that has been emitted from the exit surface of the polarized beam splitter where the first color filter and the first dichroic film are not disposed. A second color filter that transmits or reflects the third color light on an incident surface or an exit surface of the other polarization light of the second polarization beam splitter. A second polarizing beam splitter having a second dichroic film.

A three-color separation optical system according to a fourteenth aspect of the present invention forms first, second, and third color lights respectively incident on first, second, and third light valves from light from a light source. A first dichroic mirror for color-separating light from the light source into the first color light and a mixed light of the second and third color lights. The first color separated by the dichroic mirror
A first polarization beam splitter that polarization-separates the color light into two polarization lights, and a second polarization beam splitter that polarization-separates the mixed light color-separated by the first dichroic mirror into two polarization lights. A second polarization beam splitter having a first color filter or a first dichroic film transmitting the second color light on an exit surface of one of the polarization light beams of the second polarization beam splitter;
The other polarized light separated by the second polarization beam splitter and emitted from the exit surface of the second polarization beam splitter where the first color filter and the first dichroic film are not arranged. A third polarization beam splitter that reflects or transmits the other polarized light, and transmits the third color light to an incident surface or an emission surface of the other polarized light of the third polarized beam splitter. A third polarization beam splitter having a second color filter or a second dichroic film, and one of the polarized lights separated by the first polarization beam splitter and the second polarization beam splitter. The one polarized light that has been polarized and separated and transmitted through the first color filter or the first dichroic film, and
The polarized light reflected or transmitted by the third polarization beam splitter and transmitted through the second color filter or the second dichroic film is respectively transmitted to the first and second polarization filters.
And light of each color to be incident on the third light valve.

A projection display apparatus according to a fifteenth aspect of the present invention includes a first dichroic mirror for color-separating light from a light source into a first color light and a mixed light of the second and third color lights. A first polarization beam splitter that polarization-separates the first color light that has been color-separated by the first dichroic mirror into two polarization lights, and the mixed light that is color-separated by the first dichroic mirror A second polarization beam splitter that polarizes and separates the second polarization beam into two polarization beams, and a first color filter or a first color filter that transmits the second color beam on an exit surface of one of the polarization beams of the second polarization beam splitter. A second polarization beam splitter having a first dichroic film; and a second polarization beam splitter polarized by the second polarization beam splitter, the polarization light being separated by the second polarization beam splitter and before the second polarization beam splitter. The first color filter and the first
A third polarization beam splitter that reflects or transmits the other polarized light emitted from the emission surface on which the dichroic film is not disposed, and the incident surface of the other polarized light of the third polarization beam splitter. Alternatively, a second color filter or a second color filter for transmitting the third color light
A third polarizing beam splitter having a dichroic film, and one of the polarized lights separated by the first polarizing beam splitter, the first color filter separated by the second polarizing beam splitter. The first
The one polarized light transmitted through the dichroic film and the polarized light reflected or transmitted by the third polarizing beam splitter and transmitted through the second color filter or the second dichroic film, respectively. A first, a second, and a third reflection type light valve that modulates based on a signal for use with a light source, a color combining optical system, and a projection optical system.
The first, second, and third polarization beam splitters detect the respective color lights modulated by the first, second, and third reflection type light valves, respectively, and the color combining optical system includes the first, second, and third polarization beam splitters. , The second and third polarization beam splitters perform color synthesis on the respective color lights detected by the polarization beam splitter, and the projection optical system projects the light synthesized by the color synthesis optical system.

In a projection type display according to a sixteenth aspect of the present invention, in the projection type display according to the fifteenth aspect, the color combining optical system is a cross dichroic prism or a cross dichroic mirror.

A projection display according to a seventeenth aspect of the present invention is the projection display according to the fifteenth or sixteenth aspect, wherein the first, second, and third polarization beam splitters, 2nd and 3rd reflective light valves,
The color synthesizing optical system is arranged such that a principal ray determined by an aperture stop of the projection optical system has telecentricity.

The projection type display according to an eighteenth aspect of the present invention is the projection type display according to any one of the fifteenth to seventeenth aspects, wherein the light source and the first dichroic mirror are provided between the light source and the first dichroic mirror. The fly-eye integrator is arranged.

According to the seventh to twelfth aspects, the same advantages as those of the first to sixth aspects can be obtained.
According to the thirteenth to eighteenth aspects, the same advantages as those of the first to sixth aspects can be obtained.

[0037]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a three-color separation optical system according to the present invention and a projection type display device using the same will be described in detail with reference to the drawings.

(First Embodiment) First, the basic structure of a projection type display apparatus according to a first embodiment of the present invention using a three-color separation optical system according to an embodiment of the present invention will be described.
This will be described with reference to FIG.

FIG. 1 is a schematic configuration diagram showing a basic configuration of a projection type display device according to the present embodiment.

In the projection type display device according to the present embodiment,
As shown in FIG. 1, the light source 1 includes a lamp 1a and a parabolic concave mirror 1b disposed on the back of the lamp 1a. The substantially parallel light source light including the R light (red light), the G light (green light), and the B light (blue light) emitted from the light source 1 is turned by the bending mirror 3 so that the direction of the optical axis is changed to a right angle. The light travels and is incident on the first dichroic mirror 4 having the property of reflecting light in the G light wavelength region and B light wavelength region and transmitting light in the R light region arranged at an incident angle of 45 degrees with respect to the optical axis. The light is separated into R light that is transmitted through the optical axis in the same direction as the incident direction, and G light and B light that is reflected and travels while changing the optical axis at a right angle.

The R light color-separated by the dichroic mirror 4 is incident on an R light polarizing beam splitter 5R.
The polarization beam splitter of the polarization beam splitter 5R provides
The light is polarized and separated into the S-polarized light of the R light reflected and emitted by the polarization separation unit and the P-polarized light of the R light transmitted through the polarization separation unit. The S-polarized light is incident on the reflection type liquid crystal light valve 6R arranged near the exit surface of the polarization beam splitter 5R.

On the other hand, the mixed light of the G light and the B light that has been color-separated and reflected by the dichroic mirror 4 is incident on the polarization beam splitter 5G, and is incident on the polarization beam splitter 5G.
Are separated into P-polarized light transmitted through the polarized light separating section and S-polarized light reflected by the polarized light separating section. A color filter 7 having a property of transmitting G light is disposed on the exit surface of the P-polarized light of the polarization beam splitter 5G.

The P-polarized light of the mixed light of the G light and the B light transmitted through the polarization splitter of the polarizing beam splitter 5G becomes only the G light through the color filter 7, and the P-polarized light of the G light is converted to the G light. Incident on the reflective light valve 6G. Instead of the color filter 7 having the property of transmitting G light, a G light transmitting dichroic film may be formed on the emission surface. In that case, the B light is not absorbed by the dichroic film, but is reflected, proceeds toward the light source 1, and is discarded.

The S-polarized light of the mixed light of the G light and the B light reflected by the polarization beam splitter of the polarization beam splitter 5G exits the polarization beam splitter 5G and travels, and enters at 45 degrees with respect to the optical axis. The direction of the optical axis is changed to a right angle by the bending mirror 9 disposed at the corner, and the light is further advanced by 45 ° with respect to the optical axis.
B light arranged at an angle of incidence
The light B is incident on the second dichroic mirror 10 having the property of transmitting light, and only the B light travels leftward in FIG. 1 while changing its optical axis to a right angle. Dichroic mirror 10
The G light of the S-polarized light of the mixed light of the G light and the B light incident on is transmitted through the dichroic mirror 10 and discarded. The B light of the S-polarized light that has been color-separated and reflected by the dichroic mirror 10 is incident on the polarization beam splitter 5B, is reflected and emitted by the polarization separation unit of the polarization beam splitter 5B, and is a reflective light for B light. The light enters the valve 6B.

As can be understood from the above description, in the present embodiment, the dichroic mirrors 4 and 10, the polarizing beam splitters 5R, 5G and 5B, and the bending mirror 9 enter the light valves 6R, 6G and 6B, respectively. A three-color separation optical system for forming R light, G light and B light from light from the light source 1 is configured.

Here, the reflection type light valve, in particular, the electric writing type reflection type light valve employed as the light valves 6R, 6G, 6B in this embodiment will be described with reference to FIG. FIG. 5 is a schematic cross-sectional view showing an example of an electric writing type reflective light valve. As shown in FIG. 5, the electric writing type reflective light valve includes a transparent glass substrate 301, a transparent conductive film (ITO) electrode 302, a liquid crystal alignment film 303, a TN liquid crystal layer 304, a liquid crystal alignment film 305, a reflection electrode 306, Reflective electrode 306 and TFT
Conductors 307 and 308 connecting to the drain 312,
It includes a TFT drain 312, a TFT gate 310, a TFT source 311, a TFT oxide layer 309, and a silicon substrate 313. In FIG. 5, 314 is a TFT source diffusion region, and 315 is a TFT drain diffusion region. When a voltage is applied to the gate 310, TF
T switches to electrode 3 via drain 312
A voltage is applied between the liquid crystal layer 06 and the counter electrode 302, and the liquid crystal molecules of the liquid crystal layer 304 at the selected location are aligned by an electric field due to the applied voltage, and the liquid crystal layer 304 at the location is １ ／ wavelength. Acts as a plate. Therefore, the polarized light that has entered the relevant portion becomes circularly polarized light, enters the metal reflective electrode 306, is reflected by the electrode 306 in the opposite direction, and when passing through the liquid crystal 304 again, is different from the circularly polarized light as incident light. The light is emitted as linearly polarized light whose polarization direction has been changed by 90 degrees. On the other hand, in a place where a voltage is not applied to the gate 310 and the TFT is not switched and is not selected, no electric field is generated between the electrode 306 and the counter electrode 302, and the liquid crystal molecules in the liquid crystal layer 304 dissolve both the alignment films 303 and 303. The incident polarized light is rotated according to the direction determined by the alignment direction of the liquid crystal molecules 305, is rotated according to the liquid crystal molecules, travels, is reflected by the metal electrode 306, and is again rotated according to the twist of the liquid crystal molecules. The light then travels and is emitted as polarized light having the same polarization direction as the incident light. The polarized light whose polarization direction is shifted by 90 degrees from the polarization direction of the incident light can be emitted only at the selected location. The above is the function of the electric writing type reflection type light valve. The electric writing type reflection type light valve basically converts the polarization direction of the reflected outgoing light at an electrically selected location to a polarization direction different from the incident light. It has a function to make In the case of an electric writing reflective light valve having such a structure, T
Since the FT can be disposed below the electrode 306, the area of the electrode 306 can be increased, and the aperture ratio can be significantly increased.

As another example of the reflection type light valve, a light writing type reflection type light valve is known. In the present embodiment, the light writing type reflection type light valve is adopted as the light valves 6R, 6G, 6B. Of course, it may be possible. In this case, each light valve 6R, 6G,
A writing optical system for giving writing light to 6B is arranged.

Referring again to FIG. 1, the light valve 6
R light of P-polarized light incident on R, 6G, 6B, G
The light and the B light are modulated and reflected by the respective color signals, and are respectively reflected as modulated light to the respective light valves 6R, 6G, 6B.
From the polarization beam splitters 5R, 5G,
5B. The modulated light of the G light emitted from the light valve 6G is applied to the polarization beam splitter 5.
When the light enters G, the light again passes through the color filter 7 formed on the emission surface and enters the polarization splitting unit. As can be understood from the principle of the above-described electric writing type reflection type light valve, the modulated light of each color includes the S-polarized light (or P-polarized light) at the point where a voltage is applied according to the color signal for each color and the voltage. Is mixed with the P-polarized light (or S-polarized light) at the location where is not applied. The modulated light incident on the polarization beam splitters 5R, 5G, and 5B, respectively,
The light is analyzed by the polarization beam splitters 5R, 5G, and 5B, respectively. That is, only one polarized light of the modulated light of each color is transmitted or reflected by the polarization beam splitters 5R, 5G, and 5B, and advances toward the cross dichroic prism 13 as a color combining optical system (that is, the light is analyzed). ), The other polarized light of the modulated light of each color is reflected or transmitted by the polarization splitting films of the polarization beam splitters 5R, 5G, 5B and is discarded. The R light and the B light are respectively incident on the cross dichroic prism 13 from directions opposite to each other, and the G light is incident on the cross dichroic prism 13 at right angles to the incident side of the R light and the B light. Incident from the side surface.

The cross dichroic prism 13 is composed of R light reflecting dichroic films 13 R and B
It has a structure in which four right-angled isosceles triangular prisms are bonded together with an adhesive so that the light reflecting dichroic film 13B is orthogonal to each other to form an X-shape. R light and B light incident on the cross dichroic prism 13
The light analysis lights are dichroic films 13R and 13B, respectively.
By the cross dichroic prism 13
The analysis light of the G light incident on the dichroic film 13R,
13B, and all the analysis light beams are in the same optical axis direction (FIG. 1).
(Left direction in the middle) and exits from the cross dichroic prism 13. As described above, the analysis light of each color is synthesized.

The color-combined light enters the projection lens 14 and is projected on a screen (not shown) as a full-color enlarged image.

According to the present embodiment, as described above,
The light from the light source 1 is reflected by the dichroic mirror 4
It is color-separated into R light and mixed light of G light and B light. This R light is converted into P-polarized light and S-polarized light by the polarization beam splitter 5R.
The light is polarized and separated into polarized light, and the S-polarized light of the R light is incident on the light valve 6R. The mixed light color-separated by the dichroic mirror 4 is polarization-separated into P-polarized light and S-polarized light by a polarization beam splitter 5G, and the P-polarized light is arranged on one exit surface of the polarization beam splitter 5G. The light passes through the color filter 7 and becomes G light, and the P-polarized light that becomes G light enters the light valve 6G. The S-polarized light of the mixed light polarized and separated by the polarization beam splitter 5G is color-separated by the dichroic mirror 10 to be B light. The S-polarized light that has become the B light is
The light is reflected by the polarization beam splitter 5B (that is, is again polarized and separated), and is incident on the light valve 6B. According to the present embodiment, in this manner, the light from the light source 1 is color-separated into the R light, the G light, and the B light, which are respectively polarized light, and the respective color lights are respectively light valves 6R, 6G, and 6B.
Is incident on.

Therefore, according to the present embodiment, each of the polarization beam splitters 5R, 5G, and 5B only needs to obtain sufficient polarization separation characteristics only for light in the wavelength range of each color light. Since it is sufficient to obtain sufficient polarization separation characteristics only for light in the wavelength range, the polarization separation characteristics of each of the polarization beam splitters 5R, 5G, and 5B can be improved, and as a result, the contrast of the projected image is improved. be able to.

Further, according to the present embodiment, reflection type light valves are used as the light valves 6R, 6G, 6B, and the respective color lights modulated by the light valves 6R, 6G, 6B are used as the polarization beam splitters 5R, 5G. , 5B, and the detected light of each color is color-combined by the cross dichroic prism 13, which is a separate color-combining optical system. Therefore, when each color light passes through a prism member or the like constituting the cross dichroic prism 13 as a color combining optical system, the polarization direction of each color light changes due to birefringence due to distortion or the like of the prism member or the like. However, since the light is not analyzed after the color combination as in the conventional projection display device, the contrast of the projected image does not deteriorate. As described above, the birefringence of the prism member or the like constituting the color combining optical system does not affect the contrast of the projected image at all. It is not necessary to use a simple material, and cost can be reduced.

The basic configuration of the projection display device according to the present embodiment has been described above. Next, a specific example of the projection display device according to the present embodiment in which predetermined elements are added to the basic configuration will be described with reference to FIG. FIG.
1 is a schematic configuration diagram showing a projection display device according to this specific example. In FIG. 2, the same or corresponding elements as those shown in FIG. 1 are denoted by the same reference numerals, and redundant description will be omitted.

In the projection type display device according to this embodiment, as shown in FIG. 2, in addition to the basic configuration shown in FIG. 1, an optical system such as an illumination optical system, that is, a so-called separated fly-eye integrator is formed. First and second lens plates 2A and 2B, field lenses 8 and 12, and relay lens 11 are shown.

In FIG. 2, reference numeral 1 denotes a light source. The light source 1 includes a lamp 1a and a parabolic mirror 1b which is a concave mirror. The light source light emitted from the lamp 1a is reflected by the parabolic mirror 1b, emitted as a substantially parallel light beam, and is incident on the first lens plate 2A. First
The lens plate 2A constitutes a front member of a so-called separate fly-eye integrator having a lens matrix composed of a plurality of lenses on the incident surface side. In the present embodiment, the shape of the incident side surface of each lens formed on the surface of the lens plate 2A is a predetermined spherical shape, and the vertical / horizontal dimension ratio is the vertical length of the light valves 6R, 6G, 6B. / Length ratio. The substantially parallel light source light incident on each lens of the lens plate 2A is
Of the lens matrix on the second lens plate 2B which forms the rear member of the separation type fly-eye integrator via the bending mirror 3, and is condensed on each lens. You. That is,
In the present embodiment, the second lens plate 2B is disposed at a position of the focal length of the lens matrix on the first lens plate 2A.

With this configuration, each lamp image by each lens of the lens matrix on the first lens plate 2A is placed on each corresponding lens of the lens matrix on the second lens plate 2B. It is formed. The lens matrix on the second lens plate 2B is the first lens matrix.
The rows and columns of the lens matrix of the lens plate 2A are aligned.

The individual lenses constituting the lens matrix on the second lens plate 2B are arranged such that the corresponding light spots on the individual lenses of the lens matrix on the first lens plate 2A are converted to light valves 6R, 6G, 6B. Each of the light beams (sub-beams) divided by the individual lenses of the first lens plate 2A has a function of forming an image thereon, and each of the light beams (sub-beams) is divided by the individual lenses on the second lens plate 2B.
G and 6B are superimposed and irradiated. That is, the entrance surfaces of the individual lenses constituting the lens matrix on the first lens plate 2A are used as light sources by the individual lenses of the corresponding lens matrix of the second lens plate 2B on the light valves 6R, 6G, 6B. Critical illumination.

In this embodiment, since the light valves 6R and 6G have the same optical path length as viewed from the light source 1, the light valves 6R and 6G are directly formed by the individual lenses of the lens matrix of the second lens plate 2B. Critical illumination is achieved. On the other hand, the optical path length from the light source 1 to the light valve 6B is considerably longer than the optical path length to the light valves 6R and 6G.
Critical illumination is achieved for the light valves 6R, 6G via a relay optical system including the first lens 1 and the field lenses 8, 12.

That is, the same optical path length position (conjugate position) K as the light valve 6G on the optical axis of the mixed light of the G light and the B light reflected by the polarization beam splitter of the polarization beam splitter 5G.
The light spots on the individual lenses of the lens matrix of the first lens plate 2A due to the S-polarized light of the mixed light of the B light and the G light are superimposed by the individual lenses of the lens matrix of the second lens plate 2B. A critical illumination image is formed. The illumination image includes a field lens 12 disposed near the entrance surfaces of the field lens 8 and the polarizing beam splitter 5B, and an equal-magnification relay lens 1 disposed between the field lenses 8, 12.
1 forms an image on the light valve 6B and achieves critical illumination for the light valve 6B.

According to the specific example shown in FIG. 2, the light valves 6R and 6R are superposed by the individual lenses of the lens matrix on the second lens plate 2B as described above.
It is possible to improve the uniformity of illumination of each color light for G and 6B.

Next, another specific example of the projection type display device according to the present embodiment will be described with reference to FIG.

FIG. 3 is a schematic configuration diagram showing a projection type display device according to this specific example. FIG. 3 also shows the state of the principal ray of the off-axis light beam (the principal ray determined by the aperture stop 14a of the projection lens 14). Note that, in FIG. 3, the same or corresponding elements as those shown in FIGS. 1 and 2 are denoted by the same reference numerals, and redundant description thereof will be omitted.

The projection type display device according to this example is shown in FIG.
As shown in FIG. 1, the projection type display device shown in FIG. 2 in which predetermined elements are added to the basic configuration shown in FIG.
R, 5G, 5B, light valves 6R, 6G, 6B and a cross dichroic prism 1 as a color combining optical system
No. 3 is arranged at a position where the principal ray determined by the aperture stop 14a of the projection lens 14 has telecentricity.

The two light beams shown in FIG. 3 emitted from the lamp 1a of the light source 1 travel parallel to the optical axis by the parabolic mirror 1b of the light source 1, and the first lens plate is provided on both sides of the optical axis. It is assumed that the light enters the lens with the width of one lens in the lens matrix on 2A. As can be seen from the description of the projection type display device according to the specific example shown in FIG. 2 described above, the two light beams correspond to the lens matrix on the second lens plate 2B and the lens on the first lens plate 2A. The light is collected by the upper lens. Both light beams transmitted through the lens of the second lens plate 2B travel with a predetermined spread, and are color-separated into R light transmitted by the dichroic mirror 4 and mixed light of G light and B light reflected. Are incident on the field lenses 15 and 16 with the same spread, respectively, become light beams parallel to the optical axis via the field lenses 15 and 16, respectively, and become the polarization beam splitters 5R and 5R.
5G are respectively incident.

The R incident on the polarization beam splitter 5R
Bi-parallel rays of light are polarized and separated by the polarization beam splitter of the polarization beam splitter 5R, and bi-parallel rays of S-polarized light of the R light are reflected by the polarization beam splitter of the polarization beam splitter 6R to be split by the polarization beam splitter 5R. The light exits from the light valve 6R and enters the light valve 6R while keeping parallel to the optical axis. Further, the two light beams reflected by the light valve 6R are incident on the polarization beam splitter 5R while being kept parallel, and pass through the polarization splitting portion of the polarization beam splitter 5R, and the two transmitted light beams pass through the cross dichroic prism 13. The light is incident parallel to the optical axis, is reflected by the dichroic film 13R, and exits the cross dichroic prism 13 and is incident on the projection lens 14 while being parallel to the optical axis.

G incident on the polarizing beam splitter 5G
The two parallel rays of the mixed light of the light and the B light are polarization-separated by the polarization separation unit of the polarization beam splitter 5G. The biparallel rays of the P-polarized light of the mixed light pass through the polarization splitting portion of the polarization beam splitter 5G, pass through the color filter 7 and remain as G light while being parallel to the optical axis to become a G light. It is incident on 6G. Further, both light beams reflected by the light valve 6G are incident on the projection lens via the color filter 7, the polarizing beam splitter 5G, and the cross dichroic prism 13 while keeping parallel to the optical axis.

The two beams of S-polarized light, which is a mixture of G light and B light, which are incident on the polarization beam splitter 5G and reflected by the polarization splitting portion of the polarization beam splitter 6G, travel along the optical axis to the field lens 8. With respect to the relay lens 11, it is kept parallel to the field lens 8, crosses the aperture lens 11 a in the relay lens 11 via the bending mirror 9 and the dichroic mirror 10 in a state where the relay lens 11 is not parallel to the optical axis after exiting the field lens 8. The light is emitted, is made parallel again to the optical axis via the field lens 12, and the polarization beam splitter 5B and the light valve 6 are maintained while maintaining the parallel state.
B, the polarization beam splitter 5 </ b> B, and the cross dichroic prism 13, and sequentially enter the projection lens 14.

Here, the projection lens 14 will be described. The projection lens 14 is, as shown in FIG.
4a, a front lens group located closer to the cross dichroic prism 13 than the aperture stop 14a (ie, right side in the figure), and a rear lens group located closer to the screen (not shown) than the aperture stop 14a (left side in the figure). Have. The aperture stop 14a is disposed at the focal point on the rear side (the screen side is the rear side) of the front lens group, and the projection lens 1
Reference numeral 4 denotes a telecentric optical system on the side of the cross dichroic prism 13 (front side). In other words, the light beam passing through the center of the aperture stop 14a, that is, the principal ray determined by the aperture stop 14a of the projection lens 14 is parallel to the optical axis at the front side of the projection lens 14.

The two rays parallel to the optical axis, which are emitted from the cross dichroic prism to the projection lens 14 having the above characteristics and are incident from the front side, are transmitted to the aperture stop 14a.
It can be seen that they cross at the center of.

Therefore, since the two rays in FIG. 3 described above pass through the center of the aperture stop 14a of the projection lens 14, it is understood that the two rays are principal rays determined by the aperture stop 14a of the projection lens 14. it can. That is, the principal ray determined by the aperture stop 14a of the projection lens 14 becomes parallel to the optical axis in the light valves 6R, 6G, 6B, the polarization beam splitters 5R, 5G, 5B, and the cross dichroic prism 13 for each color light. The principal ray changes the telecentric characteristic to each of the elements 6R, 6R.
It can be seen that G, 6B, 5R, 5G, 5B, and 13 are maintained. In other words, each of the elements 6R, 6R
G, 6B, 5R, 5G, 5B, and 13 are arranged at positions where the principal ray has telecentricity. Further, as can be understood from the above description, the illumination optical system uses the surfaces of the individual lenses constituting the lens matrix on the first lens plate 2A as the individual light sources and the corresponding lenses on the second lens plate 2B. The telecentric critical illumination is achieved on the light valves 6R, 6G, 6B by the individual lenses that make up the matrix.

Although only the principal ray is shown in FIG. 3, the sub-beam formed by the lens matrix of the first lens plate 2A is not limited to this. For example, consider light rays incident on the left and right lenses of the first lens plate 2A. Similarly to the principal ray, the rays incident on the left and right lenses of the first lens plate 2A substantially parallel to the optical axis are respectively formed as sub-beams by the two lenses, and are formed on the corresponding second lens plate 2B. The light is focused on the lens. And the light valves 6R, 6G, 6
The light is superimposed on B and illuminated. Light valve 6R, 6
Both light beams reflected by G and 6B are condensed at both ends of the aperture of the aperture stop 14a of the projection lens 14 via the polarization beam splitters 5R, 5G and 5B and the cross dichroic prism 13.

The dichroic films 13R and 13B for performing color synthesis by the color synthesis optical system are formed by laminating a plurality of dielectric films, and these films 13R and 13B reflect light according to the incident angle of the incident light beam. The characteristics have different characteristics. For this reason, if the angles of incidence on the films 13R and 13B differ for each off-axis principal ray, color shading occurs on the screen. In this regard, according to the projection display apparatus shown in FIG. 3, as described above, the cross dichroic prism 13 as the color combining optical system is disposed at a position where the principal ray has telecentricity. No color shading due to the incident angle characteristic of the principal ray is generated.

Also, the polarization beam splitters 5R, 5G,
If the incident angle of the off-axis chief ray is different in 5B as well, the polarization separation characteristics will be different, and as a result, contrast unevenness will occur in the projected image. In this regard, in the projection display device shown in FIG. 3, as described above, the polarization beam splitters 5R, 5G, and 5B for the respective color lights are arranged at positions where the principal rays have telecentricity. No contrast unevenness of the projected image occurs due to the incident angle characteristics of the principal rays of 5R, 5G, and 5B.

Further, the liquid crystal light valves 6R, 6G, 6
If the incident angle of the off-axis chief ray also differs for B, the modulation characteristics of the liquid crystal layer differ, and as a result, contrast unevenness occurs in the projected image. In this regard, in the projection type display device shown in FIG. 3, since the light valves 6R, 6G, and 6B are arranged at positions where the principal rays have telecentricity, the incident angles of the principal rays of the light valves 6R, 6G, and 6B. There is no contrast unevenness of the projected image due to the characteristics.

In the projection type display device according to the present embodiment described above, as shown in FIGS. 1 to 3, B light from the mixed light of G light and B light reflected by the polarization splitter of the polarization beam splitter 5G is used. The color separation of light is performed by the dichroic mirror 10. However, it goes without saying that the dichroic mirror 10 may be a simple bending mirror and the mirror 9 may be a B light reflecting dichroic mirror.

Further, in the projection type display apparatus according to the present embodiment described above, the cross dichroic prism 13 is used as the color combining optical system, but a cross dichroic mirror may be used instead.

(Second Embodiment) Next, a second embodiment of the present invention will be described.
The projection type display device according to the embodiment will be described with reference to FIG.

FIG. 4 is a schematic configuration diagram showing a basic configuration of the projection type display device according to the present embodiment. In FIG.
Components that are the same as or correspond to those shown in FIG.

The projection type display device according to the present embodiment is different from the projection type display device shown in FIG. 1 in that a double-sided reflection mirror 21 is used instead of the folding mirror 9 in FIG. The arrangement of No. 3 has been changed. According to this embodiment, advantages similar to those of the above-described first embodiment can be obtained.

It is needless to say that the projection display device shown in FIG. 4 can be embodied in the same manner as the projection display device shown in FIG. 1 is embodied as shown in FIGS. .

(Third Embodiment) Next, a third embodiment of the present invention will be described.
The projection display device according to the embodiment will be described.

Although not shown in the drawing, the projection type display device according to the present embodiment uses a simple folding mirror instead of the dichroic mirror 10 in FIG. 1 in the projection type display device shown in FIG. A color filter or a dichroic film that transmits B light is formed on the exit surface of the splitter 5G for emitting the S-polarized light of the mixed light of the G light and the R light. According to this embodiment, advantages similar to those of the above-described first embodiment can be obtained.

It is needless to say that the projection display device according to the present embodiment can be embodied similarly to the case where the projection display device shown in FIG. 1 is embodied as shown in FIGS. is there. Further, in the projection type display device shown in FIG. 4, a simple bending mirror is used instead of the dichroic mirror 10 in FIG. 4, and the G of the polarization beam splitter 5G is used.
It goes without saying that a color filter or a dichroic film that transmits B light may be formed on the exit surface of the S-polarized light of the mixed light of the light and the R light.

(Fourth Embodiment) Next, a fourth embodiment of the present invention will be described.
The projection display device according to the embodiment will be described.

Although not shown in the drawing, the projection type display device according to the present embodiment uses a folding mirror instead of the dichroic mirror 10 in the projection type display device shown in FIG. Alternatively, a color filter or a dichroic film that transmits B light is formed on the exit surface to the light valve 6B. According to this embodiment, advantages similar to those of the above-described first embodiment can be obtained.

It is needless to say that the projection type display device according to the present embodiment can be embodied similarly to the case where the projection type display device shown in FIG. 1 is embodied as shown in FIGS. is there. In the projection display device shown in FIG. 4, a folding mirror is used in place of the dichroic mirror 10, and a color filter or a dichroic film transmitting B light is provided on the entrance surface of the polarization beam splitter 5B or the exit surface to the light valve 6B. It is needless to say that may be formed.

Although the embodiments of the present invention have been described above, the present invention is not limited to these embodiments.

For example, in the above-described embodiment, the light source 1
The concave mirror used in Example 1 is a parabolic mirror because it is incident on the first lens plate 2A with substantially parallel light. However, the present invention is not limited to this configuration. For example, it goes without saying that a substantially parallel light beam may be formed as a condensed light beam by an elliptical mirror using a shaping optical system using a concave lens.

Although a so-called fly-eye integrator is used as the illumination optical system, illumination may be performed using, for example, a rod integrator.

[0091]

As described above, according to the present invention,
It is possible to prevent the deterioration of the contrast of the projected image due to the inability of the polarization beam splitter to obtain good polarization separation characteristics for light in all wavelength ranges.

Further, according to the present invention, it is possible to prevent the deterioration of the contrast of the projected image due to the birefringence of the optical system for performing color synthesis.

Further, according to the present invention, a light valve,
By arranging the polarization beam splitter and the color combining optical system at a position where the principal ray determined by the aperture stop of the projection optical system has telecentricity parallel to the optical axis,
Contrast unevenness of the projected image due to the incident angle characteristic of the principal ray of the light valve, contrast unevenness of the projected image due to the incident angle characteristic of the principal ray of the polarizing beam splitter, and incident angle characteristic of the principal ray of the color combining optical system Can eliminate color shading due to

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing a basic configuration of a projection display device according to a first embodiment of the present invention.

FIG. 2 is a schematic configuration diagram showing a specific example of a projection display device according to the first embodiment of the present invention.

FIG. 3 is a schematic configuration diagram showing another specific example of the projection display device according to the first embodiment of the present invention.

FIG. 4 is a schematic configuration diagram showing a basic configuration of a projection display device according to a second embodiment of the present invention.

FIG. 5 is a schematic sectional view showing an example of an electric writing type reflection type light valve.

FIG. 6 is a schematic configuration diagram illustrating an example of a conventional projection display device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Light source 2A 1st lens plate 2B 2nd lens plate 3, 21 Bending mirror 4 R light transmission dichroic mirror 5R, 5G, 5B Polarization beam splitter 6R, 6G, 6B Reflection type light valve 7 G light transmission filter 9 Bending mirror Reference Signs List 10 B light reflecting dichroic mirror 11 Relay lens 12, 15, 16 Field lens 13 Cross dichroic prism 14 Projection lens 14a Aperture stop

Claims (6)

[Claims] 1. A first dichroic mirror for color-separating light from a light source into a first color light and a mixed light of second and third color lights, and color-separated by the first dichroic mirror. A polarizing beam splitter for splitting the mixed light into two polarized lights, the polarizing beam splitter having a color filter or a dichroic film that transmits the second color light on an exit surface of one of the polarized lights. A beam splitter, and the other polarized light that is polarized and separated by the polarization beam splitter, and is emitted from the other polarized light emitted from the emission surface on which the color filter and the dichroic film of the polarized beam splitter are not disposed. A second dichroic mirror for color-separating the third color light; and a three-color separation optical system. 2. A three-color separation optical system for forming first, second, and third color lights respectively incident on first, second, and third light valves from light from a light source, A first dichroic mirror for color-separating the light from the light source into the first color light and a mixed light of the second and third color lights; and the first dichroic mirror color-separated by the first dichroic mirror. A first polarizing beam splitter for polarizing and separating the first color light into two polarized lights; and a second polarizing beam for polarizing and separating the mixed light color-separated by the first dichroic mirror into two polarized lights. A second polarizing beam splitter having a color filter or a dichroic film that transmits the second color light on an emission surface of one of the polarized light beams of the second polarizing beam splitter; From the other polarized light that has been polarized and separated by the beam splitter and emitted from the emission surface of the second polarization beam splitter where the color filter and the dichroic film are not disposed, the third polarized light is obtained. A second dichroic mirror for color-separating the color light, and a third polarization beam splitter for reflecting or transmitting the third color light color-separated by the second dichroic mirror, wherein the first polarization beam One of the polarized lights separated by the splitter, the one polarized light separated by the second polarizing beam splitter and transmitted through the color filter or the dichroic film, and the third polarized beam splitter. The reflected or transmitted polarized light,
A three-color separation optical system, wherein each color light is incident on the first, second, and third light valves. 3. A first dichroic mirror for color-separating light from a light source into a first color light and a mixed light of second and third color lights, and color-separated by the first dichroic mirror. A first polarizing beam splitter for polarizing and separating the first color light into two polarized lights; and a second polarizing beam splitter for polarizing and separating the mixed light color-separated by the first dichroic mirror into two polarized lights. A second polarizing beam splitter having a color filter or a dichroic film that transmits the second color light on an emission surface of one of the polarized light beams of the second polarizing beam splitter; And the color filter and the dichroic film of the second polarization beam splitter are the other polarization lights polarized and separated by the polarization beam splitter. A second dichroic mirror for color-separating the third color light from the other polarized light emitted from the non-emission surface, and reflecting or transmitting the third color light color-separated by the second dichroic mirror A third polarization beam splitter; one of the polarized lights separated by the first polarization beam splitter; and the one polarized light separated by the second polarization beam splitter and transmitted through the color filter or the dichroic film. Polarized light, and the polarized light reflected or transmitted by the third polarizing beam splitter,
A first, a second, and a third reflective light valve that modulates based on a signal for each color, a color combining optical system, and a projection optical system, wherein the first, second, and third polarized lights are provided. The beam splitter detects each color light modulated by the first, second, and third reflective light valves, respectively, and the color combining optical system includes the first, second, and third polarized beams. A projection display apparatus, wherein the color light components of the respective color lights detected by the splitter are combined, and the projection optical system projects the light combined by the color combination optical system. 4. The projection display device according to claim 3, wherein the color combining optical system is a cross dichroic prism or a cross dichroic mirror. 5. The first, second and third polarization beam splitters, the first, second and third reflection type light valves, and the color combining optical system are controlled by an aperture stop of the projection optical system. 5. The projection display device according to claim 3, wherein the determined chief ray is arranged at a position having telecentricity. 6. The projection display device according to claim 3, wherein a fly-eye integrator is arranged between the light source and the first dichroic mirror.