JPH1039771A - Projection type display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve a color synthetic characteristic and a projected picture quality without impairment of color resolving characteristic. SOLUTION: Light from a light source is resolved into each color light through a cross dichroic mirror 3. Each resolved color light is polarized and separated into two polarized light through polarized light beam splitters 6R, 6G, and 6B. One of the polarized light beams of each color light is modulated by light bulbs 7R, 7B, and 7G. Modulated light of each color light is analyzed by the polarized light beam splitters 6R, 6G, and 6B, and is synthesized through a dichronic prism 8 which is a combination of three different shape triangular prism members 8-1, 8-2, and 8-3 with dichronic films 8G and 8B held and cemented in-between. The synthetic light is projected on a screen through a projection lens.

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.

[0002]

2. Description of the Related Art A conventional example of a full-color projection type display device using a reflection type light valve is disclosed in JP-A-63-392.
An apparatus described in Japanese Patent Application Publication No. 94 is known. FIG. 9 shows a configuration diagram of this conventional projection display device, and the projection display device will be described with reference to FIG.

In FIG. 9, reference numeral 211 denotes a color separation optical system. The color separation optical system 211 includes a first prism 211A, a second prism 211B, and a third prism 211C arranged as shown in FIG. . First prism 21
A dichroic thin film that reflects blue light and transmits light in a longer wavelength range than the blue light is deposited on the surface 211e of 1A. A gap is formed between the first prism 211A 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 this blue light is further totally internally reflected on the surface 211a, and the emission surface 211b
Head for. The red light of the light transmitted through the surface 211e is
The light is reflected by the surface 211f, and is totally internally reflected by the surface in contact with the gap, and travels toward the emission surface 211c. Of the light transmitted through the surface 211e, green light is transmitted through the surface 211f, and
Head to 11d. In FIG. 9, 212, 213, 21
Reference numeral 4 denotes a two-dimensional reflective liquid crystal element (light valve) for displaying a blue component video, a red component video, and a green component video in this order. Note that these light valves 212 and 21
Reference numerals 3 and 214 each have a structure in which reflective layers 215, 216, and 217 made of dielectrics are formed on the back surface of the transmission light valve, respectively, and are configured as reflection light valves. In FIG. 9, reference numeral 221 denotes a polarization beam splitter, which is arranged on the setting optical axis O of the 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.

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 color separation optical system 211. Color separation optical system 21
The linearly-polarized light (S-polarized light) incident on 1 is decomposed into each color light and incident on the light valves 212, 213, 214 for each color light, spatially modulated by the video signal of each color light, and the polarization direction is 90 degrees. The light is converted and reflected, goes backwards in the optical path, is color-combined by the color separation optical system 211, and
1a, the component (P-polarized component) whose polarization direction has been converted is analyzed by the polarization beam splitter 221 and transmitted therethrough.
5 is projected.

[0005]

However, the conventional projection display device has the following problems. That is, in the conventional projection display device, the color separation optical system 211 also serves as a color synthesis optical system.
The polarization direction of polarized light (S-polarized light) incident on the color separation optical system 211 when performing color separation, and the polarization direction (P-polarized light) of polarized light incident on the color separation optical system 211 when performing color synthesis. Will inevitably be different. However, the characteristics of the dichroic film constituting the color separation optical system 211 are different from those for P-polarized light and those for S-polarized light, and it is difficult to obtain a dichroic film having excellent dichroic characteristics for both polarized lights. It is. Therefore, there is a problem that one of the color separation characteristics and the color synthesis characteristics must be degraded, and the image quality of the projected image is degraded.

In the above-mentioned conventional projection display device, the polarization beam splitter 221 for separating and separating the light from the white light source 223 is provided in the entire wavelength region because the wavelength region to be polarized and separated is white light. Polarization separation must be achieved, but it is practically impossible to perform good polarization separation over the entire wavelength range.
In a certain wavelength region, there is a problem that the contrast of the projected image is deteriorated.

Further, in the above-mentioned 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. Is analyzed by the polarization beam splitter 221, so that, in the prisms 211 A, 211 B, and 211 C for performing color separation and color synthesis, if the polarization plane is rotated, the contrast of the projected image is degraded. . 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. I couldn't avoid it. Furthermore, even if this material is used, the birefringence cannot be completely eliminated, and as a result, the contrast of the projected image has been reduced.

The present invention has been made in view of such circumstances, and provides a projection type display device capable of improving the color composition characteristics without impairing the color separation characteristics and improving the image quality of a projected image. The purpose is to:

Further, there is provided a projection type display device capable of preventing deterioration of the contrast of a projected image due to the inability of the polarization beam splitter to obtain good polarization separation characteristics for light in all wavelength ranges. The purpose is to:

A further object of the present invention is to provide 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.

[0011]

According to a first aspect of the present invention, there is provided a projection display apparatus comprising: a light source for separating light from a light source into first, second, and third color lights; A separation optical system, first, second, and third light valves that modulate the color-separated first, second, and third color lights, respectively, and the first, second, and third light valves. A projection type display device having a color combining optical system for combining the modulated first, second, and third color lights, and a projection optical system for projecting the light combined by the color combining optical system. In the above, the color separation optical system is composed of a cross dichroic mirror or a cross dichroic prism or a plurality of flat plate dichroic mirrors, and the color synthesizing optical system includes three differently shaped triangular prism members,
It is composed of a combined dichroic prism by bonding together with a dichroic film or facing each other with an air gap therebetween.

According to the first aspect, the color separation optical system and the color synthesis optical system are constituted by separate optical systems. Therefore, only linearly polarized light having a certain polarization direction can be made to enter the color combining optical system. Therefore, the color synthesizing optical system only needs to obtain desired dichroic characteristics only for the incident polarized light, and can improve the dichroic characteristics for the incident polarized light. Therefore, without deteriorating the color separation characteristics,
The color synthesis characteristics can be improved, and the image quality of the projected image can be improved.

The projection display apparatus according to a second aspect of the present invention is the projection display apparatus according to the first aspect, wherein the first and second color lights incident on the dichroic prism constituting the color combining optical system. Are incident on the dichroic prism with optical axes perpendicular to each other, and the third color light incident on the dichroic prism constituting the color combining optical system is incident on the dichroic prism constituting the color combining optical system. Is incident on the dichroic prism with an optical axis that is neither perpendicular nor parallel to the optical axes of the first and second color lights.

The projection display apparatus according to a third aspect of the present invention is the projection display apparatus according to the second aspect, wherein the optical axes of the first and second color lights when emitted from the color separation optical system are different from each other. The first and second light beams emitted from the color separation optical system are parallel to the optical axes of the first and second color lights when entering the dichroic prism constituting the color synthesis optical system, respectively. The traveling direction of the second color light is opposite to the traveling direction of the first and second color lights when entering the dichroic prism constituting the color synthesizing optical system, and the third traveling out of the color separation optical system. Before the third color light enters the dichroic prism that forms the color combining optical system, the optical axis of the color light of the third color light enters the dichroic prism that forms the color combining optical system. The light is once converted into an optical axis that is parallel to the optical axis of the light, and the traveling direction of the third color light on the optical axis is the third color light when entering the dichroic prism that constitutes the color combining optical system. Is the direction opposite to the traveling direction.

A projection display apparatus according to a fourth aspect of the present invention is the projection display apparatus according to any one of the first to third aspects, wherein the first and second color separation optical systems separate the first and second colors. First, second, and third polarization beam splitters provided corresponding to the second and third color lights, respectively, wherein the first, second, and third polarization beam splitters are provided to the color separation optical system. The first, second, and third color lights, which have been color-separated, are respectively polarized and separated into two polarized lights, and the first, second, and third light valves are used for the first, second, and third light valves.
First and second polarization separated by the polarization beam splitter
And the first, second, and third polarization beam splitters respectively modulate one of the polarized lights of the first, second, and third color lights, and the first, second, and third light beams are modulated by the first, second, and third light valves.
The second and third color lights are respectively analyzed, and the color combining optical system colors the first, second and third color lights analyzed by the first, second and third polarization beam splitters. It is to be synthesized.

According to the fourth aspect, after the light from the light source is color-separated by the color separation optical system into the respective color lights, the color-separated color lights are provided corresponding to the respective color lights. The polarized light of each color is polarized by each polarization beam splitter, the polarized light of each color light is modulated by each light valve, and the modulated light of each color light is detected by each polarization beam splitter. As described above, since each of the polarization beam splitters separates each color light after color separation instead of white light, each polarization beam splitter performs polarization separation only on light in a narrow band wavelength range. Become. Therefore, since the wavelength range of the light to be polarization-separated in each polarization beam splitter is limited to a narrow band, the polarization separation characteristics of each polarization beam splitter can be improved, and as a result, the contrast of the projected image is improved. be able to.

Further, according to the fourth aspect, after the modulated light of each color light emitted from each light valve is analyzed by each polarizing beam splitter provided for each color light, the analysis of each color light is performed. Light is color-combined by a color-combining optical system. Therefore, when each color light passes through the prism member constituting the color combining optical system, even if the polarization direction of each color light changes due to the birefringence due to distortion or the like possessed by the prism member, the above-described conventional method is used. Since the light is not analyzed after the color combination unlike the projection display device, the contrast of the projected image does not deteriorate. As described above, since the birefringence of the prism member constituting the color combining optical system has no effect on the contrast of the projected image, an expensive material having a small birefringence is used as the material constituting the prism member. This eliminates the need to use the same, and can reduce costs.

The projection type display apparatus according to a fifth aspect of the present invention is the projection type display apparatus according to the fourth aspect, wherein the first, second and third light valves, the first and second light valves are provided.
And the third polarizing beam splitter and the color combining optical system are arranged at a position where a principal ray determined by an aperture stop of the projection optical system has telecentricity. Such an arrangement is made possible by employing an integrator or an illumination relay optical system, for example, as in sixth and seventh embodiments described later.

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 location, 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 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 light valves, the first, second, and third polarization beam splitters, and the color combining optical system include: Since the chief ray determined by the aperture stop of the projection optical system is located at a position having telecentricity, the contrast unevenness of the projected image due to the incident angle characteristic of the chief ray of the light valve, and the chief ray of the polarization beam splitter. It is possible to eliminate unevenness in contrast of a projected image due to the incident angle characteristic and color shading due to the incident angle characteristic of the principal ray of the color combining optical system.

The projection display apparatus according to a sixth aspect of the present invention is the projection display apparatus according to the fifth aspect, wherein the light from the light source is incident to form a surface light source, and the integrator is formed by the integrator. And an illumination relay optical system for forming an image of the surface light source on the first, second, and third light valves, respectively.

A projection display apparatus according to a seventh aspect of the present invention is the projection display apparatus according to the sixth aspect, wherein the illumination relay optical system includes a front group disposed in front of the color separation optical system. And a first, second, and third rear group disposed on the rear side of the color separation optical system and provided for each of first, second, and third color lights separated by the color separation optical system. And a relay optical system that forms an image of the image of the surface light source with the third color light formed by the front group and the third rear group on the third light valve. is there.

The projection display apparatus according to an eighth aspect of the present invention is the projection display apparatus according to any one of the first to seventh aspects, wherein the first color light emitted from the color separation optical system is The light incident on the color separation optical system is emitted from the color separation optical system with the same optical axis and traveling direction as the optical axis and traveling direction when entering the color separation optical system, and is emitted from the color separation optical system. The second and third color lights are emitted from the color separation optical system with an optical axis perpendicular to the optical axis of the first color light when emitted from the color separation optical system, and are output from the color separation optical system. The traveling directions of the second and third color lights at the time of emission are opposite to each other, the second color light incident on the color combining optical system is transmitted through the color combining optical system, and the first color light is green. Light, and the second color light is red light;
The third color light is blue light.

[0024]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a projection type display device according to the present invention will be described in detail with reference to the drawings.

First, a basic configuration of a projection display according to an embodiment of the present invention will be described with reference to FIG.

FIG. 1 is a schematic perspective view showing a basic configuration of a projection display according to an embodiment of the present invention. In addition,
For simplicity, X, Y, and Z axes orthogonal to each other are defined as shown in the figure.

As shown in FIG. 1, the white light source light incident from the -Y direction is changed its optical axis to the -X direction by the bending mirror 2, and the B light reflecting dichroic mirror 3B and the R light reflecting dichroic mirror 3R are mutually moved. The light enters a color separation optical system composed of a cross dichroic mirror 3 intersecting at right angles. FIG.
FIG. 6B shows an example of the transmittance-wavelength characteristic of the B light reflecting dichroic film of the light reflecting dichroic mirror 3B. FIG. 6B shows an example of the transmittance-wavelength characteristic of the R light reflecting dichroic film of the R light reflecting dichroic mirror 3R. Show. FIG.
In (a) and (b), the vertical axis indicates transmittance, and the horizontal axis indicates wavelength. The dichroic mirrors 3B and 3R are configured by forming a dichroic film having these characteristics on each glass substrate. Since the cross dichroic mirror 3 as the color separation optical system is configured as described above, the white light source light incident on the cross dichroic mirror 3 is converted into blue light (B light) traveling in the −Y direction and blue light (B light) traveling in the Y direction. The light is separated into red light (R light) that travels and green light (G light) that passes through the cross dichroic mirror 3 and travels in the −X direction.

The G light emitted from the cross dichroic mirror 3 has the same optical axis and traveling direction (-X) as the light incident on the cross dichroic mirror 3 when entering the cross dichroic mirror 3. Direction) from the color separation optical system. The R light and the B light emitted from the cross dichroic mirror 3 have an optical axis perpendicular to the optical axis of the color light of G light emitted from the cross dichroic mirror 3,
And the cross dichroic mirror 3
The traveling directions of the R light and the B light at the time of emission from are opposite to each other (Y direction and -Y direction).

Of the color lights separated by the cross dichroic mirror 3, the R light and the G light are reflected by the bending mirrors 5R and 5G, respectively, change their optical axis directions to the Z direction, and travel in the Z direction. I do. The B light color-separated by the cross dichroic mirror 3 and emitted in the −Y direction is reflected in a direction parallel to the XY plane by a bending mirror 4B arranged perpendicular to the XY plane, and reflected by the mirror 4B. The reflected B light is reflected by the bending mirror 5B, changes its optical axis direction to the Z direction, and travels in the Z direction.

FIG. 3 shows the elements 2 and 3 in FIG.
It is the XY plan view which looked at 3, 4B, 5R, 5G, and 5B in the -Z direction.

Referring again to FIG. 1, the folding mirror 5
The R light, G light, and B light reflected by R, 5G, and 5B and traveling in the Z direction are mirrors 5 when viewed in the Z direction.
R, 5G, 5B (ie, each mirror 5
R, 5G, 5B) and a polarizing beam splitter 6 disposed on a plane parallel to the XY plane.
R, 6G, and 6B are respectively incident. The direction of arrangement of the polarization beam splitters 6R, 6G, 6B is such that each color light incident on each of the polarization beam splitters 6R, 6G, 6B is converted into two linearly polarized light beams by the polarization separation units of the polarization beam splitters 6R, 6G, 6B. Outgoing direction of reflected linearly polarized light (in this example, s-polarized light) out of the two linearly polarized lights, and incident directions of the respective color lights to the bending mirrors 5R, 5G, and 5B. Are arranged in the same direction.

Each color light incident on the polarization beam splitters 6R, 6G, 6B is changed by the polarization beam splitters 6R, 6R.
The reflective liquid crystal light valves 7R, 7G, and 7B are arranged on the surface that transmits G and 6B, respectively.

Referring also to FIG. 4, the polarization beam splitter 6
The functions of R, 6G, 6B and light valves 7R, 7G, 7B will be described. Polarization beam splitters 6R, 6G,
6B is incident on the polarization beam splitter 6.
The light is polarized and separated by the R, 6G, and 6B polarization separation units into P-polarized light transmitted through the polarization separation unit and S-polarized light reflected by the polarization separation unit. In the present embodiment, the reflected S-polarized light is discarded. On the other hand, the polarization beam splitters 6R, 6G, and 6B are transmitted through the polarization splitting section.
Is incident on the reflective liquid crystal light valves 7R, 7G, 7B arranged immediately after the light is emitted.

Here, the reflection type light valve, in particular, the electric writing type reflection type light valve employed as the light valves 7R, 7G, 7B in the present embodiment will be described with reference to FIG. However, in the present embodiment, as a matter of course, a light-writing reflective light valve may be employed as the light valves 7R, 7G, 7B. FIG. 8 is a schematic cross-sectional view showing an example of an electric writing type reflective light valve. As shown in FIG. 8, the electric writing type reflection type light valve has a transparent glass substrate 3.
01, transparent ITO electrode 302, liquid crystal alignment film 303, TN
Liquid crystal layer 304, liquid crystal alignment film 305, reflective electrode 306, conductors 307 and 308 connecting between reflective electrode 306 and TFT drain 312, TFT drain 312, TFT gate 310, TFT source 311, TFT oxide layer 30
9 and a silicon substrate 313. FIG.
314 is a TFT source diffusion region, and 315 is a TFT drain diffusion region. When a voltage is applied to the gate 310, the TFT switches and the drain 31
A voltage is applied between the electrode 306 and the opposing electrode 302 via 2, and the liquid crystal molecules at that location are arranged in parallel with each other, and the liquid crystal layer 304 at that location acts as a quarter-wave 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 polarized light whose polarization direction is shifted by 90 degrees. On the other hand, at a place where no voltage is applied to the gate 310, the TFT is not switched, so that no electric field is generated between the electrode 306 and the counter electrode 302, and the liquid crystal molecules are aligned with the alignment films 303 and 30.
5, the incident light is turned and imitated according to the liquid crystal molecules, reflected by the metal electrode 306,
The light is again rotated in accordance with the twist of the liquid crystal molecules, and is emitted as polarized light having the same polarization direction as the incident light. The polarization direction and polarization direction of the incident light are 90
It is possible to emit polarized light shifted by a degree. 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 type reflective light valve having such a structure, the TFT can be arranged below the electrode 306, so that the area of the electrode 306 can be increased and the aperture ratio can be significantly increased. be able to.

Referring again to FIG. 1 and FIG. 4, the P-polarized R light, G light which has been color-separated by the cross dichroic mirror 3 and incident on the light valves 7R, 7G, 7B respectively.
The light and the B light are modulated and reflected by the image signals for the respective colors, and are reflected as modulated light, respectively.
G, 7B, and the polarization beam splitter 6
R, 6G, and 6B are respectively incident. As can be seen from the principle of the electric writing reflective light valve described above,
In the modulated light of each color, S-polarized light at a location where a voltage is applied according to the image signal for each color and P-polarized light at a location where no voltage is applied are mixed. The modulated light that has entered the polarization beam splitters 6R, 6G, and 6B is analyzed by the polarization beam splitters 6R, 6G, and 6B, respectively. That is, only the S-polarized light of the modulated light of each color is reflected by the polarization splitters of the polarization beam splitters 6R, 6G, and 6B, respectively, and travels toward the dichroic prism 8 as a color combining optical system (that is, detection). The P-polarized light of the modulated light of each color passes through the polarization beam splitters 6R, 6G, and 6B and is discarded in the −Z direction.

Each polarizing beam splitter 6R, 6G, 6B
The analysis light of each color emitted from the above is emitted in a direction opposite to the direction of incidence of the color lights separated by the cross dichroic mirror 3 as the color separation optical system into the bending mirrors 5R, 5G, 5B. The light is incident on a color combining optical system composed of a prism 8.

As can be understood from the above description, the G light and the R light incident on the dichroic prism 8 enter the dichroic prism 8 with optical axes perpendicular to each other, and the B light incident on the dichroic prism 8 is 8, the light enters the dichroic prism 8 with an optical axis that is neither perpendicular nor parallel to the optical axes of the R-light and G-light. In addition, G when entering the dichroic prism 8 as a color combining optical system
The optical axes of the light and the R light are parallel to the optical axes of the G light and the R light when they are emitted from the cross dichroic mirror 3 as a color separation optical system, respectively, and at the same time, when they are incident on the dichroic prism 8. The traveling directions of the light and the R light are different from those of the G light emitted from the cross dichroic mirror 3.
The traveling directions of the light and the R light are opposite to each other. Further, the optical axis of the B light emitted from the cross dichroic mirror 3 is, with respect to the optical axis of the B light when entering the dichroic prism 8, by the bending mirror 4 B before the B light enters the dichroic prism 8. The light beam is once converted into a parallel optical axis, and the traveling direction of the B light on the optical axis is opposite to the traveling direction of the B light when entering the dichroic prism 8.

Here, the dichroic prism 8 constituting the color combining optical system will be described with reference to FIG.
FIG. 5 shows the elements 6R, 6G, 6B, 7R, 7G,
It is the XY plan view which looked at 7B and 8 in the -Z direction. The dichroic prism 8 has three differently shaped triangular prism members 8-1, 8-2, 8-3. The member 8-1 is a triangular prism whose XY cross section is a right-angled isosceles triangle, and the member 8-2 is an acute triangle having an XY cross section (inner angle is 45 degrees as shown in FIG.
α and β. ), And the member 8-3 has an obtuse triangular XY cross-sectional shape (the member 8-3 of the two acute inner angles).
The inner angle on the side of the inner angle α of No. 2 is γ). In the present embodiment, the respective α, β, and γ can be arbitrarily determined under the condition that the sum of the angle α and the angle γ is a right angle. In the present embodiment, the dichroic prism 8 is configured by combining the members 8-1, 8-2, and 8-3 with the dichroic films 8G and 8B interposed therebetween. That is, in the present embodiment, the slope having both the two 45-degree apex angles of the member 8-1 on which the G light reflecting dichroic film 8G is formed in advance, and the apex angle β and the apex angle 45 degrees of the member 8-2 And a slope having both
Laminated with adhesive. The slope having both the apex angle α and the apex angle β of the member 8-2 on which the B light reflecting dichroic film 8B is formed in advance, and the slope having both the apex angle γ and the obtuse angle of the member 8-3 are different. , Glued together. Needless to say, each of the dichroic films 8G and 8R may be formed on the bonding surface of the member to be bonded. FIG. 7A shows an example of the transmittance-wavelength characteristic of the G light reflecting dichroic film 8G, and FIG. 7B shows the transmittance of the B light reflecting dichroic film 8B.
An example of a wavelength characteristic is shown. With the above configuration, each member 8-
After bonding 1, 8-2 and 8-3, the surface 8-1-b of the member 8-1 and the surface 8-2-a of the member 8-2 constituting the dichroic prism 8 are parallel to each other, Member 8
-1 and the surface 8-3-b of the member 8-3 are parallel to each other, and the surfaces 8-1-b and 8-2-a and the surfaces 8-1-a and 8 It becomes a right angle with -3-b.

The modulated light emitted from the light valve for R light 7R enters the polarization beam splitter 6R, is polarized and separated by the polarization splitter of the polarization beam splitter 6R, and is analyzed. Out of the polarizing beam splitter 6R in the −Y direction, and the dichroic prism 8
Are incident perpendicularly to the surface 8-1-a of the member 8-1 that constitutes. The analysis light of the R light incident on the surface 8-1-a passes through the dichroic films 8G and 8B, and the surface 8-3 of the member 8-3.
The light exits from the dichroic prism 8 perpendicularly to -b (that is, in the -Y direction).

The modulated light emitted from the G light valve 7G enters the polarization beam splitter 6G, is polarized and separated by the polarization splitter of the polarization beam splitter 6G, and is analyzed. , In the X direction, from the polarizing beam splitter 6G, and perpendicularly enter the surface 8-2-a of the member 8-2 forming the dichroic prism 8. The analysis light of the G light incident on the surface 8-2-a is reflected by the G light reflection dichroic film 8G, changes its optical axis in the -Y direction, passes through the dichroic film 8B, and transmits the member 8-3.
Out of the dichroic prism 8 perpendicularly to the surface 8-3-b (that is, in the -Y direction).

The light emitted from the light valve 7B for B light enters the polarization beam splitter 6B, is polarized and separated by the polarization beam splitter of the polarization beam splitter 6B, and is analyzed. The light is reflected by the polarization splitting unit and emitted from the polarization beam splitter 6B. The direction in which the detection light of the B light is emitted from the polarization beam splitter 6B is a direction perpendicular to the surface of the member 8-3 constituting the dichroic prism 8. The analysis light of the B light incident on the member 8-3 is
The surface 8-3-b undergoes total internal reflection, and is then reflected by the B light reflecting dichroic film 8B to form a surface 8-3 of the member 8-3.
Light is emitted perpendicular to -b (that is, in the -Y direction).

The above is the description of the dichroic prism 8 as a color combining optical system. The angles α, β, γ and the shape of the member 8-3 are further adjusted so that the B light is applied to the entire inner surface so as to satisfy the aforementioned conditions. In order to satisfy the condition of reflection, the prism member 8-1 is further arranged so that the emission optical axes of the R light, G light and B light emitted from the dichroic prism 8 coincide with each other and are perpendicular to the surface 8-3-b. , 8-2, 8-3. The light valves 7R, 7
The light path length of each color light is set to be the same from G and 7B to the dichroic prism 8 through the polarizing beam splitters 6R, 6G and 6B.

In this embodiment, since the dichroic films 8G and 8B have the characteristics shown in FIGS. 7A and 7B, respectively, the R light is emitted from the dichroic films 8R and 8B.
Therefore, both dichroic films 8G and 8B have a characteristic that their characteristics can be determined by setting a wavelength that is a boundary between the reflection wavelength region and the transmission wavelength region. In other words, if the characteristic shown in FIG. 7A is shifted to the shorter wavelength side as it is, the characteristic shown in FIG. 7B is obtained. Therefore, the design of the dichroic films 8G and 8B becomes very easy. In addition, there is an advantage that a film with less variation in characteristics due to the incident angle of the incident light beam can be achieved.

As described above, each color light valve 7R,
The modulated light of each color, which has been modulated by 7G and 7B and detected by the polarization beam splitter, is color-combined by the dichroic prism 8, and the combined light is emitted from the dichroic prism 8 in the -Y direction. Will be. And
The combined light emitted from the dichroic prism 8 enters a projection lens (not shown) as a projection optical system,
It is projected as a full-color projection image on a screen (not shown).

The basic configuration of the projection display device according to one embodiment of the present invention has been described above. Next, the projection type display device of the present embodiment in which the integrator 1 and the illumination relay optical system and the like are arranged in the basic configuration described above,
This will be described with reference to FIG. FIG. 2 is a schematic perspective view showing a specific configuration of the projection display device according to the present embodiment. 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. 2, X, Y, and Z axes orthogonal to each other are defined as in FIG.

FIG. 2 shows a light source 99, an integrator 1, an illumination relay optical system, and a projection lens 106 as a projection optical system in addition to the basic configuration shown in FIG. First, the projection lens 106 will be described.
The combined light emitted from the dichroic prism 8 as the color combining optical system enters a projection lens 106 and is projected on a screen (not shown) by the projection lens 106. The projection lens 106 has an aperture stop (not shown),
It has a structure having a rear lens group on the screen side with respect to the aperture stop and a front lens group on the dichroic prism 8 side with respect to the aperture stop. The projection lens 106 in the present embodiment is an optical system that is telecentric on the front side. That is, a principal ray (a ray passing through the center of the aperture stop (including an off-axis ray)) determined by the aperture stop of the projection lens 106 is
At the front side (opposite side of the screen) is parallel to the optical axis.

In the present embodiment, the light source 99 is composed of a lamp (not shown) and an elliptical mirror which is a concave mirror. The lamp is arranged at a position of a first focal point of the elliptical mirror. The light source light emitted from the lamp is focused on the second focal point of the elliptical mirror. In the present embodiment, the integrator 1 is formed of a rectangular parallelepiped transparent optical glass, and is arranged such that the incident end face (the end face on the side closer to the light source 99) of the integrator 1 is located at the second focal point. Therefore, the light source light is focused on the end face of the integrator 1 and enters the integrator 1.
The light source light that has entered the integrator 1 is reflected from the inner surface of the integrator 1 a plurality of times, and then emitted from the end surface of the integrator 1 opposite to the incident end surface. A surface light source having a uniform light intensity distribution is formed on the exit end face of the integrator 1.
In other words, the output end face is illuminated in a superimposed manner by light from virtual images of a plurality of light sources formed at the position of the incident end face by internal reflection of the integrator 1.

As shown in FIG. 2, the light emitted from the exit end face of the integrator 1 travels in the −Y direction, the direction of the optical axis is changed to the −X direction by the bending mirror 2, and the illumination relay optical system is changed. The light enters the cross dichroic mirror 3, which is the color separation optical system, via the front group illumination lens 101 having the focal length f1. The light incident on the cross dichroic mirror 3 is transmitted by the cross dichroic mirror 3 as it is, and passes through the cross dichroic mirror 3 as it is and travels in the −X direction, and is reflected by the R light reflecting dichroic mirror 3R and travels in the Y direction. The light is separated into R light and B light reflected by the B light reflecting dichroic mirror 3B and traveling in the −Y direction.

Of the color lights separated by the cross dichroic mirror 3, the R light and the G light are reflected by the bending mirrors 5R and 5G, respectively, change their optical axis directions to the Z direction, and travel in the Z direction. And a rear-group illumination lens 1 for R light having a focal length f2 which constitutes an illumination relay optical system.
Rear group illumination lens 10 for G light of 02R and focal length f2
After passing through 2G, the polarization beam splitters 6R, 6G
Respectively.

The distance between the exit end face of the integrator 1 and the front group illumination lens 101 is defined as the focal length f1 of the lens 101, and the principal ray determined by the aperture stop of the projection lens 106 has an optical axis between them. Is parallel to. That is, the front group illumination lens 101 forms a telecentric optical system on the front side (integrator 1 side). Further, the distance between the front group illumination lens 101 and the rear group illumination lenses 102R and 102G is f1 + f, respectively.
It is 2. That is, the rear focal position of the front group illumination lens 101 matches the front focal position of the rear group illumination lenses 102R and 102G. Therefore, the principal ray is divided into the front group illumination lens 101 and the rear group illumination lens 102R,
102G intersects at the pupil position, and is parallel to the optical axis on the rear side of the rear group illumination lenses 102R and 102G. That is, the rear group illumination lenses 102R and 102G
A telecentric optical system is configured on the rear side. After all, the relay optical system for R light composed of the front group illumination lens 101 and the rear group illumination lens 102R and the relay optical system for G light composed of the front group illumination lens 101 and the rear group illumination lens 102G are: , Each constitute a telecentric optical system on the front side and the rear side.

R light that has entered the polarizing beam splitters 6R and 6G via the rear group illumination lenses 102R and 102G,
Of the G light, the P-polarized light that has passed through the polarization beam splitters 6R and 6G respectively reaches the light valves 7R and 7G. However, the distance between the rear group illumination lenses 102R and 102G and the light valves 7R and 7G is different from each other. Lens 102
The focal length is f2 for R and 102G.

The relay optical system for R light composed of the front group illumination lens 101 and the rear group illumination lens 102R described above, and the front group illumination lens 101 and the rear group illumination lens 102G.
The polarization beam splitters 6R and 6G and the light valves 7R and 7G are arranged at positions where the chief rays have telecentricity. Further, the R and G relay optical systems form images of the output end face of the integrator 1 (surface light source formed by the integrator 1) with the R and G lights on the liquid crystal light valves 7R and 7G, respectively. Imaged. In other words, the R and G relay optical systems achieve critical illumination of the light valves 7R and 7G with the R light and the G light, respectively. In the present embodiment, the image of the exit end face of the integrator 1 is determined by the focal length f1 of the front group illumination lens 101 and the focal length f2 of the rear group illumination lenses 102R and 102G constituting the above-described relay optical system. The image is magnified by a certain magnification and formed on the light valves 7R and 7G. For this reason, it is preferable that the shape of the end surface of the integrator 1 is formed in proportion to the shape of the image display surface of the light valves 7R and 7G in order to achieve efficient illumination.

The B light color-separated by the cross dichroic mirror 3 as the color separation optical system exits the cross dichroic mirror 3 and travels in the -Y direction. In the present embodiment, this has already been described. As described above, since the incident direction of the B light of the dichroic prism 8 used as the color synthesizing optical system does not coincide with either the X direction or the Y direction, as described below, the R light and the G light An optical system different from the optical system is used. After exiting the cross dichroic mirror 3,
The B light traveling in the Y direction passes through the rear group illumination lens 103B for the B light having the focal length f3, and changes the direction of the optical axis to a direction parallel to the XY plane by the bending mirror 4B.
After passing through the front group illumination lens 104B of the focal length f4 constituting the relay optical system of FIG.
Then, the light enters the polarization beam splitter 6B via the rear group illumination lens 105B of the focal length f5 constituting the second relay optical system for the B light. Then, of the B light incident on the polarization beam splitter 6B, only the P-polarized light transmitted through the polarization separation unit of the polarization beam splitter 6B is incident on the light valve 7B. Rear group illumination lens 103B
Constitutes a first relay optical system for B light together with the front group illumination lens 101 which also serves as a part of the relay optical system for R light and the relay optical system for G light. The distance between the front group illumination lens 101 and the rear group illumination lens 103B is f1 + f3. That is, the rear focal position of the front group illumination lens 101 matches the front focal position of the rear group illumination lens 103B. Therefore, the primary image of the output end face of the integrator 1 due to the B light is shifted by the focal length f.
1, the size determined by f3, the rear group illumination lens 103
It is formed at a distance f3 from the lens 103B on the emission side of B. Front group illumination lens 104B and rear group illumination lens 105B constituting a second relay optical system for B light
The interval between them is f4 + f5. That is, the rear focal position of the front group illumination lens 104B and the rear group illumination lens 1
The front focal position of 05B matches. The distance between the rear group illumination lens 105B and the light valve 7B is
f5. Therefore, the image (secondary image) of the primary image by the B light on the exit end face of the integrator 1 is used as the illumination lens 10 constituting the second illumination relay lens for the B light.
4B and 105B form an image on the light valve 7B. That is, the light valve 7B is critically illuminated by the B light. In addition, the aforementioned B
The first and second relay optical systems make the principal ray parallel to the optical axis between the illumination lens 103B and the illumination lens 104B and between the illumination lens 105B and the light valve 7B. Therefore, the polarizing beam splitter 6B and the light valve 7B are arranged at positions where the principal ray has telecentricity by the first and second relay optical systems for the B light described above.

In this embodiment, the front group illumination lens 101, the rear group illumination lens 102R, the rear group illumination lens 102G, the rear group illumination lens 103B, and the second group for the B light are used.
Relay optical systems (the front group illumination lens 104B and the rear group illumination lens 105B) constitute an illumination relay optical system that forms an image of the surface light source formed by the integrator 1 on the light valves 7R, 7G, and 7B, respectively. doing.

The modulated lights modulated by the respective color light signals emitted from the light valves 7R, 7G, 7B are, as described above, polarized light beam splitters 6R, 6G, 6B for the respective color lights.
Are analyzed by the polarization separation units, and the analysis light of each color light is incident on the dichroic prism 8. Then, as described above, the analysis light of each color light is color-combined by the dichroic prism 8, emitted from the dichroic prism 8 in the -Y direction, and projected on the screen by the projection lens 106.

The principal rays determined by the aperture stop of the projection lens 106 are the light valves 7R and 7R for each color light.
G, 7B to the polarization beam splitters 6R, 6 for each color light
G, 6B and the dichroic prism 8 reach the projection lens 106, and are parallel to the optical axis. That is, the polarization beam splitters 6R, 6G, and 6B for the respective color lights and the dichroic prism 8 as the color combining optical system are arranged at positions where the principal rays maintain telecentricity.

The dichroic films 8G and 8B for performing color synthesis by the color synthesis optical system are formed by laminating dielectric films in multiple layers, and these films 8G and 8B reflect light according to the incident angle of incident light rays. The characteristics have different characteristics. For this reason, if the angles of incidence on the films 8G and 8B differ for each off-axis principal ray, color shading will occur on the screen. In this regard, according to the present embodiment, the dichroic prism 8 as a color combining optical system
Since the principal ray is located at a position having telecentricity, color shading due to the incident angle characteristic of the principal ray of the color combining optical system does not occur.

Further, the polarization beam splitters 6R, 6G,
If the incident angle of the off-axis chief ray is also different in 6B, the polarization separation characteristics will be different, and as a result, contrast unevenness will occur in the projected image. In this regard, in the present embodiment, the polarization beam splitters 6R, 6G, 6B for the respective color lights are used.
Since the principal ray is disposed at a position having telecentricity, there is no occurrence of contrast unevenness of the projected image due to the incident angle characteristic of the principal ray of the polarizing beam splitters 6R, 6G, 6B.

Further, the liquid crystal light valves 7R, 7G, 7
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 this embodiment, since the light valves 7R, 7G, and 7B are arranged at positions where the principal ray has telecentricity, the light valve 7
There is no unevenness in the contrast of the projected image due to the incident angle characteristics of the principal rays of R, 7G, and 7B.

In the present embodiment, the color separation optical system and the color synthesis optical system are configured as separate optical systems, and the dichroic prism 8 as the color synthesis optical system includes
Only polarized light is incident. Therefore, the dichroic films 8G and 8B of the dichroic prism 8 only need to obtain desired dichroic characteristics only for the incident S-polarized light, and can improve the dichroic characteristics for the incident S-polarized light. . For this reason, the color synthesis characteristics can be improved without impairing the color separation characteristics, and the image quality of the projected image can be improved.

Further, in the present embodiment, as described above, after the light from the light source 99 is color-separated by the cross dichroic mirror 3, the color-separated color lights correspond to the respective color lights. The polarization beams splitters 6R, 6G, 6B provided are respectively polarized, the polarization lights of the respective color lights are modulated by the respective light valves 7R, 7G, 7B, respectively, and the modulation light of the respective color lights is converted into the respective polarization beam splitters 6R. , 6G, and 6B. As described above, since each of the polarization beam splitters 6R, 6G, and 6B separates not the white light but each of the color lights after color separation, each of the polarization beam splitters 6R, 6G, and 6B converts the light into the light in the narrow band wavelength range. Polarization separation will be performed only for this. Therefore, each polarization beam splitter 6R, 6G,
Since the wavelength range of the light to be polarization-separated in 6B is limited to a narrow band, each polarization beam splitter 6R, 6G,
6B can be improved, and as a result, the contrast of the projected image can be improved.

Further, in the present embodiment, as described above, the dichroic prism 8 constituting the color synthesizing optical system is arranged such that the light emitted from the light valves 7R, 7G, 7B for each color light is arranged for each color light. After being analyzed by the polarized beam splitters 6R, 6G, and 6B, the polarized lights of the respective color lights are color-combined by the dichroic prism 8. For this reason, when each color light passes through the three constituent members 8-1, 8-2, 8-3 constituting the dichroic prism 8, the polarization direction changes due to the birefringence of the material, The combined color light is applied to the dichroic prism 8.
Is emitted and projected on the screen by the projection lens 106, the contrast of the projected image does not deteriorate.
For this reason, it is not necessary to use a high-priced material having a small birefringence as the members 8-1, 8-2, and 8-3.

Since the cross dichroic mirror has a structure in which two dichroic mirrors are arranged in an X-shape, if the cross dichroic mirror is used as a color separation optical system, generally, the two dichroic mirrors are used. The intersections affect the projected image and cause color unevenness. In this regard, in the present embodiment, the cross dichroic mirror 3, which is a color separation optical system, includes the front group illumination lens 101 and the rear group illumination lenses 102R, 102R for each color.
Since the light flux passing through the intersection of the mirrors 3R and 3B of the cross dichroic mirror 3 spreads on the light valves 7R, 7G and 7B since it is disposed between the light valves 7R and 7B, it is caused by the intersection. Color unevenness of the projected image can be prevented.

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

For example, in the above-described embodiment,
Triangular prism shaped optical members 8-1 and 8- as color synthesis optical system
Although the dichroic prism member 8 is formed by bonding the members 2 and 8-3 with the dichroic films 8B and 8G interposed therebetween, a gap may be provided between the members 8-2 and 8-3. In that case, the dichroic film 8B is formed on the member 8-3 side.

Further, R light, G light to triangular members 8-1, 8-2, 8-3 constituting the dichroic prism 8
Preferably, an antireflection film is formed on the light and B light incident surfaces.

In the above-described embodiment, a rectangular parallelepiped rod integrator is used as the integrator 1, but a fly-eye lens integrator may be used instead. Further, instead of using a lamp and an elliptical mirror as the light source 99, for example, a lamp and a parabolic mirror or a spherical mirror can be used.

Further, in the above-described embodiment,
The cross dichroic mirror 3 is used as the color separation optical system. However, as the color separation optical system, two flat dichroic mirrors are arranged in parallel or at a right angle without crossing, or a color separation like a cross dichroic prism. An optical system in which the first and second color lights of the respective color lights are emitted in directions opposite to each other and the third color light is emitted at right angles to the former can also be used.

[0069]

As described above, according to the present invention,
The color synthesis characteristics can be improved without impairing the color separation characteristics, and the image quality of the projected image can be improved.

Further, 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 polarizing 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, the light valve, the polarizing beam splitter and the color combining optical system are arranged at a position where the principal ray determined by the aperture stop of the projection optical system has telecentricity parallel to the optical axis. By doing so, the contrast unevenness of the projected image caused by the incident angle characteristic of the principal ray of the light valve, the contrast unevenness of the projected image caused by the incident angle characteristic of the principal ray of the polarizing beam splitter, and the principal ray of the color combining optical system Color shading caused by the incident angle characteristic of the image can be eliminated.

[Brief description of the drawings]

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

FIG. 2 is a schematic perspective view showing a specific configuration of the projection display device according to the embodiment of the present invention.

FIG. 3 is a schematic plan view showing a part of the projection display device according to the embodiment of the present invention.

FIG. 4 is a diagram illustrating functions of a light valve and a polarizing beam splitter.

FIG. 5 is a schematic plan view showing another part of the projection display device according to the embodiment of the present invention.

FIG. 6 is a diagram illustrating an example of a characteristic of a dichroic film of each dichroic mirror constituting a cross dichroic mirror as a color separation optical system.

FIG. 7 is a diagram illustrating characteristics of each dichroic film of a dichroic prism as a color combining optical system.

FIG. 8 is a schematic sectional view showing an example of an electric writing type reflection type light valve.

FIG. 9 is a schematic configuration diagram illustrating an example of a conventional projection display device.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Integrator 2 Folding mirror 3 Cross dichroic mirror (color separation optical system) 4B, 5B, 5G, 5R Folding mirror 6R, 6G, 6B Polarization beam splitter 7R, 7G, 7B Electric writing reflective liquid crystal light valve 8 Dichroic prism (color Synthetic optical system) 99 Light source 101 Front group illumination lens 102R, 102G, 103B Rear group illumination lens 104B Front group illumination lens 105B Rear group illumination lens 106 Projection lens

Claims (8)

[Claims] 1. A color separation optical system that separates light from a light source into first, second, and third color lights, and a color separation optical system that modulates the first, second, and third color lights, respectively. A first, a second, and a third light valve; a color combining optical system for combining the first, second, and third color lights modulated by the first, second, and third light valves, respectively; A projection optical system for projecting light that has been color-combined by the color-combining optical system; anda projection-type display device comprising: a color separation optical system comprising a cross dichroic mirror, a cross dichroic prism, or a plurality of flat dichroic mirrors. The color synthesizing optical system can be assembled by bonding three differently shaped triangular prism members with a dichroic film therebetween or facing each other with a gap therebetween. A projection-type display device comprising a dichroic prism having the same. 2. The first and second color lights incident on the dichroic prism constituting the color synthesizing optical system enter the dichroic prism with optical axes perpendicular to each other, and constitute the color synthesizing optical system. The third color light incident on the dichroic prism is the first color light incident on the dichroic prism constituting the color combining optical system.
2. The projection display device according to claim 1, wherein the light enters the dichroic prism with an optical axis that is neither perpendicular nor parallel to the optical axis of the second color light. 3. A first light source for emitting light from the color separation optical system.
And the optical axis of the second color light is parallel to the optical axis of the first and second color light when entering the dichroic prism constituting the color combining optical system, respectively.
The traveling directions of the first and second color lights when exiting from the color separation optical system are respectively the same as the traveling directions of the first and second color lights when entering the dichroic prism constituting the color synthesis optical system. Conversely, the optical axis of the third color light emitted from the color separation optical system, the third color light, before entering the dichroic prism constituting the color synthesis optical system, the color synthesis optical system When the light is incident on the dichroic prism, the light is once converted into an optical axis parallel to the optical axis of the third color light, and the traveling direction of the third color light on the optical axis constitutes the color synthesis optical system. 3. The projection display device according to claim 2, wherein the direction of travel of the third color light when entering the dichroic prism is opposite to the direction of travel. 4. The apparatus according to claim 1, further comprising: first, second, and third polarization beam splitters provided corresponding to the first, second, and third color lights separated by the color separation optical system, respectively. The first, second, and third polarization beam splitters respectively separate the first, second, and third color lights color-separated by the color separation optical system into two polarization lights, and The second and third light valves are the first,
The first, second, and third polarization beam splitters respectively modulate one of the first, second, and third color lights that have been polarization-separated by the second and third polarization beam splitters. The first, second, and third polarization beam splitters The first, second and third color valves modulated by the first, second and third light valves are respectively analyzed, and the color synthesizing optical system is configured to detect the first, second and third color light. 4. The projection display device according to claim 1, wherein the first, second, and third color lights detected by the polarizing beam splitter are combined. 5. The first, second and third light valves, the first, second and third polarization beam splitters and the color combining optical system are determined by an aperture stop of the projection optical system. The projection display device according to claim 4, wherein the principal ray is arranged at a position having telecentricity. 6. An integrator receiving light from the light source to form a surface light source, and forming an image of the surface light source formed by the integrator on the first, second, and third light valves, respectively. The projection type display device according to claim 5, further comprising: an illumination relay optical system for forming an image. 7. The illumination relay optical system further includes a front group disposed on a front side of the color separation optical system, and a second group disposed on a rear side of the color separation optical system and color-separated by the color separation optical system. A first, second, and third rear group provided for each of the first, second, and third color lights, and the surface light source using a third color light formed by the front group and the third rear group; 7. The projection display device according to claim 6, further comprising: a relay optical system that forms an image of the image on the third light valve. 8. The first color light emitted from the color separation optical system is the same as the optical axis and the traveling direction when the light incident on the color separation optical system is incident on the color separation optical system. The second and third color lights emitted from the color separation optical system in the traveling direction, and emitted from the color separation optical system,
The first color light emitted from the color separation optical system is emitted from the color separation optical system with an optical axis perpendicular to the optical axis of the first color light, and the second and third light emitted from the color separation optical system are emitted from the color separation optical system.
The traveling directions of the color lights are opposite to each other. The second color light incident on the color combining optical system is transmitted through the color combining optical system, the first color light is green light, and the second color light is Is a red light, and the third color light is a blue light. 9. The projection display device according to claim 1, wherein the third color light is a blue light.