JP2004361471A - Color separation optical system and projection type display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a color separation optical system in which optical path lengths from a light source up to an object to be irradiated or a light bulb becomes equal to one another without using a cross dichroic mirror, and to provide a projection type display device. <P>SOLUTION: The light from a light source having first color light, second color light, and third color light are polarized and split by a polarized light beam splitter, and the first color light of this light passes through a first dichroic mirror, and the mixed light of the second color light and the third color light is reflected and made incident on the polarized light beam splitter. The polarization direction of the mixed light is rotated through quarter-wave phase plates placed on the incident and exit planes of the first dichroic mirror and reflected by the polarized light beam splitter, and is separated into the second color light and the third color light by a second dichroic mirror. The first dichroic mirror is arranged at the position where the light path lengths of each color light up to the objects to be irradiated which is irradiated with each color light become equal. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a projection display device.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, a projection display device has a configuration in which light emitted from a reflection type light valve is polarized and separated by a polarization beam splitter and analyzed, and the analyzed light is color-synthesized by a cross dichroic prism and then projected by a projection lens. Is known (Patent Document 1).
[0003]
FIG. 5 is a diagram showing a configuration of such a conventional projection display device. The light emitted from the light source 51 is incident on a B (blue) light reflecting dichroic mirror 52 that is arranged obliquely so as to have an angle of 45 degrees with respect to the optical axis, and reflects the reflected B light and transmitted R (red) light. ) It is color-separated into mixed light of light and G (green) light. The mixed light of the R light and the G light further enters the G light reflecting dichroic mirror 53 disposed on the optical axis in parallel with the B light reflecting dichroic mirror 52, and the G light reflected by the G light is reflected by the G light reflecting dichroic mirror. Decomposed.
[0004]
The B light reflected by the B light reflecting dichroic mirror 52 is deflected by the reflecting mirror and is incident on the polarization beam splitter 54B. The light enters the reflective light valve 55B disposed in the vicinity.
[0005]
The G light and the R light that have been color-separated by the G light reflecting dichroic mirror 53 are incident on polarization beam splitters 54G and 54R arranged for the respective lights, are reflected by the polarization separation units, and are emitted. Incident on the reflection type light valves 55G and 55R arranged near the exit surface of the light source.
[0006]
Each color light incident on the reflective light valve for each color light is reflected and emitted after being modulated by each color signal, re-enters the polarization beam splitter for each color light, and the light that passes through the polarization separation unit is the analysis light. After being incident on the cross dichroic prism 56, which is a color synthesizing optical system, from different surfaces to be color synthesized, the light is incident on the projection lens 57, and a full-color enlarged image is projected on a screen (not shown).
[0007]
In such a projection display device, the optical path length from the light source to the reflective light valve for each color light is the same for R light and G light, but the optical path length for B light is longer than the optical path length for R light and G light. Therefore, a relay lens had to be arranged in the optical path of the B light.
[0008]
In order to solve this problem, projection display devices in which the optical path length of each color light is equal are known (Patent Documents 2 and 3). This projection display device uses a cross dichroic mirror combining two dichroic mirrors in order to separate light from a light source into B light and mixed light of R light and G light. The optical path lengths from the mirror to the light valve for each color light are configured to be equal.
[0009]
[Patent Document 1]
Japanese Patent No. 2599309 (FIG. 13)
[0010]
[Patent Document 2]
JP-A-8-234156 (FIG. 1)
[0011]
[Patent Document 3]
JP-A-10-133301 (FIG. 1)
[0012]
[Problems to be solved by the invention]
However, in the above-mentioned projection type display device, the optical path length of each color light from the light source to the light valve for each color light is equal, but since the cross dichroic mirror is used, it is difficult to assemble and adjust the cross dichroic prism, and the projection type display device There is a problem that adjustment of the optical system of the display device is also difficult.
[0013]
The present invention has been made in view of such a problem, and provides a color separation optical system and a projection display device in which an optical path length from a light source to a light valve is equal without using a cross dichroic mirror. With the goal.
[0014]
[Means for Solving the Problems]
In order to solve the above problem, the invention according to claim 1 is a polarization beam splitter that separates and emits light from a light source having first color light, second color light, and third color light, and the polarization beam splitter. The light emitted from the light source is separated into the first color light and the mixed light of the second color light and the third color light, and any one of the first color light and the mixed light is reflected. A first dichroic mirror to be incident on the polarizing beam splitter; and a first dichroic mirror disposed on an incident surface side of the first dichroic mirror on which light from the light source is incident and an emission surface side on which transmitted light is emitted. A color separation optical system comprising: a four-wavelength phase plate; and a second dichroic mirror that separates the mixed light into the second color light and the third color light.
[0015]
According to a second aspect of the present invention, in the color separation optical system according to the first aspect, each of the color lights separated from the first dichroic mirror by the first dichroic mirror and the second dichroic mirror. Are characterized in that the optical path lengths of the respective color lights to the irradiation object irradiated by the light source are equal.
[0016]
According to a third aspect of the present invention, in the color separation optical system according to the first or second aspect, the polarization beam splitter is a wire grid polarization beam splitter.
[0017]
According to a fourth aspect of the present invention, there is provided a color separation optical system that separates light from a light source into first color light, second color light, and third color light, and each color that modulates and emits the color separated color light. A light valve disposed for each color, a color synthesizing optical system for color synthesizing the respective color lights emitted from the light valve, and a projection lens for projecting the color synthesized light, wherein A polarizing beam splitter that separates the light from the light source into polarized light and emits the light; and emits the light from the light source emitted from the polarized beam splitter to the first color light, the second color light, and the third color light. And a first dichroic mirror that reflects one of the first color light and the mixed light to be incident on the polarization beam splitter, and a light source of the first dichroic mirror. of A quarter-wave phase plate disposed on the incident surface side where light is incident and on the exit surface side where transmitted light exits, respectively, and a second plate that separates the mixed light into the second color light and the third color light And a dichroic mirror.
[0018]
According to a fifth aspect of the present invention, in the projection display device according to the fourth aspect, the optical path lengths of the respective color lights from the first dichroic mirror to the light valves arranged for the respective color lights are equal. Features.
[0019]
According to a sixth aspect of the present invention, in the projection display device according to the fourth or fifth aspect, the polarization beam splitter is a wire grid polarization beam splitter.
[0020]
According to a seventh aspect of the present invention, in the projection display device according to any one of the fourth to sixth aspects, the light valve is a transmissive light valve.
[0021]
The invention according to claim 8 is the projection type display device according to any one of claims 4 to 6, wherein the light valve is a reflection light valve.
[0022]
According to a ninth aspect of the present invention, in the projection display device according to any one of the fourth to eighth aspects, the color combining optical system is a cross dichroic prism.
[0023]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
(1st Embodiment)
The first embodiment will be described with reference to FIG. FIG. 1 is a plan configuration diagram of a projection display device according to a first embodiment of the present invention. The directions shown in FIG. 1 are defined as an X axis, a Y axis, and a Z axis. The Z-axis direction is perpendicular to the paper. Light emitted from a light source having a component of R (red) light, G (green) light, and B (blue) light emitted in the X-axis direction from a light source 101 composed of a lamp and a parabolic concave mirror is: The polarized light is converted by the polarization converter 102 into polarized light having a vibration direction perpendicular to the optical axis and parallel to the XY plane. The polarized light emitted from the polarization conversion device 102 enters a wire grid polarization beam splitter 103. The wire grid polarization beam splitter 103 is a polarization beam splitter in which aluminum thin films are formed in a grid shape at predetermined intervals on a glass substrate. The wire grid polarization beam splitter 103 is perpendicular to the XY plane and is inclined by 45 degrees with respect to the optical axis of the incident light, and the wire grid is arranged in a direction to transmit the incident polarized light. The light from the light source that has passed through the wire grid polarization beam splitter 103 has a further improved degree of polarization, enters the quarter-wave phase plate 105, is converted into circularly polarized light, and is then arranged perpendicular to the optical axis. The reflected R light and G light are incident on the dichroic mirror 104 having the property of transmitting the B light, and the mixed light of the R light and G light reflected by the dichroic mirror 104 and the transmitted B light Color separation. The dichroic mirror 104 is disposed substantially at the center of the optical path between the polarization beam splitter 103 and a deflection mirror 108 described later. Note that the quarter-wave phase plate 105 is arranged on the incident surface side of the dichroic mirror 104 so that its optical axis is inclined at 45 degrees with respect to the polarization direction of light from a polarized light source.
[0024]
The B light transmitted through the dichroic mirror 104 is incident on a quarter-wave phase plate 106 disposed on the exit surface side, and is converted into polarized light having a vibration direction in a direction perpendicular to the XY plane. The optical axis of the quarter-wave phase plate 106 is arranged in the same direction as the optical axis of the quarter-wave phase plate 105. The B light emitted from the quarter-wave phase plate 106 changes its traveling direction in the Y-axis direction by the deflection mirror 108, enters the polarization beam splitter 109B, and is reflected by the polarization splitter of the polarization beam splitter 109B. Then, the light exits in the X-axis direction and enters the reflection light valve for B light 110B.
[0025]
The mixed light of the R light and the G light reflected by the dichroic mirror 104 passes through the quarter-wave phase plate 105 again and is converted into polarized light having a vibration direction in a direction perpendicular to the XY plane. The mixed light of the R light and the G light emitted from the を wavelength phase plate 105 is again incident on the wire grid polarization beam splitter 103, but the polarization direction is 90 degrees from the polarization direction of the light emitted from the polarization conversion device 102. Since it is rotating, it is reflected by the wire grid polarization beam splitter 103 in the Y-axis direction. The mixed light reflected by the wire grid polarization beam splitter 103 reflects the G light disposed at an angle of 45 degrees with respect to the optical axis, enters the dichroic mirror 107 having the property of transmitting the R light, reflects. The light is separated into G light traveling in the X-axis direction and R light transmitted and traveling in the Y-axis direction. The color-separated R light and G light enter the polarization beam splitters 109R and 109G arranged for each color light, are reflected by the polarization separation unit, and are emitted from the polarization beam splitters 109R and 109G. The light enters 110R and 110B. Here, the optical path lengths from the dichroic mirror 107 to the polarization beam splitters 109R and 109G are equal. Note that, as shown in FIG. 1, the optical path length from the dichroic mirror 104 to the reflective light valve for each color light is equal for each color light.
[0026]
Each color light incident on the reflection type light valve 110R, 110G, 110B for each color light is reflected and emitted after being modulated by a signal for each color, and re-enters the polarization beam splitter 109R, 109G, 109B for each color light. The modulated light is transmitted through the polarization splitters of the polarization beam splitters 109R, 109G, and 109B, and emitted as analytical light. The emitted analysis light enters the cross dichroic prism 111 constituting the color combining optical system from different surfaces. The cross dichroic prism 111 is a composite prism in which the R light reflecting dichroic film 111R and the B light reflecting dichroic film 11B are arranged perpendicular to the XY plane and perpendicular to each other. The light is reflected by the film 111R, the B light is reflected by the B light reflecting dichroic film 111B, and the G light is transmitted through the R light reflecting dichroic film 111R and the B light reflecting dichroic film 111B to be color-combined. The color-combined light is incident on a projection lens 112, and a full-color image is enlarged and projected on a screen (not shown).
[0027]
In the projection display device of the embodiment described above, the light from the light source is decomposed by the dichroic mirror 104 into B light and mixed light of R light and G light. Since the dichroic mirror 104 is disposed substantially at the center of the optical path between the polarizing beam splitter 103 and the deflecting mirror 108, the optical path length from the dichroic mirror 104 to the reflective light valve for each color light is the same. That is, as is clear from FIG. 1, the distance from the dichroic mirror 104 to the deflecting mirror 108 is equal to the distance from the dichroic mirror 104 to the wire grid polarization beam splitter 103, and the distance between the deflecting mirror 108 and the polarization beam splitter 109B for B light. Is equal to the distance from the wire grid polarization beam splitter 103 to the R light polarization beam splitter 1109R. Therefore, the optical path length from the dichroic mirror 104 to the polarization beam splitter is substantially equal between the B light and the R light. The distances from the dichroic mirror 107 to the polarization beam splitters 109R and 109G are equal. Therefore, in the projection type display device of the present embodiment, the light emitted from the light source 101 is incident on the dichroic mirror 104 as a mixed light of the R light, the G light, and the B light, and the polarization beam splitter 109R for each color light from the dichroic mirror 104. Since the distances to 109G and 109B are configured to be equal, the optical path length between the light source 101 and the polarizing beam splitter is substantially equal for the R light, the G light, and the B light. The distance from the polarizing beam splitter to the reflection type light valve is the same for each color light. Therefore, the optical path length of a specific color light does not differ from the optical path lengths of other color lights, and there is no need to arrange a relay optical system in the optical path. The optical path length of each color light from the reflection type light valve to the projection lens 112 is also equal.
[0028]
In the projection display device of the present embodiment, the dichroic mirror used as the color separation optical system transmits B light, reflects the R light and G light, and the dichroic mirror 104 transmits the R light and reflects the G light. Since there are two dichroic mirrors 107 and the optical path length from the light source to the light valve for each color light can be equal for each color light, the relay optical system can be used even if a cross dichroic prism is used as the color combining optical system. There is no need to place.
Since a cross dichroic mirror combining two dichroic mirrors is not used as the color separation optical system, adjustment of the optical system is facilitated.
[0029]
In this embodiment, the light reflected by the dichroic mirror 104 is a mixed light of the R light and the G light. However, the dichroic mirror 104 is changed to a dichroic mirror having optical characteristics of reflecting the B light and transmitting the R light and the G light. It does not matter. In this case, the dichroic mirror 107 that transmits the R light and reflects the G light is disposed in the optical path of the mixed light of the R light and the G light transmitted through the dichroic mirror 104. On the other hand, the reflected B light is reflected by the wire grid polarization beam splitter 103, and enters the reflection type light valve 110B via the polarization beam splitter 109B. The mixed light of the R light and the G light transmitted through the dichroic mirror 104 passes through the deflecting mirror 108, is decomposed into the R light and the G light by the dichroic mirror 107, and passes through the polarization beam splitters 109R and 109G for each color light. Light enters the light valves 110R and 110G. Also in this case, the optical path lengths from the light source to the reflective light valves for the respective colors of R light, G light and B light can be made substantially equal.
[0030]
As shown in FIG. 1, there is a space between the polarization beam splitters 109R, 109G, and 109B for each color light and the cross dichroic prism 111 of the color combining optical system. Usually, a glass substrate is arranged in this space. By attaching both members, the polarizing beam splitter and the cross dichroic prism are integrated and used. In the present embodiment, the space between the polarizing beam splitters 109R, 109G, and 109B and the cross dichroic prism 111 can be reduced as compared with a projection type display device using a conventional cross dichroic mirror for a color separation optical system. . Conventionally, the optical path length from the center of the cross dichroic prism 111 to the reflective light valves 110R, 110G, 110R for each color light is limited by the size and arrangement of the cross dichroic mirror and the deflecting mirror. However, in the present embodiment, the dichroic mirror 104 sandwiched by the quarter-wave phase plates 105 and 106 is disposed substantially at the center of the optical path of the deflection mirror 108 and the wire grid polarization beam splitter 103 so as to be perpendicular to the optical axis. The optical path length between the grid polarization beam splitter 103 and the deflecting mirror 108 can be shortened, and the polarization beam splitters 109R, 109G, and 109B can be made closer to a cross dichroic prism. The whole can be reduced in size.
(2nd Embodiment)
A second embodiment will be described with reference to FIG. FIG. 2 is a plan configuration diagram of a projection display device according to a second embodiment of the present invention. The same members as those in the first embodiment are denoted by the same reference numerals, and the X-axis, the Y-axis, and the Z-axis are defined as in the first embodiment. The configuration of the present embodiment is the same as that of the first embodiment until the light from the light source is separated into R light, G light, and B light by the two dichroic mirrors 104 and 107. Therefore, description is omitted. The light valve differs between the present embodiment and the first embodiment. In this embodiment, a transmission light valve is used as the light valve.
[0031]
The B light that has been color-separated by the dichroic mirror 104 and polarized by the deflecting mirror 108 enters the deflecting mirror 213, changes its direction by 90 degrees, and enters the B-light transmission light valve 210B. The R light and the G light color-separated by the dichroic mirror 107 are respectively incident on the deflection mirrors 214 and 215 arranged for each color light, are turned by 90 degrees, and are incident on the transmission type light valves 210R and 210G, respectively.
[0032]
Since the projection display device of the present embodiment has the same configuration as that of the first embodiment, each color light can have the same optical path length. Therefore, it is necessary to arrange a relay lens in the optical path of a specific color light. There is no.
[0033]
The transmissive light valves 210R, 210G, 210B for each color light have a configuration in which the liquid crystal panel is sandwiched between polarizing plates, and each color light incident on the liquid crystal panel via the polarizing plate arranged on the incident surface side is converted by a color signal. The modulated polarization direction is changed, the light is analyzed by a polarizing plate arranged on the exit surface side, and the light is extracted as the analysis light. The analyzed color lights enter the cross dichroic prism 211, which is a color combining optical system, from different surfaces. The cross dichroic prism 211 has the same configuration as in the first embodiment. The light synthesized by the cross dichroic prism 211 and emitted is incident on a projection lens 212, and a full-color image is enlarged and projected on a screen (not shown).
[0034]
Also in a projection display device using a transmission type light valve and using a cross dichroic prism as a synthetic optical system, a transmission type light valve for each color light from a light source using two dichroic mirrors as a color separation optical system. Can be made substantially equal for each color light.
[0035]
In this embodiment, similarly to the first embodiment, the optical characteristics of the dichroic mirror 104 may be configured to reflect B light and transmit mixed light of R light and G light.
(Third embodiment)
A third embodiment will be described with reference to FIG. FIG. 3 is a plan configuration diagram of a projection display device according to a third embodiment of the present invention. The same members as those in the first embodiment are denoted by the same reference numerals, and the X-axis, the Y-axis, and the Z-axis are defined as in the first embodiment. In the present embodiment, the overall configuration is the same as that of the first embodiment. However, the wire grid polarization beam splitter 103 of the first embodiment is composed of a composite prism in which two prisms are joined via a polarization separation unit. It is characterized in that the polarizing beam splitter 103a is configured.
[0036]
This embodiment is different from the first embodiment in the position of the dichroic mirror 104. This is because the mixed light of the R light and the G light reflected by the dichroic mirror 104 travels in the prism (glass) of the polarizing beam splitter 103-a, while the B light travels in the air to the polarizing beam splitter 109B. Therefore, even if the distance from the dichroic mirror 104 to the reflective light valve for each color light is equal as in the first embodiment, the optical path length of each color light is not equal. In the first embodiment, since the wire grid polarization beam splitter 103 is used, such a difference in optical path length does not occur. Therefore, the dichroic mirror 104 can be arranged substantially at the center of the optical path between the deflection mirror 108 and the wire grid polarization beam splitter 103.
[0037]
In order to make the optical path from the dichroic mirror 104 to the reflective light valves 114R and 114G for R and G light equal to the optical path length from the dichroic mirror 104 to the reflective light valve 114B for B light, a polarized beam The dichroic mirror 104 is arranged in consideration of the refractive index of the prism constituting the splitter 103-a. Since the refractive index of the optical material forming the prism is larger than the refractive index of air, the dichroic mirror 104 is closer to the polarization beam splitter 103-a than the center of the polarization separation film of the polarization beam splitter 103-a and the polarization mirror 108. By arranging them at the positions, the optical path length of each color light can be made equal.
[0038]
In this embodiment, a reflection type light valve is used, but a transmission type light valve may be used as in the second embodiment.
In the present embodiment, instead of the deflecting mirror 108, the same polarizing beam splitter as the polarizing beam splitter 103-a or a compound prism in which the polarization splitting part of the polarizing beam splitter is a reflection mirror may be used. With this configuration, the dichroic mirror 104 sandwiched between the quarter-wave phase plates 105 and 106 is positioned at the position where the polarizing beam splitter 103-a and the deflecting mirror 108 are arranged, as in the first embodiment. Can be arranged almost at the center of the optical path between the polarization beam splitters 109R, 109G, and 109B, and the distance between the cross dichroic plume and the optical system can be reduced.
(Fourth embodiment)
A fourth embodiment will be described with reference to FIG. FIG. 4 is a plan configuration diagram of a projection display device according to a fourth embodiment of the present invention. The same members as those in the second embodiment are denoted by the same reference numerals, and the X axis, the Y axis, and the Z axis are defined as in the second embodiment.
[0039]
In the projection type display device using the transmissive light valve according to the second embodiment, the light from the light source 101 is emitted in the X-axis direction. In the present embodiment, the light from the light source is emitted in the Y-axis direction. ing.
[0040]
Light emitted from the light source 101 in the Y-axis direction is converted by the polarization conversion device 102 into polarized light that oscillates in a direction parallel to the Z-axis, and is incident on the wire grid polarization beam splitter 103. The wire grid polarization beam splitter 103 is arranged to reflect light polarized in the Z-axis direction. The light reflected in the X-axis direction by the wire grid polarizing beam splitter 103 passes through a quarter-wave phase plate 105, reflects R light and G light, and enters a dichroic mirror 104 that transmits B light. The transmitted B light is converted into polarized light vibrated in the Y-axis direction via a quarter-wave phase plate 106.
[0041]
The R light and the G light reflected by the dichroic mirror 104 enter the quarter-wave phase plate 105 again, and are converted into polarized light vibrating in the Y-axis direction. The B light is reflected by the deflecting mirror 108, travels in the Y-axis direction, changes its direction by 90 degrees by the deflecting mirror 213, and enters the transmission type light valve 210B. The mixed light of the R light and the G light passes through the wire grid polarization beam splitter 103, is deflected by the deflecting mirror 209, travels in the Y-axis direction, enters the dichroic mirror 107 that reflects the G light, is reflected and X The light is color-separated into G light traveling in the axial direction and R light traveling therethrough and traveling in the Y-axis direction. The R light and the G light having undergone the color separation enter the transmission type light valves 210R and 210G via the deflection mirrors 214 and 215, respectively. The dichroic mirror 104 is disposed substantially at the center of the optical path between the deflecting mirrors 108 and 209 and perpendicular to the optical axis. The light incident on the transmission type light valves 210B, 210G, 210R for each color light is modulated and detected by a polarizing plate arranged on the exit surface side, and is incident on a cross dichroic prism 211 which is a color synthesis optical system to perform color synthesis. After that, the light is projected on a screen (not shown) by the projection lens 212.
[0042]
Also in the projection type display device according to the present embodiment, since the optical path length of each color light can be made equal, there is no need to arrange a relay lens in the optical path of a specific color.
[0043]
【The invention's effect】
As described above, according to the present invention, it is possible to provide a projection display device in which the optical path length from the light source to the light valve is equal without using a cross dichroic mirror.
[Brief description of the drawings]
FIG. 1 is a plan configuration diagram of a projection display device according to a first embodiment.
FIG. 2 is a plan configuration diagram of a projection display device according to a second embodiment.
FIG. 3 is a plan configuration diagram of a projection display device according to a third embodiment.
FIG. 4 is a plan configuration diagram of a projection display device according to a fourth embodiment.
FIG. 5 is a plan view showing a configuration of a projection display device according to the related art.
[Explanation of symbols]
101 light source
102 Polarization converter
103 wire grid polarizing beam splitter
103-a polarizing beam splitter
104, 107 dichroic mirror
105, 106 quarter-wave phase plate
107, 108, 209, 213, 214, 215 Deflection mirror
109R, 109G, 109B Polarizing beam splitter
110R, 110G, 110B Reflective light valve
210R, 210G, 210B Transmission type light valve
111 Cross dichroic prism
112 Projection lens

Claims (9)

A polarizing beam splitter for polarizing and separating light from a light source having a first color light, a second color light, and a third color light and emitting the light;
The light from the light source emitted from the polarization beam splitter is color-separated into the first color light and a mixed light of the second color light and the third color light, and one of the first color light and the mixed light is separated. A first dichroic mirror that reflects light and makes it enter the polarization beam splitter;
A quarter-wave phase plate disposed on an incident surface side of the first dichroic mirror on which light from the light source is incident and an exit surface side on which transmitted light is emitted;
A color separation optical system comprising: a second dichroic mirror that separates the mixed light into the second color light and the third color light. An optical path length of each color light from the first dichroic mirror to an irradiation target irradiated with each color light separated by the first dichroic mirror and the second dichroic mirror is equal. The color separation optical system according to claim 1. The color separation optical system according to claim 1, wherein the polarization beam splitter is a wire grid polarization beam splitter. A color separation optical system that separates light from a light source into first color light, second color light, and third color light, and a light valve that is arranged for each color that modulates and emits the color separated color light.
A color combining optical system that combines the colors of light emitted from the light valve,
A projection lens for projecting the color-combined light,
In a projection display device having
The color separation optical system,
A polarization beam splitter that separates and emits light from the light source,
The light from the light source emitted from the polarization beam splitter is color-separated into the first color light and a mixed light of the second color light and the third color light, and one of the first color light and the mixed light is separated. A first dichroic mirror that reflects light and makes it enter the polarization beam splitter;
A quarter-wave phase plate disposed on an incident surface side of the first dichroic mirror on which light from the light source is incident and an exit surface side on which transmitted light is emitted;
A projection display device comprising: a second dichroic mirror that separates the mixed light into the second color light and the third color light. The projection display apparatus according to claim 4, wherein the optical path lengths of the respective color lights from the first dichroic mirror to the light valves arranged for the respective color lights are equal. The projection display device according to claim 4, wherein the polarization beam splitter is a wire grid polarization beam splitter. The projection type display device according to claim 4, wherein the light valve is a transmission type light valve. The projection type display device according to any one of claims 4 to 6, wherein the light valve is a reflection light valve. 9. The projection type display device according to claim 4, wherein the color combining optical system is a cross dichroic prism.

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