Projector

Abstract

To provide a projector that suppresses the deterioration of a liquid crystal in a light modulation element for modulating a blue light beam.SOLUTION: A projector comprises: a separation optical system including a first dichroic mirror for separating outgoing light into a first colored light beam as a blue light beam and another colored light beam; a first light modulation element for modulating the first colored light beam; a second light modulation element for modulating the other colored light beam; a reflection mirror for reflecting the first colored light beam from the first dichroic mirror toward the first light modulation element; a reduction optical system for reducing luminous flux width of the first colored light beam modulated by the first light modulation element; and a color combining prism. An effective area of the first light modulation element is larger than an effective area of the second light modulation element. An optical axis of the first light modulation element is parallel to an optical axis of a reduction side imaging plane. An incident direction of the first colored light beam entering the first light modulation element is opposite to an emission direction of the first colored light beam emitted from the reduction side imaging plane. The reduction side imaging plane is at a position opposed to a first surface portion of the color combining prism which the first colored light beam enters.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a projector. [Background technology]

[0002] A projector that suppresses the deterioration of the liquid crystal of a liquid crystal device due to light from a light source is described in Patent Document 1. The projector in this document includes a light source, a dichroic mirror that separates the light from the light source into three color lights, three transmissive liquid crystal light valves that modulate the three color lights, a cross dichroic prism that combines the light modulated by the liquid crystal light valves, and a projection lens that projects the combined light. In the projector in this document, of the three liquid crystal light valves, the liquid crystal light valve that modulates blue is more susceptible to deterioration of the liquid crystal due to light than the other liquid crystal light valves that modulate red and green, so the liquid crystal light valve that modulates blue is provided with multiple liquid crystal reservoirs on the outer periphery of the effective display area. As a result, the liquid crystal light valve that modulates blue can increase the total amount of liquid crystal in the liquid crystal light valve more than the other liquid crystal light valves, and therefore can suppress deterioration of the liquid crystal due to light. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2022-38106 Summary of the Invention [Problem to be solved by the invention]

[0004] In recent years, there has been a demand for brighter projectors. However, the projector of Patent Document 1 has a problem in that when the light intensity of the light source is increased to make the projector brighter, it is difficult to suppress deterioration of the liquid crystal in the liquid crystal light valve that modulates blue light. [Means for solving the problem]

[0005] In order to solve the above problems, the projector of the present invention includes a light source, a separation optical system including a first dichroic mirror that separates light emitted from the light source into a first color light in a first wavelength band including blue light and other color light in a wavelength band longer than the first color light and reflects the first color light in a direction perpendicular to an optical axis of the emitted light, a first light modulation element that modulates the first color light separated by the first dichroic mirror, a second light modulation element that modulates the other color light separated by the first dichroic mirror, a reflection mirror that reflects the first color light separated by the first dichroic mirror toward the first light modulation element in a direction perpendicular to the first light modulation element, and the first light modulation element is disposed on an enlargement-side image forming plane, the first color light modulated by the second light modulation element is projected from the first light beam by a first light beam width modulated by the second light modulation element; and a projection optical system that projects the projected light from the color combining prism. The projection optical system has a reduction optical system that reduces the beam width of the first color light modulated by the reduction optical system at a reduction-side image forming surface, a color combining prism that emits a composite light obtained by combining the first color light whose beam width has been reduced by the reduction optical system and the other color light modulated by the second light modulation element, and a projection optical system that projects the composite light output from the color combining prism, wherein the effective area of ​​the first light modulation element is larger than the effective area of ​​the second light modulation element, the optical axis of the first light modulation element is parallel to the optical axis of the reduction-side image forming surface, the incident direction of the first color light entering the first light modulation element is opposite to the exit direction of the first color light output from the reduction-side image forming surface, and the reduction-side image forming surface is located opposite to the first surface of the color combining prism onto which the first color light is incident. [Brief description of the drawings]

[0006] [Figure 1] 1 is a schematic diagram of a main part of a projector according to a first embodiment. [Diagram 2] FIG. 11 is a schematic diagram of a main part of a projector according to a second embodiment. [Diagram 3] FIG. 11 is a schematic diagram of a main part of a projector according to a third embodiment. [Figure 4] FIG. 11 is a schematic diagram of a main part of a projector according to a fourth embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0007] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a projector according to an embodiment of the invention will be described with reference to the drawings.

[0008] [Embodiment 1] Fig. 1 is a schematic diagram of a main part of a projector 100 of the embodiment 1. As shown in Fig. 1, the projector 100 includes a light source 1, an illumination optical system 2 that uniformizes the light emitted from the light source 1, a separation optical system 3 that separates the light emitted from the illumination optical system 2 into each color light, a plurality of light modulation elements 7 that modulate each color light separated by the separation optical system 3 to form a projection image, a reflection mirror 11, a reduction optical system 6 that reduces the light beam width of the color light modulated by one of the plurality of light modulation elements 7, a color synthesis prism 8 that outputs a synthetic light obtained by synthesizing each color light modulated by the light modulation element 7, a projection optical system 9 that projects the synthetic light output from the color synthesis prism 8, and a control unit 10 that controls the light modulation elements 7.

[0009] For convenience, in the following description, the three mutually orthogonal axes are referred to as the X-axis, Y-axis, and Z-axis. The direction along the first optical axis N of the separation optical system 3 is referred to as the X-axis direction. In the X-axis direction, the direction in which the output light from the illumination optical system 2 is output is referred to as the first direction X1, and the opposite direction is referred to as the second direction X2. In the Y-axis direction, the direction in which the combined light is output from the color combining prism 8 is referred to as the third direction Y1, and the opposite direction is referred to as the fourth direction Y2.

[0010] The light source 1 is, for example, an extra-high pressure mercury lamp, a solid-state light source, etc. In this embodiment, the light source 1 emits white light as the emitted light LD.

[0011] The illumination optical system 2 includes a multi-lens 21, a polarizing beam splitter 22, a multi-lens 23, and a relay lens 24. The multi-lens 21 splits the output light LD from the light source 1 into multiple light beams. The polarizing beam splitter 22 converts the polarization direction of the output light LD output from the multi-lens 21. The multi-lens 23 focuses the output light LD output from the polarizing beam splitter 22 in the vicinity of the relay lens 24. The relay lens 24 magnifies the output light LD incident from the multi-lens 23 and outputs it toward the separation optical system 3.

[0012] The separation optical system 3 includes, in order in the first direction X1, a first dichroic mirror 31 and a second dichroic mirror 32. The first dichroic mirror 31 and the second dichroic mirror 32 are disposed along a first optical axis N of the separation optical system 3. The optical axis of the output light LD from the illumination optical system 2 coincides with the first optical axis N.

[0013] The first dichroic mirror 31 separates the output light LD into a first color light LB and another color light LC. The first dichroic mirror 31 reflects the first color light LB in a fourth direction Y2 and transmits the other color light LC in a first direction X1. The second dichroic mirror 32 separates the other color light LC into a second color light LG and a third color light LR. The second dichroic mirror 32 reflects the third color light LR in a third direction Y1 and transmits the second color light LG in a first direction X1. In this embodiment, the first color light LB is a first wavelength band including blue light. The second color light LG is a second wavelength band including green. The third color light LR is a third wavelength band including red. The first wavelength band is, for example, 420 nm to 500 nm. The second wavelength band is, for example, 500 nm to 600 nm. The third wavelength band is, for example, 600 nm to 680 nm. The wavelength band of the other color light LC is, for example, 500 nm to 680 nm.

[0014] Here, a reflecting mirror 14 is disposed in the third direction Y1 of the second dichroic mirror 32, which reflects the third color light LR separated by the second dichroic mirror 32 in the first direction X1. A reflecting mirror 15 is disposed in the first direction X1 of the second dichroic mirror 32, which reflects the second color light LG separated by the second dichroic mirror 32 in the third direction Y1. Lenses 12 are disposed between the second dichroic mirror 32 and the reflecting mirror 14, and between the second dichroic mirror 32 and the reflecting mirror 15. Lenses 13 are disposed in the first direction X1 of the reflecting mirror 14 and in the third direction Y1 of the reflecting mirror 15. The lenses 12 and 13 focus the second color light LG and the third color light LR separated by the separation optical system 3 near the light modulation element 7.

[0015] The reflecting mirror 11 is disposed in the fourth direction Y2 of the first dichroic mirror 31. The reflecting mirror 11 reflects the first color light LB separated by the first dichroic mirror 31 in the first direction X1. Here, the projector 100 includes a relay lens 19 between the reflecting mirror 11 and the first dichroic mirror 31. The relay lens 19 adjusts the imaging position of the first color light LB so that the first color light LB from the first dichroic mirror 31 is uniformly irradiated onto the first light modulation element 71. In this embodiment, the relay lens 19 is made up of one lens. Note that the relay lens 19 may be made up of a plurality of lenses.

[0016] The light modulation element 7 is a liquid crystal panel. The light modulation element 7 includes a first light modulation element 71 that modulates the first color light LB, a third light modulation element 72 that modulates the second color light LG, and a fourth light modulation element 73 that modulates the third color light LR. The first light modulation element 71, the third light modulation element 72, and the fourth light modulation element 73 each include an incident side polarizing plate 75 and an exit side polarizing plate 76. The third light modulation element 72 and the fourth light modulation element 73 correspond to the "second light modulation element" of the present invention.

[0017] The first light modulation element 71 is disposed in the first direction X1 of the first dichroic mirror 31. The optical axis N1 of the first light modulation element 71 extends in the direction along the X-axis. The optical axis N1 of the first light modulation element 71 is parallel to the first optical axis N of the separation optical system 3.

[0018] The third light modulation element 72 is disposed at a position facing the second surface 82 of the color synthesis prism 8. The fourth light modulation element 73 is disposed at a position facing the third surface 83 of the color synthesis prism 8.

[0019] The effective area of ​​the first light modulation element 71 is larger than those of the third light modulation element 72 and the fourth light modulation element 73. Regarding the diagonal dimension of the effective area (effective display region) of the light modulation element in this embodiment, the first light modulation element 71 is a 1.03-inch liquid crystal panel, and the third light modulation element 72 and the fourth light modulation element 73 are 0.67-inch liquid crystal panels. In this embodiment, the first light modulation element 71, the third light modulation element 72, and the fourth light modulation element 73 have a display resolution of WUXGA (1920 pixels in the horizontal direction, 1200 pixels in the vertical direction), as an example.

[0020] The reduction optical system 6 has a first light modulation element 71 disposed on the enlargement-side imaging surface 60A of the reduction optical system 6, and reduces the beam width of the first color light LB modulated by the first light modulation element 71 on the reduction-side imaging surface 60B. In this embodiment, the reduction optical system 6 reduces the beam width of the first color light LB modulated by the first light modulation element 71 from 1.03 inches to 0.67 inches on the reduction-side imaging surface 60B. The optical axis N1 of the first light modulation element 71 and the optical axis M1 of the enlargement-side imaging surface 60A coincide with each other. The reduction-side imaging surface 60B is disposed at a position facing the first surface 81 of the color synthesis prism 8. The distance between the reduction-side imaging surface 60B and the first surface 81 of the color synthesis prism 8 is the same as the distance between the third light modulation element 72 and the second surface 82 of the color synthesis prism 8. Furthermore, the distance between the reduction-side image formation surface 60B and the first surface 81 of the color synthesis prism 8 is the same as the distance between the fourth light modulation element 73 and the third surface 83 of the color synthesis prism 8.

[0021] Here, the projector 100 has a polarizing plate 5 disposed between the reduction-side imaging surface 60B and the first surface 81. The polarizing plate 5 and the exit-side polarizing plate 76 of the first light modulation element 71 transmit linearly polarized components in the same direction among the polarized components contained in the first color light LB. That is, when the exit-side polarizing plate 76 of the first light modulation element 71 transmits the S-polarized light of the first color light LB, the polarizing plate 5 transmits the S-polarized light, and when the exit-side polarizing plate 76 of the first light modulation element 71 transmits the P-polarized light of the first color light LB, the polarizing plate 5 transmits the P-polarized light.

[0022] The color synthesis prism 8 has a first surface 81 on which the first color light LB is incident, a second surface 82 on which the second color light LG is incident, a third surface 83 on which the third color light LR is incident, and a fourth surface 84 from which the synthesized light LE is emitted. The first surface 81 and the third surface 83 face each other in the X-axis direction. The second surface 82 and the fourth surface face each other in the Y-axis direction. The color synthesis prism 8 emits synthesized light LE, which is obtained by combining the first color light LB, the light beam width of which has been reduced by the reduction optical system 6, the second color light LG, which has been modulated by the third light modulation element 72, and the third color light LR, which has been modulated by the fourth light modulation element 73, from the fourth surface 84 in the third direction Y1. Here, the beam width of the first color light LB incident on the first surface 81 of the color synthesis prism 8 is the same as the beam width of the second color light LG incident on the second surface 82 of the color synthesis prism 8 and the beam width of the third color light LR incident on the third surface 83 of the color synthesis prism 8.

[0023] The projection optical system 9 projects the combined light LE emitted from the color combining prism 8 onto a screen. The projection optical system 9 includes a plurality of lenses. The control unit 10 operates the light modulation element 7 based on an external image signal such as a video signal.

[0024] (Details of the reduction optical system) As shown in Fig. 1, the reduction optical system 6 includes a plurality of reflective surfaces 60 having power and a lens 64. More specifically, the reduction optical system 6 includes, in order from the enlargement side to the reduction side, a first reflective surface 61 having positive power, a lens 64, a second reflective surface 62 having negative power, and a third reflective surface 63 having positive power. The first reflective surface 61 has a concave shape. The second reflective surface 62 has a convex shape. The third reflective surface 63 has a concave shape.

[0025] The first color light LB that reaches the first reflecting surface 61 from the first light modulation element 71 is reflected in the second direction X2 and the third direction Y1. The first color light LB reflected by the first reflecting surface 61 passes through the lens 64 and reaches the second reflecting surface 62. The first color light LB that reaches the second reflecting surface 62 is reflected in the first direction X1 and the third direction Y1. The first color light LB reflected by the second reflecting surface 62 passes through the lens 64 and reaches the third reflecting surface 63. The first color light LB that reaches the third reflecting surface 63 is reflected in the second direction X2. The first color light LB reflected by the third reflecting surface 63 passes through the lens 64 and reaches the reduction-side imaging surface 60B.

[0026] The optical axis M1 of the enlargement-side imaging surface 60A and the optical axis M2 of the reduction-side imaging surface 60B are parallel to each other. That is, the optical axis N1 of the first light modulation element 71 is parallel to the optical axis M2 of the reduction-side imaging surface 60B.

[0027] The incident direction of the first color light LB incident on the enlargement-side imaging surface 60A is the first direction X1. The exit direction of the first color light LB exiting from the reduction-side imaging surface 60B is the second direction X2. That is, the incident direction of the first color light LB incident on the first light modulation element 71 is the opposite direction to the exit direction of the first color light LB exiting from the reduction-side imaging surface 60B.

[0028] The enlargement-side image forming surface 60A and the reduction-side image forming surface 60B are located in the first direction X1 on the same side with respect to the first surface 81 of the color synthesis prism 8. In other words, the first light modulation element 71 and the reduction-side image forming surface 60B are located in the first direction X1 on the same side with respect to the first surface 81 of the color synthesis prism 8.

[0029] Both sides of the reduction optical system 6, that is, the enlargement side of the first reflecting surface 61 and the reduction side of the lens 64, are telecentric. The enlargement side of the first reflecting surface 61 being telecentric means that the central ray of each light beam passing between the first reflecting surface 61 and the enlargement side image forming surface 60A is parallel to the optical axis M1 or approximately parallel to the optical axis M1. The reduction side of the lens 64 being telecentric means that the central ray of each light beam passing between the lens 64 and the reduction side image forming surface 60B is parallel to the optical axis M2 or approximately parallel to the optical axis M2. In this embodiment, the angle formed by the central ray of each light beam and the optical axes M1 and M2 is within ±5°.

[0030] (Action and effect) The projector 100 of this embodiment includes a light source 1, a separation optical system 3 including a first dichroic mirror 31 that separates the output light LD emitted from the light source 1 into a first color light LB in a first wavelength band including blue light and another color light LC in a wavelength band longer than the first color light LB and reflects the first color light LB in the Y-axis direction perpendicular to the optical axis of the output light LD, a first light modulation element 71 that modulates the first color light LB separated by the first dichroic mirror 31, a second light modulation element that modulates the other color light LC separated by the first dichroic mirror 31, and a second light modulation element that modulates the first dichroic mirror 31. The optical system includes a reflecting mirror 11 that reflects the first color light LB separated by the reflective mirror 31 in the X-axis direction perpendicular to the first light modulation element 71, a reduction optical system 6 that arranges the first light modulation element 71 on the enlargement-side imaging surface 60A and reduces the light beam width of the first color light LB modulated by the first light modulation element 71 on the reduction-side imaging surface 60B, a color synthesis prism 8 that outputs a synthesized light LE that combines the first color light LB whose light beam width has been reduced by the reduction optical system 6 and the other color light LC modulated by the second light modulation element, and a projection optical system 9 that projects the synthesized light LE that has been output from the color synthesis prism 8. The effective area of ​​the first light modulation element 71 is larger than the effective area of ​​the second light modulation element. The optical axis N1 of the first light modulation element 71 is parallel to the optical axis M2 of the reduction-side imaging surface 60B. The incident direction of the first color light LB entering the first light modulation element 71 is opposite to the exit direction of the first color light LB exiting from the reduction-side imaging surface 60B. The reduction-side imaging surface 60B is located opposite to the first surface 81 of the color synthesis prism 8.

[0031] According to this embodiment, since the effective area of ​​the first light modulation element 71 is larger than that of the second light modulation element, the illuminance irradiated on the first light modulation element 71 can be made smaller than that on the second light modulation element. This makes it possible to prevent the liquid crystal of the first light modulation element 71 from being deteriorated by light even if the light source 1 is made brighter.

[0032] In addition, since the reduction optical system 6 can reduce the beam width of the first color light LB modulated by the first light modulation element 71 at the reduction side imaging surface 60B, the beam width of each color light incident on the color synthesis prism 8 can be made the same size even if the effective area of ​​the first light modulation element 71 is larger than the effective area of ​​the third light modulation element 72.

[0033] In addition, the reduction optical system 6 bends the first color light LB incident on the enlargement side imaging surface 60A by 180 degrees and emits the first color light LB from the reduction side imaging surface 60B, so the entire projector can be made more compact than when the reduction optical system 6 does not bend the first color light LB.

[0034] The projector 100 of this embodiment has a polarizing plate 5 disposed between the reduction-side imaging surface 60B and the first surface 81. Therefore, even if the polarization direction of the first colored light LB emitted from the first light modulation element 71 is disturbed when the first colored light LB passes through the reduction optical system 6, the polarizing plate 5 can compensate for the polarization direction of the first colored light LB. This makes it possible to suppress a decrease in the contrast of the first colored light LB incident on the color synthesis prism 8.

[0035] The projector 100 of this embodiment has a relay lens 19 disposed between the first dichroic mirror 31 and the reflecting mirror 11. The relay lens 19 adjusts the imaging position of the first color light LB from the first dichroic mirror 31. This allows the first color light LB from the first dichroic mirror 31 to be uniformly irradiated onto the first light modulation element 71.

[0036] The separation optical system 3 includes a second dichroic mirror 32 that separates the other color light LC transmitted by the first dichroic mirror 31 in the first direction X1 into a second color light LG in a second wavelength band including green and a third color light LR in a third wavelength band including red. The second light modulation element includes a third light modulation element 72 that modulates the second color light LG separated by the second dichroic mirror 32, and a fourth light modulation element 73 that modulates the third color light separated by the second dichroic mirror. The color synthesis prism 8 emits a composite light LE that combines the first color light LB whose light beam width has been reduced by the reduction optical system 6, the second color light LG modulated by the third light modulation element 72, and the third color light LR modulated by the fourth light modulation element 73. In this manner, the projector 100 can project a full-color composite light LE.

[0037] The luminous flux width of the first colored light LB incident on the first surface 81 of the color combining prism 8 is the same as the luminous flux width of the second colored light LG incident on the second surface 82 of the color combining prism 8 and the luminous flux width of the third colored light LR incident on the third surface 83 of the color combining prism 8. Therefore, the color combining prism 8 can easily combine the respective colored lights into one combined light LE.

[0038] The reduction optical system 6 includes a plurality of reflecting surfaces 60 having power. Both sides of the reduction optical system 6 are telecentric. Therefore, compared to reduction optical systems 6 that are not telecentric on both sides, when the reduction optical system 6 is incorporated into the projector 100, the installation accuracy of the first light modulation element 71 is not strict. In addition, the first color light LB traveling from the reduction-side imaging surface 60B toward the color synthesis prism 8 becomes parallel light, so it is easy to suppress the occurrence of various aberrations occurring in the reduction optical system 6.

[0039] In addition, since the reduction optical system 6 is composed of a plurality of reflecting surfaces 60, it is possible to use the optical path of the reduction optical system 6 as an air duct for blowing air. This makes it easy to cool the light modulation element 7, and it is possible to prevent the light modulation element 7 from deteriorating. In addition, when the optical path of the reduction optical system 6 is used as an air duct for blowing air, it is easy to cool the reflecting surfaces 60, and it is possible to prevent the reflecting surfaces 60 from deteriorating in optical performance due to thermal expansion.

[0040] [Embodiment 2] 2 is a schematic diagram of a main part of a projector 100A of embodiment 2. The projector 100A of embodiment 2 differs from the projector 100 of embodiment 1 in the position where the reduction optical system 6 is arranged. Therefore, in embodiment 2, the same components as those in embodiment 1 are denoted by the same reference numerals, and the description thereof may be omitted.

[0041] The separation optical system 3 includes, in order in the first direction X1, a first dichroic mirror 31 and a second dichroic mirror 32. The first dichroic mirror 31 and the second dichroic mirror 32 are disposed along a first optical axis N of the separation optical system 3. The first dichroic mirror 31 separates the output light LD into a first color light LB and another color light LC.

[0042] The first dichroic mirror 31 reflects the first color light LB in the third direction Y1 and transmits the other color light LC in the first direction X1. The second dichroic mirror 32 separates the other color light LC into the second color light LG and the third color light LR. The second dichroic mirror 32 reflects the second color light LG in the third direction Y1 and transmits the third color light LR in the first direction X1. In this embodiment, the first color light LB is a first wavelength band including blue light. The second color light LG is a second wavelength band including green. The third color light LR is a third wavelength band including red. The first wavelength band is, for example, 420 nm to 500 nm. The second wavelength band is, for example, 500 nm to 600 nm. The third wavelength band is, for example, 600 nm to 680 nm. The wavelength band of the other color light LC is, for example, 500 nm to 680 nm.

[0043] Here, a reflecting mirror 16 is arranged in the first direction X1 of the second dichroic mirror 32 to reflect the third color light LR separated by the second dichroic mirror 32 in the third direction Y1. A reflecting mirror 17 is arranged in the third direction Y1 of the reflecting mirror 16 to reflect the third color light LR reflected by the reflecting mirror 16 in the second direction X2. Lenses 12 are arranged between the first dichroic mirror 31 and the second dichroic mirror 32, between the second dichroic mirror 32 and the reflecting mirror 16, and between the reflecting mirror 16 and the reflecting mirror 17. Lenses 13 are arranged in the third direction Y1 of the second dichroic mirror 32 and in the second direction X2 of the reflecting mirror. The lenses 12 and 13 focus the second color light LG and the third color light LR separated by the separation optical system 3 near the light modulation element 7.

[0044] The reflecting mirror 11 is disposed in the third direction Y1 of the first dichroic mirror 31. The reflecting mirror 11 reflects the first color light LB in the third direction Y1, which is separated by the first dichroic mirror 31, toward the first direction X1. Here, the projector 100 includes a relay lens 19 between the reflecting mirror 11 and the first dichroic mirror 31. In this embodiment, the relay lens 19 is made up of one lens. Note that the relay lens 19 may be made up of a plurality of lenses.

[0045] The first light modulation element 71 is disposed in the first direction X1 of the first dichroic mirror 31. The optical axis N1 of the first light modulation element 71 extends in the direction along the X-axis. The optical axis N1 of the first light modulation element 71 is parallel to the first optical axis N of the separation optical system 3.

[0046] The third light modulation element 72 is disposed at a position facing the second surface 82 of the color synthesis prism 8. The fourth light modulation element 73 is disposed at a position facing the third surface 83 of the color synthesis prism 8.

[0047] The effective area of ​​the first light modulation element 71 is larger than those of the third light modulation element 72 and the fourth light modulation element 73. Regarding the diagonal dimension of the effective area (effective display region) of the light modulation element in this embodiment, the first light modulation element 71 is a 1.03-inch liquid crystal panel, and the third light modulation element 72 and the fourth light modulation element 73 are 0.67-inch liquid crystal panels. In this embodiment, the first light modulation element 71, the third light modulation element 72, and the fourth light modulation element 73 have a display resolution of WUXGA (1920 pixels in the horizontal direction, 1200 pixels in the vertical direction), as an example.

[0048] In the reduction optical system 6, the first light modulation element 71 is disposed on the enlargement-side imaging surface 60A of the reduction optical system 6, and reduces the beam width of the first color light LB modulated by the first light modulation element 71 on the reduction-side imaging surface 60B. The optical axis N1 of the first light modulation element 71 and the optical axis M1 of the enlargement-side imaging surface 60A coincide with each other. In this embodiment, the reduction optical system 6 reduces the beam width of the first color light LB modulated by the first light modulation element 71 from 1.03 inches to 0.67 inches on the reduction-side imaging surface 60B. The reduction-side imaging surface 60B is disposed at a position facing the first surface 81 of the color synthesis prism 8.

[0049] Here, the projector 100A has a polarizing plate 5 disposed between the reduction-side imaging surface 60B and the first surface 81. The polarizing plate 5 and the output-side polarizing plate 76 of the first light modulation element 71 transmit linearly polarized components in the same direction among the polarized components contained in the first color light LB.

[0050] The beam width of the first color light LB incident on the first surface 81 of the color synthesis prism 8 is the same as the beam width of the second color light LG incident on the second surface 82 of the color synthesis prism 8 and the beam width of the third color light LR incident on the third surface 83 of the color synthesis prism 8.

[0051] (Details of the reduction optical system) 2, the reduction optical system 6 includes, in order from the enlargement side to the reduction side, a first reflecting surface 61 having positive power, a lens 64, a second reflecting surface 62 having negative power, and a third reflecting surface 63 having positive power. The first reflecting surface 61 has a concave shape. The second reflecting surface 62 has a convex shape. The third reflecting surface 63 has a concave shape.

[0052] The first color light LB that reaches the first reflecting surface 61 from the first light modulation element 71 is reflected in the first direction X1 and the fourth direction Y2. The first color light LB reflected by the first reflecting surface 61 passes through the lens 64 and reaches the second reflecting surface 62. The first color light LB that reaches the second reflecting surface 62 is reflected in the second direction X2 and the fourth direction Y2. The first color light LB reflected by the second reflecting surface 62 passes through the lens 64 and reaches the third reflecting surface 63. The first color light LB that reaches the third reflecting surface 63 is reflected in the first direction X1. The first color light LB reflected by the third reflecting surface 63 passes through the lens 64 and reaches the reduction-side imaging surface 60B.

[0053] The optical axis M1 of the enlargement-side imaging surface 60A and the optical axis M2 of the reduction-side imaging surface 60B are parallel to each other. That is, the optical axis N1 of the first light modulation element 71 is parallel to the optical axis M2 of the reduction-side imaging surface 60B.

[0054] The incident direction of the first color light LB incident on the enlargement-side imaging surface 60A is the second direction X2. The exit direction of the first color light LB exiting from the reduction-side imaging surface 60B is the first direction X1. That is, the incident direction of the first color light LB incident on the first light modulation element 71 is the opposite direction to the exit direction of the first color light LB exiting from the reduction-side imaging surface 60B.

[0055] The enlargement-side image forming surface 60A and the reduction-side image forming surface 60B are located on the same side in the second direction X2 with respect to the first surface 81 of the color synthesis prism 8. In other words, the first light modulation element 71 and the reduction-side image forming surface 60B are located on the same side in the second direction X2 with respect to the first surface 81 of the color synthesis prism 8.

[0056] Both sides of the reduction optical system 6, ie the enlargement side of the first reflecting surface 61 and the reduction side of the lens 64, are telecentric.

[0057] (Action and effect) Even if the reduction optical system 6 is disposed as in the second embodiment, the projector 100A can obtain the same effects as those in the first embodiment.

[0058] [Embodiment 3] 3 is a schematic diagram of a main part of a projector 100B of embodiment 3. The projector 100B of embodiment 3 differs from the projector 100 of embodiment 1 in the configuration of the reduction optical system 6. Therefore, in embodiment 3, the same configurations as those in embodiment 1 are denoted by the same reference numerals, and descriptions thereof may be omitted.

[0059] 3, the reduction optical system 6 includes, in order from the enlargement side to the reduction side, a first lens group G1 having a positive power and made up of multiple lenses, a second lens group G2 having one or two lenses, at least one of which has a negative power, and a third lens group G3 having a positive power and made up of multiple lenses. The reduction optical system 6 includes an aperture 65 between the second lens group G2 and the third lens group G3. The first lens group G1, the second lens group G2, and the third lens group G3 are arranged along a second optical axis M of the reduction optical system 6.

[0060] The number of lenses in the first lens group G1 is the same as the number of lenses in the third lens group G3. More specifically, the first lens group G1 is made up of four lenses, lens L1 to lens L4. The third lens group G3 is made up of four lenses, lens L7 to lens L10.

[0061] The second lens group G2 is made up of two lenses, a lens L5 and a lens L6, at least one of which has negative power.

[0062] The reduction optical system 6 includes a first reflecting mirror 66 that reflects the first color light LB modulated by the first light modulation element 71 in the third direction Y1, and a second reflecting mirror 67 that reflects the first color light LB emitted from the lens L10 in the second direction X2. The first reflecting mirror 66 is disposed in the fourth direction Y2 of the lens L1. The second reflecting mirror 67 is disposed in the third direction Y1 of the lens L10.

[0063] The first color light LB that reaches the first reflecting mirror 66 from the first light modulation element 71 is reflected in the third direction Y1. The first color light LB reflected by the first reflecting mirror 66 passes through the first lens group G1, the second lens group G2, and the third lens group G3, and reaches the second reflecting mirror 67. The first color light LB that reaches the second reflecting mirror 67 is reflected in the second direction X2. The first color light LB reflected by the second reflecting mirror 67 reaches the reduction-side imaging surface 60B.

[0064] The optical axis M1 of the enlargement-side imaging surface 60A and the optical axis M2 of the reduction-side imaging surface 60B are parallel to each other. That is, the optical axis N1 of the first light modulation element 71 is parallel to the optical axis M2 of the reduction-side imaging surface 60B.

[0065] The incident direction of the first color light LB incident on the enlargement-side imaging surface 60A is the first direction X1. The exit direction of the first color light LB exiting from the reduction-side imaging surface 60B is the second direction X2. That is, the incident direction of the first color light LB incident on the first light modulation element 71 is the opposite direction to the exit direction of the first color light LB exiting from the reduction-side imaging surface 60B.

[0066] The enlargement-side image forming surface 60A and the reduction-side image forming surface 60B are located in the first direction X1 on the same side with respect to the first surface 81 of the color synthesis prism 8. In other words, the first light modulation element 71 and the reduction-side image forming surface 60B are located in the first direction X1 on the same side with respect to the first surface 81 of the color synthesis prism 8.

[0067] Both sides of the reduction optical system 6, that is, the enlargement side of the first reflecting mirror 66 and the reduction side of the second reflecting mirror 67, are telecentric.

[0068] (Action and effect) In this embodiment, the reduction optical system 6 includes, in order from the enlargement side to the reduction side, a first lens group G1 made up of multiple lenses and having a positive power, a second lens group G2 having two lenses, at least one of which has a negative power, and a third lens group G3 made up of multiple lenses and having a positive power. Both sides of the reduction optical system 6 are telecentric. Therefore, since the number of lenses in the first lens group G1 and the third lens group G3 sandwiching the second lens group G2 is the same, various aberrations generated in the first lens group G1 can be canceled by the third lens group G3. In addition, compared to a reduction optical system 6 in which both sides are not telecentric, when the reduction optical system 6 is incorporated into the projector 100, the installation accuracy of the first light modulation element 71 is not strict. In addition, since the first color light LB traveling from the reduction side image plane 60B toward the color synthesis prism 8 becomes parallel light, it is easy to suppress the occurrence of various aberrations generated in the reduction optical system 6.

[0069] Furthermore, even if the reduction optical system 6 of the third embodiment is employed, the projector 100B can obtain the same effects as those of the first embodiment.

[0070] [Embodiment 4] 4 is a schematic diagram of a main part of a projector 100C of embodiment 4. The projector 100C of embodiment 4 differs from the projector 100A of embodiment 2 in that the configuration of the reduction optical system 6 is the same as that of embodiment 3. Therefore, in embodiment 4, the same components as those of embodiment 1 are denoted by the same reference numerals, and the description thereof may be omitted.

[0071] 4, the reduction optical system 6 includes, in order from the enlargement side to the reduction side, a first lens group G1 having a positive power and made up of multiple lenses, a second lens group G2 having one or two lenses, at least one of which has a negative power, and a third lens group G3 having a positive power and made up of multiple lenses. The reduction optical system 6 includes an aperture 65 between the second lens group G2 and the third lens group G3. The first lens group G1, the second lens group G2, and the third lens group G3 are arranged along a second optical axis M of the reduction optical system 6.

[0072] The number of lenses in the first lens group G1 is the same as the number of lenses in the third lens group G3. More specifically, the first lens group G1 is made up of four lenses, lens L1 to lens L4. The third lens group G3 is made up of four lenses, lens L7 to lens L10.

[0073] The second lens group G2 is made up of two lenses, a lens L5 and a lens L6, at least one of which has negative power.

[0074] The reduction optical system 6 includes a first reflecting mirror 66 that reflects the first color light LB modulated by the first light modulation element 71 in the fourth direction Y2, and a second reflecting mirror 67 that reflects the first color light LB emitted from the lens L10 in the first direction X1. The first reflecting mirror 66 is disposed in the third direction Y1 of the lens L1. The second reflecting mirror 67 is disposed in the fourth direction Y2 of the lens L10.

[0075] The first colored light LB that reaches the first reflecting mirror 66 from the first light modulation element 71 is reflected in the fourth direction Y2. The first colored light LB reflected by the first reflecting mirror 66 passes through the first lens group G1, the second lens group G2, and the third lens group G3, and reaches the second reflecting mirror 67. The first colored light LB that reaches the second reflecting mirror 67 is reflected in the first direction X1. The first colored light LB reflected by the second reflecting mirror 67 reaches the reduction-side imaging surface 60B.

[0076] The optical axis M1 of the enlargement-side imaging surface 60A and the optical axis M2 of the reduction-side imaging surface 60B are parallel to each other. That is, the optical axis N1 of the first light modulation element 71 is parallel to the optical axis M2 of the reduction-side imaging surface 60B.

[0077] The incident direction of the first color light LB incident on the enlargement-side imaging surface 60A is the second direction X2. The exit direction of the first color light LB exiting from the reduction-side imaging surface 60B is the first direction X1. That is, the incident direction of the first color light LB incident on the first light modulation element 71 is the opposite direction to the exit direction of the first color light LB exiting from the reduction-side imaging surface 60B.

[0078] The enlargement-side image forming surface 60A and the reduction-side image forming surface 60B are located on the same side in the second direction X2 with respect to the first surface 81 of the color synthesis prism 8. In other words, the first light modulation element 71 and the reduction-side image forming surface 60B are located on the same side in the second direction X2 with respect to the first surface 81 of the color synthesis prism 8.

[0079] Both sides of the reduction optical system 6, that is, the enlargement side of the first reflecting mirror 66 and the reduction side of the second reflecting mirror 67, are telecentric.

[0080] (Action and effect) Even if the reduction optical system 6 is disposed as in the fourth embodiment, the projector 100C can obtain the same effects as those in the third embodiment.

[0081] [Summary of this disclosure] The following is a summary of this disclosure.

[0082] (Appendix 1) A light source; a separation optical system that separates light emitted from the light source into a first color light in a first wavelength band including blue light and another color light in a wavelength band longer than the first color light, and that includes a first dichroic mirror that reflects the first color light in a direction perpendicular to an optical axis of the emitted light; a first light modulation element that modulates the first color light separated by the first dichroic mirror; a second light modulation element that modulates the other color light separated by the first dichroic mirror; a reflecting mirror that reflects the first color light separated by the first dichroic mirror toward the first light modulation element in a direction perpendicular to the first color light; a reduction optical system in which the first light modulation element is disposed on an enlargement-side image forming surface and which reduces, on a reduction-side image forming surface, a light beam width of the first color light modulated by the first light modulation element; a color synthesis prism that outputs a synthesized light obtained by synthesizing the first color light whose light beam width has been reduced by the reduction optical system and the other color light modulated by the second light modulation element; a projection optical system that projects the combined light emitted from the color combining prism; having an effective area of ​​the first light modulation element is larger than an effective area of ​​the second light modulation element; an optical axis of the first light modulation element is parallel to an optical axis of the reduction-side image forming surface; an incident direction of the first color light incident on the first light modulation element is opposite to an exit direction of the first color light exiting from the reduction-side image forming surface, The reduction-side image forming surface is located opposite a first surface of the color synthesis prism onto which the first color light is incident.

[0083] As a result, the effective area of ​​the first light modulation element is larger than that of the second light modulation element, so that the illuminance irradiated on the first light modulation element can be made smaller than that on the second light modulation element, thereby making it possible to prevent the liquid crystal of the first light modulation element from being deteriorated by light.

[0084] In addition, since the reduction optical system can reduce the beam width of the first color light modulated by the first light modulation element at the reduction side imaging surface, the beam width of each color light incident on the color synthesis prism can be made the same size even if the effective area of ​​the first light modulation element is larger than the effective area of ​​the second light modulation element.

[0085] In addition, since the reduction optical system bends the first color light LB incident on the enlargement-side imaging surface and emits the first color light from the reduction-side imaging surface, the entire projector can be made more compact than when the reduction optical system does not bend the first color light.

[0086] (Appendix 2) The projector described in Supplementary Note 1, further comprising a polarizing plate disposed between the reduction-side image forming surface and the first screen portion.

[0087] This makes it possible to suppress a decrease in the contrast of the first color light incident on the color synthesis prism.

[0088] (Appendix 3) 3. The projector according to claim 1, further comprising a relay lens disposed between the first dichroic mirror and the reflecting mirror.

[0089] This makes it possible to adjust the imaging position of the first color light LB from the first dichroic mirror, so that the first color light from the first dichroic mirror can be uniformly irradiated onto the first light modulation element.

[0090] (Appendix 4) the separation optical system includes a second dichroic mirror that separates the other color light transmitted by the first dichroic mirror in the first direction of the optical axis into a second color light in a second wavelength band including green and a third color light in a third wavelength band including red, the second light modulation element includes a third light modulation element that modulates the second color light separated by the second dichroic mirror, and a fourth light modulation element that modulates the third color light separated by the second dichroic mirror, The projector described in any one of Appendix 1 to 3, characterized in that the color combining prism emits a combined light obtained by combining the first color light whose light beam width has been reduced by the reduction optical system, the second color light modulated by the third light modulation element, and the third color light modulated by the fourth light modulation element.

[0091] This allows the projector to project full-color composite light.

[0092] (Appendix 5) The projector described in Appendix 4, characterized in that the luminous flux width of the first color light incident on the first surface of the color combining prism is the same as the luminous flux width of the second color light incident on the second surface of the color combining prism and the luminous flux width of the third color light incident on the third surface of the color combining prism.

[0093] This makes it easy for the color combining prism to combine the various color lights into one combined light.

[0094] (Appendix 6) the reduction optical system includes a plurality of reflecting surfaces having power; The projector according to any one of claims 1 to 5, wherein both sides of the reduction optical system are telecentric.

[0095] As a result, compared to reduction optical systems that are not telecentric on both sides, the installation accuracy for the first light modulation element is not as strict when incorporating the reduction optical system into a projector. Also, since the first color light traveling from the reduction-side image plane toward the color synthesis prism becomes parallel light, it is easy to suppress the occurrence of various aberrations that occur in the reduction optical system.

[0096] (Appendix 7) the reduction optical system comprises, in order from the enlargement side to the reduction side, a first lens group consisting of a plurality of lenses and having positive power, a second lens group having one or two lenses, at least one of which has negative power, and a third lens group consisting of a plurality of lenses and having positive power, the number of lenses in the first lens group is the same as the number of lenses in the third lens group, The projector according to any one of claims 1 to 5, wherein both sides of the reduction optical system are telecentric.

[0097] As a result, the number of lenses in the first lens group and the third lens group on either side of the second lens group are the same, so the various aberrations that occur in the first lens group can be cancelled out by the third lens group. Also, compared to reduction optical systems that are not telecentric on both sides, the installation accuracy of the first light modulation element is not as strict when incorporating the reduction optical system into a projector. Also, the first color light traveling from the reduction-side image plane toward the color synthesis prism becomes parallel light, making it easier to suppress the occurrence of various aberrations that occur in the reduction optical system. [Explanation of symbols]

[0098] 1...light source, 2...illumination optical system, 3...separation optical system, 5...polarizing plate, 6...reduction optical system, 7...light modulation element, 8...color synthesis prism, 9...projection optical system, 10...control unit, 11...reflecting mirror, 12...lens, 13...lens, 14...reflecting mirror, 15...reflecting mirror, 16...reflecting mirror, 17...reflecting mirror, 19...relay lens, 21...multi-lens, 22...polarizing beam splitter, 23...multi-lens, 24...relay lens, 31...first dichroic mirror, 32...second dichroic mirror, 60...reflecting surface, 60A...magnification side image forming surface, 60B...reduction side image forming surface, 61...first reflecting surface, 62...second reflecting surface, 63...second 3 reflecting surface, 64...lens, 65...diaphragm, 66...first reflecting mirror, 67...second reflecting mirror, 71...first light modulation element, 72...third light modulation element, 73...fourth light modulation element, 75...entrance side polarizing plate, 76...exiting side polarizing plate, 81...first surface, 82...second surface, 83...third surface, 84...fourth surface, 100, 100A, 100B, 100C...projector, G1...first lens group, G2...second lens group, G3...third lens group, L1 to L10...lenses, LD...exiting light, LE...combined light, LB...first color light, LG...second color light, LR...third color light, LC...other color light, M...second optical axis, M1...optical axis, M2...optical axis, N...first optical axis.

Claims

1. A light source; a separation optical system that separates light emitted from the light source into a first color light in a first wavelength band including blue light and another color light in a wavelength band longer than the first color light, and that includes a first dichroic mirror that reflects the first color light in a direction perpendicular to an optical axis of the emitted light; a first light modulation element that modulates the first color light separated by the first dichroic mirror; a second light modulation element that modulates the other color light separated by the first dichroic mirror; a reflecting mirror that reflects the first color light separated by the first dichroic mirror toward the first light modulation element in a direction perpendicular to the first color light; a reduction optical system in which the first light modulation element is disposed on an enlargement-side image forming surface and a light beam width of the first color light modulated by the first light modulation element is reduced on a reduction-side image forming surface; a color synthesis prism that outputs a synthesized light obtained by synthesizing the first color light whose luminous flux width has been reduced by the reduction optical system and the other color light modulated by the second light modulation element; a projection optical system that projects the combined light emitted from the color combining prism; having an effective area of ​​the first light modulation element is larger than an effective area of ​​the second light modulation element; an optical axis of the first light modulation element is parallel to an optical axis of the reduction-side image forming surface; an incident direction of the first color light incident on the first light modulation element is opposite to an exit direction of the first color light exiting from the reduction-side image forming surface, The reduction-side image forming surface is located opposite a first surface of the color synthesis prism onto which the first color light is incident.

2. The projector according to claim 1 , further comprising a polarizing plate disposed between the reduction-side image forming surface and the first screen.

3. 3. The projector according to claim 1, further comprising a relay lens disposed between the first dichroic mirror and the reflecting mirror.

4. the separation optical system includes a second dichroic mirror that separates the other color light transmitted by the first dichroic mirror in the first direction of the optical axis into a second color light in a second wavelength band including green and a third color light in a third wavelength band including red, the second light modulation element includes a third light modulation element that modulates the second color light separated by the second dichroic mirror, and a fourth light modulation element that modulates the third color light separated by the second dichroic mirror, The projector according to claim 1, characterized in that the color combining prism emits a combined light obtained by combining the first color light whose light beam width has been reduced by the reduction optical system, the second color light whose light beam width has been reduced by the third light modulation element, and the third color light whose light beam width has been reduced by the fourth light modulation element.

5. The projector described in claim 4, characterized in that the luminous flux width of the first color light incident on the first surface of the color synthesis prism is the same as the luminous flux width of the second color light incident on the second surface of the color synthesis prism and the luminous flux width of the third color light incident on the third surface of the color synthesis prism.

6. the reduction optical system includes a plurality of reflecting surfaces having power; 2. The projector according to claim 1, wherein both sides of the reduction optical system are telecentric.

7. the reduction optical system comprises, in order from the enlargement side to the reduction side, a first lens group consisting of a plurality of lenses and having positive power, a second lens group having one or two lenses, at least one of which has negative power, and a third lens group consisting of a plurality of lenses and having positive power, the number of lenses in the first lens group is the same as the number of lenses in the third lens group, 2. The projector according to claim 1, wherein both sides of the reduction optical system are telecentric.

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