JP2009216979A - Heat dissipation plate for optical element, polarizing plate, polarization converter, liquid crystal panel, and projector - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a polarizing plate with a heat dissipation plate for an optical element, and also to provide a polarization converter, a liquid crystal panel, and a projector. <P>SOLUTION: The heat dissipation plate 91 is provided in optical elements such as a polarization converter 27, a prepolarization filter 49b, and the liquid crystal panel 41b. Since the heat dissipation plate 91 is constituted of three flat plate members 91x, 91y and 91z formed by using an inorganic crystal material having light transmission properties, optical elements coming close to the heat dissipation plate 91 are cooled without blocking optical paths. Since, at this time, apparent isotropic refractive index characteristics are shown by the composition of the three flat plate members 91x, 91y and 91z, retardation given to a luminous flux from an adjacent optical element and a luminous flux to the optical element is substantially eliminated not only when the luminous fluxes are made incident perpendicularly to the heat dissipation plates 91x, 91y and 91z, but even when the luminous fluxes are made incident at various incident angles. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a heat dissipation plate for an optical element formed of an inorganic crystal material, and a polarizing plate, a polarization conversion device, a liquid crystal panel, and a projector using the same.

As a conventional heat dissipation plate for optical elements, there is one that is incorporated in a polarizing plate of a light valve that constitutes a projector. In this case, the base substrate of the polarizing plate is composed of two uniaxial crystals, and each uniaxial crystal Are arranged in parallel to the surface of the base substrate (see Patent Document 1).
JP 2004-85862 A

  However, in the polarizing plate as described above, with respect to a light beam incident on the surface of the base substrate in an inclined manner, the phase difference is not accurately compensated, and the polarization is disturbed. There was a case that could not be done.

  Accordingly, the present invention provides a heat dissipation plate for an optical element that can accurately compensate for a phase difference and reduce polarization disturbance even when various oblique incident light as well as normal incident light is incident on a polarizing plate or the like. The purpose is to provide.

  Another object of the present invention is to provide a polarizing plate, a polarization conversion device, a liquid crystal panel, and a projector provided with the heat dissipation plate for the optical element.

  In order to solve the above-described problems, the heat dissipation plate for an optical element according to the present invention is formed of an inorganic crystal material, has optical transparency, and has three plate-like shapes arranged with their optical axes crossing each other. It is provided with a member, and an apparent isotropic refractive index characteristic is shown by synthesizing three flat members.

  Since the heat radiating plate includes three flat members made of an optically transparent inorganic crystal material, it is possible to achieve cooling of the optical element adjacent to the heat radiating plate without obstructing the optical path. At this time, since the heat radiating plate exhibits an apparent isotropic refractive index characteristic by combining three flat members, the light flux from the optical element and the light flux to the optical element are incident perpendicular to the heat radiating plate. The phase difference given to these light beams can be substantially eliminated not only in the case of having an angle but also in the case of having various incident angles. Therefore, it is possible to suppress the deterioration of the optical performance of the optical element while ensuring the cooling of the target optical element.

  According to a specific aspect or aspect of the present invention, in the heat dissipation plate for the optical element, the three flat members are each formed of a positive uniaxial crystal so that the optical axes are orthogonal to each other. Has been placed. In this case, each flat member can be formed of the same type of crystal material.

  According to another aspect of the present invention, the three flat members are each formed of a negative uniaxial crystal, and are arranged so that the optical axes are orthogonal to each other. In this case, each flat member can be formed of the same type of crystal material.

  According to still another aspect of the present invention, the three flat members are respectively formed of the same material and have the same thickness. In this case, each flat plate member can be formed of the same crystal material having the same characteristics, and the production of the heat sink can be made relatively simple and inexpensive.

  According to still another aspect of the present invention, the optical axes of the three flat plate members extend parallel or perpendicular to the main surface of each flat plate member. In this case, the optical axis of each flat member can be easily set, and the refractive index characteristic obtained by combining the flat members can be easily adjusted.

  The polarizing plate according to the present invention includes (a) a polarizing layer that transmits polarized light in a predetermined polarization direction, and (b) a support plate that includes the above-described heat dissipation plate for the optical element and supports the polarizing layer. In this polarizing plate, since the polarizing layer is supported by the above-described heat radiating plate, it is possible to prevent the heat radiating plate from affecting the optical action of the polarizing layer while efficiently cooling the polarizing layer.

  A polarization conversion device according to the present invention includes: (a) a conversion main body that separates a light beam from a light source according to a polarization direction and aligns the polarization direction of one separated light beam with the polarization direction of the other separated light beam. And (b) a heat radiating plate for the optical element described above, which is fixed to the light incident side or the light emitting side of the conversion main body. In the present polarization conversion device, since the above-described heat radiating plate is fixed to the light incident side or the light emitting side of the conversion main body, the heat radiating plate cools the conversion main body efficiently, while the heat radiating plate has an optical action of the conversion main body. Can be prevented.

  The liquid crystal panel according to the present invention includes (a) a liquid crystal panel main body that changes the polarization state of incident light in units of pixels, and (b) the above-described optical element fixed to a light incident side or a light emission side of the liquid crystal panel main body. A heat sink. In the present liquid crystal panel, since the above-described heat radiating plate is fixed to the light incident side or the light emitting side of the liquid crystal panel, the heat radiating plate affects the optical action of the liquid crystal panel while efficiently cooling the liquid crystal panel. Can be prevented.

  The projector according to the present invention includes: (a) an illuminating device that emits a light beam for illumination; (b) a liquid crystal display device that is illuminated by the light beam from the illuminating device; and (c) an image formed by the liquid crystal display device. (D) the above-described heat dissipation plate for the optical element is incorporated as a part in at least one of the illumination device and the liquid crystal display device. In this project, since the above-mentioned heat sink is incorporated as a part of at least one of the lighting device and the liquid crystal display device, the heat sink is illuminated while efficiently cooling the important points of the lighting device and the liquid crystal display device. This can prevent the performance of the device and the liquid crystal display device from being affected.

  FIG. 1 is a conceptual diagram illustrating a configuration of an optical system of a projector according to an embodiment of the present invention.

  The projector 100 is an optical device for modulating a light beam emitted from a light source in accordance with image information to form an optical image and enlarging and projecting the optical image on a screen. The projector 100 includes a light source device 10, a uniformizing optical system 20, a color separation / light guiding optical system 30, a light modulation unit 40, a cross dichroic prism 50, and a projection lens 60. Here, the light source device 10 and the homogenizing optical system 20 constitute an illumination device. The light modulation unit 40 includes three liquid crystal light valves 40a, 40b, and 40c. The liquid crystal light valves 40a, 40b, and 40c are liquid crystal display devices that modulate different color lights, respectively.

  In the projector 100, the light source device 10 includes a discharge light-emitting arc tube 11, an elliptical reflector 12, a spherical secondary mirror 13, and a collimating lens 14. The light beam radiated from the arc tube 11 to the surroundings is directly reflected by the reflector 12, or after being reflected by the sub-mirror 13 and further reflected by the reflector 12 to become a convergent light beam. The convergent light beam is converted into a parallel light beam by the collimating lens 14 and enters the first lens array 23 of the front side, that is, the homogenizing optical system 20. In addition, various concave mirrors, such as a paraboloid, can be used instead of the ellipsoidal reflector 12 described above. When a parabolic concave mirror is used, a parallel light beam can be emitted from the light source device 10 without providing the collimating lens 14 or the like after the reflector 12.

  The homogenizing optical system 20 supplies the illumination light with uniform illuminance to the light modulation unit 40. The homogenizing optical system 20 superimposes a first and second lens arrays 23 and 24 that divide a light beam emitted from the light source device 10 into an appropriate state and a plurality of light beams that have passed through both lens arrays 23 and 24. A lens 25 and a polarization conversion device 27 that aligns the polarization direction of the light beam incident on the superimposing lens 25 are provided. The first and second lens arrays 23 and 24 are each composed of a plurality of element lenses 23a and 24a arranged in a matrix. Among these, the light beam that has passed through the collimating lens 14 is divided into a plurality of partial light beams by the element lens 23 a that constitutes the first lens array 23. In addition, each partial light beam from the first lens array 23 is emitted at an appropriate divergence angle by the element lens 24 a constituting the second lens array 24. The superimposing lens 25 appropriately converges the partial light beam emitted from the second lens array 24 and passing through the polarization conversion device 27 as a whole, and superimposes the partial light beam on the illuminated area, that is, the display area of the subsequent liquid crystal light valves 40a, 40b, and 40c. The polarization conversion device 27 includes a conversion main body 27a composed of a PBS array or the like, and the polarization direction of each partial light beam divided by the first lens array 23 and passed through the second lens array 24 is changed to a linear polarization in one direction. Play a role to align. The conversion body 27a is a prism array having a structure in which, for example, four prism elements 27d each having the same structure and extending in the Y direction are arranged in the X direction, along the XY plane perpendicular to the system optical axis SA. Extends two-dimensionally. Further, a light transmitting heat radiating plate 91 is assembled on the incident surface side of the conversion main body 27a in order to cool the conversion main body 27a and the like.

  FIG. 2 is a partial enlarged cross-sectional view for explaining the structure of the polarization conversion device 27. Each prism element 27d constituting the conversion main body 27a is formed by joining a prism 81 having a parallelogram section and prisms 88 and 89 having a right triangle section, and has a rectangular cross section as a whole. . Each prism element 27d is disposed so as to be opposed to the polarization separation film 83 with the prism 81 interposed therebetween, and the polarization separation film 83 disposed in a state of being inclined with respect to the system optical axis SA using the inclined surface of the side surface of the prism 81. And a phase difference plate 85 fixed to the exit surface 81b of the prism 81. On the other hand, the heat radiating plate 91 is joined to the surface IS on the light incident side of the conversion main body 27a. That is, the heat radiating plate 91 is adhered to the incident surface 81a of the prism 81 and the incident-side surface 89a of the prism 89, and is held in a state perpendicular to the system optical axis SA. The heat radiating plate 91 can be bonded and fixed to the incident surface 81a and the surface 89a with, for example, a UV curable adhesive. In order to prevent the light beam from the first lens array 23 from directly entering the prism 89 at a position corresponding to the incident-side surface 89a of the prism 89 in the incident surface S11 of the heat radiating plate 91, light shielding is performed. The mask 86 is formed.

  In this polarization conversion device 27, the incident light IL from the second lens array 24 passes through the heat radiating plate 91 through the opening between the masks 86, and enters the prism 81 of each prism element 27d. Incident light IL incident on the prism 81 is branched by the polarization separation film 83 into a first light beam PL1 which is one of the polarized light on the reflected side and a second light beam PL2 which is the other polarized light on the passing side. . The first light beam PL1 reflected by the polarization separation film 83 is reflected again by the reflection film 84 and is emitted as S-polarized light from the exit surface 81b, but the phase is changed by the phase difference plate 85 and is emitted as P-polarized light. . On the other hand, the second light beam PL2 transmitted through the polarization separation film 83 is emitted from the exit surface 88b as P-polarized light. As described above, the incident light IL incident on the prism element 27d, that is, the polarization conversion device 27 is emitted as illumination in which all the polarization directions are aligned with the P-polarized light.

  In the present embodiment, for example, the phase difference plate 85 can be attached to the exit surface 88b instead of the exit surface 81b. In this case, S-polarized light can be emitted from the polarization conversion device 27.

  FIG. 3 is a conceptual diagram illustrating a cross-sectional structure of the heat radiating plate 91. As shown in the figure, the heat radiating plate 91 is formed by laminating three flat members 91x, 91y, 91z. Here, the incident surface S11 and the exit surface S12 of the first flat plate member 91x are arranged so as to be parallel to each other and parallel to the system optical axis SA. Further, the incident surface S21 and the exit surface S22 of the second flat plate member 91y are also arranged so as to be parallel to each other and parallel to the system optical axis SA, and the incident surface S31 and the exit surface of the third flat plate member 91z. The surfaces S32 are also arranged parallel to each other and parallel to the system optical axis SA. That is, the surfaces S11, S12, S21, S22, S31, and S32 as the main surfaces of the flat plate members 91x, 91y, and 91z are all parallel to each other.

  The first flat plate member 91x is formed of a sapphire plate that is an optical material having a negative uniaxial refractive index. The optical axis of the sapphire plate constituting the first flat plate member 91x extends, for example, in the X-axis direction perpendicular to the system optical axis SA. The second flat plate member 91y is also formed of a sapphire plate that is an optical material having a negative uniaxial refractive index. The optical axis of the sapphire plate constituting the second flat plate member 91y extends, for example, in the Y-axis direction perpendicular to the system optical axis SA. The third flat plate member 91z is also formed of a sapphire plate that is an optical material having a negative uniaxial refractive index. The optical axis of the sapphire plate constituting the third flat plate member 91z extends, for example, in the Z-axis direction parallel to the system optical axis SA. In the above, the thickness of each flat plate member 91x, 91y, 91z in the Z-axis direction, that is, along the system optical axis SA is all equal. Note that the above heat radiating plate 91 can be constituted by only three flat plate members 91x, 91y, 91z, but these flat plate members 91x, 91y, 91z are glass plates made of isotropic refractive index material. It can also be set as the structure supported by etc.

  4A to 4D are diagrams illustrating the functions of the three flat plate members 91x, 91y, and 91z constituting the heat radiating plate 91. FIG.

  As shown in FIG. 4A, the sapphire refractive index ellipsoid RIE1 constituting the first flat plate member 91x corresponds to a negative uniaxial refractive index. In this example, the optical axis OA1 of the refractive index ellipsoid RIE1 extends in the X-axis direction perpendicular to the system optical axis SA, and the refractive index in the X-axis direction is relatively small, but the refraction in the Y-axis and Z-axis directions. The rates are relatively large and equal to each other.

  As shown in FIG. 4B, the sapphire refractive index ellipsoid RIE2 constituting the second flat plate member 91y also corresponds to a negative uniaxial refractive index. In this example, the optical axis OA2 of the refractive index ellipsoid RIE2 extends in the Y-axis direction perpendicular to the system optical axis SA, and the refractive index in the Y-axis direction is relatively small, but the refraction in the X-axis and Z-axis directions. The rates are relatively large and equal to each other.

  As shown in FIG. 4C, the sapphire refractive index ellipsoid RIE3 constituting the third flat plate member 91z also corresponds to a negative uniaxial refractive index. In this example, the optical axis OA3 of the refractive index ellipsoid RIE3 extends in the Z-axis direction parallel to the system optical axis SA, and the refractive index in the Z-axis direction is relatively small, but the refractive in the Y-axis and Z-axis directions. The rates are relatively large and equal to each other.

  FIG. 4D is a diagram for conceptually explaining an overall effect obtained by synthesizing the first, second, and third flat plate members 91x, 91y, and 91z. The refractive index ellipsoid RIEt obtained by synthesizing the refractive index anisotropy of the flat plate members 91x, 91y, 91z is an isotropic sphere with respect to the X-axis, Y-axis, and Z-axis directions. Therefore, the refractive index ellipsoid RIEt is not only isotropic with respect to the light flux in the Z-axis direction that is perpendicularly incident on the incident surface S11 of the heat sink 91 along the system optical axis SA, but also is incident on the heat sink 91. It is isotropic with respect to an inclined light beam having an arbitrary incident angle with respect to the surface S11. That is, the heat radiating plate 91 exhibits an apparently isotropic refractive index characteristic with respect to light beams having various incident angles. As a result, the light fluxes having various incident angles that pass through the heat radiating plate 91 pass through the first, second, and third flat plate members 91x, 91y, and 91z constituting the heat radiating plate 91, so that each flat plate The phase effects received by the members 91x, 91y, and 91z cancel each other, and the overall state is maintained as if it passed through an isotropic refractive index material.

  The first, second, and third flat plate members 91x, 91y, 91z described above are all formed of sapphire, which is an inorganic crystal material, and have a higher thermal conductivity than general glass. Have. More specifically, the thermal conductivity of sapphire is, for example, 42 W / (m · k) at 20 ° C. in the direction parallel to the optical axis. On the other hand, the thermal conductivity of glass is about 1 W / (m · k) although it depends on the type of glass. Therefore, sapphire exhibits a thermal conductivity that is one digit higher than that of general glass. That is, the heat radiating plate 91 obtained by joining the first, second, and third flat plate-like members 91x, 91y, 91z is a heat conductor that is more efficient than a glass plate or the like. It is possible to efficiently cool the optical element in contact with the light source, that is, the conversion main body 27a.

  5 (A) to 5 (D) are diagrams illustrating a modification of the heat radiating plate 91 shown in FIG. 3 and correspond to FIGS. 4 (A) to 4 (D). In this case, each of the plate-like members 91x, 91y, 91z constituting the heat radiating plate 91 is formed of a quartz plate which is an optical material having a positive uniaxial refractive index, and all of these thicknesses are the same. is there.

  As shown in FIG. 5A, the refractive index ellipsoid RIE1 'of the quartz plate constituting the first flat plate member 91x corresponds to a positive uniaxial refractive index. The optical axis OA1 ′ of the refractive index ellipsoid RIE1 ′ extends in the X-axis direction perpendicular to the system optical axis SA, and the refractive index in the X-axis direction is relatively large, but the refractive index in the Y-axis and Z-axis directions. Are relatively small and equal to each other. As shown in FIG. 5B, the refractive index ellipsoid RIE2 'of the crystal plate constituting the second flat plate member 91y also corresponds to a positive uniaxial refractive index. The optical axis OA2 ′ of the refractive index ellipsoid RIE2 ′ extends in the Y-axis direction perpendicular to the system optical axis SA, and the refractive index in the Y-axis direction is relatively large, but the refractive index in the X-axis and Z-axis directions. Are relatively small and equal to each other. As shown in FIG. 5C, the refractive index ellipsoid RIE3 'of the crystal plate constituting the third flat plate member 91z also corresponds to a positive uniaxial refractive index. The optical axis OA3 ′ of the refractive index ellipsoid RIE3 ′ extends in the Z-axis direction parallel to the system optical axis SA. Although the refractive index in the Z-axis direction is relatively large, the refractive index in the X-axis and Y-axis directions. Are relatively small and equal to each other.

  FIG. 5D is a diagram for conceptually explaining an overall effect obtained by synthesizing the flat plate members 91x, 91y, and 91z of the modified example. The refractive index ellipsoid RIEt obtained by synthesizing the refractive index anisotropy of the flat plate members 91x, 91y, 91z is an isotropic sphere with respect to the X-axis, Y-axis, and Z-axis directions. That is, the heat radiating plate 91 of the modified example exhibits apparently isotropic refractive index characteristics with respect to light beams having various incident angles. As a result, the light beams having various incident angles that pass through the heat radiating plate 91 pass through all the flat plate members 91x, 91y, and 91z that constitute the heat radiating plate 91, so that each of the flat plate members 91x, 91y, and 91z. The received phase effect is canceled out, and the overall state is maintained as if it passed through an isotropic refractive index material.

  Quartz, which is the material of the flat plate members 91x, 91y, 91z described above, has a higher thermal conductivity than general glass. More specifically, the thermal conductivity of quartz is, for example, 9.3 W / (m · k) at 70 ° C. in the direction parallel to the optical axis, and 5 ° at 70 ° C. in the direction perpendicular to the optical axis. 4 W / (m · k). On the other hand, the thermal conductivity of glass is about 1 W / (m · k), as already described. Therefore, quartz has a thermal conductivity close to one digit higher than that of general glass. That is, the heat radiating plate 91 obtained by joining the first, second, and third flat plate-like members 91x, 91y, 91z is a heat conductor that is more efficient than a glass plate or the like. It is possible to efficiently cool the optical element in contact with the light source, that is, the conversion main body 27a.

  Various uniaxial crystal materials other than the sapphire and the crystal can be used for the plate-like members 91x, 91y, and 91z constituting the heat radiating plate 91. Further, the flat members 91x, 91y, 91z constituting the heat radiating plate 91 do not have to be formed of the same material as described above, and can be formed of different materials. For example, when different types of negative or positive uniaxial refractive materials are used, the thickness of each refractive material can be adjusted so that the phase difference as a whole does not substantially occur. In addition, the optical axes OA1, OA2, OA3, etc. of the respective plate-like members 91x, 91y, 91z are perpendicular or parallel to the system optical axis SA in consideration of the simplicity of manufacturing, but the optical axes OA1, OA2, OA3. Need not be perpendicular or parallel to the system optical axis SA. Furthermore, when the flat members 91x, 91y, and 91z are not formed of a uniaxial refractive material, the optical axes of the flat members 91x, 91y, and 91z are not orthogonal to each other so that the phase difference does not substantially occur as a whole. A configuration in which the angle is set to a proper angle is also possible.

  FIG. 6 is an enlarged view showing a modification of the polarization conversion device 27 shown in FIG. In this case, a heat radiating plate 91 is assembled on the exit surface side of the conversion main body 27a of the polarization conversion device 27 in order to cool the conversion main body 27a. The heat radiating plate 91 is the same as that shown in FIG. 2, and the function thereof is the same as that shown in FIGS. In the illustrated example, the heat radiating plate 91 is fixed on the exit surface of the phase difference plate 85, but the heat radiating plate 91 is disposed between the exit surfaces 81 b and 88 b of the prisms 81 and 88 and the phase difference plate 85. It can also be provided.

  Returning to FIG. 1, the color separation light guide optical system 30 includes first and second dichroic mirrors 31a and 31b, reflection mirrors 32a, 32b, and 32c, and three field lenses 33a, 33b, and 33c, and is uniform. The illumination light emitted from the optimizing optical system 20 is separated into three colors of red (R), green (G), and blue (B), and each color light is guided to the liquid crystal light valves 40a, 40b, and 40c at the subsequent stage. More specifically, first, the first dichroic mirror 31a reflects R light and transmits G light and B light among the three colors of RGB. The second dichroic mirror 31b reflects G light and transmits B light out of the two colors of GB. In this color separation light guide optical system 30, the R light reflected by the first dichroic mirror 31a enters the field lens 33a for adjusting the incident angle via the reflection mirror 32a. Further, the G light that has been transmitted through the first dichroic mirror 31a and reflected by the second dichroic mirror 31b is incident on the field lens 33b for adjusting the incident angle. Further, the B light that has passed through the second dichroic mirror 31b enters the field lens 33c for adjusting the incident angle through the relay lenses LL1 and LL2 and the reflection mirrors 32b and 32c.

  Each of the liquid crystal light valves 40a, 40b, and 40c is a non-light-emitting light modulator that modulates the spatial intensity distribution of incident illumination light. The liquid crystal light valves 40a, 40b, 40c are respectively illuminated with the three liquid crystal panels 41a, 41b, 41c corresponding to the respective color lights emitted from the color separation light guide optical system 30, and the respective liquid crystal panels 41a, 41b, 41c. Three first polarizing filters 42a, 42b, and 42c respectively disposed on the incident side, three pre-polarizing filters 49a, 49b, and 49c respectively disposed on the exit side of the liquid crystal panels 41a, 41b, and 41c, Three second polarizing filters 43a, 43b, and 43c are provided in the subsequent stage of the pre-polarizing filters 49a, 49b, and 49c.

  In this light modulator 40, the R light reflected by the first dichroic mirror 31a is incident on the liquid crystal light valve 40a via the field lens 33a and the like on the second optical path OP2, and constitutes the liquid crystal light valve 40a. The display area on 41a is illuminated. The G light transmitted through the first dichroic mirror 31a and reflected by the second dichroic mirror 31b is incident on the liquid crystal light valve 40b via the field lens 33b on the first optical path OP1 and constitutes the liquid crystal light valve 40b. The display area on the liquid crystal panel 41b is illuminated. The B light transmitted through both the first and second dichroic mirrors 31a and 31b is incident on the liquid crystal light valve 40c via the field lens 33c and the like on the third optical path OP3, and the liquid crystal panel 41c constituting the liquid crystal light valve 40c. Illuminate the upper display area. Each of the liquid crystal panels 41a to 41c modulates the spatial distribution in the polarization direction of the incident illumination light, and the polarization state of the three colors of light incident on each of the liquid crystal panels 41a to 41c is adjusted on a pixel basis. At this time, the polarization direction of the illumination light incident on the liquid crystal panels 41a to 41c is adjusted by the first polarizing filters 42a to 42c, and each liquid crystal is adjusted by the pre-polarizing filters 49a to 49c and the second polarizing filters 43a to 43c. Modulated light having a predetermined polarization direction is extracted from the modulated light emitted from the panels 41a to 41c. In addition, by providing the pre-polarization filters 49a to 49c in front of the second polarization filters 43a to 43c, unnecessary polarized light can be removed in advance, and an excessive load is prevented from being applied to the second polarization filters 43a to 43c. it can. As described above, each of the liquid crystal light valves 40a, 40b, and 40c forms modulated light, that is, image light of each color corresponding thereto.

  FIG. 7 is an enlarged cross-sectional view illustrating the structure of the green liquid crystal light valve 40b shown in FIG. As described above, the liquid crystal light valve 40b includes the liquid crystal panel 41b, the first polarizing filter 42b, the pre-polarizing filter 49b, and the second polarizing filter 43b.

  In the liquid crystal light valve 40b shown in the figure, the first polarizing filter 42b that is the polarizing element on the incident side and the pre-polarizing filter 49b or the second polarizing filter 43b that is the polarizing element on the exit side are arranged to form a crossed Nicol. Has been.

  Here, the first polarizing filter 42 b includes a flat light transmitting substrate 95 and a polarizing layer 93 attached on the light transmitting substrate 95. The polarizing layer 93 is obtained by, for example, dyeing a PVA (polyvinyl alcohol) polymer with iodine and stretching it in a predetermined direction when forming a film. The polarizing layer 93 is bonded onto the flat surface of the light transmission substrate 95 with a UV effect curable resin or the like. The polarizing layer 93 is not limited to the absorbing polarizing element formed of the organic material as described above, but can be replaced by a polarizing polarizing element formed of an inorganic material or a reflective polarizing element such as a wire grid. On the other hand, the light transmission substrate 95 is formed by processing glass, a crystal material or the like into a flat plate, for example. When the light transmitting substrate 95 is formed of a crystal material such as sapphire or quartz, the effect of cooling the polarizing layer 93 by the light transmitting substrate 95 can be enhanced.

  The pre-polarization filter 49 b includes a heat radiating plate 91 and a polarizing layer 93 attached on the heat radiating plate 91. Here, the polarizing layer 93 is the same as the polarizing layer 93 constituting the first polarizing filter 42b, but the extinction ratio is appropriately adjusted. The heat radiating plate 91 is the same as the heat radiating plate 91 constituting the polarization conversion device 27, and is formed by stacking three flat plate members 91x, 91y, 91z (see FIG. 3). In this case, the heat radiating plate 91 is made of sapphire, quartz, or the like, and can cool the polarizing layer 93 efficiently. In addition, the light flux that has passed through the heat radiating plate 91 is maintained in the same state as when the light passes through the isotropic refractive index material as a whole (see FIGS. 4, 5, etc.). Therefore, the provision of the pre-polarization filter 49b can prevent adverse effects such as a decrease in the contrast of the liquid crystal light valve 40b, and the pre-polarization filter 49b can be prevented from rising in temperature, thereby improving its heat resistance and operational stability. it can. In addition, when the refractive index of the heat sink 91 is anisotropic and has a phase difference, the polarization state of the light beam changes before and after passing through the heat sink 91, so that an unintended light amount change occurs due to the passage through the second polarizing filter 43b. The contrast may also deteriorate.

  In the pre-polarization filter 49b, it is not necessary to provide the heat radiating plate 91 on the light emitting side, and the heat radiating plate 91 can be provided on the light incident side. That is, in this case, the polarizing layer 93 is bonded to the light emission surface of the heat radiating plate 91. Further, the polarizing layer 93 can be sandwiched between a pair of heat sinks 91.

  The second polarizing filter 43 b includes a light transmitting substrate 95 and a polarizing layer 93 attached on the light transmitting substrate 95. Here, the polarizing layer 93 is the same as the polarizing layer 93 constituting the first polarizing filter 42b. The light transmitting substrate 95 is also the same as the light transmitting substrate 95 constituting the first polarizing filter 42b.

  The liquid crystal panel 41 b has a structure in which a heat radiating plate 91 is attached to the liquid crystal panel main body 70. The liquid crystal panel main body 70 includes a first substrate 72 on the incident side and a second substrate 73 on the emission side, with a liquid crystal layer 71 composed of liquid crystal operating in, for example, a twisted nematic mode interposed therebetween. These substrates 72 and 73 are both flat and are arranged such that the normal line of the incident / exit surface is parallel to the system optical axis SA, that is, the Z axis. The first substrate 72 on which the incident light IL enters includes a microlens array 72a extending along a plane parallel to the XY plane. The microlens array 72a has a large number of element lenses EL that are two-dimensionally arranged in a predetermined pattern corresponding to transparent pixel electrodes 77 described later, that is, pixel portions PP.

  In the liquid crystal panel body 70, a transparent common electrode 75 is provided on the surface of the first substrate 72 on the liquid crystal layer 71 side, and an alignment film 76 is formed thereon, for example. On the other hand, on the surface of the second substrate 73 on the liquid crystal layer 71 side, a plurality of transparent pixel electrodes 77 arranged in a matrix and thin film transistors (not shown) electrically connected to the transparent pixel electrodes 77 are provided. And an alignment film 78 is formed thereon, for example. Each pixel portion PP constituting the liquid crystal panel body 70 includes one pixel electrode 77, a part of the common electrode 75, a part of both the alignment films 76 and 78, and a part of the liquid crystal layer 71. Each pixel portion PP is configured such that the light beam of the incident light IL can be narrowed and selectively incident by the micro lens array 72a provided on the first substrate 72 on the incident side. A grid-like black matrix 79 is provided between the first substrate 72 and the common electrode 75 so as to partition each pixel portion PP.

  The heat radiating plate 91 provided on the light emission side of the liquid crystal panel 41b is bonded to the light emission surface of the second substrate 73 and is held in a state perpendicular to the system optical axis SA. The heat radiating plate 91 can be bonded and fixed to the light emission surface of the second substrate 73 by using, for example, a UV curable adhesive. The heat radiating plate 91 is the same as the heat radiating plate 91 constituting the polarization conversion device 27, and is formed by stacking three flat plate members 91x, 91y, 91z (see FIG. 3). In this case, the heat radiating plate 91 is formed of sapphire, crystal, or the like, and can cool the liquid crystal panel body 70 efficiently. In addition, the light flux that has passed through the heat radiating plate 91 is maintained in the same state as when the light passes through the isotropic refractive index material as a whole (see FIGS. 4, 5, etc.). Therefore, the provision of the heat radiating plate 91 can prevent adverse effects such as a decrease in the contrast of the liquid crystal light valve 40b, prevent an increase in temperature of the liquid crystal panel 41b, and increase its heat resistance. When the refractive index of the heat sink 91 is anisotropic and has a phase difference, the polarization state of the light beam changes before and after passing through the heat sink 91, so that an unintended light amount change occurs at the exit of the liquid crystal panel 41b and the contrast is increased. May deteriorate.

  In the liquid crystal panel 41b, it is not necessary to provide the heat radiating plate 91 on the light emitting side, and the heat radiating plate 91 can be provided on the light incident side. That is, in this case, the heat radiating plate 91 is bonded to the light incident surface of the first substrate 72.

  The above is the description of the liquid crystal light valve 40b for G light, but the other liquid crystal light valves 40a and 40c for R light and B light have the same structure as the liquid crystal light valve 40b for G light. ing. That is, also in these liquid crystal light valves 40a and 40c, for example, the heat radiating plate 91 is assembled to the pre-polarization filters 49a and 49c.

  Returning to FIG. 1, the cross dichroic prism 50 combines the image light of each color from the liquid crystal light valves 40a, 40b, and 40c as a light combining optical system for the image light of each color. More specifically, the cross dichroic prism 50 has a substantially square shape in plan view in which four right angle prisms are bonded together, and a pair of dielectric multilayer films intersecting in an X shape at the interface where the right angle prisms are bonded to each other. 51a and 51b are formed. One first dielectric multilayer film 51a reflects R light, and the other second dielectric multilayer film 51b reflects B light. The cross dichroic prism 50 reflects the R light from the liquid crystal light valve 40a by the dielectric multilayer film 51a and emits it to the left in the traveling direction, and the G light from the liquid crystal light valve 40b through the dielectric multilayer films 51a and 51b. The B light from the liquid crystal light valve 40c is reflected by the dielectric multilayer film 51b and emitted to the right in the traveling direction. In this way, the R light, the G light, and the B light are combined by the cross dichroic prism 50 to form combined light that is image light based on a color image.

  The projection lens 60 is a projection optical system, and projects the color image on a screen (not shown) by enlarging the image light by the combined light formed through the cross dichroic prism 50 with a desired magnification.

  In summary, in the projector 100 of the present embodiment, the heat radiating plate 91 is provided in the polarization conversion device 27, the pre-polarization filter 49b, and the liquid crystal panel 41b. Since the heat radiating plate 91 is composed of three plate-like members 91x, 91y, 91z made of an optically transparent inorganic crystal material, an optical element (close to the heat radiating plate 91 without interfering with the optical path) ( Specifically, the cooling of the conversion main body 27a, the polarizing layer 93, the liquid crystal panel main body 70, etc.) can be achieved. At this time, since the apparent isotropic refractive index characteristic is shown by the synthesis of the three flat plate members 91x, 91y, 91z, the light flux from the adjacent optical element (conversion main body 27a, etc.) Even when the light beams are incident on the heat radiating plates 91x, 91y, and 91z perpendicularly, even if they are incident at various incident angles, the phase difference given to these light beams can be substantially eliminated. . Therefore, it is possible to suppress the deterioration of the optical performance of the optical element (conversion body part 27a, etc.) while ensuring the cooling of the adjacent optical element (conversion body part 27a, etc.). As a result, a high-quality image with high brightness and no color unevenness can be stably projected for a long time.

  The present invention is not limited to the above-described embodiment, and can be implemented in various modes without departing from the gist thereof. For example, the following modifications are possible.

  For example, although not specifically mentioned in the above embodiment, an optical compensator for compensating the pretilt of the liquid crystal layer 71 can be inserted into the liquid crystal light valves 40a, 40b, and 40c. Can be cooled by the above-described heat radiating plate 91.

  Various lamps such as a high-pressure mercury lamp and a metal halide lamp are conceivable as lamps used in the light source device 10 of the above embodiment. Further, the light source device 10 can be a type of light source that does not have the secondary mirror 13.

  In the above embodiment, an example in which the present invention is applied to a transmissive projector has been described. However, the present invention can also be applied to a reflective projector. Here, “transmission type” means that a liquid crystal light valve including a liquid crystal panel transmits light, and “reflection type” means that the liquid crystal light valve reflects light. It means that there is. The light modulation device is not limited to a liquid crystal panel or the like, and may be a light modulation device using a micromirror, for example.

  In addition, as the projector, there are a front projector that projects an image from the direction of observing the projection surface and a rear projector that projects an image from the side opposite to the direction of observing the projection surface. The configuration can be applied to both.

  In the above embodiment, only the example of the projector 100 using the three liquid crystal panels 41a to 41c has been described. However, the present invention uses a projector using only one liquid crystal panel and four or more liquid crystal panels. It can also be applied to a projector.

It is sectional drawing explaining the projector of one Embodiment of this invention. It is a figure explaining the structure of a polarization converter. It is the elements on larger scale explaining the structure of a heat sink. (A)-(D) are perspective views explaining the pseudo refractive index isotropy in a heat sink. (A)-(D) are perspective views explaining the pseudo refractive index isotropy in the heat sink of a modification. It is the elements on larger scale explaining the structure of the heat sink of a modification. It is an expanded sectional view explaining the one liquid crystal light valve which comprises the light modulation part shown in FIG.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Light source device, 11 ... Light emission tube, 14 ... Parallelizing lens, 20 ... Uniformation optical system, 23, 24 ... Lens array, 25 ... Superimposing lens, 27 ... Polarization conversion apparatus, 27a ... Conversion main-body part, 91x ... 1st 1 plate member, 91y ... 2nd plate member, 91z ... 3rd plate member, 30 ... color separation light guide optical system, 31a, 31b ... dichroic mirror, 40 ... light modulation part, 40a, 40b, 40c ... liquid crystal Light valve, 41a, 41b, 41c ... liquid crystal panel, 42a, 42b, 42c ... first polarizing filter, 43a, 43b, 43c ... second polarizing filter, 49a, 49b, 49c ... pre-polarizing filter, 50 ... cross dichroic prism, 60 ... Projection lens, 70 ... Liquid crystal panel body, 71 ... Liquid crystal layer, 72 ... First substrate, 73 ... Second substrate, 8 , 88, 89 ... prism, 83 ... polarization separation film, 84 ... reflection film, 85 ... phase difference plate, 86 ... mask, 91 ... heat dissipation plate, 93 ... polarizing layer, 95 ... light transmission substrate, 100 ... projector, OA1, OA2, OA3 ... optical axis, SA ... system optical axis

Claims (9)

Each of which is formed of an inorganic crystal material, has optical transparency, and includes three plate-like members arranged with their optical axes crossing each other,
By combining the three flat plate members, an apparent isotropic refractive index characteristic is shown.
A heat sink for optical elements.   2. The heat dissipation plate for an optical element according to claim 1, wherein the three plate-like members are each formed of a positive uniaxial crystal and arranged so that optical axes thereof are orthogonal to each other.   2. The heat dissipation plate for an optical element according to claim 1, wherein the three plate-like members are each formed of a negative uniaxial crystal and are arranged so that optical axes thereof are orthogonal to each other.   4. The heat dissipation plate for an optical element according to claim 2, wherein the three plate-like members are respectively formed of the same material and have the same thickness. 5.   5. The heat dissipation plate for an optical element according to claim 1, wherein an optical axis of each of the three flat members extends parallel to or perpendicular to a main surface of each flat member. . A polarizing layer that transmits polarized light in a predetermined polarization direction;
A polarizing plate comprising a heat dissipation plate for an optical element according to any one of claims 1 to 5, and a support plate that supports the polarizing layer. A separation body that separates the light flux from the light source according to the polarization direction and aligns the polarization direction of the separated light flux with the polarization direction of the separated light flux;
A polarization conversion device comprising: a heat sink for an optical element according to any one of claims 1 to 5, which is fixed to a light incident side or a light emission side of the conversion main body. A liquid crystal panel body that changes the polarization state of incident light in units of pixels;
A liquid crystal panel provided with the heat sink for optical elements according to any one of claims 1 to 5, which is fixed to a light incident side or a light emission side of the liquid crystal panel main body. An illumination device that emits a luminous flux;
A liquid crystal display device illuminated by a light beam from the illumination device;
A projection lens for projecting an image formed by the liquid crystal display device,
A projector in which the heat dissipation plate for an optical element according to any one of claims 1 to 5 is incorporated as part of at least one of the illumination device and the liquid crystal display device.

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