JP2011090025A - Projector - Google Patents

Abstract

A projector capable of realizing high contrast by reducing leakage of obliquely incident light beams while using a polarizing element with little heating.
A first polarizing element 62b is a reflective polarizing element that uses reflected light, and is disposed so that a reflection axis RX of polarized light is substantially perpendicular to an incident surface, and a second polarizing element 63b is Since it is a polarizing element using transmitted light and is disposed so that the transmission axis TX of polarized light extends in a direction perpendicular to the reflection axis RX, as a result, the optical axis OA1 of the first polarizing element 62b and the second polarization The optical axis OA2 of the element 63b can be arranged in parallel. That is, the apparent angular relationship between the optical axis OA1 of the first polarizing element 62b and the optical axis OA2 of the second polarizing element 63b is maintained with respect to the central light beam and the obliquely incident light beam along the system optical axis SA. Therefore, it is possible to reduce the leakage of the obliquely incident light beam and realize high contrast.
.The

Description

  The present invention relates to a projector that projects a light beam modulated by a light modulation device as an image.

  As a projector, an ordinary polarizing plate is disposed on the light incident side of a transmissive array such as a transmissive liquid crystal array, and a wire grid type polarization separation element is disposed on the light emitting side of the transmissive array, thereby modulating light. There exists what to take out (refer patent document 1).

US Pat. No. 6,666,556

  In the projector disclosed in Patent Document 1, a wire grid type polarization separation element with little heating is used. However, the optical axis of the polarizing plate on the light incident side and the optical axis of the wire grid type polarization separation element on the light emission side The placement relationship is not considered. For this reason, in the projector as described above, there is a possibility that the leakage of the obliquely incident light beam incident obliquely with respect to the optical axis increases and the contrast is lowered.

  SUMMARY An advantage of some aspects of the invention is that it provides a projector capable of realizing high contrast by reducing leakage of obliquely incident light beams while using a polarizing element with little heating.

  In order to solve the above problems, a projector according to the present invention combines a plurality of light modulation devices that respectively modulate light beams of respective colors emitted from an illumination device, and modulated light of each color modulated by the plurality of light modulation devices. A photosynthesis unit. At least one of the plurality of light modulation devices is disposed on the polarization modulation type modulation panel, the first polarizing element disposed on the light incident side of the modulation panel, and the light emission side of the modulation panel. A second polarizing element, and one of the first and second polarizing elements is a reflective polarizing element that uses reflected light, and a polarization reflection axis with respect to a plane including the system optical axis before and after the reflection. The other of the first and second polarizing elements is a polarizing element that uses transmitted light, and is arranged so that the transmission axis extends in a direction perpendicular to the reflection axis.

  According to the projector, one of the first and second polarizing elements is a reflective polarizing element that uses reflected light, and the reflection axis of polarized light is substantially perpendicular to a plane including the system optical axis before and after reflection. As a result, the other of the first and second polarizing elements is a polarizing element using transmitted light and the transmission axis of polarized light extends in a direction perpendicular to the reflection axis. In particular, the optical axis of the first polarizing element and the optical axis of the second polarizing element can be arranged in parallel. That is, the apparent angular relationship of the optical axes of the first and second polarizing elements can be maintained with respect to the central light beam and the oblique incident light beam along the system optical axis, thereby reducing the leakage of the oblique incident light beam. Thus, high contrast can be realized. In addition, by using at least one of the first and second polarizing elements as a reflective polarizing element, it is possible to suppress the heating of the light modulation device and improve durability.

  According to a specific aspect or aspect of the present invention, in the projector, the reflective polarizing element using reflected light is an e-type polarizing element. Here, the e-type polarizing element means one that takes out extraordinary light and uses it while excluding normal light. In the case of a reflective polarizing element, the reflection axis of the polarized light used is abnormal light. Parallel to the corresponding optical axis.

  According to another aspect of the present invention, the reflective polarizing element using reflected light is a structural birefringent polarizing element in which a structure that imparts birefringence is formed on a substrate. In this case, the reflective polarizing element can be highly stable with respect to the usage environment such as temperature.

  According to still another aspect of the present invention, a reflective polarizing element using reflected light has a wire grid on a substrate, and the grid direction is a reflection axis. In this case, the reliability of the reflective polarizing element can be increased at a relatively low cost.

  According to still another aspect of the present invention, the reflective polarizing element using reflected light reflects the polarized light of interest on the surface side of the substrate. In this case, the disturbance of light due to the substrate can be reduced, and the accuracy of light modulation can be increased.

  According to still another aspect of the present invention, the polarizing element using the above-described transmitted light is an o-type polarizing element. Here, the o-type polarizing element means one that takes out normal light and uses it while eliminating extraordinary light, and the transmission axis of the polarized light used is perpendicular to the optical axis corresponding to the extraordinary light. Become.

  According to still another aspect of the present invention, the polarizing element using transmitted light is a reflective polarizing element and is disposed so as to extend substantially perpendicular to the system optical axis. In this case, both the first and second polarizing elements can be reflective polarizing elements, and the durability of the light modulation device can be further enhanced.

  According to still another aspect of the present invention, the polarizing element using transmitted light is a transmissive polarizing element formed of an organic film. In this case, the light modulation device can be made relatively reliable at low cost.

It is a figure explaining the structure of the optical system of the projector which concerns on 1st Embodiment. (A), (B) is a figure explaining the light modulation apparatus of the projector shown in FIG. (A)-(C) is a figure mainly explaining operation | movement of a polarizing element among the light modulation apparatuses shown to FIG. 2 (A). (A), (B) is a figure explaining the light modulation apparatus etc. of the projector which concerns on 2nd Embodiment. It is a figure explaining the structure of the optical system of the projector which concerns on 3rd Embodiment. It is a figure explaining the light modulation apparatus of the projector shown in FIG. (A), (B) is a figure explaining the light modulation apparatus etc. of the projector which concerns on 4th Embodiment.

[First Embodiment]
The configuration of the optical system of the projector according to the first embodiment of the invention will be described below with reference to FIG. In FIG. 1, X, Y, and Z mean three coordinate axes that constitute a three-dimensional orthogonal coordinate system.

  The illustrated projector 100 includes an illumination optical system 20 that emits illumination light, a color separation light guide optical system 40 that separates illumination light from the illumination optical system 20 into three color lights of blue, green, and red, and color separation light guide optics. A light modulation unit 60 that modulates the three color lights emitted from the system 40 in accordance with image information, a light synthesis unit 70 that synthesizes image light of each color emitted from the light modulation unit 60, and a light synthesis unit 70, respectively. A projection optical system 80 that projects the projected image light onto a screen (not shown). Of these, the portions from the illumination optical system 20 to the light combining unit 70 are accommodated in an optical component casing (not shown).

  In the projector 100 described above, the illumination optical system 20 includes the light source device 10, the concave lens 14, the first and second lens arrays 15 and 16, the polarization conversion device 17, and the superimposing lens 18. Among these, the light source device 10 is a light source that emits a light beam for illumination. For example, a light-emitting tube 11 that is a high-pressure mercury lamp or the like, and a light beam emitted forward from the light-emitting tube 11 such as a superimposing lens 18 to the light-emitting tube. And a concave mirror 12 that collects the light beam emitted backward from the arc tube 11 and emits it forward. The concave lens 14 has a role of collimating the light beam from the light source device 10, but may be omitted when the concave mirror 12 is a parabolic mirror, for example. The first lens array 15 includes a plurality of element lenses 15a arranged in a matrix, and divides the light beam emitted from the concave lenses 14 in accordance with the sections of the element lenses 15a. The second lens array 16 includes a plurality of element lenses 16a arranged corresponding to the plurality of element lenses 15a, respectively, and adjusts the divergence state of the divided light flux from each element lens 15a. The polarization conversion device 17 converts the split light beam emitted from the lens array 16 into only linearly polarized light having a polarization plane parallel to the first direction (Y direction in the present embodiment) and supplies it to the next-stage optical system. Part. The superimposing lens 18 appropriately superimposes the illumination light IL as linearly polarized light that has passed through the polarization converter 17 as a whole, so that the superimposing lens 18 is superimposed on the liquid crystal light valves 60b, 60g, and 60r of the respective colors provided in the illuminated region, that is, the light modulation unit 60. Enable lighting. In other words, the illumination light IL that has passed through both the lens arrays 15 and 16 and the superimposing lens 18 passes through the color separation light guide optical system 40 that will be described in detail below, and the liquid crystal panels 61b, 61g and 61r are uniformly superimposed and illuminated.

  The polarization conversion device 17 includes a plurality of prism elements 17a each having a structure in which a PBS and a mirror are incorporated, and a plurality of wave plates 17b attached to one light exit surface of the prism elements 17a. Each prism element 17a is a rod-shaped member extending in the Y direction, and the plurality of prism elements 17a are arranged in the Z direction and arranged in a plate shape extending in parallel to the YZ plane as a whole. The illumination light IL that is linearly polarized light in the first direction is emitted from the polarization conversion device 17 as described above. Here, the first direction is a polarization plane when the optical path of the projector 100 is linearly developed. Or the oscillation direction of the electric field, and the linearly polarized light in the first direction can be switched to a state parallel to the second direction rotated by 90 ° by passing through the liquid crystal panels 61b, 61g, 61r.

  The color separation light guide optical system 40 includes a cross dichroic mirror 21, a dichroic mirror 22, bending mirrors 23a and 23b, first lenses 31a and 31b, and second lenses 32b, 32g, and 32r. Here, the cross dichroic mirror 21 includes a first dichroic mirror 21a and a second dichroic mirror 21b as a pair of separation surfaces. The first and second dichroic mirrors 21a and 21b are orthogonal to each other, and their intersecting axis 21c extends in the Y direction. The first dichroic mirror 21a reflects, for example, blue (B) as one color component included in the illumination light IL, and transmits green (G) and red (R) colors as the other color components. The second dichroic mirror 21b reflects the green (G) and red (R) colors, which are the other color components, and transmits the blue (B) color, which is the one color component. The dichroic mirror 22 reflects, for example, green (G) color as one of the two incident color components, green red (GR) color, and transmits red (R) color as the other. Thereby, the blue light LB, the green light LG, and the red light LR constituting the illumination light IL emitted from the illumination optical system 20 are respectively guided to the first, second, and third optical paths OP1, OP2, and OP3. Each incident on different objects. More specifically, the illumination light IL from the illumination optical system 20 enters the cross dichroic mirror 21. The blue light LB reflected / branched by the first dichroic mirror 21a of the cross dichroic mirror 21 enters the first polarizing element 62b of the liquid crystal light valve 60b via the folding mirror 23a and the like. The green light LG reflected / branched by the second dichroic mirror 21b of the cross dichroic mirror 21 and further reflected / branched by the dichroic mirror 22 through the bending mirror 23b and the like is the first polarizing element 62g of the liquid crystal light valve 60g. Is incident on. Further, the red light LR reflected and branched by the second dichroic mirror 21b of the cross dichroic mirror 21 and branched by the passage of the dichroic mirror 22 is incident on the first polarizing element 62r of the liquid crystal light valve 60r.

  The first lens 31a and the second lens 32b arranged on the first optical path OP1 are provided for adjusting the angle state of the blue light LB incident on the liquid crystal panel 61b. The first lens 31b and the second lens 32g arranged on the second optical path OP2 are provided for adjusting the angle state of the green light LG incident on the liquid crystal panel 61g. The first lens 31b and the second lens 32r arranged on the third optical path OP3 are provided to adjust the angular state of the red light LR incident on the liquid crystal panel 61r. Here, the color filters 25g and 25r provided in association with the second lenses 32g and 32r are not essential, but adjust the luminance balance of the green light LG and the red light LR incident on the liquid crystal panels 61g and 61r. It is provided for.

  The light modulation unit 60 includes three liquid crystal light valves 60b, 60g, and 60r corresponding to the three optical paths OP1, OP2, and OP3 for each color described above. Each of the liquid crystal light valves 60b, 60g, and 60r is a non-light-emitting light modulator that modulates the spatial distribution of the intensity of incident illumination light.

  As shown in FIG. 2A, the liquid crystal light valve 60b for B color includes a liquid crystal panel 61b illuminated by the blue light LB, and a first polarizing element 62b disposed on the upstream side of the optical path, that is, on the light incident side. And a second polarizing element 63b disposed on the downstream side of the optical path, that is, on the light exit side.

  The B-color liquid crystal panel 61b is a transmissive liquid crystal panel, and a description of the illustration is omitted. And a liquid crystal layer hermetically sealed between the incident side substrate and the driving substrate.

  The B-color first polarizing element 62b is a reflective polarizing element that uses reflected light, and is incorporated as an e-type polarizing element. More specifically, the first polarizing element 62b is a structural birefringent polarizing element disposed in a state inclined by about 45 ° with respect to the system optical axis SA. The first polarizing element 62b is provided with a birefringent structure 42 formed by arranging wire grids made of a conductive material extending in the Y direction in a stripe shape on the surface upstream of the optical path of the substrate 41 which is a light transmissive main body. It is a thing. The first polarizing element 62b reflects the first polarized light having the polarization plane in the first direction perpendicular to the XZ plane that is the incident plane, and the second polarization plane has a polarization plane in the second direction parallel to the XZ plane that is the incident plane. Transmits polarized light. In the first polarizing element 62b, the birefringent structure 42 is formed on the inner side, and the disturbance of the light flux due to passing through the substrate 41 after passing through the birefringent structure 42 is prevented.

  The B-color second polarizing element 63b is a reflective polarizing element that uses transmitted light, and is incorporated as an o-type polarizing element. More specifically, the second polarizing element 63b is a structural birefringent polarizing element, similar to the first polarizing element 62b, on the surface upstream of the optical path of the substrate 43, which is a light transmissive main body. A birefringent structure 44 formed by arranging wire grids made of a conductive material extending in the Y direction in stripes is provided. However, the second polarizing element 63b is disposed so as to extend perpendicular to the system optical axis SA, reflects the first polarized light having the polarization plane in the first direction perpendicular to the XZ plane, and is parallel to the XZ plane. The second polarized light having a polarization plane in two directions is transmitted. In the second polarizing element 63b, the birefringent structure 44 is formed on the inner side, and the disturbance of the light flux caused by passing through the substrate 43 before passing through the birefringent structure 44 is prevented.

  The first polarizing element 62b and the second polarizing element 63b described above are arranged so as to constitute crossed Nicols. The liquid crystal panel 61b sandwiched between the first and second polarizing elements 62b and 63b partially transmits the blue light LB incident from the first polarizing element 62b side in the first direction in units of pixels according to the input signal. The first polarized light is changed to the second polarized light in the second direction, and the modulated light after the change is emitted to the second polarizing element 63b side.

  FIG. 3A is a diagram for functionally explaining the first and second polarizing elements 62b and 63b in relation to the refractive index. The first polarizing element 62b is an e-type polarizing element that uses extraordinary light, and the reflection axis RX perpendicular to the incident surface of a typical central light beam along the system optical axis SA of the blue light LB is Y-axis. Extending in the direction. When the first polarizing element 62b is regarded as a birefringent medium, the three-dimensional refractive index ellipsoid is different in only the Y-axis direction, with nx and nz being the refractive index of air and ny being the refractive index of aluminum. It is an ellipsoid with a length. In other words, it can be considered that the optical axis OA1 as the birefringent medium of the first polarizing element 62b using the reflected light extends in the Y-axis direction. That is, in the case of the first polarizing element 62b, the reflection axis RX of the used polarized light (reflected light) is parallel to the optical axis OA1 extending in the Y-axis direction.

  On the other hand, the second polarizing element 63b is an o-type polarizing element using normal light, and the transmission axis TX extends in the X-axis direction. When the second polarizing element 63b is regarded as a birefringent medium, the three-dimensional refractive index ellipsoid is different only in the Y-axis direction, with nx and nz being the refractive index of air and ny being the refractive index of aluminum. It is an ellipsoid with a length. In other words, it can be considered that the optical axis OA2 as a birefringent medium of the second polarizing element 63b using transmitted light extends in the Y-axis direction. That is, in the case of the second polarizing element 63b, the transmission axis TX of the polarized light (transmitted light) used is perpendicular to the optical axis OA2 extending in the Y-axis direction.

  As described above, the optical axis OA1 of the first polarizing element 62b and the optical axis OA2 of the second polarizing element 63b both extend in the Y-axis direction and are parallel to each other. The reflection axis RX of the first polarizing element 62b and the transmission axis TX of the second polarizing element 63b are orthogonal to each other, and satisfy the above-described orthogonal relationship of crossed Nicols.

  FIG. 3B is a Poincare sphere for explaining the polarization state of the light beam passing through the first and second polarizing elements 62b and 63b shown in FIG. The first and second polarizing elements 62b and 63b can effectively reduce leakage light with respect to an obliquely incident light beam from a direction inclined with respect to the system optical axis SA.

  More specifically, a representative central light beam along the system optical axis SA of the blue light LB is emitted from the first polarizing element 62b in a state of a point E on the axis S2 along the equator, and on the equator. The light is emitted from the second polarizing element 63b in a state of a point O which is opposite to the point E. Here, it is assumed that the liquid crystal panel 61b is, for example, a VA type and passes polarized light as it is when no voltage is applied, and the liquid crystal light valve 60b operates in a normally black mode. In this case, the liquid crystal light valve 60b is in a maximum light-shielding state (light-off state) when the voltage is not applied. Further, an oblique incident light beam from a direction inclined with respect to the system optical axis SA in the blue light LB will be considered. When such an obliquely incident light beam passes through the first and second polarizing elements 62b and 63b, the optical axis OA1 of the first polarizing element 62b and the optical axis OA2 of the second polarizing element 63b are parallel to each other. Since the apparent positional relationship between the optical axes OA1 and OA2 is maintained, the same effect as a typical central light beam along the system optical axis SA is received. Specifically, for example, an oblique incident light beam from an azimuth angle inclined by 45 ° with respect to the X axis and the Y axis (the azimuth angle of this inclination is based on the reflection after the first polarizing element 62b) is The light is emitted from the first polarizing element 62b at a point E ′ on the axis S1 along the equator, and is emitted from the second polarizing element 63b at a point O ′ on the equator, which is opposite to the point E ′. That is, the light beam incident on the liquid crystal light valve 60b has an effect that the orthogonal relationship between the first and second polarizing elements 62b and 63b is substantially maintained regardless of whether or not the light beam is parallel to the system optical axis SA. Therefore, leakage light is reduced at various incident angles, and the contrast of the liquid crystal light valve 60b can be increased.

  FIG. 3C is a Poincare sphere for explaining the polarization state of the comparative example. In this case, for example, the first polarizing element 63b is not an e-type polarizing element but an o-type polarizing element. A representative central light beam along the system optical axis SA of the blue light LB is emitted from the first polarizing element 62b in the state of the point I on the axis S2 along the equator, as in the case of FIG. Then, the light is emitted from the second polarizing element 63b in a state of a point O that is opposite to the point I on the equator. On the other hand, the obliquely incident light beam from the direction inclined with respect to the system optical axis SA in the blue light LB passes through the first and second polarizing elements 62b and 63b and the optical axis OA1 of the first polarizing element 62b. Since the optical axis OA2 of the second polarizing element 63b extends in a direction perpendicular to the optical axis OA2, the apparent arrangement relationship between the optical axes OA1 and OA2 changes with the incident azimuth angle and polar angle, and the system optical axis SA It is affected differently from the typical central luminous flux along. Specifically, for example, an obliquely incident light beam from an azimuth angle inclined by 45 ° with respect to the X axis and the Y axis is emitted from the first polarizing element 62b in a state of a point I ′ on the axis S1 along the equator, The light is emitted from the second polarizing element 63b in a state of a point O ′ on the equator that is greatly deviated from the direct opposite of the point I ′. In other words, the light beam incident on the liquid crystal light valve 60b is subjected to an action such that the orthogonal relationship between the first and second polarizing elements 62b and 63b substantially changes depending on the inclination angle or the inclination angle with respect to the system optical axis SA. Therefore, leakage light is generated corresponding to various incident angles, and the contrast of the liquid crystal light valve 60b is lowered.

  2A, the liquid crystal light valve 60g for G color includes a liquid crystal panel 61g illuminated by the green light LG, a first polarizing element 62g disposed on the upstream side of the optical path, that is, the light incident side, and the optical path. And a second polarizing element 63g disposed on the downstream side, that is, the light emission side.

  The liquid crystal panel 61g for G color is a transmissive liquid crystal panel having the same structure as the liquid crystal panel 61b for B color.

  The first polarizing element 62g for G color, like the first polarizing element 62b for B color, is a reflective polarizing element that uses reflected light, and is incorporated as an e-type polarizing element. The first polarizing element 62g reflects the first polarized light having the polarization plane in the first direction perpendicular to the XZ plane that is the incident surface, and transmits the second polarized light perpendicular thereto.

  The second polarizing element 63g for G color, like the second polarizing element 62b for B color, is a reflective polarizing element that uses transmitted light, and is incorporated as an o-type polarizing element. The second polarizing element 63g reflects the first polarized light having the polarization plane in the first direction perpendicular to the XZ plane and transmits the second polarized light perpendicular thereto.

  The 1st polarizing element 62g and the 2nd polarizing element 63g demonstrated above are arrange | positioned so that cross Nicole may be comprised. More specifically, the optical axis OA1 of the first polarizing element 62g and the optical axis OA2 of the second polarizing element 63g extend in the Y-axis direction and are parallel to each other. The reflection axis RX of the first polarizing element 62g and the transmission axis TX of the second polarizing element 63g are orthogonal to each other. The liquid crystal panel 61g sandwiched between the first and second polarizing elements 62g and 63g partially converts the green light LG incident from the first polarizing element 62g side in the first direction in units of pixels according to the input signal. The first polarized light is changed to the second polarized light in the second direction, and the modulated light after the change is emitted to the second polarizing element 63g side.

  As shown in FIG. 2B, the R color liquid crystal light valve 60r includes a liquid crystal panel 61r illuminated by the red light LR, and a first polarizing element 62r disposed on the upstream side of the optical path, that is, on the light incident side. And a second polarizing element 63r disposed on the downstream side of the optical path, that is, on the light exit side.

  The R color liquid crystal panel 61r is a transmissive liquid crystal panel having the same structure as the B color liquid crystal panel 61b.

  The first polarizing element 62r for R color, like the first polarizing element 62b for B color, is a reflective polarizing element that uses reflected light, and is incorporated as an e-type polarizing element. The first polarizing element 62r reflects the first polarized light having the polarization plane in the first direction perpendicular to the XZ plane that is the incident surface, and transmits the second polarized light perpendicular thereto.

  The second polarizing element 63r for R color is a reflective polarizing element that uses transmitted light, and is incorporated as an o-type polarizing element, like the second polarizing element 62b for B color. The second polarizing element 63r reflects the first polarized light having the polarization plane in the first direction perpendicular to the XZ plane, and transmits the second polarized light perpendicular thereto.

  The first polarizing element 62r and the second polarizing element 63r described above are arranged so as to form a crossed Nicol. More specifically, the optical axis OA1 of the first polarizing element 62r and the optical axis OA2 of the second polarizing element 63r extend in the Y-axis direction and are parallel to each other. The reflection axis RX of the first polarizing element 62r and the transmission axis TX of the second polarizing element 63r are orthogonal to each other. The liquid crystal panel 61r sandwiched between the first and second polarizing elements 62r and 63r partially applies the red light LR incident from the first polarizing element 62r side in the first direction in units of pixels according to the input signal. The first polarized light is changed to the second polarized light in the second direction, and the modulated light after the change is emitted to the second polarizing element 63r side.

  Returning to FIG. 1, the light combining unit 70 has a substantially square shape in plan view in which four right-angle prisms are bonded together, and intersects in an X shape as a combined surface at the interface where the right-angle prisms are bonded together. A pair of dichroic mirrors 71a and 71b with the shaft 71c extending in the Y direction are formed. Both dichroic mirrors 71a and 71b are formed of dielectric multilayer films having different characteristics. That is, one first dichroic mirror 71a reflects blue light LB, and the other first dichroic mirror 71b reflects red light LR. The light combining unit 70 reflects the modulated blue light LB from the liquid crystal light valve 60b by the first dichroic mirror 71a and emits it in the X direction by bending the optical path, and modulates the green light LG from the liquid crystal light valve 60g. Is transmitted straight through the first and second dichroic mirrors 71a and 71b to travel straight in the X direction, and the modulated red light LR from the liquid crystal light valve 60r is reflected by the first dichroic mirror 71b to bend the optical path. Inject in the direction. On the light emission side of the light combining unit 70, the color lights LB, LG, and LR are superimposed to perform color composition. Although not shown in the drawing, a half-wave plate may be disposed between the light combining unit 70 and the B color liquid crystal panel 61b or between the light combining unit 70 and the R color liquid crystal panel 61r. . In this case, the blue light LB and the red light LR can be incident on the dichroic mirrors 71a and 71b in the S-polarized state, and the synthesis efficiency of the respective color lights LB, LG, and LR in the light synthesis unit 70 can be increased, and color unevenness can be improved. Occurrence can be suppressed.

  The projection optical system 80 projects the color image light combined by the light combining unit 70 on a screen (not shown) at a desired magnification. That is, a color moving image or a color still image with a desired magnification corresponding to the drive signal or image signal input to each of the liquid crystal panels 61b, 61g, 61r is projected on the screen.

  As is clear from the above description, according to the projector 100 of the present embodiment, the first polarizing elements 62b, 62g, and 62r are reflective polarizing elements that use reflected light, and the system optical axis SA before and after the reflection is determined. The second polarization elements 63b, 63g, and 63r are polarization elements that use transmitted light, and the polarization transmission axis TX is the reflection axis. As a result, the optical axes OA1 of the first polarizing elements 62b, 62g and 62r and the optical axes OA2 of the second polarizing elements 63b, 63g and 63r are arranged in parallel. can do. That is, the optical axis OA1 of the first polarizing elements 62b, 62g, 62r and the optical axis OA2 of the second polarizing elements 63b, 63g, 63r with respect to the central light beam and the obliquely incident light beam along the system optical axis SA. Since the apparent angular relationship can be maintained, leakage of obliquely incident light flux can be reduced and high contrast can be realized. Note that the first polarizing elements 62b, 62g, and 62r are reflective polarizing elements, thereby suppressing the heating of the liquid crystal light valves 60b, 60g, and 60r and improving the durability.

[Second Embodiment]
Hereinafter, the configuration of the optical system of the projector according to the second embodiment will be described. The projector according to the second embodiment is a modification of the projector 100 according to the first embodiment, and portions that are not particularly described are the same as those in the first embodiment.

  FIG. 4A corresponds to FIG. 2A and shows the structure of the liquid crystal light valve 160b for B color of the projector 100 according to the second embodiment. In this case, the liquid crystal light valve 160b for B color is arranged as a light modulation device on the liquid crystal panel 61b illuminated by the blue light LB, the first polarizing element 62b arranged on the upstream side of the optical path, and on the downstream side of the optical path. The second polarizing element 63b and the auxiliary polarizing element 65b disposed on the downstream side of the optical path of the second polarizing element 63b.

  The auxiliary polarizing element 65b is a transmissive polarizing element that uses transmitted light, and is incorporated as an o-type polarizing element. More specifically, the auxiliary polarizing element 65b is obtained by providing a polarizing film 46 on the surface upstream of the optical path of the substrate 45, which is a light transmissive main body. As the polarizing film 46, for example, an organic film having polarizing properties can be used by stretching polyvinyl alcohol dyed with iodine. The auxiliary polarizing element 65b absorbs unnecessary first polarized light having a polarization plane in a first direction perpendicular to the XZ plane, and transmits second polarized light perpendicular thereto. In the auxiliary polarizing element 65b, the polarizing film 46 is formed on the inner side, and there is an effect of suppressing the disturbance of the light flux caused by passing through the substrate 45 before passing through the polarizing film 46 to some extent.

  In the liquid crystal light valve 160b described above, the optical axis OA3 of the auxiliary polarizing element 65b extends in the Y-axis direction similarly to the optical axis OA2 of the second polarizing element 63b, and is parallel to the optical axis OA1 of the first polarizing element 62b. It has become. The transmission axis TX of the auxiliary polarizing element 65b, that is, the second polarizing element 63b is orthogonal to the reflection axis RX of the first polarizing element 62b.

  In the case of the liquid crystal light valve 160b, an additional auxiliary polarizing element 65b is provided, and the degree of polarization of the light beam passing through the liquid crystal light valve 160b can be easily increased.

  In the projector 100 shown in FIG. 1, the liquid crystal light valve 60g for G color and the liquid crystal light valve 60r for R color can also have the same structure as the liquid crystal light valve 160b for B color. That is, a transmissive polarizing element that uses transmitted light and absorbs unnecessary light and functions as an o-type polarizing element can be incorporated as an additional auxiliary polarizing element on the downstream side of the optical path of the second polarizing elements 63g and 63r. .

  FIG. 4B shows a structure of a B-color liquid crystal light valve 260b obtained by modifying the B-color liquid crystal light valve 160b shown in FIG. In this case, the liquid crystal light valve 260b for B color includes the liquid crystal panel 61b illuminated by the blue light LB, the first polarizing element 62b disposed on the upstream side of the optical path, and the second polarized light disposed on the downstream side of the optical path. And an element 263b. The second polarizing element 263b has the same structure as the auxiliary polarizing element 65b shown in FIG.

  In the liquid crystal light valve 260b described above, the optical axis OA2 of the second polarizing element 263b extends in the Y-axis direction and is parallel to the optical axis OA1 of the first polarizing element 62b. The transmission axis TX of the second polarizing element 263b is orthogonal to the reflection axis RX of the first polarizing element 62b.

  In the projector 100 shown in FIG. 1, the liquid crystal light valve 60g for G color and the liquid crystal light valve 60r for R color can also have the same structure as the liquid crystal light valve 260b for B color. That is, instead of the second polarizing elements 63g and 63r, a transmissive polarizing element that uses transmitted light and absorbs unnecessary light and functions as an o-type polarizing element can be incorporated.

[Third Embodiment]
Hereinafter, the configuration of the optical system of the projector according to the third embodiment will be described. The projector according to the third embodiment is a modification of the projector 100 according to the first embodiment, and portions that are not particularly described are the same as those in the first embodiment.

  As shown in FIG. 5, the B color liquid crystal light valve 360b of the projector 100 according to the present embodiment is a liquid crystal panel 61b that is illuminated with blue light LB as a light modulation device, and a first liquid crystal panel 61b that is disposed upstream of the light path. 1 polarization element 362b and the 2nd polarization element 363b arranged on the optical path downstream side are provided. Further, the G liquid crystal light valve 360g is disposed as a light modulation device on the liquid crystal panel 61g illuminated by the green light LG, the first polarizing element 362g disposed on the upstream side of the optical path, and on the downstream side of the optical path. A second polarizing element 363g. Furthermore, the liquid crystal light valve 360r for R color is disposed as a light modulation device on the liquid crystal panel 61r illuminated by the red light LR, the first polarizing element 362r disposed on the upstream side of the optical path, and the downstream side of the optical path. Second polarizing element 363r.

  As shown in FIG. 6, the first polarizing element 362b for B color is a reflective polarizing element that uses transmitted light, and is incorporated as an o-type polarizing element. More specifically, the first polarizing element 362b is a structural birefringent polarizing element, and is a wire made of a conductive material extending in the Y direction on the surface upstream of the optical path of the substrate 43, which is a light transmissive main body. A birefringent structure 44 formed by arranging grids in stripes is provided. The first polarizing element 362b is disposed so as to extend perpendicular to the system optical axis SA, reflects the first polarized light having the polarization plane in the first direction perpendicular to the XZ plane, and the second direction parallel to the XZ plane. Transmits the second polarized light having a polarization plane. In the first polarizing element 362b, the birefringent structure 44 is formed on the inner side, and the disturbance of the light flux due to passing through the substrate 43 after passing through the birefringent structure 44 is prevented.

  The B-color second polarizing element 363b is a reflective polarizing element that uses reflected light, and is incorporated as an e-type polarizing element. More specifically, the second polarizing element 363b is a structural birefringent polarizing element arranged in a state inclined by 45 ° with respect to the system optical axis SA. The second polarizing element 363b is provided with a birefringent structure 42 formed by arranging a wire grid made of a conductive material extending in the Y direction in a stripe shape on the surface upstream of the optical path of the substrate 41 which is a light transmissive main body. It is a thing. The second polarizing element 363b reflects the first polarized light having the polarization plane in the first direction perpendicular to the XZ plane that is the incident plane, and the second polarization element has a polarization plane in the second direction parallel to the XZ plane that is the incident plane. Transmits polarized light. In the second polarizing element 363b, the birefringent structure 42 is formed on the inner side, and the disturbance of the light flux due to passing through the substrate 41 before passing through the birefringent structure 42 is prevented.

  In the liquid crystal light valve 360b described above, the first polarizing element 362b and the second polarizing element 363b are arranged to form a crossed Nicol. More specifically, the optical axis OA1 of the first polarizing element 362b and the optical axis OA2 of the second polarizing element 363b extend in the Y-axis direction and are parallel to each other. The transmission axis TX of the first polarizing element 362g and the reflection axis RX of the second polarizing element 363g are orthogonal to each other. The liquid crystal panel 61b sandwiched between the first and second polarizing elements 362b and 363 partially applies the blue light LB incident from the first polarizing element 362b side in the second direction in units of pixels according to the input signal. The second polarized light is changed to the first polarized light in the first direction, and the modulated light after the change is emitted to the second polarizing element 363b side.

  In the projector 100 of FIG. 5, the liquid crystal light valve 360g for G color and the liquid crystal light valve 360r for R color also have the same structure as the liquid crystal light valve 360b for B color. That is, in the liquid crystal light valve 360g, the first polarizing element 362g is a reflective polarizing element that uses transmitted light and is incorporated as an o-type polarizing element, and the second polarizing element 363g is a reflective type that uses reflected light. A polarizing element, which is incorporated as an e-type polarizing element. In the liquid crystal light valve 360r, the first polarizing element 362r is a reflective polarizing element that uses transmitted light and is incorporated as an o-type polarizing element, and the second polarizing element 363r is a reflective type that uses reflected light. A polarizing element, which is incorporated as an e-type polarizing element.

[Fourth Embodiment]
The configuration of the optical system of the projector according to the fourth embodiment will be described below. Note that the projector according to the fourth embodiment is a modification of the projector 100 according to the third embodiment, and portions that are not particularly described are the same as those of the third embodiment.

  FIG. 7A corresponds to FIG. 6 and shows the structure of the liquid crystal light valve 460b for B color of the projector 100 according to the fourth embodiment. In this case, the liquid crystal light valve 460b for B color is a liquid crystal panel 61b illuminated by the blue light LB, a first polarizing element 362b disposed on the downstream side of the optical path of the liquid crystal panel 61b, and a liquid crystal panel as a light modulator. The second polarizing element 363b disposed on the downstream side of the optical path 61b, the first auxiliary polarizing element 465b disposed on the upstream side of the optical path of the first polarizing element 362b, and the downstream side of the optical path of the second polarizing element 363b. A second auxiliary polarizing element 565b.

  The first auxiliary polarizing element 465b on the most upstream side of the optical path is a transmissive polarizing element that uses transmitted light and absorbs unnecessary light, and is incorporated as an o-type polarizing element. More specifically, the first auxiliary polarizing element 465b is provided with the polarizing film 46 on the surface downstream of the optical path of the substrate 45 which is a light transmissive main body. The first auxiliary polarizing element 465b absorbs the first polarized light having the polarization plane in the first direction perpendicular to the XZ plane and transmits the second polarized light perpendicular to the first polarized light. In the first auxiliary polarizing element 465b, the polarizing film 46 is formed on the inner side, and there is an effect of suppressing the disturbance of the light flux due to passing through the substrate 45 after passing through the polarizing film 46 to some extent.

  The second auxiliary polarizing element 565b on the most downstream side of the optical path is a transmissive polarizing element that uses transmitted light and absorbs unnecessary light, and is incorporated as an o-type polarizing element. More specifically, in the second auxiliary polarizing element 565b, a polarizing film 46 is provided on the surface upstream of the optical path of the substrate 45, which is a light transmissive main body. The second auxiliary polarizing element 565b transmits the first polarized light having the polarization plane in the first direction perpendicular to the XZ plane and absorbs the second polarized light perpendicular thereto. In the second auxiliary polarizing element 565b, the polarizing film 46 is formed on the inner side, and there is an effect of suppressing the disturbance of the light flux caused by passing through the substrate 45 before passing through the polarizing film 46 to some extent.

  In the liquid crystal light valve 460b described above, the optical axis OA3 of the first auxiliary polarizing element 465b extends in the Y-axis direction similarly to the optical axis OA1 of the first polarizing element 362b, and the optical axis OA2 of the second polarizing element 363b. It is parallel. The transmission axis TX of the first auxiliary polarizing element 465b, that is, the first polarizing element 362b is orthogonal to the reflection axis RX of the second polarizing element 363b.

  Further, the optical axis OA4 of the second auxiliary polarizing element 565b extends in the Y-axis direction similarly to the optical axis OA2 of the second polarizing element 363b, and is parallel to the optical axis OA1 of the first polarizing element 362b. The transmission axis TX of the second auxiliary polarizing element 565b, that is, the second polarizing element 362b is orthogonal to the transmission axis TX of the first polarizing element 362b.

  In the case of the liquid crystal light valve 460b, the first and second auxiliary polarizing elements 465b and 565b are provided, and the degree of polarization of the light beam passing through the liquid crystal light valve 460b can be reliably increased.

  In the projector 100 of FIG. 5, the G-color liquid crystal light valve 360g and the R-color liquid crystal light valve 360r have the same structure as the B-color liquid crystal light valve 460b of FIG. Can do. That is, on the upstream and downstream sides of the optical path of the second polarizing elements 363g and 363r, as additional first and second auxiliary polarizing elements, transmitted light is used and absorbs unnecessary light and functions as an o-type polarizing element. Type polarizing elements can be incorporated.

  FIG. 7B shows a structure of a B-color liquid crystal light valve 660b obtained by modifying the B-color liquid crystal light valve 460b shown in FIG. 7A. In this case, the liquid crystal light valve 660b for B color includes the liquid crystal panel 61b illuminated by the blue light LB, the first polarizing element 662b disposed on the upstream side of the optical path, and the second polarized light disposed on the downstream side of the optical path. And an element 363b.

  The first polarizing element 662b is a transmissive polarizing element that uses transmitted light and absorbs unnecessary light, and is incorporated as an o-type polarizing element. More specifically, the first polarizing element 662b is obtained by providing the polarizing film 46 on the surface downstream of the optical path of the substrate 45 which is a light transmissive main body. The first polarizing element 662b absorbs the first polarized light having the polarization plane in the first direction perpendicular to the XZ plane, and transmits the second polarized light perpendicular thereto. In the first polarizing element 662b, the polarizing film 46 is formed on the inner side, and there is an effect of suppressing the disturbance of the light flux due to passing through the substrate 45 after passing through the polarizing film 46 to some extent.

  In the liquid crystal light valve 660b described above, the optical axis OA1 of the first polarizing element 662b extends in the Y-axis direction and is parallel to the optical axis OA2 of the second polarizing element 363b. The transmission axis TX of the first polarizing element 662b is orthogonal to the reflection axis RX of the second polarizing element 363b.

  In the projector 100 shown in FIG. 5, the liquid crystal light valve 360g for G color and the liquid crystal light valve 360r for R color can have the same structure as the liquid crystal light valve 660b for B color. That is, instead of the first polarizing elements 362g and 362r, a transmissive polarizing element that uses transmitted light and absorbs unnecessary light and functions as an o-type polarizing element can be incorporated.

  Although the present invention has been described based on the above embodiments, the present invention is not limited to the above embodiments, and can be implemented in various modes without departing from the gist thereof. Such modifications are also possible.

  In other words, in the above embodiment, an optical compensator for compensating for the pretilt of the liquid crystal constituting the liquid crystal panels 61b, 61g, 61r can be inserted into the liquid crystal light valves 60b, 60g, 60r, 360b, 360g, 360r. .

  In the above embodiment, the blue light LB is guided to the first optical path OP1, the green light LG is guided to the second optical path OP2, and the red light LR is guided to the third optical path OP3. However, the combination of the optical path and the color can be changed. For example, the red light LR can be guided to the first optical path OP1, the green light LG can be guided to the second optical path OP2, and the blue light LB can be guided to the third optical path OP3.

  Further, the method of branching the optical paths OP1, OP2, and OP3 in the color separation / light guiding optical system 40 is not limited to that illustrated in the embodiment, and various methods can be used.

  In the projector 100 of the above embodiment, the first polarizing elements 62b, 62g, 62r, 362b, 362g, and 362r and the second polarizing elements 63b, 63g, 63r, 363b, 363g, and 363r are combined into a wire grid type birefringent structure 42, 44, but these polarizing elements 62b, 62g, 62r, 63b, 63g, 63r,... Are obtained by laminating a three-dimensional dielectric layer in multiple layers, a photonic crystal or other laminated birefringent structure. It can also consist of a body.

  In the projector 100 of the above embodiment, the illumination optical system 20 includes the light source device 10, the pair of lens arrays 15 and 16, the polarization conversion device 17, and the superimposing lens 18, but the lens arrays 15 and 16 are omitted. The light source device 10 can also be replaced with another light source such as an LED.

  In the above embodiment, only the example of the projector 100 using the three liquid crystal light valves 60b, 60g, and 60r or the liquid crystal light valves 360b, 360g, and 360r is given. However, the present invention includes one or two liquid crystal light valves. The present invention can also be applied to a projector using a projector or a projector using four or more liquid crystal light valves.

  In the above embodiment, only an example of a front type projector that projects from the direction of observing the screen is given, but the present invention is also applicable to a rear type projector that projects from the side opposite to the direction of observing the screen. Is possible.

  DESCRIPTION OF SYMBOLS 10 ... Light source device, 14 ... Concave lens, 15, 16 ... Lens array, 17 ... Polarization converter, 18 ... Superimposing lens, 20 ... Illumination optical system, 21 ... Cross dichroic mirror, 22 ... Dichroic mirror, 40 ... Color separation light guide Optical system, 41, 43 ... Substrate, 42, 44 ... Birefringent structure, 45 ... Substrate, 46 ... Polarizing film, 60 ... Light modulator, 60b, 60g, 60r ... Liquid crystal light valve, 360b, 360g, 360r ... Liquid crystal Light valve, 61b, 61g, 61r ... liquid crystal panel, 62b, 62g, 62r ... first polarizing element, 63b, 63g, 63r ... second polarizing element, 65b ... auxiliary polarizing element, 70 ... photosynthesis unit, 71a, 71b ... dichroic Mirror, 80 ... Projection optical system, 100 ... Projector, IL ... Illumination light, LB, LG, R ... color light, OA1, OA2 ... optical axis, OP1, OP2, OP3 ... optical path, SA ... system optical axis, RX ... reflection axis, TX ... transmission axis

Claims (8)

A plurality of light modulation devices that respectively modulate the light beams of the respective colors emitted from the illumination device;
A light combining unit that combines the modulated light of each color modulated by the plurality of light modulation devices,
At least one of the plurality of light modulation devices includes a polarization modulation type modulation panel, a first polarizing element disposed on a light incident side of the modulation panel, and a light emission side of the modulation panel. A second polarizing element that is
One of the first and second polarizing elements is a reflective polarizing element that uses reflected light, and is disposed such that the reflection axis is substantially perpendicular to a plane including the system optical axis before and after reflection.
The other of the first and second polarizing elements is a polarizing element that uses transmitted light, and is disposed so that a transmission axis extends in a direction perpendicular to the reflection axis.
projector.   The projector according to claim 1, wherein the reflective polarizing element using the reflected light is an e-type polarizing element.   The projector according to claim 2, wherein the reflective polarizing element using the reflected light is a structural birefringent polarizing element in which a structure that imparts birefringence is formed on a substrate.   The projector according to claim 3, wherein the reflective polarizing element using the reflected light has a wire grid on the substrate, and the grid direction is the reflection axis.   5. The projector according to claim 3, wherein the reflective polarizing element that uses the reflected light reflects a target polarized light on a surface side of the substrate. 6.   The projector according to any one of claims 1 to 5, wherein the polarizing element using the transmitted light is an o-type polarizing element.   The projector according to claim 6, wherein the polarizing element using the transmitted light is a reflective polarizing element and is disposed so as to extend substantially perpendicular to the system optical axis.   The projector according to claim 6, wherein the polarizing element using the transmitted light is a transmissive polarizing element formed of an organic film.

Images