JP2011197517A - projector - Google Patents

Abstract

A projector capable of achieving high contrast without sacrificing brightness.
Second compensating members 54g, 54r, and 54b as retardation layers arranged between polarizing beam splitters 52g, 52r, and 52b and polarizing layers 55i of outgoing polarizing plates 55g, 55r, and 55b are polarized beams. Since the viewing angle characteristics of the splitters 52g, 52r, and 52b are corrected, it is possible to suppress light leakage biased to light from a specific inclined direction such as up and down due to the polarization beam splitters 52g, 52r, and 52b. Thereby, high contrast can be achieved while ensuring the brightness of the projected image.
[Selection] Figure 1

Description

  The present invention relates to a projector that projects, as an image, a light beam modulated by a light modulation device having a reflective liquid crystal element and a structural birefringent polarizing plate.

  As a projector, a wire grid type PBS is disposed at a position facing the reflective liquid crystal panel at an angle of 45 ° with respect to the optical axis, and the polarized light transmitted through the wire grid type PBS is made incident on the reflective liquid crystal panel. Some of the modulated light reflected by the liquid crystal panel is reflected by a wire grid type PBS and branched (see Patent Document 1).

JP 2008-275798 A

  Wire grid type PBS used in projectors has better viewing angle characteristics compared to prism type PBS, but it is slightly easier to leak light from a direction that is tilted up and down with respect to the optical axis. have. For this reason, in projectors that pursue high contrast, it is necessary to make light as close as possible to a parallel light beam in an illumination system or the like, and as a result, the F number is increased to reduce brightness.

  SUMMARY An advantage of some aspects of the invention is that it provides a projector that can achieve high contrast without sacrificing brightness.

  In order to solve the above-described problems, a first projector according to the present invention includes a reflective liquid crystal element, a structural birefringent flat polarizing beam splitter disposed on a light incident / exit side of the reflective liquid crystal element, and An exit polarizing plate disposed on the light exit side of the polarizing beam splitter, and a retardation layer disposed between the polarizing beam splitter and the polarizing layer of the exit polarizing plate to correct the viewing angle characteristics of the polarizing beam splitter. .

  According to the projector described above, the phase difference layer disposed between the polarizing beam splitter and the polarizing layer of the output polarizing plate corrects the viewing angle characteristics of the polarizing beam splitter. The light leakage biased to the light from the inclined direction can be suppressed. Thereby, high contrast can be achieved while ensuring the brightness of the projected image.

  According to a specific aspect or aspect of the invention, in the projector, the reference direction corresponding to at least one main refractive index of the retardation layer is inclined from the in-plane direction and the normal direction of the output polarizing plate. The axial projection direction in which the reference direction is projected onto the surface of the output polarizing plate is substantially parallel to the absorption axis direction of the output polarizing plate. In this case, it is easy to give the retardation layer birefringence that apparently reduces the birefringence exhibited when the polarizing beam splitter reflects the reflected light from the reflective liquid crystal element. The birefringence exhibited when the polarizing beam splitter reflects the reflected light from the reflective liquid crystal element is approximated by a negative uniaxial refractive index ellipsoid, and its main axis is generally the polarizing beam splitter. With respect to the optical axis (principal ray) of the reflected light resulting from the above, there is a tendency to be inclined in a plane including the tilt direction of the polarization beam splitter (that is, the incident plane).

  According to another aspect of the present invention, the reference direction corresponds to the direction of the main refractive index that is relatively largest among the main refractive indexes of the retardation layer. In this case, the phase difference that the birefringence exhibited by the polarization beam splitter upon reflection gives to the reflected light can be canceled by the phase difference layer.

  According to still another aspect of the invention, the reference direction corresponds to a direction perpendicular to the relatively smallest main refractive index of the main refractive indexes of the retardation layer. In this case, the phase difference layer can cancel the phase difference that the birefringence exhibited by the polarization beam splitter upon reflection gives to the reflected light.

  According to still another aspect of the present invention, the retardation layer exists on the light incident surface side of the output polarizing plate, and the polarizing layer exists on the light output surface side of the output polarizing plate. In this case, the retardation layer can independently compensate only the birefringence exhibited by the polarizing beam splitter upon reflection, and can effectively exhibit the function of the output polarizing plate.

  According to still another aspect of the present invention, the polarizing beam splitter exhibits birefringence when reflecting the reflected light from the reflective liquid crystal element. In this case, a phase disturbance occurs when the polarized light is separated by reflection by the polarization beam splitter. Such a phase disturbance is compensated by the phase difference layer.

  According to still another aspect of the present invention, the output polarizing plate is inclined with the transmission axis direction of the output polarizing plate as the rotation axis. In this case, for light from the direction inclined in the transmission axis direction of the output polarizing plate, the absorption axis direction of the output polarizing plate can have an effect of apparently rotating according to the inclination angle of the output polarizing plate, Light leakage that is biased to light from a direction inclined in the transmission axis direction of the output polarizing plate can be suppressed. Thereby, the contrast can be further improved.

  A second projector according to the present invention includes a reflective liquid crystal element, a plate-like structural birefringent polarization beam splitter disposed on the light incident / exit side of the reflective liquid crystal element, and the light exit side of the polarization beam splitter. The output polarizing plate is inclined with respect to the transmission axis direction of the output polarizing plate as the rotation axis.

  According to the projector, since the output polarizing plate is inclined with the transmission axis direction of the output polarizing plate as the rotation axis, the light from the direction inclined in the transmission axis direction of the output polarizing plate is used as the output polarizing plate. The absorption axis direction of the output polarizing plate can be apparently rotated according to the inclination angle of the output polarizing plate, so that it is possible to suppress light leakage that is biased to light from the direction inclined in the transmission axis direction of the output polarizing plate. . Thereby, high contrast can be achieved while ensuring the brightness of the projected image.

It is a top view explaining the projector which concerns on 1st Embodiment. It is a perspective view which shows the structure of the liquid crystal light valve for specific colors among light modulation parts. (A) is a top view explaining the specific installation state etc. of a 2nd compensation member, (B) and (C) demonstrate typically the function as a phase difference layer of a 2nd compensation member. It is a perspective view and a top view. (A) is a figure explaining the effect which inserted the 2nd compensation member by the relationship with an incident angle, (B) is a figure explaining the case where the 2nd compensation member is removed by the relationship with an incident angle. is there. It is a figure which shows the correspondence of the graph shown to FIG. 4 (A) etc., the inclination direction of a light beam, etc. FIG. (A) is an enlarged view of one graph in FIG. 4 (A), and (B) is an enlarged view of one graph in FIG. 4 (B). It is the histogram which digitized the light leak corresponding to the incident angle shown to FIG. 4 (A) and 4 (B). It is a figure explaining the modification of a 2nd compensation member. It is a top view explaining the projector which concerns on 2nd Embodiment. It is a perspective view which shows the structure of the liquid crystal light valve for specific colors among light modulation parts. It is a perspective view explaining the meaning which inclines an output polarizing plate. (A) is a figure explaining the effect which inclined the output polarizing plate by the relationship with an incident angle, (B) demonstrates the case where the 1st output polarizing plate is not inclined by the relationship with an incident angle. FIG. It is the histogram which digitized the light leakage corresponding to the incident angle shown to FIG. 12 (A) and 12 (B). It is a top view explaining the projector which concerns on 3rd Embodiment. (A) is a figure explaining the effect which inserted the 2nd compensation member and inclined the output polarizing plate by the relationship with an incident angle, (B) removes the 2nd compensation member, and is the 2nd output polarization. It is a figure explaining the case where a board is not inclined in relation to an incident angle. It is the histogram which digitized the light leakage corresponding to the incident angle shown to FIG. 15 (A) and 15 (B).

[First Embodiment]
The projector according to the first embodiment of the present 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.

  A projector 100 shown in FIG. 1 includes an illumination device 20 that emits illumination light, a color separation light guide unit 40 that separates illumination light from the illumination device 20 into three color lights of green, red, and blue, and a color separation light guide unit 40. A light modulation unit 60 that modulates the three color lights emitted from the light, a light synthesis unit 70 that synthesizes the image light of each color emitted from the light modulation unit 60, and a projection that projects the image light synthesized by the light synthesis unit 70 And an optical system 80. Among these, the part from the illuminating device 20 to the photosynthesis part 70 is accommodated in the housing | casing for optical components (not shown). In the case of the projector 100, the system optical axis SA corresponding to the central axis of the light beam in the illumination device 20 to the projection optical system 80 is two-dimensionally arranged parallel to the XY plane (reference plane).

  In the projector 100 described above, the illumination device 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 reflects the light beam emitted backward from the arc tube 11 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 lens 14 in accordance with the division of the element lens 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 second direction (Y direction in the present embodiment) and supplies it to the next-stage optical system. Part. The superimposing lens 18 appropriately converges the linearly polarized illumination light beam IL that has passed through the polarization conversion device 17 as a whole, thereby superimposing illumination on the liquid crystal light valves 60g, 60r, and 60b of the respective colors provided in the illuminated region, that is, the light modulation unit 60. Enable. That is, the illumination light beam IL that has passed through both the lens arrays 15 and 16 and the superimposing lens 18 passes through the color separation light guide unit 40 described in detail below, and the liquid crystal panels 61g and 61r for each color provided in the light modulation unit 60. , 61b are illuminated with uniform illuminance.

  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 Z direction, and the plurality of prism elements 17a are arranged in the Y direction and arranged in a plate shape extending in parallel to the YZ plane as a whole. As described above, the polarization converter 17 emits the linearly polarized illumination light beam IL (Gp, Rp, Bp) in the second direction corresponding to the Y direction.

  The color separation light guide 40 includes a cross dichroic mirror 21, a dichroic mirror 22, bending mirrors 23a and 23b, first lenses 31a and 31b, and second lenses 32g, 32b, and 32r. Here, the cross dichroic mirror 21 includes a first dichroic mirror 21a and a second dichroic mirror 21b. The first and second dichroic mirrors 21a and 21b are orthogonal to each other, and their intersecting axis 21c extends in the Z direction. The first dichroic mirror 21a reflects, for example, green (G) light and red (R) light included in the illumination light beam IL, and transmits the remaining blue (B) light. The second dichroic mirror 21b reflects blue (B) light and transmits green (G) light and red (R) light. The dichroic mirror 22 reflects, for example, green (G) light out of the light including incident green red (GR) light, and transmits the remaining red (R) light. Thereby, the green light Gp, the red light Rp, and the blue light Bp included in the illumination light beam IL emitted from the illumination device 20 are guided to the first, second, and third optical paths OP1, OP2, and OP3, respectively, and are different. Each incident on the object to be illuminated. More specifically, the illumination light beam IL from the illumination device 20 enters the cross dichroic mirror 21. The green light Gp reflected / branched by the first dichroic mirror 21a of the cross dichroic mirror 21, passing through the bending mirror 23a, etc., and further reflected / branched by the dichroic mirror 22 is incident on the polarization beam splitter 52g of the liquid crystal light valve 60g. . Further, the red light Rp reflected / branched by the first dichroic mirror 21a of the cross dichroic mirror 21 and branched by passing through the dichroic mirror 22 is incident on the polarization beam splitter 52r of the liquid crystal light valve 60r. The blue light Bp reflected / branched by the second dichroic mirror 21b of the cross dichroic mirror 21 enters the polarizing beam splitter 52b of the liquid crystal light valve 60b via the folding mirror 23b and the like.

  The first lens 31a and the second lens 32g arranged on the first optical path OP1 are provided to adjust the angular state of the green light Gp incident on the liquid crystal panel 61g. The first lens 31a and the second lens 32r arranged on the second optical path OP2 are provided to adjust the angular state of the red light Rp incident on the liquid crystal panel 61r. The first lens 31b and the second lens 32b arranged on the third optical path OP3 are provided to adjust the angle state of the blue light Bp incident on the liquid crystal panel 61b.

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

  Here, the G-color liquid crystal light valve 60g disposed in the first optical path OP1 includes the liquid crystal panel 61g illuminated by the green light Gp and the green light incident / exit from the liquid crystal light valve 60g as shown in FIG. A polarizing beam splitter 52g for managing the light, a first compensation member 62g disposed opposite to the liquid crystal panel 61g, an incident polarizing plate 51g disposed on the light incident side of the liquid crystal light valve 60g, and a light emitting side of the liquid crystal light valve 60g And a second compensation member 54g disposed on the upstream side of the optical path so as to face the output polarizing plate 55g. Among these, the liquid crystal panel 61g is a reflection type liquid crystal element that includes a reflection plate on the back side and emits modulated light from the surface on which illumination light is incident, and is reflected by the first dichroic mirror 21a and the dichroic mirror 22. The illuminated area is illuminated with uniform illuminance by the green light Gp. The liquid crystal panel 61g is not illustrated, but includes a light transmissive substrate having a transparent electrode and the like, a drive substrate having a reflective pixel electrode and the like, a liquid crystal layer hermetically sealed between the light transmissive substrate and the drive substrate, Is provided. The polarization beam splitter 52g has an exit side pattern layer 53g as a polarization separation surface. The polarization beam splitter 52g is a structural birefringence polarization separation element, specifically, a wire grid polarizing plate in which a grid of a conductive material as an output side pattern layer 53g is formed in a stripe shape on a light transmissive main body flat plate. is there. The exit-side pattern layer 53g is inclined by approximately 45 ° around the Z axis from a state perpendicular to the system optical axis SA. The emission side pattern layer 53g selectively transmits the linearly polarized light in the second direction (in this case, the X direction) with respect to the incident green light Gp and guides it to the liquid crystal panel 61g. The liquid crystal panel 61g converts the polarization state of the green light Gp incident thereon according to the image signal, and reflects this toward the polarization beam splitter 52g. The exit side pattern layer 53g of the polarization beam splitter 52g selectively selects only the linearly polarized light component in the first direction (in this case, the Z direction) perpendicular to the second direction out of the light modulated through the liquid crystal panel 61g. reflect. At this time, by providing the first compensation member 62g, it is possible to compensate for the phase shift caused by the pretilt of the liquid crystal layer of the liquid crystal panel 61g and to increase the degree of polarization or the extinction ratio on the exit side of the polarization beam splitter 52g. The contrast of the liquid crystal light valve 60g can be further improved.

  In the liquid crystal light valve 60g, the green light Gp as the illumination light incident on the polarization beam splitter 52g has a degree of polarization increased by the incident polarizing plate 51g, and the second direction (X direction) corresponding to the polarization plane is the emission side pattern. As a whole, it is substantially parallel to the plane of incidence on the layer 53g (a plane parallel to the XY plane). That is, the green light Gp is incident on the exit-side pattern layer 53g in an approximately P-polarized state and passes efficiently. Further, the green light Gs as image light emitted from the liquid crystal panel 61g and reflected by the polarization beam splitter 52g has a first direction (Z direction) corresponding to the polarization plane of the incident surface (XY) on the emission side pattern layer 53g. The surface is generally perpendicular to the surface parallel to the surface. That is, the green light Gs is incident on the exit-side pattern layer 53g in an approximately S-polarized state and is efficiently reflected. Further, most of the P-polarized light that is not used as image light is transmitted through the polarizing beam splitter 52g. However, the P-polarized light transmission characteristic of the polarizing beam splitter 52g is, for example, a transmission: reflection ratio of 70: 1. Therefore, even if it is the light of a P polarization component, there exists the light reflected by the polarization beam splitter 52g.

  Therefore, an exit polarizing plate 55g is disposed on the side (light exit side) from which the image light (green light Gs) exits from the polarization beam splitter 52g. Since this output polarizing plate 55g absorbs the P-polarized component light reflected by the polarizing beam splitter 52g and transmits the S-polarized component light, the degree of polarization or extinction ratio of the green light emitted from the liquid crystal light valve 60g is reduced. The contrast of the liquid crystal light valve 60g can be made extremely high. For this reason, the output polarizing plate 55g absorbs the light of the polarization component parallel to the absorption axis direction AA corresponding to the P polarization component, and the light of the polarization component parallel to the transmission axis direction TA corresponding to the S polarization component. To Penetrate.

  As for the polarizing beam splitter 52g, as shown in FIG. 2, a periodic direction D1 in which a grid of a conductive material is periodically formed along the main surface of the exit-side pattern layer 53g, and a direction perpendicular to the periodic direction D1. A non-periodic direction D2 is defined. Here, of the light incident on the liquid crystal light valve 60g, the light beam LH that is inclined in the periodic direction D1 or the X direction with respect to the system optical axis SA that is the central axis and incident on the polarization beam splitter 52g is inclined in the left-right direction. Is incident on the polarization beam splitter 52g as polarized light from the light beam. The green light corresponding to the light beam LH reflected by the liquid crystal panel 61g and incident on the polarization beam splitter 52g has relatively no deterioration in polarization characteristics according to its inclination when reflected and emitted by the polarization beam splitter 52g. On the other hand, among the light incident on the liquid crystal light valve 60g, the light beam LV that is inclined in the non-periodic direction D2 or Z direction with respect to the central system optical axis SA as a reference and incident on the polarizing beam splitter 52g is from the direction inclined vertically. Is incident on the polarization beam splitter 52g. Then, the green light corresponding to the light beam LV reflected by the liquid crystal panel 61g and incident on the polarization beam splitter 52g is slightly degraded in polarization characteristics depending on the degree of inclination when reflected and emitted by the polarization beam splitter 52g. In order to suppress such deterioration of polarization characteristics upon reflection by the polarizing beam splitter 52g, a second retardation layer as a retardation layer is formed on the light exit side of the polarization beam splitter 52g and on the light incident side of the exit polarizing plate 55g. A compensation member 54g is provided.

  3A is a diagram for explaining a specific installation state and the like of the second compensation member 54g, and FIGS. 3B and 3C show the function of the second compensation member 54g as a retardation layer. FIG.

  As shown in FIG. 3A, the second compensation member 54g is affixed on a light-transmitting substrate 54h provided on the light incident side of the output polarizing plate 55g. A polarizing layer 54i is attached to the light exit surface side of the substrate 54h. That is, the second compensation member 54g is integrated with the output polarizing plate 55g to constitute the optical element 58.

  As shown in FIG. 3B, the second compensation member 54g is made of a positive uniaxial birefringent material and corresponds to the direction of the relatively largest main refractive index of the refractive index ellipsoid RE1. The reference direction DS1 in which the optical axis extends, that is, the optical axis extends on the xy plane including the system optical axis SA, and from the in-plane direction (x, z direction, etc.) or the normal direction (y direction) of the output polarizing plate 55g. Inclined. Further, the axial projection direction D3 when the reference direction DS1 of the refractive index ellipsoid RE1 is projected onto the surface of the output polarizing plate 55g is parallel to the absorption axis direction AA of the output polarizing plate 55g and perpendicular to the transmission axis direction TA. ing.

  On the other hand, as shown in FIG. 3C, the inventor of the present invention uses a negative uniaxial birefringent material when the polarizing beam splitter 52g reflects incident light from the liquid crystal panel 61g. It was confirmed experimentally that it behaved as if. More specifically, a part of the light modulated by the liquid crystal panel 61g into an S-polarized component and reflected by the polarizing beam splitter 52g becomes a P-polarized component and is absorbed by the output polarizing plate 55g, which is darker than the brightness corresponding to the original image signal. It becomes the image of. Further, a part of the light that is modulated into the P-polarized light component by the liquid crystal panel 61g and reflected by the polarizing beam splitter 52g becomes an S-polarized light component, and is transmitted through the output polarizing plate 55g, resulting in an image brighter than the darkness corresponding to the original image signal. Become. That is, the contrast of the liquid crystal light valve 60g is lowered by the action of the polarization beam splitter 52g changing the polarization state of the reflected light. Therefore, in this embodiment, the second compensation member 54g is provided in order to compensate for the change in the polarization state generated in the light reflected by the polarization beam splitter 52g. Specifically, the main axis corresponding to the direction of the relatively smallest main refractive index of the refractive index ellipsoid RE2 equivalent to the phase effect generated upon reflection by the polarizing beam splitter 52g, that is, the reference direction DS2 in which the optical axis extends is: It substantially coincides with the reference direction DS1 in which the optical axis of the refractive index ellipsoid RE1 of the second compensation member 54g extends. That is, the reference direction DS2 of the refractive index ellipsoid RE2 of the polarizing beam splitter 52g is on the xy plane (that is, the incident surface of the light reflected by the polarizing beam splitter 52g) including the system optical axis SA, and the output polarizing plate 55g. It is inclined from the in-plane direction (x, z direction, etc.) and the normal direction (y direction). Furthermore, the axial projection direction D4 corresponding to the projection of the reference direction DS2 of the refractive index ellipsoid RE2 on the surface of the output polarizing plate 55g is parallel to the absorption axis direction AA of the output polarizing plate 55g.

  As described above, the reference direction DS1 of the positive uniaxial refractive index ellipsoid RE1 in the second compensation member 54g and the negative uniaxial refractive index ellipsoid RE2 recognized to be equivalently present in the polarization beam splitter 52g. When the reference direction DS2 is substantially parallel, the phase difference generated in the light reflected by the polarization beam splitter 52g is canceled by the phase difference generated when the reflected light passes through the second compensation member 54g. Can be made. That is, the second compensation member 54g has a birefringence that reduces the influence of the birefringence on the polarization characteristics of the light when the polarizing beam splitter 52g reflects the light (modulated light) from the liquid crystal panel 61g. By providing it, the viewing angle characteristics of the polarizing beam splitter 52g can be corrected. Therefore, the P-polarized component light incident and reflected from the direction inclined with respect to the z direction or the vertical direction due to the optical characteristics of the polarizing beam splitter 52g can be absorbed by the output polarizing plate 55g. Leakage can be suppressed. Further, the light of the S-polarized component incident and reflected from the direction inclined with respect to the z-direction or the vertical direction due to the optical characteristics of the polarizing beam splitter 52g can be transmitted by the output polarizing plate 55g. Can be maintained. That is, as shown in FIG. 2, the incident light beam LV inclined with respect to the system optical axis SA with respect to the non-periodic direction D2 is reflected by the polarization beam splitter 52g and passes through the second compensation member 54g, so that the eyelid is also substantially isotropic. It is possible to suppress the occurrence of a phase shift of polarized light under the action of passing through a typical material. Similarly, a light beam LV incident with an inclination with respect to the system optical axis SA with respect to the periodic direction D1 is reflected by the polarization beam splitter 52g and passes through the second compensation member 54g, so that the light passes through a substantially isotropic material. Therefore, the occurrence of phase shift remains suppressed.

  FIG. 4A is a diagram for explaining the effect of inserting the second compensation member 54g in the liquid crystal light valve 60g. In FIG. 4A, eight graphs indicated as P1 to P8 are polarizations of the green light Gs incident on the output polarizing plate 55g via the second compensation member 54g for each light beam tilt direction, which will be described later with reference to FIG. Indicates the state. In each graph, the horizontal axis is the direction perpendicular to the light traveling direction and indicates the direction existing in the xy plane, and the vertical axis is the direction perpendicular to the light traveling direction and indicates the direction perpendicular to the horizontal axis. Yes.

  FIG. 4B corresponds to FIG. 4A, and is a diagram illustrating the effect of removing the second compensation member 54g in the liquid crystal light valve 60g.

  FIG. 5 shows a correspondence relationship between the graphs P1 to P8 shown in FIG. Here, the azimuth angle φ = 0 ° -180 ° direction means the X-axis direction (corresponding to the y-axis direction in FIG. 3B) upon incidence on the polarization beam splitter 52g, and the azimuth angle φ = 90 °- The 270 ° direction means the Z-axis direction (corresponding to the z-axis direction) when entering the polarizing beam splitter 52g. The polar angle θ = 0 ° means that the incident angle is parallel to the system optical axis SA, and the polar angle θ = 10 ° indicates that the incident angle is 10 ° with respect to the system optical axis SA. It means that the polar angle θ = 20 ° is an incident angle of 20 ° with respect to the system optical axis SA.

  Since the influence of the polarization beam splitter 52g on the polarization appears noticeably as light leakage during black image display, in FIG. 4A and FIG. 4B, P-polarized light is incident on the polarization beam splitter 52g from the liquid crystal panel 62g. A case where a part thereof is reflected due to the characteristics of the polarizing beam splitter 52g will be described. As shown in FIG. 4A, by providing the second compensation member 54g, the P-polarized light which is inclined from the vertical direction with the azimuth angle φ = 90 ° -270 ° and is incident on the polarization beam splitter 52g is incident on the polarization beam splitter 52g. Even if it becomes elliptically polarized light after being reflected by the light, the linearity of the polarization is ensured by giving a phase difference when passing through the second compensation member 54g, and the light passing through the output polarizing plate 55g is reduced. It can be seen that the contrast of the liquid crystal light valve 60g is improved. As shown in FIG. 4B, when the second compensation member 54g is not provided, the P-polarized light that is inclined from the vertical direction with the azimuth angle φ = 90 ° -270 ° and incident on the polarization beam splitter 52g is a polarized beam. After being reflected by the splitter 52g, it becomes elliptically polarized light, and due to the ellipticity, the light transmitted through the output polarizing plate 55g is increased as compared with the case where the above-described second compensation member 54g is provided, so that the contrast of the liquid crystal light valve 60g is deteriorated. I understand that.

  6A is an enlarged view of the graph P8 in FIG. 4A, and FIG. 6B is an enlarged view of the graph P8 in FIG. 4B. The horizontal axis of the graph is the absorption axis of the output polarizing plate 55g, and the polarization component in the vertical axis direction is transmitted through the output polarizing plate 55g. FIG. 7 is a histogram in which light leakage corresponding to the incident angles shown in FIGS. 4 (A) and 4 (B) is quantified. As is apparent from comparing FIGS. 6A and 6B, or by comparing the difference in presence or absence of the compensation member in FIG. 7, the liquid crystal light valve 60g provided with the second compensation member 54g is more suitable. It can be said that light leakage is reduced as compared with the liquid crystal light valve 60g not provided with the second compensation member 54g.

  Returning to FIG. 1, the red liquid crystal light valve 60r disposed in the second optical path OP2 has the same structure as the green liquid crystal light valve 60g. That is, the liquid crystal light valve 60r is disposed opposite to the liquid crystal panel 61r that is illuminated by the red light Rp, the polarization beam splitter 52r that manages the entrance and exit of red light at the liquid crystal light valve 60r, and the liquid crystal panel 61r. The compensation member 62r, the incident polarizing plate 51r disposed on the light incident side of the liquid crystal light valve 60r, the outgoing polarizing plate 55r disposed on the light outgoing side of the liquid crystal light valve 60r, and the optical path facing the outgoing polarizing plate 55r. And a second compensation member 54r disposed on the upstream side. The liquid crystal panel 61r is a reflection type liquid crystal element that includes a reflector on the back side and emits modulated light from the surface on which the illumination light is incident, and is reflected by the first dichroic mirror 21a and transmitted through the dichroic mirror 22. The illumination area is illuminated with uniform illuminance by the light Rp. The polarization beam splitter 52r is disposed so as to be inclined with respect to the system optical axis SA, and has an exit-side pattern layer 53r as a polarization separation surface. The polarization beam splitter 52r is a wire-grid polarizing plate or other structural birefringence polarization separation element, and selectively applies the linearly polarized light in the second direction (in this case, Y direction) to the incident red light Rp. The light is transmitted and guided to the liquid crystal panel 61r. The liquid crystal panel 61r converts the polarization state of the red light Rp incident on the liquid crystal panel 61r in accordance with the image signal, and reflects this toward the polarization beam splitter 52r. The exit side pattern layer 53r of the polarization beam splitter 52r selectively reflects only the linearly polarized light component in the first direction (in this case, the Z direction) out of the light modulated through the liquid crystal panel 61r. At this time, by providing the compensation member 62r, the phase shift caused by the pretilt of the liquid crystal layer of the liquid crystal panel 61r can be compensated, and the degree of polarization or extinction ratio on the exit side of the polarization beam splitter 52r can be increased. The contrast of the light valve 60r can be improved.

  In the liquid crystal light valve 60r, the red light Rp as the illumination light incident on the polarization beam splitter 52r has a second direction (Y direction) corresponding to the polarization plane of the light incident on the exit side pattern layer 53r (parallel to the XY plane). As a whole. That is, the red light Rp is incident on the exit-side pattern layer 53r in a substantially P-polarized state and efficiently passes therethrough. Further, the red light Rs as the image light emitted from the liquid crystal panel 61r and reflected by the polarization beam splitter 52r has a first direction (Z direction) corresponding to the polarization plane of the incident surface on the emission side pattern layer 53r ( The surface as a whole is substantially perpendicular to the plane parallel to the XY plane. That is, the red light Rs is incident on the exit-side pattern layer 53r in an approximately S-polarized state and is efficiently reflected. Further, most of the P-polarized light that is not used as image light is transmitted through the polarizing beam splitter 52r. However, the P-polarized light transmission characteristic of the polarizing beam splitter 52r is, for example, a transmission: reflection ratio of 70: 1. Therefore, even if it is the light of a P polarization component, there exists the light reflected by the polarization beam splitter 52g.

  In the liquid crystal light valve 60r described above, the second compensation member is interposed between the polarizing beam splitter 52r and the output polarizing plate 55r in order to prevent light leakage caused by a phase shift given to the light reflected by the polarizing beam splitter 52r. 54r is provided. That is, in the red liquid crystal light valve 60r, as in the case of the green liquid crystal light valve 60g shown in FIG. 2, the largest main axis of the positive uniaxial refractive index ellipsoid in the second compensation member 54r is obtained. The main axis corresponding to the direction of the refractive index, that is, the reference direction which is the direction in which the optical axis extends, and the relatively smallest main refraction of the negative uniaxial refractive index ellipsoid recognized to be equivalent to the polarizing beam splitter 52r. The main axis corresponding to the rate direction, that is, the reference direction in which the optical axis extends is made substantially parallel. Thereby, the phase difference generated in the light reflected by the polarization beam splitter 52r can be offset by the phase difference generated when the reflected light passes through the second compensation member 54r. That is, the second compensation member 54r has a birefringence that reduces the influence of the birefringence on the polarization characteristics of the light, which is shown when the polarizing beam splitter 52r reflects the light (modulated light) from the liquid crystal panel 61r. Thus, the viewing angle characteristic of the polarizing beam splitter 52r can be corrected, and the P-polarized light component incident and reflected from the direction inclined with respect to the Z direction or the vertical direction due to the optical characteristics of the polarizing beam splitter 52r. Can be absorbed by the output polarizing plate 55r, so that red light leakage can be suppressed.

  The blue liquid crystal light valve 60b disposed in the third optical path OP3 has the same structure as the green liquid crystal light valve 60g. That is, the liquid crystal light valve 60b is disposed opposite to the liquid crystal panel 61b that is illuminated by the blue light Bp, the polarization beam splitter 52b that manages the incoming and outgoing of blue light at the liquid crystal light valve 60b, and the liquid crystal panel 61b. The compensation member 62b, the incident polarizing plate 51b disposed on the light incident side of the liquid crystal light valve 60b, the outgoing polarizing plate 55b disposed on the light outgoing side of the liquid crystal light valve 60b, and the optical path facing the outgoing polarizing plate 55b. And a second compensation member 54b disposed on the upstream side. The liquid crystal panel 61b is a reflection type liquid crystal element that includes a reflector on the back side and emits modulated light from the surface on which illumination light is incident. The liquid crystal panel 61b is illuminated by the blue light Bp reflected by the second dichroic mirror 21b. Is illuminated with uniform illuminance. The polarization beam splitter 52b is disposed so as to be inclined with respect to the system optical axis SA, and has an exit-side pattern layer 53b as a polarization separation surface. The polarization beam splitter 52b is a wire-grid polarizing plate or other structural birefringence polarization separation element, and selectively applies the linearly polarized light in the second direction (in this case, Y direction) to the incident blue light Bp. The light is transmitted and guided to the liquid crystal panel 61b. The liquid crystal panel 61b converts the polarization state of the blue light Bp incident thereon according to the image signal, and reflects this toward the polarization beam splitter 52b. The exit side pattern layer 53r of the polarization beam splitter 52b selectively reflects only the linearly polarized light component in the first direction (in this case, the Z direction) out of the light modulated through the liquid crystal panel 61b. At this time, by providing the compensation member 62b, the phase shift caused by the pretilt of the liquid crystal layer of the liquid crystal panel 61b can be compensated, and the degree of polarization or extinction ratio on the exit side of the polarization beam splitter 52b can be increased. The contrast of the light valve 60b can be improved.

  In the liquid crystal light valve 60b, the blue light Bp as the illumination light incident on the polarization beam splitter 52b has a second direction (Y direction) corresponding to the polarization plane thereof that is incident on the exit side pattern layer 53b (parallel to the XY plane). As a whole. That is, the blue light Bp is incident on the exit-side pattern layer 53b in a substantially P-polarized state and passes efficiently. Further, the blue light Bs as the image light emitted from the liquid crystal panel 61b and reflected by the polarization beam splitter 52b has a first direction (Z direction) corresponding to the polarization plane of the incident surface on the emission side pattern layer 53b ( The surface as a whole is substantially perpendicular to the plane parallel to the XY plane. That is, the blue light Bs is incident on the exit-side pattern layer 53b in an approximately S-polarized state and is efficiently reflected. Further, most of the P-polarized light that is not used as image light is transmitted through the polarizing beam splitter 52r. However, the P-polarized light transmission characteristic of the polarizing beam splitter 52r is, for example, a transmission: reflection ratio of 70: 1. Therefore, even if it is the light of a P polarization component, there exists the light reflected by the polarization beam splitter 52g.

  In the liquid crystal light valve 60b described above, the second compensation member is interposed between the polarizing beam splitter 52b and the output polarizing plate 55b in order to prevent light leakage due to a phase shift given to light reflected by the polarizing beam splitter 52b. 54b is provided. That is, in the blue liquid crystal light valve 60b, as in the case of the green liquid crystal light valve 60g shown in FIG. 2, the largest main axis of the positive uniaxial refractive index ellipsoid in the second compensation member 54b is obtained. The main axis corresponding to the direction of the refractive index, that is, the reference direction which is the direction in which the optical axis extends, and the relatively smallest main refraction of the negative uniaxial refractive index ellipsoid recognized to be equivalent to the polarizing beam splitter 52b. The main axis corresponding to the direction of the rate, that is, the reference direction in which the optical axis extends is made substantially parallel. Thereby, the phase difference generated in the light reflected by the polarization beam splitter 52b can be offset by the phase difference generated when the reflected light passes through the second compensation member 54b. That is, the second compensation member 54b has a birefringence that reduces the influence of the birefringence on the polarization characteristics of the light, which is shown when the polarizing beam splitter 52b reflects the light (modulated light) from the liquid crystal panel 61b. Thus, the viewing angle characteristic of the polarizing beam splitter 52b can be corrected, and the P-polarized light component incident and reflected from the direction inclined with respect to the Z direction or the vertical direction due to the optical characteristics of the polarizing beam splitter 52b. Light can be absorbed by the output polarizing plate 55b, so that light leakage of blue light can be suppressed.

  The light synthesizing unit 70 has a substantially square shape in plan view in which four right-angle prisms are bonded, and the interface where the right-angle prisms are bonded to each other intersects in an X shape as a combined surface and the cross axis 71c is in the Y direction. A pair of extending dichroic mirrors 71a and 71b is formed. Both dichroic mirrors 71a and 71b are formed of dielectric multilayer films having different characteristics. That is, one first dichroic mirror 71a reflects red light LR, and the other first dichroic mirror 71b reflects blue light LB. The light combining unit 70 transmits the modulated green light LG from the liquid crystal light valve 60g through the first and second dichroic mirrors 71a and 71b to advance straight in the X direction, and the modulated red light from the liquid crystal light valve 60r. LR is reflected by the first dichroic mirror 71a to bend the optical path and emitted in the X direction, and modulated blue light LB from the liquid crystal light valve 60b is reflected by the second dichroic mirror 71b to bend the optical path. Inject in the direction. On the light emitting side of the light combining unit 70, the color lights LG, LB, and LR are superimposed to perform color composition. A half-wave plate 56 is disposed between the light combining unit 70 and the liquid crystal panel 61g for G color. In this case, the green light LG can be incident on the dichroic mirrors 71a and 71b in the P-polarized state, the synthesis efficiency of the color lights LG, LR, and LB in the light synthesis unit 70 can be increased, and the occurrence of color unevenness can be suppressed. it can.

  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 61g, 61r, 61b is projected on the screen.

  According to the projector 100 of the first embodiment described above, the second compensation as a retardation layer disposed between the polarizing beam splitters 52g, 52r, 52b and the polarizing layer 55i of the output polarizing plates 55g, 55r, 55b. Since the members 54g, 54r, and 54b correct the viewing angle characteristics of the polarizing beam splitters 52g, 52r, and 52b, the members 54g, 54r, and 54b are biased toward light from a specific inclined direction such as up and down due to the polarizing beam splitters 52g, 52r, and 52b. Light leakage can be suppressed. Thereby, high contrast can be achieved while ensuring the brightness of the projected image.

  The second compensation members 54g, 54r, and 54b are not limited to those formed of a positive uniaxial birefringent material as shown in FIGS. It can also be formed of a refractive material. As shown in FIG. 8, the second compensation member 154g of the modification is made of a negative uniaxial birefringent material, and corresponds to the relatively smallest main refractive index of the refractive index ellipsoid RE1 ′. The main axis, that is, the reference direction DS1 ′ in which the optical axis extends is on the xy plane including the system optical axis SA, and from the in-plane direction (x, z direction, etc.) or the normal direction (y direction) of the output polarizing plate 55g. Inclined. Further, the axial projection direction D3 when the reference direction DS1 ′ of the refractive index ellipsoid RE1 ′ is projected onto the surface of the output polarizing plate 55g is parallel to the absorption axis direction AA of the output polarizing plate 55g. The reference direction DS1 ′ of the refractive index ellipsoid RE1 ′ is a main axis corresponding to the relatively smallest main refractive index of the negative uniaxial refractive index ellipsoid RE2 recognized to be equivalent to the polarizing beam splitter 52g. That is, it is perpendicular to the reference direction DS2, which is the direction in which the optical axis extends. Also in this case, it is possible to provide an effect of canceling out the phase difference generated in the reflected light from the polarization beam splitter 52g by the phase difference generated when the light passes through the second compensation member 54g. The other second compensation members 54r and 54b shown in FIG. 1 can also be formed of a negative uniaxial birefringent material cut out similarly to FIG.

  The second compensation members 54g, 54r, and 54b can be formed of a biaxial birefringent material. In this case, for example, in FIG. 3B, the reference direction DS1 in which the main axis of the refractive index ellipsoid RE1 of the second compensation member 54g extends is set to the direction of the largest main refractive index in the biaxial birefringent material. By doing so, approximate phase difference compensation becomes possible. Further, for example, in FIG. 8, the reference direction DS1 ′ in which the main axis of the refractive index ellipsoid RE1 ′ of the second compensation member 154g extends is set to the direction of the smallest main refractive index in the biaxial birefringent material. Thus, approximate phase difference compensation is possible.

[Second Embodiment]
Hereinafter, the configuration of the optical system of the projector according to the second embodiment will be described. Note that the projector 200 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.

* Please correct the figure number in Figure 10 from 60g to 260g *
As shown in FIGS. 9 and 10, the green liquid crystal light valve 260g in the light modulator 260 does not have the second compensation member 54g. Instead, the output polarizing plate 255g is arranged around the Z axis. It is rotated and inclined with respect to the YZ plane.

  The function of the output polarizing plate 255g will be described with reference to FIG. 11. The output polarizing plate 255g is assumed to be rotated α degrees around the Z axis, that is, the transmission axis direction TA, for example, counterclockwise.

  In this case, the light beam LV1 that is inclined in the + Z direction with respect to the system optical axis SA and enters the output polarizing plate 255g has an angle β with respect to the absorption axis direction AA of the output polarizing plate 255g even if the polarization direction is parallel to the Y direction. The light is incident on the output polarizing plate 255g as if it is rotated clockwise. Therefore, when the polarization direction D6 of the light beam LV1 is originally rotated counterclockwise by an angle β with respect to the Y direction, the light beam LV1 is in a state where the polarization direction D6 coincides with the absorption axis direction AA of the output polarizing plate 255g. Thus, the light enters the output polarizing plate 255g. That is, when light corresponding to the light beam LV1 incident on the output polarizing plate 255g in a state tilted in the + Z direction with respect to the system optical axis SA is reflected by the polarization beam splitter 52g, the main polarization direction D6 is counterclockwise. , The main polarization direction D6 of the light beam LV1 reflected by the polarization beam splitter 52g is rotated by α degrees counterclockwise when viewed from the + Z direction. As a result, it can be matched with the absorption axis direction AA.

  On the other hand, the light beam LV2 that is inclined in the −Z direction with respect to the system optical axis SA and enters the output polarizing plate 255g has an angle β with respect to the absorption axis direction AA of the output polarizing plate 255g even if the polarization direction is parallel to the Y direction. Only when it is rotated counterclockwise, it enters the output polarizing plate 255g. Therefore, when the polarization direction D7 of the light beam LV2 is originally rotated clockwise by the angle β with respect to the Y direction, the light beam LV2 is in a state where the polarization direction D7 coincides with the absorption axis direction AA of the output polarizing plate 255g. , Is incident on the output polarizing plate 255g. That is, when the light beam LV2 incident on the output polarizing plate 255g in a state inclined in the −Z direction with respect to the system optical axis SA is reflected by the polarization beam splitter 52g, the main polarization direction D6 is clockwise by an angle β. If it rotates, the main polarizing direction D7 of the light beam LV2 reflected by the polarizing beam splitter 52g is rotated by α degrees counterclockwise when viewed from the + Z direction, so that the main polarizing direction D7 of the outgoing polarizing plate 255g As a result, it can be matched with AA.

  As is clear from the above, in the case of this embodiment, in the liquid crystal light valve 260g, light leakage caused by the phase shift generated in the light reflected by the polarizing beam splitter 52g is caused in the transmission axis direction TA of the output polarizing plate 255g. It can be reduced by rotation or tilting around.

  FIG. 12A is a diagram for explaining the effect of inclining the output polarizing plate 255g from the state perpendicular to the system optical axis SA in the liquid crystal light valve 260g. In FIG. 12A, eight graphs indicated as P1 to P8 show the polarization states when the P-polarized light incident on the polarizing beam splitter 52g is reflected by the polarizing beam splitter 52g and then incident on the output polarizing plate 255g. Show. FIG. 12B corresponds to FIG. 12A, and is a diagram for explaining a case where the output polarizing plate 255g is kept perpendicular to the system optical axis SA in the liquid crystal light valve 260g. In FIGS. 12A and 12B, the graphs P1 to P8 correspond to the inclination direction or the incident direction shown in FIG.

  As shown in FIG. 12 (A), by appropriately tilting the output polarizing plate 255g, the P-polarized light incident on the polarizing beam splitter 52g while being inclined from the vertical direction of the azimuth angle φ = 90 ° -270 ° is incident on the polarizing beam splitter 52g. Even if the light is reflected by the light and becomes elliptically polarized light, the main polarization direction is coincident with the absorption axis direction AA of the output polarizing plate 255g, and the light transmitted through the output polarizing plate 255g can be reduced. It can be seen that the contrast is improved. As shown in FIG. 12B, when the output polarizing plate 255g is not tilted, the P-polarized light that is inclined from the vertical direction with the azimuth angle φ = 90 ° -270 ° and is incident on the polarizing beam splitter 52g is polarized beam splitter 52g. When the light is reflected into elliptical polarized light, the main polarization direction does not coincide with the absorption axis direction AA of the output polarizing plate 255g, so that the contrast of the liquid crystal light valve 260g is deteriorated.

  FIG. 13 is a histogram in which light leakage corresponding to the incident angles shown in FIGS. 12 (A) and 12 (B) is quantified. As is clear by comparing the difference in presence / absence of the inclination of the output polarizing plate 255g in FIG. 13, the liquid crystal light valve 260g having the output polarizing plate 255g appropriately inclined does not incline the output polarizing plate 255g. It can be said that the amount of light leaked is smaller than 260 g.

  The above is a description of the liquid crystal light valve 260g for green, but the same applies to the liquid crystal light valve 260r for red and the liquid crystal light valve 260b for blue, and the output polarizing plates 255r and 255b are arranged around the Z axis. It is rotated and tilted with respect to the XZ plane, and light leakage is reduced for a tilted light beam from the vertical direction to improve contrast.

  According to the projector 200 of the second embodiment described above, the output polarizing plates 255g, 255r, and 255b are inclined with the transmission axis direction TA as the rotation axis, so that the transmission of the output polarizing plates 255g, 255r, and 255b is performed. With respect to light from a direction inclined in the axial direction TA, the absorption axis direction AA of the output polarizing plates 255g, 255r, and 255b has an effect of apparently rotating according to the inclination angle of the output polarizing plates 255g, 255r, and 255b. Therefore, it is possible to suppress light leakage biased to light from a direction inclined in the transmission axis direction TA of the output polarizing plates 255g, 255r, and 255b. Thereby, high contrast can be achieved while ensuring the brightness of the projected image.

[Third Embodiment]
Hereinafter, the configuration of the optical system of the projector according to the third embodiment will be described. Note that the projector 300 of the third embodiment is a modification of the projector 100 of the first embodiment, and portions that are not particularly described are the same as those of the first embodiment.

  As shown in FIG. 14, the liquid crystal light valve 360g for green in the light modulation unit 360 rotates the second compensation member 54g and the output polarizing plate 255g around the Z axis to make YZ perpendicular to the system optical axis SA. It is inclined with respect to the surface. That is, the projector 300 according to the third embodiment is a combination of the projector 100 according to the first embodiment provided with the second compensation member 54g and the projector 200 according to the second embodiment in which the output polarizing plate 255g is inclined. The function and insertion effect of the second compensation member 54g are the same as those of the first embodiment, and the function and inclination effect of the output polarizing plate 255g are the same as those of the second embodiment.

  FIG. 15A is a diagram for explaining the effect of inclining the output polarizing plate 255g from the state perpendicular to the system optical axis SA by inserting the second compensation member 54g in the optical path in the liquid crystal light valve 360g. In FIG. 15A, eight graphs indicated as P1 to P8 indicate the polarization state of green light incident on the output polarizing plate 255g. FIG. 15 (B) corresponds to FIG. 15 (A). In the liquid crystal light valve 360g, the second compensation member 54g is removed, and the output polarizing plate 255g is kept perpendicular to the system optical axis SA. FIG. 15A and 15B, the graphs P1 to P8 correspond to the inclination direction or the incident direction shown in FIG.

  As shown in FIG. 15 (A), the second compensation member 54g is inserted and the output polarizing plate 255g is appropriately tilted so that it is tilted from the vertical direction of the azimuth angle φ = 90 ° -270 ° and incident on the polarizing beam splitter 52g. Even if the P-polarized light is reflected by the polarizing beam splitter 52g and becomes elliptically polarized light, the linearity of the polarized light is ensured by the action of the second compensation member 54g and the output polarizing plate 255g, and the main polarization direction is emitted. Since it coincides with the absorption axis direction AA of the polarizing plate 255g, it can be seen that the contrast of the liquid crystal light valve 360g is improved. As shown in FIG. 15B, when the second compensating member 54g is removed and the output polarizing plate 255g is not tilted, the polarizing beam splitter 52g is tilted from the vertical direction with the azimuth angle φ = 90 ° -270 °. When the incident P-polarized light is reflected by the polarizing beam splitter 52g and becomes elliptically polarized light, it remains as elliptically polarized light, and its main polarization direction does not coincide with the absorption axis direction AA of the output polarizing plate 255g, so that the liquid crystal light valve 360g It can be seen that the contrast deteriorates.

  FIG. 16 is a histogram in which light leakage corresponding to the incident angles shown in FIGS. 15A and 15B is quantified. Compare the difference between the case where the second compensation member 54g in FIG. 16 is provided and the second compensation member 54g and the output polarizing plate 255g are inclined and the case where the second compensation member 54g is removed and the output polarizing plate 255g is not inclined. As is apparent from FIG. 4, the liquid crystal light valve 360g in which the second compensation member 54g is provided and the second compensation member 54g and the output polarizing plate 255g are appropriately tilted removes the second compensation member 54g and the output polarizing plate 255g. It can be said that the amount of leaked light is reduced as compared with the liquid crystal light valve 360 g that does not tilt the angle.

  The above is the description of the liquid crystal light valve 360g for green, but the same applies to the liquid crystal light valve 360r for red and the liquid crystal light valve 360b for blue, and the second compensation members 54r and 54b are connected to the polarization beam splitter 52r. , 52b and the output polarizing plates 255r and 255b, and the second compensating members 54r and 54b and the output polarizing plates 255r and 255b are rotated about the Z axis and inclined with respect to the XZ plane, Contrast is improved by reducing light leakage of the light beam tilted from the vertical direction.

  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.

  That is, in the above embodiment, the green light Gp is guided to the first optical path OP1, the red light Rp is guided to the second optical path OP2, and the blue light Bp is guided to the third optical path OP3. However, the combination of the optical path and the color can be changed. For example, the green light Gp can be guided to the first optical path OP1, the blue light Bp can be guided to the second optical path OP2, and the red light Rp 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 guide 40 is not limited to that illustrated in the embodiment, and various methods can be used.

  In the projectors 100, 200, and 300 according to the above-described embodiments, the polarization beam splitters 52g, 52r, and 52b of the liquid crystal light valves 60g, 60r, and 60b are configured by wire grid polarizers, but these beam splitters 52g, 52r, and 52b are included. It can also be composed of a photonic crystal or other structural birefringent optical element obtained by laminating three-dimensional dielectric layers.

  In the projectors 100, 200, and 300 according to the above-described embodiments, the illumination device 20 is configured by the light source device 10, the pair of lens arrays 15 and 16, the polarization conversion device 17, the superimposing lens 18, and the like. Can be omitted, and the light source device 10 can also be replaced with another light source such as an LED.

  In the above embodiment, only examples of the projectors 100, 200, and 300 using the three liquid crystal light valves 60g, 60r, and 60b have been described. However, the present invention may be a projector that uses two liquid crystal light valves or four projectors. The present invention can also be applied to a projector using the above liquid crystal light valve.

  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 15, 16 ... Lens array, 17 ... Polarization conversion device, 18 ... Superimposing lens, 20 ... Illumination device, 21 ... Cross dichroic mirror, 22 ... Dichroic mirror, 40 ... Color separation light guide part, 51b, 51g , 51r ... incident polarizing plate, 52g, 52r, 52b ... polarizing beam splitter, 53b, 53g, 53r ... exit side pattern layer, 54g, 54r, 54b ... second compensation member, 55g, 55r, 55b ... outgoing polarizing plate, 60 ... light modulation part, 60g, 60r, 60b ... liquid crystal light valve, 61g, 61r, 61b ... liquid crystal panel, 62b, 62g, 62r ... first compensation member, 70 ... light synthesis part, 71a, 71b ... dichroic mirror, 80 ... projection Optical system, 100, 200, 300 ... projector, AA ... absorption axis direction TA: Transmission axis direction, D1: Periodic direction, D2: Non-periodic direction, D3, D4: Axial projection direction, DS1, DS2: Reference direction, IL: Illumination luminous flux, LG, LB, LR: Color light, OP1, OP2, OP3 ... optical path, SA ... system optical axis

Claims (8)

A reflective liquid crystal element;
A structural birefringent flat polarizing beam splitter disposed on the light incident / exit side of the reflective liquid crystal element;
An exit polarizing plate disposed on the side from which the light reflected by the polarizing beam splitter exits;
A projector comprising: a retardation layer that is disposed between the polarizing beam splitter and a polarizing layer of the output polarizing plate and corrects a viewing angle characteristic of the polarizing beam splitter. A reference direction corresponding to at least one main refractive index of the retardation layer is inclined from an in-plane direction and a normal direction of the output polarizing plate,
2. The projector according to claim 1, wherein an axial projection direction in which the reference direction is projected onto a surface of the output polarizing plate and an absorption axis direction of the output polarizing plate are substantially parallel.   The projector according to claim 2, wherein the reference direction corresponds to a direction of a relatively large main refractive index among main refractive indexes of the retardation layer.   The projector according to claim 2, wherein the reference direction corresponds to a direction of a main refractive index that is relatively smallest among main refractive indexes of the retardation layer. The retardation layer is present on the light incident surface side of the output polarizing plate,
The projector according to any one of claims 1 to 4, wherein the polarizing layer is present on a light exit surface side of the exit polarizing plate.   The projector according to any one of claims 1 to 5, wherein the polarizing beam splitter exhibits birefringence when reflecting light from the reflective liquid crystal element.   The projector according to any one of claims 1 to 6, wherein the output polarizing plate is inclined with respect to a transmission axis direction of the output polarizing plate as a rotation axis. A reflective liquid crystal element;
A structural birefringent flat polarizing beam splitter disposed on the light incident / exit side of the reflective liquid crystal element;
An exit polarizing plate disposed on the light exit side of the polarizing beam splitter;
The projector, wherein the output polarizing plate is inclined with respect to the transmission axis direction of the output polarizing plate as a rotation axis.

Images