JP4082135B2 - projector - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a projector that projects and displays an image.
[0002]
[Prior art]
In the projector, image display is realized by modulating light emitted from the illumination optical system according to image information (image signal) using a liquid crystal light valve and projecting the modulated light on a screen.
[0003]
The liquid crystal light valve usually includes a liquid crystal panel and a polarizing plate provided on the light incident surface side or the light emission surface side thereof. The polarizing plate transmits only the light component in the polarization axis direction and blocks other light components. For this reason, linearly polarized light whose electric vector vibrates in the direction of the polarization axis is emitted from the polarizing plate.
[0004]
The polarizing plate usually generates heat when blocking light components other than the direction of the polarization axis. When the temperature of the polarizing plate rises due to this heat generation, the polarizing plate itself is distorted and deteriorated. Conventionally, in order to reduce this temperature rise, the polarizing plate has been attached on one single crystal sapphire substrate having a relatively high thermal conductivity.
[0005]
By the way, the single crystal sapphire substrate is a uniaxial crystal having one optical axis (referred to as c-axis). For this reason, when the single crystal sapphire substrate includes the c-axis substantially parallel to the surface, the polarization direction of the incident linearly polarized light (vibration direction of the electric vector) and the c-axis of the single crystal sapphire are parallel or perpendicular. It was necessary to set it correctly.
[0006]
[Problems to be solved by the invention]
However, it is difficult to attach the polarizing plate to the single crystal sapphire substrate so that the polarization direction of the linearly polarized light (that is, the polarization axis of the polarizing plate) and the c axis of the single crystal sapphire are parallel or perpendicular to each other. It was. Therefore, in practice, the polarization state of the light incident on the single crystal sapphire substrate changes due to birefringence in the single crystal sapphire substrate. At this time, the liquid crystal light valve transmits light that should not be transmitted or blocks light that should not be blocked, and as a result, the contrast of the projected and displayed image decreases.
[0007]
This problem is not limited to the case where the polarizing plate is attached to the single crystal sapphire substrate, but is common to the case where a translucent substrate composed of uniaxial crystals is used.
[0008]
The present invention has been made to solve the above-described problems in the prior art, and mitigates changes in the polarization state of light in a translucent substrate made of uniaxial crystals. As a result, it is projected and displayed by a projector. An object of the present invention is to provide a technique capable of suppressing a decrease in contrast of an image.
[0009]
[Means for solving the problems and their functions and effects]
In order to solve at least a part of the problems described above, the first device of the present invention is a projector,
Illumination optics,
An electro-optical device that modulates light from the illumination optical system according to image information;
A projection optical system that projects the modulated light obtained by the electro-optical device;
With
A pair of translucent substrates is provided in the optical path from the illumination optical system to the projection optical system,
Each of the pair of translucent substrates is composed of a uniaxial crystal including an optical axis substantially parallel to the surface thereof,
The optical axes of the pair of translucent substrates are substantially orthogonal to each other,
When the thickness of the pair of translucent substrates is assumed that light perpendicular to the pair of translucent substrates is incident on the pair of translucent substrates in a state where the pair of translucent substrates are in close contact with each other In addition, the polarization state of light incident on the pair of translucent substrates and the polarization state of light emitted from the pair of translucent substrates are set to be the same. To do.
[0010]
In this projector, since the pair of light-transmitting substrates are provided in the above relationship, the change in the polarization state of light on each light-transmitting substrate can be mitigated. As a result, an image projected and displayed by the projector It is possible to suppress a decrease in contrast.
[0011]
In the above apparatus,
The pair of translucent substrates may be included in the electro-optical device.
[0012]
In particular,
The electro-optical device has at least one of a light incident surface side and a light exit surface side,
A polarizing plate;
A base substrate provided with the polarizing plate;
With
The base substrate preferably includes the pair of translucent substrates provided in close contact with each other.
[0013]
Thus, if the translucent substrate is in contact with the polarizing plate, the temperature rise of the polarizing plate can be reduced.
[0014]
The electro-optical device includes:
LCD panel,
A polarizing plate provided on at least one of the light incident surface side and the light exit surface side of the liquid crystal panel;
With
One of the pair of translucent substrates forms a surface of the two surfaces of the liquid crystal panel facing the polarizing plate, and the other forms the surface of the two surfaces of the polarizing plate. It may be provided on the surface facing the liquid crystal panel.
[0015]
Here, the pair of translucent substrates may be provided in close contact with each other or may be provided in a separated state.
[0016]
If it does in this way, a pair of translucent board | substrate can reduce the temperature rise of both a liquid crystal panel and a polarizing plate.
[0017]
The electro-optical device includes a liquid crystal panel,
One of the pair of translucent substrates may form a light incident surface of the liquid crystal panel, and the other may form a light emission surface of the liquid crystal panel.
[0018]
Thus, if a pair of translucent board | substrates form the light-incidence surface and light-projection surface of a liquid crystal panel, the temperature rise of a liquid crystal panel can be reduced efficiently.
[0019]
In the above apparatus,
The pair of translucent substrates are preferably made of the same material.
[0020]
For example, the pair of translucent substrates may be made of single crystal sapphire or may be made of quartz.
[0021]
In this way, the projector can be manufactured relatively easily.
[0022]
Note that the pair of translucent substrates may be made of different materials.
[0023]
In the above apparatus, when the pair of translucent substrates are made of the same material, the pair of translucent substrates preferably have substantially the same thickness.
[0024]
In this way, the projector can be manufactured relatively easily.
[0025]
Note that the pair of translucent substrates may have different thicknesses.
[0026]
A second device of the present invention is a polarizing device,
A polarizing plate;
A base substrate provided with the polarizing plate;
With
The base substrate includes a pair of translucent substrates provided in close contact with each other,
Each of the pair of translucent substrates is composed of a uniaxial crystal including an optical axis substantially parallel to the surface thereof,
The optical axes of the pair of translucent substrates are substantially orthogonal to each other,
The thickness of the pair of translucent substrates is the light incident on the pair of translucent substrates, assuming that light perpendicular to the pair of translucent substrates is incident on the pair of translucent substrates. The polarization state is set so that the polarization state of the light emitted from the pair of light-transmitting substrates is the same.
[0027]
In this polarizing device, since the pair of translucent substrates are provided in the above relationship, the change in the polarization state of light in each translucent substrate can be reduced. Therefore, when this polarizing device is applied to a projector, it is possible to suppress a decrease in contrast of an image projected and displayed by the projector.
[0028]
A third device of the present invention is a liquid crystal panel,
A liquid crystal layer;
A pair of translucent substrates provided on both sides of the liquid crystal layer and forming a light incident surface and a light exit surface of the liquid crystal panel;
With
Each of the pair of translucent substrates is composed of a uniaxial crystal including an optical axis substantially parallel to the surface thereof,
The optical axes of the pair of translucent substrates are substantially orthogonal to each other,
When the thickness of the pair of translucent substrates is assumed that light perpendicular to the pair of translucent substrates is incident on the pair of translucent substrates in a state where the pair of translucent substrates are in close contact with each other In addition, the polarization state of light incident on the pair of translucent substrates and the polarization state of light emitted from the pair of translucent substrates are set to be the same. To do.
[0029]
In this liquid crystal panel, since the pair of translucent substrates are provided in the above relationship, the change in the polarization state of light in each translucent substrate can be reduced. Therefore, when this liquid crystal panel is applied to a projector, it is possible to suppress a decrease in contrast of an image projected and displayed by the projector.
[0030]
DETAILED DESCRIPTION OF THE INVENTION
A. First embodiment:
Next, embodiments of the present invention will be described based on examples. FIG. 1 is a schematic configuration diagram illustrating an example of a projector. The projector 1000 includes an illumination optical system 100, a color light separation optical system 200, a relay optical system 220, three liquid crystal light valves 300R, 300G, and 300B, a cross dichroic prism 360, and a projection optical system 380. .
[0031]
The illumination optical system 100 includes a polarization conversion element 160, which converts the light emitted from the light source device 120 into one type of linearly polarized light having a uniform polarization direction and emits it. The light emitted from the illumination optical system 100 is separated into three color lights of red (R), green (G), and blue (B) in the color light separation optical system 200. The separated color lights are modulated in accordance with image information in the liquid crystal light valves 300R, 300G, and 300B. Each modulated light modulated by each liquid crystal light valve is combined by a cross dichroic prism 360. The combined light is projected on the screen SC by the projection optical system 380. Thereby, a color image is displayed on the screen SC. 1 is described in detail in, for example, Japanese Patent Application Laid-Open No. 2002-14419 disclosed by the applicant of the present application, detailed description in this specification will not be given. Omitted.
[0032]
FIG. 2 is an explanatory diagram showing an enlarged view of the first liquid crystal light valve 300R of FIG. In the following description, the first liquid crystal light valve 300R into which the red light R is incident will be described. However, the second liquid crystal light valve 300G into which the green light G is incident and the third liquid crystal into which the blue light B is incident. The same applies to the light valve 300B.
[0033]
The liquid crystal light valve 300R includes a liquid crystal panel 310, a first polarizing device 320 provided on the light incident surface side of the liquid crystal panel, and a second polarizing device 330 provided on the light exit surface side of the liquid crystal panel. I have.
[0034]
The first polarizing device 320 includes a polarizing plate 321 and a base substrate 323 to which the polarizing plate 321 is attached. The base substrate 323 includes a pair of single crystal sapphire substrates 323a and 323b. The pair of single crystal sapphire substrates 323a and 323b are attached with an optical adhesive, for example, and are provided in close contact with each other.
[0035]
Similarly, the second polarizing device 330 includes a polarizing plate 331 and a base substrate 333 to which the polarizing plate 331 is attached. The base substrate 333 is a pair of single units provided in close contact with each other. Crystal sapphire substrates 333a and 333b are included.
[0036]
The color light R incident on the liquid crystal light valve 300R is linearly polarized light because it is emitted from the illumination optical system 100 (FIG. 1) including the polarization conversion element 160. The colored light R enters the first polarizing plate 321 after passing through the first base substrate 323. The polarizing plate has a function of transmitting only the light component in the polarization axis direction and blocking other light components in the incident light. For this reason, linearly polarized light whose electric vector vibrates in the direction of the polarization axis is emitted from the first polarizing plate 321. In this embodiment, the polarization axis of the first polarizing plate 321 is set to be substantially the same as the polarization direction of the incident linearly polarized light (color light R). Accordingly, most of the incident linearly polarized light passes through the first polarizing plate 321. In FIG. 2, the polarization axis of the first polarizing plate 321 is set in the z direction. The linearly polarized light emitted from the first polarizing plate 321 is modulated in the liquid crystal panel 310 according to given image information. The second polarizing plate 331 transmits only the light component in the polarization axis direction out of the light emitted from the liquid crystal panel 310. In FIG. 2, the polarization axis of the second polarizing plate 331 is set in the y direction and is substantially orthogonal to the polarization axis of the first polarizing plate 321. The linearly polarized light emitted from the second polarizing plate 331 passes through the second base substrate 333 and is emitted from the liquid crystal light valve 300R.
[0037]
As described above, in the past, the polarizing plate was attached on one single crystal sapphire substrate having a relatively high thermal conductivity. However, in this embodiment, the polarizing plates 321 and 331 are a pair of single crystals. It is affixed on base substrates 323 and 333 formed of a crystal sapphire substrate. By adopting this configuration, the temperature rise of the polarizing plate can be reduced. Further, the polarization state of the light incident on each base substrate and the polarization state of the light emitted from each base substrate can be made substantially the same.
[0038]
That is, single crystal sapphire is a uniaxial crystal having one optical axis called the c axis. For this reason, single crystal sapphire has different refractive indexes in the c-axis direction and the direction orthogonal to the c-axis, and induces birefringence. Specifically, when light is incident on the uniaxial crystal, the polarization state of the light usually changes. For example, when the single crystal sapphire substrate includes a c-axis substantially parallel to the surface, the linearly polarized light is elliptically polarized according to the angle between the polarization direction of the linearly polarized light and the c-axis of the single crystal sapphire. It changes to light. This is because the refractive index for ordinary light and the refractive index for extraordinary light are different, and a phase difference occurs between ordinary light and extraordinary light. If the polarization direction of the linearly polarized light and the c-axis of the single crystal sapphire are accurately set to be parallel or perpendicular, the linearly polarized light incident on the single crystal sapphire substrate remains as it is in the single crystal sapphire. Injected from the substrate.
[0039]
However, it is difficult to attach the polarizing plate to the single crystal sapphire substrate so that the polarization direction of the linearly polarized light (that is, the polarization axis of the polarizing plate) and the c axis of the single crystal sapphire are parallel or perpendicular. Therefore, in this embodiment, each base substrate is composed of a pair of single crystal sapphire substrates.
[0040]
FIG. 3 is an explanatory diagram showing a relationship between a pair of single crystal sapphire substrates 323a and 323b constituting the first base substrate 323 of FIG. 3A shows a perspective view when the pair of single crystal sapphire substrates 323a and 323b are arranged apart from each other, and FIG. 3B shows the pair of single crystal sapphire substrates 323a and 323b in FIG. The top view when it sees from ax direction is shown. Note that the same applies to the pair of single crystal sapphire substrates 333a and 333b included in the second base substrate 333 in FIG.
[0041]
As shown in the drawing, the pair of single crystal sapphire substrates 323a and 323b have a substantially square outer shape. Each of the pair of single crystal sapphire substrates 323a and 323b includes a c-axis substantially parallel to the surface thereof, and the c-axis of the pair of single crystal sapphire substrates 323a and 323b is substantially orthogonal to each other. 3A and 3B, the c-axis of each single crystal sapphire substrate is inclined by an angle θ from one of two orthogonal sides of the substrate. Further, the thicknesses D1 and D2 of the pair of single crystal sapphire substrates 323a and 323b are set substantially equal.
[0042]
As described above, when the c axes of the pair of single crystal sapphire substrates are substantially orthogonal and the thicknesses of the pair of single crystal sapphire substrates are substantially equal, the first single crystal sapphire substrate 323a is caused by birefringence. The first phase difference and the second phase difference caused by birefringence in the second single crystal sapphire substrate 323b are cancelled. As a result, the polarization state of light incident on the base substrate 323 and the polarization state of light emitted from the base substrate 323 can be made substantially the same. Therefore, it is not necessary to attach the polarizing plate to the single crystal sapphire substrate so that the polarizing axis of the polarizing plate and the c axis of the single crystal sapphire are parallel or perpendicular. For this reason, the difficult alignment at the time of sticking the polarizing plate 321 on the base substrate 323 can be omitted.
[0043]
By the way, the single crystal sapphire substrate can be manufactured using, for example, a well-known EFG method (Edge-defined Film-fed Growth Method). FIG. 4 is an explanatory view showing a crystal growth apparatus using the EFG method. This apparatus includes a crucible 710 for storing alumina melt MA, a heating coil 720 disposed so as to surround the crucible, and a crystal growth mold 730 including a slit 730s for determining the outer shape of the crystal to be grown. Yes.
[0044]
The crucible 710 is heated by the heating coil 720. The alumina melt MA in the crucible 710 fills the slit 730s and is guided to the upper end of the mold 730 by capillary action. Then, a single crystal sapphire seed crystal is placed in the alumina melt induced at the upper end of the mold 730, and the seed crystal is slowly pulled up, whereby a plate-like single crystal sapphire plate 740 is obtained.
[0045]
When this crystal growth apparatus is used, it is possible to produce a single crystal sapphire plate in which the surface of the plate and the c-axis are substantially parallel by adjusting the positional relationship between the seed crystal and the mold 730 with high accuracy. Is possible. It is also possible to produce a single crystal sapphire plate in which one side of the plate and the c-axis are substantially orthogonal. However, in practice, the c-axis is often inclined with respect to one side of the plate. Therefore, in this embodiment, a method for manufacturing the base substrate 323 is devised.
[0046]
FIG. 5 is an explanatory diagram showing a procedure for manufacturing the base substrate 323 using the single crystal sapphire plate 740 of FIG. FIG. 5A shows the single crystal sapphire plate 740 obtained in FIG. Note that since the single crystal sapphire plate 740 is a single plate, the c-axes in each portion are parallel to each other. In FIG. 5A, a plurality of substantially square single crystal sapphire substrates are cut out. FIG. 5B shows two single crystal sapphire substrates 323a and 323b obtained in FIG. Note that adjacent portions of the single crystal sapphire plate 740 in FIG. 5A are selected as the two single crystal sapphire substrates 323a and 323b. FIG. 5C illustrates a base substrate 323 obtained by bonding the two single crystal sapphire substrates 323a and 323b in FIG. 5B. At this time, the c-axes of the two single crystal sapphire substrates 323a and 323b are combined so as to be substantially orthogonal. This is realized, for example, by rotating the second single crystal sapphire substrate 323b 90 ° counterclockwise so that two right-angled portions of black circles shown in FIG. 5B overlap.
[0047]
When the base substrate 323 is manufactured in the above procedure, the c-axis of the pair of single crystal sapphire substrates 323a and 323b can be made to be orthogonal with relatively high accuracy using the processing accuracy with respect to the single crystal sapphire plate 740. . In this embodiment, since the processing accuracy with respect to the single crystal sapphire plate 740 is relatively high, for example, the base substrate 323 can be manufactured such that the deviation angle between the two c-axes is within ± 0.2 °. The deviation angle between the two c-axes is preferably within ± about 1 °, and preferably within ± about 0.5 °.
[0048]
In addition, when the base substrate 323 is manufactured by the procedure as described above, in other words, when a relatively large single crystal sapphire plate 740 is used, the thickness of the pair of single crystal sapphire substrates 323a and 323b is easily set to be approximately equal. can do. The difference between the thicknesses of the two single crystal sapphire substrates is preferably within about ± 0.05 mm of the thickness of one single crystal sapphire substrate, more preferably within about ± 0.02 mm, and about ± about More preferably, it is within 0.01 mm.
[0049]
In this embodiment, the pair of single crystal sapphire substrates have a substantially square outer shape, but have other outer shapes such as a substantially rectangular shape as long as the optical axes are substantially orthogonal to each other. May be.
[0050]
As described above, in this embodiment, the polarizing device includes the polarizing plate and the base substrate provided with the polarizing plate. The base substrate includes a pair of single crystal sapphire substrates provided in close contact with each other. Each of the pair of single crystal sapphire substrates includes a c-axis substantially parallel to the surface thereof. The c axes of the pair of single crystal sapphire substrates are substantially orthogonal to each other, and the thicknesses of the pair of single crystal sapphire substrates are set to be approximately equal.
[0051]
Thus, if the single crystal sapphire substrate is in contact with the polarizing plate, the temperature rise of the polarizing plate can be reduced. In addition, since the base substrate includes a pair of single crystal sapphire substrates in close contact with each other, the polarization state of light incident on the base substrate and the polarization state of light emitted from the base substrate are substantially the same. be able to. That is, by using two single crystal sapphire substrates in combination, the change in the polarization state of light due to birefringence in each single crystal sapphire substrate can be reduced, and as a result, an image projected and displayed by the projector It is possible to suppress a decrease in contrast.
[0052]
In the present embodiment, the pair of single crystal sapphire substrates are attached to each other with an optical adhesive, but instead, they may be held in a state of being in direct contact with each other by a holder (not shown). Thus, the pair of single crystal sapphire substrates are preferably provided in close contact with each other. By doing so, there is an advantage that the reflection of light on the surface of each single crystal sapphire substrate can be reduced.
[0053]
In the present embodiment, the liquid crystal light valve 300R includes polarizing plates 321 and 331 on both the light incident surface side and the light emitting surface side. However, when the projector 1000 includes the illumination optical system 100 that emits linearly polarized light as in the present embodiment, the polarizing plate 321 on the light incident surface side can be omitted. However, when the projector includes an illumination optical system that emits light with no bias, the liquid crystal light valve desirably includes polarizing plates on both the light incident surface side and the light emission surface side.
[0054]
Further, in this embodiment, the liquid crystal light valve 300R includes a first base substrate 323 having a first polarizing plate 321 attached to the light incident surface side. However, when the projector 1000 includes the illumination optical system 100 that emits linearly polarized light as in the present embodiment, the first polarizing plate 321 transmits most of the incident linearly polarized light, and therefore the temperature thereof is low. The rise is relatively low. Therefore, the first polarizing plate may be attached to a normal glass substrate instead of the base substrate formed of a pair of single crystal sapphire substrates.
[0055]
In general, a liquid crystal light valve includes a polarizing plate and a base substrate provided with a polarizing plate on at least one of a light incident surface side and a light emission surface side, and the base substrates are in close contact with each other. It is only necessary to include a pair of single crystal sapphire substrates provided in (1).
[0056]
A-1. Modification of the first embodiment:
FIG. 6 is an explanatory view showing a first liquid crystal light valve 300RA as a modification of the first embodiment. The liquid crystal light valve 300RA is substantially the same as the liquid crystal light valve 300R of FIG. 2, but the first polarizing device 320A and the second polarizing device 330A are changed.
[0057]
Specifically, in FIG. 2, the first polarizing device 320 includes a polarizing plate 321 on its light exit surface side, and the second polarizing device 330 includes a polarizing plate 331 on its light incident surface side. ing. On the other hand, in FIG. 6, the first polarizing device 320A includes a polarizing plate 321 on its light incident surface side, and the second polarizing device 330A includes a polarizing plate 331 on its light exit surface side.
[0058]
When the configuration of FIG. 6 is adopted, the change in the polarization state of the light in each single crystal sapphire substrate can be reduced as in the case of adopting the configuration of FIG. It is possible to suppress a decrease in contrast of an image. However, when the configuration of FIG. 2 is adopted, there is an advantage that a reduction in contrast of the image can be further suppressed. This is because the c-axis of the pair of single crystal sapphire substrates is actually slightly deviated from the state orthogonal to each other.
[0059]
That is, in FIG. 6, light passes through the first polarizing plate 321 and the first base substrate 323 in this order. For this reason, when the linearly polarized light emitted from the first polarizing plate 321 passes through the first base substrate 323, the polarization direction of the light slightly changes, and as a result, from the first polarizing device 320A. Light other than linearly polarized light is also emitted. In FIG. 6, light passes through the second base substrate 333 and the second polarizing plate 331 in this order. For this reason, when the modulated light emitted from the liquid crystal panel 310 passes through the second base substrate 333, the polarization state of the light slightly changes. As a result, the second polarizing plate 331 is not intended. Light having a polarization state also enters. Therefore, when the arrangement of FIG. 6 is employed, the liquid crystal light valve 300RA transmits light that should not be transmitted or blocks light that should not be blocked. At this time, the contrast of the projected image is slightly reduced.
[0060]
Conversely, in FIG. 2, light passes through the first base substrate 323 and the first polarizing plate 321 in this order. For this reason, only linearly polarized light is emitted from the first polarizing device 320. In FIG. 2, light passes through the second polarizing plate 331 and the second base substrate 333 in this order. For this reason, only light having an intended polarization state is incident on the second polarizing plate 331. Therefore, when the configuration of FIG. 2 is adopted, even if the polarization state of light changes in the base substrates 323 and 333, the liquid crystal light valve 300R transmits light to be transmitted and blocks light to be blocked. be able to. As a result, it is possible to further suppress a decrease in contrast of the projected and displayed image.
[0061]
B. Second embodiment:
FIG. 7 is an explanatory diagram showing the first liquid crystal light valve 300RB in the second embodiment. FIG. 7 is substantially the same as FIG. 2, but the liquid crystal panel 310B is changed.
[0062]
Specifically, the liquid crystal panel 310B includes a liquid crystal panel body 301, a first cover substrate 311 that forms a light incident surface of the liquid crystal panel 310B, and a second cover substrate 312 that forms a light emission surface of the liquid crystal panel 310B. And. The two cover substrates 311 and 312 have a function of reducing the temperature rise of the liquid crystal panel body 301 and a function of preventing dust adhering to the liquid crystal panel 310B from appearing in the projected image. Have.
[0063]
FIG. 8 is a schematic cross-sectional view of the liquid crystal panel 310B of FIG. As shown in the figure, the liquid crystal panel main body 301 includes two glass substrates 302 and 303, a liquid crystal layer 304 sandwiched between the two glass substrates, and a seal member 304s for preventing liquid crystal from leaking out. ing. A transparent common electrode 302a is formed on the surface of the first glass substrate 302 on the liquid crystal layer 304 side. Thin film transistors (not shown) and transparent pixel electrodes 303a are formed in a matrix for each pixel on the surface of the second glass substrate 303 on the liquid crystal layer 304 side. As described with reference to FIG. 7, the first cover substrate 311 and the second cover substrate 312 are attached to the liquid crystal panel main body 301.
[0064]
The first cover substrate 311 includes a pair of single crystal sapphire substrates 311a and 311b provided in close contact with each other. Note that the pair of single crystal sapphire substrates 311a and 311b are arranged in a relationship illustrated in FIG. Specifically, each of the pair of single crystal sapphire substrates 311a and 311b includes a c axis substantially parallel to the surface thereof, and the c axes of the pair of single crystal sapphire substrates 311a and 311b are substantially orthogonal to each other. Yes. Further, the thicknesses of the pair of single crystal sapphire substrates 311a and 311b are set substantially equal. The same applies to the pair of single crystal sapphire substrates 312a and 312b constituting the second cover substrate 312.
[0065]
Thus, if the single crystal sapphire substrate is in contact with the liquid crystal panel, the temperature rise of the liquid crystal panel can be efficiently reduced. In addition, since the cover substrate includes a pair of single crystal sapphire substrates in close contact with each other, the polarization state of light incident on the cover substrate is substantially the same as the polarization state of light emitted from the cover substrate. be able to. That is, the change in the polarization state of light in each single crystal sapphire substrate can be mitigated, and as a result, it is possible to suppress a decrease in contrast of an image projected and displayed by the projector.
[0066]
In the present embodiment, the liquid crystal panel 310B includes two glass substrates 302 and 303 that sandwich the liquid crystal layer 304, but the two glass substrates can be omitted. In this case, electrodes may be formed on the surface of the first cover substrate 311 on the liquid crystal layer 304 side and the surface of the second cover substrate 312 on the liquid crystal layer 304 side.
[0067]
In the present embodiment, the liquid crystal light valve 300RB includes two cover substrates 311 and 312 that form the light incident surface and the light emission surface of the liquid crystal panel, but only one of them is provided. Also good.
[0068]
C. Third embodiment:
FIG. 9 is an explanatory diagram showing the first liquid crystal light valve 300RC in the third embodiment. 9 is substantially the same as FIG. 7, but the arrangement of the two polarizing plates 321 and 331 is changed.
[0069]
Specifically, the first polarizing plate 321 is attached to the first cover substrate 311 that forms the light incident surface of the liquid crystal panel 310B, and the second polarizing plate 331 is the light of the liquid crystal panel 310B. It is affixed on the 2nd cover board | substrate 312 which forms an injection | emission surface.
[0070]
When the configuration of this embodiment is adopted, the two base substrates 323 and 333 for providing the two polarizing plates 321 and 331 can be omitted as compared with the case where the configuration of FIG. 7 is adopted. There are advantages. However, when the configuration of FIG. 7 is adopted, there is an advantage that the temperature rise of both the liquid crystal panel 310B and the two polarizing plates 321 and 331 can be efficiently reduced.
[0071]
D. Fourth embodiment:
FIG. 10 is an explanatory diagram showing the first liquid crystal light valve 300RD in the fourth embodiment. FIG. 10 is substantially the same as FIG. 6, but the arrangement of the pair of single crystal sapphire substrates on the light incident surface side of the liquid crystal light valve 300RD and the arrangement of the pair of single crystal sapphire substrates on the light emission surface side are changed. Has been.
[0072]
Specifically, in FIG. 6, the first polarizing device 320A includes a base substrate 323 composed of a pair of single crystal sapphire substrates 323a and 323b. On the other hand, in FIG. 10, the first polarizing device 320 </ b> D includes a base substrate composed of one single crystal sapphire substrate 341 a. In addition, the liquid crystal panel 310D includes a cover substrate formed of one single crystal sapphire substrate 341b.
[0073]
Note that the pair of single crystal sapphire substrates 341a and 341b are arranged in a relationship illustrated in FIG. Specifically, each of the pair of single crystal sapphire substrates 341a and 341b includes a c axis substantially parallel to the surface thereof, and the c axes of the pair of single crystal sapphire substrates 341a and 341b are substantially orthogonal to each other. Yes. Further, the thicknesses of the pair of single crystal sapphire substrates 341a and 341b are set substantially equal.
[0074]
Similarly, in FIG. 10, the second polarizing device 330 </ b> D includes a base substrate formed of one single crystal sapphire substrate 342 a. In addition, the liquid crystal panel 310D includes a cover substrate composed of one single crystal sapphire substrate 342b. Then, the pair of single crystal sapphire substrates 342a and 342b are arranged in a relationship shown in FIG.
[0075]
As can be seen from the above description, the configuration of the present embodiment corresponds to a configuration in which a pair of single crystal sapphire substrates in close contact with each other included in each of the polarization devices 320A and 330A of FIG. As described above, even when the pair of single crystal sapphire substrates are provided at separate positions, the polarization state of light incident on the pair of single crystal sapphire substrates and the polarization state of light emitted from the pair of single crystal sapphire substrates. Can be made substantially the same. That is, the change in the polarization state of the light in each single crystal sapphire substrate can be mitigated, and as a result, a decrease in contrast of an image projected and displayed by the projector can be suppressed.
[0076]
When the configuration of the present embodiment is adopted, the number of single crystal sapphire substrates is not increased as compared with the case where the configuration of FIG. 6 is adopted, and the liquid crystal panel 310D and the two polarizing plates 321 and 331 are arranged. There is an advantage that both temperature rises can be efficiently reduced.
[0077]
In this embodiment, the liquid crystal light valve 300RD includes a pair of single crystal sapphire substrates on each of the light incident surface side and the light emission surface side, but the pair of single crystal sapphire substrates is provided only on one of them. You may make it provide.
[0078]
In general, the liquid crystal light valve may include a liquid crystal panel and a polarizing plate provided on at least one of the light incident surface side and the light emission surface side of the liquid crystal panel so as to face the liquid crystal panel. . One of the pair of single crystal sapphire substrates forms a surface facing the polarizing plate of the two surfaces of the liquid crystal panel, and the other is formed on the liquid crystal panel of the two surfaces of the polarizing plate. What is necessary is just to be provided in the surface which opposes.
[0079]
E. Example 5:
FIG. 11 is an explanatory view showing a first liquid crystal light valve 300RE in the fifth embodiment. FIG. 11 is substantially the same as FIG. 7, but the liquid crystal panel 310E is changed.
[0080]
Specifically, in FIG. 7, the first cover substrate 311 forming the light incident surface of the liquid crystal panel 310B is composed of a pair of single crystal sapphire substrates 311a and 311b, and the second cover substrate forming the light emitting surface is formed. The cover substrate 312 includes a pair of single crystal sapphire substrates 312a and 312b. On the other hand, in FIG. 11, the first cover substrate that forms the light incident surface of the liquid crystal panel 310E is configured by one single crystal sapphire substrate 314a, and the second cover substrate that forms the light emission surface is 1 It is composed of two single crystal sapphire substrates 314b.
[0081]
Note that the pair of single crystal sapphire substrates 314a and 314b are arranged in a relationship illustrated in FIG. Specifically, each of the pair of single crystal sapphire substrates 314a and 314b includes a c-axis substantially parallel to the surface thereof, and the c-axis of the pair of single crystal sapphire substrates 314a and 314b is substantially orthogonal to each other. Yes. Further, the thicknesses of the pair of single crystal sapphire substrates 314a and 314b are set substantially equal.
[0082]
By the way, in this embodiment, a liquid crystal panel main body 301 is provided between the pair of single crystal sapphire substrates 314a and 314b. For this reason, when the liquid crystal panel main body 301 performs modulation with an intermediate gradation value, the polarization state of light changes due to the inclination of the liquid crystal molecules inside the liquid crystal panel main body 301. However, when the liquid crystal panel main body 301 performs modulation with the maximum gradation value and the minimum gradation value, the polarization state of the light is maintained. Therefore, the liquid crystal panel body 301 does not affect the contrast of the image related to the modulation with the maximum gradation value and the minimum gradation value. That is, as in this embodiment, even when a pair of single crystal sapphire substrates 314a and 314b sandwich the liquid crystal panel body 301, the change in the polarization state of light in each single crystal sapphire substrate can be reduced. As a result, it is possible to suppress a decrease in contrast of an image projected and displayed by the projector.
[0083]
Note that when the liquid crystal panel body 301 performs modulation with an intermediate gradation value, the polarization state of the light changes, so that the color of the projected image is not accurately reproduced. However, if the image information is subjected to gamma correction, the color of the image can be corrected.
[0084]
When the configuration of this embodiment is employed, the temperature rise of the liquid crystal panel can be efficiently reduced as in the case of employing the configuration of FIG. Further, when the configuration of this embodiment is adopted, there is an advantage that the number of single crystal sapphire substrates can be reduced as compared with the case where the configuration of FIG. 7 is adopted.
[0085]
In this embodiment, as shown in FIG. 8, the liquid crystal panel 310E includes two glass substrates 302 and 303 that sandwich the liquid crystal layer 304. However, the two glass substrates can be omitted. In this case, electrodes may be formed on the surface of the first single crystal sapphire substrate 314a on the liquid crystal layer 304 side and on the surface of the second single crystal sapphire substrate 314b on the liquid crystal layer 304 side.
[0086]
In general, a liquid crystal panel may include a liquid crystal layer and a pair of single crystal sapphire substrates that are provided on both sides of the liquid crystal layer and form a light incident surface and a light emission surface of the liquid crystal panel. Also in this case, when it is assumed that light perpendicular to the pair of substrates is incident on the pair of substrates while the pair of single crystal sapphire substrates is in close contact, the polarization state of the light incident on the pair of substrates And the polarization state of the light emitted from the pair of substrates can be made substantially the same.
[0087]
F. Example 6:
FIG. 12 is an explanatory diagram showing the first liquid crystal light valve 300RF in the sixth embodiment. FIG. 12 is substantially the same as FIG. 11, but the arrangement of the two polarizing plates 321 and 331 is changed.
[0088]
Specifically, the first polarizing plate 321 is provided on the first single crystal sapphire substrate 314a that forms the light incident surface of the liquid crystal panel 310E, and the second polarizing plate 331 is provided on the liquid crystal panel 310E. It is provided on a single crystal sapphire substrate 314b that forms a light emission surface.
[0089]
When the configuration of this embodiment is adopted, the two base substrates 323 and 333 for providing the two polarizing plates 321 and 331 can be omitted as compared with the case where the configuration of FIG. 11 is adopted. There are advantages. However, when the configuration of FIG. 11 is adopted, there is an advantage that the temperature rise between the liquid crystal panel 310E and the two polarizing plates 321 and 331 can be further reduced.
[0090]
The present invention is not limited to the above-described examples and embodiments, and can be implemented in various modes without departing from the gist thereof. For example, the following modifications are possible.
[0091]
(1) In the above embodiment, the pair of single crystal sapphire substrates is included in the liquid crystal light valve, but instead, it may be provided in another part. For example, a λ / 2 retardation plate included in the polarization conversion element 160 may be provided on a pair of single crystal sapphire substrates.
[0092]
In the above embodiment, a pair of single crystal sapphire substrates are used, but a pair of quartz substrates may be used instead. Here, quartz is SiO ₂ Means a single crystal. In this case, the quartz substrate only needs to include one optical axis called the Z axis substantially parallel to the surface thereof. Further, instead of a pair of single crystal sapphire substrates, a single crystal sapphire substrate and a quartz substrate may be used in combination.
[0093]
Furthermore, in the said Example, although the thickness of a pair of single crystal sapphire board | substrate is set substantially equal, it may replace with this and may be set to mutually different thickness. That is, the thickness of the pair of single crystal sapphire substrates is determined by canceling the first phase difference due to the birefringence of the first single crystal sapphire substrate and the second phase difference due to the birefringence of the second single crystal sapphire substrate. As long as it is set. Specifically, the sum of the two phase differences may be set to be approximately equal to 2πn (n is an integer (..., -2, -1, 0, 1, 2,...)). However, as in the above embodiment, the sum of the two phase differences is preferably set to approximately 0 (that is, n = 0). In this case, the wavelength dependence of the light of single crystal sapphire can be canceled. Specifically, the difference in refractive index between the c-axis direction of each single crystal sapphire and the direction orthogonal to the c-axis varies depending on the wavelength of light, but the sum of the phase differences of a pair of single crystal sapphire is almost 0 ( That is, by setting n = 0), the wavelength dependence of the refractive index can be canceled. When a combination of a single crystal sapphire substrate and a quartz substrate is used, the thickness of the pair of substrates is usually set to a different thickness.
[0094]
In general, a pair of translucent substrates may be provided in the optical path from the illumination optical system to the projection optical system. Each of the pair of translucent substrates is composed of a uniaxial crystal including an optical axis substantially parallel to the surface thereof, and the optical axes of the pair of translucent substrates are substantially orthogonal to each other, The thickness of the light-transmitting substrate is determined based on the assumption that light perpendicular to the pair of light-transmitting substrates is incident on the pair of light-transmitting substrates with the pair of light-transmitting substrates in close contact with each other. The polarization state of the light incident on the transparent substrate and the polarization state of the light emitted from the pair of translucent substrates may be set to be the same.
[0095]
When the pair of translucent substrates are made of the same material, the liquid crystal light valve can be manufactured relatively easily as compared with the case of being made of a different material. As a result, the projector There is an advantage that can be manufactured relatively easily.
[0096]
In addition, when the pair of translucent substrates have substantially the same thickness, the liquid crystal light valve can be manufactured relatively easily as compared with the case of having different thicknesses. There is an advantage that it can be easily manufactured.
[0097]
(2) In the above embodiments, the case where the present invention is applied to a transmissive liquid crystal panel has been described. However, the present invention is also applicable to a reflective liquid crystal panel. When the present invention is applied to a reflective liquid crystal panel, the pair of translucent substrates are provided on the light incident surface side and the light emission surface side of the beam splitter provided on one surface side of the liquid crystal panel. What is necessary is just to arrange each.
[0098]
The liquid crystal light valve of the above embodiment corresponds to the electro-optical device in the present invention. The electro-optical device may include only the liquid crystal panel, and may further include a polarizing plate provided on at least one of the light incident surface side and the light emission surface side of the liquid crystal panel.
[0099]
(3) In the above-described embodiments, the case where the present invention is applied to the projector 1000 that projects and displays a color image has been described. However, the present invention is also applicable to a projector that projects and displays a monochrome image.
[0100]
Generally, a projector includes an illumination optical system, an electro-optical device that modulates light from the illumination optical system according to image information, and a projection optical system that projects modulated light obtained by the electro-optical device. That's fine.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram illustrating an example of a projector.
FIG. 2 is an explanatory diagram showing an enlarged view of a first liquid crystal light valve 300R in FIG.
3 is an explanatory diagram showing a relationship between a pair of single crystal sapphire substrates 323a and 323b constituting the first base substrate 323 of FIG.
FIG. 4 is an explanatory view showing a crystal growth apparatus using an EFG method.
5 is an explanatory diagram showing a procedure for manufacturing a base substrate 323 using the single crystal sapphire plate 740 of FIG. 4; FIG.
FIG. 6 is an explanatory view showing a first liquid crystal light valve 300RA as a modification of the first embodiment.
FIG. 7 is an explanatory diagram showing a first liquid crystal light valve 300RB in the second embodiment.
8 is a schematic cross-sectional view of the liquid crystal panel 310B of FIG.
FIG. 9 is an explanatory diagram showing a first liquid crystal light valve 300RC in a third embodiment.
FIG. 10 is an explanatory diagram showing a first liquid crystal light valve 300RD in a fourth embodiment.
FIG. 11 is an explanatory diagram showing a first liquid crystal light valve 300RE in a fifth embodiment.
FIG. 12 is an explanatory diagram showing a first liquid crystal light valve 300RF in a sixth embodiment.
[Explanation of symbols]
1000 ... Projector
100: Illumination optical system
120: Light source device
160: Polarization conversion element
200: Color light separation optical system
220: Relay optical system
300R, 300RA to RF, 300G, 300B ... Liquid crystal light valve
301 ... LCD panel body
302, 303 ... Glass substrate
302a ... Common electrode
303a ... Pixel electrode
304 ... Liquid crystal layer
304s ... Sealing member
310, 310B, D, E ... Liquid crystal panel
311, 312 ... Cover substrate
311a, 311b ... single crystal sapphire substrate
312a, 312b ... single crystal sapphire substrate
314a, 314b ... single crystal sapphire substrate
320, 320A, D ... first polarizing device
330, 330A, D ... second polarizing device
321,331 ... Polarizing plate
323, 333 ... Base substrate
323a, 323b ... single crystal sapphire substrate
333a, 333b ... single crystal sapphire substrate
341a, 341b ... single crystal sapphire substrate
342a, 342b ... single crystal sapphire substrate
360 ... Cross dichroic prism
380 ... Projection optical system
710 ... Crucible
720 ... Heating coil
730 ... Mold
740 ... single crystal sapphire plate

Claims (10)

A projector,
Illumination optics,
An electro-optical device that modulates light from the illumination optical system according to image information;
A projection optical system that projects the modulated light obtained by the electro-optical device;
With
A pair of translucent substrates is provided in the optical path from the illumination optical system to the projection optical system,
Each of the pair of translucent substrates is composed of a uniaxial crystal including an optical axis substantially parallel to the surface thereof,
The optical axes of the pair of translucent substrates are substantially orthogonal to each other,
The thickness of the pair of translucent substrates is such that the pair of translucent substrates are brought into close contact regardless of whether the pair of translucent substrates are provided in close contact with each other or apart from each other. When it is assumed that light perpendicular to the pair of translucent substrates is incident on the pair of translucent substrates, the polarization state of the light incident on the pair of translucent substrates and the pair of translucent substrates A projector characterized in that it is set to be approximately equal so that the polarization state of light emitted from a light substrate is the same. The projector according to claim 1, wherein
The pair of translucent substrates is a projector included in the electro-optical device. The projector according to claim 2, wherein
The electro-optical device has at least one of a light incident surface side and a light exit surface side,
A polarizing plate;
A base substrate provided with the polarizing plate;
With
The base substrate includes the pair of translucent substrates provided in close contact with each other. The projector according to claim 2, wherein
The electro-optical device includes:
LCD panel,
A polarizing plate provided on at least one of the light incident surface side and the light exit surface side of the liquid crystal panel;
With
One of the pair of translucent substrates forms a surface of the two surfaces of the liquid crystal panel facing the polarizing plate, and the other forms the surface of the two surfaces of the polarizing plate. A projector provided on a surface facing a liquid crystal panel. The projector according to claim 2, wherein
The electro-optical device includes a liquid crystal panel,
One of the pair of translucent substrates is a projector that forms a light incident surface of the liquid crystal panel, and the other is a light emitting surface of the liquid crystal panel. The projector according to claim 1, wherein
The pair of translucent substrates is a projector made of the same material. The projector according to claim 6, wherein
The pair of translucent substrates is a projector made of single crystal sapphire. The projector according to claim 6, wherein
The pair of translucent substrates is a projector made of quartz. A polarizing device,
A polarizing plate;
A base substrate provided with the polarizing plate;
With
The base substrate includes a pair of translucent substrates provided in close contact with each other,
Each of the pair of translucent substrates is composed of a uniaxial crystal including an optical axis substantially parallel to the surface thereof,
The optical axes of the pair of translucent substrates are substantially orthogonal to each other,
The thickness of the pair of translucent substrates is the light incident on the pair of translucent substrates, assuming that light perpendicular to the pair of translucent substrates is incident on the pair of translucent substrates. And a polarization state of light emitted from the pair of translucent substrates is set to be approximately equal to each other. A liquid crystal panel,
A liquid crystal layer;
A pair of translucent substrates provided on both sides of the liquid crystal layer and forming a light incident surface and a light exit surface of the liquid crystal panel;
With
Each of the pair of translucent substrates is composed of a uniaxial crystal including an optical axis substantially parallel to the surface thereof,
The optical axes of the pair of translucent substrates are substantially orthogonal to each other,
The thickness of the pair of translucent substrates is such that the pair of translucent substrates are brought into close contact regardless of whether the pair of translucent substrates are provided in close contact with each other or apart from each other. When it is assumed that light perpendicular to the pair of translucent substrates is incident on the pair of translucent substrates, the polarization state of the light incident on the pair of translucent substrates and the pair of translucent substrates A liquid crystal panel, characterized in that the liquid crystal panel is set to be substantially equal so that the polarization state of light emitted from the optical substrate is the same.

Images