JP5891742B2 - Optical unit and projector - Google Patents

Description

The present invention relates to an optical unit and a projector.

  Conventionally, an exit-side polarizing plate (polarizing plate unit) used in the rear stage of a projector liquid crystal panel generates heat by light from a light source (emitted light from a liquid crystal panel). The polarizing plate unit includes a polarizing plate and a glass substrate that holds the polarizing plate. Then, when the polarizing plate unit generates heat, unevenness in illumination (decrease in contrast) occurs on the projection screen.

  FIG. 4 is a diagram schematically showing an image when a black display image is incident on the conventional polarizing plate unit 6 and emitted. FIG. 4 also substantially corresponds to a diagram schematically showing the in-plane temperature distribution of the polarizing plate unit 6. Therefore, in FIG. 4, the reference numerals are added corresponding to the glass substrate 61 of the polarizing plate unit 6. The polarizing plate unit 6 includes an exit side polarizing plate (not shown) and a glass substrate 61 on which the exit side polarizing plate is installed. In the polarizing plate, the direction of the polarization axis 62 is set to 0 degree with respect to the vertical direction.

As shown in FIG. 4, black is displayed in the center D1 and the upper and lower left and right (0 degrees (vertical direction) or 90 degrees (horizontal direction)) of the central portion D1 of the glass substrate 61. In the partial region D3, a blank state is obtained. When an image is projected using such a polarizing plate unit 6 for a projector, unevenness in illumination (contrast reduction) occurs at four corners in the projected image.
In addition, in patent document 1, in order to improve such a state, using a glass substrate with a low absolute value of a linear expansion coefficient for a glass substrate is disclosed.

JP 2008-9454 A

As a cause of uneven illuminance at the four corners, the polarization axis direction of the polarizing plate is usually set to 0 degree or 90 degrees with respect to the vertical direction in accordance with the liquid crystal panel. The influence of the stress component in the direction of ± 45 degrees with respect to the polarization axis direction is raised. Specifically, at the in-plane temperature of the rectangular glass substrate on which such a polarizing plate is installed, the central part is usually the hottest, and the four corners farthest from the central part are the coldest. Due to such an in-plane temperature difference, the stress (stress difference) at the four corner portions becomes the largest with respect to the central portion. Since the four corner portions are also in the direction of ± 45 degrees with respect to the direction of the polarization axis, which has a great influence on the illuminance unevenness, the illuminance unevenness occurs due to the stress generated by the temperature difference. As described above, there is a problem that a location where the stress difference due to the temperature difference becomes large and a location where the stress difference affects the illuminance unevenness are close.
Moreover, in patent document 1, even if it uses the glass substrate with a low absolute value of a linear expansion coefficient, there exists a subject that illuminance nonuniformity generate | occur | produces although there is a difference in a grade. Moreover, since the material of the glass substrate is a material having a low linear expansion coefficient, the amount of heat generated increases when the brightness of the light source is improved. Accordingly, there is a problem that the projector is not necessarily suitable for increasing the brightness and downsizing of the projector.
Therefore, there has been a demand for a polarizing plate unit, an optical unit, and a projector that suppress in-plane illuminance unevenness in the glass substrate on which the polarizing plate is installed.

  SUMMARY An advantage of some aspects of the invention is to solve at least a part of the problems described above, and the invention can be implemented as the following forms or application examples.

  Application Example 1 A polarizing plate unit according to this application example is a polarizing plate unit including a glass substrate and a polarizing plate installed on the glass substrate, and the glass substrate has a substantially square outer shape, Is characterized in that it is installed with its polarization axis aligned with the diagonal direction of the glass substrate.

According to such a polarizing plate unit, the glass substrate has a substantially square outer shape, and the polarizing plate is installed with the polarization axis aligned in the diagonal direction of the glass substrate. Unevenness can be suppressed. The location where the stress on the glass substrate due to the temperature difference is large is the location where the temperature difference from the center of the glass substrate is the largest in the glass substrate, and is the four corners of the glass substrate. Further, the place where the stress difference affects the illuminance unevenness is the place where the direction is ± 45 degrees with respect to the polarization axis direction. By aligning the polarization axis with the largest temperature difference in the glass substrate, that is, the diagonal direction of the substantially square glass substrate, the direction of ± 45 degrees relative to the polarization axis direction causing uneven illuminance is the glass substrate. The direction of the center part of the outer periphery of the top, bottom, left and right. In the outer periphery of the glass substrate, the central portion of the upper, lower, left, and right outer periphery is the portion where the distance from the central portion of the glass substrate is the shortest, so the in-plane temperature difference from the central portion is small compared to the four corner portions. Thus, the stress difference can be reduced. Therefore, it is possible to realize a polarizing plate unit that suppresses illuminance unevenness as compared with the prior art.
In addition, by making the glass substrate substantially square, the distance from the center of the glass substrate is the same for each of the central portions of the upper, lower, left, and right outer periphery of the glass substrate, so that the temperature difference in the outer periphery is reduced. Therefore, the stress difference of the whole glass substrate can be reduced and illuminance unevenness can be suppressed. Moreover, since the area of a glass substrate becomes large by setting it as a square, the cooling efficiency of a polarizing plate can be improved.

  Application Example 2 An optical unit according to this application example is an optical unit including a liquid crystal panel that modulates an incident light beam according to image information, and the polarizing plate unit described above, and the polarizing plate unit is a liquid crystal. A phase difference that is arranged on the light beam emission side of the panel and shifts the phase of polarized light having a predetermined polarization direction emitted from the liquid crystal panel so as to match the direction of the polarization axis between the liquid crystal panel and the polarizing plate unit. A board is provided.

  According to such an optical unit, the polarizing plate unit is disposed on the light emission side of the liquid crystal panel, and polarized light having a predetermined polarization direction emitted from the liquid crystal panel is interposed between the liquid crystal panel and the polarizing plate unit. By providing a retardation plate that matches the direction of the polarization axis of the polarizing plate unit, the structure of the liquid crystal panel remains the same as before, but the polarized light emitted from the liquid crystal panel is incident on the polarizing plate unit without reducing the efficiency. It is possible to suppress illuminance unevenness.

  Application Example 3 In the optical unit according to the application example described above, it is preferable that the polarizing plate unit and the retardation plate are disposed on the light beam incident side of the liquid crystal panel.

  According to such an optical unit, the illuminance unevenness in the polarizing plate unit can be suppressed by adopting the above configuration in the polarizing plate unit disposed on the light beam incident side of the liquid crystal panel.

  Application Example 4 A projector according to this application example includes the above-described optical unit, and projects light modulated by the optical unit.

  According to such a projector, it is possible to realize a projector that can suppress uneven illumination and suppress a decrease in contrast.

FIG. 2 is a diagram schematically illustrating a schematic configuration of a projector according to an embodiment. The front view which shows the structure of a polarizing plate unit. The perspective view which shows the structure of an optical unit typically. The figure which shows typically the image at the time of making a black display image inject with respect to the conventional polarizing plate unit, and inject | emitting.

Hereinafter, embodiments will be described with reference to the drawings.
(Embodiment)

FIG. 1 is a diagram schematically illustrating a schematic configuration of a projector 1 according to the embodiment. With reference to FIG. 1, a schematic configuration of a projector 1 according to the present embodiment will be described.
The projector 1 according to the present embodiment is a device that modulates a light beam emitted from the light source device 30 (light source 301) according to image information and enlarges and projects it on a projection surface such as a screen (not shown).

  In the subsequent drawings including FIG. 1, the dimensions and ratios of the respective constituent elements are shown as appropriately different from the actual ones in order to make the respective constituent elements large enough to be recognized on the drawing. Moreover, in drawing of FIGS. 1-3, it describes with an XYZ rectangular coordinate system for convenience of explanation. In the XYZ orthogonal coordinate system, the traveling direction of the light beam emitted from the light source device 30 (the direction along the illumination optical axis OA) is the Y direction (+ Y direction), the direction orthogonal to the Y direction and the image light is projected (Y The X direction (+ X direction) is defined as the right direction when viewed from the direction base end side. Furthermore, the Z direction (+ Z direction) is defined as the upward direction in the stationary posture that is orthogonal to the X direction and the Y direction.

  As shown in FIG. 1, the projector 1 includes an optical unit 3, a control unit (not shown), a power supply unit (not shown) that supplies power to the control unit, and a cooling mechanism (not shown) that cools the inside of the projector 1. Etc., and each of these devices is accommodated in the exterior housing 2.

  The optical unit 3 is a unit that optically processes the light beam emitted from the light source device 30 based on control by the control unit to form and project image light according to image information. The optical unit 3 accommodates the light source device 30, the illumination optical device 31, the color separation optical device 32, the relay optical device 33, the electro-optical device 34, and these optical devices 30 to 34 inside, and a projection lens 35 in a predetermined manner. An optical component housing 36 that is supported and fixed at a position is provided.

  The light source device 30 includes a light source 301 and a reflector 302. The light source device 30 aligns the emission direction of the light beam emitted from the light source 301 by the reflector 302, makes it parallel to the illumination optical axis OA, and emits it toward the illumination optical device 31. The illumination optical axis OA is the central axis of the light beam emitted from the light source device 30 toward the illuminated area. The light source device 30 of this embodiment employs an ultrahigh pressure mercury lamp.

  The illumination optical device 31 includes a first lens array 311, a second lens array 312, a polarization conversion element 313, a superimposing lens 314, and a collimating lens 315. The first lens array 311 splits the light beam emitted from the light source device 30 into partial light beams, and emits them in the direction along the illumination optical axis OA. The second lens array 312 emits the partial light beams emitted from the first lens array 311 toward the superimposing lens 314, respectively.

  The polarization conversion element 313 has a function of aligning each partial light beam, which becomes random polarized light emitted from the second lens array 312, with substantially one type of polarized light that can be used in the liquid crystal panel 342 described later. Each partial light beam emitted from the second lens array 312 and converted into substantially one type of polarized light by the polarization conversion element 313 is substantially superimposed on the surface of the liquid crystal panel 342 by the superimposing lens 314. Note that the light beam emitted from the superimposing lens 314 is collimated by the collimating lens 315 and superimposed on the liquid crystal panel 342. The collimating lens 315 is provided for each of three color lights described later.

  The color separation optical device 32 includes a first dichroic mirror 321, a second dichroic mirror 322, and a reflection mirror 323. The color separation optical device 32 separates the light beam emitted from the illumination optical device 31 into three color lights of red (R) light, green (G) light, and blue (B) light.

  The relay optical device 33 includes an incident side lens 331, a relay lens 333, and reflection mirrors 332 and 334. The relay optical device 33 guides the R light separated by the color separation optical device 32 to the liquid crystal panel 342R for R light. In the present embodiment, the relay optical device 33 is configured to guide the R light. However, the present invention is not limited to this. For example, the relay optical device 33 may be configured to guide the B light.

  The electro-optical device 34 includes, for each color light, an incident-side polarizing plate 341, a liquid crystal panel 342 as a light modulation device, a phase difference plate (exit-side retardation plate 343), and an emission-side polarizing plate 344. . The electro-optical device 34 includes a cross dichroic prism 345. Corresponding to the color light, “R” for R light, “G” for G light, and “B” for B light are added to the end of the reference numerals indicating the respective members. The exit side retardation plate 343 and the exit side polarizing plate 344 constitute a polarizing plate unit 5 described later.

  The liquid crystal panel 342 (342R, 342G, 342B) modulates the light beam separated for each color light by the color separation optical device 32 according to image information. The cross dichroic prism 345 has a substantially square shape in plan view in which four right angle prisms are bonded together, and two dielectric multilayer films are formed on the interface where the right angle prisms are bonded together. The cross dichroic prism 345 synthesizes the color lights modulated by the liquid crystal panels 342R, 342G, and 342B and emits them to the projection lens 35.

  The projection lens 35 is composed of a combined lens in which a plurality of lenses are combined, and enlarges and projects the light beam modulated and synthesized by the electro-optical device 34 onto a projection surface such as a screen.

  FIG. 2 is a front view showing the configuration of the polarizing plate unit 5 of the present embodiment. FIG. 3 is a perspective view schematically showing the configuration of the optical unit 3 of the present embodiment. The polarizing plate unit 5 of the present embodiment includes three polarizing plate units 5 (R light polarizing plate unit 5R, G light polarizing plate unit 5G, and B light polarizing plate unit 5B for each color light. 2, and the configuration is substantially the same. In FIG. 2, the polarizing plate unit 5 will be described by taking up the polarizing plate unit 5 </ b> B for B light for convenience of description. Further, the optical unit 3 also includes an electro-optical device 34 (the cross dichroic prism 345 is omitted) for each color light, and all the configurations are substantially the same. In FIG. The optical unit 3 will be described by taking up the configuration of the electro-optical device 34 for light. The configuration and operation of the polarizing plate unit 5 and the optical unit 3 will be described with reference to FIGS.

  As shown in FIG. 2, the polarizing plate unit 5B (5) includes a glass substrate 51 having a substantially square outer shape, and an exit-side polarizing plate 344B (344) as a rectangular polarizing plate installed on the glass substrate 51. It is comprised. Further, as shown in FIGS. 1 and 3, the polarizing plate unit 5B (5) of the present embodiment is a retardation plate installed between the liquid crystal panel 342B (342) and the exit-side polarizing plate 344B (344). The output side phase difference plate 343B (343) is provided.

  As shown in FIG. 2, the exit-side polarizing plate 344 is installed with the polarization axis 3441 aligned with the diagonal direction of the glass substrate 51. In the present embodiment, the polarization axis 3441 includes, as diagonal directions, a corner 511 in the upper right direction (+ Z direction in the + Z direction) and a corner portion in the lower left direction (−X direction in the −Z direction) as the diagonal direction. It is matched with 512. In other words, the polarization axis 3441 faces the exit-side polarizing plate 344 and is inclined 45 degrees in the clockwise direction with respect to the central axis C2 that is symmetrical with respect to the left and right passing through the center C1 of the glass substrate 51.

Here, the configuration of the liquid crystal panel 342 will be described with reference to FIG.
The liquid crystal panel 342 is configured as a so-called high-temperature polysilicon TFT liquid crystal panel. Specifically, the liquid crystal panel 342 includes an active matrix substrate 342B1 in which pixel electrodes (not shown) are formed in a matrix, a counter substrate 342B2 in which a counter electrode (not shown) and a light-shielding film (not shown) are formed, A liquid crystal (not shown) sealed and sandwiched between these substrates 342B1 and 342B2 is schematically configured.

  Further, each of the active matrix substrate 342B1 and the counter substrate 342B2 is subjected to a rubbing process as an alignment process. Specifically, the surface of the alignment film (not shown) formed on the active matrix substrate 342B1 is rubbed in a direction (indicated by the rubbing direction B1) that forms 0 degrees with respect to the vertical direction (Z direction). The surface of the alignment film (not shown) formed on the counter substrate 342B2 is rubbed in a direction (indicated by the rubbing direction B2) that forms 90 degrees with respect to the vertical direction (Z direction). As a result, the liquid crystal is twisted 90 degrees in the major axis direction between the active matrix substrate 342B1 and the counter substrate 342B2. That is, the liquid crystal is twisted and aligned with a twist angle of 90 degrees.

Next, the configuration and operation of the optical unit 3 will be described with reference to FIG. In addition, the code | symbol B showing colored light is abbreviate | omitted and demonstrated.
As shown in FIG. 3, in the optical unit 3, an incident side polarizing plate 341 is installed on the incident side of the liquid crystal panel 342, and an exit side polarizing plate 344 is installed on the exit side. Further, in the present embodiment, polarized light having a predetermined polarization direction transmitted through the liquid crystal panel 342 is transmitted between the liquid crystal panel 342 and the emission side polarizing plate 344, and the direction of the polarization axis 3441 of the emission side polarizing plate 344. An exit-side phase difference plate 343 is installed as a phase difference plate that shifts (rotates) the phase so as to match.

  The optical unit 3 is emitted from the light source device 30 (see FIG. 1) and polarized light L whose polarization direction is aligned by the polarization conversion element 313 (see FIG. 1) (in this embodiment, the polarization direction is aligned in the horizontal direction). Is incident on an incident-side polarizing plate 341 having a horizontal polarization axis 3411 as shown in FIG. Then, the polarized light (light) that has passed through the incident-side polarizing plate 341 enters the liquid crystal panel 342 in parallel with the rubbing direction B2, as indicated by an arrow 3421. Of the light incident on the liquid crystal panel 342, the light incident on the pixels to which no voltage is applied to the liquid crystal is emitted after the polarization axis is twisted 90 degrees in the rubbing direction B 1 as indicated by an arrow 3422. Injected onto the phase difference plate 343.

  Next, light (indicated by an arrow 3431) incident on the emission side retardation film 343 is emitted to the emission side polarizing plate 344 as light rotated by 45 degrees in the clockwise direction (indicated by an arrow 3432). The light incident on the exit-side polarizing plate 344 is transmitted through the exit-side polarizing plate 344 because the polarization axis 3441 of the exit-side polarizing plate 344 is inclined 45 degrees in the clockwise direction.

  Of the light incident on the liquid crystal panel 342, the light incident on the pixels to which the voltage is applied to the liquid crystal is emitted without being twisted by 90 degrees, and is absorbed by the exit-side polarizing plate 344. Blocked.

  The optical unit 3 emits light in the direction along the polarization axis 3441 (polarized light) from the exit-side polarizing plate 344 of the polarizing plate unit 5. In addition, the emission-side polarizing plate 344 generates heat due to the light blocked by the emission-side polarizing plate 344. This heat is transmitted to the glass substrate 51 and the glass substrate 51 generates heat.

  Returning to FIG. 2, the center portion A <b> 1 has the highest temperature in the plane of the glass substrate 51 that generates heat. Moreover, since the glass substrate 51 is substantially square, the portion where the temperature difference from the central portion A1 of the glass substrate 51 is the largest (the portion where the in-plane temperature difference is the largest) has the longest distance from the center C1. There are four corner portions (for example, corner portion 511 (region A2)) serving as a portion. In addition, the portion where the temperature difference with the central portion A1 is the smallest (the portion where the in-plane temperature difference is the smallest) in the upper, lower, left and right outer periphery of the glass substrate 51 is the portion where the distance from the center C1 is the shortest. It becomes a central portion (for example, the intersection 513 portion (region A3) between the central axis C2 and the upper outer periphery on the left and right outer periphery).

  In the present embodiment, the polarization axis 3441 of the exit-side polarizing plate 344 has a temperature that is a diagonal direction connecting the corners 511 and 512 of the glass substrate 51 that is substantially square, that is, the center portion A1 of the glass substrate 51. It is adjusted to the four corners where the difference is greatest. In other words, the glass substrate 51 is inclined 45 degrees clockwise with respect to the central axis C2 passing through the center C1 of the glass substrate 51.

  In this embodiment, the portion in the direction of ± 45 degrees with respect to the direction of the polarization axis 3441 that causes unevenness of illuminance becomes the central portion of the upper, lower, left, and right outer periphery of the glass substrate 51. Specifically, the glass substrate 51 The center axis C2 and the upper and lower outer peripheries intersect, and the X axis passing through the center C1 and the left and right outer perimeters intersect. Therefore, for example, the intersection 513 portion (region A3) described above is obtained.

  Thereby, the polarizing plate unit 5 has the smallest temperature difference between the central portion A1 of the glass substrate 51 and the portion in the direction of ± 45 degrees with respect to the direction of the polarization axis 3441, which causes uneven illumination (central portion A1). And the portion where the stress difference becomes the smallest (for example, the intersection 513 portion (region A3)). In other words, a portion where the stress difference becomes large (four corner portions of the glass substrate 51 (for example, the corner portion 511 (region A2)) and a portion where the stress difference affects illuminance unevenness (with respect to the polarization axis 3441 direction). The portion that is the direction of ± 45 degrees is shifted.

According to the embodiment described above, the following effects can be obtained.
The polarizing plate unit 5 of the present embodiment includes a glass substrate 51 having a substantially square outer shape, and a rectangular emission-side polarizing plate 344 installed on the glass substrate 51. The exit-side polarizing plate 344 is installed with the polarization axis 3441 aligned with the diagonal direction (corner portions 511 and 512 directions) of the glass substrate 51. As a result, portions where the stress difference becomes large (four corner portions of the glass substrate 51 (for example, the corner portion 511 (region A2)) and portions where the stress difference affects illuminance unevenness (± 45 with respect to the polarization axis 3441 direction). In detail, in the present embodiment, the direction of ± 45 degrees with respect to the direction of the polarization axis 3441 that causes uneven illuminance is outside the top, bottom, left, and right of the glass substrate 51. It becomes the direction of the peripheral central part (for example, the intersection 513 part (area A3)) In the glass substrate 51, the central part (for example, the intersection 513 part (area A3)) of the upper, lower, left and right outer periphery Since the distance from the central portion A1 is the shortest in the outer periphery, the in-plane temperature difference from the central portion A1 is smaller than the four corner portions (for example, the corner portion 511 (region A2)), and the stress difference Smaller ( Accordingly, it is possible to realize the polarizing plate unit 5 that can suppress the illuminance unevenness as compared with the conventional case.

In the polarizing plate unit 5 of the present embodiment, since the glass substrate 51 has a substantially square shape, the central portions of the upper, lower, left and right outer peripheries have the same distance from the center of the glass substrate 51. The temperature difference at the periphery is reduced, and the stress difference can be reduced. For example, when the glass substrate 51 has a rectangular shape (rectangular shape), the temperature difference between the central portion of the two short sides and the central portion of the two short sides is larger than that of the central portion of the two long sides. growing. Therefore, illuminance unevenness is likely to occur. By making the glass substrate 51 into a substantially square shape, the stress difference can be reduced and uneven illuminance can be suppressed.
Further, by making the glass substrate 51 substantially square, the area becomes larger than that in the case of a rectangle (rectangle), so that the cooling efficiency of the polarizing plate can be improved.

  In the optical unit 3 of the present embodiment, the polarizing plate unit 5 is disposed on the light emission side of the liquid crystal panel 342, and a predetermined polarization direction emitted from the liquid crystal panel 342 is between the liquid crystal panel 342 and the polarizing plate unit 5. The exit side phase difference plate 343 which aligns the polarized light which has these with the direction of the polarization axis 3441 of the polarizing plate unit 5 is provided. As a result, the liquid crystal panel 342 can be made incident on the exit-side polarizing plate unit 5 without reducing the efficiency of polarized light emitted from the liquid crystal panel 342 while the configuration of the liquid crystal panel 342 is kept as before, and uneven illuminance is suppressed. can do.

  The projector 1 according to the present embodiment includes the optical unit 3, and can project the light modulated by the optical unit 3, thereby realizing the projector 1 that can suppress uneven illuminance and suppress a decrease in contrast.

  According to the polarizing plate unit 5 of the present embodiment, the illuminance unevenness can be suppressed without using a glass substrate having a low absolute value of the linear expansion coefficient as in the conventional case, so that the brightness of the light source device 30 is improved. The present invention can also be applied to the case where the optical unit 3 is made small. Therefore, the projector 1 is suitable for increasing the brightness and reducing the size.

  Note that the present invention is not limited to the above-described embodiment, and various modifications and improvements can be made without departing from the scope of the invention. A modification will be described below.

  In the polarizing plate unit 5 of the embodiment, the exit side polarizing plate 344 is installed with the polarization axis 3441 aligned with the diagonal direction of the glass substrate 51. Specifically, the polarization axis 3441 is aligned with the corner portion 511 of the glass substrate 51 in the upper right direction (+ X direction and + Z direction) and the corner portion 512 in the lower left direction (−X direction and −Z direction). In other words, the polarization axis 3441 is inclined 45 degrees in the clockwise direction with respect to the center axis C2 that is symmetrical on the left and right that passes through the center C1 of the glass substrate 51. However, the present invention is not limited to this, and the polarization axis 3441 may be inclined 45 degrees in the counterclockwise direction with respect to the center axis C2 passing through the center C1.

  The polarizing plate unit 5 of the above embodiment is described by taking up the polarizing plate unit 5B for B light, but the same applies to the polarizing plate unit 5R for R light and the polarizing plate unit 5G for G light. Applicable. The B light electro-optical device 34 has been described as the optical unit 3 of the embodiment, but the present invention is similarly applied to the R light electro-optical device 34 and the G light electro-optical device 34. it can.

  In the optical unit 3 of the embodiment, the polarizing plate unit 5 is disposed on the light emission side of the liquid crystal panel 342, and a retardation plate (exit side retardation plate 343) is provided between the liquid crystal panel 342 and the polarizing plate unit 5. I have. However, the present invention is not limited to this, and the polarizing plate unit and the phase difference plate may be disposed also on the light beam incident side of the liquid crystal panel 342, and uneven illuminance in the polarizing plate unit can be further suppressed.

  The projector 1 of the embodiment employs a so-called three-plate method using three liquid crystal panels 342 corresponding to R light, G light, and B light. However, the present invention is not limited to this, and a single plate type light modulation device may be adopted. Further, a light modulation device for improving the contrast may be additionally employed.

  The light source device 30 of the embodiment employs an ultra-high pressure mercury lamp, but is not limited thereto, and various discharge lamps that emit light with high brightness can be employed. For example, a metal halide lamp or a high-pressure mercury lamp Etc. can be adopted. Further, the light source device 30 is not limited to this, and the light source device 30 may adopt various solid light emitting elements such as an LED (Light Emitting Diode), an organic EL (Electro Luminescence) element, and a silicon light emitting element.

  DESCRIPTION OF SYMBOLS 1 ... Projector, 3 ... Optical unit, 5 ... Polarizing plate unit, 30 ... Light source device, 51 ... Glass substrate, 342 ... Liquid crystal panel, 343 ... Ejection side phase difference plate, 344 ... Ejection side polarizing plate, 3441 ... Polarization axis.

Claims (3)

A liquid crystal panel that modulates incident light according to image information;
An optical unit comprising a polarizing plate unit,
The polarizing plate unit, the disposed light-irradiation side of the liquid crystal panel, Bei example a polarizing plate installed on the glass substrate and the glass substrate,
The glass substrate has a substantially square outer shape,
The polarizing plate is installed with the polarization axis aligned with the diagonal direction of the glass substrate ,
A retardation plate is provided between the liquid crystal panel and the polarizing plate unit to shift the phase of polarized light having a predetermined polarization direction emitted from the liquid crystal panel so as to be aligned with the direction of the polarization axis. A featured optical unit. The optical unit according to claim 1 ,
The optical unit, wherein the polarizing plate unit and the retardation plate are disposed on a light beam incident side of the liquid crystal panel. Comprising an optical unit according to claim 1 or claim 2, the projector, characterized in that projects the light modulated in the optical unit.

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