JP2012159782A - Projection type display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a projection type display device capable of preventing a reduction in contrast even during projection by suppressing a phase difference change of a phase difference compensation plate.SOLUTION: A projector according to the present invention comprises: a lighting device for emitting three colors light; three sets of image forming optical systems; a color synthesizing element for synthesizing the three colors light; and a projection optical system for projecting synthesized light on a projection surface to be projected such as a screen. The lighting device comprises: a light source; an integrator optical system; and a color separation optical system. Each of the image forming optical systems 3G comprises: an incident side polarizing plate 9; a PBS 10; a reflection type liquid crystal light valve 11G; a phase difference compensation plate 12; and an emission side polarizing plate 13. A liquid crystal light valve for green light 11G, the phase difference compensation plate 12 and the emission side polarizing plate 13 are fixed to a housing 50 having a substantially triangular shape, and a sealed space of the housing 50 is filled with dry gas 51.

Description

  The present invention relates to a projection display device.

  In recent years, a projector having a vertical alignment (hereinafter sometimes abbreviated as VA) mode liquid crystal light valve has been proposed as having excellent contrast when viewed from the front. A VA mode liquid crystal light valve is obtained by sandwiching a liquid crystal layer having negative dielectric anisotropy between a pair of substrates and aligning liquid crystal molecules substantially vertically in a state where no voltage is applied. However, even when such a VA mode liquid crystal light valve is used, the contrast is lowered when viewing from an oblique direction, and the display quality is lowered.

  Therefore, conventionally, a phase difference compensation element having an optical axis along the thickness direction, that is, a so-called C plate (a negative uniaxial compensation element having the smallest refractive index in the thickness direction) is used to pass through the liquid crystal layer obliquely. Compensation of the phase difference of light is performed. At this time, the C plate is tilted so that the optical axis of the C plate is parallel to the pretilt direction of the liquid crystal molecules, so that the front phase difference of the liquid crystal is compensated by the C plate.

  However, when the positional deviation of the inclination jig (inclination angle deviation) or the azimuth angle deviation of the liquid crystal alignment occurs, sufficient phase difference compensation cannot be performed only by inclining the C plate. Further, when the cell thickness of the liquid crystal panel varies, it is necessary to adjust the front phase difference of the liquid crystal panel with respect to the cell thickness change by the inclination angle of the C plate. However, in this case, the effective retardation of the C plate deviates from the optimum condition, and sufficient phase difference compensation cannot be performed. Further, as the pretilt angle of the liquid crystal molecules increases, the tilt angle of the C plate also increases. At this time, however, the difference in reflectance between P-polarized light and S-polarized light occurs with respect to incident polarized light, and the axis of incident polarized light is shifted. Decreases the contrast.

Therefore, a projector using a C + O compensator in which such a C plate and a so-called O plate integrated with a phase difference compensation element having biaxial refractive index anisotropy, for example, has been proposed (for example, Patent Document 1). reference).
In this projector, a liquid crystal light valve and a phase difference compensation plate are attached to one side surface in a state where the phase difference compensation plate is arranged inside, and a triangular prism having the inner space as an optical path is arranged for each color light, By cooling in the cooling section so that the temperature on the top surface side of the triangular prism is lower than the temperature on the bottom surface side, phase difference compensation is performed and the contrast is increased.

JP 2009-75302 A

However, in the conventional projector described above, the use of the C + O compensator eliminates the need to incline the compensator and enables space saving, but has a new problem due to the use of the C + O compensator.
That is, the C + O compensator has a problem that the phase difference changes due to the change in humidity due to the structure of the O plate that it has.
This phase difference change follows slowly with respect to the change in the humidity of the environment where the C + O compensator is placed. Therefore, if the phase difference value of the C + O compensator changes, the phase difference compensation is shifted, resulting in a difference. It will affect the contrast.

Here, when projection is performed using a projector, the temperature of the C + O compensator rises to near 100 ° C., and the environment around the C + O compensator at this time is near 100 ° C. and humidity is about 0%. It is up to. For example, when the projector is left in an environment where the humidity is 40%, when the projection is performed using the projector, the phase difference value of the C + O compensator changes by about 10%. Since the change of the phase difference value follows slowly with respect to the change of the humidity, there is a problem that the contrast may be gradually lowered during the projection of the projector.
Further, when the C + O compensator is set so that the contrast becomes maximum when the humidity is 0%, there is a problem that the contrast is lowered immediately after the projector is projected.

  The present invention has been made to solve the above-described problems, and can suppress a decrease in contrast even during projection by suppressing a change in phase difference of a phase difference compensation plate. An object is to provide an apparatus.

In order to solve the above problems, the present invention employs the following projection type display device.
That is, a first projection type display device of the present invention includes a light source that emits a plurality of color lights of different colors, a plurality of reflective liquid crystal light valves in a vertical alignment mode that modulates each of the plurality of color lights, The liquid crystal light valve and the phase difference compensation plate are arranged in a state where the phase difference compensation plate provided in each of the liquid crystal light valves and the phase difference compensation plate provided in the liquid crystal light valve are disposed inside. A plurality of housings having an internal space as an optical path, a color combining optical system for combining the color lights modulated by the plurality of liquid crystal light valves, and a light combined by the color combining optical system. A projection optical system for projecting onto the projection surface, and the housing is filled with dry gas.

  In this projection type display device, the humidity inside the housing is extremely high by holding the phase difference compensation plate on one side and filling the housing with the internal space as an optical path with dry gas. In addition, this low humidity can be maintained for a long period of time. Therefore, the inside of the housing is hardly affected by the outside air, and the phase difference change of the phase difference compensator arranged in the housing is eliminated. As a result, it is possible to prevent a decrease in contrast.

  A second projection type display device of the present invention includes a light source that emits a plurality of color lights of different colors, a plurality of reflective liquid crystal light valves in a vertical alignment mode that modulates each of the plurality of color lights, The liquid crystal light valve and the phase difference compensation plate are arranged on one side in a state where the phase difference compensation plate provided on each liquid crystal light valve and the phase difference compensation plate provided on the liquid crystal light valve are arranged inside. A plurality of housings having an internal space as an optical path, a color combining optical system for combining the color lights modulated by the plurality of liquid crystal light valves, and a projection surface for the light combined by the color combining optical system A projection optical system for projecting upward, and the inside of the casing is filled with a substance having no refractive index anisotropy.

  In this projection type display device, the phase difference compensation plate is held on one side with the phase difference compensation plate arranged on the inside, and the inside of the housing having the internal space as the optical path is filled with a material having no refractive index anisotropy. The influence of humidity in the housing can be removed, and the state from which the influence of humidity has been removed can be maintained for a long period of time. Therefore, the inside of the housing is hardly affected by the outside air, and the phase difference change of the phase difference compensator arranged in the housing is eliminated. As a result, it is possible to prevent a decrease in contrast.

In these projection type display devices, the retardation compensation plate is an integrated C plate and O plate.
In these projection type display devices, since the retardation compensation plate is formed by integrating the C plate and the O plate, the size and space can be reduced, and the arrangement is easy.

1 is a schematic configuration diagram illustrating a projector according to a first embodiment of the present invention. FIG. 2 is a perspective view illustrating a configuration around a liquid crystal light valve of the projector according to the first embodiment of the invention. It is sectional drawing of the triangular prism unit holding the liquid crystal light valve of the projector of the 1st Embodiment of this invention. (A), (B) is a schematic diagram for demonstrating the optical anisotropy of C plate and O plate of a phase difference compensating plate. It is a figure which shows the relationship between the humidity in 25 degreeC in the housing | casing of the triangular prism unit of the 1st Embodiment of this invention, and a phase difference value. It is sectional drawing of the triangular prism unit holding the liquid crystal light valve of the projector of the 2nd Embodiment of this invention. It is a figure which shows the relationship between the humidity in 25 degreeC in a housing | casing of the triangular prism unit of the 2nd Embodiment of this invention, and a phase difference value.

[First Embodiment]
Hereinafter, a first embodiment of the present invention will be described with reference to FIGS.
In the present embodiment, a projector having three reflective liquid crystal light valves, that is, a so-called three-plate liquid crystal projector will be described as an example.
FIG. 1 is a schematic configuration diagram illustrating a projector according to the present embodiment. FIG. 2 is a perspective view showing a configuration around the liquid crystal light valve of the projector. FIG. 3 is a cross-sectional view of the triangular prism unit that holds the liquid crystal light valve. FIG. 4 is a schematic diagram for explaining the optical anisotropy of the C plate and the O plate of the retardation compensation plate.
It should be noted that in all of the following drawings, in order to make each component easy to see, the scale of dimensions may be different depending on the component.

  As shown in FIG. 1, the projector 1 according to this embodiment includes a lighting device 2 that emits three colors of light including red light (R light), green light (G light), and blue light (B light), and each color. Three sets of image forming optical systems 3R, 3G, and 3B that form images by light, a color combining element 4 (color combining optical system) that combines three colors of light, and a projected surface such as a screen And a projection optical system 5 for projecting to (not shown). The illumination device 2 includes a light source 6, an integrator optical system 7, and a color separation optical system 8. The image forming optical systems 3R, 3G, and 3B include an incident-side polarizing plate 9, a PBS 10, a reflective liquid crystal light valve 11R, 11G, and 11B, a phase difference compensating plate 12, and an exit-side polarizing plate 13. ing.

The projector 1 generally operates as follows.
White light emitted from the light source 6 enters the integrator optical system 7. The white light incident on the integrator optical system 7 is emitted with uniform illuminance and with the polarization state aligned with a predetermined linearly polarized light. The white light emitted from the integrator optical system 7 is separated into R, G, and B color lights by the color separation optical system 8 and is incident on different sets of image forming optical systems 3R, 3G, and 3B for each color light. The color light incident on each of the image forming optical systems 3R, 3G, 3B becomes modulated light modulated based on the image signal of the image to be displayed. The three colors of modulated light emitted from the three sets of image forming optical systems 3R, 3G, and 3B are combined by the color combining element 4 to become multicolor light and enter the projection optical system 5. The polychromatic light incident on the projection optical system 5 is projected onto a projection surface such as a screen. In this way, a full color image is displayed on the projection surface.

Hereinafter, each component of the projector 1 will be described in detail.
The light source 6 includes a light source lamp 15 and a parabolic reflector 16. The light emitted from the light source lamp 15 is reflected in one direction by the parabolic reflector 16 to become a substantially parallel light beam, and enters the integrator optical system 7 as light source light. The light source lamp 15 is composed of, for example, a metal halide lamp, a xenon lamp, a high-pressure mercury lamp, a halogen lamp, or the like. Instead of the parabolic reflector 16, an elliptical reflector, a spherical reflector, or the like may be used. A collimating lens that collimates the light emitted from the reflector may be used according to the shape of the reflector.

  The integrator optical system 7 includes a first lens array 17, a second lens array 18, a polarization conversion element 19, and a superimposing lens 20. The first lens array 17 has a plurality of microlenses 21 arranged on a surface substantially orthogonal to the optical axis L1 of the light source 6. Similar to the first lens array 17, the second lens array 18 has a plurality of microlenses 22. The microlenses 21 and 22 are arranged in a matrix, and the planar shape in a plane orthogonal to the optical axis L1 is similar to the illuminated area of the liquid crystal light valves 11R, 11G, and 11B (substantially rectangular). . The illuminated area is an area in which a plurality of pixels are arranged in a matrix in the liquid crystal light valves 11R, 11G, and 11B and contribute substantially to display.

  The PBS 10 is a wire grid type PBS, and is composed of, for example, a glass substrate and a plurality of metal wires formed thereon (not shown). The plurality of metal wires all extend in one direction (Z direction) and are formed on the glass substrate so as to be spaced apart from each other substantially in parallel. The main surface of the glass substrate on which the plurality of metal lines is formed is a polarization separation plane, the extending direction of the plurality of metal lines is the reflection axis direction, and the arrangement direction of the plurality of metal lines is the transmission axis direction. The polarization separation surface forms an angle of about 45 ° with respect to the central axis of the light incident on the polarization separation surface. Of the light incident on the polarization separation surface, S-polarized light whose polarization direction matches the reflection axis direction is reflected by the polarization separation surface, and P-polarized light whose polarization direction matches the transmission axis direction passes through the polarization separation surface. Hereinafter, P-polarized light with respect to the polarization separation surface of the PBS 10 is simply referred to as P-polarization, and S-polarization with respect to the polarization separation surface of the PBS 10 is simply referred to as S-polarization.

  The phase difference compensation plate 12 is formed by forming a C plate (negative uniaxial C plate) on one surface of a quartz glass substrate and an O plate on the other surface. By using a C + O compensator that integrates a C plate with a vertical optical axis and an O plate with biaxial refractive index anisotropy, it is not necessary to incline the compensator as in the past, saving space. And can be easily arranged.

  The polarization conversion element 19 has a plurality of polarization conversion units 23. Each polarization conversion unit 23 has a polarization separation film (hereinafter referred to as a PBS film), a ½ phase plate, and a reflection mirror, although its detailed structure is not shown. Each microlens 21 of the first lens array 17 has a one-to-one correspondence with each microlens 22 of the second lens array 18. Each micro lens 22 of the second lens array 18 has a one-to-one correspondence with each polarization conversion unit 23 of the polarization conversion element 19.

  The light source light incident on the integrator optical system 7 is spatially divided and incident on the plurality of microlenses 21 of the first lens array 17 and is collected for each light beam incident on the microlens 21. The light source light collected by each microlens 21 forms an image on the microlens 22 of the second lens array 18 corresponding to the microlens 21. That is, a secondary light source image is formed on each of the plurality of microlenses 22 of the second lens array 18. The light from the secondary light source image formed on the microlens 22 enters the polarization conversion unit 23 corresponding to the microlens 22.

  The light incident on the polarization conversion unit 23 is separated into P-polarized light and S-polarized light with respect to the PBS film. One of the separated polarized light (for example, S-polarized light) is reflected by a reflection mirror and then passed through a half-phase plate, so that the polarization state is converted and aligned with the other polarized light (for example, P-polarized light). Here, the polarization state of the light that has passed through the polarization conversion unit 23 is aligned with the polarization state that is transmitted through the incident-side polarizing plate 9 described later. Light emitted from the plurality of polarization conversion units 23 is superimposed on the illuminated areas of the liquid crystal light valves 11R, 11G, and 11B by the superimposing lens 20. The luminous fluxes spatially divided by the first lens array 17 illuminate substantially the entire illuminated area, whereby the illuminance distribution is averaged and the illuminance on the illuminated area is made uniform.

  The color separation optical system 8 includes a first dichroic mirror 25, a second dichroic mirror 26, a third dichroic mirror 27, a first reflection mirror 28, and a second reflection mirror 29 having a wavelength selection surface. The first dichroic mirror 25 has a spectral characteristic that reflects the red light LR and transmits the green light LG and the blue light LB. The second dichroic mirror 26 has a spectral characteristic that transmits the red light LR and reflects the green light LG and the blue light LB. The third dichroic mirror 27 has a spectral characteristic that reflects the green light LG and transmits the blue light LB. The first dichroic mirror 25 and the second dichroic mirror 26 are configured such that each wavelength selection surface is substantially orthogonal to each other, and each wavelength selection surface forms an angle of about 45 ° with the optical axis L2 of the integrator optical system 7. Are arranged as follows.

  The red light LR, the green light LG, and the blue light LB contained in the light source light incident on the color separation optical system 8 are separated as follows, and the image forming optical systems 3R, 3G, Incident on 3B. That is, the red light LR is transmitted through the second dichroic mirror 26, reflected by the first dichroic mirror 25, then reflected by the first reflecting mirror 28, and enters the red light image forming optical system 3R. The green light LG is transmitted through the first dichroic mirror 25, reflected by the second dichroic mirror 26, then reflected by the second reflecting mirror 29, reflected by the third dichroic mirror 27, and image forming optical system for green light Incident to 3G. The blue light LB is transmitted through the first dichroic mirror 25, reflected by the second dichroic mirror 26, then reflected by the second reflective mirror 29, and transmitted through the third dichroic mirror 27, thereby forming an image forming optical system for blue light. Incident on 3B. The light modulated by each image forming optical system enters the color synthesis element.

  The color synthesizing element 4 is constituted by a dichroic prism. The dichroic prism has a structure in which four triangular prisms are bonded to each other. The surface to be bonded in the triangular prism becomes the inner surface of the dichroic prism. On the inner surface of the dichroic prism, a mirror surface that reflects red light LR and transmits green light LG and a mirror surface that reflects blue light LB and transmits green light LG are formed orthogonal to each other. The green light LG that has entered the dichroic prism travels straight through the mirror surface and is emitted. The red light LR and the blue light LB incident on the dichroic prism are selectively reflected or transmitted by the mirror surface and emitted in the same direction as the emission direction of the green light LG. In this way, the three color lights (images) are superimposed and synthesized, and the synthesized color lights are enlarged and projected onto the screen 7 by the projection optical system 5. The projection optical system 5 has a first lens group 44 and a second lens group 45.

  In the case of this embodiment, as shown in FIG. 2, the red light image forming optical system 3R, the green light image forming optical system 3G, and the blue light image forming optical system 3B are all unitized. It is configured. The three unitized image forming optical systems are bonded to the three surfaces of the color synthesizing element.

Here, as a representative of the image forming optical system, the configuration of the green light image forming optical system 3G will be described.
As shown in FIG. 3, the green light image forming optical system 3G includes an incident side polarizing plate 9, a PBS 10, a green light liquid crystal light valve 11G, a phase difference compensation plate 12, an exit side polarizing plate 13, It has. In addition, it is desirable that the incident-side polarizing plate 9 and the emission-side polarizing plate 13 are composed of wire grid type polarizing plates in consideration of heat resistance and the like.
The green light liquid crystal light valve 11G is a reflective liquid crystal light valve, and the liquid crystal mode is a vertical alignment mode. The green light liquid crystal light valve 11G includes a TFT array substrate 31 and a counter substrate 32 that are disposed to face each other, and a liquid crystal layer 33 that is sandwiched between the two substrates. The liquid crystal layer 33 is made of a liquid crystal material having a negative dielectric anisotropy.

A phase difference compensation plate 12 is disposed on the optical path between the PBS 10 and the green light liquid crystal cell 11G.
Since the retardation compensation plate 12 is composed of a C + O compensation plate in which a C plate whose optical axis is perpendicular to the surface and an O plate having biaxial refractive index anisotropy are integrated. There is no need to incline the compensation plate as in the prior art, space saving is possible, and the arrangement is easy.

Here, the optical anisotropy of the retardation compensation plate 12 will be described.
As shown in FIG. 4A by a refractive index ellipsoid, the C plate 53 of the phase difference compensation plate 12 has a refractive index relationship of nx = ny> nz in each direction of the C plate. Since it is isotropic with respect to light incident parallel to the axis, the phase difference cannot be compensated. In other words, the phase difference cannot be compensated for the light that enters the C plate 53 perpendicularly from the liquid crystal panel. On the other hand, of the light emitted from the liquid crystal panel, the phase difference of the oblique component light, that is, the oblique component of the VA mode liquid crystal is optically compensated. The C plate 62 does not have to completely satisfy nx = ny and may have a slight phase difference. Specifically, the front phase difference value may be about 0 nm to 3 nm. .

As this type of C plate 53, the thickness direction retardation Rth is preferably 100 nm or more and 300 nm or less, and more preferably 180 nm. Here, the thickness direction retardation Rth is defined by the following equation.
Rth = {(nx + ny) / 2−nz} × d
In the C plate shown in FIG. 4A, nx and ny indicate the main refractive index in the surface direction, and nz similarly indicates the main refractive index in the thickness direction. D indicates the thickness of the C plate.

  On the other hand, in the O plate 54, as shown by a refractive index ellipsoid in FIG. 4B, the relationship between the refractive indexes in each direction becomes nx <ny <nz (or although not shown, nz <ny <nx This is a biaxial retardation compensation plate. The O plate 54 has a slow axis 54c due to the inorganic film forming the above-described column. The slow axis 54c of the O plate 54 coincides with the major axis of the ellipse obtained by projecting the refractive index ellipsoid shown in FIG. 4B on the substrate 61 (substrate surface) when viewed from the normal direction of the substrate 61. To do.

  In the green light image forming optical system 3G, among these components, except for the incident side polarizing plate 9, the PBS 10, the green light liquid crystal light valve 11G, the phase difference compensation plate 12, and the emission side polarizing plate 13 are: It is fixed to a housing 50 having a substantially triangular prism shape. The casing 50 is made of a material having high thermal conductivity such as aluminum.

  Openings that allow light to pass through are respectively provided on three side surfaces of the housing 50. Of the three side surfaces of the housing 50, two surfaces that are in contact with each other at right angles are defined as a first side surface and a second side surface, and a surface that is in contact with the first side surface and the second side surface at an angle of 45 ° is defined as a third side surface. . A liquid crystal light valve 11R is fixed on the outer surface side of the first side surface so as to close the opening portion, and a phase difference compensation plate 12 is fixed on the inner surface side of the first side surface so as to close the opening portion. That is, the opening is closed in a state where the edge (peripheral part) of the opening is sandwiched between the outer edge (outer peripheral part) of the liquid crystal light valve 11R and the outer edge (outer peripheral part) of the retardation compensation plate 12. An exit-side polarizing plate 13 is fixed on the outer surface side of the second side surface so as to close the opening. A PBS 10 is fixed on the outer surface side of the third side surface so as to close the opening. With such a configuration, the inside of the housing 50 is a sealed space.

The sealed space of the housing 50 is filled with a dry gas 51.
Examples of the dry gas include dry air having a low humidity, for example, a humidity of 25% or less at 25 ° C., and dry nitrogen gas. This dry air can be obtained by sealing a desiccant such as silica gel or a dehumidifier together with air in a sealed space of the casing 50. It is good also as inject | pouring dry nitrogen gas etc. instead of this dry air.

In the green light image forming optical system 3G, the green light LG separated from the light source light is incident on the incident-side polarizing plate 9. The incident-side polarizing plate 9 transmits linearly polarized light that vibrates in a predetermined direction, and the transmission axis is set so as to transmit P-polarized light with respect to the polarization separation surface of the PBS 10. Since the light source light that has passed through the integrator optical system 7 has the polarization state aligned with the P-polarized light, almost all of the green light LG passes through the incident side polarizing plate 9 and enters the PBS 10.
In this PBS 10, the main surface of the glass substrate on which a plurality of metal lines is formed becomes a polarization separation surface, and this polarization separation surface has an angle of about 45 ° with respect to the central axis of the green light LG incident on the polarization separation surface. Therefore, of the green light LG incident on the polarization separation surface, S-polarized light whose polarization direction matches the reflection axis direction is reflected by the polarization separation surface, and P-polarized light whose polarization direction matches the transmission axis direction is polarized light separation. Transparent through the surface.

  The green light LG that has passed through the PBS 10 sequentially passes through the phase difference compensation plate 12 and the counter substrate 32, enters the liquid crystal layer 33, and then is reflected and folded on the TFT array substrate 31. The green light LG is modulated while being transmitted through the liquid crystal layer 33 to become modulated light, and is transmitted again through the counter substrate 32 and the phase difference compensation plate 12.

FIG. 5 is a diagram illustrating the relationship between the humidity at 25 ° C. in the housing 50 of the triangular prism unit and the phase difference value. If the humidity is kept below 25%, the fluctuation range of the phase difference value is 5%. It can be seen that the following can be suppressed.
Thus, by keeping the humidity in the housing 50 at 25% or less, the inside of the housing 50 is hardly affected by the outside air, and the phase difference change of the phase difference compensating plate 12 disposed in the housing 50 is changed. It is possible to suppress the reduction of the contrast.
Further, when projection is performed using the projector 1, even when the temperature of the phase difference compensation plate 12 rises to near 100 ° C., the fluctuation range of the phase difference value is 5% or less as shown in FIG. And there is no possibility that the contrast is lowered during projection by the projector.

  As described above, according to the projector 1 of the present embodiment, the dry gas 51 is filled in the sealed space of the casing 50 of the triangular prism unit, so the humidity in the casing 50 is kept at 25% or less. Moreover, this low humidity can be maintained over a long period of time. Therefore, since the inside of the housing 50 is hardly affected by the outside air, the change in the phase difference of the phase difference compensation plate 12 disposed in the housing 50 can be eliminated, and as a result, the reduction in contrast can be prevented. Can do.

[Second Embodiment]
FIG. 6 is a cross-sectional view of the triangular prism unit that holds the liquid crystal light valve of the projector according to the second embodiment of the present invention. The triangular prism unit of the present embodiment is different from the triangular prism unit of the first embodiment in the first embodiment. In the triangular prism unit of the embodiment, the sealed space of the casing 50 is filled with the dry gas 51, whereas in the triangular prism unit of the present embodiment, the substance having no refractive index anisotropy in the sealed space of the casing 50 is used. The other points are exactly the same as those of the projector according to the first embodiment.

As the material having no refractive index anisotropy, glass such as borosilicate glass or potassium borosilicate glass is preferably used.
The substance having no refractive index anisotropy can be filled by placing the phase difference compensation plate 12 and the like in the housing 50 and then filling the sealed space of the housing 50.

  In this triangular prism unit, since the sealed space of the casing 50 is filled with the substance 71 having no refractive index anisotropy, there is no moisture around the retardation compensation plate 12, and the retardation compensation plate 12 is Unaffected by ambient humidity.

FIG. 7 is a diagram showing the relationship between the humidity at 25 ° C. in the housing 50 of the triangular prism unit and the phase difference value. The sealed space of the housing 50 is filled with a substance 71 having no refractive index anisotropy. Therefore, it can be seen that the humidity of this space is 0%, and the fluctuation range of the phase difference value can be 0%.
As described above, since the sealed space of the casing 50 is filled with the substance 71 having no refractive index anisotropy, the inside of the casing 50 is not affected by the outside air, and the position where the casing 50 is disposed. The phase difference change of the phase difference compensation plate 12 can be eliminated, and the contrast can be prevented from being lowered.
Further, when projection is performed using this projector, even when the temperature of the phase difference compensation plate 12 rises to near 100 ° C., there is no change in phase difference of the phase difference compensation plate 12 and during projection of the projector. There is no risk of lowering the contrast.

The projector according to the present embodiment can achieve the same operations and effects as the projector according to the first embodiment.
Moreover, since the sealed space of the housing 50 is filled with the substance 71 having no refractive index anisotropy, the inside of the housing 50 is not affected by the outside air, and the phase difference disposed in the housing 50 is not affected. The change in the phase difference of the compensation plate 12 can be eliminated, and the reduction in contrast can be prevented.

The technical scope of the present invention is not limited to the above embodiment, and various modifications can be made without departing from the spirit of the present invention. For example, in the above-described embodiment, a retardation plate in which a C plate (negative uniaxial C plate) is formed on one surface of a quartz glass substrate and an O plate is formed on the other surface is used. However, a C plate (negative uniaxial C plate) is formed on one surface of a quartz glass substrate, and a C plate (negative uniaxial C plate) and an O plate are stacked in this order on the other surface. A thing may be used.
In addition, the material, shape, number, arrangement, and the like of the various structural members of the projector are not limited to the above-described embodiment, and can be changed as appropriate.

DESCRIPTION OF SYMBOLS 1 ... Projector, 11R, 11G, 11B ... Reflective type liquid crystal light valve, 12 ... Retardation compensation plate, 50 ... Housing, 51 ... Dry gas, 53 ... C plate, 54 ... O plate, 71 ... Anisotropy of refractive index Non-sexual substance

Claims (3)

A light source that emits multiple colored lights of different colors;
A plurality of reflective liquid crystal light valves in a vertical alignment mode for modulating each of the plurality of color lights;
A retardation compensation plate provided in each of the plurality of liquid crystal light valves;
A plurality of housings that hold the liquid crystal light valve and the phase difference compensation plate on one side in a state where the phase difference compensation plate provided on the liquid crystal light valve is disposed on the inner side, and have an internal space as an optical path. When,
A color synthesizing optical system that synthesizes the color light modulated by the plurality of liquid crystal light valves;
A projection optical system that projects the light synthesized by the color synthesis optical system onto a projection surface, and
A projection-type display device, wherein the casing is filled with a dry gas. A light source that emits multiple colored lights of different colors;
A plurality of reflective liquid crystal light valves in a vertical alignment mode for modulating each of the plurality of color lights;
A retardation compensation plate provided in each of the plurality of liquid crystal light valves;
A plurality of housings that hold the liquid crystal light valve and the phase difference compensation plate on one side in a state where the phase difference compensation plate provided on the liquid crystal light valve is disposed on the inner side, and have an internal space as an optical path. When,
A color synthesizing optical system that synthesizes the color light modulated by the plurality of liquid crystal light valves;
A projection optical system that projects the light synthesized by the color synthesis optical system onto a projection surface, and
A projection type display device characterized in that the casing is filled with a substance having no refractive index anisotropy.   3. The projection type display device according to claim 1, wherein the phase difference compensation plate is formed by integrating a C plate and an O plate.

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