JP2007093741A - Image display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image display device constituted so that contrast can be kept excellent while restraining the lowering of the luminance of a display image, and the high-luminance display image may be obtained while restraining the lowering of the contrast. <P>SOLUTION: In the image display device where spatial optical modulation elements 12, 18 and 21 are illuminated with the integration of illuminating light emitted from a light source 1, and an image is formed with the illuminating light passing through the spatial optical modulation elements 12, 18 and 21 by a projection optical system 22, an optical system leading to the projection optical system 22 from the light source 1 is provided with a diaphragm means 5 making an F value larger in directions other than the polarization direction of the illuminating light made incident on the spatial optical modulation elements 12, 18 and 21 and a direction orthogonal thereto. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an image display device that displays an image displayed by a spatial light modulation element via an imaging optical system such as a projection lens.

  Conventionally, illumination light for a spatial light modulation element such as a liquid crystal light valve is modulated by the spatial light modulation element, and the modulated illumination light is enlarged and imaged on a screen via an imaging optical system such as a projection lens. An image display device that displays an image has been proposed.

  In such an image display device, the polarization state of the illumination light is modulated by controlling the illumination light for each pixel of the spatial light modulation element using a reflective or transmissive spatial light modulation element. It is carried out. In such an image display device, the spatial light modulator is illuminated with linearly polarized illumination light emitted from a light source via an illumination optical system.

  FIG. 21 is a side view showing a schematic configuration of a so-called “lens array type” illumination optical system in a conventional image display apparatus.

  In such an image display apparatus, as the illumination optical system for irradiating the spatial light modulation element with illumination light, a “lens array system” having a lens array is generally used as shown in FIG. . In an image display apparatus including a “lens array type” illumination optical system, illumination light emitted from the light source 101 is reflected by the reflector 102 and emitted in the optical axis direction. The illumination optical system 103 includes a first lens array (fly eye lens) 104, a second lens array (fly eye lens) 105, an overlapping lens 106, and a condenser lens 107. On the first and second lens arrays 104 and 105, a large number of lens cells having openings substantially similar to the spatial light modulator 108 illuminated through the illumination optical system are two-dimensionally arranged. The exit opening surface of the reflector 102 is spatially divided.

  Each lens cell of the first lens array 104 condenses the light flux on the lens cell of the second lens array 105 corresponding to each lens cell. The same number of secondary light source images as the lens cells of the first lens array 104 are formed on the second lens array 105. Then, each lens cell on the second lens array 105 is subjected to spatial light modulation through the polarization beam splitter 109 through the image of each lens cell opening of the corresponding first lens array 104, that is, the tertiary light source image. It is formed on the incident surface of the element 108.

  The superimposing lens 106 makes the center of the image of each lens cell aperture of the first lens array 104 coincide with the center of the incident surface of the spatial light modulator 108, and the image of these lens cell apertures on the spatial light modulator 108. Overlapping.

  As a result, the intensity of the illumination light reflected by the reflector 102 is integrated, and the spatial light modulator 108 is superimposed and illuminated with a uniform intensity distribution by the plurality of secondary or tertiary light source images.

  Further, as shown in FIG. 22, the condenser lens 107 forms a secondary light source image on the second lens array 105 on the entrance pupil 110a of the projection optical system 110 via the polarization beam splitter 109. Has been placed.

  The F value of the illumination optical system is determined by the aperture area of the second lens array 105, and the F value of the projection optical system 110 is determined by the aperture area of the entrance pupil 110 a of the projection optical system 110.

  The spatial light modulator 108 includes, for example, a transmissive or reflective liquid crystal plate in which a plurality of liquid crystal cells are two-dimensionally arranged, and an analyzer (polarizing plate) that transmits only polarized light in a predetermined direction. ing. Then, the liquid crystal plate is controlled by an electric signal, so that light that is transmitted or reflected is polarized and modulated. The illumination light that illuminates the spatial light modulator 108 is modulated into P-polarized light or S-polarized light according to image information in the spatial light modulator 108 as shown in FIG. The illumination light that has passed through the spatial light modulation element 108 is returned to the first and second lens arrays 104 and 105 according to the polarization direction by the polarization beam splitter 109 serving as a polarization separation element, and the projection optical system 110. And the optical path incident on the light. Then, only the light in the polarization direction corresponding to the white information of the image information is incident on the projection optical system 110 and projected as image light. The image display apparatus enlarges and displays the image information displayed by the spatial light modulator 108 with the above-described configuration.

  Note that a light beam whose incident angle is shifted in a direction perpendicular to a plane including the incident optical axis and the outgoing optical axis with respect to the polarizing beam splitter 109 is spatially modulated after the polarization direction after passing through the polarizing beam splitter 109. The element 108 deviates from the optimum direction. Therefore, by arranging a wave plate (λ / 4 plate (quarter wave plate)) 111 between the polarization beam splitter 109 and the spatial light modulator 108, the pretilt and polarization of the spatial light modulator 108 are arranged. The oblique light with respect to the beam splitter 109 is compensated so that the polarization direction of the illumination light becomes the optimum polarization direction with respect to the spatial light modulator 108.

  By the way, the image display apparatus described above is for monochrome display. In the color display image display device, the illumination light that has passed through the illumination optical system 103 is color-separated into RGB (the three primary colors of red, green, and blue), and after the RGB light is modulated by the corresponding spatial light modulators 108, These RGB lights are color synthesized and projected.

  In such a color display image display apparatus, it is necessary to perform color balance (white balance) adjustment for adjusting the proportion of RGB light. Such color balance adjustment is performed by adjusting the magnitude of the electrical signal that controls each of the RGB spatial light modulators 108. That is, if the electrical signal applied to the spatial light modulator 108 is increased, the amount of light that is modulated and reflected (or transmitted) by the spatial light modulator 108 increases.

  For example, when the color temperature is set high, the RG electrical signal is reduced so that the modulation amount in the spatial light modulation element 108 of RG is suppressed so that the amount of RG light is relatively smaller than B. When the color temperature is set to be low, the BG electrical signal is reduced to suppress the modulation amount in the BG spatial light modulator 108 so that the amount of BG light is relatively small with respect to R.

  By the way, Patent Document 1 describes a technique for adjusting the luminance of a display image by controlling the amount of light emitted from a light source in accordance with the average luminance of the display image in the image display device as described above.

  Patent Document 2 describes a technique for adjusting the luminance of a display image using light amount adjustment by an optical aperture instead of changing the light emission amount of a light source in the image display device as described above. Yes. This image display device includes a variable aperture stop that blocks a part of the light beam in the illumination optical system and controls the cross-sectional area of the light beam. This variable aperture stop is configured by movably arranging a pair of light shielding plates that shield light beams in the illumination optical system, and the brightness of the display image can be adjusted by moving these light shielding plates. ing. In this image display device, the user can adjust the brightness of the display image according to the brightness of the usage environment.

JP-A-5-66501 JP 2002-23106 A

  By the way, in the image display device described in Patent Document 1, when a discharge lamp such as an ultra-high pressure mercury lamp is used as a light source, there is a possibility of adversely affecting the life of the light source and the light emission efficiency by controlling the amount of emitted light. For this reason, the amount of emitted light cannot be changed greatly, and the control amount is limited.

  In the above-described conventional image display device, the polarization beam splitter 109, the wave plate 111, and the spatial light modulator 108 each have an incident angle dependency, which is optimal for a light beam having a small incident angle. Although polarization modulation can be performed, there is a possibility that optimum polarization modulation cannot be performed for a light beam having a large incident angle. The pretilt of the spatial light modulator 108 and the oblique light with respect to the polarization beam splitter 109 are not completely compensated by the wave plate 111. As described above, when the light component in the oblique direction with respect to the spatial light modulator 108 is large, the contrast of the display image deteriorates.

  On the other hand, in an image display device, it is required to reduce the size of the device and increase the brightness of a projected display image. Therefore, in these image display devices, in order to illuminate the spatial light modulation element 108 with a short optical path using a wider range of light, the diameter of the illumination light in the illumination optical system 103 is increased to increase the illumination optical system 103. There is a desire to reduce the F value of the.

  As the F value of the illumination optical system 103 is decreased, the illumination light can be brightened and the brightness of the display image can be improved, but the light component in the oblique direction with respect to the spatial light modulator 108 increases. That is, as shown in FIG. 24, the smaller the F value of the illumination optical system 103 or the imaging optical system 110, the higher the brightness of the display image, but the lower the contrast, and the F value of the illumination optical system 103 etc. The larger the value, the higher the contrast of the displayed image, but the lower the luminance. Thus, increasing the brightness of the display image and increasing the contrast have a contradictory relationship with respect to the F value of the illumination optical system 103 and the like.

  Therefore, in the image display device described in Patent Document 2, if a high-brightness display image is to be obtained, the contrast is deteriorated, and if an attempt is made to suppress the deterioration of the contrast of the display image, sufficient brightness is obtained. The display image cannot be obtained.

  Further, in the image display device described in Patent Document 1, even if the luminance of the display image is adjusted, the contrast is not improved.

  Therefore, the present invention is proposed in view of the above-described circumstances, and it is possible to improve the contrast while suppressing a decrease in the brightness of the display image, and it is possible to improve the brightness while suppressing the decrease in the contrast. An object of the present invention is to provide an image display device that can obtain a display image.

  In order to solve the above-described problems and achieve the above object, an image display device according to the present invention has any one of the following configurations.

[Configuration 1]
The illumination light emitted from the light source is linearly polarized by the illumination optical system, and a plurality of secondary or tertiary light source images are formed on the spatial light modulation element by the illumination optical system, and the spatial light modulation element is superimposed. In an image display device that illuminates and the optical path of the illumination light polarized and modulated in the spatial light modulation element is separated by the polarization separation element according to the polarization direction, and the illumination light separated from the optical path is imaged by the projection optical system The optical system from the light source to the projection optical system is characterized by comprising diaphragm means for increasing the F value in directions other than the polarization direction of illumination light incident on the spatial light modulation element and the direction orthogonal thereto. To do.

[Configuration 2]
In the image display device having the configuration 1, the diaphragm means is a variable diaphragm having an opening for allowing the light beam to pass therethrough, blocking the light beam at a portion other than the opening, and the area of the opening being variable. It is what.

[Configuration 3]
In the image display device having the configuration 1 or the configuration 2, the stop means is provided in the illumination optical system or the projection optical system.

[Configuration 4]
In the image display device having the configuration 2 or the configuration 3, the diaphragm means supports the four light shielding plates that can move forward and backward from four directions with respect to the optical path of the illumination light, and supports these four light shielding plates. A moving operation mechanism that moves the light shielding plate in synchronization with the moving operation mechanism and a driving unit that drives the moving operation mechanism are provided.

  In this image display device, the aperture area of the diaphragm means can be automatically changed according to the brightness of the use environment.

  In the image display device according to the present invention, in the optical system from the light source to the projection optical system, the diaphragm for increasing the F value in directions other than the polarization direction of the illumination light incident on the spatial light modulation element and the direction orthogonal thereto. Therefore, the diaphragm means can block the illumination light in the region where the contrast is deteriorated in the second lens array, and can improve the contrast while suppressing the decrease in the luminance of the display image. . Further, in this image display device, it is possible to obtain a display image with high brightness while suppressing a decrease in contrast.

  In this image display device, the aperture means is a variable aperture having a variable aperture area, so that the aperture area in the aperture means is changed according to the brightness of the use environment, and a display image with appropriate luminance is obtained. be able to.

  Further, in this image display apparatus, the diaphragm means can be provided either in the illumination optical system or in the projection optical system depending on the apparatus configuration.

  The diaphragm means includes four light shielding plates that are capable of advancing and retreating from four directions with respect to the optical path of the illumination light, a movement operation mechanism that supports the four light shielding plates and moves the light shielding plates in synchronization with each other, Drive means for driving the moving operation mechanism, and in this case, the opening area of the diaphragm means is easily changed automatically according to the brightness of the use environment. be able to.

  That is, the present invention provides an image display device that can improve the contrast while suppressing a decrease in luminance of the display image, and obtain a high-luminance display image while suppressing a decrease in contrast. It can be provided.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, an image display device according to an embodiment of the invention will be described in detail with reference to the drawings.

  FIG. 1 is a side view showing a configuration of an image display apparatus according to an embodiment of the present invention.

  As shown in FIG. 1, the image display apparatus includes a light source 1 and a reflector 2 that reflects light emitted from the light source 1 in the direction of the optical axis L0. As the light source 1, a light source that emits white light such as a high-pressure mercury lamp or a metal halide lamp is used. The reflector 2 has a rotating paraboloidal reflecting surface with the optical axis L0 as an axis, reflects the light emitted from the light source 1 by the reflecting surface, and emits it as illumination light parallel to the optical axis L0.

  This illumination light is incident on the first lens array (fly eye lens) 3 constituting the illumination optical system. The illumination light that has passed through the first lens array 3 is incident on the second lens array (fly eye lens) 4. Between the first lens array 3 and the second lens array 4, a variable aperture stop 5 serving as a stop means is provided.

  The first and second lens arrays 3 and 4 are similar to the liquid crystal light valves 12, 18, and 21, which are spatial light modulation elements described later, so that the reflector 2 spatially divides the aperture from which the light beam is emitted. A plurality of shaped lens cells are two-dimensionally arranged. The first lens array 3 condenses illumination light on the lens cells of the second lens array 4 respectively corresponding to the lens cells, and the lens cells of the first lens array 3 are placed on the second lens array 4. The same number of secondary light source images are formed.

  For each lens cell, the second lens array 4 makes the image of the lens cell opening of the corresponding first lens array 3 coincide with the incident surface of the liquid crystal light valves 12, 18, 21, and the first lens array 3. The lens cells are overlapped on the incident surfaces of the liquid crystal light valves 12, 18, and 21.

  FIG. 2 is a front view showing the positional relationship between the variable aperture stop and the second lens array.

  As shown in FIG. 2, the variable aperture stop 5 can move and operate four light shielding plates 5a, 5b, 5c, and 5d that shield a part of the light flux between the first and second lens arrays 3 and 4. By arranging and arranging these light shielding plates 5a, 5b, 5c, 5d, the contrast and brightness of the display image by this image display device can be adjusted. The variable aperture stop 5 is disposed in the vicinity of the second lens array 4 where the secondary light source image is formed.

  The variable aperture stop 5 is configured to shield the illumination light transmitted through the four corners on the diagonal line of the second lens array 4 by the light shielding plates 5a, 5b, 5c, and 5d, and these light shielding plates 5a, 5b, A region other than 5c and 5d is an opening in the variable aperture stop 5.

  The illumination light emitted from the second lens array 4 is incident on the cross dichroic mirror 8 through the PS combiner 6 and the overlapping lens 7 as shown in FIG.

  The PS combiner 6 is an optical element having a flat plate shape in which a plurality of polarization beam splitters are arranged in parallel, and emits light with the polarization direction of incident light aligned in a certain direction. The superposing lens 7 makes the center of the image of each lens cell of the first lens array 4 coincide with the center of the liquid crystal light valve 12, 18, 21 so that the image of each lens cell of the first lens array 4 is the liquid crystal light. The valves 12, 18, and 21 are overlapped on the display surface.

  The cross dichroic mirror 8 separates the incident illumination light into an R (red) component, a G (green) component, and a B (blue) component. The R component light that has passed through the cross dichroic mirror 8 passes through the mirror 9 and the relay lens 10, passes through the polarization beam splitter 11 serving as a polarization separation element, and enters the red liquid crystal light valve 12. The red liquid crystal light valve 12 reflects and modulates the incident R component light according to the red component of the display image. The polarization-modulated reflected light is reflected by the polarization beam splitter 11 and enters the color synthesis prism 13 from one side surface portion.

  On the other hand, the G component light and the B component light that have passed through the cross dichroic mirror 8 are incident on the dichroic mirror 15 via the mirror 14. The dichroic mirror 15 separates the incident G component light and B component light into G component light and B component light. The G component light reflected by the dichroic mirror 15 passes through the relay lens 16, passes through the polarization beam splitter 17 serving as a polarization separation element, and enters the green liquid crystal light valve 18. The green liquid crystal light valve 18 reflects and modulates the incident G component light according to the green component of the display image. The polarization-modulated reflected light is reflected by the polarization beam splitter 17 and enters the color synthesis prism 13 from the rear surface portion.

  Then, the B component light transmitted through the dichroic mirror 15 passes through the relay lens 19, passes through the polarization beam splitter 20 serving as a polarization separation element, and enters the blue liquid crystal light valve 21. The blue liquid crystal light valve 21 reflects the incident B component light by modulating the polarization according to the blue component of the display image. The polarization-modulated reflected light is reflected by the polarization beam splitter 20 and enters the color synthesis prism 13 from the other side surface portion.

  The color combining prism 13 combines the R component light incident from one side surface portion, the G component light incident from the rear surface portion, and the B component light incident from the other side surface portion, and emits them from the front surface portion. The illumination light emitted from the color synthesizing prism 13 is incident on a projection lens 22 serving as a projection optical system. The projection lens 22 projects incident illumination light onto a screen (not shown), forms an image, and displays an image.

  By the way, in this image display apparatus, the variable aperture stop 5 is configured so that the optical system extending from the light source 1 to the projection lens 22 is other than the polarization direction of illumination light incident on the liquid crystal light valves 12, 18, and 21 and the direction orthogonal thereto. It has a function to increase the F value in the direction of. That is, the polarization direction of the illumination light incident on each of the liquid crystal light valves 12, 18, and 21 is a direction corresponding to the vertical direction of the display image in this embodiment. Since the variable aperture stop 5 shields the illumination light transmitted through the four corners on the diagonal line of the second lens array 4 by the light shielding plates 5a, 5b, 5c, 5d, the polarization direction of the illumination light and the direction orthogonal thereto. The F value in the direction other than the direction to be increased is increased.

  FIG. 3 is a front view showing the intensity distribution of illumination light for each lens cell in the second lens array.

In the second lens array 4 of the image display device, the intensity distribution of the illumination light for each lens cell is a substantially concentric distribution as shown in FIG.
FIG. 4 is a front view showing the distribution of contrast for each lens cell in the second lens array.

  On the other hand, the contrast of each lens cell in the second lens array 4 is as shown in FIG. 4 in the four corners in the diagonal direction of the second lens array 4, that is, the polarization direction of the illumination light and this. It has deteriorated in directions other than the direction orthogonal to the direction. Therefore, in this image display device, by contrasting the four corners in the diagonal direction of the second lens array 4, it is possible to improve the contrast while minimizing the decrease in the luminance of the display image.

  FIG. 5 is a front view showing the brightness and contrast of the display image in the aperture shape of this image display device and the conventional aperture shape.

  In the variable aperture stop 5 in this image display device, for example, as shown in FIG. 5A, the contrast can be 1800: 1 while maintaining the luminance of the display image at 600 lm (lumen). . On the other hand, as shown in FIG. 5B, in the conventional image display device using the diaphragm 50 having a circular opening, the contrast is maintained even if the luminance of the display image is reduced to 500 lm (lumen). Becomes 1600: 1.

  As described above, in this image display device, the contrast can be improved while minimizing the decrease in the brightness of the display image, and the brightness of the display image is improved while minimizing the deterioration of the contrast. Can be made.

[First example of configuration of variable aperture stop]
FIG. 6 is a front view showing the configuration of the variable aperture stop.

  As shown in FIG. 6, the variable aperture stop 5 in this image display device has four light shielding plates 5a, 5b, 5c and 5d arranged at the four corners of the second lens array 4. Guide pins 23 project from both surfaces of each light shielding plate 5a, 5b, 5c, 5d. The guide pins 23 on one surface of each light shielding plate 5a, 5b, 5c, 5d are respectively fitted in guide grooves 24 provided in a guide plate 29 serving as a fixed portion in the image display device. These guide grooves 24 are formed radially with the central portion of the second lens array 4 as the center, and the light shielding plates 5a, 5b, 5c, and 5d follow the guide grooves 24 to form the second lens. The array 4 is movable in the diagonal direction.

  A guide pin 23 on the other surface of each light shielding plate 5 a, 5 b, 5 c, 5 d is a cam groove 26 provided in a cam plate 25 arranged so as to be rotatable around the central portion of the second lens array 4. Respectively. That is, each light shielding plate 5a, 5b, 5c, 5d is supported by each guide groove 24 and each cam groove 26. The cam plate 25 is formed in an annular shape and rotates around the second lens array 4. The cam groove 26 of the cam plate 25 is formed in a spiral shape. Therefore, when the cam plate 25 is rotated, the light shielding plates 5a, 5b, 5c, and 5d are operated to move in synchronization with each other so that the guide grooves 24 and the cam grooves 26 intersect with each other. That is, each guide groove 24 and the cam plate 25 constitute a moving operation mechanism that supports and moves the light shielding plates 5a, 5b, 5c, and 5d.

  The outer peripheral edge portion of the cam plate 25 is a gear portion 25a. The gear portion 25a meshes with a transmission gear 28 to which the driving force of the motor 27 serving as driving means is transmitted. That is, the cam plate 25 is rotated by the driving force of the motor 27 and moves the light shielding plates 5 a, 5 b, 5 c, 5 d in the diagonal direction of the second lens array 4.

  FIG. 7 is a front view showing a state in which the opening of the variable aperture stop is open.

  FIG. 8 is a front view showing a state in which the opening of the variable aperture stop is closed.

  The variable aperture stop 5 changes the area of the opening as shown in FIGS. 7 and 8 by moving the light shielding plates 5a, 5b, 5c, and 5d as described above.

  In order to control the rotation angle of the cam plate 25, the rotation angle of the cam plate 25 may be detected by a photo sensor or the like, and the drive of the motor 27 may be controlled based on the detection result. Further, as the motor 27, a stepping motor whose driving rotation angle can be easily controlled may be used.

[Second example of configuration of variable aperture stop]
FIG. 9 is a perspective view showing a second example of the configuration of the variable aperture stop.

  As shown in FIG. 9, the variable aperture stop 5 in this image display device includes four light shielding plates 5 a, 5 b, 5 c, 5 d arranged at the four corners of the second lens array 4, and a pair of rotating shafts 30. , 31 may be rotatably supported. In the variable aperture stop 5, the light shielding plates 5 a and 5 b on one side are supported by one rotating shaft 30, and the light shielding plates 5 c and 5 d on the other side are supported by the other rotating shaft 31. Each of the light shielding plates 5 a, 5 b, 5 c, 5 d can be rotated about the rotation shafts 30, 31, and can move in the contact / separation direction with respect to the second lens array 4. In other words, each of the rotary shafts 30 and 31 constitutes a moving operation mechanism that supports the light shielding plates 5a, 5b, 5c, and 5d and moves them.

  And the pinion gears 32 and 33 are each attached to the one end side of the rotating shafts 30 and 31 which support each light shielding plate 5a, 5b, 5c, 5d. One pinion gear 32 meshes with a first rack gear 34. The second rack gear 35 is engaged with the other pinion gear 33. The rack gears 34 and 35 mesh with gears attached to the drive shaft of the motor 27 serving as drive means. That is, the rack gears 34 and 35 are moved and operated by the driving force of the motor 27, and the respective light shielding plates 5a, 5b, 5c, and 5d are moved to the second lens array 4 through rotation of the rotary shafts 30 and 31. Rotate in the direction of contact with and away from.

  In the variable aperture stop 5, a stepping motor that can easily control the drive rotation angle is used as the motor 27, and the motor 27 is controlled by a control circuit 36.

  FIG. 10 is a perspective view showing still another example of the configuration of the variable aperture stop.

  Further, in this variable aperture stop 5, in order to control the rotation angle of each rotary shaft 30, 31, the position of each rack gear 34, 35 is detected by a photo sensor, encoder switch 37, etc. as shown in FIG. Then, the drive of the motor 27 may be controlled via the detection circuit 38 and the control circuit 36 based on the detection result.

  FIG. 11 is a front view showing a state in which the aperture is open.

  FIG. 12 is a front view showing a state where the diaphragm is closed.

  The variable aperture stop 5 changes the area of the opening as shown in FIGS. 11 and 12 by rotating the light shielding plates 5a, 5b, 5c, and 5d as described above.

[Third example of configuration of variable aperture stop]
FIG. 13 is a perspective view showing a third example of the configuration of the variable aperture stop.

  As shown in FIG. 13, the variable aperture stop 5 in this image display device includes four light shielding plates 5a, 5b, 5c, and 5d arranged at the four corners of the second lens array 4, and two pairs of rotating shafts. It may be configured to be rotatably supported by 30a, 31a, 30b, 31b. In the variable aperture stop 5, the first light shielding plate 5a is supported by the first rotation shaft 30a, the second light shielding plate 5b is supported by the second rotation shaft 30b, and the third light shielding plate 5c is the first light shielding plate 5c. 3 is supported by the third rotating shaft 31b, and the fourth light shielding plate 5d is supported by the fourth rotating shaft 31a. Each of the light shielding plates 5a, 5b, 5c, 5d is rotatable about the rotation shafts 30a, 31a, 30b, 31b, and is movable in the contact / separation direction with respect to the second lens array 4.

  That is, each rotary shaft 30a, 31a, 30b, 31b constitutes a moving operation mechanism that supports and moves the light shielding plates 5a, 5b, 5c, 5d. In the variable aperture stop 5, the first rotating shaft 30 a and the fourth rotating shaft 31 a are parallel to each other and are positioned in the diagonal direction of the second lens array 4. The two rotation shafts 30 b and the third rotation shaft 31 b are parallel to each other and are positioned in the diagonal direction of the second lens array 4 to form a pair.

  Pinion gears 32a and 33a are attached to one end sides of the first rotating shaft 30a and the fourth rotating shaft 31a forming a pair for supporting the first and fourth light shielding plates 5a and 5d, respectively. One pinion gear 32a meshes with the first rack gear 34a. Further, the second rack gear 35a meshes with the other pinion gear 33a. Each rack gear 34a, 35a meshes with a gear attached to the drive shaft of the first motor 27a serving as the drive means. That is, the rack gears 34a and 35a are moved and operated by the driving force of the first motor 27a, and the first and fourth light shielding plates 5a and 5d are moved to the second through rotating the rotary shafts 30a and 31a. The lens array 4 is rotated in the contact / separation direction.

  In addition, pinion gears 32b and 33b are respectively attached to one end sides of the second rotating shaft 30b and the third rotating shaft 31b that form a pair supporting the second and third light shielding plates 5b and 5c. A third rack gear 34b meshes with one pinion gear 32b. The fourth rack gear 35b meshes with the other pinion gear 33b. Each rack gear 34b, 35b meshes with a gear attached to the drive shaft of the second motor 27b serving as the drive means. That is, the rack gears 34b and 35b are moved and operated by the driving force of the second motor 27b, and the second and third light shielding plates 5b and 5c are moved to the second through rotating the rotary shafts 30b and 31b. The lens array 4 is rotated in the contact / separation direction.

  In the variable aperture stop 5, stepping motors that can easily control the drive rotation angle are used as the motors 27 a and 27 b, and these motors 27 a and 27 b are controlled by a control circuit 36.

  FIG. 14 is a perspective view showing still another example of the configuration of the variable aperture stop.

  Further, in this variable aperture stop 5, in order to control the rotation angle of each rotary shaft 30a, 31a, 30b, 31b, as shown in FIG. 14, each rack gear 34a, 35a is provided by a photo sensor, an encoder switch 37 or the like. , 34b, 35b may be detected, and the driving of the motors 27a, 27b may be controlled via the detection circuit 38 and the control circuit 36 based on the detection result.

  FIG. 15 is a front view showing a state in which the aperture is open.

  FIG. 16 is a front view showing a state where the diaphragm is closed.

  The variable aperture stop 5 changes the area of the opening as shown in FIGS. 15 and 16 by rotating the light shielding plates 5a, 5b, 5c, and 5d as described above.

[Fourth example of configuration of variable aperture stop]
FIG. 17 is a perspective view showing a third example of the configuration of the variable aperture stop.

  As shown in FIG. 17, the variable aperture stop 5 in this image display device includes four light shielding plates 5a, 5b, 5c, and 5d arranged at the four corners of the second lens array 4, and two pairs of moving axes. You may comprise by supporting so that movement is possible by 30a, 31a, 30b, 31b. In the variable aperture stop 5, the first light shielding plate 5a is supported by the first moving shaft 30a, the second light shielding plate 5b is supported by the second moving shaft 30b, and the third light shielding plate 5c is the first light shielding plate 5c. 3 is supported by the third moving shaft 31b, and the fourth light shielding plate 5d is supported by the fourth moving shaft 31a. Each of the light shielding plates 5 a, 5 b, 5 c, 5 d can be moved by these moving shafts 30 a, 31 a, 30 b, 31 b and can be moved in the diagonal direction of the second lens array 4.

  That is, each moving shaft 30a, 31a, 30b, 31b constitutes a moving operation mechanism that supports each light shielding plate 5a, 5b, 5c, 5d and moves. In the variable aperture stop 5, the first moving shaft 30 a and the fourth moving shaft 31 a are parallel to each other and are positioned in the diagonal direction of the second lens array 4. The two moving shafts 30b and the third moving shaft 31b are parallel to each other and are positioned in the diagonal direction of the second lens array 4 to form a pair.

  One end side of the first moving shaft 30a that supports the first light shielding plate 5a is attached to the first rack gear 34a. One end side of the fourth moving shaft 31a that supports the fourth light shielding plate 5d is attached to the second rack gear 35a. The rack gears 34a and 35a mesh with gears attached to the drive shaft of the first motor 27a serving as drive means. That is, the rack gears 34a and 35a are moved by the driving force of the first motor 27a, and the first and fourth light shielding plates 5a and 5d are moved to the second through moving the moving shafts 30a and 31a. The lens array 4 is moved in a diagonal direction.

  One end side of the second moving shaft 30b that supports the second light shielding plate 5b is attached to the third rack gear 34b. One end side of the third moving shaft 31b that supports the third light shielding plate 5c is attached to the fourth rack gear 35b. The rack gears 34b and 35b mesh with gears attached to the drive shaft of the second motor 27b serving as drive means. That is, the rack gears 34b and 35b are moved by the driving force of the second motor 27b, and the second and third light shielding plates 5b and 5c are moved to the second through moving the moving shafts 30b and 31b. The lens array 4 is moved in a diagonal direction.

  In the variable aperture stop 5, stepping motors that can easily control the drive rotation angle are used as the motors 27 a and 27 b, and these motors 27 a and 27 b are controlled by a control circuit 36.

  FIG. 18 is a perspective view showing still another example of the configuration of the variable aperture stop.

  Further, in this variable aperture stop 5, in order to control the rotation angle of each moving shaft 30a, 31a, 30b, 31b, as shown in FIG. 18, each rack gear 34a, 35a is provided by a photo sensor, an encoder switch 37 or the like. , 34b, 35b may be detected, and the driving of the motors 27a, 27b may be controlled via the detection circuit 38 and the control circuit 36 based on the detection result.

  FIG. 19 is a front view showing a state in which the aperture is open.

  FIG. 20 is a front view showing a state in which the diaphragm is closed.

  The variable aperture stop 5 changes the area of the opening as shown in FIGS. 19 and 20 by rotating the light shielding plates 5a, 5b, 5c, and 5d as described above.

  As described above, the image display apparatus includes the variable aperture stop 5 having a variable aperture area, so that priority is given to the contrast of the display image according to the video source of the display image, the viewing environment, and the like. Effective adjustment can be performed by selecting a mode and a mode giving priority to luminance.

  Further, the variable aperture stop 5 may be disposed in the vicinity of the entrance pupil of the projection lens 22 which is a conjugate position with the second lens array 4. Also in this configuration, by adjusting the variable aperture stop 5, a mode that prioritizes the contrast of the display image and a mode that prioritizes the brightness are selected according to the video source of the display image, the viewing environment, and the like. Adjustments can be made.

FIG. 1 is a side view showing a configuration of an image display apparatus according to an embodiment of the present invention. It is a front view which shows the positional relationship of the variable aperture stop and 2nd lens array in the said image display apparatus. It is a front view which shows intensity distribution of the illumination light for every lens cell in the 2nd lens array in the said image display apparatus. It is a front view which shows distribution of contrast for every lens cell in the 2nd lens array in the said image display apparatus. It is a front view which shows the brightness | luminance and contrast of the display image in the aperture shape in the said image display apparatus, and the conventional aperture shape. It is a front view which shows the 1st example of a structure of the variable aperture stop in the said image display apparatus. It is a front view which shows the state in which the opening part in the variable aperture stop in the said image display apparatus is open. It is a front view which shows the state in which the opening part in the variable aperture stop in the said image display apparatus is closed. It is a perspective view which shows the 2nd example of a structure of the variable aperture stop in the said image display apparatus. It is a perspective view which shows the further another example of a structure of the variable aperture stop in the said image display apparatus. It is a top view which shows the state in which the aperture_diaphragm | restriction is open in the said image display apparatus. It is a top view which shows the state in which the aperture_diaphragm | restriction is closed in the said image display apparatus. It is a perspective view which shows the 3rd example of a structure of the variable aperture stop in the said image display apparatus. It is a perspective view which shows the further another example of a structure of the variable aperture stop in the said image display apparatus. It is a top view which shows the state in which the aperture_diaphragm | restriction is open in the said image display apparatus. It is a top view which shows the state in which the aperture_diaphragm | restriction is closed in the said image display apparatus. It is a perspective view which shows the 4th example of a structure of the variable aperture stop in the said image display apparatus. It is a perspective view which shows the further another example of a structure of the variable aperture stop in the said image display apparatus. It is a top view which shows the state in which the aperture_diaphragm | restriction is open in the said image display apparatus. It is a top view which shows the state in which the aperture_diaphragm | restriction is closed in the said image display apparatus. It is a side view showing a schematic configuration of a so-called “lens array type” illumination optical system in a conventional image display device. It is a side view which shows schematic structure of the projection optical system in the conventional image display apparatus. It is a side view which shows the optical path of the illumination light before and behind the spatial light modulation element in the conventional image display apparatus. It is a graph which shows the relationship between the brightness | luminance and contrast of a display image in the conventional image display apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Light source 3 1st lens array 4 2nd lens array 5 Variable aperture stop 6 PS combiner 11, 17, 20 Polarizing beam splitter 12 Liquid crystal light valve for red 18 Liquid crystal light valve for green 21 Liquid crystal light valve for blue 22 Projection lens 23 Guide pin 24 Guide groove 25 Cam plate 26 Cam groove 27 Motor

Claims (4)

The illumination light emitted from the light source is linearly polarized by the illumination optical system, and a plurality of secondary or tertiary light source images are formed on the spatial light modulation element by the illumination optical system. The optical path of the illumination light polarization-modulated by the spatial light modulation element is separated according to the polarization direction by the polarization separation element, and the illumination light separated from the optical path is imaged by the projection optical system. In an image display device,
The optical system from the light source to the projection optical system is provided with a diaphragm means for increasing the F value in directions other than the polarization direction of illumination light incident on the spatial light modulation element and the direction orthogonal thereto. A characteristic image display device. 2. The image according to claim 1, wherein the diaphragm means is a variable diaphragm having an opening for allowing a light beam to pass therethrough, blocking the light beam at a portion other than the opening, and the area of the opening being variable. Display device. The image display apparatus according to claim 1, wherein the diaphragm unit is provided in an illumination optical system or a projection optical system. The diaphragm means includes four light shielding plates that are capable of moving back and forth in four directions with respect to the optical path of the illumination light, and a movement operation mechanism that supports the four light shielding plates and moves the light shielding plates synchronously. An image display apparatus according to claim 2, further comprising a driving unit that drives the moving operation mechanism.