JP2013246282A - Stereoscopic image display system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a stereoscopic image display system capable of providing stereoscopic vision even when image light is randomly polarized.SOLUTION: Each liquid crystal shutter 55 of liquid crystal shutter glasses 50 comprises a glass side 1/4 waveform plate 51, an incident side polarizing plate 52, a liquid crystal element 53, and an exit side polarizing plate 54. The incident side polarizing plate 52 has an incident side absorption axis, which is a polarization axis extending in a predetermined first direction, and transmits a component of incident light, exiting from the glass side 1/4 wavelength plate 51, that is in parallel with an incident side transmission axis which is perpendicular to the incident side absorption axis. The liquid crystal element 53 outputs the incident light coming from the incident side polarizing plate 52 after changing the polarization direction thereof according to the presence or absence of voltage applied thereto. The exit side polarizing plate 54 has an exit side absorption axis, which is a polarization axis extending in a second direction perpendicular to the first direction, and transmits a component of incident light, exiting from the liquid crystal element 53, that is in parallel with an exit side transmission axis which is perpendicular to the exit side absorption axis.

Description

  The present invention relates to a stereoscopic video display system that realizes stereoscopic viewing of video displayed by a video display device.

  A method for realizing a stereoscopic view by applying a liquid crystal element as an optical shutter has been proposed. For example, in a liquid crystal television device (hereinafter sometimes referred to as “liquid crystal television”), an image displayed on the screen is time-divided, and a left-eye image and a right-eye image are respectively transmitted to the user's left eye and right eye. There is a method of switching and sending with a shutter (for example, see Patent Document 1). Here, “image” corresponds to “video”.

  In the stereoscopic television disclosed in Patent Document 1, optical shutters provided in the left eye part and the right eye part of stereoscopic glasses are provided for each field of the left image and the right image of the subject displayed on the television screen, or The image of the subject can be recognized three-dimensionally by alternately opening and closing in synchronization with the switching cycle for each field. In the stereoscopic television disclosed in Patent Document 1, a pair of polarizing plates arranged in parallel and a twisted nematic liquid crystal cell are used as optical shutters for left and right eyes, and are synchronized with image switching. Driving means for alternately supplying a predetermined AC voltage to the liquid crystal cells constituting the left-eye and right-eye optical shutters.

  Using the technology disclosed in Patent Document 1, when viewing a liquid crystal television with linearly polarized image light or when the projector image is emitted with linearly polarized light, it is displayed on a silver screen that maintains the polarization state. When observing a projected image, the brightness can be maintained, but there is a problem that the brightness decreases when the user tilts his / her neck.

  For example, Patent Document 2 discloses a method for suppressing a decrease in brightness when the user tilts his / her neck. In the image display observation system disclosed in Patent Document 2, polarized light of a direct-view type liquid crystal television is emitted as circularly polarized light using a quarter-wave plate, and an optical modulator that functions as stereoscopic glasses A quarter wave plate for converting circularly polarized light into linearly polarized light is provided in front of the liquid crystal surface. This suppresses the occurrence of a decrease in brightness when the user tilts his / her neck.

JP-A-61-227498 (FIG. 1) JP2011-75745A (paragraph 0078, FIG. 6)

  The technique disclosed in Patent Document 2 described above is effective only when the image light is circularly polarized light. Even if the image light is emitted from the projector as circularly polarized light, the polarization state may be disturbed by the white screen and may be randomly polarized light. In this way, when the image light is randomly polarized, the stereoscopic glasses do not have the function of an optical shutter not only for external light such as a fluorescent lamp but also for the image light, so that stereoscopic viewing can be realized. There is a problem that it cannot be done. This problem also exists when a projector using a non-polarized digital mirror device (abbreviation: DMD) as a light valve is used.

  An object of the present invention is to provide a stereoscopic video display system capable of realizing stereoscopic viewing even when video light is randomly polarized.

  A stereoscopic video display system according to the present invention includes a video display device that alternately displays a right-eye video and a left-eye video for forming a stereoscopically recognizable video, and a video displayed on the video display device. Liquid crystal shutter glasses that are driven by the video display device, wherein the video display device alternately emits video light corresponding to the right-eye video and video light corresponding to the left-eye video, and the video display A screen on which image light emitted from the element is projected, and a projection optical system that projects the image light emitted from the image display element onto the screen, the liquid crystal shutter glasses include incident circularly polarized light, A spectacle-side quarter-wave plate that converts linearly polarized light in a predetermined polarization direction and an incident-side absorption axis that is a polarization axis extending in a predetermined first direction are emitted from the spectacle-side quarter-wave plate. Incident Among the light, an incident-side polarizing plate that transmits light in a direction parallel to the incident-side transmission axis perpendicular to the incident-side absorption axis, and whether light incident from the incident-side polarizing plate is applied with voltage. A liquid crystal element that emits light with a polarization direction changed in response to the light source, and an emission-side absorption axis that is a polarization axis extending in a second direction perpendicular to the first direction. Of these, an emission-side polarizing plate that transmits light in a direction parallel to the emission-side transmission axis perpendicular to the emission-side absorption axis is provided.

  According to the stereoscopic image display system of the present invention, the liquid crystal shutter glasses include the incident side polarizing plate in the front stage of the liquid crystal element. As a result, even when the image light incident on the liquid crystal shutter glasses from the screen is randomly polarized, the image light having a specific polarization direction can be incident on the liquid crystal element. The polarization direction can be changed according to the presence or absence of application, and the light can be emitted. Therefore, since crosstalk in which the right-eye video and the left-eye video are mixed can be prevented, stereoscopic viewing can be realized even when the video light is randomly polarized.

1 is a perspective view showing a configuration of a stereoscopic video display system 100 of a prerequisite technology that is a prerequisite of the present invention. 1 is a perspective view showing a configuration of a stereoscopic video display system 1 according to a first embodiment of the present invention. 1 is a block diagram illustrating a configuration of a stereoscopic video display system 1 according to a first embodiment of the present invention. It is a perspective view which shows the structure of the three-dimensional video display system 2 which is the 2nd Embodiment of this invention.

<Prerequisite technology>
FIG. 1 is a perspective view showing a configuration of a stereoscopic image display system 100 as a premise technique as a premise of the present invention. The stereoscopic video display system 100 includes a video display device 10 and liquid crystal shutter glasses 30. FIG. 1 shows a case where a projection type video display device is used as the video display device 10.

  The video display device 10 includes a video display element 11, a device-side quarter-wave plate 12, a projection optical system 13, and a white screen 14. The projection optical system 13 is provided on the optical path between the image display element 11 and the white screen 14. The apparatus-side quarter-wave plate 12 is provided on the optical path between the image display element 11 and the projection optical system 13.

  The liquid crystal shutter glasses 30 are stereoscopic glasses for stereoscopically viewing an image displayed on the white screen 14. The liquid crystal shutter glasses 30 are used by being worn by the user. The liquid crystal shutter glasses 30 include a liquid crystal shutter 34 and a frame (not shown) that supports the liquid crystal shutter 34. The liquid crystal shutter 34 includes a spectacle side quarter-wave plate 31, a liquid crystal element 32, and a polarizing plate 33. The glasses side quarter wavelength plate 31, the liquid crystal element 32, and the polarizing plate 33 are provided in this order from the white screen 14 side toward the user side.

  The video display element 11 functions as a light valve that modulates and emits light from the light source. The video display element 11 is realized by a liquid crystal display element, for example. The liquid crystal display element includes a liquid crystal layer, and a transparent electrode and a transparent substrate that face each other with the liquid crystal layer interposed therebetween.

  A video signal is input to the video display element 11. The video display element 11 emits linearly polarized video light 21 corresponding to the input video signal. The apparatus-side quarter-wave plate 12 has a slow axis. The slow axis is inclined 45 ° clockwise with respect to the traveling direction of the light with respect to the vertical direction which is the polarization direction of the linearly polarized image light 21 emitted from the image display element 11. In FIG. 2, the slow axis of the device-side quarter-wave plate 12 is indicated by a thin double arrow.

  The apparatus-side quarter-wave plate 12 converts linearly polarized image light 21 emitted from the image display element 11 into circularly polarized image light 22 and emits it. The projection optical system 13 enlarges and projects the image represented by the circularly polarized image light 22 emitted from the apparatus-side quarter-wave plate 12 onto the white screen 14.

  Circularly polarized image light 23 corresponding to the enlarged image is incident on the white screen 14. Here, the “white screen” refers to a screen that disturbs the polarization state of incident light. The white screen 14 is realized by, for example, a screen in which a white paint is applied to the projection surface. The circularly polarized video light 23 that has entered the white screen 14 is disturbed in its polarization state, converted into a randomly polarized video light 41 and reflected.

  The randomly polarized image light 41 reflected by the white screen 14 is incident on the glasses-side quarter-wave plate 31 of the liquid crystal shutter glasses 30. When the randomly polarized image light 41 is incident, the glasses-side quarter-wave plate 31 emits the randomly polarized image light 42. That is, the randomly polarized image light 41 incident on the glasses-side quarter-wave plate 31 passes through the glasses-side quarter-wave plate 31 and is emitted as randomly-polarized image light 42. Randomly polarized image light 42 transmitted through the spectacle-side quarter-wave plate 31 enters the liquid crystal element 32.

  The liquid crystal element 32 rotates the polarization direction of incident light according to the presence or absence of voltage application. The liquid crystal element 32 does not rotate the polarization direction of incident light when a voltage is applied, and rotates the polarization direction of incident light when a voltage is not applied.

  When randomly polarized image light 42 is incident on the liquid crystal element 32, the image light 43 is emitted when no voltage is applied to the liquid crystal element 32, and is emitted when a voltage is applied to the liquid crystal element 32. All of the image light 44 is emitted as random polarized light. That is, the randomly polarized video light 42 incident on the liquid crystal element 32 is transmitted through the liquid crystal element 32 when a voltage is applied to the liquid crystal element 32 or not, and the randomly polarized video light 43 and 44 is applied. Is emitted.

  Randomly polarized video light 43 and 44 emitted from the liquid crystal element 32 enter the polarizing plate 33. The polarizing plate 33 transmits only the image light 45 having a predetermined polarization direction among the randomly polarized image lights 43 and 44 emitted from the liquid crystal element 32.

  As described above, in the three-dimensional image display system 100 of the base technology, the circularly polarized image light 23 incident on the white screen 14 is reflected as the randomly polarized image light 41, and the 1 / glass side 1 of the liquid crystal shutter glasses 30. The light enters the four-wave plate 31. The randomly polarized image light 41 is transmitted through the glasses-side quarter-wave plate 31 and enters the liquid crystal element 32 as randomly polarized image light 42.

  Randomly polarized video light 42 passes through the liquid crystal element 32 and is emitted as randomly polarized video light 43 and 44, whether or not a voltage is applied to the liquid crystal element 32. Shutter control, which is control for switching between transmission and non-transmission of light according to the presence or absence of voltage application, cannot be performed. Therefore, there is a problem in that stereoscopic video cannot be realized because the video for the right eye and the video for the left eye are mixed. Therefore, the stereoscopic image display system of the present invention employs the configuration shown in the following embodiments.

<First Embodiment>
FIG. 2 is a perspective view showing a configuration of the stereoscopic video display system 1 according to the first embodiment of the present invention. Since the stereoscopic video display system 1 of the present embodiment is similar in configuration to the stereoscopic video display system 100 of the base technology described above, the same reference numerals are assigned to corresponding parts, and common description is omitted. To do.

  The stereoscopic video display system 1 according to the present embodiment includes a video display device 10 and liquid crystal shutter glasses 50. The video display device 10 has the same configuration as the video display device 10 in the base technology, and includes a video display element 11, a device-side quarter-wave plate 12, a projection optical system 13, and a white screen 14. The liquid crystal shutter glasses 50 are stereoscopic glasses for stereoscopically viewing an image displayed on the white screen 14. The liquid crystal shutter glasses 30 are used by being worn by the user. The liquid crystal shutter glasses 50 include a liquid crystal shutter 55 and a later-described frame that supports the liquid crystal shutter 55. The liquid crystal shutter 55 includes a spectacle side quarter-wave plate 51, an incident side polarizing plate 52, a liquid crystal element 53, and an output side polarizing plate 54. The glasses-side quarter-wave plate 51, the incident-side polarizing plate 52, the liquid crystal element 53, and the outgoing-side polarizing plate 54 are provided in this order from the white screen 14 side toward the user side.

  Also in the present embodiment, similarly to the base technology, the randomly polarized video light 61 reflected by the white screen 14 is incident on the spectacle-side quarter-wave plate 51 of the liquid crystal shutter spectacles 50. The spectacle side quarter-wave plate 51 has a slow axis. The slow axis is inclined 45 ° clockwise with respect to the traveling direction of the light with respect to the longitudinal direction which is the polarization direction of the linearly polarized light 21 emitted from the image display element 11. In FIG. 2, the slow axis of the spectacle-side quarter-wave plate 51 is indicated by a thin double arrow.

  Similarly to the glasses-side quarter-wave plate 31 of the base technology, the spectacle-side quarter-wave plate 51 emits random-polarized video light 61 as random-polarized video light 62. That is, the randomly polarized image light 61 incident on the glasses-side quarter-wave plate 51 passes through the glasses-side quarter-wave plate 51 and is emitted as randomly-polarized image light 62. In the present embodiment, the randomly polarized image light 62 transmitted through the spectacle-side quarter-wave plate 51 is incident on the incident-side polarizing plate 52.

  The incident side polarizing plate 52 is provided on the optical path between the spectacle side quarter wavelength plate 51 and the liquid crystal element 53. The incident-side polarizing plate 52 has an absorption axis that is a polarization axis extending in a predetermined first direction. The absorption axis of the incident side polarizing plate 52 corresponds to the incident side absorption axis. In FIG. 2, the absorption axis of the incident side polarizing plate 52 is indicated by a thin double arrow.

  The incident-side polarizing plate 52 transmits only the image light 63 in the direction parallel to the transmission axis perpendicular to the absorption axis among the randomly polarized image light 62 transmitted through the glasses-side quarter-wave plate 51. The transmission axis of the incident side polarizing plate 52 is a polarization axis extending in the second direction perpendicular to the first direction. The transmission axis of the incident side polarizing plate 52 corresponds to the incident side transmission axis. The axial direction of the absorption axis and the transmission axis of the incident side polarizing plate 52 differ by 90 °. The video light 63 transmitted through the incident side polarizing plate 52 enters the liquid crystal element 53.

  The liquid crystal element 53 includes a liquid crystal layer, and a transparent electrode and a transparent substrate that face each other with the liquid crystal layer interposed therebetween. The liquid crystal element 53 rotates the polarization direction of incident light according to the presence or absence of voltage application. The liquid crystal element 53 does not rotate the polarization direction of incident light when a voltage is applied, and rotates the polarization direction of incident light when a voltage is not applied.

  When the image light 63 in a direction parallel to the transmission axis perpendicular to the absorption axis of the incident-side polarizing plate 52 is incident on the liquid crystal element 53, when the voltage is not applied, the polarization direction of the incident image light 63 is 90 °. Only the image light 64 having a different polarization direction is transmitted, and when a voltage is applied, the light of the image light 65 having the same polarization direction as that of the incident image light 63 is not transmitted. The light transmitted through the liquid crystal element 53 enters the output side polarizing plate 54.

  The output-side polarizing plate 54 has an absorption axis that is a polarization axis extending in a second direction perpendicular to the first direction. That is, the axial direction of the absorption axis of the exit-side polarizing plate 54 and the absorption axis of the incident-side polarizing plate 52 are different by 90 °. The absorption axis of the output side polarizing plate 54 corresponds to the output side absorption axis. In FIG. 2, the absorption axis of the exit-side polarizing plate 54 is indicated by a thin double arrow. The output side polarizing plate 54 transmits only the image light 66 in the direction parallel to the transmission axis perpendicular to the absorption axis of the output side polarizing plate 54. The transmission axis of the output side polarizing plate 54 corresponds to the output side transmission axis.

  FIG. 3 is a block diagram showing a configuration of the stereoscopic video display system 1 according to the first embodiment of the present invention. The stereoscopic video display system 1 includes the video display device 10 and the liquid crystal shutter glasses 50 as described above. The video display device 10 includes the video display element 11 shown in FIG. 2 described above, a display control unit 15 and a shutter control unit 16. In FIG. 3, for the sake of easy understanding, the illustration of the device-side quarter-wave plate 12, the projection optical system 13, and the white screen 14 in the configuration of the video display device 10 shown in FIG. 2 is omitted. Yes.

  The liquid crystal shutter glasses 50 include the liquid crystal shutter 55 shown in FIG. 2 and a frame 56 that supports the liquid crystal shutter 55. The liquid crystal shutter 55 includes a left-eye shutter 55a and a right-eye shutter 55b. Since the left-eye shutter 55a and the right-eye shutter 55b have the same configuration, only the one shutter is shown in FIG. 2, and the other shutter is not shown. In FIG. 2, the shutter 55 is shown in an exploded manner for easy understanding.

  The display control unit 15 includes a video signal for displaying the right-eye video (hereinafter sometimes referred to as “right-eye video signal”) and a video signal for displaying the left-eye video (hereinafter “left-eye video signal”). May be input). The display control unit 15 converts the input video signal into a signal for output to the video display element 11 and outputs the signal to the video display element 11.

  The display control unit 15 alternately outputs the right-eye video signal and the left-eye video signal to the video display element 11 in order to display the right-eye video and the left-eye video alternately on the white screen 14. The video display element 11 causes each pixel to emit light based on the video signal input from the display control unit 15. As a result, an image is displayed on the white screen 14.

  Further, the display control unit 15 outputs a timing signal indicating the switching timing between the right-eye video signal and the left-eye video signal to the shutter control unit 16. The shutter control unit 16 controls opening / closing of the liquid crystal shutter 55 of the liquid crystal shutter glasses 50, specifically, switching between transmission and non-transmission of light, based on the timing signal input from the display control unit 15.

  As shown in FIG. 2 described above, in the present embodiment, the front stage of the liquid crystal element 53 constituting the liquid crystal shutter 55, specifically, on the optical path between the liquid crystal element 53 and the glasses-side quarter-wave plate 51. In addition, an incident-side polarizing plate 52 is provided. As a result, even when the circularly polarized image light 23 projected on the white screen 14 is reflected as the randomly polarized image light 61, the linearly polarized image light 63 in a specific direction is incident on the liquid crystal element 53. Specifically, linearly polarized video light 63 having a polarization direction in a direction parallel to the transmission axis perpendicular to the absorption axis of the incident side polarizing plate 52 enters the liquid crystal element 53.

  Therefore, shutter control according to whether or not voltage is applied to the liquid crystal element 53 is possible, and therefore it is possible to prevent the right eye video and the left eye video from being mixed in the liquid crystal shutter glasses 50. As a result, the user can three-dimensionally recognize the video displayed on the white screen 14.

  As described above, according to the present embodiment, the liquid crystal shutter glasses 50 include the incident-side polarizing plate 52 in front of the liquid crystal element 53, so that the video light incident on the liquid crystal shutter glasses 50 from the white screen 14 is randomly polarized. Even in this case, video light having a specific polarization direction can be incident on the liquid crystal element 53. Thereby, in the liquid crystal element 53, incident video light can be emitted with its polarization direction changed according to the presence or absence of voltage application. That is, it is possible to perform shutter control according to the presence or absence of voltage application.

  Therefore, the crosstalk in which the right-eye video and the left-eye video are mixed with the liquid crystal shutter glasses 50 can be prevented. Therefore, even when the video light is randomly polarized on the white screen 14 as in the present embodiment, stereoscopic viewing is possible. Can be realized.

  As described above, in the present embodiment, even when the white screen 14 is used, the shutter function of the liquid crystal shutter glasses 50 can be maintained and stereoscopic viewing can be realized. Therefore, the stereoscopic image display system 1 can be realized by using the white screen 14 without using a special screen like the silver screen 71 described later.

  The glasses-side quarter-wave plate 51 may be provided so as to be removable. As in the present embodiment, when the circularly polarized image light 23 projected on the white screen 14 becomes the randomly polarized image light 61 by the white screen 14, the glasses-side quarter-wave plate 51 has a random polarization. Since it does not substantially function for image light, it does not have to be installed on the optical path of the stereoscopic image display system 1.

  As described above, the glasses-side quarter-wave plate 51 is detachably provided, so that when the randomly polarized video light 61 is emitted from the screen as in the case of using the white screen 14, for example, The four-wave plate 51 can be removed from the configuration of the stereoscopic video display system 1. Thus, the light can be brightened by the amount corresponding to the light transmission loss by the glasses-side quarter-wave plate 51.

  In the present embodiment, the liquid crystal element 53 of the left-eye liquid crystal shutter 55a transmits incident light when the left-eye image is displayed on the white screen 14, and when the left-eye image is not displayed on the white screen 14, It is controlled to block incident light. The liquid crystal element 53 of the right-eye liquid crystal shutter 55b transmits incident light when the right-eye image is displayed on the white screen 14, and blocks incident light when the right-eye image is not displayed on the white screen 14. To be controlled.

  In the present embodiment, as described above, shutter control can be performed in accordance with the presence or absence of voltage application in the liquid crystal element 53. Therefore, light transmission through the liquid crystal element 53 of the left-eye liquid crystal shutter 55a and the right-eye liquid crystal shutter 55b and By controlling the non-transmission as described above, it is possible to realize a stereoscopic view of the video displayed on the white screen 14.

<Second Embodiment>
FIG. 4 is a perspective view showing a configuration of the stereoscopic video display system 2 according to the second embodiment of the present invention. Since the stereoscopic video display system 2 of the present embodiment is similar in configuration to the above-described base technology and the stereoscopic video display systems 100 and 1 of the first embodiment, the same reference numerals are used for corresponding parts. In addition, a common description is omitted.

  The stereoscopic video display system 2 according to the present embodiment includes a video display device 70 and liquid crystal shutter glasses 50. The video display device 70 has the same configuration as that of the video display device 10 in the first embodiment, except that it includes a silver screen 71 instead of the white screen 14 in the first embodiment.

  Specifically, the video display device 70 includes a video display element 11, a device-side quarter-wave plate 12, a projection optical system 13, and a silver screen 71. On the silver screen 71, the circularly polarized image light 23 is projected from the projection optical system 13.

  Here, the “silver screen” refers to a general silver screen and refers to a screen that maintains the polarization state of incident light. The silver screen 71 is realized, for example, by a screen having a projection surface coated with a metal paint having high reflection performance. As the silver screen 71, for example, fine silver 240 (trade name, manufactured by Kikuchi Science Laboratory Co., Ltd.) or the like can be used. The silver screen 71 maintains the polarization state of the circularly polarized image light 23 projected by the projection optical system 13 and reflects it as circularly polarized image light 81.

  The liquid crystal shutter glasses 50 are used to stereoscopically view an image displayed on the silver screen 71. The circularly polarized image light 81 reflected by the silver screen 71 is incident on the glasses-side quarter-wave plate 51 of the liquid crystal shutter glasses 50. When the circularly polarized image light 81 is incident on the glasses-side quarter-wave plate 51, the incident circularly polarized image light 81 is a straight line whose polarization direction is a second direction parallel to the transmission axis of the incident-side polarizing plate 52. The light is converted into polarized image light 82 and emitted. The linearly polarized image light 82 that has passed through the glasses-side quarter-wave plate 51 enters the incident-side polarizing plate 52.

  The incident side polarizing plate 52 is provided on the optical path between the spectacle side quarter wavelength plate 51 and the liquid crystal element 53. The incident-side polarizing plate 52 has an absorption axis that is a polarization axis extending in a predetermined first direction. The incident-side polarizing plate 52 transmits only light in the second direction parallel to the transmission axis perpendicular to the absorption axis. The linearly polarized image light 82 transmitted through the spectacle-side quarter-wave plate 51 has the second direction parallel to the transmission axis of the incident-side polarizing plate 52 as the polarization direction, as described above. The light passes through and is emitted as linearly polarized image light 83 with the second direction as the polarization direction. The video light 83 transmitted through the incident side polarizing plate 52 enters the liquid crystal element 53.

  The liquid crystal element 53 rotates the polarization direction of incident light according to the presence or absence of voltage application. The liquid crystal element 53 does not rotate the polarization direction of incident light when a voltage is applied, and rotates the polarization direction of incident light when a voltage is not applied.

  When linearly polarized video light 83 having a second direction parallel to the transmission axis of the incident-side polarizing plate 52 is incident on the liquid crystal element 53, the liquid crystal element 53 is incident when no voltage is applied. It is converted into linearly polarized image light 84 having a first direction that is 90 ° different from the polarization direction of the image light 83 as the polarization direction, and transmitted. In addition, when a voltage is applied, the liquid crystal element 53 does not transmit the linearly polarized image light 85 whose polarization direction is the same as the polarization direction of the incident image light 83. The video light 84 that has passed through the liquid crystal element 53 enters the output-side polarizing plate 54.

  The exit-side polarizing plate 54 has an absorption axis that is a polarization axis extending in the second direction. The axial direction of the absorption axis of the exit-side polarizing plate 54 and the absorption axis of the incident-side polarizing plate 52 differ by 90 °. The output side polarizing plate 54 transmits only light in the first direction parallel to the transmission axis perpendicular to the absorption axis of the output side polarizing plate 54. Since the image light 84 emitted from the liquid crystal element 53 and incident on the output-side polarizing plate 54 is linearly polarized light having the first direction as the polarization direction, the output-side polarizing plate 54 converts the incident video light 84 into the first direction. The image light 86 that is parallel to one direction is transmitted as it is.

  As described above, in the present embodiment, similarly to the first embodiment, the front stage of the liquid crystal element 53 constituting the liquid crystal shutter 55, specifically, the liquid crystal element 53 and the glasses-side quarter-wave plate 51 are arranged. An incident-side polarizing plate 52 is provided on the optical path between them. As a result, linearly polarized light in a specific direction is incident on the liquid crystal element 53, so that the liquid crystal shutter 55 can perform shutter control depending on whether or not voltage is applied. Therefore, since the right-eye video and the left-eye video are not mixed by the liquid crystal shutter glasses 50, crosstalk in which the left and right videos are mixed can be suppressed.

  In the present embodiment, linearly polarized image light 21 emitted from the image display element 11 of the image display device 10 is converted into circularly polarized light by the device-side quarter-wave plate 12 and emitted from the projection optical system 13. And projected onto the silver screen 71. As described above, since the polarization state of incident light is maintained in the silver screen 71, the image light 81 reflected by the silver screen 71 is incident on the glasses-side quarter-wave plate 51 as circularly polarized light. The circularly polarized image light 81 incident on the spectacle-side quarter-wave plate 51 is converted into linearly polarized image light 82 in a specific direction and is incident on the incident-side polarizing plate 52.

  In the present embodiment, the glasses-side quarter-wave plate 51, the incident-side polarizing plate 52, the liquid crystal element 53, and the outgoing-side polarizing plate 54 constituting the liquid crystal shutter 55 are integrally configured. Thus, when the user wearing the liquid crystal shutter glasses 55 tilts his / her neck, the glasses side quarter-wave plate 51, the incident side polarizing plate 52, the liquid crystal element 53, and the outgoing side polarizing plate 54 are integrated. , Tilt in the direction the user tilted his neck. That is, the positional relationship of the axes in the spectacle-side quarter-wave plate 51, the incident-side polarizing plate 52, the liquid crystal element 53, and the outgoing-side polarizing plate 54 does not change even when the user tilts his / her neck. Even in this case, the polarization direction of the image light 82 incident on the incident-side polarizing plate 52 from the spectacle-side quarter-wave plate 51 does not change.

  Therefore, since the influence of the tilt of the liquid crystal shutter glasses 50 can be suppressed, an accurate shutter operation can be performed on the image light 81 reflected by the silver screen 71. As a result, it is possible to suppress the change in brightness and the occurrence of crosstalk in which the left and right images are mixed.

  In the present embodiment, since the silver screen 71 is used, the image light 23 incident on the silver screen 71 is maintained in a circular polarization state, and is used as the circularly polarized image light 81 on the eyeglass side of the liquid crystal shutter glasses 50. The light enters the quarter wave plate 51. The incident circularly polarized image light 81 is converted into linearly polarized image light 82 parallel to the transmission axis of the incident-side polarizing plate 52 by the glasses-side quarter-wave plate 51 and is incident on the incident-side polarizing plate 52. The As a result, the image light 82 can be efficiently transmitted through the incident-side polarizing plate 52. Therefore, the brightness that reaches the eyes of the user can be as high as when the incident-side polarizing plate 52 is not provided.

  In the image display apparatuses 10 and 70 in the first and second embodiments described above, the apparatus-side quarter-wave plate 12 is provided on the optical path between the image display element 11 and the projection optical system 13. It has been. Thereby, the image light 23 projected on the white screen 14 or the silver screen 71 can be made into circularly polarized light. Therefore, for example, when the silver screen 71 that maintains the polarization state of the incident image light 23 is used as in the second embodiment, the image light can be efficiently incident on the liquid crystal shutter 55. .

  The device-side quarter-wave plate 12 has a slow axis that rotates clockwise in the light traveling direction with respect to the longitudinal direction, which is the polarization direction of the linearly polarized image light 21 emitted from the image display element 11. It is provided so as to be inclined by 45 °. Thereby, the image light 23 emitted from the projection optical system 13 becomes right circularly polarized light.

  In order to realize stereoscopic viewing with the liquid crystal shutter glasses 50, red (Red; abbreviation: R), green (abbreviation: G) and green (Green) immediately before entering the device-side quarter-wave plate 12 from the image display element 11. The polarization direction of the image light 21 of each color of blue (Blue; abbreviation: B) needs to be aligned. By aligning the polarization directions, the rotation directions of the circularly polarized light emitted from the device-side quarter-wave plate 12 are the same for the R, G, and B image light 22. As a result, the R, G, B image light can be converted into linearly polarized light in the same lateral direction in the glasses side quarter wavelength plate 51 provided on the incident side of the liquid crystal shutter glasses 55. .

  If only the G image light has a different polarization direction, the rotation directions of the circularly polarized light emitted from the device-side quarter-wave plate 12 are R and B image light is right circularly polarized, and G image light is Left circularly polarized light. In this case, in the eyeglass-side quarter-wave plate 51 provided on the incident side of the liquid crystal shutter glasses 55, the R and B image lights are laterally linearly polarized light, and the G image light is longitudinally linearly polarized light. Become. Therefore, since the G image light is absorbed by the incident-side polarizing plate 52, only the R and B image lights reach the user's eyes, and the G image light does not reach the user's eyes.

  When the video display device 10 is a three-plate liquid crystal projector that includes a video display element 11 for each of R, G, and B colors, and includes a device-side quarter-wave plate 12 and a projection optical system 13 one by one. The light from the light source is separated by the dichroic mirror for each of the R, G, and B colors, transmitted through the video display element 11 for each of the R, G, and B colors, and then synthesized by the three-color synthesis prism. The light enters the apparatus-side quarter-wave plate 12 and the projection optical system 13.

  In the three-color synthesis prism provided between the image display element 11 for each of R, G, and B colors, the apparatus-side quarter-wave plate 12 and the projection optical system 13, the G image light in the transmitted light path is P. It is designed to be polarized, and the R and B image lights in the reflected light path become S-polarized light. This is because P-polarized light has better light use efficiency for transmitted light, and S-polarized light has better light use efficiency for reflection.

  In this way, when the polarization directions of the G image light and the R and B image lights are different, a wavelength-selective polarization rotator capable of rotating the polarization oscillation direction by 90 ° only in a specific wavelength range is provided for the three-color synthesis prism. It is preferable that the polarization direction is rotated only for the G image light provided on the exit side. This makes it possible to align the polarization directions of the three colors of R, G, and B image light. As the wavelength-selective polarization rotator, for example, ColorSelect (trade name, manufactured by Color Link) or the like can be used.

  When the wavelength selective polarization rotator is used in this way, the transmittance of the G image light is higher than when the polarization directions of the R, G, B image light are aligned before entering the three-color combining prism. High brightness can be realized.

  When the linearly polarized liquid crystal shutter glasses 50 are used as in the first and second embodiments described above, the device side 1/2 provided on the optical path between the image display element 11 and the projection optical system 13 is used. The four-wave plate 12 is preferably provided so as to be switchable between a state where it is installed on the optical path and a state where it is retracted from the optical path. In this case, there is provided drive means capable of switching between a state where the apparatus-side quarter-wave plate 12 is installed on the optical path and a state where the apparatus-side quarter-wave plate 12 is retracted from the optical path. Just do it.

  Thus, by providing the device-side quarter-wave plate 12 so that it can be switched between a state where it is placed on the optical path and a state where it is retracted from the optical path, the user can perform the first and second implementations. When the linearly polarized liquid crystal shutter glasses 50 are used as in the embodiment, the apparatus-side quarter-wave plate 12 can be retracted from the optical path. As a result, the brightness can be increased by an amount corresponding to the transmission loss of light by the device-side quarter-wave plate 12. This effect is particularly exerted when the random polarization type white screen 14 is used as in the first embodiment.

  When the apparatus-side quarter-wave plate 12 is retracted, in order to match the optical path length between the projection optical system 13 and the image display element 11 with the state where the apparatus-side quarter-wave plate 12 is installed, the apparatus-side 1/4 Instead of the four-wave plate 12, it is desirable to install a glass plate having the same thickness as the base material of the device-side quarter-wave plate 12. As the glass plate, a plate that simply transmits incident light without polarizing it may be used.

  As described above, by using the liquid crystal shutter glasses 50 according to the first and second embodiments, even when the image light incident on the liquid crystal shutter glasses 50 is randomly polarized, the user of the liquid crystal shutter glasses 50 is also in the neck. Even when tilted, an accurate shutter operation can be performed. Therefore, crosstalk where left and right images are mixed can be suppressed as much as possible.

  Specifically, for example, when the polarization state of the image light is disturbed on the white screen 14 or the like as in the first embodiment and becomes a random polarization state, the light incident on the right eye and the left eye of the user is changed. The optical shutter function of the liquid crystal shutter glasses 50 to be controlled can be exhibited. Therefore, even when the user tilts his / her head, a decrease in brightness can be suppressed as compared with the case where the user does not tilt his / her head, so that the user can view a stereoscopic image without a sense of incongruity.

  In addition, when the image light incident on the liquid crystal shutter glasses 50 is circularly polarized as in the second embodiment, the image light incident on the liquid crystal shutter glasses 50 is in the same direction in each of R, G, and B colors, for example, right If the circularly polarized state is a counterclockwise or counterclockwise circular polarization state, it is possible to prevent inconveniences such as a decrease in brightness and crosstalk when the user tilts his / her neck.

  1, 2 stereoscopic image display system, 10, 70 image display device, 11 image display element, 12 device side quarter wave plate, 13 projection optical system, 14 white screen, 50 liquid crystal shutter glasses, 51 eyeglass side quarter wavelength Plate, 52 Incident side polarizing plate, 53 Liquid crystal element, 54 Outgoing side polarizing plate, 55 Liquid crystal shutter, 71 Silver screen.

Claims (8)

A video display device that alternately displays a right-eye video and a left-eye video for forming a stereoscopically recognizable video, and liquid crystal shutter glasses that are driven according to the video displayed on the video display device Prepared,
The video display device
An image display element that alternately emits image light corresponding to the right-eye image and image light corresponding to the left-eye image;
A screen on which image light emitted from the image display element is projected;
A projection optical system for projecting image light emitted from the image display element onto the screen;
The liquid crystal shutter glasses are
A spectacle-side quarter-wave plate for converting incident circularly polarized light into linearly polarized light in a predetermined polarization direction;
An incident-side absorption axis that is a polarization axis extending in a first direction defined in advance, and the incident-side transmission axis perpendicular to the incident-side absorption axis out of the incident light emitted from the spectacle-side quarter-wave plate An incident-side polarizing plate that transmits light in a parallel direction;
A liquid crystal element that emits light that is emitted from the incident-side polarizing plate and changes the polarization direction depending on whether or not a voltage is applied; and
Outgoing light absorption axis that is a polarization axis extending in a second direction perpendicular to the first direction, and out of incident light emitted from the liquid crystal element, the light transmission axis is perpendicular to the emission side absorption axis. A stereoscopic image display system comprising: an exit-side polarizing plate that transmits light in a parallel direction.   The three-dimensional image display system according to claim 1, wherein the screen is a white screen that disturbs a polarization state of incident image light.   The three-dimensional image display system according to claim 1, wherein the screen is a silver screen that maintains a polarization state of incident image light.   The image display device includes a device-side quarter-wave plate for converting image light having a predetermined polarization direction into circularly polarized light on an optical path between the projection optical system and the image display element. The 3D image display system according to any one of claims 1 to 3.   The apparatus-side quarter-wave plate emits red, green, and blue video light constituting video light emitted from the video display element and inputted as circularly polarized light in the same rotation direction. The stereoscopic video display system according to claim 4.   6. The stereoscopic image according to claim 4, wherein the device-side quarter-wave plate is provided so as to be switchable between a state where it is installed on the optical path and a state where it is retracted from the optical path. Display system.   The stereoscopic image display system according to any one of claims 1 to 6, wherein the glasses-side quarter-wave plate is detachably provided. The liquid crystal shutter glasses are
A right-eye liquid crystal shutter disposed in a portion facing the right eye of the user;
A left-eye liquid crystal shutter disposed in a portion facing the left eye of the user,
The right-eye liquid crystal shutter and the left-eye liquid crystal shutter each include the glasses-side quarter-wave plate, the incident-side polarizing plate, the liquid crystal element, and the outgoing-side polarizing plate,
The liquid crystal element of the right-eye liquid crystal shutter transmits incident light when the right-eye image is displayed on the screen, and blocks incident light when the right-eye image is not displayed on the screen. Controlled by
The liquid crystal element of the left-eye liquid crystal shutter transmits incident light when the left-eye image is displayed on the screen, and blocks incident light when the left-eye image is not displayed on the screen. The stereoscopic image display system according to any one of claims 1 to 7, wherein the stereoscopic image display system is controlled by the control.

Images