JP5426343B2 - Image light output device - Google Patents

Description

  The present invention relates to an image light output device.

The optical path of the image light in the odd field and the optical path of the image light in the even field are switched for each field using the phase modulation optical element and the birefringence optical element, and the image in one field is changed to the image in the other field. A wobbling technique for displaying images at different positions is known.
As a display device to which this wobbling technology is applied, a polarization plane rotating element and a birefringent optical element are provided between a liquid crystal panel and a polarizing screen, and odd-numbered field image light and even-numbered field image light emitted from the liquid crystal panel. An optical wobbling display device is proposed that rotates the plane of polarization for each field and shifts the optical path of the image light of one field by one pixel in the vertical direction on the polarization screen with respect to the optical path of the image light of the other field. (For example, refer to Patent Document 1).

JP-A-8-29779

Using the optical wobbling display device described in Patent Document 1, the optical path of the image light in one field is shifted by 0.5 pixels vertically or horizontally on the screen with respect to the optical path of the image light in the other field. By doing so, it is possible to obtain an image having a resolution twice as large as that in the shift direction.
However, since the optical wobbling display device described in Patent Document 1 has a configuration in which the optical path of the image light of all the constituent colors is shifted by the birefringence optical element, the optical wobbling display device is used to display a pixel shifted. Requires twice as much video information as usual and is inefficient.

  Accordingly, the present invention has been made in view of the above problems, and an object thereof is to provide a video light output device that performs pixel-shifted display by a wobbling method by efficiently using a video source. In addition, an object of the present invention is to provide an image light output device that performs pixel-shifted display with good contrast.

[1] In order to solve the above-described problem, according to one aspect of the present invention, an optical path switching control unit that outputs a switching control signal that alternately switches the first and second states in a predetermined cycle, and a first of a predetermined color And the second video light is supplied with the predetermined color video light that is alternately switched at the predetermined cycle and the third video light with a color different from the predetermined color, and the optical path switching control unit When the switching control signal is supplied and the switching control signal is in the first state, the first and third image lights are not shifted in the optical path between the input and output of the image light output device. And when the switching control signal is in the second state, an optical path shift unit that outputs the second video light to the output side by shifting the optical path with respect to the input side of the video light output device; , wherein the light path shift unit, wherein the predetermined color of the image light In response to the supply of the third image light, the image light of the predetermined color is split to transmit one image light in a straight line and refract the other image light to shift and transmit the light path. The birefringent optical unit that transmits the third image light in a straight line and the first output image light from the birefringent optical unit when the switching control signal is in the first state. An optical phase modulation unit that modulates the polarization direction of the first output video light when the direction of the switching control signal is in the second state while not modulating the direction;
A second output image light from the optical phase modulating unit, and wherein the Rukoto and a polarizing plate that transmits only the image light in a predetermined polarization direction component.
Here, the video light output from the video light output device is, for example, red, first green, second green, and blue video light. The predetermined period is a frame period of a video and may be a field period. For example, the first and second video lights are a first green video and a second green video, respectively, and the third video light is a red video and a blue video, respectively.

  According to the present invention, it is possible to perform an efficient pixel-shifted display of a video source by shifting the optical path for only the desired color video light among the constituent colors in a time-sharing manner. In addition, according to the present invention, it is possible to perform pixel-shifted display with good contrast.

1 is a block diagram illustrating an overall configuration of a projection display system to which an image light output device according to a first embodiment of the present invention is applied. It is a block diagram which shows the function structure of the signal generator in the embodiment. It is a block diagram which shows the function structure of the optical unit part in the embodiment. It is a block diagram which shows the function structure of the optical path shift part in the embodiment. 4 is a timing chart showing operation timings of a frame synchronization signal and a switching control signal in the same embodiment. In the same embodiment, it is a figure which shows typically the polarization state in each input / output of an optical phase modulation element. In the same embodiment, it is the figure which showed typically a mode that two types of optical paths exist in the birefringent medium contained in a birefringent optical element. In the same embodiment, it is a figure which shows typically the polarization state and optical path in each part of an optical path shift part. It is a block diagram which shows the function structure of the optical path shift part contained in the imaging | video light output device which is 2nd Embodiment of this invention. In the embodiment, it is the figure which showed typically the polarization state in each input / output of an optical phase modulation element. In the same embodiment, it is a figure which shows typically the polarization state and optical path in each part of an optical path shift part. 5 is a timing chart showing the relationship between video frame switching timing and response timing of an optical phase modulation element. 6 is a timing chart showing the relationship between video frame switching timing and linearly approximated response timing of an optical phase modulation element. It is a graph which shows the relationship between the response speed and contrast of the optical phase modulation element comprised with the liquid crystal. 10 is a timing chart showing the relationship between video frame switching timing and linearly approximated response timing of an optical phase modulation element when contrast is improved in the third embodiment of the present invention. 5 is a graph showing the relationship between contrast and drive shift time when the contrast is improved in the embodiment. 10 is a graph showing the relationship between contrast and drive shift time when the contrast is improved by inserting black in the modification of the embodiment. It is a figure which shows typically the state of a frame overwrite at the time of using a green light display element as a liquid crystal display element. In a 4th embodiment of the present invention, it is a figure showing typically relation between change of a frame picture, and change control signal SC. It is a block diagram which shows the function structure of the optical path shift part and optical path switching control part which are contained in the imaging | video light output device which is 5th Embodiment of this invention. In the same embodiment, it is the figure which looked at the element surface of the optical phase modulation element contained in an optical path shift part typically. 4 is a timing chart illustrating operation timings of a frame synchronization signal and a switching control signal in the same embodiment. 5 is a graph showing the relationship between the number of horizontal lines and contrast when an optical phase modulation element is used in the embodiment. In 6th Embodiment of this invention, it is the figure which represented typically the rotary shutter which is a physical shutter mechanism from the incident side of image light. It is a block diagram which shows the function structure of the optical path shift part in the imaging | video light output device which is 6th Embodiment of this invention. In the same embodiment, it is a block diagram which shows the function structure of an optical path shift part and an optical path switching control part at the time of applying four steps of optical path shift parts. It is a block diagram which shows the schematic structure of the birefringent optical part contained in the optical path shift part in the imaging | video light output device which is 8th Embodiment of this invention. It is a block diagram which shows the whole structure at the time of applying the projection type display system in each embodiment of this invention to a stereoscopic video display system.

Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the drawings.
[First Embodiment]
FIG. 1 is a block diagram showing an overall configuration of a projection display system to which an image light output device according to a first embodiment of the present invention is applied. As shown in FIG. 1, the projection display system 1 includes a signal generation device 10, a video signal switching device 20, and a projection display device 30.
The signal generator 10 includes a red video signal Rin that is a video signal of red video, a blue video signal Bin that is a video signal of blue video, a first green video signal G1in that is a video signal of first green video, A second green video signal G2in which is a video signal of 2 green video and a frame synchronization signal FT synchronized with the frame period of the video are output.
The video signal switching device 20 is supplied with the first green video signal G1in, the second green video signal G2in, and the frame synchronization signal FT, and according to the frame period of the frame synchronization signal FT, the first green video signal G1in. And the second green video signal G2in are alternately switched to output the green video signal Gin. That is, the video signal switching device 20 outputs the green video signal Gin, which is a video in which the first green video and the second green video are alternately switched for each frame. The video signal switching device 20 is a frame switcher having a configuration of, for example, two video inputs × one video output.

The projection display device 30 receives the red video signal Rin, the blue video signal Bin, the green video signal Gin, and the frame synchronization signal FT, and receives the red video signal, the blue video, and the first green video on the frame. And the pixel position on the frame of the second green image is shifted by, for example, less than one pixel (for example, 0.5 pixel) in the vertical direction with respect to the pixel position on the frame of the first green image. Thus, the red image light Rout, the green image light Gout, and the blue image light Bout with the optical paths set are projected.
The projection display device 30 includes an optical unit 31, an optical path shift unit 32, an optical path switching control unit 33, and a projection optical system 34.
Note that the image light output device of the present embodiment is a device including an optical path shift unit 32 and an optical path switching control unit 33.

The optical unit 31 receives the red video signal Rin, the blue video signal Bin, and the green video signal Gin, converts the electrical signal into an optical signal, and converts the red video light Rlp, which is vertical linearly polarized light, The green image light Gcp, which is circularly polarized light, and the blue image light Blp, which is vertical linearly polarized light, are output.
The green video light Gcp is a first green video light (first video light) based on the first green video signal G1in and a second green video light (second video based on the second green video signal G2in) according to the frame period of the video. Light) that is alternately switched. The red video light Rlp and the blue video light Blp are the third video light.
The optical path shift unit 32 receives the supply of the red video light Rlp, the green video light Gcp, and the blue video light Blp from the optical unit unit 31 and also receives the switching control signal SC from the optical path switching control unit 33. According to the switching timing of the switching control signal SC, on the frame of the red video by the red video light Rlp, the blue video by the blue video light Blp, and the first green video by the first green video light included in the green video light Gcp. And the pixel position on the second green video frame by the second green video light included in the green video light Gcp is one pixel in the vertical direction with respect to the pixel position on the first green video frame. The red image light Rout, the green image light Gout, and the blue image light Bout, whose optical paths are set so as to be shifted by less than, are output.
In response to the supply of the frame synchronization signal FT, the optical path switching control unit 33 generates and outputs a switching control signal SC that repeats the OFF state (first state) and the ON state (second state) in the frame period. .
The projection optical system 34 includes at least a projection lens, and projects the red video light Rout, the green video light Gout, and the blue video light Bout to the outside through the projection lens.

  In addition to the red / green / blue (RGB) video signals, video control signals such as video synchronization signals and clock signals are supplied from the signal generator 10 to the video signal switching device 20 and the projection display device 30. However, in the present embodiment, only the RGB video signal system will be described and illustrated, and the description and illustration of the video control signal will be omitted.

Next, the configuration of the signal generator 10 will be described. FIG. 2 is a block diagram showing a functional configuration of the signal generator 10. As shown in the figure, the signal generating device 10 includes a video data storage unit 11, a video data reading unit 12, and a delay processing unit 13.
The video data storage unit 11 stores video data including frame data of red video, blue video, first green video, and second green video. The image data for one frame of the video data includes, for example, the arrangement positions of the pixels of the red image, the pixels of the blue image, and the pixels of the first green image, and the pixels of the second green image are the first. A frame image is formed with an arrangement position shifted vertically downward by 0.5 pixels with respect to the pixels of the green image. The video data storage unit 11 stores, as video data, four systems of shooting data captured by a four-plate imaging device using, for example, red, blue, and two systems of green (dual green). Alternatively, pixel-shifted video data may be generated by signal processing from high-definition or ultra-high-definition video data and stored as video data.

  The video data reading unit 12 reads video data from the video data storage unit 11 and supplies red video data Rd and blue video data Bd among the video data to the delay processing unit 13. The video data reading unit 12 includes a first green video signal G1in that is a video signal of the first green video data and a second green video signal G2in that is a video signal of the second green video data among the read video data. Is output. Furthermore, the video data reading unit 12 generates and outputs a frame synchronization signal FT synchronized with the frame period of the video based on the synchronization signal of the video control signal.

The delay processing unit 13 receives the supply of the red video data Rd and the blue video data Bd, and delays the transmission timing of the red video data Rd and the blue video data Bd by the time required for the processing of the video signal switching unit 20. Thereafter, a red video signal Rin that is a video signal of red video data Rd and a blue video signal Bin that is a video signal of blue video data Bd are output.
The delay processing unit 13 may be provided in front of the optical unit unit 31 in the projection display device 30 instead of the signal generation device 10 side.

  Next, a more detailed configuration of each part of the projection display device 30 will be described. FIG. 3 is a block diagram showing a functional configuration of the optical unit 31. As shown in the figure, the optical unit 31 includes a light source 311, a blue light dichroic mirror 312, a yellow light dichroic mirror 313, polarizing beam splitters 314, 315, 317, 319 and 321, and a blue light display element. 316, a green light dichroic mirror 318, a red light display element 320, a green light display element 322, a λ / 4 plate 323, and a cross dichroic prism 324.

  The light source unit 311 includes a white light source and a polarization conversion element. White light emitted from the white light source passes through the polarization conversion element, and becomes S-polarized white light L whose polarization component is aligned with S-polarized light. The blue light dichroic mirror 312 reflects the blue light B having the blue light wavelength component in the S-polarized white light L emitted from the light source unit 311 and causes the blue light B to enter the polarization beam splitter 314. The polarization beam splitter 314 reflects the incident S-polarized blue light B and makes it incident on the polarization beam splitter 315. The polarization beam splitter 315 reflects the incident blue light B, which is S-polarized light, and causes the blue light B to enter the display unit of the blue light display element 316. The blue light display element 316 receives the supply of the blue video signal Bin from the signal generation device 10 and displays it on the display unit, and modulates the blue light B incident on the display unit to generate the blue video light Blp that is P-polarized light. The light is incident on the polarization beam splitter 315 as reflected light. Note that the blue image light Blp is vertical linearly polarized light. The polarization beam splitter 315 transmits the incident blue image light Blp that is P-polarized light and makes it incident on the cross dichroic prism 324.

  The yellow light dichroic mirror 313 reflects yellow light Ye having only a red light wavelength component and a green light wavelength component in the S-polarized white light L emitted from the light source unit 311 so as to enter the polarization beam splitter 317. The polarization beam splitter 317 reflects the incident yellow light Ye, which is S-polarized light, so as to enter the green light dichroic mirror 318. The green light dichroic mirror 318 transmits the red light R having the red light wavelength component in the incident yellow light Ye and causes the red light R to enter the polarization beam splitter 319. Further, the green light dichroic mirror 318 reflects the green light G having the green light wavelength component in the yellow light Ye and makes it incident on the polarization beam splitter 321.

  The polarization beam splitter 319 reflects the incident red light R, which is S-polarized light, and causes the red light display element 320 to enter the display unit. The red light display element 320 receives the red video signal Rin from the signal generator 10 and displays the red video signal Rin on the display unit. The red light display element 320 modulates the red light R incident on the display unit to generate red video light Rlp that is P-polarized light. The light is incident on the polarization beam splitter 319 as reflected light. Note that the red video light Rlp is vertical linearly polarized light. The polarizing beam splitter 319 transmits the incident red video light Rlp, which is P-polarized light, and enters the cross dichroic prism 324.

  The polarizing beam splitter 321 reflects the incident green light G, which is S-polarized light, and causes the green light display element 322 to enter the green light display element 322. The green light display element 322 receives the supply of the green image signal Gin from the image signal switching device 20 and displays it on the display unit, and modulates the green light G incident on the display unit to generate green image light that is P-polarized light. The light is incident on the λ / 4 plate 323 as reflected light. The green image light incident on the λ / 4 plate 323 is vertical linearly polarized light. The λ / 4 plate 323 converts the polarization state of the incident green image light from vertical linearly polarized light to right circularly polarized light, and enters the cross dichroic prism 324 as green image light Gcp.

The cross dichroic prism 324 reflects and outputs the blue image light Blp incident from the polarization beam splitter 315, reflects and outputs the red image light Rlp incident from the polarization beam splitter 319, and outputs from the λ / 4 plate 323. The incident green video light Gcp is transmitted and output.
The blue light display element 316, the red light display element 320, and the green light display element 322 are reflective display elements such as LCOS (Liquid Crystal On Silicon) and DMD (Digital Mirror Device).

FIG. 4 is a block diagram illustrating a functional configuration of the optical path shift unit 32. As shown in the figure, the optical path shift unit 32 includes an optical phase modulation element 351, a phase plate 352, and a birefringence optical element 353.
The optical phase modulation element 351 is supplied with the red video light Rlp, the green video light Gcp, and the blue video light Blp from the optical unit 31, and also receives the switching control signal SC from the optical path switching controller 33. . Then, the optical phase modulation element 351 transmits the red video light Rlp, the green video light Gcp, and the blue video light Blp for each frame based on the switching control signal SC without changing the polarization state of each, The state in which only the polarization state of the green image light Gcp that is right circularly polarized light is changed and transmitted is alternately repeated.
The phase plate 352 is an optical element that converts the polarization state of only the green light wavelength component of the image light. In the present embodiment, the phase plate 352 has phase modulation characteristics for converting right circularly polarized light into vertical linearly polarized light and converting left circularly polarized light into horizontal linearly polarized light for only the green light wavelength component of the image light.
The birefringent optical element 353 is an optical element having birefringence characteristics and is formed including a birefringent medium. The birefringence characteristic is a property of traveling in two directions depending on the polarization state of the light beam when the light beam passes through the birefringent medium.

FIG. 5 is a timing chart showing operation timings of the frame synchronization signal FT and the switching control signal SC. As shown in the figure, the frame synchronization signal FT is a pulse signal that rises in a predetermined period at the beginning of each frame in the frame period of the video. This leading predetermined period may be, for example, a vertical blanking period.
The switching control signal SC is a toggle signal that repeats an OFF state and an ON state in synchronization with the rising edge of each pulse of the frame synchronization signal FT. The OFF state is a 0 (zero) value, and the ON state is an arbitrary level value. To do. The period in which the switching control signal SC is in the OFF state corresponds to the frame period of the first green video, and the period in which the switching control signal SC is in the ON state corresponds to the frame period of the second green video.
Since the frame synchronization signal FT may be any signal that can detect the frame period, the operation timing of the frame synchronization signal FT may be the same as that of the switching control signal SC in FIG.

  Next, the phase modulation characteristics of the optical phase modulation element 351 will be described. FIG. 6 is a diagram schematically showing the polarization states at the input and output of the optical phase modulation element 351. FIG. 4A is a diagram showing the polarization state of the optical phase modulation element 351 when the switching control signal SC is in the OFF state, and FIG. 4B is a diagram when the switching control signal SC is in the ON state. 6 is a diagram showing a polarization state of an optical phase modulation element 351. FIG. In both FIGS. 4A and 4B, the direction of the optical axis O is the same as the traveling direction of the light beam as shown in FIG. In the figure, after the output of the optical phase modulation element 351 when linearly polarized light whose polarization azimuth angles are 0 degrees, 45 degrees, and 90 degrees with respect to the optical axis O and right circularly polarized light are respectively incident. The polarization state is as follows.

  As shown in FIG. 6A, when the switching control signal SC is in the OFF state, the polarization state before incidence of the optical phase modulation element 351 and the polarization state after output are the same for all four types. Further, as shown in FIG. 5B, when the switching control signal SC is in the ON state, the output after the output with respect to the incident on the optical phase modulation element 351 of the linearly polarized light whose polarization azimuth is 0 degree and 90 degrees The two polarization states are the same. Further, the polarization states after output with respect to the incidence of the linearly polarized light and the right circularly polarized light on the optical phase modulation element 351 having the polarization azimuth angle of 45 degrees are the linearly polarized light and the left circularly polarized light having the polarization azimuth angle of 135 degrees.

  That is, the Mueller matrix M (bold body) obtained by quantifying the polarization characteristics of the optical phase modulation element 351 when the switching control signal SC is in the ON state is expressed by Equation (1). Note that the description “(bold)” indicates that the character immediately before is represented in bold, and that the character represented by the character is a matrix or a vector.

  When linearly polarized light having a polarization azimuth angle of 0 degrees is incident on the optical phase modulation element 351 when the switching control signal SC is in the ON state, the Stokes vector S (bold body) ′ (dash) after the phase modulation is expressed by the equation (2) That is, when the switching control signal SC is in the ON state, when linearly polarized light having a polarization azimuth angle of 0 degrees is incident on the optical phase modulation element 351, linearly polarized light having a polarization azimuth angle of 0 degrees is output.

  When linearly polarized light having a polarization azimuth angle of 45 degrees is incident on the optical phase modulation element 351 when the switching control signal SC is in the ON state, the Stokes vector S (bold body) ′ (dash) after the phase modulation is expressed by the equation (3) That is, when the switching control signal SC is in the ON state, when linearly polarized light having a polarization azimuth angle of 45 degrees is incident on the optical phase modulation element 351, linearly polarized light having a polarization azimuth angle of 135 degrees is output.

  When the linearly polarized light having a polarization azimuth angle of 90 degrees is incident on the optical phase modulation element 351 when the switching control signal SC is in the ON state, the Stokes vector S (bold body) ′ (dash) after the phase modulation is an expression. (4) That is, when the switching control signal SC is in the ON state, when linearly polarized light having a polarization azimuth angle of 90 degrees is incident on the optical phase modulation element 351, linearly polarized light having a polarization azimuth angle of 90 degrees is output.

  When the right circularly polarized light is incident on the optical phase modulation element 351 when the switching control signal SC is in the ON state, the Stokes vector S (bold body) '(dash) after the phase modulation is expressed by Equation (5). That is, when the right circular polarized light is incident on the optical phase modulation element 351 when the switching control signal SC is in the ON state, the left circular polarized light is output.

Next, the birefringent optical element 353 will be described. FIG. 7 is a diagram schematically showing a state in which two types of optical paths exist in the birefringent medium included in the birefringent optical element 353. As shown in the figure, when the optical axis of the birefringent medium included in the birefringent optical element 353 is the Z axis 71, when a light beam 72 is incident on the birefringent optical element 353, A vertically oscillating light beam (ordinary light beam) 73 travels straight, and a light beam (abnormal light beam) 74 whose vibration direction is perpendicular to the straight line refracts in the birefringent medium and travels in an oblique direction. As the birefringent medium, quartz, calcite, rutile, liquid crystal, and the like can be applied. Among these, quartz is preferably used because it is easy to make artificially.
The relationship between the angle α formed between the surface of the medium crystal on the incident side of the birefringent optical element 353 and the Z axis 71 and the angle β, which is the beam split angle between the ordinary ray 73 and the extraordinary ray 74, is the ordinary light refraction of the birefringent medium. When the rate is n _o and the extraordinary light refractive index is n _e , it is expressed by equation (6).

The optical path shift amount, which is a deviation of the exit optical axis of the extraordinary ray 74 from the exit optical axis of the ordinary ray 73 on the medium crystal surface on the output side of the birefringent optical element 353, is determined by the thickness of the birefringent medium in the exit optical axis direction. . For example, the ordinary refractive index _{n o} in the case of the crystal of the birefringent medium of the birefringent optical element 353 1.5443, extraordinary refractive index _{n e} is 1.5534, the optical path shift amount in order to 5μm is According to the calculation of equation (6), the thickness of the crystal is set to 0.851 mm. An optical path shift amount of 5 μm is a frame of 7680 pixels horizontal × vertical 4320 pixels of super high-definition video called super hi-vision on the display portion when the green light display element 322 is LCOS having a diagonal of 1.75 inches. This is a length corresponding to the size of one pixel when an image is displayed.
The direction of the optical path shift of the extraordinary ray 74 with respect to the ordinary ray 73 of the birefringent optical element 353 is determined by the rotation angle of the birefringent optical element 353 with the ordinary ray 73 as the rotation axis. In the present embodiment, the birefringent optical element 353 is provided in such a direction that the extraordinary ray 74 is shifted vertically downward on the image frame with respect to the ordinary ray 73.

  Next, the operation of the optical path shift unit 32 will be described. FIG. 8 is a diagram schematically showing the polarization state and the optical path in each part of the optical path shift unit 32. FIG. 4A shows the operation state of the optical path shift unit 32 when the switching control signal SC is in the OFF state, and FIG. 4B shows the optical path shift unit 32 when the switching control signal SC is in the ON state. The operation state of is shown.

In FIG. 8A, when the switching control signal SC is in the OFF state, the optical phase modulation element 351 has the red video light Rlp that is vertical linearly polarized light, the green video light Gcp that is right circularly polarized light, and the vertical When blue image light Blp that is linearly polarized light is incident, any image light is output without being phase-modulated.
Next, the phase plate 352 receives red image light (vertical linearly polarized light), green image light (right circularly polarized light), and blue image light (vertical linearly polarized light) output from the optical phase modulation element 351. Thus, the polarization state of only the green image light is converted from right circularly polarized light to vertical linearly polarized light.
Next, the birefringent optical element 353 outputs red image light (vertical linearly polarized light), green image light (vertical linearly polarized light), and blue image light (vertical linearly polarized light) output from the phase plate 352. The three-color image light is incident and travels straight through the birefringent medium as an ordinary ray, and the red image light Rout, the green image light Gout, and the blue image light Bout, all of which are not optically shifted, are output.

In FIG. 8B, when the switching control signal SC is in the ON state, the optical phase modulation element 351 receives the red video light Rlp, the green video light Gcp, and the blue video light Blp. Only the green image light Gcp is phase-modulated from right circularly polarized light to left circularly polarized light, while the other two image lights are output without phase modulation.
Next, the phase plate 352 receives red video light (vertical linearly polarized light), green video light (left circularly polarized light), and blue video light (vertical linearly polarized light) output from the optical phase modulation element 351. Thus, the polarization state of only the green image light is converted from left circularly polarized light to horizontal linearly polarized light.
Next, the birefringent optical element 353 outputs red image light (vertical linearly polarized light), green image light (horizontal linearly polarized light), and blue image light (vertical linearly polarized light) output from the phase plate 352. Of these three colors of image light, two image lights, red image light and blue image light, are incident on the birefringent medium as ordinary rays, and the red image light Rout that does not shift the optical path and the blue image light. The light Bout is output. At the same time, the birefringent optical element 353 causes the green image light to travel obliquely in the birefringent medium as an extraordinary ray, and outputs the green image light Gout whose optical path is shifted vertically downward in the image frame.

  That is, the optical path shift unit 32 repeats the state in which the optical path is shifted vertically downward and the state in which the optical path is not shifted with respect to only the green video light Gout in the video frame period. The green video light Gout includes the first green video light related to the first green video signal G1in in the frame in which the switching control signal SC is in the OFF state, and the second green video signal G2in in the frame in which the switching control signal SC is in the ON state. Includes second green video light. Therefore, the display positions of the red video light Rout, the first green video light, and the blue video light Bout in the video frame coincide with each other, and the second green video light is displayed vertically below the first green video light. The position can be shifted.

  According to the present embodiment, if the thickness of the birefringent medium of the birefringent optical element 353 is adjusted so that the vertically downward optical path shift amount has a length corresponding to the size of 0.5 pixels, the pixel for only the green image The resolution in the shifting direction can be doubled when the pixel is not shifted.

[Second Embodiment]
2nd Embodiment of this invention changes the structure of the optical path shift part 32 contained in the projection type display apparatus 30 among the projection type display systems 1 in 1st Embodiment mentioned above. Therefore, in this embodiment, an optical path shift unit having a different configuration from that of the first embodiment will be described, and description of other common parts will be omitted.

FIG. 9 is a block diagram illustrating a functional configuration of an optical path shift unit included in the video light output apparatus according to the second embodiment of the present invention. As shown in the figure, the optical path shift unit 32a includes a birefringent optical element 353, an optical phase modulation element 351a, and a polarizing plate 354.
The birefringent optical element 353 is the same optical element as that used in the first embodiment. However, in this embodiment, since the birefringent optical element 353 is provided in the first stage of the optical path shift unit 32a, the input / output polarization state is different from that of the first embodiment. That is, the birefringent optical element 353 includes, from the optical unit 31, the red video light Rlp that is vertical linearly polarized light, the green video light Gcp that is right circularly polarized light, and the blue video light Blp that is vertical linearly polarized light. When supplied, the red video light Rlp and the blue video light Blp travel straight through the birefringent medium as ordinary rays, and the green video light Gcp travels straight through the vertical component of the right circularly polarized light as ordinary rays, The horizontal component is advanced as an extraordinary ray in an oblique direction.

The optical phase modulation element 351a receives red image light (vertical linearly polarized light), first green image light (vertical linearly polarized light), and second green image light (horizontal linearly polarized light) from the birefringent optical element 353. ) And blue image light (vertical linearly polarized light) and a switching control signal SC from the optical path switching control unit 33, and the respective polarizations of the image light are polarized based on the switching control signal SC. The light is transmitted without changing the state, or the polarization direction is modulated by 90 degrees and transmitted. The optical phase modulation element 351a is a phase modulation element made of liquid crystal, for example, and can be realized by rotating the polarization direction by the optical rotation function of twisted nematic liquid crystal. Alternatively, the optical phase modulation element 351a may be phase-modulated by the birefringence characteristics of the liquid crystal, and a response speed of milliseconds or less can be obtained with a polarizing element using a ferroelectric liquid crystal element.
The polarizing plate 354 is a polarizer provided to pass only vertical linearly polarized light.

Next, the phase modulation characteristics of the optical phase modulation element 351a will be described. FIG. 10 is a diagram schematically showing the polarization states at the input and output of the optical phase modulation element 351a. FIG. 4A is a diagram showing the polarization state of the optical phase modulation element 351a when the switching control signal SC is in the OFF state, and FIG. 4B is a diagram when the switching control signal SC is in the ON state. It is a figure which shows the polarization state of the optical phase modulation element 351a. In both FIGS. 4A and 4B, the direction of the optical axis O is the same as the traveling direction of the light beam as shown in FIG. In the figure, the polarization state after the output of the optical phase modulation element 351a when linearly polarized light whose polarization azimuth angles are 0 degrees and 90 degrees with respect to the optical axis O is incident is as follows.
As shown in FIG. 5A, when the switching control signal SC is in the OFF state, the polarization state before the incident of the optical phase modulation element 351 and the polarization state after the output are the same. Further, as shown in FIG. 5B, when the switching control signal SC is in the ON state, the output after the output with respect to the incident on the optical phase modulation element 351 of the linearly polarized light whose polarization azimuth is 0 degree and 90 degrees In the polarization state, the polarization direction is modulated by 90 degrees.

  Next, the operation of the optical path shift unit 32a will be described. FIG. 11 is a diagram schematically showing a polarization state and an optical path in each part of the optical path shift unit 32a. FIG. 4A shows the operating state of the optical path shift unit 32a when the switching control signal SC is in the OFF state, and FIG. 4B shows the optical path shifting unit 32a when the switching control signal SC is in the ON state. The operation state of is shown.

  In FIG. 11A, the birefringent optical element 353 receives red video light Rlp that is vertical linearly polarized light, green video light Gcp that is right circularly polarized light, and blue video light Blp that is vertical linearly polarized light. Then, the red image light Rlp and the blue image light Blp travel straight through the birefringent medium as ordinary rays, and the green image light Gcp travels straight through the vertical component of the right circularly polarized light as ordinary rays. The direction component is made to travel in an oblique direction as an extraordinary ray. As a result, the second green image light (horizontal linearly polarized light) is optically shifted vertically downward in the image frame with respect to the first green image light (vertical linearly polarized light).

Next, when the switching control signal SC is in the OFF state, the optical phase modulation element 351a outputs the red image light (vertical linearly polarized light) and the first green image light (vertical) output from the birefringence optical element 353. Linearly polarized light), second green image light (horizontal linearly polarized light), and blue image light (vertical linearly polarized light) are made incident and transmitted without changing their polarization states. .
Next, the polarizing plate 354 includes red video light (vertical linearly polarized light) output from the optical phase modulation element 351a, first green video light (vertical linearly polarized light), and second green video light (horizontal polarized light). Linearly polarized light) and blue image light (vertical linearly polarized light) are incident, and only the second green image light that is horizontal linearly polarized light is blocked, and the other red image light (vertical linearly polarized light) and The first green image light (vertical linearly polarized light) and the blue image light (vertical linearly polarized light) are transmitted, and none of the optical path shifts, the red image light Rout, the green image light Gout, and the blue image light. Output as Bout.

  In FIG. 11B, the birefringent optical element 353 includes red video light Rlp that is vertical linearly polarized light, green video light Gcp that is right circularly polarized light, and blue video light Blp that is vertical linearly polarized light. Is incident, the red image light Rlp and the blue image light Blp travel straight through the birefringent medium as ordinary rays, and the green image light Gcp travels straight through the vertical component of the right circularly polarized light as ordinary rays. Then, the horizontal component is advanced in an oblique direction as an extraordinary ray. As a result, the second green image light (horizontal linearly polarized light) is optically shifted vertically downward in the image frame with respect to the first green image light (vertical linearly polarized light).

Next, when the switching control signal SC is in the ON state, the optical phase modulation element 351a outputs the red video light (vertical linearly polarized light) and the first green video light (vertical) output from the birefringence optical element 353. Linearly polarized light), second green image light (horizontal linearly polarized light), and blue image light (vertical linearly polarized light) are incident, and the polarization direction of each of these image lights is modulated by 90 degrees and transmitted. Let
Next, the polarizing plate 354 includes red video light (horizontal linearly polarized light) output from the optical phase modulation element 351a, first green video light (horizontal linearly polarized light), and second green video light (vertical). Linearly polarized light) and blue image light (horizontal linearly polarized light), only the second green image light that is vertically linearly polarized light is transmitted, and the other red image light (horizontal linearly polarized light), The first green image light (horizontal linearly polarized light) and the blue image light (horizontal linearly polarized light) are shielded, and the second green image light whose optical path is shifted by the optical phase modulation element 351a is converted into the green image light Gout. Output as.

  That is, the optical path shift unit 32 repeats the state in which the optical path is shifted vertically downward and the state in which the optical path is not shifted with respect to only the green video light Gout in the video frame period. The green video light Gout includes the first green video light related to the first green video signal G1in in the frame in which the switching control signal SC is in the OFF state, and the second green video signal G2in in the frame in which the switching control signal SC is in the ON state. Includes second green video light. Therefore, the display positions of the red video light Rout, the first green video light, and the blue video light Bout in the video frame coincide with each other, and the second green video light is displayed vertically below the first green video light. The position can be shifted.

  Also in this embodiment, if the thickness of the birefringent medium of the birefringent optical element 353 is adjusted so that the vertically downward optical path shift amount corresponds to the size corresponding to 0.5 pixels, the pixel shift of only the green image is performed. The resolution in the direction can be doubled when the pixel is not shifted.

Further, according to the present embodiment, the optical path shift unit 32a does not require the phase plate 352 that is used in the optical path shift unit 32 in the first embodiment and converts the polarization state of only the green light wavelength component of the image light. In addition, since the polarizing plate 354, which is a cheaper and more general polarizer, is used, it can be realized at a lower cost than the optical path shift unit 32.
Further, since the optical path shift unit 32a in the present embodiment can block the crosstalk light generated by the optical phase modulation element 351a by providing the polarizing plate 354 at the final stage, the projection type in the present embodiment. The display device can display an image having a higher contrast than the projection display device 30 in the first embodiment.

[Third Embodiment]
In the third embodiment of the present invention, a projection display system in which the display contrast of the projection display system 1 in the first embodiment described above is further improved will be described. In the first embodiment, when the projection display device 30 performs projection display by alternately switching the first green video signal G1in and the second green video signal G2in shifted in pixels with respect to the first green video signal G1in. In addition, when only the first green image based on the first green image signal G1in is supposed to be displayed, the second green image based on the second green image signal G2in is displayed in a leaked manner, thereby causing crosstalk. possible. Therefore, the influence of the response characteristic of the optical phase modulation element 351 on the contrast of the green video light Gout when only the response speed delay of the optical phase modulation element 351 is considered will be described below.

FIG. 12 is a timing chart showing the relationship between the video frame switching timing and the response timing of the optical phase modulation element 351. In the figure, the frame switching timing 121 and the response timing 122 representing the response characteristic of the optical phase modulation element 351 are represented by a time axis that is the horizontal axis and a modulation degree axis that is the vertical axis (the maximum value is “1”). .) Are superimposed and displayed. According to the figure, the projection display apparatus 30 displays the first green video in the section where the frame switching timing 121 is “1”, and the second green color in the section where the frame switching timing 121 is “0”. Display video. The operation timing in the time axis direction of the switching control signal SC output from the optical path switching control unit 33 substantially coincides with the frame switching timing 121.
In the figure, a region S1 is a first green video displayed at a location where the first green video is to be displayed, and a region N1 is a second green video leaked at a location where the first green video is to be displayed, a region S2 is the second green video displayed at the place where the second green video should be displayed, and the area N2 is the first green video leaked to the place where the second green video should be displayed.

  In FIG. 12, the contrast C1 of the first green image, the contrast C2 of the second green image, the crosstalk T1 of the first green image, and the crosstalk T2 of the second green image are expressed by Expression (7). The

In FIG. 12, the rising response of the optical phase modulation element 351 is r (t), the falling response is f (t), the rising response time is t _r , the falling response time is t _f , and the maximum modulation of the optical phase modulation element 351 is performed. When the degree is T _max and the frame time is T, the region S1, the region N1, the region S2, and the region N2 are each expressed by Expression (8).

Here, in order to simplify the calculation, the response of the optical phase modulation element 351 is approximated linearly. FIG. 13 is a timing chart showing the relationship between the video frame switching timing and the linearly approximated response timing of the optical phase modulation element 351. In this figure, the frame switching timing 121 and the linearly approximated response timing 122a of the optical phase modulation element 351 are represented by a time axis as the horizontal axis and a modulation degree axis (the maximum value is “1”). ) In a superimposed manner.
In FIG. 13, a region S1, a region N1, a region S2, and a region N2 are each represented by Expression (9).

  From Expression (9), the first green image contrast C1, the second green image contrast C2, the first green image crosstalk T1, and the second green image crosstalk T2 in FIG. 10).

According to Expression (10), if the modulation degree of the optical phase modulation element 351 is low (that is, T _max is small), the contrast C2 of the second green image is lowered, so that the optical phase modulation element 351 is sufficient. Neat phase modulation characteristics are required. For example, the optical phase modulation element 351 is constituted by a nematic liquid crystal, T = 1/60 _{sec, t} r = 3 _{ms, t} f = 6 _ms and T max = 0.95, the calculation of equation (10) Thus, C1 = 0.670, C2 = 0.719, T1 = 0.198, and T2 = 0.163.

FIG. 14 is a graph showing the relationship between the response speed and contrast of the optical phase modulation element 351 made of liquid crystal. In the figure, the response speed t _LC when nematic liquid crystal is used is several milliseconds, and the contrast C in that case is smaller than 0.9. Further, the response speed t _LC when using the ferroelectric liquid crystal is 1 millisecond or less, and the contrast C in that case is 0.9 or more.

  In the present embodiment, the contrast of the projection display device is improved by switching the optical phase modulation element 351 by an amount corresponding to the response time earlier than the switching timing of the video frame. Specifically, the optical path switching control unit 33 that generates the switching control signal SC based on the frame synchronization signal FT switches the switching control signal that is earlier by a predetermined time than the start of one frame time indicated by the frame synchronization signal FT. SC is output.

FIG. 15 is a timing chart showing the relationship between video frame switching timing and linearly approximated response timing of the optical phase modulation element 351 when the contrast is improved. In the figure, the frame switching timing 121 and the response timing 122b approximated to the linear shape of the optical phase modulation element 351 are represented by a time axis that is a horizontal axis and a modulation degree axis that is a vertical axis (not shown). "". "). If optical path switching control unit 33, than at the start of one frame time indicated frame synchronization signal FT and to output the switching control signal SC to replace quickly switching only drive shift time t _s, as shown in the figure, the response timing 122b is shifted in the early direction by driving the shift time _{t s} against switching timing 121 of the frame.
In FIG. 15, the region S1, the region N1, the region S2, and the region N2 are each represented by Expression (11).

  From Expression (11), the first green image contrast C1, the second green image contrast C2, the first green image crosstalk T1, and the second green image crosstalk T2 in FIG. 12).

16, in the case where the contrast is improved, which is a graph showing the relationship between the contrast C and the driving shift time t _s. This figure, the optical phase modulation element 351 is constituted by a nematic liquid crystal, T = 1/60 _{sec, t} r = 4 _{ms, t} f = 6 _ms, in the case of the _{T max} = 1, the first green image of showing the contrast C1, the contrast C2 of the second green image, the relation between the driving shift time t _s.
In the figure, the drive shift time t _s of the first green image contrast C1 is maximum, a position where the slope of the curve becomes 0 C1 (t _s), obtained by clogging formula (13).

From equation (13), the drive shift time _{t s} shown in equation (14) is obtained.

The optical path switching control unit 33 calculates the expression (14) using the rising response time _tr and the falling response time t _f of the response of the optical phase modulation element 351, and thereby the contrast C1 and the first green video image The contrast of the two green images can be maximized.

Drive shift time t _s is or based the rise response time t _r of the response of the optical phase modulation element 351, the characteristic data of the phase modulation media such as liquid crystals or measuring the fall response time t _f, in advance formula It is obtained by the calculation of (14). Or, the drive shift time t _s by measuring the contrast of the green image by actually performing image projection from the projection type display device, is determined by the adjustment.

  The optical path switching control unit 33 individually sets the switching timing of the switching control signal SC in correspondence with the rising response r (t) and the falling response f (t), which are the response characteristics of the optical phase modulation element 351. You may make it adjust to.

[Modification of Third Embodiment]
In the third embodiment described above, the projection display device 30 alternately displays the first green image and the second green image for each frame of the image. In the modification of the third embodiment, a time for generating a black display is provided between the first green image and the second green image to limit the image display time of the first green image and the second green image. Will be described.
Specifically, when the video signal switching device 20 generates a mask control signal that is turned on at the rise time _tr and the fall time t _f of the response shown in FIG. 15, and the mask control signal is on. In addition, the output of the green video signal Gin is cut off or switched to the black image signal. Thus, at the rise time t _r and the fall time t _f of the response of the optical phase modulation element 351, it is possible to display by green image Gout black.

  If the display time in each frame of the first green video and the second green video is αT (0 <α <1) and αT <T-tr, αT <T-tf as conditions, the region S1, the region N1, and the region S2 and the region N2 are expressed by Expression (15) to Expression (18), respectively.

  Here, if it defines like Formula (19), Formula (15) and Formula (16) will turn into Formula (20) and Formula (21).

17, in the case where the contrast is improved by the insertion of the black is a graph showing the relationship between the contrast C and the driving shift time t _s. This figure, the optical phase modulation element 351 is constituted by a nematic liquid crystal, T = 1/60 _{sec, t} r = 4 _{ms, t} f = 4 _{ms, T max = 0.95, α =} 0.5 and in the case of shows the contrast C1 of the first green image, and the contrast C2 of the second green image, the relation between the driving shift time t _s. As can be seen in the figure, by inserting black, the contrast can be improved compared to the third embodiment shown in FIG.

[Fourth Embodiment]
When the blue light display element 316, the red light display element 320, and the green light display element 322 included in the optical unit 31 of the projection display device 30 in the first embodiment are liquid crystal display elements, for example, Due to restrictions, the entire display screen cannot be rewritten at once. FIG. 18 is a diagram schematically showing a state (frame overwriting state) in which the first green video frame is rewritten to the second green video frame when the green light display element 322 is a liquid crystal display element. FIG. 5A shows the state of the display surface during the rewriting of the first green video frame G1 as the previous frame image to the second green video frame G2 as the current frame image. FIG. 4B is a diagram showing, in time series, how video frames are sequentially rewritten, with the horizontal direction being the time direction and the vertical direction being the horizontal lines of the screen. As shown in FIGS. 6A and 6B, in the middle stage where the current frame image is overwritten on the previous frame image, two frame images of the frames G1 and G2 are mixed on the same display screen. Become.

Therefore, in the present embodiment, a black frame image is inserted between the first green video frame G1 and the second green video frame G2, and the switching cycle of the switching control signal SC between the OFF state and the ON state is set to 2. In addition, the phase of the switching control signal SC is shifted by the horizontal display period for each horizontal line.
Specifically, the video signal switching device 20 inserts a black image for one frame between the first green frame image of the first green video signal G1in and the second green frame image of the second green video signal G2in. And output as a green video signal Gin.
The signal generator 10 supplies the horizontal synchronization signal in the video control signal to the optical path switching control unit 33 together with the frame synchronization signal FT. The optical path switching control unit 33 is based on the horizontal synchronization signal and the frame synchronization signal FT. Thus, a switching control signal SC having a cycle twice the cycle of the frame synchronization signal FT and the phase being shifted for each horizontal line by the horizontal display period is generated and supplied to the optical path shift unit 32.
FIG. 19 is a diagram schematically illustrating the relationship between the switching of frame images and the switching control signal SC. This figure shows the timing of the switching control signal SC corresponding to the first line (Top), the middle line (Middle), and the last line (Bottom) among the horizontal lines from the first line (Top) to the last line (Bottom). It is shown.

[Fifth Embodiment]
In the fifth embodiment of the present invention, the optical phase modulation element 351 included in the optical path shift unit 32 in the first embodiment is divided into two near the middle line of the video frame, and the phase of switching each optical phase modulation element is changed. An example of driving by shifting will be described.
FIG. 20 is a block diagram illustrating functional configurations of an optical path shift unit and an optical path switching control unit included in the video light output apparatus according to the present embodiment. In the same figure, the optical path switching control unit 33b receives the supply of the frame synchronization signal FT from the signal generator 10, and switches the upper half frame including the first line of the display unit of the green light display element 322 to the line near the middle. A switching control signal SCU for controlling and a switching control signal SCD for switching control of the lower half frame including the line near the middle of the display portion of the green light display element 322 to the last line are generated.

The optical path shift unit 32b receives supply of the red video light Rlp, the green video light Gcp, and the blue video light Blp from the optical unit 31, and supplies the switching control signals SCU and SCD from the optical path switching control unit 33b. receive.
The optical path shift unit 32b is on the upper half frame of the red video by the red video light Rlp, the blue video by the blue video light Blp, and the first green video by the green video light Gcp according to the switching timing of the switching control signal SCU. The pixel positions coincide with each other, and the pixel position on the upper half frame of the second green image in the green image light Gcp is equal to or less than one pixel in the vertical direction with respect to the pixel position on the upper half frame of the first green image (for example, The red video light RUout, the green video light GUout, and the blue video light BUout, whose optical paths are set so as to be shifted by 0.5 pixel), are output.

  In addition, the optical path shift unit 32b, according to the switching timing of the switching control signal SCD, the lower half frame of the red video by the red video light Rlp, the blue video by the blue video light Blp, and the first green video by the green video light Gcp. The upper pixel positions coincide with each other, and the pixel position on the lower half frame of the second green image in the green image light Gcp is one pixel or less in the vertical direction with respect to the pixel position on the lower half frame of the first green image ( For example, the red video light RDout, the green video light GDout, and the blue video light BDout whose optical paths are set to be shifted are output.

FIG. 21 is a schematic perspective view of the element surface of the optical phase modulation element included in the optical path shift unit 32b. FIG. 5A is a diagram showing a state in which light-transmitting electrodes 211U and 211D are provided on the element surface of the optical phase modulation element so as to separate the frame vertically in the vicinity of the intermediate horizontal line. Since a gap of several μm is generated between the electrode 211U and the electrode 211D for reasons of the manufacturing process, reasons of electrical characteristics, and the like, this gap is a portion through which green image light that is not phase-modulated is transmitted.
FIG. 5B is a diagram showing a state in which a light shielding object is provided in a gap portion between the electrode 211U and the electrode 211D. As shown in the figure, a light shielding member 212 may be provided in a gap portion between the electrode 211U and the electrode 211D so that green image light that is not phase-modulated is not transmitted. The material of the light shield 212 is, for example, aluminum.
The gap between the electrodes 211U and 211D and the light shield 212 as shown in FIG. 5A are optically separated from the display element surface and do not appear as an image in the projected image, so that the image quality is not impaired.

FIG. 22 is a timing chart showing operation timings of the frame synchronization signal FT, the switching control signal SCU, and the switching control signal SCD. As shown in the figure, the frame synchronization signal FT is a signal that generates a pulse in a predetermined period at the head of each frame in the frame period of the video, as in the first embodiment.
The switching control signals SCU and SCD are toggle signals that alternately repeat the OFF state and the ON state at a cycle twice that of the frame synchronization signal FT. The OFF state is a 0 (zero) value, and the ON state is an arbitrary level. Value. Both the switching control signals SCU and SCD have an operation timing for switching the state during the black video frame period, and the switching control signal SDC is shifted in phase by the drive shift time t _{sc with} respect to the switching control signal SCU. . The drive shift time t _sc is preferably about half of one frame time. The period in which the switching control signals SCU and SCD are in the OFF state corresponds to the frame period of the first green frame video, and the period in which the switching control signals SCU and SCD are in the ON state corresponds to the frame period of the second green frame video. To do.

FIG. 23 is a graph showing the relationship between the number of horizontal lines and contrast when the optical phase modulation element of this embodiment is used. This figure, the optical phase modulation element constituted by a nematic liquid crystal, T = 1/60 _{sec, t} r = 4 _{ms, t} f = 4 _{ms, α = 0.5, T max =} 0.95, t The relationship between the number of horizontal lines and the contrast C1 of the first green image when _sc = 4 milliseconds is shown.
According to the figure, the contrast C1 of the first green image is substantially “1” over the entire frame.
The number of divisions of the optical phase modulation element 351 is not limited to two and may be divided into three or more. In that case, the optical path switching control unit 33b drives each region while shifting the time.

[Sixth Embodiment]
In the present embodiment, in order to prevent unnecessary afterimage light as shown in FIG. 18 from being projected, a physical shutter mechanism is disposed at a desired location after the optical phase modulation element 351 to provide afterimage light. An example of shielding light will be described.
FIG. 24 is a diagram schematically showing a rotary shutter, which is a physical shutter mechanism, from the image light incident side. As shown in the figure, the rotary shutter 241 is provided with a plurality of fan-shaped openings 243 in a shutter plate 242 on a circular plate. The rotary shutter 241 has, for example, a light beam of red video light Rout, green video light Gout, and blue video light Bout between the optical path shift unit 32 and the projection optical system 34 in the projection display device 30. It is provided at a position passing through H.243.

The rotational angular velocity of the rotary shutter 241 and the position of the opening 243 are set and adjusted in advance so that the image light of the previous frame shown in FIG.
The rotary shutter 241 may be provided between the projection optical system 34 and the screen.

[Seventh Embodiment]
In the first embodiment, the example in which one optical path shift unit 32 is provided in the projection display device 30 and the pixel shift is performed by 0.5 pixels in the vertical direction on the screen has been described. In the present embodiment, an example will be described in which N stages of optical path shift units (N is an integer of 2 or more) are provided, and the optical path shift of image light is set to 2 to the Nth power.
FIG. 25 is a block diagram illustrating a functional configuration of an optical path shift unit in the video light output apparatus according to the present embodiment. As shown in the figure, the optical path shift unit 32c in the present embodiment has a configuration in which a λ / 4 plate 355 is added to the final stage of the configuration inside the optical path shift unit 32 in the first embodiment. The λ / 4 plate 355 converts the polarization state of the green light wavelength component of the image light supplied from the birefringent optical element 353 from vertical or horizontal linearly polarized light to right circularly polarized light.

  FIG. 26 is a block diagram illustrating a functional configuration of the optical path shift units 32c-1 to 32c-4 and the optical path switching control unit when the four stages of optical path shift units 32c are applied. In the figure, the optical path switching control unit 33c receives the supply of the frame synchronization signal FT from the signal generator 10 and switches the switching control signals SC1, SC2, SC3 so that 16 combinations of states are obtained in 16 frame periods of the video. , SC4 is generated and output. For example, the optical path switching control unit 33c includes a counter calculation processing unit that counts up an input pulse using the frame synchronization signal FT as an input signal. The optical path shift units 32c-1 to 32c-4 are obtained by cascading four (N = 4) optical path shift units 32c.

As shown in FIG. 26, when four optical path shift units 32c are cascade-connected, 2 4 = 16 optical paths can be realized. Since the optical path shift amount of the optical path shift unit 32c alone is determined by the thickness of the birefringent medium included in the birefringent optical element 353 in the light traveling direction, the pixel shift direction of each optical path shift unit 32 and the thickness of the birefringent medium are determined. By making them the same, an integral multiple optical path shift amount can be obtained.
In addition, in order to achieve high resolution by the pixel shifting method, it is required that the pixel position accuracy be about 1/20 of that of one pixel. Therefore, by providing N stages of optical path shift units 32c, it is possible to finely adjust the amount of pixel shift with an accuracy of 1 / N.

[Eighth Embodiment]
In the eighth embodiment of the present invention, an example in which the shift amount of the optical path shift by the birefringent optical element can be adjusted will be described. The optical path shift unit in the present embodiment is provided with a birefringent optical unit capable of adjusting the optical path shift amount, instead of the birefringent optical element 353 in the first embodiment. FIG. 27 is a block diagram showing a schematic configuration of a birefringence optical unit included in the optical path shift unit in the image light output device according to the present embodiment. As shown in the figure, the birefringent optical unit 271 includes wedge-shaped saval plates 271a and 271b in which two birefringent plates are bonded to form a wedge shape. The birefringent optical unit 271 is combined with the wedge-shaped Savart plates 271a and 271b such that the narrower ends of the wedge-shaped Savart plates 271a and 271b are offset from each other in the image light incident direction. The wedge-shaped sabal plate 271a is movably disposed back and forth in the direction of arrow A, which is perpendicular to the incident direction of the image light, and the wedge-shaped savar plate 261b is fixedly disposed.
The birefringent optical unit 271 adjusts the distance d between the ordinary ray and the extraordinary ray of the light beam emitted from the wedge-shaped savar plate 271b by moving the wedge-shaped savar plate 271a back and forth in the direction of arrow A. Can do.

[Other embodiments]
In the first embodiment of the present invention, the projection display device 30 has a configuration in which the optical path shift unit 32 is provided between the optical unit unit 31 and the projection optical system 34. The arrangement position of the optical path shift unit 32 is not limited to this. For example, the optical path shift unit 32 may be arranged after passing through the projection optical system 34.
In the first embodiment, an example in which pixel shifting is performed on a green image among the images of the three primary colors has been described. However, the image on which pixel shifting is performed is not limited to a green image and may be an image of any color. That is, as shown in the first embodiment, the signal generation device 10 supplies the video signal switching device 20 with two types of specific color video signals (first and second video lights) for the specific color video in which the pixels are shifted. Then, the optical unit 31 outputs the specific color image in the right circular polarization polarization state and outputs the image other than the specific image (third image light) in the vertical linear polarization direction. And output.

In addition, although the first embodiment has been described with respect to an example in which progressive scanning video is targeted, the present invention can be applied to interlaced video in addition to this. In the projection display system using the interlaced scanning image, the first green image signal G1in and the second green color are used by using a field synchronization signal synchronized with the field period of the interlaced scanning image instead of the frame period FT. The video signal G2in is shifted by one pixel in the vertical direction.
In the first embodiment, the example in which the image light output device is included in the projection display device 30 has been described. In addition, the image light output device according to the embodiment of the present invention can be applied to a direct-view display device such as a liquid crystal display, an organic EL (Electro-Luminescence) display, and a plasma display. In this case, the image light output device may be incorporated at a position after the display light emission of the display element included in the direct view display device.

  In each of the fourth to sixth embodiments of the present invention, an example in which a black video signal is inserted (fourth and fifth embodiments) and an example in which a rotary shutter 241 is used (sixth embodiment). And explained. In addition to this, for example, by blinking the light source unit 311 included in the optical unit unit 31, video readout light from each display element is intermittently emitted, and the projection display device 30 projects unnecessary afterimage light. It is possible to prevent the image quality from deteriorating. It is desirable to apply an LED (Light Emitting Diode) light source capable of high-speed blinking operation as the light source unit 311 in the case of operating in this way.

  Each embodiment from the third embodiment to the eighth embodiment of the present invention has been described as an embodiment based on the first embodiment. Among these, the third embodiment to the sixth embodiment and the eighth embodiment are described. About embodiment, it can be based on 2nd Embodiment.

  The projection display system according to each of the embodiments described above can be applied to a stereoscopic video display system. For example, as shown in FIG. 28, the projection light from the projection display system according to each embodiment of the present invention is transmitted through a compound eye lens array plate 40 provided with a microlens array in which a large number of element lenses are arranged and a lenticular. Project. As a result, it is possible to project and display a high-definition video and a super-high-definition stereoscopic video in which pixels are shifted.

In addition, in the projection display systems according to the above-described embodiments, the pixel positions on the frames of the red video, the blue video, and the first green video match, and the pixel positions on the frame of the second green video are the first green. By setting the optical path shift direction so that it is shifted by less than one pixel (for example, 0.5 pixel) in the vertical direction with respect to the pixel position on the video frame, the vertical resolution of only the green video is set to the pixel. In this example, the resolution is doubled when the shift is not performed.
In the projection display system, in addition to the above example, the pixel position on the second green video frame is less than one pixel in the horizontal direction with respect to the pixel position on the first green video frame (for example, 0.5 pixel). The direction of the optical path shift may be set so as to deviate. Accordingly, the projection display system can double the horizontal resolution of only the green image to the resolution when the pixel is not shifted.
Further, the projection display system has a pixel position on the second green image frame that is less than one pixel in the horizontal direction and the vertical direction with respect to the pixel position on the first green image frame (for example, 0.5 pixels each). The direction of the optical path shift may be set so as to be shifted (by a pixel) (that is, shifted in an oblique direction). Thus, the projection display system can double the resolution in the horizontal direction and the vertical direction of only the green image to the resolution in the case where the pixel is not shifted.

  As mentioned above, although embodiment of this invention was explained in full detail with reference to drawings, the concrete structure is not restricted to this embodiment, The design etc. of the range which does not deviate from the summary of this invention are included.

DESCRIPTION OF SYMBOLS 1 Projection type display system 10 Signal generator 20 Image | video signal switching device 30 Projection type display device 31 Optical unit part 32, 32a, 32b, 32c Optical path shift part 33, 33b, 33c Optical path switching control part 34 Projection optical system 40 Compound eye lens arrangement | sequence Plates 211D and 211U Electrodes 212 Shields 241 Rotating shutters 242 Shutter plates 243 Openings 271 Birefringent optical units 271a and 271b Wedge-shaped Savart plates 351 and 351a Optical phase modulation elements 352 Phase plates 353 Birefringent optical elements 354 Polarizing plates 355 λ / 4 Board

Claims (1)

An optical path switching control unit for outputting a switching control signal for alternately switching the first and second states at a predetermined period;
The first and second image lights of a predetermined color are supplied with the image light of the predetermined color that is alternately switched at the predetermined period and the third image light of a color different from the predetermined color, and the optical path When the switching control signal is supplied from the switching control unit and the switching control signal is in the first state, the first and third video lights are transmitted between the input and output of the video light output device. While the optical path is output without shifting, when the switching control signal is in the second state, the second video light is output to the output side while shifting the optical path with respect to the input side of the video light output device. An optical path shift unit,
Equipped with a,
The optical path shift unit is
The video light of the predetermined color and the third video light are supplied, and the video light of the predetermined color is split to transmit one video light straight and refract the other video light. A birefringent optical unit that shifts and transmits the optical path and transmits the third image light in a straight line; and
When the switching control signal is in the first state, the polarization direction of the first output image light from the birefringent optical unit is not modulated, while when the switching control signal is in the second state , An optical phase modulator that modulates the polarization direction of the first output image light;
For the second output video light from the optical phase modulation unit, a polarizing plate that transmits only video light of a predetermined polarization direction component,
Video light output device according to claim Rukoto equipped with.

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