JP2008281774A - Color holography display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a color holography display device capable of securing a wide viewing area in a horizontal direction and displaying a moving image, without requiring increase in a scale of the device. <P>SOLUTION: The color holography display device 1 is configured to irradiate an image hologram displayed by a spatial optical modulator 4 that is controlled by a control means 10 with reading light and to display the reproduced image as a three-dimensional image. The color holography display device 1 includes a color filter 5 having three primary colors RGB, disposed facing the spatial light modulator for displaying the hologram and along the pixel pitch of the spatial light modulator. In the color filter, a color corresponding to pixels in a horizontal direction is one of three primary colors RGB, and also, the colors shown by the pixels in the horizontal direction are vertically arranged at the same cycle with reference to respective colors RGB. <P>COPYRIGHT: (C)2009,JPO&amp;INPIT

Description

  The present invention relates to a color holographic display device that displays a three-dimensional optical image of an object as a color holographic image.

  In general, in order to realize a color holographic image with a moving image, the conventional technology using a spatial light modulator has a configuration in which a reproduced image is formed using three spatial light modulators, and the same display surface of the spatial light modulator. These are roughly divided into two configurations for forming a reproduced image using the three primary colors.

  The configuration of a conventional apparatus will be described with reference to FIGS. FIG. 6 is a schematic diagram schematically illustrating a state in which a conventional holographic display device is configured using three spatial light modulators, and FIG. 7 is a configuration of a color filter used in the conventional color holographic display device. FIG. 8 is a front view schematically showing, FIG. 8 is a front view schematically showing another configuration of a color filter used in a conventional color holography display device, and FIG. 9 is a case where a hologram is constituted by an element having a pixel structure. It is a top view which shows typically the state of the horizontal viewing area or the vertical viewing area at the time of reproduction | regeneration of.

  As shown in FIG. 6, as a device having the first configuration, the holographic display device 100 displays holograms of three primary colors on different spatial light modulators 101, 102, and 103, and the spatial light modulators 101, 102, and 103 are displayed. This is an apparatus that uses a technique for optically synthesizing modulated light by the laser beam.

  That is, the holographic display device 100 includes spatial light modulators 101, 102, and 103 corresponding to green, red, and blue colors, and irradiation lenses 105 and 106 that irradiate the spatial light modulators 101, 102, and 103 with readout light. Irradiating means 107A, 107B, and 107C, respectively, a half mirror 104B disposed at the intersection of the optical path of the spatial light modulator 102 and the optical path of the spatial light modulator 103, and the optical path and spatial light modulator of the half mirror 104B And a half mirror 104A disposed at the intersection of the 101 optical paths.

  Further, as shown in FIG. 7, the apparatus having the second configuration arranges the color filter 120 so as to face the spatial light modulator, and similarly to the color image display, the red filter 121, the green filter 122, and the blue filter are arranged. Each of the 123 RGB color filters is arranged in a vertical stripe pattern so that the three primary color holograms are displayed on one spatial light modulator and reproduced with white light. (For example, refer to Patent Documents 1 and 2).

Further, as shown in FIG. 8, as another configuration for displaying the three primary color holograms with one spatial light modulator, the color filter 130 has a checkered pattern of the red filter 131, the green filter 132, and the blue filter 133. Are arranged so as to face the spatial light modulator.
JP-A-10-097174 Japanese Patent Laid-Open No. 08-201630

However, the conventional color holography technology has the following problems.
In the holographic display device 100 shown in FIG. 6, since the holographic image of each color is generated independently, the scale of the device becomes large.
Further, the color filters 120 and 130 shown in FIGS. 7 and 8 have the same vertical stripe pattern arrangement or checkered pattern arrangement as that for normal color image display, so the same color does not continue in the horizontal direction. It is a configuration.

  Therefore, as shown in FIG. 9, when the sub-sampling is performed in the horizontal direction, the pixel pitch becomes large particularly when the spatial light modulator is a display unit that can handle moving images such as liquid crystal or DMD. The viewing zone is narrowed. In addition, in a display means such as liquid crystal or DMD that can currently display only in a state larger than the pixel pitch that is originally required for a color hologram, if sampling resulting in a wider pixel pitch is performed, the reproduction of the reproduced image is also adversely affected. I was supposed to.

  Furthermore, the color filter described in Patent Document 2 describes an example in which green filters are arranged so as to be continuous in the horizontal direction. However, since the red filter and the blue filter are not configured to be continuous in the horizontal direction, when the viewing area of the green filter is 1, the viewing area of the red filter and the blue filter is halved and the horizontal viewing area is widened. It is impossible to take.

  The present invention has been devised in view of the above problems, and provides a color holographic display device capable of displaying a moving image while ensuring a large horizontal viewing area without increasing the scale of the device. For the purpose.

  The color holographic display device according to the present invention has the following configuration in order to achieve the object. That is, the color holography display device is a color holography display device that displays a reproduced image as a three-dimensional image by irradiating readout light onto a hologram of an image displayed on the spatial light modulator under the control of the control means. A color filter having three primary colors of RGB arranged facing each other along the pixel pitch of the spatial light modulator for displaying the color, wherein the color filter corresponds to any of the three primary colors of RGB corresponding to the pixels in the horizontal direction. One color and the color indicated by the pixels in the horizontal direction are arranged in the same period in the vertical direction with respect to each color of RGB.

  With this configuration, the color holographic display device can be used in the horizontal direction even if subsampling is performed from the state in which the green filter, the red filter, or the blue filter, which are the same color filters, are arranged in the horizontal viewing zone. Since RGB is arranged in the same period in the vertical direction and the same color is continuous, the reduction of the horizontal viewing zone is minimized.

  Further, the color holography display device is a color holography display device that displays readout images as three-dimensional images by irradiating readout holograms on holograms of images displayed on the spatial light modulators under the control of the control means. In the spatial light modulator for displaying the color, the color corresponding to the pixel in the horizontal direction is one of the three primary colors of RGB, and the color indicated by the pixel in the horizontal direction is the same in the vertical direction with respect to each color of RGB It was set as the structure arrange | positioned with a period.

  With this configuration, the color holography display device does not need to adjust the position of the color filter, and the pixels of the same color are arranged in the horizontal viewing zone, and the RGB has the same period in the vertical direction. Therefore, the horizontal viewing area is not narrowed.

In the color holography display device, the spatial light modulator has a light modulation means capable of amplitude modulation or phase modulation.
With this configuration, the color holographic display device can make the light and darkness of the interference fringes of the object displayed by the spatial light modulator clearer. The light modulating means can be realized by adjusting the voltage applied to the electrodes constituting the pixel.

Furthermore, in the color holography display device, the control means includes a band limiting filter that removes a aliasing component according to vertical subsampling of the spatial frequency of the modulation signal.
With this configuration, the color holography display device can display a reproduced image reproduced by the readout light more clearly.

The color holographic display device according to the present invention has the following excellent effects.
Since the color holography device continuously arranges any of the three primary colors of RGB in the horizontal direction, a stereoscopic image having a wide viewing area in the horizontal direction is displayed as a moving image as a color hologram reproduction image without enlarging the device. It becomes possible.

  The color holography device has light modulation means that performs amplitude modulation or phase modulation, or a band limiting filter that removes aliasing components according to vertical sub-sampling, so that the color hologram reproduction image can be displayed more clearly. can do.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a perspective view schematically showing the overall configuration of the color holography display device, FIG. 2 is a block diagram schematically showing the overall configuration of the color holography display device, and FIG. 3 is a color used in the color holography device. It is a front view which shows the structure of a filter typically.

  As shown in FIGS. 1 and 2, the color holographic display device 1 is provided with a light irradiation means 2, a lens system 3 disposed in the optical path of the light irradiation means 2, and a light path of the lens system 3. The spatial light modulator 4 and the color filter 5, and the control means 10 for the spatial light modulator 4 are provided.

  The light irradiation means 2 irradiates readout light (white light) for reading out holography, and uses, for example, a laser irradiation apparatus that irradiates laser light. This light irradiating means 2 irradiates white or a white laser beam in which green, red and blue are mixed.

  The lens system 3 is for converting the readout light from the light irradiation means 2 into parallel light. Here, a light source lens 3a and an irradiation lens 3b that converts the diffused light from the light source lens 3a into parallel light are provided. In this lens system 3, the light source lens 3a and the irradiation lens 3b are arranged based on the focal length, the curvature, etc. so that the readout light from the light irradiation means 2 can be output as parallel light.

  The spatial light modulator 4 displays the hologram as interference fringes and displays the video as a moving image by appropriately changing the displayed interference fringes. As the spatial light modulator 4, an electrically driven liquid crystal panel is used. This electrically driven liquid crystal panel can display interference fringes and diffract light to display a hologram using a high-definition liquid crystal display. The pixel pitch of the electrically driven liquid crystal panel as the spatial light modulator 4 shown here is 0.5 to 5 μm as an example. Further, here, the spatial light modulator 4 is configured to be able to perform amplitude modulation or phase modulation, as will be described later.

  As shown in FIG. 3, the color filter 5 is configured by sequentially arranging a green filter 5 </ b> A, a red filter 5 </ b> B, and a blue filter 5 </ b> C corresponding to one column of pixels in the horizontal direction in the spatial light modulator 4. . That is, the color filter 5 is arranged so that the green filter 5A, the red filter 5B, and the blue filter 5C are horizontal stripes. The color filter 5 is formed such that each of the green filter portion 5a, the red filter portion 5b, and the blue filter portion 5c is disposed at a position facing each pixel of the spatial light modulator 4.

  The color filter 5 is formed such that, for example, the vertical intervals of the green filter 5A, the red filter 5B, and the blue filter 5C correspond to the vertical pixel pitch of the spatial light modulator 4. Here, the color filter 5 is arranged so that the three primary colors of the green filter 5A, the red filter 5B, and the blue filter 5C are continuous in the order (same period) in the vertical direction. Therefore, pixels of the same color can be subsampled in the vertical direction, so that the vertical viewing area can be the same as that of RGB.

  Note that the color holography display device 1 may include a band limiting filter 6 that removes aliasing components in accordance with vertical sub-sampling. The band limiting filter 6 is configured to remove components having a frequency equal to or higher than the Nyquist frequency of a signal input when sub-sampling is performed in the computer generated hologram creating means 12 described later.

  The control means 10 performs an operation of storing a reconstructed image created in advance and outputting it to the spatial light modulator 4 at a predetermined timing. The control means 10 is, for example, a configuration of a general personal computer, and includes an input means 10a such as a keyboard and a mouse, a video selection means 10b for selecting a video based on character information input from the input means 10a, Storage means 10c for storing the image of the hologram (interference fringe) selected via the image selection means 10b, and output for outputting the image of the hologram stored in the storage means 10c to the spatial light modulator 4 at a predetermined timing. And control means 10d.

  The output control means 10d reads the image of the hologram selected by the image selection means 10b from the storage means 10c, and stores the image of the hologram stored in the display memory 10e at a predetermined timing ( For example, the output unit 10f outputs 30 sheets per second). Here, the output means 10f plays the role of the light modulation means by changing the voltage applied to the electrode of each pixel of the spatial light modulator 4. Here, depending on the characteristics of the element, the case of changing the density (depending on the combination of the amplitude and the polarizing plate) by changing the voltage and applying the voltage and the case of changing the phase are performed.

  In addition, when changing the phase, for example, the liquid crystal molecules are used in parallel with the substrate, and the configuration after that is used, and an external voltage is applied to the liquid crystal layer via the pixel electrode. By tilting the liquid crystal molecules, only the phase of the input light can be modulated two-dimensionally by 2π radians or more.

  Note that the color holography display device 1 is created in advance as a computer generated hologram as an example when reading a hologram image. For example, an image input means 11 such as an image scanner or a CCD camera for inputting an image is connected to the control means 10, and a computer generated hologram creating means 12 for creating a hologram from an image or object input by the image input means 11 is provided. It is configured.

  Further, when the hologram is created by the computer generated hologram creating means 12, since the pixel pitch of the spatial light modulator 4 is known in advance, if there is a frequency component higher than the Nyquist frequency (sampling frequency), the high frequency component is used. Holograms are created through a band limiting filter 6 that removes aliasing distortion (components).

That is, the control means 10 first reads the data of the object to be displayed by the image input means 11, and when the high frequency signal exceeding the preset frequency is calculated when calculating the interference fringes from the input data, The limiting filter 6 is configured to remove aliasing distortion due to high frequency components.
Therefore, the computer generated hologram 12 gives the object inputted to the two-dimensional or three-dimensional array in the computer memory as a numerical value according to a predetermined condition, and there is a high-frequency signal higher than the frequency set at this time. Sometimes, the band limiting filter 6 removes the aliasing component. Furthermore, the computer generated hologram creating means 12 is created by calculating the field of light propagating from the object to the hologram surface using diffraction theory or the like. If the calculated hologram is a moving image, the calculated hologram differs depending on each frame image necessary for the moving image.

  As an example of an object, when forming a hologram of an image in which a flag flutters, a hologram corresponding to the number of frames necessary as a moving image in which the flag flutters per second is created. In addition, when the hologram created by calculation is a Fourier transform type hologram, the amplitude and phase of light on the hologram surface can be obtained using fast Fourier transform that can greatly reduce the calculation time. Then, the hologram created by calculation is stored in the storage means and used.

Next, the operation of the color holography display device 1 will be described.
The color holography display device 1 stores an image as a hologram (interference fringe) in advance in the storage unit 10c.

  Then, the color holography display device 1 outputs the white light of the laser light from the light irradiating means 2 as readout light and passes it to the color filter 5 and the spatial light modulator 4 as parallel light via the light source lens 3a and the irradiation lens 3b. Irradiate. At this time, in the spatial light modulator 4, the interference fringes stored from the storage means 10c of the control means 10 are displayed.

  The spatial light modulator 4 displaying the interference fringes is controlled by the output means 10f of the output control means 10d of the control means 10 via the color filter 5, for example, 30 continuous interferences per second. When output so that the stripes can be displayed, a reproduction image is displayed as a color hologram reproduction image h by the readout light and the displayed interference fringes. For example, a state where the flag is fluttering due to wind is displayed.

  In addition, since the band limiting filter 6 is used, aliasing components (folding distortion) can be removed in accordance with vertical sub-sampling of the spatial frequency of the modulation signal, so that an observed color hologram reproduction image h Can be reproduced and displayed more clearly.

  Although the spatial light modulator 4 has been described as a configuration in which the color filter 5 is disposed facing the display surface, the spatial light modulator 4 may be configured so that the color filter 5 is integrally incorporated in the spatial light modulator 4. Another configuration of the spatial light modulator 4 will be described with reference to FIG. FIG. 4A is a perspective view schematically showing another configuration of the spatial light modulator in the color holography display device, and FIG. 4B is a sectional view of a part of the spatial light modulator. The same configurations as those in FIGS. 1 and 2 are denoted by the same reference numerals and description thereof is omitted.

  As shown in FIG. 4, the spatial light modulator 24 is formed so that the pixels in the horizontal direction display the same one of the three primary colors. The spatial light modulator 24 includes a translucent plate 24b provided with a deflection plate 24a on the surface from the display side, a color filter unit 24c provided on the back side of the translucent plate 24b, and a back side of the color filter unit 24c. The transparent electrode 24d provided on the transparent electrode 24, the alignment films 24e and 24h provided on the back side of the transparent electrode with a predetermined interval, and the liquid crystal 24f provided between the alignment films 24e and 24h via beads 24g as spacers. A transparent electrode 24j provided on the alignment film 24h so as to face each pixel of the color filter portion 24c, a translucent plate 24k provided on the back side of the transparent electrode 24j, and a back side of the translucent plate 24k. Provided polarizing plate 24m.

  The spatial light modulator 24 is configured to be a green filter unit 25a, a red filter unit 25b, and a blue filter unit 25c for each pixel column arranged in parallel in the horizontal direction as a configuration of the color filter unit 24c. Yes.

  Accordingly, the hologram formed by each pixel is displayed by irradiating the backlight from the back or side of the spatial light modulator 24, and the color hologram is formed by irradiating the surface of the spatial light modulator 24 with the readout light. The reproduced video h can be displayed. Of course, the color hologram reproduction video h can be displayed as a moving image by displaying a predetermined hologram per second by the control means 10.

  In the color holography display device 1 described above, the spatial light modulator 4 has been described as a configuration by electrical drive, but a DMD element can also be used as a device that performs amplitude modulation. The DMD element is composed of an array of minute rotating mirrors, and can be optically modulated by rotating the rotating mirrors.

  In addition, a color hologram may be created with the configuration shown in FIG. FIG. 5 is a schematic diagram schematically showing a state in which a hologram to be reproduced by a color holography display device is photographed. As shown in FIG. 5, a half mirror 14 is disposed in the optical path from the laser light irradiation means 16 for irradiating white laser light, and the illumination light lens optical system 13A (convex lens 13a, 13b), a reference light lens optical system (same configuration as the lens system) 13B (convex lenses 13c, 13d) is disposed in the optical path of the reflected light of the half mirror 14 via the mirror 15, and the object w is irradiated The image sensor 7 is arranged via the color filter 5 so as to store the interference fringes at the position where the object light of the illumination light and the reference light are irradiated (position of the spatial light modulator 4). Yes.

  Therefore, a pattern of interference fringes in a state where the object W is flagged and fluttered by the wind is sequentially stored in the storage unit 10c of the control unit 10 along the time axis, thereby creating a color hologram of the object w. . The color hologram created in this way is displayed as described above.

1 is a perspective view schematically showing an overall structure of a color holography display device according to the present invention. 1 is a block diagram schematically showing the overall structure of a color holography display device according to the present invention. It is a front view which shows typically the structure of the color filter of the color holography display device which concerns on this invention. (A) is a perspective view which shows typically the other structure of the spatial light modulator in the color holography display device which concerns on this invention, (b) is sectional drawing of a part of spatial light modulator. It is a schematic diagram which shows typically the state which image | photographs the hologram reproduced | regenerated with the color holography display device which concerns on this invention. It is a schematic diagram which shows typically the state which comprised the conventional holography display apparatus using three spatial light modulators. It is a front view which shows typically the structure of the color filter used for the conventional color holography display device. It is a front view which shows typically the other structure of the color filter used for the conventional color holography display device. It is a top view which shows typically the state of the horizontal visual field at the time of reproduction | regeneration in the case of comprising a hologram with the element which has a pixel structure, or a vertical visual field.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Color holography display apparatus 2 Light irradiation means 3 Lens system 3a Light source lens 3b Irradiation lens 4 Spatial light modulator 5 Color filter 5A Green filter 5B Red filter 5C Blue filter 5a Green filter part 5b Red filter part 5c Blue filter part 6 Band limitation Filter 7 Image sensor 10 Control means 10a Input means 10b Video selection means 10c Storage means 10d Output control means 10e Display memory 10f Output means 11 Image input means 12 Computer hologram creation means 24 Spatial light modulator 24a Deflection plate 24b Translucent plate 24c Color Filter part 24d Transparent electrode 24e Alignment film 24f Liquid crystal 24g Bead 24h Alignment film 24j Transparent electrode 24k Translucent plate 24m Polarizing plate 25a Green filter part 25b Red filter part 25c Blue filter part h Color pholog Ram playback video

Claims (4)

In a color holography display device that displays a reproduced image as a three-dimensional image by irradiating readout light onto a hologram of an image displayed on the spatial light modulator by control of the control means,
A color filter having three primary colors of RGB arranged facing each other along a pixel pitch of a spatial light modulator for displaying the hologram;
In the color filter, the color corresponding to the pixel in the horizontal direction is any one of the three primary colors of RGB, and the color indicated by the pixel in the horizontal direction is arranged in the same period in the vertical direction with respect to each color of RGB. A color holographic display device. In a color holography display device that displays a reproduced image as a three-dimensional image by irradiating readout light onto a hologram of an image displayed on the spatial light modulator by control of the control means,
In the spatial light modulator for displaying the hologram, the color corresponding to the pixel in the horizontal direction is any one of the three primary colors of RGB, and the color indicated by the pixel in the horizontal direction is perpendicular to each color of RGB The color holographic display device is arranged in the same period.   The color holographic display device according to claim 1, wherein the spatial light modulator includes a light modulation unit capable of performing amplitude modulation or phase modulation.   4. The color holographic display device according to claim 1, wherein the control unit includes a band limiting filter that removes a aliasing component in accordance with vertical subsampling of the spatial frequency of the modulation signal. 5.

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