JPH08240869A - Stereoscopic image display device - Google Patents

Abstract

PURPOSE: To provide an inexpensive stereoscopic display device easy to extend the screen and having a comparatively small increase of calculating time accompanying the enlargement of the screen. CONSTITUTION: A calculating device 4 for calculating stereoscopic display information from the given stereoscopic display information respectively and a stereoscopic display unit 3 including a diffraction type spacial light modulator 5 driven by the stereoscopic display information are arranged in parallel, inputted stereoscopic image information l is divided corresponding to the display range of the stereoscopic image information allocated in advance to the respective stereoscopic display units, respecitive divided pieces of stereoscopic information are supplied to the corresponding stereoscopic display units and performs the stereoscopic image display of the inputted stereoscopic image information 1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a stereoscopic image display device for displaying a stereoscopic image capable of visually perceiving a depth, and more particularly to a stereoscopic image display device for easily displaying a stereoscopic moving image of a large size.

[0002]

2. Description of the Related Art Normal CRTs, LCDs (Liquid Crystals)
The output image of the display device using Device;
It is a flat display limited to 3D still or moving images. In such a display device, the display object is represented as a plane image captured from one angle. Therefore, since the information in the depth direction is greatly reduced, the observer cannot accurately perceive the depth of the subject.

On the other hand, there is known an optical wavefront control technique such as holography or kinoform which displays a stereoscopic image having a natural sense of depth by optically reproducing and displaying a wavefront that will be reproduced from an object. Has been. In the past, it was difficult to reproduce a moving image because image information was recorded on a photosensitive material that requires the same image processing as that of a photograph.
OM (Acousto-Optic Modulator) and LC
A holographic display has been proposed in which D is used as a diffractive spatial light modulator to display a moving image. A known example of such a display is S. Ben of the United States.
The invention of ton (USP: 5,172,251) and the research of Shonan Institute of Technology Koto Sato are known.

Explaining the display by the light wavefront control system, first, the stereoscopic image information is converted into the interference fringe information of the hologram. This conversion is calculated based on a formula of diffraction integral or a spectrum conversion formula such as Fourier transform or discrete cosine transform. In the diffraction integration, specifically, the solid is regarded as a set of point light sources, and the interference fringes of the wavefront (object wave) from each point and another reference wavefront (reference wave) are calculated. The calculated interference fringes are displayed on a spatial light modulator capable of modulating the amplitude and phase of light. By illuminating this spatial light modulator with a reference wave, a stereoscopically reproduced image of the object can be obtained.

The three-dimensional moving image display device of the light wavefront control system is
You can display a solid as if the object were in space. This method enables stereoscopic display of fictitious objects on a computer, obtains a natural stereoscopic effect, can display stereoscopic moving images, and has little change in stereoscopic effect due to individual differences among observers. Has excellent characteristics.

However, in the light wavefront control type display,
There are two problems: an increase in the amount of calculation of stereoscopic information and an increase in the amount of display information. However, as described above, the calculation of the interference fringes calculates the phase contribution of each pixel of the display for each object point to be displayed. Therefore, the number of calculations increases as the number of display object points increases with the expansion of the viewing area and the number of pixels increases with the expansion of the display screen. This leads to an increase in calculation time, which is a particular problem in the case of displaying a moving image.

Further, since diffraction is used for display, a very fine pixel size of several μm to several tens of μm is required. FIG. 7 shows the relationship between the amounts of information displayed on a normal display and a stereoscopic display. Generally, in a normal flat display, the number of pixels is constant regardless of the screen size. On the other hand, in the light wavefront control type stereoscopic display, the pixel pitch is determined depending on the viewing angle, and therefore the number of pixels, that is, the amount of display information increases as the screen size increases. In this way, an increase in the amount of display information and an increase in the amount of hologram calculation cannot be avoided due to the increase in screen size.

In order to solve these problems, S. Benton et al. Proposed a stereoscopic moving image display device in which a plurality of spatial light modulators are arranged in parallel and a large diameter raise, a wide band frame memory and a super computer are used. (S.Benton, "T
he Second Generation of the MIT Holographic Video
System ", Proc.of TAO First International Symposium
on 3D Image Communication Technologies (1993)). The configuration of this conventional stereoscopic display is shown in FIG. 8A (cited from the above paper).

In FIG. 8A, reference numeral 22 is a super computer, 23 is a frame memory, 24 is a spatial light modulator, 25 is a laser light source, 26 is a collimator optical system, and 27.
Is a scanning mirror, 28 is a reduction optical system, 29 is an observer, and 30 is a reproduced image.

The supercomputer 22 calculates interference fringes at high speed from the three-dimensional data of each object point for each stereoscopic image information sequentially input at a fixed timing of the frame period, and creates hologram information in frame units. , In the frame memory 23. The spatial light modulator 24 is formed by arranging a plurality of independent units, spatially divides the hologram information in the frame memory 23, and supplies each of the divided hologram information to each unit for driving. On the other hand, the laser light emitted from the laser light source 25 becomes reference light which is collimated by the collimator optical system 26 and illuminates the spatial light modulator 24. The diffracted light output from the spatial light modulator 24 is deflected and scanned in the vertical direction (y) by the scanning mirror 27, and is observed by an observer 29 via the reduction optical system 28.
The reproduced image 30 is recognized.

FIG. 8 (b) is a processing block diagram of the stereoscopic display of FIG. 8 (a). That is, an information processing unit that calculates interference fringes, a frame memory, a display unit that includes a spatial light modulator that displays interference fringes, and an output unit that includes optical components such as lenses are connected in series. ing. With this configuration, after the information on the entire screen is calculated, the information is collectively transferred to the display unit (spatial light modulator), divided, displayed on the spatial light modulator, and again combined to perform optical display. Here, when three-dimensional information is converted into display information, the amount of display information increases significantly, so a high-speed calculation processing device and a wideband bus are required, and as the screen expands, it becomes larger, more expensive, and more accurate. Optical / mechanical parts are required, and the expandability is poor, and the electronic / optical / mechanical constraints are still large due to the wide band of signals and the increase in size of the device, resulting in problems such as high cost of parts. Occurs.

[0012]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a stereoscopic image display device which is easy to expand such as screen enlargement, has a relatively small increase in calculation time associated with screen enlargement, and is inexpensive. .

[0013]

In order to solve the above problems, the present invention configures the entire screen by arranging three-dimensional image display units for displaying a partial area (hereinafter, small area) of the screen in parallel. A stereoscopic moving image display device is proposed. Here, the stereoscopic image information is divided in advance according to the display area, and then the hologram information is calculated and displayed for each unit.

FIG. 1 is a block diagram showing the principle of the present invention. 1 is input stereoscopic image information, 2 is a division processing unit, and 3-1 to 3-3-
N is N (N ≧ 2) stereoscopic image display units, 4-1 to 4-1
4-N is a calculation device, 5-1 to 5-N are diffraction type spatial light modulators, and 6-1 to 6-N are display optical systems.

The input stereoscopic image information is information that describes a stereoscopic image, for example, a set of object points represented by three-dimensional coordinate values (x, y, z), and is subdivided in advance by the division processing unit 2. It is divided into N areas according to the displayed range and is supplied to the respective stereoscopic image display units 3-1 to 3-N. In the stereoscopic image display units 3-1 to 3-N,
The calculation devices 4-1 to 4-N perform hologram calculation for converting stereoscopic image information into a stereoscopic display device, and drive the diffractive spatial light modulators 5-1 to 5-N, respectively. Display optical system 6-1
6-N pick up reproduced images from the respective diffractive spatial light modulators 5-1 to 5-N.

[0016]

According to the present invention, since the input stereoscopic image information is first divided according to a plurality of display areas that have been subdivided in advance, the calculation range is set to the object points included in the small area when calculating the interference fringes. It is possible to limit As a result, compared with the case where the entire screen is calculated first, the amount of calculation information is reduced and the calculation time can be expected to be shortened. Also, the display information amount of a stereoscopic image is
Although it depends on the screen size and the viewing angle, it is possible to easily realize an arbitrary screen size by arranging a sufficient number of stereoscopic image display units in parallel according to the screen size (band).

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 2 is an overall configuration diagram of a stereoscopic image display device according to an embodiment of the present invention. In FIG. 2, 8 is stereoscopic image information, 9 is a division processing unit for stereoscopic image information, and 10-1 to 10-N.
Is a stereoscopic image display unit, 11-1 to 11-N are stereoscopic display information calculation devices, 12-1 to 12-N are frame memories for storing stereoscopic display information, and 13-1 to 13-N are spatial light modulators. Indicates.

FIG. 3 is arbitrary (1 ≦ n ≦ N) in FIG.
2 is a diagram showing a detailed configuration of the stereoscopic image display unit of FIG.
1-n is a computer, 12-n is a frame memory, 13-
Reference numeral n is a spatial light modulator, 14 is a diffusion plate, 15-n is a drive circuit, 16-n is a laser light source, 17-n is a collimator optical system, and 18-n is a reduction optical system.

The stereoscopic image display unit shown in FIG. 3 is a calculation device 11-n for converting stereoscopic image information into display information such as hologram interference fringes, and a frame memory 12-n for storing the calculated information and transmitting it to the display system. , Spatial light modulator for display 1
3-n and its driving circuit 15-n, and an optical system 16-n, 17-n, 18-n for illuminating the reference light and propagating the diffracted light. At present, AO using TeO ₂ crystal, which is one of the spatial light modulators that can realize the finest lattice structure
In the case of M, the pixel pitch is about 6 μm, and the diffraction angle is only about 3 degrees with respect to the wavelength of 632.8 nm of the He-Ne laser.
Therefore, the reduction optical system 18-n is arranged on the output side of the spatial light modulator 13-n, the diffraction image is reduced and displayed, and the diffraction angle, that is, the viewing angle is enlarged. Although not essential, a diffuser plate 14 can be placed behind the reduction optics 18-n to increase the field of view. Hereinafter, each component will be described.

The calculator 11-n calculates stereoscopic display information (holographic interference fringes, kinoform phase, etc.) from stereoscopic image information (for example, a set of three-dimensional coordinates). The calculation is based on the formulas of diffraction integration and spectral conversion as described above.

The computing device 11-n is implemented by software operating on a computer such as a personal computer or a workstation, or by hardware such as a DSP (Digital Signal Processor). The calculation of the stereoscopic display information of the hologram can be realized by a decimal point operation including a trigonometric function or a logarithm, or a function of recording / referring these as data. When is a hologram interference fringe, as is well known, the spatial light intensity or phase distribution generated by the interference between the reference wave and the object wave is calculated and used as display information. The calculated stereoscopic display information is transmitted to the frame memory 12-n via the internal or external bus.

The frame memory 12-n transmits the stereoscopic display information to the spatial light modulator as a video signal suitable for the spatial light modulator 13-n. A drive circuit 15-n for the spatial light modulator may be provided in this path, and a filter and a signal amplifier may be provided in addition to the drive circuit 15-n.

The spatial light modulator 13-n displays the stereoscopic display information as a spatial light amplitude (transmittance, reflectance) distribution or phase (refractive index, pixel displacement) distribution. A reference wave is incident on the spatial light modulator 13-n using the laser light source 16-n. In the figure, the case where a parallel wave is used as the reference wave is shown using the laser light source 16-n and the collimator optical system 17-n. The reference wave is not limited to a parallel wave, and may be a spherical wave or a wavefront having an arbitrary aberration, as long as the wavefront can obtain a desired output image.

The spatial light modulator 13-n has a fine pixel pitch of μm unit necessary for the diffractive display, and changes the phase or transmittance distribution according to the stereoscopic display information transmitted from the frame memory 12-n. It is an optical element provided with a means to do. An example of such a spatial light modulator is an AOM.
Known are LCDs, non-linear optical crystals, photochromic materials such as bacteriorhodopsin, and the like. For example, the AOM using TeO ₂ as a crystal can realize spatial phase modulation in a signal band of 50 MHz with a pixel pitch of 6 μm.

When sampling at twice the spatial frequency, the relationship between the diffraction angle θ and the pixel pitch p in the spatial light modulator 13-n of FIG. 3 is expressed by the diffraction equation 2 sin θ = λ / (2
p). Here, λ represents the reproduction wavelength. The visual range θv, which is the range in which the image is observed, is expressed by the following equation.

Θv = 2 θ = 2 Sin ⁻¹ (λ / 4p) For example, when the wavelength is 632.8 nm of a He—Ne laser and the viewing angle θv is 15 degrees, the required pixel pitch is 1.
It becomes very fine as 2 μm. The spatial frequency of the spatial light modulator 13-n is about 6 μm even at the minimum, and is 10 μm.
Those having the following pixel pitches are difficult to manufacture. Therefore, in order to secure a sufficiently wide viewing zone required for binocular observation,
A reduction optical system 18-n for reducing the interference fringes of the spatial light modulator 13-n is used.

FIG. 2 shows an example of the structure of a transmissive spatial light modulator (eg, LCD, functional element using a photochromic material, etc.) in the embodiment of FIG. The same function can be realized with a reflective spatial light modulator or an acousto-optic device. FIG. 4A shows a reflective spatial light modulator (eg, LCLV (Liquid Crystal Light).
t Valve), BSO, PLZT, etc.), and FIG. 4B shows an example configuration of a stereoscopic image display unit when the acousto-optic element is a spatial light modulator. The reflective spatial light modulator outputs reflected diffracted light. The acousto-optic device uses the scanning optical system 20 to compensate for the display information traveling at the speed of sound in the crystal and to make it stationary on the hologram display surface. The diffracted light (output) of the spatial light modulator is converted by the reduction optical system so as to obtain a larger viewing area. When a spatial light modulator having a sufficiently high spatial frequency is used, a reduction optical system is not necessary. By illuminating the spatial light modulator with a reference wave, a stereoscopic image is displayed as a hologram image.

Next, the structure of the stereoscopic image display device by the processing of dividing the input stereoscopic information into the subdivided display ranges, that is, the calculation areas and the parallel arrangement of the stereoscopic image display units will be described. As can be seen from FIG. 7, when the stereoscopic image information is converted into display information, the amount of information to be transmitted suddenly increases. However, the stereoscopic image information is divided into areas in advance, and calculation and
If parallel processing is performed so as to display, the band to be processed by the unit can be kept low. It is possible to meet the demand for increasing the screen size with the number of units. The display area of one unit can be set to an appropriate size according to the calculation capacity of the unit, the frame memory, and the band of the spatial light modulator. As a result, a stereoscopic moving image display device having an arbitrary screen size can be realized by a set of spatial image modulators and a set of stereoscopic image display units adapted to the band limitation of the signal processing system.

Regarding the division of the display range, there are two cases shown in FIG. 5 (a) and FIG. 5 (b). Figure 5 (a) shows
The area of the object point p to be calculated by the unit is {p (x, z) |
X _{n- 1} ≦ x ≦ X _n }. At this time, the horizontal range of the hologram display of the nth unit is set to X _n-1.
≦ x ≦ X _n . According to this method, it is easy to divide the area. However, there is a drawback that the display image of the boundary area disappears when observed from the adjacent unit side. In order to prevent this, the displayable object point of a unit may be divided while allowing overlap with another unit to be calculated and displayed.

Therefore, as shown in FIG. 5B, the calculation range of the unit is {p (x, z) | X _n-1 | z | tan θ ≦ x ≦
Let it be the display object point p included in X _n + | z | tan θ}. Here, the diffraction angle of the unit was set to θ. At this time, it is possible to prevent the image point from disappearing when the image is viewed from the adjacent unit.

In the above, the case where there is diffraction only in the horizontal direction (x direction) of the screen is shown. Similarly, the same means is also effective in the case of diffracting in a two-dimensional direction including the top and bottom of the screen (y direction in the figure). In the case of simple area division, the range of the object point p to be calculated for one unit is {p (x, z) | X _n-1 ≤x
≦ X _n , Y _n−1 ≦ y ≦ Y _n }. At this time, the horizontal range of one unit of hologram display is set to X _n-1 ≤x≤X
_n and Y _n-1 ≤y≤Y _n . The condition for preventing the disappearance of the image when observed from the adjacent unit is that the range of the object point p to be calculated for one unit is {p (x, y, z) | X _n-1 | z
│tanθ _x ≤x≤X _n + | z│ tanθ _x , Y _n-1 | z |
tan θ _y ≦ y ≦ Y _n + | z | tan θ _y }. At this time, the diffraction angle in the x direction was θ _x , and the diffraction angle in the y direction was θ _y . The three-dimensional image display units described above are arranged one-dimensionally or two-dimensionally to form a large-screen display. The information of the object corresponding to the space is displayed on each stereoscopic image display unit. The shape of the display surface is not limited to a flat surface but may be a cylinder (concave surface, convex surface) hemispherical surface or the like as shown in FIG.

Regarding the arrangement of the stereoscopic image display unit,
In the case of the embodiment of FIG. 2, the arrangement is linear in the lateral direction, but as shown in FIG. 6, any arrangement such as a plane, a cylindrical surface (unevenness), or a spherical surface can be made. The stereoscopic image information (entire image) that is the original image is divided according to the display area. The division method at this time is described above. The divided stereoscopic image information is
It is transmitted to the stereoscopic image display units arranged in parallel.
Display information is calculated and displayed for each unit.

Here, consider a case where the number of object points of a stereoscopic image is L and N stereoscopic image display units of M pixels are arranged one-dimensionally. The calculation amount per unit is f × L / N × M, and the display information amount is M. In the conventional method that collectively calculates and displays from stereoscopic image information to display information, in contrast to the same display,
The calculation amount is f × L × M, and the display information amount is N × M. According to this, the calculation amount (calculation time) can be reduced to 1 / N, and the bandwidth of the bus and the frame memory required to transmit the display information can be reduced to 1 / N.

As described above, a plurality of units are arranged in parallel to form a stereoscopic image display device having a larger display screen. In addition, the stereoscopic image information can be displayed by sequentially updating the stereoscopic image information and repeatedly performing information processing from information division to display.

[0035]

According to the present invention, the screen is divided into small areas,
By performing the display processing in parallel, the restrictions on the screen size are greatly relaxed, and it becomes easy to realize a display device having a large screen.

[Brief description of drawings]

FIG. 1 is a principle configuration diagram of the present invention.

FIG. 2 is an overall configuration diagram of a stereoscopic image display device according to an embodiment of the present invention.

FIG. 3 is a configuration diagram of a stereoscopic image display unit according to an embodiment of the present invention.

FIG. 4 is a configuration diagram of another embodiment of the stereoscopic image display unit.

FIG. 5 is an explanatory diagram of display range division processing.

FIG. 6 is an explanatory diagram of an arrangement example of a stereoscopic image display unit.

FIG. 7 is a display information amount relationship graph between a normal display and a stereoscopic display.

FIG. 8 is a configuration diagram of a conventional stereoscopic display.

[Explanation of symbols]

 1 Stereoscopic image information 2 Division processing part 3-1 to 3-n Stereoscopic image display unit 4-1 to 4-n Calculation device 5-1 to 5-n Diffraction type spatial light modulator 6-1 to 6-n Display optics system

[Procedure amendment]

[Submission date] March 7, 1995

[Procedure Amendment 1]

[Document name to be corrected] Drawing

[Correction target item name] All drawings

[Correction method] Change

[Correction content]

FIG.

[Fig. 2]

[Figure 3]

[Figure 5]

[Figure 6]

[Figure 4]

[Figure 7]

[Figure 8]

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Shigetake Iwata 2-31, 19 Shiba, Minato-ku, Tokyo Banzaivil 6F Communication and Broadcasting Organization (72) Inventor Susumu Tsujikawa 5-7, Shiba, Minato-ku, Tokyo No. 1 NEC Corporation

Claims (8)

[Claims] 1. A plurality of spatial lights in which stereoscopic display information is calculated for each of the stereoscopic image information divided according to a display range that has been subdivided in advance, and the calculated stereoscopic display information is arranged in parallel. A three-dimensional image display device characterized by supplying each to a modulator to perform three-dimensional image display. 2. The display range of the three-dimensional image information that has been subdivided in advance is: the arrangement order of any subdivided display range is n, and the coordinate axis of the three-dimensional image information in the depth direction. z, two horizontal coordinate axes that are orthogonal to the coordinate axis z, x, y, the minimum coordinates of the _nth display screen area are X _n-1, Y _n-1 , the nth display screen area The maximum coordinate is X _n, Y _n , an object point represented by at least one of the two horizontal coordinate axes x and y (for example, x) and the coordinate axis z in the depth direction is p (x, z), Then, the stereoscopic image display device is characterized in that the value of x is defined as a region of an object point p (x, z) that falls between X _n-1 and X _n . 3. The stereoscopic image display device according to claim 1, wherein a display range of the stereoscopic image information that has been subdivided in advance is equal to a range of diffracted light. 4. The display range of the three-dimensional image information that has been subdivided in advance is: an arrangement order of an arbitrary subdivided display range, and a coordinate axis in the depth direction of the three-dimensional image information. z, two horizontal coordinate axes that are orthogonal to the coordinate axis z, x, y, the minimum coordinates of the _nth display screen area are X _n-1, Y _n-1 , the nth display screen area The maximum coordinate is X _n, Y _n , an object point represented by at least one of the two horizontal coordinate axes x and y (for example, x) and the coordinate axis z in the depth direction is p (x, z),・ When the diffraction angle is θ, the value of x is X _n-1 − | z | tan θ and X
A stereoscopic image display device characterized by being defined as a region of an object point p (x, z) that falls between _n + | z | tan θ. 5. A calculation device for calculating stereoscopic display information from given stereoscopic display information and a stereoscopic image display unit including a spatial light modulator driven by the stereoscopic display information are arranged in parallel and input. The stereoscopic image information is divided in association with the display range of the stereoscopic image information that is pre-assigned to each stereoscopic image display unit, and each of the divided stereoscopic image information is supplied to the corresponding stereoscopic image display unit to input the stereoscopic image. A stereoscopic image display device characterized by performing stereoscopic image display of information. 6. The display range of stereoscopic image information pre-assigned to each stereoscopic image display unit according to claim 5, is as follows: Arrangement order of each arbitrary stereoscopic image display unit is n; The coordinate axis of z is the two coordinate axes in the horizontal direction orthogonal to the coordinate axis z, x is the minimum coordinate of the display screen area of the n-th stereoscopic image display unit is X _n-1, Y _n-1 , The maximum coordinates of the display screen area of the n-th stereoscopic image display unit are X _n, Y _n , by using at least one of the two horizontal coordinate axes x and y (for example, x) and the coordinate axis z in the depth direction. When the represented object point is p (x, z), the value of x is defined as the area of the object point p (x, z) that falls between X _n-1 and X _n. 3D image display device. 7. The stereoscopic image display device according to claim 5, wherein a display range of stereoscopic image information pre-assigned to each stereoscopic image display unit is equal to a range of diffracted light. 8. The display range of stereoscopic image information pre-assigned to each stereoscopic image display unit according to claim 5, is: Arrangement order of each arbitrary stereoscopic image display unit is n, Depth direction of stereoscopic image information The coordinate axis of z is, two coordinate axes in the horizontal direction orthogonal to the coordinate axis z are x, y, the minimum coordinates of the display screen area of the n-th stereoscopic image display unit are X _n-1 , Y _{n- 1} , The maximum coordinates of the display screen area of the n-th stereoscopic image display unit are X _n, Y _n , by using at least one of the two horizontal coordinate axes x and y (for example, x) and the coordinate axis z in the depth direction. When the object point represented is p (x, z), and the diffraction angle is θ, the value of x is X _n-1 − | z | tan θ and X
A stereoscopic image display device characterized by being defined as a region of an object point p (x, z) that falls between _n + | z | tan θ.