JP2520766B2 - Holography-Display device and its driving method - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a three-dimensional display device for pseudo-displaying a three-dimensional moving image and a driving method thereof.

SUMMARY OF THE INVENTION The present invention is directed to an optical holography forming means including coherent optics and an interference optical system, an optical writing type spatial light modulator for recording holography formed by the holography forming means, a light source and a reading light flux. In a holographic display device for reproducing a hologram formed in the spatial light modulator by an image information reproducing means composed of a generating optical system and an enlarged image forming optical system for reproducing light, an electrical or optical image information inputting means and a cycle An optical path length conversion means for changing the optical path length is disposed in the interference optical system, and a two-dimensional image obtained by quantizing the three-dimensional image in a desired dimension direction from the three-dimensional image information storage means. A means for inputting the three-dimensional image information to the image information input means in synchronization with the optical path length change period of the optical path length conversion means is configured. By doing so, two-dimensional image information formed by quantizing a three-dimensional image in a specific direction with a phase difference can be sequentially recorded and reproduced as holography, and a three-dimensional image that can be operated in real time. It is intended to provide a holographic display device capable of artificially producing.

[Prior Art] Conventionally, many attempts have been made to artificially realize a three-dimensional image that can be operated in real time.

The most popular research is the study of pseudo three-dimensional images using parallax. For example, you can attach a red filter and a blue filter to the right and left eyes respectively, or a polarizing filter that transmits only the light with different polarization planes (orthogonal), and display blue and red images with parallax shift, or polarized light. A three-dimensional image is artificially formed by seeing an image formed by projecting light (orthogonal) having different planes.

In addition, three-dimensional images with slightly different shapes are formed as holograms with reference light in different directions on a hologram dry plate coated with silver salt on a glass plate or plastic film, and the direction of the reproduction light is changed to the reference light above. There is also a method of forming a pseudo three-dimensional moving image by sequentially changing so as to match the direction of.

[Problems to be Solved by the Invention] However, in the conventional method for forming a pseudo three-dimensional image using parallax, since the reproduced original image does not include phase information, the reproduced image is not stereoscopically represented. There is a problem in that it cannot be performed strictly, and it is difficult to faithfully reproduce a three-dimensional image having a stereoscopic effect.

Further, in the method of utilizing the hologram formed on the hologram dry plate described above, it takes time to prepare the reproduced original image because the process of developing and fixing the recorded hologram is required, and a longer three-dimensional moving image is realized. There is a problem that a large amount of hologram dry plate is required for this.
Also, this method is not suitable for connection with an electronic system.

[Means for Solving the Problems] The holographic display device of the present invention comprises an optical holographic forming means comprising a coherent light source and an interference optical system, and an optical writing type space for recording holography formed by the holographic forming means. In a holographic display device for reproducing a hologram formed on the spatial light modulator by an image information reproducing means including an optical modulator, a light source, a reading light flux generating optical system, and an enlarged image forming optical system for reproducing light, an electrical or An optical image information input means and an optical path length conversion means for periodically changing the optical path length are arranged in the interference optical system, and the three-dimensional image information storage means directs the three-dimensional image in a desired dimensional direction. The two-dimensional image information obtained by quantizing the optical path length of the optical path length conversion means to the image information input means. By providing a means for inputting in synchronization with the change cycle, the above problems can be solved and a pseudo three-dimensional moving image can be realized.

In particular, in order to add phase information to the image, as the optical path length conversion means for periodically changing the optical path length, the quantum of the three-dimensional image on the same scale as the size of the two-dimensional image information displayed on the image information input means. In order to facilitate connection with the electronic system, use a rotating polygon mirror or a rotating cylindrical mirror having a rotating shaft that is eccentric by half the size in the direction of rotation, and a rotating means such as a motor. , A transmissive liquid crystal display that drives a ferroelectric liquid crystal by arranging single crystal thin film transistors in a matrix as image information input means, or a CRT and an imaging optical system or a laser scanning device, and an optical writing spatial light modulator. As a photo-writing type spatial light modulator capable of real-time hologram recording, a photoconductive layer, a light reflection layer, a liquid crystal alignment layer, a light reflectance and application Ferroelectric liquid crystal layer having a bistable memory characteristic between the pressure, the voltage applying means, to solve the above problems by using an optical writing type liquid crystal light valve composed of a transparent substrate.

Further, when the three-dimensional object image is expressed in a three-dimensional Gaussian coordinate system, three-dimensional image information is quantized to a predetermined size in the z-axis direction on the two-dimensional plane expressed in xy coordinates, and stored in the memory space. Image information of a two-dimensional plane expressed by xy coordinates,
Z of the cycle of the optical path length conversion device that periodically changes the optical path length
A conventional computer-aided design system (Computer Aded Design) is used by using a drive system in which the image information input means is sequentially input in synchronization with one-half of the quantization number in the axial direction.
We have made possible a holographic display device that can be easily connected to an electronic system (System: CAD).

[Operation] The holographic display device of the present invention, as described above,
After the image information input by the image information input means such as a liquid crystal television is read by a coherent light source such as a laser and converted into a coherent image, the phase wavefront is modulated by passing the coherent image through the optical path length conversion means. As a coherent signal image, the coherent signal image and the coherent reference light generated by the interference optical system are caused to interfere with each other on the optical writing surface of the optical writing type spatial light modulator, or the coherent reference image is passed through the optical path length conversion means. By the coherent reference light whose phase wavefront is modulated by, by causing the coherent reference image and the coherent signal image input by the image information input means to interfere with each other on the optical writing surface of the optical writing spatial light modulator. , The optical writing type space light change Vessel to form a hologram of the coherent signal image. At this time, from the three-dimensional image information storage means, the two-dimensional image information obtained by quantizing the three-dimensional image in a desired dimension direction is transferred to the image information input means to change the optical path length of the optical path length conversion means. By inputting in synchronization with the cycle, a hologram of a two-dimensional image corresponding to the cross-sectional image of the three-dimensional image is formed in the optical writing type spatial light modulator including position information of the quantization direction. It Therefore, by sequentially recording and reproducing the hologram of the two-dimensional image corresponding to the sectional image of the three-dimensional image in the optical writing type spatial light modulator, the recording / reproducing cycle time is sufficient to cause the afterimage of the naked eye. If it is short, a pseudo three-dimensional image can be synthesized.

[Embodiment] An embodiment of the holographic display device and its driving method according to the present invention will be described below with reference to the drawings. First
FIG. 1 is a block diagram showing a configuration of a holographic display device of the present invention, and FIG. 1 (a) shows a case where image information input means and optical path length conversion means are arranged in parallel in an interference optical system, FIG. 1B shows a case where the image information input means and the optical path length conversion means are arranged in series in the interference optical system. In FIG. 1, 1 is an optical hologram forming means,
Reference numeral 2 is an image information reproducing means, 3 is a coherent light source, 4 is an interference optical system, 5 is an optical writing type spatial light modulator, 6 is image information input means, 7 is an optical path length converting means, 8 is a light source, 9 is a reading light flux. Generation optical system, 10 is a three-dimensional image storage means,
The interference optical system 4 includes an image information input means 6 and an optical path length conversion means 7.
The optical holography forming means is composed of the coherent light source 3 and the interference optical system 4, and the image information reproducing means 2 is composed of the light source 8 and the reading light flux generating optical system 9. Of course, the light source 8 may be the same light source as the coherent light source 8. In FIG. 1A, the coherent light emitted from the coherent light source 3 is split into two light beams by the interference optical system 4. One of the light beams branched by the interference optical system converts the two-dimensional image from the three-dimensional image storage means 10 displayed on the image information input means 6 into a coherent two-dimensional image, and the optical writing type spatial light modulator 5 The light writing surface is irradiated. At this time, the two-dimensional image from the three-dimensional image storage means 10 displayed on the image information input means 6 is
A predetermined one image of a two-dimensional image obtained by quantizing the three-dimensional image stored in the three-dimensional image storage means 10 in a desired dimension direction. On the other hand, the other light flux from the coherent light source branched by the interference optical system 4 passes through the optical path length conversion means 7 and forms a predetermined angle with the coherent two-dimensional image from the image information input means 6 and is an optical writing type. The holograms are superposed on the optical writing surface of the spatial light modulator 5 and interfere with each other to cause the optical writing type spatial light modulator 5 to display hologram interference fringes of the coherent two-dimensional image from the image information input means 6. Here, the optical path length conversion means 7 is
Means for changing the optical path length by mechanically changing the optical path length or electro-optically changing the refractive index.
The light flux emitted from the light source 8 is read out by the light flux generation optical system 9
Thus, the optical writing type spatial light modulator 5 is transmitted through the optical path length conversion means 7 to the reading surface of the optical writing type spatial light modulator 5.
The hologram interference fringes of the coherent two-dimensional image are read out from the image information storage means 6 displayed on the optical writing type spatial light modulator 5 by being irradiated in the same direction and in the opposite direction as the writing light beam irradiated on the writing surface of the, and again read. A hologram reproduction image having a desired size is formed via the reading light beam generation optical system 9.

In this way, all the two-dimensional images obtained by quantizing the three-dimensional image stored in the three-dimensional image storage means 10 in the desired dimension direction, at the quantization position of the two-dimensional image. A pseudo three-dimensional image can be obtained by sequentially performing hologram recording / reproduction at a speed sufficient to cause an afterimage effect of the naked eye while giving a corresponding optical path length.

1B is different from FIG. 1A in that the image information inputting means 6 and the optical path length converting means 7 in the interference optical system 4 are different.
Are arranged in series. Coherent light source 3
The coherent light emitted from is split into two light beams by the interference optical system 4. One of the branched light fluxes converts the two-dimensional image from the three-dimensional image storage means 10 displayed on the image information input means 6 into a coherent two-dimensional image, and then passes through the optical path length conversion means 7 to be an optical writing type. The light writing surface of the spatial light modulator 5 is irradiated with the light. On the other hand, the other light flux from the coherent light source branched by the interference optical system 4 forms a predetermined angle with the coherent two-dimensional image from the image information input means 6 which has undergone optical path length conversion, and optical writing type spatial light modulation. The image information inputting means 6 is superposed on the writing surface of the optical device 5 and interferes with each other in the optical writing type spatial light modulator 5.
The hologram interference fringes of the coherent image from are displayed. The reproduction of the hologram is the same as described with reference to FIG. However, the luminous flux emitted from the light source 8 is directed to the reading surface of the optical writing type spatial light modulator 5 by the reading luminous flux generating optical system 9 and to the writing surface of the direct optical writing type spatial light modulator 5 after being branched by the interference optical system 4. The writing light flux is emitted in the same direction and in the opposite direction.

FIG. 2 is a block diagram of an embodiment of the holographic display device of the present invention, 11 is an argon ion laser, 12 is a first beam expander, 13 is a first half mirror, and 14
Is a first mirror, 15 is a second mirror, 16 is a second half mirror, 17 is a first imaging lens, 18 is an optical stopper, 19 is a rotating polyhedral mirror, and 20 is an optical writing type spatial light modulator. , 21 is a helium neon laser, 22 is a second beam expander,
23 is a polarization beam splitter, 24 is a second imaging lens, 25
Is a computer, 26 is a liquid crystal television, and 19a is the center of rotation of the rotating polygon mirror. In FIG. 2, an optical holography forming means composed of a coherent light source and an interference optical system comprises an argon ion laser 11, a first beam expander 12, a first half mirror 13, a first mirror 14 and a second mirror 14. Mirror 15, second half mirror 16 and first imaging lens 17
And the rotating polygon mirror 19 and the LCD TV 26. The optical writing type spatial light modulator for recording holography formed by the holographic forming means is an optical writing type spatial light modulator 20. The image information reproducing means consisting of the light source, the read light flux generating optical system, and the magnifying image forming optical system of the reproduction light,
Helium neon laser 21 and second beam expander 22
A polarization beam splitter 23 and a second imaging lens 24. The electrically or optically addressable image information input means is the liquid crystal television 26, and the optical path length conversion means for periodically changing the optical path length is the rotating polygon mirror 19. The two-dimensional image information obtained by quantizing the three-dimensional image in a desired dimension direction from the three-dimensional image information storage means is synchronized with the image information input means to the optical path length change period of the optical path length conversion means. The means for inputting is the computer 25.

The coherent light beam emitted from the argon ion laser 11 is expanded to a required beam diameter by the first beam expander 12, and then split into two light beams by the first half mirror 13. The light flux transmitted through the first half mirror 13 converts the two-dimensional image displayed on the liquid crystal television 26 into a coherent two-dimensional image, and the coherent two-dimensional image is transmitted through the second half mirror 16 and the first concatenation is performed. After being reduced to a required beam diameter by the image lens 17, it is reflected by the rotating polyhedral mirror 19, enlarged by the first imaging lens 17 again, and then is expanded by the second half mirror 16 to be an optical writing type spatial light modulator. Irradiates 20 writing surfaces. At this time, it is assumed that the liquid crystal television 26 and the optical writing type spatial light modulator 20 are arranged at positions conjugate with the reflecting surface of the rotating polygon mirror 19. Further, the light stopper 18 is configured so that only the light flux reflected vertically from the rotating polyhedral mirror 19 is applied to the light writing surface of the light writing type spatial light modulator 20,
It is arranged to block unnecessary light beams. Further, the rotation center of the rotating polygon mirror 19 is eccentric, and if the distance to the shortest mirror surface is a and the distance to the longest mirror surface is b, ba is a two-dimensional image displayed on the liquid crystal television 26. Is more than the distance in the quantization direction of the three-dimensional image. On the other hand, the light beam reflected by the first half mirror 13 is successively reflected by the first mirror 14 and the second mirror 15, and then is transmitted through the second half mirror 16 to the optical writing type spatial light modulator 20. The writing surface is irradiated with the reference light and interferes with the coherent two-dimensional image, and as a result, the hologram of the coherent two-dimensional image is formed in the optical writing type spatial light modulator 20. The angle formed by the reference light and the coherent image is about 10 degrees or less. The number of rotations of the rotating polygon mirror 19 per second is the LCD TV.
It is equal to a frame rate of 26 and the number of its reflecting surfaces is equal to the quantization number of the three-dimensional image.

On the other hand, the laser light emitted from the helium neon laser 21 has its beam diameter expanded by the second beam expander 22 to a predetermined size, is then reflected by the polarization beam splitter 23, and is used as the optical writing type spatial light modulator 20. The reading surface is irradiated with the reference light in the same direction and in the opposite direction to reproduce the hologram of the coherent two-dimensional image formed in the optical writing type spatial light modulator. The coherent two-dimensional image hologram thus reproduced can be expanded and reproduced to a desired size by the second imaging lens 24 after passing through the polarization beam splitter 23.

Next, a method of inputting a two-dimensional image to the liquid crystal television 26 will be described. FIG. 5 is a block diagram showing the flow of signals in the three-dimensional image storage means of the holographic device of the present invention. 28 is a three-dimensional image input unit, 29 is a digitizing unit, 30 is a memory, 31 is a z-coordinate quantum. Numeral 32 is an xy coordinate quantizer, 33 is an output signal converter, 34 is an image information input means driver, and 35 is an image calculation processor. The three-dimensional image data input from the three-dimensional image input unit 28 such as a keyboard or a three-dimensional image reading device is converted into a digital amount of 0 and 1 or a ternary value or more by the digitizing unit 29, and the data is processed through the image calculation processing unit. After the appropriate image processing is performed by the
Is accumulated in The data extracted from the memory 30 is quantized in the z-coordinate quantizing unit to a predetermined size in the z-coordinate direction, and xy
A set of two-dimensional image data consisting of only coordinates is formed. The set data of the two-dimensional image data is sequentially transferred from the xy coordinate output unit 32 to the output signal conversion unit 33 from the positive direction or the negative direction of the z coordinate. Each of the two-dimensional image data transferred to the output signal conversion unit 33 is subjected to data compression in the output signal conversion unit 33 and processing for operating the image information input unit driving unit 34, and then the image information input unit driving unit 34. Sent to. In this way, the image information input means sequentially displays the two-dimensional images obtained by quantizing the three-dimensional image in the z-axis direction.

Next, the liquid crystal television 26 used as the image information input means 6
I will explain. FIG. 10 is a schematic exploded perspective view showing one embodiment of a liquid crystal television used in the holographic display device of the present invention, and 69a and 69b are such that the polarization planes of transmitted light are vertical (or parallel). Is a polarizing plate disposed at, 70 is a glass carrier, 71 is a common electrode, 49 is an X driver, 50 is a Y driver, 73 is an electro-optical material layer such as TN (Tw
is a liquid crystal layer such as a liquid crystal or a ferroelectric liquid crystal, 77 is a single crystal silicon semiconductor layer, and 80 is a quartz glass carrier.
The drive circuit of the liquid crystal television shown in FIG. 10 comprises an integrated circuit formed in the single crystal silicon semiconductor layer 77. This integrated circuit includes a plurality of field effect insulated gate transistors 52 arranged in a matrix. The source electrode of the transistor 52 is connected to the corresponding pixel electrode 55, the gate electrode is connected to the scanning line 54, and the drain electrode is connected to the signal line 53. The integrated circuit further includes an X driver 49 and is connected to a signal line 53 arranged in a column. Further, the Y driver 50 is connected to the scanning lines 54 arranged in rows.

FIG. 7A is a diagram showing the configuration of the circuit block of the drive substrate of the liquid crystal television shown in FIG. 10, and two-dimensional image information is displayed in the pixel region 51. As described above, in the pixel region 51, the field effect type insulated gate transistor 52, the pixel electrode 55, the signal line 53 and the scanning line 54 wired in a matrix form.
Consists of FIG. 7B is a configuration diagram showing an example of a pixel portion shown by cutting out the pixels of the liquid crystal television shown in FIG.

Next, a method of inputting image information into the liquid crystal television described above will be described. One of the signal flows in the three-dimensional image storage means of the holographic display device of the present invention shown in FIG.
According to the embodiment, the two-dimensional image information is input to the X driver 49 and the Y driver 50 shown in FIG. 7 (a) as the image information input means driving unit 34. The x-driver of the two-dimensional image information is input to the X driver 49, and the y-component of the two-dimensional image information is input to the Y driver 50. These x-component and y-component of the two-dimensional image information are synchronized by a clock signal. There is. FIG. 9 shows a scanning line voltage waveform diagram output from the Y driver 50 which drives the scanning line 54. The voltage applied to the scanning lines is synchronized by the clock signal 47, and the first scanning line, the second scanning line, the third scanning line, and the Nth scanning line.
The ON voltage 61, 63, 65, 67 applied to the first scanning line is applied to each scanning line with a predetermined time delay, and the first scanning line, the second scanning line, the third scanning line After the ON voltage 68 is applied to the Nth scanning line which is the last scanning line for displaying the image frame, the OFF voltage 62, 64, 66, 68 applied to the Nth scanning line , Are applied simultaneously to all scan lines. While the ON voltage 61 is being applied to the first scanning line, the ON voltage is being applied to a predetermined signal line among the first signal line, the second signal line, and the Nth signal line. Then, a voltage is applied to the pixel electrode 55 corresponding to the signal line to which the ON voltage is applied on the first scanning line, and as a result, the liquid crystal is applied between the common electrode 71 and the pixel electrode 55 to which the voltage is applied. layer
An electric field sufficient to invert or twist the liquid crystal molecules of 73 is generated, and the polarization characteristics of the light passing through the liquid crystal layer 73 are changed, so that pixels are displayed. In this way, the two-dimensional image information is displayed on the liquid crystal television by successively displaying the pixels on the predetermined pixels on each scanning line. To read the 2D image information displayed on the LCD TV, the ON voltage is applied to the Nth scanning line that displays the image at the end, and all the 2D images are displayed, and then all the scanning lines are turned OFF. It is performed until a voltage is applied and the entire two-dimensional image is erased.

The time required to read this two-dimensional image is about several tens of microseconds to several hundreds of microseconds. However, for LCD TVs, 1
When the above method is used for the time required to display an image frame, for example, in order to display an image having 400 × 600 pixels, when TN liquid crystal is used as the liquid crystal material, the liquid crystal twist response time is slow. Therefore, it takes several tens of msec and cannot be used as the image information input means of the holographic display device of the present invention. However, if the liquid crystal television using the ferroelectric liquid crystal material as the liquid crystal material is used, for example,
An image having 400 × 600 pixels can be displayed in several tens of microseconds to one hundred and several tens of microseconds per frame. In addition, it is extremely difficult to mount a pixel electrode, an X driver, and a Y driver with high density and drive them at a high speed in a conventional liquid crystal television that uses amorphous silicon as a transistor for driving the liquid crystal television, and cannot be used. .

However, using the driving method of the holographic display device of the present invention described above, a three-dimensional image corresponding to the number of pixels of 1000 × 1000 × 1000, for example, 30 Hz corresponding to the video rate
Since image information must be transferred to the liquid crystal television at a bit rate of at least 30 MHz or more for the above display, the extremely expensive three-dimensional image storage means 10 shown in FIG. 1 must be used. , A signal for accumulating electric charges between the pixel electrode 55 and the common electrode 71 to generate an electric field sufficient to invert the liquid crystal molecules of the liquid crystal layer 73 in the liquid crystal television when performing such high-speed signal transfer. The load on transistor 52 is greater because the voltage that must be applied to line 53 is very high. A method for avoiding such difficulty will be described below.

FIG. 8 is a block diagram showing an example of a circuit block of a liquid crystal television used in the holographic device of the present invention. FIG. 8A is a circuit block diagram in the case where the pixel region 51 is not divided. The difference from FIG. 7A is that a latch 56 for signal data is provided between the Y driver 50 and the pixel region. That is the point. This latch 56 is the Y driver 50
The signal data from is temporarily stored at high speed, and then the operation of applying a voltage corresponding to the signal data to the pixel region 51 in parallel in time is repeated in synchronization with the clock signal. By adding such a latch 56 to the circuit block, the liquid crystal layer 73 in the liquid crystal television is substantially
The voltage that must be applied to the signal line 53 in order to accumulate electric charges for generating an electric field sufficient to invert liquid crystal molecules between the pixel electrode 55 and the common electrode 71 can be lowered. The load on the transistor 52 can be reduced.

In addition, as shown in FIG. 8B, the pixel electrode 51 is connected to the signal line.
Pixel area 51 divided into a plurality of areas in the 54 direction
In regard to the above, the Y driver 50 and the latch 56 are independently provided, and each pixel region 51 is independently driven in synchronization with the clock signal, so that the signal data transfer rate is divided into pixel regions as shown in FIG. 8 (a). If not, the pixel area can be divided into a fraction, and the liquid crystal layer 73 in the liquid crystal television can be reduced.
The voltage that must be applied to the signal line 53 in order to accumulate electric charges for generating an electric field sufficient to invert the liquid crystal molecules between the pixel electrode 55 and the common electrode 71 can be further lowered. The load on the transistor 52 can be reduced.

FIG. 6 shows an embodiment of the signal flow in the three-dimensional image storage means of the holographic display device of the present invention when the pixel area is divided into n and each pixel area is provided with a Y driver and a latch. It is a block diagram shown, 28 is a three-dimensional image input unit, 29 is a digitization unit, 35 is an image calculation processing unit,
31 is a z-coordinate quantization unit, 37 is a y-coordinate division unit, 38 is a first memory unit, 39 is a second memory unit, 40 is a n-th memory unit,
41 is a first output signal converter, 42 is a second output signal converter, 43 is an nth output signal converter, 44 is a first Y driver, 45 is a second Y driver, and 46 is an nth output driver. Y driver, 47
Is a clock signal. The three-dimensional image data input from the three-dimensional image input unit 28 such as a keyboard or a three-dimensional image reading device is converted into a digital value of 0 and 1 or three or more values by the digitization unit 29, and the image calculation processing unit 35 is operated. After appropriate image processing is performed via the z-axis, the z-coordinate quantization unit 31 quantizes a predetermined number in the z-coordinate direction to form a set of two-dimensional image data including only xy coordinates. The set data of the two-dimensional image data is set by the y coordinate division unit 37 to y
The coordinate area is divided into n equal areas, and the two-dimensional image data having n divided y coordinate areas are respectively stored in the first memory section 38, the second memory section, and the nth memory section. To be done. The two-dimensional image data stored in the jth memory unit (j = 1, 2, ..., N) is transferred to the jth output signal conversion unit (j = 1, 2, ..., N). . Each of the two-dimensional image data transferred to the jth output signal converter 33 is subjected to data compression and a process for operating the Y driver in the jth output signal converter 33, and then the jth Y driver. (J
= 1, 2, ..., N). At this time, the j-th output signal conversion unit and the j-th Y driver operate in synchronization with the clock signal 47, and the j-th Y driver is divided into two-dimensional image data having a j-th y-coordinate region. The transfer start time and end time are the kth Y driver (k = 1, 2, ..., N;
j ≠ k) coincides with the transfer start time and end time of the two-dimensional image data having the kth y-coordinate region divided. In this way, the j-th Y driver successively outputs the two-dimensional images obtained by quantizing the three-dimensional image in the z-axis direction to the j-th image.
To the latch (j = 1, 2, ..., N), and the two-dimensional image can be displayed at high speed.

Next, an optical writing type spatial light modulator used in the holographic display device of the present invention will be described. FIG. 11 is a cross-sectional view showing the structure of a photo-writing type ferroelectric liquid crystal light valve as a photo-writing type spatial light modulator used in one embodiment of the present invention. Transparent substrates 81a, 81b such as glass or plastic for holding liquid crystal molecules are transparent electrode layers 83a, 83b on the surface, and silicon monoxide is orthorhombic at an angle of 75 to 85 degrees from the normal direction of the transparent substrate. Evaporated alignment film layers 84a and 84b are provided. The transparent substrates 81a and 81b have their alignment film layers 84a and 84b.
The sides are opposed to each other by controlling a gap via a spacer 90, and hold the ferroelectric liquid crystal 85.

Further, a photoconductive layer 86, a light shielding layer 87, and a dielectric mirror 88 are provided on the transparent substrate layer 81a on the light writing side, and the transparent electrode layer 83a.
And the alignment film layer 84a are laminated between the write-side transparent substrate 81a and the read-side transparent substrate 81b.
Antireflection coatings 89a and 89b are formed.

Next, a method for initializing the photo-writing type ferroelectric liquid crystal light valve having the above structure will be described. The first method is
Once the entire light writing surface of the liquid crystal light valve is irradiated with light, a DC bias voltage sufficiently higher than the maximum operation threshold voltage at the time of brightening or a DC bias voltage in which an AC voltage of 100 Hz to 50 kHz is superimposed is applied to the transparent electrode layer. A voltage is applied between 83a and 83b to align the ferroelectric liquid crystal molecules in a stable state in one direction and store the state. The second method is to apply a DC bias voltage sufficiently higher than the operation threshold voltage in the dark or a DC bias voltage superposed with an AC voltage of 100 Hz to 50 kHz between the transparent electrode layers 83a and 83b without light irradiation. The ferroelectric liquid crystal molecules are aligned in a unidirectional stable state and the state is stored in memory.

Further, the operation after the optical writing type ferroelectric liquid crystal light valve is initialized as described above will be described. The transparent electrode layers 83a and 83b have a reverse bias DC bias voltage that is equal to or lower than the minimum operation threshold voltage in the dark and is equal to or higher than the maximum operation threshold voltage during light irradiation, or a DC bias voltage in which an AC voltage of 100 Hz to 50 kHz is superimposed. An image (for example, a hologram of the coherent two-dimensional image described in the embodiment of FIG. 2) is written by a laser beam or the like while being applied during the period. Carriers are generated in the photoconductive layer 86 in the region irradiated with laser, the generated carriers drift toward the electric field due to the DC bias voltage, and as a result, the operation threshold voltage is lowered, and the operation threshold is generated in the region irradiated with laser. A bias voltage of the opposite polarity above the applied voltage is applied, and the ferroelectric liquid crystal undergoes inversion of molecules due to the inversion of spontaneous polarization and shifts to the other stable state, so the image is binarized and stored. .

The binarized and stored image is the direction of the alignment of liquid crystal molecules aligned by initialization (or the direction perpendicular to it).
By irradiating the linearly polarized read-out light whose polarization axis is aligned with, and passing the analyzer arranged so that the polarization axis is perpendicular (or parallel) to the polarization direction of the reflected light by the dielectric mirror 88. It can be read in the positive or negative state. In the embodiment shown in FIG. 2, the polarization beam splitter 23 is used as the analyzer.

In the embodiment of the present invention, (a) of the optical response characteristic diagram of the optical writing type ferroelectric liquid crystal light valve shown in FIG.
A drive waveform 91 composed of a pulse-shaped rectangular wave represented by is applied between the transparent electrode layers 83a and 83b to erase / write the hologram. In FIG. 12A, the hologram is erased when the positive voltage 92 is applied, the hologram is written when the negative voltage 94 is applied, and the written hologram is memorized when the zero voltage 93 is applied. The positive voltage 92 is a voltage higher than the operation threshold voltage at the time of light when only the reference light is irradiated, and the absolute value of the negative voltage 94 is such that both the reference light and the coherent two-dimensional image are irradiated. In this case, the voltage is higher than the appropriate operation threshold voltage during light. The drive waveform 91 is synchronized with the clock signal 47,
The application start time of the positive voltage 92 is the OFF voltage 62, 64, 6 applied to the j-th scanning line (j = 1, 2, 3, ..., N) shown in FIG.
It is the same as the application start time of 6 and 68. Also, the negative voltage 94
Is the ON voltage applied to the Nth scan line.
It matches the application start time of 67. When the drive waveforms are synchronized as described above, the time during which the hologram is recorded in the optical writing type ferroelectric liquid crystal light valve is 12th.
As shown in FIG. 7D, the period between the application start time of the ON voltage 67 applied to the Nth scan line and the application start time of the OFF voltage 66 applied to the Nth scan line is extremely short. Since it is limited in time, the hologram reproduced image obtained from this time becomes extremely dark. Then, the second
A ferroelectric liquid crystal optical shutter or a magneto-optical optical shutter is arranged between the liquid crystal television 26 and the second half mirror 16 shown in the figure, and an OFF voltage 68 applied to the Nth scanning line is applied. From the time point to the start time of application of the ON voltage 67 applied to the Nth scanning voltage, the ferroelectric liquid crystal optical shutter or the magneto-optical optical shutter is set in the non-transmissive state and applied to the Nth scanning voltage. The ferroelectric liquid crystal optical shutter or the magneto-optical optical shutter is kept in the light transmitting state from the application start time of the ON voltage 67 to an arbitrary time when the OFF voltage 68 applied to the Nth scanning line is applied, The application start time of the positive voltage 92 coincides with the ON voltage application start time applied to the (N-1) th scan line, and the application start time of the negative voltage 94 is the ON voltage 67 applied to the Nth scan line.
A bright hologram reproduced image can be obtained by matching the application start time of. The irradiation intensity of the writing light at this time changes like the writing light 96 shown in FIG. In FIG. 12 (c), when the writing light intensity is weak, only the reference light is applied to the photo-writing type ferroelectric liquid crystal light valve with the uniform light intensity distribution. Therefore, the two-dimensional image information stored in the photowriting type ferroelectric liquid crystal light valve is uniformly erased, and both the reference light and the coherent two-dimensional image are irradiated in a state where the writing light intensity is strong. Therefore, the hologram of the coherent two-dimensional image is recorded in the optical writing type ferroelectric liquid crystal light valve. During that time, the reading surface of the photo-writing type ferroelectric liquid crystal light valve is constantly irradiated with the reading light 95 shown in FIG. 12 (b), so that the photo-writing type ferroelectric liquid crystal light valve is read. The recorded holograms of the coherent two-dimensional image continue to be reproduced one after another.

In the above embodiment, when the visible light reflectance of the dielectric mirror 88 is sufficiently high and the influence of the reading light on the photoconductive layer 86 is small, the light shielding layer 87 can be omitted.

Next, the rotary polygon mirror shown by 19 in FIG. 2 will be described. FIG. 13 is a plan view showing an embodiment of a rotating polyhedral mirror used in the holographic display device of the present invention. 19 is a rotating polyhedral mirror, 19a is a center of rotation, 99 is a rotating shaft, 1
00 is a motor, 101 is a balance weight, 102 is the center of gravity of the rotating polyhedral mirror, 103 is the center of gravity of the balance weight, 104 is the basic constitutional unit of the rotating polyhedral mirror, 105 is the mirror surface of the basic constitutional unit 104, and 106 is the shortest from the center of rotation. A mirror surface at a distance, 107 is a mirror surface at the longest distance from the center of rotation. The rotating polygon mirror 19 has a rotating shaft 99.
Is connected to the motor 100 via, whereby the rotating polygon mirror 19 rotates about the rotation center 19a. As the motor 100, a stepping motor, a DC commutation motor or the like can be used. When a stepping motor is used, the rotary polyhedral mirror 19 can be rotated in synchronization with the input cycle of the three-dimensional image information by synchronizing the drive circuit of the stepping motor with the clock signal that drives the liquid crystal television. it can. When a DC rectifying motor is used, the rotary polygon mirror 19 is rotated in synchronization with a clock signal for driving the liquid crystal television by controlling the rotation speed while detecting the rotation speed of the DC rectifying motor using a rotary encoder or the like. be able to. The rotary polyhedral mirror 19 is configured by a combination of basic structural units 104 of the triangular polygonal rotary polyhedral mirror. The basic constitutional unit 104 of the rotating polygon mirror is formed by molding glass and then polishing the mirror surface 105 and the adhesive surface, or by cutting a metal material such as aluminum by cutting. After that, after forming the basic structural unit 104 of the rotating polygon mirror on the mirror surface 105 of aluminum, silver, or a dielectric multilayer film mirror, the rotating polygon mirror 19 is manufactured by bonding the mirror surface to the outer surface. . Of course, the rotating polyhedron mirror 19 may be directly manufactured by cutting a metal material having a high light reflectance such as aluminum using a method such as diamond cutting. Basic building blocks of rotating polygon mirrors created in this way 10
The distances from the fourth mirror surface 104 to the rotation center 19a differ by the amount of quantization of the input three-dimensional image information in the z-axis direction. As a result, in the embodiment shown in FIG.
The mirror surface at the shortest distance from the rotation center 19a is 106, and the mirror surface at the longest distance from the rotation center 19a is 107. When the rotary polygon mirror 19 shown in FIG. 13 is configured by using the basic constitutional unit 104 of the rotary polygon mirror whose number is twice the number obtained by quantizing the three-dimensional image information displayed in the z-axis direction in such a combination, The center of gravity 102 of this rotating polygon mirror does not coincide with the center of rotation. Therefore, when such a rotating polygon mirror 19 is rotated at a high speed, a biased centrifugal force is applied to the rotating shaft 99, and the rotating shaft 99 is rotated.
A large load is applied to 99 and motor 100,
It cannot rotate uniformly. In order to avoid such a problem, a balance weight 101 that rotates integrally with the rotation is attached. Center of gravity of the balance weight 1
03 is designed so that when combined with the center of gravity 102 of the rotating polyhedron mirror, the overall center of gravity coincides with the center of rotation 19a.
If the balance weight is designed in this way,
It does not have to have a cylindrical shape as shown in FIG.

The rotating polygon mirror 19 produced in this manner is used in the embodiment shown in FIG. When inputting the three-dimensional image information to be displayed using the rotating polygon mirror 19, for example, the three-dimensional image information is displayed at a specific time.
Among the two-dimensional image information generated by quantizing in the axial direction, the two-dimensional image information having the smallest z coordinate value is
The mirror surface 106 at the shortest distance from the center of rotation shown in FIG.
Optical writing type spatial light modulator 20 shown in FIG.
If it is recorded / reproduced as a hologram in the optical writing type spatial light modulator 20 shown in FIG. 2 by the rotation of the rotating polygon mirror 19, the two-dimensional coordinate information having a large z coordinate value one after another. The two-dimensional image information which has been recorded and reproduced as a hologram and has the maximum z coordinate value among the two-dimensional image information generated by quantizing the three-dimensional image information in the z-axis direction is shown in FIG. The data is recorded / reproduced as a hologram in the optical writing type spatial light modulator 20 shown in FIG. 2 by the mirror surface 107 having the longest distance from the rotation center shown in FIG. Subsequently, the two-dimensional coordinate information having smaller z-coordinate values one after another is recorded / reproduced as a hologram on the optical writing type spatial light modulator 20 shown in FIG. 2 by the rotation of the rotary polygon mirror 19. Then, the two-dimensional image information having the smallest z coordinate value among the two-dimensional image information generated by quantizing the three-dimensional image information in the z-axis direction is again the rotation center shown in FIG. Is recorded / reproduced as a hologram on the optical writing type spatial light modulator 20 shown in FIG. Thus, the three-dimensional image information to be displayed must be scanned and displayed twice in the z-coordinate direction while the rotating polygon mirror 19 rotates once. Therefore, the signals of the two-dimensional image information sent to the liquid crystal television 26 are transmitted in order from the smallest z component in the z-coordinate direction quantized component of the three-dimensional image information, and after reaching the maximum value of z, z
From the largest to the smallest value of z, and such a transmission method must be repeated. Such use of the rotating polygon mirror 19 reduces the load on the mechanism for rotating the rotating polygon mirror 19, but does not impose a load on the signal processing system for transmitting the two-dimensional image information signal. growing.

In order to avoid such problems, the rotating polygon mirror shown in FIG. 14 was constructed. The rotating polygon mirror shown in FIG.
The difference from the rotating polygon mirror shown in Fig. 13 is that the basic constituent units 104 of the rotating polygon mirror are arranged adjacent to each other so that the distance from the rotation center to the mirror surface increases (or decreases) in order, and the rotation center The shortest distance from the mirror surface 106
And the mirror surface 107, which is the longest distance from the center of rotation, are adjacent to each other. Such a rotating polygon mirror shown in FIG.
By using 19 in place of the rotating polygon mirror 19 shown in FIG. 2, the signal of the two-dimensional image information sent to the liquid crystal television 26 of FIG. 2 is a quantized component in the z-coordinate direction of the three-dimensional image information. Among the quantized components in the z-coordinate direction of the three-dimensional image information, z is transmitted in order from the smallest z (or the largest z) and reaches the maximum value of z.
It is possible to use a normal signal transmission method in which the maximum value of z is reached in order from the smallest one (or the largest z). Further, the rotating polygon mirror 19 is 1
Since the displayed three-dimensional image information is scanned and displayed only once in the z-coordinate direction during one rotation, the signal transmitted for inputting the two-dimensional image information and the rotation of the rotating polyhedral mirror 19 are rotated. It becomes extremely easy to synchronize the numbers. Further, even if the number of quantized three-dimensional image information to be displayed in the z-coordinate axis direction increases, mirror surface division of the rotating polygon mirror can be performed at all angles of 360 degrees, which facilitates production of the rotating polygon mirror. There is an advantage called.

When inputting three-dimensional image information using the rotating polygon mirror described above, as the number of quantization in the z-coordinate axis direction of the displayed three-dimensional image increases, it becomes difficult to process and manufacture the rotating polygon mirror. Come on. In such a case, the second
It is preferable to use a rotating cylindrical mirror instead of the rotating polygon mirror 19 shown in the figure. FIG. 3 is a block diagram of an embodiment of the holographic display device of the present invention in which a rotating cylindrical mirror is used as the optical path length conversion means. The difference between FIG. 2 and FIG. The point is that a rotating cylindrical mirror 27 is used instead of the rotating polygon mirror 19 in the figure. FIG. 15 shows a plan view of the rotating cylindrical mirror 27 used in FIG. 15 is different from FIG. 13 only in that a rotating cylindrical mirror 27 is used in FIG. 15 instead of the rotating polygon mirror 19 in FIG. In this case, the basic structural unit of the rotating cylindrical mirror is a rectangular plane having the generatrix of the rotating cylindrical mirror and the center of rotation 27a on two opposite sides, and its mirror surface coincides with the generatrix of the rotating cylindrical mirror. Even when such a rotating cylindrical mirror is used, the luminous flux irradiated to the rotating cylindrical mirror 27 by the first imaging lens 17 of FIG. 3 is larger than the radius of curvature of the rotating cylindrical mirror 27. If the beam is irradiated sufficiently on the rotating cylindrical mirror so that the mirror surface can be regarded as a flat surface, the beam irradiated on the rotating cylindrical mirror 27 is It is reflected as in the case of using the rotating polygon mirror shown in FIG. However, as in the case of using the rotating polygon mirror shown in FIG. 13, when the rotating cylindrical mirror shown in FIG. 15 is used, the three-dimensional image information displayed above is the z coordinate while the rotating cylindrical mirror 27 rotates once. It has to be scanned twice in the direction and displayed. Therefore, the signal of the two-dimensional image information sent to the liquid crystal television 26 in FIG. 3 is transmitted in order from the smallest z component in the z coordinate direction quantized component of the three-dimensional image information, and reaches the maximum value of z. After that, it is transmitted in order from the largest z and transmitted so as to reach the minimum value of z, and such a transmission method must be repeated. Using such a rotating cylindrical mirror 27 reduces the load on the mechanism for rotating the rotating cylindrical mirror 27, but does not impose a burden on the signal processing system for transmitting the signal of the two-dimensional image information. growing. Such a problem can be solved by using the rotating cylindrical mirror 27 as shown in FIG. 16 as in the case of the rotating polygon mirror. The rotating cylindrical mirror 27 shown in FIG. 16 has an asymptotic shape when the number of mirror surfaces of the rotating polyhedral mirror shown in FIG. 14 becomes infinitely large. That is, the curve of the mirror surface of the rotating cylindrical mirror shown in FIG. 16 has an origin at the center of rotation 27a and an original boundary line between the mirror surface 106 having the shortest distance from the center of rotation and the mirror surface 107 having the longest distance from the center of rotation. When polar coordinates are displayed as a line, r = (bθ / 2πa), where r is the radius, θ is the declination, a is the shortest distance from the origin to the mirror surface, and b is the longest distance from the origin to the mirror surface. ) + A, (0 ≦ θ ≦ 2π, r>
It becomes a part of Archimedes' spiral represented by 0). First
Although it is extremely difficult to process the mirror surface as shown in FIG. 16, by using such a rotating cylindrical mirror 27, the signal of the two-dimensional image information sent to the liquid crystal television 26 of FIG. , Of the quantized components in the z-coordinate direction of the three-dimensional image information, the z-coordinates of the three-dimensional image information are transmitted again after the z values are transmitted in order from the smallest z (or the largest z). Among the directional quantized components, a normal signal transmission method can be used in which the signals are transmitted in ascending order of z (or in order of increasing z) to reach the maximum value of z. Further, since the three-dimensional image information to be displayed is scanned and displayed only once in the z coordinate direction while the rotating cylindrical mirror 27 rotates once, the three-dimensional image information to be displayed is transmitted for inputting the two-dimensional image information. It becomes extremely easy to synchronize the signal and the rotation speed of the rotating cylindrical mirror 27.

2 and 3, by using the rotating polygon mirror 19 or the rotating cylindrical mirror 27 described above, the coherent two-dimensional image information input by the liquid crystal television 26 is written on the writing surface of the optical writing type spatial light modulator 20. The optical path length to reach the position of the optical writing type spatial light modulator changes depending on the position where the coherent two-dimensional image information is reflected by the rotating polyhedral mirror 19 or the rotating cylindrical mirror 27.
A pseudo three-dimensional image is reproduced from the hologram recorded in 20. The reproduced pseudo three-dimensional image can be reproduced as a real image or a virtual image depending on the position of the imaging lens 24. That is, when the imaging lens 24 is a convex lens and the pseudo three-dimensional image is reproduced by the optical writing type spatial light modulator 20 from the front focal plane of the convex lens, it is reproduced as a real image, and the pseudo image is reproduced. When the three-dimensional image is reproduced between the front focal plane of the convex lens and the convex lens, it is reproduced as a virtual image. Since it is preferable that the light source 21 for reproduction used in the present invention has an extremely high illuminance, it is preferable for safety that the pseudo three-dimensional image is reproduced as a virtual image.

FIG. 18 shows a pseudo three-dimensional image reproduced when the still two-dimensional image shown in FIG. 17 is input to the liquid crystal television 26 in the holographic display device of the present invention shown in FIG. In FIG. 18, the z direction coincides with the optical axis direction of the reproduction light. Further, the number of quantization in the z coordinate axis direction of the input three-dimensional image is 11. The difference between the maximum value and the minimum value of the Z coordinate of the reproduced pseudo three-dimensional image is proportional to twice the eccentric distance of the rotation axis of the rotating polygon mirror or the rotating cylinder mirror.

However, when an attempt is made to reproduce a pseudo three-dimensional image as shown in FIG. 18 by using the holographic device of the present invention shown in FIG. 2 and FIG. The size of the two-dimensional image displayed on the liquid crystal television 26 must be corrected in advance by the image calculation processing section 35 shown. This is because, in FIGS. 2 and 3, the distance between the two-dimensional image displayed on the liquid crystal television 26 and the optical writing type spatial light modulator 20 on which the image is formed is equal to that of the rotating polyhedral mirror 19 or the rotating cylindrical mirror. Since the rotation is substantially changed by the rotation of 27, a two-dimensional image with a magnification corresponding to the change in the distance is imaged on the optical writing type spatial light modulator 20, and the reproduced three-dimensional image is shown in FIG. This is because the image is distorted in the z coordinate axis direction as shown.

FIG. 4 shows an embodiment of a method for reducing the burden on the preprocessing of such an input two-dimensional image. FIG. 4 is a block diagram showing an embodiment of the holographic display device of the present invention, 11 is an argon ion laser, 12 is a first beam expander, 13 is a first half mirror, and 14 is a first Mirror, 15 is the second mirror, 16 is the second half mirror, 17
Is a first imaging lens, 18 is an optical stopper, 27 is a rotating cylindrical mirror, 27a is the center of rotation of the rotating cylindrical mirror, 20 is an optical writing type spatial light modulator, 21 is a helium neon laser, and 22 is a second beam. Expander, 23 is a polarization beam splitter, 24 is a second imaging lens, 25 is a computer, 26 is a liquid crystal TV,
36 is a third beam expander. In FIG. 4, the coherent light beam emitted from the argon ion laser 11 is expanded to a required beam diameter by the first beam expander 12 and then split into two light beams by the first half mirror 13. The light flux reflected by the first half mirror 13 is the first
The two-dimensional image displayed on the liquid crystal television 26 after being reflected by the mirror 14 is converted into a coherent two-dimensional image, and the coherent two-dimensional image is reflected by the second mirror 15 and then the first imaging lens 17 Then, an image is formed and irradiated on the writing surface of the optical writing type spatial light modulator 20 via the second half mirror 16. On the other hand, the luminous flux transmitted through the first half mirror 13 is the first
After passing through the half mirror 16 of the rotating beam, the beam is reduced to a required beam diameter by the third beam expander 36, and then the rotating cylindrical mirror 27.
After being reflected by the third beam expander 36, the beam diameter is expanded again to a required beam diameter, and after being reflected by the second half mirror 16, the writing surface of the optical writing spatial light modulator 20 is irradiated with the reference light. , The coherent two-dimensional images interfere with each other, and as a result, the optical writing type spatial light modulator 20.
A hologram of the coherent two-dimensional image is formed on the. The angle formed by the reference light and the coherent image is about 10 degrees or less. At this time, the optical stopper 18 is a rotating cylindrical mirror.
Only the light beam reflected vertically from 27 is arranged to block unnecessary light beams so that the light writing surface of the optical writing type spatial light modulator 20 is irradiated with the light beam. In addition, a rotating cylindrical mirror
The rotation center 27a of 27 is eccentric, and when the distance from the rotation center 27a to the shortest mirror surface is a and the distance to the longest mirror surface is b, ba is a two-dimensional image displayed on the liquid crystal television 26. Is more than the distance in the quantization direction of the three-dimensional image. The rotation speed of the rotating cylindrical mirror 27 per second is equal to the frame rate of the liquid crystal television 26.

On the other hand, the laser light emitted from the helium neon laser 21 has its beam diameter expanded by the second beam expander 22 to a predetermined size, is then reflected by the polarization beam splitter 23, and is used as the optical writing type spatial light modulator 20. The reading surface is irradiated with the reference light in the same direction and in the opposite direction to reproduce the hologram of the coherent two-dimensional image formed in the optical writing type spatial light modulator. The coherent two-dimensional image hologram thus reproduced can be expanded and reproduced to a desired size by the second imaging lens 24 after passing through the polarization beam splitter 23.

As described above, the holographic display device of the present invention shown in FIG. 4 is different from the holographic display device shown in FIGS. 2 and 3 in that the optical writable spatial light modulator 20 has a coherent two-dimensional image. In forming a hologram, the optical path length of the reference light is modulated without modulating the optical path length of the coherent two-dimensional image. Thus, in holography, by changing the relative phase relationship between the coherent two-dimensional image and the reference light, a pseudo three-dimensional image substantially similar to that shown in FIGS. 2 and 3 is reproduced. be able to. However, it should be noted that the pseudo three-dimensional image reproduced in this case has the z-coordinates whose positive and negative values are opposite to those of the pseudo three-dimensional image reproduced in FIGS. 2 and 3. Must. If it is desired to reproduce a pseudo three-dimensional image having the same z-coordinate polarity as the pseudo three-dimensional image reproduced in FIGS. 2 and 3, the quantized three-dimensional image to be sent to the liquid crystal television 26. It is necessary to invert the z-coordinate axis in advance and send it to the liquid crystal television 26.

Thus, when the pseudo three-dimensional image is reproduced using the input image shown in FIG. 17 by using the holographic display device of the present invention shown in FIG.
A pseudo three-dimensional image as shown in the figure is obtained.

In FIG. 21, the circular figure shown in FIG. 17 is used as a two-dimensional input image, and its radius r · cos (z): (r is the radius of the circle when z = 0) changes in the z coordinate axis direction. Let me 4th
An example in which a pseudo three-dimensional image is reproduced by using the holographic display device of the present invention shown in the figure is shown. As described above, it is obvious that the holographic display device of the present invention can display a three-dimensional image whose shape changes in the z-coordinate direction.

Further, since the tomographic images of the object are successively input as two-dimensional images to the holographic display device of the present invention to reproduce the pseudo three-dimensional image, the internal structure can be seen through from the outside. It is possible to perform more accurate and easy-to-understand medical activities by using it for three-dimensional tomographic diagnosis, and for example, it is possible to conduct more realistic research by using it for tracking fluid motion in a structure.

FIG. 19 shows another embodiment of the holographic display device of the present invention. In FIG. 19, 108 is a first optical writing type spatial light modulator, 109 is a second spatial light modulator, and 110 is a third spatial light modulator.
Is an image forming lens, 111 is a CRT, and 112 is a third half mirror. 19 is different from FIG. 4 in that instead of the liquid crystal television 26 as the two-dimensional image information input means, the first optical writing type spatial light modulator 108 and the CRT 111 and the information addressing means for the spatial light modulator 108 are provided. That is, the third imaging lens 110 is used. As the first optical writing type spatial light modulator 108 and the second optical writing type spatial light modulator 109 in FIG. 19, the optical writing type liquid crystal light valve shown in FIG. 11 can be used. At this time, the two-dimensional image information transferred from the computer 25 is converted into an incoherent two-dimensional image by the CRT 111, and the incoherent two-dimensional image is converted by the third imaging lens 110 into the optical writing type spatial light modulator 108. An image is formed / irradiated on the writing surface and stored in the optical writing type spatial light modulator 108. The stored two-dimensional image is read out by the coherent light beam emitted from the argon ion laser 11, converted into a beam diameter of a required size by the first beam expander 12, and reflected by the first half mirror 13. Converted into a coherent two-dimensional image. After that, a pseudo three-dimensional image is obtained in the same manner as described with reference to FIG.

In FIG. 19, the first optical writing type spatial light modulator 108 is shown.
CRT111 and the third method for addressing 2D image information to
Needless to say, instead of the imaging lens 110, a laser light source and a scanning optical system that condenses the laser light source and scans the recording surface of the first optical writing type spatial light modulator 108 at high speed may be used. At this time, if the optical writing type ferroelectric liquid crystal light valve shown in FIG.
If you use a semiconductor laser with m and output of 20 nW and record a writing beam diameter of 5 μm, you can perform digital recording in several tens of nanoseconds per bit. Can be recorded at.

The rotary polyhedral mirror 19 or the rotary columnar mirror 27 shown in FIGS. 2, 3 and 4 is the same as the rotary polyhedral mirror or the rotary columnar mirror shown in FIGS. 13 and 14 and FIGS. 15 and 16. It goes without saying that either may be used.

Further, in place of the argon ion laser 11 shown in FIGS. 2, 3 and 4, a high-order harmonic of a helium neon laser or a YAG laser or a semiconductor laser, which has good coherence and is used for the optical writing used in the holographic display device. -Type spatial light modulator 20 photoconductive layer 86
It goes without saying that any light source may be used as long as it is capable of generating a light flux with high sensitivity.

Further, as the light source 21 in FIGS. 2, 3, and 4, an argon ion laser, a semiconductor laser, a mercury lamp, a xenon lamp, or a resistance heating light source may be used instead of the helium neon laser. However, when a mercury lamp, a xenon lamp, or a resistance heating light source is used as the light source 21, it is necessary to dispose a narrow band filter at a position on any optical path between the light source 21 and the optical writing type spatial light modulator 20. .

[Effects of the Invention] As described above, the holographic display device and its driving method of the present invention record the holography formed by the optical holography forming means including the coherent light source and the interference optical system. Holographic display device for reproducing a hologram formed on the spatial light modulator by an image information reproducing means including an optical writing type spatial light modulator for controlling the light source, a reading light beam generating optical system, and a reproduction light expanding image forming optical system. In the interference optical system, there is provided an electrically or optically addressable image information input means and an optical path length conversion means for periodically changing the optical path length, The two-dimensional image information obtained by quantizing the image in a desired dimensional direction is used as the image information input means. Since the pseudo three-dimensional image information can be displayed in real time by having a means for inputting in synchronization with the optical path length changing period of the optical path length conversion means, it is possible to use a three-dimensional image for products and construction. It has an extremely large effect when designing things. Alternatively, the three-dimensional image information stored in advance can be used for a simulation for performing, for example, molecular design or fluid structure design. Needless to say, it also has an effect as a demonstration display for an unspecified large number.

[Brief description of drawings]

FIG. 1 is a block diagram showing the configuration of the holographic display device of the present invention. FIG. 1 (a) shows the case where the image information input means and the optical path length conversion means are in parallel, and FIG. 1 (b) shows the image information input. FIG. 2 and FIG. 3 and FIG. 4 and FIG. 19 are configuration diagrams of one embodiment of the holographic display device of the present invention, and FIG. 5 and FIG. FIG. 6 is a block diagram showing an embodiment of the signal flow in the three-dimensional image storage means of the holographic display device of the present invention, and FIG. 7 shows an example of a liquid crystal television used in the holographic display device of the present invention. FIG. 7A is a configuration diagram showing an example of a circuit block of a liquid crystal television used in the holographic display device of the present invention, and FIG. 7B is used in the holographic display device of the present invention. LCD TV pixel section A block diagram showing an example of the formation, eighth
FIG. 8 is a block diagram showing an example of a circuit block of a liquid crystal television used in the holographic display device of the present invention. FIG. 8 (a) shows a case where the pixel region is not divided, and FIG. 8 (b) shows a pixel electrode. FIG. 10 is a structural exploded perspective view showing an embodiment of the liquid crystal television used in the present invention, and FIG. 9 is a scanning of the liquid crystal television used in the holographic display device of the present invention. FIG. 11 is a voltage waveform diagram, FIG. 11 is a cross-sectional view showing the structure of the optical writing type ferroelectric liquid crystal light valve used in one embodiment of the present invention, and FIG.
FIG. 13 is an optical response characteristic diagram of the photo-writing type ferroelectric liquid crystal light valve used in the examples, and FIGS. 13 and 14 are plan views showing one example of the rotating polyhedral mirror used in the holographic display device of the present invention. FIG. 15 and FIG. 16 are plan views showing an embodiment of a rotating cylindrical mirror used in the holographic display device of the present invention, and FIG. 17 is an example of an input image of the holographic display device of the present invention. FIG. 18 is an example of a pseudo three-dimensional image of the holographic display device of the present invention. FIG. 20 is an example of a pseudo three-dimensional image when the size of the two-dimensional image is not corrected in the holographic display device of the present invention, and FIG. 21 is a pseudo three-dimensional image of the holographic display device of the present invention. Another example. 1 ... Optical holography forming means 2 ... Image information reproducing means 3 ... Coherent light source 4 ... Interference optical system 5 ... Optical writing type spatial light modulator 6 ... Image information input means 7 ... Optical path length conversion means 8 ... Light source 9 ... Read-out light flux generating optical system 10 ... Three-dimensional image storage means 11 ... Argon ion laser 12 ... First beam expander 13 ... First half mirror 14 ... First mirror 15 …… Second mirror 16 …… Second half mirror 17 …… First imaging lens 18 …… Optical stopper 19 …… Rotating polyhedral mirror 19a …… Rotation center 20 …… Optical writing spatial light modulator 21 …… Helium neon laser 22 …… Second beam expander 23 …… Polarization beam splitter 24 …… Second imaging lens 25 …… Computer 26 …… LCD TV 27 …… Rotating cylindrical mirror 27a …… Rotation center 28 …… 3D image input section 29 Numeralizing unit 30 ... Memory 31 ... Z coordinate quantizing unit 32 ... xy coordinate quantizing unit 33 ... Output signal converting unit 34 ... Image information input means driving unit 35 ... Image arithmetic processing unit 36 ... ... third beam expander 37 ... y-coordinate division unit 38 ... first memory unit 39 ... second memory unit 40 ... nth memory unit 41 ... first output signal conversion unit 42 ... … Second output signal conversion unit 43 …… Nth output signal conversion unit 44 …… First Y driver 45 …… Second Y driver 46 …… Nth Y driver 47 …… Clock signal 48 …… LCD TV board 49 …… X driver 50 …… Y driver 51 …… Pixel area 52 …… Transistor 53 …… Signal line 54 …… Scan line 55 …… Pixel electrode 56 …… Latch 61 …… First scan line ON voltage 62 applied to the first scanning line 63 OFF voltage applied to the first scanning line 63 ON voltage applied to the second scanning line 64… To the second scanning line OFF voltage 65 …… ON voltage applied to the 3rd scanning line 66 …… OFF voltage applied to the 3rd scanning line 67 …… ON voltage applied to the Nth scanning line 68 …… Nth scanning OFF voltage applied to the line 69a, 69b …… Polarizer 70 …… Glass carrier 71 …… Common electrode 73 …… Liquid crystal layer 77 …… Single crystal silicon semiconductor layer 80 …… Quartz glass carrier 81a, 81b …… Transparent substrate 83a, 83b …… Transparent electrode layers 84a, 84b …… Alignment film layer 85 …… Ferroelectric liquid crystal 86 …… Photoconductive layer 87 …… Light-shielding layer 88 …… Dielectric mirror 89a, 89b …… Reflective coating 90 …… Spacer 91 …… Drive waveform 92 …… Positive voltage 93 …… Negative voltage 94 …… Zero voltage 95 …… Read light 96 …… Write light 97 …… Bright state 98 …… Dark state 99 …… Rotary axis 100 …… Motor 101 …… Balance weight 102 …… Center of gravity of rotating polygon mirror 103 …… Center of gravity of balance weight 104 …… Basic structural unit of rotating polygon mirror 105 …… Basic structure Unit mirror surface 106 …… Mirror surface with the shortest distance from the rotation center 107 …… Mirror surface with the longest distance from the rotation center 108 …… First optical writing type spatial light modulator 109 …… Second optical writing spatial light Modulator 110 …… Third imaging lens 111 …… CRT 112 …… Third half mirror

Claims (10)

(57) [Claims] 1. An optical holography forming means comprising a coherent light source and an interference optical system, an optical writing type spatial light modulator for recording holography formed by the holography forming means, a light source and a reading light flux generating optical system. In a holographic display device for reproducing a hologram formed on the spatial light modulator by an image information reproducing means composed of an enlarged image forming optical system for reproducing light, an electrically or optically addressable image information inputting means and a periodical means. A two-dimensional image obtained by quantizing the three-dimensional image in a desired dimensional direction from the three-dimensional image information storage means having an optical path length converting means for changing the optical path length in the interference optical system. A means for inputting information to the image information input means in synchronism with the optical path length changing period of the optical path length conversion means is provided. And a holographic display device. 2. An optical path length conversion means for periodically changing the optical path length is the same scale as the size of the two-dimensional image information displayed on the image information input means, and the three-dimensional direction is the quantization direction of the two-dimensional image. 2. The holographic display device according to claim 1, which comprises a rotating polygon mirror or a rotating cylindrical mirror having a rotation axis eccentric by half the size of the image, and its rotating means such as a motor. 3. The holographic display device according to claim 1 or 2, wherein the image information input means is a transmissive liquid crystal display in which single crystal thin film transistors are arranged in a matrix form to drive a ferroelectric liquid crystal. 4. A holographic display device according to claim 1 or 2, wherein the image information input means comprises a CRT, an imaging optical system or a laser scanning device, and an optical writing type spatial light modulator. 5. An optical writing type spatial light modulator comprising a photoconductive layer,
A light reflection layer, a liquid crystal alignment layer, a ferroelectric liquid crystal layer having a bistable memory property between the light reflectance and an applied voltage, a voltage applying means,
The holographic display device according to claim 1, 2, 3, or 4, which is an optically writable liquid crystal light valve made of a transparent substrate. 6. An image forming optical system is arranged in an optical path between the image information inputting means and the optical writing type spatial light modulator, claim 1, claim 2 and claim 3, Claim 4
Alternatively, the holographic display device according to claim 5. 7. The coherent light source of the holography forming means is a gas laser such as a helium neon laser or an argon ion laser or a semiconductor laser.
The holographic display device according to claim 2, claim 3, claim 4, claim 5, or claim 6. 8. A light source of the image information reproducing means is a gas laser such as a helium neon laser or an argon ion laser, a visible light semiconductor laser, a light emitting diode, a mercury lamp, a xenon lamp or a resistance heating light source. The holographic display device according to claim 3, claim 4, claim 5, claim 6, or claim 7. 9. When a three-dimensional object image is represented by a three-dimensional Gaussian coordinate system, three-dimensional image information is quantized to a predetermined size in the z-axis direction on a two-dimensional plane represented by xy coordinates and stored in a memory space. Image information of a two-dimensional plane, which is stored and expressed by xy coordinates, is sequentially input in synchronization with one-half the quantization number in the z-axis direction of the cycle of the optical path length conversion device that periodically changes the optical path length. Claim 1, claim 2, claim 3,
A driving method of a holographic display device according to claim 4, claim 5, claim 6, claim 7, claim 8 or claim 9. 10. As a display system of a transmissive liquid crystal display, a voltage applied to each display segment is sequentially applied in the xy direction, and a display segment which has been turned on once is turned off until display of one image frame is completed. The display method is used in which the image information is turned off, and when the image information is off, the display method is synchronized with the end of one frame input of the transmissive liquid crystal display.
Claim 4, Claim 5, Claim 6, Claim 7, Claim 8,
Alternatively, the holographic display device driving method according to claim 9.