JP7355146B2 - 3D image display device and 3D image display method - Google Patents

Description

The present invention relates to a stereoscopic image display device and a stereoscopic image display method.

Holography technology is known as a technology for displaying three-dimensional stereoscopic images that is consistent with binocular parallax, convergence, and eye accommodation. In addition, two-dimensional wavefront modulation devices such as LCD (Liquid Crystal Display), LCOS (Liquid Crystal on Silicon), and DMD (Digital Mirror Device) generate playback light with a wavefront corresponding to a three-dimensional stereoscopic image, and the frame rate A technique is known that displays a three-dimensional stereoscopic moving image, that is, a holographic image, by switching the reproduction light accordingly.

As a display technology for holographic images, for example, a technique is disclosed in which the viewing angle of a holographic image is expanded by increasing the wavefront modulation accuracy of reproduced light by a two-dimensional wavefront modulator (for example, Patent Document 1 reference). In addition, by expanding the reproduction light by the DMD vertically and reducing it horizontally, and connecting it in the reproduction space while scanning it horizontally with a galvano mirror, the horizontal viewing angle of the holographic image can be adjusted. A technique for enlarging has been disclosed (for example, see Non-Patent Document 1).

However, according to the technology of Patent Document 1, in order to display a large-sized three-dimensional stereoscopic image, it is necessary to enlarge the reproduction light, and the viewing angle decreases due to enlargement, so a large-sized image with a wide viewing angle is required. It has been difficult to display a three-dimensional stereoscopic image.

Furthermore, in the technique of Non-Patent Document 1, the size of the galvano mirror is a constraint, and there is a limit to displaying a large-sized three-dimensional stereoscopic image.

The present invention has been made in view of the above points, and an object of the present invention is to display a large-sized three-dimensional stereoscopic image while ensuring a wide viewing angle.

A stereoscopic image display device according to one aspect of the disclosed technology is a display device that displays a holographic image, and includes a plurality of light deflection elements each having a side length of 1.0 to 1.2 μm in a two-dimensional manner. an optical deflection element array that deflects incident coherent light with each of the optical deflection elements based on an interference fringe pattern corresponding to the holographic image, and generates reproduction light; a scanning means for scanning the reproduction light in a plane intersecting the optical axis of the reproduction light; controlling generation of the reproduction light by the optical deflection element array according to the scanning; a reproduction control means for forming the holographic image by connecting the reproduced light beams, and an optical path of the reproduction light between a position where the optical deflection element array is disposed and a third position where the scanning means is disposed. a first optical system that adjusts the size of the reproduction light at the third position, the center of the reproduction light within the plane determined by the scanning angle by the scanning means at the first position; The size at the first optical system is equal to the size at the second position where the optical deflection element array is arranged, and the minimum width of the interference fringe at the first position is equal to the size at the second position where the optical deflection element array is disposed via the first optical system. maintaining a viewing angle equal to a minimum width of interference fringes at the position, and the holographic image at the first position is a combination of reproduced light at a second position where the optical deflection element array is arranged; The optical deflection element has a substrate, a fulcrum member, a plurality of regulating members, a plate-like member, and a plurality of electrodes, and the fulcrum member has a top portion, and the optical deflection element has a Each of the regulating members is provided on an upper surface, and each of the regulating members has a stopper on the upper part, and is provided at an end of the plate-like member, and the plate-like member has a light reflecting surface and a conductive part. One surface of the shaped member is supported by the fulcrum member by contacting the top, and is movable within a range defined by the substrate and the regulating member without having a fixed end, and each of the electrodes is , is provided on the substrate to face the conductive part of the plate-like member, and due to electrostatic attraction generated between the conductive part and the electrode, the plate-like member moves to the base with the top as a fulcrum. By forming an inclination determined by the interference fringe pattern and the position of the light source, the light reflected by the light reflecting surface is deflected, and by making the size at the first position and the second position equal, the reproduction control means The holographic image can be formed while maintaining the viewing angle, and the reproduction control means applies a driving voltage for tilting the plate member to one optical deflection element, and then The driving voltage is applied to another optical deflection element before the operation of tilting the plate-like member of the optical deflection element ends.

A large three-dimensional image can be displayed while ensuring a wide viewing angle.

FIG. 3 is a diagram illustrating recording and reproduction of a three-dimensional stereoscopic image using holography. FIG. 1 is a diagram illustrating an example of the configuration of a display device according to a first embodiment. FIG. 2 is a diagram illustrating an example of the hardware configuration of a display device according to a first embodiment. FIG. 1 is a diagram illustrating an example of a functional configuration of a display device according to a first embodiment. 3 is a flowchart illustrating an example of a processing flow by a control device of a display device according to the first embodiment. FIG. 3 is a diagram schematically illustrating a hologram formed by an optical deflection element array. FIG. 2 is a diagram illustrating an example of a device configuration when a variable magnification lens is provided in the display device of the first embodiment. FIG. 3 is a diagram illustrating the configuration of a light deflection element array in the first embodiment. FIG. 7 is a diagram illustrating a method of driving an optical deflection element in a second embodiment. FIG. 7 is a diagram illustrating a configuration example of a display device according to a third embodiment. FIG. 7 is a diagram illustrating a configuration example of a display device according to a fourth embodiment.

First, as a premise of this embodiment, the principle of holography will be explained using FIG. 1. Note that hereinafter, a three-dimensional stereoscopic image will be simply referred to as a stereoscopic image.

FIG. 1(a) explains recording of a three-dimensional image by holography. In FIG. 1(a), an object 101 is illuminated with illumination light 102. In FIG. Irradiation light 102 is coherent light such as a laser. Object light 103 reflected by object 101 is superimposed and interferes with reference light 104 obtained by amplitude division or wavefront division of irradiation light 102. Interference fringes 105 caused by interference between the object beam 103 and the reference beam 104 are recorded on a recording medium such as a photographic plate. A photographic plate is a type of light-sensitive material in which a photographic emulsion is coated on a colorless and transparent glass plate. By developing the photographic plate, a hologram 106 on which interference fringes 105 are recorded is obtained.

FIG. 1(b) illustrates reproduction of a three-dimensional image by holography. When the hologram 106 is irradiated with the same reference light 104 as used during recording, the reference light 104 is diffracted by the interference fringes 105 recorded on the hologram 106 and becomes a reproduction light 107 that behaves in the same manner as the object light 103. When the hologram 106 is observed from the side opposite to the side irradiated with the reference beam 104 using the reproduction light 107, a three-dimensional image 108 of the object 101 is reproduced at the position where the object 101 was. The three-dimensional image 108 in this case is a virtual image formed by the -1st order diffracted light of the reference light 104 by the hologram 106. On the other hand, on the observer side, a real image formed by the +1st-order diffracted light of the reference light 104 by the hologram 106 is reproduced.

The above is analog holography in which interference fringes are recorded on a photographic plate and reproduced, but interference fringes, or holograms, can be formed using a digital device called a two-dimensional wavefront modulator. By irradiating the reference light onto the two-dimensional wavefront modulator that acts as a hologram, a three-dimensional image can be reproduced and displayed. Furthermore, by switching the stereoscopic image according to the frame rate, a moving image of the stereoscopic image, that is, a holographic image can be displayed.

Interference fringes obtained by interference between the object light and the reference light can be obtained by computer calculation. Interference fringes generated by computer calculation are called CGH (Computer Generated Hologram). In this embodiment, reproduction and display of a holographic image using CGH data will be described as an example.
[First embodiment]
A first embodiment will be described with reference to the drawings. In each drawing, the same components are given the same reference numerals, and redundant explanations may be omitted.

FIG. 2 shows an example of the configuration of the display device of this embodiment. FIG. 2A shows the arrangement of components in the display device 200 and a front view of a space in which a stereoscopic image is reproduced by the display device 200. FIG. 2B shows the positional relationship between the stereoscopic image reproduced by the display device 200 and the viewer.

In FIG. 2A, the display device 200 includes light sources 201r, 201b, and 201g. The light sources 201r, 201b, and 201g are lasers that emit coherent light having red, blue, and green wavelengths, and are, for example, semiconductor lasers. Alternatively, a light source with higher coherence, that is, a longer coherence distance, such as a DPSS (Diode Pumped Solid State) laser, may be used.

The display device 200 also includes a control device 202 and light deflection element arrays 203r, 203b, and 203g. The control device 202 is connected to the optical deflection element arrays 203r, 203b, and 203g, and outputs CGH data corresponding to red, blue, and green, respectively. CGH data is an example of reproduction light data having a wavefront corresponding to a holographic image.

Each of the optical deflection element arrays 203r, 203b, and 203g is a device in which a plurality of optical deflection elements are two-dimensionally arranged. The plurality of optical deflection elements move independently according to CGH data input from the control device 202, and form interference fringes having a two-dimensional pattern, that is, a hologram. The positions where the optical deflection element arrays 203r, 203b, and 203g are arranged are examples of second positions where the optical deflection element arrays are arranged.

The light deflection element arrays 203r, 203b, and 203g modulate the irradiated light by deflecting the light emitted from the light sources 201r, 201b, and 201g, and generate reproduced light. Furthermore, by switching the CGH data input from the control device 202 in time series, the generated reproduction light is switched in time series.

The reproduction light generated by the optical deflection element arrays 203r, 203b, and 203g is an example of reproduction light having a wavefront corresponding to a holographic image. Note that details of the configuration and movability of the optical deflection element array will be described later.

The display device 200 further includes light shielding plates 204r, 204b, and 204g, a combining prism 205, and a micromirror 206.

Each of the light shielding plates 204r, 204b, and 204g is, for example, a pinhole formed by making a minute through hole in a thin metal plate. In order to prevent light reflected from the thin metal plate, which causes flare light, the surface of the metal thin plate is treated with flocked paper or the like. The light blocking plates 204r, 204b, and 204g block reflected light from the light deflection elements in the OFF state, which will be described later.

The combining prism 205 combines the light that has passed through the light shielding plates 204r, 204b, and 204g. Three monochromatic reproduction lights generated by each of the light deflection element arrays 203r, 203b, and 203g are combined by a combining prism 205 to become one color reproduction light.

The micromirror 206 reflects the light combined by the combining prism 205 and scans the reflected light in the horizontal and vertical directions. In FIG. 2(a), the X direction indicated by the arrow is the horizontal direction, and the Y direction is the vertical direction.

The micromirror 206 is, for example, a MEMS (Micro Electromechanical System) device. In the micromirror 206, a movable part having a light reflecting surface is formed to be rotatable around a first axis parallel to the X direction and a second axis parallel to the Y direction. The micromirror 206 two-dimensionally scans the light reflected by the light reflecting surface within the target area by rotating the movable part around each axis. The micromirror 206 is manufactured by finely processing silicon or glass using, for example, semiconductor process technology.

The reproduction space 207 is a space in which reproduction light from each of the optical deflection element arrays 203r, 203b, and 203g forms an image, or approximately forms an image. In other words, the reproduction space 207 is a three-dimensional space in which a three-dimensional image reproduced by the optical deflection element arrays 203r, 203b, and 203g that act as holograms is displayed. Here, "substantially imaged" does not mean only a state where the image is completely formed, that is, a state where the image is completely in focus, but also means that some deviation of the image formation, that is, a deviation of the focus is allowed. Note that although the stereoscopic image displayed in this embodiment is a real image, a configuration may be adopted in which a virtual image is displayed.

The reproduction light is scanned within the XY plane 207a by the micromirror 206. The XY plane 207a is a plane cut out from the playback space 207, and is, for example, the plane indicated by the two-dot chain line in FIG. 2(b).

The optical axis of the reproduction light is an axis that passes through the center of the beam of reproduction light scanned by the micromirror 206 and is parallel to the propagation direction of the reproduction light. For example, in FIG. 2A, 207b indicated by a dashed line is the optical axis of a beam 207c of reproduction light. The direction of the optical axis of the reproduction light changes depending on the scanning angle by the micromirror 206.

Note that the XY plane 207a is an example of a plane that intersects with the optical axis of the reproduction light.

Further, the position of the XY plane 207a in the direction orthogonal to the XY plane 207a is the position at which the reproduced light by each of the optical deflection element arrays 203r, 203b, and 203g, that is, the reproduced light having a wavefront corresponding to the holographic image, forms an image. This is an example of position 1.

Further, the micromirror 206 is an example of a scanning unit that scans the reproduction light within a plane intersecting the optical axis of the reproduction light at a first position where the reproduction light forms an image. Note that in addition to the micromirror 206, a polygon mirror, an acousto-optic element, or the like may be used in combination as a scanning means, for example.

One color of reproduced light generated by the light deflection element arrays 203r, 203b, and 203g and combined by the combining prism 205 is reflected by the micromirror 206. The reflected light is irradiated onto a part of the region 208 on the XY plane 207a. In area 208, a stereoscopic image according to the CGH data is reproduced and displayed. The stereoscopic image in this case is a part of the stereoscopic image obtained by two-dimensional scanning by the micromirror 206, and is hereinafter referred to as a partial stereoscopic image.

Next, the CGH data input from the control device 202 is switched, and the next color of reproduced light is generated by the light deflection element arrays 203r, 203b, and 203g. Furthermore, the micromirror 206 changes direction, and the direction of reflection is changed. As a result, the reproduction light of the next color is irradiated onto a region adjacent to the region 208 on the XY plane 207a, for example. In an area adjacent to the area 208, a partial stereoscopic image is reproduced and displayed using reproduction light of the next color according to the CGH.

A set of operations including switching the CGH data, generating colored reproduced light by the optical deflection element arrays 203r, 203b, and 203g, and changing the reflection direction of the reproduced light by the micromirror 206 are repeated. . In the XY plane 207a, the area irradiated with the color reproduction light is changed along the arrow 209.

The above operation is repeated, and the entire XY plane 207a is irradiated with color reproduction light along the arrow 209, so that the partial stereoscopic images according to the CGH data are joined together on the XY plane 207a to form the entire stereoscopic image. An image is formed.

Note that the direction of reflection of the reproduction light by the micromirror 206 is continuously changed when the reproduction light is scanned by the micromirror 206. Therefore, in order to join the partial 3D images, it is necessary to switch the CGH data and generate color reproduction light at predetermined timings while scanning the reproduction light using the micromirror 206 in synchronization with the scanning. There is.

In this embodiment, the process of joining partial stereoscopic images on the XY plane 207a is, for example, so-called tiling processing in which adjacent partial stereoscopic images are not overlapped.

Specifically, for example, let Sx be the size of one partial stereoscopic image in the X direction on the XY plane 207a, Z be the distance from the micromirror 206 to the XY plane 207a, and V be the scanning speed of the micromirror 206. Based on Sx, Z, and V, a time t during which adjacent partial stereoscopic images do not overlap is determined in advance, CGH data is switched at every time t, and color is reproduced by the light deflection element arrays 203r, 203b, and 203g. Generate light. Thereby, adjacent partial stereoscopic images can be joined together without mutually overlapping regions. The same holds true when joining partial stereoscopic images in the Y direction.

In order to synchronize the switching of CGH data and the scanning by the micromirror 206, the display device 200 has synchronization detection means. The synchronization detection means is realized, for example, by a PD (Photo Diode) provided in a part of the area where the color reproduction light is scanned by the micromirror 206.

The PD detects the timing at which the color reproduction light passes through its light receiving surface. Based on this timing, time may be measured by clock counting, etc., the CGH data may be switched at each time t, and color reproduction light may be generated by the light deflection element arrays 203r, 203b, and 203g.

For synchronized detection in the X and Y directions, it is necessary to provide at least one PD in each of the X and Y direction scanning regions of the color reproduction light by the micromirror 206.

The operation of forming the entire 3D image is performed within the cycle of the frame rate, and the entire 3D image is displayed as a video at the frame rate. The entire three-dimensional image will hereinafter be simply referred to as a three-dimensional image.

In FIG. 2(b), a stereoscopic image 211 formed in the reproduction space 207 is observed by an observer 212 in the illustrated positional relationship. 207a indicated by a two-dot chain line in FIG. 2(b) is the XY plane. The transparent plate 210 is for protecting the inside of the display device 200 and has no optical function in this embodiment.

Note that although FIG. 2B shows only the optical system for red light for convenience, the same applies to the optical systems for blue and green light.

Next, an example of the hardware configuration of the display device 200 of this embodiment will be described using FIG. 3. As shown in FIG. 3, the display device 200 includes a control device 202, a light source 201, a micromirror 206, and a light deflection element array 203, which are electrically connected to each other. The light source 201 includes light sources 201r, 201b, and 201g, and the light deflection element array 203 includes light deflection element arrays 203r, 203b, and 203g.

Among these, the control device 202 includes a CPU (Central Processing Unit) 300, a RAM (Random Access Memory) 301, a ROM (Read Only Memory) 302, an FPGA (Field-Programmable Gate Array) 303, and an external I/F 304. , a light source driver 305 , a micromirror driver 306 , and an optical deflection element array driver 307 .

The CPU 300 is an arithmetic device that reads programs and data from a storage device such as a ROM 302 onto the RAM 301, executes processing, and realizes overall control and functions of the control device 202.

The RAM 301 is a volatile storage device that temporarily holds programs and data.

The ROM 302 is a nonvolatile storage device that can retain programs and data even when the power is turned off, and stores processing programs and data that the CPU 300 executes to control each function of the display device 200. .

The FPGA 303 is a circuit that outputs control signals suitable for the light source driver 305, micromirror driver 306, and optical deflection element array driver 307 according to the processing of the CPU 300.

External I/F 304 is an interface with, for example, an external device or a network. External devices include, for example, a host device such as a PC (Personal Computer), a USB (Universal Serial Bus) memory, an SD (Secure Digital) card, a CD (Compact Disc), a DVD (Digital Versatile Disc), and an HDD (hard disk drive). ), SSD (Solid State Drive), and other storage devices. Further, the network is, for example, a LAN (Local Area Network) or the Internet. The external I/F 304 may have any configuration as long as it enables connection or communication with an external device, and an external I/F 304 may be provided for each external device.

The light source driver 305 is an electric circuit that outputs a drive signal such as a drive voltage to the light source 201 according to an input control signal. The light source driver 305 includes light source drivers 305r, 305b, and 305g that output drive signals to the light sources 201r, 201b, and 201g, respectively.

The micromirror driver 306 is an electric circuit that outputs a drive signal such as a drive voltage to the micromirror 206 according to an input control signal.

The optical deflection element array driver 307 is an electric circuit that outputs a drive signal such as a drive voltage to the optical deflection element array 203 according to an input control signal. The optical deflection element array driver 307 includes optical deflection element array drivers 307r, 307b, and 307g that output drive signals to the optical deflection element arrays 203r, 203b, and 203g, respectively.

The output of the PD for switching the CGH data and synchronizing the generation of reproduction light by the optical deflection element array 203 and the scanning by the micromirror 206 is input to, for example, the CPU 300 or the FPGA 303.

In the control device 202, the CPU 300 acquires drive information and playback information from an external device or a network via an external I/F 304. Note that any configuration may be sufficient as long as the CPU 300 can acquire the drive information and playback information, and the drive information and playback information may be stored in the ROM 302 or FPGA 303 in the control device 202. It may also be configured such that a storage device such as an SSD is provided in the storage device, and drive information and playback information are stored in the storage device.

Here, the driving information and the reproduction information are information indicating how to display a stereoscopic image in the reproduction space 207. For example, the drive information is the irradiation intensity of the light source, the movable range of the micromirror, etc., and the reproduction information is CGH data, the switching timing of CGH data according to scanning, etc.

The control device 202 can realize the functional configuration described below using instructions from the CPU 300 and the hardware configuration shown in FIG.

Next, the functional configuration of the control device 202 of the display device 200 will be described using FIG. 4. FIG. 4 is a functional block diagram of an example of the control device 202 of the display device 200.

As shown in FIG. 4, the control device 202 has a control section 400 and a drive signal output section 401 as functions. The control unit 400 is realized by, for example, the CPU 300, the FPGA 303, etc., acquires drive information and playback information from an external device, converts these into control signals, and outputs the control signals to the drive signal output unit 401.

The control unit 400 includes a drive control unit 400a and a reproduction control unit 400b, and the drive signal output unit 401 includes a light source drive signal output unit 401a, a micromirror drive signal output unit 401b, and a light deflection element array drive. It has a signal output section 401c.

The drive control unit 400a acquires, for example, the irradiation intensity of the light source and the movable range of the micromirror from an external device as drive information, generates a control signal from these through predetermined processing, and transmits the control signal to the light source drive signal output unit 401a and the micromirror. The signal is output to the mirror drive signal output section 401b.

In addition, the reproduction control unit 400b acquires, for example, CGH data, CGH data switching timing according to scanning, etc. from an external device as reproduction information, generates a control signal from the CGH data by predetermined processing, and generates a control signal from the CGH data by predetermined processing. The signal is output to the optical deflection element array drive signal output section at the timing of . As described above, the predetermined timing is for executing the tiling process, and can be set by the number of clocks to be counted after receiving the output signal from the PD.

Note that the playback control section 400b is an example of playback control means.

The light source drive signal output unit 401a is realized by the light source driver 305, for example. The micromirror drive signal output section 401b is realized by, for example, the micromirror driver 306. The optical deflection element array drive signal output section 401c is realized by, for example, the optical deflection element array driver 307. The light source drive signal output section 401a, the micromirror drive signal output section 401b, and the optical deflection element array drive signal output section 401c output signals to the light source 201, the micromirror 206, and the optical deflection element array 203 based on the input control signals, respectively. Outputs a drive signal.

The drive signal is a signal for controlling the drive of the light source 201, the optical deflection element array 203, or the micromirror 206. For example, in the light source 201, it is a drive voltage that controls the irradiation timing and irradiation intensity of the light source. For example, in the case of the micromirror 206, it is a drive voltage that controls the timing and range of movement of the light reflecting surface of the micromirror 206. Further, for example, in the optical deflection element array 203, it is a drive voltage that controls the timing and movable range of each of the plurality of optical deflection elements of the optical deflection element array 203 according to the CGH data.

Note that the drive control section 400a and the reproduction control section 400b are connected to each other, and it is also possible to cooperate in processing.

Next, the process by which the display device 200 displays a stereoscopic image in the playback space 207 will be described using FIG. 5. FIG. 5 is a flowchart of an example of processing by the control device 202 in the display device 200.

First, in step S51, the drive control unit 400a acquires drive information from an external device or the like.

Subsequently, in step S53, the drive control section 400a generates a control signal from the acquired drive information, and outputs the control signal to the light source drive signal output section 401a and the micromirror drive signal output section 401b.

Subsequently, in step S55, the light source drive signal output unit 401a outputs a drive signal to the light source 201 based on the input control signal, and the micromirror drive signal output unit 401b outputs a drive signal based on the input control signal. , outputs a drive signal to the micromirror 206. The light source 201 irradiates light based on the input drive signal, and the micromirror 206 moves the light reflecting surface based on the input drive signal to reflect the reproduced light generated by the light deflection element array 203. scan.

Subsequently, in step S57, the reproduction control unit 400b acquires reproduction information from an external device or the like. Note that the playback information may be stored in advance in a RAM or the like in the control device 202, and the playback control unit 400b may acquire the playback information from the RAM or the like.

Subsequently, in step S59, the reproduction control section 400b generates a control signal from the acquired reproduction information, and outputs the control signal to the optical deflection element array drive signal output section 401c.

Subsequently, in step S61, the optical deflection element array drive signal output unit 401c outputs a drive signal to the optical deflection element array 203 based on the input control signal. The optical deflection element array 203 moves each optical deflection element at a predetermined timing based on the input drive signal and the output signal of the PD for synchronizing with scanning. As a result, a partial stereoscopic image is displayed in the reproduction space 207.

Subsequently, in step S63, the control device 202 determines whether the display of all partial stereoscopic images has been completed, and if the display has not been completed, the process returns to step S57 and continues the process.

If the display of all partial 3D images has been completed, the control device 202 determines whether the display of all 3D images has been completed in step S65. If not, the control device 202 returns to step S57 and executes the process. continue.

In step S65, if the display of all stereoscopic images is finished, the process ends.

As described above, partial stereoscopic images according to the CGH data are scanned, and a stereoscopic image in which they are connected on the XY plane 207a is displayed.

Note that in the display device 200, one control device 202 has a device and function for controlling the light source 201, the light deflection element array 203, and the micromirror 206, but the present invention is not limited thereto. The control device for the light source, the control device for the optical deflection element array, and the control device for the micromirror may be provided separately.

Further, in the display device 200, one control device 202 is provided with the functions of the control section 400 and the drive signal output section 401, but the present invention is not limited to this. These functions may exist separately; for example, a drive signal output device having a drive signal output section 401 may be provided separately from the control device 202 having the control section 400.

Next, a pattern of interference fringes, that is, a hologram, formed by the optical deflection element array 203r will be explained using FIG. 6.

The optical deflection element array 203r forms a hologram according to CGH data input from the control device 202. In the following, for convenience of explanation, reproduction of a stereoscopic image using red light by the light deflection element array 203r will be described, but reproduction of a stereoscopic image by blue and green light using the light deflection element array 203b and the light deflection element array 203g will be described. The same applies to the reproduction and display of stereoscopic images.

FIG. 6 shows a hologram formed by the optical deflection element array 203r. FIG. 6A shows a state in which a plurality of optical deflection elements are two-dimensionally arranged in the optical deflection element array 203r. 301r represents one optical deflection element, and this optical deflection element is two-dimensionally arranged to constitute an optical deflection element array 203r. The light deflection elements each have a light reflecting surface and are movable independently.

FIG. 6(b) shows how each optical deflection element moves independently according to the CGH data. In FIG. 6B, the light deflection element 301r-a shown in a non-black state is in an ON state, and the light deflection element 301r-b shown in a black state is in an OFF state.

In this embodiment, the optical deflection element can be moved in two ways: ON or OFF. When ON, the light reflecting surface of the light deflection element is inclined at a predetermined angle with respect to the plane on which the light deflection elements are arranged, for example. Further, when the light deflection element is OFF, the light reflecting surface of the light deflection element is inclined at a different angle from when the light deflection element is ON, with respect to the plane on which the light deflection elements are arranged. When it is OFF, the light reflected from the light reflecting surface is blocked by the light shielding plate 204r and does not contribute to the reproduction of the stereoscopic image.

FIG. 6C shows an example of an interference fringe pattern expressed by combining the ON state and OFF state of the optical deflection element. In FIGS. 6(a) and 6(b), each optical deflection element is enlarged and schematically shown to make it easier to recognize each optical deflection element, but in FIG. 6(c), each light The deflection element is shown without being enlarged.

In FIG. 6C, when light enters the optical deflection element array 203r, reflected light is modulated according to the interference fringe pattern. That is, the reflected light is modulated so that it contributes to the reproduction of a stereoscopic image when the optical deflection element is ON, and does not contribute to the reproduction of the stereoscopic image when the optical deflection element is OFF. In this way, the optical deflection element array 203r acts as a hologram that modulates incident light. In addition, although the case in which the optical deflection element can be moved in two ways, ON and OFF, has been described above, it may be possible to provide more than two ways to perform more detailed modulation.

Here, in the display device 200 of this embodiment, the first position, that is, the position where the reproduced light forms an image or approximately forms an image, and the second position, that is, the position where the light deflection element array is arranged, the reproduced light The size of the reproduced light in a plane intersecting the optical axis of is equal.

The size of the reproduction light refers to the size of the reproduction light generated by the optical deflection element array in a plane intersecting the optical axis, that is, the XY plane 207a in FIG. 2.

The size of the reproduced light in the horizontal direction, that is, the X direction, is synonymous with the length (width) of the reproduced light by the optical deflection element array in the horizontal direction, that is, the X direction. The size of the reproduction light in the vertical direction, that is, the Y direction, is synonymous with the length (height) of the reproduction light in the vertical direction, that is, the Y direction, of the reproduction light by the optical deflection element array.

Furthermore, the fact that the sizes of the reproduced light beams at the first position and the second position are equal can be expressed separately as follows. That is, in the X and Y directions, if the size of one optical deflection element is px and py, and the number of optical deflection elements in the optical deflection element array is Nx and Ny, the size of the reproduced light at the first position is The direction is Nx×px, and the Y direction is Ny×py.

The same size of the reproduction light at the first position and the second position means that the size of the reproduction light is not expanded in the first position, and the viewing angle is not decreased in the first position. It means that. Here, the viewing angle refers to the angular range in which an object can be observed, or the angle at which the eyes can observe the entire object. The larger the viewing angle, the more three-dimensional a three-dimensional image can be obtained.

The viewing angle φ of the reproduced stereoscopic image and the minimum width δ of the interference fringes have a relationship expressed by the following equation (1). However, λ is the wavelength of the light source.

According to equation (1), for example, when δ is 1.0 μm, φ is about 30 degrees.

If the reproduced light by the optical deflection element array is expanded at the first position, the minimum width δ of the interference fringes will also be expanded, so according to equation (1), the viewing angle will decrease as δ increases. .

In this embodiment, since the reproduced light by the optical deflection element array is not expanded, the minimum width δ of the interference fringes at the position of the optical deflection element array is maintained even at the first position, and the viewing angle is maintained. For example, if the size of one optical deflection element in the X and Y directions is each 1.0 μm, and the number of optical deflection elements in the optical deflection element array is 1000, then the reproduced light at the first position and the second position Both sizes are 1 mm. Since the minimum width δ of the interference fringes is 1 μm, which is equal to the size of one deflection element, it is possible to observe a stereoscopic image at a viewing angle of about 30 degrees when δ is 1.0 μm.

In order to equalize the size of the reproduced light at the first position and the second position, for example, as shown in FIG. good. The variable magnification lens 213 acts to equalize the size of the reproduced light while maintaining the relationship in which the reproduced light by the optical deflection element array 203r forms an image at the first position when the variable magnification lens 213 is not provided.

Since the hologram formed by the optical deflection element array 203r is a type of lens, the hologram formed by the optical deflection element array 203r and the variable magnification lens 213 constitute a composite optical system. The focal length of the synthetic optical system is set so that the optical magnification is 1x while maintaining the imaging relationship in the case of only a hologram. This makes it possible to equalize the size of the reproduction light at the first position and the second position.

The variable power lens 213 may be configured by combining a plurality of optical systems such as lenses. Furthermore, in order to suppress the influence on the display performance of stereoscopic images, it is preferable to use a variable magnification lens 213 with reduced aberrations such as chromatic aberration.

By the way, in order to maintain the viewing angle, the horizontal and vertical lengths Rx and Ry of the reproduction light in the plane intersecting the optical axis of the reproduction light at the first position are as follows (2) , (3) relationship may be satisfied.

However, Nx and Ny are the numbers of optical deflection elements in the horizontal and vertical directions in the optical deflection element array, and λ is the wavelength of the incident coherent light.

A structure with a length smaller than λ will not produce a diffraction effect, and since the light deflection element array reflects light, it is considered that the size of the light deflection element needs to be λ/2 or more. Therefore, Rx is set to a value equal to or greater than Nx×λ/2, which is λ/2 multiplied by the number of optical deflection elements.

Also, considering that stereoscopic vision is performed with both eyes, the permissible viewing angle for sufficient stereoscopic vision is considered to be up to 1/2 of the viewing angle when wavelength λ is the minimum width of the interference fringes. It will be done. Therefore, Rx is set to a value less than or equal to 2×Nx×λ, which is the value obtained by multiplying the width 2λ of interference fringes to obtain a viewing zone angle that is 1/2 of the viewing zone angle by λ by the number of optical deflection elements.

Note that, for example, if the distance from the micromirror 206 to the XY plane 207a is short, the size of the reproduction light may vary depending on the region of the XY plane 207a that is irradiated with the reproduction light by scanning. For example, there is a case where the size of the reproduction light differs near the center and near the ends of the XY plane 207a. Since the size of the reproduction light differs depending on the region of the XY plane 207a, the problem is which region should have the size of the reproduction light as the size of the reproduction light at the first position.

In this case, since the size of the reproduction light is determined by the scanning angle of the micromirror 206, the size of the reproduction light may be standardized by the scanning angle, for example. If normalized by the scanning angle, differences in the size of the reproduced light depending on the area can be eliminated, so the standardized size of the reproduced light may be used as the size of the reproduced light at the first position. Alternatively, for example, the size of the reproduction light at the first position may be set to the size of the reproduction light near the center on the XY plane 207a as a representative value.

As described above, by making the size of the reproduction light at the first position equal to or approximately equal to the size of the reproduction light at the second position, that is, the position where the optical deflection element array is arranged, a wide A viewing angle can be secured.

Further, as described above, in the display device 200 of this embodiment, a large stereoscopic image is displayed by connecting partial stereoscopic images on the XY plane 207a while scanning the reproduced light from the optical deflection element array with the micromirror 206. be able to.

As described above, according to the display device 200 of this embodiment, a large-sized stereoscopic image can be displayed while ensuring a wide viewing angle.

Note that although the display of a stereoscopic image using CGH data has been described above, the display device 200 of this embodiment displays a three-dimensional stereoscopic image using hologram data captured and recorded based on the principle of holography. It can also be applied to

Next, an example of the structure of the optical deflection element of this embodiment will be described in detail using FIG. 8. In FIG. 8, (a) is a plan view of the optical deflection element, and (b) is a cross-sectional view taken along the line AA in (a).

In FIG. 8, the optical deflection element 800 includes a substrate 801, regulating members 802a, 802b, 802c, and 802d, fulcrum members 803a and 803b, a plate member 804, electrodes 805a and 805b, and a contact portion 807. have.

The substrate 801 is a silicon semiconductor substrate. By using materials such as silicon and glass that are generally used in semiconductor processes and liquid crystal processes, it is possible to miniaturize the structure. In addition, by forming it using a silicon substrate having a (100) plane orientation, it can be formed on the same substrate as the drive system circuit, and can be manufactured easily and at low cost.

The regulating members 802a, 802b, 802c, and 802d limit the movable range of the plate member 804 having a light reflecting surface to a predetermined space. For example, one regulating member 802a includes four cylindrical members and a stopper 806 provided at the top of the cylindrical members. The regulating members 802a, 802b, 802c, and 802d are arranged at predetermined intervals at positions corresponding to the four corners of the rectangular plate member 804. The stopper 806 limits the upward movable range of the plate member 804 by pressing the plate member 804 from above. The regulating members 802a, 802b, 802c, and 802d are formed of, for example, a silicon oxide film or a chromium oxide film. Note that the number and arrangement of the regulating members are not limited to those described above, and a large number may be arranged in the entire area corresponding to the outer periphery of the plate-like member 804.

The plate member 804 is a member formed of a thin film of aluminum or the like having high reflectance. The surface of the plate member 804 functions as a light reflecting surface. The plate member 804 is supported in contact with the tops of the fulcrum members 803a and 803b, and can be tilted and moved using the tops as fulcrums. Further, the plate member 804 has a conductive portion at least in part. The plate member 804 may be made of a conductor.

When a voltage is applied to the electrodes 805a and 805b, electrostatic attraction is generated between the conductive portion of the plate member 804 and the electrodes 805a and 805b. As described above, the movable range of the plate member 804 is limited in the upward direction by the regulating members 802a, 802b, 802c, and 802d, and in the downward direction by the substrate 801. The plate member 804 is made of a thin film and is lightweight. Thereby, the impact when colliding with the substrate 801 and the regulating members 802a to 802d is alleviated.

The fulcrum members 803a and 803b are, for example, conical members provided on the upper surface of the substrate 801, respectively. The top of the cone acts as a fulcrum on which the plate member 804 tilts. Note that the shape of the fulcrum members 803a and 803b is not limited to a cone, and can be optimized depending on the performance required of the optical deflection element 800.

The fulcrum members 803a and 803b are formed of, for example, a silicon oxide film or a silicon nitride film. However, if the potential of the plate member 804 is to be taken through the fulcrum members 803a and 803b, it is necessary to form the plate member 804 with a conductive material such as various metal films.

Electrodes 805a and 805b are arranged to face plate member 804. When a voltage is applied to the electrodes 805a and 805b, electrostatic attraction is generated between the electrodes 805a and 805b and the conductive portion of the plate member 804. The plate-shaped member 804 can be tilted by drawing the end portions together by this electrostatic attraction. The inclination angle of the plate member 804 is switched depending on the voltage applied to the electrodes 805a and 805b. The deflection direction of the light incident on the plate member 804 can be determined by using the size of the plate member 804, the angle of incidence of the light incident on the plate member 804, and the inclination angle of the plate member 804 as parameters. .

The contact portion 807 is provided on the substrate 801 and is a portion that brings the end of the plate-like member 804 into contact when the plate-like member 804 is tilted.

As an example of the action of the light deflection element 800, when the plate-like member 804 is tilted about the tops of the fulcrum members 803a and 803b, the light incident on the plate-like member 804 is directed to the outline shown in FIG. 8(a). It is deflected in the direction along arrow 808. For example, the light beam incident on the plate member 804 is reflected in direction 1 when the optical deflection element is ON, and reflected in direction 2 when the optical deflection element is OFF.

The optical deflection elements described above can be manufactured by, for example, a silicon semiconductor manufacturing process, and by arranging the optical deflection elements two-dimensionally, an optical deflection element array can be manufactured.

Next, the features of the optical deflection element array of this embodiment will be explained in detail.

In this embodiment, the optical deflection element array is driven by a so-called active matrix method. The active matrix method here is a driving method used for driving a liquid crystal panel and the like. Specifically, in addition to a simple matrix structure in which conductive wires are stretched in two directions (X and Y directions) and voltage is applied from both directions to drive the pixels at the intersections, an active element is placed in each pixel. be. The state of the active element is switched ON or OFF depending on the voltage of the conducting wire in the X direction, and when the active element is ON and voltage is also applied to the conducting wire in the Y direction, the target pixel at the intersection is driven. Thereby, only the target pixel can be reliably driven. Compared to the simple matrix type, it has the characteristics of less afterimage, wider viewing angle, higher contrast, and faster reaction speed.

In this embodiment, one light deflection element in the light deflection element array is a "pixel." By adopting the active matrix method, the number of transistors directly below one optical deflection element can be reduced. This allows fine light deflection elements with a side length of about 1 μm to be arranged two-dimensionally, making it possible to manufacture a light deflection element array including fine pixels.

In this embodiment, the size of the optical deflection element, that is, the length of each side in the X and Y directions is, for example, 1.2 μm. The size of the plate member 804 in the optical deflection element is, for example, 1.0 μm in both the X and Y directions. Further, the plate member 804 can be tilted at an angle of 10 degrees or more.

The number of optical deflection elements in the optical deflection element array of this embodiment is, for example, 1000 in both the X and Y directions. Therefore, the optical deflection element array has a total of 1 million optical deflection elements, and the size of the reproduced light formed by the optical deflection element array at the second position is 1.2 mm in both the X and Y directions.

In the XY plane 207a, the range scanned by the micromirror 206 is, for example, 30 inches diagonally, and the size of the stereoscopic image formed by joining the partial stereoscopic images is, for example, 540 mm in both the X and Y directions. In this way, it is possible to display stereoscopic images on a large screen.

Furthermore, since the optical deflection element array of this embodiment can be manufactured using a silicon semiconductor manufacturing process, it is possible to drive all the pixels of the optical deflection element array, that is, all the optical deflection elements in parallel using an active matrix method. . By driving each optical deflection element in parallel using an active matrix method and by making the plate-like member 804, which is a movable part, smaller and lighter, the display time of one partial stereoscopic image can be increased to, for example, 57 ns. can. This makes it possible to display a stereoscopic image at a practical frame rate of 60 fps (frames per second).

Since the plate member 804 is made of a thin plate without a fixed end such as a hinge, no restoring force is generated when the plate member 804 is tilted. This suppresses resistance during tilting, so it can be moved with a lower voltage. Further, miniaturization is also easy. Furthermore, if a vacuum sealed package is used in combination, further speeding up can be achieved.

In this embodiment, since the size of the optical deflection element is approximately the same as the wavelength of the incident light, the optical deflection element array constituted by a periodic structure of optical deflection elements acts like a diffraction grating. In other words, the light deflected by the light deflection element array can be made to behave like diffracted light by the light deflection element array.

In the optical deflection element array of this embodiment, the effect of a blazed diffraction grating can be obtained by tilting each optical deflection element so as to have a periodic structure. For example, if the optical deflection element array is designed to act as a blazed diffraction grating that provides maximum diffraction efficiency for +1st-order diffraction light, high diffraction efficiency can be obtained and a bright three-dimensional image can be displayed.

As described above, according to the present embodiment, a bright stereoscopic image can be displayed at a practical frame rate by using the optical deflection element array composed of the above-mentioned optical deflection elements. Furthermore, as mentioned above, by making the size of the reproduction light equal at the first position and the second position, a wide viewing angle can be secured, and by scanning and connecting the reproduction light at the first position, Large size 3D images can be displayed.
[Second embodiment]
Next, a display device according to a second embodiment will be described. Descriptions of parts that overlap with those of the first embodiment will be omitted, and differences will be described.

A method for driving the optical deflection element in the display device of this embodiment will be described in detail with reference to FIG.

FIG. 9 is a diagram schematically explaining the relationship between the drive voltage applied to the optical deflection element 800 and the operation of tilting the plate member 804. Note that the plate member 804 is made of a conductor.

The figures shown on the left side in FIGS. 9(a), (b), and (c) all represent cross-sectional views corresponding to the AA cross section in FIG. 8(a). Further, the table shown on the right side both shows the voltages applied to the electrodes 805a and 805b in the optical deflection element 800 and the fulcrum member 803 that acts as an electrode. The center column in the table shows the voltage applied to one optical deflection element, and the rightmost column shows the voltage applied to the optical deflection element driven next to one optical deflection element. Hereinafter, one optical deflection element will be referred to as an optical deflection element 800, and an optical deflection element driven next to the one optical deflection element will be referred to as an optical deflection element 800n.

FIG. 9A shows a state immediately after the driving voltage is applied to the optical deflection element 800 and immediately before the plate member 804 starts tilting. By applying the driving voltage, electrostatic attraction is generated between the plate member 804 and the electrode 805a, and the left end of the plate member 804 is pulled in the direction of the white arrow 901 by the electrostatic attraction. There is.

In this state, in the optical deflection element 800, X (V) is applied to the electrode 805a, and 0 (V) is applied to the electrode 805b and the fulcrum member 803. Further, in the optical deflection element 800n, the electrodes 805a and 805b are in an electrically floating state, that is, in a Float state, and the voltage is approximately 0 (V). 0 (V) is applied to the fulcrum member 803.

When the voltage is in this state, even for a moment, the electrostatic attraction described above is generated in the plate member 804 of the optical deflection element 800 in the direction of the white arrow 901. As a result, the plate member 804 starts to tilt. Since the plate member 804 in the optical deflection element 800 does not have a hinge, a restoring force that would hinder the tilting operation is not generated. Therefore, even if a voltage is applied to the electrode 805a and the application of voltage to the electrode 805a is stopped immediately after the plate-like member 804 starts tilting, the action of electrostatic attraction continues, and the plate-like member 804 does not tilt. Continue. In other words, the plate member 804 can be tilted even if the application of voltage to the electrode 805a is stopped immediately after the plate member 804 starts tilting.

Next, FIG. 9B shows a state in which a drive voltage is applied to the optical deflection element 800 and the plate-like member 804 is in the middle of performing a tilting operation. In this state, although the application of the drive voltage is stopped, the electrostatic attraction remains, as indicated by a dotted white arrow 902 in the figure. In this case, the electrode 805a of the optical deflection element 800 is in an electrically floating state, and is in a state of transition from X (V) to 0 (V). Similarly, the electrode 805b is in an electrically floating state, and is in a state of transitioning from X (V) to 0 (V). 0 (V) is applied to the fulcrum member 803.

At this time, in the optical deflection element 800n, X (V) is applied to the electrode 805an, and 0 (V) is applied to the electrode 805bn and the fulcrum member 803n. In the optical deflection element 800n, the plate member 804n has begun to tilt.

Next, FIG. 9(c) shows the state after the plate member 804 has finished the tilting operation. The plate member 804 comes into contact with the contact portion 807 on the substrate 801 and stops, completing the tilting operation. In the optical deflection element 800 of this embodiment, the plate member 804 is not fixed and does not have restoring force due to a hinge. Therefore, even if no voltage is applied and no electrostatic attraction is applied, the tilted state, that is, the state shown in FIG. 9(c) can be maintained. In this case, the electrode 805a and the electrode 805b are in an electrically floating state and have approximately 0 (V). 0 (V) is applied to the fulcrum member 803.

In the state of FIG. 9(c), in the optical deflection element 800n, no voltage is applied to the electrode 805an, and it is in an electrically floating state, shifting from X (V) to 0 (V). It is in a state of being Similarly, the electrode 805bn is in an electrically floating state, and is in a state of transitioning from X (V) to 0 (V). 0 (V) is applied to the fulcrum member 803.

As explained above, the voltage needs to be applied to the optical deflection element 800 only for a moment when the plate member 804 begins to tilt. Thereafter, even when the voltage application is stopped and the plate-like member 804 is in an electrically floating state, the plate-like member 804 continues its tilting operation. Even after the tilting operation is completed, the tilted state is maintained as it is. Therefore, after momentarily applying a voltage to one optical deflection element, it is possible to immediately stop applying the voltage and move on to applying voltage to the next optical deflection element. This makes it possible, for example, to eliminate the waiting time in applying voltage to the optical deflection elements, and to drive the optical deflection element array at even higher speeds.

By further increasing the driving speed of the optical deflection element array, it becomes possible to further increase the frame rate of stereoscopic image display by the display device.

Note that to drive the optical deflection element array described above, the control signal generated by the reproduction control unit 400b is output to the optical deflection element array drive signal output unit 401c, and the optical deflection element array drive signal output unit 401c outputs the drive signal to optical deflection. This is achieved by outputting to the element array 203. The above-mentioned functions of the reproduction control unit 400b and the optical deflection element array drive signal output unit 401c are such that after the reproduction control means applies a driving voltage for tilting the plate member to one optical deflection element, one optical deflection is performed. This is an example of a function in which the drive voltage is applied to other optical deflection elements before the tilting operation of the plate-like member of the element is completed.
[Third embodiment]
Next, a display device 220 according to a third embodiment will be described using FIG. 10. Descriptions of parts that overlap with the first and second embodiments will be omitted, and differences will be described.

Depending on the image to be displayed as a partial stereoscopic image, the reproduced light by the light deflection element arrays 203r, 203b, and 203g may spread widely and propagate. Furthermore, when the reproduction lights from each of the optical deflection element arrays 203r, 203b, and 203g are combined by the combining prism 205 and guided to the micromirror 206, the combined light may spread widely and propagate. In such a case, if the size of the reproduced light or the combined light becomes larger than the light reflecting surface of the micromirror 206 at the position where the micromirror 206 is arranged, that is, the third position, part of the reproduced light or the combined light is vignetted by the micromirror 206 and no longer contributes to displaying a partial stereoscopic image.

Although it is not necessary that all of the light reproduced by the light deflection element arrays 203r, 203b, and 203g be incident on the light reflecting surface of the micromirror 206, if the amount of light that does not contribute to displaying the partial stereoscopic image increases, the brightness of the partial stereoscopic image will decrease. Problems such as a decrease in image quality may occur.

According to the display device 220 of the present embodiment, for example, it is possible to prevent an increase in the amount of light that does not contribute to the display of a partial stereoscopic image, and to prevent problems such as a decrease in the brightness of the partial stereoscopic image.

In FIG. 10, a display device 220 of this embodiment has a lens 221. The lens 221 is provided between the combining prism 205 and the micromirror 206 in the optical path of the reproduced light by the optical deflection element arrays 203r, 203b, and 203g. Lens 221 is an example of a "first optical system."

The lens 221 has positive power and functions to suppress the spread of light toward the micromirror 206. For example, when the focal length of the lens 221 is f (mm), the optical axis of the reproduced light is located at a position f (mm) away from the optical deflection element arrays 203r, 203b, and 203g in the direction toward the micromirror 206. The lens 221 is provided so that the optical axis of the lens 221 substantially coincides with the optical axis of the lens 221.

Thereby, the spherical waves whose light emitting points are at the positions of the optical deflection element arrays 203r, 203b, and 203g are collimated by the lens 221, and their spread is suppressed. Further, it is possible to reduce the light that is vignetted by the micromirror 206 and no longer contributes to displaying the partial stereoscopic image, and it is possible to reduce problems such as a decrease in the brightness of the partial stereoscopic image.

Note that in the above case, vignetting caused by the micromirror 206 can be further suppressed by shortening the focal length of the lens 221 or increasing the diameter of the lens 221. In order to suppress the influence on the display performance of stereoscopic images, it is preferable to use a lens 221 with reduced aberrations such as chromatic aberration.

In the above example, the spherical waves whose light emitting points are at the positions of the optical deflection element arrays 203r, 203b, and 203g are collimated by the lens 221 having positive power, but the present invention is not limited to this. Various modifications are possible, such as converging with the lens 221 or combining lenses with negative power.
[Fourth embodiment]
Next, a display device 230, a display device 240, and a display device 250 of the fourth embodiment will be described using FIG. 11. Descriptions of parts that overlap with the first to third embodiments will be omitted, and differences will be described.

FIG. 11A shows an example of the configuration of the display device 230 of this embodiment. In FIG. 11A, the display device 230 includes a lens 231 between the micromirror 206 and the reproduction space in the optical path of reproduction by the optical deflection element arrays 203r, 203b, and 203g. The lens 231 has positive power, is scanned by the micromirror 206, and suppresses the spread of light toward the reproduction space. Further, the surface of the lens 231 that contacts the outside of the display device 230 is flat.

If the lens 231 is not provided, the light scanned by the micromirror 206 spreads as it heads toward the reproduction space. As a result, an observer observing the reproduction space from a direction facing the micromirror 206 across the reproduction space may see a stereoscopic image with reduced brightness or a stereoscopic image with a reduced viewing angle. There are cases where

Since the lens 231 can suppress the spread of light toward the reproduction space, the viewer can observe a larger three-dimensional image that is brighter and maintains the viewing angle. Note that a light ray 232 in FIG. 11A shows how the propagation direction of light toward the reproduction space is changed by the lens 231.

FIG. 11(b) is an example of the configuration of the display device 240 of this embodiment. The difference from the display device 230 is that a lens 241 is provided instead of the lens 231. The lens 241 has a surface in contact with the outside of the display device 240 that is convex toward the outside of the display device 240 . The function of the lens 241 is similar to that of the lens 231, and the display device 240 is one of the modified examples of the display device 230.

In order to suppress the influence on the display performance of stereoscopic images, it is preferable to use lenses 231 and 241 with reduced aberrations such as chromatic aberration.

Note that in the display device 230 or the display device 240, a lens 231 or a lens 241 may be provided in place of the transparent plate 210 in the position of the transparent plate 210 in FIG. Thereby, the lens 231 or the lens 241 can also be used as a member for protecting the inside of the display device 230 or the display device 240.

FIG. 11(c) is an example of the configuration of the display device 250 of this embodiment. The difference from the display device 230 or the display device 240 is that a curved mirror 251 is provided instead of the lens 231 or the lens 241. A curved mirror is a mirror whose light reflecting surface has a curved shape such as a spherical surface or a paraboloid.

Since the scanning light from the micromirror 206 is reflected by the curved mirror 251, the reproduction space is on the micromirror 206 side when viewed from the curved mirror 251. The stereoscopic image in the reproduction space is observed by an observer 253.

The ability of the curved mirror 251 to suppress the spread of light toward the reproduction space is similar to the effect of the lenses 231 and 241, and the display device 250 is a modification of the display devices 230 and 240. However, since reflection is used, there are different effects on the display devices 230 and 240, such as being able to suppress chromatic aberration.

The lens 231, the lens 241, or the curved mirror 251 may act to form a stereoscopic image from the display device on the observer's eyeball or retina.

The lens 231, the lens 241, or the curved mirror 251 is also effective in improving the fθ characteristics in scanning the reproduction light, that is, in improving the uniformity of the scanning speed.

Lens 231, lens 241, and curved mirror 251 in FIG. 11 are each an example of a "second optical system."

Although examples of embodiments of the present invention have been described above, the present invention is not limited to such specific embodiments, and various modifications may be made within the scope of the gist of the present invention as described in the claims. It is possible to transform and change.

108, 211 Stereoscopic image 200, 230, 240, 250 Display device 201, 201r, 201b, 201g Light source 202 Control device 203, 203r, 203b, 203g Light deflection element array 204 Light shielding plate 205 Synthesizing prism 206 Micromirror 207 Reproduction space 207a X Y Plane (an example of a plane that intersects the optical axis of the reproduction light)
207b Optical axis of reproduction light 207c Luminous flux of reproduction light 213 Variable magnification lens 221 Lens (an example of the first optical system)
231, 241 Lens (an example of the second optical system)
251 Curved mirror (an example of second optical system)
305 Light source driver 306 Micromirror driver 307 Optical deflection element array driver 400 Control unit 400a Drive control unit 400b Reproduction control unit 401a Light source drive signal output unit 401b Micromirror drive signal output unit 401c Optical deflection element array drive signal output unit 800 Optical deflection element 801 Substrate 802a, 802b, 802c, 802d Regulation member 803, 803a, 803b Fulcrum member 804 Plate member 805a, 805b Electrode

Patent No. 5015969

APPLIED OPTICS Vol.48, No.17 10 June 2009

Claims (2)

A display device that displays a holographic image,
A light source that emits coherent light,
A plurality of optical deflection elements each having a side length of 1.0 to 1.2 μm are two-dimensionally arranged, and the light from the light source is deflected based on an interference fringe pattern corresponding to the holographic image. an optical deflection element array that deflects each element and generates reproduction light;
scanning means for scanning the reproduction light in a plane intersecting the optical axis of the reproduction light at a first position where the reproduction light forms an image;
a reproduction control means for controlling generation of the reproduction light by the optical deflection element array according to the scanning, and connecting the scanned reproduction lights to form the holographic image;
a first optical system that adjusts the size of the reproduced light at the third position on the optical path of the reproduced light between the position where the optical deflection element array is disposed and the third position where the scanning means is disposed; system, and
The size at the center of the plane of the reproduction light determined by the scanning angle of the scanning means at the first position is determined by the size of the reproduction light at the center of the plane, which is determined by the scanning angle of the scanning means at the first position. equal to the size of
the minimum width of the interference fringes at the first position is equal to the minimum width of the interference fringes at the second position to maintain the viewing angle;
The holographic image at the first position is increased in size by connecting reproduced light at the second position where the optical deflection element array is arranged,
The optical deflection element includes a substrate, a fulcrum member, a plurality of regulating members, a plate member, and a plurality of electrodes,
The fulcrum member has a top portion and is provided on the upper surface of the substrate,
Each of the regulating members has a stopper at an upper part and is provided at an end of the plate-like member,
The plate-like member has a light reflecting surface and a conductive part, one surface of the plate-like member contacts the top part to be supported by the fulcrum member, and the plate-like member has no fixed end. movable within a range defined by the substrate and the regulating member;
Each of the electrodes is provided on the substrate to face the conductive part of the plate-like member,
Due to the electrostatic attraction generated between the conductive part and the electrode, the plate-like member tilts around the top part as a fulcrum depending on the interference fringe pattern and the position of the light source. Deflects reflected light ,
Since the sizes at the first position and the second position are equal, the holographic image formed by the reproduction control means can be formed while maintaining the viewing angle;
The reproduction control means applies a driving voltage for tilting the plate member to one optical deflection element, and before the operation of tilting the plate member included in the one optical deflection element is completed. applying the driving voltage to another optical deflection element;
A stereoscopic image display device characterized by: The light source is two or more light sources with different wavelengths,
having the optical deflection element array for each of the wavelengths,
comprising means for synthesizing the reproduction light generated by the optical deflection element array for each wavelength,
The synthesized reproduction light has a center size equal to the size of the center at the first position and the size of the optical deflection element array at the second position.
The stereoscopic image display device according to claim 1 , characterized in that: