Light reproduction device, three-dimensional space display system, light reproduction method, and program

Abstract

To provide a beam reproduction device with which it is possible to display a social metric space as a three-dimensional space by which a natural sense of distance is obtained, and which is mostly free of blurs.SOLUTION: Provided is a beam reproduction device for reproducing a beam virtually emitted from a stereoscopic image when reproducing the stereoscopic image in a reproduction space, the device including a stereoscopic image display unit for displaying the stereoscopic image, as at least one of a virtual image and a real image, by the beam emitted by each element cell included in an element cell aggregate composed of a plurality of element cells two-dimensionally arranged in correspondence to a reproduction screen. The stereoscopic image display unit displays the stereoscopic image in a region the depth distance of which in the reproduction space is equivalent to social metric, with the size of the element cell which is each cell in the element cell aggregate and the pitch of the element cells when the element cells are two-dimensionally arranged assuming the values determined in accordance with the frequency of the stereoscopic image displayed in the reproduction space being observed by observers.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a light reproduction device, a three-dimensional space display system, a light reproduction method, and a program. [Background technology]

[0002] Whether it's family, close friends, or in the political or business world, it's important to know each other's feelings when communicating. In terms of non-verbal communication, it's necessary to communicate the appropriate intervals for conversation and personal space without feeling awkward. In addition, it's important to obtain non-verbal information, such as the other person's facial expressions and gestures, within that distance.

[0003] Various technologies have been provided to facilitate smooth communication. For example, in the field of communication technology, 5G low-latency technology can reduce communication delays, allowing online conversations to be spaced in the same way as in real conversations. In addition, three-dimensional measurement technologies such as TOF (Time of Flight) can be used to accurately measure the distance between people. However, no technology is known that can display a deep space that allows appropriate interpersonal distance (personal space) without creating a sense of incongruity.

[0004] Here, a deep space in this application refers to a space that is larger than the space where an interpersonal distance of about 1.2 m to about 3.6 m can be maintained, which is mainly applied when people communicate publicly with others. In the following explanation, this deep space where an interpersonal distance of about 1.2 m to about 3.6 m can be maintained is referred to as a "social distance space."

[0005] There are various technologies for displaying three-dimensional images with depth. For example, there are wearable display devices such as head-up displays, polarized glasses, and liquid crystal shutter glasses, as well as technologies such as parallax barriers and lenticular that display three-dimensional images by having two eyes observe different parallax without wearing glasses. These three-dimensional image display technologies create a sense of three-dimensionality using only parallax. For this reason, they require convergence to focus the gaze on one point and focus adjustment, which can cause eye strain and nausea. For this reason, they are not suitable as a tool for displaying socially distant spaces with depth.

[0006] In response to this, Non-Patent Document 1 discloses a technology for displaying a three-dimensional image without the need for convergence and focus adjustment. Non-Patent Document 1 discloses a super multi-eye display and a display (see FIG. 19) that uses a microlens array to record a light field (directional information and intensity distribution on the imaging surface of light rays incident on the imaging surface of a digital camera) and reproduces (displays) the recorded light field. In addition, a static display type light field display (see FIG. 20) in which liquid crystal panels or the like are stacked is proposed.

[0007] Furthermore, the stereoscopic image display device described in Patent Document 1 discloses a technology for increasing the number of viewpoints sufficiently (super multi-eye). This makes it possible to satisfy the four factors of human stereoscopic perception: binocular parallax, focus adjustment, convergence, and motion parallax. Displaying three-dimensional images using such super multi-eye displays and light field displays achieves natural focus adjustment and convergence by reproducing light rays smaller than the size of the pupils. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Patent Application No. 2007-17634 [Non-patent literature]

[0009] [Non-Patent Document 1] [online], "Research Trends of Light Field Displays" March 2018, Takafumi Koike, [Retrieved August 3, 2020], Internet <URL: https: / / home.jeita.or.jp / device / lirec / symposium / fpd / pdf / 2018_2a.pdf> Summary of the Invention [Problem to be solved by the invention]

[0010] However, the super multi-eye display described in Patent Document 1 reproduces light rays in a size smaller than the size of the pupil, thereby realizing natural focus adjustment and convergence. Because light rays are controlled in a very small area, the blur becomes greater the further away from the display surface due to the effects of diffraction. For this reason, only objects near the display can be reproduced, and it is difficult to reproduce a social distance space when the display surface is close to the observer. On the other hand, if the display surface is placed away from the observer and near the social distance space, the display needs to be larger than the space to be displayed, which requires high costs and a large installation space.

[0011] As described above, when reproducing a social distance space, conventional light field displays had the problem of significant blurring due to the effects of diffraction.

[0012] The embodiments of the present invention have been made in consideration of the above-mentioned problems, and aim to provide a light reproduction device, a three-dimensional space display system, a light reproduction method, and a program that can display a space that has a depth of approximately 1.2 m to 3.6 m from the display surface (social distance space), or a space that has a depth greater than this, as a three-dimensional space that provides a natural sense of distance and has little blurring. [Means for solving the problem]

[0013] In order to solve the above problems, a light reproduction device according to an embodiment of the present invention is a light reproduction device that reproduces light rays virtually emitted from a stereoscopic image when the stereoscopic image is reproduced in a reproduction space, and includes a stereoscopic image display unit that displays the stereoscopic image as at least one of a virtual image and a real image by light rays emitted by each element cell included in an element cell set consisting of a plurality of element cells arranged two-dimensionally corresponding to a reproduction screen, and the stereoscopic image display unit displays the stereoscopic image in an area in the reproduction space whose distance in the depth direction corresponds to a social distance, The stereoscopic image is displayed within a range of at least 1.2 m to 3.6 m in the depth direction from the display surface, The size of each element cell in the element cell set and the pitch of the element cells when the element cells are arranged two-dimensionally are values ​​determined according to the degree to which the three-dimensional image displayed in the reproduction space is observed by the observer. the size of the element cells is determined so that the spread angle of the diffracted light from the element cells is equal to or smaller than the angular resolution according to the visual acuity of the observer, the size of the element cells is equal to or larger than 0.8 mm, and the pitch of the element cells is equal to or smaller than 1.2 mm. The degree of visibility to the observer here refers to the position and range in which the stereoscopic image is displayed, the degree of blur that the observer tolerates, and the like. Effect of the Invention

[0014] According to an embodiment of the present invention, a social distance space can be displayed as a three-dimensional space that provides a natural sense of distance and has little blurring. [Brief description of the drawings]

[0015] [Figure 1] 1 is a block diagram showing a configuration of a three-dimensional space display system 1 according to a first embodiment. [Diagram 2] FIG. 1 is a diagram illustrating an example in which a three-dimensional space display system 1 according to a first embodiment is applied. [Diagram 3] FIG. 11 is a block diagram showing the configuration of a three-dimensional space display system 100 according to a second embodiment. [Figure 4] FIG. 13 is a diagram illustrating an example in which a three-dimensional space display system 100 according to a second embodiment is applied. [Diagram 5] 1 is a characteristic diagram showing the relationship between the distance from the 3D display 30 to an object to be observed and the degree of blurring that occurs when reproducing the object. [Figure 6]FIG. 1 is a characteristic diagram showing the relationship between the distance from the 3D display 30 to an object to be observed and the resolution (diameter of the circle of confusion) on the retina of an observer who views the reproduced object. [Figure 7] FIG. 13 is a diagram showing an example of the relationship between size d and pitch p in an element cell. [Figure 8] FIG. 13 is a diagram showing an example in which a point object is reproduced as an object point A'. [Figure 9] FIG. 13 is a diagram showing an example of the brightness distribution of light rays (reproduced light) reproduced from an element cell. [Figure 10] FIG. 13 is a diagram showing an example in which a point object is reproduced as an object point A″. [Figure 11] FIG. 10 is a diagram showing an example in which a plurality of objects are reproduced using the method of FIG. [Figure 12] 11 is a diagram for explaining a method of calculating reconstruction data for a hologram by applying a ray tracing method. FIG. [Figure 13] 10 is a schematic diagram showing a manner in which an observer observes a reproduction point through a display surface. FIG. [Figure 14] 1 is a schematic diagram showing how light rays reproduced from a display become divergent light, resulting in blurring of the reproduction point. [Figure 15] 1 is a schematic diagram for explaining the divergence angle and magnitude of Fraunhofer diffraction by a circular aperture. FIG. [Figure 16] 4 is a flowchart showing the flow of processing performed by the three-dimensional display 30 of the embodiment. [Figure 17] FIG. 13 is a block diagram showing the configuration of a three-dimensional space display system 1A according to a modified example of the embodiment. [Figure 18] FIG. 13 is a diagram illustrating an example in which a three-dimensional space display system 1A according to a modified example of the embodiment is applied. [Figure 19] FIG. 1 is a schematic cross-sectional view illustrating the configuration of a conventional light field display using a microlens array. [Figure 20] FIG. 1 is a schematic cross-sectional view illustrating the configuration of a conventional static display type light field display in which liquid crystal panels are stacked. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] Hereinafter, the embodiments of the present invention will be described in detail with reference to the drawings. The three-dimensional space display system 1 is implemented, for example, by an optical device and an electric circuit. In each of the drawings described below, the thickness and ratio of components may be exaggerated for ease of viewing, and the number of components may be reduced. Furthermore, the present invention is not limited to the following embodiments as they are, and can be embodied by appropriate combinations and modifications without departing from the spirit of the present invention.

[0017] 1 is a block diagram showing the configuration of a three-dimensional space display system 1 according to a first embodiment. The three-dimensional space display system 1 includes, for example, a communication unit 10, a stereoscopic camera 20, and a three-dimensional display 30. The communication unit 10 communicates with the outside via a digital communication network NW.

[0018] The stereoscopic camera 20 is a camera that captures a stereoscopic image of an object to be observed, which is a subject, and is, for example, a stereo camera. The stereoscopic camera 20 transfers three-dimensional information of the object to be observed to the three-dimensional display 30 via the communication unit 10. The three-dimensional information here includes at least the incident direction and intensity of light rays incident on the imaging surface from the object, and may be obtained from two or more parallax image sequences or a combination of a two-dimensional image and a distance image, or may be information indicating a space including the object to be observed.

[0019] There are various methods for acquiring three-dimensional information. For example, when the stereoscopic camera 20 is a stereo camera, there is a method for acquiring three-dimensional information by measuring depth information (hereinafter, also referred to as depth information, depth distance, etc.) using images captured by the two cameras. Alternatively, there is a method for analyzing a pattern projected onto an object to be photographed. There is also a TOF method that measures the distance to an object to be observed by measuring the flight time of light. Any method may be used for acquiring three-dimensional information as long as it can measure at least the range of social distance with the required resolution. In particular, the TOF method that can accurately measure depth distances of several centimeters to several meters is preferable.

[0020] The range of space captured by the stereoscopic camera 20 is desirably a sufficiently wide space to allow recognition of social distance. For example, a space that extends 3.6 m deep at an angle of ±30 degrees and has an angle of view of 60 degrees or more is preferable. For example, a more realistic space can be captured with an angle of view of 80 degrees or more, equivalent to a wide-angle lens with a focal length of 25 mm in 35 mm film conversion. Furthermore, it is desirable that the minimum resolution Δα in the angular direction be 0.033 degrees or less, which is a resolution equivalent to a visual acuity of about 0.5.

[0021] For example, if the resolution of the stereoscopic camera 20 is high vision (1080×1920 pixels), the angle of view must be 73 degrees or less in order to make the minimum resolution in the angular direction Δα 0.033 degrees or less. Also, if the resolution of the stereoscopic camera 20 is 4K (2160×3840 pixels), the minimum resolution in the angular direction Δα must be 146 degrees or less. Therefore, when photographing a social distance space with an angle of view of 80 degrees or more, it is desirable to use a stereoscopic camera 20 with a resolution of 4K or more.

[0022] The communication unit 10 exchanges three-dimensional information with external devices using a digital communication network NW capable of stably transferring three-dimensional information video. In order to stably transfer a video including an image with a resolution of 4K and depth information for each pixel, for example, a communication speed of 25 Mbps or more is desirable. When a mobile communication network is used as the digital communication network, for example, by using a standard of 5G or higher, it becomes easy to exchange information with remote locations.

[0023] The three-dimensional display 30 is a computer device such as a PC (Personal Computer) that displays three-dimensional images, a server device, or a cloud server. The three-dimensional display 30 includes, for example, a calculation unit 31, a control unit 32, a light source unit 33, a display unit 34, a light control unit 35, and a storage unit 36. Here, the three-dimensional display 30 is an example of a "light reproduction device." The calculation unit 31 is an example of a "signal processing unit." The control unit 32 is an example of a "signal processing unit." The display unit 34 is an example of a "stereoscopic image display unit." The light control unit 35 is an example of a "stereoscopic image display unit."

[0024] The calculation unit 31 and the control unit 32 are functional units that perform signal processing, and are realized, for example, by a CPU (Central Processing Unit) of the three-dimensional display 30 executing a program pre-stored in the storage unit 36. Furthermore, these functional units that perform signal processing may be realized as integrated circuits such as ASICs (Application Specific Integrated Circuits).

[0025] The calculation unit 31 calculates the components (direction and intensity of light) of light to be reproduced (displayed) for each element cell based on the three-dimensional information acquired from the stereoscopic camera 20. The element cells here will be described in detail later.

[0026] The control unit 32 controls the light source unit 33, the display unit 34, and the light control unit 35 to reflect the direction and intensity of the light rays reproduced for each element cell. This makes it possible to display a space with a natural sense of distance and no blur. Note that if the light source unit 33 and the light control unit 35 in the three-dimensional display 30 are passive and do not need to be controlled, the control unit 32 does not need to control these functional units (the light source unit 33 and the light control unit 35).

[0027] When an image is displayed using only three-dimensional information acquired from the outside via the communication unit 10, without using the three-dimensional information acquired from the stereoscopic camera 20, it is possible to omit the stereoscopic camera 20 in the three-dimensional space display system 1. On the other hand, when an image is displayed on the three-dimensional display 30 using only the three-dimensional information from the stereoscopic camera 20, it is possible to omit the communication unit 10 in the three-dimensional display 30.

[0028] The light source unit 33 is a functional unit that has a light source function including a light emitting body such as a laser, an LED (Light-Emitting Diode), or an EL (Electro-Luminescence), and serves as a light source for the display unit 34. The light control unit 35 controls the direction and intensity of the light source irradiated by the light source unit 33 according to a control signal from the control unit 32.

[0029] The display unit 34 has a display function using display elements such as a liquid crystal display (LCD), an organic LED (OLED), a digital mirror device (DMD), etc. The display unit 34 displays an image according to the control of the control unit 32.

[0030] The display unit 34 is generally a display device that displays two-dimensional images, such as an LCD, LED, OLED, or DLP (Digital Light Processing). However, the present invention is not limited to this. The display unit 34 may be a type that scans the light source unit 33, such as a laser light source or an LED light source. In the case of a self-luminous device such as an LED or OLED, the display unit 34 has both a light source function and a display function. If the display unit 34 controls the direction of light by a diffraction pattern such as a hologram, the display function and the light control function can be realized in one device.

[0031] In the following description, the display surface refers to the surface on which a pattern is displayed by the display device of the display unit 34, and when an image is displayed using multiple display devices, refers to the surface closest to the viewer.

[0032] The storage unit 36 ​​is configured by a storage medium, for example, a hard disk drive (HDD), a flash memory, an electrically erasable programmable read only memory (EEPROM), a random access read / write memory (RAM), a read only memory (ROM), or any combination of these storage media. The storage unit 36 ​​stores programs for executing various processes of the three-dimensional display 30, and temporary data used when performing various processes. The storage unit 36 ​​stores, for example, three-dimensional information acquired by the stereoscopic camera 20. The storage unit 36 ​​stores the results of calculations performed by the calculation unit 31. The storage unit 36 ​​stores information indicating the direction and intensity of light rays reproduced under the control of the control unit 32.

[0033] Fig. 2 is a diagram for explaining an example in which the three-dimensional space display system 1 of the first embodiment is applied. In Fig. 2, the XY direction indicates a planar direction, and the Z direction indicates a vertical direction. The stereoscopic camera 20 is installed so as to be able to capture an image of the actual space JK to be observed. A plurality of actual images IM (actual images IM-1 to IM-7) are arranged in the actual space JK. The three-dimensional display 30 is installed so that the image to be displayed can be observed by an observer OB.

[0034] The stereoscopic camera 20 captures an image of the actual space JK. The three-dimensional display 30 displays a reproduced space SK that reproduces (displays) the actual space JK captured by the stereoscopic camera 20. In the example of FIG. 2, the stereoscopic camera 20 and the three-dimensional display 30 are shown overlapping, but they are in different positions in the Z direction and do not overlap. In addition, in this example, the imaging direction of the stereoscopic camera 20 is shown along the X-axis direction, but this is not limited to this. The position of the stereoscopic camera 20 may be any position that allows the observer OB to capture the actual space JK to be observed from any position or direction that the observer OB wishes to observe. In addition, the number of stereoscopic cameras 20 is not limited to one, and multiple stereoscopic cameras 20 may be installed.

[0035] In the example shown in this figure, the three-dimensional space display system 1 functions as a three-dimensional image display communicator that realizes communication by having a time lag between recording (capturing) and reproducing (displaying) three-dimensional information. That is, the three-dimensional information of the real space JK captured by the stereoscopic camera 20 is temporarily stored in the storage unit 36, and then the desired three-dimensional image is reproduced in the reproduced space SK at any time desired by the observer OB. This allows the observer OB to observe the real image IM of the real space JK at the time of capturing the image at any timing after capturing the image, even if the observer OB is not present at the time of capturing the image.

[0036] In the above, an example of recording and playing back with a time difference is shown, but the present invention is not limited to this. For example, the stereoscopic camera 20 and the three-dimensional display 30 may be installed in separate locations, such as an entrance and a living room, and function as a three-dimensional image communicator that realizes communication between separate locations where the other person cannot be directly seen. This allows the observer OB to experience (observe) a remote physical space JK without moving to the physical space JK.

[0037] Here, the social distance space that is the subject of this application will be described in detail. The social distance space is not a space in which an object (subject) exists near the display, as in the space displayed by a conventional three-dimensional display (stereoscopic image display device). The social distance space is a space in which a subject exists at a position distant in the depth direction in the space displayed by the display. The social distance space is, for example, a space inside a room or a space in a park, and is a space in which an observer (subject) exists within that section. Alternatively, it is a space that is displayed when the display is used as a window and the outside space (such as the space inside a room) is observed through the window.

[0038] Edward Hall, an American cultural anthropologist, classifies interpersonal distance (personal space) between people into the following four distance zones: 1) Close proximity 2) Individual distance 3) Social distancing 4) Public Distance

[0039] 1) Close distance is a distance of about 0 to 0.45 m, which corresponds to the distance at which you can sense the other person's body temperature or smell. Close distance is the distance between people with whom you have a very intimate relationship, and is an interpersonal distance where communication is mainly based on skin-to-skin contact, such as holding hands, and smell. 2) Personal distance is the distance between you and another person of about 0.45 to 1.2 meters, which corresponds to the distance you keep between yourself and another person in order to maintain your independence. It is the distance at which you or the other person can reach out and touch each other, and is the interpersonal distance when communicating with a close friend or other person. 3) Social distance is a distance of approximately 1.2 to 3.6 meters between people, a distance that makes it difficult to touch the other person, and is an interpersonal distance that is appropriate for communication in formal settings, such as conversations between colleagues at work. 4) Public distance is a distance of approximately 3.6 meters or more from the other person, which is a distance that is inappropriate for communication between two people, and is the interpersonal distance when communication such as a speech or lecture is taking place.

[0040] Fig. 3 is a block diagram showing the configuration of a three-dimensional space display system 100 according to the second embodiment. In the three-dimensional space display system 100 according to this embodiment, a plurality of the three-dimensional space display systems 1 shown in Fig. 1 are provided, which are connected to each other via a digital communication network NW. This constitutes a three-dimensional image display communicator that realizes natural communication between a plurality of remote locations. The three-dimensional information obtained by the stereoscopic camera 20 is compressed and / or converted by signal processing such as the calculation unit 31 as necessary, and is transmitted to the communication destination via the communication unit 10.

[0041] There are no particular limitations on the communication means used by the communication unit 10, but in order to send and receive three-dimensional information, it is preferable to have a communication means capable of transmitting large amounts of information at high speed, such as the 5G communication network mentioned above.

[0042] Fig. 4 is a diagram for explaining an example in which the three-dimensional space display system 100 of the second embodiment is applied. In Fig. 4, the XY direction indicates the planar direction, and the Z direction indicates the vertical direction. The positions, directions, and number of stereoscopic cameras 20 are the same as in Fig. 2, so their explanation will be omitted. The same applies to the three-dimensional display 30. In the example of this figure, the three-dimensional space display system 100 functions as a three-dimensional image display communicator that realizes natural communication between two remote locations that are communicatively connected via a digital communication network NW.

[0043] That is, three-dimensional information obtained by capturing images of members present in the physical space JK-1 by the stereoscopic camera 20-1 is transmitted to the three-dimensional display 30-2 via the digital communication network NW. As a result, the three-dimensional display 30-2 displays a reproduced space SK-1 that reproduces the space captured by the stereoscopic camera 20-1 (the physical space JK-1).

[0044] Meanwhile, three-dimensional information obtained by capturing an image of a member (one person in this example) present in the physical space JK-2 by the stereoscopic camera 20-2 is transmitted to the three-dimensional display 30-1 via the digital communication network NW. As a result, the three-dimensional display 30-1 displays a reproduced space SK-2 that reproduces the space (physical space JK-2) captured by the stereoscopic camera 20-2.

[0045] Here, the element cell of this embodiment will be described with reference to Fig. 5. Fig. 5 is a characteristic diagram showing the relationship between the distance from the 3D display 30 to an object to be observed and the magnitude of blurring that occurs when reproducing the object. The horizontal axis of Fig. 5 indicates the distance from the display. The vertical axis of Fig. 5 indicates the magnitude of blurring.

[0046] Generally, in a display that allows focus adjustment, as shown in Figure 13, the observer observes the space in front of and behind the display surface, and when a light ray spreading in the same direction from the reproduction point (the point object to be reproduced) is reproduced in a size smaller than the observer's pupil, the observer can observe as if there was a point light source in space.

[0047] However, strictly speaking, the light rays reproduced from the display become spread due to various reasons, as shown in Figure 14, which causes blurring in the reproduced image. In particular, when the element cells of the display that determine the direction of the light rays are small, the light will go around the outside of the aperture due to the effect of diffraction caused by the element cells as apertures, causing blurring.

[0048] The spread of diffraction caused by an aperture can be approximated as Fraunhofer diffraction at positions away from the display surface, and in the case of a circular aperture, the spread angle can be calculated from the size of the Airy disk (the bright area that occurs in the center of the diffraction pattern). In other words, the distance between the optical axis and the smallest dark ring that can be formed in the far field away from the circular aperture can be expressed as follows (see Figure 15) when expressed as the spread angle θ of a ray that is parallel to the optical axis and passes through the edge of the circular aperture. Here, λ in (Equation 1) is the wavelength of light, and d is the diameter of the circular aperture.

[0049] θ=1.22×λ / d (Formula 1)

[0050] An aperture such as the one described above is a unit of area on the display that defines the direction of light rays. This unit is called an "element cell." For example, in a light field display that uses a microlens array (Figure 19), one lens corresponds to an element cell. Also, in the case of a static display type light field display (Figure 20) in which LCD panels or the like are stacked, the pixels of the display used become element cells.

[0051] In a light field display, the direction of light rays is controlled for each element cell, so in order to provide a focus adjustment function, the element cells must be sufficiently smaller than the observer's pupil. Generally, the size of a human pupil is about 2 to 8 mm. Therefore, if the size of the element cell is 0.3 mm and the wavelength of light is 500 nm, the spread angle of the light rays can be expressed as follows from (Equation 1).

[0052] θ=1.22×500×10 -6 / 0.3 ≒2.03×10 -3 (rad) ≒0.12(degrees)

[0053] In other words, in Figure 15, the size of the blur caused by light rays passing through a 0.3 mm element cell at a position distance L = 3.6 m from the surface with the circular opening is 3600 × tan(0.12°) × 2 ≒ 15 (mm), which means that the blur spreads over a length of about 15 mm. For example, if a person's face at a position 3.6 m away is blurred by about 15 mm, the person can still be recognized, but it will be difficult to read their facial expression.

[0054] Generally, a person with 1.0 vision has an angular resolution of 1 / 60 degrees with the naked eye. The size d of the element cell that produces the equivalent divergence angle θ due to diffraction can be expressed as follows from (Equation 1), assuming a wavelength of 500 nm.

[0055] d=1.22×500×10-6 / tan(1 / 60°)×2 =4.2mm

[0056] Similarly, the size of the element cells that cause blurring, with an angular resolution of 1 / 60 / 0.7 degrees, equivalent to that of a person with 0.7 visual acuity, which is the requirement for a driver's license, is 2.9 mm. The minimum visual acuity without the need for glasses is 0.3, and the size of the element cells that cause blurring, calculated using a similar method under this condition, is 1.2 mm. With a visual acuity of 0.2, the size of the element cells that cause blurring is 0.8 mm. From this, it can be said that an element cell size d of at least 0.8 mm or more is necessary to keep the blurring to an acceptable level when observed.

[0057] Fig. 5 shows the relationship between the distance L from the display and the degree of blur caused by diffraction, with the element cell size d as a parameter. The element cell size d corresponds to d in Fig. 15. That is, it is the element cell size d calculated above, and corresponds to the calculated size d = 4.2 mm, 2.9 mm, 1.2 mm, or 0.8 mm depending on the conditions.

[0058] As shown in Figure 5, if the distance from the display (L) is the same, the larger the element cell size (d), the smaller the blur. This reflects the fact that as d in (Equation 1) increases, the spread angle θ decreases.

[0059] Here, the interval (pitch p) at which the element cells are arranged will be explained with reference to Fig. 6. Fig. 6 is a characteristic diagram showing the relationship between the distance from the 3D display 30 to the object to be observed and the resolution (diameter of the circle of confusion) on the retina of the observer who views the reproduced object. The horizontal axis of Fig. 6 indicates the distance from the display. The vertical axis of Fig. 6 indicates the diameter of the circle of confusion.

[0060] Generally, the size of a human pupil is about 2 to 8 mm, and eye focus adjustment is achieved by passing multiple light rays through this pupil. To achieve such focus adjustment, it is necessary to arrange the element cells at an interval (pitch p) such that light rays from at least two element cells enter the pupil. To achieve more natural focus adjustment, it is desirable to have a larger number of light rays (number of element cells) entering the pupil. In other words, it is desirable to reduce the interval (pitch p) between element cells in order to increase the number of element cells.

[0061] As shown in Figure 6, if the distance (L) from the observer to the object is the same, the smaller the pitch (p) of the element cells, the smaller the diameter of the circle of confusion. Since the spacing between photoreceptor cells on the human retina is approximately 10 μm (0.01 mm), in order to have better resolution (smaller diameter of the circle of confusion), an element cell pitch p of approximately 0.4 mm or less is required for an object that is more than 1.2 m away.

[0062] In addition, if the application allows for a resolution equivalent to that of a 24-inch XGA (Extended Graphics Array: a standard announced by IBM in 1990) display at a distance of 0.5 m (circle of confusion diameter of approximately 30 μm (0.03 mm) on the retina), then it can be seen that for objects more than 1.2 m away, the pitch p of the element cells should be arranged at 1.2 mm or less.

[0063] To sum up, if communication is carried out at a social distance (a distance between approximately 1.2 m and 3.6 m from the display), communication will be possible without practical problems if the element cell size d is 0.8 mm or more and the element cell pitch p is 1.2 mm or less.

[0064] In addition, the horizontal axis of Fig. 6 is the distance from the observer to the object, but the distance from which the observer will observe the display surface of the device is not known at the time of design. For this reason, at the time of design, calculations are performed assuming that the observer is closest to the display surface, that is, the distance from the observer to the object is the distance from the display surface to the object.

[0065] 7 is a schematic diagram of the case where the pitch p of the element cells is larger than the size d of the element cells (p≧d). This is an example of the above-mentioned case where the size d of the element cells is 0.8 mm or more and the pitch p of the element cells is 1.2 mm or less. In this case, since the relationship is p≧d, the element cells do not overlap each other. Therefore, the diffraction grating patterns are also independent and do not overlap.

[0066] 8 is a conceptual diagram of a display according to the present invention that reproduces a point object as object point A'. Each element cell reproduces the direction of light emitted from object point A' on the display surface. When viewed from various directions above the drawing, the viewer can see as if object point A' exists from each direction.

[0067] In this embodiment, as described in FIG. 6, it is assumed that the pitch p of the element cells is sufficiently small with respect to the size of the pupil. Also, as described in FIG. 5, it is assumed that the size d of the element cells is set to a size that causes little blurring due to diffraction. Therefore, the conditions necessary for stereoscopic vision, such as convergence, focus adjustment, and binocular parallax, are reproduced without any contradiction for the observer OB. Therefore, the observer OB does not feel eye strain. That is, even if the space is not close to the display surface or is far from the display surface, it is possible to reproduce a natural and natural space.

[0068] On the other hand, as shown in Figure 8, the light beam emitted from each element cell has a width of the element cell size (d) + the spread due to diffraction (Δα). Therefore, although there is no problem when observing a space far from the display surface, when observing an object close to the display surface, the resolution of the object will decrease.

[0069] There are several possible ways to deal with this problem. For example, as shown in Fig. 9, it is possible to make the brightness distribution of the light beam reproduced from the element cell a characteristic distribution. Fig. 9 is a diagram showing an example of the brightness distribution of the light beam (reproduced light) reproduced from the element cell. The upper part of Fig. 9 is a characteristic diagram showing the relationship between the position in the element cell and the brightness of the reproduced light. The lower part of Fig. 9 is a schematic diagram showing an image of the brightness distribution of the reproduced light emitted from the element cell.

[0070] As shown in Figure 9, the brightness of the light beam reproduced from the element cells is distributed so that it is brighter at the center and darker from the center to the periphery. In this way, it is possible to improve the resolution of the reproduced object. Creating such a brightness distribution of the light beam can be achieved by varying the diffraction efficiency within the element cells so that the transmittance of the interference fringe pattern recorded in the element cells decreases from the center to the periphery.

[0071] As a method for preventing a decrease in resolution, it is possible to adjust the size of object point A'' formed by the ray of reconstructed light reconstructed from each element cell, as shown in FIG. 10. That is, element cells are formed on the display surface, recording spherical waves diverging from object point A'', that is, interference fringes between the wavefront from the object point and the reference light. This makes it possible to reduce the size of object point A'' formed by the ray of light reconstructed from each element cell to the diffraction limit of the size d of the element cell, as shown in FIG. 10.

[0072] One method for achieving this is, for example, to use a CGH (Computer-Generated Hologram) calculated for each element cell. With this method, a hologram of the wavefront and reference light is calculated when light from an object reaches the position of an element cell. With this method, it is sufficient to execute calculations for each element cell. Therefore, the amount of calculations is smaller than that of normal CGH calculations, as described below, and parallel calculations are also possible, enabling high-speed calculations.

[0073] In this case, even one element cell can fulfill the function of focus adjustment. Therefore, even if the pitch p of the element cells is 1.2 mm or more, natural stereoscopic vision is possible. However, in order to smoothly change the image as the observer OB moves his / her viewpoint, it is desirable that the pitch p of the element cells is equal to or smaller than the size of the pupil. Therefore, it is desirable that the pitch p of the element cells is at least 7 mm or less, and more desirably 2 mm or less. In other words, when the element cells are holograms that record spherical waves from an object, a stereoscopic image with higher resolution can be observed by setting the size d of the element cells to 1.2 mm or more (equivalent to 0.5 visual acuity) and the pitch p of the element cells to 2 mm or less.

[0074] The state in which multiple objects are reproduced using the method of Fig. 10 will be described with reference to Fig. 11. In each element cell of the display surface, interference fringes between the spherical wave diverging from each point on the surface of the object and the reference light are recorded. From object B', which exists relatively close to the display surface, a spherical wave diverging from a nearby light point is reproduced. On the other hand, from object C', which exists relatively far from the display surface, a spherical wave diverging from a distant light point is reproduced. In this way, the wavefront is recorded differently depending on the distance from the display surface to the object.

[0075] In this embodiment, the interference fringes between the spherical waves diverging from each point on the surface of the object and the reference light are digitized by a stereoscopic camera 20. This is similar to conventional digital holograms, but this embodiment is characterized in that the object is sampled. That is, as shown in Fig. 11, the points at which the object is sampled are resolved by an angle of Δα from each element cell position.

[0076] As a result, while conventional digital holograms require wavefront calculations at a sampling pitch on the order of μm, the method of this embodiment requires sampling at a pitch of several mm to several cm, making it possible to reduce the enormous amount of calculations required in conventional methods.

[0077] Furthermore, in the method of this embodiment, the sampling interval (sampling pitch) increases the further away from the display surface, making the method of this embodiment suitable for reproducing a wide space far from the display surface.

[0078] In a holographic stereogram, a three-dimensional image is created to reproduce the direction of light rays. Therefore, it is possible to create data for displaying a three-dimensional image from images of an object taken from multiple directions. Therefore, by using CG (computer graphics) techniques that are being researched in various ways, it is possible to reproduce not only the shape of an object, such as a glossy or transparent object, but also its texture. Furthermore, by capturing an image of the actual object, it is also possible to reproduce a three-dimensional image of the actual object.

[0079] For example, a method of calculating a hologram pattern by applying the ray tracing method, which is one of the CG techniques, will be described with reference to FIG. 12. First, the center of each element cell is set as the starting point of a ray emitted by the ray tracing method. Next, the ray tracing method is performed with the center of each element cell as the starting point to find the intersection between the ray and the object to be the subject. This allows each element cell to have a set of point light sources from different viewpoint positions, making it possible to create a pattern of element cells with parallax in the up, down, left, and right directions. Note that the object (subject) here may be a three-dimensional object created based on three-dimensional information obtained from information captured by the stereoscopic camera 20, or may be a virtual object created using CAD (computer-aided design) or the like. In addition, if only the direction of the ray is considered in this calculation, the image will be reproduced by the ray as shown in FIG. 8. On the other hand, if both the direction of the ray and the distance to the object point are considered in this calculation, the image will be reproduced by the ray as shown in FIG. 10 or FIG. 11.

[0080] Here, the flow of processing performed by the 3D display 30 of the embodiment will be described with reference to the flowchart in Fig. 16. Fig. 16 shows the flow of calculation processing for a hologram pattern when the direction of a light ray and the distance to an object point are taken into consideration.

[0081] First, the three-dimensional display 30 obtains three-dimensional information of an object to be displayed on the display (step S10). Next, the three-dimensional display 30 determines the center position of the element cell to be calculated (step S11), and determines the intersection points between the object and each line that is emitted from the center position of the element cell and has an angle that differs by Δα (step S12). Then, the three-dimensional display 30 determines the intersection points with each object as object points, and determines the sum of the complex amplitudes of the spherical waves diverging from each object point at the element cell position (step S13). The complex amplitudes determined here may be within the range of the size of the element cell.

[0082] The three-dimensional display 30 performs the above steps (steps S11 to S13) for all element cells (steps S14 and S17).

[0083] Thereafter, the three-dimensional display 30 obtains the complex amplitude on the display surface by calculating the sum of the complex amplitudes of all the element cells (step S15). Next, the three-dimensional display 30 obtains the pattern of interference fringes between the wavefront of the reference light and the complex amplitude on the display surface (step S16). This allows the three-dimensional display 30 to obtain the pattern of the hologram to be displayed on the display.

[0084] In the process shown in the above-mentioned flowchart, the sum of the complex amplitudes is calculated (step S15) instead of the sum of the interference fringe patterns for each element cell, and then the interference fringe pattern with the reference light is calculated (step S16). In this way, the three-dimensional display 30 can record and reproduce a three-dimensional image of an object as information including both the direction of the light beam and the distance to the object point.

[0085] In the process shown in the above-mentioned flowchart, the sum of the complex amplitudes of the element cells is calculated, and then the interference pattern with the reference light is calculated, but this is not limited to this. The three-dimensional display 30 may calculate the sum of each interference pattern after obtaining the interference pattern with the reference light for each element cell. In this case, the three-dimensional display 30 can execute the calculation for each element cell. This makes it easier to perform parallel calculations, and the time required for the calculations can be shortened.

[0086] Furthermore, the recorded stereoscopic image (three-dimensional information of an object) may be a stereogram that takes into account only the horizontal parallax, but in order to make the focus adjustment more effective, it is preferable that the stereogram has both horizontal and vertical parallax. Furthermore, in the above-mentioned embodiment, the element cells are described as being circular, but this is not a limitation. The shape of the element cells may be a polygonal shape such as a triangle, a square, a pentagon, or a hexagon, or may be a star, an ellipse, a rectangle, or the like.

[0087] In addition, it is preferable to use a monochromatic light source such as a laser or LED as a light source for reproducing a holographic stereogram, or a light source that combines a normal light source with a filter, in order to suppress blurring caused by differences in diffraction angles due to wavelengths.

[0088] Furthermore, when using a laser light source as the light source, it is desirable to take measures to reduce the coherence in order to reduce noise caused by speckles. Possible methods for reducing the coherence of a laser light source include passing the light through an optical fiber, vibrating the light source, changing the optical path length, inserting a moving diffusing element into the optical path, and combining multiple light sources.

[0089] In the above, the social distance is set to a distance of approximately 1.2 m to approximately 3.6 m, but it is not necessary that all objects reproduced in the space exist within this distance range. It is sufficient that the object that is the main object of observation exists at least within this social distance range. Furthermore, the object (object) to be reproduced is not limited to a person, but may be an animal or a robot. Furthermore, the object (object) to be reproduced may be a two-dimensional image reproduced in the space. Furthermore, it may be a building that suggests the presence of a communication target, for example, a desk, chair, or table arranged in the space. Furthermore, the object to be reproduced does not have to be something that directly communicates. For example, the natural ground that is the object of observation when remotely operating heavy machinery may exist within the social distance range. The same applies to remote surgery, the operation of a robot arm in outer space, and the operation of an unmanned reconnaissance aircraft in the military.

[0090] As explained with reference to Figures 5 and 6, the present invention makes it possible to reproduce a wide space with little blur even when the depth of the space exceeds 3.6 m. For example, the present invention can be used to express a wide space such as a landscape or a space including large objects such as buildings or large plants and animals, thereby expressing a space beyond the social distance.

[0091] In addition, when the display is observed through an optical system such as an eyepiece, the conditions of the size d of the element cells and the pitch p of the element cells may be corrected based on the magnification of the optical system. For example, consider a case where the size d of the element cells is 1.0 mm and the pitch p of the element cells is 1.2 mm when the distance from the display is about 1.2 m to about 3.6 m and there is no eyepiece. In this case, when this embodiment is applied to a head-mounted display or the like and the magnification of the eyepiece attached to the head-mounted display or the like is 2 times, the three-dimensional display 30 corrects the size d of the element cells to 1.0 / 2=0.5 mm and the pitch p of the element cells to 1.2 / 2=0.6 mm. Conversely, when a reduction optical system is used and the magnification of the optical system is 0.5, the three-dimensional display 30 corrects the size d of the element cells to 1.0 / 0.5=2.0 mm and the pitch p of the element cells to 1.2 / 0.5=2.4 mm.

[0092] That is, the corrected size d# and the corrected p# are expressed by the following formula: In the following formula, d is the size before correction, p is the pitch before correction, and BR is the magnification of the optical system such as the eyepiece lens.

[0093] d#=d / BR p#=p / BR

[0094] When observing the display surface directly without using eyepieces, it is desirable to be able to observe with both eyes simultaneously in order to obtain the effect of convergence. Since the average interocular distance is about 60 mm, it is desirable for the size of the display surface to be at least 60 mm in the long axis direction.

[0095] (Modification of the embodiment) Here, a modified example of the embodiment will be described. This modified example differs from the above-described embodiment in that a virtual object (hereinafter, a virtual object) is reproduced in the reproduction space. The virtual object is, for example, a virtual character.

[0096] 17 is a block diagram showing the configuration of a three-dimensional space display system 1A in a modified example of the embodiment. The three-dimensional space display system 1A includes, for example, a communication unit 10 and a three-dimensional display 30. That is, in this modified example, it is possible to omit the stereoscopic camera 20.

[0097] The communication unit 10 acquires three-dimensional information of a virtual object from the outside. The virtual object includes not only the object to be observed but also three-dimensional information of the reproduced space, such as the background. The three-dimensional display 30 uses the three-dimensional information of the virtual object acquired via the communication unit 10 to reproduce and display, for example, the space in which the virtual object exists at a social distance.

[0098] Alternatively, the three-dimensional display 30 may include a functional unit that creates three-dimensional information of a virtual object. Alternatively, the three-dimensional display 30 of this modified example may use three-dimensional information of a virtual object that is stored in advance in the storage unit 36. In this case, the communication unit 10 can be omitted in the three-dimensional space display system 1.

[0099] Fig. 18 is a diagram for explaining an example in which a three-dimensional space display system 1A in a modified example of the embodiment is applied. In Fig. 18, a reproduction space SK in which a three-dimensional image of a virtual object generated by the configuration shown in Fig. 17 exists as a reproduction image SIM (in this example, reproduction images SIM1 to SIM7) can be displayed on a display. In this way, by using the three-dimensional display 30 of this modified example, more natural communication can be performed in a social distance space with depth that allows social distance with non-existent people such as people and characters created in a virtual space, or avatars of communication partners sent from other systems.

[0100] The means of communication in this modification is not limited to a specific means. For example, the three-dimensional space display system 1A may be applied to a means for communicating with a character. The character here is a virtual character displayed as a virtual object.

[0101] In this case, the three-dimensional space display system 1 includes, for example, a live camera and a processor that performs signal processing to display a three-dimensional space image in which a character has a predetermined reaction. The live camera captures an image of a user. The processor recognizes a gesture of the user from the image captured by the live camera, determines a reaction to be made by the character based on the gesture, and displays an image of the character having the determined reaction. This makes it possible to communicate with the character through the gesture.

[0102] Alternatively, the three-dimensional space display system 1A includes a microphone, a speaker, and a processor that performs signal processing to display a three-dimensional space image in which a character has a predetermined reaction. The user's voice is input to the microphone. The processor determines a voice response in response to the user's voice input from the microphone, and outputs the determined response from the speaker. The processor also determines a reaction to be made by the character in response to the user's voice, and displays an image of the character having the determined reaction. This makes it possible to communicate with the character through voice.

[0103] In addition, in this modified example, the virtual object may not be CG (Computer Graphics) but may be a live-action video image captured in advance by a stereoscopic camera, etc. Even in such a case, it is possible to interact (communicate) with the virtual object by switching the video image to be played as a reaction in response to input such as gestures or voice from the user as described above.

[0104] Furthermore, when the virtual object reproduced (displayed) by the three-dimensional space display system 1A is a stationary object, the display unit 34 of the three-dimensional display 30 may be configured to display an unchanging (still) image such as a printed matter.

[0105] The image displayed by the display unit 34 of the three-dimensional display 30 may be an image in which a hologram pattern is drawn using a fine patterning device such as an electron beam drawing device, or may be an image in which the drawn hologram pattern is replicated. In this way, by using a fixed hologram pattern (still image) as the image to be displayed, it is possible to reproduce a large space at low cost. In this case, the display unit 34 controls the direction of light by the hologram pattern. The display unit 34 displays the hologram pattern as at least one of a virtual image and a real image by the light beam emitted by each element cell. Therefore, the display function and the light control function are realized by one device. In such a case, it is not possible to make the virtual character displayed as a virtual object react, but it is possible to establish pseudo-audio communication with the virtual object as described above. In addition, the light control unit 35 may display a still image such as a fixed hologram pattern together with the display unit 34 or instead of the display unit 43. The display unit 34 is an example of a "stereoscopic image display unit". The light control unit 35 is an example of a "stereoscopic image display unit". Moreover, an image in which a hologram pattern is drawn is an example of a “stereoscopic image.” An image in which a drawn hologram pattern is replicated is an example of a “stereoscopic image.”

[0106] As described above, the three-dimensional display 30 of the embodiment reproduces light rays virtually emitted from a stereoscopic image when the stereoscopic image is reproduced in a reproduction space.

[0107] The three-dimensional display 30 of the embodiment includes a display unit 34 and / or a light control unit 35. The display unit 34 and / or the light control unit 35 are an example of a "stereoscopic image display unit." The display unit 34 and / or the light control unit 35 display a stereoscopic image as at least one of a virtual image and a real image by light rays emitted by each element cell included in an element cell set consisting of a plurality of element cells arranged two-dimensionally corresponding to a reproduction screen. The display unit 34 and / or the light control unit 35 display the stereoscopic image in an area in which the distance in the depth direction in the reproduction space corresponds to the social distance. In the three-dimensional display 30, the size d of the element cells and the pitch p of the element cells are values ​​determined according to the degree to which the stereoscopic image reproduced in the reproduction space is observed by the observer. The stereoscopic image is reproduced in an area in which the distance in the depth direction in the reproduction space corresponds to the social distance.

[0108] As a result, the 3D display 30 of the embodiment can determine the size d of the element cells and the pitch p of the element cells so that the stereoscopic image at the social distance in the reproduction space can be clearly seen by the observer OB. Therefore, the social distance space can be reproduced as a 3D space with a natural sense of distance and little blurring.

[0109] Moreover, the three-dimensional display 30 of the embodiment includes a calculation unit 31 and / or a control unit 32. The calculation unit 31 and / or the control unit 32 are an example of a "signal processing unit." The calculation unit 31 and / or the control unit 32 calculates the direction of a light ray to be reproduced for each element (element cell) of the element cell group. The element cells are arranged two-dimensionally corresponding to the reproduction screen. The element cells correspond to each element obtained by dividing a group of a plurality of light rays emitted from the surface of the stereoscopic image according to the position on the reproduction screen where each light ray reaches. This provides the same effect as described above.

[0110] In the three-dimensional display 30 of the embodiment, the element cell size d is determined according to the magnitude of blurring occurring in the reproduced three-dimensional image. As a result, the element cell size d is determined so as to suppress the magnitude of blurring to an allowable level, and therefore a three-dimensional image with little blurring can be reproduced.

[0111] Furthermore, the pitch p of the element cells is determined according to the resolution on the retina of the observer who observes the reproduced stereoscopic image. As a result, the pitch p of the element cells is determined so that focus adjustment is possible, and a stereoscopic image that can be focused on by the observer OB can be reproduced.

[0112] The three-dimensional space display system 1 (1A, 100) and the three-dimensional display 30 in the above-mentioned embodiment may be realized in whole or in part by a computer. In that case, a program for realizing this function may be recorded in a computer-readable recording medium, and the program recorded in the recording medium may be read into a computer system and executed to realize the function. The term "computer system" as used herein includes hardware such as an OS and peripheral devices. The term "computer-readable recording medium" refers to portable media such as flexible disks, optical magnetic disks, ROMs, and CD-ROMs, and storage devices such as hard disks built into a computer system. The term "computer-readable recording medium" may also include a medium that dynamically holds a program for a short period of time, such as a communication line when a program is transmitted via a network such as the Internet or a communication line such as a telephone line, and a medium that holds a program for a certain period of time, such as a volatile memory inside a computer system that is a server or client in that case. The above-mentioned program may be a program for realizing a part of the above-mentioned function, or may be a program that can realize the above-mentioned function in combination with a program already recorded in the computer system, or may be a program that is realized using a programmable logic device such as an FPGA.

[0113] Although an embodiment of the present invention has been described in detail above with reference to the drawings, the specific configuration is not limited to this embodiment, and designs that do not deviate from the gist of the present invention are also included. [Explanation of symbols]

[0114] 1, 1A, 100... three-dimensional space display system, 10... communication unit, 20... stereoscopic camera, 30... three-dimensional display (light reproduction device), 31... calculation unit (signal processing unit), 32... control unit (signal processing unit), 33... light source unit, 34... display unit (stereoscopic image display unit), 35... light control unit (stereoscopic image display unit), 36... storage unit

Claims

1. A light beam reproducing device for reproducing light beams virtually emitted from a stereoscopic image when the stereoscopic image is displayed in a reproduction space, comprising: a stereoscopic image display unit that displays the stereoscopic image as at least one of a virtual image and a real image by light rays emitted from each element cell included in an element cell set consisting of a plurality of element cells that are two-dimensionally arranged corresponding to a reproduction screen on which the plurality of light rays emitted from the surface of the stereoscopic image reach; Equipped with the stereoscopic image display unit displays the stereoscopic image in an area in the reproduction space where a distance in a depth direction corresponds to a social distance, the stereoscopic image is displayed within a range of at least 1.2 m to 3.6 m in the depth direction from the display surface; a size of an element cell which is each element in the element cell set, and a pitch of the element cells when the element cells are two-dimensionally arranged are values ​​determined according to a degree to which the stereoscopic image displayed in the reproduction space is observed by a viewer, a size of the element cell is determined so that a spread angle of diffracted light from the element cell is equal to or smaller than an angular resolution according to the visual acuity of the observer; The size of the element cell is 0.8 mm or more, and the pitch of the element cell is 1.2 mm or less. Ray regenerator.

2. A light beam reproducing device for reproducing light beams virtually emitted from a stereoscopic image when the stereoscopic image is displayed in a reproduction space, comprising: a stereoscopic image display unit that displays the stereoscopic image as at least one of a virtual image and a real image by light rays emitted from each element cell included in an element cell set consisting of a plurality of element cells that are two-dimensionally arranged corresponding to a reproduction screen on which the plurality of light rays emitted from the surface of the stereoscopic image reach; Equipped with the stereoscopic image display unit displays the stereoscopic image in an area in the reproduction space where a distance in a depth direction corresponds to a social distance, the stereoscopic image is displayed within a range of at least 1.2 m to 3.6 m in the depth direction from the display surface; a size of an element cell which is each element in the element cell set, and a pitch of the element cells when the element cells are two-dimensionally arranged are values ​​determined according to a degree to which the stereoscopic image displayed in the reproduction space is observed by a viewer, a size of the element cell is determined so that a spread angle of diffracted light from the element cell is equal to or smaller than an angular resolution according to the visual acuity of the observer; The size of the element cell is 1.2 mm or more, and the pitch of the element cell is 7 mm or less. Ray regenerator.

3. a signal processing unit that divides a set of a plurality of the light rays emitted from a surface of the stereoscopic image in accordance with a position on the reproduction screen, associates each element of the element cell set with each of the divided elements of the plurality of the light rays, and calculates one or more components of the light rays to be reproduced for each element of the element cell set, 3. The light reproducing device according to claim 1 or 2.

4. The pitch of the element cells is set to an area in which the distance in the depth direction in the reproduction space corresponds to the social distance. When the stereoscopic image is displayed on a retina of an observer who observes the displayed stereoscopic image, Determined according to the resolution above, The light reproducing device according to any one of claims 1 to 3.

5. The size of the element cell is determined to be smaller than the pitch of the element cell.

5. The light reproducing device according to claim 1.

6. The element cell is a hologram that records a wavefront from a stereoscopic image.

6. A light reproducing device according to claim 1.

7. The light reproducing device according to any one of claims 1 to 6, a stereoscopic camera that outputs three-dimensional information of a stereoscopic image to the light reproduction device; A three-dimensional space display system comprising:

8. A light reproduction method for a light reproduction device having a stereoscopic image display unit which reproduces light rays virtually emitted from a stereoscopic image when the stereoscopic image is displayed in a reproduction space, and displays the stereoscopic image as at least one of a virtual image and a real image by light rays emitted by each element cell included in an element cell set consisting of a plurality of element cells arranged two-dimensionally corresponding to a reproduction screen, comprising: the stereoscopic image display unit displays the stereoscopic image in an area in the reproduction space where the distance in the depth direction corresponds to a social distance; the stereoscopic image is displayed within a range of at least 1.2 m to 3.6 m in the depth direction from the display surface; a size of an element cell which is each element in the element cell set, and a pitch of the element cells when the element cells are two-dimensionally arranged are values ​​determined according to a degree to which the stereoscopic image displayed in the reproduction space is observed by a viewer, a size of the element cell is determined so that a spread angle of diffracted light from the element cell is equal to or smaller than an angular resolution according to the visual acuity of the observer; The size of the element cell is 0.8 mm or more, and the pitch of the element cell is 1.2 mm or less. Ray regeneration method.

9. A light reproduction method for a light reproduction device having a stereoscopic image display unit which reproduces light rays virtually emitted from a stereoscopic image when the stereoscopic image is displayed in a reproduction space, and displays the stereoscopic image as at least one of a virtual image or a real image by light rays emitted by each element cell included in an element cell set consisting of a plurality of element cells arranged two-dimensionally corresponding to a reproduction screen, comprising: the stereoscopic image display unit displays the stereoscopic image in an area in the reproduction space where the distance in the depth direction corresponds to a social distance; the stereoscopic image is displayed within a range of at least 1.2 m to 3.6 m in the depth direction from the display surface; a size of an element cell which is each element in the element cell set, and a pitch of the element cells when the element cells are two-dimensionally arranged are values ​​determined according to a degree to which the stereoscopic image displayed in the reproduction space is observed by a viewer, a size of the element cell is determined so that a spread angle of diffracted light from the element cell is equal to or smaller than an angular resolution according to the visual acuity of the observer; The size of the element cell is 1.2 mm or more, and the pitch of the element cell is 7 mm or less, Ray regeneration method.

10. a computer of a light beam reproduction device including a stereoscopic image display unit which reproduces light beams virtually emitted from a stereoscopic image when the stereoscopic image is displayed in a reproduction space, and displays the stereoscopic image as at least one of a virtual image and a real image by light beams emitted from each element cell included in an element cell set consisting of a plurality of element cells arranged two-dimensionally corresponding to a reproduction screen; a signal processing means for dividing a set of a plurality of said light rays emitted from a surface of said stereoscopic image in accordance with a position on said reproduction screen, for associating each element of said element cell set with each of said divided elements of said plurality of said light rays, and for calculating one or more components of said light rays to be reproduced for each element of said element cell set; A program that functions as the stereoscopic image display unit displays the stereoscopic image in an area in the reproduction space where a distance in a depth direction corresponds to a social distance, the stereoscopic image is displayed within a range of at least 1.2 m to 3.6 m in the depth direction from the display surface; a size of an element cell which is each element in the element cell set, and a pitch of the element cells when the element cells are two-dimensionally arranged are values ​​determined according to a degree to which the stereoscopic image displayed in the reproduction space is observed by a viewer, a size of the element cell is determined so that a spread angle of diffracted light from the element cell is equal to or smaller than an angular resolution according to the visual acuity of the observer; The size of the element cell is 0.8 mm or more, and the pitch of the element cell is 1.2 mm or less. program.

11. a computer of a light beam reproduction device including a stereoscopic image display unit which reproduces light beams virtually emitted from a stereoscopic image when the stereoscopic image is displayed in a reproduction space, and displays the stereoscopic image as at least one of a virtual image and a real image by light beams emitted from each element cell included in an element cell set consisting of a plurality of element cells arranged two-dimensionally corresponding to a reproduction screen; a signal processing means for dividing a set of a plurality of said light rays emitted from a surface of said stereoscopic image in accordance with a position on said reproduction screen, for associating each element of said element cell set with each of said divided elements of said plurality of said light rays, and for calculating one or more components of said light rays to be reproduced for each element of said element cell set; A program that functions as the stereoscopic image display unit displays the stereoscopic image in an area in the reproduction space where a distance in a depth direction corresponds to a social distance, the stereoscopic image is displayed within a range of at least 1.2 m to 3.6 m in the depth direction from the display surface; a size of an element cell which is each element in the element cell set, and a pitch of the element cells when the element cells are two-dimensionally arranged are values ​​determined according to a degree to which the stereoscopic image displayed in the reproduction space is observed by a viewer, a size of the element cell is determined so that a spread angle of diffracted light from the element cell is equal to or smaller than an angular resolution according to the visual acuity of the observer; The size of the element cell is 1.2 mm or more, and the pitch of the element cell is 7 mm or less. program.

Images