Reception control device, light receiving device, communication device, reception control method, and program

Abstract

In order to achieve continuous optical space communication at a stable communication speed, the present invention provides a reception control device comprising: a first processing circuit having a switching circuit including a switch connected to each of a plurality of light-receiving elements, selection switches arranged in each of groups in which the plurality of light-receiving elements are distributed, and a switching switch for switching the output destination of the selection switch of each group, and an amplification circuit configured from a plurality of amplifiers connected to the output of the switching circuit; a selector connected to the output of the first processing circuit; at least one second processing circuit that is arranged at a stage after the selector and decodes signals assigned via the selector; and a control circuit that controls the switching circuit so as to assign signals from the plurality of light-receiving elements to one of the plurality of amplifiers and controls the selector so as to assign a signal amplified by the amplification circuit to one of the second processing circuits.

Description

[Technical field]

[0001] The present disclosure relates to a reception control device that controls reception of an optical signal propagating through space. [Background technology]

[0002] In optical space communication, optical signals (hereinafter also referred to as spatial optical signals) that propagate through space are transmitted and received without using a medium such as optical fiber. In order to receive spatial optical signals that propagate through space, it is preferable to use a lens with as large a diameter as possible. In optical space communication, a light receiving element with a small capacitance is adopted to perform high-speed communication. Such light receiving elements have a small light receiving area. Since the focal length of a lens is limited, it is difficult to guide spatial optical signals arriving from various directions to a light receiving area with a small area using a large-diameter lens.

[0003] Patent Document 1 discloses an optical signal device that receives an optical signal via a medium such as an optical fiber. The device in Patent Document 1 includes an array of pixels having light receiving elements for receiving input signal light. The device in Patent Document 1 selects outputs from pixels in the array, adds the selected pixel outputs, and outputs the sum. The device in Patent Document 1 also includes an amplifier that amplifies the outputs of multiple pixels. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] International Publication No. 2008 / 114314 Summary of the Invention [Problem to be solved by the invention]

[0005] In the device of Patent Document 1, many pixels are connected to one amplifier. Therefore, in the device of Patent Document 1, when a light receiving element connected to the same amplifier is used for communication, the other light receiving elements connected to that amplifier cannot receive optical signals. Also, in the device of Patent Document 1, the circuit connected to one amplifier becomes huge, and the receiving speed of the optical signal decreases. In other words, in the device of Patent Document 1, it is not possible to realize continuous optical space communication at a stable communication speed.

[0006] An object of the present disclosure is to provide a reception control device and the like that can realize continuous free space optical communication at a stable communication speed. [Means for solving the problem]

[0007] A reception control device according to one embodiment of the present disclosure comprises a first processing circuit having a switching circuit including a switch connected to each of a plurality of light receiving elements, a selection switch arranged for each group into which the plurality of light receiving elements are distributed, and a change-over switch for switching the output destination of the selection switch for each group, and an amplification circuit composed of a plurality of amplifiers connected to the output of the switching circuit, a selector connected to the output of the first processing circuit, at least one second processing circuit arranged downstream of the selector and decoding a signal assigned via the selector, and a control circuit that controls the switching circuit to assign a signal from the plurality of light receiving elements to one of a plurality of amplifiers, and controls the selector to distribute a signal amplified by the amplification circuit to one of the second processing circuits.

[0008] In a reception control method according to one embodiment of the present disclosure, a control circuit controls a first processing circuit having a switching circuit including a first switch circuit constituted by a switch connected to each of a plurality of photoreceiving elements, a second switch circuit that switches the output destination of each group formed by integrating some of the plurality of switches included in the first switch circuit, and an amplification circuit including a plurality of amplifiers connected to the output of the switching circuit, thereby assigning signals from a plurality of photoreceiving elements to one of a plurality of amplifiers connected to the output of the switching circuit, and controls a selector connected to the output of the plurality of amplifiers to assign the signal amplified in the amplification circuit to one of a plurality of second processing circuits that decode the signal output from the first processing circuit.

[0009] A program according to one embodiment of the present disclosure causes a computer to execute the following processes: by controlling a first processing circuit having a switching circuit including a first switch circuit constituted by a switch connected to each of a plurality of light receiving elements, a second switch circuit that switches the output destination of each group formed by integrating some of the plurality of switches included in the first switch circuit, and an amplification circuit including a plurality of amplifiers connected to the output of the switching circuit, the program causes a computer to execute the following processes: by controlling a selector connected to the outputs of the plurality of amplifiers, the program causes a computer to execute the following processes: by controlling a first processing circuit having a switching circuit including a first switch circuit constituted by a switch connected to each of a plurality of light receiving elements, a second switch circuit that switches the output destination of each group formed by integrating some of the plurality of switches included in the first switch circuit, the program causes a computer to execute the following processes: by controlling a selector connected to the outputs of the plurality of amplifiers, the program causes a computer to execute the following processes: Effect of the Invention

[0010] According to the present disclosure, it is possible to provide a reception control device and the like that can realize continuous free space optical communication at a stable communication speed. [Brief description of the drawings]

[0011] [Figure 1] 1 is a conceptual diagram illustrating an example of a configuration of a light receiving device according to a first embodiment. [Diagram 2]3A and 3B are conceptual diagrams for explaining an example of light collection by a ball lens of the light receiving device according to the first embodiment. [Diagram 3] 2 is a conceptual diagram illustrating an example of a configuration of a light receiver included in the light receiving device according to the first embodiment. FIG. [Figure 4] 2 is a conceptual diagram showing an example of reception of an optical signal by a light receiving element constituting a light receiving element array included in the light receiving device according to the first embodiment. FIG. [Diagram 5] 2 is a conceptual diagram showing an example of reception of a spatial optical signal by the light receiving device according to the first embodiment. FIG. [Figure 6] 4 is a conceptual diagram showing another example of reception of a spatial optical signal by the light receiving device according to the first embodiment. FIG. [Figure 7] 2 is a block diagram showing an example of the configuration of a reception control device included in the light receiving device according to the first embodiment. FIG. [Figure 8] 2 is a conceptual diagram showing an example of the configuration of a first processing circuit included in a reception control device provided in the light receiving device according to the first embodiment. FIG. [Figure 9] 4 is a conceptual diagram for explaining an example of light reception control of a spatial light signal in the light receiving device according to the first embodiment. FIG. [Figure 10] 4 is a conceptual diagram for explaining an example of light reception control of a spatial light signal in the light receiving device according to the first embodiment. FIG. [Figure 11] 4 is a conceptual diagram for explaining an example of light reception control of a spatial light signal in the light receiving device according to the first embodiment. FIG. [Figure 12] 4 is a conceptual diagram for explaining an example of light reception control of a spatial light signal in the light receiving device according to the first embodiment. FIG. [Figure 13] 4 is a conceptual diagram for explaining an example of light reception control of a spatial light signal in the light receiving device according to the first embodiment. FIG. [Figure 14] 4 is a conceptual diagram for explaining an example of light reception control of a spatial light signal in the light receiving device according to the first embodiment. FIG. [Figure 15] 1 is a conceptual diagram showing an example of a configuration of a light receiving unit included in a light receiving device according to a first modified example of the first embodiment. FIG. [Figure 16] 11 is a conceptual diagram showing an example of a configuration of a light receiver included in a light receiving device according to a second modified example of the first embodiment. FIG. [Figure 17] 1 is a conceptual diagram for explaining an example of light reception control of a spatial light signal in a related art. [Figure 18] FIG. 11 is a block diagram showing an example of a configuration of a communication device according to a second embodiment. [Figure 19] 11 is a conceptual diagram illustrating an example of the configuration of a light transmitting device included in a communication device according to a second embodiment. FIG. [Figure 20] FIG. 11 is a conceptual diagram illustrating an example of a configuration of a communication device according to a second embodiment. [Figure 21] FIG. 11 is a conceptual diagram for explaining Application Example 1 according to the second embodiment. [Figure 22] FIG. 13 is a conceptual diagram illustrating an example of the configuration of a reception control device according to a third embodiment. [Figure 23] FIG. 2 is a block diagram showing an example of a hardware configuration for executing control and processing according to each embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] Hereinafter, the embodiments for carrying out the present invention will be described with reference to the drawings. However, the embodiments described below are limited in a manner that is technically preferable for carrying out the present invention, but the scope of the invention is not limited to the following. In addition, in all the drawings used to explain the following embodiments, the same reference numerals are used for similar parts unless otherwise specified. In addition, in the following embodiments, repeated explanations of similar configurations and operations may be omitted.

[0013] In all the drawings used to explain the following embodiments, the direction of the arrows in the drawings is an example, and does not limit the direction of light or signals. Furthermore, the lines showing the trajectory of light in the drawings are conceptual, and do not accurately represent the actual traveling direction or state of light. For example, in the drawings, the change in the traveling direction or state of light due to refraction, reflection, diffraction, diffusion, etc. at the interface between air and material may be omitted, or a light beam may be represented by a single line.

[0014] (First embodiment) First, a light receiving device according to a first embodiment will be described with reference to the drawings. The light receiving device of this embodiment is used for optical space communication in which an optical signal propagating through space (hereinafter also referred to as spatial optical signal) is transmitted and received without using a medium such as an optical fiber. The light receiving device of this embodiment may be used for purposes other than optical space communication as long as it receives light propagating through space. In this embodiment, unless otherwise specified, the spatial optical signal is regarded as parallel light because it arrives from a position sufficiently distant.

[0015] (composition) FIG. 1 is a conceptual diagram showing an example of the configuration of a light receiving device 10 of this embodiment. The light receiving device 10 includes a ball lens 11, a light receiving element array 13, and a reception control device 14. The ball lens 11 and the light receiving element array 13 constitute a light receiver 100. FIG. 1 is a plan view of the light receiver 100 seen from above. The light receiving element array 13 is composed of a plurality of light receiving elements 131 arranged in an arc shape. The positional relationship between the ball lens 11 and the light receiving element array 13 is fixed by a support (not shown). In this embodiment, the support for fixing the ball lens 11 and the light receiving element array 13 is omitted.

[0016] Ball lens 11 is a spherical lens. Ball lens 11 is an optical element that focuses a spatial optical signal arriving from the outside. Ball lens 11 is spherical when viewed from any angle. Ball lens 11 focuses the incident spatial optical signal. Light (also called an optical signal) originating from the spatial optical signal focused by ball lens 11 is focused toward the focusing area. Since ball lens 11 is spherical, it focuses a spatial optical signal arriving from any direction. That is, ball lens 11 exhibits the same focusing performance for spatial optical signals arriving from any direction.

[0017] FIG. 2 is a conceptual diagram showing an example of a trajectory of light focused by ball lens 11. In the example of Fig. 2, light emitted from light source 110, which emits parallel light, is irradiated towards ball lens 11. The light irradiated to ball lens 11 is refracted when entering the inside of ball lens 11. The light that has traveled inside ball lens 11 is refracted again when emitting to the outside of ball lens 11. Most of the light refracted by ball lens 11 is condensed in the light-condensing region. Light that has entered from the periphery of ball lens 11 is emitted in a direction away from the light-condensing region when emitting from ball lens 11.

[0018] For example, the ball lens 11 can be made of a material such as glass, crystal, or resin. When receiving a spatial optical signal in the visible region, a material that transmits / refracts light in the visible region can be applied to the ball lens 11. The material that transmits / refracts light in the visible region is, for example, glass, crystal, or resin. For example, the ball lens 11 can be made of optical glass such as crown glass or flint glass. For example, the ball lens 11 can be made of crown glass such as BK (Boron Kron). For example, the ball lens 11 can be made of flint glass such as LaSF (Lanthanum Schwerflint). For example, the ball lens 11 can be made of quartz glass. For example, the ball lens 11 can be made of crystal such as sapphire. For example, the ball lens 11 can be made of transparent resin such as acrylic. When the spatial optical signal is light in the near-infrared region (hereinafter also referred to as near-infrared), a material that transmits near-infrared light is used for the ball lens 11. For example, when receiving a spatial optical signal in the near-infrared region of about 1.5 micrometers (μm), materials such as silicon can be used for the ball lens 11 in addition to glass, crystal, resin, etc. When the spatial optical signal is light in the infrared region (hereinafter also referred to as infrared), a material that transmits infrared light is used for the ball lens 11. For example, when the spatial optical signal is infrared, materials such as silicon, germanium, and chalcogenide can be used for the ball lens 11. There is no limitation on the material of the ball lens 11 as long as it can transmit / refract light in the wavelength region of the spatial optical signal. The material of the ball lens 11 may be appropriately selected according to the required refractive index and application.

[0019] FIG. 3 is a perspective view of a light receiver 100 composed of a ball lens 11 and a light receiving element array 13. FIG. 3 is a perspective view looking down on the light receiver 100 from a vantage point diagonally above the incident surface side. The light receiving element array 13 has an arc shape with respect to the center of the ball lens 11. The light receiving element array 13 has an arc-shaped long side and a straight short side. The long side and the short side are perpendicular to each other. The multiple light receiving elements 131 constituting the light receiving element array 13 are arranged with their light receiving portions facing the center of the ball lens 11.

[0020] FIG. 4 is a cross-sectional view of a portion of the optical receiver 100. The optical receiver 100 is composed of a ball lens 11 and a light receiving element array 13. FIG. 4 shows a cross-section of an example in which light receiving elements 131 are arranged on an arc-shaped substrate 130. FIG. 4 shows the trajectory of light collected by the ball lens 11. The ball lens 11 collects an optical signal in a light collecting region in which the light receiving element array 13 is arranged. The collected optical signal is received by one of the light receiving elements 131 that constitute the light receiving element array 13. An optical signal that does not pass through the light receiving portion 132 of the light receiving element 131 is not received by the light receiving element 131.

[0021] The light receiving element array 13 includes a plurality of light receiving elements 131 arranged in an arc shape along the circumferential direction of the ball lens 11. There is no limitation on the number of light receiving elements 131 constituting the light receiving element array 13. The light receiving element array 13 is disposed behind the ball lens 11. The plurality of light receiving elements 131 include a light receiving section 132 that receives an optical signal derived from a spatial optical signal to be received. Each of the plurality of light receiving elements 131 is disposed such that the light receiving section 132 faces the emission surface of the ball lens 11. The light receiving section 132 of each of the plurality of light receiving elements 131 is disposed at the position of the light collecting region of the ball lens 11. The optical signal collected by the ball lens 11 is received by the light receiving section 132 of the light receiving element 131. The light receiving surface of each of the plurality of light receiving elements 131 includes a region where the light receiving section 132 is not located (also called a dead region).

[0022] FIG. 5 is a conceptual diagram showing an example in which the light receiving device 10 receives a spatial optical signal arriving from one direction. FIG. 6 is a conceptual diagram showing an example in which the light receiving device 10 receives a spatial optical signal arriving from two directions. Since the ball lens 11 is a sphere, the light receiving device 10 can uniformly receive spatial optical signals arriving from any direction within a range that can be received by the light receiving element array 13. For example, when the arc-shaped long side of the light receiving element array 13 is set parallel to a horizontal plane, the light receiving device 10 is likely to receive spatial optical signals arriving in the horizontal direction from about the same height. For example, when the arc-shaped long side of the light receiving element array 13 is set perpendicular to a horizontal plane, the light receiving device 10 is likely to receive spatial optical signals arriving from any height in the same manner. The orientation of the arc-shaped long side of the light receiving element array 13 may be adjusted according to the direction of arrival of the spatial optical signal to be received.

[0023] The multiple light receiving elements 131 are grouped into groups of several light receiving elements 131. For example, the multiple light receiving elements 131 are grouped into groups of four adjacent light receiving elements 131. The optical signals received by each of the multiple light receiving elements 131 are sorted into groups and distributed to one of multiple amplifiers (described later) included in the reception control device 14. The optical signals received by each of the multiple light receiving elements 131 are amplified by the amplifiers and then processed individually.

[0024] The light receiving element 131 receives light in a wavelength region of the spatial optical signal to be received. For example, the light receiving element 131 is sensitive to light in the visible region. For example, the light receiving element 131 is sensitive to light in the infrared region. The light receiving element 131 is sensitive to light with a wavelength in the 1.5 μm (micrometer) band, for example. The wavelength band of the light received by the light receiving element 131 can be set arbitrarily according to the wavelength of the spatial optical signal transmitted from a transmitting device (not shown). The wavelength band of the light received by the light receiving element 131 may be set to, for example, a 0.8 μm band, a 1.55 μm band, or a 2.2 μm band. The wavelength band of the light received by the light receiving element 131 may be, for example, a 0.8 to 1.0 μm band. A shorter wavelength band is less absorbed by moisture in the atmosphere, and is therefore advantageous for optical space communication during rainfall. Furthermore, if the light receiving element 131 becomes saturated with intense sunlight, it will not be able to read the optical signal derived from the spatial optical signal. For this reason, a color filter that selectively passes light in the wavelength band of the spatial optical signal may be provided in front of the light receiving element 131.

[0025] For example, the light receiving element 131 can be realized by an element such as a photodiode or a phototransistor. For example, the light receiving element 131 is realized by an avalanche photodiode. The light receiving element 131 realized by the avalanche photodiode can support high-speed communication. Note that the light receiving element 131 may be realized by an element other than a photodiode, a phototransistor, or an avalanche photodiode as long as it can convert an optical signal into an electrical signal. In order to improve the communication speed, it is preferable that the light receiving section 132 of the light receiving element 131 is as small as possible. For example, the light receiving section 132 of the light receiving element 131 has a square light receiving surface with one side of about 5 mm (millimeters). For example, the light receiving section 132 of the light receiving element 131 has a circular light receiving surface with a diameter of about 0.1 to 0.3 mm. The size and shape of the light receiving section 132 of the light receiving element 131 may be selected according to the wavelength band of the spatial optical signal, the communication speed, and the like.

[0026] The light receiving element 131 converts the received optical signal into an electrical signal. The light receiving element 131 outputs the converted electrical signal to the reception control device 14. Although only one line (path) is illustrated between the light receiving element array 13 and the reception control device 14 in FIG. 1, this does not indicate that the light receiving element array 13 and the reception control device 14 are connected by a single path. For example, the light receiving element array 13 and the reception control device 14 are connected by a plurality of paths. For example, each of the light receiving elements 131 constituting the light receiving element array 13 may be individually connected to the reception control device 14. For example, some of the light receiving elements 131 constituting the light receiving element array 13 may be grouped together, and the group may be connected to the reception control device 14.

[0027] The reception control device 14 acquires signals output from each of the multiple light receiving elements 131. The reception control device 14 includes multiple amplifiers. The reception control device 14 has a switching circuit that distributes signals from the multiple light receiving elements 131 to one of the multiple amplifiers. The reception control device 14 distributes signals output from the multiple light receiving elements 131 to one of the multiple amplifiers. When distributing a new optical signal, the reception control device 14 distributes the signal to an available amplifier among the multiple amplifiers. The reception control device 14 amplifies the signal from each of the multiple light receiving elements 131 with one of the amplifiers. The reception control device 14 decodes the amplified signal. The reception control device 14 analyzes the decoded signal from the communication target. For example, the reception control device 14 collectively analyzes the signals for each of the multiple grouped light receiving elements 131. When the signals for each of the multiple light receiving elements 131 are collectively analyzed, a single-channel light receiving device 10 that communicates with a single communication target can be realized. For example, the reception control device 14 individually analyzes the signal for each of the multiple light receiving elements 131. When the signals are analyzed individually for each of the multiple light receiving elements 131, a multi-channel light receiving device 10 that communicates with multiple communication targets simultaneously can be realized. The signals decoded by the reception control device 14 can be used for any purpose. There are no particular limitations on the use of the signals decoded by the reception control device 14.

[0028] [Reception control device] Next, an example of a detailed configuration of the reception control device 14 provided in the light receiving device 10 will be described with reference to the drawings. FIG. 7 is a block diagram showing an example of the configuration of the reception control device 14. The reception control device 14 has a first processing circuit 15, a control circuit 17, a selector 18, and a plurality of second processing circuits 19-1 to N (N is a natural number). In the example of FIG. 7, the number of light receiving elements 131 constituting the light receiving element array 13 is M (M is a natural number). Note that FIG. 7 is an example of the configuration of the reception control device 14, and is not intended to limit the configuration of the reception control device 14.

[0029] The first processing circuit 15 is connected to the plurality of light receiving elements 131-1 to M. The first processing circuit 15 amplifies a signal for each group of some of the light receiving elements 131 included in the plurality of light receiving elements 131-1 to M.

[0030] Fig. 8 is a conceptual diagram showing an example of the configuration of the first processing circuit 15. The first processing circuit 15 has a switching circuit 150 and an amplifier circuit 153. Fig. 8 shows an example in which a plurality of light receiving elements 131-1 to M constituting the light receiving element array 13 are distributed to one of a plurality of light receiving element groups PG (Photodiode Groups). Fig. 8 shows an example in which PGs each including four light receiving elements 131 are distributed to five light receiving element groups PG (PG1, PG2, PG3, PG4, PG5).

[0031] The switching circuit 150 includes a first switch circuit 151 and a second switch circuit 152. The first switch circuit 151 includes a plurality of switches SW (Switch) and a plurality of selection switches SS (Selection Switch). Each of the plurality of switches SW is associated with one of the plurality of light receiving elements 131-1 to M. The plurality of switches SW are distributed to one of the switch groups SG (Switch Groups) associated with one of the plurality of light receiving element groups PG. In FIG. 8, due to space limitations, only the leftmost switch SW is labeled with the symbol "SW", but all the switches SW included in the switch group SG have the same configuration. FIG. 8 shows an example in which the first switch circuit 151 includes a selection switch SS1, a selection switch SS2, a selection switch SS3, a selection switch SS4, and a selection switch SS5.

[0032] In the example of FIG. 8, each of the multiple selection switches SS is associated with one of the switch groups SG including four light receiving elements 131 each. In the example of FIG. 8, the multiple selection switches SS are arranged in association with each of the light receiving element groups PG in which some of the multiple light receiving elements 131-1 to M are grouped. The input terminal of each of the multiple selection switches SS is connected to the output terminal of one of the switch groups SG. Therefore, each of the multiple selection switches SS is associated with one of the light receiving element groups PG. The multiple selection switches SS are used for selection control of the light receiving element groups PG.

[0033] In the example of FIG. 8, five switch groups SG (SG1, SG2, SG3, SG4, SG5) are arranged in association with five light receiving element groups PG (PG1, PG2, PG3, PG4, PG5), respectively. The switch group SG1 is associated with the light receiving element group PG1. The input terminals of the switches SW included in the switch group SG1 are connected to any one of the light receiving elements 131 included in the light receiving element group PG1. The output terminals of the switches SW included in the switch group SG1 are connected to an input terminal of the selection switch SS1. The switch group SG2 is associated with the light receiving element group PG2. The input terminals of the switches SW included in the switch group SG2 are connected to any one of the light receiving elements 131 included in the light receiving element group PG2. The output terminals of the switches SW included in the switch group SG2 are connected to an input terminal of the selection switch SS2. The switch group SG3 is associated with the light receiving element group PG3. An input terminal of each of the switches SW included in the switch group SG3 is connected to one of the light receiving elements 131 included in the light receiving element group PG3. An output terminal of each of the switches SW included in the switch group SG3 is connected to an input terminal of the selection switch SS3. A switch group SG4 is associated with the light receiving element group PG4. An input terminal of each of the switches SW included in the switch group SG4 is connected to one of the light receiving elements 131 included in the light receiving element group PG4. An output terminal of each of the switches SW included in the switch group SG4 is connected to an input terminal of the selection switch SS4. A switch group SG5 is associated with the light receiving element group PG5. An input terminal of each of the switches SW included in the switch group SG5 is connected to one of the light receiving elements 131 included in the light receiving element group PG5. An output terminal of each of the switches SW included in the switch group SG5 is connected to an input terminal of the selection switch SS5.

[0034] An output terminal of each of the multiple switch groups SG included in the first switch circuit 151 is connected to an input terminal of one of the multiple selection switches SS. A multiple number of switches SW included in each of the multiple switch groups SG are opened and closed in response to the control of the control circuit 17. The selection switch SS connected to each of the multiple switch groups SG is also opened and closed in response to the control of the control circuit 17. A signal included in an optical signal received by the light receiving element 131 connected to a path in which the switch SW and the selection switch SS are closed is output to the second switch circuit.

[0035] The second switch circuit 152 includes a plurality of changeover switches CS (Changeover Switches). The plurality of changeover switches CS included in the second switch circuit 152 are controlled to be opened or closed by the control circuit 17. Depending on the open or closed state of the plurality of changeover switches CS, the output from the plurality of selection switches SS included in the first switch circuit 151 is distributed to one of the plurality of amplifiers AMP (Amplifiers) constituting the amplifier circuit 153. As a result, a connection is established between one of the light receiving element groups PG and the amplifier AMP. FIG. 8 shows an example in which the second switch circuit 152 includes a plurality of changeover switches CS (CS1, CS2, CS3, CS4, CS5, CS6, CS7, . . .). The changeover switch CS has a first end and a second end. The first ends of the plurality of changeover switches CS are connected to the output ends of at least one of the plurality of selection switches SS included in the first switch circuit 151. The second ends of the plurality of changeover switches CS are connected to one of the plurality of amplifiers AMP included in the amplifier circuit 153. In the example of FIG. 8, four light receiving element groups PG are assigned to one amplifier AMP. For example, four light receiving element groups PG may be assigned to one amplifier AMP. For example, the number of light receiving element groups assigned to one amplifier AMP can be set arbitrarily.

[0036] In the example of FIG. 8, the output terminal of the selection switch SS1 is connected to a first terminal of the changeover switch CS1. The output terminal of the selection switch SS2 is connected to a first terminal of the changeover switch CS2 and the changeover switch CS3. The output terminal of the selection switch SS3 is connected to a first terminal of the changeover switch CS3 and the changeover switch CS4. The output terminal of the selection switch SS4 is connected to a first terminal of the changeover switch CS5 and the changeover switch CS6. The output terminal of the selection switch SS5 is connected to a first terminal of the changeover switch CS6 and the changeover switch CS7.

[0037] A second end of each of the multiple selector switches CS included in the second switch circuit 152 is connected to an input end of multiple amplifiers AMP included in the amplifier circuit 153. By combining the open / closed states of the multiple switches SW, the multiple selection switches SS, and the multiple selector switches CS, it is possible to connect the light receiving elements 131 included in the light receiving element array 13 to the amplifiers AMP included in the amplifier circuit 153. The selector switches CS are used to distribute a signal of each light receiving element group PG included in the light receiving element array 13 to one of the amplifiers AMP included in the amplifier circuit 153.

[0038] The amplifier circuit 153 includes a plurality of amplifiers AMP. In the example of Fig. 8, the amplifier circuit 153 includes a plurality of amplifiers AMP (AMP1, AMP2, AMP3, ...). An input terminal of each of the plurality of amplifiers AMP is connected to a second terminal of one of a plurality of changeover switches CS included in the second switch circuit 152. Each amplifier AMP acquires a signal input via the second switch circuit 152. Each amplifier AMP amplifies the acquired signal. There is no particular limitation on the amplification factor of the signal by the amplifier AMP.

[0039] An output terminal of each of the multiple amplifiers AMP is connected to a selector 18. A signal amplified by each amplifier is output to the selector 18. By combining the open / closed states of multiple switches included in the switching circuit 150, signals from all of the multiple light receiving elements 131 included in the light receiving element array 13 can be input to each amplifier AMP. A signal from any of the multiple light receiving elements 131 is input to each amplifier AMP according to the combination of switches closed by the control circuit 17.

[0040] In the example of Fig. 8, the input terminal of the amplifier AMP1 is connected to the second terminals of the changeover switches CS1 and CS2. The input terminal of the amplifier AMP2 is connected to the second terminals of the changeover switches CS4 and CS5. The input terminal of the amplifier AMP3 is connected to the second terminal of the changeover switch CS7. The output terminals of the amplifiers AMP1, AMP2, and AMP3 are connected to the selector 18.

[0041] For example, the first processing circuit 15 may include a high-pass filter (not shown). For example, the high-pass filter is disposed between the light receiving element array 13 and the first processing circuit 15. The high-pass filter acquires a signal from the light receiving element 131. The high-pass filter selectively passes signals of high frequency components corresponding to the wavelength band of the spatial light signal from among the acquired signals. The high-pass filter cuts signals derived from ambient light such as sunlight. For example, instead of the high-pass filter, a band-pass filter that selectively passes signals in the wavelength band of the spatial light signal may be configured. If the light receiving element 131 becomes saturated with intense sunlight, the optical signal becomes unreadable. For this reason, a color filter that selectively passes light in the wavelength band of the spatial light signal may be disposed in front of the light receiving element array 13.

[0042] For example, the first processing circuit 15 includes an output monitor (not shown). The output monitor monitors the output value of each of the multiple amplifiers AMP included in the amplification circuit 153. The output monitor outputs a signal that exceeds a predetermined output value among the signals amplified by the amplifier AMP to the selector 18. Among the signals output to the selector 18, a signal to be received is assigned to one of the multiple second processing circuits 19-1 to 19-N according to the control of the control circuit 17. The signal to be received is a spatial optical signal from a communication device (not shown) to be communicated with. A signal from the light receiving element 131 that is not used to receive the spatial optical signal is not output to the second processing circuit 19.

[0043] For example, the first processing circuit 15 may include an integrator (not shown) as an output monitor (not shown). The integrator acquires a signal output from the high-pass filter. The integrator integrates the acquired signal. The integrator outputs the integrated signal to the control circuit 17. The integrator is disposed to measure the intensity of the spatial optical signal received by the light receiving element 131. Since the intensity of the spatial optical signal received in a state where the beam diameter is not narrowed is weaker than that in a state where the beam diameter is narrowed, it is difficult to measure the voltage of the signal amplified only by the amplifier. By using the integrator, the voltage of the signal can be increased to a level at which the voltage can be measured by integrating the signal for a period of, for example, several milliseconds to several tens of milliseconds.

[0044] The control circuit 17 controls the open / close states of a plurality of switches SW and a plurality of selection switches SS included in the switching circuit 150 of the first processing circuit 15. As a result, the light receiving element 131 used for receiving an optical signal is connected to the amplifier AMP used for amplifying a signal from the light receiving element 131. The control circuit 17 assigns a signal from the light receiving element 131 to an amplifier AMP not used for scanning or communication among the plurality of amplifiers AMP included in the amplification circuit 153. An example of control of the switching circuit 150 by the control circuit 17 will be described later in detail. The control circuit 17 controls the selector 18 so as to assign the signal from the light receiving element 131 to any one of a plurality of second processing circuits 19-1 to 19-N. For example, the control circuit 17 assigns a new scan or communication to a second processing circuit 19 that is not in use.

[0045] For example, the control circuit 17 acquires a signal output from the first processing circuit 15. In other words, the control circuit 17 acquires a signal derived from an optical signal received by each of the multiple light receiving elements 131-1 to M. The control circuit 17 may acquire an optical signal from the first processing circuit 15, or may acquire an optical signal from the second processing circuit 19. The control circuit 17 may acquire only an output value of an optical signal. For example, the control circuit 17 compares the read values ​​of signals from multiple light receiving elements 131 adjacent to each other. The control circuit 17 selects the light receiving element 131 having the maximum signal strength according to the comparison result. The control circuit 17 assigns one of the amplifiers AMP to the selected light receiving element 131. The control circuit 17 controls at least one of the multiple switches arranged between the selected light receiving element 131 and the selected amplifier AMP to a closed state, thereby establishing a connection between the light receiving element 131 and the amplifier AMP. By connecting the light receiving element 131 and the amplifier AMP, a connection between the light receiving element 131 and the selector is also established.

[0046] For example, when the position of the communication target is specified in advance, the control circuit 17 does not estimate the arrival direction of the spatial optical signal, and outputs the signal output from the light receiving elements 131-1 to M to any one of the second processing circuits 19 set in advance. For example, when the position of the communication target is not specified in advance, the control circuit 17 selects the second processing circuit 19 to which the signal output from the light receiving elements 131-1 to M is to be output. For example, during scanning of the communication target, the control circuit 17 measures the light receiving intensity of the optical signal received by the multiple light receiving elements 131 included in the light receiving element array 13 in order. For example, the control circuit 17 selects the light receiving element 131 having the maximum light receiving intensity of the optical signal as the light receiving element 131 to be assigned to receive the optical signal. The control circuit 17 selects the light receiving element 131, thereby making it possible to estimate the arrival direction of the spatial optical signal. The control circuit 17 selecting the light receiving element 131 corresponds to identifying the communication device that is the source of the spatial optical signal. Moreover, allocating a signal from the light receiving element 131 selected by the control circuit 17 to any one of the plurality of second processing circuits corresponds to associating the identified communication target with the light receiving element 131 that receives the spatial optical signal from the communication target. The control circuit 17 can identify the communication device that is the source of the optical signal (spatial optical signal) based on the optical signal received by the plurality of light receiving elements 131-1 to M. For example, the control circuit allocates the second processing circuit 19 to be used for communication with the communication target according to the intensity of the received optical signal, and establishes communication with the communication target.

[0047] For example, it is assumed that when 64 light receiving elements 131 are assigned to each of 8 amplifiers AMPs, each amplifier AMP is responsible for an angle of 15 degrees. The angle of 15 degrees corresponds to a width of 13.2 meters at 50 meters away and a width of 26.3 meters at 100 meters away. With such a width, signals originating from spatial optical signals transmitted from different communication targets may be input to one amplifier AMP. When signals originating from spatial optical signals transmitted from different communication targets are input to one amplifier AMP, interference occurs between the spatial optical signals from those communication targets. In order to avoid interference from the same direction, it is necessary to leave an interval of 2 to 3 light receiving elements 131. In other words, interference can be avoided by arranging one amplifier AMP for every 3 to 4 light receiving elements 131. In a general method, if one amplifier AMP is arranged for every 3 to 4 light receiving elements, 16 to 21 amplifiers AMPs are required. Furthermore, in order to accurately detect the direction of a communication target, it is necessary to configure a light receiving element group PG including at least four light receiving elements 131. In a general method, when configuring a light receiving element group PG including four light receiving elements 131, 64 light receiving elements are divided into groups of 16, which requires 16 amplifier circuits.

[0048] In this embodiment, a plurality of switches SW are associated with a light receiving element group PG, and a signal is allocated to a plurality of amplifiers AMP by combining the open / closed states of a plurality of selection switches SS and a plurality of changeover switches CS. Therefore, according to this embodiment, the number of amplifiers can be reduced while forming a group with an appropriate number of light receiving elements, so that the direction of the communication target can be accurately detected. For example, it is preferable that the number of light receiving elements 131 constituting the light receiving element group PG is set to an angle equal to or smaller than the angle at which the communication device can be positioned when viewed from the viewpoint of the light receiving device 10. If set in this manner, it is possible to prevent interference of spatial optical signals transmitted from a plurality of communication targets. That is, the plurality of light receiving elements 131 constituting the light receiving element array 13 are assigned to any of the light receiving element groups PG (groups) constituted by the number of light receiving elements 131 that fall within the light receiving range in which the spatial optical signal transmitted from a single communication target is received. In this embodiment, the plurality of light receiving elements 131 constituting the light receiving element array 13 are grouped for every four light receiving elements 131.

[0049] The selector 18 is connected to the first processing circuit 15. The selector 18 is connected to a plurality of amplifiers AMP included in the amplifier circuit 153 of the first processing circuit 15. A signal amplified by the amplifier circuit 153 included in the first processing circuit 15 is input to the selector 18. In response to the control of the control circuit 17, the selector 18 outputs a signal to be received among the input signals to one of the plurality of second processing circuits 19-1 to 19-N. Signals that are not to be received are not output from the selector 18.

[0050] A signal from any one of the light receiving elements 131-1 to 131-N assigned by the control circuit 17 is input to the second processing circuits 19-1 to 19-N. Each of the second processing circuits 19-1 to 19-N decodes the input signal. Each of the second processing circuits 19-1 to 19-N may be configured to perform some kind of signal processing on the decoded signal, or may be configured to output the decoded signal to an external signal processing device or the like (not shown).

[0051] A signal originating from the light receiving element 131 selected by the control circuit 17 is selected by the selector 18, so that one second processing circuit 19 is assigned to one communication target. That is, the control circuit 17 assigns signals originating from the spatial optical signals from the communication targets, which are received by the multiple light receiving elements 131-1 to M, to any one of the multiple second processing circuits 19-1 to N. This establishes optical space communication with the communication target. As a result, the light receiving device 10 is able to read the signal originating from the spatial optical signal from the communication target on a channel set in any one of the second processing circuits 19. According to the method of this embodiment, the spatial optical signals from the multiple communication targets can be read simultaneously on multiple channels. For example, in order to communicate simultaneously with multiple communication targets, the spatial optical signals from the multiple communication targets may be read in a single channel in a time-division manner. Allocating signals included in the spatial optical signals from the multiple communication targets to multiple channels can increase the transmission speed compared to using a single channel.

[0052] For example, the direction of arrival of the spatial optical signal may be identified by a coarse primary scan, and the exact location of the communication target may be identified by a fine secondary scan in the identified direction. When communication with the communication target is possible, the exact location of the communication target can be determined by exchanging signals with the communication target. If the location of the communication target has been identified in advance, the process of identifying the location of the communication target can be omitted.

[0053] [Reception control] Next, the reception control of the spatial light signal in the reception control device 14 will be described with some examples. Below, possible examples of reception control in scanning a communication target and reception control in communication with a communication target with which communication has been established will be given. Note that the reception control given below is merely an example and does not limit the reception control of this embodiment. Furthermore, the reception control given below does not cover all of the reception control of this embodiment. The reception control of this embodiment may include methods other than the examples below.

[0054] [Control example 1] Fig. 9 is a conceptual diagram for explaining an example (control example 1) of spatial optical signal reception control in the reception control device 14. The example in Fig. 9 relates to a mode for scanning a communication target (also called a scan mode).

[0055] In the example of Fig. 9, the light receiving element group PG2 and the amplifier AMP1 are connected. The control circuit 17 closes the second switch SW from the left of the switch group SG2, the selection switch SS2, and the changeover switch CS2. As a result, the light receiving element group PG2 and the amplifier AMP1 are connected. In Fig. 9, the light receiving element 131 being scanned and the amplifier AMP1 used for that scan are indicated by hatching. The path between the light receiving element 131 being scanned and the amplifier AMP1 used for that scan is indicated by a thick line as the path along which the signal propagates during scanning.

[0056] In the scan mode, the control circuit 17 activates the light receiving elements 131 included in the light receiving element array 13 in sequence, and selects the light receiving element 131 to be assigned for communication with the communication target. For example, the control circuit 17 selects the light receiving element 131 that receives the strongest optical signal. For example, the control circuit 17 may assign the light receiving element group PG that includes the light receiving element 131 that receives the strongest optical signal to communication with the communication target. According to this control example, a scan mode can be set to scan for a communication target.

[0057] [Control example 2] Fig. 10 is a conceptual diagram for explaining an example (control example 2) of reception control of a spatial optical signal in the reception control device 14. This control example is an example in which scanning of another communication target is continued after communication with the communication target (first communication target) is established in control example 1. In the example of Fig. 10, a communication mode in which communication with the communication target is performed and a scan mode in which the communication target is scanned are performed in parallel.

[0058] In the example of Fig. 10, the light receiving element group PG2 and the amplifier AMP1 are connected. The control circuit 17 closes the third switch SW from the left of the switch group SG2, the selection switch SS2, and the changeover switch CS2. As a result, the light receiving element group PG2 and the amplifier AMP1 are connected. In Fig. 10, the light receiving element 131 in communication and the amplifier AMP1 used for that communication are indicated by hatching. The path between the light receiving element 131 in communication and the amplifier AMP1 used for that communication is indicated by a thick line as the path along which the signal in communication with the first communication target propagates.

[0059] In the example of Fig. 10, the light receiving element group PG5 and the amplifier AMP3 are connected. The control circuit 17 closes the second switch SW from the left of the switch group SG5, the selection switch SS5, and the changeover switch CS7. As a result, the light receiving element group PG5 and the amplifier AMP3 are connected. In Fig. 10, the light receiving element 131 being scanned and the amplifier AMP3 used for the scan are indicated by hatching. The path between the light receiving element 131 being scanned and the amplifier AMP3 used for the scan is indicated by a thick line as the path along which the signal propagates during the scan.

[0060] In the example of FIG. 10, the communication mode and the scan mode are set in parallel. In the communication mode, the control circuit 17 fixes the connection between the light receiving element 131 with which communication has been established and the amplifier AMP. With respect to the light receiving element group PG not used for communication, the control circuit 17 activates the light receiving elements 131 included in the light receiving element array 13 in order, and selects the light receiving element 131 to be assigned to communication with the communication target. For example, the control circuit 17 selects the light receiving element 131 with the maximum strength of the received optical signal. For example, the control circuit 17 may assign the light receiving element group PG including the light receiving element 131 with the maximum strength of the received optical signal to communication with the communication target.

[0061] Fig. 11 shows a state where the scanning in Fig. 10 is continued. The example in Fig. 11 shows a state where scanning of the light receiving element group PG1 is completed after scanning of the light receiving element group PG3, the light receiving element group PG4, and the light receiving element group PG5. According to this control example, the light receiving element group PG in communication is skipped, and the scan mode can be set for the light receiving element groups PG other than that light receiving element group PG.

[0062] [Control Example 3] Fig. 12 is a conceptual diagram for explaining an example (control example 3) of reception control of a spatial optical signal in the reception control device 14. This control example shows a state after communication with a second communication target (second communication target) is established by control example 2. In the example of Fig. 12, communication with two communication targets (first communication target, second communication target) is performed in parallel.

[0063] In the example of Fig. 12, the light receiving element group PG2 and the amplifier AMP1 are connected. The control circuit 17 closes the third switch SW from the left of the switch group SG2, the selection switch SS2, and the changeover switch CS2. As a result, the light receiving element group PG2 and the amplifier AMP1 are connected. In Fig. 12, the light receiving element 131 in communication included in the light receiving element group PG2 and the amplifier AMP1 used for that communication are indicated by hatching. The path between the light receiving element 131 in communication included in the light receiving element group PG2 and the amplifier AMP1 used for that communication is indicated by a thick line as a path along which a signal in communication with the first communication target propagates.

[0064] In the example of Fig. 12, the light receiving element group PG5 and the amplifier AMP3 are connected. The control circuit 17 closes the second switch SW from the left of the switch group SG5, the selection switch SS5, and the changeover switch CS7. As a result, the light receiving element group PG5 and the amplifier AMP3 are connected. In Fig. 12, the light receiving element 131 included in the light receiving element group PG5 in communication and the amplifier AMP3 used for that communication are indicated by hatching. The path between the light receiving element 131 included in the light receiving element group PG5 in communication and the amplifier AMP3 used for that communication is indicated by a thick line as a path along which a signal during communication with the second communication target propagates.

[0065] 12, two communication modes are set in parallel. In the communication mode, the control circuit 17 fixes the connection between the light receiving element 131 and the amplifier AMP with which communication has been established. According to this control example, communication with two communication targets can be established.

[0066] [Control Example 4] Fig. 13 is a conceptual diagram for explaining an example (control example 4) of reception control of a spatial optical signal in the reception control device 14. This control example is an example in which communication with a new communication target (third communication target) is established by a new scan after control example 3. In the example of Fig. 13, communication with three communication targets (first communication target, second communication target, third communication target) is performed in parallel.

[0067] In the example of Fig. 13, the light receiving element group PG2 and the amplifier AMP1 are connected. The control circuit 17 closes the third switch SW from the left of the switch group SG2, the selection switch SS2, and the changeover switch CS2. As a result, the light receiving element group PG2 and the amplifier AMP1 are connected. In Fig. 13, the light receiving element 131 in communication included in the light receiving element group PG2 and the amplifier AMP1 used for that communication are indicated by hatching. The path between the light receiving element 131 in communication included in the light receiving element group PG2 and the amplifier AMP1 used for that communication is indicated by a thick line as a path along which a signal in communication with the first communication target propagates.

[0068] In the example of Fig. 13, the light receiving element group PG5 and the amplifier AMP3 are connected. The control circuit 17 closes the second switch SW from the left of the switch group SG5, the selection switch SS5, and the changeover switch CS7. As a result, the light receiving element group PG5 and the amplifier AMP3 are connected. In Fig. 13, the light receiving element 131 included in the light receiving element group PG5 in communication and the amplifier AMP3 used for that communication are indicated by hatching. The path between the light receiving element 131 included in the light receiving element group PG5 in communication and the amplifier AMP3 used for that communication is indicated by a thick line as a path along which a signal in communication with the second communication target propagates.

[0069] Furthermore, in the example of Fig. 13, the light receiving element group PG4 and the amplifier AMP2 are connected. The control circuit 17 closes the first switch SW from the left of the switch group SG4, the selection switch SS4, and the changeover switch CS5. As a result, the light receiving element group PG4 and the amplifier AMP2 are connected. In Fig. 13, the light receiving element 131 in communication included in the light receiving element group PG4 and the amplifier AMP2 used for that communication are indicated by hatching. The path between the light receiving element 131 in communication included in the light receiving element group PG4 and the amplifier AMP2 used for that communication is indicated by a thick line as a path along which a signal in communication with the third communication target propagates.

[0070] In the example of Fig. 13, three communication modes are set in parallel. In the communication mode, the control circuit 17 fixes the connection between the light receiving element 131 and the amplifier AMP with which communication has been established. According to this control example, communication with three communication targets can be established. Four or more communication targets may be set for communication. When the scan mode and the communication mode are performed in parallel, it is sufficient that at least one amplifier AMP is set in an unused state so that scanning is performed.

[0071] [Control Example 5] Fig. 14 is a conceptual diagram for explaining an example (control example 5) of reception control of a spatial optical signal in the reception control device 14. This control example is an example in which, after control example 4, communication with two communication targets (first communication target, second communication target) is ended, and a new scan is started while communication with one communication target (third communication target) is continued. In the example of Fig. 14, communication with one communication target (third communication target) and scanning of the new communication target are performed in parallel.

[0072] In the example of FIG. 14, the light receiving element group PG4 and the amplifier AMP2 are connected. The control circuit 17 closes the first switch SW from the left of the switch group SG4, the selection switch SS4, and the changeover switch CS5. As a result, the light receiving element group PG4 and the amplifier AMP2 are connected. In FIG. 14, the light receiving element 131 included in the light receiving element group PG4 in communication and the amplifier AMP2 used for that communication are indicated by hatching. The path between the light receiving element 131 included in the light receiving element group PG4 in communication and the amplifier AMP2 used for that communication is indicated by a thick line as a path along which a signal in communication with the third communication target propagates.

[0073] In the example of Fig. 14, the light receiving element group PG3 and the amplifier AMP1 are connected. The control circuit 17 closes the second switch SW from the left of the switch group SG3, the selection switch SS3, the changeover switch CS2, and the changeover switch CS3. As a result, the light receiving element group PG3 and the amplifier AMP1 are connected. In Fig. 14, the light receiving element 131 being scanned in the light receiving element group PG3 and the amplifier AMP1 used for the scan are indicated by hatching. The path between the light receiving element 131 being scanned in the light receiving element group PG3 and the amplifier AMP1 used for the scan is indicated by a thick line as the path along which the signal propagates during the scan.

[0074] In the example of FIG. 14, the communication mode and the scan mode are set in parallel. In the communication mode, the control circuit 17 fixes the connection between the light receiving element 131 with which communication has been established and the amplifier AMP. For the light receiving element group PG not used for communication, the control circuit 17 activates the light receiving element 131 included in the light receiving element array 13 in order and selects the light receiving element 131 to be assigned to communication with the communication target. The control circuit 17 skips the light receiving element group PG including the light receiving element 131 in communication and sets the scan mode for the light receiving element groups PG other than the light receiving element group PG. According to this control example, the light receiving element 131 and the amplifier AMP used for communication can be diverted to scanning while continuing communication with the communication target with which communication has been established.

[0075] [Variation 1] Next, a first modified example according to the present embodiment will be described with reference to the drawings. Fig. 15 is a conceptual diagram showing an example of the configuration of a photoreceiver 10-1 of this modified example. Fig. 15 is a perspective view of the photoreceiver 10-1 as seen from a vantage point diagonally above the incident surface side. The photoreceiver 10-1 of this modified example is composed of a ball lens 11 and a photoreceptor array 13-1.

[0076] Light receiving element array 13-1 has a structure in which multiple light receiving element arrays 13 are stacked in the short side direction. Each of the light receiving elements included in light receiving element array 13-1 is disposed in the light collecting region of ball lens 11. That is, light receiving element array 13-1 is composed of multiple light receiving elements arranged in an array on a curved surface that matches the light collecting region of ball lens 11. Fig. 15 shows an example in which three light receiving element arrays 13 are stacked to form light receiving element array 13-1, but there is no particular limit to the number of light receiving element arrays 13 that constitute light receiving element array 13-1.

[0077] Even if the direction of arrival of the spatial optical signal is slightly shifted in the direction of the short side of the photodetector array 13-1, the photodetector 10-1 of this modification can similarly receive the spatial optical signal arriving at the ball lens 11. In other words, according to this modification, even if the direction of arrival of the spatial optical signal fluctuates in the vertical direction within the plane formed by the arc of the photodetector array 13-1, the signal light originating from the spatial optical signal can be received by any of the multiple photodetector arrays 13 included in the photodetector array 13-1.

[0078] If the directions of arrival of the spatial optical signals are not limited to within the same plane, a situation may arise in which communication with a desired communication target cannot be performed if the spatial optical signals arriving from three-dimensional directions cannot be received with respect to ball lens 11. According to this modification, by using light-receiving element array 13-1 in which a plurality of light-receiving elements are arranged in an array, the light-receiving range of the spatial optical signals can be expanded compared to the case in which a single light-receiving element array 13 is used.

[0079] [Modification 2] Next, a second modified example of this embodiment will be described with reference to the drawings. Fig. 16 is a conceptual diagram showing an example of the configuration of a photoreceiver 10-2 of this modified example. Fig. 16 is a perspective view of the photoreceiver 10-2 as seen from a vantage point diagonally above the incident surface side. The photoreceiver 10-2 of this modified example is composed of a ball lens 11 and a photoreceptor array 13-2.

[0080] The light receiving element array 13-2 has a structure in which a plurality of light receiving element arrays 13 are arranged in a ring shape. Each of the light receiving elements included in the light receiving element array 13-2 is arranged in the light collecting area of ​​the ball lens 11. That is, the light receiving element array 13-2 is composed of a plurality of light receiving elements arranged in a ring shape on a circumference that matches the light collecting area of ​​the ball lens 11. There is no limitation on the number of light receiving elements that constitute the light receiving element array 13-2. The light receiving element array 13-2 is arranged in the rear stage of the ball lens 11. The plurality of light receiving elements include a light receiving section (not shown) that receives an optical signal derived from a spatial optical signal to be received. Each of the plurality of light receiving elements is arranged so that the light receiving section faces the exit surface of the ball lens 11. Each of the plurality of light receiving elements is arranged so that the light receiving section is located in the light collecting area of ​​the ball lens 11. The optical signal collected by the ball lens 11 is received by the light receiving section of the light receiving element located in the light collecting area.

[0081] If the direction of arrival of the spatial optical signal is not limited to one direction, a situation may arise in which communication with a desired communication target cannot be performed if the spatial optical signals arriving from various directions cannot be received from ball lens 11. According to this modification, by using light-receiving element array 13-2 in which a plurality of light-receiving elements are arranged in a ring shape, it is possible to receive spatial optical signals arriving from directions of 360 degrees.

[0082] Comparative Example Next, the light receiving control of a comparative example (related technology) of this embodiment will be described with reference to the drawings. The comparative example includes the problems solved by this embodiment. The comparative example is an example for explaining problems that may occur when an amplifier is shared for multiple light receiving elements. FIG. 17 is a conceptual diagram for explaining the light receiving control of the comparative example. The light receiving control of the comparative example will be described by taking as an example a light receiving device including a light receiving element array 135, a processing circuit 155, and a selector 185.

[0083] The light receiving element array 135 includes a plurality of light receiving elements. The light receiving elements included in the light receiving element array 135 are assigned to any one of a plurality of light receiving element groups PG (light receiving element group PG101, light receiving element group PG102, . . . ).

[0084] The processing circuit 155 includes a switch group 156 including a plurality of switches, and an amplifier circuit including a plurality of amplifiers AMP. Each of the plurality of switches included in the processing circuit 155 is connected to one of the plurality of light receiving elements included in the light receiving element array 135. The plurality of switches included in the processing circuit 155 are assigned to one of a plurality of switch groups SG (switch group SG101, switch group SG102, ...).

[0085] Each of the multiple amplifiers AMP (amplifier AMP101, amplifier AMP102) included in the amplifier circuit 153 is disposed between the switch group 156 and the selector 185. The amplifier AMP101 is connected to the output terminals of the multiple switches included in the switch group SG101. The amplifier AMP102 is connected to the output terminals of the multiple switches included in the switch group SG102. The output terminals of each of the multiple amplifiers AMP (amplifier AMP101, amplifier AMP102) are connected to the selector 185.

[0086] In the example of FIG. 17, the sixth switch from the left of the switch group SG101 included in the switch group 156 is set to a closed state. As a result, the sixth light receiving element from the left of the light receiving element group PG101 of the light receiving element array 135 is connected to the amplifier AMP101. The path between the light receiving element in the light receiving element group PG101 that is communicating and the amplifier AMP101 used for that communication is indicated by a thick line as the path along which the signal during scanning propagates. In the comparative example, the light receiving element group PG101 including the light receiving element in communication and the amplifier AMP101 cannot be used for scanning. Therefore, the light receiving element group PG102 and the amplifier AMP102 that do not include the light receiving element in communication are used for scanning another communication target. In the comparative example, the switch group is not hierarchical, and the amplifier AMP corresponding to the light receiving element group PG is fixed, so that the communication mode and the scan mode cannot be flexibly switched.

[0087] For example, assume that 64 light receiving elements are assigned to each of 8 amplifier AMPs, with each amplifier AMP handling an angle of 15 degrees. An angle of 15 degrees is 13.2 meters wide at 50 meters away, and 26.3 meters wide at 100 meters away. With this width, two different communication targets may enter the light receiving range of one amplifier AMP. If two different communication targets enter the light receiving range of one amplifier AMP, the spatial light signals from those communication targets will interfere with each other. In order to avoid interference from the same direction, it is necessary to leave an interval of 2 to 3 light receiving elements. In other words, interference can be avoided by placing one amplifier AMP for every 3 to 4 light receiving elements. However, if one amplifier AMP is placed for every 3 to 4 light receiving elements, 16 to 21 amplifier AMPs will be required. Also, in order to accurately detect the direction of the communication target, it is necessary to form a group that includes at least four light receiving elements. However, when configuring the photodetector in groups each including four photodetectors, 64 photodetectors are divided into groups each containing 16, which requires 16 amplifier circuits.

[0088] As in the comparative example, if the amplifier AMP is shared by multiple light receiving elements, the number of circuits can be reduced. However, when any of the paralleled light receiving elements is in use, the amplifier AMP associated with the light receiving element group including that light receiving element cannot be assigned to another scan or communication. Therefore, many light receiving elements cannot be used. In optical space communication, since communication and scanning with multiple communication targets are performed in parallel, it is difficult to realize continuous optical space communication in the configuration of comparative example 1. In contrast, in the method of this embodiment, the number of amplifiers can be optimized while forming a group with an appropriate number of light receiving elements, so that the direction of the communication target can be accurately detected.

[0089] As described above, the light receiving device of this embodiment includes a light receiving element array, a light condenser (ball lens), and a reception control device. The light receiving element array is composed of a plurality of light receiving elements. The light condenser condenses a spatial optical signal toward at least one of the light receiving elements constituting the light receiving element array. The reception control device includes a first processing circuit, a control circuit, a selector, and at least one second processing circuit. The first processing circuit has a switching circuit and an amplifier circuit. The switching circuit includes a plurality of switches SW, a plurality of selection switches SS, and a plurality of changeover switches CS. Each of the plurality of switches SW is connected to each of the plurality of light receiving elements. The selection switch SS is arranged for each group (light receiving element group PG) into which the plurality of light receiving elements are distributed. The changeover switch CS switches the output destination of the selection switch SS for each group. The amplifier circuit is composed of a plurality of amplifiers AMP connected to the output of the switching circuit. The selector is connected to the output of the first processing circuit. The second processing circuit is arranged after the selector. The second processing circuit decodes the signal assigned via the selector. The control circuit controls the switching circuit so as to distribute signals from the multiple light receiving elements to one of the multiple amplifiers AMP. The control circuit controls the selector so as to assign the signal amplified by the amplifier circuit to one of the second processing circuits.

[0090] According to the communication control device of this embodiment, the number of amplifiers can be optimized while forming a group with an appropriate number of light receiving elements, so that continuous optical space communication can be realized at a stable communication speed. In this embodiment, an example in which an optical signal focused by a ball lens is received by a light receiving element array has been described. The method of this embodiment can be applied to receiving an optical signal focused by not only a ball lens but also any concentrator.

[0091] In one aspect of the present embodiment, the output terminals of the multiple switches are integrated for each group. The input terminals of the multiple selection switches are connected to any of the output terminals of the multiple switches integrated for each group. The output terminals of the multiple selection switches are connected to a first terminal of at least one of the multiple changeover switches. The second terminals of the multiple changeover switches are connected to an input terminal of any of the multiple amplifiers. The control circuit controls the open / closed states of the switches, the selection switches, and the changeover switches included in the switching circuit, thereby controlling the connection state between the multiple light receiving elements and the multiple amplifiers. According to this aspect, the connection state between the multiple light receiving elements and the multiple amplifiers can be flexibly controlled by controlling the open / closed states of the multiple switches included in the switching circuit.

[0092] In one aspect of this embodiment, the control circuit sequentially switches between the light receiving elements connected to the amplifiers used to scan the communication target by controlling the open / close states of the switches, selection switches, and changeover switches included in the switching circuit. The control circuit sequentially switches between the light receiving elements connected to the amplifiers used to scan the communication target, thereby scanning the spatial optical signal transmitted from the communication target. According to this aspect, the spatial optical signal transmitted from the communication target can be scanned by controlling the open / close states of the multiple switches included in the switching circuit.

[0093] In one aspect of this embodiment, the control circuit establishes communication with the at least one communication target by closing a switch, a selection switch, and a changeover switch on a path between the light receiving element used for communication with the at least one communication target and the amplifier. According to this aspect, communication with the at least one communication target can be established by establishing a path between the light receiving element used for communication with the at least one communication target and the amplifier.

[0094] In one aspect of this embodiment, the control circuit maintains in a closed state the switches, selection switches, and changeover switches on the path between the light receiving element and the amplifier used for communication with at least one communication target with which communication has been established. The control circuit controls the switching circuit to sequentially switch the light receiving element connected to the amplifier not used for communication, thereby scanning the spatial optical signal transmitted from a communication target other than the communication target currently in communication. According to this aspect, it is possible to scan the other communication target while continuing communication with the communication target.

[0095] In one aspect of this embodiment, the multiple light receiving elements constituting the light receiving element array are assigned to any of the groups constituted by the number of light receiving elements that fall within the light receiving range in which the spatial optical signal transmitted from a single communication target is received. According to this aspect, it is possible to configure the minimum number of amplifiers while grouping with an appropriate number of light receiving elements for each communication target.

[0096] Second Embodiment Next, a communication device according to a second embodiment will be described with reference to the drawings. The communication device of this embodiment has a configuration in which the light receiving device of the first embodiment and a light transmitting device that transmits a spatial light signal are combined. In the following, an example of a communication device equipped with a light transmitting device including a phase modulation type spatial light modulator will be described. Note that the communication device of this embodiment may be equipped with a light transmitting device that includes a light transmitting function other than a phase modulation type spatial light modulator.

[0097] (composition) 18 is a conceptual diagram showing an example of the configuration of the communication device 2 of this embodiment. The communication device 2 includes a light receiving device 200, a control device 250, and a light transmitting device 270. The light receiving device 200 and the light transmitting device 270 transmit and receive spatial optical signals to and from an external communication target. For this reason, the communication device 2 is provided with an opening or window for transmitting and receiving spatial optical signals.

[0098] The light receiving device 200 is a light receiving device of the first embodiment. The light receiving device 200 receives a spatial optical signal transmitted from a communication target (not shown). The light receiving device 200 converts the received spatial optical signal into an electrical signal. The light receiving device 200 outputs the converted electrical signal to the control device 250.

[0099] The control device 250 acquires a signal output from the light receiving device 200. The control device 250 executes a process according to the acquired signal. There is no particular limitation on the process executed by the control device 250. The control device 250 outputs a control signal to the light transmitting device 270 for transmitting an optical signal according to the executed process.

[0100] The light transmitting device 270 receives a control signal from the control device 250. The light transmitting device 270 projects a spatial light signal according to the control signal. The spatial light signal projected from the light transmitting device 270 is received by a communication target (not shown). For example, the light transmitting device 270 includes a phase modulation type spatial light modulator.

[0101] [Transmitting device] Fig. 19 is a conceptual diagram showing an example of the configuration of light transmitting device 270. Light transmitting device 270 has light source 271, spatial light modulator 273, curved mirror 275, and control unit 277. Light source 271, spatial light modulator 273, and curved mirror 275 configure a transmission unit. Fig. 19 is a side view of the internal configuration of light transmitting device 270 as viewed from the lateral direction. Fig. 19 is conceptual and does not accurately represent the positional relationship between the components or the traveling direction of light.

[0102] The light source 271 emits a laser beam in a predetermined wavelength band according to the control of the control unit 277. The wavelength of the laser beam emitted from the light source 271 is not particularly limited and may be selected according to the application. For example, the light source 271 emits a laser beam in a visible or infrared wavelength band. For example, in the case of near infrared rays of 800 to 900 nanometers (nm), the laser class can be increased, so that the sensitivity can be improved by about one order of magnitude compared to other wavelength bands. For example, in the case of infrared rays in a wavelength band of 1.55 micrometers (μm), a high-output laser light source can be used. As a laser light source for infrared rays in a wavelength band of 1.55 μm, an aluminum gallium arsenide phosphide (AlGaAsP)-based laser light source or an indium gallium arsenide (InGaAs)-based laser light source can be used. The longer the wavelength of the laser beam, the larger the diffraction angle can be, and the higher the energy can be set. The light source 271 includes a lens that expands the laser beam according to the size of the modulation unit 2730 of the spatial light modulator 273. The light source 271 emits light 202 that is expanded by a lens. The light 202 emitted from the light source 271 travels toward a modulation section 2730 of the spatial light modulator 273.

[0103] The spatial light modulator 273 has a modulation section 2730 to which the light 202 is irradiated. The light 202 emitted from the light source 271 is irradiated to the modulation section 2730 of the spatial light modulator 273. A pattern (also called a phase image) corresponding to an image displayed by the projection light 205 is set in the modulation section 2730 of the spatial light modulator 273 under the control of the control section 277. The light 202 incident on the modulation section 2730 of the spatial light modulator 273 is modulated according to the pattern set in the modulation section 2730 of the spatial light modulator 273. The modulated light 203 modulated by the modulation section 2730 of the spatial light modulator 273 proceeds toward the reflecting surface 2750 of the curved mirror 275.

[0104] For example, the spatial light modulator 273 is realized by a spatial light modulator using ferroelectric liquid crystal, homogeneous liquid crystal, vertically aligned liquid crystal, or the like. For example, the spatial light modulator 273 can be realized by LCOS (Liquid Crystal on Silicon). The spatial light modulator 273 may also be realized by MEMS (Micro Electro Mechanical System). In the phase modulation type spatial light modulator 273, the energy can be concentrated on the image portion by operating to sequentially switch the location where the projection light 205 is projected. Therefore, when the phase modulation type spatial light modulator 273 is used, if the output of the light source 271 is the same, the image can be displayed brighter than in other methods.

[0105] The modulation section 2730 of the spatial light modulator 273 is divided into a plurality of regions (also called tiling). For example, the modulation section 2730 is divided into rectangular regions (also called tiles) with a desired aspect ratio. A phase image is assigned to each of the plurality of tiles set in the modulation section 2730. Each of the plurality of tiles is composed of a plurality of pixels. A phase image corresponding to the image to be projected is set in each of the plurality of tiles. The phase images set in each of the plurality of tiles may be the same or different.

[0106] A phase image is tiled on each of the tiles assigned to the modulation unit 2730. For example, a pre-generated phase image is set on each of the tiles. When light 202 is irradiated on the modulation unit 2730 with phase images set on the tiles, modulated light 203 that forms an image corresponding to the phase image of each tile is emitted. The more tiles set on the modulation unit 2730, the clearer the image that can be displayed, but the resolution decreases when the number of pixels of each tile decreases. Therefore, the size and number of tiles set on the modulation unit 2730 are set according to the application.

[0107] The curved mirror 275 is a reflecting mirror having a curved reflecting surface 2750. The reflecting surface 2750 of the curved mirror 275 has a curvature according to the projection angle of the projected light 205. The reflecting surface 2750 of the curved mirror 275 may be a curved surface. In the example of FIG. 31, the reflecting surface 2750 of the curved mirror 275 has a shape of a side surface of a cylinder. For example, the reflecting surface 2750 of the curved mirror 275 may be a spherical surface. For example, the reflecting surface 2750 of the curved mirror 275 may be a free-form surface. For example, the reflecting surface 2750 of the curved mirror 275 may have a shape that combines multiple curved surfaces instead of a single curved surface. For example, the reflecting surface 2750 of the curved mirror 275 may have a shape that combines a curved surface and a flat surface.

[0108] The curved mirror 275 is disposed on the optical path of the modulated light 203 with the reflecting surface 2750 facing the modulating section 2730 of the spatial light modulator 273. The modulated light 203 modulated by the modulating section 2730 of the spatial light modulator 273 is irradiated onto the reflecting surface 2750 of the curved mirror 275. The light (projected light 205) reflected by the reflecting surface 2750 of the curved mirror 275 is magnified at a magnification rate according to the curvature of the reflecting surface 2750 and projected. In the case of the example of FIG. 31, the projected light 205 is magnified along the horizontal direction (direction perpendicular to the paper surface of FIG. 31) according to the curvature of the irradiation range of the modulated light 203 on the reflecting surface 2750 of the curved mirror 275. The curved mirror 275 may be omitted. When the curved mirror 275 is omitted, the modulated light 203 modulated by the modulation section 2730 of the spatial light modulator 273 may be projected as it is as the projection light 205 .

[0109] For example, a shield (not shown) may be disposed between the spatial light modulator 273 and the curved mirror 275. In other words, a shield may be disposed on the optical path of the modulated light 203 modulated by the modulation unit 2730 of the spatial light modulator 273. The shield is a frame body that shields unnecessary light components contained in the modulated light 203 and defines the outer edge of the display area of ​​the projection light 205. For example, the shield is an aperture in which a slit-shaped opening is formed in a portion that passes light that forms a desired image. The shield passes light that forms a desired image and shields unnecessary light components. For example, the shield shields zero-order light and ghost images contained in the modulated light 203. Details of the shield will not be described.

[0110] The control unit 277 controls the light source 271 and the spatial light modulator 273. For example, the control unit 277 is realized by a microcomputer including a processor and a memory. The control unit 277 sets a phase image corresponding to the image to be projected in the modulation unit 2730 according to the aspect ratio of the tiling set in the modulation unit 2730 of the spatial light modulator 273. For example, the control unit 277 sets a phase image corresponding to an image according to the purpose such as image display, communication, distance measurement, etc. in the modulation unit 2730. The phase image of the image to be projected may be stored in advance in a storage unit (not shown). There is no particular limitation on the shape or size of the image to be projected.

[0111] The control unit 277 drives the spatial light modulator 273 so that a parameter that determines the difference between the phase of the light 202 irradiated to the modulation unit 2730 of the spatial light modulator 273 and the phase of the modulated light 203 reflected by the modulation unit 2730 changes. The parameter that determines the difference between the phase of the light 202 irradiated to the modulation unit 2730 of the spatial light modulator 273 and the phase of the modulated light 203 reflected by the modulation unit 2730 is, for example, a parameter related to optical characteristics such as a refractive index and an optical path length. For example, the control unit 277 adjusts the refractive index of the modulation unit 2730 by changing a voltage applied to the modulation unit 2730 of the spatial light modulator 273. The phase distribution of the light 202 irradiated to the modulation unit 2730 of the phase modulation type spatial light modulator 273 is modulated according to the optical characteristics of the modulation unit 2730. The method of driving the spatial light modulator 273 by the control unit 277 is determined according to the modulation method of the spatial light modulator 273 .

[0112] The control unit 277 drives the light source 271 in a state where a phase image corresponding to an image to be displayed is set in the modulation unit 2730. As a result, the light 202 emitted from the light source 271 is irradiated onto the modulation unit 2730 of the spatial light modulator 273 in accordance with the timing at which the phase image is set in the modulation unit 2730 of the spatial light modulator 273. The light 202 irradiated onto the modulation unit 2730 of the spatial light modulator 273 is modulated in the modulation unit 2730 of the spatial light modulator 273. The modulated light 203 modulated in the modulation unit 2730 of the spatial light modulator 273 is emitted toward the reflecting surface 2750 of the curved mirror 275.

[0113] For example, the curvature of the reflecting surface 2750 of the curved mirror 275 included in the light transmitting device 270 and the distance between the spatial light modulator 273 and the curved mirror 275 are adjusted to set the projection angle of the projection light 205 to 180 degrees. If two light transmitting devices 270 configured in this way are used, the projection angle of the projection light 205 can be set to 360 degrees. If a part of the modulated light 203 is turned back by a plane mirror or the like inside the light transmitting device 270 and the projection light 205 is configured to be projected in two directions, the projection angle of the projection light 205 can be set to 360 degrees. For example, a configuration is made in which the light transmitting device 270 configured to project the projection light in a 360-degree direction is combined with the light receiver 10-2 (FIG. 16) of the second modified example of the first embodiment. With such a configuration, a communication device that transmits a spatial optical signal in a 360-degree direction and receives a spatial optical signal arriving from a 360-degree direction can be realized.

[0114] [Application example 1] Next, an application example 1 of the communication device 2 of this embodiment will be described with reference to the drawings. Fig. 20 is a conceptual diagram for explaining a communication device 2-1 of this application example. In this application example, a communication network is configured in which multiple communication devices 2-1 are arranged on the tops of poles such as utility poles and street lamps.

[0115] FIG. 20 is a conceptual diagram showing an example of the configuration of the communication device 2-1. The communication device 2-1 includes a light receiving device 200-1, a transmission device 27-1, and a control device (not shown). In FIG. 20, the light receiving circuit and the control device are omitted. The communication device 2-1 has a cylindrical outer shape. The light receiving device 200-1 includes a ball lens 21-1, a light receiving unit 23-1, a substrate 24, a support member 28, and a color filter 29. The ball lens 21-1 is sandwiched by a pair of support members 28 arranged above and below. The top and bottom of the ball lens 21-1 are not used for transmitting and receiving spatial optical signals, so they may be formed in a flat shape so that they can be easily sandwiched by the support member 28. The light receiving unit 23-1 is arranged in a ring shape in accordance with the light collecting area of ​​the ball lens 21-1 so that the spatial optical signal to be received can be received. The light receiving unit 23-1 is formed on the substrate 24. The light receiving unit 23-1 is connected to a control device (not shown) and a transmission device 27-1 by a conductor 280. A color filter 29 is arranged on the side of the cylindrical light receiving device 200-1. The color filter 29 removes unnecessary light and selectively transmits a spatial optical signal used for communication. A pair of support members 28 are arranged on the upper and lower surfaces of the cylindrical light receiving device 200-1. The pair of support members 28 sandwich the upper and lower sides of the ball lens 21-1. The light receiving unit 23-1 formed in an annular shape is arranged on the output side of the ball lens 21-1. The spatial optical signal incident on the ball lens 21-1 through the color filter 29 is focused on the light receiving unit 23-1 by the ball lens 21-1. The control device (not shown) causes the transmission device 27-1 to transmit the spatial optical signal in response to the optical signal received by the light receiving unit 23-1. For example, the transmission device 27-1 can be realized by the configuration of FIG. 19. For example, the transmitting device 27-1 may be configured by combining a plurality of light sources, a spatial light modulator, a curved mirror, and a reflecting mirror so as to transmit a spatial optical signal in a 360-degree direction. In the example of Fig. 20, the transmitting device 27-1 has a slit formed so as to be able to project a spatial optical signal in a 360-degree direction.

[0116] FIG. 21 shows an example of a communication network in which a plurality of communication devices 2-1 arranged on the top of utility poles are arranged. The plurality of communication devices 2-1 transmit and receive spatial optical signals to and from each other. There are few obstacles on the top of poles such as utility poles and street lamps. Therefore, the top of poles such as utility poles and street lamps are suitable for installing the communication devices 2-1. Furthermore, if the communication devices 2-1 are installed at the same height on the top of the poles, the direction of arrival of the spatial optical signals is limited to the horizontal direction, so that the light receiving area of ​​the light receiving unit 23-1 constituting the light receiving device 200-1 can be reduced and the device can be simplified. A pair of communication devices 2-1 that exchange communication are arranged so that at least one communication device 2-1 receives the spatial optical signal transmitted from the other communication device 2-1. A pair of communication devices 2-1 may be arranged so that they transmit and receive spatial optical signals to and from each other. When a communication network of spatial optical signals is configured with a plurality of communication devices 2-1, a communication device 2-1 located in the middle may be arranged so as to relay a spatial optical signal transmitted from another communication device 2-1 to another communication device 2-1.

[0117] According to this application example, communication using spatial optical signals is possible between a plurality of communication devices 2-1 installed on different poles. For example, in response to communication between the communication devices 2-1 installed on different poles, communication by wireless communication may be performed between the communication device 2-1 and a wireless device or base station installed in an automobile, a house, or the like. For example, the communication device 2-1 may be configured to be connected to the Internet via a communication cable or the like installed on the pole.

[0118] As described above, the communication device of the present embodiment includes a light receiving device, a light transmitting device, and a control device. The light transmitting device transmits a spatial optical signal. The control device acquires a signal based on the spatial optical signal received by the light receiving device. The control device executes processing according to the acquired signal. The control device causes the light transmitting device to transmit the spatial optical signal according to the executed processing. The light receiving device includes a light receiving element array, a light condenser (ball lens), and a reception control device. The light receiving element array is composed of a plurality of light receiving elements. The light condenser condenses the spatial optical signal toward at least one of the light receiving elements constituting the light receiving element array. The reception control device includes a first processing circuit, a control circuit, a selector, and at least one second processing circuit. The first processing circuit has a switching circuit and an amplifier circuit. The switching circuit includes a plurality of switches SW, a plurality of selection switches SS, and a plurality of changeover switches CS. Each of the plurality of switches SW is connected to each of the plurality of light receiving elements. The selection switch SS is arranged for each group (light receiving element group PG) into which the plurality of light receiving elements are distributed. The changeover switch CS switches the output destination of the selection switch SS for each group. The amplification circuit is composed of multiple amplifiers AMP connected to the output of the switching circuit. The selector is connected to the output of the first processing circuit. The second processing circuit is arranged after the selector. The second processing circuit decodes the signal assigned via the selector. The control circuit controls the switching circuit to distribute signals from the multiple light receiving elements to one of the multiple amplifiers AMP. The control circuit controls the selector to assign the signal amplified by the amplification circuit to one of the second processing circuits.

[0119] According to the communication control device of this embodiment, it is possible to optimize the number of amplifiers while configuring groups with an appropriate number of light receiving elements, thereby realizing continuous free space optical communication at a stable communication speed. (Third embodiment) Next, a communication control device of a third embodiment will be described with reference to the drawings. The communication control device of this embodiment has a simplified configuration of the communication control device of the first embodiment. FIG. 22 is a conceptual diagram showing an example of the configuration of a communication control device 34 of this embodiment. The communication control device 34 includes a first processing circuit 35, a control circuit 37, a selector 38, and at least one second processing circuit 39. FIG. 22 also illustrates a light receiving element array 33 connected to the communication control device 34. The light receiving element array includes a plurality of light receiving elements 331.

[0120] The first processing circuit 35 has a switching circuit 350 and an amplifier circuit 353. The switching circuit 350 includes a plurality of switches SW, a plurality of selection switches SS, and a plurality of changeover switches CS. Each of the plurality of switches SW is connected to each of the plurality of light receiving elements 131. The selection switch SS is arranged for each group (light receiving element group PG) into which the plurality of light receiving elements 131 are distributed. The changeover switch CS switches the output destination of the selection switch SS for each group. The amplifier circuit 353 is composed of a plurality of amplifiers AMP connected to the output of the switching circuit 350. The selector 38 is connected to the output of the first processing circuit 35. The second processing circuit 39 is arranged in the rear stage of the selector 38. The second processing circuit 39 decodes the signal assigned via the selector 38. The control circuit 37 controls the switching circuit 350 to distribute the signal from the plurality of light receiving elements 131 to one of the plurality of amplifiers AMP. The control circuit 37 controls the selector 38 to assign the signal amplified by the amplifier circuit 353 to one of the second processing circuits 39.

[0121] As described above, according to the communication control device of this embodiment, it is possible to optimize the number of amplifiers while forming groups with an appropriate number of photodetectors, thereby realizing continuous optical space communication at a stable communication speed.

[0122] (Hardware) Here, a hardware configuration for executing the control and processing according to each embodiment of the present disclosure will be described using an information processing device 90 in Fig. 23 as an example. Note that the information processing device 90 in Fig. 23 is an example of a configuration for executing the control and processing according to each embodiment, and does not limit the scope of the present disclosure.

[0123] As shown in Fig. 23, an information processing device 90 includes a processor 91, a main storage device 92, an auxiliary storage device 93, an input / output interface 95, and a communication interface 96. In Fig. 23, the interface is abbreviated as I / F (Interface). The processor 91, the main storage device 92, the auxiliary storage device 93, the input / output interface 95, and the communication interface 96 are connected to each other via a bus 98 so as to be able to communicate data with each other. In addition, the processor 91, the main storage device 92, the auxiliary storage device 93, and the input / output interface 95 are connected to a network such as the Internet or an intranet via the communication interface 96.

[0124] The processor 91 loads a program stored in the auxiliary storage device 93 or the like into the main storage device 92. The processor 91 executes the program loaded into the main storage device 92. In this embodiment, a software program installed in the information processing device 90 may be used. The processor 91 executes the control and processing according to this embodiment.

[0125] The main memory device 92 has an area in which a program is loaded. The processor 91 loads a program stored in the auxiliary memory device 93 or the like in the main memory device 92. The main memory device 92 is realized by a volatile memory such as a dynamic random access memory (DRAM). Furthermore, a non-volatile memory such as a magnetoresistive random access memory (MRAM) may be configured / added to the main memory device 92.

[0126] The auxiliary storage device 93 stores various data such as programs. The auxiliary storage device 93 is realized by a local disk such as a hard disk or a flash memory. Note that it is also possible to configure the main storage device 92 to store various data and omit the auxiliary storage device 93.

[0127] The input / output interface 95 is an interface for connecting the information processing device 90 to peripheral devices based on standards and specifications. The communication interface 96 is an interface for connecting to external systems and devices through a network such as the Internet or an intranet based on standards and specifications. The input / output interface 95 and the communication interface 96 may be a common interface for connecting to external devices.

[0128] Input devices such as a keyboard, a mouse, and a touch panel may be connected to the information processing device 90 as necessary. These input devices are used to input information and settings. When a touch panel is used as an input device, the display screen of the display device may also serve as an interface for the input device. Data communication between the processor 91 and the input devices may be mediated by an input / output interface 95.

[0129] The information processing device 90 may be equipped with a display device for displaying information. When the display device is equipped, the information processing device 90 is preferably equipped with a display control device (not shown) for controlling the display of the display device. The display device may be connected to the information processing device 90 via the input / output interface 95.

[0130] The information processing device 90 may also be provided with a drive device. The drive device mediates between the processor 91 and a recording medium (program recording medium) for reading data and programs from the recording medium, writing the processing results of the information processing device 90 to the recording medium, and the like. The drive device may be connected to the information processing device 90 via an input / output interface 95.

[0131] The above is an example of a hardware configuration for enabling the control and processing according to each embodiment of the present invention. The hardware configuration in FIG. 23 is an example of a hardware configuration for executing the control and processing according to each embodiment, and does not limit the scope of the present invention. In addition, a program for causing a computer to execute the control and processing according to each embodiment is also included in the scope of the present invention. Furthermore, a program recording medium on which a program according to each embodiment is recorded is also included in the scope of the present invention. The recording medium can be realized, for example, by an optical recording medium such as a CD (Compact Disc) or a DVD (Digital Versatile Disc). The recording medium may be realized by a semiconductor recording medium such as a USB (Universal Serial Bus) memory or an SD (Secure Digital) card. In addition, the recording medium may be realized by a magnetic recording medium such as a flexible disk or other recording medium. When a program executed by a processor is recorded on a recording medium, the recording medium corresponds to a program recording medium.

[0132] The components of each embodiment may be combined in any manner. Furthermore, the components of each embodiment may be realized by software or by a circuit.

[0133] Although the present invention has been described above with reference to the embodiments, the present invention is not limited to the above-mentioned embodiments. Various modifications that can be understood by those skilled in the art can be made to the configuration and details of the present invention within the scope of the present invention. [Explanation of symbols]

[0134] 2. Communications equipment 10 Photodetector 11 Ball Lens 13 Photodetector array 14 Receiving control device 15 First processing circuit 17 Control circuit 18 Selectors 19 Second processing circuit 100 receiver 130 Substrate 131 Photodetector 150 Switching Circuits 151 First switch circuit 152 Second switch circuit 153 Amplification circuit 200 Photodetector 250 Control device 270 Light transmitting device 271 Light source 273 Spatial Light Modulator 275 Curved Mirror

Claims

1. a first processing circuit including a switching circuit including a switch connected to each of a plurality of light receiving elements, a selection switch arranged for each group into which the plurality of light receiving elements are distributed, and a changeover switch for switching an output destination of the selection switch for each group, and an amplification circuit including a plurality of amplifiers connected to an output of the switching circuit; a selector connected to an output of the first processing circuit; at least one second processing circuit arranged downstream of the selector and configured to decode a signal assigned via the selector; A receiving control device comprising: a control circuit that controls the switching circuit to distribute signals from a plurality of the light receiving elements to one of a plurality of the amplifiers, and controls the selector to assign the signal amplified by the amplifier circuit to one of the second processing circuits.

2. The output terminals of the plurality of switches are The groups are integrated together, The input terminals of the plurality of selection switches are connected to any one of the output terminals of the plurality of switches integrated for each group, The output terminals of the plurality of selection switches are A first terminal of at least one of the plurality of changeover switches is connected to the first terminal of the first terminal of the changeover switch. The second terminals of the plurality of changeover switches are A power amplifier is connected to an input terminal of any one of the plurality of amplifiers, The control circuit includes:

2. The reception control device according to claim 1, wherein the connection state between the plurality of light receiving elements and the plurality of amplifiers is controlled by controlling the open / closed states of the switch, the selection switch, and the changeover switch included in the switching circuit.

3. The control circuit includes:

3. The receiving control device according to claim 2, wherein the light receiving element connected to the amplifier used for scanning a communication target is sequentially switched by controlling the open / closed states of the switch, the selection switch, and the changeover switch included in the switching circuit, thereby scanning the spatial light signal transmitted from the communication target.

4. The control circuit includes: A receiving control device as described in claim 3, which establishes communication with at least one of the communication targets by closing the switch, the selection switch, and the changeover switch on the path between the photodetector and the amplifier used for communication with at least one of the communication targets.

5. The control circuit includes:

5. The reception control device according to claim 4, wherein the switching circuit is controlled to sequentially switch the light receiving element connected to the amplifier not used for communication while maintaining the switch, the selection switch, and the changeover switch on the path between the light receiving element and the amplifier used for communication with at least one of the communication targets with which communication has been established in a closed state, thereby scanning spatial optical signals transmitted from a communication target other than the communication target with which communication has been established.

6. A reception control device according to any one of claims 1 to 5, a light receiving element array including a plurality of light receiving elements; a concentrator that focuses a spatial optical signal toward at least one of the light receiving elements constituting the light receiving element array.

7. The light receiving device according to claim 6, wherein the plurality of light receiving elements constituting the light receiving element array are assigned to any one of groups constituted by a number of light receiving elements that fall within a light receiving range in which a spatial optical signal transmitted from a single communication target is received.

8. A light receiving device according to claim 6 or 7, a light transmitting device for transmitting a spatial optical signal; A communication device comprising: a control device that acquires a signal based on the spatial light signal received by the light receiving device, performs processing according to the acquired signal, and causes the light transmitting device to transmit a spatial light signal according to the processing performed.

9. The control circuit a first processing circuit including a switching circuit including a first switch circuit configured with a switch connected to each of a plurality of light receiving elements, a second switch circuit configured to switch an output destination for each group formed by integrating some of the plurality of switches included in the first switch circuit, and an amplification circuit including a plurality of amplifiers connected to an output of the switching circuit, by controlling the first processing circuit to assign signals from a plurality of the light receiving elements to any of a plurality of amplifiers connected to an output of the switching circuit; A reception control method for allocating the signal amplified by the amplifier circuit to one of a plurality of second processing circuits that decode the signal output from the first processing circuit by controlling selectors connected to the outputs of a plurality of the amplifiers.

10. a process of allocating signals from the plurality of light receiving elements to any of the plurality of amplifiers connected to the output of the switching circuit by controlling a first processing circuit having a switching circuit including a first switch circuit configured with a switch connected to each of the plurality of light receiving elements, a second switch circuit configured to switch an output destination for each group formed by integrating some of the plurality of switches included in the first switch circuit, and an amplification circuit including a plurality of amplifiers connected to the output of the switching circuit; and a process of controlling selectors connected to the outputs of the plurality of amplifiers to assign the signal amplified by the amplifier circuit to one of a plurality of second processing circuits that decode the signal output from the first processing circuit.

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