Receiving device, communication device, and communication system

Abstract

In order to uniformly receive optical signals arriving from various directions despite having a simple configuration, this reception device comprises: a light-receiving-element array configured from a ball lens for collecting optical signals propagating through a space and a plurality of light-receiving elements for receiving the optical signals collected by the ball lens, the light-receiving-element array outputting a signal derived from the optical signals received by the plurality of light-receiving elements; and a reception circuit for decoding the signal outputted from the light-receiving-element array.

Description

[Technical field]

[0001] The present disclosure relates to a receiving device or the like that receives 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 imaging device using a spherical lens. The device in Patent Document 1 has a spherical lens and an imaging means. The imaging means has a light receiving surface that is curved along the curved image surface of the spherical lens. The spherical lens forms an object image on the light receiving surface of the imaging means.

[0004] Patent Document 2 discloses an optical receiving device that converts an optical signal into an electrical signal. The device in Patent Document 2 is composed of a condenser lens such as a spherical lens, and a light receiving element having multiple light receiving surfaces. Each of the multiple light receiving surfaces of the light receiving element is configured so that the area increases from the center to the periphery in accordance with the size of the light spot formed by the condenser lens. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 63-096616 [Patent Document 2] Japanese Patent Application Laid-Open No. 63-151232 Summary of the Invention [Problem to be solved by the invention]

[0006] According to the device of Patent Document 1, by using a spherical lens, it is possible to realize a wide angle of view while suppressing the decrease in peripheral light amount. The device of Patent Document 1 uses an imaging element such as a CCD (Charge Coupled Device) with a curved light receiving surface. Therefore, the device of Patent Document 1 had to adopt a special imaging element with a curved light receiving surface.

[0007] According to the device of Patent Document 2, a light receiving system with an improved angle of view can be realized by combining a wide-angle lens such as a spherical lens with a light receiving element divided on a plane. In the device of Patent Document 2, the area of ​​the light receiving surface is changed according to the angle of incidence of the optical signal. Therefore, the device of Patent Document 2 has a problem that when receiving spatial optical signals arriving from various directions, differences in the received light intensity occur depending on the direction of arrival of the spatial optical signal.

[0008] An object of the present disclosure is to provide a receiving device etc. that has a simple configuration and is capable of evenly receiving optical signals arriving from various directions. [Means for solving the problem]

[0009] A receiving device according to one aspect of the present disclosure includes a ball lens that focuses an optical signal propagating through space, a photodetector array that is composed of a plurality of photodetectors that receive the optical signal focused by the ball lens and outputs a signal derived from the optical signal received by the plurality of photodetectors, and a receiving circuit that decodes the signal output from the photodetector array. Effect of the Invention

[0010] According to the present disclosure, it is possible to provide a receiving device or the like that has a simple configuration and is capable of evenly receiving optical signals arriving from various directions. [Brief description of the drawings]

[0011] [Figure 1]1 is a conceptual diagram illustrating an example of a configuration of a receiving device according to a first embodiment. [Diagram 2] FIG. 2 is a conceptual diagram for explaining an example of light focusing by a ball lens in the receiving device according to the first embodiment. [Diagram 3] 3 is a conceptual diagram showing an example of the positional relationship between a ball lens and a light receiving element array in the receiving device according to the first embodiment. FIG. [Figure 4] 3 is a conceptual diagram showing how an optical signal collected by a ball lens of the receiving device according to the first embodiment is received by a light receiving element. FIG. [Diagram 5] FIG. 2 is a conceptual diagram showing an example of reception of a spatial optical signal by a receiving device according to the first embodiment. [Figure 6] 4 is a conceptual diagram showing another example of reception of a spatial optical signal by the receiving device according to the first embodiment. FIG. [Figure 7] 2 is a block diagram showing an example of a configuration of a receiving circuit of a receiving device according to the first embodiment. FIG. [Figure 8] FIG. 11 is a conceptual diagram for explaining a light receiver according to a modified example of the first embodiment. [Figure 9] FIG. 11 is a conceptual diagram for explaining a light receiver according to another modified example of the first embodiment. [Figure 10] FIG. 11 is a conceptual diagram illustrating an example of the configuration of a receiving device according to a second embodiment. [Figure 11] FIG. 11 is a conceptual diagram illustrating an example of the configuration of a receiving device according to a second embodiment. [Figure 12] 13 is a conceptual diagram for explaining a light receiving range of a spatial optical signal that can be received by a ball lens of a receiving device according to a second embodiment. FIG. [Figure 13] 10 is a conceptual diagram showing an example of the positional relationship between a ball lens and a light receiving element array in a receiving device according to a second embodiment. FIG. [Figure 14] FIG. 13 is a conceptual diagram illustrating an example of the configuration of a receiving device according to a third embodiment. [Figure 15] 13 is a conceptual diagram showing an example of the positional relationship between an optical element and a light receiving element array of a receiving device according to a third embodiment. FIG. [Figure 16]13 is a conceptual diagram showing how an optical signal guided by an optical element of a receiving device according to a third embodiment is received by a light receiving element. FIG. [Figure 17] FIG. 13 is a conceptual diagram showing an example of the positional relationship between an optical element and a light receiving element array in a receiving device according to a modified example of the third embodiment. [Figure 18] FIG. 13 is a conceptual diagram illustrating an example of the configuration of a receiving device according to a fourth embodiment. [Figure 19] 13 is a conceptual diagram showing an example of the positional relationship between an optical element and a light receiving element array of a receiving device according to a fourth embodiment. FIG. [Figure 20] 13 is a conceptual diagram showing how an optical signal guided by an optical element of a receiving device according to a fourth embodiment is received by a light receiving element. FIG. [Figure 21] FIG. 13 is a conceptual diagram showing an example of the positional relationship between an optical element and a light receiving element array in a receiving device according to a modified example of the fourth embodiment. [Figure 22] FIG. 13 is a conceptual diagram showing an example of the configuration of a receiving device according to a fifth embodiment. [Figure 23] FIG. 13 is a conceptual diagram showing an example of the positional relationship between an optical element and a light receiving element array in a receiving device according to a fifth embodiment. [Figure 24] 13 is a conceptual diagram showing how an optical signal guided by an optical element of a receiving device according to a fifth embodiment is received by a light receiving element. FIG. [Diagram 25] FIG. 13 is a conceptual diagram showing an example of the positional relationship between an optical element and a light receiving element array in a receiving device according to a modified example of the fifth embodiment. [Figure 26] FIG. 13 is a conceptual diagram showing an example of the configuration of a receiving device according to a sixth embodiment. [Figure 27] FIG. 13 is a conceptual diagram showing an example of the configuration of a light receiving element array of a receiving device according to a sixth embodiment. [Figure 28] FIG. 13 is a conceptual diagram showing an example of reception of a spatial optical signal by a receiving device according to a sixth embodiment. [Figure 29] FIG. 13 is a conceptual diagram showing another example of reception of a spatial optical signal by the receiving device according to the sixth embodiment. [Diagram 30]FIG. 13 is a block diagram showing an example of the configuration of a communication device according to a seventh embodiment. [Diagram 31] FIG. 13 is a conceptual diagram illustrating an example of the configuration of a transmission device of a communication device according to a seventh embodiment. [Diagram 32] FIG. 13 is a conceptual diagram illustrating an example of a communication system including a communication device according to a seventh embodiment. [Diagram 33] FIG. 13 is a conceptual diagram illustrating an example of the configuration of a photoreceiver included in a communication system including a communication device according to a seventh embodiment. [Diagram 34] FIG. 13 is a conceptual diagram showing another example of the configuration of the optical receiver included in the communication system including the communication device according to the seventh embodiment. [Diagram 35] FIG. 13 is a conceptual diagram showing an example of reception of a spatial optical signal by a photoreceiver included in a communication system configured by a communication device according to a seventh embodiment. [Diagram 36] FIG. 13 is a conceptual diagram showing another example of reception of a spatial optical signal by a photoreceiver included in a communication system configured by a communication device according to the seventh embodiment. [Figure 37] FIG. 13 is a conceptual diagram for explaining application example 1 of the seventh embodiment. [Figure 38] FIG. 23 is a conceptual diagram for explaining transmission and reception of a spatial optical signal in application example 1 of the seventh embodiment. [Figure 39] FIG. 13 is a conceptual diagram for explaining application example 2 of the seventh embodiment. [Diagram 40] FIG. 13 is a conceptual diagram showing an example of the configuration of a receiving device according to an eighth embodiment. [Diagram 41] FIG. 2 is a block diagram showing an example of a hardware configuration for implementing 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, 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 receiving device according to a first embodiment will be described with reference to the drawings. The 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 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 receiving device 1 of this embodiment. The receiving device 1 includes a ball lens 11, a light receiving element array 13, and a receiving circuit 15. The ball lens 11 and the light receiving element array 13 constitute a light receiver 10. FIG. 1 is a plan view of the light receiver 10 as viewed from above. 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 the trajectory of light focused by ball lens 11. The example in FIG. 2 shows how light irradiated from light source 110, which emits parallel light, toward ball lens 11 is refracted by ball lens 11. Light that enters ball lens 11 is refracted when entering the inside of ball lens 11. Light traveling inside ball lens 11 is refracted again when it is emitted to the outside of ball lens 11. Most of the light refracted by ball lens 11 is focused in the light-focusing region. On the other hand, light that enters from the periphery of ball lens 11 is emitted in a direction away from the light-focusing region when it is emitted 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, the ball lens 11 can be made of a material such as glass, crystal, or resin that transmits / refracts light in the visible region. 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), the ball lens 11 can be made of a material such as silicon in addition to glass, crystal, or resin. When the spatial optical signal is light in the infrared region (hereinafter also referred to as infrared rays), a material that transmits infrared rays is used for ball lens 11. For example, when the spatial optical signal is infrared, silicon, germanium, or a chalcogenide-based material can be used for ball lens 11. There are no limitations on the material of ball lens 11 as long as it can transmit / refract light in the wavelength region of the spatial optical signal. The material of ball lens 11 may be selected appropriately depending on the desired refractive index and application.

[0019] FIG. 3 is a perspective view of the optical receiver 10 composed of the ball lens 11 and the light receiving element array 13. FIG. 3 is a perspective view of the optical receiver 10 as viewed from an obliquely upward position on the incident surface side. FIG. 4 is a cross-sectional view of a part of the optical receiver 10 composed of the ball lens 11 and the light receiving element array 13. FIG. 4 shows an example in which the light receiving element 131 is arranged on the arc-shaped substrate 130. FIG. 4 shows the trajectory of light collected by the ball lens 11. The optical signal collected by the ball lens 11 in the light collecting region where the light receiving element array 13 is arranged is received by one of the light receiving elements 131 constituting the light receiving element array 13. Note that the optical signal that is not received by the light receiving portion 132 of the light receiving element 131 is not received by the light receiving element 131.

[0020] 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 so that the light receiving section 132 faces the emission surface of the ball lens 11. Each of the plurality of light receiving elements 131 is disposed so that the light receiving section 132 is located in 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 located in the light collecting region. 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).

[0021] FIG. 5 is a conceptual diagram showing an example in which the receiving device 1 receives a spatial optical signal arriving from one direction. FIG. 6 is a conceptual diagram showing an example in which the receiving device 1 receives a spatial optical signal arriving from two directions. Since the ball lens 11 is a sphere, the receiving device 1 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 plane formed by the arc of the light receiving element array 13 is set parallel to the horizontal plane, the receiving device 1 is likely to receive spatial optical signals arriving in the horizontal direction from about the same height. For example, when the plane formed by the arc of the light receiving element array 13 is set perpendicular to the horizontal plane, the receiving device 1 is likely to receive spatial optical signals arriving from any height in the same manner.

[0022] 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 in a wavelength region of, for example, 1.5 μm (micrometer). Note that the wavelength region of light to which the light receiving element 131 is sensitive is not limited to the 1.5 μm region. The wavelength region of 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 region of light received by the light receiving element 131 may be set to, for example, a 0.8 μm region, a 1.55 μm region, or a 2.2 μm region. The wavelength region of light received by the light receiving element 131 may be, for example, a 0.8 to 1 μm region. A shorter wavelength region 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.

[0023] 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.

[0024] 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 receiving circuit 15. Although only one line (path) between the light receiving element array 13 and the receiving circuit 15 is illustrated in FIG. 1, the light receiving element array 13 and the receiving circuit 15 may be 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 receiving circuit 15. For example, the light receiving elements 131 constituting the light receiving element array 13 may be configured to be connected to the receiving circuit 15 in groups of several of the light receiving elements 131 constituting the light receiving element array 13.

[0025] The receiving circuit 15 acquires a signal output from each of the multiple light receiving elements 131. The receiving circuit 15 amplifies the signal from each of the multiple light receiving elements 131. The receiving circuit 15 decodes the amplified signal and analyzes the signal from the communication target. For example, the receiving circuit 15 is configured to analyze the signals from each of the multiple light receiving elements 131 collectively. When the signals from each of the multiple light receiving elements 131 are analyzed collectively, a single-channel receiving device 1 that communicates with a single communication target can be realized. For example, the receiving circuit 15 is configured to analyze the signals from each of the multiple light receiving elements 131 individually. When the signals from each of the multiple light receiving elements 131 are analyzed individually, a multi-channel receiving device 1 that communicates with multiple communication targets simultaneously can be realized. The signal decoded by the receiving circuit 15 is used for any purpose. There is no particular limitation on the use of the signal decoded by the receiving circuit 15.

[0026] [Receiving circuit] Next, an example of a detailed configuration of the receiving circuit 15 included in the receiving device 1 will be described with reference to the drawings. Fig. 7 is a block diagram showing an example of the configuration of the receiving circuit 15. 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 receiving circuit 15 and does not limit the configuration of the receiving circuit 15.

[0027] The receiving circuit 15 has a plurality of first processing circuits 151-1 to M, a control circuit 152, a selector 153, and a plurality of second processing circuits 155-1 to N (M and N are natural numbers). The first processing circuit 151 is associated with any one of the plurality of light receiving elements 131-1 to M. The first processing circuit 151 may be configured for each group of the plurality of light receiving elements 131 included in the plurality of light receiving elements 131-1 to M.

[0028] For example, the first processing circuit 151 includes a high-pass filter (not shown). 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 installed in front of the light receiving section of the light receiving element 131.

[0029] For example, the first processing circuit 151 includes an amplifier (not shown). The amplifier acquires the signal output from the high-pass filter. The amplifier amplifies the acquired signal. There is no particular limitation on the amplification factor of the signal by the amplifier.

[0030] For example, the first processing circuit 151 includes an output monitor (not shown). The output monitor monitors the output value of the amplifier. The output monitor outputs to the selector 153 a signal that exceeds a predetermined output value among the signals amplified by the amplifier. Among the signals output to the selector 153, a signal to be received is assigned to one of the multiple second processing circuits 155-1 to N according to the control of the control circuit 152. 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 155.

[0031] For example, the first processing circuit 151 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 152. 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 over a period of, for example, several milliseconds to several tens of milliseconds.

[0032] The control circuit 152 acquires signals output from each of the multiple first processing circuits 151-1 to M. In other words, the control circuit 152 acquires signals derived from optical signals received by each of the multiple light receiving elements 131-1 to M. For example, the control circuit 152 compares the read values ​​of signals from multiple adjacent light receiving elements 131. Depending on the comparison result, the control circuit 152 selects the light receiving element 131 having the maximum signal strength. The control circuit 152 controls the selector 153 to assign the signal derived from the selected light receiving element 131 to any of the multiple second processing circuits 155-1 to N.

[0033] When the position of the communication target is specified in advance, the process of estimating the arrival direction of the spatial optical signal is not performed, and the signal output from the light receiving elements 131-1 to M is output to any one of the second processing circuits 155 set in advance. On the other hand, when the position of the communication target is not specified in advance, the second processing circuit 155 to which the signal output from the light receiving elements 131-1 to M is output is selected. For example, the control circuit 152 can estimate the arrival direction of the spatial optical signal by selecting the light receiving element 131. That is, the control circuit 152 selecting the light receiving element 131 corresponds to identifying the communication device that is the transmission source of the spatial optical signal. Also, the control circuit 152 assigning the signal from the light receiving element 131 selected by the control circuit 152 to any one of the multiple 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. That is, the control circuit 152 can identify the communication device that is the transmission source of the optical signal (spatial optical signal) based on the optical signal received by the multiple light receiving elements 131-1 to M.

[0034] Signals amplified by the amplifiers included in each of the multiple first processing circuits 151-1 to M are input to the selector 153. The selector 153 outputs signals to be received among the input signals to one of the multiple second processing circuits 155-1 to N in accordance with the control of the control circuit 152. Signals not to be received are not output from the selector 153.

[0035] A signal from any one of the light receiving elements 131-1 to N assigned by the control circuit 152 is input to the second processing circuits 155-1 to N. Each of the second processing circuits 155-1 to N decodes the input signal. Each of the second processing circuits 155-1 to 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).

[0036] A signal originating from the light receiving element 131 selected by the control circuit 152 is selected by the selector 153, so that one second processing circuit 155 is assigned to one communication target. That is, the control circuit 152 assigns signals originating from spatial optical signals from multiple communication targets, which are received by the multiple light receiving elements 131-1 to M, to any one of the multiple second processing circuits 155-1 to N. This enables the receiving device 1 to simultaneously read signals originating from spatial optical signals from multiple communication targets in separate channels. For example, in order to simultaneously communicate with multiple communication targets, the spatial optical signals from multiple communication targets may be read in a single channel in a time-division manner. In the method of this embodiment, the spatial optical signals from multiple communication targets are simultaneously read in multiple channels, so that the transmission speed is faster than when a single channel is used.

[0037] 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.

[0038] [Variation 1] Next, a modified example (modified example 1) according to this embodiment will be described with reference to the drawings. FIG. 8 is a conceptual diagram showing an example of the configuration of a light receiver 10-1 of this modified example. FIG. 8 is a plan view of the light receiver 10-1 viewed from above. The light receiver 10-1 of this modified example is composed of a ball lens 11 and a plurality of light receiving element arrays 13 (13A, 13B, 13C). FIG. 8 shows an example in which there are three light receiving element arrays 13, but the number of light receiving element arrays 13 is not particularly limited.

[0039] The optical receiver 10-1 of this modification is suitable for cases where the direction of arrival of the spatial optical signal is limited. When the direction of arrival of the spatial optical signal is limited, there will be an area where the spatial optical signal is not received. In this modification, the photodetector array 13 is arranged in accordance with the arrival range of the spatial optical signal. Note that instead of using multiple photodetector arrays 13, multiple photodetectors 131 may be arranged on the same substrate in accordance with the arrival range of the spatial optical signal.

[0040] The light receiving element array 13A is arranged in correspondence with the arrival range of the spatial light signal A. The light receiving element array 13A receives spatial light signals arriving from the arrival range of the spatial light signal A. The light receiving element array 13B is arranged in correspondence with the arrival range of the spatial light signal B. The light receiving element array 13B receives spatial light signals arriving from the arrival range of the spatial light signal B. The light receiving element array 13C is arranged in correspondence with the arrival range of the spatial light signal C. The light receiving element array 13C receives spatial light signals arriving from the arrival range of the spatial light signal C.

[0041] When the direction of the communication target is specified, the circuit scale can be reduced by omitting the light receiving elements 131 in the portion where the spatial optical signal does not arrive. Furthermore, if the number of light receiving elements 131 is reduced, the cost of the device can be reduced. That is, according to this modification, the circuit scale can be reduced and the cost can be reduced.

[0042] [Modification 2] Next, another modified example (modified example 2) according to the present embodiment will be described with reference to the drawings. FIG. 9 is a conceptual diagram showing an example of the configuration of the optical receiver 10-2 of this modified example. FIG. 9 is a perspective view of the optical receiver 10-2 viewed from an obliquely upward viewpoint on the incident surface side. The optical receiver 10-2 of this modified example is configured by a ball lens 11 and a light receiving element array 13-2. The light receiving element array 13-2 has a structure in which a plurality of light receiving element arrays 13 are stacked in the short side direction. Each of the plurality of light receiving element arrays 13 is disposed in the light collecting region of the ball lens 11. That is, the light receiving element array 13-2 includes light receiving elements 131 arranged in a two-dimensional array on the curved surface of the light receiving element array 13-2 formed in accordance with the light collecting region of the ball lens 11. FIG. 9 shows an example in which three light receiving element arrays 13 are stacked to configure the light receiving element array 13-2, but there is no particular limitation on the number of light receiving element arrays 13 that configure the light receiving element array 13-2.

[0043] Even if the direction of arrival of the spatial optical signal is slightly shifted in the direction of the short side of the photoreceptor array 13-2, the photoreceiver 10-2 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 with respect to the plane including the arc of the photoreceptor array 13-2, the signal light originating from the spatial optical signal can be received by the multiple photoreceptor arrays 13 included in the photoreceptor array 13-2.

[0044] If the direction of arrival of the spatial optical signal is not limited to within the same plane, it may be impossible to communicate with the desired communication target unless it is possible to receive the spatial optical signal arriving three-dimensionally at ball lens 11. In this modification, by using light-receiving element array 13-2 in which multiple light-receiving elements 131 are arranged in a two-dimensional array, the light-receiving range of the spatial optical signal can be expanded compared to light-receiving element array 13.

[0045] As described above, the receiving device of this embodiment includes a ball lens, a light receiving element array, and a receiving circuit. The ball lens focuses optical signals propagating through space. The light receiving element array is composed of a plurality of light receiving elements arranged in an arc shape along the circumferential direction of the ball lens in the focusing region of the ball lens. The light receiving element array outputs a signal derived from the optical signals received by the plurality of light receiving elements. The receiving circuit decodes the signal output from the light receiving element array.

[0046] The receiving device of this embodiment receives optical signals focused by a ball lens using multiple receiving elements arranged in an arc shape in the focusing area of ​​the ball lens. The ball lens focuses optical signals arriving from any direction in the surrounding focusing area. Therefore, this embodiment has a simple configuration and can evenly receive optical signals arriving from various directions.

[0047] The receiving device according to one aspect of the present embodiment includes at least one light receiving element array arranged in accordance with the direction of arrival of the spatial optical signal. In this aspect, the light receiving element array is arranged at a position where the optical signal is focused, and the light receiving element array is not arranged at a position where the optical signal is not focused. Therefore, according to this aspect, unnecessary light receiving elements can be omitted.

[0048] In one aspect of the present embodiment, the light receiving element array is composed of a plurality of light receiving elements arranged in a two-dimensional array along the circumferential direction of the ball lens in the light collecting region of the ball lens. According to this aspect, the light receiving angle of the spatial optical signal can be expanded in the direction perpendicular to the arrangement direction of the plurality of light receiving elements.

[0049] Second embodiment Next, a receiving device according to a second embodiment will be described with reference to the drawings. The receiving device of this embodiment differs from the receiving device of the first embodiment in that a receiving element array formed in a ring shape is arranged so as to surround the periphery of a ball lens.

[0050] (composition) FIG. 10 is a conceptual diagram showing an example of the configuration of the receiving device 2 of this embodiment. The receiving device 2 includes a ball lens 21, a light receiving element array 23, and a receiving circuit 25. The ball lens 21 and the light receiving element array 23 constitute the light receiver 20. FIG. 10 is a plan view of the light receiver 20 seen from above. FIG. 11 is a side view of the receiving device 2 seen from a viewpoint perpendicular to a plane including a circle formed by the light receiving element array 23. The light receiving element array 23 is placed on a substrate 200 having a hollowed-out portion for arranging the ball lens 21. The substrate 200 may be included in the light receiver 20. The positional relationship between the ball lens 21 and the light receiving element array 23 is fixed by a support (not shown). In this embodiment, the support for fixing the ball lens 21 and the light receiving element array 23 is omitted. The ball lens 21 and the light receiving element array 23 may be fixed by the substrate 200.

[0051] The ball lens 21 has the same configuration as the ball lens 11 of the first embodiment. The ball lens 21 focuses a spatial optical signal arriving from the outside onto a focusing area of ​​the ball lens 21.

[0052] Fig. 12 is a conceptual diagram for explaining the light receiving range of a spatial optical signal that can be received by ball lens 21. Fig. 12 is a plan view of optical receiver 20 viewed from above. Although a portion of the spatial optical signal arriving toward ball lens 21 is blocked by light receiving element array 23 and substrate 200, most of the light is collected by ball lens 21 and received by light receiving element array 23. As shown in Fig. 12, receiving device 2 of this embodiment can receive spatial optical signals arriving from directions of 360 degrees within a plane parallel to a plane including a circle formed by light receiving element array 23.

[0053] FIG. 13 is a perspective view of the light receiver 20 composed of the ball lens 21 and the light receiving element array 23. FIG. 13 is a perspective view of the light receiver 20 viewed from an obliquely upward position on the incident surface side. The light receiving element array 23 includes a plurality of light receiving elements 231 arranged in an annular shape along the circumferential direction of the ball lens 21. Each of the plurality of light receiving elements 231 constituting the light receiving element array 23 has a configuration similar to that of the light receiving element 131 of the first embodiment. There is no limitation on the number of light receiving elements 231 constituting the light receiving element array 23. The light receiving element array 23 is disposed in the rear stage of the ball lens 21. The plurality of light receiving elements 231 include a light receiving section (not shown) that receives an optical signal derived from a spatial optical signal of a light receiving object. Each of the plurality of light receiving elements 231 is disposed so that the light receiving section faces the exit surface of the ball lens 21. Each of the plurality of light receiving elements 231 is disposed so that the light receiving section is located in the light collecting region of the ball lens 21. The optical signal focused by ball lens 21 is received by the light receiving portion of light receiving element 231 located in the light focusing area.

[0054] Each of the multiple light receiving elements 231 constituting the light receiving element array 23 converts a received optical signal into an electrical signal. Each of the multiple light receiving elements 231 constituting the light receiving element array 23 outputs the converted electrical signal to the receiving circuit 25. Although only one line (path) between the light receiving element array 23 and the receiving circuit 25 is illustrated in FIG. 10, the light receiving element array 23 and the receiving circuit 25 may be connected by multiple paths. For example, each of the light receiving elements 231 constituting the light receiving element array 23 may be individually connected to the receiving circuit 25. For example, the light receiving elements 231 constituting the light receiving element array 23 may be configured to be connected to the receiving circuit 25 in groups of several light receiving elements 231 constituting the light receiving element array 23.

[0055] The receiving circuit 25 has the same configuration as the receiving circuit 15 of the first embodiment. The receiving circuit 25 acquires signals output from each of the multiple light receiving elements 231 constituting the light receiving element array 23. The receiving circuit 25 amplifies the signals from each of the multiple light receiving elements 231. The receiving circuit 25 decodes the amplified signals and analyzes the signals from the communication target. The signals decoded by the receiving circuit 25 are used for any purpose. There are no particular limitations on the use of the signals decoded by the receiving circuit 25.

[0056] As described above, the receiving device of this embodiment includes a ball lens, a light receiving element array, and a receiving circuit. The ball lens focuses optical signals propagating through space. The light receiving element array is composed of a plurality of light receiving elements. The plurality of light receiving elements are arranged in a ring shape in the light focusing region of the ball lens so as to surround the periphery of the ball lens. The light receiving element array outputs a signal derived from the optical signal received by the plurality of light receiving elements. The receiving circuit decodes the signal output from the light receiving element array.

[0057] The receiving device of this embodiment receives optical signals collected by the ball lens using a plurality of receiving elements arranged in a ring shape in the light collecting region of the ball lens. The ball lens collects optical signals arriving from any direction approximately parallel to a plane including the ring formed by the plurality of light receiving elements in the light collecting region. Since the plurality of receiving elements are arranged in a ring shape in the light collecting region of the ball lens, spatial optical signals arriving from any direction along the surface of the ring formed by the light receiving element array can be received. That is, according to this embodiment, spatial optical signals arriving from 360-degree directions can be received.

[0058] (Third embodiment) Next, a receiving device according to a third embodiment will be described with reference to the drawings. The receiving device of this embodiment differs from the receiving device of the first embodiment in that it includes a cylindrical lens that refracts the signal light collected by the ball lens in a direction substantially perpendicular to the direction in which the signal light is refracted. The receiving device of this embodiment may be combined with the configuration of the second embodiment.

[0059] (composition) Fig. 14 is a conceptual diagram showing an example of the configuration of the receiving device 3 of this embodiment. The receiving device 3 includes a ball lens 31, a light receiving element array 33, a receiving circuit 35, and an optical element 37. The ball lens 31, the light receiving element array 33, and the optical element 37 configure a light receiver 30. Fig. 14 is a plan view of the light receiver 30 as viewed from above.

[0060] The ball lens 31 has the same configuration as the ball lens 11 of the first embodiment. The ball lens 31 focuses a spatial optical signal arriving from the outside onto the focusing area of ​​the ball lens 31.

[0061] Fig. 15 is a perspective view showing an example of the positional relationship between light receiving element array 33 and optical element 37. Fig. 15 is a perspective view seen from an obliquely upward viewpoint on the incident surface side of optical element 37. Light receiving element array 33 and optical element 37 have a shape curved in an arc toward the center of ball lens 31.

[0062] The optical element 37 is a cylindrical lens bent in an arc shape. The optical element 37 has a shape bent in an arc shape with the curved surface (first surface) of the cylindrical lens facing inward and the flat surface (second surface) facing outward. The optical element 37 is formed with a curvature that matches the light collecting area formed around the ball lens 31. The optical element 37 is disposed between the ball lens 31 and the light receiving element array 33. The first surface of the optical element 37 faces the emission surface of the ball lens 31. The second surface of the optical element 37 faces the light receiving surface of the light receiving element array 33. The optical element 37 focuses the optical signal focused by the ball lens 31 toward the light receiving elements 331 that constitute the light receiving element array 33.

[0063] Fig. 16 is a cross-sectional view of a portion of a light receiver 30 composed of a ball lens 31, a light receiving element array 33, and an optical element 37. Fig. 16 shows an example in which a light receiving element 331 is arranged on an arc-shaped substrate 330. Fig. 16 shows the trajectory of light collected by the ball lens 31. An optical signal collected by the ball lens 31 in the light collecting region of the ball lens 31 is collected by the optical element 37. The optical signal collected by the optical element 37 is received by any of the light receiving elements 331 constituting the light receiving element array 33 arranged in the light collecting region of the optical element 37.

[0064] The light receiving element array 33 has the same configuration as the light receiving element array 13 of the first embodiment. The light receiving element array 33 is disposed after the optical element 37. The light receiving elements 331 included in the light receiving element array 33 each include a light receiving section 332 that receives an optical signal derived from a spatial optical signal to be received. Each of the light receiving elements 331 is disposed such that the light receiving section 332 faces the emission surface of the optical element 37. Each of the light receiving elements 331 is disposed such that the light receiving section 332 is located in the light collecting region of the optical element 37. The optical signal collected by the ball lens 31 is collected by the optical element 37 and received by the light receiving section 332 of the light receiving element 331.

[0065] In the configuration of the first embodiment, when a spatial optical signal spreading in a direction parallel to the horizontal plane is received, the light receiving element array 13 is arranged so that the arc formed by the light receiving element array 13 is approximately parallel to the horizontal plane. If arranged in this way, it is possible to share the reception of spatial optical signals arriving from various directions with each of the multiple light receiving elements 131. However, in such an arrangement, it is difficult to efficiently receive a spatial optical signal spreading in a direction perpendicular to the horizontal plane, since the spatial optical signal is incident on the light receiving element array 13 with a shift in the short side direction. In contrast, in the configuration of this embodiment, the optical signal incident on the light receiving element array 33 with a shift in the short side direction is focused along the short side direction by the optical element 37. Therefore, according to the configuration of this embodiment, it is easier to receive a spatial optical signal spreading in the vertical direction than the configuration of the first embodiment.

[0066] Each of the plurality of light receiving elements 331 constituting the light receiving element array 33 converts a received optical signal into an electrical signal. Each of the plurality of light receiving elements 331 constituting the light receiving element array 33 outputs the converted electrical signal to the receiving circuit 35. Although only one line (path) between the light receiving element array 33 and the receiving circuit 35 is illustrated in FIG. 14, the light receiving element array 33 and the receiving circuit 35 may be connected by a plurality of paths. For example, each of the plurality of light receiving elements 331 constituting the light receiving element array 33 may be individually connected to the receiving circuit 35. For example, the light receiving element array 33 may be configured so that each group of some of the plurality of light receiving elements 331 constituting the light receiving element array 33 is connected to the receiving circuit 35.

[0067] The receiving circuit 35 has the same configuration as the receiving circuit 15 of the first embodiment. The receiving circuit 35 acquires signals output from each of the multiple light receiving elements 331 constituting the light receiving element array 33. The receiving circuit 35 amplifies the signals from each of the multiple light receiving elements 331. The receiving circuit 35 decodes the amplified signals and analyzes the signals from the communication target. The signals decoded by the receiving circuit 35 are used for any purpose. There are no particular limitations on the use of the signals decoded by the receiving circuit 35.

[0068] [Modification 3] Next, a modified example (modified example 3) of this embodiment will be described with reference to the drawings. FIG. 17 is a conceptual diagram showing an example of the configuration of a receiving device 3-3 of this modified example. The receiving device 3-3 includes a ball lens 31, a light receiving element array 33, a receiving circuit 35, and an optical element 37-3. The ball lens 31, the light receiving element array 33, and the optical element 37-3 constitute a light receiver 30-3. FIG. 17 is a plan view of the light receiver 30-3 seen from above. The receiving device of this modified example includes an optical element 37-3 in which a plurality of cylindrical lenses are combined. FIG. 17 is a perspective view showing an example of the positional relationship between the light receiving element array 33 and the optical element 37-3. FIG. 17 is a perspective view seen from a viewpoint obliquely above the incident surface side of the optical element 37-3. The light receiving element array 33 and the optical element 37-3 have a shape curved in an arc toward the center of the ball lens 31.

[0069] The optical element 37-3 has a structure in which a plurality of partial optical elements 370 are combined. Each of the plurality of partial optical elements 370 is associated with each of the plurality of light receiving elements 331. For example, the partial optical element 370 is a cylindrical lens. The partial optical element 370 is arranged in an arc shape with the curved surface (first surface) of the cylindrical lens facing the ball lens 31 side and the flat surface (second surface) facing the light receiving element 331 side. The partial optical element 370 is arranged with a curvature that matches the light collecting area formed around the ball lens 31. The partial optical element 370 is arranged between the ball lens 31 and the light receiving element array 33. The first surface of the partial optical element 370 is directed to the emission surface of the ball lens 31. The second surface of the partial optical element 370 is directed to the light receiving surface of the light receiving element 331. The partial optical element 370 focuses the optical signal focused by the ball lens 31 toward the corresponding light receiving element 331. The partial optical element 370 focuses the optical signal along the short side direction of the light receiving element array 33, and also focuses the optical signal along the long side direction of the light receiving element array 33. In other words, the partial optical element 370 focuses the optical signal focused by the ball lens 31 toward the associated light receiving element 331.

[0070] The optical signal focused by the ball lens 31 in the light-focusing region where the optical element 37-3 is disposed is focused by any of the partial optical elements 370 constituting the optical element 37-3. The optical signal focused by the partial optical element 370 is received by the light-receiving element 331 disposed in the light-focusing region of the partial optical element 370.

[0071] By using the optical element 37-3 of this modification, it is possible to guide an optical signal toward the light receiving element 331 in the long side direction as well as in the short side direction of the light receiving element array 33. When the optical element 37 is used, it is not possible to receive light that is focused on the light receiving element array 33 but is focused on an insensitive region outside the light receiving element 331. By using the optical element 37-3 of this modification, it is possible to configure the light that is focused on an insensitive region outside the light receiving element 331 to be guided to the light receiving element 331. In other words, by using the optical element 37-3 of this modification, it is possible to improve the light receiving efficiency of the optical signal compared to the case where the optical element 37 is used.

[0072] As described above, the receiving device of the present embodiment includes a ball lens, a light receiving element array, an optical element, and a receiving circuit. The ball lens collects an optical signal propagating through space. The light receiving element array is composed of a plurality of light receiving elements that receive the optical signal collected by the ball lens. The optical element is disposed between the ball lens and the light receiving element array. The optical element guides the optical signal collected by the ball lens toward the light receiving section of any of the light receiving elements that constitute the light receiving element array. For example, the optical element is a cylindrical lens that is bent in an arc shape along the circumferential direction of the ball lens with the flat side facing outward. The optical element collects the optical signal collected by the ball lens in a direction perpendicular to the arrangement direction of the light receiving element array, and guides the optical signal to the light receiving section of any of the light receiving elements that constitute the light receiving element array. The light receiving element array outputs a signal derived from the optical signal received by the plurality of light receiving elements. The receiving circuit decodes the signal output from the light receiving element array.

[0073] The receiving device of this embodiment focuses optical signals in a direction perpendicular to the arrangement direction of the multiple light receiving elements by using a cylindrical lens that is bent in an arc shape with its flat side facing outward along the circumferential direction of the ball lens. According to this embodiment, optical signals that deviate from the direction perpendicular to the arrangement direction of the multiple light receiving elements are guided toward the light receiving parts of the light receiving elements by optical elements, thereby improving the light receiving efficiency of the optical signals.

[0074] (Fourth embodiment) Next, a receiving device according to a fourth embodiment will be described with reference to the drawings. The receiving device of this embodiment differs from the receiving device of the first embodiment in that it includes a diffractive optical element (DOE) that refracts the signal light collected by the ball lens in a direction substantially perpendicular to the direction in which the signal light is refracted. The receiving device of this embodiment may be combined with the configuration of the second embodiment.

[0075] (composition) Fig. 18 is a conceptual diagram showing an example of the configuration of the receiving device 4 of this embodiment. The receiving device 4 includes a ball lens 41, a light receiving element array 43, a receiving circuit 45, and an optical element 47. The ball lens 41, the light receiving element array 43, and the optical element 47 configure a light receiver 40. Fig. 18 is a plan view of the light receiver 40 as viewed from above.

[0076] The ball lens 41 has the same configuration as the ball lens 11 of the first embodiment. The ball lens 41 focuses a spatial optical signal arriving from the outside onto the focusing area of ​​the ball lens 41.

[0077] Fig. 19 is a perspective view showing an example of the positional relationship between light-receiving element array 43 and optical element 47. Fig. 19 is a perspective view looking down from a vantage point diagonally above the incident surface side of optical element 47. Light-receiving element array 43 and optical element 47 have a shape curved in an arc toward the center of ball lens 41.

[0078] Optical element 47 (also called diffractive optical element) includes first diffraction section 471, second diffraction section 472, and transparent section 475. First diffraction section 471, second diffraction section 472, and transparent section 475 have a shape curved in an arc shape toward the center of ball lens 41. First diffraction section 471 and second diffraction section 472 are configured to sandwich transparent section 475. For example, first diffraction section 471 and second diffraction section 472 are near-field diffractive optical elements that diffract the optical signal collected by ball lens 41 toward the light collection region. Transparent section 475 is made of a material that transmits light in the wavelength region of the optical signal. Transparent section 475 may be made of an optical member that collects light in the wavelength region of the optical signal toward light receiving element 431, or may be opened.

[0079] The optical element 47 has a shape curved in an arc with a first surface facing inward and a second surface opposing the first surface facing outward. The optical element 47 is formed with a curvature that matches the light collecting area formed around the ball lens 41. The optical element 47 is disposed between the ball lens 41 and the light receiving element array 43. The first surface of the optical element 47 is a light receiving surface. The first surface of the optical element 47 faces the exit surface of the ball lens 41. The second surface of the optical element 47 is an exit surface. The second surface of the optical element 47 faces the light receiving surface of the light receiving element array 43. The optical element 47 diffracts the optical signal collected by the ball lens 41 toward the light receiving elements 431 that constitute the light receiving element array 43.

[0080] FIG. 20 is a cross-sectional view of a part of the light receiver 40 composed of the ball lens 41, the light receiving element array 43, and the optical element 47. FIG. 20 shows an example in which the light receiving element 431 is arranged on the arc-shaped substrate 430. FIG. 20 shows the trajectory of light diffracted by the ball lens 41. The optical signal collected by the ball lens 41 in the light collecting region in which the optical element 47 is arranged is diffracted by the optical element 47. The first diffraction section 471 diffracts the optical signal incident on the light receiving surface of the optical element 47 from obliquely above toward any one of the light receiving elements 431 constituting the light receiving element array 43. The second diffraction section 472 diffracts the optical signal incident on the light receiving surface of the optical element 47 from obliquely below toward any one of the light receiving elements 431 constituting the light receiving element array 43. The optical signal that has passed through the transparent section 475 proceeds toward any one of the light receiving elements 431 constituting the light receiving element array 43. The optical signal diffracted by the optical element 47 is received by any one of the light receiving elements 431 constituting the light receiving element array 43 arranged after the optical element 47 .

[0081] For example, when the direction in which the spatial optical signal arrives with respect to the surface formed by the light receiving element array 43 is limited to one direction, the optical element 47 may be composed of only one of the first diffraction section 471 and the second diffraction section 472. For example, when the spatial optical signal arrives only from above with respect to the surface formed by the light receiving element array 43, the spatial optical signal does not arrive from below, so the optical element 47 may be composed of only the first diffraction section 471. For example, when the spatial optical signal arrives only from below with respect to the surface formed by the light receiving element array 43, the spatial optical signal does not arrive from above, so the optical element 47 may be composed of only the second diffraction section 472.

[0082] The light receiving element array 43 has the same configuration as the light receiving element array 13 of the first embodiment. The light receiving element array 43 is disposed after the optical element 47. The light receiving elements 431 included in the light receiving element array 43 each include a light receiving section 432 that receives an optical signal derived from a spatial optical signal to be received. Each of the light receiving elements 431 is disposed so that the light receiving section 432 faces the emission surface of the optical element 47. Each of the light receiving elements 431 is disposed so that the light receiving section 432 is located at a position where the optical signal diffracted by the optical element 47 can be easily received. The optical signal collected by the ball lens 41 is diffracted by the optical element 47 and received by the light receiving section 432 of the light receiving element 431.

[0083] In the configuration of the first embodiment, when a spatial optical signal spreading in a direction parallel to the horizontal plane is received, the light receiving element array 13 is arranged so that the arc formed by the light receiving element array 13 is approximately parallel to the horizontal plane. If arranged in this way, each of the multiple light receiving elements 131 can be assigned to receive the spatial optical signals arriving from various directions. However, in such an arrangement, it is difficult to efficiently receive the spatial optical signal spreading in a direction perpendicular to the horizontal plane, since the spatial optical signal is incident on the light receiving element array 13 with a shift in the short side direction. In contrast, in the configuration of this embodiment, the optical signal incident on the light receiving element array 43 with a shift in the short side direction is diffracted along the short side direction by the optical element 47. Therefore, according to the configuration of this embodiment, it is easier to receive the spatial optical signal spreading in the vertical direction compared to the configuration of the first embodiment.

[0084] Each of the plurality of light receiving elements 431 constituting the light receiving element array 43 converts a received optical signal into an electrical signal. Each of the plurality of light receiving elements 431 constituting the light receiving element array 43 outputs the converted electrical signal to the receiving circuit 45. Although only one line (path) between the light receiving element array 43 and the receiving circuit 45 is illustrated in FIG. 18, the light receiving element array 43 and the receiving circuit 45 may be connected by a plurality of paths. For example, each of the plurality of light receiving elements 431 constituting the light receiving element array 43 may be individually connected to the receiving circuit 45. For example, the light receiving element array 43 may be configured so that each group of some of the plurality of light receiving elements 431 constituting the light receiving element array 43 is connected to the receiving circuit 45.

[0085] The receiving circuit 45 has the same configuration as the receiving circuit 15 of the first embodiment. The receiving circuit 45 acquires signals output from each of the multiple light receiving elements 431 constituting the light receiving element array 43. The receiving circuit 45 amplifies the signals from each of the multiple light receiving elements 431. The receiving circuit 45 decodes the amplified signals and analyzes the signals from the communication target. The signals decoded by the receiving circuit 45 are used for any purpose. There are no particular limitations on the use of the signals decoded by the receiving circuit 45.

[0086] [Modification 4] Next, a modified example (Modification 4) of this embodiment will be described with reference to the drawings. FIG. 21 is a conceptual diagram for explaining this modification. In FIG. 21, the ball lens 41 is omitted. The receiving device of this modification includes an optical element 47-4 having a diffraction portion that diffracts an optical signal diffracted between the light receiving portions 432 of two adjacent light receiving elements 431 toward one of the light receiving portions 432 of the light receiving elements 431. FIG. 21 is a perspective view showing an example of the positional relationship between the light receiving element array 43 and the optical element 47-4. FIG. 21 is a perspective view looking down from a viewpoint obliquely above the incident surface side of the optical element 47-4. The light receiving element array 43 and the optical element 47-4 have a shape curved in an arc toward the center of the ball lens 41.

[0087] Optical element 47-4 (also referred to as a diffractive optical element) includes first diffraction section 471, second diffraction section 472, third diffraction section 473, fourth diffraction section 474, and transparent section 475. First diffraction section 471, second diffraction section 472, and transparent section 475 have a shape curved in an arc toward the center of ball lens 41. First diffraction section 471 and second diffraction section 472 are configured to sandwich transparent section 475 from above and below. A plurality of third diffraction sections 473 and a plurality of fourth diffraction sections 474 are arranged in transparent section 475 in association with each of a plurality of light receiving elements 431.

[0088] Optical element 47-4 is disposed between ball lens 41 and light receiving element array 43. A first surface (light receiving surface) of optical element 47-4 faces the exit surface of ball lens 41. A second surface (exit surface) of optical element 47-4 faces the light receiving surface of light receiving element array 43. Optical element 47-4 diffracts the optical signal collected by ball lens 41 toward the associated light receiving element 431.

[0089] The first diffraction section 471 diffracts an optical signal incident on the light receiving surface of the optical element 47-4 from obliquely above, toward the associated light receiving element 431. The second diffraction section 472 diffracts an optical signal incident on the light receiving surface of the optical element 47-4 from obliquely below, toward the associated light receiving element 431. Each of the multiple third diffraction sections 473 is associated with each of the multiple light receiving elements 431. Each of the multiple third diffraction sections 473 is disposed to the left of the associated light receiving element 431 with respect to the light receiving surface of the optical element 47-4. The third diffraction section 473 diffracts an optical signal incident on the light receiving surface of the optical element 47-4 from obliquely left, toward the associated light receiving element 431. Each of the multiple fourth diffraction sections 474 is associated with each of the multiple light receiving elements 431. Each of the plurality of fourth diffraction sections 474 is disposed to the right of the corresponding light receiving element 431 with respect to the light receiving surface of the optical element 47-4. The fourth diffraction section 474 diffracts an optical signal incident on the light receiving surface of the optical element 47-4 from the diagonal right toward the corresponding light receiving element 431. The transparent section 475 is partitioned by the plurality of third diffraction sections 473 and the plurality of fourth diffraction sections 474, and is associated with each of the plurality of light receiving elements 431. The optical signal that passes through the transparent section 475 proceeds toward the corresponding light receiving element 431. The optical signal collected by the optical element 47-4 is received by any of the light receiving elements 431 that constitute the light receiving element array 43 arranged after the optical element 47-4.

[0090] The optical signal focused by ball lens 41 in the light-focus region where optical element 47-4 is disposed is diffracted by first diffraction section 471, second diffraction section 472, third diffraction section 473, and fourth diffraction section 474, or passes through transparent section 475. The optical signal guided by optical element 47-4 is received by light-receiving element 431 disposed after optical element 47-4.

[0091] By using the optical element 47-4 of this modification, it is possible to guide an optical signal toward the light receiving element 431 in the long side direction as well as in the short side direction of the light receiving element array 43. When the optical element 47 is used, an optical signal that is diffracted toward the light receiving element array 43 and enters an insensitive region outside the light receiving element 431 cannot be received. By using the optical element 47-4 of this modification, it is possible to configure so that light that has been collected in an insensitive region outside the light receiving element 431 is guided to the light receiving element 431. That is, by using the optical element 47-4 of this modification, it is possible to improve the light receiving efficiency of the optical signal compared to the case where the optical element 47 is used.

[0092] As described above, the receiving device of the present embodiment includes a ball lens, a light receiving element array, an optical element, and a receiving circuit. The ball lens focuses an optical signal propagating through space. The light receiving element array is composed of a plurality of light receiving elements that receive the optical signal focused by the ball lens. The optical element is disposed between the ball lens and the light receiving element array. The optical element guides the optical signal focused by the ball lens toward the light receiving section of any of the light receiving elements that constitute the light receiving element array. For example, the optical element includes a diffractive optical element that is curved in an arc shape along the circumferential direction of the ball lens. The optical element diffracts the optical signal focused by the ball lens in a direction perpendicular to the arrangement direction of the light receiving element array, and guides the optical signal to the light receiving section of any of the light receiving elements that constitute the light receiving element array. The light receiving element array outputs a signal derived from the optical signal received by the plurality of light receiving elements. The receiving circuit decodes the signal output from the light receiving element array.

[0093] The receiving device of this embodiment diffracts the optical signal in a direction perpendicular to the arrangement direction of the multiple light receiving elements by a diffractive optical element bent in an arc shape with the flat side facing outward along the circumferential direction of the ball lens. According to this embodiment, the optical signal that deviates from the direction perpendicular to the arrangement direction of the multiple light receiving elements is guided by the optical element toward the light receiving portion of the light receiving element, thereby improving the light receiving efficiency of the optical signal.

[0094] Fifth embodiment Next, a receiving device according to a fifth embodiment will be described with reference to the drawings. The receiving device of this embodiment differs from the receiving device of the first embodiment in that it includes a diffusion plate that diffuses the signal light collected by the ball lens in a direction substantially perpendicular to the direction in which the signal light is refracted. The receiving device of this embodiment may be combined with the configuration of the second embodiment.

[0095] (composition) Fig. 22 is a conceptual diagram showing an example of the configuration of the receiving device 5 of this embodiment. The receiving device 5 includes a ball lens 51, a light receiving element array 53, a receiving circuit 55, and an optical element 57. The ball lens 51, the light receiving element array 53, and the optical element 57 configure a light receiver 50. Fig. 22 is a plan view of the light receiver 50 as viewed from above.

[0096] The ball lens 51 has the same configuration as the ball lens 11 of the first embodiment. The ball lens 51 focuses a spatial optical signal arriving from the outside onto the focusing area of ​​the ball lens 51.

[0097] Fig. 23 is a perspective view showing an example of the positional relationship between light-receiving element array 53 and optical element 57. Fig. 23 is a perspective view looking down from a vantage point diagonally above the incident surface side of optical element 57. Light-receiving element array 53 and optical element 57 have a shape curved in an arc toward the center of ball lens 51.

[0098] Optical element 57 (also referred to as a diffusion plate) includes first diffusion portion 571, second diffusion portion 572, and transparent portion 575. First diffusion portion 571, second diffusion portion 572, and transparent portion 575 have a shape curved in an arc toward the center of ball lens 51. First diffusion portion 571 and second diffusion portion 572 are configured to sandwich transparent portion 575 from above and below. For example, first diffusion portion 571 and second diffusion portion 572 are diffusion plates that diffuse the optical signal collected by ball lens 51. Transparent portion 575 is made of a material that transmits light in the wavelength region of the optical signal. Transparent portion 575 may be made of an optical member that collects light in the wavelength region of the optical signal toward light receiving element 531, or may be opened.

[0099] The optical element 57 has a shape curved in an arc with a first surface facing inward and a second surface opposing the first surface facing outward. The optical element 57 is formed with a curvature that matches the light collecting region formed around the ball lens 51. The optical element 57 is disposed between the ball lens 51 and the light receiving element array 53. The first surface of the optical element 57 is a light receiving surface. The first surface of the optical element 57 faces the exit surface of the ball lens 51. The second surface of the optical element 57 is an exit surface. The second surface of the optical element 57 faces the light receiving surface of the light receiving element array 53. The optical element 57 diffuses the optical signal collected by the ball lens 51 toward a range including the light receiving elements 531 that constitute the light receiving element array 53.

[0100] FIG. 24 is a cross-sectional view of a part of the light receiver 50 composed of the ball lens 51, the light receiving element array 53, and the optical element 57. FIG. 24 shows an example in which the light receiving element 531 is arranged on the arc-shaped substrate 530. FIG. 24 shows the trajectory of light diffused by the ball lens 51. The optical signal collected by the ball lens 51 in the light collecting region in which the optical element 57 is arranged is diffused by the optical element 57. The first diffusion section 571 diffuses the optical signal incident on the light receiving surface of the optical element 57 from obliquely above toward a range including any of the light receiving elements 531 constituting the light receiving element array 53. The second diffusion section 572 diffuses the optical signal incident on the light receiving surface of the optical element 57 from obliquely below toward a range including any of the light receiving elements 531 constituting the light receiving element array 53. The optical signal that has passed through the transparent section 575 proceeds toward any of the light receiving elements 531 constituting the light receiving element array 53. The optical signal diffused by the optical element 57 is received by any one of the light receiving elements 531 constituting the light receiving element array 53 arranged after the optical element 57 .

[0101] For example, when the direction in which the spatial optical signal arrives with respect to the surface formed by the light receiving element array 53 is limited to one direction, the optical element 57 may be composed of only one of the first diffusion section 571 and the second diffusion section 572. For example, when the spatial optical signal arrives only from above with respect to the surface formed by the light receiving element array 53, the spatial optical signal does not arrive from below, so the optical element 57 may be composed of only the first diffusion section 571. For example, when the spatial optical signal arrives only from below with respect to the surface formed by the light receiving element array 53, the spatial optical signal does not arrive from above, so the optical element 57 may be composed of only the second diffusion section 572.

[0102] The light receiving element array 53 has the same configuration as the light receiving element array 13 of the first embodiment. The light receiving element array 53 is disposed after the optical element 57. The light receiving elements 531 included in the light receiving element array 53 each include a light receiving section 532 that receives an optical signal derived from a spatial optical signal to be received. Each of the light receiving elements 531 is disposed so that the light receiving section 532 faces the emission surface of the optical element 57. Each of the light receiving elements 531 is disposed so that the light receiving section 532 is located at a position where the optical signal diffused by the optical element 57 can be easily received. The optical signal collected by the ball lens 51 is diffused by the optical element 57 and received by the light receiving section 532 of the light receiving element 531.

[0103] In the configuration of the first embodiment, when a spatial optical signal spreading in a direction parallel to the horizontal plane is received, the light receiving element array 13 is arranged so that the arc formed by the light receiving element array 13 is approximately parallel to the horizontal plane. If arranged in this way, each of the multiple light receiving elements 131 can be assigned to receive the spatial optical signals arriving from various directions. However, in such an arrangement, it is difficult to efficiently receive the spatial optical signal spreading in a direction perpendicular to the horizontal plane, since the spatial optical signal is incident on the light receiving element array 13 while shifting in the short side direction. In contrast, in the configuration of this embodiment, the optical signal incident on the light receiving element array 53 while shifting in the short side direction is diffused along the short side direction by the optical element 57. Therefore, according to the configuration of this embodiment, it is easier to receive a spatial optical signal spreading in the vertical direction compared to the configuration of the first embodiment. The configuration of this embodiment is a simple configuration, but can improve the light receiving efficiency compared to the configuration of the first embodiment.

[0104] Each of the plurality of light receiving elements 531 constituting the light receiving element array 53 converts a received optical signal into an electrical signal. Each of the plurality of light receiving elements 531 constituting the light receiving element array 53 outputs the converted electrical signal to the receiving circuit 55. Although only one line (path) between the light receiving element array 53 and the receiving circuit 55 is illustrated in FIG. 22, the light receiving element array 53 and the receiving circuit 55 may be connected by a plurality of paths. For example, each of the plurality of light receiving elements 531 constituting the light receiving element array 53 may be individually connected to the receiving circuit 55. For example, the light receiving element array 53 may be configured so that each group of some of the plurality of light receiving elements 531 constituting the light receiving element array 53 is connected to the receiving circuit 55.

[0105] The receiving circuit 55 has the same configuration as the receiving circuit 15 of the first embodiment. The receiving circuit 55 acquires signals output from each of the multiple light receiving elements 531 constituting the light receiving element array 53. The receiving circuit 55 amplifies the signals from each of the multiple light receiving elements 531. The receiving circuit 55 decodes the amplified signals and analyzes the signals from the communication target. The signals decoded by the receiving circuit 55 are used for any purpose. There are no particular limitations on the use of the signals decoded by the receiving circuit 55.

[0106] [Modification 5] Next, a modified example (Modification 5) of this embodiment will be described with reference to the drawings. FIG. 25 is a conceptual diagram for explaining this modification. In FIG. 25, the ball lens 51 is omitted. The receiving device of this modification includes an optical element 57-5 that diffuses an optical signal diffused between the light receiving sections 532 of two adjacent light receiving elements 531 toward one of the light receiving sections 532 of the light receiving elements 531. FIG. 25 is a perspective view showing an example of the positional relationship between the light receiving element array 53 and the optical element 57-5. FIG. 25 is a perspective view looking down from a viewpoint obliquely above the incident surface side of the optical element 57-5. The light receiving element array 53 and the optical element 57-5 have a shape curved in an arc toward the center of the ball lens 51.

[0107] Optical element 57-5 (also referred to as a diffusion plate) includes diffusion portion 573 and transparent portion 576. Diffusion portion 573 has a shape curved in an arc toward the center of ball lens 51. Transparent portion 576 is provided in diffusion portion 573 in correspondence with each of the multiple light receiving elements 531.

[0108] Optical element 57-5 is disposed between ball lens 51 and light receiving element array 53. A first surface (light receiving surface) of optical element 57-5 faces the exit surface of ball lens 51. A second surface (exit surface) of optical element 57-5 faces the light receiving surface of light receiving element array 53. Optical element 57-5 diffuses the optical signal collected by ball lens 51 toward a range including light receiving element 531.

[0109] The diffusion section 573 diffuses the optical signal incident on the light receiving surface of the optical element 57-5 toward a range including the light receiving element array 53. The optical signal that passes through the transparent section 576 proceeds toward the associated light receiving element 531. The optical signal collected by the optical element 57-5 is received by any of the light receiving elements 531 that constitute the light receiving element array 53 and are disposed after the optical element 57-5.

[0110] The optical signal focused by ball lens 51 in the light-focus region where optical element 57-5 is disposed is diffused by diffusion portion 573 or passes through transparent portion 575. The optical signal guided by optical element 57-5 is received by light-receiving element 531 disposed after optical element 57-5.

[0111] By using the optical element 57-5 of this modification, it is possible to guide an optical signal toward the light receiving element 531 even with respect to an optical signal that is diffused into a dead area between adjacent light receiving elements 531. When the optical element 57 is used, an optical signal that is diffused within the range of the light receiving element array 53 but enters a dead area outside the light receiving element 531 cannot be received. By using the optical element 57-5 of this modification, it is possible to configure so that a part of the light that has been collected in a dead area outside the light receiving element 531 is guided to the light receiving element 531. That is, by using the optical element 57-5 of this modification, it is possible to improve the light receiving efficiency of an optical signal compared to the case where the optical element 57 is used.

[0112] As described above, the receiving device of the present embodiment includes a ball lens, a light receiving element array, an optical element, and a receiving circuit. The ball lens collects an optical signal propagating through space. The light receiving element array is composed of a plurality of light receiving elements that receive the optical signal collected by the ball lens. The optical element is disposed between the ball lens and the light receiving element array. The optical element guides the optical signal collected by the ball lens toward the light receiving section of any of the light receiving elements that constitute the light receiving element array. For example, the optical element includes a diffusion plate that is curved in an arc shape along the circumferential direction of the ball lens. The optical element diffuses the optical signal collected by the ball lens and guides it to the light receiving section of any of the light receiving elements that constitute the light receiving element array. The light receiving element array outputs a signal derived from the optical signal received by the plurality of light receiving elements. The receiving circuit decodes the signal output from the light receiving element array.

[0113] The receiving device of this embodiment diffuses the optical signal by a diffusion plate bent in an arc shape along the circumferential direction of the ball lens. According to this embodiment, the optical signal that deviates in a direction perpendicular to the arrangement direction of the multiple light receiving elements is guided toward the light receiving parts of the light receiving elements by the optical element, thereby improving the light receiving efficiency of the optical signal.

[0114] The optical elements of the third to fifth embodiments may be combined in any desired manner. For example, the optical element of the first embodiment may be disposed in the transparent portion of the optical element of the fourth to fifth embodiments. For example, the optical element of the fourth embodiment may be used for the spatial optical signal arriving from above, and the optical element of the fifth embodiment may be used for the spatial optical signal arriving from below, relative to the surface formed by the light receiving element array. For example, the optical elements of the third to fifth embodiments may be stacked in any desired order in the minor axis direction to configure the optical element.

[0115] Sixth embodiment Next, a receiving device according to a sixth embodiment will be described with reference to the drawings. The receiving device of this embodiment differs from the receiving device of the first embodiment in that it includes a reflecting structure that reflects an optical signal focused at a position away from the light receiving portion of the light receiving element toward the light receiving portion. The receiving device of this embodiment may be combined with the configurations of the second to fifth embodiments.

[0116] (composition) Fig. 26 is a conceptual diagram showing an example of the configuration of the receiving device 6 of this embodiment. The receiving device 6 includes a ball lens 61, a light receiving element array 63, and a receiving circuit 65. The ball lens 61 and the light receiving element array 63 configure a light receiver 60. Fig. 26 is a plan view of the light receiver 60 as viewed from above.

[0117] The ball lens 61 has the same configuration as the ball lens 11 of the first embodiment. The ball lens 61 focuses a spatial optical signal arriving from the outside onto the focusing area of ​​the ball lens 61.

[0118] The light receiving element array 63 includes a plurality of light receiving elements 631 arranged in an arc shape along the circumferential direction of the ball lens 61. Each of the plurality of light receiving elements 631 constituting the light receiving element array 63 has a configuration similar to that of the light receiving element 131 of the first embodiment. There is no limitation on the number of light receiving elements constituting the light receiving element array 63. The light receiving element array 63 includes a reflection structure 636. The reflection structure 636 is provided in correspondence with each of the plurality of light receiving elements 631.

[0119] The reflection structure 636 is disposed in a dead area of ​​the light receiving surface of the light receiving element 631. The dead area is a portion of the light receiving surface of the light receiving element 631 where the light receiving portion 632 is not exposed. FIG. 27 is a conceptual diagram showing an example of the installation of the reflection structure 636. FIG. 27 is a perspective view looking down from a viewpoint obliquely above the incident surface side of the light receiving element array 63. In the example of FIG. 27, a common reflection structure 636 is installed in the dead area between the light receiving portions 632 of two adjacent light receiving elements 631. In addition, a dedicated reflection structure 636 is installed in the light receiving elements 631 at both ends of the light receiving element array 63. The multiple reflection structures 636 may have the same shape or different shapes. The reflection structures 636 may be installed in the dead areas above and below the light receiving element 631.

[0120] For example, the reflecting structure 636 has a base material such as plastic, glass, silicon, or metal. For example, the reflecting surface of the reflecting structure 636 is formed by plating, vapor deposition, polishing, or the like. For example, the reflecting structure 636 can be formed by vapor deposition of aluminum on glass. For example, the reflecting structure 636 may be attached to a metal frame such as aluminum and fixed to a dead area around the light receiving unit 632 of the light receiving element 631. Note that there are no particular limitations on the material of the reflecting structure 636 or the properties of the reflecting surface as long as it can reflect the incident optical signal to the light receiving unit 632.

[0121] Light receiving element array 63 is disposed after ball lens 61. A plurality of light receiving elements 631 include a light receiving portion 632 that receives an optical signal derived from a spatial optical signal to be received. Each of the plurality of light receiving elements 631 is disposed so that light receiving portion 632 faces the emission surface of ball lens 61. Each of the plurality of light receiving elements 631 is disposed so that light receiving portion 632 is located in the light collecting region of ball lens 61. The optical signal collected by ball lens 61 is received by light receiving portion 632 of light receiving element 631 located in the light collecting region. Of the optical signal collected by ball lens 61, a component that is incident on light receiving portion 632 of light receiving element 631 is received as it is by light receiving portion 632. Of the optical signal focused by ball lens 61, the component that enters the insensitive area of ​​light receiving element 631 is reflected by the reflecting surface of reflecting structure 636 and guided to light receiving section 632, where it is received.

[0122] Fig. 28 is a conceptual diagram for explaining an example of the trajectory of a spatial optical signal incident on the optical receiver 60. Fig. 28 shows the trajectory of light focused by the ball lens 61. In the example of Fig. 28, the optical signal focused by the ball lens 61 in the light-focusing region where the light-receiving element array 63 is arranged is incident on the light-receiving portion 632 of a single light-receiving element 631. In the case of the example of Fig. 28, the optical signal focused in the light-focusing region where the light-receiving element array 63 is arranged is received by the single light-receiving element 631.

[0123] FIG. 29 is a conceptual diagram for explaining another example of the trajectory of a spatial optical signal incident on the optical receiver 60. FIG. 29 shows the trajectory of light collected by the ball lens 61. In the example of FIG. 29, the optical signal collected by the ball lens 61 in the light collection region where the light receiving element array 63 is arranged is incident on the light receiving parts 632 of the two adjacent light receiving elements 631. Of the optical signal collected by the ball lens 61, the component that is incident on the light receiving part 632 of the light receiving element 631 is received by the light receiving part 632 as it is. Of the optical signal collected by the ball lens 61, the component that is incident on the blind region of the light receiving element 631 is reflected by the reflecting surface of the reflecting structure 636 and guided to the light receiving part 632, and is received by the light receiving part 632. In the example of FIG. 29, the optical signal collected in the light collection region where the light receiving element array 63 is arranged is received by the two adjacent light receiving elements 631.

[0124] Each of the multiple light receiving elements constituting the light receiving element array 63 converts a received optical signal into an electrical signal. Each of the multiple light receiving elements constituting the light receiving element array 63 outputs the converted electrical signal to the receiving circuit 65. Although only one line (path) between the light receiving element array 63 and the receiving circuit 65 is illustrated in FIG. 26, the light receiving element array 63 and the receiving circuit 65 may be connected by multiple paths. For example, each of the light receiving elements 631 constituting the light receiving element array 63 may be individually connected to the receiving circuit 65. For example, the light receiving elements 631 constituting the light receiving element array 63 may be configured to be connected to the receiving circuit 65 in groups of several of the light receiving elements 631 constituting the light receiving element array 63.

[0125] In the configuration of the first embodiment, the optical signal focused on the dead area of ​​the light receiving surface of the light receiving element 131 is not received. In contrast, in the configuration of this embodiment, the optical signal focused on the dead area of ​​the light receiving surface of the light receiving element 631 is reflected by the reflecting surface of the reflecting structure 636 and guided to the light receiving section 632. Therefore, according to the configuration of this embodiment, the received light intensity of the spatial optical signal is increased compared to the configuration of the first embodiment.

[0126] The receiving circuit 65 has the same configuration as the receiving circuit 15 of the first embodiment. The receiving circuit 65 acquires signals output from each of the multiple light receiving elements 631 constituting the light receiving element array 63. The receiving circuit 65 amplifies the signals from each of the multiple light receiving elements 631. The receiving circuit 65 decodes the amplified signals and analyzes the signals from the communication target. The signals decoded by the receiving circuit 65 are used for any purpose. There are no particular limitations on the use of the signals decoded by the receiving circuit 65.

[0127] As described above, the receiving device of this embodiment includes a ball lens, a light receiving element array, a reflection structure, and a receiving circuit. The ball lens focuses an optical signal propagating through space. The light receiving element array is composed of a plurality of light receiving elements that receive the optical signal focused by the ball lens. The optical element is disposed between the ball lens and the light receiving element array. The reflection structure is disposed in an insensitive region of the plurality of light receiving elements. The reflection structure reflects the optical signal emitted from the ball lens toward the light receiving portion of the light receiving element. The light receiving element array outputs a signal derived from the optical signal received by the plurality of light receiving elements. The receiving circuit decodes the signal output from the light receiving element array.

[0128] In the receiving device of this embodiment, the optical signal that falls outside the dead zone of the light receiving element is reflected toward the light receiving section by the reflection structure. According to this embodiment, the optical signal that falls outside the dead zone of the light receiving element is reflected toward the light receiving section of the light receiving element by the reflection structure, so that the light receiving efficiency of the optical signal can be improved.

[0129] Seventh embodiment Next, a communication device according to a seventh embodiment will be described with reference to the drawings. The communication device of this embodiment includes a receiving device according to any one of the first to sixth embodiments, and a transmitting device that transmits a spatial light signal corresponding to a received spatial light signal. In the following, an example of a communication device including a transmitting device including a phase modulation type spatial light modulator will be described. Note that the communication device of this embodiment may include a transmitting device including a light transmission function other than a phase modulation type spatial light modulator.

[0130] (composition) 30 is a conceptual diagram showing an example of the configuration of a communication device 700 of this embodiment. The communication device 700 includes a receiving device 710, a control device 750, and a transmitting device 770. The receiving device 710 and the transmitting device 770 transmit and receive spatial optical signals to and from external communication targets. For this reason, the communication device 700 is provided with an opening or window for transmitting and receiving spatial optical signals.

[0131] The receiving device 710 is any of the receiving devices according to the first to sixth embodiments. The receiving device 710 may be a receiving device having a configuration that combines the first to sixth embodiments. The receiving device 710 receives a spatial optical signal transmitted from a communication target (not shown). The receiving device 710 converts the received spatial optical signal into an electrical signal. The receiving device 710 outputs the converted electrical signal to the control device 750.

[0132] The control device 750 acquires a signal output from the receiving device 710. The control device 750 executes a process according to the acquired signal. There is no particular limitation on the process executed by the control device 750. The control device 750 outputs a control signal to the transmitting device 770 for transmitting an optical signal according to the executed process.

[0133] The transmitting device 770 receives a control signal from the control device 750. The transmitting device 770 projects a spatial light signal according to the control signal. The spatial light signal projected from the transmitting device 770 is received by a communication target (not shown). For example, the transmitting device 770 includes a phase modulation type spatial light modulator. The transmitting device 770 may also include a light transmitting function other than the phase modulation type spatial light modulator.

[0134] [Transmitting device] Fig. 31 is a conceptual diagram showing an example of the configuration of a transmitting device 770. The transmitting device 770 has a light source 771, a spatial light modulator 773, a curved mirror 775, and a control unit 777. The light source 771, the spatial light modulator 773, and the curved mirror 775 constitute a transmitting unit. Fig. 31 is a side view of the internal configuration of the transmitting device 770 as seen from the lateral direction. Fig. 31 is conceptual and does not accurately represent the positional relationship between the components or the traveling direction of light.

[0135] The light source 771 emits a laser beam in a predetermined wavelength band according to the control of the control unit 777. The wavelength of the laser beam emitted from the light source 771 is not particularly limited and may be selected according to the application. For example, the light source 771 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 771 includes a lens that expands the laser beam according to the size of the modulation unit 7730 of the spatial light modulator 773. A light source 771 emits light 702 that is expanded by a lens. The light 702 emitted from the light source 771 travels toward a modulation section 7730 of a spatial light modulator 773.

[0136] The spatial light modulator 773 has a modulation section 7730 to which the light 702 is irradiated. The light 702 emitted from the light source 771 is irradiated to the modulation section 7730 of the spatial light modulator 773. A pattern (also called a phase image) corresponding to an image displayed by the projected light 705 is set in the modulation section 7730 of the spatial light modulator 773 under the control of the control section 777. The light 702 incident on the modulation section 7730 of the spatial light modulator 773 is modulated according to the pattern set in the modulation section 7730 of the spatial light modulator 773. The modulated light 703 modulated by the modulation section 7730 of the spatial light modulator 773 proceeds toward the reflecting surface 7750 of the curved mirror 775.

[0137] For example, the spatial light modulator 773 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 773 can be realized by LCOS (Liquid Crystal on Silicon). The spatial light modulator 773 may also be realized by MEMS (Micro Electro Mechanical System). In the phase modulation type spatial light modulator 773, the energy can be concentrated on the image portion by operating to sequentially switch the location where the projection light 705 is projected. Therefore, when the phase modulation type spatial light modulator 773 is used, if the output of the light source 771 is the same, the image can be displayed brighter than in other methods.

[0138] The modulation section 7730 of the spatial light modulator 773 is divided into a plurality of regions (also called tiling). For example, the modulation section 7730 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 7730. 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.

[0139] A phase image is tiled on each of the tiles assigned to the modulation unit 7730. For example, a pre-generated phase image is set on each of the tiles. When light 702 is irradiated on the modulation unit 7730 with phase images set on the tiles, modulated light 703 that forms an image corresponding to the phase image of each tile is emitted. The more tiles set on the modulation unit 7730, 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 7730 are set according to the application.

[0140] The curved mirror 775 is a reflecting mirror having a curved reflecting surface 7750. The reflecting surface 7750 of the curved mirror 775 has a curvature according to the projection angle of the projected light 705. The reflecting surface 7750 of the curved mirror 775 may be a curved surface. In the example of FIG. 31, the reflecting surface 7750 of the curved mirror 775 has a shape of a side surface of a cylinder. For example, the reflecting surface 7750 of the curved mirror 775 may be a spherical surface. For example, the reflecting surface 7750 of the curved mirror 775 may be a free-form surface. For example, the reflecting surface 7750 of the curved mirror 775 may have a shape that combines multiple curved surfaces instead of a single curved surface. For example, the reflecting surface 7750 of the curved mirror 775 may have a shape that combines a curved surface and a flat surface.

[0141] Curved mirror 775 is disposed on the optical path of modulated light 703 with reflecting surface 7750 facing modulation section 7730 of spatial light modulator 773. Modulated light 703 modulated by modulation section 7730 of spatial light modulator 773 is irradiated onto reflecting surface 7750 of curved mirror 775. Light reflected by reflecting surface 7750 of curved mirror 775 (projected light 705) is magnified at a magnification rate according to the curvature of reflecting surface 7750 and projected. In the example of FIG. 31, projected light 705 is magnified along the horizontal direction (direction perpendicular to the paper surface of FIG. 31) according to the curvature of the irradiation range of modulated light 703 on reflecting surface 7750 of curved mirror 775.

[0142] For example, a shield (not shown) may be disposed between the spatial light modulator 773 and the curved mirror 775. In other words, a shield may be disposed on the optical path of the modulated light 703 modulated by the modulation unit 7730 of the spatial light modulator 773. The shield is a frame body that shields unnecessary light components contained in the modulated light 703 and defines the outer edge of the display area of ​​the projected light 705. 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 703. Details of the shield will not be described.

[0143] The control unit 777 controls the light source 771 and the spatial light modulator 773. For example, the control unit 777 is realized by a microcomputer including a processor and a memory. The control unit 777 sets a phase image corresponding to the image to be projected in the modulation unit 7730 according to the aspect ratio of the tiling set in the modulation unit 7730 of the spatial light modulator 773. For example, the control unit 777 sets a phase image corresponding to an image according to the application, such as image display, communication, distance measurement, etc., in the modulation unit 7730. 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.

[0144] The control unit 777 drives the spatial light modulator 773 so that a parameter that determines the difference between the phase of the light 702 irradiated to the modulation unit 7730 of the spatial light modulator 773 and the phase of the modulated light 703 reflected by the modulation unit 7730 changes. The parameter that determines the difference between the phase of the light 702 irradiated to the modulation unit 7730 of the spatial light modulator 773 and the phase of the modulated light 703 reflected by the modulation unit 7730 is, for example, a parameter related to optical characteristics such as a refractive index and an optical path length. For example, the control unit 777 adjusts the refractive index of the modulation unit 7730 by changing a voltage applied to the modulation unit 7730 of the spatial light modulator 773. The phase distribution of the light 702 irradiated to the modulation unit 7730 of the phase modulation type spatial light modulator 773 is modulated according to the optical characteristics of the modulation unit 7730. The method of driving the spatial light modulator 773 by the control unit 777 is determined according to the modulation method of the spatial light modulator 773 .

[0145] The control unit 777 drives the light source 771 in a state where a phase image corresponding to an image to be displayed is set in the modulation unit 7730. As a result, the light 702 emitted from the light source 771 is irradiated onto the modulation unit 7730 of the spatial light modulator 773 in accordance with the timing at which the phase image is set in the modulation unit 7730 of the spatial light modulator 773. The light 702 irradiated onto the modulation unit 7730 of the spatial light modulator 773 is modulated in the modulation unit 7730 of the spatial light modulator 773. The modulated light 703 modulated in the modulation unit 7730 of the spatial light modulator 773 is emitted toward the reflecting surface 7750 of the curved mirror 775.

[0146] For example, the curvature of the reflecting surface 7750 of the curved mirror 775 included in the transmitting device 770 and the distance between the spatial light modulator 773 and the curved mirror 775 are adjusted to set the projection angle of the projected light 705 to 180 degrees. If two transmitting devices 770 configured in this way are used, the projection angle of the projected light 705 can be set to 360 degrees. Also, if a part of the modulated light 703 is folded back by a plane mirror or the like inside the transmitting device 770 and the projected light 705 is configured to be projected in two directions, the projection angle of the projected light 705 can be set to 360 degrees. For example, a configuration is made in which the transmitting device 770 configured to project the projected light in a 360-degree direction is combined with the receiving device 2 of the second 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.

[0147] [Communication Systems] Next, a communication system using the communication device of this embodiment will be described with reference to the drawings. FIG. 32 is a conceptual diagram showing an example of the configuration of a communication system using a communication device 700. The communication device 700 has a similar configuration to the communication device 700. FIG. 32 shows an example in which a spatial optical signal is transmitted and received between a plurality of communication devices 700 arranged in a mesh pattern on a plane parallel to a horizontal plane. In the case of the configuration of FIG. 32, there are communication devices 700 arranged at the corners of a rectangle forming a communication network, and communication devices 700 arranged on the sides of the rectangle.

[0148] FIG. 33 is a conceptual diagram showing an example of the configuration of a light receiving device 70-1 of a communication device 700 arranged at a corner of a rectangle forming a communication network. The light receiving device 70-1 includes a plurality of light receiving units 74. The light receiving unit 74 is configured by combining the light receiving element array and a receiving circuit of each embodiment. The plurality of light receiving units 74 are arranged on one surface of a substrate 740 in which a portion where a ball lens 71 is arranged is hollowed out. The plurality of light receiving units 74 are arranged with their light receiving surfaces facing the ball lens 71. For example, each of the plurality of light receiving units 74 is fixed to the substrate 740 by a method such as screwing. The light receiving unit 74 can be removed from the substrate 740 and can be fixed to any position within the range of a unit arrangement region 745 of the substrate 740.

[0149] The communication devices 700 arranged at the corners of a rectangle forming the communication network receive spatial optical signals arriving from a direction of 90 degrees on a plane formed by the multiple communication devices 700. Therefore, the light receiving units 74 of the optical receiver 70-1 are concentrated and arranged within a 90-degree range so that the light receiving surfaces face the communication devices 700 that are the communication targets. The multiple light receiving units 74 may be arranged according to the direction of arrival of the spatial optical signals.

[0150] FIG. 34 is a conceptual diagram showing an example of the configuration of the optical receiver 70-2 of the communication device 700 arranged on the side of a rectangle forming a communication network. The optical receiver 70-2 includes a plurality of optical receiving units 74. The optical receiving unit 74 is configured by combining the optical receiving element array and the receiving circuit of each embodiment. The plurality of optical receiving units 74 are arranged on one surface of a substrate 740 in which a portion where the ball lens 71 is arranged is hollowed out. The plurality of optical receiving units 74 are arranged with the optical receiving surface facing the ball lens 71. For example, each of the plurality of optical receiving units 74 is fixed to the substrate 740 by a method such as screwing. With such a configuration, the communication devices 700 arranged on the sides and corners of the rectangle forming the communication network can be realized with the same specifications.

[0151] The communication devices 700 arranged on the sides of a rectangle forming a communication network receive spatial optical signals arriving from a direction of 180 degrees on a plane formed by the multiple communication devices 700. Therefore, the light receiving units 74 of the optical receiver 70-2 are arranged in a distributed manner within a range of 180 degrees so that the light receiving surfaces face the communication devices 700 with which they are to communicate. The multiple light receiving units 74 may be arranged according to the directions from which the spatial optical signals arrive.

[0152] 35 and 36 are conceptual diagrams showing how a spatial optical signal is incident on the optical receiver 70-2 of the communication device 700. FIG. 35 is a view of the optical receiver 70-2 looking down from a viewpoint above the optical receiver 70-2. FIG. 36 is a view of the optical receiver 70-2 looking from a viewpoint on the opposite side of the direction of arrival of the spatial optical signal. The multiple optical receiving units 74 constituting the communication device 700 are arranged in a dispersed manner. The spatial optical signal arrives with an irradiation range larger than the width of the optical receiving unit 74. Therefore, the optical receiving unit 74 arranged on the lower side of FIG. 35 can receive the spatial optical signal focused by the ball lens 71, although the arrival of the spatial optical signal is hindered by the optical receiving unit 74 arranged opposite to it.

[0153] [Application example 1] Next, an application example 1 of the communication device of this embodiment will be described with reference to the drawings. FIG. 37 is a conceptual diagram for explaining this application example. In this application example, a communication network is configured in which a plurality of communication devices 700-1 are arranged on the top of poles such as utility poles and street lights. The communication device 700-1 has a similar configuration to the communication device 700.

[0154] FIG. 38 is a conceptual diagram showing an example of the configuration of a communication device 700-1. The communication device 700-1 includes a photoreceiver 7101, a transmitter 7701, and a control device (not shown). In FIG. 38, the photoreceiver circuit and the control device are omitted. The communication device 700-1 has a cylindrical outer shape. The photoreceiver 7101 includes a ball lens 71, a photoreceiver unit 74-1, a substrate 740, and a light receiving unit 74-2. -1 , plate-like member 780, and color filter 790-1. Ball lens 71 is sandwiched between a pair of plate-like members 780 arranged above and below. The top and bottom of ball lens 71 are not used for transmitting and receiving spatial optical signals, so they may be formed flat so that they can be easily sandwiched by plate-like members 780. Light receiving unit 74-1 is arranged in an annular shape in accordance with the light collecting area of ​​ball lens 71 so that it can receive the spatial optical signal to be received. Light receiving unit 74 -1 is formed on the substrate 740-1. -1is connected to a control device (not shown) and a transmitter 7701 by conductor wires 78. A color filter 790-1 is arranged on the side of the cylindrical light receiver 7101. The color filter 790-1 removes unnecessary light and selectively transmits spatial optical signals used for communication. A pair of plate-like members 780 are arranged on the top and bottom surfaces of the cylindrical light receiver 7101. The pair of plate-like members sandwich the top and bottom of the ball lens 71. A light receiving unit 74 formed in an annular shape is arranged on the output side of the ball lens 71. -1 are arranged. The spatial optical signal incident on ball lens 71 via color filter 790-1 is focused by ball lens 71 onto light receiving unit 74-1. A control device (not shown) causes transmitter 7701 to transmit a spatial optical signal in response to the optical signal received by light receiving unit 74-1. Transmitter 7701 can be realized by the configuration shown in FIG. 31. Transmitter 7701 has a slit formed so that the spatial optical signal can be projected in 360-degree directions.

[0155] There are few obstacles on the top of poles such as utility poles and street lights. Therefore, the top of poles such as utility poles and street lights are suitable for installing the communication device 700-1. Furthermore, if the communication devices 700-1 are installed at the same height on the top of the pole, the direction of arrival of the spatial optical signal is limited to the horizontal direction, so that the light receiving area of ​​the light receiving unit 74-1 constituting the optical receiver 7101 can be reduced and the device can be simplified. A pair of communication devices 700-1 that exchange communication is arranged so that at least one communication device 700-1 receives the spatial optical signal transmitted from the other communication device 700-1. A pair of communication devices 700-1 may be arranged so that they transmit and receive spatial optical signals to each other. When a communication network of spatial optical signals is configured with multiple communication devices 700-1, the communication device 700-1 located in the middle may be arranged so as to relay the spatial optical signal transmitted from the other communication device 700-1 to another communication device 700-1.

[0156] According to this application example, communication using spatial optical signals is possible between a plurality of communication devices 700-1 installed on different poles. For example, in response to communication between the communication devices 700-1 installed on different poles, communication by wireless communication may be performed between the communication device 700-1 and a wireless device or base station installed in an automobile, a house, or the like. For example, the communication device 700-1 may be configured to be connected to the Internet via a communication cable or the like installed on the pole.

[0157] [Application example 2] Next, an application example 2 of the communication device of this embodiment will be described with reference to the drawings. FIG. 39 is a conceptual diagram for explaining this application example. The communication device of this application example transmits and receives a spatial optical signal to and from a drone 730 flying in the sky. In FIG. 39, a spatial optical signal is transmitted from the drone 730 flying in the sky to a communication device (receiver 7102) installed on the ground. In the following, it is assumed that the drone 730 can transmit and receive a spatial optical signal. The drone 730 can fly at any position in the sky. Therefore, the receiver 7102 is configured to be able to receive spatial optical signals arriving from all directions in the sky. In the example of FIG. 39, configurations of a transmitting device (transmitter), a receiving circuit, a control device, and the like are omitted.

[0158] The receiver 7102 includes a ball lens 71, a light receiving unit 74-2, and a color filter 790-2. The light receiving unit 74-2 is arranged in a ring shape with its light receiving surface facing the sky in accordance with the light collecting area of ​​the ball lens 71 so that it can receive the spatial optical signal transmitted from the drone 730. The upper side (incident side) of the ball lens 71 is covered with a spherical color filter 790-2. The color filter 790-2 removes unnecessary light and selectively transmits the spatial optical signal used for communication. The light receiving unit 74-2 formed along a spherical surface is arranged below (exiting side) the ball lens 71. The spatial optical signal incident on the ball lens 71 through the color filter 790-2 is collected by the ball lens 71 on the light receiving unit 74-2. For example, a control device (not shown) may cause a transmission device (not shown) to transmit a spatial optical signal toward the drone 730 in response to the optical signal received by the light receiving unit 74-2.

[0159] According to this application example, communication using spatial optical signals is possible between a drone 730 flying at any position in the sky and a communication device installed on the ground. For example, if the communication device is connected to the Internet, a system can be configured that utilizes information acquired by the drone 730 in real time.

[0160] As described above, the communication device of this embodiment includes a receiving device, a transmitting device, and a control device of any of the first to sixth embodiments. The transmitting device transmits a spatial optical signal in response to control by the control device. The control device receives a signal based on an optical signal received by the receiving device from another communication device. The control device executes processing in response to the received signal. The control device causes the transmitting device to transmit an optical signal in response to the executed processing. According to this embodiment, a communication device that transmits and receives optical signals can be realized.

[0161] According to one aspect of the present embodiment, a communication system includes a plurality of communication devices arranged to transmit and receive optical signals to and from each other. According to this aspect, a communication network that transmits and receives optical signals can be realized.

[0162] A receiving device according to one aspect of the present embodiment includes a ball lens and a plurality of light receiving units. The ball lens focuses an optical signal propagating through space. The plurality of light receiving units include a light receiving element array and a receiving circuit. The light receiving element array is composed of a plurality of light receiving elements that receive an optical signal focused by the ball lens. The light receiving element array outputs a signal derived from the optical signal received by the plurality of light receiving elements. The receiving circuit decodes the signal output from the light receiving element array. The plurality of light receiving units are arranged in a light focusing region of the ball lens with their light receiving surfaces facing the ball lens. For example, the plurality of light receiving units are arranged in accordance with the direction of arrival of the optical signal. The receiving device according to this aspect has a configuration in which a single ball lens is associated with a plurality of light receiving units. According to this aspect, a communication system in which communication devices can be flexibly arranged can be constructed by changing the orientation of the light receiving part of the light receiving unit according to the direction of arrival of the optical signal.

[0163] Eighth embodiment Next, a receiving device according to an eighth embodiment will be described with reference to the drawings. The receiving device of this embodiment has a simplified configuration of the receiving devices of the first to seventh embodiments. FIG. 40 is a conceptual diagram showing an example of the configuration of a receiving device 80 of this embodiment. The receiving device 80 includes a ball lens 81, a light receiving element array 83, and a receiving circuit 85.

[0164] The ball lens 81 focuses the optical signal propagating through space. The light receiving element array 83 is composed of a plurality of light receiving elements (not shown) that receive the optical signal focused by the ball lens 81. The light receiving element array 83 outputs a signal derived from the optical signal received by the plurality of light receiving elements. The receiving circuit 85 decodes the signal output from the light receiving element array.

[0165] The receiving device of this embodiment receives optical signals focused by a ball lens using multiple receiving elements. The ball lens evenly focuses spatial optical signals arriving from any direction onto the surrounding focusing area. Therefore, this embodiment has a simple configuration and can evenly receive optical signals arriving from various directions.

[0166] (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. 41 as an example. Note that the information processing device 90 in Fig. 41 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.

[0167] As shown in Fig. 41, 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. 41, 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.

[0168] The processor 91 loads a program stored in an auxiliary storage device 93 or the like into a 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 control and processing according to each embodiment.

[0169] 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.

[0170] 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.

[0171] 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.

[0172] 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.

[0173] 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.

[0174] 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.

[0175] 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. 41 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.

[0176] 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.

[0177] 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.

[0178] A part or all of the above-described embodiments can be described as, but is not limited to, the following supplementary notes. (Appendix 1) A ball lens that focuses an optical signal propagating through space; a light receiving element array including a plurality of light receiving elements that receive the optical signal collected by the ball lens, the light receiving element array outputting a signal derived from the optical signal received by the plurality of light receiving elements; a receiving circuit that decodes the signal output from the light receiving element array. (Appendix 2) The light receiving element array includes: 2. The receiving device according to claim 1, which is configured with a plurality of the light receiving elements arranged in an arc shape along the circumferential direction of the ball lens in the light collecting area of ​​the ball lens. (Appendix 3) 3. A receiving device as described in claim 1 or 2, comprising at least one of the photodetector arrays arranged in accordance with the direction of arrival of the optical signal. (Appendix 4) The light receiving element array includes: 4. The receiving device according to claim 1, wherein the receiving device is configured with a plurality of the light receiving elements arranged in a two-dimensional array along the circumferential direction of the ball lens in the light collecting region of the ball lens. (Appendix 5) The light receiving element array includes: 5. The receiving device according to claim 1, wherein the receiving device is configured with a plurality of the light receiving elements arranged in a ring shape around the ball lens in the light collecting area of ​​the ball lens. (Appendix 6) 6. The receiving device according to claim 1, further comprising an optical element disposed between the ball lens and the light receiving element array, the optical element guiding the optical signal focused by the ball lens toward a light receiving portion of any of the light receiving elements constituting the light receiving element array. (Appendix 7) The optical element is 7. The receiving device described in appendix 6, which is a cylindrical lens bent in an arc shape with its flat side facing outward along the circumferential direction of the ball lens, focuses the optical signal focused by the ball lens in a direction perpendicular to the arrangement direction of the light receiving element array, and guides the light to a light receiving portion of any of the light receiving elements that constitute the light receiving element array. (Appendix 8) The optical element is 7. The receiving device described in appendix 6, including a diffractive optical element bent into an arc shape along the circumferential direction of the ball lens, diffracting the optical signal collected by the ball lens in a direction perpendicular to the arrangement direction of the light receiving element array, and guiding the optical signal to a light receiving portion of any of the light receiving elements that constitute the light receiving element array. (Appendix 9) The optical element is 7. The receiving device described in claim 6, including a diffusion plate bent in an arc shape along a circumferential direction of the ball lens, diffusing the optical signal collected by the ball lens and guiding it to a light receiving portion of any of the light receiving elements constituting the light receiving element array. (Appendix 10) 10. A receiving device according to any one of claims 1 to 9, comprising a reflection structure disposed in an insensitive area of ​​a plurality of the light receiving elements and reflecting the optical signal emitted from the ball lens toward the light receiving portion of the light receiving element. (Appendix 11) A receiving device according to any one of Supplementary Notes 1 to 10; A transmitting device for transmitting an optical signal; A communication device comprising: a control device that receives a signal based on an optical signal received by the receiving device from another communication device, performs processing according to the received signal, and causes the transmitting device to transmit an optical signal according to the performed processing. (Appendix 12) A plurality of communication devices according to claim 11, A plurality of the communication devices, A communications system arranged to transmit and receive optical signals to and from each other. (Appendix 13) The receiving device includes: a ball lens that focuses the optical signal propagating through space; a plurality of light-receiving units each including a light-receiving element array configured with a plurality of light-receiving elements that receive the optical signal collected by the ball lens and that outputs a signal derived from the optical signal received by the plurality of light-receiving elements, and a receiving circuit that decodes the signal output from the light-receiving element array; The plurality of light receiving units include 13. The communication system of claim 12, wherein the light receiving surface faces the ball lens and is disposed in a light collecting area of ​​the ball lens. (Appendix 14) The plurality of light receiving units include 14. The communication system of claim 13, arranged in accordance with the direction of arrival of the optical signal. [Explanation of symbols]

[0179] 1, 2, 3, 4, 5, 6 Receiver 10, 20, 30, 40, 50, 60, 70 receiver 11, 21, 31, 41, 51, 61, 71 Ball Lens 13, 23, 33, 43, 53, 63 Photodetector array 15, 25, 35, 45, 55, 65 Receiver circuit 37, 47, 57 Optical elements 74 Light receiving unit 110 Light source 130, 330, 430, 530 board 131, 231, 331, 431, 531, 631 Light receiving element 132, 332, 432, 532, 632 Light receiving section 151 First Processing Circuit 152 Control circuit 153 Selector 155 Second Processing Circuit 200 Substrates 471 First Diffraction Section 472 Second Diffraction Section 473 Third Diffraction Section 474 4th Diffraction Section 475 Transparent part 571 First diffusion section 572 Second diffusion section 575, 576 Transparent part 636 Reflective structure 700 Communication Equipment 710 Receiving Equipment 740 Substrate 750 Control Unit 770 Transmitting Device 771 Light source 773 Spatial Light Modulator 7730 Modulation section

Claims

1. A ball lens that condenses an optical signal propagating in space, A light-receiving element array composed of a plurality of light-receiving elements that receive the optical signal condensed by the ball lens, and outputs a signal derived from the optical signal received by the plurality of light-receiving elements, A receiving circuit that decodes the signal output from the light-receiving element array, The light-receiving element array, A receiving device configured by a plurality of the light-receiving elements arranged in an annular shape so as to surround the periphery of the ball lens in the condensing region of the ball lens.

2. The receiving device according to claim 1, further comprising an optical element disposed between the ball lens and the light-receiving element array, and guiding the optical signal condensed by the ball lens toward a light-receiving portion of any one of the light-receiving elements constituting the light-receiving element array.

3. The optical element, Is a cylindrical lens bent in an arc shape with the plane side facing outward along the circumferential direction of the ball lens, condenses the optical signal condensed by the ball lens in a direction orthogonal to the arrangement direction of the light-receiving element array, and guides it to the light-receiving portion of any one of the light-receiving elements constituting the light-receiving element array. The receiving device according to claim 2.

4. The optical element, Includes a diffractive optical element bent in an arc shape along the circumferential direction of the ball lens, diffracts the optical signal condensed by the ball lens in a direction orthogonal to the arrangement direction of the light-receiving element array, and guides it to the light-receiving portion of any one of the light-receiving elements constituting the light-receiving element array. The receiving device according to claim 2.

5. The optical element, Includes a diffusion plate bent in an arc shape along the circumferential direction of the ball lens, diffuses the optical signal condensed by the ball lens, and guides it to the light-receiving portion of any one of the light-receiving elements constituting the light-receiving element array. The receiving device according to claim 2.

6. The receiving device according to any one of claims 1 to 5, further comprising a reflection structure disposed in an insensitive region of the plurality of light-receiving elements and reflecting the optical signal emitted from the ball lens toward the light-receiving portion of the light-receiving element.

7. The receiving device according to any one of claims 1 to 6, A transmitting device that transmits an optical signal, A communication device comprising: a control device that receives a signal based on an optical signal from another communication device received by the receiving device, executes processing according to the received signal, and causes the transmitting device to transmit an optical signal according to the executed processing.

8. A communication system comprising a plurality of the communication devices according to claim 7, wherein the plurality of communication devices are arranged to transmit and receive optical signals to and from each other.

9. The receiving device comprises a ball lens that condenses the optical signal propagating in space, a light-receiving element array configured by a plurality of light-receiving elements that receive the optical signal condensed by the ball lens and output a signal derived from the optical signal received by the plurality of light-receiving elements, and a receiving circuit that decodes the signal output from the light-receiving element array, and a plurality of light-receiving units having the same, wherein the plurality of light-receiving units are arranged in the light-condensing region of the ball lens with their light-receiving surfaces facing the ball lens, in accordance with the arrival direction of the optical signal, in the communication system according to claim 8.

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