Power transmitting device, power transmission control method, power receiving device, and power reception control method

Abstract

A power transmitting device according to the present technology comprises: a light emitting unit configured to be capable of emitting light at a first power for transferring electric power to a power receiving device and emitting light at a second power lower than the first power; and a power transmission side control unit that causes the light emitting unit to emit light at the second power, determines the presence or absence of an obstacle between the light emitting unit and the power receiving device on the basis of a determination result indicating whether low power light, which is the light emitted at the second power, has been received on the power receiving device side, and, on the condition that it has been determined that there is no obstacle, causes the light emitting unit to emit light at the first power in order to transfer electric power to the power receiving device.

Description

Power transmitting device, power transmission control method, power receiving device, and power receiving control method

[0001] The present technology relates to a power transmitting device, a power transmission control method, a power receiving device, and a power reception control method, and in particular to a technology for supplying power from a power transmitting device to a power receiving device by wireless power transmission.

[0002] There are known techniques for supplying power from a power transmitting device to a power receiving device by wireless power transmission. For example, Patent Document 1 listed below discloses a technique for supplying power to a power receiving device by wireless power transmission by irradiating the power receiving device with a beam such as an electromagnetic beam or a laser beam.

[0003] JP 2019-126199 A

[0004] When power is supplied from a power transmitting device to a power receiving device by wireless power transmission using light, if there is an obstacle between the light emitting unit for power transmission and the power receiving device, the obstacle will block the light for power transmission, making it impossible to supply power efficiently. Furthermore, if the obstacle is a person or an animal, the person or animal will be irradiated with the high-power light for power supply, which may reduce safety.

[0005] The present technology has been made in view of the above circumstances, and aims to realize a power supply system that can supply power efficiently and safely through wireless power transmission.

[0006] A power transmission device according to the present technology includes a light-emitting unit configured to emit light at a first power for transmitting power to a power receiving device and a second power lower than the first power, and a power transmission-side control unit configured to cause the light-emitting unit to emit light at the second power, determine the presence or absence of an obstacle between the light-emitting unit and the power receiving device based on a determination result of whether weak-power light emitted at the second power is received by the power receiving device, and, if it is determined that no obstacle is present, cause the light-emitting unit to emit light at the first power to transmit power to the power receiving device. With this configuration, if an obstacle is present between the light-emitting unit and the power receiving device, it is possible to prevent the light from being emitted at a high power for power supply, thereby improving power supply efficiency. Furthermore, it is possible to emit light at a high power for power supply only when it is determined that no obstacle is present, thereby preventing the high-power light from being irradiated on obstacles such as people or animals, thereby improving safety. In this case, the light emitted for determining the presence or absence of an obstacle is weak-power light, thereby suppressing a decrease in efficiency and safety.

[0007] A power receiving device according to the present technology includes a photoelectric conversion unit that performs photoelectric conversion, and a power receiving-side control unit that performs a light reception determination process that determines whether weak-power light, which is light at a second power that is lower than the first power, irradiated from a power transmitting device including a light emitting unit that is configured to be able to emit light at a first power for power transmission and light at a second power that is lower than the first power, is received by the power receiving device itself, and a determination information transmission process that transmits determination result information from the light reception determination process to the power transmitting device. Such a power receiving device enables the power transmitting device according to the present technology to obtain determination result information necessary for the power transmitting device to determine the presence or absence of an obstacle.

[0008] 1 is a diagram showing an example of the configuration of a power supply system including a power transmitting device and a power receiving device as an embodiment according to the present technology. FIG. 1 is a block diagram showing an example of the configuration of a power transmitting device as an embodiment. FIG. 2 is a block diagram showing an example of the configuration of a power receiving device as an embodiment. FIG. 3 is a diagram illustrating a schematic cross-sectional structure of a photoelectric conversion unit in an embodiment. FIG. 4 is a diagram showing an extracted configuration related to positioning in each of a power transmitting device and a power receiving device. FIG. 5 is an explanatory diagram of an example of a positioning calculation based on distance. FIG. 6 is an explanatory diagram of a power supply control method as an embodiment. FIG. 7 is a diagram showing the characteristics of the allowable amount of light irradiation to the cornea and skin with respect to the light wavelength. FIG. 8 is a flowchart showing an example of a specific processing procedure for realizing the power supply control method as an embodiment. FIG. 9 is a flowchart showing an example of the specific processing procedure for realizing the power supply control method as an embodiment, together with FIG. 9. FIG. 10 is a diagram showing an example of the configuration of a light emitting unit as a modified example. FIG. 11 is a diagram for explaining an example of the configuration of a power receiving device as a modified example.

[0009] Hereinafter, with reference to the accompanying drawings, embodiments according to the present technology will be described in the following order: <1. Power supply system of the embodiment> (1-1. Specific example of the system) (1-2. Configuration examples of the power transmitting device and the power receiving device) (1-3. Regarding positioning) <2. Power supply control method as an embodiment> <3. Processing procedure> <4. Modification example> <5. Summary of the embodiment> <6. The present technology>

[0010] 1 shows a configuration example of a power supply system including a power transmission device (power transmission device 1) and a power receiving device (power receiving device 2) according to an embodiment of the present technology. In the power supply system according to the present embodiment, the power transmission device 1 is configured as a lighting device. Specifically, the power transmission device 1 in this example is configured as a lighting device that is supported by a ceiling CL in a room and serves as a so-called ceiling light.

[0011] The power receiving device 2 is a device configured to be able to receive power wirelessly transmitted by the power transmitting device 1. In this example, the power receiving device 2 is configured as a portable information processing device such as a smartphone, a tablet terminal, or a notebook PC (personal computer). The power receiving device 2 in this example includes a battery (a battery 22 described below) that serves as its own operating power source, and is configured to be able to charge the battery based on the power received from the power transmitting device 1.

[0012] (1-2. Configuration Examples of Power Transmitting Device and Power Receiving Device) Configuration examples of the power transmitting device 1 and the power receiving device 2 will be described with reference to Figs. 2 and 3. Fig. 2 is a block diagram showing a configuration example of the power transmitting device 1. As shown in the figure, the power transmitting device 1 includes an illumination light source 10, a positioning communication unit 11, a light emitting unit 12, an actuator 13, a communication unit 14, and a power transmitting side control unit 15.

[0013] The illumination light source 10 is a light source that emits illumination light. A light source suitable for indoor lighting, such as an LED (Light Emitting Diode) or a fluorescent lamp, may be used as the illumination light source 10. The power transmitting side control unit 15 controls the turning on and off of the illumination light source 10.

[0014] The positioning communication unit 11 is provided to locate the position of the power receiving device 2. In this example, the position of the power receiving device 2 is determined based on the results of communication performed between the power transmitting device 1 and the power receiving device 2 using the UWB (Ultra Wide Band) system. Note that, regarding the positioning of the power receiving device 2, an example of a specific positioning method will be described later.

[0015] The light-emitting unit 12 emits light for wireless power transmission. The light-emitting unit 12 in this embodiment is configured to be capable of emitting light at a first power for transmitting power to the power receiving device 2 and emitting light at a second power lower than the first power. Specifically, the light-emitting unit 12 in this example uses a common light source for emitting light at the first power and emitting light at the second power, and is able to switch between emitting light at the first power and emitting light at the second power by changing the light-emitting power of the common light source.

[0016] In the following description, the light emitted by the light-emitting unit 12 at the first power is referred to as "strong power light," and the light emitted by the light-emitting unit 12 at the second power is referred to as "weak power light." The "first power" may also be referred to as "strong power," and the "second power" may also be referred to as "weak power."

[0017] In this example, a light source that emits infrared light is used as the light source of the light-emitting unit 12. Infrared light as used herein refers to light with a wavelength in the range of 780 nm to 2500 nm. Specifically, a light source that emits shortwave infrared light (SWIR) is used as the light source of the light-emitting unit 12. Shortwave infrared light as used herein refers to light with a wavelength in the range of 1000 nm to 2500 nm. More specifically, a light source that emits shortwave infrared light with a wavelength of 1400 nm or longer is used as the light source of the light-emitting unit 12 in this example.

[0018] A light emitting element such as a semiconductor laser or an LED may be used as the light source of the light emitting unit 12. In this example, a VCSEL (Vertical Cavity Surface Emitting Laser) is used as the light source of the light emitting unit 12.

[0019] In the light emitting unit 12, the power transmitting side control unit 15 controls the turning on and off of the light source and the light emission power.

[0020] The actuator 13 is an actuator that changes the direction of light emitted by the light-emitting unit 12. Although not shown in the figure, the power transmitting device 1 is provided with a mechanism for changing the direction of light emitted by the light-emitting unit 12 (hereinafter referred to as an "illumination direction variable mechanism"), and the actuator 13 is provided as an actuator that drives this illumination direction variable mechanism. The illumination direction variable mechanism may be configured as a mechanism that holds the light-emitting unit 12 so that the orientation of the light-emitting unit 12 can be freely changed. In this example, the illumination direction variable mechanism is configured to be able to change the orientation of the light-emitting unit 12 not only in one dimension but also in any two-dimensional direction. Therefore, by controlling the drive of the actuator 13, it is possible to irradiate light from the light-emitting unit 12 in any two-dimensional direction. The drive of the actuator 13 is controlled by the power transmitting side control unit 15.

[0021] By providing the above-mentioned actuator 13, even if the power receiving device 2 is a movable device such as a smartphone, it is possible to irradiate light for power supply toward the location where the power receiving device 2 is located, and the battery of the power receiving device 2 can be charged.

[0022] The power transmission side control unit 15 is configured with a microcomputer having, for example, a CPU (Central Processing Unit), a ROM (Read Only Memory), and a RAM (Random Access Memory), and the CPU executes processing in accordance with a program stored in the ROM or a program loaded from the ROM to the RAM, thereby performing overall control of the power transmission device 1. For example, the power transmission side control unit 15 controls turning on and off the illumination light source 10, the light emitting unit 12, and the actuator 13.

[0023] The power transmitting-side control unit 15 is connected to a communication unit 14. The communication unit 14 is a communication device for performing data communication with an external device, particularly the power receiving device 2 in this example. In this example, a communication device that performs data communication using a predetermined wireless communication method such as Bluetooth (registered trademark) is used. Note that the communication unit 14 may also be a communication device that has a function for connecting to a predetermined communication network such as the Internet or a LAN (Local Area Network). In this case, the power transmitting-side control unit 15 can perform data communication via the communication network with an external device other than the power receiving device 2, such as a predetermined server device.

[0024] Here, the power transmitting side control unit 15 in this example performs calculations to determine the position of the power receiving device 2 based on the communication results of the positioning communication unit 11, and a specific example of this calculation will be described later.

[0025] 3 is a block diagram showing an example of the internal configuration of the power receiving device 2. The power receiving device 2 includes a photoelectric conversion unit 20, a charging unit 21, a battery 22, a display panel 23, a display driving unit 24, a power receiving side control unit 25, a positioning communication unit 26, and a communication unit 27.

[0026] The photoelectric conversion unit 20 has one or more photoelectric conversion elements such as photodiodes, and performs photoelectric conversion on incident light.

[0027] Here, in the power receiving device 2 of this embodiment, the photoelectric conversion unit 20 is formed in a form that covers the display panel 23, which is a display panel that displays information, such as an LCD (Liquid Crystal Display) panel or an organic EL (Electro-Luminescence) panel.

[0028] A schematic cross-sectional structure of the photoelectric conversion unit 20 in this case is shown in Fig. 4. As shown in Fig. 4, the photoelectric conversion unit 20 in this case is formed by stacking, from the top, a glass layer L1, a transparent electrode layer L2, a buffer layer L3, a photoelectric conversion layer L4, a buffer layer L5, and a transparent electrode layer L6. Note that the "upper layer" here refers to the case where the light incident surface is the upward direction.

[0029] The uppermost glass layer L1 functions as a cover layer.

[0030] The photoelectric conversion layer L4 is formed by two-dimensionally arranging a plurality of photoelectric conversion elements (e.g., photodiodes). Buffer layers L3 and L5 formed above and below the photoelectric conversion layer L4 function as buffer layers between the photoelectric conversion layer L4 and transparent electrode layers L2 and L6 formed above and below them. The transparent electrode layers L2 and L6, which are provided to sandwich the photoelectric conversion layer L4, enable extraction of electric power obtained by photoelectric conversion in the photoelectric conversion layer L4.

[0031] 3, a charging unit 21 charges a battery 22 based on the power obtained by photoelectric conversion in a photoelectric conversion unit 20. The battery 22 is formed of a secondary battery such as a lithium ion battery.

[0032] The display drive unit 24 drives the display of the display panel 23. In this example, the display panel 23 is configured to be capable of displaying images, and the display drive unit 24 drives the display of the display panel 23 so that an image instructed by the power receiving-side control unit 25 is displayed on the display panel 23.

[0033] The positioning communication unit 26 is provided to perform positioning of the power receiving device 2 together with the positioning communication unit 11 in the power transmitting device 1. In this example, since the positioning communication unit 11 performs communication using the UWB system, the positioning communication unit 26 also performs UWB communication.

[0034] The power receiving-side control unit 25 is configured with, for example, a microcomputer having a CPU, ROM, and RAM, and performs overall control of the power receiving device 2 by the CPU executing processing in accordance with a program stored in the ROM or a program loaded from the ROM to the RAM. For example, it controls the display drive unit 24, such as instructing an image to be displayed on the display panel 23, and controls the charging operation of the battery 22 by the charging unit 21. In particular, the power receiving-side control unit 25 in this embodiment determines whether or not light of the second power described above has been received by the photoelectric conversion unit 20, which will be described later.

[0035] A communication unit 27 is connected to the power receiving side control unit 25. The communication unit 27 is a communication device for performing data communication with an external device, particularly the power transmitting device 1 in this example, and in this example, a communication device that performs data communication using the same wireless communication method as the communication unit 14 provided in the power transmitting device 1 is used. Note that the communication unit 27 may also be a communication device that has a function of connecting to a predetermined communication network such as the Internet or a LAN.

[0036] In this example, data communication between the power transmitting device 1 and the power receiving device 2 is enabled by the positioning communication unit 11 included in the power transmitting device 1 and the positioning communication unit 26 included in the power receiving device 2. Therefore, in order to realize data communication between the power transmitting device 1 and the power receiving device 2, it is not essential to provide the communication unit 14 and the communication unit 27.

[0037] 5 and 6, an example of a positioning method employed in the embodiment will be described. In the positioning method of this example, a distance between the power transmitter 1 and the power receiver 2 (specifically, the distance between the antenna At on the power transmitter 1 side and the antenna At on the power receiver 2 side) is measured based on the result of UWB communication between the power transmitter 1 and the power receiver 2, and the position of the power receiver 2 is identified based on the measured distance.

[0038] 5 illustrates extracted configurations related to positioning in the power transmitting device 1 and the power receiving device 2. Specifically, Fig. 5A illustrates an example of the internal configuration of the positioning communication unit 11 and the power transmitting side control unit 15 in the power transmitting device 1. Fig. 5B illustrates an example of the internal configuration of the positioning communication unit 26 in the power receiving device 2.

[0039] In this case, at least three communication and ranging units 11 a are provided in the positioning communication unit 11. Specifically, in this example, three communication and ranging units 11 a are provided in the positioning communication unit 11. On the other hand, one communication and ranging unit 11 a is provided in the positioning communication unit 26.

[0040] Each communication and ranging unit 11a has a communication antenna At, and performs UWB communication via the antenna At. Based on the communication results, the positioning communication unit 11 calculates the distance between its own antenna At and the antenna At of the communication and ranging unit 11a that is the communication partner. In order to distinguish between the antennas At of each communication and ranging unit 11a, the antennas At are denoted by the symbols "At1," "At2," and "At3" on the positioning communication unit 11 side.

[0041] When performing positioning, first, each communication and ranging unit 11a in the positioning communication unit 11 communicates with the communication and ranging unit 11a in the positioning communication unit 26 using the UWB system. This communication is performed in a time-division manner for each communication and ranging unit 11a in the positioning communication unit 11.

[0042] Each communication and ranging unit 11a in the positioning communication unit 11 performs a distance measurement calculation based on the results of communication with the communication and ranging unit 11a in the positioning communication unit 26. This distance measurement calculation is performed based on the arrival time of radio waves between the antennas At. Note that specific techniques for performing distance measurement based on the results of UWB communication are well known, and therefore will not be described here.

[0043] By performing the ranging calculations by each communication / ranging unit 11a in the positioning communication unit 11 as described above, the distance D (hereinafter referred to as distances D1, D2, and D3, respectively) between each of the antennas At1, At2, and At3 and the antenna At of the communication / ranging unit 11a in the positioning communication unit 26 is determined.

[0044] The power transmitting side control unit 15 performs a calculation (positioning calculation) to identify the position of the power receiving device 2 based on these distances D1, D2, and D3.

[0045] FIG. 6 is an explanatory diagram of an example of positioning calculation based on distances D1, D2, and D3. If the corresponding distances D1, D2, and D3 for antennas At1, At2, and At3 can be determined, the position of the power receiving device 2 can be determined by triangulation. Specifically, since the locations of antennas At1, At2, and At3 are known, the position of the power receiving device 2 can be determined as the intersections (marked with "x" in the figure) of three circles whose centers are the positions of antennas At1, At2, and At3 and whose radii are the corresponding distances D (D1, D2, and D3), as shown in FIG. 6A . However, in practice, it is rare for the three circles to intersect at a single point. That is, even if the circles do intersect, there are usually multiple intersections P. FIG. 6B shows a situation in which the three circles do not intersect at a single point, but rather form a total of six intersections P1, P2, P3, P4, P5, and P6. In this case, the position of the device to be positioned (i.e., the power receiving device 2) can be calculated based on the area formed by these intersections P. Specifically, one method is to identify three points that can be selected from the six intersections P, and then identify three points that form a triangle with the smallest area by connecting the points, in other words, three intersections P that form an overlapping portion of three circles (in the example shown in the figure, the three intersections P2, P4, and P5), and determine the center of gravity of the triangle formed by the three points as the position of the device to be positioned.

[0046] The positioning method described above is merely an example, and in this embodiment, the positioning method of the power receiving device 2 is not limited to a specific method. For example, although the example in which the positioning calculation is performed on the power transmitting device 1 side has been given, the positioning calculation can also be performed on the power receiving device 2 side. In this case, for example, the communication and ranging unit 11a in the positioning communication unit 26 calculates the distances D1, D2, and D3, and the power receiving-side control unit 25 performs the positioning calculation based on these distances D1, D2, and D3.

[0047] It is also possible to perform positioning calculations using a distance calculated based on the results of communication using a wireless communication method other than the UWB method, such as the BLE (Bluetooth Low Energy: Bluetooth is a registered trademark) method.

[0048] In the above example, a communication unit (positioning communication unit) that performs communication for positioning is provided in the power transmitting device 1, but the positioning communication unit may also be provided in an external device separate from the power transmitting device 1. In this case, positioning calculation for the position of the power receiving device 2 is performed in the external device or the power receiving device 2 based on the results of communication performed between the external device and the power receiving device 2 using a UWB system or the like. Therefore, in this case, the power transmitting device 1 does not need to perform positioning calculation itself, and it is sufficient to acquire the position information of the power receiving device 2 calculated in this manner in the external device or the power receiving device 2.

[0049] 2. Power Supply Control Method as an Embodiment Here, in the case where power is supplied from the power transmitting device 1 to the power receiving device 2 by wireless power transmission using light, as in the power supply system of the present embodiment, if an obstacle exists between the light-emitting unit 12 for power transmission and the power receiving device 2, the light for power transmission is blocked by the obstacle, making it impossible to supply power efficiently. Furthermore, if the obstacle is a person or an animal, the person or animal will be irradiated with high-power light for power supply, which may reduce safety.

[0050] Therefore, in this embodiment, in order to realize a power supply system that can supply power efficiently and safely by wireless power transmission, the following power supply control method is adopted.

[0051] 7A and 7B are explanatory diagrams of a power supply control method according to an embodiment. First, in the power supply system according to this embodiment, when power is supplied from the power transmitter 1 to the power receiver 2, the power receiver 2 is first located as indicated by <1> in Fig. 7A. Specifically, as described above, the power transmission-side control unit 15 performs a positioning calculation on the position of the power receiver 2 based on the result of wireless communication between the power transmitter 1 and the power receiver 2.

[0052] Next, based on the positioning result of the above <1>, the power transmitting side control unit 15 adjusts the direction of light emitted by the light emitting unit 12 (see <2> in FIG. 7B ). Specifically, the power transmitting side control unit 15 controls the actuator 13 so that the light emitted by the light emitting unit 12 is directed toward the position of the power receiving device 2 determined by the positioning calculation.

[0053] Furthermore, in response to the completion of the adjustment of <2> above, the power transmitting-side controller 15 causes the light emitting unit 12 to emit weak-power light (see <3> in FIG. 7B ). That is, the light emitting unit 12 emits weak-power light. As a result, weak-power light is irradiated toward the power receiving device 2.

[0054] Then, in response to performing the irradiation control of <3> above, the power transmitting device 1 determines whether or not there is an obstacle (see <4> in FIG. 7B ). To perform this obstacle determination, the power receiving device 2 first determines whether or not weak-power light has been received by the photoelectric conversion unit 20. The power transmitting device 1 performs the obstacle determination based on the result of the determination of whether or not weak-power light has been received by the power receiving device 2. That is, if weak-power light is received, it is estimated that there is no object blocking the weak-power light between the light emitting unit 12 and the power receiving device 2 (photoelectric conversion unit 20), and thus the determination result indicates that there is no obstacle. On the other hand, if weak-power light is not received, the determination result indicates that there is an obstacle.

[0055] If the above obstacle presence / absence determination determines that no obstacle is present, the power transmitting-side control unit 15 causes the light emitting unit 12 to emit high-power light (i.e., to transmit power), as indicated by <5> in FIG. 7C . On the other hand, if the power transmitting-side control unit 15 determines that an obstacle is present, the power transmitting-side control unit 15 stops the light emitting unit 12 from emitting high-power light. Thus, if an obstacle is present between the light emitting unit 12 and the power receiving device 2, high-power light emission for power supply is not performed, thereby improving power supply efficiency. Furthermore, high-power light emission for power supply is performed only when it is determined that no obstacle is present, thereby preventing high-power light from being irradiated on obstacles such as people or animals, thereby improving safety. In this case, low-power light is irradiated for the obstacle presence / absence determination, thereby minimizing degradation of efficiency and safety.

[0056] In the power supply control method of this embodiment, the power transmission side control unit 15 repeatedly performs, on a time axis, a process of determining the presence or absence of an obstacle by irradiating low-power light toward the power receiving device 2 based on the positioning result of the power receiving device 2, and a process of causing the light emitter 12 to emit high-power light in accordance with the result of the determination. As a result, if the power receiving device 2 is a movable device, it is possible to irradiate high-power light for power supply so as to track the power receiving device 2 if there is no obstacle between the power receiving device 2 and the power receiving device 2. Therefore, it is possible to realize a highly convenient power supply system that allows the power receiving device 2 to be freely moved when supplying power. Furthermore, while allowing the power receiving device 2 to be freely moved, it is possible to prevent the high-power light from being irradiated if an obstacle is present between the power receiving device 2 and the power receiving device 2, thereby ensuring safety.

[0057] Furthermore, in the power supply control method of this embodiment, when the power transmitting side control unit 15 determines that an obstacle is present, it waits until a re-positioning condition for the position of the power receiving device 2 is met, and once the re-positioning condition is met, it again performs positioning, controls the actuator 13 based on the positioning result, and determines whether or not an obstacle is present by irradiating weak-power light. As a result, even if it has been determined that an obstacle is present once, if the positional relationship between the power receiving device 2 and the obstacle subsequently changes and the obstacle disappears, it becomes possible to supply power to the power receiving device 2.

[0058] As mentioned above, in this example, the light emitting unit 12 emits short-wave infrared light. FIG. 8 shows the characteristics of the light irradiation tolerance to the cornea and skin with respect to the light wavelength. Specifically, in FIG. 8, the vertical axis represents the light emission power per unit area (W / m ２ The horizontal axis represents the wavelength of light, and the thick solid lines indicate the light exposure tolerance to the cornea and skin. In the figure, the thick dotted vertical lines represent wavelengths of 455 nm, 940 nm, 1350 nm, and 1550 nm, respectively.

[0059] As shown in the figure, it can be seen that the maximum light irradiation tolerance to the cornea and skin is reached at a wavelength of around 1400 nm. ２ That's about it.

[0060] In this example, in view of such characteristics, the light emitting power of the light emitting unit 12 is set to 10 mW or more as the strong power.

[0061] 9 and 10, a specific example of a processing procedure for realizing the power supply control method according to the embodiment described above will be described. In the flowcharts shown in Fig. 9 and 10, the processing shown as "power transmitting side" is executed by the CPU of the power transmitting side control unit 15 based on a program stored in the ROM or the like of the power transmitting side control unit 15, and the processing shown as "power receiving side" is executed by the CPU of the power receiving side control unit 25 based on a program stored in the ROM or the like of the power receiving side control unit 25. In the description of Fig. 9 and 10, the entity that executes the processing on the "power transmitting side" is referred to as the power transmitting side control unit 15, and the entity that executes the processing on the "power receiving side" is referred to as the power receiving side control unit 25.

[0062] 9 , first, in step S201, the power receiving-side control unit 25 waits until a charging-required state is reached. That is, the power receiving-side control unit 25 waits until a state requiring charging of the battery 22 is reached. The determination of whether or not the battery 22 is in a state requiring charging can be made, for example, by determining whether or not the remaining charge of the battery 22 is equal to or less than a predetermined amount.

[0063] If it is determined in step S201 that the power receiving side control unit 25 is in a state requiring charging, the process proceeds to step S202, where the power receiving side control unit 25 requests the power transmitting device 1 to transmit power.

[0064] The power transmission side control unit 15 waits for the power transmission request in step S101, and if a power transmission request is received, the process proceeds to step S102.

[0065] In step S102, the power transmitting-side control unit 15 performs a positioning process. That is, the positioning communication unit 11 communicates with the positioning communication unit 26 of the power receiving device 2, and performs distance measurement based on the communication result, and performs positioning calculation for the position of the power receiving device 2 based on the distance measurement result. Note that the specific method of the positioning calculation in this example has already been described, so a duplicate description will be avoided.

[0066] In step S103 following step S102, the power transmitting-side control unit 15 controls the direction of irradiation based on the position determined in step S102. Specifically, the power transmitting-side control unit 15 controls the actuator 13 so that the light from the light emitting unit 12 is irradiated toward the position of the power receiving device 2 determined in step S102.

[0067] In step S104 following step S103, the power transmitting-side control unit 15 issues a weak-power irradiation notification to the power receiving device 2. This weak-power irradiation notification is a prior notification of weak-power light irradiation. Then, in the following step S105, the power transmitting-side control unit 15 performs weak-power irradiation processing. That is, processing to cause the light emitting unit 12 to emit light at weak power.

[0068] In response to the power transmission request made in the previous step S202, the power receiving-side control unit 25 waits in step S203 for the weak power irradiation notification of step S104. If it is determined in step S203 that the weak power irradiation notification has been received, the power receiving-side control unit 25 proceeds to step S204 and determines whether weak power light has been received. This determination process may be performed, for example, as a determination process of whether the amount of light received by the photoelectric conversion unit 20 is equal to or greater than a predetermined threshold. The threshold value in this case should be determined taking into consideration the influence of noise light such as ambient light.

[0069] If it is determined in step S204 that weak-power light has not been received, the power-receiving-side control unit 25 proceeds to step S205 to determine whether a timeout has occurred. That is, it determines whether a predetermined time or more has elapsed since the timing of the above-described weak-power irradiation notification. If it is determined in step S205 that a timeout has not occurred, the power-receiving-side control unit 25 returns to step S204.

[0070] If it is determined in step S204 that weak power light has been received, the power receiving-side control unit 25 proceeds to step S206 and sends a light reception notification to the power transmitting device 1. On the other hand, if it is determined in step S205 that a timeout has occurred, the power receiving-side control unit 25 proceeds to step S208 and sends a no light reception notification to the power transmitting device 1.

[0071] In response to having performed the weak-power irradiation process in step S105 described above, the power transmitting-side control unit 15 performs a process of determining whether or not light has been received in step S106. Specifically, it determines whether the power receiving-side control unit 25 has issued a notification of light reception in step S206 or a notification of no light reception in step S208. This determination process in step S106 makes it possible to determine whether or not weak-power light has been received by the photoelectric conversion unit 20 of the power receiving device 2. In other words, this determination process in step S106 corresponds to a process of determining whether or not there is an obstacle.

[0072] If the light reception notification of step S206 is received and it is determined that light has been received in step S106, the power transmitting side control unit 15 proceeds to step S107 to perform high power irradiation processing, i.e., processing to cause the light emitting unit 12 to emit light at high power.

[0073] On the other hand, if the power transmitting-side control unit 15 determines in step S106 that no light is received because of the notification of no light reception in step S208, the power transmitting-side control unit 15 proceeds to step S108 to perform irradiation stop processing, i.e., processing to control the light emitting unit 12 to a non-light emitting state.

[0074] After executing the process of either step S107 or S108, the power transmitting side control unit 15 advances the process to step S109 shown in FIG.

[0075] In response to the notification of light reception in step S206, the power receiving-side control unit 25 proceeds to step S207 to perform charging start processing. That is, when the processing in step S207 is performed, high-power light is irradiated onto the photoelectric conversion unit 20, so the power receiving-side control unit 25 causes the charging unit 21 to start charging the battery 22 based on the power obtained by photoelectric conversion in the photoelectric conversion unit 20.

[0076] After executing the process of either step S207 or S208, the power receiving side control unit 25 advances the process to step S209 shown in FIG.

[0077] 10 , the power receiving-side control unit 25 determines whether charging is complete in step S209. That is, it determines whether a predetermined charging completion condition, such as the battery 22 being fully charged, is met. If it is determined in step S209 that charging is not complete, the power receiving-side control unit 25 proceeds to step S210, where it determines whether a relocation notification has been received from the power transmitting device 1. This relocation notification will be described later. Furthermore, if it is determined in step S210 that a relocation notification has not been received, the power receiving-side control unit 25 proceeds to step S211, where it determines whether a termination condition has been met, that is, whether a processing termination condition that has been previously set to terminate the series of processes shown in FIGS. 9 and 10 has been met, such as an operation input instructing termination of charging of the battery 22 by power supply from the power transmitting device 1 or the number of consecutive failures in receiving weak-power light reaching a predetermined number or more. If it is determined in step S211 that the processing termination condition is not met, the power receiving-side control unit 25 returns to step S209.

[0078] Of steps S209 to S211, if it is determined in step S209 that charging is complete, the power receiving-side control unit 25 proceeds to step S219 and notifies the power transmitting device 1 of the completion of charging.

[0079] If the power receiving-side control unit 25 determines in step S211 that the termination condition is met, the process proceeds to step S220 and notifies the power transmitting device 1 of the termination.

[0080] In step S109, the power transmitting-side control unit 15 determines whether a re-positioning condition is satisfied. The re-positioning condition defines a condition for re-performing the process of locating the position of the power receiving device 2 and irradiating weak-power light based on the positioning result. Specifically, in this example, it is defined that the position of the power receiving device 2 is to be located at a predetermined interval, for example, every few seconds. Therefore, in this case, the re-positioning condition is that the elapsed time since the previous positioning reaches a predetermined time.

[0081] If it is determined in step S109 that the elapsed time since the previous positioning has not reached the predetermined time and that the re-positioning condition is not satisfied, the power transmitting-side control unit 15 proceeds to step S110 to determine whether charging is complete. Specifically, it determines whether or not a charging completion notification has been received from the power receiving device 2 in the preceding step S219. If it is determined in step S110 that no charging completion notification has been received and charging is not complete, the power transmitting-side control unit 15 proceeds to step S111 to determine whether or not an end notification has been received. That is, it determines whether or not an end notification has been received from the power receiving device 2 in step S220. If it is determined in step S111 that no end notification has been received, the power transmitting-side control unit 15 returns to step S109.

[0082] Of the above steps S109 to S111, if it is determined in step S109 that the repositioning conditions are met, the power transmitting side control unit 15 proceeds to step S112, and performs a process of controlling the light emitting unit 12 to a non-light emitting state as an irradiation stop process, and then sends a repositioning notification to the power receiving device 2 in step S113.

[0083] Then, in step S114 following step S113, the power transmitting side control unit 15 performs positioning processing. This positioning processing is the same as the positioning processing in the previous step S102, so a duplicated description will be avoided. Furthermore, in step S115 following step S114, the power transmitting side control unit 15 controls the irradiation direction based on the positioning position. This processing in step S115 is the same as the previous step S103, so a duplicated description will be avoided.

[0084] In step S116 following step S115, the power transmitting-side controller 15 notifies the power receiving device 2 of weak power irradiation. Then, in subsequent step S117, the power transmitting-side controller 15 performs weak power irradiation processing (the same processing as step S105).

[0085] Here, when the relocation notification is sent in step S113, the power receiving device 2 obtains a determination result in the previous step S210 that the relocation notification has been sent. If the power receiving-side control unit 25 determines in step S210 that the relocation notification has been sent, the process proceeds to step S212, where it performs a charging stop process, i.e., a process of controlling the charging unit 21 to stop charging of the battery 22 based on the power obtained by the photoelectric conversion unit 20, and then in step S213, it waits for a weak-power irradiation notification from the power transmitting device 1. Here, the reason for stopping charging once in step S212 is that it is not possible to charge the battery 22 during the irradiation period of weak-power light.

[0086] In step S213, if a notification of weak power irradiation is received, the receiving-side control unit 25 proceeds to step S214, where it determines whether or not weak power light has been received (the same process as step S204), and if it determines that weak power light has not been received, it determines whether or not a timeout has occurred in step S215 (the same process as step S205), and if it determines that a timeout has not occurred, it returns to step S214.

[0087] If the power receiving-side control unit 25 determines in step S214 that weak power light has been received, the process proceeds to step S216, where it notifies the power transmitting device 1 that light has been received. If the power receiving-side control unit 25 determines in step S215 that time has expired, the power receiving-side control unit 25 proceeds to step S218, where it notifies the power transmitting device 1 that light has not been received.

[0088] In response to performing the weak power irradiation process in step S117, the power transmitting side control unit 15 performs a determination process in step S118 as to whether light has been received, that is, determines whether the power receiving side control unit 25 has notified the user of light reception in step S216 or notified the user of no light reception in step S218.

[0089] If the power transmitting-side control unit 15 determines in step S118 that light has been received based on the notification of light reception in step S216, the power transmitting-side control unit 15 proceeds to step S119 and performs high-power irradiation processing (the same processing as step S107). On the other hand, if the power transmitting-side control unit 15 determines in step S118 that light has not been received based on the notification of no light reception in step S218, the power transmitting-side control unit 15 proceeds to step S120 and performs irradiation stop processing, i.e., processing to control the light emitting unit 12 to a non-light emitting state.

[0090] After executing the process of either step S119 or S120, the power transmitting side control unit 15 returns to step S109.

[0091] In response to the light reception notification in the previous step S216, the power receiving-side control unit 25 advances the process to step S217 and performs charging start processing. As a result, after the power receiving device 2 has been relocated, if it can receive weak-power light from the power transmitting device 1 and in response supplies power using strong-power light from the power transmitting device 1, charging of the battery 22 is resumed.

[0092] The power receiving side control unit 25 returns to step S209 after executing the process of either step S217 or S218.

[0093] 10 described above, it is possible to repeatedly perform on the time axis the process of determining the presence or absence of an obstacle by irradiating weak-power light toward the power receiving device 2 based on the positioning result of the power receiving device 2, and the process of causing the light emitter 12 to emit light at high power depending on the result of the determination. Furthermore, if it is determined that an obstacle is present, the process waits thereafter until a re-positioning condition for the position of the power receiving device 2 is met, and once the re-positioning condition is met, the process again performs positioning, controls the actuator 13 based on the positioning result, and determines the presence or absence of an obstacle by irradiating weak-power light.

[0094] When the power transmitting-side control unit 15 determines in step S110 that charging is completed or when the power transmitting-side control unit 15 determines in step S111 that the termination notification has been received, the power transmitting-side control unit 15 proceeds to step S121 to perform irradiation stop processing, i.e., processing to control the light emitting unit 12 to a non-light emitting state. Then, the power transmitting-side control unit 15 ends the series of processing shown in Figs. 9 and 10 in response to performing the irradiation stop processing in step S121.

[0095] Furthermore, the power receiving-side control unit 25 ends the series of processes shown in FIGS. 9 and 10 in response to having executed either the charging completion notification process in step S219 or the termination notification process in step S220.

[0096] 4. Modifications Note that the embodiment is not limited to the specific example described above, and various modification configurations may be employed. For example, the above example illustrates an example in which the light-emitting unit 12 emits weak-power light and strong-power light from a common light source. However, it is also possible to use a light-emitting unit that includes a weak-power light-emitting element 12a that emits weak-power light and a strong-power light-emitting element 12b that emits strong-power light, as in the light-emitting unit 12A shown in FIG. 11 . In this case, the light-emitting state of weak power light and the light-emitting state of strong power light are switched by controlling the light-emitting power of either the weak-power light-emitting element 12a or the strong-power light-emitting element 12b, rather than controlling the light-emitting power of the common light-emitting element.

[0097] Although the above example has been given in which the power receiving device 2 is configured as a portable information processing device such as a smartphone, the power receiving device according to the present technology may also take the form of a charging stand-type device such as the power receiving device 2A illustrated in Fig. 12. Fig. 12 shows an example of the charging stand-type power receiving device 2A configured to be able to charge a portable information processing device 50 such as a smartphone or a tablet terminal.

[0098] In addition, although the above example shows a case where the light-emitting unit of the power transmission device according to the present technology emits infrared light, the light-emitting unit may also emit light in a wavelength band other than infrared light.

[0099] In addition, although the above example gives an example in which the determination of whether weak power light is received is performed by determining whether light is received by the photoelectric conversion unit 20, it is also possible to determine whether weak power light is received by providing a light receiving element (photoelectric conversion element) other than the photoelectric conversion unit 20 in the power receiving device 2, and performing a process to determine whether light is received by that light receiving element.

[0100] 5. Summary of the Embodiments As described above, the power transmission device (1) according to the embodiment includes a light-emitting unit (12, 12A) configured to emit light at a first power for transmitting power to a power receiving device (2) and a second power lower than the first power, and a power transmission-side control unit (15) that causes the light-emitting unit to emit light at the second power, determines the presence or absence of an obstacle between the light-emitting unit and the power receiving device based on a determination result of whether weak-power light emitted at the second power is received by the power receiving device, and, if it is determined that no obstacle is present, causes the light-emitting unit to emit light at the first power to transmit power to the power receiving device. This configuration prevents the light-emitting unit from emitting light at a high power for power supply when an obstacle is present between the light-emitting unit and the power receiving device, thereby improving power supply efficiency. Furthermore, the light-emitting unit can emit light at a high power for power supply only when it is determined that no obstacle is present, preventing high-power light from being irradiated on obstacles such as people or animals, thereby improving safety. At this time, the light emitted for determining the presence or absence of an obstacle is low-power light, which prevents a decrease in efficiency and safety. Therefore, according to this embodiment, it is possible to realize a power supply system that can supply power via wireless power transmission efficiently and safely.

[0101] In the power transmission device according to the embodiment, the light emitting unit emits infrared light. By using light in the invisible light band as the light for power supply, it is possible to prevent the weak power light for determining the presence or absence of an obstacle and the light for power supply from being visible, thereby preventing visual annoyance.

[0102] Furthermore, in the power transmission device according to the embodiment, the light emitting unit emits short-wave infrared light. Short-wave infrared light tends to have a high light transmission efficiency in air. Therefore, by using short-wave infrared light as the light for power supply, it is possible to improve the power supply efficiency.

[0103] Furthermore, in the power transmission device according to the embodiment, the light emitting unit emits short-wave infrared light with a wavelength of 1400 nm or more. Short-wave infrared light with a wavelength of 1400 nm or more is in the so-called eye-safe band, which is not absorbed by the retina. Therefore, safety can be improved.

[0104] In the power transmitting device according to the embodiment, the first power is set to 10 mW or more. By setting an appropriate power as the first power, it is possible to ensure that power is supplied to the power receiving device appropriately.

[0105] Furthermore, in the power transmission device according to the embodiment, the light source of the light emitting unit is a vertical cavity surface emitting laser, which improves the light emitting efficiency of the light emitting unit and improves the efficiency of power supply.

[0106] Furthermore, the power transmitting device according to the embodiment includes an actuator (13) that changes the direction of light emitted by the light emitting unit. By enabling the light emitting unit to change the direction of light emitted, power can be supplied even when the power receiving device is a movable device, such as a portable device. Therefore, a highly convenient power supply system can be realized that allows the power receiving device to be moved when supplying power.

[0107] In the power transmitting device according to the embodiment, when the light emitting unit emits low-power light to determine whether an obstacle is present, the power transmitting control unit controls the actuator to irradiate the low-power light toward the power receiving device based on the positioning result of the power receiving device. This makes it possible to appropriately determine whether an obstacle is present using the low-power light even when the power receiving device is a movable device.

[0108] Furthermore, in the power transmitting device according to the embodiment, the power transmitting side control unit repeatedly performs, on a time axis, a process of determining whether an obstacle is present by irradiating weak-power light toward the power receiving device based on the positioning result, and a process of causing the light emitting unit to emit light at a first power in accordance with the result of the determination. As a result, if the power receiving device is a movable device, if there is no obstacle between the power receiving device and the power receiving device, it is possible to irradiate light at the first power so as to track the power receiving device. Therefore, it is possible to realize a highly convenient power supply system that allows the power receiving device to be freely moved when supplying power. Furthermore, while allowing the power receiving device to be freely moved, it is possible to prevent light at the first power from being emitted if an obstacle is present between the power receiving device and the power receiving device, thereby ensuring safety.

[0109] In a power transmission control method according to an embodiment, a power transmitting device causes a light emitting unit configured to be capable of emitting light at a first power for transmitting power to a power receiving device and at a second power lower than the first power to emit light at the second power, determines whether or not an obstacle exists between the light emitting unit and the power receiving device based on a determination result of whether or not weak-power light, which is light emitted at the second power, is received by the power receiving device, and, if it is determined that no obstacle exists, causes the light emitting unit to emit light at the first power to transmit power to the power receiving device. This power transmission control method can also achieve the same functions and effects as those of the power transmitting device according to the above-described embodiment.

[0110] The power receiving device (2) according to the embodiment includes a photoelectric conversion unit (20) that performs photoelectric conversion, a power transmitting device including a light emitting unit configured to emit light at a first power for power transmission and light at a second power lower than the first power, and a power receiving-side control unit that performs a light reception determination process that determines whether the power receiving device receives weak-power light, which is light at a second power, emitted from the power transmitting device, and a determination information transmission process that transmits determination result information from the light reception determination process to the power transmitting device. This power receiving device allows the power transmitting device of this embodiment to obtain the determination result information necessary for determining the presence or absence of an obstacle. Therefore, a power supply system that can efficiently and safely supply power via wireless power transmission can be realized.

[0111] In addition, the power receiving device according to the embodiment includes a display panel (23) that displays information, and the photoelectric conversion unit is formed in a form that covers the display panel. By forming the photoelectric conversion unit in a form that covers the display panel as described above, it becomes easier to secure the area of ​​the photoelectric conversion region, and power receiving efficiency can be improved.

[0112] In the power receiving control method according to the embodiment, a power receiving device including a photoelectric conversion unit that performs photoelectric conversion performs a light reception determination process to determine whether weak-power light, which is light at a second power that is irradiated from a power transmitting device including a light emitting unit that is configured to be able to emit light at a first power for power transmission and light at a second power that is lower than the first power, has been received by the power receiving device itself, and a determination information transmission process to transmit information on the determination result of the light reception determination process to the power transmitting device. This power receiving control method can also achieve the same functions and effects as the power receiving device according to the embodiment described above.

[0113] The effects described in this specification are merely examples and are not limiting, and other effects may also be present.

[0114] <6. Present Technology> The present technology may also have the following configurations. (1) A power transmission device including: a light-emitting unit configured to be able to emit light at a first power for transmitting power to a power receiving device and at a second power lower than the first power; and a power transmission-side control unit that causes the light-emitting unit to emit light at the second power, determines the presence or absence of an obstacle between the light-emitting unit and the power receiving device based on a determination result of whether weak-power light, which is light emitted at the second power, is received by the power receiving device, and, on the condition that it is determined that no obstacle is present, causes the light-emitting unit to emit light at the first power to transmit power to the power receiving device. (2) The power transmission device described in (1), in which the light-emitting unit emits infrared light. (3) The power transmission device described in (2), in which the light-emitting unit emits shortwave infrared light. (4) The power transmission device described in (3), in which the light-emitting unit emits shortwave infrared light having a wavelength of 1400 nm or more. (5) The power transmitting device according to any one of (2) to (4), wherein the first power is 10 mW or more. (6) The power transmitting device according to any one of (1) to (5), wherein a light source of the light emitting unit is a vertical cavity surface emitting laser. (7) The power transmitting device according to any one of (1) to (6), further comprising an actuator that changes the direction of light irradiation by the light emitting unit. (8) The power transmitting device according to (7), wherein the power transmitting side control unit, when making the light emitting unit emit the weak power light to determine the presence or absence of the obstacle, controls the actuator so that the weak power light is irradiated toward the power receiving device based on a positioning result of the power receiving device. (9) The power transmitting device according to (8), wherein the power transmitting side control unit repeatedly performs, on a time axis, a process of determining the presence or absence of the obstacle by irradiating the weak power light toward the power receiving device based on the positioning result, and a process of making the light emitting unit emit light at the first power in accordance with the result of the determination.(10) A power transmission control method in which a power transmitting device causes a light emitting unit configured to be capable of emitting light at a first power for transmitting power to a power receiving device and at a second power lower than the first power to emit light at the second power, determines whether or not an obstacle is present between the light emitting unit and the power receiving device based on a determination result of whether or not weak power light, which is light emitted at the second power, is received by the power receiving device, and, on the condition that it is determined that no obstacle is present, causes the light emitting unit to emit light at the first power to transmit power to the power receiving device. (11) A power receiving device comprising: a photoelectric conversion unit that performs photoelectric conversion, and a power receiving-side control unit that performs a light reception determination process that determines whether or not weak power light, which is light at the second power, irradiated from a power transmitting device having a light emitting unit configured to be capable of emitting light at a first power for transmitting power and at a second power lower than the first power, is received by the power receiving device itself, and a determination information transmission process that is a process of transmitting determination result information of the light reception determination process to the power transmitting device. (12) The power receiving device according to (11), further comprising: a display panel that displays information, wherein the photoelectric conversion unit is formed in a form that covers the display panel. (13) A power receiving control method, further comprising: a power receiving device including a photoelectric conversion unit that performs photoelectric conversion; performing a light reception determination process that determines whether weak-power light, which is light at a second power that is lower than the first power and is irradiated from a power transmitting device including a light emitting unit that is configured to be able to emit light at a first power for power transmission and light at the second power, has been received by the power receiving device; and a determination information transmission process that transmits determination result information from the light reception determination process to the power transmitting device.

[0115] REFERENCE SIGNS LIST 1 Power transmitting device 2, 2A Power receiving device CL Ceiling 10 Light source for illumination 11 Positioning communication section 12, 12A Light emitting section 13 Actuator 14 Communication section 15 Power transmitting side control section 20 Photoelectric conversion section 21 Charging section 22 Battery 23 Display panel 24 Display driving section 25 Power receiving side control section 26 Positioning communication section 27 Communication section 11a Communication and ranging section 12a Weak power light emitting element 12b Strong power light emitting element

Claims

1. A power transmission device comprising: a light-emitting unit configured to be capable of emitting light at a first power for transmitting power to a power receiving device, and emitting light at a second power lower than the first power; and a power transmission side control unit that causes the light-emitting unit to emit light at the second power, and determines whether or not there is an obstacle between the light-emitting unit and the power receiving device based on a determination result of whether or not weak power light, which is light emitted at the second power, is received by the power receiving device, and, on the condition that it is determined that there is no obstacle, causes the light-emitting unit to emit light at the first power and transmit power to the power receiving device.

2. The power transmitting device according to claim 1, wherein the light emitting unit emits infrared light.

3. The power transmitting device according to claim 2, wherein the light emitting unit emits shortwave infrared light.

4. The power transmitting device according to claim 3, wherein the light emitting unit emits shortwave infrared light having a wavelength of 1400 nm or more.

5. The power transmitting device according to claim 2, wherein the first power is 10 mW or more.

6. The power transmitting device according to claim 1, wherein the light source of the light emitting section is a vertical cavity surface emitting laser.

7. The power transmitting device according to claim 1, further comprising an actuator for changing the direction of light irradiation by the light emitting unit.

8. The power transmitting device according to claim 7, wherein the power transmitting side control unit, when causing the light emitting unit to emit the weak power light to determine the presence or absence of an obstacle, controls the actuator so that the weak power light is irradiated toward the power receiving device based on the positioning results of the power receiving device.

9. The power transmitting device according to claim 8, wherein the power transmitting control unit repeatedly performs, on a time axis, a process of determining whether or not there is an obstacle by irradiating the weak power light toward the power receiving device based on the positioning result, and a process of causing the light emitting unit to emit light at the first power depending on the result of the determination.

10. A power transmission control method in which a power transmitting device causes a light emitting unit configured to be capable of emitting light at a first power for transmitting power to a power receiving device and at a second power lower than the first power to emit light at the second power, determines whether or not there is an obstacle between the light emitting unit and the power receiving device based on a determination result of whether or not weak power light, which is light emitted at the second power, is received by the power receiving device, and, on the condition that it is determined that there is no obstacle, causes the light emitting unit to emit light at the first power to transmit power to the power receiving device.

11. A power receiving device comprising: a photoelectric conversion unit which performs photoelectric conversion; and a power receiving side control unit which performs a light reception determination process which determines whether weak power light, which is light at a second power irradiated from a power transmitting device having a light emitting unit configured to be capable of emitting light at a first power for power transmission and light at a second power lower than the first power, has been received by the power receiving device; and a determination information transmission process which is a process of transmitting determination result information from the light reception determination process to the power transmitting device.

12. A power receiving device according to claim 11, further comprising a display panel for displaying information, the photoelectric conversion unit being formed in a form that covers the display panel.

13. A power receiving control method in which a power receiving device having a photoelectric conversion unit that performs photoelectric conversion performs a light reception determination process for determining whether or not weak-power light, which is light at a second power irradiated from a power transmitting device having a light emitting unit configured to be capable of emitting light at a first power for power transmission and light at a second power lower than the first power, has been received by the power receiving device itself, and a determination information transmission process for transmitting determination result information from the light reception determination process to the power transmitting device.

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