Power transmission device and method performed by the power transmission device

Abstract

To provide a power transmission device having a plurality of power transmission coils, capable of performing an appropriate control in regard to a radio power transmission.SOLUTION: A power transmission device includes: a plurality of coils; transmission means of transmitting a plurality of Pings via the plurality of coils; acquisition means of acquiring identification information from one or more power reception device; and power transmission means of transmitting a power in radio to a first power reception device that is a first coil contained in the plurality of coils via a first coil corresponded to the first power reception device contained in a plurality of power reception devices in the case where there are the plurality of power reception devices, and of transmitting a power in radio to a second power reception device via a second coil that is contained in the plurality of coils, the second coil being corresponded to a second power reception device contained in the plurality of power reception devices . The transmission means does not transmit a Ping for detecting the power reception device via the coil that is existed at a neighbor of the first coil during a power transmission in radio to the first power reception device via the first coil.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present disclosure relates to control of wireless power transmission. [Background technology]

[0002] In recent years, technological development of wireless power transmission systems has been widely carried out, and power transmitting devices and power receiving devices that comply with standards (hereinafter referred to as WPC standards) established by the Wireless Power Consortium (WPC), a standardization organization for wireless charging standards, have been provided.

[0003] Moreover, Patent Document 1 discloses a power transmitting device having a plurality of power transmitting coils. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2018-186699 A Summary of the Invention [Problem to be solved by the invention]

[0005] Patent Document 1 discloses the arrangement of multiple power transmitting coils, but does not consider a method for controlling wireless power transmission of a power transmitting device having multiple power transmitting coils.

[0006] An object of the present disclosure is to provide a technique capable of performing appropriate control over wireless power transmission in a power transmitting device having multiple power transmitting coils. [Means for solving the problem]

[0007] The power transmission device of the present disclosure comprises a plurality of coils, a transmission means for transmitting a plurality of Pings via the plurality of coils, an acquisition means for acquiring identification information from one or more power receiving devices, and a power transmission means for, when the plurality of power receiving devices are present, wirelessly transmitting power to a first power receiving device via a first coil included in the plurality of coils that corresponds to a first power receiving device included in the plurality of power receiving devices, and wirelessly transmitting power to a second power receiving device via a second coil included in the plurality of coils that corresponds to a second power receiving device included in the plurality of power receiving devices, wherein the transmission means does not transmit a Ping for detecting the power receiving device via a coil in the vicinity of the first coil during wireless power transmission to the first power receiving device via the first coil. Effect of the Invention

[0008] According to the present disclosure, it is possible to perform appropriate control regarding wireless power transmission in a power transmitting device having a plurality of power transmitting coils. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 is a diagram for explaining a configuration of a wireless power transmission system. [Diagram 2] 2 is a diagram illustrating an example of a functional configuration of a power transmitting device. FIG. [Diagram 3] 2 is a diagram illustrating an example of a functional configuration of a power receiving device. FIG. [Figure 4] 2A and 2B are diagrams for explaining an example of the configuration of a power transmission coil group included in a power transmission device. [Diagram 5] 1 is a diagram for explaining processing performed by a power transmitting device and a power receiving device that comply with the WPC standard. [Figure 6] 1A and 1B are diagrams for explaining a process performed by a power transmission device having a plurality of power transmission coils. [Figure 7] 4 is a flowchart for explaining a process performed by the power transmitting device according to the first embodiment. [Figure 8]4 is a sequence diagram for explaining processing performed by a power transmitting device and a power receiving device in the first embodiment. FIG. [Figure 9] 11 is a sequence diagram for explaining processing performed by a power transmitting device and a power receiving device in the second embodiment. FIG. [Figure 10] 10 is a flowchart for explaining a process performed by a power transmitting device according to the second embodiment. [Figure 11] 2A to 2C are diagrams illustrating an example of a configuration of a power transmitting device and a power transmitting coil group included in the power transmitting device. [Figure 12] 11 is a flowchart for explaining a process performed by a power transmitting device according to a third embodiment. [Figure 13] FIG. 11 is a sequence diagram for explaining processing performed by a power transmitting device and a power receiving device in the third embodiment. [Figure 14] 4 is a diagram illustrating an example of an arrangement of a power transmitting coil group and a power receiving device. FIG. [Figure 15] 13 is a flowchart for explaining a process performed by a power transmitting device according to a fourth embodiment. [Figure 16] 4 is a diagram showing timing of power transmission and detection signal transmission performed by the power transmitting device. FIG. [Figure 17] FIG. 2 is a diagram illustrating an example of an arrangement of power receiving devices. [Figure 18] 13 is a flowchart for explaining a process performed by a power transmitting device according to a fifth embodiment. [Figure 19] FIG. 13 is a sequence diagram for explaining processing performed by a power transmitting device and a power receiving device in a fifth embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. Note that the components described in the following embodiments are examples of the embodiments of the present disclosure, and the present disclosure is not limited to them.

[0011] (Embodiment 1) [System configuration] FIG. 1 shows an example of a wireless power transmission system according to this embodiment. The wireless power transmission system in this embodiment includes a power transmitting device 100 and power receiving devices (a first power receiving device 101a and a second power receiving device 101b). The power transmitting device 100 in this embodiment has a function of simultaneously charging the first power receiving device 101a and the second power receiving device 101b placed within a range in which the power transmitting device 100 can transmit power. Note that FIG. 1 shows an example in which two power receiving devices exist on the power transmitting device, but this is not limiting. For example, the power transmitting device 100 may charge only one device. Furthermore, the power transmitting device 100 may be configured to be capable of charging three or more power receiving devices simultaneously.

[0012] In this embodiment, the state in which the power receiving device is placed includes the following states. The state in which the power receiving device is placed includes, for example, the case in which the power receiving device is placed (installed) on a surface within the range in which the power transmitting device can transmit power. However, the method described in this embodiment is applicable at least in a state in which the power receiving device is included within the range in which the power transmitting device can transmit power, and may be, for example, a state in which the power receiving device and the power transmitting device are not in contact with each other. Furthermore, the surface on which the power receiving device can be placed may not only be a horizontal surface, but also a vertical surface or an inclined surface.

[0013] [Device configuration] 2 is a block diagram for explaining a functional configuration of the power transmitting device 100. The power transmitting device 100 includes a control unit 201, a power supply unit 202, a first power transmitting circuit 203, a first communication unit 204, a second power transmitting circuit 205, a second communication unit 206, a memory 207, a selection unit 208, and a power transmitting coil group 210. The power transmitting coil group 210 includes a plurality of power transmitting coils 209a to 209n. The number of the power transmitting coils 209a to 209b can be two or more. In the following description, the power transmitting coils 209a to 209b will be simply referred to as the power transmitting coil 209 unless there is a particular need to distinguish them. Each processing unit will be described below.

[0014] The control unit 201 performs overall control of the power transmitting device 100. The control unit 201 includes one or more processors, such as a central processing unit (CPU) or a micro processing unit (MPU). The control unit 201 may include an application specific integrated circuit (ASIC) or a field programmable gate array (FPGA) configured to execute the processes described below.

[0015] The power supply unit 202 is a power supply that supplies power for operating the control unit 201, the first power transmitting circuit 203, and the second power transmitting circuit 205. The power supply unit 202 can be, for example, a wired power receiving circuit that receives power from a commercial power source, a battery, or the like.

[0016] The first power transmitting circuit 203 and the second power transmitting circuit 205 generate an AC voltage and an AC current in any power transmitting coil 209 included in a power transmitting coil group 210 described later. The first power transmitting circuit 203 and the second power transmitting circuit 205 convert a DC voltage supplied by the power supply unit 202 into an AC voltage using a switching circuit in a half-bridge or full-bridge configuration using a FET (Field Effect Transistor), for example. In this case, the power transmitting circuit 203 includes a gate driver that controls ON / OFF of the FET.

[0017] The first communication unit 204 performs control communication of wireless power transmission based on a standard (hereinafter referred to as the WPC standard) established by the Wireless Power Consortium (WPC) with a communication unit of the power receiving device described later. In this embodiment, the first communication unit 204 load-modulates the AC voltage or AC current generated by the first power transmitting circuit 203, and transmits the communication data to the power receiving device by superimposing the communication data on the power to be transmitted. The first communication unit 204 also receives the communication data transmitted from the power receiving device by demodulating the AC voltage or AC current modulated by the communication unit of the power receiving device described later. This process realizes the control communication. The second communication unit 206, like the first communication unit 204, load-modulates or demodulates the AC voltage or AC current generated by the second power transmitting circuit 205, and transmits and receives the communication data, thereby realizing the control communication.

[0018] The memory 207 stores the power transmitting device 100 and each element and the overall state of the wireless power transmission system.

[0019] The power transmission coil group 210 has a plurality of power transmission coils 209. Any one or more of the power transmission coils 209 are connected to the first power transmission circuit 203 or the second power transmission circuit 205. The selection unit 208 connects any one or more of the power transmission coils 209 included in the power transmission coil group 210 to the first power transmission circuit 203 or the second power transmission circuit 205. The selection unit 208 connects the first power transmission circuit 203 to any one or more of the power transmission coils 209, and connects the second power transmission circuit 205 to the other one or more of the power transmission coils 209. The control unit 201 controls the selection unit 208 to determine which of the power transmission coils 209 are to be connected to the first power transmission circuit 203 and the second power transmission circuit 205. The selection unit 208 switches the connections between the first power transmission circuit 203 and the second power transmission circuit 205 and the power transmission coils in accordance with the control by the control unit 201. The control of the connections between the first power transmitting circuit 203 and the second power transmitting circuit 205 and the power transmitting coil will be described later.

[0020] In this embodiment, the first power transmitting circuit 203 and the second power transmitting circuit 205 can operate independently, and can each transmit power for charging to a maximum of one power receiving device at the same time. In other words, the power transmitting device 100 can charge a maximum of two power receiving devices simultaneously.

[0021] 2, the control unit 201, the power supply unit 202, the first power transmitting circuit 203, the first communication unit 204, the second power transmitting circuit 205, the second communication unit 206, the memory 207, the selection unit 208, and the power transmitting coil group 210 are each depicted as separate blocks, but are not limited to this. Two or more of the above blocks may be integrated into one chip or the like. Also, one block may be divided into multiple blocks.

[0022] 3 is a block diagram for explaining the functional configuration of the first power receiving device 101a and the second power receiving device 101b. The first power receiving device 101a and the second power receiving device 101b in this embodiment have the same functional configuration, and when there is no need to particularly distinguish them, they are simply referred to as the power receiving device 101. However, the first power receiving device 101a and the second power receiving device 101b may be devices of different types. The power receiving device 101 has a control unit 301, a power receiving unit 302, a communication unit 303, a memory 304, a power receiving coil 305, a charging unit 306, and a battery 307. Each processing unit will be described below.

[0023] The control unit 301 controls the entire power receiving device 101. The control unit 301 includes one or more processors, such as a central processing unit (CPU) or a micro processing unit (MPU). The control unit 201 may include an application specific integrated circuit (ASIC) or a field programmable gate array (FPGA) configured to execute the processes described below. The control unit 301 is activated by receiving a predetermined power from the power transmitting device 100.

[0024] The power receiving unit 302 acquires an AC voltage and an AC current generated in the power receiving coil 305 by power transmission from any one or more power transmitting coils 209 included in the power transmitting coil group 210. The power receiving unit 302 also converts the acquired AC voltage and AC current into a DC voltage and a DC current for operating the control unit 301, the charging unit 306, etc.

[0025] The communication unit 303 performs control communication for wireless power transmission based on the WPC standard with the first communication unit 204 or the second communication unit 206 of the power transmitting device 100. The communication unit 303 transmits communication data to the power transmitting device 100 by load modulating the AC voltage and AC current received by the power receiving coil 305. The communication unit 303 also receives communication data transmitted from the power transmitting device 100 by demodulating the AC voltage and AC current modulated by the power transmitting device 100.

[0026] The charging unit 306 charges the battery 307 using the DC voltage and DC current supplied from the power receiving unit 302. The memory 304 stores the state of each element of the power receiving device 101 and the wireless power transmission system, as well as the overall state.

[0027] 3, the control unit 301, the power receiving unit 302, the communication unit 303, the memory 304, and the charging unit 306 are each depicted as separate blocks, but are not limited to this. Two or more of the above blocks may be integrated into one chip or the like. Also, one block may be divided into multiple blocks.

[0028] The power receiving device 101 and the power transmitting device 100 may have a function of executing an application other than wireless charging. An example of the power receiving device 101 is a smartphone, and an example of the power transmitting device 100 is an accessory device for charging the smartphone. The power receiving device 101 and the power transmitting device 100 may be a storage device such as a hard disk device or a memory device, or an information processing device such as a personal computer (PC). The power receiving device 101 and the power transmitting device 100 may be, for example, an image input device such as an imaging device (camera, video camera, etc.) or a scanner, or an image output device such as a printer, a copier, or a projector. The power transmitting device 100 may be a smartphone. In this case, the power receiving device 101 may be another smartphone or a wireless earphone. The power transmitting device 100 may be a charger installed in a console or the like in a car.

[0029] Next, the configuration of the power transmitting coil group 210 of the power transmitting device 100 in this embodiment will be described with reference to FIG. 4. FIG. 4 shows a top view of the power transmitting coil group 210. That is, FIG. 4 shows an arrangement of a plurality of power transmitting coils 209 on a two-dimensional xy plane. However, the actual plurality of power transmitting coils 209 may be arranged in a three-dimensional space including the height direction. Note that the arrangement of the plurality of power transmitting coils shown in FIG. 4 is one example, and is not limited thereto. Also, power transmitting coils 400 to 411 in the following description correspond to the plurality of power transmitting coils 209 constituting the power transmitting coil 210.

[0030] 4(a) and (b) are top views of a portion of the power transmitting coil group 210. FIG. 4(a) shows the arrangement of six circular coils, power transmitting coils 400 to 405. Power transmitting coil 400, power transmitting coil 401, and power transmitting coil 402 are each arranged such that the circumference of the power transmitting coil is in contact with the other two coils. Similarly, power transmitting coil 403, power transmitting coil 404, and power transmitting coil 405 are each arranged such that the circumference of the power transmitting coil is in contact with the other two coils. Similarly, power transmitting coil 402, power transmitting coil 403, and power transmitting coil 404 are each arranged such that the circumference of the power transmitting coil is in contact with the other two coils.

[0031] FIG. 4(b) shows an arrangement of six circular coils, power transmitting coils 406 to 411. The arrangement of power transmitting coils 406 to 411 shown in FIG. 4(a) corresponds to an arrangement obtained by flipping the arrangement of power transmitting coils 400 to 405 shown in FIG. 4(b) from left to right. Power transmitting coil 409, power transmitting coil 410, and power transmitting coil 411 are each arranged such that the circumference of the power transmitting coil is in contact with the other two coils. Similarly, power transmitting coil 406, power transmitting coil 407, and power transmitting coil 408 are each arranged such that the circumference of the power transmitting coil is in contact with the other two coils. Similarly, power transmitting coil 408, power transmitting coil 409, and power transmitting coil 411 are each arranged such that the circumference of the power transmitting coil is in contact with the other two coils.

[0032] Fig. 4(c) is a top view of the entire power transmitting coil group 210. The power transmitting coil group 210 is configured by arranging the power transmitting coils 400 to 405 shown in Fig. 4(a) on top of the power transmitting coils 406 to 411 shown in Fig. 4(b).

[0033] FIG. 4(d) is a diagram for explaining the positional relationship between the power transmitting coils. FIG. 4(d) shows the power transmitting coils 400, 401, 410, and 411 of the power transmitting coil group 210 shown in FIG. 4(c). The power transmitting coil 400 and the power transmitting coil 410 overlap when viewed from above. Power transmitting coils having such a positional relationship are expressed as "overlapping". Similarly, the power transmitting coil 401 and the power transmitting coil 410 overlap. On the other hand, the power transmitting coil 400 and the power transmitting coil 411 do not overlap when viewed from above. Power transmitting coils having such a positional relationship are expressed as "not overlapping". Further, the distance 412 is the distance between the tangent to the circumference of the power transmitting coil 400 and the tangent to the circumference of the power transmitting coil 411. Each tangent passes through an intersection point between a straight line connecting the center of the circle of the power transmitting coil 400 and the center of the circle of the power transmitting coil 411 and the circumference of each power transmitting coil. That is, the distance 412 is the shortest distance between the power transmitting coil 400 and the power transmitting coil 411, and indicates that the power transmitting coil 400 and the power transmitting coil 411 are separated by the distance 412. In the present embodiment, the definition of the distance between the power transmitting coils is the distance between the positions on the power transmitting coils when the multiple power transmitting coils are viewed from above, but the definition of the distance is not limited to this. For example, the center of gravity of the power transmitting coil may be set as a reference point, and the distance between the reference points of the power transmitting coils may be set as the distance between the power transmitting coils. Furthermore, the distance 412 in FIG. 4(d) is the distance on the xy plane, but the multiple coils may be disposed at any position in a three-dimensional space including the z-axis direction. In this case as well, the distance between the power transmitting coils may be the shortest distance between the power transmitting coils in the xyz space, or may be the distance between the reference points of the power transmitting coils.

[0034] Although the power transmission coil has been described as being circular, the shape is not limited to this and the power transmission coil may be, for example, a coil having a rectangular shape.

[0035] 4(e) is a diagram for explaining the range in which the first power transmission circuit 203 and the second power transmission circuit 205 can transmit power. The first power transmission circuit 203 in this embodiment is connectable to the power transmission coils 400, 401, 402, 403, 405, 408, 409, 410, and 411. This allows the first power transmission circuit 203 to transmit power to the power receiving device 101 placed in an area 413 indicated by a dotted line. The second power transmission circuit 205 in this embodiment is connectable to the power transmission coils 402, 403, 404, 405, 406, 407, 408, 409, and 411. This allows the second power transmission circuit 205 to transmit power to the power receiving device 101 placed in an area 414 indicated by a dashed line.

[0036] The area 415 is a common area where the area 413 and the area 414 overlap. The area 415 is a range where power can be transmitted by the power transmitting coils 402, 403, 405, and 408, and these power transmitting coils can be connected to both the first power transmitting circuit 203 and the second power transmitting circuit 205. That is, the power receiving device 101 placed in the area 415 receives power from either the first power transmitting circuit 203 or the second power transmitting circuit 205. In the following description, the area 415 is referred to as a shared area 415. Moreover, the area of ​​the area 413 excluding the shared area 415 is referred to as a dedicated area 416 of the first power transmitting circuit 203. The power receiving device 101 placed in the dedicated area 416 can be charged only from the first power transmitting circuit 203. Moreover, the area of ​​the area 414 excluding the shared area 415 is referred to as a dedicated area 417 of the second power transmitting circuit 205. The power receiving device 101 placed in the area 417 can be charged only from the second power transmitting circuit 205.

[0037] Next, the flow of control between the power transmitting device 100 and the power receiving device 101 in this embodiment will be described. First, the control of wireless power transmission conforming to the WPC standard will be described. FIG. 5 is a sequence diagram showing the flow of control of the power transmitting device and the power receiving device conforming to the WPC standard v1.2.3. The sequence shown in FIG. 5 is not limited to the power transmitting device 100 having a plurality of power transmitting coils and a plurality of power transmitting circuits as in this embodiment, but is a control executed by a power transmitting device having a configuration conforming to the WPC standard. In the following description, the power transmitting device 100 is described as transmitting power to the power receiving device 101 using an arbitrary power transmitting coil 209. Note that, in the following, a case where the power transmitting device and the power receiving device conform to the WPC standard v1.2.3 will be described, but is not limited thereto. That is, the power transmitting device and the power receiving device of the present disclosure may conform to the WPC standard of a version after the WPC standard v1.2.3, or may conform to a version earlier than the WPC standard v1.2.3.

[0038] The WPC standard specifies multiple phases, including a power transfer phase in which power transmission for charging is performed, and a phase before power transmission for charging is performed. The phases before power transmission include (1) a selection phase, (2) a ping phase, (3) an identification and configuration phase, (4) a negotiation phase, and (5) a calibration phase. In the following, the identification and configuration phase is referred to as the I&C phase.

[0039] In the Selection phase, the power transmitting device 100 transmits an Analog Ping (hereinafter, referred to as an A-Ping) (F500) to detect an object existing in the vicinity of the power transmitting coil 209. Note that a method of controlling the A-Ping in this embodiment will be described later. A-Ping is a pulsed power for detecting an object. Even if the power receiving device receives A-Ping, the power is so small that the control unit 301 of the power receiving device 101 cannot be started. The power transmitting device 100 transmits A-Ping intermittently. Here, the voltage and current applied to the power transmitting coil 209 change depending on whether an object is placed in the power transmitting range of the power transmitting device 100 or not. Therefore, the control unit 201 of the power transmitting device 100 detects at least one of the voltage value and the current value of the power transmitting coil 209 when transmitting A-Ping. When the detected voltage value is below a certain threshold value or the detected current value is above a certain threshold value, the control unit 201 determines that an object is present and transitions to the Ping phase.

[0040] In the Ping phase, when the power transmitting device 100 detects that an object has been placed by the A-Ping, it measures the Q-factor (Quality Factor) of the power transmitting coil 209 (F501). When the Q-factor measurement ends, the power transmitting device 100 starts transmitting a Digital Ping (hereinafter referred to as D-Ping) (F502). The D-Ping is power for starting the control unit 301 of the power receiving device 101, and is a power greater than the A-Ping. After that, the power transmitting device 100 continues transmitting power equal to or greater than the D-Ping from when it starts transmitting the D-Ping (F502) until it receives an End Power Transfer (EPT) packet requesting the power receiving device 101 to stop transmitting power (F522). When the control unit 301 of the power receiving device 101 receives the D-Ping and starts up, it transmits a Signal Strength packet, which is data storing the voltage value of the received D-Ping, to the power transmitting device 100 (F503). The power transmitting device 100 recognizes that the object detected in the Selection phase is a power receiving device by receiving a Signal Strength packet from the power transmitting device 101 that has received the D-Ping. Upon receiving the Signal Strength packet, the power transmitting device 100 transitions to the I&C phase.

[0041] In the I&C phase, the power receiving device 101 transmits data storing an ID including version information of the WPC standard to which the power receiving device 101 complies and device identification information (F504). The power receiving device 101 also transmits a Configuration packet to the power transmitting device 100 including information indicating the maximum value of power that the power receiving unit 302 supplies to the load (charging unit 306) (F505). By receiving the ID and the Configuration packet, the power transmitting device 100 determines whether the version of the power receiving device 101 corresponds to the WPC standard to which the power receiving device 101 complies, and transmits an ACK. Specifically, when the power transmitting device 100 determines that the power receiving device 101 complies with an extended protocol of the WPC standard v1.2 or later (including processing in the negotiation phase to be described later), it responds with an ACK (F506). When the power receiving device 101 receives the ACK, it transitions to the Negotiation phase in which negotiations are performed regarding the power to be transmitted and received.

[0042] In the negotiation phase, the power receiving device 101 transmits FOD Status data to the power transmitting device 100 (F507). In this embodiment, the FOD Status data is expressed as FOD(Q). The power transmitting device 100 performs foreign object detection based on the Q value stored in the received FOD(Q) and the Q value measured by the Q value measurement, and transmits an ACK indicating that it has been determined that there is a high possibility that no foreign object is present to the power receiving device (F508).

[0043] When the power receiving device receives the ACK, the power receiving device transmits a General Request (Capability) packet, which is data inquiring about the capabilities of the power transmitting device 100 and is one of the General Requests defined in the WPC standard (F535). Hereinafter, the General Request (Capability) packet is referred to as a GRQ (CAP) packet. When the power transmitting device 100 receives the GRQ (CAP) packet, the power transmitting device 100 transmits a Capability packet (hereinafter, referred to as CAP) that stores capability information supported by the power transmitting device 100 (F536).

[0044] The power receiving device 101 negotiates Guaranteed Power (hereinafter, referred to as GP), which is the maximum value of the power value requested for receiving power. Specifically, Guaranteed Power represents the amount of power available to the power receiving device 101, agreed upon in negotiation with the power transmitting device 100. In other words, GP is the maximum value of power (power consumed by the charging unit 306) that can be used to supply to the load of the power receiving device 101. The negotiation is realized by transmitting to the power transmitting device 100 a packet that stores the value of Guaranteed Power requested by the power receiving device, among Specific Request packets defined in the WPC standard (F509). In this embodiment, the data is expressed as an SRQ (GP) packet.

[0045] The power transmitting device 100 responds to the SRQ(GP) packet, taking into consideration its own power transmitting capability and the like. When the power transmitting device 100 determines that the Guaranteed Power is acceptable, it transmits an ACK indicating that the request has been accepted (F510). When the power receiving device 101 finishes negotiation of a plurality of parameters including the Guaranteed Power, it transmits an SRQ (EN) of the Specific Request requesting the end of the negotiation (End Negotiation) to the power transmitting device (F511). The power transmitting device 100 transmits an ACK in response to the SRQ (EN) packet (F512), ends the negotiation, and transitions to a calibration phase in which a criterion for performing foreign object detection based on a power loss method is created. Note that the foreign object detection is a process of determining whether or not an object other than the power receiving device (hereinafter, referred to as a foreign object) is present or there is a possibility that a foreign object is present within the power transmitting range of the power transmitting device 100.

[0046] In the calibration phase, the power receiving device 101 notifies the power transmitting device 100 of the received power value R1 when the power receiving device 101 receives a D-Ping in a state in which the power receiving unit 302 is not connected to a load (battery 307). At this time, the power receiving device 100 transmits a Received Power packet (mode1) (hereinafter referred to as PR1) storing the received power value R1 to the power transmitting device 100. Upon receiving RP1, the power transmitting device 100 transmits an ACK to the power receiving device 101 (F514). At this time, the power transmitting device 100 measures its own transmitted power value T1 and calculates the difference Δ1 between T1, which is the power loss, and R1. After receiving the ACK, the power receiving device 101, with the power receiving unit 302 and the load connected, transmits to the power transmitting device 100 a Control Error packet (hereinafter referred to as CE) requesting the power transmitting device 100 to increase or decrease the receiving voltage. A code and a numerical value are stored in the CE, and if the code of the numerical value stored in the CE is positive, it indicates a request to increase the receiving voltage, if negative, it indicates a request to decrease the receiving voltage, and if the numerical value is zero, it indicates that the receiving voltage is to be maintained. Here, the power receiving device transmits CE(+) to the power transmitting device 100, which indicates to increase the receiving voltage (F515).

[0047] When the power transmitting device 100 receives CE(+), it changes the setting value of the power transmitting circuit and increases the power transmission voltage (F516). When the received power increases in response to CE(+), the power receiving device 100 supplies the received power to the charging unit 306, which is a load, and transmits RP2 (Received Power packet (mode2) (hereinafter referred to as RP2) to the power transmitting device 100 (F517). Here, RP2 stores a received power value R2 in a state in which the power receiving device 101 supplies the output of the power receiving unit 302 to the load (battery 307).

[0048] Upon receiving RP2, the power transmitting apparatus 100 transmits an ACK to the power receiving apparatus (F514). At this time, the power transmitting device 100 measures its own transmission power value T2, and calculates the difference Δ2 between the power loss T2 and R2. The power transmitting device 100 performs foreign object detection based on the power loss, using as references the power loss Δ1 when the power receiving unit 302 is not connected to a load and the power consumption of the load is zero, and the power loss Δ2 when the power receiving unit 302 is connected to a load and the power consumption of the load is not zero. Specifically, the power transmitting device 100 predicts the power loss in a state where there is no foreign object at an arbitrary received power value from Δ1 and Δ2, and can perform foreign object detection based on the actually received received power value and transmitted power value. When the power transmitting device 100 transmits an ACK to RP2, it transitions to the Power Transfer phase.

[0049] In the power transfer phase, the power transmitting device 100 transmits the maximum 15 watts of power negotiated by the power receiving device in the negotiation phase. The power receiving device 101 periodically transmits to the power transmitting device 100 a Received Power packet (mode 0) (hereinafter referred to as RP0) that stores a CE and a current received power value (F519, F520). When the power transmitting device 100 receives RP0 from the power receiving device, it predicts the power loss at an arbitrary received power from Δ1 and Δ2 and performs foreign object detection. If the power transmitting device 100 determines that there is a high possibility that there is no foreign object as a result of the foreign object detection, it transmits an ACK to the power receiving device (F521). If it determines that there is a high possibility that there is a foreign object, the power transmitting device 100 transmits a NAK to the power receiving device.

[0050] When charging of the battery 307 is completed, the power receiving device 101 transmits an EPT (End Power Transfer) packet requesting the power transmitting device 100 to stop power transmission (F522). The above is the flow of control of the power transmitting device 100 and the power receiving device compliant with the WPC standard v1.2.3.

[0051] Next, an example of control when the power transmitting device 100 having a plurality of power transmitting coils 209 transmits power based on the WPC standard will be described with reference to Fig. 6. The first power transmitting circuit 203 and the second power transmitting circuit 205 of the power transmitting device 100 in this embodiment can each perform the processes shown in Fig. 5. Note that, although some processes are omitted in Fig. 6 for the sake of simplicity, it is assumed that the same processes as those shown in Fig. 5 are actually performed.

[0052] First, the first power transmission circuit 203 and the second power transmission circuit 205 each use the power transmission coil 209 connected thereto to intermittently transmit A-Pings for detecting a power receiving device placed within the power transmission range of the power transmission device 100 (F541). A method for controlling A-Pings in this embodiment will be described later. Here, when the first power receiving device 101a is placed near the power transmission coil 209 to which the first power transmission circuit 203 is connected, the first power receiving device 203 transmits D-Pings to the first power receiving device 101a (F542, 543). In addition, the first power transmission circuit 203 performs the above-mentioned control communication, transitions to the Power Transfer phase, and transmits power for charging to the first power receiving device 101a (F544). At this time, the second power transmission circuit 205 continues to transmit A-Pings (F545).

[0053] Then, when the second power receiving device 101b is placed near the power transmitting coil 209 to which the second power transmitting circuit 205 is connected, the second power receiving device 205 transmits a D-Ping to the second power receiving device 101b (546). The second power transmitting circuit 205 also performs the above-mentioned control communication, transitions to the Power Transfer phase, and transmits power for charging to the second power receiving device 101b (F547). Through the above-described process, the power transmitting device 100 can simultaneously charge a plurality of power receiving devices.

[0054] [Processing in power transmission equipment] A problem to be solved in this embodiment will be described. When the first power transmission circuit 203 and the second power transmission circuit 205 perform control communication and power transmission, respectively, the power transmitted by the power transmission coil connected to one power transmission circuit may be superimposed on the power of the power transmission coil connected to the other power transmission circuit. This phenomenon is expressed as interference in this embodiment. The definitions of interference and non-interference will be described. The two power transmission coils "do not interfere" as follows. That is, when the voltage / current amplitude fluctuation or frequency fluctuation of the modulated signal transmitted and received by one of the two power transmission coils is not observed by the other power transmission coil, or when the observed level is equal to or lower than a predetermined value and does not affect the demodulation performance when the communication unit demodulates the other modulated signal. The two power transmission coils "interfere" as follows. That is, when the voltage / current amplitude fluctuation or frequency fluctuation of the modulated signal transmitted and received by one of the two power transmission coils is observed by the other power transmission coil, or when the observed level is greater than a predetermined value and affects the demodulation performance when the communication unit demodulates the other modulated signal.

[0055] Furthermore, the presence or absence of interference may be expressed based on the high-frequency voltage or high-frequency current applied to one of two electromagnetically coupled power transmitting coils (i.e., the coupling coefficient is not zero). That is, if the fluctuation of the high-frequency voltage or high-frequency current applied to one power transmitting coil is not induced in the other power transmitting coil, or the induced level is equal to or lower than a predetermined value, it may be expressed as "no interference," and otherwise as "interference."

[0056] The above-mentioned interference may occur, for example, when the first power transmitting circuit 203 and the second power transmitting circuit 205 simultaneously perform control communication or power transmission. In order to prevent interference, for example, a method of shifting the timing at which the first power transmitting circuit 203 and the second power transmitting circuit 205 perform control communication or power transmission may be used. In the following, a method of detecting an object by outputting A-Ping using multiple power transmitting coils so as to prevent interference will be described. According to this method, A-Pings are output simultaneously from power transmitting coils in different positions, so that an object can be detected efficiently in a short time.

[0057] The degree of interference varies depending on the relative positions of the two power transmitting coils. In this embodiment, it is assumed that the two power transmitting coils do not interfere with each other if they are separated by a predetermined distance D or more. Now, it is assumed that the distance 412 between the power transmitting coil 400 and the power transmitting coil 411 shown in FIG. 4(d) is D. In this case, the power transmitting coil 400 and the power transmitting coil 411 can be said to be power transmitting coils that do not interfere with each other. Also, the power transmitting coil 400 and the power transmitting coil 410, and the power transmitting coil 401 and the power transmitting coil 410 overlap each other and are not separated by the distance D or more, so they can be said to be power transmitting coils that interfere with each other.

[0058] The predetermined distance D is set in advance by, for example, measuring the distance between the power transmission coils at which no interference occurs. For example, a voltage or current is applied to a predetermined power transmission coil among the multiple power transmission coils, and the fluctuation of the voltage or current in the other power transmission coils at this time is measured. By this measurement, a power transmission coil in which no fluctuation occurs or the fluctuation is equal to or less than a predetermined amount is specified, and the distance from the predetermined power transmission coil is measured, so that the distance D at which no interference occurs can be obtained. Also, for example, the amplitude or frequency of the voltage or current applied to a predetermined power transmission coil among the multiple power transmission coils is fluctuated, and the fluctuation of the amplitude or frequency of the voltage or current in the other power transmission coils at this time is measured. By this measurement, a power transmission coil in which no fluctuation occurs or the fluctuation is equal to or less than a predetermined amount is specified, and the distance from the predetermined power transmission coil is measured, so that the distance D at which no interference occurs can be obtained. The predetermined value used to determine the presence or absence of interference and the predetermined distance D may be specified in the WPC standard.

[0059] The predetermined distance D at which no interference occurs may be a different value depending on the definition of the distance between the power transmitting coils. For example, the predetermined distance D may be a different value when the distance between the power transmitting coils is the distance between reference points (e.g., centers of gravity) of the power transmitting coils and when it is the shortest distance between the power transmitting coils. Also, the power transmitting coils may be arranged not only on a two-dimensional plane as in FIG. 4 but also in a three-dimensional space (e.g., in the height direction). In this embodiment, the predetermined distance D at which no interference occurs can be obtained in the same manner under any condition, and the control described below can be performed.

[0060] As described above, simultaneous power transmission from power transmission coils in a predetermined positional relationship may cause the power transmission coils to interfere with each other, affecting the power transmission and control communication of each power transmission coil. Therefore, when selecting power transmission coils to be connected to the first power transmission circuit 203 and the second power transmission circuit 205, the power transmission device 100 in this embodiment operates to select power transmission coils located at a predetermined distance D or more away so as not to interfere with each other. This makes it possible to perform appropriate power transmission even when multiple power transmission coils are used for power transmission.

[0061] In the present disclosure, it is also possible to use a method in which a specific predetermined distance D is not determined. Specifically, it is sufficient to identify other power transmitting coils that cause interference due to power transmission to a certain power transmitting coil. In other words, it is possible to identify in advance other power transmitting coils that interfere with power transmission to a certain power transmitting coil or other power transmitting coils that do not interfere, and to store the identification results. Based on this identification result, when selecting a certain power transmitting coil, a power transmitting coil that is identified as not interfering is selected. It is sufficient to operate using the selected power transmitting coils.

[0062] Fig. 7 is a flowchart for explaining the processing executed by the power transmitting device 100 in this embodiment. Fig. 8 is a sequence diagram showing the processing executed by the power transmitting device 100 in this embodiment. The flowchart shown in Fig. 7 and the sequence diagram shown in Fig. 8 can be realized by the control unit 201 of the power transmitting device 100 executing a control program stored in the memory 207, and performing calculations and processing of information and control of each piece of hardware.

[0063] When the power transmitting device 100 is turned on (S601), the control unit 201 performs a process of selecting a power transmitting coil to be connected to the first power transmitting circuit 203 and the second power transmitting circuit 205 from the power transmitting coil group 210. At this time, the process differs depending on whether the power transmitting device 100 is already performing a power transmitting process for charging or not (S602). Here, since the power transmitting device 100 has just been turned on, it is assumed that a power transmitting process is not being performed, and the process proceeds to S603. The control unit 201 selects a coil that will not cause interference even if the first power transmitting circuit 203 and the second power transmitting circuit 205 use it simultaneously.

[0064] Here, a method for selecting coils that do not cause interference will be described. As described with reference to FIG. 4(d), if two power transmitting coils are separated by a distance D or more, interference between the coils will not occur. The control unit 201 determines a combination of power transmitting coils that are separated by a distance D or more, such as the power transmitting coil 400 and the power transmitting coil 411 shown in FIG. 4(d). As an example, the control unit 201 determines combinations of power transmitting coils that do not cause interference in the power transmitting coil group 210 shown in FIG. 4(c) as (400, 411), (401, 409), (402, 404), (403, 407), (405, 406), and (408, 410). Note that this combination example is merely an example, and other combinations may be determined. The selection unit 208 connects two power transmitting coils that are in a positional relationship that does not cause interference to the first power transmitting circuit 203 and the second power transmitting circuit 205, respectively, according to the combination determined by the control unit 201 (S603).

[0065] The power transmitting device 100 waits for the power receiving device to be placed on the power transmitting device 100 (S605). The control of A-Ping will be described in detail with reference to FIG. 8. Based on the determined combination of power transmitting coils, the selection unit 208 first connects the first power transmitting circuit 203 and the coil 400, and the second power transmitting circuit 205 and the coil 411. The control unit 201 also performs object detection processing by simultaneously outputting A-Ping from the coils 400 and 411 (F701). Since the power transmitting coil 400 and the power transmitting coil 411 are in a positional relationship that does not interfere with each other, even if the first power transmitting circuit 203 and the second power transmitting circuit 205 are controlled to simultaneously transmit A-Pings, interference between the power transmitting coils does not occur. Note that the timing and period at which A-Pings are output from each of the two power transmitting coils may or may not be the same. It is sufficient that the periods during which A-Ping is output from each of the two transmitting coils overlap at least partially. Note that, in order to prevent interference, a method may be used in which the periods during which A-Ping is output from each of the multiple transmitting coils do not overlap.

[0066] If no power receiving device is detected, the selection unit 208 then connects the first power transmitting circuit 203 to the coil 401 and the second power transmitting circuit 205 to the coil 409, and performs a power receiving device detection process. In this way, the power transmitting device 100 connects the first power transmitting circuit 203 and the second power transmitting circuit 205 to the power transmitting coils based on the determined coil combination until a power receiving device is detected, and performs an object detection process.

[0067] In F702, when a power receiving device is placed on the power transmitting device 100, a change in voltage or current is detected in the coil 400 of the power transmitting device 100 that is currently transmitting an A-Ping. Then, the power transmitting device 100 transmits a D-Ping in the Ping phase described above. Then, through communication in the Ping phase, the power transmitting device 100 identifies the object as the power receiving device 101. In this way, the power receiving device 101 is detected (F703).

[0068] 7, when the control unit 201 of the power transmitting device 100 detects that the power receiving device is placed (Yes in S506), the first power transmitting circuit 203 performs power transmission processing through multiple phases defined in the WPC standard (S606). Here, it is assumed that the power transmitting device 100 detects the placement of the power receiving device 101 via the power transmitting coil 400 connected to the first power transmitting circuit 203. The power transmitting device 100 transmits power for charging using the power transmitting coil 400 that detected the power receiving device. The control unit 201 prohibits the use of coils in the power transmitting coil group 210 that cause interference with the power transmitting coil (here, the power transmitting coil 400) used for power transmission processing. Specifically, in FIG. 4(c), the power transmitting coils (401, 402, 409, 410) are not located at a distance D or more from the power transmitting coil 400. Therefore, the use of these coils is prohibited while the power transmitting coil 400 is in use (S607).

[0069] On the other hand, since the second power transmitting circuit 205 has not detected the placement of a power receiving device (No in S608), it performs the processes from S602 onwards again to select a power transmitting coil from the coil group 210 and detect the placement of a power receiving device. Since the first power transmitting circuit 203 is already performing the power transmission process (Yes in S602), the second power transmitting circuit 205 selects a power transmitting coil other than the prohibited power transmitting coil from the coil group 210 and performs the detection process until it detects the placement of a power receiving device (S610). That is, the second power transmitting circuit 205 detects the newly placed power receiving device using a power transmitting coil that is positioned so as not to interfere with the power transmitting coil 400 that the first power transmitting circuit 203 is using for power transmission for charging.

[0070] A detailed description will be given with reference to Fig. 8. When the power transmitting device 100 detects that a power receiving device has been placed on the power transmitting coil 400 (F703), it starts transmitting power for charging using the power transmitting coil 400 (F704). The power transmitting device 100 also prohibits the use of power transmitting coils that interfere with the power transmitting coil 400 (F705). The power transmitting device 100 sequentially connects the power transmitting coils other than the prohibited power transmitting coils to the second power transmitting circuit 205, and executes A-Ping power transmission for detecting the power receiving device (F706).

[0071] Returning to Fig. 7, when the second power transmitting circuit 205 detects a power receiving device, it performs power transmission processing through multiple phases defined in the WPC standard described above (S606). When all power transmitting circuits are transmitting power for charging (Yes in S608), the power transmitting device 100 ends the control processing for power transmission. Note that a power transmitting circuit that has finished the power transmission processing by receiving an EPT packet from a power receiving device or the like executes the processing from S602 onwards again to detect a new power receiving device and transmit power. The processing shown in Fig. 7 is repeated until the power transmitting device 100 is turned off.

[0072] As described above, the power transmitting device 100 in this embodiment controls so that A-Ping is not output simultaneously from two power transmitting coils that are located closer than a predetermined distance apart from each other among the multiple power transmitting coils. According to this embodiment, even if multiple power transmitting coils are closely packed together, it is possible to efficiently control power transmission while preventing interference between the power transmitting coils. As a result, the power transmitting device 100 can appropriately detect and transmit power even if multiple power receiving devices are placed at any position on the power transmitting device 100.

[0073] In the above description, the power transmission for charging is performed using a power transmission coil that detects an object (power receiving device), but the present disclosure is not limited to this. In order to perform efficient power transmission, power transmission for charging may be performed using a coil different from the power transmission coil that detects the object (power receiving device). In this case, a power transmission circuit different from the power transmission circuit used for charging transmits A-Ping using a power transmission coil that does not interfere with the power transmission coil that transmits power for charging. In other words, a power transmission coil that does not interfere with the power transmission coil used for charging power transmission may be specified, and A-Ping may be transmitted using that power transmission coil.

[0074] In addition, in the present embodiment, an example in which there are two power transmission circuits has been described, but the method described in the present embodiment can also be applied to a case in which there are three or more power transmission circuits. For example, when the power transmission device 100 has three power transmission circuits, including a third power transmission circuit (not shown) in addition to the first power transmission circuit 203 and the second power transmission circuit 205, the power transmission device 100 performs the following process. That is, when the control unit 201 of the power transmission device 100 uses the three power transmission coils 209 connected to each power transmission circuit at positions spaced apart from each other by a predetermined distance D or more when outputting a signal for object detection using each power transmission circuit. In the example of the power transmission coil group 210 shown in FIG. 4(c), for example, the power transmission coils 400, 403, and 411 are selected as the three power transmission coils. Since the three power transmission coils are spaced apart from each other by a distance D or more, no interference occurs even if A-Ping is transmitted at the same time. By selecting the power transmitting coils 209 to be connected to each power transmitting circuit in this manner, the power transmitting device 100 can prevent interference between the three power transmitting coils 209 even when A-Pings are output from the three power transmitting coils 209. The same applies to the case where there are four or more power transmitting circuits.

[0075] (Embodiment 2) In the above-described first embodiment, the first power transmission circuit 203 and the second power transmission circuit 205 may have the same or different power transmission capabilities. In this embodiment, control in the case where the power transmission circuits of a power transmission device have different power transmission capabilities will be described. When transmitting power to a power receiving device using a power transmission device having multiple power transmission circuits with different power transmission capabilities, the following problems may occur. For example, when a power receiving device is placed on the power transmission device, a power transmission process may be performed by a power transmission circuit that cannot sufficiently transmit the power that the power receiving device can receive (has low power transmission capability). This causes a problem that charging of the power receiving device is not efficiently performed. In this way, when transmitting power to a power receiving device using a power transmission device having power transmission circuits with different power transmission capabilities, appropriate power transmission may not be performed.

[0076] In this embodiment, a method for supplying sufficient power to a power receiving device is described by determining which power transmitting circuit to use for power transmission based on the power transmitting capability of the power transmitting circuit and the power receiving capability of the power receiving device. In this embodiment, the same names and symbols are used for configurations similar to those in the first embodiment.

[0077] [Processing in power transmission equipment] The process executed by the power transmitting device 100 will be described below with reference to Figs. 9 and 10. The process in Fig. 9(a) is the process shown in Fig. 5 plus the switching process of the power transmitting circuit described in this embodiment. In F505, the power transmitting device 100 acquires a configuration packet from the power receiving device 101 and acquires the power receiving capability of the power receiving device 101 from the acquired packet. The power receiving capability here is the power that the power receiving device 101 can receive based on the maximum value of the power that the power receiving unit 302 of the power receiving device 101 supplies to the load (charging unit 306), and more specifically, is the power that corresponds to the maximum power in the WPC standard. The power transmitting device 100 executes the switching process based on the maximum power (power transmission capability) that the power transmitting device 100 can transmit to charge the power receiving device and the acquired power receiving capability of the power receiving device 101 (F826). This switching process may be executed before transitioning to the Power Transfer phase.

[0078] FIG. 10 is a process flow of the power transmission circuit switching process of the power transmission device according to the present embodiment. The process shown in FIG. 10 is performed in F826 in FIG. 9. Now, it is assumed that the power transmission device 100 detects the power receiving device 101 by the first power transmission circuit 203 and acquires a Configuration packet from the power receiving device 101. First, the power transmission device 100 determines whether another power transmission circuit having a higher power transmission capacity than the first power transmission circuit 203 performing control communication with the power receiving device is available for power transmission (S901). That is, the power transmission device 100 determines whether there is a power transmission circuit having a higher power transmission capacity than the first power transmission circuit 203 and not yet transmitting power to another power receiving device. Here, it is assumed that the second power transmission circuit 205 has a higher power transmission capacity than the first power transmission circuit 203 and is not transmitting power. Note that when the power transmission circuit performing control communication with the power receiving device is the second power transmission circuit, there is no power transmission circuit having a higher power transmission capacity than the second power transmission circuit in the first place, so the determination in S901 is No.

[0079] If the corresponding power transmission circuit is available for power transmission (Yes in S901), the power transmission device 100 determines whether the power transmission capability of the power transmission circuit currently performing control communication with the power receiving device is lower than the power receiving capability of the power receiving device (S902). Here, if the power transmission device 100 cannot perform power transmission that satisfies the Maximus Power included in the Configuration packet, the power transmission capability is considered to be lower than the power receiving capability. If the power transmission capability is lower than the power receiving capability (Yes in S902), the power transmission device 100 switches the first power transmission circuit 203 performing control communication with the power receiving device 101 to another power transmission circuit with higher power transmission capability (S903). Here, the power transmission device 100 uses the selection unit 208 to switch the connection of the power transmission coil performing control communication with the power receiving device 101 from the first power transmission circuit 203 to the second power transmission circuit 205. On the other hand, if the power transmission capability is higher than the power receiving capability (No in S902), the process ends.

[0080] A case where there is no other power transmission circuit that corresponds to the power transmission device 100 in S901 (No in S901) will also be described. If the result in S901 is No, the power transmission device 100 determines whether there is another power transmission circuit with a lower power transmission capability and whether the other power transmission circuit is usable (S906). If another power transmission circuit with a lower power transmission capacity is available (Yes in S906), the process proceeds to S904. On the other hand, if another power transmission circuit with a lower power transmission capacity is not available, the process ends without switching the power transmission circuit. The power transmission device 100 determines whether the power transmission capacity of the other power transmission circuit with a lower power transmission capacity is equal to or greater than the power receiving capacity of the power receiving device (S904). That is, the power transmission device 100 determines whether the maximum power that can be transmitted by the other power transmission circuit is equal to or greater than the power that can be received by the power receiving device. If the power transmission capacity of the other power transmission circuit is equal to or greater than the power receiving capacity, the first power transmission device 100 switches the connection of the power transmission coil that is performing control communication with the power receiving device to the other power transmission circuit with a lower power transmission capacity (S905). If it is lower than the power receiving capacity, the process ends. By performing the processing described here, when a second power receiving device as described below is placed, it becomes possible to transmit sufficient power to the second power receiving device, thereby making effective use of the power transmission capacity of the power transmitting device 100.

[0081] Here, the processing of the power transmitting device of the present embodiment will be described using a specific example. Now, a method of supplying sufficient power to the power receiving device will be described for a case where a first power receiving device 101a with a power receiving capacity of 60w is placed on a power transmitting device 100 with a power transmitting capacity of 15w of a first power transmitting circuit and a power transmitting capacity of 60w of a second power transmitting circuit. The power transmitting device 100 transmits A-Ping via the first power transmitting circuit 203 in F500 of FIG. 9(a). When the first power receiving device 101a is placed, the first power transmitting device 100 and the first power receiving device 101a execute sequences F509 to F506. Here, the first power transmitting device 100 can know that the power receiving capacity of the first power receiving device 101a is 60w from the value of the maximum power receiving power included in the Configuration packet in F505. The power transmitting device 100 transmits power via the first power transmitting circuit 203, and therefore cannot supply sufficient power to the first power receiving device 101a. Therefore, the first power transmission device 100 performs a power transmission circuit switching process F826. In S901 of FIG. 10, since the second power transmission circuit 205 with a power transmission capacity of 60 w is present, the power transmission device 100 advances the process to S902. Next, in S902, since the power transmission capacity of the first power transmission circuit 203 currently transmitting power is equal to or less than 60 w, which is the power receiving capacity of the power receiving device, the power transmission device 100 advances the process to S903. In S903, the power transmission device 100 stops power transmission and switches the power transmission circuit transmitting power to the first power receiving device 101a to the second power transmission circuit 205. The power transmission device 100 performs the process from F507 onward using the second power transmission circuit 205. In addition, since the first power transmission circuit 203 is not communicating with the power receiving device, it transmits A-Ping to detect a new power receiving device. In this way, in a power transmission device having multiple transmission circuits with different capacities, it is possible to supply sufficient power to the power receiving device by switching the transmission circuit that transmits power to the power receiving device based on the power receiving capacity of the power receiving device and the power transmission capacity of the transmission circuit.

[0082] FIG. 9B is a sequence diagram for explaining the operation of each power transmission circuit and the process when a second power receiving device is placed. In the process shown in FIG. 9, the same processes as those shown in FIG. 5 and FIG. 9A are denoted by the same reference numerals, and the description thereof will be omitted. In FIG. 9B, when the first power transmission circuit 203 detects the placement of the power receiving device 101a (F542), the first power transmission circuit 203 transmits a D-Ping to the power receiving device 101a and performs control communication (F543). When the first power transmission circuit 203 acquires a Configuration packet from the first power receiving device 101a (F505), the first power transmission circuit 203 transmits an ACK to the first power receiving device 101a (F506), and performs the switching process of the power transmission circuit shown in FIG. 10 (F826). As a result, the subsequent processes are performed by the second power transmission circuit 205.

[0083] The second power transmitting circuit 205 performs the process from F507 in FIG. 9A onward to transmit power to the first power receiving device 101a for charging (F827). Since the power transmitting device 100 has already acquired information about the first power receiving device 101a via the first power transmitting circuit 203, the second power transmitting circuit 205 can perform the power transmission process without acquiring information such as a Configuration packet again. Meanwhile, the first power transmitting circuit 203 transmits A-Ping power to detect the placement of a new power receiving device (F828). Here, when the first power transmitting circuit 203 detects that the second power receiving device 101b has been newly placed, it transmits D-Ping to the second power receiving device 101b to perform control communication (F829) and starts power transmission for charging (F830).

[0084] Here, a specific example of the process of FIG. 9(b) will be described. Now, assume that a first power receiving device 101a with a power receiving capacity of 5w is placed on a power transmitting device 100 with a first power transmitting circuit having a power transmitting capacity of 15w and a second power transmitting circuit having a power transmitting capacity of 5w, and then a power receiving device with a power receiving capacity of 15w is placed on the power transmitting device 100. The first power transmitting device 100 transmits an A-Ping via the first power transmitting circuit 203 in F541. When the first power receiving device 101a is placed, the first power transmitting device 100 obtains a Configuration packet from the first power receiving device 101a in F506, and can know that the power receiving capacity of the first power receiving device 101a is 5w. The first power transmitting device 100 performs a power transmitting circuit switching process shown in FIG. 10 (F826). In S901, the power transmitting device advances the process to S906 because there is no other power transmitting circuit with a higher power transmitting capacity than the power transmitting circuit performing control communication. In S906, the power transmitting device 100 advances the process to S904 because another power transmitting circuit (the second power transmitting circuit 205) having a lower power transmitting capability than the power transmitting circuit performing the control communication is available. Then, in S904, the power transmitting device 100 advances the process to S905 because the power transmitting capability of the other power transmitting circuit is equal to or greater than the power receiving capability of the power receiving device. In S905, the power transmitting device switches the power transmitting circuit that transmits power to the first power receiving device 101a to the second power transmitting circuit 205.

[0085] In F828, the first power transmission device 100 transmits an A-Ping via the first power transmission circuit 203. After that, when the second power reception device 101b with a power receiving capacity of 15 W is placed, the first power transmission device 100 transmits a D-Ping to the second power reception device 101b (F829) and starts power transmission for charging (F830). Although not shown in FIG. 9B, the second power transmission circuit 205 acquires a Configuration packet from the second power reception device 101b after F828 and performs a switching process in the same manner. However, since the power transmission device 100 is aware that power transmission by the first power transmission circuit 203 has already been performed and that there is no power transmission circuit other than the second power transmission circuit 205 that can be used, the switching process may be omitted.

[0086] The above-mentioned process allows the power transmitting device 100 to supply sufficient power to the newly placed second power receiving device 101b. In this way, in a power transmitting device having a plurality of power transmitting circuits with different capabilities, the power transmitting circuit that transmits power to the power receiving device is switched based on the power receiving capability of the power receiving device and the power transmitting capability of the power transmitting circuit, so that sufficient power can be supplied. In this embodiment, the power transmitting circuit is switched using the selection unit 208 so that power transmission is not stopped, but other methods may be used. For example, the power transmitting device 100 transmits an EPT to the first power receiving device 101a, stops power transmission, and then switches the power transmitting circuit using the selection unit 208 and resumes processing from A-Ping. This allows even a power transmitting device that cannot instantly switch the power transmitting circuit to be able to supply sufficient power to the power receiving device. In addition, when the power transmitting device 100 receives a Configuration packet from the power receiving device, the power transmitting device 100 may perform the switching process before responding with an ACK.

[0087] In the present embodiment, the power transmitting device 100 determines whether to switch the power transmitting circuit based on information included in a configuration packet acquired by the power transmitting device 100 in the I&C phase, but the present invention is not limited to this. The power transmitting device 100 may be configured to determine whether to switch the power transmitting circuit based on information on the GP acquired from the power receiving device 101 in the Negotiation phase, for example. The power transmitting device 100 compares the power that the power transmitting circuit can transmit with the power represented by the GP included in the SRQ (GP) packet acquired from the power receiving device 101, and determines whether to switch the power transmitting circuit. If the power transmitting device 100 cannot transmit power equivalent to the GP, it switches to a power transmitting circuit with a higher power transmission capability (Yes in S902 in FIG. 10, S903). Also, if the power that another power transmitting circuit with a lower power transmission capability can transmit is higher than the GP, the power transmitting circuit 100 switches to another power transmitting circuit with a lower power transmission capability (Yes in S904 in FIG. 10, S905). In this case, in the sequence of FIG. 9A, the power transmitting device 100 performs the switching process after acquiring an SRQ (GP) packet in F511 or after transmitting an ACK as a response to the SRQ (GP) packet in F512.

[0088] Furthermore, when the GP is changed during power transmission, the power transmitting device 100 may perform a power transmission circuit switching process based on the changed GP. The power transmitting device 100 and the power receiving device 101 may be configured to be able to change the GP by performing renegotiation. In this case, when the power transmitting device 100 cannot transmit power corresponding to the GP determined by the renegotiation, the power transmitting device 100 switches to a power transmission circuit having a higher power transmission capacity. As a result, when the power transmission circuit during power transmission cannot supply sufficient power, sufficient power can be supplied by switching the power transmission circuit. Furthermore, when the power that can be transmitted by another power transmission circuit having a lower power transmission capacity is greater than the power corresponding to the GP determined by the renegotiation, the power transmitting device 100 switches to another power transmission circuit having a lower power transmission capacity. As a result, when a new power receiving device is mounted, power can be transmitted to the new power receiving device using a power transmission circuit having a higher power transmission capacity. As a result, the power transmitting device 100 can effectively utilize the power transmission capacity of the power transmission circuit.

[0089] In addition, after determining the power transmission circuit to be used for power transmission in the I&C phase, the power transmission device 100 may switch the power transmission circuit based on information included in an SRQ packet acquired in the negotiation phase. In addition, the power transmission device 100 may switch the power transmission circuit based on information acquired in renegotiation.

[0090] Further, the power receiving capability of the power receiving device is described as the maximum power receiving value or GP, but is not limited to this. For example, the power receiving capability of the power receiving device may be acquired based on the identification number of the power receiving device, information that can identify the type of the power receiving device, and information on the version of the WPC, and the like, and a power transmission circuit switching process may be performed. For example, the power transmitting device may identify that the power receiving device is one that has previously transmitted power based on the identification number of the power receiving device, and determine the power transmission circuit to be used according to the past power transmission record. For example, the power transmitting device may identify the type of the power receiving device and switch the power transmitting device between the case where the power receiving device is a smartphone and the case where the power receiving device is a PC. Note that the types of the power receiving device described here are merely examples, and the power receiving device may be of a type other than the above. Also, a configuration may be used in which a switching process is performed based on any number of pieces of information among the above-mentioned information acquired from the power receiving device.

[0091] The method described in this embodiment is also applicable to power transmission devices other than those having multiple power transmission coils as shown in Figs. 2 and 4. That is, this embodiment is applicable to power transmission devices having multiple power transmission circuits with different power transmission capabilities. For example, the power transmission device may be capable of connecting multiple power transmission circuits with different power transmission capabilities to one power transmission coil. The method of this embodiment is also applicable to power transmission devices having multiple power transmission circuits including at least two power transmission circuits with different power transmission capabilities. For example, even in a power transmission device having two or more power transmission circuits, power transmission using an appropriate power transmission circuit can be performed by applying the process shown in Fig. 10.

[0092] (Embodiment 3) In this embodiment, a case is considered in which a power transmitting device having a plurality of power transmitting circuits detects another power receiving device while transmitting power to one or more power receiving devices. In this case, if A-Ping is constantly transmitted from each power transmitting coil to detect another power receiving device while transmitting power to the power receiving device, there is a problem that the radiation noise increases and adversely affects the surrounding devices (existing power transmission). In addition, since the A-Ping is continuously transmitted from the multiple power transmitting coils, the power transmitting device consumes unnecessary power while no other power receiving device is placed on the device. Thus, when a power transmitting device having multiple power transmitting coils detects a power receiving device, there is a risk of adverse effects being generated between the power transmitting coils.

[0093] In order to solve this problem, the power transmitting device in this embodiment determines whether or not power is being transmitted to the power receiving device, and if power is being transmitted, stops transmitting A-Ping from the power transmitting coils and detects an object based on a change in a physical quantity (physical parameter) in the object detection coils. Then, only when an object is detected by the object detection coils, A-Ping is transmitted from each power transmitting coil. In this way, by suppressing unnecessary transmission of A-Ping, it is possible to detect the placement of a new power receiving device while reducing the adverse effect on existing power transmission due to the generation of radiation noise. In addition, unnecessary power consumption can be suppressed.

[0094] Hereinafter, an embodiment will be described in detail with reference to the accompanying drawings. Note that the same names and reference numerals are used for configurations similar to those of the above-described embodiment.

[0095] [Device configuration] FIG. 11 is a diagram for explaining the configuration of the power transmitting device 200 in this embodiment. As shown in FIG. 11(a), the power transmitting device 200 further includes an object detection coil 211 configured to encompass the entire power transmission range of the power transmitting coil group 210. FIG. 11(b) shows an example of the configuration of the object detection coil. The object detection coil 211 is, for example, a coil configured to surround the transmission coil group 210 shown in FIG. 4(c). That is, the area in which the object display coil 211 can transmit power encompasses the area in which the power transmitting coil group 210 can transmit power. The shape of the object detection coil 211 is not limited to that shown in FIG. 11(b).

[0096] [Processing in power transmission equipment] Next, a description will be given of the flow of processing executed by the power transmitting device 200. Fig. 12 shows a flowchart of processing executed by the power transmitting device 200. This processing can be realized, for example, by the control unit 201 of the power transmitting device executing a program read from the memory 207. At least a part of the following procedure may be realized by hardware. In this case, the hardware may be realized by, for example, automatically generating a dedicated circuit using a gate array circuit such as an FPGA from a program for realizing each processing step using a predetermined compiler. In addition, this process may be executed in response to the power supply of the power transmitting device 200 being turned on, in response to the user of the power transmitting device 200 inputting an instruction to start a contactless charging application, or in response to the power transmitting device 200 being connected to a commercial power source and receiving power supply. In addition, this process may be started by another trigger. In addition, the power transmitting device 200 executes this process using a plurality of power transmitting coils 209, and may execute the process by sequentially selecting one of the power transmitting coils 209, or may execute the process in parallel using a plurality of or all of the power transmitting coils.

[0097] In the following description, it is assumed that one or more power receiving devices are placed on the power transmitting device 200 (for example, on a charging stand (mounting surface) configured to be close to a plurality of power transmitting coils in the power transmitting device 200), but the present invention is not limited thereto. It may also be assumed that one or more power receiving devices are present within a power transmitting range of the power transmitting device 200, for example.

[0098] First, the power transmitting device 200 determines whether or not power is being transmitted to the power receiving device (S1001). If power is being transmitted to the power receiving device (Yes in S1001), the process proceeds to S1002, and if power is not being transmitted to the power receiving device (No in S1001), the process proceeds to S1005. Next, in S1002, the power transmitting device 200 transmits an object detection signal from the object detection coil 211, and the process proceeds to S1003. At this time, in order to detect an object within a predetermined time period, such as one second, the power transmitting device 200 transmits A-Ping as an object detection signal from the object detection coil 211 once per second.

[0099] Here, the object detection signal may be A-Ping of the WPC standard, but may be another signal. In S1003, the power transmitting device 200 calculates the amount of change in the physical quantity in the object detection coil 211, and the process proceeds to S1004. Here, the amount of change in the physical quantity may be calculated by measuring the current value of the object detection coil 211 caused by a change in the state of the object detection coil 211 and calculating the difference from the previously measured value, but is not limited to this. For example, the amount of change in the physical quantity may be the difference in the voltage value applied to the object detection coil 211, the amount of shift in the resonant frequency of the object detection coil 211, or the difference in the characteristic impedance of the object detection coil 211. In this way, when the state inside object detection coil 211 changes due to the transmission of the object detection signal, at least one of the current, voltage, resonant frequency, etc. generated in the coil changes. Based on this change, control unit 201 of power transmitting device 200 can detect that a new power receiving device may have been placed. The reason why the current, voltage, resonant frequency, etc. in the coil change is because the magnetic flux in the coil or the characteristic impedance changes due to the change in the state inside object detection coil 211.

[0100] In S1004, the power transmitting device 200 determines whether the amount of change in the physical quantity calculated by the object detection coil 211 is equal to or greater than a threshold, that is, whether there is a possibility that a new power receiving device has been placed. If the amount of change in the physical quantity is equal to or greater than the threshold (Yes in S1004), the process proceeds to S1005, and if the amount of change in the physical quantity is less than the threshold (No in S1004), the process returns to S1001. If the amount of change in the physical quantity is equal to or greater than the threshold, this means that a new object has been placed on the power transmitting device 200.

[0101] Next, in S1005, the power transmitting device 200 starts the process defined as the Selection phase of the WPC standard described above. The power transmitting device 200 transmits A-Pings sequentially from the power transmitting coils 209 to detect the position of an object present within the power transmitting range. At this time, in order to detect the position of an object within a predetermined time period, such as one second, the power transmitting device 200 needs to transmit A-Pings from each of the multiple power transmitting coils 209 per second. Therefore, the power transmitting device 200 in this case transmits A-Pings sequentially from the multiple power transmitting coils 209 every (1 / N) seconds (N is the number of power transmitting coils 209), for example.

[0102] When the power transmitting device 200 detects an object within the power transmitting range, the power transmitting device 200 transitions to the Ping phase of the WPC standard and transmits a D-Ping using the power transmitting coil 209 that detected the object. When there is a predetermined response to the D-Ping, the power transmitting device 200 determines that the detected object is a power receiving device and that the power receiving device is placed on the target power transmitting coil, and stores the result (S1006). When the power transmitting device 200 detects that the power receiving device is placed, the power transmitting device 200 transitions to the I&C phase of the WPC standard described above, and acquires identifier information and capability information of the power receiving device (S1007). Next, the power transmitting device 200 transitions to the negotiation phase of the WPC standard described above, and determines a GP value between the power transmitting device 200 and the power receiving device (S1008). After determining the GP, the power transmitting device 200 transitions to the calibration phase of the WPC standard described above. Here, the power transmitting device 200 notifies the power transmitting device 200 of a predetermined received power value (received power value in a light load state / received power value in a maximum load state) of the power receiving device, and performs adjustment so that the power transmitting device 200 transmits power efficiently.

[0103] Next, the power transmitting device 200 transitions to the Power Transfer phase of the WPC standard described above, and performs control for continuing power transmission and stopping power transmission due to an error or full charge (S1010), and the process returns to S1001. Note that when the power supply to the power transmitting device 200 is stopped, the power transmitting device 100 ends the process.

[0104] As described above, the power transmitting device of the present embodiment does not start the process for object detection in the power transmitting coil, that is, the process defined as the Selection phase of the WPC standard, when power is being transmitted to the power receiving device and the placement of an object is not detected. This can reduce the adverse effect on existing power transmission caused by the generation of radiation noise. In addition, unnecessary power consumption can be suppressed.

[0105] [System-wide processing] Next, an operation sequence of the power transmitting device 200 will be described with reference to Figs. 13 and 14. Here, for the sake of simplicity, the power transmitting device 200 has three power transmitting coils 209a to 209c and an object detection coil 211 as shown in Fig. 14(a). Note that, in an initial state, a power receiving device is not placed on the power transmitting device 200, and the power transmitting device 200 has a sufficient power transmitting capability to be able to transmit power at the GP requested by the power receiving device. Also, it is assumed that a threshold value for the amount of change in the physical quantity calculated by the object detection coil is set in advance in the power transmitting device 200 as a predetermined value. Note that the threshold value may be set by an input operation by a user. In the following description, the expression that a power receiving device is placed on the power transmitting coil 209 of the power transmitting device 200 includes the following cases. In other words, placing the power receiving device is synonymous with placing the power receiving device on a charging stand (placing surface) configured in close proximity to the power transmitting coil 209, or arranging the power receiving device in the vicinity of the power transmitting coil 209 (within the power transmission range).

[0106] In this embodiment, the power transmitting device 200 detects the placement of the first power receiving device 101a and starts power transmission. At this time, the power transmitting device 200, upon starting power transmission to the first power receiving device 101a, stops the transmission of A-Ping from the power transmitting coil 209 and starts object detection by transmitting an object detection signal from the object detection coil 211. When the second power receiving device 101b is placed, the state of the object detection coil 211 changes, causing a change in physical quantity, and the difference between the physical quantity and the object detection signal becomes equal to or greater than a threshold value, so that the power transmitting device 200 determines that an object has been placed. The power transmitting device 200 resumes the transmission of A-Ping from the power transmitting coil 209 to detect the placement of the second power receiving device 101b, and starts power transmission. After that, the power transmitting device 200 again stops the transmission of A-Ping from the power transmitting coil 209 and resumes object detection by transmitting an object detection signal from the object detection coil 211.

[0107] 13, the power transmitting device 200 is not transmitting power to the power receiving device, so the power transmitting coils 209a to 209c transmit A-Pings in sequence to wait for an object to be placed on the power transmitting device 200 (No in S1001, F1101). When the first power receiving device 300 is placed on the power transmitting device 200, a change occurs in the A-Ping transmitted from the power transmitting coil 209a, and the power transmitting device 200 detects that an object has been placed on the power transmitting device 200 (in the vicinity of the power transmitting coil 209a) by the subsequent D-Ping (F1105, F1106). Furthermore, the power transmitting device 200 detects from the D-Ping response that the placed object is a power receiving device (first power receiving device 300), and stores the fact that it has been placed on the power transmitting coil 209a (S1005, S1006).

[0108] Next, the power transmitting device 200 acquires identification information and capability information from the first power receiving device 300 through communication in the I&C phase (S1007, F1107). Next, the power transmitting device 200 and the first power receiving device 300 execute communication in the Negotiation phase, and it is assumed that GP=15 W is determined (S1008, F1108). Next, the power transmitting device 200 and the first power receiving device 300 derive calibration data through communication in the Calibration phase (S1009, F1109). Thereafter, the power transmitting device 200 executes power transmission to the first power receiving device 101a (S1010, F1110).

[0109] Next, since the power transmitting device is transmitting power to the first power receiving device 300, the power transmitting coil 209 stops transmitting A-Ping, the object detection coil 211 transmits an object detection signal, and calculates the change in physical quantity (S1001 to 1003, F1111 to 1113). At this time, since a new power receiving device is not placed and the calculated change in physical quantity is less than the threshold, it is determined that a new object has not been detected. In addition, the power transmitting device 200 repeatedly transmits the object detection signal and calculates the change in physical quantity at a predetermined interval (No in S1004, S1001 to 1003, F1112 to 1113). After that, when the second power receiving device 310 is placed, the power transmitting device 200 determines that a new object has been detected because the calculated change in physical quantity is equal to or greater than the threshold. The power transmitting device 200 resumes the transmission of A-Ping from the power transmitting coil 209b to 209c except for the power transmitting coil 209a that is transmitting power (Yes in S1004, F1114 to 1116). When the second power receiving device 101b is placed, a change occurs in the A-Ping transmitted from the power transmitting coil 209c, and the power transmitting device 200 detects that an object has been placed on the power transmitting coil 209c (F1117, F1118). Since the subsequent processing of F1119 to F1124 is similar to F1105 to F1110, a description thereof will be omitted. When power transmission to the second power receiving device 310 is executed via the power transmitting coil 209c, the power transmitting device 200 stops object detection by A-Ping in the power transmitting coil 209 again because the power transmitting device 200 is transmitting power to the first power receiving device 101a and the second power receiving device 101b. Furthermore, the power transmitting device 200 transmits an object detection signal from the object detection coil 211, and calculates the amount of change in the physical quantity (Yes in S1001, S1002 to 1003, F1125 to 1127).

[0110] According to the above-described operation, after starting power transmission to the power receiving device, the power transmitting device 200 stops transmitting A-Ping from each power transmitting coil 209 and starts object detection with the object detection coil. Then, the power transmitting device 200 detects the power receiving device by transmitting an object detection signal (A-Ping) from each power transmitting coil 209 based on the detection of an object using the object detection coil. At this time, the object detection coil is configured to include the entire power transmission range of the power transmitting coil group. Therefore, the number of times that the object detection signal is transmitted from the object detection coil in a predetermined time length is less than the total number of times that A-Ping is transmitted from each power transmitting coil in the same predetermined time length. This makes it possible to relatively suppress the generation of radiation noise, etc., and to detect the placement of a new power receiving device while reducing the adverse effect on power transmission to an existing power receiving device. In addition, by transmitting A-Ping only from the object detection coil, power consumption can be relatively reduced compared to transmitting A-Ping from each power transmitting coil.

[0111] In the above-described embodiment, when the power transmitting device starts transmitting power to the power receiving device, it stops transmitting A-Ping from each power transmitting coil and transmits an object detection signal from the object detection coil to calculate the change in physical quantity, but it is not necessary to transmit the object detection signal. At this time, the power transmitting device can calculate the change in physical quantity caused by the change in the state of the object detection coil caused by the power transmitted from the power transmitting coil during power transmission. This makes it possible to suppress the generation of radiation noise and unnecessary power consumption more effectively than when the object detection signal is transmitted.

[0112] In the above-described embodiment, when the power transmitting device is not transmitting power to the power receiving device, the power transmitting device transmits A-Pings in sequence from each power transmitting coil, but this is not limited to the above. That is, even when the power transmitting device 200 is not transmitting power to the power receiving device (when no power receiving device is placed), the power transmitting device 200 may transmit an object detection signal from the object detection coil 211 and perform object detection by calculating the amount of change in the physical quantity. This makes it possible to suppress unnecessary power consumption even when power is not being transmitted to the power receiving device.

[0113] In the above-described embodiment, the power transmitting device has an object detection coil configured to include the entire power transmission range of the power transmitting coil group, but is not limited thereto. For example, the power transmitting device 200 may select a specific power transmitting coil 209 other than the power transmitting coil 209 currently transmitting power, and transmit A-Ping from the determined specific power transmitting coil 209. This makes it possible to suppress the generation of radiation noise and unnecessary power consumption, as compared with the case where A-Pings are transmitted sequentially from a plurality of power transmitting coils. In addition, in this configuration, the power transmitting device 200 may not have an object detection coil 211 that surrounds the power transmitting coil group 210.

[0114] In the above-described embodiment, the power transmitting device has one object detection coil configured to cover the entire power transmission range of the power transmitting coil group, but is not limited thereto. The power transmitting device 200 may have a plurality of object detection coils. For example, a case will be described in which a plurality of object detection coils are arranged to cover the areas where each power transmitting circuit can transmit power (for example, the dedicated area 416 and the dedicated area 417 in FIG. 4). In this case, the power transmitting device 200 can start object detection only with the object detection coil that covers the area where the power transmitting circuit that is not transmitting power can transmit power, and when an object is detected, transmit A-Ping only with the power transmitting coil in the area covered by the object detection coil. In this way, by transmitting A-Ping only in the area where it is determined that an object has been detected, the number of times of signal transmission is reduced compared to the case where A-Ping is transmitted sequentially in the entire power transmission range. This makes it possible to relatively suppress the generation of radiation noise, etc., and detect the placement of a new power receiving device while further reducing the adverse effect on power transmission to an existing power receiving device.

[0115] (Embodiment 4) As described in the above-mentioned embodiment 1, when power is transmitted simultaneously from a plurality of power transmitting coils, if the power transmitting coils are not appropriately selected, there is a problem that the power transmitted from each power transmitting coil interferes with each other. In the embodiment 1, a method for suppressing interference by transmitting power using power transmitting coils having a positional relationship that does not interfere with each other (separated by a predetermined distance D or more) is described. In the present embodiment, another method for suppressing interference between power transmitting coils is described. In particular, in the present embodiment, a method for suppressing the influence (interference) between power transmitting coils in a case where a power transmitting coil transmits A-Ping for object detection while another power transmitting coil transmits A-Ping for object detection while a power transmitting coil transmits power for charging is described. Note that the same names and symbols are used for configurations similar to those in the above-mentioned embodiment.

[0116] [Processing in power transmission equipment] Fig. 15 is a flowchart showing a process executed by the power transmitting device 100. The flowchart shown in Fig. 15 can be realized by the control unit 201 of the power transmitting device 100 executing a control program stored in the memory 207, and performing calculations and processing of information and control of each piece of hardware.

[0117] First, when the power supply of the power transmitting device is turned on, the process starts (S1301). The power transmitting device 100 selects, from the power transmitting coil group 210, a first power transmitting coil to be used by the first power transmitting circuit 203 for power transmission and a second power transmitting coil to be used by the second power transmitting circuit 205 for power transmission via the control unit 201, and connects each power transmitting circuit to each power transmitting coil (S1302). Here, the power transmitting device 100 selects a power transmitting coil that does not cause interference with each other even when A-Ping power transmission is performed simultaneously from the first power transmitting circuit and the second power transmitting circuit. The selection method at this time may be, for example, the method described in the first embodiment.

[0118] Next, the power transmitting device 100 determines whether the power transmitting circuit is transmitting power (S1303). Since the power transmitting device has just been powered on, it is assumed that no power transmitting circuit is transmitting power (No in S1303). Next, the power transmitting device 100 transmits (transmits power) the above-mentioned A-Ping from each power transmitting coil connected to each power transmitting circuit (S1304). The power of the A-Ping is smaller than the transmission power during power transmission.

[0119] Next, the power transmitting device 100 determines whether or not a power receiving device is placed on the coil of the power transmitting device (S1305). When the power transmitting device 100 detects that an object is placed on the power transmitting device by A-Ping, the power transmitting device 100 detects the placement of the power receiving device through the above-mentioned Selection phase, Ping phase, and I&C phase.

[0120] Next, the power transmitting device performs power transmission processing through multiple phases defined in the above-mentioned WPC standard to the power receiving device detected in S1305, and starts power transmission (S1306).

[0121] Next, the power transmitting device 100 determines whether all the power transmitting circuits of the power transmitting device are being used (S1307). If all the power transmitting circuits are being used, the power transmitting device 100 ends the control for power transmission. Although not shown in FIG. 15, the power transmitting device 100 transmits power for charging until it receives a command (EPT) to stop power transmission from the power receiving device, for example, when the battery of the power receiving device becomes fully charged. Furthermore, when the power transmitting device 100 ends the power transmission for charging, it executes the process from S1303 onwards again to detect a new power receiving device. The process from S1303 onwards is repeated until the power transmitting device 100 is turned off. Furthermore, if no power receiving device is detected before a predetermined time has elapsed in S1305, the process returns to S1303 after the predetermined time has elapsed.

[0122] Next, a case where it is determined in S1303 that the power transmitting device is transmitting power will be described. Here, it is assumed that the first power transmitting circuit 203 and the second power transmitting circuit 205 are configured to transmit power using the first power transmitting coil and the second power transmitting coil, respectively. The reason for performing the control described here is as follows. That is, when power transmission from the first power transmitting coil and transmission of A-Ping, which is a signal for object detection, from the second power transmitting coil are performed simultaneously, the A-Ping, which has a small power, may be disturbed by the power of the transmitted power, which has a large power. Therefore, the A-Ping transmitted from the second power transmitting coil may not function correctly as a detection signal, which may lead to erroneous detection of an object. The power transmitting device 100 in this embodiment suppresses the problem of A-Ping being disturbed by performing the following processing.

[0123] When it is determined in S1303 that the power transmitting device is transmitting power (Yes in S1303), the power transmitting device 100 temporarily interrupts the power transmission from the first power transmitting circuit 203 to stop the power transmission. Then, during a period (moment) when the power transmitting device 100 stops power transmission, a detection signal is transmitted from another power transmitting coil that is not used for power transmission. Here, it is assumed that the second power transmitting coil is not used for power transmission, and a detection signal is transmitted from the second power transmitting coil. The power transmitting device 100 stops (momentarily interrupts) power transmission from the first power transmitting coil that is transmitting power for a predetermined period (S1308). Then, during a period when power transmission from the first power transmitting coil is stopped, a detection signal is transmitted from the second power transmitting coil that is not transmitting power (S1309). That is, during a period when power transmission from the first power transmitting circuit 203 that transmits power is stopped, an A-Ping is transmitted using the second power transmitting circuit 205 that is not transmitting power. Then, after stopping power transmission for a predetermined period, the power transmitting device 100 resumes power transmission (S1310). At this time, it is necessary that the A-Ping output by the second power transmitting circuit 205 for object detection does not overlap with the power transmission performed by the first power transmitting circuit 203. That is, the period during which power transmission from the first power transmitting coil is stopped is controlled to be longer than the period during which the detection signal is transmitted from the second power transmitting coil. Therefore, the predetermined period during which power transmission is stopped is longer than the period during which the second power transmitting circuit 205 detects an object. This process makes it possible to transmit the detection signal transmitted from the second power transmitting coil without overlapping the charging power transmitted from the first power transmitting coil and the detection signal transmitted from the second power transmitting coil.

[0124] The timing of stopping the power transmission for charging by the power transmitting device 100 and the timing of transmitting the detection signal will be described with reference to FIG. 16. In the above embodiment, the power transmitting device 100 performs the power transmission process using two power transmitting circuits and two power transmitting coils connected to each of the circuits. However, the present embodiment is not limited to this, and can be applied to the power transmission process using more power transmitting circuits and power transmitting coils. It is assumed that the first power transmitting circuit 203 is currently transmitting power for charging using the first power transmitting coil. The second power transmitting circuit 205 is also sequentially connected to the second power transmitting coil, the third power transmitting coil, and the fourth power transmitting coil, and transmits A-Ping from each of the power transmitting coils.

[0125] In FIG. 16, the first power transmitting coil is used for power transmission and transmits power to a power receiving device. After a predetermined time has elapsed, the first power transmitting circuit 203 stops (momentarily interrupts) power transmission from the first power transmitting coil for a predetermined period at a first timing (S1308). During the period in which power transmission is stopped, the second power transmitting circuit 205 transmits A-Ping using the second power transmitting coil (S1309). The first power transmitting circuit connected to the first power transmitting coil momentarily interrupts power transmission for a predetermined period, and then resumes power transmission (S1310). If the second power transmitting circuit 205 does not detect a power receiving device (S1305), after a predetermined time has elapsed, the first power transmitting circuit 203 stops (momentarily interrupts) power transmission from the first power transmitting coil for a predetermined period at a second timing (S1308). During the period when the power transmission is stopped, the second power transmission circuit 205 transmits A-Ping using the third power transmission coil (S1309). After the first power transmission circuit 203 has stopped power transmission for a predetermined period, it resumes power transmission (S1310). If the second power transmission circuit 205 does not detect a power receiving device (S1305), the first power transmission circuit 203 stops (momentarily interrupts) power transmission from the first power transmission coil for a predetermined period at a third timing after a predetermined time has elapsed (S1308). During the period when the power transmission is stopped, the second power transmission circuit 205 transmits A-Ping using the third power transmission coil (S1309). After the first power transmission circuit 203 has stopped power transmission for a predetermined period, it resumes power transmission (S1310).

[0126] The above-described process is repeated until the second power transmitting circuit 205 detects a power receiving device. When the second power transmission circuit 205 detects an object placed on the power transmission device using A-Ping and detects a power receiving device after going through a predetermined number of phases (S1305), the power transmission device starts transmitting power to the power receiving device detected in S1305 via the second power transmission circuit 205 (S1306).

[0127] In this way, the power transmitting device 100 can periodically check whether or not a power receiving device is present near each power transmitting coil by transmitting detection signals from the other power transmitting coils in turn while stopping the power transmission for charging. The timing at which the power transmitting device 100 stops the power transmission for charging may be set in advance in the power transmitting device 100. The predetermined period during which the power transmitting device 100 stops the power transmission may be set to a length that does not affect the power receiving process of the power receiving device. Alternatively, the power transmitting device 100 may perform the above process after determining whether or not there is a problem with the power transmission being interrupted based on the version of the power receiving device that is transmitting the power for charging. The power transmitting device 100 may transmit information indicating the timing of the power transmission being interrupted to the power receiving device in the negotiation phase, for example, or obtain the information from the power receiving device, thereby sharing the timing of the power transmission being interrupted with each other.

[0128] The configuration of the power transmission circuit and the power transmission coil is not limited to the above. For example, four power transmission circuits may be used, with the first power transmission coil connected to the first power transmission circuit, the second power transmission coil connected to the second power transmission circuit, the third power transmission coil connected to the third power transmission circuit, and the fourth power transmission coil connected to the fourth power transmission circuit. The number of power transmission coils may also be any number.

[0129] In the above embodiment, the power transmitting device 100 transmits the detection signal in order from the power transmitting coil not used for power transmission, but the A-Ping, which is the detection signal, may be transmitted simultaneously from a plurality of coils. That is, the power transmitting device may temporarily stop (flash) the power transmission from the first power transmitting coil, and transmit A-Ping simultaneously from the second power transmitting coil, the third power transmitting coil, and the fourth power transmitting coil during the period when the power transmission is stopped. Alternatively, the first power transmitting circuit may be connected to the first power transmitting coil and the second power transmitting coil, the second power transmitting circuit may be connected to the third power transmitting coil, and the third power transmitting circuit may be connected to the fourth power transmitting coil. In the above configuration, the power transmitting device 100 may temporarily stop (flash) the power transmission from the first power transmitting coil, connect the first power transmitting circuit to the second power transmitting coil, and transmit A-Ping simultaneously from the second power transmitting coil, the third power transmitting coil, and the fourth power transmitting coil. At this time, the combination of power transmitting coils that simultaneously transmit A-Pings may be determined using, for example, the method of the first embodiment described above.

[0130] In the above-described embodiment, the detection signal transmitted from the power transmitting device is described as a signal for detecting the power receiving device. However, the detection signal may be used to detect a foreign object (object) other than the power receiving device. If a foreign object, for example a conductor, exists on the power transmitting device, when the power transmitting device transmits power, the foreign object may consume power and generate heat. Therefore, the power transmitting device 100 may detect the presence of an object by the A-Ping transmitted in S1304 or S1309, and may control the power transmitting device 100 to stop transmitting power when it is determined that a "foreign object is present" or that a "foreign object may be present". The presence or absence of a foreign object can be determined by going through the above-described Ping phase, Selection phase, Ping phase, Identification and Configuration phase, and Negotiation phase. As a result, the power transmitting device shown in FIG. 14 can periodically check whether or not a foreign object exists near each power transmitting coil by transmitting a detection signal in order from the power transmitting coils not used for power transmission. Therefore, the power transmitting device can detect a foreign object on the power transmitting device with high accuracy.

[0131] Furthermore, a foreign object may be detected based on a transient response of the voltage or current in the power transmission coil when power transmission is momentarily interrupted.

[0132] In the above-described embodiment, the configuration is described in which power can be simultaneously transmitted from both the first power transmission circuit and the second power transmission circuit to the power receiving device. However, the configuration may be such that power is transmitted only from one of the power transmission circuits without transmitting power simultaneously from each power transmission circuit. That is, when the first power transmission coil detects the presence of the first power receiving device and detects the presence of the second power receiving device in the vicinity of the second power transmission coil (S1305), after S1305, one of the power receiving devices is selected based on a predetermined condition. Here, the predetermined condition for selecting the power receiving device may be, for example, the selection based on a priority (priority order) to be the power transmission target. The priority order is information for the power transmitting device to communicate with the first power receiving device and the second power receiving device and to determine the priority order. The reason why the power transmitting device selects one of the power receiving devices as the power transmission target is as follows. For example, when the transmission power transmitted from the first power transmission circuit and the second power transmission circuit is very large, even if the power transmission coil used for power transmission is appropriately selected, interference may occur between the power transmitted from the first power transmission circuit and the power transmitted from the second power transmission circuit. This is because there is a risk of communication errors occurring between the power transmission device and the power receiving device. In addition, there is a risk that the noise generated by transmitting power from multiple power transmission circuits will be greater than a reference value. Therefore, power interference is suppressed by performing "selection of a power receiving device" and transmitting power to the selected power receiving device.

[0133] Furthermore, even if power transmission from multiple power transmission circuits would exceed the power supply capacity of the hardware of the power transmission device, it is possible to transmit power appropriately by "selecting a power receiving device". Furthermore, even when such "selecting a power receiving device" is performed, the method of this embodiment periodically checks whether a new power receiving device has been installed on the power transmission device, and even if a new power receiving device with a high priority is installed, it is possible to detect it and start power transmission early.

[0134] (Embodiment 5) In this embodiment, the operation of the power transmitting device 100 when a first power receiving device 101a and a second power receiving device 101b are placed on the power transmitting coil group 210 will be described. A problem to be solved in this embodiment will be described with reference to Fig. 17. Fig. 17 is a diagram showing the arrangement of the power transmitting coil group 210 and the power receiving devices. Note that the configuration of the power transmitting device in this embodiment is the same as that in the first embodiment, and each of the first power transmitting circuit 203 and the second power transmitting circuit 205 of the power transmitting device 100 is capable of transmitting power to a maximum of one power receiving device.

[0135] In FIG. 17(a), the first power receiving device 101a is placed in the shared area 415, and no power receiving device is placed in the dedicated area 416 of the first power transmitting circuit 203 or the dedicated area 417 of the second power transmitting circuit 205. FIG. 17(b) shows that the second power receiving device 101b is placed in the dedicated area 416 of the first power transmitting circuit 203 in the state of FIG. 17(a). Here, it is assumed that the first power transmitting circuit 203 transmits power to the first power receiving device 101a placed in the shared area 415 in FIG. 17(a). In this case, when the second power receiving device 101b is newly placed in the dedicated area of ​​the first power transmitting circuit 203 as shown in FIG. 17(b), the first power transmitting circuit 203 cannot transmit power to the second power receiving device 101b. This is because the maximum number of power receiving devices to which the first power transmitting circuit 203 can transmit power simultaneously is one. Thus, even if the power transmission device 100 itself has two power transmission circuits and is configured to be able to transmit power to two power receiving devices simultaneously, there is a problem that power can only be transmitted to one power receiving device depending on the order and position in which the power receiving devices are placed.

[0136] In the following, an embodiment will be described in which a power transmitting device capable of transmitting power to a plurality of power receiving devices appropriately controls power transmission regardless of the placement conditions of the power receiving devices. Note that the same names and symbols are used for configurations similar to those of the other embodiments described above.

[0137] [Processing in power transmission equipment] The process performed by the power transmitting device in this embodiment will be described with reference to FIGS. 17 and 18. This process may be started in response to the power being turned on and the power transmitting circuit 203 being started by receiving power supply from the power supply unit 202, etc. This process may be realized by the control unit 201 executing a program stored in the memory 207. However, this is not limited to the above, and may be executed in response to the power transmission function being started by an operation such as pressing a predetermined button by a user. At least a part of the process shown in FIG. 18 may be realized by hardware. When at least a part of the process is realized by hardware, for example, a dedicated circuit automatically generated on an FPGA using a predetermined compiler from a program for realizing the processing steps may be used. Similarly to the FPGA, the hardware for executing the predetermined processing steps may be realized by a gate array circuit.

[0138] 18, the process starts when the power transmission device 100 is powered on. The power transmission device 100 transmits an A-Ping and determines whether a power receiving device has been placed (S1600). Here, as shown in FIG. 17(a), it is assumed that the first power receiving device 101a has been placed in the shared area 415. When the power transmission device 100 detects that a power receiving device has been placed (Yes in S1600), the process proceeds to S1602.

[0139] When the power transmitting device 100 transmits a D-Ping and receives a Signal Strength packet, it determines that the first power receiving device 101a has been detected. Here, it is assumed that the D-Ping was transmitted by the first power transmitting circuit 203. Here, the power transmitting device 100 compares the number of power receiving devices to which the power transmitting circuit is currently transmitting power (in the Power Transfer phase) with the upper limit of the number of power receiving devices to which the power transmitting circuit can transmit power (S1602). In the example of FIG. 17(a), the first power transmitting circuit 203 transmits D-Ping power to the first power receiving device 101a, but there is no power receiving device currently transmitting power in the Power Transfer phase, so the number of power receiving devices is 0. Also, the upper limit of the first power transmitting circuit 203 is 1 as described above. Since the upper limit is greater than the number of power receiving devices (Yes in S1602), the power transmitting device 100 advances the process to S1611. The power transmitting device 100 compares the number of power receiving devices currently transmitting power in the area where the power receiving device is detected with the upper limit of the number of power receiving devices to which the first power transmitting circuit 203 can transmit power in the area where the power receiving device is detected (S1611). Here, the number of power receiving devices in the shared area 415 is compared with the upper limit indicating the number of power receiving devices to which the first power transmitting circuit 203 can transmit power in the shared area 415. Currently, there is no power receiving device currently transmitting power in the shared area 415, so the number of power receiving devices is 0. Also, the upper limit of the number of power receiving devices to which the first power transmitting circuit 203 can transmit power in the shared area 415 is 1. Since the number of power receiving devices is smaller than the upper limit of the area (Yes in S1611), the power transmitting device 100 determines that the first power transmitting circuit 203 that detected the first power receiving device 101a will transmit power to the first power receiving device 101a (S1607), and ends the process. Since the power transmission circuit for transmitting power to the power receiving device has been determined, the power transmitting device 100 transmits power to the first power receiving device 101a based on the flow of FIG.

[0140] 17(b), it is assumed that the second power receiving device 101b is further placed in the dedicated area 416 of the first power transmitting circuit 203. The power transmitting device 100 detects the second power receiving device 101b using A-Ping (Yes in S1600). Although the power transmitting device 100 is transmitting power to the first power receiving device 101a, the power transmitting device 100 may detect the second power receiving device 101b using the object detection coil shown in the third embodiment. Furthermore, as shown in the fourth embodiment, the power transmitting device 100 may detect the second power receiving device 101b while the first power transmitting circuit momentarily interrupts the power transmission to the first power receiving device 101a in the shared area 416. Specifically, the power transmitting device 100 may detect the second power receiving device 101b placed in the dedicated area 416 using the power transmitting coil included in the dedicated area 416 during the momentary interruption.

[0141] When the power transmitting device 100 detects the second power receiving device 101b, it compares the number of power receiving devices with the upper limit (S1602). Since the first power transmitting circuit 203 is transmitting power to the first power receiving device 101a, the number of power receiving devices is 1. Since the upper limit of the first power transmitting circuit 203 is 1, it is determined that the upper limit is not greater than the number of power receiving devices (No in S1602). Then, the power transmitting device 100 acquires the placement area of ​​the detected power receiving devices, including the power receiving device currently transmitting power (S1601). It can be determined in which area the power receiving device is placed based on which power transmitting coil in FIG. 4(e) has received the Signal Strength Packet.

[0142] Since the first power transmission circuit 203 is currently transmitting power to the first power receiving device 101a in the shared area 415 (Yes in S1603), the power transmission device 100 selects another power transmission circuit capable of transmitting power in the shared area 415 (S1604). Here, since the second power transmission circuit 205 is capable of transmitting power in the shared area 415, the power transmission device 100 selects the second power transmission circuit 205 (S1604) and compares the number of power receiving devices to which the second power transmission circuit 205 is transmitting power with the upper limit of the number of power receiving devices to which power can be transmitted (S1605). Since the second power transmission circuit 205 is not transmitting power to any power receiving device at this point, the upper limit (=1) is greater than the number of power receiving devices (=0) (Yes in S1605). Next, the power transmission device compares the number of power receiving devices currently transmitting power in the shared area with the upper limit of the number of power receiving devices to which power can be transmitted in the shared area. Since power is being transmitted to the first power receiving device 101a in the shared area 415, the number of power receiving devices is 1. Furthermore, the upper limit of the number of power receiving devices to which the selected second power transmitting circuit 205 can transmit power in the shared area 415 is 1. Therefore, since the number of power receiving devices is equal to or less than the upper limit of the area (Yes in S1610), the power transmitting device 100 determines that the currently selected second power transmitting circuit 205 will transmit power to the first power receiving device 101a placed in the shared area 415 (S1606).

[0143] The power transmitting device 100 stops the power transmission of the first power transmitting circuit 203 currently transmitting power in the shared area 415 (S1609). The second power transmitting circuit 205 transmits power to the first power receiving device 101a in the shared area 415 based on the flow shown in FIG. 5. At this time, the first power transmitting circuit 203 is in a state of not transmitting power to any power receiving device. The power transmitting device 100 detects the second power receiving device 101b placed in the dedicated area 416 using the first power transmitting circuit 203 (S1600), and compares the number of power receiving devices currently transmitting power with the upper limit of the number of power receiving devices to which power can be transmitted (S1602). As a result of the comparison, it is determined that the upper limit (=1) of the first power transmitting circuit 203 is greater than the number of power receiving devices currently transmitting power (=0), and the process proceeds to S1611. Note that the power transmitting device 100 has already detected the second power receiving device 101b, so the detection process here may be omitted. The power transmitting device 100 compares the number of power receiving devices currently transmitting power (=0) with the upper limit (=0) of the number of power receiving devices to which power can be transmitted in the dedicated area 416 (S1611), and transmits power to the second power receiving device 101b (S1607).

[0144] The above is the power transmission control process performed by the power transmitting device 100 in this embodiment. By performing the above-mentioned control, it becomes possible to efficiently transmit power to a plurality of power receiving devices using a plurality of power transmitting circuits.

[0145] Another example of power transmission control will be described. Here, in FIG. 17(b), it is assumed that the second power receiving device 101b is placed in the dedicated area 416 of the first power transmitting circuit 203 first, and then the first power receiving device 101a is placed in the shared area 415. In this case, the power transmitting device 100 first transmits power to the second power receiving device 101b using the first power transmitting circuit 203. Next, when the first power receiving device 101a is placed in the shared area 415, the power transmitting device 100 detects the first power receiving device 101a by the first power transmitting circuit 203 or the second power transmitting circuit 205. If the first power transmitting circuit 203 detects the first power receiving device 101a, the result in S1602 is No, so the power transmitting device 100 selects the second power transmitting circuit 205 in S1604 and transmits power to the first power receiving device 101a using the second power transmitting circuit 205. Furthermore, if the second power transmitting circuit 205 detects the first power receiving device 101a, the result in S1602 becomes Yes, and therefore the second power transmitting circuit 205 transmits power to the first power receiving device 101a in S1607.

[0146] Although not shown, assume that a third power receiving device is placed in the dedicated area 417 of the second power transmitting circuit 205 in the state of FIG. 17(b). In this case, the upper limit (=1) of the number of power receiving devices to which the second power transmitting circuit 205 can transmit power is not greater than the number (=1) of power receiving devices currently transmitting power (No in S1605). Therefore, the power transmitting device 100 determines that none of the power transmitting circuits transmit power to the third power receiving device (S1608). Note that, when detecting the third power receiving device, the power transmitting device 100 may detect the second power receiving device 101b with the object detection coil shown in the third embodiment. Also, as described in the fourth embodiment, the power transmitting device 100 may momentarily interrupt the power transmission performed by the first power transmitting circuit 203 in the dedicated area 416 and the second power transmitting circuit 205 in the shared area 416, and operate based on the flow of FIG. 15. Specifically, the first power transmitting circuit 203 periodically transmits A-Ping during the momentary interruption using the power transmitting coils included in the dedicated area 416 and the common area 416. The second power transmitting circuit 205 may periodically transmit A-Ping during the momentary interruption using the power transmitting coils included in the dedicated area 417 and the common area 416 to detect the third power receiving device.

[0147] 15(c), when the first power receiving device 101a and the second power receiving device 101b are placed in the dedicated areas of the first power transmitting circuit 203 and the second power transmitting circuit 205, respectively, the following operation is performed: That is, the first power transmitting circuit 203 and the second power transmitting circuit 205 transmit power to the first power receiving device 101a and the second power receiving device 101b according to the processes of S1602, S1611, and S1607, respectively.

[0148] 15(d), consider a case where the first power receiving device 101a is first placed in the dedicated area 416 of the first power transmitting circuit 203 and the first power transmitting circuit 203 is transmitting power to the first power receiving device 101a, and then the second power receiving device 101b is placed in the dedicated area 416 of the first power transmitting circuit 203. In this case, the power transmitting device 100 detects the second power receiving device 101b by using the method described in the above-mentioned embodiment 3 or embodiment 4. In this case, when the second power receiving device 101b is placed, power cannot be transmitted to the power receiving devices in the dedicated area 416 any more (No in S1610), so the power transmitting device 100 decides not to transmit power to the detected second power receiving device 101b via any of the power transmitting circuits (S1608).

[0149] [System-wide processing] The processing of the entire system will be described with reference to Figs. 17(a), (b) and 19. The power transmitting device 100 transmits A-Ping using the first power transmitting circuit 203 and the second power transmitting circuit 205 (F1701), and performs detection processing of the power receiving device. Here, it is assumed that the first power receiving device 101a is placed in the common area 415 and detected by the A-Ping transmitted by the first power transmitting circuit 203. The first power transmitting circuit 203 transmits D-Ping to the first power receiving device 101a (F1701), and transmits power for charging according to the flow shown in Fig. 5 (F1702). Here, it is assumed that the second power receiving device 101b is further placed in the dedicated area 416 of the first power transmitting circuit 203 and detected by the A-Ping transmitted by the first power transmitting circuit 203 (F1703). The first power transmitting circuit 203 transmits a D-Ping (F1711) and performs the process of S1602 in Fig. 18. Since the first power transmitting circuit 203 is already transmitting power to the first power receiving device 101a (No in S1602), the power transmitting device 100 selects the second power transmitting circuit 205 in S1604 and controls the second power transmitting circuit 205 to transmit power to the first power receiving device 101a (S1609). In addition, the power transmitting device 100 stops the power transmission to the first power receiving device 101a by the first power transmitting circuit 203 (S1609, F1704). Note that, although the D-Ping is transmitted at F1711 in Fig. 19, the power transmission may be stopped at F1704 without transmitting the D-Ping.

[0150] The second power transmitting circuit 205 transmits A-Ping (S1705) and D-Ping (F1706) to transmit power to the first power receiving apparatus 101a (F1707). The first power transmitting circuit 203 transmits A-Ping (S1708) and D-Ping (F1709) to transmit power to the second power receiving apparatus 101b (F1710).

[0151] As described above, when a power receiving device is placed on the power transmitting device in this embodiment, the power transmitting device determines a power transmitting circuit to transmit power to the placed power receiving device based on the upper limit of the number of power receiving devices to which the power transmitting circuit can transmit power and the area in which the power receiving device is placed. This makes it possible to transmit power to multiple power receiving devices simultaneously, even when the power receiving devices are placed as shown in FIG. 17(b).

[0152] According to the above-mentioned method, the power transmitting device 100 determines the power transmitting circuit to transmit power to the placed power receiving device based on the upper limit of the number of power receiving devices to which the power transmitting circuit can transmit power and the area in which the power transmitting device is placed. However, the present invention is not limited to this, and the power transmitting device 100 may determine the power transmitting circuit to transmit power to the power receiving device based on the fact that the power transmitting circuit is performing a predetermined process for the power receiving device. For example, when the number of power receiving devices to which the power transmitting circuit can simultaneously transmit power is 1, the power transmitting device 100 determines whether the power transmitting circuit is performing the following process. That is, the power transmitting device 100 determines whether the power transmitting circuit is transmitting A-Ping (selection phase) or D-Ping (negotiation phase, power transfer phase). In the process of S1602 and S1605 shown in FIG. 18, the power transmitting device 100 determines No if the power transmitting circuit is transmitting A-Ping or D-Ping, and determines Yes if the power transmitting circuit is not transmitting power. As a result, the power transmitting circuit 100 determines that the power transmitting circuit that has already transmitted an A-Ping or a D-Ping cannot transmit power to a new power receiving device any more.

[0153] Furthermore, when the power transmitting device 100 of the present embodiment receives a Signal Strength Packet in response to the transmitted D-Ping, it determines that the first power receiving device 101a has been detected. However, this may be changed to determining that an object exists in the vicinity in response to an A-Ping.

[0154] As shown in FIG. 15(d), when the number of power receiving devices placed exceeds the upper limit of the power transmission circuit to which the power transmission circuit can transmit power or the upper limit of the power receiving devices to which the power transmission circuit can transmit power in the same area, the following process may be performed. For example, the power transmitting device 100 may transmit a message regarding the "number of power receiving devices" to the second power receiving device 101b to which the power transmitting device 100 was placed later, using the communication unit. Specifically, the message may be a message indicating that "the power transmitting device or the power transmitting circuit has exceeded the upper limit of the number of power receiving devices to which the power transmitting device or the power transmitting circuit can transmit power simultaneously" or "the power transmitting device or the power transmitting circuit has exceeded the upper limit of the number of power receiving devices to which the power transmitting device or the power transmitting circuit can transmit power in the same area". Alternatively, the message may simply be a message indicating "many, much" or "too much". The message may also be a message regarding the "distance between the multiple power receiving devices". Specifically, the message may be a message indicating that "the distance between the multiple power receiving devices placed is close" or simply "close" or "too close". In this way, the power transmitting device 100 can notify the power receiving device of the reason for not transmitting power, and the power receiving device can recognize the reason why the power transmitting device 100 does not transmit power.

[0155] Furthermore, the power receiving device that has received the message may display on the UI of the power receiving device a message urging the user to place the power receiving device in a different position of the power transmitting coil group 210 so that power can be transmitted to the power receiving device. For example, a message such as "Place the charging device in a different location", "The distance to other charging devices (power receiving devices) is too close for wireless charging", or "Place the charging device farther away from other charging devices (power receiving devices) for wireless charging" may be displayed.

[0156] Also, the attributes of the charging device (power receiving device) may be detected by the Identification packet, Extended Identification packet, and Configuration packet defined in the WPC standard, and the attributes may be displayed on the UI. For example, if the first power receiving device 101a is a smartphone and the second power receiving device 101b is a smartwatch, the following display may be displayed on the UI of the smartwatch. For example, the display may show "Please place the device in a different location from the smartphone for wireless charging", "The device is too close to the smartphone for wireless charging", or "Please place the device farther away from the smartphone for wireless charging".

[0157] If a user who has confirmed the above-mentioned message moves, for example, the second power receiving device 101b in FIG. 15(d) to the shared area 415, the power transmitting device 100 becomes able to transmit power to the second power receiving device 101b. In this way, the power transmitting device notifies the power receiving device of the reason why power cannot be transmitted, and the notified power receiving device displays the device attributes on the UI in addition to the reason why power cannot be transmitted or a method for enabling power transmission. In this way, it becomes possible to transmit power to the power receiving device. Although not shown, a similar message can also be displayed in a case where, for example, the first power receiving device 101a and the second power receiving device 101b are both placed in the shared area 416 and no other power receiving device is placed there.

[0158] In addition, in FIG. 15(b), the power transmitting device 100 switches the power transmitting circuit that transmits power to the first power receiving device 101a from the first power transmitting circuit 203 to the second power transmitting circuit 205. Then, the second power transmitting circuit 205 starts A-Ping power transmission (S500, F1705), that is, the Selection phase, according to the flow of FIG. 5. However, although the power transmitting circuit is switched from the first power transmitting circuit 203 to the second power transmitting circuit 205, the power transmitting device 100 has already grasped the information of the first power receiving device 101a, so the second power transmitting circuit 205 may start in the middle of the flow of FIG. 5. Specifically, the Negotiation process and the Calibration process may be omitted, and power transmission in the Power Transfer phase may be started. By doing so, power transmission to the first power receiving device 101a can be started early.

[0159] In addition, when the first power receiving device 101a is a device having a display unit such as a smartphone, and the second power receiving device 101b is a device not capable of displaying such as a wireless earphone, the power transmitting device may display the following information on the smartphone during charging. The information displayed by the power transmitting device on the smartphone is, for example, the upper limit of the number of power receiving devices to which the power transmitting device can transmit power, a message indicating that the upper limit of power transmission in the same area has been exceeded, and information on devices that cannot be charged. The power transmitting device may display information on the wireless earphone on the display unit of the smartphone during charging. For example, a message may be displayed saying "Please place the wireless earphone in a different location from the smartphone to wirelessly charge it" or "The distance between the wireless earphone and the smartphone is too close to wirelessly charge it." In addition, a message may be displayed saying "Please place the wireless earphone away from the smartphone to wirelessly charge it." This allows the user to check information on devices that do not have a display unit (such as wireless earphones).

[0160] The power transmitting device 100 may also transmit a message to the second power receiving device 101b placed later, indicating that the communication unit has exceeded the upper limit of power transmission or the upper limit of power transmission in the same area. If the power transmitting circuit has exceeded the upper limit of power transmission or the upper limit of power transmission in the same area, the power transmitting device may display the reason why power transmission is not possible on the display unit of the device to which power cannot be transmitted. For example, the power transmitting device may display a message such as "The number of devices that can be wirelessly charged simultaneously has been exceeded" or "Please stop wireless charging of other devices to perform wireless charging."

[0161] In addition, the power transmitting coil 402, the power transmitting coil 403, the power transmitting coil 405, the power transmitting coil 408, the power transmitting coil 409, and the power transmitting coil 411 present in the shared area 416 are exclusively connectable to both the first power transmitting circuit 203 and the second power transmitting circuit 205. However, this does not mean that each power transmitting circuit is not connectable to all of the above power transmitting coils as long as either the first power transmitting circuit 203 or the second power transmitting circuit 205 can transmit power to a power receiving device placed in the shared area 416. For example, the first power transmitting circuit 203 may be connectable to the power transmitting coil 402, the power transmitting coil 403, and the power transmitting coil 405, and the second power transmitting circuit 205 may be connectable to the power transmitting coil 408, the power transmitting coil 409, and the power transmitting coil 411.

[0162] In addition, the power receiving device is configured to display a UI based on a message transmitted by the communication unit of the power transmitting device, but the message may be transmitted by a communication unit other than the communication unit of the power transmitting device that conforms to the WPC standard. The communication unit may be a communication unit conforming to the Bluetooth Low Energy standard, the Wi-Fi standard, or the NFC standard.

[0163] In the present embodiment, the power transmitting device 100 has been described as having two power transmitting circuits, the first power transmitting circuit 203 and the second power receiving device 101b, and one shared area 415. However, it is clear that the present invention can be applied to a case where there are any number of power transmitting circuits and any number of shared areas 415 and dedicated areas.

[0164] (Other embodiments) The above-mentioned first to fifth embodiments can be implemented in any combination.

[0165] The present disclosure can also be realized by a process in which a program for implementing one or more functions of the above-described embodiments is supplied to a system or device via a network or a storage medium, and one or more processors in a computer of the system or device read and execute the program. It can also be realized by a circuit (e.g., ASIC) that implements one or more functions. [Explanation of symbols]

[0166] 100 Power transmission equipment 201 Control section 203 First power transmission circuit 205 Second power transmission circuit 209 Transmission Coil 210 Transmission coil group

Claims

1. A plurality of coils; A transmitting means for transmitting a plurality of pings through the plurality of coils; An acquisition means for acquiring identification information from one or more power receiving devices; a power transmitting means for transmitting power wirelessly to a first power receiving device via a first coil included in the plurality of coils and corresponding to a first power receiving device included in the plurality of power receiving devices when the plurality of power receiving devices are present, and transmitting power wirelessly to a second power receiving device via a second coil included in the plurality of coils and corresponding to a second power receiving device included in the plurality of power receiving devices, A power transmitting device characterized in that the transmitting means does not transmit a Ping for detecting the power receiving device via a coil in the vicinity of the first coil while wirelessly transmitting power to the first power receiving device via the first coil.

2. A method performed by a power transmitting device, comprising: Send multiple pings through multiple coils, obtaining identification information from one or more power receiving devices after transmitting the Ping; When there are a plurality of power receiving devices, wirelessly transmitting power to a first power receiving device via a first coil included in the plurality of coils and corresponding to the first power receiving device included in the plurality of power receiving devices; wirelessly transmitting power to a second power receiving device via a second coil included in the plurality of coils and corresponding to the second power receiving device included in the plurality of power receiving devices; A method comprising the steps of: not transmitting a ping to detect a power receiving device via a coil in the vicinity of the first coil while wirelessly transmitting power to the first power receiving device via the first coil.

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