Power transmission device, power transmission device control method, and program

Abstract

To perform appropriate control over wireless power transmission in a power transmission device including a plurality of power transmission coils.SOLUTION: A power transmission device 100 comprises: a power transmission coil group 210 for wirelessly transmitting power to a power receiving device, the power transmission coil group 210 including a first power transmission coil 209, and a second power transmission coil 209 arranged at a position closer than a position separated by a prescribed distance from the first coil; and a control unit 201 that implements detection for detecting an object by having a signal for detecting the object be output from some of the power transmission coils within the power transmission coil group 210, and that, on the basis of the detected object being a power receiving device, wirelessly transmits power to the power receiving device using at least one power transmission coil 209 and performs a control such that signals for detecting the object are not simultaneously output from the first power transmission coil 209 and the second power transmission coil 209.SELECTED DRAWING: Figure 2

Description

[Technical Field]

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

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

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

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2018-186699 Summary of the Invention [Problem to be solved by the invention]

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

[0006] An object of the present disclosure is to provide a technology that allows appropriate control of wireless power transmission in a power transmission device having multiple power transmission coils. [Means for solving the problem]

[0007] The power transmission device of the present disclosure is characterized by having a plurality of coils used to wirelessly transmit power to a power receiving device, the plurality of coils including a first coil and a second coil positioned closer than a predetermined distance from the first coil, a detection means for detecting an object by outputting a signal for detecting the object from some of the plurality of coils, a power transmission means for wirelessly transmitting power to the power receiving device using at least one of the plurality of coils based on the object detected by the detection means being a power receiving device, and a control means for controlling the first coil and the second coil so that signals for detecting the object are not output simultaneously. [Effects of the Invention]

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

[0009] [Figure 1] FIG. 1 is a diagram illustrating a configuration of a wireless power transmission system. [Figure 2] FIG. 2 is a diagram illustrating an example of a functional configuration of a power transmitting device. [Figure 3] FIG. 2 is a diagram illustrating an example of a functional configuration of a power receiving device. [Figure 4] 3A and 3B are diagrams illustrating an example of the configuration of a power transmission coil group included in a power transmission device. [Figure 5] 10A and 10B are diagrams for explaining processing performed by a power transmitting device and a power receiving device that comply with the WPC standard. [Figure 6] 10A and 10B 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 processing 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]FIG. 10 is a sequence diagram for explaining processing performed by a power transmitting device and a power receiving device in the second embodiment. [Figure 10] 10 is a flowchart illustrating processing performed by a power transmitting device according to the second embodiment. [Figure 11] 3A and 3B are diagrams illustrating an example of the configuration of a power transmitting device and a power transmitting coil group included in the power transmitting device. [Figure 12] 11 is a flowchart illustrating processing 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 a third embodiment. [Figure 14] FIG. 2 is a diagram illustrating an example of the arrangement of a power transmission coil group and a power receiving device. [Figure 15] 10 is a flowchart illustrating processing performed by a power transmitting device according to a fourth embodiment. [Figure 16] 3A and 3B are diagrams illustrating timings of power transmission and detection signal transmission performed by the power transmitting device. [Figure 17] FIG. 1 is a diagram illustrating an example of an arrangement of power receiving devices. [Figure 18] 13 is a flowchart illustrating processing 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 INVENTION

[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 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 according to 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 according to this embodiment has a function of simultaneously charging the first power receiving device 101a and the second power receiving device 101b that are placed within a range from 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, placing a power receiving device includes the following states: The state in which the power receiving device is placed includes, for example, a case in which the power receiving device is placed (installed) on a surface within a range in which the power transmitting device can transmit power. However, the method described in this embodiment is applicable at least to a state in which the power receiving device is included within a range in which the power transmitting device can transmit power, and for example, the power receiving device and the power transmitting device may be in a non-contact state. 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 illustrating the 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 power transmitting coils 209a to 209b can be two or more. In the following description, when there is no particular need to distinguish between them, they will simply be referred to as power transmitting coils 209. 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 also include an application specific integrated circuit (ASIC), a field programmable gate array (FPGA), or the like, 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, for example, a DC voltage supplied by the power supply unit 202 into an AC voltage using a switching circuit with a half-bridge or full-bridge configuration using FETs (Field Effect Transistors). In this case, the power transmitting circuit 203 includes a gate driver that controls the ON / OFF of the FETs.

[0017] The first communication unit 204 performs control communication for wireless power transmission with a communication unit of the power receiving device (described later) based on a standard established by the Wireless Power Consortium (WPC) (hereinafter referred to as the WPC standard). 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 superimposes the communication data on the transmitted power, thereby transmitting the communication data to the power receiving device. The first communication unit 204 also receives communication data transmitted from the power receiving device by demodulating the AC voltage or AC current modulated by a communication unit of the power receiving device (described later). This process realizes 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 communication data, thereby realizing control communication.

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

[0019] The power transmitting coil group 210 has a plurality of power transmitting coils 209. Any one or more of the plurality of power transmitting coils 209 are connected to the first power transmitting circuit 203 or the second power transmitting circuit 205. The selection unit 208 connects any one or more of the power transmitting coils 209 included in the power transmitting coil group 210 to the first power transmitting circuit 203 or the second power transmitting circuit 205. The selection unit 208 connects the first power transmitting circuit 203 to any one or more of the power transmitting coils 209, and connects the second power transmitting circuit 205 to one or more other of the power transmitting coils 209. The control unit 201 controls the selection unit 208 to determine which of the power transmitting coils 209 are to be connected to the first power transmitting circuit 203 and the second power transmitting circuit 205. The selection unit 208 switches the connections between the first power transmitting circuit 203 and the second power transmitting circuit 205 and the power transmitting coils in accordance with the control of the control unit 201. 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 simultaneously transmit power for charging to a maximum of one power receiving device. That is, the power transmitting device 100 can charge up to 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 this is not limiting. Two or more of the above blocks may be integrated into one chip or the like. Furthermore, 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. In this embodiment, the first power receiving device 101a and the second power receiving device 101b have the same functional configuration, and when there is no particular need to distinguish between 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 different types of devices. 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 CPU (Central Processing Unit) or an MPU (Micro Processing Unit). The control unit 301 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 amount of 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 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 overall state and each element of the power receiving device 101 and the wireless power transmission system.

[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 this is not limiting. Two or more of the above blocks may be integrated into a single chip, etc. Furthermore, one block may be divided into multiple blocks.

[0028] The power receiving device 101 and the power transmitting device 100 may have a function to execute applications 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 storage devices such as hard disk drives or memory devices, or information processing devices such as personal computers (PCs). The power receiving device 101 and the power transmitting device 100 may be image input devices such as imaging devices (cameras, video cameras, etc.) or scanners, or image output devices such as printers, copiers, and projectors. The power transmitting device 100 may be a smartphone. In this case, the power receiving device 101 may be another smartphone or wireless earphones. The power transmitting device 100 may be a charger installed in a console or the like inside a vehicle.

[0029] Next, the configuration of the power transmitting coil group 210 included in the power transmitting device 100 of 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 multiple power transmitting coils 209 on a two-dimensional xy plane. However, the multiple power transmitting coils 209 may actually be arranged in a three-dimensional space including the height direction. Note that the arrangement of the multiple power transmitting coils shown in FIG. 4 is an example and is not limited to this. Furthermore, power transmitting coils 400 to 411 in the following description correspond to the multiple power transmitting coils 209 that make up the power transmitting coil group 210.

[0030] 4(a) and 4(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 so 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 so 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 so that the circumference of the power transmitting coil is in contact with the other two coils.

[0031] FIG. 4(b) shows the 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 the arrangement of power transmitting coils 400 to 405 shown in FIG. 4(b) reversed from side to side. Power transmitting coil 409, power transmitting coil 410, and power transmitting coil 411 are each arranged so 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 so 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 so 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 transmission coil group 210. The power transmission coil group 210 is configured by arranging the power transmission coils 400 to 405 shown in Fig. 4(a) on top of the power transmission coils 406 to 411 shown in Fig. 4(b).

[0033] FIG. 4(d) is a diagram illustrating the positional relationship between the power transmitting coils. FIG. 4(d) shows power transmitting coils 400, 401, 410, and 411 from 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 this 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 this positional relationship are expressed as "not overlapping." Furthermore, distance 412 is the distance between a tangent to the circumference of the power transmitting coil 400 and a tangent to the circumference of the power transmitting coil 411. Each tangent passes through the intersection of the circumference of each power transmitting coil and 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. That is, distance 412 is the shortest distance between power transmitting coil 400 and power transmitting coil 411, and indicates that power transmitting coil 400 and power transmitting coil 411 are separated by distance 412. Note that in the present embodiment, the definition of the distance between power transmitting coils is the distance between positions on the power transmitting coils when the multiple power transmitting coils are viewed from above, but the definition of distance is not limited to this. For example, the center of gravity of the power transmitting coil may be used as a reference point, and the distance between the reference points of the power transmitting coils may be the distance between the power transmitting coils. Furthermore, although distance 412 in FIG. 4(d) is the distance on the xy plane, the multiple coils may be disposed at any positions in 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 xyz space or 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 ranges in which the first power transmitting circuit 203 and the second power transmitting circuit 205 can transmit power. The first power transmitting circuit 203 in this embodiment is connectable to power transmitting coils 400, 401, 402, 403, 405, 408, 409, 410, and 411. This allows the first power transmitting circuit 203 to transmit power to the power receiving device 101 placed in an area 413 indicated by a dotted line. The second power transmitting circuit 205 in this embodiment is connectable to power transmitting coils 402, 403, 404, 405, 406, 407, 408, 409, and 411. This allows the second power transmitting circuit 205 to transmit power to the power receiving device 101 placed in an area 414 indicated by a dashed-dotted line.

[0036] The area 415 is a common area where the area 413 and the area 414 overlap. The area 415 is a range in which 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 the shared area 415. The area of the area 413 excluding the shared area 415 is referred to as the 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 by the first power transmitting circuit 203. The area of the area 414 excluding the shared area 415 is referred to as the 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, a control flow between the power transmitting device 100 and the power receiving device 101 in this embodiment will be described. First, control of wireless power transmission compliant with the WPC standard will be described. FIG. 5 is a sequence diagram showing a control flow of the power transmitting device and the power receiving device compliant with the WPC standard v1.2.3. The sequence shown in FIG. 5 is not limited to the power transmitting device 100 having multiple power transmitting coils and multiple power transmitting circuits as in this embodiment, but is control executed by a power transmitting device having a configuration that complies with 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, although the following description will be given of a case where the power transmitting device and the power receiving device comply with the WPC standard v1.2.3, this is not limiting. That is, the power transmitting device and the power receiving device of the present disclosure may comply with the WPC standard version later than WPC standard v1.2.3, or may comply with a version earlier than WPC standard v1.2.3.

[0038] The WPC standard defines multiple phases, including a power transfer phase in which power is transmitted for charging, and phases before power is transmitted for charging. 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. Note that the identification and configuration phase will be referred to as the I&C phase below.

[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 present near the power transmitting coil 209. A method for controlling the A-Ping in this embodiment will be described later. The A-Ping is a pulsed power used to detect an object. Even if the power receiving device receives the A-Ping, the power is so small that it cannot activate the control unit 301 of the power receiving device 101. The power transmitting device 100 transmits the A-Ping intermittently. Here, the voltage and current applied to the power transmitting coil 209 change depending on whether an object is placed within 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 current value of the power transmitting coil 209 when the A-Ping is transmitted. If the detected voltage value is below a certain threshold or the detected current value is above a certain threshold, 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 an A-Ping, it measures the Q-factor (Quality Factor) of the power transmitting coil 209 (F501). When the power transmitting device 100 finishes measuring the Q-factor, it starts transmitting a Digital Ping (hereinafter referred to as a D-Ping) (F502). The D-Ping is power for activating the control unit 301 of the power receiving device 101 and is greater than the A-Ping. After that, the power transmitting device 100 continues to transmit power equal to or greater than the D-Ping from the start of D-Ping transmission (F502) until it receives an End Power Transfer (EPT) packet from the power receiving device 101 requesting that power transmission be stopped (F522). When the control unit 301 of the power receiving device 101 receives the D-Ping and activates, 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 conforms 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 Configuration packet, the power transmitting device 100 determines whether the version of the WPC standard to which the power receiving device 101 conforms corresponds to the version of the WPC standard to which the power receiving device 101 conforms, and transmits an ACK. Specifically, if the power transmitting device 100 determines that the power receiving device 101 conforms to an extended protocol of WPC standard v1.2 or later (including processing in the Negotiation phase, which will be described later), it responds with an ACK (F506). Upon receiving the ACK, the power receiving device 101 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 Q value measurement, and transmits an ACK to the power receiving device indicating that it has determined that there is a high possibility that no foreign object is present (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 will be referred to as a GRQ (CAP) packet. When the power transmitting device 100 receives the GRQ (CAP) packet, it transmits a Capability packet (hereinafter referred to as CAP) that stores information about capabilities supported by the power transmitting device 100 (F536).

[0044] The power receiving apparatus 101 negotiates Guaranteed Power (hereinafter referred to as GP), which is the maximum value of power that the power receiving apparatus 101 requests to receive. Specifically, Guaranteed Power represents the amount of power that the power receiving apparatus 101 can use, agreed upon in negotiation with the power transmitting apparatus 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 apparatus 101. The negotiation is realized by transmitting to the power transmitting apparatus 100 a packet that stores the value of Guaranteed Power requested by the power receiving apparatus, out of the Specific Request packets defined in the WPC standard (F509). In this embodiment, this 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 transmission capability and the like. If the power transmitting device 100 determines that Guaranteed Power can be accepted, it transmits an ACK indicating that the request has been accepted (F510). When the power receiving device 101 completes negotiation of multiple parameters including Guaranteed Power, it transmits an SRQ (EN) of the Specific Requests requesting the end of 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), terminates the negotiation, and transitions to a calibration phase in which a standard for performing foreign object detection based on a power loss method is created. Note that foreign object detection is a process of determining whether an object other than the power receiving device (hereinafter referred to as a foreign object) exists or there is a possibility that a foreign object exists within the power transmission 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 with the power receiving unit 302 not connected to the 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 and R1, which is the power loss. After receiving the ACK, the power receiving device 101, with the power receiving unit 302 and the load connected, transmits a Control Error packet (hereinafter referred to as CE) to the power transmitting device 100 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 it is negative, it indicates a request to decrease the receiving voltage; and if the numerical value is zero, it indicates a request to maintain the receiving voltage. Here, the power receiving device transmits CE(+) to the power transmitting device 100, indicating that the receiving voltage should be increased (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 the load, and transmits RP2 (Received Power packet (mode 2) (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 transmitted power value T2 and calculates the difference Δ2 between T2 and R2, which is the power loss. The power transmitting device 100 performs foreign object detection based on the power loss, using as reference the power loss Δ1 when the power receiving unit 302 is not connected to a load and the load's power consumption is zero, and the power loss Δ2 when the power receiving unit 302 is connected to a load and the load's power consumption is not zero. Specifically, the power transmitting device 100 can predict the power loss in a state where there is no foreign object at any received power value from Δ1 and Δ2, and perform foreign object detection based on the actually received received power value and transmitted power value. When the power transmitting device 100 sends 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 that the power receiving device can receive, as negotiated in the Negotiation phase. The power receiving device 101 periodically transmits to the power transmitting device 100 an RP0 (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 any 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 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 100 that complies with the WPC standard v1.2.3.

[0051] Next, an example of control when the power transmitting device 100 having multiple 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 processing shown in Fig. 5. Note that, for the sake of simplicity, some processing is omitted in Fig. 6, but in reality, processing similar to the processing shown in Fig. 5 is executed.

[0052] First, the first power transmitting circuit 203 and the second power transmitting circuit 205 each use the power transmitting coil 209 connected thereto to intermittently transmit A-Pings to detect power receiving devices placed within the power transmitting range of the power transmitting 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 transmitting coil 209 to which the first power transmitting circuit 203 is connected, the first power receiving device 203 transmits D-Pings to the first power receiving device 101a (F542, 543). Furthermore, the first power transmitting circuit 203 performs the control communication described above, 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 transmitting 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). Furthermore, the second power transmitting circuit 205 performs the control communication described above, transitions to the Power Transfer phase, and transmits power for charging to the second power receiving device 101b (F547). Through the above-described processing, the power transmitting device 100 can simultaneously charge a plurality of power receiving devices.

[0054] [Processing in power transmission equipment] The following describes a problem to be solved in this embodiment. When the first power transmitting circuit 203 and the second power transmitting circuit 205 perform control communication and power transmission, respectively, the power transmitted by a power transmitting coil connected to one power transmitting circuit may be superimposed on the power of a power transmitting coil connected to the other power transmitting circuit. This phenomenon is referred to as interference in this embodiment. The definitions of interference and non-interference are described below. Two power transmitting coils "do not interfere" as follows: That is, when the voltage / current amplitude fluctuations or frequency fluctuations of a modulated signal transmitted and received by one of the two power transmitting coils are not observed by the other power transmitting coil, or when the observed level is below a predetermined value and does not affect the demodulation performance when a communication unit demodulates the other modulated signal. Furthermore, two power transmitting coils "interfere" as follows: That is, when the voltage / current amplitude fluctuations or frequency fluctuations of a modulated signal transmitted and received by one of the two power transmitting coils are observed by the other power transmitting coil, or when the observed level is greater than a predetermined value and affects the demodulation performance when a 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., a coupling coefficient that 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 if the induced level is equal to or less than a predetermined value, it may be determined that there is "no interference," and otherwise it may be determined that there is "interference."

[0056] The above-described 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. To prevent interference, for example, 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 shifted. Below, a method for performing object detection by outputting A-Ping using multiple power transmitting coils to prevent interference will be described. According to this method, A-Pings are output simultaneously from power transmitting coils in different positions, allowing for efficient object detection in a short time.

[0057] The degree of interference differs depending on the relative positions of the two power transmitting coils. In this embodiment, it is assumed that 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 power transmitting coil 400 and power transmitting coil 411 shown in FIG. 4(d) is D. In this case, power transmitting coil 400 and power transmitting coil 411 can be said to be power transmitting coils that do not interfere with each other. Furthermore, power transmitting coil 400 and power transmitting coil 410, and power transmitting coil 401 and 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 power transmitting coils at which no interference occurs. For example, a voltage or current is applied to a predetermined power transmitting coil among multiple power transmitting coils, and fluctuations in the voltage or current at the other power transmitting coils are measured. This measurement identifies a power transmitting coil that does not generate fluctuations or whose fluctuations are below a predetermined amount, and measures the distance from the predetermined power transmitting coil. This allows the distance D at which no interference occurs to be obtained. Alternatively, for example, the amplitude or frequency of the voltage or current applied to a predetermined power transmitting coil among multiple power transmitting coils is varied, and fluctuations in the amplitude or frequency of the voltage or current at the other power transmitting coils are measured. This measurement identifies a power transmitting coil that does not generate fluctuations or whose fluctuations are below a predetermined amount, and measures the distance from the predetermined power transmitting coil. This allows the distance D at which no interference occurs to 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 take a different value depending on the definition of the distance between the power transmitting coils. For example, the predetermined distance D may take 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 the distance between the power transmitting coils is the shortest distance between the power transmitting coils. Furthermore, the power transmitting coils may be arranged not only on a two-dimensional plane as shown 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 conditions, 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 connect 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 that are located at a predetermined distance D or more apart 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 will cause interference when power is transmitted to a certain power transmitting coil. In other words, it is possible to identify in advance other power transmitting coils that will interfere with power transmission to a certain power transmitting coil, or other power transmitting coils that will not interfere, and store the identification results. Based on this identification result, when selecting a certain power transmitting coil, select a power transmitting coil that has been identified as not interfering. Operation can then be performed 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 powered 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 changes depending on whether the power transmitting device 100 is already performing a power transmitting process for charging (S602). Here, since the power transmitting device 100 has just been powered 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 the 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 positioned so as not to cause interference to the first power transmitting circuit 203 and the second power transmitting circuit 205, respectively, in accordance with the combination determined by the control unit 201 (S603).

[0065] The power transmitting device 100 waits for a 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 to the coil 400 and the second power transmitting circuit 205 to the coil 411. The control unit 201 then performs an object detection process by simultaneously outputting A-Pings from the coils 400 and 411 (F701). Since the power transmitting coil 400 and the power transmitting coil 411 are positioned so as not to interfere with each other, no interference occurs between the power transmitting coils even if the first power transmitting circuit 203 and the second power transmitting circuit 205 are controlled to simultaneously transmit A-Pings. The timing and duration at which A-Pings are output from the two power transmitting coils may or may not be the same. It is sufficient that the periods during which A-Pings are output from 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-Pings are output from the multiple transmitting coils do not overlap.

[0066] If no power receiving device is detected here, 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, and performs an object detection process, until a power receiving device is detected.

[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. The power transmitting device 100 then 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 101 has been placed (Yes in S506), the first power transmitting circuit 203 performs a power transmission process 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 at a distance D or more from the power transmitting coil 400. Therefore, these coils are prohibited from use while the power transmitting coil 400 is in use (S607).

[0069] On the other hand, because 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. Because 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 from the coil group 210 other than the power transmitting coil that has been prohibited from use, 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] This will be explained in detail 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 (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, etc., executes the processing from S602 onwards again to detect and transmit power to a new power receiving device. 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 the power transmitting coils so that two power transmitting coils that are closer than a predetermined distance from each other do not simultaneously output A-Pings. According to this embodiment, even if the power transmitting coils are closely spaced, 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 location on the power transmitting device 100.

[0073] Although an example has been described in which power transmission for charging is performed using a power transmitting coil that detects an object (power receiving device), the present disclosure is not limited to this. To achieve efficient power transmission, power transmission for charging may be performed using a coil different from the power transmitting coil that detects the object (power receiving device). In this case, a power transmitting circuit different from the power transmitting circuit used for charging transmits A-Ping using a power transmitting coil that does not interfere with the power transmitting coil that transmits power for charging. In other words, a power transmitting coil that does not interfere with the power transmitting coil used for charging power transmission may be identified, and A-Ping may be transmitted using that power transmitting coil.

[0074] Furthermore, although the present embodiment has been described with reference to an example in which there are two power transmission circuits, the method described in the present embodiment can also be applied to cases in which there are three or more power transmission circuits. For example, if the power transmission device 100 has three power transmission circuits, including the first power transmission circuit 203, the second power transmission circuit 205, and a third power transmission circuit (not shown), the power transmission device 100 performs the following process. That is, when outputting a signal for object detection using each power transmission circuit, the control unit 201 of the power transmission device 100 uses three power transmission coils 209 connected to each power transmission circuit that are located at positions that are at least a predetermined distance D from each other. In the example of the power transmission coil group 210 shown in FIG. 4(c), for example, power transmission coils 400, 403, and 411 are selected as the three power transmission coils. Because these three power transmission coils are at least the distance D from each other, no interference occurs even if A-Pings are transmitted simultaneously. By selecting the power transmitting coils 209 to be connected to each power transmitting circuit in this way, 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 capacities. In the present embodiment, control when the power transmission capacities of the multiple power transmission circuits included in a power transmission device are different 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 capacities, the following problems may occur. For example, when a power receiving device is placed on the power transmission device, power transmission processing may be performed by a power transmission circuit that is not capable of transmitting sufficient power (has low power transmission capacity) to the power receiving device. This results in a problem of inefficient charging of the power receiving device. In this way, when transmitting power to a power receiving device using a power transmission device having power transmission circuits with different power transmission capacities, appropriate power transmission may not be performed.

[0076] In this embodiment, a method for supplying sufficient power to a power receiving device will be described by determining which power transmitting circuit to use for power transmission based on the power transmission capacity of the power transmitting circuit and the power receiving capacity of the power receiving device. In this embodiment, the same names and symbols are used for components similar to those in embodiment 1.

[0077] [Processing in power transmission equipment] The processing executed by the power transmitting device 100 will be described below with reference to FIGS. 9 and 10. The processing in FIG. 9(a) is the processing shown in FIG. 5 plus the switching processing 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 refers to 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, the power that corresponds to the maximum power in the WPC standard. The power transmitting device 100 executes switching processing based on the maximum power that it can transmit (power transmission capability) in order to charge the power receiving device and the acquired power receiving capability of the power receiving device 101 (F826). This switching processing may be executed before transitioning to the Power Transfer phase.

[0078] FIG. 10 shows a processing flow of power transmission circuit switching processing of a power transmitting device according to this embodiment. The processing shown in FIG. 10 is performed in F826 of FIG. 9. Assume now that the power transmitting device 100 has detected the power receiving device 101 using the first power transmitting circuit 203 and acquired a Configuration packet from the power receiving device 101. First, the power transmitting device 100 determines whether another power transmitting circuit having a higher power transmission capacity than the first power transmitting circuit 203, which is performing control communication with the power receiving device, is available for power transmission (S901). That is, the power transmitting device 100 determines whether there is a power transmitting circuit having a higher power transmission capacity than the first power transmitting circuit 203 and which has not yet transmitted power to another power receiving device. Here, it is assumed that the second power transmitting circuit 205 has a higher power transmission capacity than the first power transmitting circuit 203 and is not transmitting power. Note that when the power transmitting circuit performing control communication with the power receiving device is the second power transmitting circuit, there is no power transmitting circuit having a higher power transmission capacity than the second power transmitting circuit, and therefore the determination in S901 is No.

[0079] If the corresponding power transmission circuit is usable 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 Maximum 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] The case where there is no other power transmission circuit that meets the requirement 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 this embodiment will be described using a specific example. A method for supplying sufficient power to the power receiving device will be described for a case in which a first power receiving device 101a with a power receiving capacity of 60 W is placed on a power transmitting device 100 having a first power transmitting circuit with a power transmitting capacity of 15 W and a second power transmitting circuit with a power transmitting capacity of 60 W. The power transmitting device 100 sends an 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 determine in F505 that the power receiving capacity of the first power receiving device 101a is 60 W based on the value of the maximum received power included in the Configuration packet. Because the power transmitting device 100 transmits power via the first power transmitting circuit 203, it cannot supply sufficient power to the first power receiving device 101a. Therefore, the first power transmission device 100 performs power transmission circuit switching processing F826. In S901 of FIG. 10, the power transmission device 100 determines that a second power transmission circuit 205 with a power transmission capacity of 60 W is present, and therefore proceeds to processing S902. Subsequently, in S902, the power transmission device 100 determines that 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, and therefore proceeds to processing S903. In S903, the power transmission device 100 stops power transmission and switches the power transmission circuit that transmits power to the first power receiving device 101a to the second power transmission circuit 205. The power transmission device 100 performs processing from F507 onwards using the second power transmission circuit 205. Furthermore, because the first power transmission circuit 203 is not communicating with any power receiving devices, it transmits an 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 power transmission circuit.

[0082] 9B is a sequence diagram for explaining the operation of each power transmission circuit and the processing when a second power receiving device is placed. In the processing 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 that the power receiving device 101a has been placed (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 power transmission circuit switching processing shown in FIG. 10 (F826). As a result, the subsequent processing is performed by the second power transmission circuit 205.

[0083] 9A and transmits power to the first power receiving device 101a for charging (F827). Note that because 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 an A-Ping 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 a 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 processing in FIG. 9B will be described. Assume that a first power receiving device 101a with a power receiving capacity of 5W is placed on a power transmitting device 100 having a first power transmitting circuit with a power transmitting capacity of 15W and a second power transmitting circuit with 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. In F541, the first power transmitting device 100 sends an A-Ping via the first power transmitting circuit 203. When the first power receiving device 101a is placed, the first power transmitting device 100 acquires a Configuration packet from the first power receiving device 101a in F506, and is able to know that the power receiving capacity of the first power receiving device 101a is 5W. The first power transmitting device 100 performs the power transmitting circuit switching processing shown in FIG. 10 (F826). In S901, the power transmitting device is performing control communication with the power transmitting circuit. Since there is no other power transmitting circuit with a higher power transmitting capacity, the processing proceeds to S906. In S906, the power transmitting device 100 proceeds to S904 because another power transmitting circuit (second power transmitting circuit 205) with a lower power transmitting capacity than the power transmitting circuit with which control communication is being performed is available. Subsequently, in S904, the power transmitting device 100 proceeds to S905 because the power transmitting capacity of the other power transmitting circuit is equal to or greater than the power receiving capacity 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 sends an A-Ping via the first power transmission circuit 203. Thereafter, when the second power reception device 101b, which has a power receiving capacity of 15 W, is placed, the first power transmission device 100 sends a D-Ping to the second power reception device 101b (F829) and starts power transmission for charging (F830). Here, 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, because the power transmission device 100 knows 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-described process enables the power transmitting device 100 to supply sufficient power to the newly placed second power receiving device 101b. In this manner, a power transmitting device having a plurality of power transmitting circuits with different capacities can supply sufficient power by switching the power transmitting circuit that transmits power to the power receiving device based on the power receiving capability of the power receiving device and the power transmitting capability of the power transmitting circuit. In this embodiment, the power transmitting circuit is switched using the selection unit 208 so as not to stop power transmission, 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 a power transmitting device that cannot instantaneously switch power transmitting circuits to supply sufficient power to the power receiving device. Furthermore, 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 this is not limiting. The power transmitting device 100 may be configured to determine whether to switch the power transmitting circuit based on, for example, information about the GP acquired from the power receiving device 101 in the negotiation phase. The power transmitting device 100 compares the power that the power transmitting circuit can transmit with the power indicated 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 is unable to transmit power equivalent to the GP, the power transmitting device 100 switches to a power transmitting circuit with a higher power transmission capacity (Yes in S902 of FIG. 10, S903). Furthermore, if the power that another power transmitting circuit with a lower power transmission capacity can transmit is greater than the GP, the power transmitting circuit 100 switches to the other power transmitting circuit with a lower power transmission capacity (Yes in S904 of FIG. 10, S905). In this case, in the sequence of FIG. 9A, the power transmitting device 100 performs the switching process after acquiring the 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, if the power transmitting device 100 cannot transmit power corresponding to the GP determined by the renegotiation, it switches to a power transmitting circuit with a higher power transmission capacity. As a result, when the power transmitting circuit currently transmitting power cannot supply sufficient power, it becomes possible to supply sufficient power by switching the power transmitting circuit. Furthermore, when the power that can be transmitted by another power transmitting circuit with 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 transmitting circuit with a lower power transmission capacity. As a result, when a new power receiving device is installed, power can be transmitted to the new power receiving device using a power transmitting circuit with a higher power transmission capacity. As a result, the power transmitting device 100 can effectively utilize the power transmission capacity of the power transmitting circuit.

[0089] Furthermore, 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. Furthermore, the power transmission device 100 may switch the power transmission circuit based on information acquired in renegotiation.

[0090] Furthermore, the power receiving capability of the power receiving device is described as the maximum received power 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 WPC version, and the power transmitting circuit switching process may be performed. For example, the power transmitting device may identify that the power receiving device is a device that has transmitted power in the past based on the identification number of the power receiving device, and determine the power transmitting circuit to be used based on the past power transmission record. Also, for example, the power transmitting device may identify the type of the power receiving device and switch the power transmitting device depending on whether the power receiving device is a smartphone or a PC. Note that the types of power receiving devices described here are merely examples, and other types of power receiving devices may also be used. Furthermore, the switching process may be performed based on any number of pieces of information such as those described above 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 capacities. For example, the power transmission device may be one in which multiple power transmission circuits with different power transmission capacities can be connected 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 capacities. For example, even in a power transmission device having two or more power transmission circuits, power can be transmitted using an appropriate power transmission circuit 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 multiple 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 radiation noise increases and adversely affects surrounding devices (existing power transmission). Furthermore, because A-Pings are continuously transmitted from multiple power transmitting coils, the power transmitting device consumes unnecessary power while no other power receiving device is placed on the device. As such, 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] To solve this problem, the power transmitting device in this embodiment determines whether power is being transmitted to the power receiving device, and if power is being transmitted, stops transmitting A-Pings from the power transmitting coils and detects an object based on changes in physical quantities (physical parameters) in the object detection coils. Then, only when an object is detected by the object detection coils, does the power transmitting device transmit A-Pings. This suppresses unnecessary A-Ping transmissions, thereby reducing the adverse effects on existing power transmissions due to the generation of radiation noise, and enabling detection of the placement of a new power receiving device. Furthermore, unnecessary power consumption can be suppressed.

[0094] Hereinafter, the embodiments will be described in detail with reference to the accompanying drawings. Note that the same names and symbols are used for the same components as those in the above-described embodiments.

[0095] [Device configuration] FIG. 11 is a diagram illustrating the configuration of the power transmitting device 200 according to 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. An example configuration of the object detection coil is shown in FIG. 11(b). The object detection coil 211 is, for example, a coil configured to surround the transmission coil group 210 shown in FIG. 4(c). In other words, the area in which the object detection coil 211 can transmit power encompasses the area in which the power transmitting coil group 210 can transmit power. Note that 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 steps may be implemented by hardware. In this case, the hardware may be implemented by, for example, using a predetermined compiler to automatically generate a dedicated circuit using a gate array circuit such as an FPGA from a program for implementing each processing step. This process may be executed when the power transmitting device 200 is turned on, when a user of the power transmitting device 200 inputs an instruction to start a contactless charging application, or when the power transmitting device 200 is connected to a commercial power source and receives power. This process may also be started by some other trigger. The power transmitting device 200 executes this process using multiple power transmitting coils 209. The power transmitting device 200 may sequentially select one of the power transmitting coils 209 and execute the process, or may execute the process in parallel using multiple 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 (placing 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 to this. It may also be assumed that one or more power receiving devices exist 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 an 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, power transmitting device 200 calculates the amount of change in physical quantity in object detection coil 211, and the process proceeds to S1004. Here, the amount of change in physical quantity may be calculated by measuring the current value of object detection coil 211 that occurs due to a change in the state of object detection coil 211 and determining the difference from the previously measured value, but is not limited to this. For example, the amount of change in physical quantity may be the difference in voltage value applied to object detection coil 211, the amount of shift in resonant frequency of object detection coil 211, or the difference in characteristic impedance of 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 current, voltage, resonant frequency, etc. in the coil change because the change in the state inside object detection coil 211 changes the magnetic flux inside the coil or the characteristic impedance.

[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. The power transmitting device 200 sequentially transmits A-Pings 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 an A-Ping from each of the multiple power transmitting coils 209 per second. Therefore, in this case, the power transmitting device 200 sequentially transmits A-Pings 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 a predetermined response to the D-Ping is received, the power transmitting device 200 determines that the detected object is a power receiving device and that the power receiving device has been placed on the target power transmitting coil, and stores this information (S1006). When the power transmitting device 200 detects that the power receiving device has been 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 with 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 receiving device 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), and the power transmitting device 200 makes adjustments to efficiently transmit power.

[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 if the power supply to the power transmitting device 200 is stopped, the power transmitting device 100 ends the process.

[0104] As described above, when the power transmitting device of this embodiment is transmitting power to the power receiving device and has not detected the placement of an object, the power transmitting device does not start the process for object detection in the power transmitting coil, i.e., the process defined as the Selection phase of the WPC standard. This reduces the adverse effects of radiation noise on existing power transmission. Furthermore, 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 simplicity of description, it is assumed that 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, it is assumed that a power receiving device is not placed on the power transmitting device 200, and that 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. It is also 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. It is also assumed that the threshold value may be set by an input operation by the user. In the following description, the expression "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 a 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. Since the difference between the physical quantity and the object detection signal becomes equal to or greater than a threshold, 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. Thereafter, 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 devices, and therefore waits for an object to be placed on the power transmitting device 200 by sequentially transmitting A-Pings from the power transmitting coils 209a to 209c (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 (near 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, through communication in the I&C phase, the power transmitting device 200 acquires identification information and capability information from the first power receiving device 300 (S1007, F1107). Next, the power transmitting device 200 and the first power receiving device 300 perform 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 perform communication in the Calibration phase to derive calibration data (S1009, F1109). Thereafter, the power transmitting device 200 performs power transmission to the first power receiving device 101a (S1010, F1110).

[0109] Next, because the power transmitting device is transmitting power to the first power receiving device 300, it stops transmitting A-Ping from the power transmitting coil 209, transmits an object detection signal from the object detection coil 211, and calculates the amount of change in the physical quantity (S1001 to 1003, F1111 to 1113). At this time, a new power receiving device is not placed, and the calculated amount of change in the physical quantity is less than the threshold, so it is determined that a new object has not been detected. Furthermore, the power transmitting device 200 repeatedly transmits the object detection signal and calculates the amount of change in the physical quantity at predetermined intervals (No in S1004, S1001 to 1003, F1112 to 1113). Thereafter, 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 amount of change in the physical quantity is equal to or greater than the threshold. The power transmitting device 200 resumes transmission of A-Pings from the power transmitting coils 209b to 209c, excluding the power transmitting coil 209a that is currently transmitting power (Yes in S1004, F1114 to F1116). 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). The subsequent processing from F1119 to F1124 is the same as F1105 to F1110, and therefore 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 again stops object detection by A-Ping from the power transmitting coil 209 because it is currently transmitting power to the first power receiving device 101a and the second power receiving device 101b. Furthermore, power transmitting device 200 transmits an object detection signal from object detection coil 211 and calculates the amount of change in the physical quantity (Yes in S1001, S1002 to S1003, F1125 to S1127).

[0110] According to the above-described operation, after starting power transmission to the power receiving device, the power transmitting device 200 stops transmitting A-Pings from each power transmitting coil 209 and starts object detection using the object detection coils. Then, based on the detection of an object using the object detection coils, the power transmitting device 200 detects the power receiving device by transmitting an object detection signal (A-Ping) from each power transmitting coil 209. At this time, the object detection coils are configured to encompass 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 coils in a predetermined time period is less than the total number of times that A-Pings are transmitted from each power transmitting coil in the same predetermined time period. This makes it possible to relatively suppress the generation of radiation noise and the like, thereby enabling the placement of a new power receiving device to be detected while mitigating adverse effects on power transmission to existing power receiving devices. Furthermore, transmitting A-Pings only from the object detection coils consumes less power than transmitting A-Pings 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-Pings from each power transmitting coil and transmits object detection signals from the object detection coils to calculate changes in physical quantities. However, it is not necessary to transmit object detection signals. In this case, the power transmitting device can calculate changes in physical quantities caused by changes in the state of the object detection coils due to the power transmitted from the power transmitting coils during power transmission. This can further reduce the generation of radiated noise and unnecessary power consumption compared to when object detection signals are transmitted.

[0112] In the above-described embodiment, the power transmitting device transmits A-Pings sequentially from each power transmitting coil when not transmitting power to a power receiving device, but this is not limiting. That is, even when not transmitting power to a power receiving device (when no power receiving device is mounted), 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 reduce unnecessary power consumption even when not transmitting power to a power receiving device.

[0113] Furthermore, in the above-described embodiment, the power transmitting device has an object detection coil configured to encompass the entire power transmission range of the power transmitting coil group, but this is not limited to this. 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 an A-Ping from the determined specific power transmitting coil 209. This can suppress the generation of radiated noise and unnecessary power consumption compared to a case where A-Pings are transmitted sequentially from multiple power transmitting coils. Furthermore, in this configuration, the power transmitting device 200 does not need to 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 encompass the entire power transmission range of the power transmitting coil group. However, this is not limiting. The power transmitting device 200 may have multiple object detection coils. For example, a case will be described in which multiple object detection coils are arranged, each encompassing an area where each power transmitting circuit can transmit power (e.g., dedicated area 416 and dedicated area 417 in FIG. 4 ). In this case, the power transmitting device 200 may start object detection only with the object detection coils that encompass the area where the power transmitting circuit that is not currently transmitting power can transmit power. When an object is detected, the power transmitting device 200 may transmit A-Pings only with the power transmitting coils in the area encompassed by the object detection coils. In this way, transmitting A-Pings only in the area where it is determined that an object has been detected reduces the number of signal transmissions compared to sequentially transmitting A-Pings throughout the entire power transmission range. This makes it possible to relatively suppress the generation of radiated noise and the like, thereby detecting the placement of a new power receiving device while further reducing adverse effects on power transmission to existing power receiving devices.

[0115] (Embodiment 4) As described in the first embodiment above, when power is transmitted simultaneously from multiple 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 may interfere with each other. In the first embodiment, a method for suppressing interference by transmitting power using power transmitting coils that are positioned so as not to 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 when one power transmitting coil transmits A-Ping for object detection while another 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-described embodiments.

[0116] [Processing in power transmission equipment] Fig. 15 is a flowchart showing processing 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, processing starts when the power transmitting device is turned on (S1301). The power transmitting device 100 selects, from the power transmitting coil group 210 via the control unit 201, 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, and connects each power transmitting circuit to each power transmitting coil (S1302). Here, the power transmitting device 100 selects power transmitting coils that do 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 embodiment 1.

[0118] Next, the power transmitting device 100 determines whether the power transmitting circuit is transmitting power (S1303). Here, 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 this A-Ping is smaller than the transmitted 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). Here, if the power transmitting device 100 detects by A-Ping that an object is placed on the power transmitting device, the power transmitting device 100 goes through the above-mentioned Selection phase, Ping phase, and I&C phase to detect the placement of the power receiving device.

[0120] Next, the power transmitting device performs a power transmission process for the power receiving device detected in S1305 through a plurality of phases defined in the WPC standard described above, and starts power transmission (S1306).

[0121] Next, the power transmitting device 100 determines whether all of the power transmitting circuits of the power transmitting device are in use (S1307). If all of the power transmitting circuits are in use, the power transmitting device 100 ends control for power transmission. Although not shown in FIG. 15 , the power transmitting device 100 continues transmitting power for charging until it receives a power transmission stop command (EPT) from the power receiving device, for example, when the battery of the power receiving device becomes fully charged. Furthermore, after the power transmitting device 100 ends the power transmission for charging, it executes the processing from S1303 onwards again to detect a new power receiving device. The processing 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 processing 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, if power transmission from the first power transmitting coil and transmission of an A-Ping, which is an object detection signal, from the second power transmitting coil are performed simultaneously, the A-Ping, which has low power, may be disturbed by the high-power transmission power. As a result, the A-Ping transmitted from the second power transmitting coil may not function correctly as a detection signal, which may lead to erroneous object detection. The power transmitting device 100 of this embodiment performs the following processing to mitigate the problem of A-Ping being disturbed.

[0123] If 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 being used for power transmission. Here, it is assumed that the second power transmitting coil is not being used for power transmission, and that the 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 the 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 the period when power transmission from the first power transmitting circuit 203 that is transmitting 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 to ensure that the A-Ping output by the second power transmitting circuit 205 for object detection does not overlap with power transmission performed by the first power transmitting circuit 203. In other words, 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 allows the detection signal to be 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 power transmission for charging by the power transmitting device 100 and the timing of transmitting a detection signal will be described using FIG. 16 . In the above-described embodiment, the power transmitting device 100 performs power transmission processing using two power transmitting circuits and two power transmitting coils connected to each of the power transmitting circuits. However, this is not limited to this, and the present embodiment can also be applied to power transmission processing using more power transmitting circuits and power transmitting coils. Now, it is assumed that the first power transmitting circuit 203 is transmitting power for charging using the first power transmitting coil. Furthermore, it is assumed that the second power transmitting circuit 205 is connected to the second power transmitting coil, the third power transmitting coil, and the fourth power transmitting coil in sequence, and transmits an A-Ping from each of the power transmitting coils.

[0125] 16, the first power transmitting coil is used for power transmission and transmits power to a power receiving device. Then, after a predetermined time has elapsed, the first power transmitting circuit 203 suspends (momentarily interrupts) power transmission from the first power transmitting coil for a predetermined period at a first timing (S1308). Then, during the period when power transmission is suspended, 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 suspends 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 suspends (momentarily interrupts) power transmission from the first power transmitting coil for a predetermined period at a second timing (S1308). Then, during the period when power transmission is stopped, the second power transmitting circuit 205 transmits an A-Ping using the third power transmitting coil (S1309). Then, after the first power transmitting circuit 203 has stopped power transmission for a predetermined period of time, it resumes power transmission (S1310). If the second power transmitting circuit 205 has not detected a power receiving device (S1305), after a predetermined time has elapsed, the first power transmitting circuit 203 suspends (momentarily interrupts) power transmission from the first power transmitting coil at a third timing for a predetermined period of time (S1308). Then, during the period when power transmission is suspended, the second power transmitting circuit 205 transmits an A-Ping using the third power transmitting coil (S1309). Then, after the first power transmitting circuit 203 has suspended power transmission for a predetermined period of time, 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 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 power transmission for charging. The timing at which the power transmitting device 100 stops power transmission for charging may be preset in the power transmitting device 100. The predetermined period during which the power transmitting device 100 stops 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 there is any problem with momentary interruption of power transmission based on, for example, the version of the power receiving device that is transmitting power for charging. Furthermore, the power transmitting device 100 may transmit information indicating the timing at which power transmission will be momentarily interrupted to the power receiving device or obtain the information from the power receiving device, for example, during the negotiation phase, so that the timing at which power transmission will be momentarily interrupted is shared between the power transmitting device and the power receiving device.

[0128] Furthermore, the configuration of the power transmitting circuits and power transmitting coils is not limited to the above. For example, a configuration may be adopted in which four power transmitting circuits are used, with the first power transmitting coil connected to the first power transmitting circuit, the second power transmitting coil connected to the second power transmitting circuit, the third power transmitting coil connected to the third power transmitting circuit, and the fourth power transmitting coil connected to the fourth power transmitting circuit. Furthermore, the number of power transmitting coils may be any number.

[0129] In the above-described embodiment, the power transmitting device 100 transmits the detection signal in order starting from the power transmitting coil not being used for power transmission. However, the A-Ping, which is the detection signal, may be transmitted simultaneously from multiple coils. That is, the power transmitting device may temporarily stop (flash interruption) power transmission from the first power transmitting coil, and transmit A-Pings simultaneously from the second power transmitting coil, the third power transmitting coil, and the fourth power transmitting coil during the power transmission stop period. Alternatively, the first power transmitting circuit may be connectable 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-described configuration, the power transmitting device 100 may temporarily stop (flash interruption) power transmission from the first power transmitting coil, connect the first power transmitting circuit to the second power transmitting coil, and transmit A-Pings 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 also be used to detect a foreign object (object) other than the power receiving device. If a foreign object, such as a conductor, is present on the power transmitting device, the foreign object may consume power and generate heat when the power transmitting device transmits power. Therefore, the power transmitting device 100 may detect the presence of an object using the A-Ping transmitted in S1304 or S1309, and may stop power transmission if it determines 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 Ping phase, Selection phase, Ping phase, Identification and Configuration phase, and Negotiation phase described above. As a result, the power transmitting device shown in FIG. 14 can periodically check whether a foreign object is present near each power transmitting coil by transmitting a detection signal in sequence from the power transmitting coils not used for power transmission. This allows the power transmitting device to 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, a configuration has been described in which power can be transmitted to a power receiving device simultaneously from both the first power transmitting circuit and the second power transmitting circuit. However, a configuration in which power is transmitted from only one of the power transmitting circuits without simultaneously transmitting power from each power transmitting circuit is also possible. That is, when the first power transmitting coil detects the presence of a first power receiving device and the second power transmitting coil detects the presence of a second power receiving device near the first power transmitting coil (S1305), one of the power receiving devices is selected after S1305 based on a predetermined condition. Here, the predetermined condition for selecting a power receiving device may be, for example, based on a priority (priority) of the power receiving device to be the power receiving device. The priority is information used by the power transmitting device to communicate with the first power receiving device and the second power receiving device and determine the priority. The reason why the power transmitting device selects one of the power receiving devices as the power receiving device 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 to be 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 may cause communication errors between the power transmission device and the power receiving device. Furthermore, when power is transmitted from multiple power transmission circuits, the generated noise may exceed a reference value. Therefore, power interference is suppressed by performing "power receiving device selection" and transmitting power to the selected power receiving device.

[0133] Furthermore, even when power transmission from multiple power transmission circuits exceeds the power supply capacity of the power transmission device hardware, appropriate power transmission can be performed by "selecting a power receiving device." 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 when a new power receiving device with a high priority has been installed, it becomes 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. The problem to be solved in this embodiment will be described using 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 in embodiment 1, and the first power transmitting circuit 203 and the second power transmitting circuit 205 of the power transmitting device 100 are each 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 devices are 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, from the state of FIG. 17(a), the second power receiving device 101b is placed in the dedicated area 416 of the first power transmitting circuit 203. Here, it is assumed that the first power transmitting circuit 203 is transmitting power to the first power receiving device 101a placed in the shared area 415 in FIG. 17(a). In this case, if 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 first power transmitting circuit 203 can simultaneously transmit power to a maximum of one power receiving device. 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 processing performed by the power transmitting device in this embodiment will be described with reference to FIGS. 17 and 18 . This processing may be initiated when the power transmitting circuit 203 is powered on and activated, for example, by receiving power from the power supply unit 202. This processing may be implemented by the control unit 201 executing a program stored in the memory 207. However, this is not limited to this, and this processing may also be executed when, for example, a user activates the power transmission function by pressing a predetermined button. At least a portion of the processing shown in FIG. 18 may be implemented by hardware. When at least a portion of the processing is implemented by hardware, for example, a dedicated circuit automatically generated on an FPGA using a predetermined compiler from a program for implementing the processing steps may be used. Similarly to an FPGA, the hardware for executing the predetermined processing steps may be implemented by a gate array circuit.

[0138] 18, the process starts when the power transmission device 100 is turned 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] The power transmitting device 100 transmits a D-Ping and, upon receiving a Signal Strength packet, 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. The power transmitting device 100 then compares the number of power receiving devices to which it 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 is transmitting D-Ping power to the first power receiving device 101a, but there are no power receiving devices 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. Because the upper limit is greater than the number of power receiving devices (Yes in S1602), the power transmitting device 100 proceeds 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 power receiving devices to which power can be transmitted 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 representing the number of power receiving devices to which the first power transmitting circuit 203 can transmit power in the shared area 415. Currently, there are no power receiving devices currently transmitting power in the shared area 415, so the number of power receiving devices is 0. Also, the upper limit of power receiving devices to which the first power transmitting circuit 203 can transmit power in the shared area 415 is 1. Because 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, which detected the first power receiving device 101a, will transmit power to the first power receiving device 101a (S1607), and ends the process. Now that the power transmission circuit that transmits 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, it may detect the second power receiving device 101b using the object detection coil described in the third embodiment. Furthermore, as described in the fourth embodiment, the power transmitting device 100 may detect the second power receiving device 101b while the first power transmitting circuit is momentarily interrupting 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). Because the first power transmitting circuit 203 is transmitting power to the first power receiving device 101a, the number of power receiving devices is 1. Because 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) received the Signal Strength Packet.

[0142] Since the first power transmitting circuit 203 is currently transmitting power to the first power receiving device 101a in the shared area 415 (Yes in S1603), the power transmitting device 100 selects another power transmitting circuit that can transmit power in the shared area 415 (S1604). In this case, since the second power transmitting circuit 205 can transmit power in the shared area 415, the power transmitting device 100 selects the second power transmitting circuit 205 (S1604) and compares the number of power receiving devices to which the second power transmitting 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 transmitting circuit 205 is not transmitting power to any power receiving devices at this point, the upper limit (= 1) is greater than the number of power receiving devices (= 0) (Yes in S1605). Next, the power transmitting 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 power transmission from the first power transmitting circuit 203 currently transmitting power in the shared area 415 (S1609). Furthermore, 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 point, the first power transmitting circuit 203 is in a state where it is not transmitting power to any power receiving device. The power transmitting device 100 uses the first power transmitting circuit 203 to detect the second power receiving device 101b placed in the dedicated area 416 (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. Since the power transmitting device 100 has already detected the second power receiving device 101b, this detection process may be omitted. The power transmitting apparatus 100 compares the number of power receiving apparatuses currently transmitting power (=0) with the upper limit (=0) of the number of power receiving apparatuses to which power can be transmitted in the dedicated area 416 (S1611), and transmits power to the second power receiving apparatus 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-described control, it becomes possible to efficiently transmit power to a plurality of power receiving devices using a plurality of power transmitting circuits.

[0145] Next, another example of power transmission control will be described. Here, it is assumed that, in FIG. 17(b), the second power receiving device 101b is first placed in the dedicated area 416 of the first power transmitting circuit 203, 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. Subsequently, 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 using 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, and therefore 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 apparatus 101a, the result in S1602 becomes Yes, and therefore the second power transmitting circuit 205 transmits power to the first power receiving apparatus 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 will transmit power to the third power receiving device (S1608). Note that when detecting the third power receiving device, the power transmitting device 100 may also detect the second power receiving device 101b using the object detection coil described in the third embodiment. Furthermore, as described in the fourth embodiment, the power transmitting device 100 may momentarily interrupt the power transmission that the first power transmitting circuit 203 was performing in the dedicated area 416 and the second power transmitting circuit 205 was performing in the shared area 416, and operate based on the flow of FIG. 15. Specifically, the first power transmitting circuit 203 periodically transmits A-Pings during the momentary power outage 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-Pings during the momentary power outage 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 using the method described in the third or fourth embodiment. In this case, when the second power receiving device 101b is placed, power cannot be transmitted to any more power receiving devices in the dedicated area 416 (No in S1610), so the power transmitting device 100 determines that none of the power transmitting circuits will transmit power to the detected second power receiving device 101b (S1608).

[0149] [System-wide processing] 17(a), (b), and 19, the processing of the entire system will be described. The power transmitting device 100 transmits an A-Ping using the first power transmitting circuit 203 and the second power transmitting circuit 205 (F1701), and performs a power receiving device detection process. Here, it is assumed that the first power receiving device 101a is placed in the shared area 415 and is detected by the A-Ping transmitted by the first power transmitting circuit 203. The first power transmitting circuit 203 transmits a 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 also placed in the dedicated area 416 of the first power transmitting circuit 203 and is 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. Because 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). Furthermore, the power transmitting device 100 stops power transmission to the first power receiving device 101a by the first power transmitting circuit 203 (S1609, F1704). Note that although Fig. 19 illustrates the case where a D-Ping is transmitted at F1711, a configuration in which power transmission is stopped at F1704 without transmitting a D-Ping may also be adopted.

[0150] The second power transmitting circuit 205 transmits an A-Ping (S1705) and a D-Ping (F1706) to the first power receiving apparatus 101a (F1707). The first power transmitting circuit 203 transmits an A-Ping (S1708) and a D-Ping (F1709) 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 the power receiving device is placed in. This makes it possible to simultaneously transmit power to multiple power receiving devices even when the power receiving devices are placed as shown in Fig. 17(b).

[0152] According to the above-described 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 receiving device is placed. However, the present invention is not limited to this. The power transmitting device 100 may also determine the power transmitting circuit to transmit power to the power receiving device based on whether 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 one, 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 (in the Selection phase) or D-Ping (in the Negotiation phase or Power Transfer phase). In the processes 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, in this embodiment, when the power transmitting device 100 receives a Signal Strength Packet in response to the transmitted D-Ping, it determines that it has detected the first power receiving device 101a, but it may also determine that an object is present nearby using an A-Ping.

[0154] As shown in FIG. 15(d), when the number of power receiving devices placed in the same area exceeds the upper limit of the power transmission capacity of the power transmission circuit or the upper limit of the power receiving devices that can transmit power in the same area, the following processing may be performed. For example, the power transmission device 100 may use a communication unit to transmit a message regarding the “number of power receiving devices” to the second power receiving device 101b to which the power transmission device 100 was placed later. Specifically, the message may indicate that “the power transmission device or the power transmission circuit has exceeded the upper limit of the number of power receiving devices that can simultaneously transmit power” or “the power transmission device or the power transmission circuit has exceeded the upper limit of the number of power receiving devices that can transmit power in the same area.” Alternatively, the message may simply be a message stating “many (much)” or “too much.” Furthermore, the message may be related to “the distance between the multiple power receiving devices.” Specifically, the message may be a message stating 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 why power transmission is not performed, and the power receiving device can recognize the reason why the power transmitting device 100 is not transmitting power.

[0155] Furthermore, the power receiving device that has received the message may display on its UI 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] Furthermore, the attributes of the charging device (power receiving device) may be detected using the Identification packet, Extended Identification packet, and Configuration packet specified 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 UI of the smartwatch may display the following messages: "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," "Please place the device farther away from the smartphone for wireless charging," etc.

[0157] If a user who has confirmed the above-described 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 transmission is not possible, and the notified power receiving device displays the device attributes on the UI in addition to the reason why power transmission is not possible 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 when, 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 devices are placed there.

[0158] 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) according to the flow of FIG. 5, that is, from the Selection phase. However, although the power transmitting circuit switches from the first power transmitting circuit 203 to the second power transmitting circuit 205, the power transmitting device 100 already knows the information about the first power receiving device 101a, so the second power transmitting circuit 205 may start from 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] Furthermore, if the first power receiving device 101a is a device with a display, such as a smartphone, and the second power receiving device 101b is a device without a display, such as wireless earphones, 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 may include, 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 about devices that cannot be charged. The power transmitting device may also display information about the wireless earphones on the display of the smartphone during charging. For example, a message may be displayed stating, "Place the wireless earphones in a different location from the smartphone to wirelessly charge them," or "The wireless earphones are too close to the smartphone to wirelessly charge them." Another message may be displayed stating, "Place the wireless earphones farther away from the smartphone to wirelessly charge them." This allows the user to check information about devices that do not have a display (such as wireless earphones).

[0160] Furthermore, the power transmitting device 100 may transmit a message to the second power receiving device 101b, which is placed later, indicating that the communication unit has exceeded the upper limit of power transmission capability or the upper limit of power transmission capability in the same area. If the power transmitting circuit has exceeded the upper limit of power transmission capability or the upper limit of power transmission capability in the same area, the power transmitting device may display the reason for not being able to transmit power 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 "To perform wireless charging, please stop wireless charging of other devices."

[0161] Furthermore, 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 common area 416 are connectable exclusively 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 common 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 different communication unit that does not comply with the WPC standard, and the communication unit may be a communication unit that complies with the Bluetooth Low Energy standard, the Wi-Fi standard, or the NFC standard.

[0163] In addition, in this embodiment, the explanation has been given using an example of a power transmitting device 100 that has 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 this is applicable to any number of power transmitting circuits and any number of shared areas 415 and dedicated areas.

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

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

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

Claims

1. a plurality of coils used to wirelessly transmit power to a power receiving device, the plurality of coils including a first coil and a second coil disposed at a position closer than a predetermined distance from the first coil; a detection means for detecting an object by outputting a signal for detecting the object from some of the plurality of coils; receiving means for receiving a Signal Strength packet after the detecting means detects an object; a power transmitting unit that transmits power wirelessly to a power receiving device using at least one of the plurality of coils based on the Signal Strength packet; a control means for controlling the second coil so that a signal for detecting an object is not output during wireless power transmission to the power receiving device via the first coil; and A power transmission device characterized in that, when there are multiple power receiving devices, the power transmission means wirelessly transmits power to a first power receiving device included in the multiple power receiving devices via a coil corresponding to the first power receiving device, and wirelessly transmits power to a second power receiving device included in the multiple power receiving devices via a coil corresponding to the second power receiving device.

2. The power transmission device according to claim 1, characterized in that the predetermined distance is a distance at which the voltage or current in the second coil does not fluctuate due to the voltage or current in the first coil when a signal for detecting an object is output from the first coil.

3. The power transmission device according to claim 1, characterized in that the predetermined distance is a distance at which the fluctuation in voltage or current in the second coil caused by the voltage or current in the first coil when a signal for detecting an object is output from the first coil is less than a predetermined value.

4. the plurality of coils further includes a third coil disposed at a position farther than the predetermined distance from the first coil; 2. The power transmitting device according to claim 1, wherein the detecting means simultaneously outputs signals for detecting an object from the first coil and the third coil.

5. The power transmission means has a first power transmission circuit that transmits power wirelessly through some of the plurality of coils, and a second power transmission circuit that transmits power wirelessly through some of the plurality of coils, the first power transmitting circuit and the second power transmitting circuit are capable of wirelessly transmitting power via the second coil; The power transmitting device according to claim 4, characterized in that the control means controls the second power transmitting circuit so that a signal for detecting an object is not output via the second coil while wireless power is being transmitted to the power receiving device via the first coil using the first power transmitting circuit.

6. The power transmission device described in Claim 5, characterized in that the detection means detects an object different from the power receiving device by using the second power transmission circuit to output a signal for detecting the object through the third coil.

7. The power transmission device according to claim 4, characterized in that, when the power transmission means is transmitting power to the power receiving device via the first coil, the detection means detects an object other than the power receiving device by outputting a signal for detecting the object from the third coil.

8. 2. The power transmitting device according to claim 1, wherein the signal is an Analog Ping defined by the Wireless Power Consortium (WPC) standard.

9. 2. The power transmitting device according to claim 1, wherein the simultaneous output means that periods in which signals for detecting an object are output from the two coils overlap at least partially.

10. A method for controlling a power transmitting device having a plurality of coils used to wirelessly transmit power to a power receiving device, the plurality of coils including a first coil and a second coil disposed at a position closer than a predetermined distance from the first coil, the method comprising: a detection step of detecting an object by outputting a signal for detecting the object from some of the plurality of coils; a receiving step of receiving a Signal Strength packet after detecting an object in the detecting step; a power transmitting step of wirelessly transmitting power to the power receiving device using at least one of the plurality of coils based on the Signal Strength packet; a control step of controlling the second coil so that a signal for detecting an object is not output during wireless power transmission to the power receiving device via the first coil; and A control method characterized in that, in the power transmission process, when there are multiple power receiving devices, power is transmitted wirelessly to a first power receiving device included in the multiple power receiving devices via a coil corresponding to the first power receiving device, and power is transmitted wirelessly to a second power receiving device included in the multiple power receiving devices via a coil corresponding to the second power receiving device.

11. A program for causing a computer to function as the power transmitting device according to any one of claims 1 to 9.

Images