Power receiving device and communication method

Abstract

To provide a power receiving device, program, and communication method that perform appropriate communication control in the power receiving device and a power transmitting device which can execute both in-band communication and out-band communication.SOLUTION: In a wireless power transmitting system, a first power receiving device RX1 that wirelessly receives power from a first power transmitting device TX1 communicates with the first power transmitting device at a second frequency when receiving a first packet from the first power transmitting device at a first frequency which indicates communication at the second frequency is possible, and transmits a packet indicating power transmission stop when receiving a packet indicating NAK from the first power transmitting device to a second packet transmitted at the first frequency.SELECTED DRAWING: Figure 6

Description

[Technical field]

[0001] The present invention relates to a control communication technique for wireless power transmission. [Background technology]

[0002] Technical development of wireless power transmission systems including a power transmitting device and a power receiving device has been widely conducted. Patent Document 1 describes a method of transmitting and receiving control signals in a power transmission system by using a frequency, coil, and antenna different from those used for power transmission and reception, that is, out-of-band communication.

[0003] In the standards (WPC standards) established by the Wireless Power Consortium (WPC), a standardization organization for wireless power transmission standards, power transmission and reception and the associated control communications are carried out by magnetic induction. Furthermore, power transmitting devices and power receiving devices that comply with the current WPC standards perform control communications using the same frequency as that used for power transmission and reception. This control communication is so-called in-band communication, which is carried out via the coil used for power transmission and reception. Note that the communication range in which in-band communication can be performed without errors is narrower than that of out-band communication. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2012-217224 A Summary of the Invention [Problem to be solved by the invention]

[0005] When considering a power transmitting device and a power receiving device capable of performing both in-band communication and out-band communication, appropriate communication control in such a power transmitting device and a power receiving device has not been considered.

[0006] The present invention has been made in view of the above-mentioned problems, and has an object to provide an appropriate communication control technique in a power receiving device and a power transmitting device capable of performing both in-band communication and out-band communication. [Means for solving the problem]

[0007] A power receiving device according to one embodiment of the present invention has a power receiving means for wirelessly receiving power from a power transmitting device and a communication means for communicating with the power transmitting device, wherein when the communication means receives a first packet from the power transmitting device at a first frequency indicating that communication at a second frequency is possible, the communication means communicates with the power transmitting device at the second frequency, and when the communication means receives a packet from the power transmitting device indicating a NAK in response to a second packet transmitted at the first frequency, the communication means transmits a packet indicating a stop of power transmission. Effect of the Invention

[0008] According to the present invention, communication control can be appropriately performed in a power receiving device and a power transmitting device capable of performing both in-band communication and out-band communication. [Brief description of the drawings]

[0009] [Figure 1] 1 is a block diagram showing a configuration example of a wireless power transmission system. [Diagram 2] 2 is a block diagram showing a configuration example of a power transmitting device. FIG. [Diagram 3] 2 is a block diagram showing a configuration example of a power receiving device; [Figure 4] 10 is a flowchart illustrating an example of a process flow of a power transmitting device. [Diagram 5] 10 is a flowchart illustrating an example of a process flow of a power receiving device. [Figure 6] FIG. 4 is an operation sequence diagram of the wireless power transmission system. [Figure 7] FIG. 13 is a diagram illustrating the structure of a Configuration Packet. [Figure 8]FIG. 13 is a diagram illustrating the structure of a Power Transmitter Capability Packet. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings. Note that the following embodiment is an example, and is not intended to limit the present invention to the described scope. Various changes and modifications can be made within the scope of the technical idea of ​​the present invention.

[0011] (System Configuration) FIG. 1 shows a wireless charging system according to the present embodiment. The wireless charging system includes a power transmitting device (first power transmitting device 101, second power transmitting device 102) and a power receiving device (first power receiving device 111 and second power receiving device 112). In the following, the first power transmitting device 101 and the first power receiving device 111 may be referred to as "TX1" and "RX1", respectively, and similarly, the second power transmitting device 102 and the second power receiving device 112 may be referred to as "TX2" and "RX2", respectively. It is assumed that these power transmitting devices and power receiving devices each have a communication function based on Bluetooth (registered trademark) Low Energy (BLE). It is also assumed that, as an example, there are other devices (first communication device 121 and second communication device 122) around the wireless charging system that have a communication function based on BLE but do not have a function of wireless power transmission. It is assumed that, in the following, a communication unit of BLE (a unit formed of an antenna, a communication circuit, etc.) may be referred to as "BLE".

[0012] Here, as shown in FIG. 1, TX1 and TX2 function as BLE Centrals, and RX1 and RX2 function as BLE Peripherals. The first communication device 121 functions as a Central, and the second communication device 122 functions as a Peripheral. Note that "Central" indicates a BLE control station, and "Peripheral" indicates a BLE terminal station. A BLE Central communicates with a BLE Peripheral, but does not communicate with other Centrals. A BLE Peripheral communicates with a BLE Central, but does not communicate with other Peripherals. That is, in BLE, communication between Centrals or between Peripherals is not performed. A Central can be in a connected state (BLE CONNECT_State) with multiple Peripherals, and can transmit and receive data to and from multiple Peripherals. On the other hand, a Peripheral can be in a connected state with only one Central, and does not communicate with multiple Centrals in parallel.

[0013] 1, it is assumed that RX1 is located within the power transmission and reception range from TX1, while RX2 is not located within the power transmission and reception range. Therefore, TX1 transmits wireless power only to RX1, and does not transmit power to RX2.

[0014] In this case, in order for TX1 to perform control communication by out-band communication using BLE and transmit power to RX1, the BLE (Central) of TX1 must be in a connected state with at least the BLE (Peripheral) of RX1. As described above, since the BLE Central can be in a connected state with multiple Peripherals at the same time, the BLE (Central) of TX1 may be in a connected state not only with RX1 but also with RX2 functioning as a Peripheral and the second communication device 122. Similarly, the BLE (Central) of TX2 may be in a connected state with RX1 and the second communication device 122 as long as it is in a connected state with the BLE (Peripheral) of RX2.

[0015] On the other hand, the BLE (Peripheral) of RX1 can be connected to only one Central. Therefore, in order to perform control communication for power transmission between TX1 and RX1 by BLE, the BLE (Peripheral) of RX1 needs to be in a connected state only with the BLE (Central) of TX1. This is because, when the BLE (Peripheral) of RX1 is in a connected state with other BLE (Central) such as Tx2 or the first communication device 121, it cannot perform control communication with the BLE (Central) of TX1. Similarly, in order to perform control communication for power transmission between TX2 and RX2 by BLE, the BLE (Peripheral) of RX2 must be in a connected state only with the BLE (Central) of TX2. Therefore, the BLE (Peripheral) of RX2 should not be in a connected state with other BLE (Central) such as Tx1 or the first communication device 121.

[0016] In this way, the control communication should be performed between the power transmitting device and the power receiving device (e.g., TX1 and RX1) where the power transmission and reception are performed. However, when the communication range of the outband communication is wider than the communication range of the inband communication, the power transmitting device and the power receiving device may establish a connection for outband communication with a device that is not a target of power transmission and reception. Establishing such a connection for outband communication with a device that is not a target of power transmission and reception is called a cross-connection. For example, in FIG. 1, a state in which RX1 and TX2 or the first communication device 121 are BLE connected is a cross-connection.

[0017] In FIG. 1, when TX1 uses BLE (outband communication) for control communication, it should not transmit power to charge the battery of RX1 or negotiate on power unless it is certain that a BLE connection is established with RX1 that is within the power transmission and reception range. This is because if TX1 establishes a BLE connection with RX2 or the second communication device 122 to perform control communication while setting RX1 as the power transmission target, the power transmission target (RX1) and the other device of the control communication (RX2 or the second communication device 122) may differ. In this case, TX1 cannot perform appropriate control communication with RX1. Similarly, when RX1 uses control communication by BLE (outband communication), it should not receive power to charge the battery from TX1 or negotiate on power unless it is certain that a BLE connection is established with TX1 that is within the power transmission and reception range. This is because, if RX1, with TX1 as the power receiving source, establishes a BLE connection with TX2 or the first communication device 121 to perform control communication, the power receiving source (TX1) and the other device of the control communication (TX2 or the first communication device 121) may be different. In this case, RX1 will not be able to perform appropriate control communication with TX1.

[0018] As described above, in the wireless power transmission system of FIG. 1, it is important that both the power transmitting device and the power receiving device obtain confirmation that control communication by BLE with a counterpart device within the power transmission / reception range is possible before transmitting / receiving power for charging the battery or negotiating the power. For this reason, in this embodiment, the power transmitting device and the power receiving device are allowed to establish a connection by BLE between the counterpart device of the wireless power transmission. Note that BLE is an example, and any wireless communication method that can be used for out-band communication in wireless power transmission can be used. In addition, in the following, the wireless power transmission to be performed is assumed to comply with the WPC standard, and the WPC standard here includes functions defined in version 1.2.2. Note that in this embodiment, the power transmitting device and the power receiving device will be described as complying with the WPC standard, but this is not limited to this, and other wireless power transmission standards may be used. In the following, a configuration example of the power transmitting device and the power receiving device and an example of the flow of the processing to be performed will be described.

[0019] (Device configuration) 2 is a block diagram showing a configuration example of a power transmitting device (for example, TX1 and TX2). The power transmitting device includes, for example, a control unit 201, a power supply unit 202, a power transmitting unit 203, a first communication unit 204, a power transmitting coil 205, a second communication unit 206, and a memory 207.

[0020] The control unit 201 controls the entire power transmitting device. The control unit 201 includes, for example, one or more processors such as a central processing unit (CPU) or a micro processing unit (MPU). The control unit 201 may include an application specific integrated circuit (ASIC) or a field programmable gate array (FPGA) configured to execute the processes described below.

[0021] The power supply unit 202 is a power source that supplies power when at least the control unit 201 and the power transmission unit 203 operate. 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. The power transmission unit 203 generates an AC voltage and an AC current in the power transmission coil 205 in order to transmit power to the power receiving device via the power transmission coil 205. The power transmission unit 203 converts the DC voltage supplied by the power supply unit 202 into an AC voltage using, for example, a switching circuit in a half-bridge or full-bridge configuration using FETs. In this case, the power transmission unit 203 includes a gate driver that controls ON / OFF of the FET.

[0022] The first communication unit 204 performs control communication for wireless power transmission based on the WPC standard with a communication unit of the power receiving device (first communication unit 303 shown in FIG. 3). In this embodiment, the communication performed by the first communication unit 204 is so-called in-band communication (communication by the first method) in which the AC voltage or current generated by the power transmitting unit 203 is modulated and communication target data is superimposed on the wireless power. In this embodiment, when the power transmitting device uses only in-band communication for control communication, it is assumed that the power transmitting device can supply enough power to output a maximum of 15 watts of power to a charging unit of the power receiving device that also uses in-band communication.

[0023] The second communication unit 206 performs control communication of wireless power transmission based on the WPC standard with a communication unit of the power receiving device (second communication unit 304 shown in FIG. 3). The second communication unit 206 performs so-called out-band communication (communication by a second method) using a frequency different from the frequency of the power transmitting unit 203 and an antenna (not shown) different from the power transmitting coil 205. In this embodiment, the second communication unit 206 is assumed to be compatible with BLE, but instead of this, a communication unit compatible with other wireless communication methods such as NFC or WiFi may be used.

[0024] In this embodiment, when out-band communication is used for control communication with a power receiving device, the power transmitting device can supply a larger amount of power to the power receiving device than when in-band communication is used. For example, when control communication is performed by out-band communication, the power transmitting device can supply power such that the power output to the charging unit of the power receiving device is a maximum of 100 watts. In in-band communication, minute changes in voltage and current are superimposed on the transmitted power for communication. In contrast, when the transmitted power increases, the noise generated from the power transmitting unit and the power receiving unit increases. For this reason, when in-band communication is used, the transmitted power is limited so that the communication unit of the in-band communication can detect minute changes in voltage and current for communication. On the other hand, when out-band communication is used, such restrictions are eliminated, and the amount of transmitted power can be increased.

[0025] The memory 207 stores the state of each element of the power transmitting device and the wireless power transmission system, as well as the overall state.

[0026] 2, the control unit 201, the power supply unit 202, the power transmission unit 203, the first communication unit 204, the memory 207, and the second communication unit 206 are each depicted as separate blocks, but two or more of these blocks may be integrated into one chip, etc. Also, one block may be divided into multiple blocks.

[0027] 3 is a block diagram showing a configuration example of a power receiving device (e.g., RX1 and RX2). The power receiving device includes, for example, a control unit 301, a power receiving unit 302, a first communication unit 303, a second communication unit 304, a power receiving coil 305, a charging unit 306, a battery 307, and a memory 308.

[0028] The control unit 301 controls the entire power receiving device. The control unit 301 includes, for example, one or more processors such as a central processing unit (CPU) or a micro processing unit (MPU). The control unit 201 may include an application specific integrated circuit (ASIC) or a field programmable gate array (FPGA) configured to execute the processes described below.

[0029] The power receiving unit 302 acquires the AC voltage and AC current generated in the power receiving coil 305 by power transmission from the power transmitting coil 205, and converts the received power into a DC voltage and DC current for operating the control unit 301, the charging unit 306, etc. The first communication unit 303 performs control communication for wireless power transmission based on the WPC standard with the first communication unit 204 of the power transmitting device. This control communication is performed by in-band communication (communication by a first method) that load modulates the electromagnetic waves received by the power receiving coil 305. In this embodiment, when only in-band communication is used for control communication with the power transmitting device, the power receiving device is capable of wirelessly receiving power from the power transmitting device and outputting a maximum of 15 watts of power to the charging unit 306.

[0030] The second communication unit 304 performs control communication of wireless power transmission based on the WPC standard with the second communication unit 206 of the power transmitting device. The second communication unit 304 uses a frequency different from the frequency of the electromagnetic waves received by the power receiving unit 302, and performs out-band communication (communication by the second method) using an antenna (not shown) different from the power receiving coil 305. In this embodiment, the second communication unit 304 is compatible with BLE, but instead of this, a communication unit compatible with other wireless communication methods such as NFC and WiFi may be used. In addition, the second communication unit 304 may receive power from a battery 307, or may receive power directly from the power receiving unit 302 without going through the battery 307. In this embodiment, when out-band communication is used for control communication with the power transmitting device, the power receiving device is capable of receiving power wirelessly from the power transmitting device and outputting a maximum of 100 watts of power to the charging unit 306.

[0031] The charging unit 306 charges the battery 307 using the DC voltage and DC current supplied from the power receiving unit 302. The memory 308 stores the overall state and each element of the power receiving device and the wireless power transmission system.

[0032] 3, the control unit 301, the power receiving unit 302, the first communication unit 303, the second communication unit 304, the charging unit 306, and the memory 308 are each depicted as separate blocks, but two or more of these blocks may be integrated into one chip, etc. Also, one block may be divided into multiple blocks.

[0033] In the following, the fact that a power transmitting device or a power receiving device supports control communication via out-of-band communication is referred to as being compatible with WPC standard version A. WPC standard version A is the successor to WPC v1.2.2, and includes at least the addition of a control communication function via out-of-band communication.

[0034] (Processing flow) Next, an example of the flow of processing executed in each device will be described, and then an example of the flow of processing in the entire system will be described.

[0035] [Power transmission device operation] An example of the flow of the process executed by the power transmitting device (TX1) will be described below with reference to FIG. 4. This process may be started in response to the power being turned on and the power transmitting unit 203 being started by receiving power supply from the power supply unit 202, etc. This process may be realized by the control unit 201 executing a program stored in the memory 207. However, this is not limited to the above, and may be executed in response to the power transmission function being started by an operation such as pressing a predetermined button by a user. At least a part of the process shown in FIG. 4 may be realized by hardware. When at least a part of the process is realized by hardware, for example, a dedicated circuit automatically generated on an FPGA using a predetermined compiler from a program for realizing the processing steps may be used. Similarly to the FPGA, the hardware for executing the predetermined processing steps may be realized by a gate array circuit.

[0036] When this process is started, the TX1 starts processing in accordance with the WPC standard. In the WPC standard, the other device is identified by a Selection phase (hereinafter referred to as the "Selection phase"), a Ping phase, and an Identification & Configuration phase (hereinafter referred to as the "I&C phase"). Then, in the Negotiation phase (hereinafter referred to as the "Negotiation phase"), negotiations regarding the transmission power are performed, and then, after a Calibration phase (hereinafter referred to as the "Calibration phase") for power transmission, processing is performed in the Power Transfer phase (hereinafter referred to as the "PT phase") in which actual power transmission is performed.

[0037] In FIG. 4, TX1 first executes the processes of the selection phase and the Ping phase (S401). In the selection phase, TX1 transmits an Analog Ping via the power transmitting coil 205. The Analog Ping is a small amount of power for detecting an object present in the vicinity of the power transmitting coil 205. TX1 detects the voltage value or current value of the power transmitting coil when transmitting the Analog Ping, and when the voltage is below a certain threshold or the current value exceeds a certain threshold, it determines that an object is present in the vicinity, and transitions to the Ping phase. Then, in the Ping phase, TX1 transmits a Digital Ping that is larger than the Analog Ping. Here, the Digital Ping has enough power to start the control unit 301, the first communication unit 303, and the second communication unit 304 of RX1 present in the vicinity of the power transmitting coil 205. When the control unit 301 and the first communication unit 303 of RX1 are activated by a Digital Ping received via the receiving coil 305, the control unit 301 and the first communication unit 303 notify TX1 of the magnitude of the receiving voltage by in-band communication by the first communication unit 303. When TX1 receives a notification of the receiving voltage value via the first communication unit 204, it ends the processing of the Ping phase and transitions to the I&C phase. In the I&C phase, TX1 receives an Identification Packet transmitted by RX1 (S402). At this time, TX1 may obtain information on whether or not RX1, which is the source of the packet, supports version A of the WPC standard, individual identification information of RX1 used in at least a version of the WPC standard earlier than version A, and identification information used in BLE. In one example, TX1 obtains the identification information used by RX1 in the WPC standard in the Identification Packet, and checks whether or not the EXT bit indicating the presence of additional ID information is set to "1". Then, when the EXT bit is "1", TX1 obtains additional ID information by the Extended Identification Packet transmitted subsequently according to the WPC standard. In this embodiment, the Extended Identification Packet stores an 8-byte Bluetooth Device Address that RX1 uses in BLE.In the following, the Bluetooth Device Address is referred to as "BD_ADDR". BD_ADDR is a public address defined in the BLE standard that indicates, for example, the manufacturer of RX1 or individual identification information of the BLE communication function (second communication unit 304). At this point, TX1 can recognize that the identification information of RX1 used in the WPC standard corresponds to the identification information of BLE (they relate to the same device).

[0038] In addition, TX1 also receives the Configuration Packet transmitted by RX1 in the I&C phase (S402). In this embodiment, a BLE bit indicating whether or not RX1, which is the source of this packet, supports control communication by BLE, is transmitted using one bit in the Configuration Packet. TX1, which supports the WPC standard version A, can determine whether or not RX1 has a control communication function using BLE by monitoring this bit. In addition, in this embodiment, a BLE Enable bit indicating whether RX1 can use BLE for control communication at that time is transmitted using another bit in the Configuration Packet. The Configuration Packet has a configuration as shown in FIG. 7, and the BLE bit / BLE Enable bit can be set in any of the reserved areas (areas 700, 701, and 702). At this time, if the BLE control communication is supported, the area (bit) in which the BLE bit is set is set to "1", and if the BLE can be used for control communication, the area in which the BLE Enable bit is set is set to "1". Since "0" is usually stored in the Reserved area, a power receiving device that complies with a version earlier than the WPC standard version A stores "0" in this area. This can prevent the power transmitting device from misunderstanding that a power receiving device that does not comply with version A of the WPC standard is compatible with or capable of executing control communication via BLE. Note that these are merely examples, and the Configuration Packet does not necessarily need to include these elements. For example, since it is known that communication via BLE is supported by transmitting BR_ADDR by the Extended Identification Packet as described above, the BLE bit may be omitted. In this case, TX1 can know whether RX1 is capable of executing control communication via BLE by transmitting only the BLE Enable bit, for example, when RX1 is not communicating with another device via BLE.Note that the BLE bit and the BLE Enable bit are merely examples and may not be used. For example, it may indicate whether or not outband communication not limited to BLE is supported, and whether or not control communication by outband communication is executable at the time of transmitting the Configuration Packet. Also, for each communication method available for outband communication other than BLE, an area similar to the BLE bit and the BLE Enable bit may be provided, which indicates whether or not a communication function is provided and whether or not control communication is executable. For example, an NFC bit indicating whether or not an NFC communication function is provided may be provided.

[0039] Then, in response to receiving the configuration packet, TX1 transmits an acknowledgement (ACK) by in-band communication (S403). In response to transmitting the ACK, TX1 transitions to the negotiation phase.

[0040] Furthermore, by receiving the Configuration Packet, TX1 determines whether RX1 has a control communication function by BLE and is in a state in which control communication by BLE can be performed with TX1 (S404). If RX1 does not have a control communication function by BLE or is not in a state in which control communication by BLE can be performed with TX1 (NO in S404), TX1 determines not to use outband communication (S420) since control communication by BLE cannot be performed with RX1. In this case, TX1 executes inband communication instead of outband communication. Then, TX1 determines that the maximum allowable value of Guaranteed Power (GP) is 15 watts (W) (S421). Note that GP refers to a power value guaranteed by the power transmitting device with respect to the output power to the load (e.g., charging unit or battery) of the power receiving unit 302 even if the positional relationship between the power transmitting device and the power receiving device is shifted and the power transmission efficiency between the power transmitting coil 205 and the power receiving coil 305 is reduced. TX1 determines the size of the allowable GP, and operates to reject a request for a GP that exceeds the allowable value in the subsequent negotiation. After that, TX1 moves the process to S414.

[0041] On the other hand, when RX1 has a control communication function by BLE and is in a state where control communication by BLE can be executed (YES in S404), TX1 judges whether or not there has been an inquiry about capability information from RX1 (S405). This inquiry about capability information is made by transmitting a General Request, which is data defined in the WPC standard, from RX1 to TX1. Hereinafter, such a General Request for inquiring about capability information is called "General Req (Capability)". When TX1 does not receive a General Req (Capability) (NO in S405), the process proceeds to S420 and determines not to use outband communication. On the other hand, when TX1 receives a General Req (Capability) (YES in S405), it transmits a Power Transmitter Capability Packet, defined in the WPC standard, to RX1. Hereinafter, the Power Transmitter Capability Packet is called a "TX Capability Packet". As shown in FIG. 8, the TX Capability Packet includes information about the capability of the power transmitting device, such as the maximum value of GP. In this embodiment, one bit of the reserved area (area 800 and area 801 in FIG. 8) of the TX Capability Packet is further allocated as a BLE Enable bit. This BLE Enable bit has the same meaning as the BLE Enable bit in the Configuration Packet transmitted by RX1. Note that TX1 may use one bit of the reserved area of ​​the TX Capability Packet as a BLE bit. This BLE bit also has the same meaning as the BLE bit in the Configuration Packet transmitted by RX1.

[0042] Prior to transmitting information in the TX Capability Packet, TX1 determines whether its own device is in a state in which BLE can be used (S406). If its own device is not in a state in which BLE can be used (NO in S406), TX1 sets the BLE Enable bit of the Tx Capability Packet to "0" and transmits it to RX1 (S419), and moves the process to S420. On the other hand, TX1 determines whether control communication by BLE can be performed at the present time based on, for example, whether its own device is operating as a BLE Peripheral or whether BLE is being used between itself and another device. For example, when its own device is a Central, TX1 can connect to multiple Peripherals, and therefore can determine that BLE can be used for control communication. Also, TX1 can determine that BLE can be used for control communication when its own device is not communicating with another device by BLE. On the other hand, TX1 can determine that BLE cannot be used for control communication when its own device is communicating with another device by BLE as a Peripheral. Furthermore, TX1 may perform this determination by communication with a control unit of a product (such as a printer) connected to TX1. For example, the control unit 201 of TX1 may be connected to the control unit of the product via GPIO (General Purpose Input / Output) or serial communication, and the control unit 201 of TX1 may inquire of the control unit of the product about the usage status of BLE. In this case, when a response from the control unit of the product regarding the usage status of BLE indicates that BLE is in use, the control unit 201 of TX1 may determine that BLE cannot be used for control communication at that time. Furthermore, when the response indicates that BLE is not in use, the control unit 201 of TX1 may determine that BLE can be used for control communication.

[0043] Then, if TX1 is in a state where its own device can use BLE (YES in S406), it sets the BLE Enable bit of the Tx Capability Packet to "1" and transmits it to RX1 (S407). Then, TX1 determines that it is possible to communicate with RX1 by BLE at this point, and stores the BD_ADDR of RX1 acquired in S402 in memory (S408). Note that TX1 may store the BD_ADDR of RX1 in memory at the time of acquiring it in S402, and discard the information when it determines that its own device cannot use BLE (NO in S406).

[0044] After the Tx Capability Packet with the BLE Enable bit set to "1" is transmitted in S407, TX1 may receive a signal from RX1 inquiring about the BLE identification information of TX1. This signal may be, for example, a General Request of the WPC standard. Hereinafter, the General Request inquiring about the BLE identification information is called "General Req (ID)". When TX1 receives the General Req (ID), it transmits a response including a BD_ADDR for the BLE of its own device to RX1. This response may be a Power Transmitter Identification Packet (hereinafter, called "TX ID Packet") defined in the WPC standard. The TX ID Packet includes the version of the WPC standard that the power transmitting device supports and an identification number by the manufacturer of the functional block related to the in-band communication of the power transmitting device. Furthermore, a power transmitting device that supports version A can include the BLE BD_ADDR in this TX ID Packet. This allows RX1 to recognize the WPC standard identification information of TX1 in association with the BLE identification information (BD_ADDR).

[0045] Following the process of S408, TX1 activates its own device's BLE communication function as a scanner in order to attempt control communication with RX1 via BLE (S409). Note that a scanner is one of the states defined in the BLE standard, and receives a broadcasted ADVERTISE_INDICATION and discovers the BLE device (or service) that sent it. In the following, ADVERTISE_INDICATION will be referred to as ADV_IND. ADV_IND is a signal that is broadcast by a device in the Advertiser state defined in the BLE standard, and is used to notify the BD_ADDR of the device and information on the services it supports.

[0046] After starting as a scanner, TX1 waits for an ADV_IND to be transmitted (S410). Then, when TX1 receives an ADV_IND for the BD_ADDR held in S408 (YES in S410 and S411) before a predetermined time has elapsed (while NO in S418), it transmits a connection request message by BLE to that BD_ADDR. That is, when TX1 receives an ADV_IND from RX1 before the timeout, it transmits a connection request message by BLE to RX1. This connection request message is CONNECT_REQ (hereinafter, sometimes referred to as "CONNECT") defined in the BLE standard. Then, TX1 moves to the negotiation phase. Here, since communication by BLE is possible, negotiation in the negotiation phase is performed using BLE. Since TX1 is in a state where control communication by BLE (outband communication) can be performed at this point, it determines that GP can be set sufficiently high. Therefore, TX1 sets the maximum allowable value of GP to, for example, 100 W (S413), and proceeds to the process of S414. Note that TX1 may execute a process of determining the maximum allowable value of GP after a connection for outband communication is actually established. In this case, even if TX1 has decided to use outband communication, if a connection for outband communication cannot actually be established, it may shift the process to S420.

[0047] Even if TX1 receives ADV_IND, it does not transmit CONNECT if the ADV_IND is not the ADV_IND of the BD_ADDR held in S408 (NO in S411). That is, in the stage of attempting control communication for power transmission, TX1 limits the target to which CONNECT is transmitted so that a BLE connection for a purpose other than such control communication is not established. If a timeout occurs without receiving ADV_IND from RX1 (YES in S418), the process proceeds to S420.

[0048] In S414, TX1 negotiates the GP with RX1. This negotiation is performed based on the maximum value of the GP that TX1 can tolerate and the value of the GP that RX1 requests. Note that the maximum value of the GP that TX1 can tolerate is determined by the processing of S413 or S421 according to whether or not outband communication is available, as described above. After that, TX1 executes the processing in the calibration phase (S415), and then transitions to the PT phase (S416) to transmit power to RX1. In the PT phase, control data requesting an increase or decrease in the transmission power is transmitted from RX1 to TX1. Since this communication is control communication, it is performed by BLE (outband communication) in a situation where it is available. After that, when TX1 receives an End Power Transfer (EPT) from RX1 requesting the stop of power transmission due to the end of charging, etc. (S417), it ends the power transmission processing. Note that the transmission and reception of EPT is also control communication, and therefore it is performed by BLE in a situation where it is available.

[0049] As described above, TX1 checks whether RX1 can execute control communication by BLE. In addition, TX1 recognizes the correspondence between RX1's identification information in the WPC standard and its identification information in BLE, and transmits CONNECT when TX1 receives ADV_IND including RX1's identification information in BLE. This makes it possible to establish a connection by BLE with the target of power transfer, while preventing the establishment of a connection by BLE with other devices that are not the target of power transfer.

[0050] [Power receiving device operation] Next, an example of the flow of the process executed by the power receiving device (RX1) will be described with reference to FIG. 5. This process may be executed, for example, when the power receiving function is activated by a user's operation such as pressing a predetermined button, or when RX1 is brought close to TX1. This process may be started when the control unit 301 and the first communication unit 303 are activated by the power received through the power receiving coil 305. This process may be realized by the control unit 301 executing a program stored in the memory 308, but dedicated hardware for executing the process described below may be used. For example, when at least a part of the process is realized by hardware, a dedicated circuit automatically generated on an FPGA using a predetermined compiler from a program for realizing the process steps may be used. Similarly to the FPGA, the hardware for executing the predetermined process steps may be realized by a gate array circuit.

[0051] In Fig. 5, RX1 is first placed near TX1 and is detected by TX1, which causes TX1 to transmit a Digital Ping. Then, the control unit 301 and the first communication unit 303 of RX1 are activated by the Digital Ping received via the receiving coil 305, and measure the magnitude of the receiving voltage of the Digital Ping. Then, RX1 notifies TX1 of the magnitude of the receiving voltage by in-band communication (S501). After that, RX1 transitions to the I&C phase.

[0052] In the I&C phase, RX1 transmits an Identification Packet to TX1 by in-band communication (S502). At this time, the Identification Packet includes information indicating whether or not it supports version A of the WPC standard, and individual identification information used in at least a version of the WPC standard earlier than version A. The individual identification information used in the WPC standard is identification information when control communication is performed by in-band communication. In addition, RX1 can set an EXT bit indicating whether or not there is additional ID information in the Identification Packet and transmit it. If there is additional ID information, RX1 sets the EXT bit of the Identification Packet to "1" and transmits an Extended Identification Packet for transmitting the additional ID information. The Extended Identification Packet is also transmitted by in-band communication according to the WPC standard. In this embodiment, an 8-byte BD_ADDR used in BLE is transmitted by the Extended Identification Packet.

[0053] After transmitting the Identification Packet, RX1 transmits a Configuration Packet. At this time, first, RX1 determines whether its own device is currently in a state in which BLE can be used for control communication (S503). The determination of whether BLE can be used for control communication is performed based on, for example, whether its own device is operating as a BLE Peripheral, whether BLE is being used between RX1 and another device, and the like. For example, when RX1 is a Central, RX1 can connect to a plurality of Peripherals, and therefore may determine that BLE can be used for control communication. In addition, RX1 may determine that BLE can be used for control communication when its own device is not communicating with another device by BLE. On the other hand, when its own device is communicating with another device by BLE as a Peripheral, RX1 may determine that BLE cannot be used for control communication. In addition, RX1 may perform this determination by communication with a control unit of a product (for example, a smartphone, a camera, etc.) connected to RX1. For example, the control unit 301 of RX1 and the control unit of the product may be connected by GPIO (General Purpose Input / Output) or serial communication, and the control unit 301 of RX1 may inquire of the control unit of the product about the usage status of BLE. In this case, when the response from the control unit of the product about the usage status of BLE indicates that BLE is in use, the control unit 301 of RX1 may determine that BLE cannot be used for control communication at that time. Also, when the response indicates that BLE is not in use, the control unit 301 of RX1 may determine that BLE can be used for control communication. Note that information indicating whether RX1 supports communication by BEL and whether BLE can be used for control communication may be transmitted using a reserved area of ​​a configuration packet as described above.

[0054] If RX1 cannot currently use BLE for control communication (NO in S503), it transmits a Configuration Packet with the BLE Enable bit set to "0" to TX1 by in-band communication (S520). Then, since RX1 cannot perform control communication with TX1 by BLE, it decides not to use out-band communication (S521). In this case, RX1 executes in-band communication instead of out-band communication. Then, RX1 decides that the maximum value of the GP to be requested is 15 watts (W) (S522), and the process proceeds to S523.

[0055] On the other hand, if RX1 can currently use BLE for control communication (YES in S503), it transmits a Configuration Packet with the BLE Enable bit set to "1" to TX1 by in-band communication (S504). After that, RX1 waits for an ACK from TX1 (S505). If RX1 does not receive an ACK (NO in S505), it transitions to the PT phase (S525) and receives the power transmitted from TX1. Then, RX1 transmits an EPT to TX1 (S526) in response to, for example, the completion of charging the battery 307 and the determination to end the power transmission, and terminates the process. A power transmitting device that supports only versions earlier than version 1.2 of the WPC standard does not support the negotiation phase and the calibration phase. For this reason, when such a power transmitting device receives a Configuration Packet, it transitions to the PT phase without transmitting an ACK. Therefore, when RX1 does not receive ACK from TX1, it transitions to the PT phase, so that it can receive power even if TX1 is a power transmitting device of a version earlier than version 1.2 of the WPC standard. That is, with this configuration, RX1 can ensure backward compatibility. Note that when ACK is not received, the maximum value of power that the power receiving unit 302 can supply to the load (the charging unit 306 and the battery 307) is limited to 5 watts.

[0056] When RX1 receives an ACK (YES in S505), it transmits a General Req (Capability) to inquire about the capability information of TX1 (S506) and waits for the response (TX Capability Packet) (S507). When it does not receive the TX Capability Packet (NO in S507), it decides not to use out-band communication (S521) and executes the above-mentioned processing from S522 onward. When RX1 receives a TX Capability Packet (YES in S507), it checks the BLE bit and BLE Enable bit of the packet and judges whether TX1 can execute control communication in BLE (S508). When it is judged that TX1 cannot execute control communication in BLE (NO in S508), the processing proceeds to S521.

[0057] When it is determined that TX1 can execute control communication in BLE (YES in S508), RX1 transmits General Req (ID) to acquire BLE identification information of TX1 (S509). Then, RX1 waits for a TX ID Packet from TX1 as a response to the General Req (ID) (S510). When the TX ID Packet is not received from TX1 (NO in S510), RX1 decides not to use outband communication (S521) and executes the above-mentioned process from S522 onward. On the other hand, when RX1 receives a TX ID Packet from TX1 corresponding to version A of the WPC standard (YES in S510), it acquires the BD_ADDR of TX1 stored in the packet and holds it in the memory 308 (S511). At this point, RX1 can recognize the association between the identification information of TX1 in the WPC standard and the BD_ADDR in BLE. Then, in order to perform control communication with TX1 by BLE, RX1 starts its own device as a BLE advertiser (S512) and broadcasts ADV_IND (S513). Note that the advertiser is one of the states defined in the BLE standard, and its role is to notify its own device's BD_ADDR and supported service information by ADV_IND so that the above-mentioned Scanner can find a BLE device (or service). Here, ADV_IND includes a UUID (Universally Unique IDentifier) ​​indicating a service (profile) supported by the second communication unit 304. Note that in this embodiment, a UUID indicating a wireless charging service (hereinafter referred to as a "wireless charging service") using out-band communication according to the WPC standard is included in ADV_IND. In addition, ADV_IND may also include information such as the device type (e.g., camera, smartphone), manufacturer name, model name, and serial number of the product to which the power receiving device (RX1) is connected.

[0058] After that, RX1 waits for CONNECT transmitted from the Scanner that received ADV_IND (S514). Then, when RX1 receives CONNECT (YES in S514), it judges whether or not the identification information of the transmission source of the CONNECT is held in the memory 308 as the identification information (BD_ADDR) of TX1 (S515). That is, RX1 judges whether or not the transmission source of the CONNECT is TX1. Here, if the transmission source of the CONNECT is not TX1 (NO in S515), RX1 transmits LL_TERMINATE_IND indicating that the BLE connection established by CONNECT is to be disconnected to the device that transmitted the CONNECT (S518). Note that LL_TERMINATE_IND will be referred to as "TERMINATE" below. If RX1 has not received CONNECT from TX1 (NO in S514 or S515), it repeatedly transmits ADV_IND (S513) until a predetermined time has elapsed since the start of transmission of ADV_IND and a timeout occurs (while NO in S519). If RX1 times out without receiving CONNECT from TX1 (YES in S519), it decides not to use outbound communication (S521) and executes the above-mentioned processes from S522 onwards.

[0059] On the other hand, when RX1 receives CONNECT from TX1 (YES in S514 and S515), it decides to use outband communication (S516) and decides to set the maximum GP value requested to 100 watts (W) (S517). RX1 may perform a process of determining the requested GP value in response to the decision to use outband communication, or may perform this process after the connection in outband communication is actually established. Even if RX1 decides to use outband communication in S516, if the connection in outband communication cannot actually be established, it may move the process to S521. After that, RX1 advances the process to S523. In S523, RX1 negotiates the GP with TX1. This negotiation is performed based on the maximum GP value that is acceptable to TX1 and the GP value requested by RX1. The maximum GP value requested by RX1 is determined by the process of S517 or S522 depending on whether or not the outband communication is available, as described above. Then, after performing the process in the calibration phase (S524), RX1 transitions to the PT phase (S525) and receives power from TX1. In the PT phase, control data is transmitted from RX1 to TX1 requesting an increase or decrease in the transmission power. Since this communication is control communication, it is performed by BLE (outband communication) in a situation where BLE is available. After that, for example, in response to the end of charging, RX1 transmits an EPT indicating a request to TX1 to stop the power transmission for battery charging by BLE (outband communication) (S526). Then, RX1 transmits TERMINATE to disconnect the BLE connection as necessary, and ends this process. Note that TX1 may transmit TERMINATE after transmitting EPT.

[0060] As described above, RX1 checks whether TX1 can execute control communication by BLE. In addition, RX1 recognizes the WPC standard identification information of TX1 in association with the BLE identification information, and when RX1 receives a CONNECT that does not include the BLE identification information of TX1, it disconnects the connection and accepts only CONNECT from TX1. This makes it possible to establish a BLE connection with the target of power transfer, while preventing the establishment of a BLE connection with other devices that are not the target of power transfer.

[0061] [Power transmission system processing flow] Next, an example of the flow of processing executed in the power transmission system will be described with reference to FIG. 6. First, in TX1, when the power transmitting unit 203 receives power supply from the power supply unit 202 and starts up, TX1 starts operation in accordance with the WPC standard. That is, first, in the selection phase, TX1 transmits an Analog Ping via the power transmitting coil 205 (M601). Then, as shown in FIG. 3, TX1 detects that RX1 is present in the vicinity of its own device (within the power transmitting and receiving range) by the Analog Ping, and transitions to the Ping phase. Then, in the Ping phase, TX1 transmits a Digital Ping (M602). When the control unit 301 and the first communication unit 303 of RX1 start up by the Digital Ping received via the power receiving coil 305, RX1 notifies TX1 of the magnitude of the receiving voltage by in-band communication by the first communication unit 303 (M603), and transitions to the I&C phase. When TX1 receives the notification of the received voltage value, it ends the processing of the Ping phase and transitions to the I&C phase.

[0062] Next, RX1 transmits an Identification Packet to TX1 using the first communication unit 303 (M604). Here, RX1 notifies TX1 of information indicating that it supports version A of the WPC standard and individual identification information of RX1 used in at least a version of the WPC standard earlier than version A in the Identification Packet. In this processing example, RX1 transmits an Identification Packet with the EXT bit set to "1" in order to transmit identification information used in BLE later. Then, RX1 transmits an 8-byte BD_ADDR used in BLE by including it in an Extended ID Packet and by in-band communication (M605). Then, in this processing example, RX1 transmits a Configuration Packet in which the BLE bit is set to "1" indicating that the device itself supports control communication by BLE (M606). In addition, in this Configuration Packet, the BLE Enable Bit is set to "1".

[0063] TX1 transmits an acknowledgement (ACK) by in-band communication in response to the configuration packet from RX1 (M607). After transmitting the ACK, TX1 transitions to the negotiation phase. Furthermore, upon receiving the ACK, RX1 ends the I&C phase and transitions to the negotiation phase. Note that at this point, TX1 can recognize that RX1's identification information in the WPC standard corresponds to the BD_ADDR in BLE. Furthermore, TX1 can recognize that RX1 is capable of control communication by BLE.

[0064] After that, RX1 transmits a General Req (Capability) by in-band communication to obtain information about the capabilities of TX1 (M608). When TX1 receives this General Req (Capability), it transmits a TX Capability Packet to RX1 (M609). Here, TX1 transmits a TX Capability Packet including information that TX1 supports version A of the WPC standard and with the BLE bit / BLE Enable Bit set to "1" to indicate that TX1 can execute control communication by BLE. At this time, when RX1 receives the TX Capability Packet, it can recognize that TX1 supports control communication by BLE and that BLE can be used for control communication. Next, RX1 transmits a General Req (ID) by in-band communication to request transmission of identification information of TX1 (M610). When TX1 receives this General Req (ID), it transmits a TX ID Packet to RX1 by in-band communication (M611). At this point, RX1 can recognize that TX1's identification information in the WPC standard corresponds to the BD_ADDR in BLE, and can also recognize that TX1 is capable of control communication by BLE.

[0065] After that, RX1 starts its own BLE as an Advertiser to attempt control communication with TX1 via BLE, and transmits ADV_IND (M612). At this time, TX1 holds in memory the BD_ADDR of RX1 acquired in M405, and starts its own device as a BLE Scanner to perform control communication with RX1 via BLE.

[0066] Here, it is assumed that not only TX1 but also another device (for example, the first communication device 121) operates as a scanner. At this time, it is assumed that the other device receives ADV_IND transmitted by RX1 in M612 and transmits CONNECT to RX1 to request a connection by BLE (M613). When RX1 receives this CONNECT, it refers to the memory 308 and determines whether or not the identification information of the transmission source of CONNECT matches the identification information (BD_ADDR) of TX1. In this case, since the other device is different from TX1, RX1 determines not to connect to this other device and transmits TERMINATE to this other device (M614).

[0067] On the other hand, when TX1 receives ADV_IND, it checks whether or not the ADV_IND includes a UUID indicating a wireless charging service. Here, as described above, ADV_IND includes a UUID corresponding to the wireless charging service. Then, TX1 subsequently refers to the memory 207 and determines whether or not the sender of ADV_IND matches the identification information (BD_ADDR) of RX1 stored in the memory 207. Since the ADV_IND in M612 is sent from RX1, TX1 determines to connect to RX1, which is the sender of ADV_IND, and sends CONNECT to RX1 (M615). Then, since the sender of this CONNECT is TX1, RX1 does not send TERMINATE in this case and maintains the connection.

[0068] There is a case where TX2 receives ADV_IND transmitted by RX1. However, in this case, TX2 holds the BD_ADDR of RX2, which is present within the power transmission / reception range, in the memory 207, but does not hold the BD_ADDR of RX1. For this reason, TX2 does not transmit CONNECT to RX1.

[0069] After that, TX1 and RX1 negotiate on GP using BLE (outband communication) (M616). At this point, TX1 can use BLE (outband communication) for control communication with RX1 that exists within the power transmission and reception range, so the maximum allowable GP value is set to 100 watts (W). Similarly, RX1 also requests a maximum GP value of 100 watts (W). Then, TX1 and RX1 negotiate to determine the GP using these allowable GP values ​​and the required GP values. After that, after processing in the calibration phase is performed (M617), power is transmitted between TX1 and RX1 in the PT phase for charging the battery (M618). In the PT phase, control data requesting an increase or decrease in the transmission power is transmitted from RX1 to TX1, and in this example, this is performed by BLE (outband communication).

[0070] When charging is completed, RX1 transmits an EPT to TX1 by BLE (outband communication) indicating a request to stop power transmission for battery charging (M619). When TX1 receives this EPT, it terminates power transmission for charging. Then, when this power transmission for charging is terminated, RX1 transmits a TEMINATE to TX1 and disconnects the BLE (M620).

[0071] As described above, in this embodiment, the power transmitting device and the power receiving device use in-band communication to determine whether the other device supports out-band communication. Then, the power transmitting device and the power receiving device use in-band communication to obtain identification information used by the other device in out-band communication. Furthermore, when the power transmitting device receives AVD_IND in out-band communication, it determines whether to send CONNECT based on the identification information obtained in in-band communication. Moreover, when the power receiving device receives CONNECT as a response to AVD_IND, it determines whether to send TERMINATE based on the identification information received in in-band communication.

[0072] This allows the power transmitting device and the power receiving device to perform control communication by BLE with the power receiving device and the power transmitting device within the power transmission / reception range prior to transmitting / receiving power for charging the battery and negotiating the power. By performing control communication by out-of-band communication in this manner, it becomes possible to transmit and receive a larger amount of power than in the case of in-band communication.

[0073] In addition, even if the other device supports BLE, the power transmitting device and the power receiving device determine to use in-band communication instead of out-band communication if BLE is not available (BLE Enable bit is "0") This allows the power transmitting device and the power receiving device to transmit and receive power using in-band communication when BLE is already being used by the control unit of the product to which the other device is connected.

[0074] In the above embodiment, when out-band communication cannot be performed, the maximum GP allowable in the power transmitting device and the maximum value of the GP required in the power receiving device are set to 15 watts. Also, when TX1 is a power transmitting device of a version earlier than version 1.2 of the WPC standard, the power supplied to the load of the power receiving device is limited to 5 watts. On the other hand, depending on the product connected to the power receiving device, it is assumed that the product cannot operate due to insufficient power at 5 watts or 15 watts. For example, the load does not operate on battery power, and is a product that receives power directly from the power receiving unit 302. In this case, if 5 watts or 15 watts of power is supplied, it may cause the product to malfunction. In order to avoid such a state, the power receiving device may transmit an EPT to the power transmitting device when it is determined that out-band communication cannot be used for control communication. This can prevent insufficient power from being supplied by wireless power transmission, and prevent problems such as product malfunction.

[0075] On the other hand, it is also conceivable that the control unit of the product connected to RX1 controls the BLE (second communication unit 304) of RX1, and the second communication unit 304 operates on the power of the battery 307. In such a system, out-of-band communication cannot be performed when the remaining battery power is insufficient (for example, when the remaining battery power is 0). However, when the product operates on battery power and the remaining battery power is insufficient, the product does not operate, so problems such as the above-mentioned malfunction do not occur. For this reason, RX1 may receive power at 15 watts using in-band communication instead of transmitting EPT.

[0076] In the above embodiment, RX1 requests the transmission of BD_ADDR of TX1 by transmitting General Req(ID), but this is not limited to this. For example, a reserved packet or a proprietary packet with an undefined packet type may be used for this request among the specific requests of version 1.2.2 of the WPC standard. For example, a reserved packet or a proprietary packet with an undefined packet type may be used for this request among the general requests of version 1.2.2 of the WPC standard. For example, a packet other than a specific request or a general request may be used for this request among the packets of version 1.2.2 of the WPC standard. For example, a reserved packet or a proprietary packet with an undefined packet type other than a specific request or a general request may be used for this request.

[0077] Also, it has been described that RX1 notifies TX1 that its own device supports control communication by BLE using a Configuration Packet. However, this is not limited to this. For example, this notification may be made by a Reserved Packet or a Proprietary Packet with an undefined packet type among Specific Requests of version 1.2.2 of the WPC standard. Also, a Reserved Packet or a Proprietary Packet with an undefined packet type among General Requests of version 1.2.2 of the WPC standard may be used for this notification. Also, a packet other than a Specific Request or a General Request among packets of version 1.2.2 of the WPC standard may be used for this notification. For example, a Reserved Packet or a Proprietary Packet with an undefined packet type other than a Specific Request or a General Request may be used for this notification.

[0078] In the above description, the BD_ADDR is a public address defined in the BLE standard that indicates the individual identification information of the manufacturer of the power transmitting device or the power receiving device, or the BLE communication circuit (second communication unit), but is not limited to this. For example, the BD_ADDR may be a random number automatically generated by the second communication unit, such as a random address defined in the BLE standard. Among the random addresses, any of a static device address, a resolvable private address, and a non-resolvable private address may be used. Here, the static device address is a random number address that is generated every time the second communication unit (BLE communication circuit) is powered on. The non-resolvable private address is a random number address that is generated at regular intervals. The resolvable private address is an address that is generated based on an encryption key exchanged between the Central and the Peripheral.

[0079] Also, it has been explained that RX1 transmits ADV_IND in M612, and transmits TERMINATE to CONNECT from a BLE-compatible device other than TX1 that transmitted BD_ADDR in-band (for example, the first communication device 121 or TX2). Instead of this, ADV_DIRECT_IND, which is defined in the BLE standard and can directly specify the BD_ADDR of the BLE-compatible device that transmits CONNECT, may be transmitted in M612. For example, RX1 transmits ADV_DIRECT_IND storing the BD_ADDR of TX1 in M612. In this case, only TX1 that has been specified with the BD_ADDR transmits CONNECT, and the first communication device 121 does not transmit CONNECT. This can simplify the BLE connection process.

[0080] In the present embodiment, as shown in FIG. 1, an example has been described in which the power receiving device is a Peripheral and the power transmitting device is a Central. However, the power receiving device may be a Central and the power transmitting device may be a Peripheral. That is, in the process related to BLE described above, RX1 and TX1 may be replaced. For example, TX1 may start up its own device's BLE as an Advertiser to attempt control communication with RX1 by BLE, and transmit ADV_IND in M612. Then, RX1 may start up its own device's BLE as a Scanner to attempt control communication with TX1 by BLE, and receive ADV_IND from TX1. When the identification information of the sender of the ADV_IND corresponds to the BD_ADDR of TX1 acquired by receiving the TX ID Packet in M611, RX1 may transmit CONNECT to TX1 in M615. TX1 establishes and maintains a connection in BLE by CONNECT from RX1 based on the BD_ADDR of RX1 acquired by receiving the Extended ID Packet acquired in M605. On the other hand, when TX1 receives a CONNECT from a device other than RX1, it rejects the BLE connection by transmitting a TERMINATE to disconnect the established BLE connection. Note that even in this case, TX1 may transmit, in M612, an ADV_DIRECT_IND that stores the BD_ADDR of RX1 that was previously received.

[0081] In the above description, TX1 or RX1 uses the BLE bit or the BLE Enable bit to determine whether the other device supports BLE or whether BLE is available. However, at least one of these determinations may be made by a response to a packet transmitted by RX1 requesting a transition from in-band communication to out-band communication. In the negotiation phase, RX1 may use a Reserved Packet or a Proprietary Packet packet with an undefined packet type among the Specific Request packets of version 1.2.2 of the WPC standard for this request. Also, a Reserved Packet or a Proprietary Packet with an undefined packet type among the General Request packets of version 1.2.2 of the WPC standard may be used for this request. Also, a packet other than a Specific Request or a General Request packet among the packets of version 1.2.2 of the WPC standard may be used for this request. For example, by using these packets, a packet requesting outband communication may be newly defined, and when RX1 receives an ACK from TX1 as a response to the packet, it may determine that TX1 supports BLE and can use BLE (YES in S508). Also, when RX1 receives a NAK, which means a denial of the request, it may determine that TX1 does not support BLE or cannot use BLE, and may determine to use inband communication (S521). Also, when TX1 does not support version A, TX1 transmits a No Data Response (ND Resp) packet or a Not Data Available packet indicating that it cannot understand this request. Therefore, when RX1 receives an ND Resp packet or a Not Data Available packet, it may determine that TX1 does not support outband communication and therefore to use inband communication (S521).

[0082] In the above embodiment, RX1 transmits the BD_ADDR using an Extended ID Packet. By using the Extended ID Packet already defined in the WPC standard to transmit the BD_ADDR, it is possible to use a packet that is already defined without defining a new packet in version A.

[0083] Also, after transmitting and receiving the ACK of M607, TX1 and RX1 of version 1.2.2 move to the negotiation phase and negotiate the GP. In contrast, TX1 and RX1 of this embodiment perform the BLE connection process (M612, M615) and then perform negotiation to determine whether the GP should be set to 15 watts or 100 watts depending on the result of the connection process. At this time, by determining the maximum value of the GP allowable in TX1 and the GP required in RX1 prior to the negotiation based on the result of the BLE connection, it becomes unnecessary to set an inappropriate GP and perform renegotiation. As a result, it is possible to reduce the time loss caused by such renegotiation. For example, if it is decided to transmit 100 watts as a result of the negotiation and then BLE connection cannot be established, renegotiation is required with the maximum value of the GP set to 15 watts, but such an event can be avoided.

[0084] In the above description, an example in which wireless power transmission conforming to the WPC standard is used has been described, but the power transmission method is not particularly limited. For example, a magnetic resonance method may be used in which power is transmitted by coupling due to magnetic resonance between a TX resonator (resonant element) and an RX resonator (resonant element). In addition, a power transmission method using an electromagnetic induction method, an electric field resonance method, a microwave method, a laser method, or the like may be used.

[0085] The above description has been given using specific technical terms based on the WPC standard and the BLE standard, but is not limited thereto. That is, the present invention should be understood to include a case in which a message having a similar purpose is transmitted and received and a similar process is executed in a system having a similar configuration. In addition, in the above description, it has been described that a region for transmitting specific information is provided in a specific message in the WPC standard or the BLE standard, but is not limited thereto. That is, a message different from the above description may be used to transmit information of the same purpose. For example, it has been described that information indicating whether RX1 is compatible with BLE or is in a state in which control communication by BLE can be executed is stored in a specific region in the Configuration Packet, but a new message for transmitting this information may be defined. The same applies to other messages.

[0086] The power transmitting device and the power receiving device may be included in, for example, an image input device such as an imaging device (such as a camera or a video camera) or a scanner, or an image output device such as a printer, a copier, a projector, etc. The power transmitting device and the power receiving device may be included in a storage device such as a hard disk device or a memory device, or may be included in an information processing device such as a personal computer (PC) or a smartphone.

[0087] <<Other embodiments>> The present invention can also be realized by a process in which a program for implementing one or more of the functions of the above-described embodiments is supplied to a system or device via a network or a storage medium, and one or more processors in a computer of the system or device read and execute the program. The present invention can also be realized by a circuit (e.g., ASIC) that implements one or more of the functions. [Explanation of symbols]

[0088] 101, 102: power transmitting device, 111, 112: power receiving device, 201: control unit, 202: power supply unit, 203: power transmitting unit, 204: first communication unit, 205: power transmitting coil, 206: second communication unit, 207: memory, 301: control unit, 302: power receiving unit, 303: first communication unit, 304: second communication unit, 305: power receiving coil, 306: charging unit, 307: battery, 308: memory

Claims

1. A power receiving means for wirelessly receiving power from a power transmitting device; A communication means for communicating with the power transmitting device, when the communication means receives, at a first frequency, a first packet indicating that communication at a second frequency is possible from the power transmission device, the communication means communicates with the power transmission device at the second frequency; when the communication means receives a packet indicating a NAK from the power transmitting device in response to the second packet transmitted at the first frequency, the communication means transmits a packet indicating a power transmission stop. Powered device.

2. The power receiving device according to claim 1 , wherein the first packet is a packet indicating a capability of the power transmitting device.

3. The power receiving device according to claim 1 , wherein the second packet is a packet requesting communication at the second frequency.

4. A program for causing a computer to function as each of the means of the power receiving device according to any one of claims 1 to 3.

5. A communication method executed by a power receiving device that wirelessly receives power from a power transmitting device, comprising: a first communication step of communicating with the power transmitting device at the second frequency when a first packet indicating that communication at a second frequency is possible is received from the power transmitting device at a first frequency; a second communication step of transmitting a packet indicating a power transmission stop when a packet indicating a NAK is received from the power transmitting device in response to the second packet transmitted at the first frequency; A communication method including:

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