Electric power feeding device, electric power reception device, method performed by said devices, and program

Abstract

This electric power feeding device carries out a transaction with an electric power reception device, wirelessly feeds electric power to the electric power reception device on the basis of the result of the transaction, and executes a process including detection of a near field communication (NFC) tag (F709–F724). In at least the transaction, the electric power feeding device transmits, to the electric power reception device, information relating to the NFC tag detection performed during electric power feeding.

Description

Power transmitting device, power receiving device, and methods and programs for performing these functions

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

[0002] In recent years, technological development of wireless power transmission systems has been widely carried out. The technologies of wireless power transmission systems generally comply with the standard (WPC standard) established as a wireless charging standard by the Wireless Power Consortium (WPC).

[0003] Meanwhile, the NFC standard is known as a standard for short-range wireless communication. NFC stands for Near Field Communication. In the NFC standard, polling refers to transmitting a carrier wave and modulating the carrier wave to send a message for detecting a device with which to communicate. Polling is transmitted by a device having a function called an NFC-standard reader / writer. An NFC tag is a device that has the function of receiving polling transmitted by the reader / writer and responding to the polling by applying load modulation to the carrier wave transmitted by the reader / writer.

[0004] Furthermore, a power transmitting device that complies with the WPC standard and is equipped with an NFC reader / writer can detect NFC tags in various processes of the WPC standard. The power transmitting device can perform NFC tag detection processing while periodically polling NFC during a negotiation process or a process of transmitting power to a power receiving device.

[0005] Patent Literature 1 discloses a technology in which a power transmitting device having an NFC tag detection function transmits information indicating the result of an NFC tag detection process (detection status) to a power receiving device during a negotiation process of the WPC standard. Specifically, the power transmitting device transmits, as detection status, information indicating whether the NFC tag detection process has been executed or not, and, when the NFC tag detection process has been executed, information indicating whether an NFC tag has been detected or not, to the receiving device.

[0006] Furthermore, in recent years, wireless power transmission systems have been required to transmit higher power output, and efforts are being made to improve user convenience by enabling faster charging through higher power output.

[0007] Patent No. 7336581

[0008] Frequency noise may occur during wireless power transmission. Such noise may interfere with the communication frequency used for NFC tag detection that may be performed during power transmission. As a result, the power transmitting device may not be able to properly perform NFC tag detection.

[0009] The present disclosure provides a technique that can appropriately execute an NFC tag detection process.

[0010] A power transmission device according to one embodiment of the present disclosure includes a negotiation means for negotiating with a power receiving device, a power transmission means for wirelessly transmitting power to the power receiving device based on a result of the negotiation, a processing means for executing processing including detection of an NFC (Near Field Communication) tag, and a communication means for transmitting, at least during the negotiation, information regarding NFC tag detection performed during the power transmission to the power receiving device.

[0011] According to the present disclosure, it is possible to appropriately execute the NFC tag detection process.

[0012] 1 is a diagram illustrating an example of the configuration of a wireless power transmission system according to the first embodiment. FIG. 1 is a block diagram illustrating an example of the configuration of a power receiving device. FIG. 2 is a block diagram illustrating an example of the configuration of a power transmitting device. FIG. 3 is a sequence diagram illustrating an example of basic processing by a power transmitting device and a power receiving device according to the first embodiment. FIG. 4 is a flowchart illustrating an example of processing performed by a power receiving device according to the first embodiment. FIG. 5 is a flowchart illustrating a continuation of FIG. 6. FIG. 7 is a flowchart illustrating an example of processing performed by a power transmitting device according to the first embodiment. FIG. 9 is a flowchart illustrating a continuation of FIG. 10. FIG. 11 is a sequence diagram illustrating an example of processing by a power transmitting device and a power receiving device. FIG. 12 is a diagram illustrating an example of a state in which an NFC tag is inserted between a power transmitting device and a power receiving device. FIG. 13 is a flowchart illustrating processing performed by a power receiving device according to the second embodiment. FIG. 14 is a flowchart illustrating processing by a power transmitting device and a power receiving device according to the second embodiment. FIG. 15 is a flowchart illustrating processing performed by a power receiving device according to the third embodiment. FIG. 16 is a flowchart illustrating processing performed by a power transmitting device according to the third embodiment. FIG. 17 is a sequence diagram illustrating processing by a power transmitting device and a power receiving device according to the third embodiment. FIG. 18 is a diagram illustrating examples of information transmitted by a power transmitting device to a power receiving device during negotiation. FIG. 10 is a diagram illustrating an example of a state notification command for a power transmitting device.

[0013] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. Not all of the features in the embodiments of the present disclosure are essential, and multiple features may be combined as desired. Furthermore, the configurations shown in the following embodiments are merely examples, and the present disclosure is not limited to the illustrated configurations. In the drawings, the same reference symbols are used to designate the same or similar configurations, and redundant explanations will be omitted.

[0014] [First embodiment] <System configuration> Fig. 1 is a diagram showing an example of the configuration of a wireless power transmission system according to one embodiment. The configuration of the wireless power transmission system according to this embodiment is shown. In one example, the wireless power transmission system includes a power receiving device 101 and a power transmitting device 102. For simplicity of notation, the power transmitting device 102 may be referred to as TX and the power receiving device 101 may be referred to as RX below.

[0015] The RX is, for example, an electronic device that receives power from the TX and charges a built-in battery. The RX also includes a Wireless Power Consortium (WPC) function that complies with the WPC standard and is also compatible with the device authentication protocol of the standard.

[0016] The TX is, for example, an electronic device that wirelessly transmits power to the RX placed on the device itself. The TX transmits power wirelessly to the RX via a power transmission antenna.

[0017] This system performs wireless power transmission using an electromagnetic induction method for contactless charging based on the WPC standard. That is, the RX and TX perform wireless power transmission for contactless charging based on the WPC standard between the RX's power receiving antenna and the TX's power transmitting antenna. Note that the wireless power transmission method (contactless power transmission method) is not limited to the method specified by the WPC standard, and may be other methods such as electromagnetic induction, magnetic field resonance, electric field resonance, microwave, or laser. Furthermore, in this embodiment, wireless power transmission is used for contactless charging, but wireless power transmission may also be performed for purposes other than contactless charging.

[0018] In the WPC standard, the amount of power guaranteed when an RX receives power from a TX is specified by a value called guaranteed power, i.e., guaranteed load power (hereinafter referred to as "GP"). GP indicates the power value guaranteed to be output to an RX load, such as a charging circuit, even if the positional relationship between the RX and TX fluctuates and the power transmission efficiency between the receiving antenna and the transmitting antenna decreases, i.e., the RX load power value (load power). Furthermore, GP may be a load power level agreed upon through negotiation between the TX and RX. For example, if the GP is 15 watts, the TX transmits power by controlling so as to output 15 watts to the load in the RX, even if the positional relationship between the receiving antenna and the transmitting antenna fluctuates and the power transmission efficiency decreases.

[0019] 2 is a diagram showing an example of the configuration of an RX according to this embodiment. The RX includes a control unit 201, a WPC communication unit 203, a receiving antenna (receiving coil) 204, a receiving unit 205, a detection unit 206, a charging unit 207, a battery 208, a notification unit 209, an operation unit 210, a memory 211, and a timer 212.

[0020] The control unit 201 controls the entire RX. The control unit 201 includes one or more processors, such as a CPU (Central Processing Unit) or an MPU (Microprocessor Unit). The control unit 201 can also measure time using a timer 212. The control unit 201 performs control by executing a control program stored in a memory 211, for example.

[0021] The control unit 201 may be configured with hardware dedicated to a specific process, such as an application specific integrated circuit (ASIC). Alternatively, the control unit 201 may be configured to include an array circuit, such as a field programmable gate array (FPGA), compiled to execute a predetermined process. The control unit 201 stores information to be stored in the memory 211 while executing various processes.

[0022] In this embodiment, the control unit 201 is illustrated as a single component, but is not limited to this. For example, a WPC control unit that controls processing related to power reception with a power transmitting device in a power receiving device may be configured separately from the control unit 201. Alternatively, a WPC control unit that controls processing related to WPC communication may be configured separately from the control unit 201. When the control unit 201 is configured as multiple separate units, the respective control units are connected to each other via a communication interface, enabling data communication. Specifically, the communication interface may be any interface that realizes data communication, such as I2C or GPIO.

[0023] The WPC communication unit 203 performs wireless power transmission communication based on the WPC standard with the communication unit 306 of the TX. The WPC communication unit 203 demodulates the electromagnetic waves input from the power receiving antenna 204 to acquire information transmitted from the TX, and performs load modulation of the electromagnetic waves to superimpose the information to be transmitted to the TX onto the electromagnetic waves, thereby performing communication with the TX. In other words, the communication performed by the communication unit 306 is superimposed on the electromagnetic waves transmitted from the power transmitting antenna 305 of the TX.

[0024] The power receiving unit 205 receives AC power (AC voltage and AC current) generated by electromagnetic induction based on electromagnetic waves radiated from the power transmitting antenna of the TX via the power receiving antenna 204. The power receiving unit 205 converts the AC power into DC or AC power of a predetermined frequency and outputs it to the detection unit 206. The power receiving unit 205 is primarily an example of a power receiving means that receives power wirelessly from the power transmitting device based on negotiation.

[0025] The detection unit 206 detects that the RX is placed on the TX based on the WPC standard. For example, the detection unit 206 detects at least one of the voltage value and the current value of the power receiving antenna 204 when the power receiving unit 205 receives a Digital Ping of the WPC standard via the power receiving antenna 204. For example, the detection unit 206 can determine that the RX is placed on the TX (is in a state where it can receive power) when the voltage value is below a predetermined voltage threshold or the current value exceeds a predetermined current threshold.

[0026] Charging unit 207 charges battery 208 with power supplied from power receiving unit 205. Charging unit 207 also starts or stops charging battery 208 based on the control of control unit 201, and further adjusts the power used to charge battery 208 based on the charge state of battery 208. When the power used by charging unit 207 changes, the power supplied from power receiving unit 205, i.e., the received power in RX, also changes accordingly. Charging unit 207 shown here is a load in RX.

[0027] The battery 208 supplies the entire RX with power required for control of each part of the RX by the control unit 201 and for power reception and communication. The battery 208 also stores power received via the power receiving antenna 204.

[0028] The notification unit 209 notifies the user of information by any method such as visually, audibly, or tactilely. The notification unit 209 notifies the user of, for example, the charging status of the RX or the status related to power transmission of the wireless power transmission system including the RX and TX as shown in Fig. 1. The notification unit 209 includes, for example, a liquid crystal display, an LED, a speaker, a vibration generating circuit, and / or other notification devices.

[0029] The operation unit 210 has a function of receiving operations for the RX from the user. The operation unit 210 includes, for example, a voice input device such as a button, a keyboard, or a microphone, a motion detection device such as an acceleration sensor or a gyro sensor, and / or other input devices. Note that a device in which the notification unit 209 and the operation unit 210 are integrated, such as a touch panel, may also be used.

[0030] As described above, the memory 211 stores various types of information such as identification information and device configuration information, control programs, etc. The memory 211 may store information obtained by a functional unit other than the control unit 201.

[0031] The timer 212 measures time using, for example, a count-up timer that measures the elapsed time from the time of activation, or a count-down timer that counts down from a set time.

[0032] 3 is a diagram showing an example of the configuration of the TX according to this embodiment. The TX has a control unit 301, a power supply unit 302, a power transmission unit 303, a detection unit 304, and a power transmission antenna (power transmission coil) 305. The TX also has a communication unit 306, a notification unit 307, an operation unit 308, a memory 309, a timer 310, and an NFC (Near Field Communication) communication unit 311.

[0033] The control unit 301 controls the entire TX by executing a control program stored in the memory 309, for example. That is, the control unit 301 controls each functional unit shown in FIG. 3 . The control unit 301 also controls power transmission control in the TX. The control unit 301 also controls the NFC function in the TX. The control unit 301 may also control the execution of applications other than wireless power transmission. The control unit 301 includes one or more processors, such as a CPU or MPU. The control unit 301 may be configured with a single processor, or a main control unit that controls the entire TX and a sub-control unit that controls power transmission processing and NFC communication may each be implemented by separate processors.

[0034] The control unit 301 may be configured to include hardware dedicated to a specific process, such as an application specific integrated circuit (ASIC), or an array circuit, such as an FPGA, compiled to execute a predetermined process. The control unit 301 stores information to be stored while executing various processes in the memory 309. The control unit 301 may also measure time using a timer 310.

[0035] The power supply unit 302 supplies the entire TX with power required for the control of the TX by the control unit 301 and for power transmission and communication. The power supply unit 302 is, for example, a commercial power supply or a battery. The battery stores power supplied from the commercial power supply.

[0036] The power transmitting unit 303 converts the DC or AC power input from the power supply unit 302 into AC frequency power in a frequency band used for wireless power transmission, and inputs the AC frequency power to the power transmitting antenna 305 to generate electromagnetic waves for the RX to receive power. The frequency of the AC power generated by the power transmitting unit 303 is, for example, about several hundred kHz (e.g., 110 kHz to 205 kHz). Based on instructions from the control unit 301, the power transmitting unit 303 inputs the AC frequency power to the power transmitting antenna 305 so that the power transmitting antenna 305 outputs electromagnetic waves for transmitting power to the RX.

[0037] The power transmitting unit 303 also controls the intensity of the electromagnetic waves to be output by adjusting the voltage (transmission voltage) or current (transmission current), or both, input to the power transmitting antenna 305. Increasing the transmission voltage or transmission current increases the intensity of the electromagnetic waves, whereas decreasing the transmission voltage or transmission current decreases the intensity of the electromagnetic waves. Based on instructions from the control unit 301, the power transmitting unit 303 controls the output of AC frequency power so as to start or stop power transmission from the power transmitting antenna 305. Furthermore, the power transmitting unit 303 notifies the control unit 301 of the current transmission power, allowing the control unit 301 to know the transmission power at any given timing. Measurement of the transmission power and notification to the control unit 301 may be configured to be performed by a device other than the power transmitting unit 303. The power transmitting unit 303 is primarily an example of a power transmitting means that wirelessly transmits power to a power receiving device based on negotiation.

[0038] The detection unit 304 detects whether an object is placed on the TX based on the WPC standard. Specifically, the detection unit 304 detects whether an object is placed on the interface surface of the TX. For example, the detection unit 304 detects at least one of the voltage value and the current value of the power transmitting antenna 305 when the power transmitting unit 303 transmits an Analog Ping of the WPC standard via the power transmitting antenna 305.

[0039] The detection unit 304 may detect a change in impedance. The detection unit 304 may determine that an object is placed on the TX when the voltage falls below a predetermined voltage value or when the current value exceeds a predetermined current value. Whether the object is a power receiving device or another foreign object is determined based on whether or not a predetermined response is received in response to a Digital Ping subsequently transmitted by the communication unit 306. That is, if the TX receives the predetermined response, the object is determined to be a power receiving device; otherwise, the object is determined to be an object other than a power receiving device.

[0040] The communication unit 306 performs control communication with the RX based on the WPC standard as described above. The communication unit 306 modulates the electromagnetic waves output from the power transmitting antenna 305 and transmits information to the RX to perform communication. The communication unit 306 also demodulates the electromagnetic waves output from the power transmitting antenna 305 and modulated by the RX to acquire information transmitted by the RX. In other words, the communication performed by the communication unit 306 is superimposed on the electromagnetic waves transmitted from the power transmitting antenna 305.

[0041] The notification unit 307 notifies the user of information by any method such as visually, audibly, or tactilely. The notification unit 307 notifies the user of, for example, the charging state of the TX or information indicating the state of power transmission in the wireless power transmission system including the TX and the RX as shown in Fig. 1. The notification unit 307 includes, for example, a liquid crystal display, an LED, a speaker, a vibration generating circuit, and / or other notification devices.

[0042] The operation unit 308 has a reception function for receiving operations for TX from the user. The operation unit 308 includes, for example, a voice input device such as a button, a keyboard, or a microphone, a motion detection device such as an acceleration sensor or a gyro sensor, and / or other input devices. Note that a device in which the notification unit 307 and the operation unit 308 are integrated, such as a touch panel, may also be used.

[0043] The memory 309 stores various information such as identification information and capability information, control programs, etc. The capability information includes information indicating whether the device has a high-precision foreign object detection processing capability. The memory 309 may store information obtained by a functional unit other than the control unit 301.

[0044] The timer 310 measures time by, for example, a count-up timer that measures the elapsed time from the time of activation, or a count-down timer that counts down from a set time.

[0045] The NFC communication unit 311 is a hardware module that realizes the NFC function. Specifically, the NFC communication unit 311 realizes a card emulation mode that acts as a contactless IC card, a reader / writer mode for reading the NFC tag 801, and a P2P mode for directly exchanging messages between NFC devices. For example, the card emulation mode can be used to enable electronic money payments.

[0046] The communication unit 306 and the NFC communication unit 311 may be realized by a single piece of hardware, or may be realized by separate pieces of hardware.

[0047] <Basic Sequence of TX and RX> FIG. 4 is a sequence diagram showing an example of the flow of control by TX and RX in accordance with the WPC standard.

[0048] The TX transmits an Analog Ping (hereinafter referred to as an A-Ping) to detect an object present in the vicinity of the transmitting antenna 305 (F400). The A-Ping is a pulsed power used to detect an object. The A-Ping is such a small power that even if the RX receives the A-Ping, it cannot activate the control unit 301 of the RX. The TX detects an object by detecting a shift in the resonant frequency of the voltage value inside the transmitting antenna 305, which is caused by an object present in the vicinity of the transmitting antenna 305, or by detecting changes in the voltage value and / or current value flowing through the transmitting antenna 305.

[0049] When the TX detects an object by A-Ping, it measures the Q-factor of the transmitting antenna 305 (F401), although details will not be described. After completing the Q-factor measurement, the TX starts transmitting a Digital Ping (hereinafter referred to as a D-Ping) (F402). The D-Ping is power for activating the control unit 301 of the RX, and is greater in power than the A-Ping. The D-Ping is transmitted continuously thereafter. That is, the TX continues transmitting power equal to or greater than the D-Ping from the time it starts transmitting the D-Ping (F402) until it receives EPT (End Power Transfer) data from the RX requesting that power transmission be stopped (F416).

[0050] When the RX receives a D-Ping and starts up, it transmits to the TX a Signal Strength, which is data storing the voltage value of the received D-Ping (F403). The RX then transmits data storing an ID, including version information of the WPC standard to which the RX conforms and device identification information (F404). Furthermore, the RX transmits to the TX Configuration data, including information such as the maximum value of power that the power receiving unit 205 supplies to the load (or the charging unit 207) (F405). When the TX determines, by receiving the ID and Configuration data, that the RX supports the extended protocol (including Negotiation, described later) of the WPC standard v1.2 or later, it responds with an ACK (F406).

[0051] When the RX receives the ACK, it transitions to a Negotiation Phase where it negotiates the power to be transmitted and received. In the negotiation phase, the RX's control unit 201 and the program for realizing the negotiation are examples of negotiation means. Similarly, the TX's control unit 301 and the program for realizing the negotiation are examples of negotiation means. First, the RX transmits FOD (Foreign Object Detection) Status data to the TX (F407). In this embodiment, the FOD Status data is expressed as FOD(Q). The TX 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 RX indicating that it has determined that there is a high possibility that a foreign object is not present (F408).

[0052] When the RX receives the ACK, it transmits a General Request (Capabilities) (F409), which is data inquiring about the capabilities of the TX and is one of the General Requests defined in the WPC standard. Hereinafter, the General Request (Capabilities) is referred to as GRQ (CAP). When the TX receives the GRQ (CAP), it transmits Capability data (referred to as CAP) that stores information about the capabilities that the TX supports (F410).

[0053] Next, the RX transmits a General Request (ID) (referred to as GRQ(ID)), which is one of the General Requests defined in the WPC standard and is data requesting the TX to transmit identification information (F411). The identification information includes the supported standard version, etc. The TX transmits the identification information in response to the request from the RX (F412).

[0054] Next, GP negotiation is performed between the TX and the RX. That is, GP is a value that can be determined by agreement in the negotiation with the TX. The GP requested by the RX in the negotiation is power according to the power receiving capability of the RX, and can be set as the maximum value of the load power of the RX (power consumed by the charging unit 207), for example. This negotiation is realized by transmitting data that stores the GP value requested by the RX from the Specific Request data defined in the WPC standard to the TX (F413). In this embodiment, this data is expressed as SRQ(GP) (Specific Request(GP)).

[0055] The TX responds to the SRQ(GP) taking into consideration its own power transmission capacity, etc. If the TX determines that it can accept the GP, it sends an ACK indicating that the request has been accepted (F414), and if it determines that it cannot accept the GP, it sends a NAK indicating that the request has not been accepted. If a NAK is sent, the RX resends an SRQ(GP) with a changed requested GP value and checks for a response from the TX. The processes of F413 and F414 are repeated until the TX accepts the GP and returns an ACK. In this embodiment, it is assumed that the RX requests 100 watts as GP in the SRQ(GP).

[0056] Next, the RX transmits GRQ (ACAP) (F415), which is data inquiring about the TX's extended capabilities and is a General Request defined in the WPC standard. ACAP stands for Additional Capabilities. The ACAP contains additional information about the TX's capabilities. Details of the ACAP will be described later. Upon receiving the GRQ (ACAP), the TX transmits the ACAP containing the additional information it supports (F416).

[0057] When the negotiation of multiple parameters including the GP is completed, the RX transmits an SRQ (EN) of the Specific Request, which requests the end of the negotiation (End Negotiation), to the TX (F417). The TX transmits an ACK in response to the SRQ (EN) (F418) and ends the negotiation. Thereafter, the RX transitions to the power transmission phase, in which it transmits and receives power at the GP power determined in the Power Transfer Phase (power transmission phase) (F419).

[0058] After receiving the ACK, the RX connects the power receiving unit 205 to the load (charging unit 207) and supplies the received power to the load. With power being supplied to the load, the RX transmits a Control Error (hereinafter referred to as CE) packet to the TX according to the load. The CE packet will be referred to as CEP hereinafter. A code and a value are stored in the CEP. If the code of the value stored in the CEP is positive, it means that the receiving voltage is increased by that value. If the code of the value stored in the CEP is negative, it means that the receiving voltage is decreased by that value. If the value is zero (CE(0)), it means that the receiving voltage is requested to be maintained. Controlling the receiving voltage is equivalent to controlling the receiving power. Here, the RX transmits, for example, CE(+) to the TX, indicating that the receiving voltage should be increased (F420).

[0059] When the TX receives CE(+), it changes the setting value of the power transmission circuit in the power transmission unit 303 to increase the transmission voltage (transmission power). When the RX confirms that the received power has increased in response to CE(+) (F421), it supplies the received power to a load (e.g., the charging unit 207) and transmits a Received Power Packet (RPP) to the TX (F422). Here, the RPP stores the received power value in the state in which the RX supplies the output of the power receiving unit 205 to the load. After receiving and confirming the RPP, the TX transmits an ACK to the RX (F423). The processes from F420 to F423 are repeatedly executed during the power transmission phase.

[0060] Furthermore, for example, in parallel with the processing of F420 to F423, the TX performs processing including NFC tag detection in F424 and F425 (for example, F709 to F725 in FIG. 12, which will be described later). Processing including NFC tag detection specifically means processing related to adjusting (for example, suppressing) the transmission power by the TX, including NFC tag detection. As shown in FIG. 13, it is assumed that an NFC tag 801 is inserted between the TX and the RX, and F424 and F425 are processing to detect it.

[0061] Specifically, the TX measures a predetermined time to periodically execute NFC tag detection (F424). The predetermined time is a time set by an NFC timer (described later) and is an example of an execution standby time. The predetermined time is, for example, 50 ms, but is not limited to this. After the predetermined time has elapsed, the TX executes NFC tag detection processing (F425). By repeating NFC tag detection every predetermined time, the TX can detect the appearance of an NFC tag during the power transmission phase.

[0062] In this disclosure, "after a certain amount of time has passed" does not literally mean immediately after the time has passed, but rather means "any time after the time has passed." For example, "processing after a certain amount of time has passed" is not limited to processing immediately after the time has passed, but may include other processing between the processing immediately after the time has passed and the target processing. This is not limited to "after a certain amount of time has passed," but also applies to "after" such as "after exceeding a threshold value."

[0063] When an NFC tag is detected, the TX controls the transmission power to a predetermined value, taking into consideration the possibility that the NFC tag may be damaged by electromagnetic waves during power transmission. The predetermined value is a value calculated depending on the situation and can take multiple values ​​depending on the situation. The predetermined value can be 0 W, meaning that power transmission can be stopped. "Depending on the situation" means, for example, that if the NFC tag information contains information about the power allowed by the NFC tag, the TX controls the transmission power to be equal to or lower than that allowed power. Alternatively, "depending on the situation" means, for example, that if the NFC tag information does not contain information indicating that power transmission is allowed, the TX sets the transmission power to, for example, the minimum value or stops power transmission.

[0064] It should be noted that the above-described process of adjusting the transmission power including detecting an NFC tag is different from the process of controlling the transmission power to a predetermined value when an NFC tag is detected. Details will be described later.

[0065] The control unit 301, the NFC communication unit 311, the program for realizing NFC tag detection, the program for communicating with the RX during power transmission, etc. are examples of processing means for executing processes including NFC tag detection. Also, the control unit 301, the communication unit 306, the program for communicating with the RX during negotiation and power transmission, etc. are examples of communication means in the power transmitting device. Similarly, the control unit 201, the WPC communication unit 203, the program for communicating with the TX, etc. are examples of communication means in the power receiving device.

[0066] When charging of the battery 208 is completed, the RX transmits EPT (End Power Transfer) data to the TX requesting that the TX stop transmitting power (F426).

[0067] The above is the flow of TX and RX control that complies with the WPC standard, and is the basic sequence of TX and RX processing in wireless power transmission.

[0068] From here, we will mainly explain the processing when an NFC tag 801 gets stuck between TX and RX as shown in Fig. 13 during the high-power power transmission phase. Even in such a case, according to this embodiment, power can be transmitted at an appropriate power level, and NFC tag detection can be performed reliably. This will be explained with reference to Figs. 5 to 12. Figs. 5 to 8 are flowcharts showing RX processing. Figs. 9 to 11 are flowcharts showing TX processing. Fig. 12 is a sequence diagram showing TX and RX processing.

[0069] In this embodiment, the TX and RX exchange various information in a negotiation phase before the power transmission phase in order to suppress (reduce) the transmission power when detecting an NFC tag in the high-power power transmission phase. In the power transmission phase, the TX uses the information to adjust (e.g., suppress) the transmission power during periodic NFC tag detection, while the RX adjusts the TX's transmission power accordingly. Cooperation between the TX and RX aims to achieve both high-power power transmission and NFC tag detection.

[0070] <Processing by the Power Receiving Device> FIGS. 5 to 8 are flowcharts showing an example of processing performed by the RX. FIG. 5 is a flowchart showing processing in the negotiation phase, and FIGS. 6, 7, and 8 are flowcharts showing processing in the power transmission phase. This processing can be realized, for example, by the control unit 201 of the RX executing a program read from the memory 211. At least a part of the following procedure can be realized by hardware. In this case, the hardware can be realized, for example, by 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 processing can also be executed in response to the RX being powered on, or in response to the RX being started by power supplied from the battery 208 or the TX, or in response to the user of the RX inputting a command to start the contactless charging application. This processing can also be started in response to other triggers.

[0071] In S5001, the RX executes basic command processing in the negotiation phase. This assumes the processing from F407 to F414 in the sequence diagram described above. In S5002, the RX transmits a GRQ (ACAP) message. The transmission of various messages from the RX to the TX is realized by the control unit 201 transmitting messages to the WPC communication unit 203.

[0072] In S5003, RX waits for an ACAP message from TX. Reception of the message sent from TX by RX is realized by the control unit 201 polling the WPC communication unit 203. After checking the message, RX holds the received information in S5004.

[0073] In this embodiment, the message transmitted from the TX may have the content and format shown in Fig. 20(A). The RX can receive information from the TX about B0 "power suppression threshold (e.g., 80 W)", B1 "inquiry time", B2 "power at power suppression", and B3 "power suppression time".

[0074] The "power transmission restriction threshold" is a threshold of the power transmission amount that triggers the start of power transmission restriction.

[0075] "Inquiry time" is the time until an inquiry is made to the TX in the process including NFC tag detection in the power transmission phase (F709 to F724 in FIG. 12, which will be described later). In this case, the inquiry means a request by the RX that the TX transmit predetermined information to the RX. The predetermined information includes, for example, the time until the TX actually performs NFC tag detection. The predetermined information also includes the above-mentioned B2 "power when power transmission is suppressed" and B3 "time for power transmission suppression."

[0076] As will be described later, the timing at which the inquiry time starts (the above transmission request is executed) is after the RX receives and confirms "power transmission suppression ON / OFF switching information" (here, from OFF to ON) from the TX. The RX needs to know the timing at which to perform NFC tag detection in order to prepare for power transmission suppression when the TX detects an NFC tag. Preparation for power transmission suppression mainly involves adjusting the processing load on the RX side, as will be described later. In this embodiment, it is assumed that the RX performs transmission processing of a CE (CEP) or an RPP. Therefore, as will be described later, the RX performs an inquiry when a timer based on the inquiry time is started and when the RX transmits a CEP or RPP that is executed after the timer is fired. The inquiry time is, for example, 30 ms, but is not limited to this. The "inquiry time" is an example of an inquiry standby time.

[0077] "Power during power transmission suppression" is the power transmission during the period when the power transmission is suppressed ("time of power transmission suppression"). The power during power transmission suppression can take a value equal to or less than the "power transmission threshold", for example, 40 W. As will be described later in [Other embodiments], stopping power transmission (i.e., 0 W) is also included in "power transmission suppression". The information on "power during power transmission suppression" is an example of adjustment power information.

[0078] The "power transmission suppression time" is the time for which the power transmission suppression state continues. The information on the "power transmission suppression time" is an example of duration information.

[0079] In S5005, the RX transmits an SRQ / EN to end the negotiation phase. In S5006, the RX waits for an ACK, and after confirming the ACK, ends the negotiation phase and proceeds to the power transmission phase from S5101 onwards.

[0080] 6, in S5101, the RX checks whether command processing is to be performed, and if command processing is to be performed, the process proceeds to S5102. If command processing is not to be performed, other processing is performed in S5117 and the process returns to S5101. A command mainly means a request sent from the RX side to the TX side. For example, if the answer is YES in S5101, the command may be CEP or RPP.

[0081] In S5102, the RX checks whether the power transmission suppression when detecting an NFC tag is currently ON or OFF. The process of returning from S5103 to S5101 via YES in S5108 is a process in which the power transmission suppression is OFF and the transmission power does not exceed the "power transmission suppression threshold" (e.g., 80 W).

[0082] In S5103, the RX determines whether to transmit a CE (CEP). If a CE is to be transmitted, the RX transmits the CE to the TX in S5104. If a CE is not to be transmitted, the RX executes other command processing in S5116. Note that the request for control of the transmission power to the CE, i.e., the TX, is executed regardless of whether the transmission power suppression is ON or OFF (S5104, S5121 described below).

[0083] In S5105, the RX checks the transmission power by the TX for the transmitted CE (F421). After checking the (change in) transmission power, the RX sends an RPP (Received Power Packet) to the TX in S5106 (F421). In S5107, the RX waits for a response to the RPP from the TX, and upon receiving a response, checks the type of response in S5108. If the response is an ACK in S5108 (F423), the RX returns to S5101. If the response is an ATN (ATTENTION) (YES in S5109), the RX sends a DSR (Data Stream Response) / poll to the TX in S5110. The ATN is a response indicating that the TX wants to send additional information to the RX.

[0084] In S5111, the RX waits for a response to DSR / poll, and checks the response content in S5112. If the response content is "power transmission suppression ON / OFF switching information" when an NFC tag is detected, the RX checks the content of the switching information in S5113 and returns to the processing of S5101.

[0085] The transmission power suppression ON / OFF switching information is information indicating whether to start or cancel transmission suppression when detecting an NFC tag under power transmission in the power transmission phase. Specifically, the transmission power suppression ON / OFF switching information is information indicating "switching from OFF to ON" to start power transmission suppression, and information indicating "switching from ON to OFF" to cancel it. When YES is returned in S5112, information indicating "switching from OFF to ON" is received. Here, since the current process is a process that goes through NO in S5102, YES in S5112 means "switching from OFF to ON" and that the transmission power has exceeded a threshold value (e.g., 80 W).

[0086] In the following description, "switching from OFF to ON" in the process of suppressing power transmission will be expressed as "OFF → ON," and "switching from ON to OFF" will be expressed as "ON → OFF." In the following description, "power transmission suppression ON / OFF switching information" may also be abbreviated as "switching information."

[0087] Conversely, if the response is not "switching information" (NO in S5112), the RX executes processing corresponding to the contents of the response received in S5112 in S5114 and returns to S5101. Also, if the response received in S5107 is neither an ACK nor an ATN (NO in S5108 and S5109), the RX executes processing corresponding to the contents of the response received in S5112 in S5115 and returns to S5101.

[0088] Next, the processing when power transmission suppression when an NFC tag is detected is ON in S5102 will be described with reference to Fig. 7. In S5118, the RX determines whether or not to transmit CE (CEP). If CE is to be transmitted, the RX starts a timer in S5119. If CE is not to be transmitted, the RX executes other command processing in S5135 and returns to S5101.

[0089] In S5119, the RX sets a timer to the "inquiry time" acquired from the TX in S5002 to S5004. Hereinafter, for convenience of explanation, this timer will be referred to as the "inquiry timer." The timer is started by the control unit 201 operating the timer 212. In S5120, the RX checks whether the inquiry timer has fired, that is, whether the set time has elapsed (or whether the current time has reached the set time). The control unit 201 checks whether the inquiry timer has fired by polling the timer 212. When the RX checks whether the inquiry timer has fired, it transmits a CE in S5121 and checks the transmission power in S5122. These processes are the same as the processes in S5104 and S5105.

[0090] In S5121, since the transmission power exceeds a threshold (e.g., 80 W), it is preferable to transmit CE(-) to reduce the transmission power in S5121. However, this is not necessarily the case, and CE(-) may also be transmitted. This is because even if CE(+) or CE(0) is transmitted, the TX can simply ignore the request and perform transmission suppression (S6120 described below).

[0091] In S5123, the RX transmits an RPP and waits for an ATN in S5124. In the processing when power transmission suppression is ON when an NFC tag is detected (processing from S5118 onward), it is assumed that the TX will transmit an ATN in response to the RPP (S6111, described later). After receiving the ATN, the RX transmits a DSR / poll to the TX in S5125.

[0092] In S5126, the RX waits for a response to DSR / poll, and checks the response content in S5127 as shown in FIG. 8. As described above, if the transmission power exceeds the threshold (NO in S6110, described later) and the response content is not switching information (NO in S5127), the received response content means that the RX has acquired the time until NFC tag detection. In other words, in S6114, described later, the TX transmits time information until NFC tag detection, and the RX receives this. In this case, the RX checks the response information in S5128 and starts a timer in S5129. In S5129, a time corresponding to the time until NFC tag detection acquired in S5128 is set.

[0093] In S5130, the RX checks whether the timer has fired. After the timer has fired, in S5131, the RX adjusts the processing load within the RX. Adjusting the processing load here means controlling the processing load of the RX so that the RX can operate within the range of the "power during power transmission suppression" acquired from the TX in S5002-S5004. Specific examples of adjusting the processing load include the following: Stopping software with a high processing load among those being processed by the control unit 201 for the "power transmission suppression time" acquired from the TX in S5004. Alternatively, the clock of the control unit 201 may be set to a low value for the "power transmission suppression time" of the processing load. The control unit 201 and the program for adjusting the processing load are primarily examples of adjustment means for adjusting the processing load of the power receiving device.

[0094] Then, in S5132, the RX waits for the transmission power to be restored. This is achieved by the control unit 201 polling the power receiving unit 205. When the transmission power is restored, in S5133 the RX releases the processing load control implemented in S5131 and returns to S5101. Also, if the content of the response in S5126 is "transmission power suppression ON / OFF switching information" (YES in S5127), the RX checks the content of the switching information in S5134 and returns to S5101. The switching information here is information indicating that the transmission power suppression control has changed from "ON to OFF" when detecting an NFC tag during power transmission. In other words, this means that the transmission power has fallen below a threshold value (e.g., 80 W).

[0095] As described above, the RX can respond to the power transmission suppression that switches in accordance with changes in the transmission power when an NFC tag is detected, while communicating with the TX.

[0096] <Processing by Power Transmission Device> Figures 9 to 11 are flowcharts showing an example of processing executed by the TX. Figure 9 is a flowchart showing processing in the negotiation phase, and Figures 10 and 11 are flowcharts showing processing in the transfer phase. This processing can be realized, for example, by the control unit 301 of the TX executing a program read from the memory 309. Note that at least a part of the following procedure may be realized by hardware. In this case, the hardware can be realized, for example, by using a predetermined compiler to automatically generate a dedicated circuit using a gate array circuit such as an FPGA from a program for realizing each processing step. Furthermore, this processing can be executed in response to the power supply of the TX being turned on. Furthermore, this processing may be started by some other trigger.

[0097] In S6001, the TX waits to receive a request. Reception of a request by the TX can be achieved by the control unit 301 polling the communication unit 306. The TX waits in S6001 until a request arrives. When the TX receives a request, it performs processing according to the request in S6002 and subsequent steps.

[0098] The TX checks whether the request received in S6001 is a GRQ (ACAP). This corresponds to the transmission of a GRQ (ACAP) by the RX in S5002. If it is a GRQ (ACAP), the TX transmits the ACAP in S6003. This is the information received by the RX in S5004, and as described above, is B0 "threshold for transmission suppression (e.g., 80 W)" / B1 "inquiry time" / B2 "power at transmission suppression" / B3 "time for transmission suppression" shown in FIG. 20A. The transmission from the TX in S6003 is realized by the control unit 301 writing a message to the communication unit 306. After the ACAP is transmitted, the process returns to S6001.

[0099] If the request received in S6002 is not GRQ (ACAP), then in S6004 the TX checks whether the request received in S6001 is SRQ / EN. If it is SRQ / EN, then in S6005 the TX sends an ACK, ends the negotiation phase, and proceeds to processing in the power transmission phase from S6101. If it is not SRC / EN, then in S6006 the TX performs processing corresponding to the received command and returns to S6001. S6006 corresponds to the processing of 5001 by the RX, and corresponds to the processing from F407 to F414 in the sequence diagram described above.

[0100] 10 , in S6101, the TX checks whether a request from the RX has been received. If the request is from the CE, the TX proceeds to S6103 and controls the transmission power in accordance with the request from the CE from the RX. The control of the transmission power is realized by the control unit 301 controlling the power transmission unit 303.

[0101] In S6104, the TX waits for an RPP. After confirming that an RPP has been received, the TX checks the contents of the RPP in S6105 and ascertains the received power on the RX side. In S6106, the TX determines whether or not it is necessary to switch ON / OFF ("OFF → ON" or "ON → OFF") the power transmission suppression when an NFC tag is detected. The TX makes the determination in S6106 by checking its own transmission power. The control unit 301 checks the power transmission unit 303, so that the transmission power from the TX at that time can be confirmed.

[0102] The control unit 301 changes "OFF → ON" when the value of the transmission power exceeds a threshold (e.g., 80 W), and conversely, changes "ON → OFF" when it falls below the threshold. After transmitting ATN in S6107, the TX waits for a DSR / poll from the RX in S6108. After confirming reception of the DSR / poll, the TX transmits transmission power suppression ON / OFF switching information to the RX in S6109, and returns to S6101. The switching information transmitted in S6109 can be confirmed by the RX in S5113 and S5134.

[0103] If switching of the power transmission suppression is not necessary in S6106, the TX checks in S6110 whether the transmission power is equal to or less than a threshold value (e.g., 80 W). If the transmission power is equal to or less than the threshold value, this means that the power transmission suppression is OFF and the TX is in the normal power transmission phase, and so the TX transmits an ACK in S6111 and then returns to S6101.

[0104] Conversely, if the transmission power exceeds the threshold in S6110, the TX transmits an ATN in S6112 to transmit switching information to the RX, and waits for a DSR / poll from the RX in S6113. After confirming receipt of the DSR / poll, the TX transmits the time until NFC tag detection in S6114 and returns to S6101. The time until NFC tag detection information transmitted in S6114 is information confirmed by the RX in S5128, and is information regarding the execution standby time described above. This means the remaining time of the set time (execution standby time, for example, 50 ms) of the NFC timer activated in S6126 or S6128, which will be described later. This remaining time of the set time of the NFC timer is an example of the remaining execution time. The remaining time of the NFC timer is confirmed by the control unit 301 by checking the remaining time of the corresponding timer in the timer 310.

[0105] If it is not CE in S6102, the TX executes other command processing in S6115 and returns to S6101.

[0106] If the TX has not received a request from the RX in S6101, it refers to Fig. 11 and determines whether or not to perform NFC processing (NFC tag detection processing) in S6116. If it is NFC processing, the TX checks whether the NFC timer is running in S6117, and if it is not NFC processing, it executes other processing in S6127 and returns to S6101. The timer in S6117 is the NFC timer (e.g., 50 ms) for the periodic NFC tag detection described above, and is realized by the control unit 301 checking the timer 310, as described above.

[0107] If the NFC timer is running in S6117, the TX checks in S6118 whether the NFC timer has fired, and if the NFC timer has not fired, the TX starts the NFC timer in S6128 and then returns to S6101. The control unit 301 starts the NFC timer by setting a time in the timer 310. The control unit 301 checks the corresponding timer in the timer 310 to confirm whether the NFC timer has fired. If the NFC timer has not fired in S6118, the TX returns to S6101. If the NFC timer has fired, the TX subsequently performs power transmission suppression and NFC tag detection.

[0108] First, in S6119, the TX checks whether the transmission power exceeds the threshold. If the transmission power exceeds the threshold, the TX suppresses power transmission in S6120, and then detects an NFC tag in S6121. If the transmission power is equal to or less than the threshold, the TX proceeds directly to S6121. The power in the processing of S6120 is the "power during power transmission suppression" in FIG. 20A. The NFC tag detection processing of S6121 is realized by the control unit 301 controlling the NFC communication unit 311.

[0109] In S6122, the TX checks whether or not power transmission suppression is currently being performed, and if power transmission suppression is being performed, the TX restores the transmission power in S6123 and then proceeds to S6124. If power transmission suppression is not being performed, the TX proceeds directly to S6124 and determines whether or not an NFC tag has been detected.

[0110] When an NFC tag is detected, various countermeasures that the TX can take are conceivable, but in this embodiment, the TX reduces the transmission power to a level that does not affect the NFC tag in S6125, and then returns to S6101. If an NFC tag is not detected in S6124, the TX starts an NFC timer in S6126 to detect the next NFC tag, and then returns to S6101.

[0111] In S6120, the TX suppresses power transmission, thereby suppressing the generation of noise that affects communication when detecting an NFC tag, and enabling appropriate NFC tag detection processing. Meanwhile, in S6125, the TX, for example, controls the transmission power to a predetermined value, thereby suppressing damage caused by electromagnetic waves to the NFC tag detected in S6124. The predetermined value is a value calculated depending on the situation and can take multiple values ​​depending on the situation. "Control to a predetermined value" is as described above. In this way, the power transmission suppression in S6120 is performed to appropriately detect the NFC tag, and the control of the transmission power in S6125 is performed after the NFC tag is detected to suppress damage to the NFC tag. Thus, the two processes have different purposes and execution timings.

[0112] As described above, the TX communicates with the RX, and can execute the processing of the power transmission phase while switching ON / OFF the power transmission suppression when an NFC tag is detected in accordance with changes in the transmission power.

[0113] <TX and RX Sequences During High-Power Power Transmission> FIG. 12 is a sequence diagram showing an example in which, from the normal Power Transfer Phase sequence in FIG. 4, the transmission power exceeds a threshold (e.g., 80 W) and NFC tag detection is performed while suppressing power transmission.

[0114] The RX transmits, for example, CE(+) (F701). The TX that receives the CE(+) controls the transmission power in accordance with the request of the RX (F702). The TX confirms that the transmission power threshold has been exceeded by controlling the transmission power (F703, YES in S6106, YES in S5102). Furthermore, when the RX confirms that the received power has increased in response to the CE(+) (F704), it transmits an RPP to the TX (F705). The RPP stores the received power value when the RX supplies the output of the power receiving unit 205 to the load (charging unit 207).

[0115] The TX, having confirmed the RPP, transmits an ATN to the RX (F706). The RX, having received the ATN, transmits a DSR / poll to the TX (F707). The TX, having received the DSR / poll, transmits information that power transmission suppression is ON to the RX (F708, ON in S6109). This allows both the TX and RX to understand that power transmission suppression will be performed when an NFC tag is detected.

[0116] In F708 (S6109), information on the power transmission suppression "OFF → ON" is transmitted to the RX, and when the RX receives this information (YES in S5112), it starts processing including NFC tag detection in the power transmission suppression ON state (F709 to F724). In the processing including NFC tag detection, as described below, the TX starts an NFC timer until the detection is performed as a preliminary step to actually detecting the NFC tag (F709, S6128). When the RX receives the information on "OFF → ON", it starts an inquiry timer for the "inquiry time" (ACAP information in F416) (F710, S5119).

[0117] The RX transmits a CE (F712, S5121) in response to the firing of the inquiry timer (F711, S5120). The TX controls the transmission power in accordance with the CE (F713, S6103). When the RX confirms that the received power has changed in response to the CE (F714, S5121), it transmits an RPP to the TX (F715, S5123). The RPP stores the received power value in the state in which the RX supplies the output of the power receiving unit 205 to the load (charging unit 207).

[0118] Here, it is assumed that the power transmission suppression ON state continues, i.e., the transmission power exceeds the threshold (NO in S6106, NO in S6110). The TX that confirmed the RPP transmits an ATN to the RX (F716, S6112). The RX that received the ATN (YES in S5124) transmits a DSR / poll to the TX (F717, S5125). The TX that received the DSR / poll (YES in S6113) sets time information (remaining execution time) until NFC tag detection and transmits this to the RX (F718, S6114). The RX that received the time until NFC tag detection (YES in S5126) starts a timer and sets the time (F719, NO in S5127, S5128).

[0119] When the timer for detecting an NFC tag on the RX side fires (F720, YES in S5130), the RX adjusts the processing load (F721, S5131). On the other hand, when the NFC timer on the TX side fires (F722, YES in S6118), the TX suppresses the transmission power (F723, S6120). The TX then executes an NFC tag detection process (F724, S6121) and restores the transmission power (F725, S6123). After confirming that the transmission power has been restored (YES in S5132), the RX cancels the adjustment of the processing load (F716, S5133). The processes from F709 to F724 are repeated as long as the transmission power exceeds the threshold.

[0120] Frequency noise occurs in wireless power transmission. For example, as the power output increases, the frequency band of the generated noise becomes wider and the noise intensity increases. As the power output increases, noise may occur that interferes with the communication frequency (e.g., 13.56 MHz) during NFC tag detection, which may be performed during power transmission. Therefore, if no countermeasures are taken, NFC tag detection may not be performed properly. However, according to this embodiment, in the negotiation phase, the TX transmits the "power suppression threshold," "inquiry time," "power at power suppression," and "power suppression time" to the RX via ACAP. Then, while the TX checks the transmission power during the power transmission phase, if it exceeds the threshold, the RX suppresses the transmission power during the NFC tag detection process during the power transmission phase. This allows the TX to reliably perform NFC tag detection during the power transmission phase. Therefore, even in situations where high transmission power generates noise that affects NFC tag detection communication, the NFC tag detection process can be performed appropriately and reliably. That is, in this embodiment, it is possible to achieve both high-power wireless power transmission and NFC tag detection during wireless power transmission.

[0121] In this embodiment, command processing using CEP / RPP is used. However, RPP may be used instead of CEP for communication in the NFC tag detection process in the power transmission phase (communication after F710). This can improve the efficiency of the process. It is also possible to define dedicated messages related to NFC tag detection in the power transmission phase.

[0122] Second Embodiment Next, as in the first embodiment, a second embodiment will be described, mainly regarding the processing performed when an NFC tag 801 is caught between the TX and RX as shown in FIG. 13 during the high-power power transmission phase. In this embodiment, the TX and RX communicate with each other during the power transmission phase using information communicated during the negotiation phase, while also communicating with each other regarding the power and suppression time during power transmission suppression for each NFC tag detection process. This allows for flexible power transmission suppression. In this embodiment, descriptions of elements and functions similar to those in the first embodiment will be omitted.

[0123] <Processing by the Power Receiving Device> In the negotiation phase, the RX executes the same processes as S5001 to S5006 shown in Fig. 5. However, in this embodiment, the message acquired by the ACAP from the TX in S5002 to S5004 may have the content and format shown in Fig. 20(B). That is, the RX acquires B0 "power suppression threshold (e.g., 80 W)" / B1 "inquiry time."

[0124] 14 is a flowchart showing the processing executed by the RX in the power transmission phase. This processing can be realized, for example, by the control unit 201 of the RX executing a program read from the memory 211. In the power transmission phase, the RX executes the same processing as S5101 to S5130, S5134, and S5135 shown in FIG.

[0125] The processing from S5130 onwards when YES is determined is the processing from S9131 onwards. The timing of S5130 is the timing when the timer measures the time from TX to NFC tag detection after the transmission power exceeds the threshold (S5128 via YES in S6114 to S5126) and the time is measured. This is the same as in the first embodiment.

[0126] In this embodiment, in S9131, the RX performs CEP / RPP processing again. The processing from S9131 to S9136 is the same as the processing from S5121 to S5126. The information that the RX receives from the TX in S9136 is information on "power when power transmission is suppressed" / "time for power transmission suppression" when performing the current NFC tag detection processing. Based on the received information, the RX performs processing related to the processing load in the same way as in S5131 to S5133 and thereafter.

[0127] As described above, the RX can respond to the power transmission suppression during the NFC tag detection process, which is switched in accordance with changes in the transmission power, while communicating with the TX.

[0128] <Processing by Power Transmitting Device> In the negotiation phase, the TX performs the same processes as S6001 to S6006 in Fig. 9. However, in this embodiment, the data transmitted to the RX by ACAP in S6002 and S6003 is the information shown in Fig. 20(B), which is the value of "power transmission suppression threshold" / "inquiry time".

[0129] 15A and 15B are flowcharts showing the processing executed by the TX in the power transmission phase. This processing can be realized, for example, by the control unit 301 of the TX executing a program read from the memory 309.

[0130] As shown in Fig. 15A, in the power transmission phase, the TX performs the same processes as YES in S6101 to S6113 and S6115 in Fig. 10. The timing of S6113 is the timing when the TX receives a DSR / poll from the RX after transmitting an ATN in response to an RPP command received by the RX in a state where the transmission power exceeds the threshold.

[0131] After YES in S6113, in S1514, the TX checks whether the "time until NFC tag detection" has been transmitted to the RX. In this embodiment, it is assumed that two communications (two CEP / RPP processes) are performed when detecting an NFC tag. Therefore, in S1514, the TX checks whether the transmission of the "time until NFC tag detection" has been completed as the first communication.

[0132] If the "time until NFC tag detection" has not yet been transmitted, the TX transmits the "time until NFC tag detection" as the first communication in S1515. This is the same as the processing in S6114. On the other hand, if the "time until NFC tag detection" has already been transmitted, the TX transmits the transmission power and suppression time during power transmission suppression as the second communication in S1516, and returns to S6101. The information transmitted in S1516 is received by the RX in S9137.

[0133] As shown in FIG. 15(B), the TX performs the same processing as NO in S6101, S6116 to S6118, and S6119. In S1522, the TX checks whether the transmission power and suppression time at the time of suppression have been transmitted. This means checking whether the transmission power and suppression time at the time of suppression have been transmitted to the RX in S1516 in order to perform transmission suppression in the subsequent processing. If this information has been transmitted, the TX performs the same processing as S6120 to S6126. If this information has not been transmitted, the TX returns to S6101, and after the processing of S1516, returns to S1522 again. Note that the TX performs the same processing as these for S6127 and S6128 in FIG. 11.

[0134] As described above, the TX communicates with the RX, and can execute the processing of the power transmission phase while switching ON / OFF the power transmission suppression when an NFC tag is detected in accordance with changes in the transmission power.

[0135] <TX and RX Sequences During High-Power Power Transmission> Fig. 16 is a sequence diagram showing TX and RX processing. Similar to Fig. 12 , Fig. 16 illustrates processing from the normal Power Transfer Phase sequence in Fig. 4 to perform NFC tag detection while suppressing power transmission when the transmitted power exceeds a threshold value (e.g., 80 W).

[0136] The processing from F1101 to F1120 is the same as the processing from F701 to F720. The processing from F1121 to F1126 (from CE transmission to DSR / poll transmission) is the same as the processing from F1112 to F1117.

[0137] Upon receiving DSR / poll, the TX transmits information about the transmission power during suppression and the suppression time to the RX in F1127. This corresponds to the processing in S1516. The processing from F1128 to F1133 is the same as the processing from F721 to F726. The processing from F1109 to F1133 is repeated as long as the transmission power exceeds the threshold.

[0138] As described above, according to this embodiment, in the negotiation phase, the TX transmits the “power transmission suppression threshold” / “inquiry time” to the RX via ACAP. Then, while the TX checks the transmission power during the power transmission phase, if the power exceeds the threshold, it transmits the “power transmission suppression threshold” / “inquiry time” for each NFC tag detection process during the power transmission phase. That is, in the first embodiment, the “power at power transmission suppression” / “power transmission suppression time” were transmitted during the negotiation phase. However, in this embodiment, these pieces of information are transmitted dynamically (each time an NFC tag detection process is attempted) even during the power transmission phase. The RX can then reliably perform NFC tag detection during the power transmission phase by responding to the suppression of transmission power performed by the TX. Therefore, even in a situation where high transmission power generates noise that affects NFC tag detection communication, it is possible to perform NFC tag detection appropriately and reliably. That is, in this embodiment, it is possible to achieve both high-power wireless power transmission and NFC tag detection during wireless power transmission.

[0139] [Third Embodiment] Next, as in the first and second embodiments, a third embodiment will be described, which mainly deals with the processing performed when an NFC tag 801 is interposed between the TX and the RX as shown in FIG. 13 during a high-power power transmission phase. In this embodiment, when the NFC detection processing is performed with power transmission suppression ON, the TX itself transmits information regarding power transmission suppression (TX state notification information, described later) to the RX, regardless of an inquiry from the RX, to suppress power transmission. This allows for more flexible power transmission suppression. In this embodiment, descriptions of elements and functions similar to those of the first and second embodiments will be omitted.

[0140] <Processing by the Power Receiving Device> In the negotiation phase, the RX executes the same processes as S5001 to S5006 shown in Fig. 5. However, in this embodiment, the message acquired by the ACAP from the TX in S5002 to S5004 may have the content and format shown in Fig. 20(C). That is, the RX acquires B0 "power suppression threshold (e.g., 80 W)."

[0141] 17 is a flowchart showing a process executed by the RX in the power transmission phase. This process can be realized by, for example, the control unit 201 of the RX executing a program read from the memory 211.

[0142] As in the processing in Fig. 6, in S5101, the RX determines whether or not the processing is a command. If it is a command processing, in S1702 it determines whether or not the command processing is a transmission processing, and if it is a transmission processing, the process proceeds to S5103 (Fig. 6). As shown in Fig. 6, the RX executes the processing in S5103 to S5116, and also executes the processing in S5117 if the answer is NO in S5101.

[0143] If it is not a command transmission process in S1702, the RX performs a command reception process in S1718. In this embodiment, it is assumed that a command will also be issued from the TX, so the RX also performs a reception process for the command issued by the TX. The command reception process in the RX is realized by the control unit 201 polling the WPC communication unit 203. In S1718, the RX checks whether the command received from the TX is a TX status notification command. If it is not a TX status notification command, the RX executes the corresponding command processing in S1725 and returns to S1701.

[0144] If the command received in S1718 is a TX status notification, the RX checks the contents of the command in S1719. The TX status notification allows the RX to understand the current status of the TX. Fig. 21 is a diagram showing an example of the contents and format of a TX status notification command. The TX status notification command includes information on the status of the TX, as well as B1 "power when transmission is suppressed" and B2 "time for transmission suppression".

[0145] In S1720, the RX transmits an ACK to the TX. In S1721, the RX determines whether or not power transmission suppression during NFC tag detection processing is ON. If it is ON, in S5131, the RX adjusts the processing load of the RX using the information on "power during power transmission suppression" / "time of power transmission suppression" in the TX status notification command received in S1718, as in the first and second embodiments. Thereafter, the RX executes the processes of S5132 and S5133 in FIG. 6.

[0146] <Processing by Power Transmission Device> In the negotiation phase, the TX performs the same processing as S6001 to S6006 in Fig. 9. However, in this embodiment, the data that the TX transmits in S6002 and S6003 via ACAP is the information shown in Fig. 20(C), which is B0 "power transmission suppression threshold."

[0147] 18 is a flowchart showing an example of processing executed by the TX in the power transmission phase. This processing can be realized, for example, by the control unit 301 of the TX executing a program read from the memory 309.

[0148] In the power transmission phase, the TX performs the same processes as those from YES in S6101 to S6119 in FIG. 10, and also performs the same processes as those from YES in S6101 to S6114 and S6115.

[0149] After S6118, if the transmission power exceeds a threshold (e.g., 80 W) in S6119, the TX needs to suppress power transmission because it needs to detect NFC tags under conditions where the transmission power exceeds the threshold. For this reason, in this embodiment, it is assumed that the TX sends a command to the RX. In S1820, the TX prepares information on "power when transmission is suppressed" and "time for transmission suppression," and in S1821 sends this information to the RX as a TX status notification command (FIG. 21).

[0150] In S1822, TX waits for an ACK from RX, and then executes the processes of S6120 to S6126 in FIG.

[0151] <TX and RX Sequences During High-Power Power Transmission> Fig. 19 is a sequence diagram showing TX and RX processing. Similar to Fig. 12 and Fig. 16, Fig. 19 illustrates processing from the normal Power Transfer Phase sequence in Fig. 4 in which the transmitted power exceeds a threshold (e.g., 80 W) and NFC tag detection is performed while suppressing power transmission.

[0152] The processing from F1401 to F1409 is the same as the processing from F701 to F709. After that, the TX checks whether the NFC timer started in F1409 has fired (F1410). When the NFC timer has fired, the TX transmits a TX state notification command to the RX (F1411), and the RX returns an ACK (F1412).

[0153] The RX adjusts the processing load in accordance with the information on "power during power transmission suppression" / "power transmission suppression time" received in F1411 (F1413). The processing from F1414 to F1417 is the same as the processing from F723 to F726. The processing from F1409 to F1417 is repeated as long as the transmission power exceeds the threshold.

[0154] As described above, according to this embodiment, in the negotiation phase, the TX transmits the "power suppression threshold" to the RX via ACAP. Then, while checking the transmission power during the power transmission phase, the TX transmits the "power suppression threshold" / "inquiry time" for each NFC tag detection process during the power transmission phase if the power exceeds the threshold. Unlike the first and second embodiments, in this embodiment, the RX does not request control of the transmission power (CE) according to its own load. Therefore, the TX transmits the "power suppression threshold" / "inquiry time" itself, rather than waiting for an inquiry from the RX. The RX can then reliably perform NFC tag detection during the power transmission phase by responding to the transmission power suppression performed by the TX. Therefore, even in a situation where high transmission power generates noise that affects NFC tag detection communication, it is possible to perform NFC tag detection processing appropriately and reliably. That is, this embodiment can achieve both high-power wireless power transmission and NFC tag detection during wireless power transmission.

[0155] Other Embodiments Hereinafter, other embodiments will be described that are not limited to the above-described contents, with respect to the parts that are commonly described in the first to third embodiments.

[0156] In the above description, the TX checks the transmission power as the criterion for turning on transmission suppression when an NFC tag is detected. However, other methods are also possible. For example, the TX can determine the threshold based on the received power transmitted by the RX via RPP. That is, the TX can turn on transmission suppression based on whether the received power transmitted from the RX via RPP exceeds a threshold. Alternatively, the TX may determine the threshold based on the GP determined in the negotiation phase. In this case, the GP may be used as the threshold, or both the GP and the threshold may be used. In the latter case, for example, if the GP is determined to be a value exceeding the threshold, this means that transmission suppression is always turned on in the NFC tag detection process in the Power Transfer Phase. The control unit 301 and the program for determining the threshold are examples of a determination means. Alternatively, the power transmission profile determined in the negotiation phase may be used as the criterion. For example, when a Power Profile that is expected to be high output is selected, this means that power transmission suppression is always set to ON during the NFC tag detection process in the Power Transfer Phase. Alternatively, conversely, in a Power Profile that minimizes the possibility of an NFC tag being inserted during the power transmission phase, it is also possible to always keep power transmission suppression OFF. This is expected to be the case in a Profile where the TX and RX are firmly connected and there is little room for foreign objects to be inserted.

[0157] In the above embodiments, an example has been described in which the RX adjusts the processing load in response to the suppression of power transmission during NFC tag detection processing, but this is not limiting. For example, if the battery 208 of the RX is sufficiently supplied with power and suppressing transmission power does not pose a problem, the RX may not adjust the processing load. Furthermore, the RX may determine whether to adjust the processing load based on the relationship between the power supply of wireless power transmission and the power consumption on the RX side. For example, when the RX is executing a high-load process and the power consumption on the RX side exceeds the power supplied from the TX, it may determine to adjust the processing load.

[0158] In the above embodiments, the TX reduces the transmission power as a way to suppress power transmission during NFC tag detection processing. However, this is not limiting. For example, power transmission may be stopped when an NFC tag is detected. However, if power transmission is stopped, the RX must take care in its response. If the RX does not have a battery or has a battery with a low charge, stopping power transmission may cause the previous state to be lost due to a power loss, and the RX may be unable to communicate with the TX due to a state mismatch. Therefore, if the RX does not have a battery or has a battery with a low charge, when adjusting the processing load, the RX saves the current state to non-volatile memory in preparation for power transmission stop. Then, after power transmission is restored (resumed), the RX may restore the saved information so that the Power Transfer Phase can be continued. In addition, the TX may also retain information about the RX's state while power transmission is stopped, so that the power transmission phase with the RX can be continued after power transmission is restored (resumed). The information about the status of the RX is information that the TX has received from the RX in the negotiation phase and the power transmission phase. The control unit 201 is an example of a restart means that restarts power reception based on the information about the status of the power receiving device that it has stored. Furthermore, the TX can confirm the presence of the RX by issuing an Analog Ping while power transmission is stopped in order to determine whether the RX has been moved from the appropriate charging position during the power transmission stop.

[0159] The TX can also variably control the NFC tag detection process cycle (execution standby time), inquiry time, and / or time until NFC tag detection (remaining execution time) based on the transmission power. For example, when the transmission power is high, it is preferable to frequently perform NFC tag detection. To achieve this, the TX can appropriately change the NFC tag detection process cycle and the inquiry interval (inquiry time) from the RX to the TX according to the transmission power. Take the TX process in FIG. 10 as an example. The process of "send the time until the next NFC tag detection" in S6114 is performed when the transmission power exceeds the threshold (NO in S6110). Here, the TX can change the inquiry time by notifying the RX of the "inquiry time" from the next time onward in addition to "send the time until the next NFC tag detection." In response, the RX acquires information on "send the time until the next NFC tag detection" and the "inquiry time" from the next time onward in the process of S5128. Then, the RX can change the inquiry period by setting the next timer start in S5119 to the acquired inquiry time. Also, the TX can start the timer with the changed NFC detection period when starting the NFC timer in S6128 or S6126. In the case of the third embodiment, this can be achieved simply by the TX changing the period of the NFC timer on its side.

[0160] Alternatively, the TX can variably control the period of the NFC tag detection process (execution waiting time), the inquiry time, and / or the time until NFC tag detection (remaining execution time) based on the GP determined in the negotiation phase. For example, the TX can determine the period of the NFC tag detection process according to the value of GP, and adjust the inquiry interval transmitted by ACAP according to that value.

[0161] In the above embodiments, the information on the "power transmission suppression threshold" is transmitted to the RX in the negotiation phase, but it may also be transmitted to the RX in the power transmission phase. The same applies to the "inquiry time" in the first and second embodiments. In this case, it is sufficient that at least one of the "power transmission suppression threshold" and the "inquiry time" is transmitted to the RX in the power transmission phase. Alternatively, either the "power at the time of power transmission suppression" or the "time of power transmission suppression" may be transmitted in the negotiation phase, and the other may be transmitted in the power transmission phase.

[0162] In the above embodiments, the TX transmits the GRQ (ACAP) (F415) after the SRQ (GP) transmission in F413 in Fig. 4. However, the timing of transmitting the GRQ (ACAP) may be any timing as long as it is after the ACK transmission in F408 in the negotiation phase. An example of such timing is between F412 and F413.

[0163] Some (or in some cases all) of the components in the above embodiment may be replaced with other components that perform similar functions, or may be omitted, or other components may be added. Furthermore, the present invention is not limited to the WPC standard, and can be applied to various standards.

[0164] The power transmitting device and the power receiving device may be, for example, an image input device such as an imaging device (still camera, video camera, etc.) or a scanner, or an image output device such as a printer, copier, projector, etc. Furthermore, they may be storage devices such as a hard disk drive or a memory device, or information processing devices such as a personal computer (PC), a smartphone, or a tablet device.

[0165] The power receiving device of the present disclosure may also be an information terminal device. For example, the information terminal device has a display unit (display) that receives power from a power receiving antenna and displays information to a user. The power received from the power receiving antenna is stored in a power storage unit (battery), and power is supplied from the battery to the display unit. In this case, the power receiving device may have a communication unit that communicates with another device different from the power transmitting device. The communication unit may be compatible with communication standards such as NFC communication and the fifth generation mobile communication system (5G).

[0166] The power receiving device of the present disclosure may also be a vehicle such as an automobile. For example, the automobile serving as the power receiving device may receive power from a charger (power transmitting device) via a power transmitting antenna installed in a parking lot. The automobile serving as the power receiving device may also receive power from the charger (power transmitting device) via a power transmitting antenna embedded in the road. Such an automobile supplies the received power to a battery. The battery's power may be supplied to a driving unit (motor, electric unit) that drives the wheels, or may be used to drive a sensor used for driving assistance or a communication unit that communicates with an external device. In other words, in this case, the power receiving device may include, in addition to the wheels, a battery, a motor or sensor that is driven using the received power, and even a communication unit that communicates with devices other than the power transmitting device. Furthermore, the power receiving device may have a storage unit for accommodating a person. For example, the sensor may be a sensor used to measure the distance between vehicles or the distance to other obstacles. The communication unit may be compatible with, for example, the Global Positioning System (GPS), or may be compatible with a communication standard such as the fifth generation mobile communication system (5G). The vehicle may be a bicycle or a motorcycle.

[0167] The power receiving device of the present disclosure may also be an electric tool, a home appliance, or the like. These devices, which are power receiving devices, may have a battery and a motor that is driven by the received power stored in the battery. These devices may also have a notification means for notifying the user of the remaining battery charge, etc. These devices may also have a communication unit that communicates with other devices different from the power transmitting device. The communication unit may be compatible with communication standards such as NFC and the fifth generation mobile communication system (5G).

[0168] The power transmission device of the present disclosure may also be an on-board charger that transmits power to a mobile information terminal device, such as a smartphone or tablet, that supports wireless power transmission within the vehicle. Such an on-board charger may be installed anywhere within the vehicle. For example, the on-board charger may be installed in the console of the vehicle, on the instrument panel (instrument panel, dashboard), between passenger seats, on the ceiling, or in the door. However, it is preferable that the on-board charger not be installed in a location that interferes with driving. Furthermore, while the power transmission device has been described using the example of an on-board charger, such a charger is not limited to being installed in a vehicle, but may also be installed in transportation such as a train, airplane, or ship. In this case, the charger may also be installed between passenger seats, on the ceiling, or in the door.

[0169] The power transmitting device may also be a vehicle such as an automobile equipped with an on-board charger. In this case, the power transmitting device has wheels and a battery, and supplies power to the power receiving device via a power transmitting circuit unit and a power transmitting antenna using power from the battery.

[0170] A program for realizing one or more of the functions of the above-described embodiments may be supplied to a system or device via a network or a storage medium, and one or more processors in the computer of the system or device may read and execute the program. Alternatively, the program may be implemented by a circuit (e.g., an ASIC) that realizes one or more of the functions.

[0171] The present disclosure has been described above in detail based on preferred embodiments thereof, but the present disclosure is not limited to the above embodiments, and various modifications are possible based on the gist of the present disclosure, and these modifications are not excluded from the scope of the present disclosure.

[0172] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims the benefit of Japanese Patent Application No. 2024-5434, filed on January 17, 2024. The contents of this Japanese patent application are incorporated herein by reference in their entirety.

Claims

1. A power transmission device, comprising: negotiation means for negotiating with a power receiving device; power transmission means for wirelessly transmitting power to the power receiving device based on the result of the negotiation; processing means for executing a process including detection of an NFC (Near Field Communication) tag; and communication means for transmitting, at least in the negotiation, information regarding the NFC tag detection performed during the power transmission to the power receiving device.

2. The power transmission device according to claim 1, wherein the processing means adjusts the power transmission power by the power transmission means based on the information regarding the NFC tag detection, and executes the NFC tag detection in a state where the power transmission power is adjusted.

3. The power transmission device according to claim 2, wherein the information regarding the NFC tag detection includes information indicating a threshold value of the power transmission power for the processing means to start processing regarding the adjustment of the power transmission power.

4. The information regarding the NFC tag detection further includes adjustment power information indicating the power transmission power at the time of adjustment and continuous time information indicating the time for continuing power transmission at the power transmission power at the time of adjustment, and the processing means adjusts the power transmission power based on the adjustment power information and the continuous time information. The power transmission device according to claim 3, characterized in that.

5. The power transmission device according to claim 4, wherein the communication means transmits the adjustment power information and the continuous time information to the power receiving device after the power transmission power exceeds the threshold value.

6. The information regarding the NFC tag detection further includes information indicating an inquiry waiting time until the power receiving device executes an inquiry to the power transmission device, and the object of the inquiry is information regarding an execution waiting time from when the power transmission power exceeds the threshold value until the processing means executes the NFC tag detection. The power transmission device according to claim 3, characterized in that.

7. The information regarding the NFC tag detection further includes adjustment power information indicating the power transmission power at the time of adjustment and continuous time information indicating the time for continuing power transmission at the power transmission power at the time of adjustment, and the processing means adjusts the power transmission power based on the adjustment power information and the continuous time information. The power transmission device according to claim 6, characterized in that.

8. The transmission device according to claim 7, wherein the execution standby time includes the remaining execution time until the NFC tag detection is executed, which is set based on the communication means receiving the inquiry.

9. The transmission device according to claim 8, wherein the communication means transmits information indicating the remaining execution time for the inquiry to the power receiving device before the execution standby time elapses, and the processing means adjusts the transmission power after the execution standby time elapses.

10. The transmission device according to claim 9, wherein the communication means transmits information indicating the remaining execution time for the inquiry to the power receiving device before the execution standby time elapses, and further transmits the adjustment power information and the duration information to the power receiving device based on receiving the inquiry further executed by the power receiving device based on the remaining execution time.

11. The transmission device according to claim 5, wherein the processing means sets the execution standby time from after the transmission power exceeds the threshold until the processing means executes the NFC tag detection, and the communication means transmits the adjustment power information and the duration information to the power receiving device after the execution standby time elapses.

12. The transmission device according to claim 8, wherein the processing means controls at least one of the execution standby time, the inquiry standby time, and the remaining execution time based on the transmission power.

13. The transmission device according to claim 8, wherein the processing means controls at least one of the execution standby time, the inquiry standby time, and the remaining execution time based on the guaranteed power determined in the negotiation.

14. The transmission device according to claim 2, wherein the processing means reduces the transmission power or stops the transmission as the adjustment of the transmission power.

15. The transmission device according to claim 14, wherein when the processing means stops the transmission, it holds information regarding the state of the power receiving device, and resumes the transmission based on the held information regarding the state of the power receiving device after executing the NFC tag detection.

16. The power transmission device according to claim 2, characterized in that the information regarding the NFC tag detection includes information indicating a threshold value of the received power by the power receiving device for the processing means to start processing regarding the adjustment of the power transmission power.

17. The power transmission device according to claim 3, further comprising determination means for determining the threshold value based on the information of the guaranteed power or the power transmission profile determined in the negotiation.

18. A power receiving device comprising: negotiation means for negotiating with a power transmission device capable of executing a process including detection of an NFC (Near Field Communication) tag; power receiving means for wirelessly receiving power from the power transmission device based on the result of the negotiation; and communication means for receiving, at least in the negotiation, information regarding the NFC tag detection performed during power transmission from the power transmission device.

19. The information regarding the NFC tag detection includes information indicating a threshold value of the power transmission power for the power transmission device to start processing regarding the adjustment of the power transmission power, and information indicating a query waiting time until the communication means executes a query to the power transmission device. The power transmission device adjusts the power transmission power based on the information regarding the NFC tag detection, executes the NFC tag detection in a state where the power transmission power is adjusted, and the communication means receives the remaining execution time until the execution of the NFC tag detection, which is set and transmitted based on the reception of the query by the power transmission device after the query waiting time has elapsed. The power receiving device according to claim 18.

20. The power transmission device adjusts the power transmission power based on the adjustment power information indicating the power transmission power at the time of adjustment and the duration information indicating the time for continuing power transmission at the power transmission power at the time of adjustment, which are further included in the information regarding the NFC tag detection. After the remaining execution time has elapsed, the power receiving device according to claim 19 further comprises adjustment means for adjusting the processing load of the power receiving device based on the adjustment power information and the duration information.

21. The power transmission device further transmits the adjustment power information and the duration information to the power reception device based on receiving the inquiry executed after the remaining execution time has elapsed by the power reception device, and the adjustment means adjusts the processing load based on the adjustment power information and the duration information transmitted from the power transmission device. The power reception device according to claim 20, characterized in that.

22. The information related to the NFC tag detection includes information indicating a threshold value of the power transmission for the power transmission device to start processing related to the adjustment of the power transmission, adjustment power information indicating the power transmission during adjustment, and duration information indicating the time for continuing power transmission at the power transmission during adjustment. The power transmission device sets an execution standby time until the power transmission device executes the NFC tag detection after the power transmission exceeds the threshold value, and after the execution standby time has elapsed, transmits the adjustment power information and the duration information to the power reception device, adjusts the power transmission based on the adjustment power information and the duration information, executes the NFC tag detection in a state where the power transmission has been adjusted, and further has adjustment means for adjusting the processing load of the power reception device based on the adjustment power information and the duration information transmitted from the power transmission device. The power reception device according to claim 18, characterized in that.

23. The power transmission device lowers the power transmission or stops the power transmission as the adjustment of the power transmission. When the power transmission is stopped, it holds information related to the state of the power reception device, and when the power transmission is restarted after the NFC tag detection is executed, it further has restart means for restarting power reception based on the held information related to the state of the power reception device. The power reception device according to claim 18, characterized in that.

24. A method performed by a power transmission device, comprising: a negotiation step of negotiating with a power reception device; a power transmission step of wirelessly transmitting power to the power reception device based on the result of the negotiation; a processing step of executing a process including detection of an NFC (Near Field Communication) tag; and a communication step of transmitting information related to the NFC tag detection performed during the power transmission to the power reception device at least in the negotiation step. A negotiation step of negotiating with a power transmission device capable of executing a process including detection of an NFC (Near Field Communication) tag; a power reception step of wirelessly receiving power from the power transmission device based on the result of the negotiation; and at least in the negotiation step, a communication step of receiving information regarding NFC tag detection performed during power transmission from the power transmission device. A method performed by a power reception device, characterized by comprising the above steps. A program for causing a computer to execute the method according to claim 24 or 25.

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