Power reception device, power transmission device, method performed by power reception device, method performed by power transmission device, and program

Abstract

This power reception device receives power from a power transmission device via a coil and communicates with the power transmission device via the coil when receiving the power from the power transmission device. The power reception device performs communication by a first communication method using the coil when receiving power with a first power and performs communication by a second communication method that is faster than the first communication method by using the coil when receiving power with a second power larger than the first power.

Description

Power receiving device, power transmitting device, method performed by power receiving device, method performed by power transmitting device, and program

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

[0002] In a wireless power transmission system, a power transmitting device transmits power to a power receiving device placed on a charging stand or the like. There is a need for faster charging in wireless charging. Patent Document 1 (JP-A-2005-102666) discloses control of rapid wireless charging.

[0003] JP 2018-108014 A

[0004] Because rapid wireless charging involves transmitting large amounts of power, it is necessary to ensure safety during charging. To achieve this, improvements in communication performance are required, such as by speeding up or stabilizing communication between the power transmitting device and the power receiving device to control charging.

[0005] The present disclosure provides a technique for improving communication performance between a power transmitting device and a power receiving device.

[0006] A power receiving device according to an embodiment of the present disclosure includes a power receiving unit that receives power from a power transmitting unit via a coil, and a communication unit that communicates with the power transmitting unit via the coil when receiving power from the power transmitting unit, wherein the communication unit uses the coil to communicate using a first communication method when receiving power at a first power, and uses the coil to communicate using a second communication method that is faster than the first communication method when receiving power at a second power that is greater than the first power.

[0007] According to the present disclosure, it is possible to improve the communication performance between a power transmitting device and a power receiving device.

[0008] 1 is a diagram illustrating an example of the configuration of a wireless power transmission system; FIG. 2 is a diagram illustrating an example of the configuration of a power transmitting device; FIG. 3 is a diagram illustrating an example of the configuration of a power receiving device; FIG. 4 is an explanatory diagram of a threshold setting method in state detection by the Power Loss method; FIG. 5 is an explanatory diagram of a Q-value measurement method; FIG. 6 is a block diagram illustrating an example of the functional configuration of a control unit of the power transmitting device; FIG. 7 is a flowchart illustrating processing of the power transmitting device; FIG. 8 is a flowchart illustrating processing of the power receiving device; FIG. 9 is an explanatory diagram of state detection by the waveform attenuation method; FIG. 10 is a diagram illustrating an example of processing for performing wireless power transmission; FIG. 11 is an explanatory diagram of a threshold setting method in state detection by the waveform attenuation method; FIG. 12 is an explanatory diagram of a coupling state index measurement method for a power transmitting antenna and a power receiving antenna; FIG. 13 is an explanatory diagram of a threshold setting method in state detection by the coupling state index measurement method; FIG. 14 is a flowchart illustrating processing of the power transmitting device of the first embodiment; FIG. 15 is a flowchart illustrating processing of the power receiving device of the first embodiment; FIG. 16 is a sequence diagram illustrating processing of the power transmitting device and the power receiving device of the first embodiment; FIG. 17 is a flowchart illustrating processing of the power transmitting device of the third embodiment; FIG. 18 is a sequence diagram illustrating processing of the power transmitting device and the power receiving device of the third embodiment; FIG. 19 is a flowchart illustrating processing of the power transmitting device and the power receiving device of the third embodiment; 10 is a flowchart illustrating processing by a power receiving device of a fourth embodiment. FIG. 11 is a sequence diagram illustrating processing by a power transmitting device and a power receiving device of a fourth embodiment. FIG. 12 is a table illustrating processing by a power transmitting device and a power receiving device of a fourth embodiment. FIG. 13 is a table illustrating processing by a power transmitting device and a power receiving device of a fourth embodiment. FIG. 14 is a table illustrating processing by a power transmitting device and a power receiving device of a fourth embodiment. FIG. 15 is a flowchart illustrating processing by a power receiving device of a sixth embodiment. FIG. 16 is a sequence diagram illustrating processing by a power transmitting device and a power receiving device of a sixth embodiment. FIG. 17 is a table illustrating processing by a power transmitting device and a power receiving device of a fifth embodiment. FIG. 18 is a table illustrating processing by a power transmitting device and a power receiving device of a sixth embodiment. FIG. 19 is a sequence diagram illustrating processing by a power transmitting device and a power receiving device of a sixth embodiment.

[0009] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. Although the embodiments describe multiple features, not all of these features are necessarily essential to the invention, and multiple features may be combined in any desired manner. Furthermore, in the accompanying drawings, the same reference numerals are used to designate identical or similar components. Each embodiment illustrates a wireless charging system to which a wireless power transmission system is applied. As an example, wireless power transmission based on the standard established by the Wireless Power Consortium, a wireless charging standardization organization (hereinafter referred to as the WPC standard), will be described.

[0010] [First embodiment] This embodiment will be described with reference to the drawings. Fig. 1 is a diagram showing an example of the configuration of a wireless charging system. This system includes a power transmitting device 100, a power receiving device 200, and a charging stand 300.

[0011] In the following, for simplicity of notation, the power receiving device 200 may be referred to as the RX 200, and the power transmitting device 100 may be referred to as the TX 100. Detailed configurations of the TX 100 and the RX 200 will be described later with reference to FIGS.

[0012] The RX200 is an electronic device that receives power from the TX100 and charges its built-in battery while placed on the charging stand 300. The TX100 is an electronic device that wirelessly transmits power to the RX200 placed on the charging stand 300. Because the charging stand 300 constitutes a part of the TX100, hereinafter, the RX200 "placed on the charging stand 300" may be referred to as "placed on the TX100." The spatial range in which the RX200 can receive power from the TX100 is schematically shown by the dotted line frame 400 in FIG. 1. The RX200 and the TX100 may have a function for executing applications other than the wireless charging function. For example, the RX200 is a smartphone, and the TX100 is an accessory device for charging the battery of the RX200. However, the present invention is not limited to this example.

[0013] Next, an example configuration of the power transmitting device 100 will be described with reference to FIG. 2 . FIG. 2 is a functional block diagram showing an example configuration of the power transmitting device 100. The TX 100 includes a control unit 101, a power supply unit 102, a power transmitting unit 103, a first communication unit 104, a power transmitting antenna (power transmitting coil) 105, a memory 106, a resonant capacitor 107, a switch unit 108, a second communication unit 109, and a UI (user interface) unit 110. Hereinafter, the user interface will be referred to as UI. Although each functional block element is depicted as a separate entity in FIG. 2 , any number of functional block elements may be implemented within the same chip.

[0014] The control unit 101 controls the entire TX 100 by executing a control program stored in the memory 106. The control unit 101 also controls power transmission, including communication for device authentication in the TX 100. The control unit 101 can also control the execution of applications other than wireless power transmission. The control unit 101 includes one or more processors, such as a CPU (Central Processing Unit) or an MPU (Microprocessor Unit). Alternatively, the control unit 101 may be configured with hardware, such as an application-specific integrated circuit (ASIC). The control unit 101 may also include an array circuit, such as an FPGA (Field Programmable Gate Array), compiled to execute a predetermined process. The control unit 101 can perform processing to store information that should be stored during the execution of various processes in the memory 106, and can also perform timing processing using a timer (not shown).

[0015] The power supply unit 102 supplies power to each functional block element. The power supply unit 102 includes, for example, a power supply connection circuit to a commercial power source and a battery. The battery is charged with power supplied from the commercial power source.

[0016] The power transmitting unit 103 converts the DC power or AC power input from the power supply unit 102 into AC power in a frequency band used for wireless power transmission, and inputs the AC power to the power transmitting antenna 105 to generate electromagnetic waves for receiving power at the RX 200. For example, the power transmitting unit 103 includes an inverter, and converts the DC voltage supplied by the power supply unit 102 into an AC voltage using a switching circuit with a half-bridge or full-bridge configuration. The power transmitting unit 103 includes a plurality of FETs (Field Effect Transistors) that form a bridge, and a gate driver that controls the ON / OFF of the plurality of FETs.

[0017] The power transmitting unit 103 controls the intensity of the electromagnetic waves to be output (transmission power) by adjusting the voltage (transmission voltage) or current (transmission current), or both, input to the power transmitting antenna 105. The intensity of the electromagnetic waves (intensity of the transmission power) is controlled by the magnitude of the transmission voltage or the transmission current. Alternatively, the power transmitting unit 103 controls the intensity of the electromagnetic waves to be output (transmission power) by adjusting the voltage (inverter input voltage) or current (inverter input current), or both, input to an inverter included in the power transmitting unit 103. The voltage input to this inverter is hereinafter referred to as the inverter input voltage. Also, the current input to this inverter is hereinafter referred to as the inverter input current. The intensity of the electromagnetic waves (intensity of the transmission power) is controlled by the magnitude of the inverter input voltage or the inverter input current.

[0018] Alternatively, the power transmitting unit 103 controls the intensity of the electromagnetic waves (transmitted power) by adjusting the voltage (inverter output voltage) or current (inverter output current), or both, output from the inverter included in the power transmitting unit 103. The voltage output from the inverter is hereinafter referred to as the inverter output voltage. The current output from the inverter is hereinafter referred to as the inverter output current. The strength of the electromagnetic waves (strength of transmitted power) is controlled by the magnitude of the inverter output voltage or inverter output current.

[0019] The power transmitting unit 103 controls the output of AC frequency electromagnetic wave power so as to start or stop power transmission by the power transmitting antenna 105 or control the intensity of the electromagnetic waves to be output based on an instruction signal from the control unit 101. The power transmitting unit 103 is also assumed to have a power supply capacity sufficient to output 50 watts (W) of power to the charging unit of the power receiving device 200 that complies with the WPC standard.

[0020] The first communication unit 104 is connected to the control unit 101 and the power transmitting unit 103, and communicates with the RX 200 for power transmission control based on the WPC standard. The first communication unit 104 performs frequency shift keying of the electromagnetic waves output from the power transmitting antenna 105 and transmits information to the RX 200 to perform communication. The first communication unit 104 also demodulates the electromagnetic waves modulated by the RX 200 and transmitted from the power transmitting antenna 105 to acquire the information transmitted by the RX 200. Communication by the first communication unit 104 is performed by superimposing a communication signal on the electromagnetic waves transmitted from the power transmitting antenna 105. The first communication unit 104 performs so-called in-band communication. The first communication unit 104 is an example of a communication means for communicating with the power receiving device via a coil when transmitting power to the power receiving device. The communication means may include the control unit 101 in addition to the first communication unit 104.

[0021] In addition to the control program, the memory 106 can store information about the states of the TX 100 and the RX 200. The information about the states of the TX 100 and the RX 200 includes the transmitted power value, the received power value, etc. The information about the state of the TX 100 is acquired by the control unit 101. The information about the state of the RX 200 is acquired by the control unit of the RX 200, and can be received by the first communication unit 104 or the second communication unit 109 described later.

[0022] The switch unit 108 is connected in parallel to the series circuit of the resonant capacitor 107 and the power transmitting antenna 105. The control unit 101 transmits a control signal to the switch unit 108 to control its ON / OFF. The power transmitting antenna 105 is connected to the resonant capacitor 107. When the control signal from the control unit 101 turns the switch unit 108 ON and short-circuits it, the power transmitting antenna 105 and the resonant capacitor 107 form a series resonant circuit that resonates at a specific frequency fA. At this time, a current flows through the closed circuit formed by the power transmitting antenna 105, the resonant capacitor 107, and the switch unit 108. On the other hand, when the control signal from the control unit 101 turns the switch unit 108 OFF and the circuit is opened, power is supplied from the power transmitting unit 103 to the power transmitting antenna 105 and the resonant capacitor 107.

[0023] The second communication unit 109 is connected to the control unit 101 and communicates with the RX 200 using a standard different from the WPC standard. For example, the second communication unit 109 communicates with the RX 200 using an antenna (not shown) different from the power transmitting antenna 105. Examples of communication methods used by the second communication unit 109 include wireless LAN (Local Area Network), Bluetooth Low Energy (BLE), and NFC (Near Field Communication). BLE may be any communication method compatible with Bluetooth standard version 4.0 or later. The frequency band used when transmitting power from the power transmitting antenna 105 is different from the frequency band used for communication by the second communication unit 109. The second communication unit 109 performs so-called out-band communication.

[0024] Regarding communication between the TX 100 and the RX 200, the TX 100 may selectively use one of a plurality of communication standards to communicate with the RX 200. The following communication modes are possible, selectively using a plurality of communication modes: - Communication based on a first standard (WPC standard) between the first communication unit 104 of the TX 100 and the first communication unit 204 of the RX 200 (see FIG. 3). - Communication based on a second standard (a standard other than the WPC standard) between the second communication unit 109 of the TX 100 and the second communication unit 212 of the RX 200 (see FIG. 3).

[0025] The UI unit 110 is connected to the control unit 101 and performs various outputs to the user. The various outputs include screen display, blinking or color changes of LEDs (Light Emitting Diodes), audio output from a speaker, vibration of the TX100 main body, and other operations. The UI unit 110 is realized by a liquid crystal panel, a speaker, a vibration motor, etc.

[0026] Next, a configuration example of the power receiving device 200 will be described with reference to Fig. 3. Fig. 3 is a block diagram showing a configuration example of the power receiving device 200. The RX 200 has a control unit 201, a UI unit 202, a power receiving unit 203, a first communication unit 204, a power receiving antenna 205, a charging unit 206, a battery 207, and a memory 208. The RX 200 further has a first switch unit 209, a second switch unit 210, a resonant capacitor 211, a second communication unit 212, and a third switch unit 213. In this embodiment, an example is shown in which the functional block elements in Fig. 3 are individual elements, but multiple functional block elements may also be realized as a single hardware module.

[0027] The control unit 201 controls each functional block element of the RX200 by executing a control program stored in the memory 208. Furthermore, the control unit 201 can also perform control for executing applications other than wireless power transmission. The control unit 201 includes one or more processors such as a CPU or an MPU. The control unit 201 can also control the entire RX200 (e.g., the entire smartphone) in cooperation with an operating system (OS) running on the control unit 201. Alternatively, the control unit 201 can be configured with hardware such as an ASIC, or can include an array circuit such as an FPGA compiled to execute predetermined processes. The control unit 201 stores information to be stored during execution of various processes in the memory 208 and can also perform timing processes using a timer (not shown).

[0028] The UI unit 202 is connected to the control unit 201 and performs various outputs to the user. The various outputs include screen display, blinking or color changes of LEDs (Light Emitting Diodes), audio output from a speaker, vibration of the RX200 main body, and other operations. The UI unit 202 is realized by a liquid crystal panel, a speaker, a vibration motor, etc.

[0029] The power receiving unit 203 receives, via the power receiving antenna (power receiving coil) 205, AC power (AC voltage and AC current) generated by electromagnetic induction based on electromagnetic waves radiated from the power transmitting antenna 105 of the TX 100. The power receiving unit 203 then converts the AC power into DC or AC power of a predetermined frequency and supplies the power to the charging unit 206. The charging unit 206 charges the battery 207. The power receiving unit 203 includes a rectifier (rectifier, rectifier circuit) and a voltage control unit required for supplying power to the load in the RX 200. The rectifier converts the AC voltage and AC current received from the power transmitting antenna via the power receiving antenna 205 into DC voltage and DC current. This DC voltage will be referred to below as the rectifier output voltage. Furthermore, this DC current will be referred to below as the rectifier output current. The voltage control unit converts the level of the DC voltage (rectifier output voltage) output by the rectifier to a predetermined level. The predetermined level is a DC voltage level at which control unit 201, charging unit 206, etc. can operate. Power receiving unit 203 supplies power for charging from charging unit 206 to battery 207. It is assumed that power receiving unit 203 has a power supply capacity sufficient to output 50 watts of power to charging unit 206.

[0030] The first communication unit 204 communicates with the first communication unit 104 of the TX 100 for power reception control based on the WPC standard. The first communication unit 204 is connected to the power receiving antenna 205 and the control unit 201. The first communication unit 204 demodulates electromagnetic waves input from the power receiving antenna 205 to acquire information transmitted from the TX 100. The first communication unit 204 performs load modulation, amplitude modulation, or backscatter modulation on the input electromagnetic waves, and superimposes a signal related to information to be transmitted to the TX 100 on the electromagnetic waves, thereby communicating with the TX 100. The first communication unit 204 is an example of a communication means that communicates with the power transmitting device via a coil when receiving power from the power transmitting device. The communication means may include the control unit 201 in addition to the first communication unit 204.

[0031] In addition to the control program, the memory 208 stores information about the states of the TX 100 and the RX 200. Information about the state of the RX 200 is acquired by the control unit 201. Information about the state of the TX 100 is acquired by the control unit 101 of the TX 100, and can be received by the first communication unit 204 or a second communication unit 212 described later.

[0032] The second communication unit 212 is connected to the control unit 201, and communicates with the TX 100 using a standard different from the WPC standard. For example, the second communication unit 212 communicates with the TX 100 using an antenna different from the power receiving antenna 205. The communication method used by the second communication unit 212 includes wireless LAN, BLE, and NFC. BLE may be any communication method compatible with Bluetooth standard version 4.0 or later. The frequency band used when receiving power via the power receiving antenna 205 is different from the frequency band used for communication by the second communication unit 212.

[0033] Regarding communication between the TX100 and the RX200, the RX200 may selectively use one of a plurality of communication standards to communicate with the TX100. The following communication modes are possible, selectively using a plurality of communication standards: - Communication based on a first standard (WPC standard) between the first communication unit 104 of the TX100 and the first communication unit 204 of the RX200. - Communication based on a second standard (a standard other than the WPC standard) between the second communication unit 109 of the TX100 and the second communication unit 212 of the RX200.

[0034] First switch unit 209 is provided between charging unit 206 and battery 207, and is controlled by control unit 201. First switch unit 209 has a function of controlling whether or not power received by power receiving unit 203 is supplied to battery 207, and a function of controlling the magnitude of the load. When first switch unit 209 is turned OFF and opened by control unit 201, the power received by power receiving unit 203 is not supplied to battery 207. When first switch unit 209 is turned ON and short-circuited by control unit 201, the power received by power receiving unit 203 is supplied to battery 207.

[0035] In FIG. 3, first switch unit 209 is disposed between charging unit 206 and battery 207 , but first switch unit 209 may be disposed between power receiving unit 203 and charging unit 206 .

[0036] Alternatively, the first switch unit 209 may be disposed between the power receiving unit 203 and a closed circuit formed by the power receiving antenna 205, the resonant capacitor 211, and the second switch unit 210. In this case, the first switch unit 209 has a function of controlling whether or not the power received by the power receiving antenna 205 is to be supplied to the power receiving unit 203.

[0037] 3, first switch unit 209 is depicted as a single functional block element, but first switch unit 209 can be realized as part of charging unit 206 or power receiving unit 203. Furthermore, first switch unit 209 is not limited to being inserted in series between charging unit 206 and battery 207, and first switch unit 209 may be inserted in parallel between charging unit 206 and battery 207. In this case, when first switch unit 209 is turned OFF by control unit 201 and opened, the power received by power receiving unit 203 is supplied to battery 207. When first switch unit 209 is turned ON by control unit 201 and short-circuited, the power received by power receiving unit 203 is not supplied to battery 207.

[0038] On the input side of the power receiving unit 203, the second switch unit 210 is connected in parallel to the resonant capacitor 211. The resonant capacitor 211 is connected to the power receiving antenna 205 via the third switch unit 213. The second switch unit 210 and the third switch unit 213 are controlled by the control unit 201. The third switch unit 213 has a function of controlling whether or not the terminal of the power receiving antenna 205 is opened. When the control unit 201 turns the third switch unit 213 to the OFF state, the terminal of the power receiving antenna 205 is opened. When the control unit 201 turns the third switch unit 213 to the ON state, the power receiving antenna 205 is connected to the power receiving unit 203 via the resonant capacitor 211.

[0039] When the control unit 201 turns the third switch unit 213 ON and the second switch unit 210 ON to short-circuit the power receiving antenna 205 and the resonant capacitor 211 form a series resonant circuit that resonates at a specific frequency fB. Current flows through the closed circuit formed by the power receiving antenna 205, the resonant capacitor 211, and the second switch unit 210, but no current flows through the power receiving unit 203. When the second switch unit 210 turns OFF to open the circuit, power received by the power receiving antenna 205 and the resonant capacitor 211 is supplied to the power receiving unit 203. Note that the present invention is not limited to the example of FIG. 3 , and the second switch unit 210 may be disposed between the power receiving antenna 205 and the resonant capacitor 211. When the third switch unit 213 is ON and the second switch unit 210 is ON, the terminals of the power receiving antenna 205 are short-circuited. Furthermore, the third switch section 213 may be disposed between the resonant capacitor 211 and the power receiving section 203 .

[0040] In this system, the TX 100 and the RX 200 perform wireless power transmission between the transmitting antenna 105 and the receiving antenna 205 based on the WPC standard. In the WPC standard, the load power level agreed upon between the RX 200 and the TX 100 is specified by a value called Guaranteed Load Power (hereinafter referred to as "GP"). The load power is the power consumed by the load. For example, the GP indicates a power value that is guaranteed to be output from the RX 200 to the load even if the coupling between the receiving antenna 205 and the transmitting antenna 105 weakens due to a change in the positional relationship between the RX 200 and the TX 100, resulting in a decrease in power transmission efficiency. The load of the RX 200 is the charging unit 206, the battery 207, etc., and the GP value corresponds to the power guaranteed to be output from the receiving unit 203. Alternatively, the GP value corresponds to the power guaranteed to be output from the rectifier unit of the receiving unit 203. For example, let us assume that the value of GP is 5 (watts) and the positional relationship between the power receiving antenna 205 and the power transmitting antenna 105 fluctuates. In this case, even if the power transmission efficiency decreases, the TX 100 performs power transmission control so as to be able to output 5 watts to the load of the RX 200. Furthermore, the GP is determined by negotiation between the TX 100 and the RX 200. Note that this embodiment is applicable not only to GP but also to a configuration in which power is transmitted and received at a power determined by mutual negotiation between the TX 100 and the RX 200.

[0041] Also, assume that an object is present near the TX 100 when transmitting power from the TX 100 to the RX 200. In this case, the object is an object (foreign object) that may affect the power transmission from the TX 100 to the RX 200, but is different from the RX 200. The electromagnetic waves used for power transmission may affect the foreign object, potentially causing the foreign object to heat up or be destroyed. In this disclosure, a foreign object refers to an object that is not part of a power receiving device and a product incorporating the power receiving device, or a power transmitting device and a product incorporating the power transmitting device, but that may generate heat when exposed to a power signal. Examples of foreign objects include a paper clip and an IC card. Objects that are integral parts of a power receiving device and a product incorporating the power receiving device, or a power transmitting device and a product incorporating the power transmitting device, and that may unintentionally generate heat when exposed to wireless power transmitted by a power transmitting antenna, are not considered foreign objects.

[0042] The WPC standard specifies a method for preventing a foreign object from increasing in temperature or being destroyed by stopping power transmission when a foreign object is present. Specifically, the power transmitting device 100 can detect the presence of a foreign object on the charging stand 300. The power loss method is a method for detecting a foreign object based on the difference between the transmitted power in the TX 100 and the received power in the RX 200. The Q-factor measurement method is a method for detecting a foreign object based on a change in the quality factor (Q-factor, quality coefficient, Q value) of the transmitting antenna 105 (power transmitting coil) in the TX 100. Alternatively, the Q-factor measurement method is a method for detecting a foreign object based on a change in the quality factor (Q-factor, quality coefficient, Q value) of a resonant circuit including the transmitting antenna 105 and resonant capacitor 107 in the TX 100. In the present disclosure, the Quality Factor of the power transmitting antenna 105 and the Quality Factor of the resonant circuit including the power transmitting antenna 105 and the resonant capacitor 107 are referred to as the Quality Factor related to the power transmitting antenna 105. However, the foreign objects detected by the TX 100 are not limited to objects present on the charging stand 300. The TX 100 is capable of detecting foreign objects located in the vicinity of the TX 100. For example, the TX 100 can detect foreign objects located within a range where power can be transmitted.

[0043] Referring to Figure 4, foreign object detection based on the Power Loss method defined in the WPC standard will be described. In Figure 4, the horizontal axis represents the transmitted power of the TX 100, and the vertical axis represents the received power of the RX 200. On the graph line represented by the straight line segment 1002, point 1000 corresponds to the first transmitted power value Pt1 and the first received power value Pr1, and point 1001 corresponds to the second transmitted power value Pt2 and the second received power value Pr2. On the graph line, point 1003 corresponds to the third transmitted power value Pt3 and the third received power value Pr3. The foreign object to be detected is a conductive metal piece or the like.

[0044] First, the TX 100 transmits power to the RX 200 at a first transmission power value Pt1, and the RX 200 receives power at a first reception power value Pr1. Hereinafter, this state is referred to as a light load state. The TX 100 stores the first transmission power value Pt1. At this time, the RX 200 performs load control so that the received power is minimized. Alternatively, the RX 200 performs load control so that the received power is within a predetermined range or below a predetermined threshold. Here, the "power within a predetermined range" or "power below a predetermined threshold" refers to a power value approximately 10% of the Reference Power (described later). The RX 200 may also disconnect the load from the receiving antenna 205 so that the received power is not supplied to the load (e.g., the charging unit 206 or the battery 207 in FIG. 3 ). Alternatively, the RX200 may control the load so that a predetermined power is supplied to the load. This can be achieved by controlling the first switch unit 209. Next, the RX200 notifies the TX100 of the first received power value Pr1. The TX100, having received a signal relating to the first received power value Pr1 from the RX200, calculates the power loss between the TX100 and the RX200. The power loss at this time is Pt1-Pr1 (=Ploss1). A calibration point (hereinafter abbreviated as CP) 1000 indicating the correspondence between Pt1 and Pr1 can be generated.

[0045] Next, the TX 100 changes the transmission power value to the second transmission power value Pt2 and transmits power to the RX 200, and the RX 200 receives power at the second receiving power value Pr2. Hereinafter, this state is referred to as the Connected Load state (load connected state). The TX 100 then stores the second transmission power value Pt2. At this time, the RX 200 performs load control so that the received power is the maximum power. Here, "maximum power" refers to a power value close to the Reference Power, which will be described later. Alternatively, the RX 200 performs load control so that the received power is within a predetermined range or is equal to or greater than a predetermined threshold. For example, the RX 200 connects the receiving antenna 205 to the load so that the received power is supplied to the load. These operations can be achieved by controlling the first switch unit 209. Next, RX200 notifies TX100 of the second received power value Pr2. TX100, which has received a signal related to the second received power value Pr2 from RX200, calculates the power loss between TX100 and RX200. The power loss at this time is Pt2-Pr2 (=Ploss2). CP1001 indicating the correspondence between Pt2 and Pr2 can be generated.

[0046] The TX 100 performs linear interpolation between CP 1000 and CP 1001 to generate a line segment 1002. The line segment 1002 shows the relationship between the transmitted power and the received power in a state where no foreign object is detected near the TX 100 and the RX 200 (hereinafter referred to as the first detection state). Based on the line segment 1002, the TX 100 can estimate the power value that the RX 200 will receive when transmitting power at a predetermined transmitted power in the first detection state. For example, assume that the TX 100 transmits power at a third transmitted power value Pt3. In this case, the TX 100 can estimate the third received power value Pr3 that the RX 200 will receive from a point 1003 on the line segment 1002 that corresponds to Pt3.

[0047] As described above, the power loss between the TX 100 and the RX 200 corresponding to the load can be determined based on multiple combinations of the transmission power value of the TX 100 and the reception power value of the RX 200 measured while changing the load. Furthermore, by performing an interpolation process using multiple combinations of the transmission power value and the reception power value, the power loss between the TX 100 and the RX 200 corresponding to all loads can be estimated. The calibration process performed by the TX 100 and the RX 200 in this manner to obtain combinations of the transmission power value and the reception power value of the TX 100 is referred to as "calibration process using the power loss method." The calibration process is also abbreviated as "CAL process." Performing the calibration process again after the calibration process has been performed once and updating or adding calibration points is referred to as "recalibration process," also abbreviated as "ReCAL process."

[0048] Assume that after the CAL process of the Power Loss method, the TX 100 actually transmits power to the RX 200 at the third transmission power value Pt3, and the TX 100 receives a signal related to the received power value Pr3* from the RX 200. This signal related to the received power value Pr3* is the Received Power Data packet (mode 0) specified in the WPC standard, but other messages may also be used. Hereinafter, the Received Power Data packet (mode 0) will be referred to as RP0. RP0 includes the value of the received power value Pr3*. The TX 100 calculates Pr3-Pr3* (=Ploss_FO) by subtracting the received power value Pr3* actually received from the RX 200 from the received power value Pr3 in the first detection state. If a foreign object is present near the TX 100 and RX 200, Ploss_FO can be estimated as the power consumed by the foreign object, i.e., the power loss. Hereinafter, the state in which the presence of a foreign object near the TX 100 and RX 200 is detected is referred to as the second detection state.

[0049] In the second detection state, the TX100 compares the power loss Ploss_FO that is likely to have been consumed by the foreign object with a predetermined threshold. If the value of the power loss Ploss_FO exceeds the threshold, the TX100 can determine that a foreign object is present. Alternatively, the TX100 acquires the third received power value Pr3 in the first detection state from the RX200 and calculates in advance the power loss Pt3-Pr3 (=Ploss3) between the TX100 and the RX200.

[0050] Next, the TX 100 acquires the received power value Pr3* from the RX 200 in the second detection state, and calculates the power loss Pt3-Pr3* (=Ploss3*) between the TX 100 and the RX 200 in the second detection state. The TX 100 can then estimate the power loss Ploss_FO using Ploss3*-Ploss3.

[0051] As described above, there are two methods for calculating Ploss_FO in the second detection state: a first method for calculating Ploss_FO from Pr3 - Pr3*, and a second method for calculating Ploss_FO from Ploss3* - Ploss3.

[0052] In this embodiment, the second method will basically be described, but the contents of this embodiment can also be applied to the first method.

[0053] Next, foreign object detection based on the Q-factor measurement method defined in the WPC standard will be described with reference to FIG. 5 . FIG. 5(A) is a schematic circuit diagram for explaining a method for measuring a quality factor (Q-factor, quality coefficient, Q-factor) using the Q-factor measurement method. The AC power supply 901 is a power supply that outputs AC power generated by the power transmitting unit 103 of the TX 100. The power transmitting antenna 902 corresponds to the power transmitting antenna 105, and the capacitor 903 corresponds to the resonant capacitor 107. The power transmitting antenna 902 and the capacitor 903 are connected in series. The voltage value V8 is a voltage value of a predetermined frequency generated by the power transmitting unit 103 for operating the wireless power transmission system. The voltage value V9 is a voltage value applied to the power transmitting antenna 902. Here, it is assumed that the TX 100 is capable of changing the frequency related to the voltage value. The voltage values ​​V8 and V9 are voltage values ​​measured by the TX 100 when the TX 100 transmits an Analog Ping (hereinafter referred to as "AP") or a Digital Ping (hereinafter referred to as "DP") to the RX 200. Since the voltage values ​​V8 and V9 are AC voltage values, their effective values ​​(RMS) may also be used.

[0054] 5B shows an example of measurement results of V9 / V8 versus frequency, showing characteristics with a peak at 100 kHz. The horizontal axis represents frequency, and the vertical axis represents the voltage ratio "V9 / V8." V9 / V8 represents the Quality Factor associated with the power transmitting antenna 902, and its value changes when an object is placed near the power transmitting antenna 902. The change in the Quality Factor differs depending on whether an object is placed on the TX 100, whether the RX 200 is placed on the TX 100, whether a foreign object (such as a metal piece) is placed on the TX 100, or whether the RX 200 and the foreign object are placed on the TX 100.

[0055] In the Negotiation phase (described later) defined in the WPC standard, the TX 100 receives an FOD Status Data packet signal from the RX 200. The FOD Status Data packet includes a Reference Quality Factor Value and a Reference Resonance Frequency Value. The Reference Quality Factor Value is a Quality Factor that can be measured at the terminal of the transmitting antenna of the test TX 100 when the RX 200 is placed on the test TX 100 and there is no foreign object nearby. The Reference Resonance Frequency Value is as follows: That is, it is the resonance frequency calculated from the inductance value that can be measured at the terminals of the power transmitting antenna of the test TX100 when the RX200 is placed on the test TX100 and no foreign object is present nearby. In the Q-factor measurement method, a threshold is set based on the Reference Quality Factor Value. Foreign objects are detected by comparing this threshold with the Quality Factor found from the actually measured V9 / V8. Alternatively, a threshold is set based on the Reference Resonance Frequency Value. Foreign objects are detected by comparing this threshold with the resonance frequency found by actually measuring V9 / V8.

[0056] The RX200 and TX100 of this embodiment communicate for power transmission and reception control based on the WPC standard. The WPC standard defines multiple phases, including a power transfer phase in which power transmission is performed and one or more phases before the actual power transmission. Communication for necessary power transmission and reception control is performed in each phase. For example, foreign object detection using the power loss method is performed in the power transfer phase based on data obtained in the calibration phase. Furthermore, foreign object detection using the Q-factor measurement method is performed before power transmission (before sending a digital ping and in the negotiation phase or renegotiation phase).

[0057] The WPC standard defines the phases before power transmission as a Selection phase, a Ping phase, and a Configuration phase. In addition, the WPC standard also defines a Negotiation phase and a Calibration phase. The processing in each phase will be described below.

[0058] In the Selection phase, the TX100 intermittently transmits Analog Pings to detect that an object has been placed on the charging base of the TX100. Analog Pings are short-duration power signals applied to detect the presence of an object. However, this power signal does not activate the control unit of the power receiving device. For example, it detects that the RX200, a conductor piece, or the like has been placed on the charging base. The TX100 detects one or both of the voltage and current values ​​of the transmitting antenna 105 when it transmits Analog Pings. If the voltage value is below a threshold or the current value exceeds a threshold, the TX100 determines that an object is present and transitions to the Ping phase. Alternatively, if the Quality Factor calculated from the voltage value satisfies a predetermined condition, or if the Quality Factor calculated from the current value satisfies a predetermined condition, the TX 100 determines that an object is present and transitions to the Ping phase.

[0059] In the Ping phase, the TX100 transmits a Digital Ping, which has a higher power than the Analog Ping. The Digital Ping is a power signal for activating the control unit of the RX200 placed on the TX100. The RX200 notifies the TX100 of the received power voltage value. In this way, the TX100 recognizes that the object detected in the Selection phase is the RX200 by receiving a response from the RX200 that received the Digital Ping. When the TX100 receives notification of the received power voltage value from the RX200, it transitions to the Configuration phase. Furthermore, before transmitting the Digital Ping, the TX100 measures the Quality Factor associated with the power transmitting antenna 105, for example, using an Analog Ping. This measurement result is used when executing foreign object detection processing using the Q-factor measurement method. Depending on the version of the WPC standard, the above-mentioned Selection phase may be included as part of the above-mentioned Ping phase and may be called the Ping phase.

[0060] In the configuration phase, TX100 identifies RX200 and acquires device configuration information (capability information) from RX200. RX200 transmits an ID Data packet and a Configuration Data packet. The ID Data packet contains identifier information of RX200, and the Configuration Data packet contains device configuration information (capability information) of RX200. Upon receiving the ID Data packet and Configuration Data packet signals, TX100 responds with an acknowledgement (positive response ACK). Then, the configuration phase ends.

[0061] In the negotiation phase, the GP value is determined based on the GP value requested by the RX 200, the power transmission capability of the TX 100, and the like. The TX 100 also receives an FOD Status Data packet from the RX 200, including the Reference Quality Factor Value and Reference Resonance Frequency Value. In the Q-value measurement method, the presence or absence of a foreign object is determined based on a threshold value based on the Reference Quality Factor Value and Reference Resonance Frequency Value. The TX 100 executes foreign object detection processing using the Q-value measurement method in accordance with the request from the RX 200. The WPC standard also prescribes a method of transitioning to a power transfer phase once, and then performing the same processing as in the negotiation phase again at the request of the RX 200. The phase transitioning from the power transfer phase and performing these processing is called a renegotiation phase.

[0062] In the calibration phase, calibration processing using the power loss method (hereinafter referred to as "CAL processing using the power loss method") is performed based on the WPC standard. In addition, the RX 200 notifies the TX 100 of a predetermined received power value, and the TX 100 makes adjustments to enable efficient power transmission. The predetermined received power value is, for example, the received power value in a light load state (light load state) or a maximum load state (connected load state). The received power value notified to the TX 100 is used for foreign object detection processing using the power loss method.

[0063] In the Power Transfer phase, the TX100 and the RX200 perform control for starting and continuing power transmission, as well as error processing and stopping power transmission due to a full charge. The TX100 and the RX200 perform communication processing for these power transmission and reception control operations. For example, using the power transmitting antenna 105 and the power receiving antenna 205 used when performing wireless power transmission based on the WPC standard, communication is performed by superimposing a signal on electromagnetic waves transmitted from the power transmitting antenna 105 or the power receiving antenna 205. Note that the range in which communication based on the WPC standard between the TX100 and the RX200 is possible is the same as the power transmission range of the TX100. Note that depending on the version of the WPC standard, the above-mentioned Calibration phase may also be called the Power Transfer phase as part of the above-mentioned Power Transfer phase.

[0064] Next, the function of the control unit of the TX 100 will be described with reference to Fig. 6. Fig. 6 is a block diagram showing an example of the functional configuration of the control unit 101 of the power transmitting device 100 (TX 100). The control unit 101 has a communication control unit 301, a power transmission control unit 302, a measurement unit 303, a setting unit 304, and a state detection unit 305. The communication control unit 301 controls communication with the RX 200 based on the WPC standard via the first communication unit 104, or controls communication with the RX 200 via the second communication unit 109.

[0065] The power transmission control unit 302 controls the power transmission unit 103 to control power transmission to the RX 200. The measurement unit 303 measures a waveform attenuation index, which will be described later. The measurement unit 303 also measures the power transmitted to the RX 200 via the power transmission unit 103, and measures the average transmitted power per unit time. The measurement unit 303 also measures a quality factor related to the power transmitting antenna 105. The measurement unit 303 also measures temperatures using temperature sensors arranged at multiple locations on the TX 100. The measurement unit 303 also measures a quantity (e.g., a coupling coefficient) that represents the electromagnetic coupling state between the power transmitting antenna 105 and the power receiving antenna 205.

[0066] The setting unit 304 calculates and sets a threshold for foreign object detection in the Q-factor measurement method and a threshold for foreign object detection in the power loss method using the above-described method. The setting unit 304 also sets a threshold for foreign object detection in the waveform attenuation method described below. The setting unit 304 also calculates and sets a threshold for foreign object detection or a threshold for detecting a misalignment between the TX 100 and the RX 200 based on, for example, the coupling coefficient between the power transmitting antenna 105 and the power receiving antenna 205 measured by the measurement unit 303. The setting unit 304 also calculates and sets a threshold for foreign object detection or a threshold for detecting a misalignment between the TX 100 and the RX 200 based on, for example, the temperature of the power transmitting device measured by the measurement unit 303.

[0067] The status detection unit 305 detects the status of the TX 100 and the RX 200. For example, the status detection unit 305 detects a foreign object present between the TX 100 and the RX 200, and also detects a misalignment between the power transmitting antenna 105 and the power receiving antenna 205. More specifically, the status detection unit 305 can perform status detection processing based on the power loss method, the Q-factor measurement method, the waveform attenuation method, the temperature measured in the TX 100, and the electromagnetic coupling state (e.g., the coupling coefficient) between the power transmitting antenna 105 and the power receiving antenna 205. The status detection unit 305 can also perform foreign object detection and detection processing of a misalignment between the power transmitting antenna 105 and the power receiving antenna 205 using other methods. For example, in a TX 100 equipped with an NFC communication function, the status detection unit 305 performs status detection processing using an opposite device detection function according to the NFC standard. Furthermore, the state detection unit 305 can detect the presence or absence of a foreign object and the electromagnetic coupling state between the power transmitting antenna and the power receiving antenna, as well as detect changes in the state of the TX 100. For example, the state detection unit 305 can detect an increase or decrease in the number of RX 200 on the TX 100.

[0068] The setting unit 304 sets a threshold value that serves as a reference for determining the presence or absence of a foreign object when the TX 100 performs status detection. Status detection includes, for example, status detection based on the power loss method, the Q-factor measurement method, or the waveform attenuation method, status detection based on the temperature measured by the TX 100, or status detection based on the coupling coefficient between the power transmitting antenna 105 and the power receiving antenna 205. The setting unit 304 can set a determination threshold value required for status detection processing using other methods. The status detection unit 305 can perform foreign object detection processing and detection processing of misalignment between the power transmitting antenna 105 and the power receiving antenna 205 based on the threshold value set by the setting unit 304 and the measurement results by the measurement unit 303. For example, the status detection unit 305 can acquire data such as a waveform attenuation index, transmission power, quality factor, temperature measured by the TX 100, and coupling coefficient between the power transmitting antenna 105 and the power receiving antenna 205 as measurement results from the measurement unit 303.

[0069] 6 can be realized using a program executed by a CPU or the like included in the control unit 101. Each process is executed in parallel according to an independent program while maintaining synchronization between the programs through event processing or the like. However, two or more of these processes may be incorporated into the processing of a single program.

[0070] Next, an example of the flow of processing related to power transmission and reception control executed by the TX 100 and the RX 200 will be described. Fig. 7 is a flowchart showing an example of power transmission control processing executed by the TX 100. This processing is realized, for example, by the control unit 101 of the TX 100 executing a program read from the memory 106. This processing can also be executed in response to the TX 100 being powered on, in response to the user of the TX 100 inputting an instruction to start a wireless power transmission application, or in response to the TX 100 being connected to a commercial power source and receiving power. This processing may also be started in response to some other trigger.

[0071] In S1201 of Fig. 7, the TX 100 executes the processes defined as the Selection phase and Ping phase of the WPC standard, and waits for the RX 200 to be placed. Specifically, the TX 100 repeatedly and intermittently transmits Analog Pings according to the WPC standard to detect an object present within the power transmission range. For example, the TX 100 can detect that the RX 200, a conductor piece, or the like has been placed on the charging stand 300. When the TX 100 detects the presence of an object within the power transmission range, it transmits a Digital Ping.

[0072] When a predetermined response to the Digital Ping is received, the TX100 determines that the detected object is the RX200 and that the RX200 has been placed on the charging stand 300. Here, the "predetermined response" is a Signal Strength (SIG) data packet transmitted by the RX200. This packet includes a Signal Strength Value that indicates the signal strength of the signal received by the RX200. The Signal Strength Value is calculated from the following parameters. That is, the parameters are the voltage (rectifier output voltage) output by the rectifier (rectifier) ​​of the power receiving unit 203 measured by the RX200, the voltage (open circuit voltage) of an open circuit including the power receiving antenna 205 measured by the RX200, or the received power value measured by the RX200, etc.

[0073] Before transmitting the Digital Ping, the TX 100 measures the Quality Factor of the power transmitting antenna 105. The measurement result is used when executing the foreign object detection process using the Q-factor measurement method.

[0074] After the placement of the RX 200 is detected, in S1202 the TX 100 acquires identification information from the RX 200 through communication in the configuration phase defined by the WPC standard. In the configuration phase, the RX 200 transmits an Identification Data Packet (ID Packet) to the TX 100. The ID Packet stores a Manufacturer Code and a Basic Device ID, which are identification information for each individual RX 200, as well as information elements that can identify the version of the WPC standard that is supported.

[0075] Furthermore, the RX200 transmits a Configuration Data Packet to the TX100. The Configuration Data Packet includes the following capability information of the RX200: Maximum Power Value or Reference Power, which is a value specifying the maximum power that the RX200 can supply to a load Information indicating whether the RX200 has a negotiation function of the WPC standard Parameters used in frequency shift keying, which is a communication modulation method used when the TX100 transmits information to the RX200 Information indicating whether the RX200 supports an out-of-band communication function

[0076] When the TX100 receives the packet from the RX200, it transmits an acknowledgement ACK to the RX200, and the Configuration phase ends. The TX100 may acquire the identification information of the RX200 by a method other than communication in the Configuration phase of the WPC standard. The identification information for each individual RX200 may be a Wireless Power ID. Alternatively, the identification information may be any other identification information capable of identifying each individual RX200, such as a Bluetooth Address (hereinafter referred to as "BD_ADDR") unique to the second communication unit 212 of the RX200. The BD_ADDR is an 8-byte address used in BLE. The BD_ADDR is a public address defined in the BLE standard that indicates, for example, the manufacturer of the RX 200 or individual identification information of the BLE communication function (the second communication unit 212). The BD_ADDR may also be a random address.

[0077] Next, in S1203, TX100 determines a GP through negotiation with RX200 based on the request from RX200 and the power transmission capacity of its own device. In S1203, communication in the negotiation phase of the WPC standard is performed. For example, RX200 notifies TX100 of the requested power value by sending a Specific Request to TX100. TX100 determines whether to accept the request based on the power transmission capacity of its own device and other conditions. If TX100 accepts the request, it sends an acknowledgment ACK to RX200, and if it does not accept the request, it sends a negative acknowledgment NACK or NAK to RX200. The GP value determined through negotiation with RX200 is the value requested by RX200 when TX100 accepts the request from RX200. If the TX 100 does not accept the request from the RX 200, the GP value may be set to a predetermined value (e.g., 5 watts) specified in the WPC standard. Also, if the TX 100 acquires information indicating that the RX 200 does not support the negotiation phase (e.g., S1302 described below), the TX 100 does not perform communication in the negotiation phase and sets the GP value to a predetermined value. The predetermined value is, for example, a value (e.g., 5 watts) specified in advance in the WPC standard.

[0078] In addition, TX100 performs foreign object detection processing using the Q-factor measurement method in accordance with a request from RX200. TX100 receives an FOD Status Data packet from RX200. This packet includes the above-mentioned Reference Quality Factor Value and Reference Resonance Frequency Value. TX100 then performs foreign object detection using the Q-factor measurement method. This foreign object detection is performed based on the following information: The Quality Factor and resonance frequency of the power transmitting antenna 105 measured by the TX 100 before transmitting a Digital Ping. A threshold value based on the Reference Quality Factor Value and Reference Resonance Frequency Value received by the TX 100 from the RX 200.

[0079] Next, in S1204, the TX100 and the RX200 perform processing (CAL processing) of the calibration phase of the WPC standard. In the calibration phase, the TX100 performs CAL processing of the Power Loss method based on the determined Reference Power value or GP value. First, the RX200 transmits a signal containing information about the received power in a light load state (hereinafter referred to as first reference received power information) to the TX100. A light load state is, for example, a load disconnection state, a load state in which the received power value of the RX200 is equal to or less than a first threshold, or a load state in which the received power value of the RX200 is within a predetermined range (hereinafter referred to as the "first range"). In this embodiment, the first reference received power information is 500 milliwatts. The first reference received power information is information contained in a Received Power Data packet (mode 1) specified in the WPC standard, but other messages may be used. Hereinafter, the Received Power Data packet (mode 1) will be referred to as RP1. The TX100 determines whether to accept the first reference received power information based on the Control Error Value contained in the Control Error (CE) data packet received from the RX200. If the TX100 accepts the first reference received power information, it transmits an acknowledgement (ACK) to the RX200. If the TX100 does not accept the first reference received power information, it transmits a negative acknowledgement (NAK) to the RX200.

[0080] Next, the RX 200 performs processing to transmit to the TX 100 a signal containing information regarding the received power in a load-connected state (hereinafter referred to as second reference received power information). The load-connected state is, for example, a maximum load state, a load state in which the transmitted power value is equal to or greater than a second threshold, or a load state in which the power received by the RX 200 is maximum. Here, "maximum power" refers to a power value close to the Reference Power. Alternatively, the load-connected state is a load state in which the received power value of the RX 200 is within a predetermined range (hereinafter referred to as the "second range"). Here, the second range is a range of power values ​​higher than the first range. In this embodiment, the second reference received power information is 15 watts. The second reference received power information is information included in the Received Power Data packet (mode 2) specified in the WPC standard, but other messages may be used.

[0081] Hereinafter, the Received Power Data packet (mode 2) is referred to as RP2. TX100 determines whether to accept the second reference received power information based on the Control Error Value included in the Control Error (CE) data packet received from RX200. If TX100 accepts the second reference received power information, it transmits an acknowledgement (ACK) to RX200. If TX100 does not accept the second reference received power information, it transmits a negative acknowledgement (NAK) to RX200. TX100 transmits an acknowledgement (ACK) in response to the second reference received power information from RX200, and completes the CAL process.

[0082] The above CAL process enables the TX100 to calculate the amount of power loss between the TX100 and the RX200 in the light load state and the load-connected state based on the transmission power value of the TX100 and the received power values ​​included in the first and second reference received power information. Furthermore, the TX100 can calculate the amount of power loss between the TX100 and the RX200 for all possible transmission powers of the TX100 by performing interpolation between multiple power loss amounts. All possible transmission powers of the TX100 are, for example, any power within a range in which the received power received by the RX200 in this embodiment is between 500 milliwatts and 15 watts.

[0083] Thereafter, in S1205, the TX 100 transmits power until the battery 207 of the RX 200 is fully charged. In S1205, communication in the Power Transfer phase of the WPC standard is performed. The RX 200 repeatedly transmits a Control Error Data Packet (hereinafter referred to as a "CE packet") to the TX 100 at time intervals of t_interval. The t_interval is a value defined in the WPC standard, and is, for example, 250 milliseconds. The CE packet includes a request for how much to increase or decrease the transmission power. The TX 100 adjusts the transmission power by controlling the current or voltage of the transmitting antenna 105 based on the received CE packet. In other words, the CE packet includes parameter data for adjusting the transmission power. By repeating this process, power is transmitted at an appropriate power in response to the request of the RX 200 in almost real time.

[0084] When the battery 207 is fully charged, the RX 200 transmits an End Power Transfer data packet (hereinafter referred to as an "EPT packet") to end the Power Transfer phase. The RX 200 can transmit an EPT packet for reasons other than full charge. Furthermore, when the Power Transfer phase ends, the TX 100 stops transmitting power to the RX 200 for charging.

[0085] Furthermore, if the TX 100 fails to receive the next CE packet after the time t_timeout has elapsed since the last CE packet was received, it determines that the RX 200 has been removed from the charging stand 300. In this case, the Power Transfer phase ends. t_timeout is a value defined in the WPC standard, and is, for example, 1500 milliseconds.

[0086] The RX 200 may transmit packets other than the CE packet to the TX 100 during the Power Transfer phase. For example, there is a Charge Status Data Packet that notifies the TX 100 of the status of the battery 207 of the RX 200. This packet stores a Charge Status Value that indicates the percentage of charge of the battery 207. When the TX 100 receives the Charge Status Data Packet, the TX 100 notifies the user of the charging status by, for example, displaying text or a graphic based on the Charge Status Value using the UI unit 110. The TX 100 may receive the Charge Status Data Packet at any time, and may notify the user at any timing.

[0087] In the Power Transfer phase, the TX 100 transmits power to the RX 200 and performs foreign object detection processing using the Power Loss method. For example, by CAL processing, the amount of power loss between the TX 100 and the RX 200 in the first detection state during power transmission processing is calculated from the difference between the transmitted power value and the received power value. The calculated amount of power loss corresponds to a reference amount of power loss in a state where no foreign object is present. Then, when the TX 100 determines that the difference between the amount of power loss between the TX 100 and the RX 200 measured during power transmission after CAL processing and the reference amount of power loss is equal to or greater than a threshold, it determines that the state is in the second detection state.

[0088] An example of the flow of processing related to power reception control executed by the RX 200 will be described with reference to Fig. 8. This processing is realized, for example, by the control unit 201 of the RX 200 executing a program read from the memory 208. In S1301, the RX 200 executes processing defined as the Selection phase and Ping phase of the WPC standard, and waits for the RX 200 to be placed on the TX 100. The RX 200 detects that it has been placed on the TX 100, for example, by detecting a Digital Ping from the TX 100.

[0089] When the RX200 detects that its own device has been placed on the TX100, it transmits a signal including its own device identification information to the TX100 using an ID packet and a configuration data packet in S1302. The identification information of the RX200 may be transmitted by a method other than communication in the configuration phase of the WPC standard. Also, other identification information such as BD_ADDR may be used as long as it is information that can identify each individual RX200. Also, the RX200 can transmit information other than the identification information to the TX100 in S1302.

[0090] Next, in S1303, the RX 200 transmits a signal including information on the requested power value to the TX 100, and negotiates with the TX 100 to determine the GP. In S1303, communication in the negotiation phase of the WPC standard is performed. The RX 200 transmits an FOD Status Data packet to the TX 100. This packet includes a Reference Quality Factor Value and a Reference Resonance Frequency Value.

[0091] Next, in S1304, the RX200 and the TX100 perform processing of the Calibration phase of the WPC standard (CAL processing). The processing performed by the RX200 in this phase is as described above. Thereafter, in S1305, the RX200 receives power until the battery 207 is fully charged. The processing performed by the RX200 in this phase is as described above. In the Power Transfer phase, the RX200 and the TX100 perform foreign object detection processing using the Power Loss method. In S1305, the RX200 repeatedly transmits a CE packet at intervals of t_interval, and finally transmits an EPT packet to the TX100, thereby completing the processing.

[0092] As described above, the Power Loss method is a method of detecting a foreign object based on the results of measuring the amount of power loss during power transmission from the TX 100 to the RX 200. This method has the disadvantage that the accuracy of foreign object detection decreases when the TX 100 is transmitting a large amount of power, but has the advantage that high power transmission efficiency can be maintained because foreign object detection processing can be performed while power transmission is continuing.

[0093] However, foreign object detection using only the Power Loss method during the Power Transfer phase may result in erroneous detection of a foreign object or in an erroneous determination that a foreign object is not present even though a foreign object is actually present. For example, consider a case where a foreign object is present near the TX 100 and the RX 200 during power transmission in the Power Transfer phase. In this case, heat generation from the foreign object may increase, so improving the accuracy of foreign object detection during the Power Transfer phase is required. Therefore, a foreign object detection method using the waveform attenuation method will be described. This method allows the TX 100 to detect a foreign object based on the attenuation state (envelope) of the power transmission waveform (voltage waveform or current waveform) related to power transmission to the RX 200. In other words, foreign object detection is possible without using a newly defined foreign object detection signal or the like.

[0094] FIG. 9 is a diagram illustrating the principle of foreign object detection using the waveform attenuation method. This diagram illustrates an example of foreign object detection using a transmission waveform associated with power transmission from a power transmitting device 100 to a power receiving device 200. In FIG. 9 , the horizontal axis represents time, and the vertical axis represents voltage or current. Waveform 600 in FIG. 9 illustrates, for example, the change over time in the voltage value of a high-frequency voltage applied to the power transmitting antenna 105 of the TX 100. The TX 100, which is transmitting power to the RX 200 via the power transmitting antenna 105, stops transmitting power at time T0. At time T0, the power supply from the power supply unit 102 is stopped, and the power supply to the power transmitting antenna 105 is also stopped. The frequency f1 of the transmission wave before power transmission is stopped at time T0 is a fixed frequency between 87 kHz and 205 kHz, for example, as used in the WPC standard. Point 601 on the waveform 600 is a point on the envelope of the high-frequency voltage and corresponds to the voltage value A1 at time T1. At point 601, (T1, A1) indicates that the voltage value at time T1 is A1. Point 602 on waveform 600 is a point on the envelope of the high-frequency voltage and corresponds to voltage value A2 at time T2. At point 602, (T2, A2) indicates that the voltage value at time T2 is A2.

[0095] The Quality Factor (Q-factor, Q value) of the transmitting antenna 105 can be found based on the change over time in the voltage value after time T0. For example, the TX 100 calculates the Quality Factor using Equation 1 based on the time and voltage values ​​at points 601 and 602 on the envelope of the high-frequency voltage, and the frequency f2 of the high-frequency voltage after power transmission is stopped at time T0. Q=π f2 (T2-T1) / ln(A1 / A2) (Equation 1) In Equation 1, ln represents a natural logarithm function.

[0096] It should be noted that the frequency (f1) of the transmitting wave when the TX 100 is transmitting power to the RX 200 may differ from the frequency (f2) of the transmitting wave when the TX 100 stops transmitting power to the RX 200.

[0097] The Quality Factor value decreases when a foreign object is present near the TX 100 and the RX 200. This is because the foreign object causes energy loss. Therefore, when focusing on the slope of the voltage attenuation, the slope of the line connecting points 601 and 602 is steeper when a foreign object is present than when no foreign object is present. When energy loss occurs due to a foreign object, the attenuation rate of the amplitude of the waveform 600 increases. For example, in the waveform attenuation method, the presence or absence of a foreign object can be determined based on the attenuation state of the voltage value between points 601 and 602. The actual presence or absence of a foreign object can be determined by comparing some numerical value representing the attenuation state. For example, when using the Quality Factor for determination, a lower Quality Factor value than the reference value indicates a higher waveform attenuation rate (the degree of decrease in waveform amplitude per unit time).

[0098] As another example, there is a method of making a determination using the slope of the line connecting points 601 and 602, calculated by (A1-A2) / (T2-T1). Furthermore, if the times (T1 and T2) at which the voltage value decay state is measured are fixed, the presence or absence of a foreign object can be determined using the difference in voltage values ​​(A1-A2) or the ratio of voltage values ​​(A1 / A2). Alternatively, if the voltage value A1 immediately after power transmission is stopped is constant, the presence or absence of a foreign object can be determined using the voltage value A2 after a predetermined time has elapsed. Alternatively, the presence or absence of a foreign object can be determined using the time (T2-T1) that elapses until the voltage value A1 reaches the predetermined voltage value A2.

[0099] The waveform attenuation method can determine the presence or absence of a foreign object based on the attenuation state of the waveform during a power transmission outage. Indicators such as the Quality Factor that represent the attenuation state are collectively referred to as "waveform attenuation indicators" in this embodiment. Although the vertical axis of FIG. 9 represents the voltage value of the high-frequency voltage applied to the power transmitting antenna 105 of the TX 100 in the above description, the vertical axis of FIG. 9 may also represent the current value flowing through the power transmitting antenna 105. As with the voltage value, the attenuation state of the current value during a power transmission outage varies depending on the presence or absence of a foreign object. When a foreign object is present, the waveform attenuation rate is higher than when a foreign object is not present. Therefore, a foreign object can be detected by applying the same method described above to the temporal change in the current value flowing through the power transmitting antenna 105. That is, the presence or absence of a foreign object can be determined and foreign object detection can be performed using the Quality Factor calculated from the current waveform, the slope of the attenuation of the current value, the difference in the current value, the ratio of the current value, the absolute value of the current value, or the time until the current value reaches a predetermined value as a waveform attenuation indicator.

[0100] There is also a method based on both the attenuation state of the voltage value and the attenuation state of the current value. In this method, the presence or absence of a foreign object can be determined using an evaluation value calculated from the waveform attenuation index of the voltage value and the waveform attenuation index of the current value. Note that the present invention is not limited to the example in which the waveform attenuation index is measured during a period in which the TX 100 temporarily suspends power transmission. The waveform attenuation index may also be measured during a period in which the TX 100 temporarily reduces the power supplied from the power supply unit 102 from a predetermined power level to a lower power level. That is, the waveform attenuation index may also be measured during a period in which the power supply for power transmission to the power transmitting antenna 105 is temporarily reduced from a predetermined power level to a lower power level. Furthermore, the power transmitting unit 103 may limit or stop the power supply for power transmission to the power transmitting antenna 105 as described above based on an instruction signal from the control unit 101. In the above example, the voltage or current values ​​are measured at two points in time during the period in which the TX 100 limits power transmission. However, the voltage or current values ​​may also be measured at three or more points in time.

[0101] A foreign object detection method based on a power transmission waveform using the waveform attenuation method will be described with reference to Fig. 10. The power transmission waveform shown in Fig. 10 is a power transmission waveform used when performing foreign object detection using the waveform attenuation method, with the horizontal axis representing time and the vertical axis representing the voltage value or current value of the power transmitting antenna 105.

[0102] During the transient response period immediately after the TX100 starts power transmission, the transmission waveform is not stable. Therefore, during this transient response period, the RX200 controls the TX100 so that it does not communicate with the TX100 (communication by amplitude modulation or load modulation). Furthermore, the TX100 controls the RX200 so that it does not communicate with the RX200 (communication by frequency shift keying). Hereinafter, this period is referred to as the communication prohibition period. However, during the communication prohibition period, the TX100 transmits power to the RX200. Then, after the communication prohibition period has elapsed, the TX100 transmits power to the RX200. Hereinafter, this period is referred to as the power transmission period. When the TX100 receives a foreign object detection execution request (packet, command) from the RX200, the TX100 temporarily suspends power transmission after a predetermined period has elapsed or temporarily reduces the transmission power. Hereinafter, this predetermined period is referred to as the preparation period. During the preparation period, RX 200 controls TX 100 not to perform communication using amplitude modulation, load modulation, or backscatter modulation. Also, TX 100 controls RX 200 not to perform communication using frequency shift keying. By controlling not to perform communication during the preparation period, disturbance of the transmission wave waveform is suppressed, and TX 100 can more accurately calculate the waveform attenuation index of the transmission wave waveform, which will be described later.

[0103] The foreign object detection execution request (packet, command) may be RP0, RP1, or RP2. When the power transmitting unit 103 of the TX 100 receives the foreign object detection execution request, it temporarily suspends power transmission or temporarily reduces the transmission power, thereby attenuating the amplitude of the transmitted wave. The period from when the TX 100 temporarily suspends power transmission or temporarily reduces the transmission power to when it resumes power transmission or starts restoring the transmission power is called the transmission power control period.

[0104] Here, "resuming power transmission" means that the TX 100 increases the transmission power to a predetermined value. Alternatively, the period from when the TX 100 temporarily sets or reduces the value of the inverter input voltage input to the inverter included in the power transmitting unit 103 to 0 volts to when the input voltage value is restored to a predetermined value is hereinafter referred to as the transmission power control period. Alternatively, the period from when the TX 100 temporarily sets or reduces the value of the inverter output voltage output by the inverter included in the power transmitting unit 103 to when the output voltage value is restored to a predetermined value is hereinafter referred to as the transmission power control period. Furthermore, the control by the TX 100 to temporarily stop or temporarily reduce the transmission power is referred to as transmission power control. The TX 100 calculates a waveform attenuation index based on the attenuated waveform, and compares the calculated waveform attenuation index with a predetermined threshold to determine whether a foreign object is present or the possibility (probability) that a foreign object exists (hereinafter also referred to as foreign object determination). During the transmission power control period, the RX 200 controls the TX 100 so that it does not communicate using amplitude modulation, load modulation, or backscatter modulation. The TX 100 also controls the RX 200 so that it does not communicate using frequency shift keying. By controlling communication not to occur during the transmission power control period, disturbances in the transmission wave waveform are suppressed, and the TX 100 can more accurately calculate the waveform attenuation index of the transmission wave waveform. Foreign object detection can be performed during the transmission power control period, the communication prohibition period, or the power transmission period.

[0105] After the transmission power control period has elapsed, if no foreign object is detected, the TX 100 resumes power transmission or controls the restoration of the transmission power. During the transient response period immediately after this control is started, the transmission waveform is not stable, so this period becomes a communication prohibited period. After that, the TX 100 transitions to a power transmission period in which stable power transmission is performed from the TX 100 to the RX 200.

[0106] As described above, the TX100 repeatedly controls the power transmission start, communication prohibition period, power transmission period, preparation period, and transmission power control period. The TX100 calculates a waveform attenuation index based on the attenuated waveform at a predetermined timing and performs foreign object determination based on the result of comparing the calculated waveform attenuation index with a predetermined threshold. In other words, foreign object determination can be performed based on voltage or current values ​​at two or more points in time during a predetermined period in which power transmission is restricted (including power transmission suspension). Furthermore, during the preparation period, transmission power control period, and communication prohibition period, the RX200 controls the TX100 so as not to communicate with the RX200 using amplitude modulation, load modulation, or backscatter modulation. Furthermore, the TX100 controls the RX200 so as not to communicate with the RX200 using frequency shift keying. In other words, the TX100 controls the RX200 so as not to communicate with the RX200 during a predetermined first period after receiving an execution request (packet, command) from the RX200. The WPC standard specifies a period during which the TX 100 cannot transmit packets to the RX 200 after the TX 100 receives a packet other than an execution request (packet, command) from the RX 200 during the Power Transfer phase. The first period is a period longer than the period.

[0107] Furthermore, the RX 200 is controlled not to communicate with the TX 100 for a predetermined second period after transmitting an execution request (packet, command) to the TX 100. The WPC standard specifies a period during which the RX 200 cannot transmit packets to the TX 100 after transmitting a packet other than an execution request (packet, command) to the TX 100 during the Power Transfer phase. The second period is longer than the period.

[0108] During the transmission power control period, if elements such as the power receiving unit 203, the charging unit 206, and the battery 207 are connected to the power receiving antenna 205 and the resonant capacitor 211 of the RX 200, the waveform attenuation index is affected by the loads of these elements. That is, the value of the waveform attenuation index changes depending on the states of the power receiving unit 203, the charging unit 206, and the battery 207. As a result, even if the value of the waveform attenuation index is large, it is difficult to distinguish whether this is due to the influence of a foreign object or a change in the state of the power receiving unit 203, the charging unit 206, the battery 207, etc. Therefore, when measuring the waveform attenuation index to detect a foreign object, the control unit 201 of the RX 200 turns off the first switch unit 209 during the preparation period. The RX 200 transmits an execution request (packet, command) to the TX 100 and executes the above process during the preparation period. Alternatively, the RX 200 executes the above process simultaneously with transmitting the execution request (packet, command) to the TX 100. This makes it possible to suppress the influence of the battery 207. Furthermore, the same effect can be achieved by switching the first switch unit 209 to a light load state (light load state) instead of disconnecting the first switch unit 209. Furthermore, the same effect can be achieved by the RX 200 controlling the load so that the received power is minimized instead of disconnecting the first switch unit 209. Alternatively, the same effect can be achieved by the RX 200 controlling the load so that the received power is within a predetermined range or is equal to or less than a predetermined threshold instead of disconnecting the first switch unit 209. Here, the "power within a predetermined range" or "power equal to or less than a predetermined threshold" refers to a power that is approximately 10% of the Reference Power. Alternatively, the RX 200 may control the load so that a predetermined power is supplied to the load instead of disconnecting the first switch unit 209. These can be achieved by controlling the first switch unit 209. The RX 200 maintains the above-described control during the transmission power control period, and then cancels the above-described control at a timing after power transmission is resumed, and performs control to return to the original state.

[0109] Alternatively, the control unit 201 turns on the second switch unit 210 to short-circuit it, causing a current to flow through a closed loop formed by the power receiving antenna 205, the resonant capacitor 211, and the second switch unit 210. This makes it possible to suppress the effects of the power receiving unit 203, the charging unit 206, and the battery 207. The RX 200 transmits a foreign object detection execution request (command) to the TX 100, and the above processing is performed during the preparation period. Alternatively, the RX 200 executes the above processing simultaneously with transmitting the execution request (packet, command) to the TX 100. The RX 200 maintains the above control during the transmission power control period. Then, after power transmission is resumed, the RX 200 releases the above control and controls the RX 200 to return to the original state. Obtaining a waveform attenuation index based on the transmission waveform measured with the first switch unit 209 disconnected or with the second switch unit 210 turned on and short-circuited (connected) enables more accurate foreign object detection. Alternatively, by both disconnecting the first switch section 209 and shorting (connecting) the second switch section 210, foreign matter detection can be performed with even higher accuracy.

[0110] Alternatively, during the preparation period, the RX200 may transition to a low power consumption mode or control the power consumption to be constant while the first switch unit 209 is turned ON to short-circuit and the second switch unit 210 is turned OFF to disconnect. The RX200 transmits an execution request (packet, command) to the TX100 and executes the above processing during the preparation period. Alternatively, the RX200 executes the above processing simultaneously with transmitting the execution request (packet, command) to the TX100. The RX200 maintains the above control during the transmission power control period. Then, after power transmission is resumed, the RX200 releases the above control and controls the RX200 to return to its original state. If the power consumption of the RX200 is not constant or if a large amount of power is consumed, the value of the waveform attenuation index based on the attenuated waveform is affected by fluctuations in power consumption. To mitigate this effect, it is effective to limit or stop the operation of software applications running on the RX200 or to set the hardware function blocks of the RX200 to a low power consumption mode or an operation suspension mode. By detecting a foreign object using a waveform attenuation index based on a transmission waveform measured while the power consumption of the RX200 is suppressed, more accurate foreign object detection is possible.

[0111] Similarly, in the TX 100, if elements such as the power transmitting unit 103, the first communication unit 104, and the power supply unit 102 are connected to the power transmitting antenna 105 and the resonant capacitor 107 of the TX 100 when measuring the waveform attenuation index, the waveform attenuation rate will be affected by these elements. That is, the value of the waveform attenuation index will change depending on the states of the power transmitting unit 103, the first communication unit 104, and the power supply unit 102. As a result, even if the value of the waveform attenuation index is large, for example, it will be difficult to distinguish whether this is due to the influence of a foreign object or the influence of the power transmitting unit 103, the first communication unit 104, and the power supply unit 102.

[0112] Therefore, when the TX 100 receives a foreign object detection execution request (command) from the RX 200, the control unit 101 turns on the switch unit 108 during the preparation period. This allows current to flow through the closed loop circuit formed by the power transmitting antenna 105, the resonant capacitor 107, and the switch unit 108. This makes it possible to suppress the influence of the power transmitting unit 103, the first communication unit 104, and the power supply unit 102 when measuring the waveform attenuation index in the TX 100.

[0113] Alternatively, a switch (not shown) may be provided between the power transmitting antenna 105 and the power transmitting unit 103, and the influence of the power supply unit 102, the power transmitting unit 103, and the first communication unit 104 may be suppressed by disconnecting the switch during the preparation period. Alternatively, a switch may be provided between the power transmitting unit 103 and a closed loop circuit formed by the power transmitting antenna 105, the resonant capacitor 107, and the switch unit 108. When measuring the waveform attenuation index and detecting a foreign object, the TX 100 controls the switch to disconnect the closed loop circuit from the power transmitting unit, thereby suppressing the influence. The TX 100 maintains the above-described control during the transmission power control period. Then, after power transmission is resumed, the TX 100 releases the above-described control and controls the system to return to the original state. By implementing the above methods alone or in combination, more accurate foreign object detection is possible.

[0114] As described above, at least one of the following states is realized: a short-circuit (connected) state with the switch unit 108 turned on; a disconnected state with the switch relating to the power transmitting antenna 105 and the power transmitting unit 103; and a disconnected state with the switch relating to the closed loop circuit and the power transmitting unit 103. This enables more accurate foreign object detection.

[0115] Next, a method for setting a threshold value for the waveform attenuation index for detecting the status of the TX 100 and RX 200 and determining whether a foreign object is present based on the waveform attenuation method will be described. The measured value of the waveform attenuation index is compared with a predetermined threshold, and foreign object detection is possible based on the comparison result. A first threshold setting method is a method in which the TX 100 holds a predetermined threshold value, which is a common value independent of the RX 200 to which power is transmitted. This threshold value is a fixed value or a variable value determined by the TX 100 depending on the situation. The waveform attenuation rate of the transmission waveform during the transmission power control period increases when a foreign object is present. Therefore, the value of the waveform attenuation index acquired when no foreign object is present is held, and this value is set as the threshold. By comparing the measured value of the waveform attenuation index with the threshold, it is possible to determine whether a foreign object is present or whether there is a high possibility that a foreign object is present. For example, if a Q value is used as the waveform attenuation index, the TX 100 compares the measured value of the Q value with a predetermined threshold. The threshold value is set based on the measured value in the first detection state or a value that takes measurement error into account for the measured value. If the measured Q value is smaller than the threshold, it is determined that "foreign matter is present" or "there is a high possibility that a foreign matter exists." If the measured Q value is equal to or greater than the threshold, it is determined that "foreign matter is not present" or "there is a low possibility that a foreign matter exists."

[0116] The second threshold setting method is a method in which the TX100 adjusts and determines the threshold based on information transmitted from the RX200. A notable difference from the first threshold setting method is that the value of the waveform attenuation index may differ depending on the RX200 to which power is transmitted and placed on the TX100. This is because the electrical characteristics of the RX200 coupled via the TX100's power transmitting antenna affect the value of the waveform attenuation index. For example, if a Q-factor is used as the waveform attenuation index, the Q-factor measured by the TX100 when no foreign object is present may differ depending on the RX200 placed on the TX100. Therefore, the RX200 stores Q-factor information for each TX100 when the RX200 is placed on the TX100 in the absence of a foreign object, and notifies the TX100 of the Q-factor information. The TX100 adjusts and determines the threshold for each RX200 based on the Q-factor information received from the RX200.

[0117] More specifically, in the Negotiation phase, the TX100 receives an FOD Status Data Packet containing information about the Reference Quality Factor Value, and adjusts and determines the threshold value in the Q-factor measurement method. The Reference Quality Factor Value is the Quality Factor that can be measured at the terminal of the transmitting antenna of the test TX100 when the RX200 is placed on the test TX100 and no foreign object is present nearby. The TX100 considers this Reference Quality Factor Value to be equivalent to "Q-factor information when the RX200 is placed on the TX100 in the absence of a foreign object," and uses it to determine the threshold value. In other words, the TX100 can adjust and determine the threshold value for foreign object determination using the waveform attenuation method based on the Reference Quality Factor Value. The Reference Quality Factor Value transmitted from the RX200 to the TX100 during the negotiation phase is information originally used for foreign object detection using the Q-factor measurement method, which measures the Q-factor in the frequency domain. However, when the Q-factor is used as the waveform attenuation index, although the method for deriving the Q-factor is different, the Q-factor can also be calculated using the waveform attenuation method, which measures the Q-factor in the time domain, for example, using Equation 1 from the waveform in FIG. 9 . Therefore, it is possible to set the Q-factor threshold value for the waveform attenuation method based on the Reference Quality Factor Value. The waveform attenuation index value obtained by adding a predetermined value (a value corresponding to a measurement error) to the Reference Quality Factor Value may be set as the threshold value for determining foreign matter.

[0118] In this way, the TX 100 sets the Q-value threshold for the waveform attenuation method based on the information already transmitted from the RX 200 to the TX 100 in the negotiation phase, eliminating the need to perform new measurements or other processing to set the threshold. As a result, the threshold can be set in a shorter time.

[0119] In the third threshold setting method, the TX 100 measures the waveform attenuation index in a state where no foreign object is present, and adjusts and determines the threshold based on the information on the measurement result. The timing for pre-measuring the waveform attenuation rate in a state where no foreign object is present will be described below. In the negotiation phase of the WPC standard, if foreign object detection using the Q-value measurement method is performed and it is determined that no foreign object is present, the system proceeds to the calibration phase and the power transfer phase. In other words, the fact that the phase has progressed to the negotiation phase or later means that it has been determined that no foreign object is present as a result of foreign object detection using the Q-value measurement method. There is a high possibility that the waveform attenuation index in a state where no foreign object is present can be measured in any of the negotiation phase, calibration phase, and power transfer phase. Therefore, the timing for measuring the waveform attenuation index in the absence of a foreign object may be any one of the negotiation phase, the calibration phase, and the power transfer phase.

[0120] For example, assume that the waveform attenuation index is measured in the power transfer phase. The timing for measuring the waveform attenuation index in the absence of a foreign object is set to the first stage of the power transfer phase. The reason for this is that the more time that passes since the Q-factor measurement method determines that no foreign object is present, the higher the probability that a foreign object will be present near the TX100 and the RX200. The timing is specified by the RX200 or the TX100, and the TX100 measures the waveform attenuation index at that time and sets the value of the waveform attenuation index as the threshold. If the RX200 specifies the timing, the RX200 notifies the TX100 of the timing by transmitting a predetermined packet. If the TX100 specifies the timing, the TX100 notifies the RX200 of the timing by transmitting a predetermined packet. Note that a value obtained by adding a predetermined value (a value corresponding to a measurement error) to the waveform attenuation index may be set as the threshold for foreign object determination.

[0121] The fourth threshold setting method is a method in which the TX100 adjusts and determines the threshold according to the transmission power. The value of the waveform attenuation index may differ depending on the transmission power of the TX100. The reason for this is that the amount of heat generated and various characteristics of the electrical circuit of the TX100 change depending on the transmission power of the TX100, and these affect the value of the waveform attenuation index. The TX100 measures the waveform attenuation index for each transmission power and adjusts and determines the threshold based on the measurement results, thereby enabling more accurate foreign object detection.

[0122] Fig. 11 is a diagram illustrating a method for setting a threshold value for foreign object detection for each transmission power of the TX 100 in the waveform attenuation method. In Fig. 11, the horizontal axis represents the transmission power of the TX 100, and the vertical axis represents the waveform attenuation index (waveform attenuation rate) of the voltage waveform or current waveform. On the graph line represented by the straight line segment 1102, point 1100 corresponds to the transmission power value Pt1 and the waveform attenuation index δ1, and point 1101 corresponds to the transmission power value Pt2 and the waveform attenuation index δ2. On the graph line, point 1103 corresponds to the transmission power value Pt3 and the waveform attenuation index δ3.

[0123] First, the RX200 controls the RX200 so that it is in a light-load state when power is transmitted from the TX100. In the light-load state, either no power is supplied to the load of the RX200, only power below a threshold is supplied, or power within a predetermined range (hereinafter referred to as the "third range") is supplied. The transmission power value of the TX100 in this state is Pt1. The RX200 then transmits a packet to the TX100 requesting measurement of the waveform attenuation index. Upon receiving this packet, the TX100 stops power transmission or reduces the transmission power while the load of the RX200 is controlled to a light-load state, and measures the waveform attenuation index δ1. At this time, the TX100 recognizes the transmission power value Pt1 and stores in memory a calibration point CP1100 that associates the transmission power value Pt1 with the waveform attenuation index δ1. Next, the RX200 controls the load connection state. The load connection state is a state in which, when power is transmitted from the TX100, maximum power is supplied to the load of the RX200, power equal to or greater than a predetermined threshold is supplied, or power within a predetermined range (hereinafter referred to as the "fourth range") is supplied. Here, the "fourth range" is a power range greater than the "third range." The transmission power value of the TX100 in this state is Pt2. The RX200 then transmits a packet to the TX100 requesting measurement of the waveform attenuation index. Upon receiving this packet, the TX100 stops power transmission or reduces the transmission power while the load of the RX200 is controlled to the load connection state, and measures the waveform attenuation index δ2. At this time, the TX100 stores in memory a CP1101 that associates the transmission power value Pt2 with the waveform attenuation index δ2. The TX100 then linearly interpolates between CP1100 and CP1101 to generate a line segment 1102. Line segment 1102 shows the relationship between the transmission power in a first detection state in which no foreign object is present around TX 100 and RX 200 and the waveform attenuation index of the waveform observed by the transmitting antenna 105. Therefore, based on line segment 1102, TX 100 can estimate the waveform attenuation index of the waveform observed by the transmitting antenna 105 for each transmission power value in the first detection state.For example, for a transmission power value Pt3, the waveform attenuation index is estimated to be δ3 from point 1103 on line segment 1102 corresponding to Pt3. The TX 100 can calculate a threshold value used to determine the presence or absence of a foreign object for each transmission power value based on the estimation result. For example, a waveform attenuation index that is larger by a predetermined value (a value corresponding to a measurement error) than the estimated result of the waveform attenuation index in the first detection state for a certain transmission power value can be set as the threshold value for determining a foreign object.

[0124] The CAL process performed by the TX100 and the RX200 so that the TX100 can acquire a combination of a transmission power value and a waveform attenuation index is hereinafter referred to as the "CAL process of the waveform attenuation method." Furthermore, performing a calibration process again after a calibration process has been performed once and updating or adding calibration points is referred to as a recalibration process, abbreviated as a ReCAL process. In the above example, measurements were performed at two points, the transmission power values ​​Pt1 and Pt2. However, to improve accuracy, measurements may be performed at three or more points to calculate the waveform attenuation index for each transmission power. The RX200 may perform the light load state control and the load connection state control after notifying the TX100 of the execution of the control using a predetermined packet. Furthermore, either of the two controls may be performed first.

[0125] The calculation process of the threshold value used for foreign object determination for each load (or each transmission power value) described in this embodiment may be performed in the calibration phase. As described above, the TX100 acquires data required for foreign object detection using the power loss method in the calibration phase. At that time, the TX100 acquires data related to the received power value and power loss of the RX200 when the RX200 is in a light load state and when a load is connected. Therefore, measurements of CP1100 and CP1101 in FIG. 11 may be performed together with measurements of power loss when the RX200 is in a light load state and a load is connected in the calibration phase. For example, when the TX100 receives a signal containing first reference received power information from the RX200, it measures CP1100 in addition to the predetermined processing to be performed in the calibration phase. This first reference received power information is RP1 information specified in the WPC standard, but other messages may be used. Furthermore, when TX100 receives a signal having second reference received power information from RX200, it measures CP1101 in addition to the predetermined processing to be performed in the calibration phase. This second reference received power information is RP2 information specified in the WPC standard, but other messages may be used. Since there is no need to set aside a separate period for measuring CP1100 and CP1101, the measurements of CP1100 and CP1101 can be performed in a shorter time.

[0126] In this way, based on the information on the waveform attenuation index measured by the TX100 at each transmission power, the TX100 adjusts and sets the threshold value of the waveform attenuation index for each transmission power. For example, if a Q value is used as the waveform attenuation index, the TX100 compares the measured Q value with the threshold value determined by the above method. If the measured Q value is smaller than the threshold value, it is determined that "foreign object is present" or "there is a possibility that a foreign object exists." If the measured Q value is equal to or greater than the threshold value, it is determined that "no foreign object exists" or "there is a low possibility that a foreign object exists." In this way, a threshold value for each transmission power of the TX100 is set, enabling more accurate foreign object determination.

[0127] The threshold value for determining whether or not a foreign object is present is not limited to one, but multiple threshold values ​​can be set in stages. For example, a first threshold value can be set as a threshold value for determining whether or not an abnormal condition exists, a second threshold value can be set as a threshold value for determining whether or not an abnormal condition exists, a third threshold value can be set as a threshold value for determining whether or not an abnormal condition exists, and a fourth threshold value can be set as a threshold value for determining whether or not an abnormal condition exists.

[0128] Furthermore, performing the foreign object detection process only once may not be accurate. For example, when performing foreign object detection using the waveform attenuation method, if a single transmission power control is performed and a foreign object is determined based on the waveform attenuation index at that time, there is a possibility that the amplitude and phase of the transmitted wave may be disturbed during the transmission power control period. This may include noise contamination during the transmission power control period or misalignment of the RX 200 mounted on the TX 100. In this case, if the value of the waveform attenuation index calculated from the transmitted wave during a single transmission power control period is inaccurate, this may result in an erroneous foreign object determination. Therefore, the TX 100 performs transmission power control multiple times, measures the waveform attenuation index from the transmitted wave during multiple transmission power control periods, and enables more accurate foreign object determination based on the results of the multiple measurements.

[0129] Next, a first measurement method will be described as a method for measuring an indicator of the coupling state between the power transmitting antenna and the power receiving antenna. Hereinafter, the measurement performed by the first measurement method will be referred to as the first measurement. In wireless power transmission, power is transmitted by electromagnetically coupling the power transmitting antenna 105 and the power receiving antenna 205. An AC current is passed through the power transmitting antenna 105, changing the magnetic flux penetrating the power receiving antenna 205, thereby inducing a voltage in the power receiving antenna 205. The coupling coefficient (referred to as k or k value), which is an indicator of the coupling state between the power transmitting antenna and the power receiving antenna, is, for example, "k = 1" when all (100%) of the magnetic flux generated by the power transmitting antenna penetrates the power receiving antenna. Similarly, "k = 0.7" when 70% of the magnetic flux generated by the power transmitting antenna penetrates the power receiving antenna. In this case, the remaining (30%) magnetic flux generated by the power transmitting antenna is leakage magnetic flux. This is the magnetic flux generated by the power transmitting antenna that does not penetrate the power receiving antenna. Therefore, when the coupling state between the transmitting antenna and the receiving antenna is good and the k value is large, the transmission efficiency of power transmitted from the TX 100 to the RX 200 is high. Conversely, when the coupling state is poor and the k value is small, the transmission efficiency of power transmitted from the TX 100 to the RX 200 is low.

[0130] Factors that can decrease the value of the coupling coefficient include the presence of a foreign object (such as a metal piece) between the power transmitting antenna and the power receiving antenna, misalignment between the power transmitting antenna and the power receiving antenna, and an increase in the distance between the power transmitting antenna and the power receiving antenna. If a foreign object is present between the power transmitting antenna and the power receiving antenna, heat may be generated in the foreign object. Furthermore, misalignment or separation between the power transmitting antenna and the power receiving antenna increases leakage magnetic flux, which may generate significant noise in the surrounding area. When the k value is small, appropriate control is required to achieve safer, higher-quality wireless power transmission. In this embodiment, a process is performed to detect the coupling state (including the coupling coefficient) between the power transmitting antenna and the power receiving antenna in order to improve the detection accuracy for foreign objects and for cases where the misalignment or distance is large.

[0131] A method for measuring the coupling state indicator between the power transmitting antenna and the power receiving antenna will be described with reference to Fig. 12. Fig. 12(A) is an equivalent circuit diagram for explaining the first measurement method. The definitions of various quantities related to the power transmitting antenna (power transmitting coil) on the primary side (TX100) are shown below. r1: winding resistance of the power transmitting antenna L1: self-inductance of the power transmitting antenna V1: power transmitting voltage (input voltage) applied to the power transmitting antenna measured by the TX100

[0132] The definitions of the various quantities related to the receiving antenna (receiving coil) on the secondary side (RX200) are shown below: r2: winding resistance of the receiving antenna L2: self-inductance of the receiving antenna V2: receiving voltage (output voltage) applied to the receiving antenna measured by the RX200

[0133] The coupling coefficient k between the power transmitting antenna and the power receiving antenna can be calculated by the following formula 2: k=(V2 / V1)·√(L1 / L2) (Formula 2) The value of the coupling coefficient k is sometimes called the "k value."

[0134] When the TX100 calculates the coupling coefficient k, the RX200 notifies the TX100 of the measured receiving voltage V2 and the value of the self-inductance L2 of the receiving antenna that is stored in advance by the RX200. The TX100 calculates the k value using the measured transmitting voltage V1, the value of the self-inductance L1 of the transmitting antenna that is stored in advance, and the values ​​of the receiving voltage V2 and self-inductance L2 received from the RX200. Alternatively, the RX200 notifies the TX100 of a constant calculated using either or all of L1 and L2, and V2, and the TX100 can calculate the k value using the constant received from the RX200, V2, and the transmitting voltage V1 measured by the TX100.

[0135] On the other hand, when the RX200 calculates the coupling coefficient k, the TX100 notifies the RX200 of the measured power transmission voltage V1 and the value of the self-inductance L1 of the power transmitting antenna that is stored in advance. The RX200 calculates the k value using the measured power receiving voltage V2, the value of the self-inductance L2 of the power receiving antenna that is stored in advance, and the power transmitting voltage V1 and the value of the self-inductance L1 received from the TX100. Alternatively, the TX100 notifies the RX200 of a constant calculated using all or either of L1 and L2, and V1, and the RX200 can calculate the k value using the constant received from the TX100, V1, and the power receiving voltage V2 measured by the RX200.

[0136] The transmission voltage V1 can be calculated by the TX 100 by actually measuring the voltage applied to the power transmitting antenna or by the TX 100 from the set value of the transmission power. Alternatively, the transmission voltage V1 can be set as the set value of the transmission voltage during power transmission. Furthermore, the transmission voltage V1 applied to the power transmitting antenna can be calculated from the transmission voltage (denoted as V3) applied to a circuit (e.g., an inverter) included in the power transmitting unit 103 of the TX 100 and the voltage applied across the resonant capacitor 107. Here, the transmission voltage V3 applied to the circuit included in the power transmitting unit 103 of the TX 100 is, for example, the inverter input voltage input to the inverter included in the power transmitting unit 103 of the TX 100, or the inverter output voltage output by the inverter. In this case, the transmission voltage V3 can also be calculated by the TX 100 from the set value of the transmission power. Alternatively, the TX 100 can actually measure the transmission voltage V3 and the voltage applied across the resonant capacitor 107 and use these measurements to calculate the transmission voltage V1. Alternatively, the TX 100 may transmit the measured values ​​of the transmission voltage V3 and the voltage across the resonant capacitor 107 to the RX 200, and the RX 200 may calculate the k value by determining the transmission voltage V1.

[0137] Furthermore, when the TX100 or RX200 performs the first measurement, the RX200 may turn off the third switch unit 213 to open the terminals of the power receiving antenna 205. This allows both ends of the power receiving antenna to be open, as shown in FIG. 12A . Since the first measurement is not affected by the resonant capacitor 211, the power receiving unit 203, the charging unit 206, or the battery 207, the coupling coefficient k can be measured with higher accuracy. Furthermore, the power receiving voltage V2 applied to the power receiving antenna can be calculated from the power receiving voltage (denoted as V4) applied to a circuit (e.g., a rectifier) ​​included in the power receiving unit 203 of the RX200 and the voltage across the resonant capacitor 211. Here, the power receiving voltage V4 applied to the circuit included in the power receiving unit 203 of the RX200 is, for example, the rectifier input voltage input to the rectifier included in the power receiving unit 203 of the RX200. Alternatively, the receiving voltage V2 applied to the receiving antenna can be calculated from the receiving voltage (denoted as V5) of a circuit (e.g., a rectifier) ​​included in the power receiving unit 203 of the RX 200 and the voltage across the resonant capacitor 211. Here, the receiving voltage V5 applied to the circuit included in the power receiving unit 203 of the RX 200 is, for example, the rectifier output voltage output from the rectifier included in the power receiving unit 203 of the RX 200. In this case, the RX 200 may actually measure the receiving voltage V4 and the voltage across the resonant capacitor 211 and use these measurements to calculate the receiving voltage V2. Alternatively, the RX 200 may actually measure the receiving voltage V5 and the voltage across the resonant capacitor 211 and use these measurements to calculate the receiving voltage V2. Alternatively, the RX 200 may transmit the measured values ​​of the receiving voltage V4 and the voltage across the resonant capacitor 211 to the TX 100, and the TX 100 may calculate the receiving voltage V2, thereby calculating the k value. Alternatively, the RX 200 may transmit the measured received voltage V5 and the value of the voltage across the resonant capacitor 211 to the TX 100, and the TX 100 may calculate the k value by determining the received voltage V2.

[0138] Alternatively, when the TX100 or the RX200 performs the first measurement, the RX200 may be controlled to be in a light load state or a loaded state. By keeping the load state of the RX200 constant, it is possible to measure the coupling coefficient k with higher accuracy. Furthermore, the TX100 or the RX200 may be controlled to perform the first measurement when the RX200 is in both a light load state and a loaded state. Alternatively, the TX100 or the RX200 may be controlled to perform the first measurement when the RX200 is in each of three or more load states. By measuring the coupling states in the load states of multiple RX200 and determining the coupling state based on the measurements, it is possible to determine the coupling state with higher accuracy.

[0139] In addition to the coupling coefficient, there are several other indices that represent the electromagnetic coupling state between the power transmitting antenna and the power receiving antenna, and in this embodiment, these are collectively referred to as "coupling state indices." Each of the coupling state indices has a value that corresponds to the electromagnetic coupling state between the power transmitting antenna and the power receiving antenna.

[0140] The contents of this embodiment can also be applied to the case where other coupling state indices than the coupling coefficient are used.

[0141] For example, one method for calculating the coupling state index uses a transmission voltage V3 applied to a circuit (e.g., an inverter) included in the power transmitting unit 103 of the TX 100 and a receiving voltage (denoted as V4) applied to a circuit (e.g., a rectifier) ​​included in the power receiving unit 203 of the RX 200. Here, the transmission voltage V3 applied to the circuit included in the power transmitting unit 103 of the TX 100 is, for example, an inverter input voltage input to an inverter included in the power transmitting unit 103 of the TX 100, or an inverter output voltage output by the inverter. Here, the receiving voltage V4 applied to the circuit included in the power receiving unit 203 of the RX 200 is, for example, a rectifier input voltage input to a rectifier included in the power receiving unit 203 of the RX 200. Using these, the calculation process for the coupling state index between the power transmitting antenna and the power receiving antenna can be performed. Alternatively, the coupling status index between the transmitting antenna and the receiving antenna can be calculated using the transmitting voltage V3 applied to a circuit (e.g., an inverter) included in the power transmitting unit 103 of the TX100 and the receiving voltage (denoted as V5) of a circuit (e.g., a rectifier) ​​included in the power receiving unit 203 of the RX200. Here, the receiving voltage V5 applied to the circuit included in the power receiving unit 203 of the RX200 is, for example, the rectifier output voltage output from the rectifier included in the power receiving unit 203 of the RX200. Alternatively, it is a voltage applied to a load (a charging unit, a battery). The TX100 notifies the RX200 of the transmitting voltage V3, and the RX200 can calculate the coupling status index using the notified V3 and V4 or V5. At this time, the TX100 notifies the RX200 of a constant calculated using the electrical characteristics (e.g., L1) of the power transmitting antenna, and the RX200 can calculate the coupling status index using the constant.

[0142] Alternatively, the RX200 notifies the TX100 of the receiving voltage V4 or V5, and the TX100 calculates the value of the coupling state index using the notified V4 or V5 and V3. At this time, the RX200 notifies the TX100 of a constant calculated using the electrical characteristics (e.g., L2) of the receiving antenna, and the TX100 can calculate the coupling state index using the constant.

[0143] The TX 100 and the RX 200 exchange information such as voltage values ​​V1 to V5, values ​​of self-inductance L1 and L2, or constants representing the electrical characteristics of the transmitting and receiving antennas. The timing of measuring voltage values ​​and the timing of sending and receiving each piece of information will be described below. Measurement of each voltage value is performed, for example, during the Ping phase. During the Ping phase, the TX 100 transmits a Digital Ping to the RX 200. Therefore, any one of the voltage values ​​V1, V2, V3, V4, and V5 generated when transmitting the Digital Ping can be used. During the Ping phase, the TX 100 and the RX 200 measure any one of the values ​​V1 to V5 and store and retain the value in the memory 106 or the memory 208. Alternatively, the TX 100 transmits a predetermined packet to the RX 200 to notify the timing of measuring the voltage values. When the RX 200 receives the predetermined packet, it measures one of the voltage values ​​V2, V4, and V5. The RX 200 measures one of the values ​​V2, V4, and V5 and stores and holds the value in memory 208. Alternatively, the RX 200 transmits a predetermined packet to the TX 100 to notify the timing of measuring the voltage value. When the RX 200 receives the predetermined packet, it measures one of the voltage values ​​V1 and V3. The TX 100 measures one of the values ​​V1 and V3 and stores and holds the value in memory 106.

[0144] The TX 100 transmits a predetermined transmission request packet to the RX 200 to request transmission of a packet including information on any or all of the voltage values ​​V2, V4, and V5. Upon receiving the transmission request packet, the RX 200 transmits a predetermined packet containing information on any or all of the voltage values ​​V2, V4, and V5 to the TX 100. The TX 100 receives the predetermined packet containing information on any or all of the voltage values ​​V2, V4, and V5 notified from the RX 200 and stores the information in the memory 106. The information contained in the predetermined packet may include not only the voltage of the RX 200, but also information such as the received power, the requested received power value, the value of the self-inductance L2, and a constant calculated using the electrical characteristics of the receiving antenna. Alternatively, information regarding the temperature of the RX 200 may also be included. The TX 100 receives the information from the RX 200 and performs more appropriate control using the information and the calculated coupling state index. The predetermined packet can be a Signal Strength Data packet used to notify the TX 100 of information about the RX 200. Alternatively, the predetermined packet may be an Identification Data packet or an Extended Identification Data packet in the Configuration phase. Alternatively, the predetermined packet may be a Configuration Data packet. Alternatively, the predetermined packet may be a packet in the Calibration phase or the Power Transfer phase. In other words, RP1, RP2, or RP0 may be used. Note that the present invention is not limited to the example in which the TX 100 uses the voltage value generated when transmitting a Digital Ping. Any one of the voltage values ​​V1 to V5 generated when the TX 100 transmits an Analog Ping in the Selection phase may be used. Alternatively, any one of the voltage values ​​V1 to V5 generated when the TX 100 transmits power to the RX 200 in the Power Transfer phase may be used.

[0145] The RX 200 transmits a predetermined transmission request packet to the TX 100 to request the transmission of a packet including information on either or all of the voltage values ​​V1 and V3. Upon receiving the transmission request packet, the TX 100 transmits to the RX 200 a predetermined packet including information on either or all of the voltage values ​​V1 and V3.

[0146] The RX 200 receives a predetermined packet containing information on either or all of the voltage values ​​V1 and V3 notified from the TX 100 and stores the information in the memory 208. The information contained in the predetermined packet may include not only the voltage of the TX 100 but also information such as the transmission power value, the transmittable power value, the value of the self-inductance L1, and a constant calculated using the electrical characteristics of the power transmitting antenna. Alternatively, the information may include the result of foreign object detection using the foreign object detection methods described above (power loss method, Q-factor measurement method, waveform attenuation method) and information on the temperature of the TX 100. The RX 200 receives the information from the TX 100 and can perform more appropriate control using the information and the calculated coupling state index. Furthermore, the predetermined packet may use a Power Transmitter Capabilities (CAP) Data Packet to notify the RX 200 of information on the TX 100. Alternatively, the TX 100 can notify the RX 200 of information about the TX 100 using a Power Transmitter Identification (ID) data packet. Note that the present invention is not limited to the example in which the voltage value generated when the TX 100 transmits a Digital Ping is used. Any of the voltage values ​​V1 to V5 generated when the TX 100 transmits an Analog Ping in the Selection phase may be used. Alternatively, any of the voltage values ​​V1 to V5 generated when the TX 100 transmits power to the RX 200 in the Power Transfer phase may be used.

[0147] When performing the first measurement, RX200 may turn off third switch unit 213 located between resonant capacitor 211 and power receiving unit 203, and control the circuit formed by power receiving antenna 205 and resonant capacitor 211 to be in an open state. This prevents the power receiving unit 203, charging unit 206, and battery 207 from affecting the performance of the first measurement method, enabling more accurate measurement of the coupling state index.

[0148] Next, a second measurement method will be described as another example of a method for measuring an indicator of the coupling state between a transmitting antenna and a receiving antenna. The measurement performed in the second measurement method will be referred to as the second measurement hereinafter. Fig. 12(B) is an equivalent circuit diagram for explaining the second measurement method. r1, r2 and L1, L2 are the same as in Fig. 12(A). The definitions of various quantities related to the transmitting antenna (coil) on the primary side (TX100) are shown below. V6: Input voltage (transmitting voltage) of the transmitting antenna when the receiving antenna side is shorted V7: Input voltage (transmitting voltage) of the transmitting antenna when the receiving antenna side is open I1: Current flowing through the transmitting antenna when the receiving antenna side is shorted I2: Current flowing through the transmitting antenna when the receiving antenna side is open

[0149] The coupling coefficient k can be calculated by the following equation 3: k=√(1−Lsc / Lopen) (Equation 3)

[0150] In Equation 3, Lsc represents the inductance of the power transmitting antenna when both ends of the power receiving antenna are short-circuited. For example, the control unit 201 turns on the third switch unit 213 and the second switch unit 210 (short-circuited state). The Lsc value can be obtained by measuring the inductance value of the power transmitting antenna in this state. The inductance value of the power transmitting antenna can be calculated from the input voltage V6 and current I1 of the power transmitting antenna.

[0151] In Equation 3, Lopen represents the inductance of the power transmitting antenna when both ends of the power receiving antenna are open. For example, the control unit 201 sets the third switch unit 213 to the OFF state (open state). The Lopen value can be obtained by measuring the inductance value of the power transmitting antenna in this state. The inductance value of the power transmitting antenna can be calculated from the input voltage V7 and current I2 of the power transmitting antenna. In the second measurement method, the coupling state index (coupling coefficient) can be calculated from the input voltage and current of the power transmitting antenna when both ends of the power receiving antenna are short-circuited and when they are open.

[0152] The TX 100 can also calculate a coupling state index based on the transmission voltage and current applied to a circuit (e.g., an inverter) included in the power transmitting unit 103. In this case, the input voltages V6 and V7 represent the transmission voltage applied to the circuit (e.g., an inverter) included in the power transmitting unit 103. Here, the transmission voltages V6 and V7 applied to the circuit included in the power transmitting unit 103 of the TX 100 are, for example, the inverter input voltage or the inverter output voltage. The input voltages V6 and V7 may also be the voltage applied to both terminals of a series resonant circuit consisting of a power transmitting antenna and a resonant capacitor. Alternatively, the transmission voltage applied to the circuit (e.g., an inverter) included in the power transmitting unit 103 and the voltage applied across the resonant capacitor 107 may be measured, and the voltage applied to the power transmitting antenna may be calculated from the results. In other words, the coupling state index can be calculated from the measurement results of the transmission voltage applied to the circuit (e.g., an inverter) included in the power transmitting unit 103 and the voltage applied across the resonant capacitor 107. In this case, the transmission voltage applied to the circuit (for example, inverter) included in the power transmitting unit 103 may be calculated by the TX 100 from the set value of the transmission power.

[0153] 12B, the current I1 or I2 is not limited to a current flowing through the power transmitting antenna, but may be, for example, a current flowing through a circuit (e.g., an inverter) included in the power transmitting unit 103. Here, the current flowing through a circuit included in the power transmitting unit 103 of the TX 100 is, for example, an inverter input current or an inverter output current. The open state and short state of the power receiving antenna have been described as being realized by the control unit 201 controlling the second switch unit 210 and the third switch unit 213. These states may also be realized by the power receiving unit 203. Instead of the short state, a light load state (light load state) may be used. Instead of the open state, a connected load state (load connected state) may be used.

[0154] In the second measurement method, the TX100 can calculate the coupling status index by measuring the input voltages V6 and V7 and the currents I1 and I2. Therefore, information such as the voltage values ​​measured by the RX200 and the inductance value of the receiving antenna is not required, and the RX200 does not need to notify the TX100 of this information. However, when the TX100 measures the input voltage V6 and the current I1, the RX200 must short both terminals of the circuit containing the receiving antenna. Furthermore, when the TX100 measures the input voltage V7 and the current I2, the RX200 must open both terminals of the circuit containing the receiving antenna. In other words, depending on the timing at which the TX100 measures the input voltage and current, the RX200 must control both terminals of the circuit containing the receiving antenna to a short or open state. Once this control is complete, the TX100 performs measurement. The timing of measurement is determined by the TX100 and notified to the RX200, or determined by the RX200 and notified to the TX100. Furthermore, the RX200 notifies the TX100 when it has completed control to set both terminals of the circuit including the power receiving antenna to a SHORT (short circuit) or OPEN (open) state. These notifications are performed by communication based on the WPC standard between the first communication unit 104 of the TX100 and the first communication unit 204 of the RX200, or by communication based on a standard other than the WPC standard between the second communication unit 109 of the TX100 and the second communication unit 212 of the RX200.

[0155] Measurement of the input voltages V6 and V7 and the currents I1 and I2 is performed, for example, during the Ping phase. During the Ping phase, the TX 100 transmits a Digital Ping to the RX 200. Therefore, the values ​​of V6 and V7 and the currents I1 and I2 generated when transmitting the Digital Ping can be used. During the Ping phase, the TX 100 acquires the values ​​of V6, V7, I1, and I2 and stores them in the memory 106 to calculate the coupling state index. Note that the TX 100 is not limited to using the voltage values ​​and current values ​​generated when transmitting a Digital Ping. For example, the values ​​of V6, V7, I1, and I2 generated when the TX 100 transmits an Analog Ping during the Selection phase may be used. Alternatively, the voltage values ​​of V6, V7, I1, and I2 generated when the TX 100 transmits power to the RX 200 in the power transfer phase may be used.

[0156] In the present disclosure, both the first measurement method and the second measurement method can be applied to a method for measuring a coupling status indicator between a power transmitting antenna and a power receiving antenna. Below, a method for setting a status determination threshold for a coupling status indicator acquired by the first or second measurement method will be described. The status determination includes a determination regarding the detection of a foreign object between the power transmitting antenna and the power receiving antenna, a determination regarding the detection of a misalignment between the power transmitting antenna and the power receiving antenna, and a determination regarding the detection of separation between the power transmitting antenna and the power receiving antenna. By implementing the first or second measurement method, it is possible to determine the presence or absence of a status abnormality using the status determination threshold. Below, first to fourth threshold setting methods will be described.

[0157] The first threshold setting method is a method in which the value of the coupling status indicator used to detect the status between the transmitting antenna and the receiving antenna when there is no status abnormality is set as the threshold. The status detection produces a judgment result such as "status abnormality present," "high probability of status abnormality," "low probability of status abnormality," or "no status abnormality." Assume that the RX 200 is mounted on the test TX 100 and there is no status abnormality between the transmitting antenna and the receiving antenna. In this case, the value of the coupling status indicator between the test TX 100 including the transmitting antenna and the RX 200 including the receiving antenna can be set as the threshold. The RX 200 stores the value of the coupling status indicator (threshold) measured in advance in its memory, and the RX 200 notifies the TX 100 of the threshold. The TX 100 uses the threshold to perform a judgment process related to status detection. The RX 200 may transmit this threshold to the TX 100 by including it in the FOD Status Data packet specified in the WPC standard. Alternatively, the value of the coupling state index between the power transmitting antenna and the power receiving antenna at which a predetermined power transfer efficiency is obtained may be set as the threshold. In the state detection, for example, the following determination results are obtained: "The predetermined power transfer efficiency cannot be obtained," or "The coupling between the power transmitting antenna and the power receiving antenna is weak." "It is highly likely that the predetermined power transfer efficiency cannot be obtained," or "The coupling between the power transmitting antenna and the power receiving antenna may be weak." "It is highly likely that the predetermined power transfer efficiency can be obtained," or "The coupling state between the power transmitting antenna and the power receiving antenna may be good." "The predetermined power transfer efficiency can be obtained," or "The coupling state between the power transmitting antenna and the power receiving antenna is good."

[0158] Here, it is assumed that the RX 200 is placed on the test TX 100, there is no abnormality in the state between the transmitting antenna and the receiving antenna, and a predetermined power transmission efficiency is obtained. In this case, the value of the coupling state index between the test TX 100 including the transmitting antenna and the RX 200 including the receiving antenna can be used as the threshold. The RX 200 stores the value of the coupling state index measured in advance as a threshold in memory and notifies the TX 100 of the threshold. The TX 100 uses the threshold to perform a determination process related to state detection. The RX 200 may transmit this threshold to the TX 100 by including it in the FOD Status Data packet specified in the WPC standard.

[0159] The second threshold setting method is a method in which the TX100 and RX200 set the coupling condition index measured by the first or second measurement method in a predetermined state as the threshold. The predetermined state is a state in which there is no abnormal condition between the transmitting antenna and the receiving antenna. Methods for confirming this state can include foreign object detection using the power loss method, waveform attenuation method, Q-factor measurement method, and foreign object detection based on the temperature of the TX100 or RX200. As a result, if it is determined that there is no abnormal condition, it can be confirmed with a high probability that there is no abnormal condition between the transmitting antenna and the receiving antenna.

[0160] That is, this confirmation is performed by a method and means other than the first or second measurement method. As a result, if it is determined that there is no abnormal condition (or no foreign matter), the bonding condition indicator is measured using the first or second measurement method, and an appropriate threshold value is set based on the measurement result.

[0161] For example, in the WPC standard, foreign object detection processing using the Q-factor measurement method is performed in the negotiation phase or the renegation phase. If the result of the foreign object detection processing is that "no abnormal condition" (or "no foreign object") is determined, the binding status index is measured using the first or second measurement method after the negotiation phase or the renegation phase. A more appropriate threshold value can be set based on the measurement results. Furthermore, foreign object detection processing using the power loss method is performed during the power transfer phase. After the foreign object detection processing is performed, the binding status index is measured using the first or second measurement method, and a more appropriate threshold value can be set based on the measurement results. Alternatively, foreign object detection processing can be performed using a quality factor or the like in the selection phase or the ping phase. In this case, the binding condition indicator is measured using the first or second measurement method after the phase in which the foreign object detection process is performed, and an appropriate threshold value can be set based on the measurement results. Alternatively, the foreign object detection process using the waveform attenuation method described above is performed during the power transfer phase. After the foreign object detection process is performed, the binding condition indicator is measured using the first or second measurement method, and a more appropriate threshold value can be set based on the measurement results.

[0162] Next, a third threshold setting method will be described with reference to FIG. 13 . FIG. 13 is a diagram illustrating a threshold setting method for state detection using a coupling state index. In FIG. 13 , the horizontal axis represents transmitted power, and the vertical axis represents the coupling state index. On the graph line represented by the straight line segment 1202, point 1200 corresponds to the transmitted power value Pt1 and the coupling state index value k1, and point 1201 corresponds to the transmitted power value Pt2 and the coupling state index value k2. On the graph line, point 1203 corresponds to the transmitted power value Pt3 and the coupling state index value k3. The first or second measurement method described above can be used to calculate each coupling state index value.

[0163] As shown in Figure 3, the charging unit 206 and battery 207 are connected as loads to the power receiving unit 203 of the RX 200, so the calculated coupling state index value changes depending on the state of the load. In order to determine whether or not there is a state abnormality depending on the state of the load, it is necessary to set a threshold value for the coupling state index. First, when power is transmitted from the TX 100, the RX 200 controls the load so that it is in a light load state. The light load state is a state in which no power is supplied to the load of the RX 200, or a state in which only power equal to or less than a threshold is supplied. Alternatively, it is a load state in which the received power value of the RX 200 is within a predetermined range (hereinafter referred to as the "fifth range").

[0164] The transmission power value of the TX100 in this state is set to Pt1. Then, the RX200 transmits a packet to the TX100 requesting that a measurement of the coupling status index be performed. Alternatively, the TX100 transmits a packet to the RX200 requesting that a measurement of the coupling status index be performed. In this state, the TX100 and the RX200 measure the transmission voltage on the TX100 side and the receiving voltage on the RX200 side. The TX100 and the RX200 exchange information such as the values ​​of V1 to V7, the values ​​of the self-inductances L1 and L2, and constants calculated using the electrical characteristics of the transmitting antenna and the receiving antenna, and the TX100 or the RX200 calculates the coupling status index value k1. When the RX200 calculates the coupling status index value k1, it notifies the TX100 of the result. When the TX100 calculates the coupling status index value k1, it notifies the RX200 of the result and Pt1. At this time, the TX 100 recognizes the transmission power value Pt1 and stores in memory the CP 1200 that associates Pt1 with k1. Alternatively, the RX 200 stores in memory the CP 1200 that associates Pt1 with k1.

[0165] Next, when power is transmitted from the TX100, the RX200 controls the load of the RX200 so that it enters a load connection state. The load connection state is a state in which maximum power or power equal to or greater than a threshold is supplied to the load of the RX200. Here, "maximum power" refers to a power value close to the Reference Power. Alternatively, it is a load state in which the received power value of the RX200 is within a predetermined range (hereinafter referred to as the "sixth range"). Here, the sixth range is a range of power values ​​higher than the fifth range. The transmitted power value of the TX100 in this state is set to Pt2. Then, the RX200 transmits a packet to the TX100 requesting measurement of the coupling status indicator. Alternatively, the TX100 transmits a packet to the RX200 requesting measurement of the coupling status indicator. In this state, the TX100 and the RX200 measure the transmitted voltage on the TX100 side and the received voltage on the RX200 side. The TX100 and the RX200 exchange information such as the values ​​of V1 to V7, the values ​​of self-inductances L1 and L2, and constants calculated using the electrical characteristics of the transmitting and receiving antennas, and the TX100 or the RX200 calculates a coupling state index value k2. When the RX200 calculates the coupling state index value k2, it notifies the TX100 of the result. When the TX100 calculates the coupling state index value k2, it notifies the RX200 of the result and Pt2. The TX100 stores in memory a CP1201 that associates Pt2 with k2. Alternatively, the RX200 stores in memory a CP1201 that associates Pt2 with k2. Next, the TX100 performs linear interpolation between CP1200 and CP1201 to generate a line segment 1202. Line segment 1202 shows the relationship between the transmission power and the coupling state index when there are no abnormal conditions around the TX 100 and the RX 200. Using line segment 1202, the TX 100 can estimate the coupling state index value for each transmission power value when there are no abnormal conditions around the TX 100 and the RX 200. For example, assume that the transmission power value is Pt3. In this case, the coupling state index value k3 can be estimated from point 1203 on line segment 1202 that corresponds to the transmission power value Pt3. Based on the estimation result, the TX 100 can calculate a threshold value used to determine the presence or absence of an abnormal condition for each transmission power value.For example, a coupling state index value obtained by adding a predetermined value (a value corresponding to a measurement error) to the estimated result of the coupling state index value when there is no abnormality at a certain transmission power value can be set as the judgment threshold value.

[0166] In this way, the CAL process performed by the TX100 and the RX200 in order for the TX100 to acquire a combination of the transmission power value and the coupling state index value is called the "CAL process of the coupling state index measurement method." Furthermore, performing the calibration process again after the calibration process has been performed once and updating or adding calibration points is called a recalibration process, abbreviated as ReCAL process. Note that the RX200 may perform the control to put the load into a light load state and the control to put the load into a load connected state after notifying the TX100 that the control will be performed. Furthermore, either of these two controls may be performed first.

[0167] In this embodiment, the operation for calculating the determination threshold for state detection for each load (or each transmission power value) is performed, for example, in the calibration phase. In the calibration phase, the TX100 acquires data required for foreign object detection using the power loss method. At that time, the TX100 acquires data on the amount of power loss when the load state of the RX200 is a light load state and when the load state of the RX200 is a loaded state. Therefore, measurements of CP1200 and CP1201 in FIG. 13 can be performed together with measurements of power loss when the RX200 is in a light load state and a loaded state during the calibration phase. That is, when the TX100 receives first reference received power information from the RX200, it measures CP1200 in addition to the predetermined processing to be performed during the calibration phase. The first reference received power information is information according to RP1 specified in the WPC standard, but other messages may also be used. Furthermore, when TX100 receives the second reference received power information from RX200, it measures CP1201 in addition to the predetermined processing to be performed in the calibration phase. The second reference received power information is information according to RP2 specified in the WPC standard, but other messages may also be used. In this way, there is no need to set aside a separate period for measuring CP1200 and CP1201, so that CP1200 and CP1201 can be measured in a shorter time.

[0168] In a fourth threshold setting method, the TX 100 or RX 200 presets a threshold for a coupling status indicator having a value within a predetermined range. The TX 100 or RX 200 holds a predetermined threshold value as a common value independent of the RX 200 to which power is transmitted. The threshold may be a fixed value that does not depend on the situation, or a variable value determined by the TX 100 or RX 200 depending on the situation. For example, if the coupling status indicator is a coupling coefficient k, the k value range is "0≦k≦1." For example, the TX 100 or RX 200 determines that "a status abnormality exists" when "0≦k<0.2" and determines that "the status abnormality is highly likely" when "0.2≦k<0.5." The TX 100 or RX 200 determines that "the status abnormality is low" when "0.5≦k<0.8" and determines that "the status abnormality is not present" when "0.8≦k≦1." Data on conditions for the k value is stored in advance in a memory, and the determination process is carried out based on this data.

[0169] Alternatively, for example, the TX100 or RX200 determines that "a predetermined power transmission efficiency cannot be obtained" or "the coupling between the transmitting antenna and the power receiving antenna is weak" when "0≦k<0.2". The TX100 or RX200 determines that "a predetermined power transmission efficiency is likely to be obtained" or "the coupling between the transmitting antenna and the power receiving antenna is likely to be weak" when "0.2≦k<0.5". The TX100 or RX200 determines that "a predetermined power transmission efficiency is likely to be obtained" or "the coupling between the transmitting antenna and the power receiving antenna is likely to be good" when "0.5≦k<0.8". The TX100 or RX200 determines that "a predetermined power transmission efficiency can be obtained" or "the coupling between the transmitting antenna and the power receiving antenna is good" when "0.8≦k≦1". Data on the conditions for the k value is stored in advance in memory, and the determination process is performed based on this data.

[0170] Furthermore, when setting a judgment threshold for state detection using a binding state index, a value obtained by adding a predetermined value (a value corresponding to a measurement error) to a binding state index value calculated based on the measurement results or received information can be set as the judgment threshold. Note that the threshold is not limited to one, and multiple thresholds can be set in stages, as described above.

[0171] Next, the timing for calculating the coupling state between the transmitting antenna and the receiving antenna using the first or second measurement method will be described. The calculation (measurement) of the coupling state is performed by the RX 200 transmitting a predetermined packet to the TX 100. Here, the predetermined packet is a Signal Strength Data packet transmitted from the RX 200 to the TX 100. Alternatively, the predetermined packet may be an Identification Data packet or an Extended Identification Data packet in the Configuration phase. Alternatively, the predetermined packet may be a Configuration Data packet. Alternatively, the predetermined packet may be a packet in the Calibration phase or the Power Transfer phase. In other words, it may be RP1, RP2, or RP0.

[0172] When the TX100 receives a predetermined packet from the RX200, it calculates a coupling status index between the transmitting antenna and the receiving antenna. Then, the TX100 makes a determination by comparing the calculated coupling status index with the determination threshold set by the above method. If the TX100 determines that there is no status abnormality, it transmits an ACK (acknowledgement) to the RX200, or status information indicating that there is no status abnormality, to the RX200. If the TX100 determines that there is a low possibility of a status abnormality or that there is a high possibility of a status abnormality, it transmits status information indicating the respective determination results to the RX200. If the TX100 determines that there is a status abnormality, it transmits a NAK (negative acknowledgement) to the RX200, or status information indicating that there is a status abnormality, to the RX200.

[0173] Alternatively, if the TX100 determines that "a predetermined power transmission efficiency can be obtained" or "the coupling state between the power transmitting antenna and the power receiving antenna is good," it transmits an acknowledgment (ACK) to the RX200 or status information indicating the determination result to the RX200. If the TX100 determines that "a predetermined power transmission efficiency is likely to be obtained" or "the coupling state between the power transmitting antenna and the power receiving antenna is likely to be good," it transmits status information indicating the determination result to the RX200. If the TX100 determines that "a predetermined power transmission efficiency is likely not to be obtained" or "the coupling between the power transmitting antenna and the power receiving antenna is likely to be weak," it transmits status information indicating the determination result to the RX200. If the TX100 determines that "a predetermined power transmission efficiency cannot be obtained" or "the coupling between the power transmitting antenna and the power receiving antenna is weak," it transmits a negative acknowledgment (NAK) to the RX200 or status information indicating the determination result to the RX200.

[0174] The status information is, for example, numerical information according to the status, and is as follows: Status information "0" corresponds to the determination result of "no status abnormality", or "a predetermined power transmission efficiency can be obtained", or "the coupling state between the power transmitting antenna and the power receiving antenna is good" Status information "1" corresponds to the determination result of "low possibility of status abnormality", or "high possibility of obtaining the predetermined power transmission efficiency", or "the coupling state between the power transmitting antenna and the power receiving antenna may be good" Status information "2" corresponds to the determination result of "high possibility of status abnormality", or "high possibility of not obtaining the predetermined power transmission efficiency", or "the coupling between the power transmitting antenna and the power receiving antenna may be weak" Status information "3" corresponds to the determination result of "status abnormality exists", or "the predetermined power transmission efficiency cannot be obtained", or "the coupling between the power transmitting antenna and the power receiving antenna is weak"

[0175] Alternatively, the calculation (measurement) of the coupling state is performed by the TX 100 transmitting a predetermined packet to the RX 200. Here, the predetermined packet is a Power Transmitter Capabilities (CAP) Data Packet transmitted from the TX 100 to the RX 200. Alternatively, the predetermined packet is a Power Transmitter Identification (ID) Data Packet.

[0176] When the RX200 receives a predetermined packet from the TX100, it calculates a coupling status index between the transmitting antenna and the receiving antenna. Then, the RX200 makes a determination by comparing the calculated coupling status index with the determination threshold set by the above method. When the RX200 determines that there is no abnormal status, it transmits a predetermined packet including status information indicating the determination result to the TX100. When the RX200 determines that there is a low possibility of an abnormal status or that there is a high possibility of an abnormal status, it transmits a predetermined packet including status information indicating the respective determination result to the TX100. When the RX200 determines that there is a abnormal status, it transmits a predetermined packet including status information indicating the determination result to the TX100.

[0177] Alternatively, if the RX200 determines that "a predetermined power transmission efficiency can be obtained" or "the coupling state between the power transmitting antenna and the power receiving antenna is good," it transmits status information indicating the determination result to the TX100. If the RX200 determines that "the predetermined power transmission efficiency is likely to be obtained" or "the coupling state between the power transmitting antenna and the power receiving antenna is likely to be good," it transmits status information indicating the determination result to the TX100. If the RX200 determines that "the predetermined power transmission efficiency is likely to not be obtained" or "the coupling between the power transmitting antenna and the power receiving antenna is likely to be weak," it transmits status information indicating the determination result to the TX100. If the RX200 determines that "the predetermined power transmission efficiency cannot be obtained" or "the coupling between the power transmitting antenna and the power receiving antenna is weak," it transmits status information indicating the determination result to the TX100.

[0178] The status information is, for example, numerical information according to the status, and is as follows: Status information "0" corresponds to the determination result of "no status abnormality", or "a predetermined power transmission efficiency can be obtained", or "the coupling state between the power transmitting antenna and the power receiving antenna is good" Status information "1" corresponds to the determination result of "low possibility of status abnormality", or "high possibility of obtaining the predetermined power transmission efficiency", or "the coupling state between the power transmitting antenna and the power receiving antenna may be good" Status information "2" corresponds to the determination result of "high possibility of status abnormality", or "high possibility of not obtaining the predetermined power transmission efficiency", or "the coupling between the power transmitting antenna and the power receiving antenna may be weak" Status information "3" corresponds to the determination result of "status abnormality exists", or "the predetermined power transmission efficiency cannot be obtained", or "the coupling between the power transmitting antenna and the power receiving antenna is weak"

[0179] Next, the operation of the TX100 to rapidly charge the battery of the RX200 appropriately will be described. Rapid charging requires transmitting higher power from the TX100 to the RX200. The WPC standard includes a Baseline Power Profile (BPP), which transmits 5 watts or less to the RX200, and an Extended Power Profile (EPP), which transmits 15 watts or less. The BPP uses the Baseline Protocol, a unidirectional communication protocol. The EPP uses the Extended Protocol, an extended protocol for bidirectional communication. This embodiment assumes a case where higher power is transmitted than in the EPP. That is, a case where the TX100 transmits more than 15 watts of power to the RX200 is assumed. A state (profile, mode) in which wireless power transmission of more than 15 watts to the RX200 is performed is called a fast charge mode or a fast charge profile. Alternatively, a state (profile, mode) in which the TX100 and RX200 can set a GP of more than 15 watts is called a fast charge mode, a fast charge profile, or a fast charge power profile. Furthermore, the maximum GP that can be set in the fast charge mode, the fast charge profile, or the fast charge power profile is assumed to be 50 watts. Here, a power profile is a set of features that defines the compliance level of a power transmitting device or a power receiving device.

[0180] The following describes the operation when the TX100 and the RX200 perform wireless charging in rapid charge mode, using the flowchart of the power transmitting device in Fig. 14 and the flowchart of the power receiving device in Fig. 15. Note that the following describes the Negotiation phase and subsequent steps (not shown) that occur after the TX100 and the RX200 have executed the above-mentioned Selection phase, Ping phase, and Configuration phase. First, in the Negotiation phase, the RX200 requests transmission of information indicating whether the power transmitting device supports rapid charge mode (F1501). Specifically, the request is made using a General Request (GRQ) data packet defined in the WPC standard.

[0181] When the TX100 receives a request from the RX200 to transmit information indicating whether the power transmitting device supports the rapid charge mode (F1401), the TX100 transmits a packet including information indicating that the power transmitting device supports the rapid charge mode to the RX200 (F1402). Here, "supporting the rapid charge mode" means that the TX100 or the RX200 has hardware, control means, and functions that enable the TX100 to operate in the rapid charge mode for the RX200. This packet is a Power Transmitter Capabilities (CAP) Data Packet. Alternatively, it is a Power Transmitter Identification (ID) Data Packet. These packets have a 1-bit field indicating whether the power transmitting device supports the rapid charge mode. When the TX 100 notifies the RX 200 that it supports the rapid charge mode, it stores "1" in the corresponding field, and when it notifies the RX 200 that it does not support the rapid charge mode, it stores "0" in the corresponding field. Note that the meanings of "1" and "0" stored in the corresponding field may be reversed.

[0182] Alternatively, the Power Transmitter Identification (ID) data packet has a field for storing version information of the WPC standard. Information capable of identifying the version of the WPC standard (Qi standard) supported by the TX100 is stored in the fields for storing the major and minor versions of the Power Transmitter ID data packet. These fields are used to store information on the version supported by the MPP (described later) and information on the version supported by the MPP and the rapid charge mode. If the TX100 does not support the MPP (described later), the TX100 controls the RX200 so as not to notify the RX200 of information indicating support for the rapid charge mode. In other words, in the above example, if the TX100 "does not support MPP," the TX100 controls the RX200 so as not to transmit "version information that supports both MPP and the rapid charge mode." For example, the TX100 may transmit "version information that does not support either the MPP or the rapid charge mode." Furthermore, when the TX100 notifies the RX200 of information indicating that it supports the above-mentioned rapid charge mode, the TX100 must also support MPP, which will be described later. In other words, in the above example, if the TX100 "supports rapid charge mode," the TX100 controls the RX200 to transmit "version information that supports both MPP and rapid charge mode."

[0183] The RX200 determines whether or not it has received a packet from the TX100 that includes information that the TX100 supports the rapid charge mode (F1502). If it has not received a packet, it periodically or irregularly repeats the determination in F1502 until a predetermined time has elapsed (No in F1502, No in F1517). If the RX200 has not received a packet that includes information that the TX100 supports the rapid charge mode within the predetermined time (No in F1502, Yes in F1517), it ends the processing. That is, the RX200 returns to the Selection phase.

[0184] When the RX200 receives a packet from the TX100 including information indicating that the RX200 supports the rapid charge mode (Yes in F1502), the RX200 transmits a packet including information indicating whether the RX200 supports the rapid charge mode to the TX100 (F1503). This packet is, for example, an FOD Status Data Packet. These packets are provided with a 1-bit field indicating whether the RX200 supports the rapid charge mode. When the RX200 notifies the TX100 that the RX200 supports the rapid charge mode, the RX200 stores "1" in this field. When the RX200 notifies the TX100 that the RX200 does not support the rapid charge mode, the RX200 stores "0" in this field. In this case, the RX200 is a power receiving device that supports the rapid charge mode, and therefore transmits a packet including information indicating that the RX200 supports the rapid charge mode. Note that the meanings of "1" and "0" stored in the corresponding field may be reversed. Furthermore, a different packet may be used in place of the FOD Status Data Packet as long as it is a packet used in the Negotiation phase. The TX100 determines whether or not it has received a packet from the RX200 that includes information that the RX200 supports the rapid charge mode (F1403). If the TX100 has not received a packet, it periodically or irregularly repeats the determination in F1403 until a predetermined time has elapsed (No in F1403, No in F1418). If the TX100 has not received a packet that includes information that the RX200 supports the rapid charge mode within the predetermined time (No in F1403, Yes in F1418), it terminates the processing. That is, the TX100 returns to the Selection phase.

[0185] In the above example, the RX200 receives information from the TX100 indicating that "the RX100 supports the rapid charge mode," and then the RX200 transmits information indicating that "the RX200 supports the rapid charge mode" to the TX100. However, the order of transmission and reception of information may be reversed. That is, the TX100 may receive information from the RX200 indicating that "the RX200 supports the rapid charge mode," and then the TX100 may transmit information indicating that "the RX100 supports the rapid charge mode" to the RX200. For example, the information indicating that "the RX200 supports the rapid charge mode" may be transmitted before the configuration phase. This information may be stored in a signal strength data packet transmitted from the RX200 to the TX100 in the ping phase. Alternatively, this information may be stored in a packet transmitted in the configuration phase. The packet can be an Identification Data Packet, an Extended Identification Data Packet, or a Configuration Data Packet.

[0186] Furthermore, the Identification Data Packet has a field for storing version information of the WPC standard. Information capable of identifying the version of the WPC standard (Qi standard) supported by the RX200 is stored in the fields for storing the major and minor versions of the Identification (ID) data packet. These fields are used to store information on the version supported by the MPP (described later) and information on the version supported by the MPP and the rapid charge mode. If the RX200 does not support the MPP (described later), the RX200 controls the TX100 so as not to notify the TX100 of information indicating support for the rapid charge mode. In other words, in the above example, if the RX200 "does not support MPP," the RX200 controls the TX100 so as not to transmit "version information that supports both MPP and the rapid charge mode." For example, the RX200 may transmit "version information that does not support either the MPP or the rapid charge mode." Furthermore, when the RX200 notifies the TX100 of information indicating that it supports the above-mentioned rapid charge mode, the RX200 must support the MPP described below. In other words, in the above example, when the RX200 "supports the rapid charge mode," the RX200 controls the TX100 to transmit "version information that supports both the MPP and the rapid charge mode."

[0187] Alternatively, only one of the TX 100 and the RX 200 may transmit a packet containing information indicating that the RX 200 or the TX 100 is compatible with the rapid charging mode.

[0188] Next, RX200 transmits to TX100 a packet including "information for determining whether or not the conditions for transitioning to the rapid charge mode are met" (F1504). This packet may be an FOD Status Data Packet. The FOD Status Data Packets transmitted in F1503 and F1504 may be the same packet, or different FOD Status Data Packets. In the former case, F1503 and F1504 are performed in a single process. In addition, another packet may be used instead of the FOD Status Data Packet as long as it is a packet used in the negotiation phase. Furthermore, the packet including "information for determining whether or not the conditions for transitioning to the rapid charge mode are met" and the packet including the information that "TX100 supports the rapid charge mode" may be the same type of packet, or may be different types.

[0189] Here, the "conditions for transitioning to the rapid charge mode" will be described. These conditions may be all of the following conditions, a combination of some of them, or any one of them.

[0190] [First Condition] The first condition is that the TX100 and RX200 are compatible with MPP. MPP stands for Magnetic Power Profile, and the WPC has announced that MPP will be adopted in "Qi2," the next-generation standard of the "Qi" wireless power receiving standard. MPP has the function of precisely fixing the TX100 and RX200 to predetermined positions. There are several possible means for precisely fixing the TX100 and RX200 to predetermined positions. For example, the TX100's power transmitting antenna (power transmitting coil) and the RX200's power receiving antenna (power receiving coil) can be precisely aligned (directly facing) by using magnets built into the TX100 and RX200, respectively. In other words, in this case, MPP can be considered an extension of BPP, a profile (power profile) that uses magnets to align the power transmitting device and the power receiving device. The magnets may be permanent magnets or electromagnets. Increasing power transmission efficiency and reducing power loss when transmitting large amounts of power in fast charging mode is also desirable for the environment. Therefore, if the TX100 and RX200 are MPP-compatible and can operate at MPP, the TX100 and RX200 are controlled to operate in fast charging mode. Therefore, in F1504, the RX200 transmits a packet to the TX100 containing information indicating that "the RX200 is MPP-compatible." Note that, if the RX200 cannot operate at MPP, it transmits a packet containing information indicating that it is not MPP-compatible. That is, in F1504, the RX200 transmits a packet containing information indicating whether it is possible to align the power transmitting device and the power receiving device using a magnet.

[0191] [Second Condition] The second condition is that the TX100 and the RX200 have a predetermined method (means) for fixing the TX100 and the RX200 to predetermined positions with high precision. Alternatively, the TX100 and the RX200 have a predetermined method (means) for fixing the transmitting antenna of the TX100 and the receiving antenna of the RX200 to predetermined positions with high precision. There are several methods (alignment methods) for fixing the TX100 and the RX200 to predetermined positions with high precision, or for fixing the transmitting antenna of the TX100 and the receiving antenna of the RX200 to predetermined positions with high precision.

[0192] <First alignment method> A method in which the TX100 and RX200 each have a built-in magnet, and the power transmitting antenna of the TX100 and the power receiving antenna of the RX200 are made to face each other by magnetic force. <Second alignment method> The TX100 has a movable power transmitting antenna, and the power transmitting antenna is moved near the power receiving coil of the RX200 to make the power transmitting antenna of the TX100 and the power receiving antenna of the RX200 face each other. <Third alignment method> The TX100 has a holder for fixing the RX200 so that the RX200 can be placed in a predetermined position on the TX100, and the RX200 is placed along the holder to make the power transmitting antenna of the TX100 and the power receiving antenna of the RX200 face each other.

[0193] These alignment methods vary in the positional accuracy with which the transmitting antenna of the TX100 and the receiving antenna of the RX200 face each other. As described above, the higher the positional accuracy with which the transmitting antenna of the TX100 and the receiving antenna of the RX200 face each other, the higher the power transmission efficiency, which is preferable. Therefore, when the TX100 and the RX200 support a predetermined alignment method that can align the transmitting antenna of the TX100 and the receiving antenna of the RX200 with a predetermined or higher level of accuracy, the TX100 and the RX200 are controlled to operate in fast charging mode.

[0194] For example, among the alignment methods described above, the first alignment method can be cited as an alignment method that can align the transmitting antenna of the TX100 and the receiving antenna of the RX200 with a predetermined or higher level of precision. By using magnets built into the TX100 and the RX200, the transmitting antenna (transmitting coil) of the TX100 and the receiving antenna (receiving coil) of the RX200 can be precisely aligned (directly facing each other). Therefore, if the TX100 and the RX200 are compatible with the first alignment method, the TX100 and the RX200 are controlled to operate in rapid charge mode. In F1504, the RX200 transmits a packet to the TX100 containing information indicating that the RX200 is compatible with the first alignment method. For example, the following can be cited as a method for notifying information about the alignment method.

[0195] (1) A method in which the RX 200 indicates the supported alignment method using predetermined information. For example, if the RX 200 supports the first alignment method, it includes information "1" in a predetermined packet and transmits it to the TX 100. If the RX 200 supports the second alignment method, it includes information "2" in a predetermined packet and transmits it to the TX 100. If the RX 200 supports the third alignment method, it includes information "3" in a predetermined packet and transmits it to the TX 100.

[0196] (2) A method in which RX200 notifies whether it supports the first alignment method by using predetermined information. For example, if RX200 supports the first alignment method, it includes information "1" in a predetermined packet and transmits it to TX100. If RX200 does not support the first alignment method, it includes information "2" in a predetermined packet and transmits it to TX100.

[0197] [Third Condition] The third condition is that the coupling status index between the transmitting antenna of the TX 100 and the receiving antenna of the RX 200 is equal to or exceeds a predetermined value. The method for measuring the coupling status index between the transmitting antenna of the TX 100 and the receiving antenna of the RX 200, or the method for setting a threshold for determining the superiority or inferiority of the coupling status index, is as described above.

[0198] If the transmitting antenna of the TX100 and the receiving antenna of the RX200 are facing each other, the value of the coupling status index will be good (large in the case of the coupling coefficient), and the power transmission efficiency will be high, which is desirable. Therefore, if the measured coupling status index of the TX100 and RX200 is equal to or greater than a set threshold value or exceeds the threshold value, the TX100 and RX200 are controlled to operate in fast charging mode.

[0199] In F1504, the RX transmits a packet to the TX containing “information used by the TX to calculate the coupling status indicator between the transmitting antenna and the receiving antenna.” The information received from the RX and required by the TX to calculate the coupling status indicator between the transmitting antenna and the receiving antenna is as described above in the description of the coupling status indicator measurement method.

[0200] In the above description, the method for determining the coupling status index between the transmitting antenna of the TX 100 and the receiving antenna of the RX 200 has been described based on a method for measuring the coupling status index between the transmitting antenna of the TX 100 and the receiving antenna of the RX 200, or a method for setting a threshold value for the coupling status index. Below, another method for determining the coupling status index between the transmitting antenna of the TX 100 and the receiving antenna of the RX 200 will be described.

[0201] <Another method for determining a coupling status index between the transmitting antenna of the TX100 and the receiving antenna of the RX200> The RX200 measures the received power value and notifies the TX100 of the measurement result. For example, in the Ping phase, the TX100 transmits a DP, and the RX200 measures the voltage value of the received (received) DP. The RX200 stores the measured voltage value in a Signal Strength Data Packet as a Signal Strength Value. The RX200 transmits the packet to the TX100, and the TX100 receives the packet from the RX200. The Signal Strength Value is a value measured by the RX200 as a voltage value regarding the power transmitted by the TX100. In other words, the magnitude of the received voltage value (measured value) indicates the strength of coupling between the transmitting antenna and the receiving antenna. The TX 100 compares the Signal Strength Value in the packet with a threshold. If the Signal Strength Value is equal to or greater than the threshold, the TX 100 determines that the coupling state is strong, and if the Signal Strength Value is less than the threshold, the TX 100 determines that the coupling state is weak. Note that the Signal Strength Value is a value measured by the RX 200 as a voltage value of the power transmitted by the TX 100. The RX 200 determines the strength of the coupling between the transmitting antenna and the receiving antenna based on the comparison result of the measured Signal Strength Value with the threshold. The RX200 determines that the signal strength value is equal to or greater than the threshold value and determines that the signal strength value is weakly coupled when the signal strength value is less than the threshold value. The TX100 or the RX200 controls the transmitting antenna and the receiving antenna to operate in the rapid charge mode when the transmitting antenna and the receiving antenna are strongly coupled. The TX100 or the RX200 controls the transmitting antenna and the receiving antenna not to operate in the rapid charge mode when the transmitting antenna and the receiving antenna are weakly coupled.

[0202] The threshold setting in the above-mentioned "another method for determining a coupling state index between the transmitting antenna of the TX 100 and the receiving antenna of the RX 200" may be as follows. That is, among the threshold setting methods for measuring the coupling state index, the first or fourth threshold setting method may be implemented, and the TX 100 may store a threshold in advance. Also, the RX 200 may notify the TX 100 of the threshold. Alternatively, the TX 100 and the RX 200 may store the same threshold in advance.

[0203] [Fourth Condition] The fourth condition occurs when no foreign object is detected by the foreign object detection method described above, or when the probability of the presence of a foreign object determined by the foreign object detection method described above is equal to or less than a predetermined value. The foreign object detection methods are the power loss method, the Q-factor measurement method, and the waveform attenuation method. The detailed operations for executing each foreign object detection method and the method for setting the threshold for determining the presence or absence of a foreign object or the probability of the presence of a foreign object are as described above.

[0204] Performing wireless power transmission when a foreign object is present near the transmitting antenna of the TX100 and the receiving antenna of the RX200 is undesirable because it generates heat in the foreign object. This is particularly undesirable because the greater the power transmitted from the TX100 to the RX200, the greater the amount of heat generated. Therefore, when a foreign object detection method determines that there is no foreign object or that the probability of the presence of a foreign object is equal to or less than a predetermined value, the TX100 and RX200 are controlled to operate in fast charging mode.

[0205] In F1504, RX200 transmits a packet including "information used by TX100 to execute a foreign object detection method" to TX100. The information received from RX200 that is necessary for TX100 to execute a foreign object detection method is as described above. In other words, the information received from RX200 is all the information that RX200 should provide to TX100 in order for TX100 to execute the various foreign object detection methods described above. This information also includes information used to determine the threshold to be set when executing a foreign object detection method.

[0206] The threshold for executing the foreign object detection method to determine the presence or absence of a foreign object or the probability of the presence of a foreign object may be set to a specific fast charge mode transition determination threshold for determining whether the conditions for transitioning to the fast charge mode are met. In other words, the threshold for the foreign object detection method used when operating with an EPP that transmits 15 watts or less is set to be different from the threshold for determining transition to the fast charge mode. For example, the threshold for determining transition to the fast charge mode is set to a stricter value than the threshold for the foreign object detection method used when operating with an EPP that transmits 15 watts or less. The thresholds are set by adding a predetermined margin to the reference value, but the threshold for determining transition to the fast charge mode is set by reducing this margin compared to the threshold for the foreign object detection method used when operating with an EPP that transmits 15 watts or less. This enables a safer transition to high-power power transmission in the fast charge mode.

[0207] [Fifth Condition] The fifth condition is when the temperature of a predetermined location on the TX100 or RX200 is equal to or lower than a predetermined value. When high-power power is transmitted in the rapid charge mode, the components of the TX100 or RX200 (such as the transmitting antenna, receiving antenna, and battery) generate more heat than when transmitting low-power power. Therefore, if the TX100 or RX200 transitions to the rapid charge mode while the temperature is high and transmits high power, this may result in damage to the TX100 or RX200. Therefore, when the temperature of the TX100 or RX200 is equal to or lower than a predetermined value, the TX100 and RX200 are controlled to operate in the rapid charge mode.

[0208] Here, we will explain a method of control based on the temperature of the TX 100. The TX 100 and the RX 200 each have temperature sensors at multiple locations. In particular, the temperature sensors are arranged at a higher density on the transmitting antenna 105, the charging stand 300, and the receiving antenna 205 than on other locations.

[0209] In F1504, the RX 200 transmits a packet including "timing information indicating the timing at which the TX 100 acquires temperature information from the temperature sensor of the TX 100" to the TX 100. This information may include information used to determine the temperature threshold to be set.

[0210] [Sixth Condition] The sixth condition is when the TX and RX are operating at the MPP described above. The TX and RX perform predetermined control to operate at the MPP. When the TX and RX are operating at the MPP, it is determined that "the conditions for transitioning to the fast charge mode are met."

[0211] The first to sixth conditions have been described above as the "conditions for transitioning to the rapid charge mode." The "conditions for transitioning to the rapid charge mode" may be a combination of the first to sixth conditions described above. For example, the "conditions for transitioning to the rapid charge mode" may be defined as a case where both the first and second conditions described above are satisfied. Furthermore, the "conditions for transitioning to the rapid charge mode" may be defined as a combination of not only two of the first to sixth conditions, but also three, four, five, or all of the first to sixth conditions.

[0212] Next, the TX100 determines whether or not it has received a packet containing "information for determining whether or not the conditions for switching to the rapid charge mode are met" from the RX200 (F1404). If the packet is not received, the TX100 makes the determination in F1404 periodically or irregularly until a predetermined time has elapsed (No in F1404, No in F1419). If the packet containing "information for determining whether or not the conditions for switching to the rapid charge mode are met" is not received even after the predetermined time has elapsed (No in F1404, Yes in F1419), the processing ends. In other words, the TX100 transitions to the Selection phase.

[0213] When the TX100 receives a packet including "information for determining whether the conditions for switching to the rapid charge mode are met" (Yes in F1404), it determines whether the conditions for switching to the rapid charge mode are met based on the information (F1405). If it is determined that "the conditions for switching to the rapid charge mode are met" as a result of the determination (Yes in F1405), the process proceeds to F1406. If it is determined that "the conditions for switching to the rapid charge mode are not met" (No in F1405), the process proceeds to F1415.

[0214] Here, the process of determining each of the above conditions will be described.

[0215] [When the first condition is included as a condition for transitioning to the rapid charge mode] When the TX100 receives a packet including information that "the RX200 is compatible with MPP," and if the TX100 is also compatible with MPP, it determines that the conditions for transitioning to the rapid charge mode are met and proceeds to F1406. Here, when the TX100 receives a packet that does not include information that "the RX200 is compatible with MPP," it determines that the conditions for transitioning to the rapid charge mode are not met and proceeds to F1415. Alternatively, when the TX100 receives a packet including information that "the RX200 is not compatible with MPP," it determines that the conditions for transitioning to the rapid charge mode are not met and proceeds to F1415. In other words, when both the TX100 and the RX200 are compatible with MPP, the TX100 controls the TX100 to operate in the rapid charge mode. On the other hand, if at least one of the TX 100 and the RX 200 cannot support MPP, the TX 100 controls so as not to operate in the rapid charge mode.

[0216] [When the second condition is included as a condition for transitioning to the rapid charge mode] When the TX100 receives a packet including information indicating that "the RX200 supports the first re-allocation method," and the TX100 also supports the first re-allocation method, it determines that the conditions for transitioning to the rapid charge mode are met. That is, it proceeds to F1406. On the other hand, when the TX100 receives a packet that does not include information indicating that "the RX200 supports the first re-allocation method," it determines that the conditions for transitioning to the rapid charge mode are not met, and it proceeds to F1415. Alternatively, when the TX100 receives a packet including information indicating that "the RX200 does not support the first re-allocation method," it determines that the conditions for transitioning to the rapid charge mode are not met, and it proceeds to F1415. That is, when both the TX100 and the RX200 support the first re-allocation method, the TX100 controls the TX100 to operate in the rapid charge mode. On the other hand, if at least one of the TX 100 and the RX 200 does not support the first alignment method, the TX 100 controls so as not to operate in the rapid charge mode.

[0217] [When the third condition is included as a condition for transitioning to the rapid charge mode] The TX 100 calculates the coupling status index using "information used by the TX 100 to calculate the coupling status index of the transmitting antenna and the receiving antenna." If the coupling status index satisfies a predetermined condition, the TX 100 determines that the conditions for transitioning to the rapid charge mode are met, and proceeds to F1406. Here, "satisfying the predetermined condition" means that the coupling status index is equal to or exceeds a set predetermined threshold. On the other hand, if the coupling status index does not satisfy the predetermined condition, the TX 100 determines that the conditions for transitioning to the rapid charge mode are not met, and proceeds to F1415.

[0218] [When the fourth condition is included as a condition for transitioning to the rapid charge mode] The TX100 executes the foreign object detection method using the "information used by the TX100 to execute the foreign object detection method" received from the RX200. If the result of the foreign object detection method satisfies a predetermined condition, the TX100 determines that the condition for transitioning to the rapid charge mode is satisfied, and proceeds to F1406. Here, "satisfying the predetermined condition" means that the result of foreign object detection by the foreign object detection method is that there is no foreign object, or that the probability of the presence of a foreign object is equal to or less than a predetermined value. If the result of foreign object detection by the foreign object detection method does not satisfy the predetermined condition, the TX100 determines that the condition for transitioning to the rapid charge mode is not satisfied, and proceeds to F1415.

[0219] [When the fifth condition is included as a condition for transitioning to the rapid charge mode] When the TX100 receives a packet from the RX200 including "timing information indicating the timing at which the TX100 acquires temperature information from the TX100's temperature sensor," the TX100 acquires the value of the TX100's temperature sensor at the timing at which the TX100 receives the packet. The TX100 then determines whether or not the condition for transitioning to the rapid charge mode is satisfied. If the acquired temperature sensor value of the TX100 satisfies a predetermined condition, the TX100 determines that the condition for transitioning to the rapid charge mode is satisfied, and proceeds to F1406. Here, "satisfying the predetermined condition" means that the temperature sensor value is equal to or less than a predetermined value. "Not satisfying the predetermined condition" means that the temperature sensor value is equal to or greater than a predetermined value.

[0220] In the above example, the TX 100 acquires the value of the temperature sensor of the TX 100 at the timing when it receives "timing information indicating the timing when the TX 100 acquires temperature information from the temperature sensor of the TX 100" from the RX 200. However, this is not limiting, and for example, the TX 100 may acquire temperature information from the temperature sensor of the TX 100 at a timing determined by the TX 100 at every predetermined cycle.

[0221] Furthermore, the TX 100 is not limited to determining whether to transition to the rapid charge mode based on the acquired temperature sensor value. For example, the TX 100 may calculate the temperature rise rate based on multiple temperature detection values ​​acquired at predetermined times. In this case, the TX 100 may determine that "the conditions for transitioning to the rapid charge mode are met" when the temperature rise rate is equal to or less than a predetermined threshold value. Furthermore, the TX 100 may determine that "the conditions for transitioning to the rapid charge mode are not met" when the temperature rise rate is equal to or greater than a predetermined threshold value.

[0222] Furthermore, the RX200 may acquire a value from the temperature sensor of the RX200 and transmit a packet including "temperature information from the temperature sensor of the RX200" to the TX100. This information may also include information used to determine the temperature threshold to be set. In this case, if the received temperature sensor value of the RX200 satisfies a predetermined condition, the TX100 determines that the conditions for transitioning to the rapid charge mode are met, and proceeds to F1406. Here, "satisfying the predetermined condition" means that the temperature sensor value of the RX200 is equal to or less than a predetermined value. If the temperature sensor value of the RX200 does not satisfy the predetermined condition, the TX100 determines that the conditions for transitioning to the rapid charge mode are not met, and proceeds to F1415. Here, "not satisfying the predetermined condition" means that the temperature sensor value of the RX200 is equal to or greater than a predetermined value.

[0223] The TX100 may also calculate a temperature rise rate based on values ​​from multiple temperature sensors acquired from the RX200, and determine that "the conditions for transitioning to the rapid charge mode are met" if the temperature rise rate is equal to or less than a predetermined threshold value. The TX100 may also determine that "the conditions for transitioning to the rapid charge mode are not met" if the temperature rise rate is equal to or greater than a predetermined threshold value.

[0224] Using the method described above, the TX100 determines in F1405 whether the conditions for transitioning to the rapid charge mode are met. The flow from F1405 onward will be described below. If the TX100 determines in F1405 that "the conditions for transitioning to the rapid charge mode are met," the process proceeds to F1406. The TX100 then transmits a packet containing information indicating that "the conditions for transitioning to the rapid charge mode are met" to the RX200 (F1406). An ACK, which is a positive acknowledgement, is used as this packet. The RX200 determines whether or not it has received a packet containing information indicating that "the conditions for transitioning to the rapid charge mode are met" from the TX100 (F1505). If the RX200 has not received this packet from the TX100 (for example, if it has received a NAK, which is a negative acknowledgement), the RX200 periodically or irregularly performs the determination in F1505 until a predetermined period has elapsed (No in F1505, No in F1518). If the RX 200 does not receive a packet containing information indicating that "the conditions for transitioning to the rapid charge mode are met" within the predetermined time (No in F1505, Yes in F1518), the RX 200 ends the process. In other words, the RX 200 returns to the Selection phase.

[0225] If the result in F1505 is Yes, the RX200 transmits a packet including information indicating a request to transition to the rapid charge mode to the TX100 (F1506). The TX100 determines whether or not it has received a packet including information indicating "a request to transition to the rapid charge mode" from the RX200 (F1407). The FOD Status Data Packet is used as this packet. This packet has a 1-bit field indicating whether or not to request a transition to the rapid charge mode. If the RX200 requests the TX100 to transition to the rapid charge mode, the RX200 stores "1" (or "0") in this field, and if the RX200 does not request the TX100 to transition to the rapid charge mode, the RX200 stores "0" (or "1") in this field. Note that, if the packet is used in the negotiation phase, another packet may be used instead of the FOD Status Data Packet.

[0226] If the TX100 does not receive the packet containing information requesting transition to the rapid charge mode (No in F1407), the TX100 proceeds to F1415. If the TX100 receives the packet (Yes in F1407), the TX100 transmits an ACK, which is a positive response, to the RX200 (F1408). Then, the TX100 proceeds to F1409. The RX200 determines whether or not an ACK has been received from the TX100 (F1507). If the RX200 does not receive an ACK from the TX100, the RX200 periodically or irregularly performs the determination in F1507 until a predetermined time has elapsed (No in F1507, No in F1519). If an ACK has not been received even after the predetermined time has elapsed (No in F1507, Yes in F1519), the processing ends. In other words, the RX200 returns to the Selection phase. If RX200 receives an ACK from TX100 (Yes in F1507), the process proceeds to F1508.

[0227] The operation of the TX100 in the fast charge mode from F1409 onwards will be described. In F1409, the TX100 executes negotiation / renegation corresponding to the power in the fast charge mode. Specifically, the TX100 can set the Negotiable Load Power to more than 15 watts. More specifically, the TX100 can set the Negotiable Load Power to the Potential Load Power. The Potential Load Power is the highest GP level that the TX100 can negotiate. This allows the GP to be set to more than 15 watts. However, the Negotiable Load Power may not be set to the Potential Load Power due to other conditions. As a result, even in the fast charge mode, the GP is not necessarily set to more than 15 watts. Negotiation / Renegotiation is an operation performed in the above-mentioned Negotiation phase. Through the above-mentioned control, the TX 100 and the RX 200 agree on the GP through negotiation.

[0228] Then, the process proceeds to F1410, where CAL processing / ReCAL processing corresponding to the power in the rapid charge mode is performed. The CAL processing / ReCAL processing is an operation performed in the calibration phase described above. If the GP is set to more than 15 watts, Pt2 in FIG. 4 will also be more than 15 watts. Line 1002 in FIG. 4 is created to cover the transmitted power and received power in the rapid charge mode. Line 1002 in FIG. 4 is created taking into account the GP in the rapid charge mode. Note that the number of calibration points created in the CAL processing / ReCAL processing for the rapid charge mode may be controlled to be greater than the number of calibration points created in the CAL processing / ReCAL processing when operating in BPP or EPP. Alternatively, the number of calibration points created in the CAL processing / ReCAL processing for the rapid charge mode is controlled to be equal to or greater than a predetermined number. The "predetermined number" is, for example, "3" or a greater number. Alternatively, the number of calibration points created in the CAL process / ReCAL process in the rapid charge mode may be determined according to the GP value. For example, the number of calibration points may be "3" when the GP is 20 watts, "4" when the GP is 30 watts, and "5" when the GP is 40 watts. The above-described method of determining the number of calibration points is applicable to the above-described "CAL process using the power loss method," "CAL process using the waveform decay method," and "CAL process using the binding state index measurement method."

[0229] Furthermore, the calibration points may be controlled to create calibration points corresponding to the following powers: Guaranteed Load Power, Requested Load Power, Negotiable Load Power, Potential Load Power, Maximum Power Value or Reference Power.

[0230] The above-described method for creating calibration points can be applied to the above-described "CAL processing of the power loss method," "CAL processing of the waveform decay method," and "CAL processing of the binding state index measurement method."

[0231] Next, the process proceeds to F1411, where the TX100 starts transmitting power of less than 5 watts or equal to or less than 5 watts to the RX200. Then, the process proceeds to F1412, where authentication defined in the WPC standard is performed. Here, authentication refers to the process in which the RX200 authenticates the TX100. Authentication includes the process in which the RX200 determines whether the TX100 supports authentication. If the RX200 determines that the TX100 supports authentication, the RX200 transmits a predetermined first packet to the TX100. The RX200 determines whether a response from the TX100 that received the predetermined packet satisfies a predetermined condition. If the RX200 determines that the predetermined condition is satisfied, the RX200 transmits a predetermined second packet to the TX100. The RX200 determines whether authentication has been successful or not based on the content of the response from the TX100 that received the specified packet (F1412). Alternatively, in the authentication process, in addition to the process in which the RX200 authenticates the TX100, the TX100 may also perform a process in which the TX100 authenticates the RX200. The authentication includes a process in which the TX100 determines whether the RX200 supports authentication. If the TX100 determines that the RX200 supports authentication, the TX100 transmits a specified third packet to the RX200. The TX100 determines whether the response from the RX200 that received the specified packet satisfies a specified condition. If the TX100 determines that the response satisfies the specified condition, the TX100 transmits a specified fourth packet to the RX200. The TX100 determines whether authentication has been successful or not based on the content of the response from the RX200 that received the specified packet (F1412). In this case, TX100 and RX200 determine that "authentication has been successful" if RX200 has successfully authenticated TX100 and TX100 has successfully authenticated RX200.

[0232] If the authentication is successful (Yes in F1412), the process proceeds to F1413, where control for rapid charge mode operation, which will be described in the second embodiment, is executed. By successfully authenticating, the RX200 can receive power from a reliable TX100. Therefore, when the RX200 attempts to receive large amounts of power in rapid charge mode from the TX100, the RX200 controls the transition to rapid charge mode only when authentication is successful. In rapid charge mode, power transmission up to the GP determined in F1409 is possible. On the other hand, if the authentication fails (No in F1412), the process proceeds to F1415.

[0233] The details of the operation executed in F1413 will be described later in the second embodiment, but this is control to solve the problem that occurs when operating in the rapid charge mode. Next, the process proceeds to F1414, and power transmission in the rapid charge mode is started. This concludes the description of the operations from F1409 to F1414.

[0234] Next, the operation of the TX100 from F1415 onwards will be described. Operation from F1415 onwards is performed when it has been decided to operate in BPP or EPP rather than in the rapid charge mode. In F1415, the TX100 executes Negotiation / Renegotiation corresponding to the BPP / EPP power. Negotiation / Renegotiation is an operation executed in the Negotiation phase described above. The TX100 and RX200 set the GP to 5 watts or less for BPP or 15 watts or less for EPP. Specifically, the TX100 sets the Negotiable Load Power to 5 watts or less or 15 watts or less. This sets the GP to 5 watts or less or 15 watts or less.

[0235] Then, the process proceeds to F1416, where CAL processing / ReCAL processing corresponding to the BPP / EPP power is performed. CAL processing / ReCAL processing is an operation performed in the calibration phase described above. Since GP is set to 5 watts or less for BPP or 15 watts or less for EPP, Pt2 in FIG. 4 will also be 15 watts or less. Line 1002 in FIG. 4 is created to cover the transmitted power and received power of BPP or EPP.

[0236] 4 is created taking into consideration the GP of BPP or EPP. Next, proceeding to F1417, the TX 100 starts transmitting power at BPP or EPP to the RX 200. This concludes the description of the operations from F1415 to F1417.

[0237] The operation of the RX200 in the fast charge mode from F1508 onwards will be described. In F1508, the RX200 executes Negotiation / Renegotiation corresponding to the power in the fast charge mode. Specifically, the RX200 can set the Requested Load Power to more than 15 watts. This makes it possible to set the GP to more than 15 watts. However, even in the fast charge mode, the GP is not necessarily set to more than 15 watts. Negotiation / Renegotiation is an operation executed in the above-mentioned Negotiation phase. Through the above-mentioned control, the TX100 and the RX200 agree on the GP through negotiation.

[0238] Then, the process proceeds to F1509, where CAL processing / ReCAL processing corresponding to the power in the quick charge mode is executed. This processing has been explained in F1410 above, and therefore will not be explained again.

[0239] Next, the process proceeds to F1510, where the RX 200 starts receiving power from the TX 100 at less than 5 watts or at or below 5 watts. Then, the process proceeds to F1511, where authentication defined by the WPC standard is performed. If the authentication is successful (Yes in F1511), the process proceeds to F1512, where "control during rapid charge mode operation" described in the second embodiment is performed. Then, the process proceeds to F1513, where power reception in rapid charge mode is started. Note that if the authentication fails (No in F1511), the process proceeds to F1514. This concludes the description of the operations from F1508 to F1513.

[0240] Next, the operation of the RX200 from F1514 onwards will be described. The operations from F1514 onwards are those when it has been decided to operate in BPP or EPP rather than in the rapid charge mode. In F1514, the RX200 executes Negotiation / Renegotiation corresponding to the BPP / EPP power. Negotiation / Renegotiation is an operation executed in the Negotiation phase described above. The TX100 and RX200 set the GP to 5 watts or less for BPP or 15 watts or less for EPP. Specifically, the RX200 sets the Requested Load Power to 5 watts or less or 15 watts or less. As a result, the GP is set to 5 watts or less or 15 watts or less.

[0241] Then, the process proceeds to F1515, where CAL processing / ReCAL processing corresponding to the BPP / EPP power is executed. This processing has been explained in F1416 above, so the explanation will be omitted. Next, the process proceeds to F1516, where the RX 200 starts receiving power from the TX 100 via BPP or EPP. This concludes the explanation of the operations from F1514 to F1516.

[0242] 16 is a sequence diagram illustrating a case where power is transmitted from the TX100 to the RX200 in the rapid charge mode. First, the RX200 requests information indicating whether or not the TX100 supports the rapid charge mode (S1601), and the TX100 receives the request (S1602). The TX100 and the RX200 each notify the TX100 that they support the rapid charge mode (S1603, S1604). The RX200 then notifies the TX100 of information used to determine whether or not the "conditions for transitioning to the rapid charge mode" are met (S1605). Based on the information, the TX100 determines whether or not the conditions for transitioning to the rapid charge mode are met (S1606). Then, since the conditions for transitioning to the rapid charge mode are met, the TX100 notifies the RX200 that the conditions for transitioning to the rapid charge mode are met (S1607). Next, the RX200 notifies the RX200 of a request to transition to the rapid charge mode (S1608). The TX100 then transmits an acknowledgement (ACK) (S1609). Thereafter, the TX100 and the RX200 execute Negotiation / Renegotiation corresponding to the power of the rapid charge mode (S1610). Next, the TX100 and the RX200 execute CAL processing / ReCAL processing corresponding to the power of the rapid charge mode (S1611). The RX200 then executes authentication of the TX100 (S1612). The TX100 also executes authentication of the RX200 (S1612). If the authentication is successful (S1613), the TX100 and the RX200 execute "control during rapid charge mode operation" (S1614). Then, the TX 100 and the RX 200 start transmitting power in the rapid charging mode (S1615).

[0243] The order of S1601 to S1607 until the RX200 notifies the TX100 of a request to transition to the rapid charge mode may be different. For example, control may be performed so that S1601 to S1604 are performed after S1605 to S1607 are performed. In this case, if it is determined in S1606 that the TX100 does not satisfy the conditions for transitioning to the rapid charge mode, the TX100 may not perform S1607, and the TX100 and RX200 may also be controlled not to perform S1601 to S1604.

[0244] Next, the operation of the TX100 and RX200 to set / change the signal modulation method in in-band communication related to information transmission from the RX200 to the TX100 when the RX200 and TX100 enter the rapid charge mode will be described with reference to Figures 33 and 34. The in-band communication has been described above. The terms "signal modulation method" and "communication modulation method" that appear in the following description are essentially synonymous with "communication method."

[0245] In F3401, the RX200 transmits to the TX100 a predetermined packet including information indicating that the RX200 supports a modulation method for signals used in communication related to information transmission from the RX200 to the TX100, which is different from the modulation method used in BPP or EPP. In addition to the operations in the above-described embodiment, the TX100 determines in F3301 whether or not the RX200 has received a predetermined packet from the RX200 including information indicating that the RX200 supports a modulation method different from the modulation method used in BPP or EPP. If the determination result indicates that the predetermined packet has been received, the TX100 proceeds to F3303. If the determination result indicates that the predetermined packet has not been received, the TX100 proceeds to F3302 and determines whether or not a predetermined time has elapsed. If the TX100 determines in F3302 that the predetermined time has not elapsed, the TX100 returns to F3301. If the TX100 determines in F3302 that the predetermined time has elapsed, the TX100 terminates its operation. In this case, the RX 200 and the TX 100 use the modulation method used in the conventional BPP or EPP.

[0246] In F3303, the TX 100 determines whether the conditions for changing the modulation method of the signal in the communication related to the information transmission from the RX to the TX are met based on the information contained in the received predetermined packet. Specifically, in F3303, the TX 100 makes this determination based on whether the TX 100 supports the modulation method supported by the RX 200, for example, as notified by the predetermined packet. If the determination result in F3303 is Yes, the TX 100 transmits a packet to the RX 200 including information indicating that the conditions for changing the modulation method are met (F3304). If the determination result in F3303 is No, the TX 100 terminates its operation. In this case, the RX 200 and the TX 100 use the modulation methods used in conventional BPP and EPP.

[0247] The RX200 determines whether or not it has received a packet from the TX100 containing information indicating that the conditions for changing the modulation method are met (F3402). If the determination result in F3402 is Yes, the RX200 proceeds to F3405. If the determination result in F3402 is No, the RX200 proceeds to F3403 and determines whether or not it has received information indicating that the conditions for changing the modulation method are not met. If the determination result in F3403 is Yes, the RX200 terminates its operation. In this case, the RX200 and the TX100 use the modulation methods used in conventional BPP and EPP.

[0248] If the determination result in F3403 is No, the RX200 determines in F3404 whether or not a predetermined time has elapsed. If the RX200 determines in F3404 that the predetermined time has not elapsed, it returns to F3402. If the RX200 determines in F3404 that the predetermined time has elapsed, it ends its operation. In this case, the RX200 and the TX100 use the modulation method used in conventional BPP or EPP.

[0249] In F3405, RX200 transmits a packet including information requesting a change in modulation method to TX100 (F3405). TX100 determines whether or not a packet including information requesting a change in modulation method has been received from RX200 (F3305). If the determination result in F3305 is No, TX100 terminates its operation. In this case, RX200 and TX100 use the modulation method used in conventional BPP or EPP. If the determination result in F3305 is Yes, TX100 proceeds to F3306 and transmits an ACK to RX200.

[0250] In F3406, the RX200 determines whether or not an ACK has been received from the TX100. If the RX200 determines in F3406 that an ACK has not been received, it proceeds to F3407 and determines whether or not a predetermined time has elapsed. If the RX200 determines in F3407 that the predetermined time has not elapsed, it returns to F3406. If the RX200 determines in F3407 that the predetermined time has elapsed, it ends operation. In this case, the RX200 and the TX100 use the modulation method used in conventional BPP or EPP.

[0251] If the RX 200 determines in F3406 that it has received an ACK from the TX 100, it proceeds to F3408, changes the modulation method, and uses the changed modulation method to communicate with the TX 100. The TX 100 changes the modulation method in F3307, and uses the changed modulation method to communicate with the RX 200.

[0252] 35 is a sequence diagram showing the flow of the control described above. RX200 transmits a packet to TX100 containing information indicating that it supports a modulation method different from the modulation methods used in BPP and EPP (S3501). TX100 determines whether the conditions for changing the modulation method of the signal in communication are met (S3502). TX100 notifies RX200 that the conditions for changing the modulation method are met (S3503). RX200 notifies TX100 that it requests a change of the modulation method (S3504). TX100 transmits an ACK to RX200 indicating approval (S3505). TX100 and RX200 then change the modulation method (S3506).

[0253] Through the above operations, the RX200 and the TX100 recognize that a modulation method different from the modulation method used in BPP or EPP can be used as the signal modulation method in communication related to information transmission from the RX200 to the TX100. Then, the RX200 and the TX100 can communicate using a modulation method different from the modulation method used in BPP or EPP. The RX200 can include information indicating that the RX200 supports this modulation method in the Configuration Data Packet transmitted in the Configuration phase. Alternatively, the RX200 can include data indicating which modulation method the RX200 will use from the modulation methods different from the modulation methods used in BPP or EPP in the Configuration Data Packet.

[0254] For example, when the RX200 recognizes that it operates in the rapid charge mode, it stores data (e.g., "1") indicating the use of a modulation method different from the modulation methods used in BPP or EPP in a predetermined field in the Configuration Data Packet. Alternatively, "1" corresponding to the use of a first modulation method or "2" corresponding to the use of a second modulation method different from the first modulation method is stored in the field. Furthermore, "3" corresponding to the use of a third modulation method different from the first modulation method or the second modulation method is stored in the field. On the other hand, when the TX100 and the RX200 do not operate in the rapid charge mode, that is, when they operate in BPP or EPP, "0" corresponding to the use of a modulation method different from the modulation method used in BPP or EPP is stored in the field. Alternatively, for each modulation method, the RX200 stores information indicating whether the device itself supports the modulation method in a predetermined field. If the modulation method is supported, the data stored in the field is "1," and if the modulation method is not supported, the data stored in the field is "0." The RX 200 transmits the packet to the TX 100.

[0255] When executing the above process, the RX200 may notify the TX100 of the modulation method to be used in advance by a predetermined packet. For example, information about the modulation method to be used can be included in the Configuration Data Packet that the RX200 transmits in the Configuration phase. When the RX200 recognizes that the TX100 and the RX200 operate in the fast charge mode, the RX200 sets a field in the packet indicating the modulation method to be used by the RX200 to a predetermined value, and transmits the packet to the TX100. The TX100 determines the modulation method based on the information about the modulation method to be used by the RX200 that is included in the received packet.

[0256] In the above example, the RX200 transmits (F3401) to the TX100 "a predetermined packet including information indicating that the RX200 supports a modulation method different from the modulation method used in BPP or EPP" after starting power reception in the quick charge mode (F2101 described below). However, the information may be transmitted before starting power reception in the quick charge mode.

[0257] In the above example, the "predetermined packet including information indicating that the RX 200 supports a modulation method different from the modulation method used in BPP or EPP" transmitted to the TX 100 may be included in the Configuration Data Packet. In addition to this, the following packets may also be included:・Identification Data Packet (ID Packet) ・Extended Identification Data packet ・MPP Extended Identification Packet (MPP Extended Identification Data Packet, Qi MPP Extended Identification, MPP-XID data packet) ・ECAP data packet (Extended Power Receiver Capabilities Data Packet, Extended Power Receiver Capabilities, PRx Capabilities Packet)

[0258] In the above example, the operation of TX100 and RX200 when changing the modulation method of signals in communication related to information transmission from RX200 to TX100 has been described. Conversely, when changing the modulation method of signals in communication related to information transmission from TX100 to RX200, TX100 in the above explanation can be read as RX200 and RX200 as TX100. In this case, the following packets can be given as examples of "predetermined packets including information indicating that TX100 supports a modulation method different from the modulation methods used in BPP or EPP" that TX100 transmits to RX200.・Identification (ID) data packet (Power Transmitter Identification, Power Transmitter Identification data packet)・Power Transmitter Capabilities (CAP) data packet (CAP data packet, Power Transmitter Capabilities) ・Power Transmitter Extended Capabilities (XCAP) data packet Extended Capabilities) ・PTx XID data packet (PTx Extended Power Transmitter Identification Data Packet, Extended Power Transmitter Identification, ・PTx Extended Power Transmitter Identification Packet) ・PTx Extended Power Transmitter Extended Capabilities Packet (PTx Extended Power Transmitter Extended Capabilities Data Packet, ECAP data packet, Extended Power Transmitter Extended Capabilities)

[0259] The following describes the modulation index (frequency shift, modulation degree, depth) that is set when changing the "signal modulation method in communication related to information transmission from TX 100 to RX 200 and communication related to information transmission from RX 200 to TX 100." Details of the modulation index will be described in the second embodiment.

[0260] The TX100 or RX200 selects a modulation index according to the value of the "coupling status index between the transmitting antenna of the TX100 and the receiving antenna of the RX200." The TX100 or RX200 measures the coupling status between the transmitting antenna of the TX100 and the receiving antenna of the RX200 using the method described above. If the coupling status index (coupling status measurement value) indicating the coupling status is equal to or greater than a predetermined threshold, the TX100 or RX200 selects / sets a first modulation index. If the coupling status measurement value is less than or equal to the predetermined threshold, the TX100 or RX200 selects / sets a second modulation index. Here, a large coupling status measurement value indicates a strong coupling status, and a small coupling status measurement value indicates a weak coupling status. In this case, the second modulation index is controlled to be larger than the first modulation index. This is because, when the coupling condition index is small, communication becomes unstable, and therefore the modulation index is increased to improve the stability of communication.

[0261] The "modulation method" described in this embodiment can be applied to both a "primary modulation method" and a "secondary modulation method." Examples of the "primary modulation method" include ASK, PSK, FSK, and QAM. Examples of the "secondary modulation method" include direct sequence spread spectrum, frequency hopping, time division multiplexing, frequency division multiplexing, and code division multiplexing. Specific details of the "modulation method different from the modulation method used in BPP or EPP" will be described later.

[0262] The TX100 and the RX200 execute the controls shown in Figures 33 and 34 in parallel with the controls shown in Figures 14 and 15, respectively. The control of F3307 of the TX100 in Figure 33 corresponds to the control of F1413 in Figure 14. Furthermore, the control of F3408 of the RX200 in Figure 34 corresponds to the control of F1512 in Figure 14. In other words, when operating in the rapid charge mode, the TX100 and the RX200 are controlled to use a modulation method different from the modulation method used in BPP or EPP. Alternatively, when operating in the rapid charge mode, the TX100 and the RX200 may be controlled to use the modulation method used in BPP or EPP instead of a modulation method different from the modulation method used in BPP or EPP. By controlling in this manner, when the RX200 and the TX100 enter the rapid charge mode, it is possible to set / change the modulation method of signals in in-band communication related to information transmission from the RX to the TX. This makes it possible to apply a modulation method that is more suitable for rapid charging.

[0263] <Various Modifications> The roles of the controls described in F1404 to F1406 in FIG. 14 and F1504 to F1505 in FIG. 15 may be interchanged as follows.

[0264] For example, the TX 100 may notify the RX 200 of information for determining whether or not the "conditions for transitioning to the rapid charge mode" are met using a predetermined packet. The packet may use a Power Transmitter Capabilities (CAP) Data Packet. Alternatively, the packet may use a Power Transmitter Identification (ID) Data Packet. However, these packets may be sent as a response to a General Request (GRQ) Data Packet from the RX 200. Specifically, the TX 100 may first use a GRQ Data Packet to request the RX 200 to transmit information for determining whether or not the "conditions for transitioning to the rapid charge mode" are met. In response to the request, the TX 100 may transmit information for determining whether or not the "conditions for transitioning to the rapid charge mode" are met.

[0265] Furthermore, the RX 200 may determine that the "conditions for transitioning to the rapid charge mode" are met, and notify the TX 100 of this fact by a predetermined packet. The packet may be an ACK, which is a positive response.

[0266] The RX 200 may also request to transition to the "quick charge mode" using a predetermined packet. The packet may use the FOD Status Data Packet.

[0267] Furthermore, the information transmitted by the TX100 to the RX200 for determining whether the "conditions for transitioning to the rapid charge mode" are satisfied is, for example, information that "the TX100 is capable of supporting MPP." Alternatively, as described above in the description of the coupling status indicator measurement method, it is information about the TX100 that is required when the RX200 calculates the coupling status indicator. Alternatively, it may be a packet that includes information indicating the timing at which the RX200 acquires the value of the temperature sensor of the RX200. Alternatively, it may be a packet that includes information about the value of the temperature sensor of the TX100.

[0268] Alternatively, another modified example may be as follows. That is, first, the RX200 notifies the TX100 of information for executing the "foreign object detection process" or the "calculation of the coupling state index." Then, the TX100 executes the "foreign object detection process" or the "calculation of the coupling state index" based on the information received from the RX200. After that, the TX100 notifies the RX200 of the execution result of the "foreign object detection process" or the "calculation of the coupling state index." That is, the TX100 notifies the RX200 of the value of the coupling state index, the presence or absence of a foreign object, or the probability of the presence of a foreign object. Then, the RX200 compares the execution result of the "foreign object detection process" or the "calculation of the coupling state index" received from the TX100 with a threshold value stored in the RX200, and determines whether or not the "conditions for transitioning to the rapid charge mode" are met. Based on the result of the determination, the RX200 requests transition to the "rapid charge mode." In this case, a combination of the first to sixth conditions may also be used, and control may be performed so that when a combination of the first to sixth conditions is met, it is determined that the "conditions for transitioning to the rapid charge mode are met."

[0269] Furthermore, the RX200 may perform the operation of F1506 "notifying the power transmitting device of a request to transition to the rapid charge mode" in the Power Transfer phase. During the Power Transfer phase in BPP or EPP, the RX200 performs the operation of F1506 when it desires to receive even greater power or determines that a predetermined condition for receiving greater power has been met. In this case, the TX100 transmits an ACK, which is the operation of F1408, and the RX200 receives an ACK, which is the operation of F1507. Then, the TX100 proceeds to the operation of F1409 and executes Renegation corresponding to the power in the rapid charge mode. Then, the TX100 proceeds to the operation of F1410 and executes ReCAL corresponding to the power in the rapid charge mode. Then, the TX100 performs the operations of F1412, F1413, and F1414. The RX200 also shifts to the operation of F1508 and executes Renegotiation corresponding to the power in the rapid charge mode.The RX200 then shifts to the operation of F1509 and executes ReCAL corresponding to the power in the rapid charge mode.Then, the TX100 performs the operations of F1510 to F1513.

[0270] In the above-described embodiment, an example has been described in which the information indicating whether the rapid charge mode is supported is notified in the Negotiation phase, but the information may be notified in other phases. For example, the RX200 may notify the information indicating whether the rapid charge mode is supported using a Signal Strength Data Packet in the Ping phase. Alternatively, the RX200 may notify the information indicating whether the rapid charge mode is supported using an Identification Data Packet in the Configuration phase. Alternatively, the RX200 may use an Extended Identification Data Packet or a Configuration Data Packet. In this case, F1503 is performed before F1501 in FIG. 15 .

[0271] Alternatively, packets in the calibration phase or power transfer phase may be used. For example, RP1, RP2, or RP0 may be used. Therefore, the processing from F1503 onward is performed in the renegotiation phase after the calibration phase or power transfer phase.

[0272] In the above-described embodiment, the notification of information for determining whether the "conditions for transitioning to the rapid charge mode" are satisfied is performed in the Negotiation phase, but the notification may be performed in other phases. For example, the RX 200 may use a Signal Strength Data Packet in the Ping phase. Alternatively, the RX 200 may use an Identification Data Packet in the Configuration phase. Alternatively, the RX 200 may use an Extended Identification Data Packet or a Configuration Data Packet. In this case, F1504 is performed in advance of F1501 in FIG. 15 .

[0273] Alternatively, packets in the calibration phase or power transfer phase may be used. For example, RP1, RP2, or RP0 may be used. Therefore, the processing from F1503 onward is performed in the renegotiation phase after the calibration phase or power transfer phase.

[0274] In the above-described embodiment, the TX100 performs steps F1409 and F1410 before F1412. However, steps F1409 and F1410 may be performed after F1412, and steps F1413 and F1414 may also be performed. Furthermore, the RX200 performs steps F1508 and F1509 before F1511. However, steps F1508 and F1509 may be performed after F1511, and steps F1512 and F1513 may also be performed. In other words, if authentication is successful, the TX100 and RX200 perform Negotiation / Renegotiation and CAL / ReCAL corresponding to the rapid charge mode. Then, they perform control during rapid charge mode operation and start power transmission and reception in the rapid charge mode.

[0275] In the first embodiment described above, the TX100 operates in a case where it is determined after F1415 in FIG. 14 that it will operate in BPP or EPP rather than in the rapid charge mode. Alternatively, the TX100 may operate in a case where it is determined after F1415 in FIG. 14 that it will operate in an MPP other than the rapid charge mode rather than in the rapid charge mode. In the first embodiment described above, the RX200 operates in a case where it is determined after F1514 in FIG. 15 that it will operate in BPP or EPP rather than in the rapid charge mode. Alternatively, the TX200 may operate in a case where it is determined after F1514 in FIG. 15 that it will operate in an MPP other than the rapid charge mode rather than in the rapid charge mode. Here, "an MPP other than the rapid charge mode" refers to a mode in which the TX100 transmits power of 15 watts or less to the RX200 in an MPP that has a function of accurately fixing the TX100 and the RX200 to predetermined positions. Alternatively, in an MPP having a function for fixing the TX 100 and the RX 200 at predetermined positions with high precision, this indicates a mode in which the RX 200 receives power of 15 watts or less from the TX 100.

[0276] [Second Embodiment] In this embodiment, the control performed by the TX100 and RX200 will be described in F1413 of FIG. 14 , which is the flowchart for the TX100, and F1512 of FIG. 15 , which is the flowchart for the RX200, as described in the first embodiment. Specifically, the control performed during rapid charge mode operation, which is not performed in BPP or EPP, will be described. As described above, in rapid charge mode, the TX100 transmits more power to the RX200 than in BPP or EPP. Therefore, the following problems arise in rapid charge mode: - More noise leaks from the power transmitting (receiving) antenna to the surroundings than in BPP or EPP operation - Faster and more stable communication is required than in BPP or EPP operation - Foreign object detection accuracy is lower than in BPP or EPP operation

[0277] The control performed during the rapid charge mode operation to solve the above problems will be described in detail below.

[0278] <Noise Leaking to the Surroundings> As a first method for suppressing noise leaking to the surroundings from the transmitting antenna and the receiving antenna, a method of changing the transmission power from the TX100 to the RX200 according to the coupling state index of the transmitting antenna and the receiving antenna will be described. First, a method of the TX100 reducing the transmission power to the RX200 according to the coupling state index of the transmitting antenna and the receiving antenna will be described. The TX100 and the RX200 measure / calculate the coupling state index of the transmitting antenna and the receiving antenna. A case where the coupling state index of the transmitting antenna and the receiving antenna is smaller (weak) than a predetermined threshold is hereinafter referred to as a weak coupling state. A case where the coupling state index of the transmitting antenna and the receiving antenna is larger (strong) than a predetermined threshold is hereinafter referred to as a strong coupling state.

[0279] When the TX 100 and the RX 200 recognize that they are in a weakly coupled state, they control the power by reducing the transmission power compared to when they are in a strongly coupled state. The power source of the power transmitted from the TX 100 can also be a noise source. Therefore, by reducing the transmission power, it is possible to suppress noise leaking to the surroundings from the transmitting antenna and the receiving antenna. The control unit 101 of the TX 100 controls the power transmitting unit 103 to set the transmission power to a predetermined power value or less. The power transmitted from the power transmitting antenna 105 is limited to a predetermined power value or less.

[0280] Another method for reducing the transmission power of the TX100, or the receiving power of the RX200, is for the TX100 and RX200 to negotiate and determine a GP in the renegotiation phase. The RX200 transmits Requested Load Power information to the TX100. The Requested Load Power is the value of power that the RX200 requests the TX100 to output to the load. This power is the power consumed by the load. The load refers to a system to which power is supplied from the RX200 or the power receiving unit of the RX200, such as the charging unit 206 and battery 207 of the RX200.

[0281] On the other hand, the TX 100 has a Potential Load Power value or a Negotiable Load Power value in advance. The Potential Load Power is the maximum load power value (Highest Load Power Level) that the TX 100 can negotiate and that can be output (supplied) to the load of the RX 200. The Negotiable Load Power is the maximum load power value (Highest Load Power Level) that the TX 100 can negotiate and that can be output (supplied) to the load of the RX 200 during a predetermined period or under predetermined conditions. Negotiation is successful when the value of Requested Load Power is smaller than the value of Negotiable Load Power. TX100 and RX200 set the value of Requested Load Power as the value of GP and store it in memory. That is, TX100 receives the value of Requested Load Power from RX200, and if that value is smaller than the value of Negotiable Load Power, it sends an acknowledgement ACK to RX200. TX100 and RX200 set the value of Requested Load Power as the value of GP and store it in memory.

[0282] Furthermore, TX100 receives the Requested Load Power value from RX200, and if that value is greater than the Negotiable Load Power value, it transmits a negative acknowledgement NAK to RX200. RX200 reduces the Requested Load Power value and again transmits information indicating the Requested Load Power value to TX100. RX200 repeats this process until it receives an acknowledgement ACK from TX100. When RX200 receives the acknowledgement ACK from TX100, TX100 and RX200 set the Requested Load Power value as the GP value and store it in memory.

[0283] By setting the value of GP to a predetermined value or less, the transmission power of the TX 100 can be reduced, and the receiving power of the RX 200 can be reduced. To this end, the TX 100 sets the Potential Load Power or the Negotiable Load Power to a predetermined value or less. Alternatively, the RX 200 sets the value of the Requested Load Power to a predetermined value or less. Note that the above control may be performed in the negotiation phase. Furthermore, the TX 100 may switch the inverter included in the power transmitting unit 103 from a full-bridge switching circuit to a half-bridge switching circuit.

[0284] In the above example, the operation of the TX100 and the RX200 when it is recognized that the TX100 and the RX200 are in a weakly coupled state has been described. Meanwhile, if a foreign object (such as a metal piece) that existed between the power transmitting antenna and the power receiving antenna is removed, or if the misalignment between the power transmitting antenna and the power receiving antenna is eliminated and they are positioned directly opposite each other, the coupling state between the power transmitting antenna and the power receiving antenna changes from a weakly coupled state to a strongly coupled state. Alternatively, if the distance between the power transmitting antenna and the power receiving antenna is reduced, the coupling state between the power transmitting antenna and the power receiving antenna changes from a weakly coupled state to a strongly coupled state. The following describes the operation when the coupling state between the power transmitting antenna and the power receiving antenna changes from a weakly coupled state to a strongly coupled state. The TX100 and the RX200 calculate (measure) a coupling state index using the above-described coupling state index measurement method and compare the calculated coupling state index with a set threshold.

[0285] The threshold setting method is as described above. Then, it is recognized that the TX100 and the RX200 are in a strongly coupled state. When it is recognized that the TX100 and the RX200 are in a strongly coupled state, control is performed to increase the transmission power of the TX100 (to increase the received power of the RX200) compared to when they are in a weakly coupled state. In this case, by setting the GP value to a predetermined value or higher, it is possible to increase the transmission power of the TX100 (to increase the received power of the RX200).

[0286] To achieve this, the TX 100 sets the Potential Load Power or the Negotiable Load Power to a predetermined value or higher. Alternatively, the RX 200 sets the value of the Requested Load Power to a predetermined value or higher. Note that the above control may be performed in the Negotiation phase or the Renegation phase. Furthermore, the TX 100 may switch the inverter included in the power transmitting unit 103 from a switching circuit with a half-bridge configuration to a switching circuit with a full-bridge configuration.

[0287] Furthermore, in the power transfer phase, the TX100 or the RX200 calculates (measures) a coupling status index using the above-described coupling status index measurement method at a predetermined timing, and compares the calculated coupling status index with a set threshold to determine the coupling status. The predetermined timing occurs at a predetermined cycle, or occurs when the TX100 receives a predetermined packet from the RX200. Alternatively, the predetermined timing occurs when the RX200 receives a predetermined packet from the TX100. The TX100 or the RX200 may control the transmission power using the above-described method depending on the result of the coupling status determination.

[0288] Next, a second method for suppressing noise leakage from the transmitting and receiving antennas to the surroundings will be described, in which the TX 100 changes the frequency band of the transmitting wave. Noise occurs in the frequency band used to transmit power from the transmitting antenna to the receiving antenna (hereinafter referred to as the operating frequency band). Note that, throughout this specification, the term "operating frequency band" may be interpreted as "operating frequency." Furthermore, harmonic noise occurs in a frequency band higher than the operating frequency band. If another system uses the frequency band in which noise occurs, this may cause malfunctions in the other system. Therefore, when operating in fast charging mode, the TX 100 and RX 200 control the operating frequency band to change from a first frequency band to a second frequency band. Changing the frequency band of noise leaking from the transmitting and receiving antennas to the surroundings can suppress the impact on other systems. The operating frequency band specified in the WPC standard is between 87 kHz and 205 kHz. When the TX100 and the RX200 recognize that they are operating in the rapid charge mode, they change the frequency band they use to a frequency band lower than 87 kHz or a frequency band higher than 205 kHz.

[0289] Next, a method using a noise suppression circuit will be described as a third method for suppressing noise leaking from the power transmitting antenna and the power receiving antenna to the surrounding area. The TX 100 or the RX 200 has a noise suppression circuit. For example, the noise suppression circuit is mounted on the circuit board of the TX 100 and is configured with inductors, capacitors, resistors, filters, and noise suppression components (ferrite, etc.) connected to the power transmitting antenna 105, the power transmitting unit 103, and the first communication unit 104. The noise suppression circuit is also mounted on the circuit board of the RX 200 and is configured with inductors, capacitors, resistors, filters, and noise suppression components (ferrite, etc.) connected to the power receiving antenna 205, the power receiving unit 203, and the first communication unit 204. The noise suppression circuit is configured according to the frequency band used. This is because the noise source is based on the power transmitted by the TX 100, and the frequency band of the generated noise is determined depending on the frequency band used. Therefore, the TX 100 or the RX 200 has a noise suppression circuit for each frequency band used. When operating in the rapid charging mode, the TX100 and the RX200 change the operating frequency band from the first frequency band to the second frequency band and perform noise suppression control by switching to a noise suppression circuit corresponding to the changed operating frequency band.

[0290] Next, as a fourth method for suppressing noise leaking from the transmitting antenna and the receiving antenna to the surroundings, a method for changing the parameters of the frequency shift keying used by the TX 100 for communication with the RX 200 will be described. Also, a method for changing the parameters of the load modulation, amplitude modulation, or backscatter modulation used by the RX 200 for communication with the TX 100 will be described.

[0291] In communication for transmitting information from the TX 100 to the RX 200, the first communication unit 104 of the TX 100 performs frequency shift keying of the electromagnetic waves output from the power transmitting antenna 105. In this case, the TX 100 transmits information by changing the frequency of the carrier wave (power transmission waveform). When two frequencies are used, the TX 100 associates a relatively high frequency signal with first information (e.g., "1") and a relatively low frequency signal with second information (e.g., "0"). The TX 100 transmits (transmits power) while switching between the two frequencies, and transmits information to the RX 200.

[0292] The TX 100 also switches the frequency of the carrier wave between a first operating frequency (denoted as fop) corresponding to an unmodulated state and a second operating frequency (denoted as fmod) corresponding to a modulated state, and transmits information to the RX 200. fop and fmod are defined by two parameters.

[0293] The first parameter is polarity, which indicates whether the difference between fmod and fop (fmod-fop) is positive or negative. Changing the polarity makes it possible to suppress noise in a specific frequency band. Noise in the frequency band used for communication, or harmonic noise in a frequency band higher than that frequency band, can cause malfunctions in other systems. Changing the polarity makes it possible to change the frequency band used for communication. The second parameter is modulation index (frequency deviation, modulation depth), which indicates the magnitude (absolute value) of the difference between fmod and fop. The larger the modulation index, the greater the magnitude of the difference between fmod and fop. Therefore, the bandwidth of noise in a specific frequency band leaking from the transmitting antenna and the receiving antenna to the surrounding area becomes wider. When the TX100 and RX200 operate in fast charging mode, strong noise may occur over a wider bandwidth during power transmission.

[0294] Therefore, when the TX100 and the RX200 operate in the rapid charge mode, the TX100 and the RX200 control the values ​​of the first and second parameters to predetermined values ​​in communication when transmitting information from the TX100 to the RX200.

[0295] For example, when the TX100 and the RX200 operate in fast charging mode, the polarity is controlled to be negative (positive). By changing the polarity, the frequency band used for communication can be controlled. This makes it possible to suppress noise in a specific frequency band leaking from the transmitting antenna and the receiving antenna to the surrounding area.

[0296] Furthermore, when the TX100 and the RX200 operate in the fast charge mode, they control the modulation index (frequency deviation, modulation degree, depth) to be small. Because the difference between fmod and fop is small, it is possible to narrow the bandwidth of noise in a specific frequency band that leaks from the transmitting antenna and the receiving antenna to the surrounding area.

[0297] The first and second parameters can be included in a Configuration Data Packet that RX200 transmits in the configuration phase. When RX200 recognizes that TX100 and RX200 operate in the fast charge mode, RX200 sets the values ​​of two parameters related to frequency shift keying in the Configuration Data Packet to predetermined values ​​and transmits the packet to TX100. TX100 performs frequency shift keying based on the values ​​of the two parameters in the received packet and transmits information to RX200.

[0298] The packet used by RX 200 to transmit the values ​​of the first and second parameters to TX 100 is a Signal Strength Data packet or an Identification Data packet. Alternatively, it may be an Extended Identification Data packet. Alternatively, it may be a packet in the Calibration phase or the Power Transfer phase, i.e., RP1, RP2, or RP0. Hereinafter, these packets are collectively referred to as a "predetermined packet."

[0299] Next, a method for changing parameters of load modulation, amplitude modulation, or backscatter modulation used when the RX 200 performs communication to transmit information to the TX 100 will be described. The first communication unit 204 of the RX 200 performs load modulation, amplitude modulation, or backscatter modulation of the electromagnetic waves output from the transmitting antenna 105 of the TX 100, and transmits information to the TX 100 for communication. At this time, the RX 200 changes the amplitude of the carrier wave (transmission waveform) to transmit the information. When two amplitude magnitudes are used, the RX 200 associates a signal with a relatively large amplitude with first information (e.g., "1") and a signal with a relatively small amplitude with second information (e.g., "0"). The RX 200 transmits information to the TX 100 by superimposing a signal on the transmission waveform while switching the amplitude magnitude.

[0300] The RX 200 transmits information to the TX 100 by switching the amplitude of the carrier wave between the following two amplitudes: Amplitude Amp_A in the Hi-State state (relatively large amplitude) Amplitude Amp_B in the Low-State state (relatively small amplitude)

[0301] The magnitude of the difference between Amp_A and Amp_B is called the modulation depth. The greater the modulation depth, the greater the change in the carrier frequency, and therefore the wider the bandwidth of noise in a specific frequency band leaking from the transmitting antenna and the receiving antenna to the surroundings. Therefore, when the TX100 and the RX200 operate in fast charge mode, there is a possibility that strong noise will be generated over a wider bandwidth during power transmission. Therefore, when the TX100 and the RX200 operate in fast charge mode, the TX100 and the RX200 control the modulation depth to a predetermined value in communication from the RX200 to the TX100. More specifically, control is performed to reduce the modulation depth, and the magnitude of the difference between the amplitude Amp_A and the amplitude Amp_B becomes smaller. Therefore, it is possible to narrow the bandwidth of noise in a specific frequency band leaking from the transmitting antenna and the receiving antenna to the surroundings.

[0302] When performing the above process, the RX 200 may notify the TX 100 of the modulation factor to be used in advance using a predetermined packet. For example, the information on the modulation factor to be used may be included in the Configuration Data Packet that the RX 200 transmits in the Configuration phase. When operating in the fast charge mode, the RX 200 sets the value of the parameter (modulation factor) related to load modulation, amplitude modulation, or backscatter modulation in the Configuration Data Packet to a predetermined value and transmits the packet to the TX 100. The TX 100 controls the transmission wave type based on the value of the parameter (modulation factor) related to load modulation, amplitude modulation, or backscatter modulation included in the received packet. Note that the packet used by the RX 200 to transmit information on the parameter (modulation factor) related to load modulation, amplitude modulation, or backscatter modulation to the TX 100 may be the above-mentioned predetermined packet.

[0303] Next, as a fifth method for suppressing noise leakage from the transmitting antenna and the receiving antenna to the surroundings, a method of changing the modulation method for communication from TX to RX and from RX to TX will be described. An example of a modulation method is a spread spectrum method, in which communication is performed using a signal having a wide frequency band that exceeds the frequency band required for information transmission. Specifically, a first method is a direct sequence spread spectrum (DSSS) method.

[0304] For example, when operating in the fast charge mode, the first communication unit 104 of the TX 100 performs arithmetic processing on the original frequency-shift-keyed signal using a spreading signal called a spreading code (PN: Pseudo Noise) or pseudorandom noise. The first method is a method of directly spreading energy over a frequency band wider than the frequency band required for transmitting the original signal. The TX 100 transmits the processed signal to the RX 200. The RX 200 stores data of the spreading signal used by the TX 100 for the arithmetic processing in advance in the memory 208. The RX 200 performs an inverse conversion on the received signal using the spreading signal to obtain the original frequency-shift-keyed signal. Furthermore, when the RX 200 recognizes that the TX 100 and the RX 200 are operating in the fast charge mode during transmission from the RX 200 to the TX 100, the following processing is performed. That is, the first communication unit 204 of the RX 200 performs arithmetic processing on the original load-modulated, amplitude-modulated, or backscatter-modulated signal using the spreading signal. The RX 200 transmits the processed signal to the TX 100. The TX 100 stores in advance in the memory 106 the data of the spreading signal used by the RX 200 for the calculation process. The TX 100 performs an inverse transformation on the received signal using the spreading signal to obtain the original signal that has been load modulated, amplitude modulated, or backscatter modulated. By using the first method, it is possible to reduce the magnitude (level) of noise in a specific frequency band that leaks into the surroundings from the transmitting antenna and the receiving antenna.

[0305] The second method is the frequency hopping method (FHSS: Frequency Hopping Spread Spectrum). In this method, the frequency band allocated for communication is divided into multiple frequency slots, and the frequency slots used for communication are rapidly switched in a short period of time according to a frequency switching pattern. In other words, transmission is performed by switching between different bands within a wide frequency band in a short period of time. The frequency slots are also called "hopping channels." The frequency switching pattern is called a hopping sequence or hopping pattern. The TX 100 and the RX 200 can receive signals in their respective frequency bands according to a hopping sequence known in advance and obtain the original signal.

[0306] For example, when transmitting from TX100 to RX200, if TX100 and RX200 operate in fast charge mode, the first communication unit 104 of TX100 performs a process of transmitting the original frequency shift keyed signal using a frequency slot according to the hopping sequence.

[0307] The TX 100 transmits the processed signal to the RX 200. The RX 200 stores in advance in the memory 208 the data of the hopping sequence used by the TX 100 for processing. The RX 200 performs an inverse transformation on the received signal according to the hopping sequence to obtain the original signal that has been frequency shift modulated. Furthermore, when operating in the fast charge mode, the first communication unit 204 of the RX 200 performs processing to transmit the original signal that has been load modulated, amplitude modulated, or backscatter modulated, using a frequency slot in accordance with the hopping sequence. The RX 200 transmits the processed signal to the TX 100. The TX 100 stores in advance in the memory 106 the data of the hopping sequence used by the RX 200 for processing. The TX 100 performs an inverse transformation on the received signal according to the hopping sequence to obtain the original signal that has been load modulated, amplitude modulated, or backscatter modulated. By using the second method, it is possible to reduce the magnitude (level) of noise in a specific frequency band that leaks from the power transmitting antenna and the power receiving antenna to the surrounding area.

[0308] The third method combines direct sequence spread spectrum processing with frequency hopping processing, making it possible to further reduce the level of noise in a specific frequency band leaking from the transmitting and receiving antennas.

[0309] Information indicating which of the first to third methods is to be used or whether the method is supported can be included in the Configuration Data Packet transmitted by the RX200 in the Configuration phase. When the TX100 and the RX200 operate in the rapid charge mode, the RX200 stores data (e.g., "1") indicating the use of one of the first to third methods in a predetermined field in the Configuration Data Packet. Alternatively, "1" is stored in the field as data corresponding to the use of the first method, "2" is stored as data corresponding to the use of the second method, and "3" is stored as data corresponding to the use of the third method. When the RX200 recognizes that the TX100 and the RX200 do not operate in the rapid charge mode, it does not use any of the first to third methods and therefore stores "0" in the field. Alternatively, information indicating whether the RX 200 supports each of the first to third methods is stored in a predetermined field. If the method is supported, the data "1" is stored in the field, and if the method is not supported, the data "0" is stored in the field. Upon receiving the Configuration Data Packet from the RX 200, the TX 100 transmits information to the RX 200 and receives information from the RX 200 based on the modulation method information in the packet. Note that the packet used by the RX 200 to transmit information indicating which of the first to third methods to use or which method is supported to the TX 100 may be the predetermined packet.

[0310] Information indicating which of the first to third methods is to be used or whether or not the method is supported can be included in the following packets: a Power Transmitter Capabilities (CAP) Data Packet or a Power Transmitter Identification (ID) Data Packet transmitted by the TX 100. For example, the TX 100 stores data (e.g., "1") indicating that one of the first to third methods will be used in a predetermined field in the Power Transmitter Capabilities (CAP) Data Packet. Similarly, when a Power Transmitter Identification (ID) data packet is used, data (e.g., "1") indicating the use of one of the first to third methods is stored in a predetermined field. Alternatively, "1" is stored in the field as data corresponding to the use of the first method, "2" is stored as data corresponding to the use of the second method, and "3" is stored as data corresponding to the use of the third method. When the TX100 and the RX200 do not operate in fast charge mode, the RX200 does not use any of the first to third methods, and therefore stores "0" in the field. Alternatively, information indicating whether the TX100 supports each of the first to third methods is stored in a predetermined field. If the method is supported, the data "1" is stored in the field, and if the method is not supported, the data "0" is stored in the field. Upon receiving the Power Transmitter CAP Data Packet or the Power Transmitter ID Data Packet, the RX 200 transmits or receives information to or from the TX 100 in accordance with the modulation method specified in the packet.

[0311] When executing the above process, the RX200 may notify the TX100 of the modulation method to be used in advance by a predetermined packet. For example, information about the modulation method to be used can be included in the Configuration Data Packet that the RX200 transmits in the Configuration phase. When the TX100 and the RX200 operate in the fast charge mode, the RX200 sets a predetermined value in a field in the packet that indicates the modulation method to be used by the RX200, and transmits the packet to the TX100. The TX100 transmits information to the RX200 and receives information from the RX200 based on the information about the modulation method to be used by the RX200 that is included in the received packet.

[0312] When performing the above process, the TX100 may notify the RX200 of the modulation method to be used in advance using a predetermined packet. For example, information on the modulation method to be used can be included in the Power Transmitter CAP Data Packet or Power Transmitter ID data packet transmitted by the TX100. When the TX100 and the RX200 operate in the fast charge mode, the TX100 sets a predetermined value in a field in the packet that indicates the modulation method to be used by the TX100, and transmits the packet to the RX200. The RX200 transmits information to and receives information from the TX100 based on the information on the modulation method to be used by the TX100 that is included in the received packet.

[0313] In the above-described method, RX200 notifies TX100 of information about the modulation method to be used by a predetermined packet in advance. Then, TX100 and RX200 may negotiate with each other through communication based on that information and determine the modulation method to be used for communication. Alternatively, in the above-described method, TX100 notifies RX200 of information about the modulation method to be used by a predetermined packet in advance. Then, TX100 and RX200 may negotiate with each other through communication based on that information and determine the modulation method to be used for communication.

[0314] Next, a sixth method for suppressing noise leakage from the transmitting antenna and the receiving antenna to the surroundings, in which the TX100 switches the transmitting antenna (power transmitting coil), will be described. When the TX100 and the RX200 operate in fast charging mode, the TX100 transmits high power to the RX200, resulting in increased noise leakage to the surroundings. Another cause of increased noise is a large difference in size between the transmitting antenna and the receiving antenna. For example, consider a case where the transmitting antenna is larger than the receiving antenna. In this case, because the size of the receiving antenna is relatively small, when transmitting power from the TX100 to the RX200, some of the magnetic flux generated from the transmitting antenna does not penetrate the inside of the receiving antenna. The greater the difference in size between the transmitting antenna and the receiving antenna, the greater the leakage magnetic flux. To solve this problem, the TX100 has two or more transmitting antennas. For example, of two power transmitting antennas, the larger power transmitting antenna is referred to as the "power transmitting antenna (large)" and the smaller power transmitting antenna is referred to as the "power transmitting antenna (small)."

[0315] Assume that the TX100 selects the large transmitting antenna, measures / calculates the coupling state index between the transmitting antenna and the receiving antenna using the method described above, compares it with a threshold, and determines that the coupling state is weak. In this case, the TX100 selects the small transmitting antenna. Then, using the method described above, the TX100 measures / calculates the coupling state index between the transmitting antenna and the receiving antenna, and again compares it with a threshold to determine whether the coupling state is weak. Assume that the determination result shows that the coupling between the transmitting antenna and the receiving antenna is stronger than when the large transmitting antenna was selected. In this case, the TX100 controls to use the small transmitting antenna in each subsequent phase.

[0316] Also, suppose that the TX100 initially selects the small transmitting antenna, measures / calculates the coupling state index between the transmitting antenna and the receiving antenna using the method described above, compares it with a threshold, and recognizes that the coupling state is weak. In this case, the TX100 selects the large transmitting antenna. Then, using the method described above, the TX100 measures / calculates the coupling state index between the transmitting antenna and the receiving antenna, compares it with a threshold, and again determines whether the coupling state is weak. As a result of the determination, suppose that the coupling between the transmitting antenna and the receiving antenna is stronger than when the small transmitting antenna was selected. In this case, the TX100 controls to use the large transmitting antenna in each subsequent phase.

[0317] The TX 100 may have three or more transmitting antennas of different sizes. The TX 100 measures and determines the coupling state between the transmitting antenna and the receiving antenna when each transmitting antenna is used. In each of the subsequent phases, the TX 100 controls to use the transmitting antenna with the best coupling state.

[0318] Alternatively, as shown in the first method, the RX200 notifies the TX100 of detailed information about the hardware of the power receiving device using a predetermined packet. More specifically, the RX200 notifies the TX100 of the size, type, etc. of the power receiving antenna (power receiving coil). The TX100 receives a predetermined packet from the RX200 and selects a power transmitting antenna that is determined to be optimal for the target power receiving antenna based on information such as the size and type of the power receiving antenna (power receiving coil). The TX100 or the RX200 measures a coupling status index between the power transmitting antenna and the power receiving antenna and determines whether a value indicating the coupling status (e.g., k value) is equal to or greater than a threshold. In each of the subsequent phases, the TX100 performs control to use the power transmitting antenna with the best coupling status selected based on the determination result.

[0319] Next, as a seventh method for suppressing noise leakage from the power transmitting antenna and the power receiving antenna to the surroundings, a method of modifying the circuit to increase the Quality Factor of the circuit related to power transmission, including the power transmitting antenna, will be described. The power transmission efficiency from the TX100 to the RX200 is expressed as the product of the coupling coefficient k and the Quality Factor (Q-factor, quality factor, Q value). When the TX100 and the RX200 operate in fast charging mode, the decrease in transmission efficiency can be suppressed by controlling the Quality Factor value to be high. When the TX100 and the RX200 operate in fast charging mode, the TX100 (or the RX200) modifies the circuit to increase the Quality Factor of the circuit related to power transmission, including the power transmitting antenna (or the power receiving antenna). Specifically, a first control is performed to switch the power transmitting antenna 105 (or the power receiving antenna 205) to a power transmitting antenna (or a power receiving antenna) having a different size or a different inductance value.

[0320] Alternatively, a second control is performed to switch the resonant capacitor 107 (or the resonant capacitor 211) to a resonant capacitor with a different constant. Alternatively, a third control is performed to connect a new capacitor or inductor to the power transmitting antenna 105 (or the power receiving antenna 205) or the resonant capacitor 107 (or the resonant capacitor 211). All of the first, second, and third controls may be performed, or at least one of them may be performed. The first, second, and third controls may be performed when the RX200, having recognized that the TX100 and the RX200 will operate in the rapid charge mode, notifies the TX100 of this using a packet. Alternatively, the TX100, having recognized that the TX100 and the RX200 will operate in the rapid charge mode, may be performed when the TX100, having recognized that the TX100 and the RX200 will operate in the rapid charge mode, notifies the RX200 of this using a predetermined packet.

[0321] <Communication> Next, a first method for suppressing instability in communication between the TX100 and the RX200 will be described. When the TX100 and the RX200 operate in rapid charge mode, the TX100 and the RX200 need to perform rapid control in order to improve transmission efficiency. Therefore, stable communication is required for the communication between the TX100 and the RX200 to perform control. Therefore, a method for stabilizing communication will be described. Specifically, a first change method for changing parameters of frequency shift keying used in transmitting signals from the TX100 and a second change method for changing parameters of load modulation, amplitude modulation, or backscatter modulation used in transmitting signals from the RX200 will be described.

[0322] First, in the first modification method, the frequency shift keying parameter is the modulation index (frequency shift, modulation degree, depth), which represents the magnitude of the difference between fmod and fop. The larger the modulation index, the larger the magnitude of the difference between fmod and fop, making it easier for the RX200 to demodulate the signal received from the TX100. Therefore, when the TX100 and the RX200 operate in the fast charge mode, the TX100 and the RX200 control the modulation index to a predetermined value in communication when transmitting information from the TX100 to the RX200. More specifically, when the TX100 and the RX200 operate in the fast charge mode, the modulation index is controlled to be larger compared to when operating in BPP or EPP, making it easier for the RX200 to demodulate the signal received from the TX100.

[0323] The modulation index can be included in the Configuration Data Packet that RX200 transmits in the Configuration phase. When RX200 recognizes that TX100 and RX200 operate in the fast charge mode, RX200 sets the modulation index in the Configuration Data Packet to a predetermined value and transmits the packet to TX100. TX100 transmits information from TX100 to RX200 based on the modulation index included in the received packet. The packet that RX200 uses to transmit information about the modulation index to TX100 may be the predetermined packet.

[0324] Next, a second change method will be described. As described above, for example, the RX200 switches the amplitude of the carrier wave between a relatively large amplitude Amp_A and a relatively small amplitude Amp_B to transmit information to the TX100. The larger the modulation depth, which corresponds to the magnitude of the difference between Amp_A and Amp_B, the easier it is for the TX100 to demodulate the signal transmitted by the RX200. Therefore, when the TX100 and the RX200 operate in the rapid charge mode, the TX100 and the RX200 control the modulation depth of amplitude modulation or load modulation to a predetermined value in communication transmitting information from the RX200 to the TX100. More specifically, when the TX100 and the RX200 operate in the rapid charge mode, the modulation depth is controlled to be larger than when operating in BPP or EPP. This increases the difference between the amplitude Amp_A in the Hi-State state and the amplitude Amp_B in the Low-State state, making it easier for the TX 100 to demodulate the signal transmitted by the RX 200 .

[0325] When executing the above process, the RX 200 may notify the TX 100 of the modulation factor to be used in advance using a predetermined packet. This is as described above, and the same applies to the predetermined packet used to transmit the modulation factor, so the explanation of these will be omitted.

[0326] Next, a method for changing the communication method for communication between the TX100 and the RX200 (a second method for suppressing instability in communication between the TX100 and the RX200) will be described. In order for the TX100 and the RX200 to perform high-speed control, it is necessary to make the communication between the TX100 and the RX200 faster. Therefore, the TX100 and the RX200 perform control to change the communication method when they recognize that they are operating in a rapid charging mode. Control is performed to change the communication method between the second communication unit 109 of the TX100 and the second communication unit 212 of the RX200 to one based on a standard other than the WPC standard. Examples of such communication methods include wireless LAN, BLE, and NFC. The second communication unit 109 of the TX100 communicates with the RX200 using an antenna different from the power transmitting antenna 105. The second communication unit 212 of the RX 200 communicates with the TX 100 using an antenna different from the power receiving antenna 205. The frequency band used for communication by the second communication unit 109 and the second communication unit 212 is different from the frequency band used for power transmission. In this way, when the TX 100 and the RX 200 operate in the quick charge mode, the TX 100 and the RX 200 can perform stable communication using a communication method different from the communication method using the power transmitting antenna 105 and the power receiving antenna 205.

[0327] The RX200 can include information on whether or not the RX200 supports a communication method based on a standard other than the WPC standard in the Configuration Data Packet transmitted in the Configuration phase. Alternatively, the RX200 can include data indicating which communication method will be used among the communication methods based on standards other than the WPC standard in the Configuration Data Packet. For example, when the RX200 recognizes that it operates in the fast charge mode, it stores data (e.g., "1") indicating that a communication method based on a standard other than the WPC standard will be used in a predetermined field in the Configuration Data Packet. Alternatively, "1" corresponding to the use of a wireless LAN or "2" corresponding to the use of BLE is stored in the field. Furthermore, "3" corresponding to the use of NFC is stored in the field. Furthermore, when the TX100 and RX200 do not operate in rapid charge mode, that is, when they operate in BPP or EPP, "0" is stored in this field, which corresponds to the case where a communication method based on a standard other than the WPC standard is not used. Alternatively, information indicating whether the RX200 supports each communication method is stored in a predetermined field. If the communication method is supported, "1" is stored as data in this field, and if the method is not supported, "0" is stored as data. The RX200 transmits the packet to the TX100.

[0328] Based on the information about the communication method included in the received Configuration Data Packet, the TX 100 transmits information from the TX 100 to the RX 200. Note that the packet used by the RX 200 to transmit to the TX 100 information about whether or not the TX 100 supports a communication method based on a standard other than the WPC standard may be the above-mentioned predetermined packet.

[0329] When executing the above process, the RX200 may notify the TX100 of the communication method to be used in advance by a predetermined packet. For example, information about the communication method to be used can be included in a Configuration Data Packet that the RX200 transmits in the Configuration phase. When the RX200 recognizes that the TX100 and the RX200 operate in the fast charge mode, the RX200 sets a field in the packet indicating the communication method to be used by the RX200 to a predetermined value, and transmits the packet to the TX100. The TX100 determines the communication method based on information about the communication method to be used by the RX200 that is included in the received packet. Note that the packet that the RX200 uses to transmit information about the communication method to be used to the TX100 may be the predetermined packet.

[0330] The TX100 can include in a predetermined packet information indicating whether or not the TX100 supports a communication method based on a standard other than the WPC standard, or data indicating which communication method of the communication methods based on standards other than the WPC standard will be used. For example, when the TX100 recognizes that the TX100 and the RX200 are operating in rapid charge mode, the TX100 stores data (e.g., "1") indicating that a communication method based on a standard other than the WPC standard will be used in a predetermined packet field. Alternatively, "1" corresponding to the use of wireless LAN or "2" corresponding to the use of BLE is stored in the field. Furthermore, "3" corresponding to the use of NFC is stored in the field. Furthermore, when the TX100 and the RX200 do not operate in rapid charge mode, that is, when operating in BPP or EPP, "0" corresponding to the use of a communication method based on a standard other than the WPC standard is stored in the field. The TX100 transmits the packet to the RX200. Alternatively, information indicating whether the TX100 supports each communication method is stored in a predetermined field. If the communication method is supported, the data "1" is stored in the field, and if the method is not supported, the data "0" is stored in the field. The RX 200 transmits information to the TX 100 based on the communication method information contained in the received predetermined packet.

[0331] When executing the above process, the TX 100 may notify the RX 200 of the communication method to be used in advance by a predetermined packet. When the TX 100 recognizes that the TX 100 and the RX 200 operate in the quick charge mode, the TX 100 sets a field in the packet indicating the communication method to be used by the TX 100 to a predetermined value, and transmits the packet to the RX 200.

[0332] The RX 200 determines the communication method based on the information on the communication method used by the TX 100 contained in the received packet.

[0333] <Foreign Object Detection Accuracy> Next, a first method for improving the detection accuracy of a foreign object present between the TX100 and the RX200 will be described. When the TX100 and the RX200 operate in fast charge mode, the detection accuracy of foreign object detection using the Q-factor measurement method or the Power Loss method specified in the WPC standard may decrease. Therefore, when the TX100 and the RX200 operate in fast charge mode, the TX100 and the RX200 use a foreign object detection method other than that specified in the WPC standard.

[0334] As a first foreign object detection method other than that specified in the WPC standard, a method for detecting a foreign object based on the coupling state between the power transmitting antenna and the power receiving antenna will be described. When a weak coupling state is recognized, the presence or absence of a foreign object can be detected based on the coupling state between the power transmitting antenna and the power receiving antenna. As described in the coupling state indicator measurement method, the TX100 and the RX200 measure the coupling state indicator between the power transmitting antenna and the power receiving antenna and perform foreign object detection processing based on the measurement value. Also, a method for setting a threshold value for determining the possibility of the presence or absence of a foreign object has already been described. In the case of a weak coupling state, the possibility of the presence or absence of a foreign object can be determined with higher accuracy based on the measurement result of the coupling state indicator between the power transmitting antenna and the power receiving antenna. Measuring the coupling state indicator between the power transmitting antenna and the power receiving antenna and determining the possibility of the presence or absence of a foreign object based on the measurement result may be performed periodically. Note that, when performing foreign object detection processing based on the measurement result of the coupling state indicator, the TX100 and the RX200 may combine the Q-factor measurement method, the power loss method, and the waveform attenuation method. The method for setting the threshold value for determination for each method is as described above.

[0335] For example, if the entity executing the foreign object detection process based on the measurement result of the coupling status index between the power transmitting antenna and the power receiving antenna is the TX100, the TX100 executes the foreign object detection process based on the measurement result of the coupling status index between the power transmitting antenna and the power receiving antenna and obtains a determination result. The determination result may be "highly likely to have a foreign object," "foreign object present," "lowly likely to have a foreign object," or "no foreign object," and the TX100 notifies the RX200 of the determination result. If the determination result is "highly likely to have a foreign object" or "foreign object present," the RX200 transmits a packet to the TX100 requesting the execution of a predetermined foreign object detection process. Alternatively, if the determination result is "highly likely to have a foreign object" or "foreign object present," the TX100 may transmit a packet to the RX200 requesting the TX100 to transmit a packet requesting the RX200 to transmit a packet requesting the execution of a predetermined foreign object detection process. Upon receiving the packet, the RX200 transmits a packet to the TX100 requesting the execution of a predetermined foreign object detection process. The predetermined foreign object detection process may be all or one or more of the foreign object detection processes based on the Q-factor measurement method, the Power Loss method, and the waveform attenuation method. In response to a request from the RX 200, the TX 100 executes the predetermined foreign object detection process and notifies the RX 200 of the determination result. If the determination result is "high possibility of the presence of a foreign object" or "foreign object present," the RX 200 transmits a packet to the TX 100 requesting that power transmission be limited. For example, the packet may be a packet requesting that the GP value be set to a low value, or an RP1 or RP2 packet requesting a re-execution of the Power Loss method CAL process. Alternatively, the packet may be a packet requesting a re-execution of the waveform attenuation method or the coupling status indicator measurement method CAL process. Alternatively, the packet may be an EPT packet requesting the suspension of power transmission.

[0336] The RX 100 then executes the predetermined foreign object detection process described above, and notifies the RX 200 of the determination result. If the determination result is "highly likely that a foreign object exists" or "foreign object exists," the RX 200 transmits a packet to the TX 100 requesting that the TX 100 execute foreign object detection processing based on the coupling state between the power transmitting antenna and the power receiving antenna. Upon receiving the packet, the TX 100 executes foreign object detection processing based on the coupling state between the power transmitting antenna and the power receiving antenna, and notifies the RX 200 of the determination result. If the determination result is "highly likely that a foreign object exists" or "foreign object exists," the RX 200 transmits a packet to the TX 100 requesting that power transmission be limited. For example, the packet may be a packet requesting that the GP value be set to a low value, or RP1 or RP2 requesting re-execution of CAL processing using the Power Loss method. Alternatively, the packet may be a packet requesting re-execution of CAL processing using the waveform attenuation method. Alternatively, the packet may be an EPT packet requesting that power transmission be stopped.

[0337] Alternatively, if the RX200 is the entity that executes the foreign object detection process based on the measurement results of the coupling state index between the power transmitting antenna and the power receiving antenna, the RX200 executes the foreign object detection process and obtains a determination result. The determination result may be "high possibility of foreign object presence," "foreign object present," "low possibility of foreign object presence," or "no foreign object," and the RX200 notifies the TX100 of the determination result. If the determination result is "high possibility of foreign object presence" or "foreign object present," the RX200 transmits a packet to the TX100 requesting execution of a predetermined foreign object detection process. The predetermined foreign object detection process may be all or one or more of foreign object detection processes based on the Q-factor measurement method, the power loss method, and the waveform attenuation method. The TX100 executes the predetermined foreign object detection process in accordance with the request from the RX200 and notifies the RX200 of the determination result. If the determination result is "high possibility of the presence of a foreign object" or "foreign object is present," the RX 200 transmits a packet to the TX 100 requesting that power transmission be limited. For example, the packet is a packet requesting that the GP value be set to a low value, or an RP1 or RP2 requesting that the CAL process of the Power Loss method be performed again. Alternatively, the packet is a packet requesting that the CAL process of the waveform decay method or the coupling status indicator measurement method be performed again. Alternatively, the packet is an EPT packet requesting that power transmission be stopped.

[0338] The RX 200 then executes the predetermined foreign object detection process described above, and notifies the RX 200 of the determination result. If the determination result is "highly likely that a foreign object exists" or "foreign object exists," the RX 200 transmits a packet to the TX 100 notifying the TX 100 that it will execute foreign object detection processing based on the coupling state between the power transmitting antenna and the power receiving antenna. After transmitting the packet, the RX 200 executes foreign object detection processing based on the coupling state between the power transmitting antenna and the power receiving antenna, and notifies the TX 100 of the determination result. If the determination result is "highly likely that a foreign object exists" or "foreign object exists," the RX 200 transmits a packet to the TX 100 requesting that power transmission be limited. For example, the packet may be a packet requesting that the GP value be set to a low value, or RP1 or RP2 requesting re-execution of CAL processing using the Power Loss method. Alternatively, the packet may be a packet requesting re-execution of CAL processing using the waveform attenuation method. Alternatively, the packet may be an EPT packet requesting the suspension of power transmission.

[0339] In the above example, the TX100 or RX200 performs a foreign object detection process based on the measurement result of the coupling status indicator between the transmitting antenna and the receiving antenna, and a predetermined foreign object detection process at different times. The TX100 or RX200 may perform a foreign object detection process based on the measurement result of the coupling status indicator between the transmitting antenna and the receiving antenna, and one or more of the predetermined foreign object detection processes, at the same time. If the RX200 specifies the timing, the RX200 notifies the TX100 of the timing by transmitting a predetermined packet. If the TX100 specifies the timing, the TX100 notifies the RX200 of the timing by transmitting a predetermined packet. For example, upon receiving the predetermined packet, the TX100 or RX200 performs a foreign object detection process based on the measurement result of the coupling status indicator between the transmitting antenna and the receiving antenna, and a foreign object detection process using the Power Loss method. Alternatively, upon receiving the specified packet, the TX100 or RX200 executes foreign object detection processing based on the measurement result of the coupling state index between the power transmitting antenna and the power receiving antenna, and foreign object detection processing using the waveform attenuation method. Alternatively, upon receiving the specified packet, the TX100 or RX200 executes foreign object detection processing based on the measurement result of the coupling state index between the power transmitting antenna and the power receiving antenna, foreign object detection processing using the power loss method, and foreign object detection processing using the waveform attenuation method.

[0340] Alternatively, the TX100 or the RX200 may perform one or more of the predetermined foreign object detection processes at the same time. If the timing is specified by the RX200, the RX200 notifies the TX100 of the timing by transmitting a predetermined packet. If the timing is specified by the TX100, the TX100 notifies the RX200 of the timing by transmitting a predetermined packet. For example, upon receiving the predetermined packet, the TX100 or the RX200 performs foreign object detection processing using the waveform attenuation method. Alternatively, upon receiving the predetermined packet, the TX100 or the RX200 performs foreign object detection processing using the power loss method and foreign object detection processing using the waveform attenuation method.

[0341] Next, a second method for improving the accuracy of detecting a foreign object present between the TX 100 and the RX 200 will be described, which involves detecting a foreign object based on the temperature of the TX 100 or the RX 200. The TX 100 and the RX 200 each have temperature sensors at multiple locations. In particular, the temperature sensors are arranged at a higher density in the transmitting antenna 105, the charging stand 300, and the receiving antenna 205 than in other locations. This makes it possible to detect a foreign object present between the TX 100 and the RX 200 with higher accuracy.

[0342] When the TX100 or RX200 recognizes that the TX100 and RX200 are operating in rapid charge mode, the TX100 or RX200 executes foreign object detection processing based on the detected temperature. The TX100 acquires a detected value from the temperature sensor at a predetermined timing. The predetermined timing occurs at a predetermined cycle or when a predetermined packet is received from the RX200. If the detected value from the temperature sensor is greater than a predetermined threshold, the TX100 determines that a foreign object is likely to be present. The TX100 also calculates a temperature rise rate based on multiple detected temperature values ​​acquired at the predetermined timing. If the temperature rise rate is greater than the predetermined threshold, the TX100 determines that a foreign object is likely to be present. The TX100 notifies the RX200 of the determination result in a predetermined packet. Alternatively, when the determination result is acquired, the TX100 performs the control to limit the transmission power (reduce power) or stop power transmission as described above. These controls have already been described, so they will not be described here.

[0343] Next, the foreign object detection process based on the temperature of the RX 200 will be described. The RX 200 acquires a detection value from a temperature sensor at a predetermined timing. The predetermined timing occurs at a predetermined cycle or when a predetermined packet is received from the TX 100. If the detection value from the temperature sensor is greater than a predetermined threshold, the RX 200 determines that there is a high possibility that a foreign object is present. The RX 200 also calculates a temperature rise rate based on multiple temperature detection values ​​acquired at the predetermined timing. If the temperature rise rate is greater than the predetermined threshold, the RX 200 determines that there is a high possibility that a foreign object is present. The TX 100 is notified of this determination result in a predetermined packet. Alternatively, when this determination result is acquired, the RX 200 transmits a predetermined packet to the TX 100 to perform the process of limiting the transmission power (reducing power) or stopping power transmission as described above.

[0344] In this way, with the second method, when the TX100 or RX200 recognizes that the TX100 and RX200 are operating in fast charge mode, the TX100 or RX200 measures the temperature of the TX100 or RX200, and based on the measurement results, more accurate foreign object detection is possible. Note that, when performing this foreign object detection, the TX100 and RX200 may combine the Q-factor measurement method, the power loss method, and the waveform attenuation method. For example, if the TX100 is the entity that executes the temperature-based foreign object detection process, the TX100 executes the temperature-based foreign object detect...

Claims

power receiving means for receiving power from the power transmitting device via a coil; a communication means for communicating with the power transmission device via the coil when receiving power from the power transmission device, The communication means performs communication using the coil in a first communication method when receiving power at a first power level, and performs communication using the coil in a second communication method that is faster than the first communication method when receiving power at a second power level that is greater than the first power level. A power receiving device characterized by: 　 The power transmission device further includes a parameter change unit that changes a parameter of modulation of the communication based on a coupling state between a coil of the power transmission device and a coil of the power receiving device. The power receiving device according to claim 1 . 　 When the second communication method is used, the communication unit shortens a transmission interval of packets used for foreign object detection executed by the power transmitting device compared to when the first communication method is used.

3. The power receiving device according to claim 1 or 2. 　 The packet used in the foreign object detection is a Received Power Data packet in the Wireless Power Consortium standard. The power receiving device according to claim 3 . 　 When the second communication method is used, the communication unit transmits, at predetermined intervals, a packet requesting information indicating a state of the power transmitting device, which is used in state detection of the power transmitting device and the power receiving device, executed by the power transmitting device. The power receiving device according to any one of claims 1 to 4. 　 The communication means receives information indicating an electrical state of an inverter of the power transmission device from the power transmission device in response to transmission of a packet requesting information indicating a state of the power transmission device. The power receiving device according to claim 5 . 　 When the second communication method is used, the communication means shortens a transmission interval of a packet in which the power receiving device requests the power transmitting device to control transmission power compared to when the first communication method is used. The power receiving device according to any one of claims 1 to 6. 　 The packet requesting control of the transmission power is a Control Error Data Packet in the WPC (Wireless Power Consortium) standard. The power receiving device according to claim 7 . 　 The first power is a power specified in the Baseline Power Profile or the Extended Power Profile in the Wireless Power Consortium standard. The power receiving device according to any one of claims 1 to 8. 　 the first communication method uses load modulation that performs modulation of a first number of quantization bits, The second communication method uses load modulation for modulating a second quantization bit rate that is greater than the first quantization bit rate. The power receiving device according to any one of claims 1 to 9. 　 the first communication method performs load modulation using a load of a first value; The second communication method performs load modulation using a load of a second value smaller than the first value. The power receiving device according to any one of claims 1 to 9. 　 The communication means communicates using a third communication method different from the second communication method and communicating at a higher speed than the first communication method, depending on a control index indicating at least one of a state of the power transmitting device, a state of the power receiving device, and a state of foreign object detection. The power receiving device according to any one of claims 1 to 11. 　 The communication means communicates at a higher speed than the first communication method according to information related to power communicated between the power transmitting device and the power receiving device, using a third communication method different from the second communication method. The power receiving device according to any one of claims 1 to 12. 　 a power receiving step of receiving power from a power transmitting device via a coil; a communication step of communicating with the power transmission device via the coil when receiving power from the power transmission device, In the communication step, communication is performed using the coil in a first communication method when receiving power at a first power, and communication is performed using the coil in a second communication method faster than the first communication method when receiving power at a second power higher than the first power. A method performed by a power receiving device. 　 a power transmitting means for transmitting power to a power receiving device via a coil; a communication means for communicating with the power receiving device via the coil when transmitting power to the power receiving device, The communication means communicates using the coil in a first communication method when transmitting power at a first power, and communicates using the coil in a second communication method that communicates at a higher speed than the first communication method when transmitting power at a second power that is higher than the first power. A power transmission device characterized by: 　 a power transmitting step of transmitting power to a power receiving device via a coil; a communication step of communicating with the power receiving device via the coil when transmitting power to the power receiving device, In the communication step, communication is performed using the coil in a first communication method when transmitting power at a first power, and communication is performed using the coil in a second communication method that communicates at a higher speed than the first communication method when transmitting power at a second power that is higher than the first power. A method performed by a power transmission device. 　 A program causing a computer to execute the steps according to claim 14 or 16.

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