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

Abstract

To provide a technology that improves communication performance between a power transmitting device and a power receiving device.SOLUTION: The power receiving device receives power from a power transmitting device via a coil and communicates with the power transmitting device via the coil during power reception from the power transmitting device. Furthermore, the power receiving device communicates using a first communication method via the coil when receiving power at a first power level, and communicates using a second communication method (F3408), which is faster than the first communication method via the coil when receiving power at a second power level, which is greater than the first power level.SELECTED DRAWING: Figure 34

Description

[Technical Field]

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

[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 discloses control for rapid wireless charging. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2018-108014 Summary of the Invention [Problem to be solved by the invention]

[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. [Means for solving the problem]

[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. [Effects of the Invention]

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

[0008] [Figure 1] FIG. 1 is a diagram illustrating a configuration example of a wireless power transmission system. [Figure 2] FIG. 2 is a diagram illustrating an example of the configuration of a power transmission device. [Figure 3] FIG. 2 illustrates an example of the configuration of a power receiving device. [Figure 4] FIG. 10 is an explanatory diagram of a threshold setting method for state detection using the Power Loss method. [Figure 5] FIG. 1 is an explanatory diagram of a Q-value measurement method. [Figure 6] FIG. 2 is a block diagram illustrating an example of a functional configuration of a control unit of the power transmitting device. [Figure 7] 10 is a flowchart illustrating processing of the power transmitting device. [Figure 8] 10 is a flowchart illustrating processing of a power receiving device. [Figure 9] FIG. 10 is an explanatory diagram of state detection using a waveform decay method. [Figure 10] FIG. 10 is a diagram illustrating an example of a process for wireless power transmission. [Figure 11] FIG. 10 is an explanatory diagram of a threshold setting method for state detection using the waveform decay method. [Figure 12] 1 is an explanatory diagram of a method for measuring a coupling state indicator between a power transmitting antenna and a power receiving antenna; [Figure 13] FIG. 10 is an explanatory diagram of a threshold setting method for detecting a state by a combined state index measurement method. [Figure 14] 4 is a flowchart illustrating processing of the power transmitting device according to the first embodiment. [Figure 15] 5 is a flowchart illustrating processing of the power receiving device according to the first embodiment. [Figure 16] FIG. 4 is a sequence diagram illustrating processing by the power transmitting device and the power receiving device according to the first embodiment. [Figure 17]10 is a flowchart illustrating processing of a power transmitting device according to a third embodiment. [Figure 18] 10 is a flowchart illustrating processing of a power receiving device according to a third embodiment. [Figure 19] FIG. 11 is a sequence diagram illustrating processing by a power transmitting device and a power receiving device according to the third embodiment. [Figure 20] 10 is a flowchart illustrating processing of a power transmitting device according to a fourth embodiment. [Figure 21] 10 is a flowchart illustrating processing of a power receiving device according to a fourth embodiment. [Figure 22] FIG. 11 is a sequence diagram illustrating processing by a power transmitting device and a power receiving device according to the fourth embodiment. [Figure 23] 10 is a table illustrating processing by a power transmitting device and a power receiving device according to the fourth embodiment. [Figure 24] 10 is a table illustrating processing by a power transmitting device and a power receiving device according to the fourth embodiment. [Figure 25] 10 is a table illustrating processing by a power transmitting device and a power receiving device according to the fourth embodiment. [Figure 26] 13 is a flowchart illustrating processing of a power transmitting device according to a sixth embodiment. [Figure 27] 13 is a flowchart illustrating processing of a power receiving device according to a sixth embodiment. [Figure 28] FIG. 13 is a sequence diagram illustrating processing by a power transmitting device and a power receiving device according to the sixth embodiment. [Figure 29] 13 is a table illustrating processing by a power transmitting device and a power receiving device according to the fifth embodiment. [Figure 30] 13 is a table illustrating processing by a power transmitting device and a power receiving device according to the sixth embodiment. [Figure 31] 13 is a table illustrating processing by a power transmitting device and a power receiving device according to the seventh embodiment. [Figure 32] 13 is a table illustrating processing by a power transmitting device and a power receiving device according to the seventh embodiment. [Figure 33] 4 is a flowchart illustrating processing of the power transmitting device according to the first embodiment. [Figure 34] 5 is a flowchart illustrating processing of the power receiving device according to the first embodiment. [Figure 35] FIG. 4 is a sequence diagram illustrating processing by the power transmitting device and the power receiving device according to the first embodiment. DETAILED DESCRIPTION OF THE INVENTION

[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] The present 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. The 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 RX200, and the power transmitting device 100 may be referred to as TX100. The detailed configurations of the TX100 and RX200 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 transmits power wirelessly 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 to execute 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, a configuration example of the power transmitting device 100 will be described with reference to Fig. 2. Fig. 2 is a functional block diagram showing a configuration example of the power transmitting device 100. The TX 100 has 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 ASIC (Application Specific Integrated Circuit). The control unit 101 may also be configured with an array circuit, such as an FPGA (Field Programmable Gate Array), compiled to execute predetermined processes. The control unit 101 can store information to be stored during the execution of various processes in the memory 106 and can perform timekeeping 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, thereby generating electromagnetic waves for receiving power at the RX200. 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 multiple FETs (Field Effect Transistors) that form a bridge, and a gate driver that controls the ON / OFF of the multiple 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. 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 strength 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] In the power transmitting unit 103, output control of the power of the AC frequency electromagnetic waves is performed so as to start or stop power transmission by the power transmitting antenna 105 or to control the intensity of the electromagnetic waves to be output based on an instruction signal from the control unit 101. Also, the power transmitting unit 103 is 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 performs communication with the RX200 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 RX200 to perform communication. The first communication unit 104 also demodulates the electromagnetic waves modulated by the RX200 and transmitted from the power transmitting antenna 105, and acquires the information transmitted by the RX200. 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 that communicates with the power receiving device via the 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] The memory 106 can store information about the states of the TX100 and RX200 in addition to the control program. Information about the states of the TX100 and RX200 includes transmitted power values, received power values, etc. Information about the state of the TX100 is acquired by the control unit 101. Information about the state of the RX200 is acquired by the control unit of the RX200 and can be received by the first communication unit 104 or the second communication unit 109, which will be 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 sends 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 to the ON state and short-circuits it, the power transmitting antenna 105 and the resonant capacitor 107 form a series resonant circuit and resonate 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 to the OFF state 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 RX200 using a standard different from the WPC standard. For example, the second communication unit 109 communicates with the RX200 using an antenna (not shown) different from the power transmitting antenna 105. The second communication unit 109 may use any communication method such as a wireless LAN (Local Area Network), Bluetooth (registered trademark) Low Energy (BLE), or 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-of-band communication.

[0024] Regarding communication between the TX100 and the RX200, the TX100 may selectively use one of a number of communication standards to communicate with the RX200. The following communication formats are possible, each of which selectively uses one of the following communication formats: Communication based on the first standard (WPC standard) is performed 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) that is performed 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, an example configuration of the power receiving device 200 will be described with reference to Fig. 3. Fig. 3 is a block diagram showing an example configuration of the power receiving device 200. The RX200 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 RX200 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 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 it. Alternatively, the control unit 201 may be configured with hardware such as an ASIC, or may include an array circuit such as an FPGA compiled to execute predetermined processes. The control unit 201 stores information to be stored during the execution of various processes in the memory 208, and can also perform timing processing 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, speaker, vibration motor, etc.

[0029] The power receiving unit 203 receives, via a 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 TX100. The power receiving unit 203 then converts the AC power into DC or AC power of a predetermined frequency and supplies the power to a charging unit 206. The charging unit 206 charges a battery 207. The power receiving unit 203 includes a rectifier (rectifier, rectifier circuit) and a voltage control unit required for supplying power to a load in the RX200. 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. Also, 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 that allows operation of control unit 201, charging unit 206, etc. 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 TX100 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 the electromagnetic waves input from the power receiving antenna 205 to acquire information transmitted from the TX100. The first communication unit 204 performs load modulation, amplitude modulation, or backscattering modulation on the input electromagnetic waves, and superimposes a signal related to information to be transmitted to the TX100 on the electromagnetic waves, thereby communicating with the TX100. The first communication unit 204 is an example of a communication means that communicates with the power transmitting device via the 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 TX100 and RX200. Information about the state of the RX200 is acquired by the control unit 201. Information about the state of the TX100 is acquired by the control unit 101 of the TX100, and can be received by the first communication unit 204 or the second communication unit 212 described below.

[0032] The second communication unit 212 is connected to the control unit 201, and communicates with the TX100 using a standard different from the WPC standard. For example, the second communication unit 212 communicates with the TX100 using an antenna different from the power receiving antenna 205. Examples of communication methods used by the second communication unit 212 include 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 number of communication standards to communicate with the TX100. The following communication formats are possible, each of which selectively uses one of the following communication formats: Communication based on the first standard (WPC standard) is performed between the first communication unit 104 of the TX 100 and the first communication unit 204 of the RX 200. Communication based on a second standard (a standard other than the WPC standard) that is carried out 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 section 209 may be disposed between the power receiving section 203 and a closed circuit formed by the power receiving antenna 205, the resonant capacitor 211, and the second switch section 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 illustrated as one 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 to open the circuit, 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 to short-circuit the circuit, 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, creating a 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 and opens 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 this 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. The third switch unit 213 may also be disposed between the resonant capacitor 211 and the power receiving unit 203.

[0040] In this system, the TX100 and the RX200 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 RX200 and the TX100 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 RX200 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 RX200 and the TX100, resulting in a decrease in power transmission efficiency. The load of the RX200 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 consider a case where the GP value is 5 (watts) and the positional relationship between the power receiving antenna 205 and the power transmitting antenna 105 changes. In this case, even if the power transmission efficiency decreases, the TX100 performs power transmission control so as to be able to output 5 watts to the load of the RX200. The GP is determined by negotiation between the TX100 and the RX200. Note that this embodiment is not limited to the GP, and can be applied to a configuration in which power is transmitted and received at a power determined by mutual negotiation between the TX100 and the RX200.

[0041] Also, assume that an object is present near the TX100 when transmitting power from the TX100 to the RX200. In this case, the object is an object (foreign object) that may affect the power transmission from the TX100 to the RX200 but is different from the RX200. The electromagnetic waves used for power transmission may affect the foreign object, causing it 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, but 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 TX100 and the received power in the RX200. 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-factor) of the power transmitting antenna 105 (power transmitting coil) in the TX100. 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-factor) of a resonant circuit including the power transmitting antenna 105 and the resonant capacitor 107 in the TX100. In this 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 of the power transmitting antenna 105. However, the foreign objects that the TX100 detects are not limited to objects present on the charging stand 300. The TX100 can detect foreign objects located near the TX100. For example, the TX100 can detect foreign objects located within a range where power can be transmitted.

[0043] With reference 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 TX100, and the vertical axis represents the received power of the RX200. On the graph line indicated by 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 TX100 transmits power to the RX200 at a first transmission power value Pt1, and the RX200 receives power at a first reception power value Pr1. Hereinafter, this state is referred to as a light load state. The TX100 stores the first transmission power value Pt1. At this time, the RX200 performs load control so that the received power is minimized. Alternatively, the RX200 performs load control so that the received power is within a predetermined range or is equal to or less than a predetermined threshold. 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 (described later). Furthermore, the RX200 may disconnect the load from the power receiving antenna 205 so that the received power is not supplied to the load (such as the charging unit 206 or battery 207 in FIG. 3). Alternatively, the RX200 may control the load so that a predetermined power is supplied to the load. These 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, which has 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 TX100 changes the transmission power value to the second transmission power value Pt2 and transmits power to the RX200, and the RX200 receives power at the second received power value Pr2. Hereinafter, this state is referred to as the Connected Load state. The TX100 stores the second transmission power value Pt2. At this time, the RX200 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 RX200 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 RX200 connects the receiving antenna 205 to the load so that the received 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 second received power value Pr2. The TX100, which has received a signal relating to the second received power value Pr2 from the RX200, calculates the power loss between the TX100 and the RX200. The power loss at this time is Pt2-Pr2 (=Ploss2). A CP1001 indicating the correspondence between Pt2 and Pr2 can be generated.

[0046] The TX100 performs linear interpolation between CP1000 and CP1001 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 TX100 and the RX200 (hereinafter referred to as the first detection state). Based on the line segment 1002, the TX100 can estimate the power value that the RX200 will receive when transmitting power at a predetermined transmitted power in the first detection state. For example, assume that the TX100 transmits power at a third transmitted power value Pt3. In this case, the TX100 can estimate the third received power value Pr3 that the RX200 will receive from a point 1003 on the line segment 1002 that corresponds to Pt3.

[0047] As described above, the power loss between the TX100 and RX200 corresponding to the load can be calculated based on multiple combinations of the TX100's transmission power value and the RX200's reception power value measured while changing the load. Furthermore, by performing interpolation processing on multiple combinations of the transmission power value and reception power value, the power loss between the TX100 and RX200 corresponding to all loads can be estimated. The calibration processing performed by the TX100 and RX200 in this way to obtain combinations of the transmission power value and reception power value of the TX100 is called "calibration processing using the power loss method." The calibration processing is abbreviated as "CAL processing." Performing calibration processing again after a calibration processing has been performed once to update or add calibration points is called recalibration processing, abbreviated as "ReCAL processing."

[0048] Assume that after the CAL process using the Power Loss method, the TX100 actually transmits power to the RX200 at the third transmission power value Pt3, and the TX100 receives a signal related to the received power value Pr3* from the RX200. 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) is referred to as RP0. RP0 includes the value of the received power value Pr3*. The TX100 calculates Pr3-Pr3* (=Ploss_FO) by subtracting the received power value Pr3* actually received from the RX200 from the received power value Pr3 in the first detection state. If a foreign object is present near the TX100 and RX200, 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 TX100 and RX200 is detected will be 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 be 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 obtains the third received power value Pr3 in the first detection state from the RX200 and calculates the power loss Pt3-Pr3 (=Ploss3) between the TX100 and the RX200 in advance.

[0050] Next, the TX100 acquires the received power value Pr3* from the RX200 in the second detection state, and calculates the power loss Pt3-Pr3* (=Ploss3*) between the TX100 and the RX200 in the second detection state. The TX100 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. ·The first method calculates Ploss_FO from Pr3-Pr3*. ·Ploss3* - The second method for calculating Ploss_FO from 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) using the Q-factor measurement method. An AC power supply 901 is a power supply that outputs AC power generated by the power transmitting unit 103 of the TX100. A power transmitting antenna 902 corresponds to the power transmitting antenna 105, and a capacitor 903 corresponds to the resonant capacitor 107. The power transmitting antenna 902 and the capacitor 903 are connected in series. A 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. A voltage value V9 is a voltage value applied to the power transmitting antenna 902. Here, it is assumed that the TX100 is capable of changing the frequency related to the voltage value. The voltage values ​​V8 and V9 are voltage values ​​measured by the TX100 when the TX100 transmits an Analog Ping (hereinafter referred to as "AP") or a Digital Ping (hereinafter referred to as "DP") to the RX200. Note that since the voltage values ​​V8 and V9 are AC voltage values, their effective values ​​(RMS) may also be used.

[0054] FIG. 5(B) shows an example of measurement results of V9 / V8 versus frequency, showing characteristics with a peak at 100 kHz. The horizontal axis is the frequency axis, and the vertical axis represents the voltage ratio "V9 / V8." V9 / V8 represents the quality factor related to the power transmitting antenna 902, so 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 TX100, whether the RX200 is placed on the TX100, whether a foreign object (such as a piece of metal) is placed on the TX100, or whether the RX200 and a foreign object are placed on the TX100.

[0055] The TX100 receives an FOD Status Data packet signal from the RX200 during the Negotiation phase (described later) specified in the WPC standard. The FOD Status Data packet includes a Reference Quality Factor Value and a Reference Resonance Frequency Value. The Reference Quality Factor Value is the Quality Factor 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 objects are present nearby. The Reference Resonance Frequency Value is as follows: 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 objects are 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 calculated from the actually measured V9 / V8. Alternatively, the threshold is set based on the Reference Resonance Frequency Value. Foreign objects are detected by comparing this threshold value with the resonance frequency obtained 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. In each phase, communication for the necessary power transmission and reception control is performed. 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-value measurement method is performed before power transmission (before sending a digital ping and in the negotiation or renegotiation phase).

[0057] The WPC standard specifies the phases before power transmission: Selection phase, Ping phase, and Configuration phase. Additionally, there are Negotiation phase and Calibration phase. The processing in each phase is explained below.

[0058] In the Selection phase, the TX100 intermittently transmits Analog Pings to detect that an object has been placed on the TX100's charging base. Analog Pings are short-duration power signals applied to detect the presence of an object. However, these power signals do not activate the control unit of the power receiving device. For example, they detect that the RX200 or a conductor piece has been placed on the charging base. The TX100 detects one or both of the voltage and current values ​​of the power transmitting antenna 105 when the Analog Ping is transmitted. 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 meets a predetermined condition or if the Quality Factor calculated from the current value meets a predetermined condition, the TX100 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 higher power than the Analog Ping. The Digital Ping is a power signal used to activate 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 of the power transmitting antenna 105, for example, using an Analog Ping. This measurement result is used when performing foreign object detection processing using the Q-factor measurement method. Note that 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 also be called the Ping phase.

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

[0061] In the Negotiation phase, the GP value is determined based on the GP value requested by the RX200 and the power transmission capability of the TX100. The TX100 also receives an FOD Status Data packet from the RX200, which includes the Reference Quality Factor Value and Reference Resonance Frequency Value. The Q-factor measurement method determines whether or not a foreign object is present based on thresholds based on the Reference Quality Factor Value and Reference Resonance Frequency Value. The TX100 performs foreign object detection processing using the Q-factor measurement method in response to a request from the RX200. The WPC standard also stipulates a method in which, after transitioning to the Power Transfer phase, processing similar to that of the Negotiation phase is performed again at the request of the RX200. The phase in which these processing operations are performed after transitioning from the Power Transfer phase is called the 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 RX200 notifies the TX100 of a predetermined received power value, and the TX100 performs 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 TX100 is used for foreign object detection processing using the power loss method.

[0063] In the power transfer phase, the TX100 and RX200 perform control such as starting and continuing power transmission, error processing, and stopping power transmission due to a full charge. The TX100 and RX200 perform communication processing for this power transmission and reception control. For example, using the power transmitting antenna 105 and power receiving antenna 205 used when performing wireless power transmission based on the WPC standard, communication is performed by superimposing a signal on the electromagnetic waves transmitted from the power transmitting antenna 105 or power receiving antenna 205. Note that the range in which communication based on the WPC standard between the TX100 and 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 TX100 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 (TX100). 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 RX200 based on the WPC standard via the first communication unit 104, or controls communication with the RX200 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 RX200. 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 RX200 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 TX100. 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-mentioned 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 positional deviation between the TX100 and the RX200 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 positional deviation between the TX100 and the RX200 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 TX100 and the RX200. For example, the status detection unit 305 detects foreign objects present between the TX100 and the RX200, and also detects 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 TX100, 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 misalignment between the power transmitting antenna 105 and the power receiving antenna 205 using other methods. For example, in a TX100 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. In addition to detecting the presence or absence of foreign objects and the electromagnetic coupling state between the power transmitting antenna and the power receiving antenna, the status detection unit 305 can also detect status changes on the TX100. For example, the state detection unit 305 can detect an increase or decrease in the number of RX200 on the TX100.

[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 TX100 performs status detection. Status detection may be, for example, status detection based on the power loss method, Q-factor measurement method, or waveform attenuation method, status detection based on the temperature measured by the TX100, 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 also 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, transmitted power, a quality factor, the temperature measured by the TX100, and the coupling coefficient between the power transmitting antenna 105 and the power receiving antenna 205 as the measurement results of 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 TX100 and the RX200 will be described. Fig. 7 is a flowchart showing an example of power transmission control processing executed by the TX100. This processing is realized, for example, by the control unit 101 of the TX100 executing a program read from the memory 106. This processing can also be executed when the power of the TX100 is turned on, when the user of the TX100 inputs an instruction to start a wireless power transmission application, or when the TX100 is connected to a commercial power source and receives power. This processing may also be started by some other trigger.

[0071] In S1201 of Figure 7, the TX100 executes the processes defined as the Selection phase and Ping phase of the WPC standard, and waits for the RX200 to be placed. Specifically, the TX100 repeatedly and intermittently transmits Analog Pings according to the WPC standard to detect objects present within the power transmission range. For example, the TX100 can detect that the RX200 or a piece of conductor has been placed on the charging stand 300. If the TX100 detects the presence of an object within the power transmission range, it transmits a Digital Ping.

[0072] When there is a predetermined response to the Digital Ping, 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, or 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] Furthermore, 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 detecting that the RX200 has been placed, in S1202 the TX100 acquires identification information from the RX200 through communication in the configuration phase defined by the WPC standard. In the configuration phase, the RX200 transmits an Identification Data Packet (ID Packet) to the TX100. The ID Packet contains the Manufacturer Code and Basic Device ID, which are identification information for each individual RX200, 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 contains the following capability information of the RX200: Maximum Power Value or Reference Power, which is the value that specifies the maximum power that the RX200 can supply to the load. Information indicating whether the RX200 has the WPC standard negotiation function Parameters used in frequency shift keying, a communication modulation method used when TX100 transmits information to RX200 -Information indicating whether the RX200 supports out-of-band communication functions

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

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

[0078] In addition, the TX100 performs foreign object detection processing using the Q-value measurement method in response to a request from the RX200. The TX100 receives an FOD Status Data packet from the RX200. This packet includes the Reference Quality Factor Value and Reference Resonance Frequency Value described above. The TX100 then performs foreign object detection using the Q-value measurement method. This foreign object detection is performed based on the following information: The quality factor and resonant frequency of the transmitting antenna 105 measured by the TX100 before sending the Digital Ping Threshold based on the Reference Quality Factor Value and Reference Resonance Frequency Value received by the TX100 from the RX200

[0079] Next, in S1204, the TX100 and RX200 perform processing of the calibration phase (CAL processing) 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 assumed to be 500 milliwatts. The first reference received power information is information included in the Received Power Data packet (mode 1) defined in the WPC standard, but other messages may also 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 included 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 RX200 performs processing to transmit to the TX100 a signal containing information about 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 RX200 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 RX200 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 set to 15 watts. The second reference received power information is information included in a 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. The TX100 determines whether or not to accept the second reference received power information based on the Control Error Value included in the Control Error (CE) data packet received from the RX200. If the TX100 accepts the second reference received power information, it transmits an acknowledgement ACK to the RX200. If the TX100 does not accept the second reference received power information, it transmits a negative acknowledgement NAK to the RX200. The TX100 transmits an acknowledgement ACK in response to the second reference received power information from the RX200, and completes the CAL process.

[0082] The above CAL processing 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 value 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 the range in which the received power of the RX200 receives power from 500 milliwatts to 15 watts in this embodiment.

[0083] After that, in S1205, the TX100 transmits power until the battery 207 of the RX200 is fully charged. In S1205, communication in the Power Transfer phase of the WPC standard is performed. The RX200 repeatedly transmits Control Error Data Packets (hereinafter referred to as "CE packets") to the TX100 at time intervals of t_interval. t_interval is a value defined in the WPC standard, and is, for example, 250 milliseconds. The CE packet contains a request for how much to increase or decrease the transmission power. The TX100 adjusts the transmission power by controlling the current or voltage of the power transmitting antenna 105 based on the received CE packet. In other words, the CE packet contains parameter data for adjusting the transmission power. By repeating this process, power is transmitted at an appropriate power level according to the request of the RX200 in almost real time.

[0084] When the battery 207 is fully charged, the RX200 transmits an End Power Transfer data packet (hereinafter referred to as an "EPT packet") to end the power transfer phase. The RX200 can transmit an EPT packet for reasons other than full charge. Furthermore, when the power transfer phase ends, the TX100 stops transmitting power to the RX200 for charging.

[0085] Furthermore, if the TX100 fails to receive the next CE packet after the t_timeout time has elapsed since the last CE packet was received, it determines that the RX200 has been removed from the charging base 300. In this case, it ends the Power Transfer phase. t_timeout is a value defined in the WPC standard, and is, for example, 1500 milliseconds.

[0086] The RX200 may transmit packets other than CE packets to the TX100 during the power transfer phase. For example, there is a Charge Status Data Packet that notifies the TX100 of the status of the battery 207 of the RX200. This packet stores a Charge Status Value that indicates the percentage of charge of the battery 207. When the TX100 receives the Charge Status Data Packet, it notifies the user of the charging status by, for example, displaying text or graphics based on the Charge Status Value using the UI unit 110. The TX100 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 TX100 transmits power to the RX200 and performs foreign object detection processing using the power loss method. For example, the amount of power loss between the TX100 and RX200 in the first detection state during power transmission processing is calculated from the difference between the transmitted power value and the received power value using calibration processing. The calculated amount of power loss corresponds to the reference amount of power loss in a state where no foreign object is present. If the TX100 determines that the difference between the amount of power loss between the TX100 and RX200 measured during power transmission after calibration 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 RX200 will be described with reference to Figure 8. This processing is realized, for example, by the control unit 201 of the RX200 executing a program read from the memory 208. In S1301, the RX200 executes processing defined as the Selection phase and Ping phase of the WPC standard, and waits for its own device to be mounted on the TX100. The RX200 detects that it has been mounted on the TX100, for example, by detecting a Digital Ping from the TX100.

[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. Note that the RX200 identification information may be transmitted by a method other than the WPC standard configuration phase communication. 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 RX200 transmits a signal containing information about the power value it requests to the TX100, and negotiates with the TX100 to determine the GP. In S1303, communication in the negotiation phase of the WPC standard is performed. The RX200 transmits an FOD Status Data packet to the TX100. This packet contains a Reference Quality Factor Value and a Reference Resonance Frequency Value.

[0091] Next, in S1304, the RX200 and 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. Then, 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 TX100 perform foreign object detection processing using the power loss method. In S1305, the RX200 repeatedly transmits CE packets at intervals of t_interval, and finally transmits an EPT packet to the TX100, ending the processing.

[0092] As described above, the power loss method is a method for detecting foreign objects based on the results of measuring the amount of power loss while transmitting power from the TX 100 to the RX 200. While this method has the disadvantage that the accuracy of foreign object detection decreases when the TX 100 is transmitting a large amount of power, it has the advantage of being able to maintain high power transmission efficiency 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 foreign object detection or an erroneous determination that a foreign object is not present even though it is present. For example, consider a case where a foreign object is present near the TX100 and RX200 during power transmission during the power transfer phase. In this case, the foreign object may generate significant heat, 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 TX100 to detect foreign objects based on the attenuation state (envelope) of the power transmission waveform (voltage waveform or current waveform) related to power transmission to the RX200. In other words, foreign object detection is possible without using a newly defined foreign object detection signal, etc.

[0094] FIG. 9 illustrates the principle of foreign object detection using the waveform attenuation method. This figure shows an example of foreign object detection using a transmission waveform for power transmission from the power transmitting device 100 to the power receiving device 200. In FIG. 9, the horizontal axis represents time, and the vertical axis represents voltage or current. A waveform 600 shown in FIG. 9 shows, for example, the change over time in the voltage value of a high-frequency voltage applied to the power transmitting antenna 105 of the TX100. The TX100, which is transmitting power to the RX200 via the power transmitting antenna 105, stops transmitting power at time T0. At time T0, the power supply from the power supply unit 102 for power transmission 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 power transmitting antenna 105 can be calculated based on the time change in the voltage value after time T0. For example, the TX100 calculates the quality factor using Equation 1 based on the time and voltage value 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 the natural logarithm function.

[0096] Note that the frequency (f1) of the transmitting wave when the TX100 is transmitting power to the RX200 may differ from the frequency (f2) of the transmitting wave when the TX100 stops transmitting power to the RX200.

[0097] The quality factor value decreases when a foreign object is present near the TX100 and RX200. 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 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 that represents the attenuation state. For example, when using the quality factor for determination, a quality factor value that is lower than the reference value means that the waveform attenuation rate (the degree to which the waveform amplitude decreases per unit time) is high.

[0098] As another example, the determination can be made using the slope of the line connecting points 601 and 602, calculated as (A1-A2) / (T2-T1). If the times (T1 and T2) at which the voltage attenuation state is measured are fixed, the difference (A1-A2) in the voltage values ​​or the ratio (A1 / A2) of the voltage values ​​can be used to determine whether a foreign object is present. Alternatively, if the voltage value A1 immediately after power transmission is stopped is constant, the voltage value A2 after a predetermined time has elapsed can be used to determine whether a foreign object is present. Alternatively, the time (T2-T1) that elapses until the voltage value A1 reaches the predetermined voltage value A2 can be used to determine whether a foreign object is present.

[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 indexes" in this embodiment. While 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 waveform attenuation indexes such as the Quality Factor calculated from the current waveform, the slope of the attenuation of the current value, the difference between the current values, the ratio of the current values, the absolute value of the current values, or the time until the current value reaches a predetermined value.

[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 TX100 temporarily suspends power transmission. The waveform attenuation index may also be measured during a period in which the TX100 temporarily reduces the power supplied from the power supply unit 102 from a predetermined power level to a lower power level. In other words, the waveform attenuation index may 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 based on an instruction signal from the control unit 101. In the above example, the voltage value or current value is measured at two points in time during the period in which the TX100 limits power transmission. However, the voltage value or current value 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 transmitting power, 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 using amplitude modulation or load modulation). Furthermore, the TX100 controls the RX200 so that it does not communicate with the RX200 (communication using frequency shift keying). Hereinafter, this period is referred to as the communication prohibited period. However, during the communication prohibited period, the TX100 transmits power to the RX200. After the communication prohibited 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 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, the RX200 controls the TX100 so that it does not communicate with the TX100 using amplitude modulation, load modulation, or backscatter modulation. In addition, the TX100 controls the RX200 so that it does not communicate using frequency shift keying. By controlling the RX200 not to communicate during the preparation period, disturbances in the transmission wave pattern are suppressed, and the TX100 can more accurately calculate the waveform attenuation index of the transmission wave pattern (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 TX100 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 TX100 temporarily suspends power transmission or temporarily reduces the transmission power to when it resumes power transmission or starts to restore the transmission power is called the transmission power control period.

[0104] Here, "resuming power transmission" means that the TX100 increases the transmission power to a predetermined value. Alternatively, the period from when the TX100 temporarily sets the inverter input voltage input to the inverter in the power transmitting unit 103 to 0 volts or temporarily reduces it 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 TX100 temporarily sets the inverter output voltage output from the inverter in the power transmitting unit 103 to 0 volts or temporarily reduces it to when the output voltage value is restored to a predetermined value is hereinafter referred to as the transmission power control period. Also, the control by the TX100 to temporarily stop or temporarily reduce the transmission power is referred to as transmission power control. The TX100 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 RX200 controls the TX100 so that it does not communicate using amplitude modulation, load modulation, or backscatter modulation. In addition, the TX100 controls the RX200 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, allowing the TX100 to calculate the waveform attenuation index of the transmission wave waveform with higher accuracy. Foreign object detection can be performed during the transmission power control period, communication prohibition period, or power transmission period.

[0105] If no foreign object is detected after the transmission power control period has elapsed, the TX100 resumes power transmission or controls the restoration of transmission power. During the transient response period immediately after this control begins, the transmission waveform is not stable, so this period becomes a communication prohibited period. After this, the TX100 transitions to a power transmission period in which stable power transmission is performed from the TX100 to the RX200.

[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 TX100 cannot send packets to the RX200 after the TX100 receives a packet other than an execution request (packet, command) from the RX200 during the power transfer phase. The first period is a period longer than this period.

[0107] Furthermore, the RX200 is controlled so as not to communicate with the TX100 for a predetermined second period after sending an execution request (packet, command) to the TX100. The WPC standard specifies a period during which the RX200 cannot send packets to the TX100 after sending a packet other than an execution request (packet, command) to the TX100 during the power transfer phase. The second period is longer than the first 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 RX200, 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 RX200 turns off the first switch unit 209 during the preparation period. 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. This makes it possible to suppress the influence of the battery 207. Furthermore, the same effect can be achieved by switching to a light load state instead of disconnecting the first switch unit 209. Furthermore, the same effect can be achieved by the RX200 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 RX200 controlling the load so that the received power is within a predetermined range or 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 RX200 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 RX200 maintains the above-described control even during the transmission power control period. Then, at a timing after the power transmission is resumed, the above-mentioned control is released and the original state is restored.

[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 RX200 transmits a foreign object detection execution request (command) to the TX100, and the above processing is performed 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 to return to the original state. More accurate foreign object detection is possible by acquiring a waveform attenuation index based on the transmission power waveform measured with the first switch unit 209 disconnected or with the second switch unit 210 turned on and short-circuited (connected). 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 switch the first switch unit 209 ON to short-circuit it and the second switch unit 210 OFF to disconnect it, and then transition to a low power consumption mode or control the power consumption to be constant. The RX200 sends 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 sending the execution request (packet, command) to the TX100. The RX200 maintains the above control during the transmission power control period. Then, after power transmission resumes, the RX200 releases the above control and controls the system 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 will be 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 operation suspension mode. By detecting foreign objects using a waveform attenuation index based on the power transmission waveform measured with the RX200's power consumption suppressed, more accurate foreign object detection is possible.

[0111] Similarly, in the TX100, 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 TX100 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 TX100 receives a foreign object detection execution request (command) from the RX200, the control unit 101 turns on the switch unit 108 during the preparation period. This causes a state in which current flows 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 TX100.

[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 turning off 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 TX100 controls the switch to disconnect the closed loop circuit from the power transmitting unit, thereby suppressing the influence. The TX100 maintains the above-described control during the transmission power control period. Then, after power transmission is resumed, the TX100 releases the above-described control and controls to return to the original state. More accurate foreign object detection is possible by implementing the above methods alone or in combination.

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

[0115] Next, we will explain how to set a threshold value for the waveform attenuation index for detecting the status of the TX100 and RX200 and for detecting foreign objects based on the waveform attenuation method. Foreign object detection is possible by comparing the measured value of the waveform attenuation index with a predetermined threshold and determining the presence of a foreign object based on the comparison result. In the first threshold setting method, the TX100 stores a predetermined threshold value, which is a common value independent of the RX200 to which power is being transmitted. This threshold value is either a fixed value or a variable value determined by the TX100 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 stored and set as the threshold value. 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 TX100 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. If the measured Q value is smaller than the threshold, it is determined that there is a foreign object or that there is a high possibility that a foreign object is present. If the measured Q value is equal to or greater than the threshold, it is determined that there is no foreign object or that there is a low possibility that a foreign object is present.

[0116] In the second threshold setting method, the TX100 adjusts and determines the threshold based on information transmitted from the RX200. One 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 transmission antenna affect the value of the waveform attenuation index. For example, if a Q value is used as the waveform attenuation index, the Q value 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 value information for each TX100 when placed on the TX100 without any foreign object, and notifies the TX100 of this Q value information. The TX100 adjusts and determines the threshold for each RX200 based on the Q value 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 for the Q-factor measurement method. The Reference Quality Factor Value is a quality factor 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. The TX100 uses this Reference Quality Factor Value to determine the threshold value, regarding it as equivalent to "Q-factor information when the RX200 is placed on the TX100 in the absence of a foreign object." In other words, the TX100 can adjust and determine the threshold value for foreign object detection using the waveform attenuation method based on the Reference Quality Factor Value. Note that the Reference Quality Factor Value transmitted from the RX200 to the TX100 in the negotiation phase is information that is originally used for foreign object detection in the Q-factor measurement method, which measures the Q-factor in the frequency domain. However, when a Q value is used as the waveform attenuation index, although the method of deriving the Q value is different, the Q value can also be calculated from the waveform in Figure 9 using (Equation 1) using the waveform attenuation method, which measures the Q value in the time domain. Therefore, it is possible to set the Q value threshold for the waveform attenuation method based on the Reference Quality Factor Value. Note that the value of the waveform attenuation index, which takes into account a predetermined value (a value corresponding to the measurement error) for the Reference Quality Factor Value, may be set as the threshold for foreign matter determination.

[0118] In this way, the TX100 sets the Q-value threshold for the waveform attenuation method based on the information already sent from the RX200 to the TX100 during 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 TX100 measures the waveform attenuation index when no foreign object is present, and then adjusts and determines the threshold based on the measurement results. The timing for pre-measuring the waveform attenuation rate when no foreign object is present is described below. In the negotiation phase of the WPC standard, if foreign object detection using the Q-factor measurement method determines that no foreign object is present, the system proceeds to the calibration phase and power transfer phase. In other words, if the system has progressed beyond the negotiation phase, this means that the Q-factor measurement method determined that no foreign object is present. It is highly likely that the waveform attenuation index when no foreign object is present can be measured in either the negotiation phase, calibration phase, or power transfer phase. Therefore, the timing for measuring the waveform attenuation index when no foreign object is present can be any of the negotiation phase, calibration phase, and power transfer phase.

[0120] For example, assume that the waveform attenuation index is measured during the power transfer phase. The timing for measuring the waveform attenuation index when there is no foreign object is set to the beginning of the power transfer phase. The reason for this is that the longer the time that passes since the Q-factor measurement method determines that there is no foreign object, the higher the probability that a foreign object will be present near the TX100 and the RX200. The timing is specified by either 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 sending a specified packet. If the TX100 specifies the timing, the TX100 notifies the RX200 of the timing by sending a specified packet. Note that a value obtained by adding a specified value (a value corresponding to the measurement error) to the waveform attenuation index may be set as the threshold for foreign object determination.

[0121] The fourth threshold setting method is one 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. This is because the amount of heat generated and various characteristics of the TX100's electrical circuitry change depending on the transmission power of the TX100, which in turn 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, 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 TX100 in the waveform attenuation method. In Fig. 11, the horizontal axis represents the transmission power of the TX100, and the vertical axis represents the waveform attenuation index (waveform attenuation rate) of the voltage waveform or current waveform. On the graph line indicated 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 CP1100, which is a calibration point 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, or 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 CP1101, which associates the transmission power value Pt2 with the waveform attenuation index δ2. Next, the TX100 generates a line segment 1102 by linearly interpolating between CP1100 and CP1101. Line segment 1102 shows the relationship between the transmitted power in a first detection state in which no foreign object is present around TX100 and RX200 and the waveform attenuation index of the waveform observed by the transmitting antenna 105. Therefore, based on line segment 1102, TX100 can estimate the waveform attenuation index of the waveform observed by the transmitting antenna 105 for each transmitted 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. Based on the estimation result, TX100 can calculate a threshold value used to determine the presence or absence of a foreign object for each transmission power value. 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 to acquire a combination of the transmission power value and the waveform attenuation index by the TX100 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 called a recalibration process, abbreviated as 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 detection for each load (or each transmitted 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 when 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 the RP1 information specified in the WPC standard, but other messages may also be used. Furthermore, when the TX100 receives a signal containing second reference received power information from the RX200, it measures CP1101 in addition to the predetermined processing to be performed in the calibration phase. This second reference received power information is the RP2 information specified in the WPC standard, but other messages may also 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, the TX100 adjusts and sets the threshold value of the waveform attenuation index for each transmission power based on the information of the waveform attenuation index measured by the TX100 at 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 determined by the above method. If the measured Q value is smaller than the threshold, 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, it is determined that "foreign object is not present" or "there is a low possibility that a foreign object exists." In this way, the 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, and multiple threshold values ​​can be set in stages. For example, a first threshold value is set as a threshold value for determining whether or not an abnormal condition exists, a second threshold value is set as a threshold value for determining whether or not an abnormal condition exists, a third threshold value is set as a threshold value for determining whether or not an abnormal condition exists, and a fourth threshold value is 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 RX200 mounted on the TX100. In this case, if 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 TX100 performs transmission power control multiple times, measures the waveform attenuation index from the transmitted wave during multiple transmission power control periods, and performs more accurate foreign object determination based on the results of these 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 using 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, which changes 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, when 70% of the magnetic flux generated by the power transmitting antenna penetrates the power receiving antenna, it is "k = 0.7." 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 between the transmitting antenna and the receiving antenna is good and the k value is large, the transmission efficiency of power transmitted from the TX100 to the RX200 is high. Conversely, when the coupling is poor and the k value is small, the transmission efficiency of power transmitted from the TX100 to the RX200 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: Transmitting antenna winding resistance L1: Self-inductance of the power transmitting antenna V1: The transmission voltage (input voltage) applied to the 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 receiving antenna L2: Self-inductance of the receiving antenna V2: The 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 using the following formula 2. k=(V2 / V1) √(L1 / L2) (Equation 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 the RX200 holds in advance. The TX100 calculates the k value using the measured transmitting voltage V1, the value of the self-inductance L1 of the transmitting antenna that the TX100 holds in advance, and the receiving voltage V2 and self-inductance L2 values ​​received from the RX200. Alternatively, the RX200 can notify the TX100 of V2, as well as a constant calculated using either or all of L1 and L2, 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 transmitting voltage V1 and the value of the self-inductance L1 of the transmitting antenna that it has stored in advance. The RX200 calculates the k value using the measured receiving voltage V2, the value of the self-inductance L2 of the receiving antenna that it has stored in advance, and the values ​​of the transmitting voltage V1 and self-inductance L1 that it has received from the TX100. Alternatively, the TX100 can notify the RX200 of V1, as well as a constant calculated using either or all of L1 and L2, and the RX200 can calculate the k value using the constant received from the TX100, V1, and the receiving voltage V2 that it has measured.

[0136] The transmission voltage V1 is calculated by the TX100 by actually measuring the voltage applied to the power transmitting antenna or by the TX100 from the set value of the power transmission power. Alternatively, the transmission voltage V1 may be set as the set value of the power 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 TX100 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 TX100 is, for example, the inverter input voltage input to the inverter included in the power transmitting unit 103 of the TX100, or the inverter output voltage output by the inverter. In this case, the transmission voltage V3 may also be calculated by the TX100 from the set value of the power transmission power. Alternatively, the TX100 may 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 TX100 may transmit the measured values ​​of the transmission voltage V3 and the voltage across the resonant capacitor 107 to the RX200, and the RX200 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. 12(A). 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 power receiving voltage V2 applied to the power receiving antenna can be calculated from the power receiving voltage (denoted as V5) of 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 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. In this case, the RX200 may actually measure the power receiving voltage V4 and the voltage across the resonant capacitor 211 and use these measurements to calculate the power receiving voltage V2. Alternatively, the RX200 may actually measure the power receiving voltage V5 and the voltage across the resonant capacitor 211 and use these measurements to calculate the power receiving voltage V2. Alternatively, the RX200 may transmit the measured values ​​of the power receiving voltage V4 and the voltage across the resonant capacitor 211 to the TX100, and the TX100 may calculate the power receiving voltage V2, thereby calculating the k value. Alternatively, the RX200 may transmit the measured power receiving voltage V5 and the value of the voltage across the resonant capacitor 211 to the TX100, and the TX100 may calculate the k value by determining the power receiving voltage V2.

[0138] Alternatively, when the TX100 or 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 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 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 multiple load states of the 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 is to use a transmission voltage V3 applied to a circuit (e.g., an inverter) included in the power transmitting unit 103 of the TX100 and a receiving voltage (denoted as V4) applied to a circuit (e.g., a rectifier) ​​included in the power receiving unit 203 of the RX200. Here, the transmission voltage V3 applied to the circuit included in the power transmitting unit 103 of the TX100 is, for example, an inverter input voltage input to an inverter included in the power transmitting unit 103 of the TX100, 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 RX200 is, for example, a rectifier input voltage input to a rectifier included in the power receiving unit 203 of the RX200. 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 status 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 of the receiving antenna (for example, L2), and the TX100 can calculate the coupling status index using the constant.

[0143] The TX100 and RX200 exchange information such as voltage values ​​V1 to V5, self-inductance values ​​L1 and L2, and constants representing the electrical characteristics of the transmitting and receiving antennas. The timing of voltage measurement and the timing of sending and receiving each piece of information are described below. Measurement of each voltage value is performed, for example, during the Ping phase. During the Ping phase, the TX100 sends a Digital Ping to the RX200. Therefore, any one of the voltage values ​​V1, V2, V3, V4, and V5 generated when the Digital Ping is sent can be used. During the Ping phase, the TX100 and RX200 measure any one of the values ​​V1 to V5 and store it in memory 106 or memory 208. Alternatively, the TX100 sends a specified packet to the RX200 notifying it of the timing of voltage measurement. Upon receiving the specified packet, the RX200 measures any one of the voltage values ​​V2, V4, or V5. The RX200 measures one of the values ​​V2, V4, and V5 and stores and holds the value in the memory 208. Alternatively, the RX200 transmits a predetermined packet to the TX100 to notify the timing of voltage value measurement. Upon receiving the predetermined packet, the RX200 measures one of the voltage values ​​V1 and V3. The TX100 measures one of the values ​​V1 and V3 and stores and holds the value in the memory 106.

[0144] The TX100 transmits a predetermined transmission request packet to the RX200 to request transmission of a packet containing information on any or all of the voltage values ​​V2, V4, and V5. Upon receiving the transmission request packet, the RX200 transmits a predetermined packet containing information on any or all of the voltage values ​​V2, V4, and V5 to the TX100. The TX100 receives the predetermined packet containing information on any or all of the voltage values ​​V2, V4, and V5 notified from the RX200 and stores the information in the memory 106. The information contained in the predetermined packet may include not only the voltage of the RX200, 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, the information may also include information on the temperature of the RX200. The TX100 receives the information from the RX200 and performs more appropriate control using the information and the calculated coupling state index. The specified packet can be a Signal Strength Data packet, which notifies the TX100 of information about the RX200. Alternatively, the specified packet may be an Identification Data packet or an Extended Identification Data packet in the Configuration phase. Or it may be a Configuration Data packet. Or it may be a packet in the Calibration phase or the Power Transfer phase. In other words, it may be RP1, RP2, or RP0. Note that the present invention is not limited to the example in which the voltage value generated when the TX100 transmits a Digital Ping may be used. Any of the voltage values ​​V1 to V5 generated when the TX100 transmits an Analog Ping in the Selection phase may also be used. Alternatively, any of the voltage values ​​V1 to V5 generated when the TX100 transmits power to the RX200 in the Power Transfer phase may also be used.

[0145] The RX200 transmits a predetermined transmission request packet to the TX100 to request transmission of a packet containing information on either or all of the voltage values ​​V1 and V3. Upon receiving the transmission request packet, the TX100 transmits to the RX200 a predetermined packet containing information on either or all of the voltage values ​​V1 and V3.

[0146] The RX200 receives a predetermined packet containing information on either or both of the voltage values ​​V1 and V3 notified from the TX100 and stores the information in the memory 208. The information contained in the predetermined packet may include not only the voltage of the TX100 but also information such as the transmitted 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 above-mentioned foreign object detection methods (power loss method, Q-factor measurement method, waveform attenuation method) and information on the temperature of the TX100. The RX200 receives the information from the TX100 and can perform more appropriate control using the information and the calculated coupling status index. Furthermore, the RX200 can notify the RX200 of the information on the TX100 using a Power Transmitter Capabilities (CAP) Data Packet as the predetermined packet. Alternatively, the RX200 can notify the RX200 of the information on the TX100 using a Power Transmitter Identification (ID) Data Packet. Note that the present invention is not limited to the example of using the voltage value generated when the TX100 transmits a Digital Ping. Any of the voltage values ​​V1 to V5 generated when the TX100 transmits an Analog Ping in the Selection phase may be used. Alternatively, any of the voltage values ​​V1 to V5 generated when the TX100 transmits power to the RX200 in the Power Transfer phase may be used.

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

[0148] Next, we will explain the second measurement method as another example of a method for measuring the coupling status indicator between the transmitting antenna and the receiving antenna. The measurement performed in the second measurement method will be referred to as the second measurement hereinafter. Figure 12(B) is an equivalent circuit diagram for explaining the second measurement method. r1, r2 and L1, L2 are the same as in Figure 12(A). The definitions of various quantities related to the transmitting antenna (coil) on the primary side (TX100) are shown below. V6: Input voltage of the transmitting antenna when the receiving antenna is shorted (transmitting voltage) V7: Input voltage of the transmitting antenna when the receiving antenna is open (transmitting voltage) I1: Current flowing through the transmitting antenna when the receiving antenna is shorted I2: Current flowing through the transmitting antenna when the receiving antenna 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). In this state, the Lsc value can be obtained by measuring the inductance value of the power transmitting antenna. 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). In this state, the Lopen value can be obtained by measuring the inductance value of the power transmitting antenna. 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 TX100 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 voltages 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 TX100 are, for example, the inverter input voltage or the inverter output voltage. The input voltages V6 and V7 may also be the voltages 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 obtained 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 TX100 may calculate the transmission voltage applied to the circuit (e.g., an inverter) included in the power transmitting unit 103 from the set value of the transmission power.

[0153] 12(B), the current I1 or I2 is not limited to the 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 TX100 is, for example, the inverter input current or the 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 may be used. Instead of the open state, a connected load 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 when 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 the measurement. The timing of measurement is determined by the TX100 and notified to the RX200, or the RX200 determines and notifies the TX100. The RX200 also notifies the TX100 when it has completed control to set both terminals of the circuit including the power receiving antenna to a SHORT or OPEN state. These notifications are made 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 TX100 transmits a Digital Ping to the RX200. Therefore, the values ​​of V6 and V7 and the currents I1 and I2 generated when the Digital Ping is transmitted can be used. During the Ping phase, the TX100 acquires the values ​​of V6, V7, I1, and I2, stores them in the memory 106, and calculates the coupling status index. Note that the TX100 is not limited to using the voltage values ​​and current values ​​generated when the TX100 transmits a Digital Ping. For example, the values ​​of V6, V7, I1, and I2 generated when the TX100 transmits an Analog Ping during the Selection phase can also be used. Alternatively, the voltage values ​​of V6, V7, I1, and I2 generated when the TX100 transmits power to the RX200 during the Power Transfer phase can also be used.

[0156] In the present disclosure, both the first and second measurement methods can be applied to the method for measuring the coupling status indicator between the power transmitting antenna and the power receiving antenna. The following describes a method for setting a status determination threshold for the coupling status indicator acquired by the first or second measurement method. The status determination includes, for example, determining whether a foreign object is detected between the power transmitting antenna and the power receiving antenna, determining whether a misalignment between the power transmitting antenna and the power receiving antenna is detected, or determining whether the power transmitting antenna and the power receiving antenna are separated from each other. By implementing the first or second measurement method, it is possible to determine whether a status abnormality exists using the status determination threshold. The following describes the first to fourth threshold setting methods.

[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 abnormal status is set as the threshold. The status detection produces a judgment result such as "there is an abnormal status," "there is a high possibility of an abnormal status," "there is a low possibility of an abnormal status," or "there is no abnormal status." Assume that the RX200 is placed on the test TX100 and there is no abnormal status between the transmitting antenna and the receiving antenna. In this case, the value of the coupling status indicator between the test TX100 including the transmitting antenna and the RX200 including the receiving antenna can be set as the threshold. The RX200 stores the value of the coupling status indicator measured in advance in its memory, and the RX200 notifies the TX100 of the threshold. The TX100 uses the threshold to perform judgment processing related to status detection. The RX200 may transmit this threshold to the TX100 by including it in an 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 transmission efficiency is obtained may be set as the threshold value. In the state detection, for example, the following determination results are obtained. "The specified power transmission efficiency cannot be achieved" or "The coupling between the power transmitting antenna and the power receiving antenna is weak" "There is a high possibility that the specified power transmission efficiency will not be achieved," or "There is a possibility that the coupling between the power transmitting antenna and the power receiving antenna is weak." "There is a high possibility that the specified power transmission efficiency can be achieved," or "There is a possibility that the coupling state between the power transmitting antenna and the power receiving antenna is good." "A specified power transmission efficiency is achieved" or "The coupling between the power transmitting antenna and the power receiving antenna is good"

[0158] Here, it is assumed that the RX200 is placed on the test TX100, there is no abnormality between the power transmitting antenna and the power receiving antenna, and a predetermined power transfer efficiency is obtained. In this case, the value of the coupling status index between the test TX100 including the power transmitting antenna and the RX200 including the power receiving antenna can be used as the threshold. The RX200 stores the value of the coupling status index measured in advance as a threshold in memory and notifies the TX100 of the threshold. The TX100 uses the threshold to perform a determination process related to status detection. The RX200 may transmit this threshold to the TX100 by including it in an 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 status indicator measured by the first or second measurement method as the threshold in a predetermined state. The predetermined state is a state in which there are no abnormal conditions between the transmitting antenna and the receiving antenna. Methods for confirming this state include foreign object detection using the power loss method, the waveform attenuation method, the 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 are no abnormal conditions, it can be confirmed with a high probability that there are no abnormal conditions between the transmitting antenna and the receiving antenna.

[0160] In other words, 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 binding condition indicator is measured using the first or second measurement method, and an appropriate threshold 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 renegotiation phase. If the foreign object detection processing results in a "no abnormality" (or "no foreign object"), the coupling status indicator is measured using the first or second measurement method after the negotiation phase or renegotiation 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 coupling status indicator 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 ping phase. In this case, the coupling status indicator is measured using the first or second measurement method after the phase in which the foreign object detection processing was performed, and an appropriate threshold value can be set based on the measurement results. Alternatively, foreign object detection processing using the waveform attenuation method described above is performed during the power transfer phase. After the foreign matter detection process is performed, the binding state indicator is measured using the first or second measurement method, and a more appropriate threshold value can be set based on the measurement result.

[0162] Next, a third threshold setting method will be described with reference to Fig. 13. Fig. 13 is a diagram for explaining 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 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 FIG. 3, the power receiving unit 203 of the RX200 is connected to the charging unit 206 and the battery 207 as loads, so the calculated coupling state index value changes depending on the load state. In order to determine whether or not there is a state abnormality depending on the load state, it is necessary to set a threshold value for the coupling state index. First, when power is transmitted from the TX100, the RX200 controls the load so that it is in a light load state. A light load state is a state in which no power is supplied to the load of the RX200, or a state in which only power below a threshold is supplied. 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 "fifth range").

[0164] The transmission power value of the TX100 in this state is set to Pt1. Then, the RX200 sends a packet to the TX100 requesting that a coupling status indicator be measured. Alternatively, the TX100 sends a packet to the RX200 requesting that a coupling status indicator be measured. In this state, the TX100 and RX200 measure the transmission voltage on the TX100 side and the receiving voltage on the RX200 side. The TX100 and RX200 exchange information such as the values ​​of V1 to V7, the self-inductances L1 and L2, and constants calculated using the electrical characteristics of the transmitting and receiving antennas, and the TX100 or RX200 calculates the coupling status indicator value k1. When the RX200 calculates the coupling status indicator value k1, it notifies the TX100 of the result. When the TX100 calculates the coupling status indicator 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 RX200 measure the transmitted voltage on the TX100 side and the received voltage on the RX200 side. The TX100 and 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 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 TX100 and the RX200. Using line segment 1202, the TX100 can estimate the coupling state index value for each transmission power value when there are no abnormal conditions around the TX100 and the RX200. 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 TX100 can calculate a threshold value used to determine whether or not there is 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 abnormal state at a certain transmission power value can be set as the determination threshold value.

[0166] In this way, the CAL process performed by the TX100 and the RX200 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 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 the measurement 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 in the calibration phase. The first reference received power information is information according to RP1 defined in the WPC standard, but other messages may also be used. Furthermore, when the TX100 receives the second reference received power information from the 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 defined 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 CP1200 and CP1201 can be measured in a shorter time.

[0168] In the fourth threshold setting method, the TX100 or RX200 presets a threshold for a coupling status indicator that has a value within a predetermined range. The TX100 or RX200 holds this threshold as a common value that is independent of the RX200 to which power is transmitted. The threshold may be a fixed value that does not depend on the situation, or a variable value that the TX100 or RX200 determines depending on the situation. For example, if the coupling status indicator is a coupling coefficient k, the range of k is "0≦k≦1." For example, the TX100 or RX200 determines that "there is a status abnormality" when "0≦k<0.2" and "there is a high possibility of a status abnormality" when "0.2≦k<0.5." The TX100 or RX200 determines that "there is a low possibility of a status abnormality" when "0.5≦k<0.8" and "there is no status abnormality" when "0.8≦k≦1." Data on conditions for the k value is stored in advance in memory, and the determination process is performed based on this data.

[0169] Alternatively, for example, the TX100 or RX200 determines that "the specified power transfer efficiency cannot be achieved" or "the coupling between the power transmitting antenna and the power receiving antenna is weak" when "0≦k<0.2." The TX100 or RX200 determines that "the specified power transfer efficiency is likely to be not achieved" or "the coupling between the power transmitting antenna and the power receiving antenna may be weak" when "0.2≦k<0.5." The TX100 or RX200 determines that "the specified power transfer efficiency is likely to be achieved" or "the coupling between the power transmitting antenna and the power receiving antenna may be good" when "0.5≦k<0.8." The TX100 or RX200 determines that "the specified power transfer efficiency can be achieved" or "the coupling between the power transmitting antenna and the power receiving antenna is good" when "0.8≦k≦1." Condition data for the k value is stored in memory in advance, and the determination process is performed based on that 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 result 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 RX200 transmitting a predetermined packet to the TX100. Here, the predetermined packet is a Signal Strength Data packet transmitted by the RX200 to the TX100. Alternatively, it may be an Identification Data packet or an Extended Identification Data packet in the Configuration phase. Alternatively, it may be a Configuration Data packet. Alternatively, it 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 indicator between the power transmitting antenna and the power receiving antenna. Then, the TX100 makes a judgment by comparing the calculated coupling status indicator with the judgment threshold set by the above method. If the TX100 judges that there is no status abnormality, it sends an acknowledgment ACK to the RX200, or status information indicating that there is no status abnormality. If the TX100 judges that there is a low possibility of a status abnormality or that there is a high possibility of a status abnormality, it sends status information indicating the respective judgment result to the RX200. If the TX100 judges that there is a status abnormality, it sends a negative acknowledgment NAK to the RX200, or status information indicating that there is a status abnormality.

[0173] Alternatively, if the TX100 determines that "a predetermined power transfer 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 "the predetermined power transfer 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 "the predetermined power transfer 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 "the predetermined power transfer 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 state information is, for example, numerical information according to the state, as follows: Status information "0" corresponds to the determination result of "no status abnormality", or "the specified power transmission efficiency can be achieved", 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 achieving the specified power transmission efficiency", or "the coupling state between the power transmitting antenna and the power receiving antenna is good". Status information "2" corresponds to the determination result that "there is a high possibility of a status abnormality," or "there is a high possibility that the specified power transmission efficiency cannot be achieved," or "there is a possibility that the coupling between the power transmitting antenna and the power receiving antenna is weak." Status information "3" corresponds to the determination result of "abnormal status exists," or "predetermined power transmission efficiency cannot be achieved," or "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 by 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 power transmitting antenna and the power receiving antenna. Then, the RX200 makes a judgment by comparing the calculated coupling status index with the judgment threshold set by the above method. If the RX200 judges that there is no abnormal status, it transmits a predetermined packet containing status information indicating the judgment result to the TX100. If the RX200 judges 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 containing status information indicating the respective judgment result to the TX100. If the RX200 judges that there is a abnormal status, it transmits a predetermined packet containing status information indicating the judgment result to the TX100.

[0177] Alternatively, if the RX200 determines that "a predetermined power transfer 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 transfer 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 transfer 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 transfer 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 state information is, for example, numerical information according to the state, as follows: Status information "0" corresponds to the determination result of "no status abnormality", or "the specified power transmission efficiency can be achieved", 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 achieving the specified power transmission efficiency", or "the coupling state between the power transmitting antenna and the power receiving antenna is good". Status information "2" corresponds to the determination result that "there is a high possibility of a status abnormality," or "there is a high possibility that the specified power transmission efficiency cannot be achieved," or "there is a possibility that the coupling between the power transmitting antenna and the power receiving antenna is weak." Status information "3" corresponds to the determination result of "abnormal status exists," or "predetermined power transmission efficiency cannot be achieved," or "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 that the TX100 transmit higher power to the RX200. The WPC standard includes a Baseline Power Profile (BPP) that transmits 5 watts or less to the RX200, and an Extended Power Profile (EPP) that 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, it assumes a case where the TX100 transmits more than 15 watts of power to the RX200. This state (profile, mode) in which more than 15 watts of wireless power is transmitted to the RX200 is called a rapid charge mode or rapid 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, fast charge profile, or fast charge power profile. The maximum GP that can be set in a fast charge mode, fast charge profile, or fast charge power profile is 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 RX200 perform wireless charging in quick 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 phases (not shown) after the TX100 and RX200 have executed the above-mentioned Selection phase, Ping phase, and Configuration phase. First, in the Negotiation phase, the RX200 requests the transmission of information indicating whether the power transmitting device supports quick 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 rapid charge mode is supported. When the TX100 notifies the RX200 that the rapid charge mode is supported, the TX100 stores "1" in the corresponding field. When the TX100 notifies the RX200 that the rapid charge mode is not supported, the TX100 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. The fields for storing the major and minor versions of the Power Transmitter ID data packet store information that can identify the version of the WPC standard (Qi standard) that the TX100 supports. These fields are used to store information about the version that supports MPP (described below) and information about the version that supports MPP and the fast charge mode. If the TX100 does not support MPP (described below), it controls the RX200 so as not to notify the RX200 of information indicating that it supports the fast 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 send "version information that supports both MPP and the fast charge mode." For example, it may also send "version information that does not support either MPP or the fast charge mode." Furthermore, if the TX100 notifies the RX200 of information indicating that it supports the fast charge mode, the TX100 must support MPP (described below). In other words, in the above example, if the TX100 "supports the fast charge mode," the TX100 controls the RX200 to send "version information that supports both MPP and fast 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 makes the determination in F1502 periodically or irregularly 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. In other words, the RX200 returns to the Selection phase.

[0184] When the RX200 receives a packet from the TX100 containing information indicating that the RX200 supports the rapid charge mode (Yes in F1502), the RX200 transmits a packet containing 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 notifying the TX100 that the RX200 supports the rapid charge mode, the RX200 stores "1" in this field, and when notifying 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 containing 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, as long as the packet is used in the negotiation phase, another packet may be used instead of the FOD Status Data Packet. 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 it has not received a packet, it makes the determination in F1403 periodically or irregularly 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 ends the processing. In other words, 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 fast charge mode," and then the RX200 transmits information indicating that "the RX200 supports the fast charge mode" to the TX100. However, the order of transmitting and receiving information may be reversed. That is, the TX100 may receive information from the RX200 indicating that "the RX200 supports the fast charge mode," and then the TX100 may transmit information indicating that "the RX100 supports the fast charge mode" to the RX200. For example, the information indicating that "the RX200 supports the fast 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, it may be stored in a packet transmitted in the configuration phase. This packet may be an identification data packet, an extended identification data packet, or a configuration data packet.

[0186] The Identification Data Packet also has a field for storing version information of the WPC standard. The fields for storing the major and minor versions of the Identification (ID) Data Packet store information that can identify the version of the WPC standard (Qi standard) supported by the RX200. These fields are used to store information about the version that supports MPP (described below) and information about the version that supports MPP and the rapid charge mode. If the RX200 does not support MPP (described below), it controls the RX200 not to notify the TX100 of information indicating that it supports the rapid charge mode described above. In other words, in the above example, if the RX200 "does not support MPP," the RX200 controls the TX100 not to send "version information that supports both MPP and the rapid charge mode." For example, it may also send "version information that does not support either MPP or the rapid charge mode." Furthermore, if the RX200 notifies the TX100 of information indicating that it supports the rapid charge mode described above, the RX200 must support MPP (described below). In other words, in the example above, if the RX200 "supports fast charging mode," the RX200 controls the TX100 to send "version information that supports both MPP and fast charging mode."

[0187] Alternatively, only one of the TX100 and the RX200 may transmit a packet containing information indicating that the RX200 or the TX100 is compatible with the fast charging mode.

[0188] Next, the RX200 transmits a packet including "information for determining whether or not the conditions for transitioning to the rapid charge mode are met" to the TX100 (F1504). This packet can be an FOD Status Data Packet. The FOD Status Data Packets transmitted in F1503 and F1504 can be the same packet, or different FOD Status Data Packets. In the former case, F1503 and F1504 are performed in a single step. In addition, a different packet can be used instead of the FOD Status Data Packet as long as it is 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 "the TX100 supports the rapid charge mode" can be the same type of packet, or they can 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 requirement is that the TX100 and RX200 must support MPP. MPP stands for Magnetic Power Profile, and the WPC has announced that it will adopt MPP in Qi2, the next-generation standard for wireless charging (Qi). MPP functions to precisely fix the TX100 and RX200 in their predetermined positions. There are several possible ways to fix the TX100 and RX200 in their predetermined positions. For example, the TX100's transmitting antenna (transmitting coil) and the RX200's receiving antenna (receiving coil) can be precisely aligned (directly facing each other) using the magnets built into each device. 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 transmitter and receiver. The magnets can be permanent magnets or electromagnets. Increasing power transmission efficiency and reducing power loss when transmitting large amounts of power in fast charging mode are also environmentally beneficial. Therefore, if the TX100 and RX200 are MPP compatible and can operate in MPP, the TX100 and RX200 are controlled to operate in fast charge 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 in MPP, it transmits a packet containing information indicating that it does not support MPP. 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 power transmitting antenna of the TX100 and the power 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 power transmitting antenna of the TX100 and the power receiving antenna of the RX200 to predetermined positions with high precision.

[0192] <First alignment method> The TX100 and RX200 each have a built-in magnet, and the TX100's transmitting antenna and the RX200's receiving antenna are aligned by magnetic force. <Second alignment method> The TX100 has a movable power transmitting antenna, and by moving the power transmitting antenna near the power receiving coil of the RX200, 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 so that the transmitting antenna of the TX100 and the receiving antenna of the RX200 face each other.

[0193] These alignment methods vary in the positional accuracy with which the power transmitting antenna of the TX100 and the power receiving antenna of the RX200 face each other. As described above, the higher the positional accuracy with which the power transmitting antenna of the TX100 and the power 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 power transmitting antenna of the TX100 and the power receiving antenna of the RX200 with a predetermined or higher level of accuracy, the TX100 and the RX200 are controlled to operate in fast charge 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 power transmitting antenna of the TX100 and the power receiving antenna of the RX200 with a predetermined or higher level of precision. The power transmitting antenna (power transmitting coil) of the TX100 and the power receiving antenna (power receiving coil) of the RX200 can be precisely aligned (directly facing each other) by using magnets built into the TX100 and RX200. Therefore, if the TX100 and RX200 are compatible with the first alignment method, they are controlled to operate in rapid charge mode. In F1504, the RX200 transmits a packet to the TX100 containing information 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 RX200 notifies the supported alignment methods by using predetermined information. For example, if the RX200 supports the first alignment method, it will include information "1" in a specified packet and send it to the TX100. If the RX200 supports the second alignment method, it will include information "2" in a specified packet and send it to the TX100. If the RX200 supports the third alignment method, it will include information "3" in a specified packet and send it to the TX100.

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

[0197] [Third condition] The third condition is that the coupling state index of the transmission antenna of TX100 and the reception antenna of RX200 is equal to or greater than a predetermined value. The method for measuring the coupling state index of the transmission antenna of TX100 and the reception antenna of RX200, or the method for setting the threshold value for determining the superiority or inferiority of the coupling state index, is as described above.

[0198] If the transmission antenna of TX100 and the reception antenna of RX200 are facing each other, the value of the coupling state index will also be a good value (a large value in the case of the coupling coefficient), and the power transmission efficiency will be high, which is preferable. Therefore, when the measured coupling state index of TX100 and RX200 is equal to or greater than the set threshold value, TX100 and RX200 are controlled to operate in the rapid charging mode.

[0199] In F1504, RX transmits a packet containing "information used by TX to calculate the coupling state index of the transmission antenna and the reception antenna" to TX. The information received from RX that is necessary for TX to calculate the coupling state index of the transmission antenna and the reception antenna is as described in the explanation of the above coupling state index measurement method.

[0200] In the above description, as a method for obtaining the coupling state index of the transmission antenna of TX100 and the reception antenna of RX200, the explanation was given based on the method for measuring the coupling state index of the transmission antenna of TX100 and the reception antenna of RX200, or the method for setting the threshold value of the coupling state index. The following describes another method for obtaining the coupling state index of the transmission antenna of TX100 and the reception antenna of RX200.

[0201] <Another method for obtaining the coupling state index of the transmission antenna of TX100 and the reception antenna of 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 the voltage value measured by the RX200 regarding the power transmitted by the TX100. In other words, the magnitude of the received voltage value (measured value) indicates the strength of the coupling between the transmitting antenna and the receiving antenna. The TX100 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 TX100 determines that the coupling is strong; if the Signal Strength Value is less than the threshold, the TX100 determines that the coupling is weak. The Signal Strength Value is the voltage value measured by the RX200 of the power transmitted by the TX100. The RX200 determines the strength of the coupling between the transmitting antenna and the receiving antenna by comparing the measured Signal Strength Value with a threshold. If the Signal Strength Value is equal to or greater than the threshold, the RX200 determines that the coupling is strong, and if the Signal Strength Value is less than the threshold, the RX200 determines that the coupling is weak. If the transmitting antenna and the receiving antenna are strongly coupled, the TX100 or RX200 controls them to operate in fast charge mode. If the transmitting antenna and the receiving antenna are weakly coupled, the TX100 or RX200 controls them not to operate in fast charge mode.

[0202] The threshold setting in the above-mentioned "another method for determining the coupling status index between the transmitting antenna of the TX100 and the receiving antenna of the RX200" may be as follows. That is, among the threshold setting methods for measuring the coupling status index, the first or fourth threshold setting method may be implemented, and the TX100 may store the threshold in advance. Also, the RX200 may notify the TX100 of the threshold. Alternatively, the TX100 and RX200 may store the same threshold in advance.

[0203] [Fourth condition] The fourth condition is when no foreign object is detected by the foreign object detection method described above, or when the probability of foreign object presence 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 foreign object presence are as described above.

[0204] If a foreign object is present near the transmitting antenna of the TX100 and the receiving antenna of the RX200, wireless power transmission will undesirably generate heat in the foreign object. This is particularly undesirable, as the power transmitted from the TX100 to the RX200 increases, which is likely to increase the amount of heat generated. Therefore, if the 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, the RX200 transmits a packet to the TX100 that includes "information used by the TX100 to execute a foreign object detection method." The information received from the RX200 and required for the TX100 to execute a foreign object detection method is as described above. In other words, the information received from the RX200 is all the information that the RX200 must provide to the TX100 in order for the TX100 to execute the various foreign object detection methods described above. This information also includes information used to determine the thresholds to be set when executing the 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 its presence may be set to a specific fast-charge mode transition determination threshold for determining whether the conditions for transitioning to 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 fast-charge mode. For example, the threshold for determining transition to 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, while the threshold for determining transition to 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 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 fast 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 switches to fast charge mode when its temperature is high and transmits high power, this could damage 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 fast 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 power transmitting antenna 105, the charging stand 300, and the power receiving antenna 205 than on other locations.

[0209] In F1504, the RX200 transmits a packet including "timing information indicating the timing at which the TX100 acquires temperature information from the temperature sensor of the TX100" to the TX100. This information may include information used to determine the temperature threshold to be set.

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

[0211] The first to sixth conditions have been described above as "conditions for transitioning to the rapid charge mode." Note that 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 them.

[0212] Next, the TX100 determines whether or not a packet containing "information for determining whether or not the conditions for switching to the rapid charge mode are met" has been received 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 a packet containing "information for determining whether or not the conditions for switching to the rapid charge mode are met" has not been 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 the determination result indicates that "the conditions for switching to the rapid charge mode are met" (Yes in F1405), the process proceeds to F1406. If the determination result indicates 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 switching to fast charging mode] If the TX100 receives a packet containing information indicating that "the RX200 is MPP compatible," and if the TX100 is also MPP compatible, it determines that the conditions for transitioning to the rapid charge mode are met and proceeds to F1406. Here, if the TX100 receives a packet that does not contain information indicating that "the RX200 is MPP compatible," it determines that the conditions for transitioning to the rapid charge mode are not met and proceeds to F1415. Alternatively, if the TX100 receives a packet containing information indicating that "the RX200 is not MPP compatible," it determines that the conditions for transitioning to the rapid charge mode are not met and proceeds to F1415. In other words, if both the TX100 and the RX200 are MPP compatible, the TX100 controls the TX100 to operate in the rapid charge mode. On the other hand, if at least one of the TX100 or the RX200 is not MPP compatible, the TX100 controls the TX100 not to operate in the rapid charge mode.

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

[0217] [When the third condition is included as a condition for switching to fast charging mode] The TX100 calculates the coupling status index using "information used by the TX100 to calculate the coupling status index of the power transmitting antenna and the power receiving antenna." If the coupling status index 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 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 TX100 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 switching to fast charging 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 conditions for transitioning to the rapid charge mode are met, 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 conditions for transitioning to the rapid charge mode are not met, and proceeds to F1415.

[0219] [When the fifth condition is included as a condition for switching to fast charging mode] When the TX100 receives a packet from the RX200 that includes "timing information indicating the timing at which the TX100 acquires temperature information from the TX100's temperature sensor," it acquires the value of the TX100's temperature sensor at the time the packet is received. The TX100 then determines whether or not the conditions for transitioning to rapid charge mode are met. If the acquired temperature sensor value of the TX100 satisfies a predetermined condition, the TX100 determines that the conditions for transitioning to rapid charge mode are met, 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 TX100 acquires the value of the temperature sensor of the TX100 at the timing when it receives "timing information indicating the timing when the TX100 acquires temperature information from the temperature sensor of the TX100" from the RX200. However, this is not a limitation, and for example, the TX100 may acquire temperature information from the temperature sensor of the TX100 at a timing determined by the TX100 at predetermined intervals.

[0221] Furthermore, the TX100 is not limited to determining whether to transition to the rapid charge mode based on the acquired temperature sensor value. For example, the TX100 may calculate the temperature rise rate based on multiple temperature detection values ​​acquired at predetermined times. In this case, the TX100 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 TX100 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 the value of its temperature sensor and transmit a packet including "temperature information from the RX200's temperature sensor" to the TX100. This information may also include information used to determine the temperature threshold to be set. In this case, if the received value from the RX200's temperature sensor 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 value from the RX200's temperature sensor is equal to or less than a predetermined value. If the value from the RX200's temperature sensor 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 value from the RX200's temperature sensor 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 if the temperature rise rate is equal to or less than a predetermined threshold, determine that "the conditions for transitioning to the rapid charge mode are met." If the temperature rise rate is equal to or greater than a predetermined threshold, the TX100 may also determine that "the conditions for transitioning to the rapid charge mode are not met."

[0224] Using the method described above, the TX100 determines in F1405 whether or not the conditions for transitioning to the rapid charge mode are met. The flow from F1405 onwards will be explained 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 makes the determination in F1505 periodically or irregularly until a predetermined period has elapsed (No in F1505, No in F1518). If the RX200 does not receive a packet containing information indicating that "the conditions for transitioning to the fast charge mode are met" within the predetermined time (No in F1505, Yes in F1518), the RX200 ends the process. In other words, the RX200 returns to the Selection phase.

[0225] If the result of 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 that indicates 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 a different packet may be used in place of the FOD Status Data Packet as long as it is used in the negotiation phase.

[0226] If the TX100 does not receive the packet containing information requesting transition to the rapid charge mode (No in F1407), the process proceeds to F1415. If the TX100 receives the packet (Yes in F1407), the TX100 transmits an ACK, which is an affirmative response, to the RX200 (F1408). The TX100 then 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 repeats 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 process ends. In other words, the process returns to the Selection phase. If the RX200 receives an ACK from the TX100 (Yes in F1507), the process proceeds to F1508.

[0227] The following describes the operation of the TX100 in the fast charge mode from F1409 onwards. At F1409, the TX100 executes negotiation / renegotiation corresponding to the power in fast charge mode. Specifically, the TX100 can set the Negotiable Load Power to greater than 15 watts. More specifically, the TX100 can set the Negotiable Load Power to Potential Load Power. Potential Load Power is the highest GP level that the TX100 can negotiate. This allows the GP to be set to greater than 15 watts. However, the Negotiable Load Power may not be set to Potential Load Power due to other conditions. As a result, even in fast charge mode, the GP is not necessarily set to greater than 15 watts. Negotiation / renegotiation is an operation executed in the negotiation phase described above. Through the above control, the TX100 and RX200 agree on the GP through negotiation.

[0228] Then, the process proceeds to F1410, where CAL processing / ReCAL processing corresponding to the power in the fast 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 fast charge mode. Line 1002 in FIG. 4 is created taking into account the GP in the fast charge mode. Note that the number of calibration points created in the CAL processing / ReCAL processing in the fast 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 in the fast charge mode may be controlled to be greater than or equal to a predetermined number. The "predetermined number" is, for example, "3" or a greater number. Alternatively, the number of calibration points created in the CAL processing / ReCAL processing in the fast charge mode may be determined according to the value of the GP. 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 method for determining the number of calibration points described above is applicable to the "CAL processing of the power loss method," "CAL processing of the waveform decay method," and "CAL processing of the binding state index measurement method" described above.

[0229] Furthermore, the calibration points may be controlled so as 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 less to the RX200. The process proceeds to F1412, where authentication is performed as defined in the WPC standard. 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 predetermined conditions. If the RX200 determines that the response satisfies the predetermined conditions, the RX200 transmits a predetermined second packet to the TX100. The RX200 determines whether authentication was successful based on the content of the response from the TX100 that received the predetermined packet (F1412). Alternatively, in authentication, in addition to the process in which the RX200 authenticates the TX100, the TX100 may also authenticate the RX200. 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 predetermined third packet to the RX200. The TX100 determines whether the response from the RX200 that received the predetermined packet satisfies predetermined conditions. If the TX100 determines that the response satisfies the predetermined conditions, the TX100 transmits a predetermined fourth packet to the RX200. The TX100 determines whether authentication has been successful based on the content of the response from the RX200 that received the predetermined packet (F1412). In this case, the TX100 and RX200 determine that "authentication has been successful" if the RX200 has successfully authenticated the TX100 and the TX100 has successfully authenticated the 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. If the authentication is successful, the RX200 can receive power from a reliable TX100. Therefore, when the RX200 attempts to receive a large amount of power in rapid charge mode from the TX100, the RX200 controls the transition to rapid charge mode only if the authentication is successful. In rapid charge mode, power can be transmitted up to the GP determined in F1409. On the other hand, if the authentication is unsuccessful (No in F1412), the process proceeds to F1415.

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

[0234] Next, the operation of the TX100 after F1415 will be explained. After F1415, it is determined that the device will operate in BPP or EPP mode, rather than in fast charge mode. At 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 power of the BPP / EPP is performed. CAL processing / ReCAL processing is an operation performed in the calibration phase described above. Since the GP is set to 5 watts or less for the BPP or 15 watts or less for the 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 the BPP or EPP.

[0236] 4 is created taking into account the GP of BPP or EPP. Next, proceeding to F1417, TX100 starts transmitting power to RX200 at BPP or EPP. This concludes the explanation of the operations from F1415 to F1417.

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

[0238] Then, the process proceeds to F1509, where the CAL process / ReCAL process corresponding to the power in the quick charge mode is executed. This process has been explained in F1410 above, so the explanation will be omitted.

[0239] Next, the process proceeds to F1510, where the RX200 starts receiving power from the TX100 at less than 5 watts or equal to or less than 5 watts. Then, the process proceeds to F1511, where authentication is performed as defined in the WPC standard. If the authentication is successful (Yes in F1511), the process proceeds to F1512, where the "control during quick charge mode operation" described in the second embodiment is performed. Then, the process proceeds to F1513, where power reception in quick 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, we will explain the operation of the RX200 from F1514 onwards. F1514 and onwards is the operation when it has been decided to operate in BPP or EPP rather than in fast charge mode. In F1514, the RX200 executes Negotiation / Renegotiation corresponding to the BPP / EPP power. Negotiation / Renegotiation is the 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. This sets the GP 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 power of the BPP / EPP is executed. This processing was explained in F1416 above, so the explanation will be omitted. Next, the process proceeds to F1516, where the RX200 starts receiving power from the TX100 via the BPP or EPP. This concludes the explanation of the operations from F1514 to F1516.

[0242] FIG. 16 is a sequence diagram when power is transmitted from the TX100 to the RX200 in quick charge mode. First, the RX200 requests information indicating whether or not the TX100 supports quick charge mode (S1601), and the TX100 receives this request (S1602). The TX100 and RX200 each notify each other that they support quick charge mode (S1603, S1604). The RX200 notifies the TX100 of information used to determine whether or not the "conditions for transitioning to quick charge mode" are met (S1605). Based on this information, the TX100 determines whether or not the conditions for transitioning to quick charge mode are met (S1606). Then, because the conditions for transitioning to quick charge mode are met, the TX100 notifies the RX200 that the conditions for transitioning to quick charge mode are met (S1607). Next, the RX200 notifies the RX100 of a request to transition to quick charge mode (S1608). The TX100 then transmits an acknowledgement (ACK) (S1609). After that, the TX100 and RX200 execute negotiation / renegotiation corresponding to the power of the fast charge mode (S1610). Next, the TX100 and RX200 execute CAL processing / ReCAL processing corresponding to the power of the fast charge mode (S1611). Then, the RX200 executes authentication of the TX100 (S1612). The TX100 also executes authentication of the RX200 (S1612). If authentication is successful (S1613), the TX100 and RX200 execute "control during fast charge mode operation" (S1614). Then, the TX100 and RX200 start transmitting power in fast charge mode (S1615).

[0243] The order of steps S1601 to S1607 until the RX200 notifies the TX100 of a request to transition to the rapid charge mode may be different. For example, steps S1605 to S1607 may be performed first, followed by steps S1601 to S1604. In this case, if it is determined in step S1606 that the TX100 does not satisfy the conditions for transitioning to the rapid charge mode, the TX100 may not perform step S1607, and the TX100 and RX200 may also be controlled not to perform steps 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 fast charge mode will be described using Figures 33 and 34. 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 signal modulation method used in communication for transmitting information from the RX200 to the TX100 is a modulation method 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 it has received a predetermined packet from the RX200 including information indicating that the RX200 is a modulation method different from the modulation method used in BPP or EPP. If it is determined that the predetermined packet has been received, the process proceeds to F3303. If it is determined that the predetermined packet has not been received, the TX100 proceeds to F3302 and determines whether or not a predetermined time has elapsed. If it is determined in F3302 that the predetermined time has not elapsed, the TX100 returns to F3301. If it is determined in F3302 that the predetermined time has elapsed, the TX100 terminates its operation. In this case, the RX200 and TX100 use the modulation method used in conventional BPP and EPP.

[0246] In F3303, the TX100 determines whether the conditions for changing the modulation method of signals in communications related to information transmission from RX to TX are met based on the information contained in the received predetermined packet. Specifically, in F3303, the TX100 makes this determination based on whether the TX100 supports the modulation method that the RX200 supports, as notified by the predetermined packet. If the determination result in F3303 is Yes, the TX100 transmits to the RX200 a packet containing information indicating that the conditions for changing the modulation method are met (F3304). If the determination result in F3303 is No, the operation ends. In this case, the RX200 and TX100 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 that includes 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 ends operation. In this case, the RX200 and TX100 use the modulation method used in conventional BPP or 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 operation. In this case, the RX200 and the TX100 use the modulation method used in conventional BPP or EPP.

[0249] In F3405, the RX200 transmits a packet containing information requesting a change in the modulation method to the TX100 (F3405). The TX100 determines whether or not it has received a packet containing information requesting a change in the modulation method from the RX200 (F3305). If the determination result in F3305 is No, the TX100 terminates its operation. In this case, the RX200 and TX100 use the modulation method used in the conventional BPP or EPP. If the determination result in F3305 is Yes, the TX100 proceeds to F3306 and transmits an ACK to the 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 RX200 determines in F3406 that it has received an ACK from the TX100, it proceeds to F3408, changes the modulation method, and uses the changed modulation method to communicate with the TX100. The TX100 changes the modulation method in F3307, and uses the changed modulation method to communicate with the RX200.

[0252] Figure 35 is a sequence diagram showing the above-mentioned control flow. The RX200 sends the TX100 a packet containing information indicating that it supports a modulation method different from the modulation method used in BPP or EPP (S3501). The TX100 determines whether the conditions for changing the modulation method of the signal in communication are met (S3502). The TX100 notifies the RX200 that the conditions for changing the modulation method are met (S3503). The RX200 notifies the TX100 that it requests a change of the modulation method (S3504). The TX100 sends an ACK to the RX200 indicating approval (S3505). The 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 for communication related to information transmission from the RX200 to the TX100. The RX200 and the TX100 can then 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 that it transmits 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 will operate in the fast charge mode, it stores data (e.g., "1") in a predetermined field in the Configuration Data Packet indicating that a modulation method different from the modulation method used in BPP or EPP will be used. 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 that field. Furthermore, "3" corresponding to the use of a third modulation method different from the first and second modulation methods is stored in that field. On the other hand, when the TX100 and RX200 do not operate in the fast charge mode, that is, when operating 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 that field. Alternatively, for each modulation method, the RX200 stores information indicating whether or not it supports that modulation method in a predetermined field. If the modulation method is supported, "1" is stored as data in that field, and if the modulation method is not supported, "0" is stored as data in that field. The RX200 transmits the packet to the TX100.

[0255] When executing the above process, the RX200 may notify the TX100 of the modulation method to be used in advance using 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 RX200 operate in fast charge mode, it 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 quick charge mode (F2101 described below). However, this information may also be transmitted before starting power reception in quick charge mode.

[0257] In the above example, the "predetermined packet containing information indicating that the RX200 supports a modulation method different from that used in BPP or EPP" sent to the TX100 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 the TX100 and RX200 when changing the modulation method of signals in communications related to information transmission from RX200 to TX100 was described. Conversely, when changing the modulation method of signals in communications related to information transmission from TX100 to RX200, simply read TX100 as RX200 and RX200 as TX100 in the above explanation. In this case, the following packets are examples of "predetermined packets containing information indicating that TX100 supports a modulation method different from the modulation methods used in BPP and EPP" that TX100 sends 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(XCAP data packet, Power Transmitter 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 TX100 to RX200 and communication related to information transmission from RX200 to TX100." 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 TX100's transmitting antenna and the RX200's receiving antenna." Using the method described above, the TX100 or RX200 measures the coupling status between the TX100's transmitting antenna and the RX200's receiving antenna. 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 a small coupling status index makes communication unstable, so increasing the modulation index improves communication stability.

[0261] The "modulation method" described in this embodiment can be applied to both "primary modulation method" and "secondary modulation method." "Primary modulation method" includes ASK, PSK, FSK, and QAM. "Secondary modulation method" includes 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 RX200 execute the controls shown in FIGS. 33 and 34 in parallel with the controls shown in FIGS. 14 and 15, respectively. The control of F3307 in FIG. 33 of the TX100 corresponds to the control of F1413 in FIG. 14. The control of F3408 in FIG. 34 of the RX200 corresponds to the control of F1512 in FIG. 14. In other words, when operating in fast charge mode, the TX100 and RX200 are controlled to use a modulation method different from that used in BPP or EPP. Alternatively, when operating in fast charge mode, the TX100 and RX200 may be controlled to use the modulation method used in BPP or EPP instead of a modulation method different from that used in BPP or EPP. By controlling in this manner, when the RX200 and TX100 enter fast charge mode, it is possible to set or change the modulation method of the signal in in-band communication related to information transmission from RX to TX. This makes it possible to apply a modulation method more suitable for fast 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 TX100 may notify the RX200 of information for determining whether or not the "conditions for transitioning to the rapid charge mode" are met using a predetermined packet. This packet may be a Power Transmitter Capabilities (CAP) Data Packet. Alternatively, this packet may be 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 RX200. Specifically, the RX200 may first request the transmission of information for determining whether or not the "conditions for transitioning to the rapid charge mode" are met using a GRQ Data Packet. Then, in response to this request, the TX100 may transmit information for determining whether or not the "conditions for transitioning to the rapid charge mode" are met.

[0265] The RX200 may also determine that the "conditions for transitioning to the rapid charge mode" are met and notify the TX100 of this fact using a predetermined packet. This packet may be an ACK, which is an acknowledgement.

[0266] The RX200 may also request a transition to "quick charge mode" using a specific packet. This packet may be an FOD Status Data Packet.

[0267] Furthermore, the information transmitted by the TX100 to the RX200 for determining whether the "conditions for transitioning to the fast charge mode" are met 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 its temperature sensor. Alternatively, it may be a packet that includes information about the value of the TX100's temperature sensor.

[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 "calculation of the coupling state index." Then, the TX100 executes the "foreign object detection process" or "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 "calculation of the coupling state index." That is, it 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 "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 determination result, the RX200 requests transition to the "rapid charge mode." In this case, multiple combinations of the first to sixth conditions may be combined, and control may be exercised so that the "conditions for transitioning to the rapid charge mode are met" when multiple conditions are met.

[0269] Furthermore, the RX200 may perform the operation of F1506 "notifying the power transmitting device of a request to transition to rapid charge mode" during the Power Transfer phase. If the RX200 desires to receive even greater power or determines that certain conditions for receiving greater power have been met during the Power Transfer phase in BPP or EPP, the RX200 performs the operation of F1506. 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. The TX100 then transitions to the operation of F1409 and performs renegotiation corresponding to the power in rapid charge mode. The TX100 then transitions to the operation of F1410 and performs ReCAL corresponding to the power in rapid charge mode. The TX100 then performs the operations of F1412, F1413, and F1414. The RX200 also transitions to the operation of F1508 and performs renegotiation corresponding to the power in rapid charge mode. The RX200 then transitions to operation F1509 and performs ReCAL corresponding to the power in fast charge mode.Then, the TX100 performs operations F1510 to F1513.

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

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

[0272] In the above-described embodiment, the information for determining whether the "conditions for transitioning to the fast charge mode" are satisfied is reported in the negotiation phase, but the information may be reported in other phases. For example, the RX200 may use a signal strength data packet in the ping phase. Alternatively, the RX200 may use 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, step F1504 is performed before step F1501 in FIG. 15 .

[0273] Packets in the calibration phase or power transfer phase may also be used. For example, RP1, RP2, and RP0 may be used. Therefore, the processing from F1503 onwards 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 compatible with the rapid charge mode. Then, they execute control for rapid charge mode operation and start power transmission / reception in the rapid charge mode.

[0275] In the first embodiment described above, the TX100 operates in a case where it is determined, at F1415 in FIG. 14 and thereafter, that it will operate in a BPP or EPP rather than in the rapid charge mode. Alternatively, the TX100 may operate in a case where it is determined, at F1415 in FIG. 14 and thereafter, 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, at F1514 in FIG. 15 and thereafter, that it will operate in a BPP or EPP rather than in the rapid charge mode. Alternatively, the TX200 may operate in a case where it is determined, at F1514 in FIG. 15 and thereafter, 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 that has the function of fixing the TX100 and RX200 in predetermined positions with high precision, this indicates a mode in which the RX200 receives power of 15 watts or less from the TX100.

[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 described in the first embodiment, and F1512 of FIG. 15, which is the flowchart for the RX200. Specifically, the control performed during rapid charge mode operation, which is not performed in the BPP or EPP, will be described. As described above, in rapid charge mode, the TX100 transmits more power to the RX200 than in the BPP or EPP. Therefore, the following issues arise in rapid charge mode. The noise leaking from the power transmitting (receiving) antenna to the surrounding area is greater than when BPP or EPP is operating. -High speed and stable communication is required compared to when BPP or EPP is running. -Fault detection accuracy is lower than when BPP or EPP is in 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 surrounding area> As a first method for suppressing noise leakage from the transmitting and receiving antennas to the surrounding area, we will describe a method in which the TX100 changes the power transmitted from the TX100 to the RX200 according to the coupling index of the transmitting and receiving antennas. First, we will explain a method in which the TX100 reduces the power transmitted to the RX200 according to the coupling index of the transmitting and receiving antennas. The TX100 and RX200 measure / calculate the coupling index of the transmitting and receiving antennas. When the coupling index of the transmitting and receiving antennas is smaller (weak) than a predetermined threshold, this is referred to as a weak coupling state. When the coupling index of the transmitting and receiving antennas is larger (strong) than a predetermined threshold, this is referred to as a strong coupling state.

[0279] When the TX100 and RX200 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 TX100 can also be a noise source. Therefore, by reducing the transmission power, it is possible to suppress noise leaking into the surroundings from the transmitting antenna and the receiving antenna. The control unit 101 of the TX100 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 the GP in the renegotiation phase. The RX200 transmits Requested Load Power information to the TX100. 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 is the 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 TX100 has a Potential Load Power value or a Negotiable Load Power value in advance. Potential Load Power is the maximum load power value (Highest Load Power Level) that the TX100 can negotiate and that can be output (supplied) to the load of the RX200. Negotiable Load Power is the maximum load power value (Highest Load Power Level) that the TX100 can negotiate and that can be output (supplied) to the load of the RX200 during a specified period or under specified conditions. Negotiation is successful when the Requested Load Power value is smaller than the Negotiable Load Power value. The TX100 and RX200 set the Requested Load Power value as the GP value and store it in memory. In other words, the TX100 receives the Requested Load Power value from the RX200, and if that value is smaller than the Negotiable Load Power value, it sends an acknowledgement ACK to the RX200. The TX100 and RX200 set the Requested Load Power value as the GP value and store it in memory.

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

[0283] By setting the GP value to a predetermined value or less, the transmission power of the TX100 can be reduced, and the received power of the RX200 can also be reduced. To achieve this, the TX100 sets the Potential Load Power or Negotiable Load Power to a predetermined value or less. Alternatively, the RX200 sets the Requested Load Power value to a predetermined value or less. Note that the above control may be performed in the negotiation phase. Furthermore, the TX100 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 TX100 and RX200 behave as if they recognize that they are in a weakly coupled state. On the other hand, if a foreign object (such as a metal piece) 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. This section describes the behavior 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 RX200 calculate (measure) the coupling state index using the above-mentioned 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, the TX100 and RX200 recognize that they are in a strongly coupled state. When it is recognized that the TX100 and RX200 are in a strongly coupled state, control is performed to increase the transmission power of the TX100 (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 (increase the received power of the RX200).

[0286] To achieve this, the TX100 sets the Potential Load Power or Negotiable Load Power to a predetermined value or higher. Alternatively, the RX200 sets the value of Requested Load Power to a predetermined value or higher. Note that the above control may be performed in the negotiation phase or renegotiation phase. Furthermore, the TX100 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 RX200 calculates (measures) a coupling status indicator using the above-described coupling status indicator measurement method at a predetermined timing, and compares the calculated coupling status indicator 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, it occurs when the RX200 receives a predetermined packet from the TX100. The TX100 or RX200 may control the transmission power using the above-described method depending on the result of the coupling status determination.

[0288] Next, we will explain a second method for suppressing noise leakage from the power transmitting antenna and the power receiving antenna to the surroundings, which involves the TX100 changing the frequency band of the transmitting wave. Noise occurs in the frequency band used to transmit power from the power transmitting antenna to the power receiving antenna (hereinafter referred to as the operating frequency band). Note that, in this specification, the term "operating frequency band" may be interpreted as "operating frequency." Harmonic noise also occurs in frequency bands higher than the operating frequency band. If another system uses the frequency band in which noise occurs, it may cause malfunction in that system. Therefore, when operating in fast charging mode, the TX100 and RX200 control the operating frequency band to change from a first frequency band to a second frequency band. By changing the frequency band of the noise leaking from the power transmitting antenna and the power receiving antenna to the surroundings, it is possible to 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 RX200 recognize that they are operating in fast charging 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, we will explain a third method for suppressing noise leaking from the power transmitting antenna and the power receiving antenna to the surrounding area, which is a method using a noise suppression circuit. The TX100 or RX200 has a noise suppression circuit. For example, the noise suppression circuit is mounted on the circuit board of the TX100 and is composed of 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 RX200 and is composed of 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 TX100, and the frequency band of the generated noise is determined depending on the frequency band used. Therefore, the TX100 or RX200 has a noise suppression circuit for each frequency band used. When operating in fast charging mode, the TX100 and RX200 change the operating frequency band from a first frequency band to a second frequency band and perform noise suppression control by switching to a noise suppression circuit that corresponds to the changed operating frequency band.

[0290] Next, as a fourth method for suppressing noise leaking into the surroundings from the transmitting antenna and the receiving antenna, a method for changing the parameters of the frequency shift keying used by the TX100 for communication with the RX200 will be described. Also, a method for changing the parameters of the load modulation, amplitude modulation, or backscatter modulation used by the RX200 for communication with the TX100 will be described.

[0291] In communication for transmitting information from the TX100 to the RX200, the first communication unit 104 of the TX100 performs frequency shift keying of the electromagnetic waves output from the power transmitting antenna 105. At that time, the TX100 changes the frequency of the carrier wave (power transmitting waveform) to transmit information. When using two frequencies, the TX100 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 TX100 performs transmission (power transmission) while switching between the two frequencies, and transmits information to the RX200.

[0292] The TX 100 also switches the carrier frequency 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 the modulation index (frequency shift, modulation depth), which represents the magnitude (absolute value) of the difference between fmod and fop. The larger the modulation index, the greater the difference between fmod and fop. As a result, the bandwidth of specific frequency band noise leaking into the surrounding area from the transmitting and receiving antennas becomes wider. When the TX100 and RX200 operate in fast charging mode, there is a possibility that strong noise will be generated 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 RX200 operate in fast charging mode, the polarity is controlled to be negative (positive). Changing the polarity allows the frequency band used for communication to be controlled. This makes it possible to suppress noise in specific frequency bands leaking into the surrounding area from the transmitting and receiving antennas.

[0296] Additionally, when the TX100 and RX200 operate in fast charge mode, they control the modulation index (frequency shift, modulation degree, depth) to be smaller. This reduces the difference between fmod and fop, making it possible to narrow the bandwidth of specific frequency band noise leaking from the transmitting and receiving antennas to the surrounding area.

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

[0298] The packet used by the RX200 to transmit the values ​​of the first and second parameters to the TX100 is a Signal Strength Data packet or an Identification Data packet. Alternatively, it may be an Extended Identification Data packet. Alternatively, it may be packets in the calibration phase or power transfer phase, i.e., RP1, RP2, or RP0. Hereinafter, these packets are collectively referred to as "predetermined packets."

[0299] Next, a method for changing parameters of load modulation, amplitude modulation, or backscatter modulation used when the RX200 performs communication to transmit information to the TX100 will be described. The first communication unit 204 of the RX200 performs load modulation, amplitude modulation, or backscatter modulation of the electromagnetic wave output from the power transmitting antenna 105 of the TX100, and transmits information to the TX100 for communication. At this time, the RX200 changes the amplitude of the carrier wave (power transmission waveform) to transmit the information. When using two amplitude magnitudes, the RX200 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 RX200 transmits information to the TX100 by superimposing a signal on the power transmission waveform while switching the amplitude magnitude.

[0300] The RX200 switches the amplitude of the carrier wave between the following two amplitudes to transmit information to the TX100. Amplitude Amp_A in Hi-State (relatively large amplitude) Amplitude Amp_B in Low-State (relatively small amplitude)

[0301] The difference between Amp_A and Amp_B is called the modulation depth. The greater the modulation depth, the greater the carrier frequency change, and the wider the bandwidth of the specific frequency band noise 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 during communication from the RX200 to the TX100. More specifically, the modulation depth is controlled to be smaller, which reduces the difference between the amplitude Amp_A and the amplitude Amp_B. This makes it possible to narrow the bandwidth of the specific frequency band noise leaking from the transmitting antenna and the receiving antenna to the surroundings.

[0302] When performing the above processing, the RX200 may notify the TX100 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 transmitted by the RX200 in the Configuration phase. When operating in fast charge mode, the RX200 sets the parameter (modulation factor) value related to load modulation, amplitude modulation, or backscatter modulation in the Configuration Data Packet to a predetermined value and transmits the packet to the TX100. The TX100 controls the transmission wave shape based on the parameter (modulation factor) value related to load modulation, amplitude modulation, or backscatter modulation contained in the received packet. Note that the packet used by the RX200 to transmit information on the parameter (modulation factor) related to load modulation, amplitude modulation, or backscatter modulation to the TX100 may be the above-mentioned predetermined packet.

[0303] Next, we will explain a fifth method for suppressing noise leakage from the transmitting and receiving antennas to the surrounding area, which involves changing the modulation method for communication from TX to RX and from RX to TX. An example of a modulation method is the spread spectrum method, in which communication is performed using signals with a wide frequency band that exceeds the frequency band required for information transmission. Specifically, the first method is the direct sequence spread spectrum (DSSS) method.

[0304] For example, when operating in the fast charge mode, the first communication unit 104 of the TX100 performs arithmetic processing on the original signal that has been frequency-shift modulated 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 TX100 transmits the processed signal to the RX200. The RX200 stores data of the spreading signal used by the TX100 for the arithmetic processing in advance in the memory 208. The RX200 performs an inverse conversion on the received signal using the spreading signal to obtain the original signal that has been frequency-shift modulated. Furthermore, when the RX200 recognizes that the TX100 and the RX200 are operating in the fast charge mode during transmission from the RX200 to the TX100, the following processing is performed. That is, the first communication unit 204 of the RX200 performs arithmetic processing on the original signal that has been load-modulated, amplitude-modulated, or backscatter-modulated using the spreading signal. The RX200 transmits the processed signal to the TX100. The TX100 stores in advance in the memory 106 the data of the spreading signal used by the RX200 for calculation processing. The TX100 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 surrounding area from the transmitting antenna and the receiving antenna.

[0305] The second method is the frequency hopping spread spectrum (FHSS). This method divides the frequency band allocated for communication into multiple frequency slots, and the frequency slots used for communication are rapidly switched over in a short period of time according to a frequency switching pattern. In other words, transmission is carried out 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 TX100 and RX200 can receive signals from each frequency band according to a pre-determined hopping sequence and retrieve the original signal.

[0306] For example, when transmitting from TX100 to RX200, if TX100 and RX200 are operating 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 TX100 transmits the processed signal to the RX200. The RX200 stores in advance in memory 208 the data of the hopping sequence used by the TX100 for processing. The RX200 performs an inverse transformation on the received signal according to the hopping sequence to obtain the original frequency-shift keyed signal. When operating in fast charge mode, the first communication unit 204 of the RX200 transmits the original load-modulated, amplitude-modulated, or backscatter-modulated signal using a frequency slot according to the hopping sequence. The RX200 transmits the processed signal to the TX100. The TX100 stores in advance in memory 106 the data of the hopping sequence used by the RX200 for processing. The TX100 performs an inverse transformation on the received signal according to the hopping sequence to obtain the original load-modulated, amplitude-modulated, or backscatter-modulated signal. Using the second method makes it possible to reduce the level of noise in a specific frequency band leaking into the surrounding area from the transmitting and receiving antennas.

[0308] The third method is a method that performs direct sequence spread spectrum processing and then frequency hopping processing. By combining these two methods, it is possible to further reduce the noise level in specific frequency bands that leaks into the surrounding area from the transmitting antenna and receiving antenna.

[0309] 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 Configuration Data Packet transmitted by the RX200 in the Configuration phase. When the TX100 and RX200 operate in fast 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 RX200 do not operate in fast charge mode, it stores “0” in the field because none of the first to third methods are used. Alternatively, information indicating whether or not the RX200 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 RX200, the TX100 transmits information to the RX200 and receives information from the RX200 based on the modulation method information in the packet. Note that the packet used by the RX200 to transmit to the TX100 information indicating which of the first to third methods to use or which method is supported may be the above-mentioned 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 TX100. For example, the TX100 stores data (e.g., "1") indicating the use of one of the first to third methods in a predetermined field in the Power Transmitter Capabilities (CAP) Data Packet. Similarly, when using the Power Transmitter Identification (ID) Data Packet, 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 corresponding field when the first method is used, "2" is stored when the second method is used, and "3" is stored when the third method is used. When the TX100 and 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 corresponding field. Alternatively, information indicating whether the TX100 supports each of the first to third methods is stored in a specified 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 Power Transmitter ID Data Packet, the RX200 transmits and receives information to the TX100 according to the modulation method specified in the packet.

[0311] When performing the above processing, the RX200 may notify the TX100 of the modulation method to be used in advance using 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 RX200 operate in 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 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 about 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 RX200 operate in 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 about the modulation method to be used by the TX100 that is included in the received packet.

[0313] In the above-described method, the RX200 notifies the TX100 of information about the modulation method to be used by a predetermined packet in advance. Then, the 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, the TX100 notifies the RX200 of information about the modulation method to be used by a predetermined packet in advance. Then, the 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, we will explain a sixth method for suppressing noise leakage from the transmitting and receiving antennas to the surrounding area, in which the TX100 switches the transmitting antenna (power transmitting coil). When the TX100 and RX200 are operating in fast charging mode, the TX100 transmits high power to the RX200, resulting in increased noise leakage to the surrounding area. Another cause of increased noise is the large difference in size between the transmitting and receiving antennas. For example, consider a case where the transmitting antenna is larger than the receiving antenna. In this case, because the receiving antenna is relatively small, some of the magnetic flux generated from the transmitting antenna does not penetrate the inside of the receiving antenna when transmitting power from the TX100 to the RX200. The greater the difference in size between the transmitting and receiving antennas, 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 status index between the transmitting antenna and the receiving antenna using the method described above, compares it with the threshold, and determines that the coupling is weak. In this case, the TX100 selects the small transmitting antenna. Then, using the method described above, the TX100 measures / calculates the coupling status index between the transmitting antenna and the receiving antenna, and again compares it with the threshold to determine whether the coupling is weak. As a result of the determination, assume 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 first selects the small transmitting antenna, measures / calculates the coupling status index between the transmitting antenna and the receiving antenna using the method described above, compares it with a threshold, and determines that the coupling is weak. In this case, the TX100 selects the large transmitting antenna. Then, using the method described above, the TX100 measures / calculates the coupling status index between the transmitting antenna and the receiving antenna, compares it with a threshold, and determines again whether the coupling 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 TX100 may have three or more transmitting antennas of different sizes. The TX100 measures and determines the coupling state between the transmitting antenna and the receiving antenna when each transmitting antenna is used. In each subsequent phase, the TX100 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 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 for modifying the circuit to increase the quality factor of the power transmission circuit, 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 coefficient, Q value). When the TX100 and the RX200 operate in fast charging mode, a decrease in transmission efficiency can be suppressed by controlling the quality factor to increase. 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 power transmission circuit, 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 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 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 using a predetermined packet.

[0321] <Communication> Next, we will explain a first method for preventing communication between the TX100 and RX200 from becoming unstable. When the TX100 and RX200 operate in fast charge mode, they need to perform rapid control to improve transmission efficiency. Therefore, stable communication is required for the control between the TX100 and RX200. Therefore, we will explain methods for stabilizing communication. Specifically, we will explain a first change method that changes the parameters of the frequency shift keying used to transmit signals from the TX100, and a second change method that changes the parameters of the load modulation, amplitude modulation, or backscatter modulation used to transmit signals from the RX200.

[0322] First, in the first modification method, the parameter of frequency shift keying is the modulation index (frequency shift, modulation 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 RX200 operate in fast charge mode, the TX100 and 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 RX200 operate in fast charge mode, the modulation index is controlled to be larger than 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 a configuration data packet that the RX200 transmits in the configuration phase. When the RX200 recognizes that the TX100 and RX200 are operating in fast charge mode, it sets the modulation index in the configuration data packet to a predetermined value and transmits the packet to the TX100. The TX100 transmits information from the TX100 to the RX200 based on the modulation index included in the received packet. The packet that the RX200 uses to transmit modulation index information to the TX100 may be the predetermined packet.

[0324] Next, the 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 greater 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 fast 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 fast 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 high-state state and the amplitude Amp_B in the low-state state, making it easier for the TX100 to demodulate the signal transmitted by the RX200.

[0325] When executing the above process, the RX200 may notify the TX100 in advance of the modulation factor to be used in a predetermined packet. This is as described above, and the same applies to the predetermined packet used to transmit the modulation factor, so a description 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 preventing communication between the TX100 and the RX200 from becoming unstable) will be described. To enable high-speed control between the TX100 and the RX200, the communication between the TX100 and the RX200 needs to be faster. Therefore, when the TX100 and the RX200 recognize that they are operating in quick charge mode, they perform control to change the communication method. 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 this communication method 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 RX200 communicates with the TX100 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 TX100 and the RX200 operate in the quick charge mode, the TX100 and the RX200 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 indicating whether or not it 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 based on a standard other than the WPC standard will be used in the Configuration Data Packet. For example, when the RX200 recognizes that it will operate in fast charge mode, it stores data (e.g., "1") indicating that it will use a communication method based on a standard other than the WPC standard in a predetermined field in the Configuration Data Packet. Alternatively, "1" corresponding to the use of wireless LAN or "2" corresponding to the use of BLE is stored in that field. Furthermore, "3" corresponding to the use of NFC is stored in that field. Furthermore, when the TX100 and RX200 do not operate in fast charge mode, that is, when they operate 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 that field. Alternatively, information indicating whether or not the RX200 supports each communication method is stored in a predetermined field. If the communication method is supported, the data stored in the field is "1," and if the method is not supported, the data stored in the field is "0." The RX200 sends the packet to the TX100.

[0328] Based on the communication method information contained in the received Configuration Data Packet, the TX100 transmits information to the RX200. Note that the packet used by the RX200 to transmit to the TX100 information on whether or not the TX200 supports a communication method based on a standard other than the WPC standard may be the above-mentioned specified packet.

[0329] When executing the above processing, the RX200 may notify the TX100 of the communication method to be used in advance using a predetermined packet. For example, information about the communication 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 fast charge mode, it 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 the 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 above-mentioned predetermined packet.

[0330] The TX100 can include in a predetermined packet information indicating whether or not a communication method based on a standard other than the WPC standard is supported, or data indicating which communication method of the communication methods based on standards other than the WPC standard will be used. For example, if the TX100 recognizes that the TX100 and the RX200 are operating in fast 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 that field. Furthermore, "3" corresponding to the use of NFC is stored in that field. Furthermore, if the TX100 and the RX200 are not operating in fast charge mode, that is, if they are 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 that field. The TX100 transmits the packet to the RX200. Alternatively, the TX100 stores information indicating whether or not each communication method is supported by the TX100 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. The RX200 transmits information to the TX100 based on the communication method information contained in the received packet.

[0331] When executing the above process, the TX100 may notify the RX200 of the communication method to be used in advance by a predetermined packet. When the TX100 recognizes that the TX100 and the RX200 operate in the quick charge mode, the TX100 sets a predetermined value in a field in the packet indicating the communication method to be used by the TX100, and transmits the packet to the RX200.

[0332] The RX200 determines the communication method based on the information about the communication method used by the TX100, which is included in the received packet.

[0333] <Foreign object detection accuracy> Next, we will explain the first method for improving the accuracy of detecting foreign objects present between the TX100 and RX200. When the TX100 and RX200 operate in fast charge mode, the accuracy of foreign object detection using the Q-factor measurement method and power loss method specified in the WPC standard may decrease. Therefore, when the TX100 and RX200 operate in fast charge mode, they 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 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. A method for setting a threshold value for determining the possibility of the presence or absence of a foreign object has also 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 high 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 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 has been 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 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 the predetermined foreign object detection process. The predetermined foreign object detection process is 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 RX200, the TX100 executes the predetermined foreign object detection process 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 RX200 transmits a packet to the TX100 requesting that power transmission be limited. For example, this packet could be a packet requesting that the GP value be set to a low value, or an RP1 or RP2 packet requesting re-execution of the power loss method CAL process. Alternatively, this packet could be a packet requesting re-execution of the waveform attenuation method or the coupling status indicator measurement method CAL process. Alternatively, this packet could be an EPT packet requesting the suspension of power transmission.

[0336] The TX100 then executes the predetermined foreign object detection process described above, and notifies the RX200 of the result of the determination. If the result of the determination is "highly likely that a foreign object exists" or "foreign object exists," the RX200 transmits a packet to the TX100 requesting that the TX100 execute foreign object detection based on the coupling state between the power transmitting antenna and the power receiving antenna. Upon receiving the packet, the TX100 executes foreign object detection based on the coupling state between the power transmitting antenna and the power receiving antenna, and notifies the RX200 of the result of the determination. If the result of the determination is "highly likely that a foreign object exists" or "foreign object exists," the RX200 transmits a packet to the TX100 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 status indicator between the power transmitting antenna and the power receiving antenna, the RX200 executes the foreign object detection process and obtains the 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 RX200 notifies the TX100 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 that the TX100 execute 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. The TX100 executes the predetermined foreign object detection process in response to the request from the RX200 and 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 that the TX100 limit power transmission. For example, the packet may be a packet requesting that the GP value be set to a low value, or RP1 or RP2 requesting a retry of CAL processing using the power loss method, or a packet requesting a retry of CAL processing using the waveform decay method or the coupling status indicator measurement method, or an EPT packet requesting the suspension of power transmission.

[0338] The RX200 then executes the predetermined foreign object detection process described above, and notifies the TX100 of the result of the determination. If the result of the determination is "highly likely that a foreign object exists" or "foreign object exists," the RX200 transmits a packet to the TX100 notifying it of the execution of foreign object detection based on the coupling state between the power transmitting antenna and the power receiving antenna. After transmitting the packet, the RX200 executes foreign object detection based on the coupling state between the power transmitting antenna and the power receiving antenna, and notifies the TX100 of the result of the determination. If the result of the determination is "highly likely that a foreign object exists" or "foreign object exists," the RX200 transmits a packet to the TX100 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 power transmitting antenna and the power 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 power transmitting antenna and the power 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 power transmitting antenna and the power 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 status 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 status 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 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 RX200 performs foreign object detection processing using the waveform attenuation method. Alternatively, upon receiving the predetermined packet, the TX100 or 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 foreign objects present between the TX100 and the RX200 will be described, which involves detecting foreign objects based on the temperature of the TX100 or the RX200. The TX100 and the RX200 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. This makes it possible to detect foreign objects present between the TX100 and the RX200 with higher accuracy.

[0342] When the TX100 or RX200 recognizes that the TX100 and RX200 are operating in fast charge mode, the TX100 or RX200 executes foreign object detection processing based on the detected temperature. The TX100 acquires the detected value of 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 of the temperature sensor is greater than a predetermined threshold, the TX100 determines that there is a high possibility that a foreign object is present. The TX100 also calculates the 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 there is a high possibility that a foreign object is present. The RX200 is notified of this determination result in a predetermined packet. Alternatively, when this determination result is acquired, the TX100 performs the control to limit the transmitted power (reduce power) or stop power transmission as described above. These controls have already been explained, so they will not be described here.

[0343] Next, the foreign object detection process based on the temperature of the RX200 will be described. The RX200 acquires the detected value of the temperature sensor at a predetermined timing. The predetermined timing occurs at a predetermined cycle or when a predetermined packet is received from the TX100. If the detected value of the temperature sensor is greater than a predetermined threshold, the RX200 determines that there is a high possibility that a foreign object is present. The RX200 also calculates the 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 RX200 determines that there is a high possibility that a foreign object is present. The RX200 notifies the TX100 of the result of this determination in a predetermined packet. Alternatively, when the result of this determination is acquired, the RX200 transmits a predetermined packet to the TX100 to perform the process of requesting the aforementioned limiting of the transmitted power (reducing power) or stopping power transmission.

[0344] As described above, 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 performs more accurate foreign object detection based on the measurement results. 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 performs the temperature-based foreign object detection process, the TX100 performs the temperature-based foreign object detection process and notifies the RX200 of the foreign object determination result. If the determination result is "high probability of foreign object presence" or "foreign object presence," the RX200 notifies the TX100 of a packet requesting the execution of foreign object detection process based on one or more of the Q-factor measurement method, the power loss method, and the waveform attenuation method. In response to the request from the RX200, the TX100 performs the specified foreign object detection process and notifies the RX200 of the determination result. If the result of the foreign object detection process is "high possibility of foreign object presence" or "foreign object present," the RX200 transmits a packet to the TX100 requesting that power transmission be limited. This packet may be, for example, a packet requesting that the GP value be set to a low value, or an RP1 or RP2 packet requesting that calibration using the power loss method be performed again. Alternatively, this packet may be a packet requesting that calibration using the waveform attenuation method or calibration using the coupling status indicator measurement method be performed again. Alternatively, this packet may be an EPT packet requesting that power transmission be stop...

Claims

1. 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:

2. 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 .

3. 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. The power receiving device according to claim 1 .

4. 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 .

5. 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 claim 1 .

6. 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 .

7. 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 transmitted power compared to when the first communication method is used. The power receiving device according to claim 1 .

8. 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 .

9. 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 claim 1 .

10. 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 claim 1 .

11. 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 claim 1 .

12. 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 claim 1 .

13. 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 claim 1 .

14. 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.

15. 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:

16. 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.

17. A program causing a computer to execute the steps according to claim 14 or 16.

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