WO2024095593A1

WO2024095593A1 - Power-transmitting device, power-receiving device, wireless power transfer system, method for controlling wireless power transmission, and storage medium

Info

Publication number: WO2024095593A1
Application number: PCT/JP2023/031900
Authority: WO
Inventors: 元志村
Original assignee: キヤノン株式会社
Priority date: 2022-11-02
Filing date: 2023-08-31
Publication date: 2024-05-10

Abstract

In order to provide technology that, in a power-transmitting device having a plurality of power-transmitting coils, controls a processing period pertaining to measurement processing executed during a period in which power transmission to a power-receiving device is limited, this power-transmitting device 100 wirelessly transmits power to a power-receiving device 200 using a plurality of power-transmitting coils 105. The power-receiving device 200 is capable of receiving power via a power-receiving coil 205. The power-transmitting device 100 measures voltage or current in the power-transmitting coils 105 at two or more points in time when power transmission to the power-receiving device 200 is stopped or during a power transmission restriction period in which the transmitted power is reduced. When a request to execute a foreign object detection process is received from the power-receiving device 200, the power-transmitting device 100 sets the processing period during which measurement processing is performed for a plurality of selected power-transmitting coils 105 for each power-transmitting coil on the basis of time information pertaining to the processing period, the time information being received from the power-receiving device 200.

Description

POWER TRANSMITTING APPARATUS, POWER RECEIVING APPARATUS, WIRELESS POWER TRANSMISSION SYSTEM, CONTROL METHOD FOR WIRELESS POWER TRANSMISSION, AND STORAGE MEDIUM

The present disclosure relates to a power transmission device capable of wireless power transmission, a power receiving device, a wireless power transmission system, a control method for wireless power transmission, a storage medium, etc.

The standard (hereinafter referred to as the WPC standard) established by the Wireless Power Consortium, a standardization organization for wireless charging, is known. Patent Document 1 discloses a method for foreign object detection in the WPC standard.

Patent Document 2 discloses a method for determining whether or not an object is present near a power transmitter based on the amount of attenuation of the power transmitter's voltage value during the period in which the power transmitter's voltage gradually decreases after power transmission is stopped. Patent Document 3 discloses a method for determining the presence or absence of a foreign object in a wireless power transmission device having multiple coils by using information on the quality factor obtained from each coil.

JP 2017-70074 A JP 2018-512036 A JP 2020-114170 A

In the power transmission device disclosed in Patent Document 3, the method described in Patent Document 2 is applied to assume a process for determining the presence or absence of a foreign object. The power transmission device performs a process for measuring voltage or current during a period in which power transmission is restricted in multiple power transmission coils. In this case, the power transmission device needs to appropriately control the period related to the measurement process, but the conventional technology does not take into account the period related to the measurement process performed in multiple power transmission coils.

The present disclosure aims to provide a technology for controlling the processing period for measurement processing executed during a period in which power transmission to a power receiving device is restricted in a power transmitting device having multiple power transmitting coils.

The power transmission device disclosed herein includes a power transmission means for wirelessly transmitting power to a power receiving device using multiple power transmission coils, a communication means for communicating with the power receiving device, a measurement means for measuring the voltage or current related to the power transmission coils or the voltage and current, and a control means for limiting the power transmission from the power transmission means to the power receiving device by controlling the power transmission performed by the power transmission means using a power transmission coil selected from the multiple power transmission coils. When the communication means receives from the power receiving device a request to execute a detection process for an object different from the power receiving device, the control means controls to limit the power transmission to the selected multiple power transmission coils, and sets the processing period related to the measurement process performed by the measurement means for each of the power transmission coils based on information on the processing period determined by the power receiving device for each of the power transmission coils.

The present disclosure provides a technology for controlling the processing period for measurement processing executed during a period in which power transmission to a power receiving device is restricted in a power transmitting device having multiple power transmitting coils.

1 is a diagram illustrating an example of the configuration of a wireless power transmission system according to a first embodiment. 1 is a functional block diagram illustrating a configuration example of a power transmitting device according to a first embodiment. FIG. 2 is a diagram illustrating an example of the configuration of a power receiving device according to the first embodiment. This is an explanatory diagram of a method for setting thresholds in state detection using the Power Loss method. 5A and 5B are explanatory diagrams of a Q-factor measurement method according to the first embodiment. 4 is a block diagram showing an example of a functional configuration of a control unit of a power transmitting device according to the first embodiment. FIG. 5 is a flowchart illustrating a process of the power transmitting device according to the first embodiment. 5 is a flowchart illustrating processing of a power receiving device according to the first embodiment. 5A to 5C are explanatory diagrams of state detection using a waveform attenuation method according to the first embodiment. FIG. 4 is an explanatory diagram of a detection processing period using a waveform attenuation method according to the first embodiment. 5 is an explanatory diagram of a threshold setting method in state detection using a waveform attenuation method according to the first embodiment; FIG. 4A and 4B are diagrams illustrating a method for measuring a coupling state indicator between a power transmitting antenna and a power receiving antenna according to the first embodiment. 4 is an explanatory diagram of a threshold setting method in state detection by a bonding state indicator measurement method according to the first embodiment. FIG. 1A and 1B are schematic diagrams illustrating a power transmitting device and a power receiving device according to a first embodiment. 5 is a flowchart illustrating a process of the power transmitting device in the first embodiment. 5 is a flowchart illustrating processing of a power receiving device in the first embodiment. 4 is a sequence diagram illustrating an example of processing by a power transmitting device and a power receiving device according to the first embodiment. FIG. 5 is a flowchart illustrating a process of the power transmitting device in the first embodiment. 5 is a flowchart illustrating a process of a power receiving device in the first embodiment. 10 is a sequence diagram illustrating another example of processing by the power transmitting device and the power receiving device according to the first embodiment. FIG. 10 is a flowchart illustrating a process of a power transmitting device according to a second embodiment. 10 is a flowchart illustrating a process of a power receiving device according to a second embodiment.

Below, an embodiment of the present disclosure will be described in detail with reference to the attached drawings. In the embodiment, a wireless charging system to which a wireless power transmission system is applied is shown. As an example, wireless power transmission based on the WPC standard will be described.

[First embodiment]
Fig. 1 is a diagram showing an example of the configuration of a wireless charging system according to a first embodiment. This system includes a power transmitting device 100, a power receiving device 200, and a charging stand 300. In the following, for the sake of simplicity, the power receiving device 200 may be referred to as RX and the power transmitting device 100 as TX. The detailed configurations of TX and RX will be described later with reference to Figs. 2 and 3.

RX is an electronic device that receives power from TX and charges its built-in battery while placed on the charging stand 300. TX is an electronic device that transmits power wirelessly to RX placed on the charging stand 300.

Because the charging stand 300 constitutes a part of the TX, hereinafter, when the RX is "placed on the charging stand 300," it may be said that the RX is "placed on the TX." The spatial range in which the RX can receive power from the TX is shown diagrammatically within the dotted line frame 400 in Figure 1.

RX and TX may have the functionality to execute applications other than the wireless charging function. For example, RX is a smartphone and TX is an accessory device for charging the battery of the smartphone.

With reference to FIG. 2, an example of the configuration of the power transmission device 100 will be described. FIG. 2 is a functional block diagram showing an example of the configuration of the power transmission device 100 (TX) according to the first embodiment. The TX has a control unit 101, a power supply unit 102, a power transmission unit 103, a first communication unit 104, a power transmission antenna (power transmission coil) 105, a memory 106, a resonant capacitor 107, and a switch unit 108.

The TX also has a second communication unit 109 and a user interface (hereinafter referred to as UI) unit 110. Note that although each functional block element is shown as a separate entity in FIG. 2 (and FIG. 3), any number of functional block elements may be implemented within the same chip.

The power transmission device 100 has multiple power transmission units 103. In this embodiment, an example is shown in which the TX has three

power transmission units

103a, 103b, and 103c. The power transmission device 100 also has multiple first communication units 104.

In this embodiment, an example is shown in which the TX has three

first communication units

104a, 104b, and 104c. The

first communication units

104a, 104b, and 104c are connected to the corresponding

power transmission units

103a, 103b, and 103c, respectively. In this embodiment, all three power transmission units 103 (or first communication units 104) have the same characteristics, but they may each have different characteristics.

The power transmission device 100 has N

power transmission antennas

105a, 105b, ... 105n. The power transmission device 100 also has N

resonant capacitors

107a, 107b, ... 107n. The power transmission device 100 also has

N switch units

108a, 108b, ... 108n.

Each power transmission antenna, resonant capacitor, and switch unit has the same alphabet attached to its reference number, forming a pair. For example, power transmission antenna 105a, resonant capacitor 107a, and switch unit 108a form a pair.

The power transmitting antenna 105a and the resonant capacitor 107a are connected in series, and the switch unit 108a is connected in parallel to the power transmitting antenna 105a and the resonant capacitor 107a. In this embodiment, all N power transmitting antennas 105 (or resonant capacitors 107, or switch units 108) have the same characteristics, but they may each have different characteristics.

The control unit 101 controls the entire TX 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. Furthermore, the control unit 101 can control the execution of applications other than wireless power transmission.

The control unit 101 includes one or more processors, such as a CPU (Central Processing Unit) or an MPU (Microprocessor Unit). Alternatively, the control unit 101 may be configured with hardware, such as an application specific integrated circuit (ASIC).

The control unit 101 may also be configured to include an array circuit such as an FPGA (Field Programmable Gate Array) compiled to execute a specified process. The control unit 101 can execute a process of storing information to be stored in the memory 106 during execution of various processes, and a time measurement process using a timer (not shown).

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.

The power transmission unit 103 converts the DC or AC power input from the power supply unit 102 into AC power in the frequency band used for wireless power transmission, and inputs the AC power to the power transmission antenna 105, thereby generating electromagnetic waves for the RX to receive power.

For example, the power transmission 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 transmission 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.

The power transmitting unit 103 controls the intensity of the electromagnetic waves (transmission power) to be output by adjusting the voltage (transmission voltage) or current (transmission current), or both, input to the power transmitting antenna 105. The strength of the electromagnetic waves (corresponding to the strength of the transmission power, hereinafter also referred to as the intensity) is controlled by the magnitude of the transmission voltage or the transmission current.

For example, if the power transmission unit 103 has an inverter, the intensity of the electromagnetic waves to be output is controlled by adjusting the voltage or current, or both, input to the inverter. Alternatively, the intensity of the electromagnetic waves to be output is controlled by adjusting the voltage or current, or both, output from the inverter included in the power transmission unit 103.

The control unit 101 controls the start and stop of power transmission by issuing instructions to the power transmission unit 103, and also controls the intensity of the electromagnetic waves to be output. Based on an instruction signal from the control unit 101, the power transmission unit 103 performs output control related to the power of the AC frequency electromagnetic waves so that the start or stop of power transmission by the power transmission antenna 105 or the intensity of the electromagnetic waves to be output is controlled.

Furthermore, the power transmitting unit 103 is assumed to have a power supply capacity sufficient to output 15 watts (W) of power to the charging unit (206 in FIG. 3) of the power receiving device 200 that complies with the WPC standard.

The first communication unit 104 is connected to the control unit 101 and the power transmission unit 103, and communicates with the RX 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 transmission antenna 105, and transmits information to the RX to perform communication.

The first communication unit 104 also demodulates the electromagnetic waves transmitted from the power transmitting antenna 105 that were modulated by the RX, and acquires the information transmitted by the RX. 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.

In addition to the control program, the memory 106 can store information about the TX and RX states. Information about the TX and RX states includes the transmitted power value and the received power value. Information about the TX state is acquired by the control unit 101. Information about the RX state is acquired by the RX control unit (201 in FIG. 3) and can be received by the first communication unit 104 or the second communication unit 109.

The switch unit 108 is connected in parallel to the series circuit of the resonant capacitor 107 and the power transmitting antenna 105. The control unit 101 transmits a control signal to the switch unit 108 via the selection unit 111, which will be described later, to control its ON/OFF state. The power transmitting antenna 105 is connected to the resonant capacitor 107.

When the switch unit 108 is turned on and short-circuited by a control signal from the control unit 101, 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 switch unit 108 is turned OFF by a control signal from the control unit 101 and the circuit is opened, power is supplied from the power transmission unit 103 to the power transmission antenna 105 and the resonant capacitor 107.

The second communication unit 109 is connected to the control unit 101, and communicates with the RX using a standard different from the WPC standard. For example, the second communication unit 109 communicates with the RX (the second communication unit 212 in FIG. 3) using an antenna different from the power transmission antenna 105.

Examples of communication using standards different from the WPC standard include wireless LAN (Local Area Network), Bluetooth (registered trademark) Low Energy (BLE), and NFC (Near Field Communication). The frequency band used by the power transmitting antenna 105 to transmit power is different from the frequency band used by the second communication unit 109 for communication.

Regarding communication between TX and RX, TX may selectively use one of multiple communication standards to communicate with RX. The following communication formats are possible:

- Communication based on the first standard (WPC standard) between the first communication unit 104 of the TX and the first communication unit 204 of the RX (Figure 3).

- Communication based on a second standard (a standard other than the WPC standard) between the second communication unit 109 of the TX and the second communication unit 212 of the RX (Figure 3).

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 TX main unit, and other operations. The UI unit 110 is realized by an LCD panel, a speaker, a vibration motor, etc.

The selection unit 111 connects each of the

power transmission units

103a, 103b, and 103c to one of the power transmission antennas 105 (power transmission antennas 105a to 105n). The selection unit 111 connects the power transmission unit 103 (103a, 103b, or 103c) to any one or more power transmission antennas.

The control unit 101 controls the selection unit 111 to determine which of the power transmission antennas 105a to 105n each power transmission unit should be connected to. The selection unit 111 switches the connection between the power transmission unit 103 and the power transmission antenna 105 in accordance with a control signal from the control unit 101.

In the example of FIG. 2, a configuration having three power transmission units 103 and three first communication units 104 is shown. Without being limited to this example, the power transmission device may have one power transmission unit 103 and one first communication unit 104. In this case, one power transmission unit 103 is connected to any one or multiple power transmission antennas 105 via a selection unit 111 controlled by the control unit 101.

Next, referring to FIG. 3, an example of the configuration of the power receiving device 200 according to the first embodiment will be described. FIG. 3 is a block diagram showing an example of the configuration of the power receiving device 200 (RX). The RX has a control unit 201, a UI unit 202, a power receiving unit 203, a first communication unit 204, a power receiving antenna 205, a charging unit 206, a battery 207, and a memory 208. The RX 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 RX has three

power receiving units

203a, 203b, and 203c, and three

first communication units

204a, 204b, and 204c. The

first communication units

204a, 204b, and 204c are connected to the corresponding

power receiving units

203a, 203b, and 203c, respectively. In this embodiment, all three power receiving units 203 (or first communication units 204) have the same characteristics, but they may each have different characteristics.

RX has multiple receiving antennas (receiving coils) 205. In this example, RX has

N receiving antennas

205a, 205b, ... 205n. RX also has N

resonant capacitors

211a, 211b, ... 211n.

RX has N

second switch units

210a, 210b, ... 210n and N

third switch units

213a, 213b, ... 213n. Each receiving antenna, resonant capacitor, second switch unit, and third switch unit are paired with the same alphabet attached to the reference numeral.

For example, a power receiving antenna 205a, a resonant capacitor 211a, a second switch section 210a, and a third switch section 213a form a group. The power receiving antenna 205a is connected to the resonant capacitor 211a via the third switch section 213a, and the second switch section 210a is connected in parallel to the power receiving antenna 205a, the third switch section 213a, and the resonant capacitor 211a.

In this embodiment, all N receiving antennas 205 (or resonant capacitors 211, or second switch section 210, or third switch section 213) have the same characteristics, but may each have different characteristics.

The control unit 201 controls each functional block element of the RX by executing a control program stored in the memory 208. Furthermore, the control unit 201 can perform control to execute applications other than wireless power transmission.

The control unit 201 is configured to include one or more processors such as a CPU or MPU. In addition, the control unit 201 can control the entire RX (e.g., the entire smartphone) in cooperation with the OS (Operating System) that it is running.

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 a specified process. The control unit 201 stores information to be stored during execution of various processes in the memory 208, and is also capable of executing timing processes using a timer (not shown).

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 RX main unit, and other operations. The UI unit 202 is realized by an LCD panel, a speaker, a vibration motor, etc.

The power receiving unit 203 receives AC power (AC voltage and AC current) generated by electromagnetic induction based on electromagnetic waves radiated from the TX power transmitting antenna 105 via the power receiving antenna (power receiving coil) 205. The power receiving unit 203 then converts the AC power into DC or AC power of a specified frequency and outputs the power to the charging unit 206.

The charging unit 206 charges the battery 207. The power receiving unit 203 includes a rectification unit (rectifier, rectification circuit) and a voltage control unit that are necessary to supply power to the load in RX. The rectification unit converts the AC voltage and AC current received from the power transmitting antenna 105 via the power receiving antenna 205 into DC voltage and DC current.

The voltage control unit converts the level of the DC voltage input from the rectification unit to a predetermined level. The predetermined level is a DC voltage level at which the control unit 201 and the charging unit 206 can operate. The power receiving unit 203 supplies power for charging the battery 207 from the charging unit 206. It is assumed that the power receiving unit 203 has a power supply capacity sufficient to output 15 watts of power to the charging unit 206.

The first communication unit 204 communicates with the first communication unit 104 of the TX 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 receiving antenna 205 to obtain the information transmitted from the TX. The first communication unit 204 performs load modulation or amplitude modulation on the input electromagnetic waves, and superimposes a signal related to the information to be transmitted to the TX on the electromagnetic waves, thereby communicating with the TX.

In addition to the control program, the memory 208 stores information about the status of the TX and RX. Information about the status of the RX is acquired by the control unit 201. Information about the status of the TX is acquired by the control unit 101 of the TX, and can be received by the first communication unit 204 or the second communication unit 212.

The first switch unit 209 is provided between the charging unit 206 and the battery 207, and is controlled by the control unit 201. The first switch unit 209 has a function of controlling whether or not the power received by the power receiving unit 203 is to be supplied to the battery 207, and a function of controlling the size of the load.

When the control unit 201 turns the first switch unit 209 to the OFF state and opens it, the power received by the power receiving unit 203 is not supplied to the battery 207. When the control unit 201 turns the first switch unit 209 to the ON state and shorts it, the power received by the power receiving unit 203 is supplied to the battery 207.

3, the first switch unit 209 is disposed between the charging unit 206 and the battery 207, but the first switch unit 209 may be disposed between the power receiving unit 203 and the charging unit 206. Alternatively, multiple first switch units 209 may be disposed between the closed circuit formed by the power receiving antenna 205, the resonant capacitor 211, and the second switch unit 210, and each of the power receiving units 203 (power receiving unit 203a, power receiving unit 203b, power receiving unit 203c).

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 supplied to the power receiving unit 203. Also, in the example of FIG. 3, the first switch unit 209 is shown as one functional block element, but it is possible to realize the first switch unit 209 as part of the charging unit 206 or the power receiving unit 203.

Furthermore, the first switch unit 209 is not limited to being inserted in series between the charging unit 206 and the battery 207, but may be inserted in parallel between the charging unit 206 and the battery 207.

In this case, when the control unit 201 turns the first switch unit 209 to the OFF state and opens it, the power received by the power receiving unit 203 is supplied to the battery 207. When the control unit 201 turns the first switch unit 209 to the ON state and shorts it, the power received by the power receiving unit 203 is not supplied to the battery 207.

On the input side of the power receiving unit 203, the second switch unit 210 is connected in parallel with 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.

In this embodiment, the second switch unit 210 and the third switch unit 213 are controlled by the control unit 201 via the selection unit 214 described below. 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 in an open state. 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 and the selection unit 214.

When the control unit 201 turns the third switch unit 213 to the ON state and the second switch unit 210 is turned ON and short-circuited, the receiving antenna 205 and the resonant capacitor 211 form a series resonant circuit and resonate 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 section 210, and no current flows through the power receiving section 203. When the second switch section 210 is turned OFF and the circuit is opened, the power received by the power receiving antenna 205 and the resonant capacitor 211 is supplied to the power receiving section 203.

Note that, without being limited to the example of FIG. 3, the second switch section 210 may be disposed between the power receiving antenna 205 and the resonant capacitor 211. When the third switch section 213 is in the ON state and the second switch section 210 is in the ON state, the terminals of the power receiving antenna 205 are shorted. The third switch section 213 may also be disposed between the resonant capacitor 211 and the power receiving section 203.

The selection unit 214 connects each of the

power receiving units

203a, 203b, and 203c to one of the power receiving antennas 205 (power receiving antennas 205a to 205n). The selection unit 214 connects the power receiving unit 203 (203a, 203b, or 203c) to any one or more power receiving antennas 205.

The control unit 201 controls the selection unit 214 to determine which of the power receiving antennas 205 (power receiving antennas 205a to 205n) each power receiving unit should be connected to. The selection unit 214 switches the connection between the power receiving unit 203 and the power receiving antenna 205 according to a control signal from the control unit 201.

The TX and RX perform wireless power transmission based on the WPC standard between the transmitting antenna 105 and the receiving antenna 205. In the WPC standard, the amount of power guaranteed when the RX receives power from the TX is specified by a value called Guaranteed Load Power (hereinafter referred to as "GP").

For example, GP indicates the power value that guarantees output to the load of RX even if the efficiency of power transmission between the receiving antenna 205 and the transmitting antenna 105 decreases due to a change in the relative positions of RX and TX. The load of RX is the charging unit 206, the battery 207, etc. in FIG. 3, and the value of GP corresponds to the amount of power that is guaranteed to be output from the receiving unit 203.

Alternatively, the value of GP corresponds to the amount of power guaranteed to be output from the rectification unit of the power receiving unit 203. For example, assume that the value of GP is 5 (watts) and the positional relationship between the power receiving antenna 205 and the power transmitting antenna 105 has changed. In this case, even if the power transmission efficiency decreases, the TX performs power transmission control so that it can output 5 watts to the RX load.

GP is determined by negotiation between TX and RX. This embodiment can be applied to any configuration in which power is transmitted and received at a power determined by mutual negotiation between a power transmitting device and a power receiving device, not limited to GP.

In addition, when transmitting power from TX to RX, a case is assumed in which an object is present near TX. In this case, the object is an object that can affect power transmission and is an object (foreign object) different from the power receiving device 200. There is a possibility that the electromagnetic waves used for power transmission will affect the foreign object, causing an increase in temperature or destruction of the foreign object.

In this disclosure, a foreign object is, for example, a paperclip or an IC card. A foreign object is neither a part of a power receiving device or a product in which the power receiving device is incorporated, nor a part of a power transmitting device or a product in which the power transmitting device is incorporated, but is an object that can generate heat when exposed to a power signal transmitted by a power transmitting antenna.

A power receiving device and an object that is an integral part of a product in which the power receiving device is incorporated, or a power transmitting device and an object that is an integral part of a product in which the power transmitting device is incorporated, are not considered foreign objects. The WPC standard specifies a method for preventing the foreign object from heating up or being destroyed by stopping power transmission when a foreign object is present. Specifically, the power transmitting device 100 is capable of detecting 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 power transmitting device 100 and the received power in the power receiving device 200. The Q-factor measurement method is a method for detecting a foreign object based on a change in the quality factor (Q-factor, quality coefficient, Q-factor) associated with the power transmitting antenna 105 (power transmitting coil) in the power transmitting device 100.

The Q-factor measurement method is a method for detecting foreign objects by detecting changes in the quality factor (Q-factor, quality coefficient, Q-factor) of the resonant circuit including the power transmitting antenna 105 (power transmitting coil) and the resonant capacitor 107 in the power transmitting device 100.

However, the foreign objects that the power transmission device 100 detects are not limited to objects present on the charging stand 300. The power transmission device 100 can detect foreign objects located in the vicinity of the power transmission device 100. For example, the power transmission device 100 can detect foreign objects located within a range where power can be transmitted.

With reference to Figure 4, foreign object detection based on the Power Loss method defined in the WPC standard will be described. Figure 4 is an explanatory diagram of a threshold setting method for state detection using the Power Loss method, with the horizontal axis representing the transmitted power of the power transmitting device 100 and the vertical axis representing the received power of the power receiving device 200.

On the graph line indicated by the straight line segment 1002, point 1000 corresponds to the first transmitted power value Pt1 and the first received power value Pr1, and point 1001 corresponds to the second transmitted power value Pt2 and the second received power value Pr2. On the graph line, point 1003 corresponds to the third transmitted power value Pt3 and the third received power value Pr3. The foreign object to be detected is a conductive metal piece or the like.

First, the power transmitting device 100 transmits power to the power receiving device 200 at a first transmission power value Pt1, and the power receiving device 200 receives power at a first reception power value Pr1. Then, the power transmitting device 100 stores the first transmission power value Pt1. For example, the first transmission power value Pt1 and the first reception power value Pr1 are predetermined minimum transmission power values and reception power values.

At this time, the power receiving device 200 performs load control so that the power it receives is the minimum power. Alternatively, the power receiving device 200 performs load control so that the power it receives is within a predetermined range or is equal to or less than a predetermined threshold.

The "power" in "power within a predetermined range" or "power below a predetermined threshold" refers to a power with a value of approximately 10% of the Reference Power described below. For example, the power receiving device 200 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 and battery 207 in FIG. 3).

Alternatively, the load may be controlled so that a predetermined amount of power is supplied to the load. This can be achieved by the power receiving device 200 controlling the first switch unit 209. Hereinafter, the state of the load controlled in this way is referred to as the light load state.

Then, the power receiving device 200 notifies the power transmitting device 100 of the first received power value Pr1. The signal related to the first received power value Pr1 is a Received Power Data Packet (mode 1) defined in the WPC standard. Hereinafter, this packet will be referred to as "RP1."

The power transmitting device 100, which receives RP1 from the power receiving device 200, calculates the power loss between the power transmitting device 100 and the power receiving device 200. The power loss at this time is Pt1-Pr1 (=Ploss1). A calibration point (hereafter abbreviated as CP) 1000 that indicates the correspondence between Pt1 and Pr1 can be created.

Then, the power transmitting device 100 changes the transmission power value to the second transmission power value Pt2 and transmits power to the power receiving device 200, and the power receiving device 200 receives power at the second receiving power value Pr2. Hereinafter, this state is referred to as the Connected Load state.

Then, the power transmitting device 100 stores the second transmission power value Pt2. For example, the second transmission power value Pt2 and the second reception power value Pr2 are the maximum transmission power value and reception power value that have been determined in advance. At this time, the power receiving device 200 performs load control so that the received power becomes the maximum power.

Here, "maximum power" refers to a power value close to the Reference Power described below. For example, the power receiving device 200 connects the power receiving antenna 205 to the load so that the received power is supplied to the load.

These can be achieved by controlling the first switch unit 209. Next, the power receiving device 200 notifies the power transmitting device 100 of the second received power value Pr2. The signal related to the second received power value Pr2 is a Received Power Data Packet (mode 2) defined in the WPC standard.

Hereinafter, this packet will be referred to as "RP2". The power transmitting device 100, which has received RP2 from the power receiving device 200, calculates the power loss between the power transmitting device 100 and the power receiving device 200. The power loss at this time is Pt2-Pr2 (=Ploss2). It is possible to generate CP1001, which indicates the correspondence between Pt2 and Pr2.

The power transmitting device 100 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 in which no foreign object is detected to exist near the power transmitting device 100 and the power receiving device 200 (hereinafter referred to as the first detection state).

Based on the line segment 1002, the power transmission device 100 can estimate the power value that the power receiving device 200 will receive when transmitting power at a specified transmission power in the first detection state. For example, assume that the power transmission device 100 transmits power at a third transmission power value Pt3. In this case, the power transmission device 100 can estimate the third received power value Pr3 that the power receiving device 200 will receive from a point 1003 on the line segment 1002 that corresponds to Pt3.

As described above, the power loss between the power transmitting device 100 and the power receiving device 200 according to the load can be obtained based on multiple combinations of the transmission power value of the power transmitting device 100 and the reception power value of the power receiving device 200 measured while changing the load. In addition, the power loss between the power transmitting device 100 and the power receiving device 200 according to all loads can be estimated by performing an interpolation process from multiple combinations of the transmission power value and the reception power value.

The calibration process performed by the power transmission device 100 and the power receiving device 200 in this way so that the power transmission device 100 can obtain a combination of the transmission power value and the reception power value is called "Power Loss method calibration process." The calibration process is also abbreviated as CAL process.

It is assumed that after the CAL process of the Power Loss method, the power transmitting device 100 transmits power to the power receiving device 200 at a third transmission power value Pt3, and the power transmitting device 100 receives a signal related to a received power value Pr3 ^* from the power receiving device 200.

The signal relating to the received power value Pr3 ^* is a Received Power Data Packet (mode 0) defined in the WPC standard, but other messages may be used. Hereinafter, this packet will be referred to as "RP0".

RP0 includes, for example, received power value Pr3 ^* . Power transmitting device 100 subtracts received power value Pr3 ^* from received power value Pr3 in the first detection state to calculate Pr3-Pr3 ^* (=Pluss_FO).

When a foreign object is present near the power transmitting device 100 and the power receiving device 200, Ploss_FO can be estimated as the power consumed by the foreign object, i.e., the power loss. Hereinafter, the state in which the presence of a foreign object is detected near the power transmitting device 100 and the power receiving device 200 is referred to as the second detection state.

In the second detection state, the power transmission device 100 compares the power loss Ploss_FO that would have been consumed by the foreign object with a predetermined threshold value. If the value of the power loss Ploss_FO exceeds the threshold value, the power transmission device 100 can determine that a foreign object is present.

Alternatively, the power transmitting device 100 obtains the third received power value Pr3 in the first detection state from the power receiving device 200, and calculates the power loss Pt3-Pr3 (=Ploss3) between the power transmitting device 100 and the power receiving device 200 in advance.

Next, the power transmitting device 100 acquires the received power value Pr3 ^* from the power receiving device 200 in the second detection state, and calculates the power loss Pt3-Pr3 ^* (=Ploss3 ^* ) between the power transmitting device 100 and the power receiving device 200 in the second detection state. Then, the power transmitting device 100 can estimate the power loss Ploss_FO using Ploss3 ^* -Ploss3.

As described above, there are two methods for calculating Ploss_FO in the second detection state.
A first method of calculating Ploss_FO from Pr3-Pr3 ^* .
Plus3 ^*-- A second method for calculating Plus_FO from Plus3.

In this embodiment, the second method is basically described, but the contents of this embodiment can also be applied to the first method.

Next, referring to Figure 5, foreign object detection based on the Q-factor measurement method defined in the WPC standard will be described. Figures 5(A) and (B) are explanatory diagrams of the Q-factor measurement method according to the first embodiment, and Figure 5(A) is a schematic circuit diagram for explaining a method of measuring the Quality Factor (Q-factor, quality coefficient, Q-factor) using the Q-factor measurement method.

The AC power supply 901 is a power supply that outputs the AC power generated by the power transmission unit 103 of the TX. The power transmission antenna 902 corresponds to the power transmission antenna 105, and the capacitor 903 corresponds to the resonant capacitor 107. The power transmission antenna 902 and the capacitor 903 are connected in series.

The voltage value V8 is a voltage value of a predetermined frequency generated by the power transmitting unit 103 for operating the wireless power transmission system. The voltage value V9 is a voltage value applied to the power transmitting antenna 902. Here, TX is capable of changing the frequency related to the voltage value.

The voltage values V8 and V9 are voltage values that the TX measures when it transmits an Analog Ping (hereinafter referred to as AP) or a Digital Ping (hereinafter referred to as DP) to the RX. Note that since the voltage values V8 and V9 are AC voltage values, their effective values (RMS) may also be used.

Figure 5 (B) shows an example of the measurement results of V9/V8 versus frequency, with a characteristic that has 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 when an object is placed near the power transmitting antenna 902, the value changes.

The change in Quality Factor differs depending on whether no object is placed on the TX, whether an RX is placed on the TX, whether a foreign object (such as a metal piece) is placed on the TX, or whether an RX and a foreign object are placed on the TX.

In the Negotiation phase, TX receives a FOD Status Data packet signal from RX. This packet contains 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 transmitting antenna of the test TX when the RX is placed on the test TX and there are no foreign objects nearby.

The Reference Resonance Frequency Value is the resonant frequency calculated from the inductance value that can be measured at the terminal of the transmitting antenna of the test TX when the RX is placed on the test TX and there is no foreign object nearby.

In the Q-value 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 measured V9/V8.

Alternatively, a threshold value is set based on the Reference Resonance Frequency Value. Foreign objects are detected by comparing this threshold value with the resonance frequency obtained by measuring V9/V8.

The RX and TX in this embodiment communicate for power transmission and reception control based on the WPC standard. The WPC standard specifies 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 is carried out for the necessary power transmission and reception control. For example, foreign object detection using the Power Loss method is performed in the Power Transfer phase based on data acquired in the Calibration phase. In addition, foreign object detection using the Q-value measurement method is performed before power transmission (before sending DP and in the Negotiation phase or Renegotiation phase).

Next, the function of the control unit 101 of the TX 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 transmission device 100 (TX) according to the first embodiment. The control unit 101 has a communication control unit 301, a power transmission control unit 302, a measurement unit 303, a setting unit 304, and a state detection unit 305. The communication control unit 301 controls communication with the RX via the first communication unit 104 or the second communication unit 109.

The power transmission control unit 302 controls the power transmission unit 103 to control the power transmission to the RX. The measurement unit 303 measures the waveform attenuation index, which will be described later. The measurement unit 303 also measures the power transmitted to the RX via the power transmission unit 103, and measures the average transmitted power per unit time. The measurement unit 303 also measures the Quality Factor of the power transmission antenna 105.

The measurement unit 303 also measures the quality factor of the resonant circuit including the power transmitting antenna 105 and the resonant capacitor 107. Hereinafter, the quality factor of the power transmitting antenna 105 and the quality factor of the resonant circuit including the power transmitting antenna 105 and the resonant capacitor 107 are referred to as the quality factor related to the power transmitting antenna 105.

The measurement unit 303 also measures the temperature using temperature sensors arranged at multiple locations on the power transmitting device 100. The measurement unit 303 also measures a quantity (coupling state index) that indicates the electromagnetic coupling state (hereinafter also simply referred to as the coupling state) between the power transmitting antenna 105 and the power receiving antenna 205. The coupling state index includes, for example, a coupling coefficient. The method of measuring the coupling state index will be described later.

The setting unit 304 sets a threshold value that serves as a reference for determining the presence or absence of a foreign object when the TX performs status detection. Status detection is, for example, status detection based on the power loss method, the Q value measurement method, or the waveform attenuation method, status detection based on the temperature measured in the power transmitting device 100, or status detection based on the coupling coefficient between the power transmitting antenna 105 and the power receiving antenna 205, etc.

The setting unit 304 can set judgment thresholds required for state detection processing using other methods. The setting unit 304 calculates and sets the thresholds for detecting foreign objects or the thresholds for detecting positional deviations between TX and RX in the Power Loss method, the Q-factor measurement method, the waveform attenuation method, and the coupling state index measurement method for the power transmitting antenna and the power receiving antenna.

The setting unit 304 also calculates and sets a threshold value for detecting foreign objects or a threshold value for detecting misalignment between TX and RX based on the temperature of the power transmitting device measured by the measurement unit 303. The setting unit 304 can also set a judgment threshold value required for state detection processing using other methods.

The state detection unit 305 detects the state of TX and RX. For example, the state detection unit 305 detects foreign objects present between TX and RX, and also detects misalignment between the transmitting antenna 105 and the receiving antenna 205. More specifically, state detection processing is possible using the power loss method, the Q value measurement method, the waveform attenuation method, the temperature measured by the power transmitting device 100, and the electromagnetic coupling state (e.g., the coupling coefficient) between the transmitting antenna 105 and the receiving antenna 205.

The status detection unit 305 can detect foreign objects and positional deviations between the power transmitting antenna 105 and the power receiving antenna 205 using other methods. For example, in a TX equipped with an NFC communication function, the status detection unit 305 performs status detection processing using a function for detecting a counterpart device according to the NFC standard.

The state detection unit 305 can detect state changes on the TX in addition to detecting the presence or absence of a foreign object and the electromagnetic coupling state between the transmitting antenna and the receiving antenna. For example, the TX can detect an increase or decrease in the number of RXs on the TX. The state detection unit 305 can perform a foreign object detection process and a positional deviation detection process between the transmitting antenna 105 and the 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 state detection unit 305 can obtain data such as the waveform attenuation index, the transmission power, the Quality Factor, the temperature measured by the power transmission device 100, and the coupling coefficient between the power transmission antenna 105 and the power receiving antenna 205 as the measurement results of the measurement unit 303.

The processes performed by the communication control unit 301, power transmission control unit 302, measurement unit 303, setting unit 304, and state detection unit 305 shown in FIG. 6 can be realized using programs executed by a CPU or the like provided in the control unit 101. Each process is executed in parallel according to an independent program, with synchronization between the programs achieved by event processing or the like. However, two or more of these processes may be incorporated into the processing of a single program.

Next, an example of the flow of the power transmission and reception control process executed by TX and RX will be explained. Before the Power Transfer phase, which is the power transmission phase, there are the following phases.

- Selection phase.
・Ping phase.
Identification and Configuration phase (Configuration phase).
-Negotiation phase.
- Calibration phase.

In the following, the Identification and Configuration phase will be referred to as the I&C phase.

FIG. 7 is a flowchart explaining the processing of the power transmission device according to the first embodiment, and shows an example of the flow of the power transmission control processing executed by the TX. This processing is realized, for example, by the control unit 101 of the TX executing a program read from the memory 106.

This process is also executed when the power of the TX is turned on, when the user of the TX inputs an instruction to start a wireless power transmission application, or when the TX is connected to a commercial power source and receives power. This process may also be started by some other trigger.

In S1201, the TX executes the processes defined as the Selection phase and Ping phase, and waits for the RX to be placed. In the Selection phase, the TX repeatedly transmits the AP intermittently, and detects objects that are within the power transmission range.

For example, the TX can detect that an RX, a conductor piece, etc. has been placed on the charging stand 300. The TX detects one or both of the voltage and current values of the power transmitting antenna 105 when an AP is transmitted. If the voltage value falls below a threshold value or if the current value exceeds a threshold value, the TX determines that an object is present and transitions to the Ping phase.

Then, if the TX detects the presence of an object within the power transmission range, it transmits a DP. The power of the DP is greater than the power of the AP, and is sufficient to start up the control unit 201 of the RX placed on the TX. If there is a specified response to the DP, the TX determines that the object detected in the Selection phase is the RX, and that the RX has been placed on the charging stand 300.

Here, the "predetermined response" is a Signal Strength (SIG) Data Packet sent by the RX. This packet includes a Signal Strength Value that indicates the signal strength of the signal received by the RX.

This value is calculated from the voltage (rectified voltage) applied to the rectifier of the power receiving unit 203 measured by the RX, or the voltage (open circuit voltage) of the open circuit including the power receiving antenna 205 measured by the RX, or the received power value measured by the RX, etc.

Before transmitting the DP, the TX also measures the Quality Factor of the transmitting antenna 105, for example, using the AP. This measurement result is used when executing the foreign object detection process using the Q-value measurement method. Note that, depending on the version of the WPC standard, the above-mentioned Selection phase may be called the Ping phase as part of the above-mentioned Ping phase.

At S1202, the TX receives a Signal Strength (SIG) Data Packet. When the TX detects that the RX has been placed, it obtains identification information from the RX through communication in the I&C phase defined by the WPC standard.

In the I&C phase, the RX sends an Identification Data Packet (ID Packet) to the TX. This packet contains the Manufacturer Code and Basic Device ID, which are identifiers for each individual RX, as well as information elements that can identify the version of the WPC standard that is supported.

Furthermore, the RX sends a Configuration Data Packet to the TX. This packet contains the RX's capability information (device configuration information) shown below.

- Information that makes it possible to identify the version of the WPC standard that the RX supports.
- Maximum Power Value or Reference Power, which is a value that specifies the maximum power the RX can supply to the load.
Information indicating whether the RX has a WPC standard Negotiation function.
A parameter used in frequency shift keying, which is a communication modulation method used when TX transmits information to RX.

When the TX receives these packets, it sends an ACK acknowledgement, and the I&C phase ends. Note that the I&C phase may also be called the Configuration phase depending on the version of the WPC standard.

The TX may also obtain the identification information of the RX by a method other than communication in the I&C phase of the WPC standard. The identification information for each individual RX may also be a Wireless Power ID.

Furthermore, the identification information for each individual RX may be any other identification information capable of identifying the individual RX, such as a Bluetooth (registered trademark) Address (hereinafter referred to as "BD_ADDR") unique to the second communication unit 212 of the RX.

BD_ADDR is an 8-byte address used in BLE. BD_ADDR is a public address defined in the BLE standard that indicates, for example, the manufacturer of the RX or individual identification information of the BLE communication function (second communication unit 212). BD_ADDR may also be a random address.

Next, in S1203, the TX determines the GP value through negotiation with the RX based on the RX's request and the power transmission capacity of the device itself. Communication is performed in the negotiation phase of the WPC standard, and the GP value is determined based on the GP value requested by the RX, the TX's power transmission capacity, etc.

GP, which is determined through negotiation between the TX and RX, is the power output (supplied) to the load of the RX. Here, we explain the process flow for determining the GP value. The RX sends a Specific Request to the TX, which includes information about the Requested Load Power.

Requested Load Power is the power requested by the RX to be output to the load of the RX. This power is consumed by the load, and the load refers to the system to which power is supplied from the RX or the power receiving unit of the RX (for example, the charging unit 206 of the RX, the battery 207).

On the other hand, the TX already has a Potential Load Power value or a Negotiable Load Power value. Potential Load Power is the maximum load power value (Highest Load Power Level) that the TX can negotiate and output (supply) to the RX load.

Negotiable Load Power is the maximum load power value (Highest Load Power Level) that the TX can negotiate and output (supply) to the RX load during a specified period or under specified conditions. The negotiation is successful when the Requested Load Power value is smaller than the Negotiable Load Power value.

In this case, TX and RX set the Requested Load Power value as the GP value and store it in memory. In other words, TX receives the Requested Load Power value from RX, and if that value is smaller than the Negotiable Load Power value, it sends an ACK acknowledgement to RX.

The TX and RX set the Requested Load Power value as the GP value and store it in memory. If the Requested Load Power value received from the RX is greater than the Negotiable Load Power value, the TX sends a negative acknowledgement NAK to the RX.

The RX reduces the value of Requested Load Power and again sends a signal indicating the value of Requested Load Power to the TX. The RX repeats the above process until it receives an ACK positive response from the TX. When the RX receives an ACK positive response, the TX and RX set the value of Requested Load Power as the GP value and store it in memory.

The GP value that is determined will be the value requested by the RX if the TX accepts the request from the RX, but if not, it will be a predetermined value (e.g., 5 watts) defined in the WPC standard. Alternatively, if the TX obtains information indicating that the RX does not support the negotiation phase, it will not perform communication in the negotiation phase and will determine the GP value to be a predetermined value. The predetermined value is, for example, a value (e.g., 5 watts) that is predefined in the WPC standard.

The TX also performs foreign object detection processing using the Q-value measurement method in response to a request from the RX. The TX receives an FOD Status Data packet from the RX. This packet includes the above-mentioned Reference Quality Factor Value and Reference Resonance Frequency Value.

In the Q-value measurement method, foreign object detection processing is performed based on a threshold value based on the Reference Quality Factor Value and the Reference Resonance Frequency Value.

In the foreign object detection process using the Q-factor measurement method, in response to a request from the RX to the TX, the value of the Quality Factor of the transmitting antenna 105 measured by the TX before transmitting the DP is compared with the above threshold value, and the presence or absence of a foreign object and the possibility of its presence are determined based on the comparison result.

The WPC standard also prescribes a method of transitioning to the Power Transfer phase, and then performing the same processing as the Negotiation phase again upon request from the RX. The phase in which this processing is performed after the Power Transfer phase is called the Renegotiation phase.

Next, in S1204, the TX and RX execute CAL processing in the calibration phase. The TX executes CAL processing using the Power Loss method based on the determined Reference Power value or GP value.

Specifically, the RX transmits a signal to the TX that contains information about the received power in a light load state (hereinafter referred to as first reference received power information). A light load state is, for example, a load disconnection state, a load state in which the received power value of the RX is equal to or lower than a first threshold, or a load state in which the received power value of the RX is within a predetermined first range.

For example, the first reference received power information is information indicating 500 milliwatts. The first reference received power information is information contained in RP1, but other messages may be used. The TX determines whether or not to accept the first reference received power information based on the value of the Control Error Value contained in the Control Error (CE) Data Packet received from the RX.

Hereinafter, Control Error Data Packet will be abbreviated as CE, and Control Error Value will be abbreviated as CEV. If TX accepts the first reference received power information, it will send an acknowledgment ACK to RX. If TX does not accept the first reference received power information, it will send a negative acknowledgment NAK to RX.

Next, the RX performs processing to transmit to the TX a signal containing information about the received power in a load connection state (hereinafter referred to as second reference received power information). The load connection state is, for example, a maximum load state or a load state in which the transmitted power value is equal to or greater than a second threshold value.

Or, it is a load state in which the power received by the RX is the maximum power. Here, "maximum power" is a power value close to the Reference Power. Or, it is a load state in which the received power value of the RX is within a predetermined second range. Here, the second range is a range of power values higher than the first range.

For example, the second reference received power information is information indicating 5 watts. The second reference received power information is information included in RP2, but other messages may be used. The TX determines whether or not to accept the second reference received power information based on the CEV included in the CE received from the RX.

If the TX accepts the second reference received power information, it sends an acknowledgment ACK to the RX. If the TX does not accept the second reference received power information, it sends a negative acknowledgment NAK to the RX. The TX completes the CAL process after sending an acknowledgment ACK to the second reference received power information from the RX.

The above CAL process enables the TX to calculate the amount of power loss between the TX and the RX in the light load state and the load connected state based on the transmission power value of the TX and the received power value contained in the first and second reference received power information.

The TX can also calculate the amount of power loss between the TX and the RX for all possible transmission powers by performing an interpolation process between multiple power loss amounts. All possible transmission powers by the TX are, for example, any power within the range of the receiving power received by the RX in this embodiment from 500 milliwatts to 5 watts.

Then, in S1205, the TX transmits power until the RX battery is fully charged. In the communication in the Power Transfer phase, control is performed for starting and continuing power transmission, as well as error processing and stopping power transmission due to full charge. The TX and RX perform communication processing for this power transmission and reception control.

For example, using the transmitting antenna 105 and the 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 transmitting antenna 105 or the receiving antenna 205. Note that the range in which communication based on the WPC standard between the TX and the RX is possible is the same as the range in which the TX can transmit power.

The RX repeatedly transmits CE to the TX at time intervals of t_interval. t_interval is a value defined in the WPC standard, e.g., 250 milliseconds. The RX can use the CE to request the TX how much to increase or decrease its transmission power.

In other words, the CE packet includes a parameter (CEV) for adjusting the transmission power. The TX adjusts the transmission power by controlling the current or voltage of the transmission antenna 105 based on the received CE. By repeating this process, transmission at an appropriate power according to the request of the RX is performed almost in real time.

When the RX is fully charged, it sends an End Power Transfer Data Packet (hereinafter referred to as "EPT") to the TX to end the Power Transfer phase. The RX may send an EPT for reasons other than full charge. In addition, when the Power Transfer phase ends, the TX stops transmitting power to the RX for charging.

If TX does not receive the next CE even after t_timeout has elapsed since the last CE was received, TX determines that RX has been removed from the charging station 300 and ends the Power Transfer phase. t_timeout is a value defined by the WPC standard, and is, for example, 1500 milliseconds.

The RX may transmit packets other than CE during the Power Transfer phase. An example of a packet other than CE is a Charge Status Data Packet that notifies the TX of the status of the RX's battery 207. The packet stores a Charge Status Value that indicates the percentage of charge of the battery 207.

When the TX receives the Charge Status Data Packet, it notifies the user of the charging status, for example by displaying text or a figure based on the Charge Status Value on the UI unit 110. The TX may receive the Charge Status Data Packet at any time, and may notify the user at any time.

In the Power Transfer phase, the TX transmits power to the RX and performs foreign object detection processing using the Power Loss method. For example, the amount of power loss between the TX and RX in the first detection state during the power transmission process is calculated from the difference between the transmitted power value and the received power value using CAL processing.

The calculated amount of power loss corresponds to the reference amount of power loss in the absence of a foreign object. If the TX determines that the difference between the amount of power loss between the TX and RX measured during power transmission after CAL processing and the reference amount of power loss is equal to or greater than a threshold value, it determines that the second detection state is present.

Note that depending on the version of the WPC standard, the Calibration phase mentioned above may also be called the Power Transfer phase as part of the Power Transfer phase mentioned above.

An example of the power receiving control process executed by the RX will be described with reference to FIG. 8. FIG. 8 is a flowchart illustrating the process of the power receiving device according to the first embodiment. This process is realized, for example, by the control unit 201 of the RX executing a program read from the memory 208. In S1301, the RX executes the processes defined as the Selection phase and Ping phase of the WPC standard, and waits for its own device to be placed on the TX.

The RX detects that it has been placed on the TX, for example, by detecting a DP from the TX. When the RX receives the DP, it sends a Signal Strength (SIG) Data Packet to the TX.

In S1302, when the RX detects that its own device has been placed on the TX, it transmits information including its own device's identification information to the TX using the above-mentioned ID Packet and Configuration Data Packet.

The identification information of the RX may be transmitted by a method other than communication in the I&C phase, and other identification information such as BD_ADDR may be used as long as it is information that can identify each individual RX. Furthermore, the RX may transmit information other than the identification information to the TX in S1302.

Next, in S1303, the RX sends a Specific Request including the Requested Load Power information to the TX, waits for a response from the TX, and determines the GP.

In S1303, communication takes place in the negotiation phase of the WPC standard. The RX transmits the above-mentioned FOD Status Data packet to the TX. This packet requests the TX to perform foreign object detection using the Q-value measurement method.

Next, in S1304, RX and TX perform the calibration phase processing. RX transmits RP1 and RP2 to TX. In S1305, RX receives power until the battery 207 is fully charged.

In the Power Transfer phase, the RX and TX perform foreign object detection processing using the Power Loss method. In S1305, the RX repeatedly transmits CE at intervals of t_interval. When the battery 207 is fully charged, the RX transmits EPT to the TX and ends the processing.

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 during power transmission, and has the disadvantage that the accuracy of foreign object detection decreases when the power transmission device 100 is transmitting a large amount of power. On the other hand, it has the advantage that high power transmission efficiency can be maintained because the foreign object detection process can be performed while continuing power transmission.

However, when detecting foreign objects only using the Power Loss method during the Power Transfer phase, there is a possibility that a foreign object may be erroneously detected, or that a foreign object may be erroneously determined not to exist even though it is actually present. For example, consider the case where a foreign object is present near the TX and RX during power transmission in the Power Transfer phase.

In this case, there is a possibility that the heat generated by the foreign object may increase, so it is necessary to improve the accuracy of foreign object detection during the power transfer phase. Therefore, in order to improve the accuracy of foreign object detection, we will explain the waveform attenuation method, which makes it possible to detect foreign objects based on the attenuation state of the transmitted wave. With the waveform attenuation method, the TX can detect foreign objects using the voltage waveform or current waveform related to the power transmission to the RX.

In other words, foreign object detection is possible without using a newly defined foreign object detection signal, etc. In this disclosure, the voltage waveform or current waveform related to the power transmission from the TX to the RX is called the power transmission waveform.

FIG. 9 is an explanatory diagram of state detection using the waveform attenuation method according to the first embodiment, and explains the principle of foreign object detection using the waveform attenuation method. An example of foreign object detection using a transmission waveform related to power transmission from a power transmitting device 100 (TX) to a power receiving device 200 (RX) is shown. In FIG. 9, the horizontal axis represents time, and the vertical axis represents voltage or current values.

The waveform 600 shown in FIG. 9 shows, for example, the change over time of the high-frequency voltage value or current value observed at the TX power transmission antenna 105. Alternatively, it shows the change over time of the high-frequency voltage value or current value observed at a circuit including the TX power transmission antenna 105 and the resonant capacitor 107.

TX, which is transmitting power to RX via the transmitting antenna 105, stops transmitting power at time _T0 . At time _T0 , the power supply for power transmission from the power supply unit 102 is stopped. In other words, the power supply for power transmission to the transmitting antenna 105 is stopped. The frequency _f1 of the transmitting wave is a fixed frequency that is between 87 kHz and 205 kHz, for example, that is used in the WPC standard.

Point 601 on waveform 600 is a point on the envelope of the high frequency voltage, and ( _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 ( _T2 , _A2 ) indicates that the voltage value at time _T2 is _A2 .

The Quality Factor (Q-factor, quality coefficient, Q value) of the resonant circuit including the power transmitting antenna 105 and the resonant capacitor 107 can be obtained based on the change in voltage value over time after time _T0 .

For example, the TX 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 transmission wave after power transmission is stopped at time _T0 .
Q = π f ₂ (T ₂ - T ₁ ) / ln (A ₁ / A ₂ ) (Equation 1)

In Equation 1, ln represents a natural logarithm function. Note that the frequency _f1 of the transmission wave when the TX is transmitting power to the RX may differ from the frequency _f2 of the transmission wave immediately after the TX stops transmitting power to the RX.

The value of the Quality Factor decreases when a foreign object is present near TX and RX because the foreign object causes energy loss. Therefore, when looking at the slope of the attenuation of the voltage value, the slope of the line connecting points 601 and 602 is greater when a foreign object is present than when no foreign object is present.

If energy loss occurs due to a foreign object, the attenuation rate of the amplitude of waveform 600 increases. With 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.

In order to actually determine whether or not there is a foreign object, it is possible to make a judgment by comparing some kind of numerical value that indicates the attenuation state. For example, when making a judgment using the Quality Factor, a value of the Quality Factor that is lower than the reference value means that the waveform attenuation rate (the degree of decrease in the amplitude of the waveform per unit time) is high.

As another example, there is a method of making the judgment using the slope of the line connecting points 601 and 602, which is calculated by ( _A1 - _A2 )/( _T2 - _T1 ).In addition, if the times ( _T1 and _T2 ) at which the attenuation state of the voltage values is measured are fixed, the presence or absence of a foreign object can be judged using the difference in the voltage values ( _A1 - _A2 ) or the ratio of the voltage values ( _A1 / _A2 ).

Alternatively, if the voltage value _A1 immediately after the power transmission is stopped is constant, the presence or absence of a foreign object can be determined using the voltage value _A2 after a predetermined time has elapsed. Alternatively, the presence or absence of a foreign object can be determined using the time ( _T2 - _T1 ) that has elapsed until the voltage value _A1 reaches the predetermined voltage value _A2 .

In the waveform attenuation method, it is possible to determine the presence or absence of a foreign object based on the attenuation state of the waveform during the power transmission stop period. Indicators such as the Quality Factor that indicate the attenuation state of the transmitted radio wave are collectively referred to as "waveform attenuation indicators" in this disclosure. In addition, while the vertical axis of FIG. 9 has been described as the axis of the voltage value of the high-frequency voltage applied to the TX power transmission antenna 105, the vertical axis of FIG. 9 may also be the value of the current flowing through the power transmission antenna 105.

As with the voltage value, the attenuation state of the current value during the power transmission stop period changes 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 time change in the current value flowing through the power transmission antenna 105.

In other words, the Quality Factor calculated from the current waveform, the slope of the current value attenuation, the current value difference, the current value ratio, the current value absolute value, or the time it takes for the current value to reach a predetermined value can be used as waveform attenuation indicators to determine the presence or absence of a foreign object and detect the foreign object.

There is also a method based on both the attenuation state of the voltage value and the attenuation state of the current value. With 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 this is not limited to the example of measuring the waveform attenuation index during the period when the TX temporarily stops power transmission. The waveform attenuation index may be measured during the period when the TX 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 the period when 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.

In addition, in the above example, the voltage or current values are measured at two points in time during the period when the TX limits power transmission (power transmission limit period), but measurements may be taken at three or more points in time and the waveform attenuation index may be calculated using these measurements. In this disclosure, power transmission limiting includes stopping power transmission from the TX to the RX and reducing the transmission power.

A method for detecting a foreign object based on a power transmission waveform during power transmission using the waveform attenuation method will be described with reference to FIG. 10. FIG. 10 is an explanatory diagram of a detection processing period using the waveform attenuation method according to the first embodiment, and FIG. 10 shows a power transmission waveform when detecting a foreign object 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 transmission antenna 105.

During the transient response period immediately after the TX starts transmitting power, the transmission waveform is not stable. Therefore, during this transient response period when the transmission waveform is not stable, the RX controls the TX not to communicate using amplitude modulation or load modulation. In addition, the TX controls the RX not to communicate using frequency shift keying.

Hereinafter, this period will be referred to as the communication prohibition period. During this communication prohibition period, TX will transmit power to RX. After the communication prohibition period has elapsed, TX will transmit power stably to RX. Hereinafter, this period will be referred to as the power transmission period.

When the TX receives an execution request packet (command) from the RX requesting a foreign object detection operation, it suspends power transmission after a specified period of time has elapsed, or temporarily reduces the transmission power. Hereinafter, this specified period will be referred to as the preparation period. During the preparation period, the RX controls the TX so that it does not communicate using amplitude modulation or load modulation.

The TX also controls the RX so that it does not communicate using frequency shift keying. By controlling so that communication does not occur during the preparation period, disturbances in the transmission wave shape are suppressed, and the TX is able to more accurately calculate the waveform attenuation index of the transmission wave shape (described later).

The request packet for executing the foreign object detection operation may be RP0, RP1, or RP2 as described above. When the power transmitting unit 103 of the TX stops power transmission or temporarily reduces the transmission power, the amplitude of the transmitted wave attenuates. The period from when the TX temporarily stops power transmission or temporarily reduces the transmission power to when power transmission is resumed is hereinafter referred to as the transmission power control period.

Here, "resuming power transmission" means that the TX increases the transmission power to a predetermined value. Alternatively, the period from when the TX temporarily sets the value of the inverter input voltage input to the inverter in the power transmission unit 103 to 0 volts or temporarily reduces it to when the input voltage value is returned to the predetermined value is hereinafter referred to as the transmission power control period.

The period from when the TX temporarily sets the inverter output voltage output by the inverter in the power transmission unit 103 to 0 volts or temporarily reduces it to when the output voltage value is returned to a predetermined value is hereafter referred to as the transmission power control period. Also, the control by the TX to temporarily stop or temporarily reduce the transmission power is referred to as transmission power control.

The TX calculates the waveform attenuation index of the transmitted wave, compares the calculated value of the waveform attenuation index with a threshold value, and determines whether or not a foreign object is present, or the possibility (probability of presence) of a foreign object. This determination is called foreign object determination. During the transmission power control period, the RX controls the TX so that it does not communicate using amplitude modulation or load modulation.

The TX also controls the RX so that it does not communicate using frequency shift keying. By controlling so that communication does not occur during the transmission power control period, disturbance of the transmission wave shape is suppressed, and the TX can calculate the waveform attenuation index of the transmission wave shape with higher accuracy. Furthermore, foreign object determination may be performed during the transmission power control period, during the communication prohibition period, or during the power transmission period.

If no foreign object is detected after the transmission power control period has elapsed, the TX resumes power transmission. During the transient response period immediately after power transmission resumes, the transmission waveform is not stable, so communication is prohibited again. Then, the TX transitions to a power transmission period in which stable power transmission is performed from the TX to the RX.

As described above, the TX repeatedly executes the processes at the start of power transmission, the communication prohibited period, the power transmission period, the preparation period, and the transmission power control period. The TX then calculates a waveform attenuation index at a predetermined timing, compares the calculated value of the waveform attenuation index with a threshold value, and performs a foreign object determination. In the waveform attenuation method, a foreign object determination is performed based on a voltage value or a current value measured at at least two points in time during the transmission power control period.

In addition, during the preparation period, transmission power control period, and communication prohibited period, the RX controls the TX so that it does not communicate with the TX using amplitude modulation or load modulation. Also, the TX controls the RX so that it does not communicate with the RX using frequency shift keying. In other words, the TX controls the RX so that it does not communicate with the RX during a predetermined first period after receiving an execution request packet (command) from the RX.

The WPC standard specifies the period during which the TX cannot transmit packets to the RX (packet transmission is prohibited) after the TX receives a packet other than an execution request packet from the RX during the Power Transfer phase. The first period is a period longer than the period.

In addition, the RX controls the TX so that it does not communicate with the TX for a specified second period after sending an execution request packet (command) to the TX. The WPC standard specifies a period during which the RX cannot send packets to the TX (packet transmission is prohibited) after the RX has sent a packet other than an execution request packet to the TX during the Power Transfer phase. The second period is longer than that period.

During the transmission power control period, if elements such as the power receiving unit 203, charging unit 206, and battery 207 are connected to the RX power receiving antenna 205 and resonant capacitor 211, the waveform attenuation index is affected by the load of these elements. The waveform attenuation index changes depending on the state of the power receiving unit 203, charging unit 206, and battery 207.

As a result, it becomes difficult to distinguish whether the reason for a large value of the waveform attenuation index is 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 detecting a foreign object based on the waveform attenuation index, the control unit 201 of the RX switches the first switch unit 209 to the disconnected (OFF) state during the preparation period.

The RX transmits an execution request packet (command) to the TX and executes the above process during the preparation period. Alternatively, the RX transmits an execution request packet (command) to the TX and executes the above process at the same time. This makes it possible to suppress the effect of the battery 207.

Alternatively, the same effect can be obtained by setting the first switch unit 209 to a light load state instead of a disconnected state. In this case, the same effect can be obtained by performing load control so that the power received by the RX is minimized.

Alternatively, instead of turning off the first switch unit 209, the same effect can be achieved by performing load control so that the power received by the RX is within a predetermined range or is below a predetermined threshold.

Here, in "power within a predetermined range" or "power below a predetermined threshold," "power" refers to power with a value of approximately 10% of the Reference Power. Alternatively, instead of the first switch unit 209 being disconnected, the RX 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. The operations in the Light Load state include the above-mentioned operations. The RX maintains the above-mentioned control even during the transmission power control period. Then, after the power transmission is resumed, the RX releases the above-mentioned control and performs control to return to the original state.

Alternatively, the RX control unit 201 may turn on the second switch unit 210 to short circuit it, allowing current to flow through the closed circuit formed by the power receiving antenna 205, the resonant capacitor 211, and the second switch unit 210. This makes it possible to suppress the effects of the power receiving unit 203, the charging unit 206, and the battery 207.

The RX transmits an execution request packet (command) to the TX and executes the above process during the preparation period. Alternatively, the RX transmits the execution request packet (command) to the TX and executes the above process at the same time. The RX maintains the above control during the transmission power control period. Then, after the power transmission is resumed, the RX releases the above control and performs control to return to the original state.

More accurate foreign object detection is possible based on the waveform attenuation index of the transmitted radio wave acquired by controlling the first switch unit 209 or the second switch unit 210, or both. The same effect can also be obtained by setting the first switch unit 209 to the Light Load state instead of the disconnected state.

Alternatively, during the preparation period, the RX may switch to a low power consumption mode or control the power consumption to be constant while the first switch unit 209 is turned ON to short circuit and the second switch unit 210 is turned OFF to disconnect. The RX transmits an execution request packet (command) to the TX and executes the above processing during the preparation period.

Alternatively, the RX executes the above process at the same time as sending an execution request packet (command) to the TX. The RX maintains the above control even during the transmission power control period. Then, after the power transmission is resumed, the RX releases the above control and performs control to return to the original state.

If the power consumption in the RX is not constant or if a large amount of power is consumed, the waveform attenuation index is affected by the fluctuations in power consumption. For this reason, the RX limits (including halting) the operation of software applications, or sets hardware function block elements to a low power consumption mode or a stopped operation mode. By using the waveform attenuation index measured with the RX power consumption suppressed, more accurate foreign object detection is possible.

Similarly, for TX, 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 when the waveform attenuation index is measured, the waveform attenuation rate is affected by these elements. The value of the waveform attenuation index changes depending on the state 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, it is difficult to distinguish whether this is due to the influence of a foreign object or the influence of the power transmission unit 103, the first communication unit 104, and the power supply unit 102.

When the TX receives a request packet (command) to execute foreign object detection from the RX, the TX turns on the switch unit 108 during the preparation period, causing a current to flow through the closed 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.

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 the closed circuit formed by the power transmitting antenna 105, the resonant capacitor 107, and the switch unit 108.

When the TX measures the waveform attenuation index and detects a foreign object, it can control the switch to disconnect the closed circuit from the power transmission unit, thereby suppressing the above-mentioned effects. The TX maintains the above-mentioned control even during the transmission power control period.

Then, after power transmission is resumed, the TX releases the above-mentioned control and controls the system to return to its original state. By implementing the above methods alone or in combination, more accurate foreign object detection is possible.

Next, a method for setting a threshold for foreign object detection based on the waveform attenuation method will be described. A measurement value of the waveform attenuation index is compared with a predetermined threshold, and a foreign object can be detected based on the comparison result. The first threshold setting method is a method in which the TX holds a predetermined value as the threshold, which is a common value that is not dependent on the RX to which power is transmitted.

This threshold is a fixed value, or a variable value determined by the TX depending on the situation. If a foreign object is present, the waveform attenuation rate of the transmission waveform during the transmission power control period increases. Therefore, the value of the waveform attenuation index obtained when no foreign object is present is stored in advance, and this value is set as the threshold.

By comparing the measured value of the waveform attenuation index with a threshold value, it can be determined that "foreign matter is present" or "there is a high possibility that a foreign matter is present." For example, if Quality Factor is used as the waveform attenuation index, the TX compares the measured value of Quality Factor with a predetermined threshold value.

The threshold value is set based on the measured value of Quality Factor when no foreign matter is present or on the measured value taking into account the measurement error. If the measured value of Quality Factor is smaller than the threshold value, it is determined that "foreign matter is present" or "there is a high possibility that foreign matter is present." If the measured value of Quality Factor is equal to or greater than the threshold value, it is determined that "no foreign matter is present" or "there is a low possibility that foreign matter is present."

The second threshold setting method is a method in which the TX adjusts and determines the threshold based on information transmitted from the RX. A notable difference from the first threshold setting method is that the value of the waveform attenuation index may differ depending on the RX that is the target of power transmission and is placed on the TX.

The reason is that the electrical characteristics of the RX, which is electromagnetically coupled via the TX's transmitting antenna, affect the value of the waveform attenuation index. For example, if Quality Factor is used as the waveform attenuation index, the Quality Factor measured by the TX when no foreign object is present may differ depending on the RX placed on the TX.

The RX therefore retains Quality Factor information for each TX when the RX is placed on the TX in the absence of any foreign object, and notifies the TX of the Quality Factor information. The TX adjusts and determines the threshold for each RX based on the Quality Factor information received from the RX.

More specifically, in the Negotiation phase, the TX receives a FOD Status Data Packet containing the above-mentioned Reference Quality Factor Value information, and adjusts and determines the threshold value in the Q-value measurement method.

The Reference Quality Factor Value corresponds to the Quality Factor information when the RX is placed on the TX in the absence of any foreign object. Therefore, the TX performs adjustments based on the Reference Quality Factor Value and determines the threshold value for foreign object detection using the waveform attenuation method.

The Reference Quality Factor Value transmitted from the RX to the TX in this phase is information used for foreign object detection in the Q-value measurement method, which originally measures the Quality Factor in the frequency domain.

However, when Quality Factor is used as the waveform decay index, although the method of deriving Quality Factor is different, the Quality Factor can also be calculated from the waveform in Figure 9 using Equation 1, for example, using the waveform decay method that measures Quality Factor in the time domain.

Therefore, it is possible to set the threshold value of the Quality Factor of 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 value for foreign matter determination.

In this way, the TX sets the threshold value for the Quality Factor of the waveform attenuation method based on the information already sent from the RX to the TX in the Negotiation phase, eliminating the need to perform new measurements to set the threshold value. As a result, the threshold value can be set in a shorter time. Foreign object determination based on the set threshold value and the measured value of the Quality Factor is as described above.

The third threshold setting method is a method in which the TX measures the waveform attenuation index in the first detection state in which no foreign object is present, and adjusts and determines the threshold based on the information from the measurement result. Below, the timing for pre-measuring the waveform attenuation index in the first detection state is explained. Assume that in the negotiation phase, foreign object detection is performed using the Q-value measurement method, and it is determined that no foreign object is present.

In this case, the system proceeds to the Calibration phase and the Power Transfer phase. In other words, proceeding to the Negotiation phase or later means that the foreign object detection using the Q-value measurement method has determined that no foreign object is present.

There is a high possibility that the waveform attenuation index can be measured in the absence of foreign objects during the Negotiation phase, Calibration phase, or Power Transfer phase.

Therefore, the timing for measuring the waveform attenuation index in the absence of foreign matter may be the Negotiation phase, the Calibration phase, or the Power Transfer phase.

For example, consider the case where the waveform attenuation index is measured in the power transfer phase. The timing for measuring the waveform attenuation index in the absence of a foreign object is set to the first stage of the power transfer phase. The reason for this is that the more time that passes from the point at which the Q-value measurement method determines that there is no foreign object, the higher the probability that a foreign object will be present near the TX and RX.

The timing is specified by either the RX or the TX, and the TX measures the waveform attenuation index at that time and sets the measured value as the threshold. For example, the RX transmits a specified packet to the TX to notify the TX of the timing. After receiving the specified packet from the RX, the TX measures the waveform attenuation index at that time and sets the measured value as the threshold.

The specified packet will be referred to as an execution request packet below. 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 determining foreign matter.

The fourth threshold setting method is one in which the TX adjusts and determines the threshold depending on the transmission power. The value of the waveform attenuation index may differ depending on the transmission power. This is because the amount of heat generated and the characteristics of the TX's electrical circuitry change depending on the transmission power, which affects the value of the waveform attenuation index. Therefore, the TX 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.

FIG. 11 is an explanatory diagram of a threshold setting method for state detection using the waveform attenuation method according to the first embodiment, and is a diagram for explaining a threshold setting method for foreign object determination for each TX transmission power in the waveform attenuation method. In FIG. 11, the horizontal axis represents the transmission power of the power transmitting device 100, and the vertical axis represents the waveform attenuation index (waveform attenuation rate) of the transmission 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.

First, the RX performs control so that the RX is in a light load state when power is transmitted from the TX. A light load state is, for example, a load disconnection state in which no power is supplied to the load of the RX, a load state in which the received power value of the RX is equal to or lower than a first threshold, or a load state in which the received power value of the RX is within a predetermined first range.

The transmission power value of the TX in this state is Pt1. Then, the TX stops transmission in a light load state or reduces the transmission power and measures the waveform attenuation index δ1. At this time, the TX recognizes the transmission power value Pt1, and stores in memory CP1100 that associates the transmission power value Pt1 with the waveform attenuation index δ1.

Next, the RX controls the load connection state. The load connection state is, for example, a maximum load state or a load state in which the transmission power value is equal to or greater than the second threshold. Alternatively, it is a load state in which the power received by the RX is the maximum power. Here, "maximum power" is a power value close to the Reference Power.

Or it is a load state in which the received power value of the RX is within a predetermined second range. Here, the second range is a range of power values higher than the first range. The transmitted power value of the TX in this state is Pt2. Then, the TX stops transmitting power while connected to the load, or reduces the transmitted power, and measures the waveform attenuation index δ2.

At this time, the TX stores in memory CP1101, which associates the transmission power value Pt2 with the waveform attenuation index δ2. Next, the TX generates line segment 1102 by linearly interpolating between CP1100 and CP1101. Line segment 1102 shows the relationship between the transmission power in the first detection state and the waveform attenuation index of the transmission wave.

The TX can therefore estimate the waveform attenuation index of the transmitted wave for each transmitted power value in the first detection state based on line segment 1102. For example, for a transmitted power value Pt3, the waveform attenuation index is estimated to be δ3 from point 1103 on line segment 1102 that corresponds to Pt3. The TX can calculate a threshold value for foreign object determination for each transmitted power value based on the estimation result.

For example, the waveform attenuation index estimated in the first detection state for a certain transmission power value, plus a predetermined value (a value corresponding to the measurement error), can be set as the threshold for determining whether a foreign object is present.

The CAL processing performed by the power transmitting device 100 and the power receiving device 200 to obtain a combination of the transmission power value and the waveform attenuation index is hereinafter referred to as the "CAL processing of the waveform attenuation method." In the above example, measurements were performed at two points, the transmission power values Pt1 and Pt2, but to improve accuracy, measurements may be performed at three or more points to calculate the waveform attenuation index for each transmission power.

The RX may control the light load state and the load connection state after notifying the TX by sending a specified packet. Also, either of the two controls may be performed first.

The calculation process of the foreign object determination threshold for each load (or each transmission power value) may be performed in the calibration phase. As described above, in the calibration phase, the TX acquires the data required for foreign object detection using the Power Loss method.

At that time, the TX acquires data on the received power value and power loss of each RX when the load state of the RX is a light load state and when the load state is connected. Therefore, the measurements of CP1100 and CP1101 in FIG. 11 may be performed together with the measurement of power loss when the RX is in a light load state and when the RX is in a loaded state during the calibration phase.

For example, when the TX receives a signal having first reference received power information from the RX, in addition to the predetermined processing to be performed in the calibration phase, the TX measures CP1100. This first reference received power information is the RP1 information defined in the WPC standard, but other messages may also be used.

Furthermore, when TX receives a signal having second reference received power information from RX, in addition to the predetermined processing to be performed in the calibration phase, it measures CP1101. This second reference received power information is information of RP2, but other messages may be used. Since there is no need to set aside a separate period for measuring CP1100 and CP1101, the measurements of CP1100 and CP1101 can be performed in a shorter time.

In this way, based on the waveform attenuation index measured by the TX at each transmission power, the TX adjusts and sets the threshold value of the waveform attenuation index at each transmission power. For example, when Quality Factor is used as the waveform attenuation index, the TX compares the measured value of Quality Factor with the threshold value determined by the above method.

If the measured value of the Quality Factor is smaller than the threshold, it is determined that "foreign object is present" or "there is a possibility that a foreign object is present." If the measured value of the Quality Factor is equal to or greater than the threshold, it is determined that "no foreign object is present" or "there is a low possibility that a foreign object is present." In this way, thresholds are set for each transmission power of the TX, enabling more accurate foreign object determination.

The number of judgment thresholds set by the above method is not limited to one. Multiple thresholds can be set in stages. For example, the first threshold is set as the judgment threshold for "there is a status abnormality", the second threshold is set as the judgment threshold for "there is a high possibility of a status abnormality", the third threshold is set as the judgment threshold for "there is a low possibility of a status abnormality", and the fourth threshold is set as the judgment threshold for "there is no status abnormality".

In addition, there is a possibility that accuracy cannot be expected by performing the foreign object detection process only once. For example, if a single transmission power control is performed and a foreign object is determined based on the waveform attenuation index, there is a possibility that disturbances will occur in the transmission power waveform during the transmission power control period.

The causes of this are, for example, noise being mixed in during the transmission power control period, or the position of the RX placed on the TX being shifted. If the value of the waveform attenuation index calculated from the transmission waveform during one transmission power control period is not accurate, it may lead to an erroneous judgment in foreign object detection.

The TX then performs multiple transmission power controls, measures the waveform attenuation index from the transmission waveform during multiple transmission power control periods, and is able to perform more accurate foreign object detection based on the results of the multiple measurements.

Next, a method for measuring the coupling state index relating to the power transmitting antenna and the power receiving antenna will be described. First, the first measurement method will be described. In wireless power transmission, power is transmitted by electromagnetically coupling the power transmitting antenna 105 and the power receiving antenna 205.

By passing an alternating current through the transmitting antenna 105 and changing the magnetic flux that penetrates the receiving antenna 205, a voltage is induced in the receiving antenna 205. The coupling coefficient (denoted as k, and its value is called the k value), which is an index of the coupling state, is "k = 1" when, for example, all (100%) of the magnetic flux generated by the transmitting antenna penetrates the receiving antenna.

When 70% of the magnetic flux generated by the transmitting antenna penetrates the receiving antenna, k = 0.7. In this case, the remaining magnetic flux (30%) generated by the transmitting antenna becomes leakage magnetic flux.

This is the magnetic flux generated by the transmitting antenna that did not penetrate the 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 TX to RX is high. Conversely, when the coupling is not good and the k value is small, the transmission efficiency of power transmitted from TX to RX is low.

The k value can decrease if a foreign object (such as a metal piece) gets between the transmitting antenna and the receiving antenna, or if the transmitting antenna and the receiving antenna are misaligned. Or the distance between the transmitting antenna and the receiving antenna becomes too large.

If a foreign object gets between the transmitting antenna and the receiving antenna, heat may be generated in the object. Also, if the transmitting antenna and the receiving antenna are misaligned or separated, there will be a lot of leakage magnetic flux, which may cause a large amount of noise in the surrounding area.

When the k value is small, appropriate control is required to achieve safer and higher quality wireless power transmission. In this embodiment, a process for detecting coupling state indicators related to the transmitting antenna and the receiving antenna is performed to improve the accuracy of detecting foreign objects and the accuracy of detection when the positional deviation or distance is large.

The method for measuring the coupling status indicator of the transmitting antenna and the receiving antenna will be described with reference to Figure 12. Figures 12(A) and (B) are explanatory diagrams of the method for measuring the coupling status indicator of the transmitting antenna and the receiving antenna according to the first embodiment, and Figure 12(A) is an equivalent circuit diagram for explaining the first measurement method. The definitions of various quantities related to the transmitting antenna (transmitting coil) on the primary side (TX) are shown below.

r1: Winding resistance of the transmitting antenna.
L1: Self-inductance of the transmitting antenna.
V1: The transmitting voltage (input voltage) across the transmitting antenna, measured by the TX.

The following are definitions of various quantities related to the receiving antenna (receiving coil) on the secondary side (RX).
r2: Winding resistance of the receiving antenna.
L2: Self-inductance of the receiving antenna.
V2: The receiving voltage (output voltage) across the receiving antenna measured by the RX.

The coupling coefficient k between the power transmitting antenna and the power receiving antenna can be calculated by the following formula 2.
k = (V2/V1) · √(L1/L2) (Equation 2)

When the TX calculates the coupling coefficient k, the RX notifies the TX of the measured receiving voltage V2 and the value of the self-inductance L2 of the receiving antenna that the RX holds in advance. The TX calculates the k value using the measured transmitting voltage V1, the value of the self-inductance L1 of the transmitting antenna that the TX holds in advance, and the receiving voltage V2 and self-inductance L2 values received from the RX.

Alternatively, RX can notify TX of a constant calculated using either or both of L1 and L2, and V2, and TX can calculate the k value using the constant and V2 received from RX, and the transmission voltage V1 measured by TX.

On the other hand, when the RX calculates the coupling coefficient k, the TX notifies the RX of the measured transmission voltage V1 and the previously stored value of the self-inductance L1 of the transmission antenna. The RX calculates the k value using the measured receiving voltage V2, the previously stored value of the self-inductance L2 of the receiving antenna, and the values of the transmission voltage V1 and self-inductance L1 received from the TX.

Alternatively, the TX can notify the RX of a constant calculated using either or both of L1 and L2, and V1, and the RX can calculate the k value using the constant and V1 received from the TX, and the receiving voltage V2 measured by the RX.

The transmission voltage V1 is calculated by the TX actually measuring the voltage applied to the transmission antenna, or by the TX calculating it from the set value of the transmission power. Alternatively, the transmission voltage V1 may be set as the set value of the transmission voltage during transmission.

Furthermore, the transmission voltage V1 applied to the transmission antenna can be obtained from the transmission voltage (denoted as V3) applied to a circuit (e.g., an inverter) in the TX power transmission unit 103 and the voltage across the resonant capacitor 107. Here, the transmission voltage V3 applied to the circuit in the TX power transmission unit 103 is, for example, the inverter input voltage input to the inverter in the TX power transmission unit 103, or the inverter output voltage output by the inverter.

In this case, the TX may also calculate the transmission voltage V3 from the set value of the transmission power. Alternatively, the TX may actually measure the transmission voltage V3 and the voltage across the resonant capacitor 107, and use these to determine the transmission voltage V1. Alternatively, the TX may transmit the measured values of the transmission voltage V3 and the voltage across the resonant capacitor 107 to the RX, and the RX may calculate the transmission voltage V1, thereby calculating the k value.

Also, when the TX or RX performs the first measurement method, the RX may control the third switch unit 213 to be turned OFF so that the terminal of the power receiving antenna 205 is in an open state. This makes it possible to open both ends of the power receiving antenna as shown in FIG. 12(A).

The first measurement method is not affected by the resonant capacitor 211, the power receiving unit 203, the charging unit 206, or the battery 207, so it is possible to measure the coupling coefficient k with higher accuracy. In addition, the power receiving voltage V2 applied to the power receiving antenna can be calculated from the power receiving voltage (denoted as V4) applied to the circuit (e.g., the rectifier) of the RX power receiving unit 203 and the voltage applied across the resonant capacitor 211.

Here, the receiving voltage V4 applied to the circuit of the RX power receiving unit 203 is, for example, the rectifier input voltage input to the rectifier of the RX power receiving unit 203. Alternatively, the receiving voltage V2 applied to the receiving antenna can be calculated from the receiving voltage (or the output voltage of the rectifier) of the circuit (for example, the rectifier) of the RX power receiving unit 203 and the voltage across the resonant capacitor 211.

In this case, RX may actually measure the receiving voltage V4 and the voltage across the resonant capacitor 211, and use these to determine the receiving voltage V2. Alternatively, RX may actually measure the receiving voltage of the rectifier (or the output voltage of the rectifier) and the voltage across the resonant capacitor 211, and use these to determine the receiving voltage V2.

Alternatively, RX may transmit the measured value of the receiving voltage V4 and the voltage across the resonant capacitor 211 to TX, and TX may calculate the receiving voltage V2, thereby calculating the k value. Alternatively, RX may transmit the measured value of the receiving voltage of the rectifier (or the output voltage of the rectifier) and the voltage across the resonant capacitor 211 to TX, and TX may calculate the receiving voltage V2, thereby calculating the k value.

When the TX or RX performs the first measurement method, the RX may be controlled to be in a light load state or a loaded state. By keeping the load state of the RX constant, it becomes possible to measure the coupling coefficient k with higher accuracy. Alternatively, the TX or RX may be controlled to perform the first measurement method in both states when the RX is in a light load state and when it is in a loaded state.

Alternatively, the TX or RX may be controlled so that the first measurement method is performed when the RX is in each of three or more load states. By measuring the coupling state in multiple load states of the RX and determining the coupling state based on the multiple measurement results, the coupling state can be determined with higher accuracy.

In addition to the coupling coefficient, there are several other quantities that can be used as indices to represent the electromagnetic coupling state between the transmitting antenna and the receiving antenna, and in this disclosure, these are collectively referred to as "coupling state indices." Each coupling state index has a value that corresponds to the electromagnetic coupling state between the transmitting antenna and the receiving antenna. The contents of this embodiment can also be applied in the same way when using other coupling state indices other than the coupling coefficient.

For example, there is a method of using the transmission voltage V3 applied to the circuit of the TX power transmitting unit 103 and the receiving voltage V4 applied to the circuit of the RX power receiving unit 203 as the coupling state indicator. Here, V3 is, for example, the inverter input voltage input to the inverter of the TX power transmitting unit 103, or the inverter output voltage output by the inverter.

V4 is, for example, the rectifier input voltage input to the rectifier of the RX power receiving unit 203. These can be used to perform a calculation process for the coupling state between the transmitting antenna and the receiving antenna. Alternatively, the coupling state between the transmitting antenna and the receiving antenna can be calculated using the output voltage (denoted as V5) of a circuit (for example, a rectifier) of the RX power receiving unit 203. The output voltage V5 is the voltage applied to the load (charging unit, battery).

The TX notifies the RX of the transmission voltage V3, and the RX is able to calculate the coupling state index. At this time, the TX notifies the RX of a constant calculated using the electrical characteristics of the transmitting antenna (e.g., L1), and the RX can calculate the coupling state index using the constant.

In other words, the RX can calculate the coupling state index from the transmission voltage V3 received from the TX, a constant calculated using the electrical characteristics of the transmission antenna (e.g., L1) received from the TX, and the receiving voltage V4 or output voltage V5 measured by the RX.

Alternatively, RX notifies TX of receiving voltage V4 or output voltage V5, and TX calculates the value of the coupling state index. At this time, RX notifies TX of a constant calculated using the electrical characteristics of the receiving antenna (e.g., L2), and TX can calculate the coupling state index using the constant.

In other words, the TX can calculate the coupling state index from the receiving voltage V4 or output voltage V5 received from the RX, a constant calculated using the electrical characteristics of the receiving antenna received from the RX (e.g., L2), and the transmitting voltage V3 measured by the TX.

The TX and RX exchange information such as the voltage values V1 to V5, the self-inductance values L1 and L2, or constants that represent the electrical characteristics of the transmitting and receiving antennas. The timing of measuring the voltage values and the timing of sending and receiving each piece of information are explained below. Measurement of each voltage value is performed, for example, during the Ping phase. During the Ping phase, the TX transmits a DP to the RX.

Therefore, any of the voltage values V1, V2, V3, V4, and V5 that are generated when transmitting a DP can be used. In the Ping phase, the TX and RX measure any of the values V1 to V5 and store and retain the value in memory 106 or memory 208. Alternatively, the TX transmits a specified packet to the RX to notify it of the timing of measuring the voltage value.

When the RX receives the specified packet, it measures the voltage value of either V2, V4, or V5. The RX measures the value of either V2, V4, or V5 and stores it in memory 208.

Alternatively, the RX transmits a specified packet to the TX to notify it of the timing for measuring the voltage value. When the TX receives the specified packet, it measures the voltage value of either V1 or V3. The TX measures either the value of V1 or V3 and stores it in the memory 106.

The following describes a case where the TX receives information on the voltage value of either V2, V4, or V5 from the RX. The TX transmits a specified transmission request packet to the RX to request the transmission of a packet containing information on the voltage value of either V2, V4, or V5.

When RX receives the transmission request packet, it transmits a specified packet containing information on one of the voltage values V2, V4, or V5 to TX. TX receives the specified packet containing information on one of the voltage values V2, V4, or V5 notified by RX, and stores the information in memory 106.

The information contained in the specified packet may include not only the receiving voltage of the RX, but also the receiving power, the requested receiving power value, the value of the self-inductance L2, a constant calculated using the electrical characteristics of the receiving antenna, etc. Also, information regarding the temperature of the RX may be included.

The TX receives the information from the RX and can use the information and the calculated coupling status index to perform more appropriate control. As the specified packet, the Signal Strength Data packet can be used to notify the TX of the RX's information.

Alternatively, the specified packet may be an Identification Data packet or an Extended Identification Data packet in the I&C phase. Or it may be a Configuration Data packet.

Alternatively, it may be a packet in the calibration phase or 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 TX uses the voltage value generated when transmitting DP.

Any of the voltage values V1 to V5 that are generated when the TX transmits to the AP during the Selection phase may be used. Alternatively, any of the voltage values V1 to V5 that are generated when the TX transmits power to the RX during the Power Transfer phase may be used.

Next, we will describe the case where RX receives information on either the voltage value V1 or V3 from TX. RX transmits a specified transmission request packet to TX to request the transmission of a packet including information on either the voltage value V1 or V3.

When the TX receives the transmission request packet, it transmits a specified packet containing information on either the V1 or V3 voltage value to the RX. The RX receives the specified packet containing information on either the V1 or V3 voltage value transmitted by the TX, and stores the information in memory 208.

The information contained in the specified packet may include not only the TX voltage, but also the transmitted power value, the transmittable power value, the value of the self-inductance L1, a constant calculated using the electrical characteristics of the transmitting antenna, and other information.

Alternatively, the information may include the results of foreign object detection using the foreign object detection methods described above (power loss method, Q-value measurement method, waveform attenuation method) and information regarding the temperature of the TX. The RX can receive this information from the TX and use this information and the calculated binding state index to perform more appropriate control.

Furthermore, as a specified packet, the Power Transmitter Capabilities (CAP) Data Packet can be used to notify the RX of TX information. Alternatively, the Power Transmitter Identification (ID) data packet can be used to notify the RX of TX information.

Note that this is not limited to the example where the voltage value generated when the TX transmits the DP is used. Any of the voltage values V1 to V5 generated when the TX transmits the AP in the Selection phase may be used. Alternatively, any of the voltage values V1 to V5 generated when the TX transmits power to the RX in the Power Transfer phase may be used.

When performing the first measurement method, the RX may control the third switch section 213 between the resonant capacitor 211 and the power receiving section 203 to be turned OFF, so that the terminal of the circuit formed by the power receiving antenna 205 and the resonant capacitor 211 is in an open state.

As a result, the coupling state index can be measured with higher accuracy since the first measurement method is not affected by the power receiving unit 203, the charging unit 206, or the battery 207. Alternatively, when the first measurement method is performed, the RX may control the load so that the above-mentioned light load state is achieved.

When implementing the first measurement method, the RX may control the load so that the load is in the load connection state described above. This makes it possible to measure the coupling state index while maintaining the load state in a specified state, enabling more accurate state detection.

Next, a second measurement method will be described as another example of a method for measuring the coupling state indicator between the transmitting antenna and the receiving antenna. 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 various quantities related to the transmitting antenna (coil) on the primary side (TX) are defined below.

V6: Input voltage (transmission voltage) of the transmission antenna when the receiving antenna side is shorted.
V7: Input voltage (transmission voltage) of the transmission antenna when the receiving antenna side is in an open state.
I1: The current flowing through the transmitting antenna when the receiving antenna is shorted.
I2: The current flowing through the transmitting antenna when the receiving antenna is in an open state.

The coupling coefficient k can be calculated by the following formula 3.
k = √(1-Lsc/Lopen) (Equation 3)

Lsc in Equation 3 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 sets the third switch unit 213 and the second switch unit 210 to the ON state (short-circuit state).

In this state, the Lsc value can be obtained by measuring the inductance value of the transmitting antenna. The inductance value of the transmitting antenna can be calculated from the input voltage V6 and current I1 of the transmitting antenna.

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 transmitting antenna can be determined from the input voltage V7 and current I2 of the transmitting antenna. In the second measurement method, the coupling state index (coupling coefficient) can be determined from the input voltage and current of the transmitting antenna when both ends of the receiving antenna are short-circuited and open.

TX can also calculate the coupling state index based on the transmission voltage and current applied to a circuit (e.g., an inverter) in the power transmitting unit 103. In this case, the input voltages V6 and V7 represent the transmission voltage applied to a circuit (e.g., an inverter) in the power transmitting unit 103.

Here, the transmission voltages V6 and V7 applied to the circuit included in the power transmission unit 103 of the TX 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 transmission antenna and a resonant capacitor.

Alternatively, the transmission voltage applied to a circuit (e.g., an inverter) in the power transmitting unit 103 and the voltage across the resonant capacitor 107 can be measured, and the voltage applied to the power transmitting antenna can be calculated from the results.

In other words, it is possible to obtain the coupling state index from the measurement results of the transmission voltage applied to the circuit (e.g., inverter) of the power transmitting unit 103 and the voltage applied to both ends of the resonant capacitor 107. In this case, the transmission voltage applied to the circuit (e.g., inverter) of the power transmitting unit 103 may be calculated by the TX from the set value of the transmission power.

In FIG. 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 TX is, for example, an inverter input current or an inverter output current.

The open and short states of the power receiving antenna have been described as examples in which the control unit 201 realizes these states by controlling the second switch unit 210 and the third switch unit 213. These states may also be realized by the power receiving unit 203. Also, instead of the short state, a Light Load state may be used. Also, instead of the open state, a Connected Load state may be used.

In the second measurement method, the TX can calculate the coupling state index by measuring the input voltages V6 and V7 and the currents I1 and I2. Therefore, information such as the voltage value measured by the RX or the inductance value of the receiving antenna is not required, so there is no need for the RX to notify the TX of this information.

However, when the TX measures the input voltage V6 and the current I1, the RX needs to keep both terminals of the circuit that includes the receiving antenna in SHORT. Also, when the TX measures the input voltage V7 and the current I2, the RX needs to keep both terminals of the circuit that includes the receiving antenna in OPEN.

In other words, depending on the timing when the TX measures the input voltage and current, the RX needs to control both terminals of the circuit that contains the receiving antenna to a SHORT or OPEN state. The TX (or RX) decides the measurement timing and notifies the RX (or TX).

The RX also notifies the TX when it has completed the control of setting both terminals of the circuit containing the receiving antenna to the SHORT or OPEN state. This notification is performed by communication based on the WPC standard between the first communication unit 104 of the TX and the first communication unit 204 of the RX, or by communication based on a standard other than the WPC standard between the second communication unit 109 of the TX and the second communication unit 212 of the RX.

The input voltages V6, V7 and currents I1, I2 are measured, for example, in the Ping phase. In the Ping phase, the TX transmits a DP to the RX. Therefore, the values of V6, V7 and currents I1, I2 generated when transmitting the DP can be used. In the Ping phase, the TX acquires the values of V6, V7, I1, I2, stores them in memory 106, and calculates the coupling state index.

Note that this is not limited to the example where the voltage and current values generated when the TX transmits a DP are used. For example, the values of V6, V7, I1, and I2 generated when the TX transmits an AP in the Selection phase may be used. Alternatively, the voltage values of V6, V7, I1, and I2 generated when the TX transmits power to the RX in the Power Transfer phase may be used.

In this disclosure, either the first or second measurement method can be applied to the method of measuring the coupling status index of the transmitting antenna and the receiving antenna. Below, a method of setting a status determination threshold for the coupling status index obtained by the first or second measurement method is described.

The status determination includes a determination regarding the detection of a foreign object between the power transmitting antenna and the power receiving antenna, a determination regarding the detection of a misalignment between the power transmitting antenna and the power receiving antenna, and a determination regarding the detection of the separation between the power transmitting antenna and the power receiving antenna. By implementing the first or second measurement method, it is possible to determine the presence or absence of a status abnormality using a status determination threshold. The first to fourth threshold setting methods are described below.

The first threshold setting method is to set the value of the coupling status index when there is no status abnormality as the threshold. In status detection, for example, a judgment result such as "status abnormality exists", "status abnormality is highly likely", "status abnormality is low", "no status abnormality" or the like is obtained. Assume that the RX is placed on the test TX and there is no status abnormality between the transmitting antenna and the receiving antenna.

In this case, the value of the coupling state index between the test TX including the transmitting antenna and the RX including the receiving antenna can be set as the threshold. The value of the coupling state index (threshold) measured in advance is stored in the memory of the RX, and the RX notifies the TX of the threshold.

The TX uses this threshold value to perform a judgment process regarding status detection. The RX may transmit this threshold value to the TX within an FOD Status Data packet defined in the WPC standard. Alternatively, when the RX performs a judgment process regarding status detection, the RX uses this threshold value to perform the judgment process regarding status detection.

Alternatively, the value of the coupling state index of the power transmitting antenna and the power receiving antenna that provides a predetermined power transmission efficiency is set as the threshold value. The determination result regarding the state detection is, for example, as follows.

(A1) "The specified power transmission efficiency cannot be obtained" or "The coupling state between the transmitting antenna and the receiving antenna is not good."
(A2) "There is a high possibility that the specified power transmission efficiency cannot be obtained" or "The coupling state between the transmitting antenna and the receiving antenna may not be good."
(A3) "There is a high possibility that a specified power transmission efficiency can be obtained" or "There is a high possibility that the coupling state between the transmitting antenna and the receiving antenna is good."
(A4) "A predetermined power transmission efficiency is obtained" or "The coupling state between the transmitting antenna and the receiving antenna is good."

Assume that the RX is placed on the test TX and there is no abnormality in the state between the transmitting antenna and the receiving antenna (A4). In this case, the value of the coupling state index between the test TX including the transmitting antenna and the RX including the receiving antenna can be set as the threshold. The RX holds the value of the coupling state index measured in advance in its memory as the threshold, and notifies the TX of the threshold.

The second threshold setting method is a method in which the TX and RX set the coupling state index measured by the first or second measurement method as the threshold when there is no abnormality between the transmitting antenna and the receiving antenna. The method for confirming this state can utilize a state detection means for the TX and RX related to foreign object detection by the power loss method, foreign object detection by the waveform attenuation method, foreign object detection by the Q value measurement method, foreign object detection based on the temperature of the TX or RX, etc.

If it is determined that there is no abnormal condition as a result, it can be confirmed with a high probability that there is no abnormal condition. In other words, this confirmation is performed by a method and means other than the first or second measurement method. If it is determined that there is no abnormal condition (or no foreign matter) as a result, the bond condition index is measured using the first or second measurement method, and an appropriate threshold value is set based on the measurement result.

For example, in the WPC standard, a foreign object detection process using a Q-value measurement method is executed in the Negotiation phase or Renegotiation phase. If the result of the foreign object detection process is that there is "no abnormal state" (or "no foreign object"), the bond state index is measured using the first or second measurement method after the Negotiation phase or Renegotiation phase.

Based on the measurement results, the TX or RX can set a more appropriate threshold value. Furthermore, the foreign object detection process using the Power Loss method is executed during the Power Transfer phase. After the foreign object detection process is executed, the binding state index is measured using the first or second measurement method, and based on the measurement results, a more appropriate threshold value can be set.

Alternatively, the TX can measure the Quality Factor by the waveform attenuation method using the AP or DP transmitted by the TX in the Selection phase or Ping phase, and execute the foreign object detection process. In this case, the binding status index is measured using the first or second measurement method after the phase in which the foreign object detection process is executed, and an appropriate threshold can be set based on the measurement result.

Alternatively, the foreign object detection process using the waveform attenuation method is performed during the power transfer phase. After the foreign object detection process is performed, the binding state index is measured using the first or second measurement method, and a more appropriate threshold value can be set based on the measurement result.

Next, the third threshold setting method will be described with reference to FIG. 13. FIG. 13 is a diagram for explaining the threshold setting method for state detection using the coupling state index according to the first embodiment. In FIG. 13, the horizontal axis represents the transmission power, and the vertical axis represents the coupling state index. On the graph line represented by the straight line segment 1202, point 1200 corresponds to the transmission power value Pt1 and the coupling state index value k1, and point 1201 corresponds to the transmission power value Pt2 and the coupling state index value k2.

On the graph line, point 1203 corresponds to the transmission power value Pt3 and the coupling state index value k3. Below, an example is shown in which the receiving voltage V4 or the output voltage V5 applied to a circuit (e.g., a rectifier) of the receiving unit 203 of the RX is used to calculate the coupling state index value in the first measurement method.

As shown in FIG. 3, the charging unit 206 and the battery 207 are connected as loads to the RX power receiving unit 203. The calculated coupling state index value changes depending on the load state. In order to determine the presence or absence of a state abnormality depending on the load state, it is necessary to set an appropriate threshold value for the coupling state index.

First, when power is transmitted from TX, RX controls the load so that it is in a light load state. A light load state is, for example, a load disconnection state, a load state in which the received power value of RX is equal to or lower than a first threshold, or a load state in which the received power value of RX is within a first predetermined range. The transmitted power value in this state is Pt1.

In this state, the TX and RX measure the transmission voltage on the TX side and the receiving voltage on the RX side. The TX and RX exchange information such as the above values of V1 to V7, the values of self-inductance L1 and L2, or constants calculated using the electrical characteristics of the transmitting antenna and the receiving antenna, and the TX or RX calculates the coupling state index value k1.

At this time, the TX recognizes the transmission power value Pt1, and stores in memory CP1200 that associates Pt1 with k1. Next, the RX controls the load of the RX so that it is in a load connection state when power is transmitted from the TX. The load connection state is, for example, a maximum load state or a load state in which the transmission power value is equal to or greater than a second threshold value.

The transmission power value of the TX in this state is Pt2. In this state, the TX and RX measure the transmission voltage on the TX side and the receiving voltage on the RX side. The TX and RX exchange information such as the values of V1 to V7 mentioned above, the values of self-inductances L1 and L2, or constants calculated using the electrical characteristics of the transmitting antenna and receiving antenna, and the TX or RX calculates the coupling state index value k2.

The TX stores in memory CP1201, which associates Pt2 and k2. Next, the TX performs linear interpolation between CP1200 and CP1201 to generate line segment 1202. Line segment 1202 shows the relationship between the transmission power and the coupling state index when there is no state abnormality.

The TX can use line segment 1202 to estimate the coupling state index value for each transmission power value when there is no abnormal state. For example, assume that the transmission power value is Pt3. In this case, the coupling state index value can be estimated to be k3 from point 1203 on line segment 1202 that corresponds to the transmission power value Pt3. Based on the estimation result, the TX can calculate a threshold value to be used to determine the presence or absence of an abnormal state for each transmission power value.

For example, the coupling state index value obtained by adding a predetermined value (a value corresponding to the measurement error) to the estimated result of the coupling state index value when there is no abnormality at a certain transmission power value can be set as the judgment threshold value.

The CAL processing performed by the power transmitting device 100 and the power receiving device 200 in this manner so that the power transmitting device 100 can obtain a combination of the transmitted power value and the coupling state index value is referred to as the "CAL processing of the coupling state index measurement method."

The RX may control the load to a light load state and to a load connected state after notifying the TX that it will perform these controls. Also, either of these two controls may be performed first.

The operation for calculating the judgment 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 TX acquires the data required for foreign object detection using the Power Loss method.

At that time, the TX acquires data on the amount of power loss when the RX is in a light load state and when the RX is in a loaded state. Therefore, the measurements of CP1200 and CP1201 in FIG. 13 can be performed together with the measurement of power loss when the RX is in a light load state and when it is in a loaded state during the calibration phase.

In other words, when the TX receives the first reference received power information from the RX, it measures CP1200 in addition to the predetermined processing to be performed in the calibration phase. The first reference received power information is information from RP1, but other messages may be used. Also, when the TX receives the second reference received power information from the RX, it measures CP1201 in addition to the predetermined processing to be performed in the calibration phase.

The second reference received power information is information from RP2, but other messages may 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.

Alternatively, when the RX performs a determination process regarding state detection, the RX receives a specified packet including the above-mentioned Pt1 information from the TX. Then, when the RX receives the specified packet including the Pt1 information, it measures k1 and stores in memory CP1200 that associates Pt1 with k1.

Similarly, RX receives a specific packet containing the above Pt2 information from TX. Then, when RX receives a specific packet containing Pt2 information, it measures k2 and stores CP1201, which associates Pt2 with k2, in memory. Next, RX performs linear interpolation between CP1200 and CP1201 to generate line segment 1202.

The RX can use line segment 1202 to estimate the coupling state index value for each transmission power value in a state where there is no abnormality. In this way, the power receiving device 200 can obtain the combination of the transmission power value and the coupling state index value of the power transmitting device 100.

The fourth threshold setting method is a method in which the TX or RX sets a threshold in advance for a coupling state indicator having a value within a predetermined range. This threshold is a common value that is not dependent on the RX to which power is transmitted, and the TX or RX holds a predetermined value. Note that the threshold is a fixed value that is independent of the situation, or a variable value that is determined by the TX or RX depending on the situation.

For example, if the coupling coefficient k is used as the coupling status index, the range of the k value is "0≦k≦1". For example, TX or RX will determine that "there is a status abnormality" when "0≦k<0.2", and will determine that "there is a high possibility of a status abnormality" when "0.2≦k<0.5".

TX or RX will determine that "the possibility of a status abnormality is low" if "0.5≦k<0.8" and will determine that "there is no status abnormality" if "0.8≦k≦1". Data on the conditions for the k value is stored in memory in advance, and the determination process is carried out based on the conditions.

For example, TX or RX will determine the above (A1) if "0≦k<0.2", the above (A2) if "0.2≦k<0.5", the above (A3) if "0.5≦k<0.8", and the above (A4) if "0.8≦k≦1".

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 the binding state index value calculated based on the measurement results or received information can also be set as the judgment threshold. As mentioned above, the threshold is not limited to one, and multiple thresholds can be set in stages.

Next, the timing for calculating the coupling status indicator using the first or second measurement method will be described. The coupling status indicator measurement is performed by the RX transmitting a specified packet to the TX. The specified packet is a Signal Strength Data packet transmitted from the RX to the TX.

Or it may be an Identification Data packet, Extended Identification Data packet, or Configuration Data packet in the I&C phase. Or it may be a packet in the Calibration phase or Power Transfer phase. In other words, it may be RP1, RP2, or RP0.

When the TX receives the above-mentioned specified packet from the RX, it calculates the binding status index. The TX makes a judgment by comparing the judgment threshold set by the above-mentioned method with the calculated binding status index value. If the TX judges that there is no abnormal status, it sends a positive response ACK to the RX.

Alternatively, TX transmits status information to RX that means "no status abnormality." Also, if TX determines that "the possibility of a status abnormality is low," it transmits status information to RX that means "the possibility of a status abnormality is low."

If the TX judges that "there is a high possibility of a status abnormality," it will send status information to the RX indicating that "there is a high possibility of a status abnormality." If the TX judges that "there is a status abnormality," it will either send a negative acknowledgement NAK to the RX, or send status information to the RX indicating that "there is a status abnormality."

Alternatively, if the TX judges that the above is (A4), it transmits an ACK acknowledgement to the RX, or transmits status information corresponding to the judgment result to the RX. Also, if the TX judges that the above is (A3) or (A2), it transmits status information corresponding to the judgment result to the RX.

If the TX judges that the above (A1) is true, it either transmits a negative acknowledgement (NAK) to the RX, or transmits status information corresponding to the judgment result to the RX. For example, the status information is numerical information according to the status.

For example, in the case of (A4) above, it is set to "0", in the case of A(3) above, it is set to "1", in the case of (A2) above, it is set to "2", and in the case of (A1) above, it is set to "3", and the TX transmits the status information (level) expressed as a numerical value to the RX. Alternatively, when the coupling status indicator measurement is performed by the RX, it is executed by the TX transmitting a specified packet to the RX.

When the TX receives a request packet from the RX requesting transmission of the specified packet, the TX may transmit the specified packet. When the RX receives the specified packet from the TX, the RX calculates a binding status index. The RX makes a judgment by comparing the judgment threshold set by the above-mentioned method with the calculated binding status index value.

If RX determines that there is no abnormal status, it transmits status information to TX that means there is no abnormal status. If RX determines that there is a low possibility of an abnormal status, it transmits status information to TX that means there is a low possibility of an abnormal status. If RX determines that there is a high possibility of an abnormal status, it transmits status information to TX that means there is a high possibility of an abnormal status.

If RX determines that "there is an abnormal status", it transmits status information meaning "there is an abnormal status" to RX. Alternatively, RX transmits status information corresponding to the determination result to TX. For example, the status information is numerical information according to the status. For example, in the case of (A4) above, it transmits "0", in the case of A(3) above, it transmits "1", in the case of (A2) above, it transmits "2", and in the case of (A1) above, it transmits "3", and the status information (level) expressed as a numerical value to TX.

Methods for detecting foreign objects include the power loss method, the Q-factor measurement method, the waveform attenuation method, and methods based on the temperature measured by the power transmitting device 100 and the electromagnetic coupling state (e.g., the coupling coefficient) between the power transmitting antenna 105 and the power receiving antenna 205.

When detecting foreign objects using the waveform decay method in a power transmission device with multiple power transmission antennas, it is necessary to appropriately control the preparation period, power transmission power control period, communication prohibition period, and power transmission period. Below, we explain an example of how to set each period in the waveform decay method and how to determine the appropriate time for each period.

First, the methods for determining the preparation period will be explained. The first method is for the TX to set the length (time) of the preparation period to a predetermined value. In this case, the RX also holds in advance a predetermined value which is the length (time) of the preparation period. The second method is for the TX (or RX) to determine the length of the period to a predetermined value depending on the state of the device itself and notify the RX (or TX).

The third method is for TX and RX to communicate with each other and determine the length of the period to a predetermined value. For example, TX (or RX) notifies RX (or TX) of the determined maximum time. RX (or TX) notifies TX (or RX) of the determined minimum time. RX (or TX) determines a value within the range set by TX and RX and notifies TX (or RX).

The fourth method is to set the length of the preparation period to a different predetermined value for each transmitting antenna involved in the execution of the waveform attenuation method. The fifth method is to set the length of the preparation period to the same value for multiple transmitting antennas involved in the execution of the waveform attenuation method. By setting the length of the preparation period to an appropriate time, it is possible to suppress waveform disturbance during the transmission power control period.

Next, a method for determining the transmission power control period will be described. As with the third method above, the length of the transmission power control period is determined by negotiation between the RX and the TX. For example, the TX (or RX) determines the minimum time that can be set as the transmission power control period and notifies the RX (or TX).

The RX (or TX) also determines the maximum time that can be set as the transmission power control period and notifies the TX (or RX). In addition, the RX (or TX) determines the minimum time that can be set as the transmission power control period and notifies the TX (or RX). The TX or RX determines the time within the settable range based on the times notified to each other. The optimal transmission power control period can be set within the determined time range.

When determining the optimal transmission power control period, the TX (or RX) notifies the RX (or TX) of the length of the determined transmission power control period using a specified packet. The specified packet by which the RX notifies the TX of the length of the determined transmission power control period may be an execution request packet (e.g., a Received Power Data Packet).

As a result of the negotiation, the TX or RX determines the length of the transmission power control period to be the minimum time within the range set by both devices. The greater the difference in power between the power immediately before transmission resumes and the transmission power at the time transmission resumes, the greater the ringing that occurs. Therefore, the above-mentioned method makes it possible to suppress ringing that occurs in the transmission waveform at the time transmission resumes.

Alternatively, the TX or RX may determine the maximum time within the range set by both devices as the length of the transmission power control period. In this way, the attenuation state of the transmitted radio wave can be observed for a longer period of time, enabling highly accurate foreign object detection.

The content of the negotiation is not limited to the above example. For example, the TX (or RX) notifies the RX (or TX) of the range of time that the device itself can set. The RX (or TX) then decides on the time.

In addition, information for determining the length of the transmission power control period may be included in the execution request packet (e.g., Received Power Data Packet). Alternatively, a predetermined value may be set as the length of the transmission power control period. Alternatively, the TX (or RX) may determine a predetermined value depending on the state of the device and notify the RX (or TX).

Next, the relationship between the transmission power by TX and the transmission power control period will be explained. TX or RX is determined so that the transmission power control period is shorter when the transmission power of TX is large than when it is small. When transmission is resumed after the transmission power control period, ringing occurs in the transmission waveform at the point where transmission is resumed. The greater the difference in level between the power immediately before transmission is resumed and the transmission power at the time transmission is resumed, the greater the ringing that occurs.

Therefore, in order to reduce ringing, it is necessary to reduce the difference in level between the power just before transmission resumes and the transmitted power when transmission resumes. By shortening the transmission power control period, transmission resumes with little attenuation of the transmitted radio wave, which results in a smaller difference in level and makes it possible to suppress ringing. Similarly, the higher the transmission power, the smaller the difference in level can be made by shortening the transmission power control period, making it possible to suppress ringing.

On the other hand, when the measurement accuracy of the waveform attenuation index is prioritized, there is a method of determining a longer transmission power control period as the transmission power is higher. For example, the higher the transmission power, the higher the risk of a foreign object being present, so more accurate foreign object detection is required. Therefore, when the transmission power is greater than a predetermined value, the transmission power control period is made longer so that the attenuation state can be observed for a long period of time.

This makes it possible to increase the accuracy of measuring the attenuation state and improve the accuracy of the waveform attenuation index. In addition, whether to lengthen or shorten the transmission power control period depending on the magnitude of the transmission power may be determined based on a user specification, etc. The TX or RX can determine the length of the transmission power control period based on the magnitude of the transmission power.

In the above explanation, the magnitude of the transmission power of TX is taken as an example, but this may be replaced with the following power.
・Guaranteed Load Power
・Requested Load Power
・Potential Load Power
・Negotiable Load Power
・Maximum Power Value
・Reference Power

The length of the transmission power control period can be determined based on the magnitude of the setting value for the transmission power determined by negotiation between the TX and the RX. Alternatively, the length of the transmission power control period may be determined based on information stored in RP0, RP1, or RP2 that the RX transmits to the TX.

The Received Power Data Packet stores received power value information that indicates the amount of power received by the RX from the TX. The information on the transmitted power of the TX may be replaced with this received power value information. Alternatively, the information on the transmitted power of the TX may be replaced with the load power consumption consumed by the load of the RX.

Next, the relationship between the electromagnetic coupling state between the transmitting antenna 105 and the receiving antenna 205 and the transmission power control period will be described. The coupling state index of both antennas can be measured by the above-mentioned coupling state index measurement method or other measurement methods. TX or RX is determined so that the transmission power control period is longer when the coupling state between the transmitting antenna 105 and the receiving antenna 205 is not good than when the state is good.

For example, a good bonding state is one in which a comparison of the measured k value with a threshold value results in a determination of "no abnormal condition." A bad bonding state is one in which a comparison of the measured k value with a threshold value results in a determination of "possible abnormal condition" or "abnormal condition."

If the antenna coupling state is not good, there is a possibility that a foreign object is present between the transmitting antenna 105 and the receiving antenna 205, so highly accurate foreign object detection is required. If the coupling state index value is not within a specified range, the transmission power control period is extended and the attenuation state is observed for a long period of time.

This makes it possible to increase the accuracy of the attenuation state measurement and improve the accuracy of the waveform attenuation index. Alternatively, if the measurement accuracy of the waveform attenuation index is given priority, there is a method in which when the coupling state is not good (when the electromagnetic coupling is weak), the transmission power control period is lengthened according to the degree of the poor coupling state.

On the other hand, when priority is given to power transmission efficiency, one method is to determine a shorter transmission power control period according to the coupling state index, the weaker the antenna coupling. The weaker the antenna coupling, the lower the power transmission efficiency. When antenna coupling is weak, shortening the transmission power control period makes it possible to secure a longer period during which power can be transmitted, improving power transmission efficiency.

In addition, the measurement of the coupling state index between the transmitting antenna 105 and the receiving antenna 205 may be performed multiple times at a predetermined timing before or after the start of TX power transmission. When performing multiple measurements at a predetermined timing after the start of power transmission, the length of the transmission power control period may be changed based on each measurement result.

For example, the TX performs measurements three times at a predetermined timing after starting power transmission. If the measured coupling state index values are all different, the length of the transmission power control period is changed three times. There is also a method of determining whether to lengthen or shorten the transmission power control period depending on the coupling state, based on user specifications, etc. The TX or RX can determine the length of the transmission power control period based on the value of the coupling state index.

Next, the relationship between the frequency of the electromagnetic waves (hereinafter referred to as transmission radio waves) radiated from the transmitting antenna 105 to the receiving antenna 205 for power transmission and the transmission power control period will be described. TX or RX is determined so that the transmission power control period is longer when the frequency of the transmission radio waves is low than when it is high. The frequency of the transmission radio waves is the frequency of the electromagnetic waves radiated from the transmitting antenna 105 to the receiving antenna 205 for power transmission during the power transmission period.

In general, the higher the frequency of the electromagnetic waves, the greater the loss. Therefore, the higher the frequency of the transmitted radio waves, the greater the attenuation rate of the electromagnetic waves during the transmission power control period, and the steeper the attenuation. On the other hand, the lower the frequency of the electromagnetic waves, the smaller the attenuation rate of the electromagnetic waves during the transmission power control period, and the more gradually they attenuate.

Furthermore, the higher the frequency of the transmitted radio waves, the shorter the wavelength of the electromagnetic waves during the transmission power control period. This makes it possible to shorten the time difference between points 601 and 602 in FIG. 10, and makes it possible to calculate the attenuation rate in a shorter time. On the other hand, the lower the frequency of the electromagnetic waves, the longer the wavelength of the electromagnetic waves during the transmission power control period.

The time difference between points 601 and 602 in Figure 10 becomes longer, and it takes longer to calculate the attenuation rate. Therefore, the lower the frequency of the transmitted radio waves, the longer the transmission power control period can be set, allowing the attenuation state to be observed for a longer period of time. This increases the accuracy of measuring the attenuation state and improves the accuracy of the waveform attenuation index.

From another perspective, there is a method of shortening the transmission power control period as the frequency of the transmission radio waves is lower. The lower the frequency of the transmission radio waves, the more stable the waveform of the electromagnetic waves. On the other hand, the higher the frequency of the electromagnetic waves, the more susceptible the electromagnetic waves are to the influence of objects around the power transmitting antenna 105, and the more likely it is that the waveform of the electromagnetic waves will become unstable.

Therefore, when the frequency of the transmitted radio waves is high, the attenuation state can be observed for a long period of time by making the transmission power control period longer. This increases the accuracy of measuring the attenuation state and improves the accuracy of the waveform attenuation index.

For example, the frequency of the electromagnetic waves used for power transmission in the WPC standard is between 87 kHz and 205 kHz. If the frequency of the transmitted radio waves varies between 87 kHz and 205 kHz, the transmission power control period may be controlled according to the frequency.

Alternatively, if the frequency of the transmission radio waves is within a predetermined first frequency band (e.g., 87 kHz to 205 kHz), a first transmission power control period is set. If the frequency is within a second frequency band different from the first frequency band, a second transmission power control period having a different length from the first transmission power control period is set.

There is also a method of determining whether to lengthen or shorten the transmission power control period based on user specifications, etc., depending on the frequency of the transmission radio waves. The TX or RX can determine the length of the transmission power control period based on the frequency of the transmission radio waves.

Next, the relationship between the Quality Factor of the transmitting antenna 105 and the transmission power control period will be described. The Quality Factor of the transmitting antenna 105 can be obtained by a Q-factor measurement method or other measurement method. TX or RX is determined so that the transmission power control period is shorter when the Quality Factor of the transmitting antenna 105 is low than when it is high.

The lower the Quality Factor, the greater the waveform attenuation rate during the transmission power control period when the waveform attenuation method is executed. In this case, the amplitude of the transmission wave waveform during the transmission power control period becomes smaller in a short period of time when the Quality Factor is low than when the Quality Factor is high.

Therefore, the TX or RX shortens the transmission power control period when the Quality Factor is low rather than when it is high. This makes it possible to reduce the difference in transmission power when transmission resumes, making it possible to suppress ringing.

On the other hand, when priority is given to the accuracy of foreign object detection, there is a method of determining a longer transmission power control period as the Quality Factor for the transmitting antenna 105 is lower. The lower the Quality Factor, the smaller the amplitude of the transmitted wave during the transmission power control period becomes in a short period of time.

When the amplitude of the transmission wave becomes smaller, the transmission waveform becomes more susceptible to the effects of surrounding noise, etc., and there is a possibility that the transmission waveform may become distorted. Therefore, when the Quality Factor is low, the transmission power control period can be lengthened to ensure a longer period during which the attenuation state of the transmission wave can be observed. This improves the accuracy of foreign object detection.

In addition, the quality factor of the transmitting antenna 105 may be measured multiple times at a predetermined timing before or after the start of power transmission by the TX. When the TX performs measurements multiple times at a predetermined timing after the start of power transmission, the transmission power control period can be changed based on each measurement result.

For example, the TX performs measurements three times at a specified timing after starting power transmission. If the measured Quality Factors are all different, the length of the transmission power control period is changed three times. There is also a method of determining whether to lengthen or shorten the transmission power control period depending on the Quality Factor, based on user specifications, etc. The TX or RX can determine the length of the transmission power control period based on the Quality Factor.

Next, we will explain how to determine the communication prohibition period. The purpose of setting the communication prohibition period is to prevent communication from occurring when ringing occurs in the transmission waveform after power transmission is resumed. The length of the communication prohibition period is determined by the TX, who sets the length (time) of the communication prohibition period to a predetermined value.

In this case, RX also holds in advance a predetermined value which is the length (time) of the communication prohibition period. Alternatively, RX (or TX) determines the length of the communication prohibition period to a predetermined value and notifies TX (or RX). Alternatively, RX (or TX) may determine the length of the communication prohibition period to a predetermined value depending on the state of the device and notify TX (or RX).

Alternatively, the TX and RX may communicate with each other and determine the length of the communication prohibition period to a predetermined value. Alternatively, the TX may notify the RX of the maximum time (or minimum time) that it has determined, and the RX may notify the TX of the minimum time (or maximum time) that it has determined. The TX or the RX may determine the length of the communication prohibition period within a range set by the TX and the RX.

TX (or RX) notifies RX (or TX) of the determined length of the communication prohibition period using a specified packet. The specified packet may be an execution request packet (Received Power Data Packet). For example, within the range set by TX and RX, TX or RX determines the shortest time as the length of the communication prohibition period.

This lengthens the time during which communication is possible, enabling high-speed communication and faster control. Alternatively, within the range set by TX and RX, TX or RX may determine the maximum time as the length of the communication prohibition period.

This allows communication to take place after the ringing has subsided, which is effective in stabilizing communication. In addition, information for determining the length of the communication prohibition period may be included in the execution request packet (Received Power Data Packet).

Next, the relationship between the TX transmission power and the communication prohibition period will be explained. TX or RX is determined so that the communication prohibition period is longer when the transmission power is large than when it is small. When power transmission is resumed after a transmission power control period or at the timing of power transmission resumption, ringing occurs in the transmission waveform.

The greater the difference in transmission power when transmission resumes, the greater the ringing that will occur. The higher the transmission power, the greater the possibility of ringing. Therefore, by making the communication prohibition period longer for higher transmission power, communication can be resumed after the ringing has converged or become sufficiently small.

In other words, stable communication can be performed between the TX and RX. Note that, in cases where it is desired to shorten the period during which communication is performed as much as possible, the TX or RX may set the communication prohibition period to be shorter. The TX or RX can determine the length of the communication prohibition period based on the magnitude of the transmission power.

In the above explanation, the magnitude of the transmission power is used as an example, but this may be replaced with the various settings related to the transmission power mentioned above. In other words, the length of the communication prohibition period can be determined based on the setting value related to the transmission power determined by negotiation between the TX and the RX. Alternatively, the length of the communication prohibition period may be determined based on the information stored in RP0, RP1, or RP2.

These packets contain information about the received power value of the RX. The transmission power transmitted by the TX may be replaced with this received power value information. Alternatively, the information about the transmission power of the TX may be replaced with the load power consumption consumed by the load of the RX.

Next, the relationship between the coupling state between the transmitting antenna 105 and the receiving antenna 205 and the communication prohibition period will be explained. TX or RX is determined so that the communication prohibition period is longer when the coupling state between the transmitting antenna and the receiving antenna is not good than when it is good. When the coupling state is not good, there is a possibility that a foreign object has entered between the transmitting antenna and the receiving antenna.

In addition, if the coupling state is not good, there is a possibility that the transmitting antenna and the receiving antenna are misaligned. The inclusion of foreign matter or misalignment of the antennas can cause waveform distortion and signal degradation in communication between the TX and RX, and also increase the likelihood of communication errors.

Therefore, for example, when the value of the coupling status index is less than the threshold, a longer communication prohibition period is set compared to when the value of the coupling status index is equal to or greater than the threshold. This allows communication to be performed after the ringing of the transmission wave waveform when power transmission is resumed has converged or become sufficiently small, reducing the possibility of a communication error occurring.

Alternatively, the configuration may be such that the smaller the coupling status index, the longer the communication prohibition period that is determined. The TX or RX can determine the length of the communication prohibition period depending on the coupling status index.

From another perspective, in order to improve communication quality, there is a method of shortening the communication prohibition period the worse the antenna coupling state. The worse the coupling state, the higher the possibility of a communication error occurring. When the coupling state is poor, the communication prohibition period can be shortened to ensure a longer period during which communication is possible.

In this case, the TX and RX communicate at a slower speed or with a larger modulation depth than when the coupling is good. For example, the TX transmits communication data using a slower frequency shift keying modulation, or transmits communication data using a frequency shift keying modulation with a larger modulation depth.

The RX also transmits communication data using slower amplitude modulation or load modulation, or transmits communication data using amplitude modulation or load modulation with a higher modulation depth. This reduces the probability of communication errors occurring and improves communication quality.

For example, in a first coupled state where the value of the coupled state index is less than the threshold, a shorter communication prohibition period is set compared to a second coupled state where the value of the coupled state index is equal to or greater than the threshold. In the first coupled state, the TX and RX communicate at a slower speed or with a larger modulation depth than in the second coupled state.

The TX and RX may be configured to set the communication prohibition period to be shorter in response to a decrease in the coupling state index value, and to perform slower communication or communication using a larger modulation factor. Alternatively, regardless of the setting or change of the length of the communication prohibition period, when the coupling state is poor, communication may be performed at a slower speed or with a larger modulation factor compared to when the coupling state is good, regardless of the setting or change of the length of the communication prohibition period.

In addition, the antenna coupling status index may be measured multiple times at a predetermined timing before or after the start of TX power transmission. When multiple measurements are performed at a predetermined timing after the start of power transmission, the length of the communication prohibition period, or the communication speed or modulation level can be changed based on each measurement result.

For example, the TX performs three measurements at a predetermined timing after starting power transmission, and the measured values of the coupling state index are all different. In this case, the length of the communication prohibition period, or the communication speed or modulation degree, will be changed three times. There is also a method of determining whether to lengthen or shorten the communication prohibition period depending on the coupling state, based on user specifications, etc.

Next, the relationship between the frequency of the radio waves transmitted by the power transmitting antenna 105 and the communication prohibition period will be explained. TX or RX is determined so that the communication prohibition period is longer when the frequency of the transmitted radio waves is high than when the frequency is low.

When power transmission is resumed after a period of power transmission control, the higher the frequency of the transmitted radio waves, the greater the ringing that may occur in the transmission waveform. In other words, the higher the frequency of the transmitted radio waves, the greater the ringing that may occur. Therefore, by making the communication prohibition period longer for the higher frequency of the transmitted radio waves, communication can be performed after the ringing has converged or become sufficiently small.

This enables stable communication between the TX and RX. When the frequency of the transmitted radio waves is higher than the threshold, the communication prohibition period is set longer than when the frequency of the transmitted radio waves is equal to or lower than the threshold. Alternatively, the communication prohibition period may be set longer as the frequency is higher.

From another perspective, there is a method of lengthening the communication prohibition period the lower the frequency of the transmitted radio waves. When power transmission is resumed after a transmission power control period, the lower the frequency of the transmitted radio waves, the more likely it is that ringing will occur for a long period of time.

The lower the frequency of the radio waves transmitted by the power transmitting antenna 105, the longer the communication inhibition period should be, so that communication can be performed after the ringing has converged or become sufficiently small.

Therefore, stable communication between TX and RX is possible. When the frequency is lower than the threshold, the communication prohibition period is set longer than when the frequency is equal to or higher than the threshold. Alternatively, the communication prohibition period may be set longer as the frequency is lower.

In addition, when the frequency of the transmitted radio waves varies within a predetermined range (for example, between 87 kHz and 205 kHz in the WPC standard), the communication prohibition period may be controlled according to the frequency. For example, when the frequency is within a first frequency band, the first communication prohibition period is set.

If the frequency is within a second frequency band different from the first frequency band, a second communication prohibition period is set with a length different from that of the first communication prohibition period. There is also a method of determining whether to lengthen or shorten the communication prohibition period based on a user specification or the like, depending on the frequency of the radio waves transmitted by the power transmitting antenna 105. The TX or RX can determine the length of the communication prohibition period based on the frequency of the transmitted radio waves.

Next, the relationship between the Quality Factor of the transmitting antenna 105 and the communication prohibition period will be explained. The Quality Factor can be obtained by Q-factor measurement or other measurement methods. TX or RX is determined so that the communication prohibition period is longer when the Quality Factor is low than when it is high.

The lower the Quality Factor, the smaller the amplitude of the transmitted wave during the transmission power control period in a short time, so the difference in the transmitted power when transmission resumes becomes larger, and larger ringing occurs. Therefore, the lower the Quality Factor, the longer the communication prohibition period is, and communication is performed after the ringing has subsided, making it possible to suppress the occurrence of communication errors.

If the Quality Factor is lower than the threshold, the communication prohibition period is longer than when the Quality Factor is equal to or greater than the threshold. Alternatively, the communication prohibition period may be longer the lower the Quality Factor.

From another perspective, there is a method for shortening the communication inhibition period the lower the Quality Factor of the power transmitting antenna 105 is. The lower the Quality Factor is, the lower the power transmission efficiency from TX to RX may be.

When the Quality Factor is low, the communication inhibition period can be shortened to ensure a longer period during which power can be transmitted from TX to RX. This contributes to improving power transmission efficiency and also makes it possible to suppress the impact of a low Quality Factor on the decrease in power transmission efficiency.

If the Quality Factor of the power transmitting antenna 105 is lower than the threshold value, the communication prohibition period is set shorter than when the Quality Factor is equal to or higher than the threshold value. Alternatively, the communication prohibition period may be set shorter as the Quality Factor is lower.

In addition, the Quality Factor related to the transmitting antenna 105 can be measured multiple times at a predetermined timing before or after the start of TX power transmission, and the length of the communication prohibition period can be changed based on each measurement result. For example, if three measurements are performed at a predetermined timing after the start of power transmission and the measured values of the Quality Factor are all different, the communication prohibition period will be changed three times.

There is also a method of determining whether to lengthen or shorten the communication prohibition period depending on the Quality Factor, based on a user specification, etc. The TX or RX can determine the length of the communication prohibition period based on the Quality Factor associated with the power transmitting antenna 105.

Next, the relationship between the transmission power control period and the communication prohibition period will be explained. TX or RX is determined so that the longer the transmission power control period, the longer the communication prohibition period. As mentioned above, the greater the difference in level between the power just before transmission resumes and the transmission power at the time transmission resumes, the greater the ringing that occurs. The longer the transmission power control period, the greater the attenuation of the transmitted wave, so the greater the difference in level and the greater the ringing that occurs.

The longer the transmission power control period, the longer the communication prohibition period, allowing communication to take place after the ringing has converged or become sufficiently small. This allows stable communication between the TX and RX. The TX and RX can determine the length of the communication prohibition period based on the length of the transmission power control period.

Next, a method for determining the power transmission period will be described. RX (or TX) determines the length of the power transmission period to a predetermined value and notifies TX (or RX). Alternatively, TX (or RX) may determine the length of the power transmission period to a predetermined value depending on the state of the device and notify RX (or TX).

Alternatively, the TX and RX may communicate with each other and determine the length of the power transmission period to a predetermined value. The TX determines the maximum time (or minimum time) that can be set as the length of the power transmission period and notifies the RX. The RX determines the minimum time (or maximum time) that can be set as the length of the power transmission period and notifies the TX.

The TX or RX determines the length of the power transmission period within the range set by the TX and RX. In this case, the TX (or RX) that determines the power transmission period notifies the RX (or TX) of the determined power transmission period using a specified packet. The specified packet may be an execution request packet (e.g., a Received Power Data Packet).

Next, the relationship between the TX transmission power and the transmission period will be explained. TX or RX is determined so that the transmission period is shorter when the transmission power is large than when it is small. The higher the transmission power, the higher the foreign object detection accuracy required.

The higher the transmission power, the shorter the transmission period can be, which increases the number of transmission power control periods within a given period. In addition, by increasing the number of times the attenuation state of the transmission wave is observed, the opportunities for detecting foreign objects can be increased, enabling highly accurate foreign object detection.

From another perspective, there is a method of setting the transmission period longer as the transmission power increases. By setting a longer transmission period, it becomes possible to transmit power without reducing the transmission efficiency.

The method of determining the length of the transmission period is not limited to the method of determining the size of the transmission power. The size of the transmission power by the TX may be replaced with the various setting values related to the transmission power that are determined by negotiation between the TX and the RX. The TX can determine the length of the transmission period based on the setting values.

Alternatively, the length of the power transmission period can be determined based on the load power consumption consumed by the RX load. Also, when the TX and RX determine the length of the power transmission period using the method described above, the RX transmits a packet requesting execution of the above-mentioned foreign object detection operation so as to satisfy the determined length of the power transmission period.

In other words, if TX and RX determine the power transmission period to be a first length, RX transmits an execution request packet to TX at a first time interval. If TX and RX determine the power transmission period to be a second length that is longer than the first length, RX transmits an execution request packet to TX at a second time interval that is longer than the first time interval.

In this way, it becomes possible to transmit power with the length of the power transmission period determined by TX and RX. This can also be applied to the control of the length of the power transmission period described below.

Next, the relationship between the coupling state of the transmitting antenna 105 and the receiving antenna 205 and the power transmission period will be explained. TX or RX is determined so that the power transmission period is shorter when the coupling state of both antennas is not good than when it is good. When the coupling state is not good, there is a possibility that a foreign object has entered between the transmitting antenna and the receiving antenna, so high accuracy in detecting foreign objects is required.

Therefore, by shortening the power transmission period as the coupling state becomes poorer, it is possible to increase the number of power transmission control periods within a given period, and increase the number of times the attenuation state of the transmitted radio wave is observed, thereby increasing the opportunities for detecting foreign objects. This makes it possible to detect foreign objects with high accuracy.

From another perspective, there is a method of making the power transmission period longer when the coupling state between the transmitting antenna 105 and the receiving antenna 205 is not good than when it is good. With this method, the power transmission efficiency decreases, but by setting the power transmission period longer, it becomes possible to transmit power without reducing the transmission efficiency of the transmitted power.

If the TX does not receive the execution request packet from the RX during the power transmission period, the power transmission period is not set as a detection processing period, and power transmission continues. When the antenna coupling state is not good, the TX makes the power transmission period longer than when the coupling state is good. Alternatively, the TX may be configured to make the power transmission period longer the worse the antenna coupling state.

Next, the relationship between the Quality Factor of the transmitting antenna 105 and the power transmission period will be explained. The method for measuring the Quality Factor is as described above, and it can be obtained by a Q-value measurement method or the like. TX or RX is determined so that the power transmission period is longer when the Quality Factor is low than when it is high.

The lower the Quality Factor, the more likely it is that the efficiency of power transmission from TX to RX will decrease. When the Quality Factor is low, the power transmission period can be lengthened to ensure a longer period during which power can be transmitted from TX to RX. This improves power transmission efficiency and also makes it possible to suppress the impact of a low Quality Factor on the decrease in power transmission efficiency.

When the Quality Factor is lower than the threshold, the TX extends the power transmission period more than when the Quality Factor is equal to or greater than the threshold. Alternatively, the TX may be configured to extend the power transmission period as the Quality Factor becomes lower.

From another perspective, there is a method of shortening the power transmission period as the Quality Factor of the power transmitting antenna 105 becomes lower. When the Quality Factor is low, there is a possibility that a foreign object is present between the power transmitting antenna and the power receiving antenna, so high accuracy in detecting foreign objects is required.

The lower the Quality Factor, the shorter the power transmission period can be, which increases the number of power transmission power control periods within a specified period and increases the number of times the attenuation state of the transmitted radio wave is observed, thereby increasing the opportunities for foreign object detection. This enables highly accurate foreign object detection. Note that if the TX does not receive the execution request packet from the RX during the power transmission period, the power transmission period is not set as a detection processing period, and power transmission continues.

Each period described above does not necessarily have to be set individually. For example, a configuration may be used in which the length of the entire detection processing period, including at least the transmission power control period, is determined. In this case, the TX and RX determine the length of the entire detection processing period based on the magnitude of the transmission power or the various setting values related to the transmission power. Alternatively, the TX and RX determine the length of the entire detection processing period based on the load power consumption consumed by the RX load.

Alternatively, the length of the entire detection processing period may be determined based on the coupling state between the transmitting antenna and the receiving antenna, or the quality factor associated with the antennas. Note that the method of setting each period described above can also be applied to a configuration in which the TX has one transmitting antenna and the RX has one receiving antenna.

Next, a case where foreign object detection is performed using the waveform attenuation method in a power transmission device 100 having multiple power transmission antennas will be described. In this case, foreign objects can be detected with higher accuracy than when the waveform attenuation method is performed for one power transmission antenna. When the waveform attenuation method is performed for each of multiple power transmission antennas, it is necessary to set a detection processing period for performing the waveform attenuation method for each power transmission antenna.

This detection processing period is a period that is set to include a communication prohibition period, a power transmission period, a preparation period, a power transmission control period, or one or more of these periods. In controlling each period performed by the TX and RX, the length of the period and the timing (start or end point of the period) can be set arbitrarily.

In this embodiment, the set value of the detection processing period related to the waveform attenuation method executed for each power transmitting antenna is set to be the same for all power transmitting antennas. For example, when explaining using a communication prohibited period as an example, one of the N power transmitting antennas that executes the waveform attenuation method among multiple power transmitting antennas is referred to as the jth power transmitting antenna.

j is a natural number variable that represents any value in the range from 1 to N. The communication prohibition period corresponding to the jth power transmitting antenna is denoted as the jth communication prohibition period. The first through Nth communication prohibition periods are all set to the same length. Similarly, the power transmitting period, preparation period, and transmission power control period corresponding to the jth power transmitting antenna are all set to the same length.

Based on the method described above, the TX and RX determine the length of each period to be an optimal time. The detection processing period related to the waveform decay method performed for each transmitting antenna is set to the same length for all transmitting antennas that perform the waveform decay method.

By setting the length of the detection processing period to an optimal time, it becomes possible to measure the waveform attenuation index at each transmitting antenna. In addition, by setting the detection processing period to the same length for each transmitting antenna that performs the waveform attenuation method, it becomes possible to suppress disturbances and ringing in the transmitted radio wave waveform, and to perform stable communication while detecting foreign objects with high accuracy.

In the above example, the control is described in which the detection processing periods (communication prohibited period, power transmission period, preparation period, and power transmission power control period) for each power transmission antenna are made the same, but this is not limiting. For example, the configuration may be such that the length of the entire detection processing period including the first power transmission power control period is made the same as the length of the entire detection processing period including the second power transmission power control period.

A period including at least one of a communication prohibition period, a power transmission period, a preparation period, and a power transmission power control period corresponding to a first power transmission antenna is referred to as a first period. A period including at least one of a communication prohibition period, a power transmission period, a preparation period, and a power transmission power control period corresponding to a second power transmission antenna is referred to as a second period. A configuration may be adopted in which the first period and the second period are controlled to be the same.

Next, the timing of the waveform attenuation method will be explained. In the first control method, the TX controls the timing of the waveform attenuation method executed at each transmitting antenna based on the determined detection processing period so that the timing is the same. The communication prohibited period, power transmission period, preparation period, and transmission power control period are the same for each transmitting antenna.

When the RX determines the timing for executing the waveform attenuation method for each transmitting antenna, it simultaneously transmits an execution request packet for determining the timing to each transmitting antenna of the TX. This simplifies transmission control. On the other hand, when the TX determines the timing for executing the waveform attenuation method for each transmitting antenna, the TX only needs to simultaneously set the timing and execute the waveform attenuation method, making control simple.

The second control method is a method of controlling so that the above timing for each period is different. Based on the determined detection processing period, the TX sets the waveform attenuation method executed at each transmitting antenna to different timing. For example, one or more of the communication prohibited period, the power transmission period, the preparation period, and the transmission power control period are at different timings for at least one transmitting antenna.

When the RX determines the timing for executing the waveform attenuation method for each transmitting antenna, it transmits an execution request packet for determining the timing to each transmitting antenna related to the execution of the waveform attenuation method at different timings. When the TX receives the execution request packet at different timings from each transmitting antenna, it performs transmission power control at different timings accordingly.

This makes it possible to reduce the level of noise generated by the TX at frequencies other than those used to transmit power. Alternatively, when the TX performs transmission power control using the first control method, the received power of the RX temporarily decreases, but the second control method makes it possible to suppress the amount of this decrease.

Next, we will explain a method for determining whether or not a foreign object exists based on multiple measurement results obtained when the TX measures waveform attenuation indices (e.g., Quality Factor) at multiple transmitting antennas. The TX performs transmission power control for multiple selected transmitting antennas during a transmission power control period, and can obtain multiple waveform attenuation indices from the measurement results of the attenuation state of the transmitted radio wave.

The TX compares the acquired values of the multiple waveform attenuation indexes with a predetermined threshold value to determine the presence of a foreign object. For example, when a Quality Factor is used as the waveform attenuation index, the TX determines that a foreign object is present if the number of Quality Factors smaller than the threshold value among the multiple Quality Factors is greater than a predetermined number.

Alternatively, when the waveform attenuation amount or waveform attenuation rate is used as the waveform attenuation index, the TX determines that a foreign object is present if the number of waveform attenuation amounts or waveform attenuation rates that are greater than a threshold value among multiple waveform attenuation amounts or waveform attenuation rates is greater than a predetermined number. The threshold value for determining a foreign object may be set as a predetermined range having an upper threshold value and a lower threshold value.

In this case, a foreign object determination is made based on the number of waveform attenuation indices that are within a predetermined range based on a threshold value, or the number of waveform attenuation indices that are not within the predetermined range. Note that the above "predetermined number" is a number obtained by multiplying the number of times transmission power control is executed by a predetermined ratio.

For example, if the TX executes the waveform attenuation method five times, 40% of five times (5 x 0.4 = 2) is set as the predetermined number. If the number of Quality Factors smaller than the threshold among the multiple Quality Factors is greater than 2, it is determined that "foreign matter is present." Note that the same applies to the "predetermined number" when a waveform attenuation index other than the Quality Factor is used.

Furthermore, any number can be set as a ratio for determining the "predetermined number," and the method for determining the "predetermined number" is not limited to this, and any method can be adopted. Furthermore, if the number of Quality Factors smaller than the threshold value among multiple Quality Factors is 1 or more, it may be determined that "foreign matter is present."

TX may compare the value of the waveform attenuation index with a threshold value to determine the possibility that a foreign object exists and express this as a specified index. Hereinafter, an index indicating the possibility (probability of existence) of a foreign object is referred to as the "probability of existence index" of a foreign object. For example, TX calculates the number of waveform attenuation indexes that fall within a specified range. The specified range is a predefined range having an upper threshold value and a lower threshold value.

The TX obtains a presence probability index corresponding to the number of waveform attenuation indexes within the range and notifies the RX. The more waveform attenuation indexes that fall within the specified range, the lower the probability of a foreign object being present, and the fewer the waveform attenuation indexes that fall within the specified range, the higher the probability of a foreign object being present.

The TX notifies the RX of a presence probability index according to the magnitude of the probability of the presence of a foreign object. Note that the criteria for judgment can be changed arbitrarily depending on the type of waveform attenuation index. In addition, the probability of the presence of a foreign object itself may be used as the index of the probability of the presence of a foreign object.

The TX can compare each of the multiple waveform attenuation indices with a predetermined threshold value to obtain multiple presence probability indices that correspond to the possibility (presence probability) that a foreign object exists. The TX determines a final result from the multiple presence probability indices.

This is a judgment result that indicates the presence or absence of a foreign object, or the possibility that a foreign object exists (probability of existence). The TX transmits a signal (e.g., ACK or NAK) based on the judgment result to the RX. Alternatively, the TX may notify the RX of information indicating the probability of the presence of a foreign object using a specified packet.

The RX can receive information on multiple waveform attenuation indicators or presence probability indicators from the TX and perform the above-mentioned foreign object determination. Alternatively, the TX can compare the measurement results at each transmitting antenna with the above-mentioned threshold value to determine the presence or absence of a foreign object at each transmitting antenna, or the possibility that a foreign object exists (probability of existence), and notify the RX of the determination result.

The RX can make a comprehensive judgment on the judgment results from each transmitting antenna and make a final judgment on the possibility (probability) of the presence of a foreign object. Also, an example was shown in which the TX calculates a waveform attenuation index from the measurement results, but since the transmitting antenna and the receiving antenna are electromagnetically coupled, the RX can observe the attenuation state of the transmitted wave.

Therefore, the RX may calculate a waveform attenuation index from the measurement results and perform the above-mentioned foreign object determination based on the calculated waveform attenuation index. The TX executes transmission power control multiple times for multiple transmitting antennas. By performing foreign object determination using multiple waveform attenuation indexes calculated from the respective waveform attenuation states, more accurate foreign object detection is possible.

Next, Figs. 14(A) and (B) are schematic diagrams showing the configuration of a power transmission device and a power receiving device according to the first embodiment. With reference to Fig. 14(A), the processing executed by a power transmission device having multiple power transmission antennas and a power receiving device having one power receiving antenna will be described.

The number of power transmission antennas that the power transmitting device 100 can use for power transmission is n, and the number of antennas that the power receiving device 200 can use for power reception is one. The TX transmits power to the RX using multiple power transmission antennas selected from the n power transmission antennas.

For example, assume that power is transmitted to RX using three transmitting antennas. RX wirelessly receives the power transmitted by TX using one receiving antenna. In this case, the receiving antenna is larger in size than one of the three transmitting antennas. With the configuration shown in FIG. 14(A), TX and RX are capable of one-to-one communication.

The processing flow of RX and TX will be described with reference to Figures 15 and 16. Figure 15 is a flowchart explaining the processing of the power transmitting device in the first embodiment, and shows the processing of the TX. Figure 16 is a flowchart explaining the processing of the power receiving device in the first embodiment, and shows the processing of the RX. The following processing is realized by each control unit of the TX and RX executing a program stored in memory.

In Figure 15, processing begins at S1501, and the power supply of the TX is turned ON at S1502. After the Selection phase and Ping phase, the TX detects the RX at S1503. The TX starts transmitting power to the detected RX at S1504.

The power transmission at this time is performed in the I&C phase, the Negotiation phase, the Calibration phase, the Power Transfer phase, etc. Next, proceed to the processing of S1505.

In S1505, the TX determines whether or not it has received a packet requesting execution of foreign object detection from the RX. If the packet requesting execution has not been received (No in S1505), the TX waits for a predetermined period of time, and then repeats the determination process in S1505. If the TX has received a packet requesting execution from the RX (Yes in S1505), the TX proceeds to the process in S1506.

In S1506, the TX selects one of the multiple power transmitting antennas to be used for foreign object detection. For example, the TX selects the multiple power transmitting antennas that are being used to transmit power to the RX. Alternatively, the TX may select all of the power transmitting antennas. Alternatively, the TX may select multiple power transmitting antennas that are spaced apart by a predetermined distance.

It is possible to select multiple transmitting antennas based on a predetermined rule. Alternatively, the TX may select multiple transmitting antennas that have detected the placement of an object through transmission from the AP. In the example shown in FIG. 14(A), the three transmitting antennas used to transmit power to the RX are selected.

In S1507, the TX sets each period related to the transmission power control to be executed for the selected transmitting antenna based on the information in the execution request packet received from the RX. Each period related to the transmission power control is set to be the same period.

Each period related to transmission power control is a detection processing period, which is a communication prohibited period, a transmission period, a preparation period, a transmission power control period, or a period set to include one or more of these periods. In S1508, the TX executes transmission power control based on the periods set for the selected transmission antenna.

For example, the TX controls the timing of the waveform attenuation method to be executed for each transmitting antenna so that it is the same. In this case, the communication inhibition period, transmission period, preparation period, and transmission power control period related to the execution of the waveform attenuation method are the same for each transmitting antenna.

Alternatively, the TX may control the timing of the waveform attenuation method to be executed for each transmitting antenna to be different. In this case, at least one of the communication inhibition period, the transmission period, the preparation period, and the transmission power control period related to the execution of the waveform attenuation method will have different timing for at least one transmitting antenna. Next, proceed to processing of S1509.

In S1509, the TX determines whether or not foreign object detection processing has been performed for the selected multiple transmitting antennas. In the example shown in FIG. 14(A), the determination processing in S1509 is repeatedly performed until the waveform attenuation index is measured for all three selected transmitting antennas and foreign object detection processing is performed.

When the waveform attenuation index has been measured for all three selected transmitting antennas and the foreign object detection process has been completed (Yes in S1509), the process proceeds to S1510. In S1510, the TX compares the multiple acquired measurement results with a threshold value to determine the presence or absence of a foreign object, or the possibility (probability of presence) of a foreign object.

In S1511, the TX determines whether the judgment result is "foreign object present" or "there is a high possibility that a foreign object is present." If the judgment result is obtained (Yes in S1511), the TX proceeds to processing in S1512, and if the judgment result is not obtained (No in S1511), the TX proceeds to processing in S1516.

In S1512, the TX notifies the RX of the determination result ("foreign object present" or "high possibility of the presence of a foreign object") in a specified packet. For example, the TX sends a negative acknowledgement NAK to the RX. On the other hand, in S1516, the TX notifies the RX of the determination result ("no foreign object" or "low possibility of the presence of a foreign object") in a specified packet. For example, the TX sends an acknowledgement ACK to the RX.

In regard to the "possibility of the presence of a foreign object" as a judgment result, information on the foreign object presence probability index can be used. The TX may notify the RX of the presence probability index information. For example, the TX obtains the presence probability of a foreign object based on the difference between the measured waveform attenuation index and a set threshold value, and calculates the presence probability index.

The packet transmitted from the TX to the RX includes any of the following information: the presence or absence of a foreign object, the possibility of the presence of a foreign object, the probability of the presence of a foreign object, or an index of the probability of the presence of a foreign object. In addition, the TX may notify the RX of an action it requests while transmitting the packet. For example, the action request may be an action request to reduce the transmission power of the TX or the reception power of the RX, or an action request to change the GP value.

Or there is a request to perform additional or re-perform measurement processing (CAL processing) to set a threshold value used in foreign object detection. The foreign object detection is based on the power loss method, the Q value measurement method, the waveform attenuation method, the temperature measured by the power transmitting device 100, or the electromagnetic coupling state (e.g., the coupling coefficient) between the power transmitting antenna 105 and the power receiving antenna 205.

Or, there is an operation request to execute the foreign object detection. These matters are also the same in the example and embodiment of FIG. 14(B) described later.

After S1512, the process proceeds to S1513. Also, from S1516, the process proceeds to S1505. At S1513, the TX receives an EPT, which is a power transmission stop command, from the RX. At S1514, the TX stops transmitting power to the RX. Alternatively, at S1513, the TX receives a specified packet from the RX requesting an operation to limit the TX's transmission power or the RX's receiving power.

Then, the TX executes a predetermined operation to limit the transmission power of the TX or the receiving power of the RX. Here, the predetermined operation may be the process flow for determining the GP value described above. Then, in S1514, the TX may reduce the transmission power to the RX. In S1515, the series of processes ends.

Next, the processing of the RX will be explained. Processing starts at S1601 in FIG. 16, and the power supply of the RX is turned ON at S1602. When the RX is placed on the TX at S1603, the TX detects the RX after passing through the Selection phase and Ping phase. At S1604, the RX starts receiving power transmitted from the TX.

The power received here is the power transmitted from the TX in the I&C phase, Negotiation phase, Calibration phase, Power Transfer phase, etc. Next, proceed to processing of S1605.

In S1605, the RX determines whether to request foreign object detection from the TX. If the predetermined conditions are met, the RX decides to request foreign object detection from the TX using the waveform attenuation method (Yes in S1605) and proceeds to processing in S1606.

If the specified conditions are not met, the RX decides not to request the TX to detect foreign objects using the waveform attenuation method (No in S1605). In this case, the process of S1606 is repeated and the RX continues receiving power. Examples of the specified conditions in S1605 are shown below.

・An error occurs in communication between TX and RX. (RX detects a communication error.)
A decrease in the power transmitted from the TX to the RX is observed. (The RX observes a decrease in the power received.)
The acquired calibration data is an abnormal value. (The RX receives information from the TX indicating that the calibration data is abnormal.)
A temperature rise is observed in the TX or RX. (The RX detects a temperature rise, or the RX receives information from the TX indicating that the temperature is rising.)
A high probability that a foreign object is present is detected using a method other than the waveform attenuation method. (The RX receives information from the TX indicating that a foreign object is present.)

These conditions are conditions when the presence of a foreign object is suspected. Alternatively, the specified conditions are conditions when the transmission power transmitted from the TX to the RX is to be increased or decreased. Alternatively, the specified conditions are conditions when the receiving power received by the RX from the TX is to be increased or decreased.

Alternatively, the specified condition is a condition when information (set value) related to the transmission power of the TX or information (set value) related to the receiving power of the RX, which is held by the TX or RX, is changed. Alternatively, the specified condition is a condition when the value of the GP is changed. Alternatively, the specified condition is a condition when calibration (CAL processing of the Power Loss method) is performed.

In the CAL process, measurements are performed to set the threshold value used in foreign object detection. Alternatively, the predetermined condition is a condition under which the RX notifies the TX of the RX's state (e.g., received power, etc.). For example, when any one or more of a number of conditions are satisfied, the RX determines to request foreign object detection from the TX. Note that the predetermined condition may be a condition other than the above, and can be set arbitrarily.

In S1606, the RX determines the length of the detection processing period related to the transmission power control executed for each transmitting antenna. The detection processing period and the method for setting it are as described above. In S1607, the RX transmits to the TX an execution request packet including information for determining each period related to the transmission power control.

For example, the information is information for determining the length of the transmission power control period and the length of the communication prohibition period. The execution request packet may be RP0, RP1, or RP2, or individual packets may be used.

The execution request packet that the RX sends to the TX in S1607 will be described. The RX sends to the TX the number of execution request packets corresponding to the number of transmitting antennas involved in the execution of the waveform attenuation method. In the example of FIG. 14, the three transmitting antennas involved in the execution of the waveform attenuation method are referred to as the first to third transmitting antennas.

The RX transmits first to third execution request packets to the TX. The first to third execution request packets each include information for determining the respective periods related to the transmission power control of the first to third transmission antennas. The information for determining the detection processing periods related to the transmission power control, which is included in the first to third execution request packets, respectively, is set by the RX so that it is the same for the first transmission antenna, the second transmission antenna, and the third transmission antenna.

For example, the RX sets the length of each period in the detection processing period one by one. The setting value of the detection processing period related to the waveform attenuation method executed by each transmitting antenna is set to be the same value for each transmitting antenna.

The RX can transmit multiple execution request packets to the TX as separate execution request packets. In this case, each execution request packet further includes information that associates each transmitting antenna with the setting value of each detection processing period. For example, the TX notifies the RX of information regarding the transmitting antenna that the TX selected prior to the time of S1605.

Specifically, the information includes the number of transmitting antennas involved in the execution of the waveform attenuation method, the identifiers of the transmitting antennas, and information on the type and electrical characteristics of the transmitting antennas. Each execution request packet includes information relating to the transmitting antenna, which associates the identifier of the transmitting antenna with the setting value of each detection processing period, to identify the target transmitting antenna and indicate which transmitting antenna the detection processing period is for.

Therefore, the TX can recognize the setting value of the detection processing period corresponding to each power transmission antenna. Note that the above-mentioned power transmission antenna may be replaced with a power transmission unit. Each execution request packet includes information relating to the power transmission unit, which associates the identifier of the power transmission unit with the setting value of each detection processing period, as information relating to the power transmission unit for identifying the target power transmission unit in order to indicate which power transmission unit the detection processing period is for.

Furthermore, consider controlling each period for each transmitting antenna to have a different timing. When the RX determines the timing for executing the waveform decay method for each transmitting antenna, the RX transmits multiple execution request packets including identifiers of each transmitting antenna related to the execution of the waveform decay method at different timings.

The multiple execution request packets contain the same information for determining each period related to the transmission power control. When the TX receives an execution request packet including an identifier of a transmission antenna, it performs transmission power control at the transmission antenna with that identifier. When the TX receives multiple execution request packets at different times, it performs transmission power control at each transmission antenna at different times accordingly. Note that the above-mentioned transmission antenna may be replaced with a power transmission unit.

Alternatively, the RX can transmit the first to third execution request packets to the TX as a single execution request packet. In the example of FIG. 14, the RX transmits to the TX an execution request packet that includes identifiers of the three power transmitting antennas and the corresponding three detection processing period setting values.

One execution request packet includes a list (information) that associates the identifier of each power transmitting antenna with the setting value of each detection processing period. The TX that receives the execution request packet can recognize the setting value of the detection processing period for each power transmitting antenna that is the target of execution. Note that the above-mentioned power transmitting antenna may be replaced with a power transmitting unit.

One execution request packet contains a list (information) that associates the identifier of each power transmitting unit with the setting value of each detection processing period. In addition, it is considered to control the above-mentioned periods in each power transmitting antenna so that they have the same timing. When the RX determines the timing to execute the waveform attenuation method (transmission power control) in each power transmitting antenna, it can transmit the above-mentioned one execution request packet to the TX as a packet that determines the timing.

When the TX receives the execution request packet, it executes the waveform attenuation method (transmission power control) simultaneously for each transmitting antenna. Alternatively, if the TX determines the timing for executing the waveform attenuation method for each transmitting antenna, the TX can execute the waveform attenuation method simultaneously at that timing.

Furthermore, consider controlling the above-mentioned periods at each transmitting antenna so that they are different timing. When the TX receives one execution request packet as described above from the RX, the TX controls the timing at which the TX executes the waveform attenuation method (transmission power control) at each transmitting antenna to be shifted by a predetermined period and executed at different timings.

The above-mentioned power transmission antenna may be replaced with a power transmission unit. The detection processing period related to the waveform decay method executed for multiple power transmission antennas is set to the same length for all power transmission antennas for which the waveform decay method is executed.

The RX transmits one execution request packet to the TX, which includes one piece of time information for each period set by the above-mentioned method. The TX sets the length of the detection processing period of each transmitting antenna for which the waveform attenuation method is to be executed to the same value based on each piece of time information included in the received execution request packet.

After S1607, the process proceeds to S1608, where the RX determines whether or not it has received the foreign object detection determination result from the TX. If a notification packet including the foreign object detection determination result is not received from the TX (No in S1608), the RX waits until it receives the notification packet, and the determination process of S1608 is repeated. If the RX receives the notification packet from the TX (Yes in S1608), the process proceeds to S1609.

In S1609, the RX determines whether the judgment result included in the received notification packet satisfies a predetermined condition. The predetermined condition is, for example, that a judgment result of "foreign object present" or "there is a high possibility that a foreign object is present" is obtained.

If the specified condition is met (Yes in S1609), the process proceeds to S1610. If the specified condition is not met (No in S1609), for example, if the determination result is "no foreign object" or "the possibility of the presence of a foreign object is low," the process proceeds to S1612.

In S1610, the RX transmits a power transmission stop command (EPT) to the TX. Alternatively, in S1610, the RX may transmit to the TX a specified packet requesting an operation to reduce the TX transmission power or the RX reception power, or a specified packet requesting an operation to change the GP value.

Then, the RX executes a predetermined operation to limit the transmission power of the TX or the receiving power of the RX. Here, the predetermined operation can be the process flow for determining the GP value described above. Alternatively, the RX may request the TX to execute an additional measurement process (CAL process) for setting a threshold value used in foreign object detection, or to execute it again.

The foreign object detection may be based on the power loss method, the Q value measurement method, the waveform attenuation method, the temperature measured at the TX, or the electromagnetic coupling state (e.g., the coupling coefficient) between the transmitting antenna and the receiving antenna. After S1610, the series of processes ends at S1611.

On the other hand, in S1612, RX executes a predetermined process, and then proceeds to the process of S1605. An example of the predetermined process is shown below.
A process of increasing the transmission power sent from TX to RX.
Measurement process (CAL process) for setting the threshold value used in foreign object detection.
-Process of notifying TX of RX status (received power, etc.)

FIG. 17 is a sequence diagram explaining an example of processing by the power transmitting device and power receiving device according to the first embodiment, showing an example of the operation of the TX and RX. The operation of the TX is shown on the left, and the operation of the RX is shown on the right. After the TX is powered on, it transitions to the Selection phase and the Ping phase, and upon detecting the placement of the RX, it starts the power transmission process. After the RX is powered on, it is placed on the TX, and transitions to the Selection phase and the Ping phase.

The RX determines the execution request for foreign object detection and determines the length of the detection processing period. The RX transmits an execution request packet requesting the TX to detect foreign objects using the waveform attenuation method. The TX, having received the execution request packet, selects a transmitting antenna to execute foreign object detection and sets the length of the detection processing period corresponding to the selected transmitting antenna.

The TX measures the waveform attenuation index and performs a foreign object determination based on the measurement results. The TX notifies the RX of the foreign object determination results. The RX analyzes the acquired foreign object determination results and sends a power transmission stop command (EPT) to the TX. The TX stops power transmission to the RX in accordance with the received power transmission stop command.

Next, referring to FIG. 14(B), the processing performed by a power transmitting device having n power transmitting antennas and a power receiving device having n power receiving antennas will be described. FIG. 14(B) shows an example in which three power transmitting coils are selected from the n power transmitting antennas in the power transmitting device 100, and the power receiving device 200 having three power receiving antennas receives power.

The three transmitting antennas face the three receiving antennas, respectively, and wireless power transmission is carried out by each of the three pairs of transmitting and receiving antennas. TX and RX are capable of independent communication in an n-to-n (e.g., 3-to-3) configuration.

The flow of RX and TX processing will be described with reference to Figures 18 and 19. Figure 18 is a flowchart explaining the processing of the power transmitting device in the first embodiment, and shows the TX processing. Figure 19 is a flowchart explaining the processing of the power receiving device in the first embodiment, and shows the RX processing.

The following processing is realized by each control unit of TX and RX executing a program stored in memory. The processing of S1701 to S1705 in FIG. 18 is similar to the processing of S1501 to S1505 in FIG. 15, respectively, and therefore will not be described.

If in S1705 the TX determines that it has received a packet requesting execution of foreign object detection from the RX (Yes in S1705), it proceeds to processing in S1706. In S1706, the TX sets each period (detection processing period) related to the transmission power control to be executed in the transmitting antenna that received the execution request packet, based on the information in the execution request packet received from the RX.

The TX sets the length of each period related to the transmission power control to be executed for the three selected transmitting antennas (the three transmitting antennas that received the execution request packet) to be the same. In S1707, the TX executes the transmission power control for the three transmitting antennas that received the execution request packet based on each of the set periods. Next, the process proceeds to S1708.

In S1708, the TX determines whether the execution of the foreign object detection operation has been completed for all transmitting antennas that received the request to execute foreign object detection. If the waveform attenuation index has been measured for all three transmitting antennas that received the execution request packet and the execution of the foreign object detection operation has been completed (Yes in S1708), the TX proceeds to processing in S1709.

If the measurement of the waveform attenuation index and the execution of the foreign object detection operation have not been completed for any of the power transmitting antennas that received the execution request packet (No in S1708), the determination process of S1708 is repeatedly executed.

In S1709, the TX compares the acquired multiple measurement results with a threshold value to determine whether a foreign object is present. If the determination result is "foreign object present" or "there is a high possibility that a foreign object is present" (Yes in S1710), the process proceeds to S1711. If the determination result is "no foreign object present" or "there is a low possibility that a foreign object is present" (No in S1710), the process proceeds to S1715.

In S1711, the TX notifies the RX of the determination result ("foreign object present" or "high possibility of foreign object presence") in a specified packet. This can be achieved, for example, by the TX sending a negative acknowledgement NAK to the RX. In S1712, the TX receives a power transmission stop command (EPT) from the RX, and in S1713 the TX stops transmitting power to the RX.

Alternatively, in S1712, the TX receives a specified packet from the RX requesting an operation to limit the TX transmission power or the RX reception power. The RX then executes a specified operation to limit the TX transmission power or the RX reception power. Here, the specified operation may be the process flow for determining the GP value described above.

Then, in S1713, the TX may reduce the power transmitted to the RX. At this time, the TX may include information requesting the RX to perform a specific operation in a packet containing the result of the foreign object detection determination and transmit the packet to the RX. Then, in S1714, the series of processes ends.

In addition, in S1715, the TX notifies the RX of the determination result ("no foreign object" or "low possibility of the presence of a foreign object") in a specified packet. This can be achieved by the TX sending an ACK acknowledgement to the RX, for example. Then, the process proceeds to S1705 to continue power transmission.

Next, the RX processing will be described. The processing of S1801 to S1805 in FIG. 19 is similar to the processing of S1601 to S1605 in FIG. 16, so the description will be omitted and only the differences will be described. If the RX determines in S1805 to request foreign object detection using the waveform attenuation method (Yes in S1805), the process proceeds to S1806.

In S1806, the RX selects a power transmitting antenna for performing foreign object detection. In other words, a power transmitting antenna for transmitting a packet requesting execution of foreign object detection is selected. The RX can select, as the power transmitting antenna for requesting foreign object detection, one of multiple power transmitting antennas used for transmitting power to the RX, or all power transmitting antennas facing the power receiving antennas possessed by the RX.

Alternatively, the RX may select multiple transmitting antennas based on a predetermined rule. For example, it is possible to select multiple transmitting antennas that are separated by a predetermined distance from multiple transmitting antennas that face the receiving antenna possessed by the RX. In the example shown in FIG. 14(B), three transmitting antennas that are used to transmit power to the RX are selected.

Note that the configuration is not limited to one in which the RX selects the transmitting antenna that performs foreign object detection, and the TX may select the transmitting antenna that performs foreign object detection. In this case, the TX notifies the RX of predetermined information on the transmitting antenna that performs foreign object detection, and the RX selects the transmitting antenna that transmits the execution request packet based on that information. After S1806, the process proceeds to S1807.

In S1807, the RX determines the detection processing period related to the foreign object detection processing. The detection processing period and the method for setting it are as described above. In S1808, the RX transmits to the TX an execution request packet including information for determining each period related to the transmission power control. In this embodiment, the information included in the execution request packet is, for example, information for determining the length of the transmission power control period and the length of the communication prohibition period.

The execution request packet may be RP0, RP1, or RP2. Also, individual packets may be used as the execution request packet. RX transmits the execution request packet to each of the three transmitting antennas selected in S1806. For example, the transmitting antennas selected by RX in S1806 are the first to third transmitting antennas.

The receiving antennas facing the first to third transmitting antennas, respectively, are called the first to third receiving antennas. The RX transmits execution request packets containing the same information for determining each period related to the transmission power control from each of the first to third receiving antennas to the first to third transmitting antennas.

The RX may control the timing of the waveform attenuation method (transmission power control) executed by each transmission antenna so that the timing is the same. The RX simultaneously transmits an execution request packet to each transmission antenna related to the execution of the waveform attenuation method. The TX that receives the execution request packet sets the communication prohibition period, transmission period, preparation period, and transmission power control period for each transmission antenna so that they are all at the same timing.

Then, the TX executes the waveform attenuation method (transmission power control) at the same timing for each transmitting antenna. Alternatively, the timing of each of the above periods for each transmitting antenna may be controlled so that each period has a different timing. In this case, the RX transmits an execution request packet to each transmitting antenna involved in executing the waveform attenuation method, the execution request packet including an instruction to set each period to a different timing.

Alternatively, the RX transmits an execution request packet at different times to each transmitting antenna involved in the execution of the waveform attenuation method. The execution request packet includes the same information for determining each period related to the transmission power control. When the TX receives the execution request packet transmitted by the RX at different times for each transmitting antenna, the TX performs transmission power control at different times for each transmitting antenna accordingly.

The TX controls at least one of the communication prohibition period, power transmission period, preparation period, and power transmission power control period for each power transmission antenna so that the timing is different for at least one power transmission antenna.

Alternatively, when the TX simultaneously receives execution request packets from the RX for each transmitting antenna, the TX may control the timing at which the TX executes the waveform attenuation method (transmitted power control) for each transmitting antenna to be shifted by a predetermined period and executed at different timings. After S1808, the process proceeds to S1809.

In S1809, the RX receives information from the TX indicating that the foreign object detection operation has been completed at each transmitting antenna. This information includes information used for foreign object determination at the transmitting antenna selected by the RX. In S1810, the RX determines whether or not the result of the foreign object detection determination has been received from the TX. The processes of S1810 to S1814 are similar to the processes of S1608 to S1612 in FIG. 16, respectively, and therefore will not be described here.

FIG. 20 is a sequence diagram explaining another example of processing of the power transmitting device and the power receiving device according to the first embodiment, showing an example of the operation of the TX and the RX. Only the differences from FIG. 17 will be explained. After the RX determines the execution request for foreign object detection, it selects the power transmitting antenna related to the execution of foreign object detection and determines the length of the detection processing period. The RX transmits an execution request packet requesting the TX to detect a foreign object using the waveform attenuation method.

The TX that receives the execution request packet sets the length of the detection process period for the power transmission antenna selected by the RX. Note that in the above example, the TX and RX perform control through communication based on the first standard (WPC standard) between the first communication unit 104 of the TX and the first communication unit 204 of the RX.

The TX and RX may perform control through 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 and the second communication unit 212 of the RX. The TX may have a second communication unit 109 in each of the

power transmitting units

103a, 103b, and 103c. The RX may have a second communication unit 212 in each of the

power receiving units

203a, 203b, and 203c. In this case, faster communication is possible, making it possible to perform appropriate control.

According to this embodiment, in a power transmission device having multiple power transmission antennas, it is possible to appropriately control the processing period for the measurement process performed during the period when power transmission is restricted.

[Second embodiment]
Next, a second embodiment of the present disclosure will be described. In this embodiment, a case will be described in which the length (time) of each period related to the power transmission control for multiple power transmitting antennas is set to a different value and foreign object detection is performed using the waveform attenuation method. By executing the foreign object detection process for multiple power transmitting antennas and performing a foreign object determination based on multiple detection results, more reliable foreign object detection can be achieved.

In the method described in the first embodiment, for example, when transmission power control is performed for multiple transmission antennas using the same transmission power control period, noise may occur in a specific frequency band. In general, when transmitting a sine wave of a specific frequency, the spectrum is limited to that frequency.

If there is a transmission pause for a specified period during the transmission of a sine wave of a specified frequency, the spectrum will have a spectrum other than the specified frequency, depending on the transmission pause period and cycle. With transmission power control for multiple transmission antennas, it is assumed that multiple detection processing periods are each set to the same length and repeated multiple times.

In this case, electromagnetic waves with relatively large power may be generated in a specific frequency band other than the frequency band used for power transmission (e.g., 87 kHz to 205 kHz). For example, if the power transmitted from TX to RX is smaller than a specified value, the electromagnetic waves in the specific frequency band may not be so large that no problem may occur.

In other words, when the transmission power is less than a predetermined value, as described in the first embodiment, setting the lengths of the multiple detection processing periods related to the execution of the waveform attenuation method for multiple transmission antennas to the same optimal value is effective in performing highly accurate foreign object detection. However, when the transmission power is greater than the predetermined value, the generated electromagnetic waves may become noise that may cause malfunctions in other devices.

In addition, the Radio Laws of each country set limits on power in each frequency band, but depending on the power transmission conditions, the strength of electromagnetic waves generated at frequencies other than those between 87 kHz and 205 kHz may exceed the regulated values.

In this embodiment, a method is described for controlling each period related to the transmission power control of the waveform attenuation method executed by multiple transmission antennas to different lengths. The detection processing period related to the waveform attenuation method executed by each transmission antenna is set to be a different length for all transmission antennas involved in the execution of the waveform attenuation method, or at least for some of the transmission antennas.

For example, the communication prohibition periods corresponding to the first through Nth power transmitting antennas involved in the execution of the waveform attenuation method are all set to different lengths. Alternatively, the length of the communication prohibition period corresponding to at least one of the first through Nth power transmitting antennas is set to a length different from the communication prohibition periods corresponding to the other power transmitting antennas.

These items also apply to the power transmission period, preparation period, and power transmission power control period corresponding to the first to Nth power transmission antennas, respectively. Alternatively, for example, the control may be configured so that the length of the entire detection processing period including at least the power transmission power control period corresponding to the first power transmission antenna is different from the length of the detection processing period including at least the power transmission power control period corresponding to the second power transmission antenna.

Furthermore, the configuration may be such that the length of at least one of the communication prohibition period, power transmission period, preparation period, and power transmission power control period related to the first power transmitting antenna is controlled to be different from the length of the corresponding period in the detection processing period related to the second power transmitting antenna. In controlling each period performed by the TX and RX, it is possible to change the length and timing of the period (start or end point of the period).

For example, the TX sets the communication prohibition period, power transmission period, preparation period, and power transmission power control period for each power transmitting antenna to the same timing for each power transmitting antenna based on the determined detection processing period. When the RX determines the timing for executing the waveform attenuation method for each power transmitting antenna, it can simultaneously transmit an execution request packet that determines the timing for transmission to the TX.

Alternatively, if the TX determines the timing for executing the waveform attenuation method for each transmitting antenna, the TX can execute the waveform attenuation method at the same time. In either case, it is possible to simplify the control.

Alternatively, the TX can control, based on the determined detection processing period, at least one of the communication prohibition period, power transmission period, preparation period, and power transmission power control period for each power transmission antenna to have different timing for at least one power transmission antenna.

This makes it possible to reduce the level of noise generated by the TX at frequencies other than those used to transmit power. In addition, when the TX performs transmission power control, the received power of the RX temporarily decreases, but it is possible to suppress the amount of this decrease.

The method for setting each of the above periods is as described in the first embodiment. For example, the TX or RX determines the optimal length of each period based on the setting method described in the first embodiment. However, in order to vary the length of the detection processing period, it is not necessary to set the period to the optimal length each time.

For example, when the first power transmitting antenna detects a foreign object for the first time, the length of the detection processing period is determined by the method of the first embodiment, and from the second time onwards, a detection processing period is determined that is adjusted to have a length different from the first detection processing period. In addition, the method for adjusting the period length at this time may be any method.

The TX also determines the detection processing period based on information contained in the execution request packet received from the RX. The execution request packet includes information for determining the length of the detection processing period. The RX sets the length of the detection processing period corresponding to the information so that it is a different length for each transmitting antenna where the waveform attenuation method is executed.

In this embodiment, for example, the length (time) of the detection processing period is set to a different value for each of multiple transmitting antennas involved in the execution of the waveform attenuation method. By suppressing noise in a specific frequency band, more accurate foreign object detection can be implemented. The method described in the first embodiment can be applied to the method of foreign object determination that is performed based on multiple measurement results obtained when the TX measures waveform attenuation indices (Q value, etc.) for multiple transmitting antennas.

With reference to FIG. 14(A), this embodiment will be described in an example in which the TX transmits power to the RX using three transmitting antennas, and the RX receives power wirelessly using one receiving antenna. FIG. 21 is a flowchart explaining the processing of the power transmitting device in the second embodiment, and shows the processing of the TX.

The processes in steps S1901 to S1904 and S1909 to S1916 in FIG. 21 are similar to the processes in steps S1501 to S1504 and S1509 to S1516 in FIG. 15, respectively, and therefore will not be described.

After S1904, the process proceeds to S1905. The TX waits until it receives a packet requesting execution of foreign object detection from the RX (No in S1905). If the TX receives a packet requesting execution of foreign object detection from the RX (Yes in S1905), the process proceeds to S1906. In S1906, the TX selects, based on the information contained in the packet requesting execution, a power transmitting antenna that will perform the foreign object detection operation from among the multiple power transmitting antennas that the TX possesses.

For example, in FIG. 14(A), three transmitting antennas to be used for transmitting power to RX are selected based on the information contained in the execution request packet. Next, in S1907, TX sets each period related to transmission power control for the three selected transmitting antennas based on the information in the foreign object detection request packet.

The TX may control the timing of the waveform attenuation method (transmission power control) executed by each transmission antenna so that it is the same. The method of control is as described in the first embodiment. In other words, the communication inhibition period, transmission period, preparation period, and transmission power control period related to the waveform attenuation method executed by the TX at each transmission antenna are the same for each transmission antenna.

Alternatively, the TX may control the timing of the waveform attenuation method (transmission power control) executed by each transmission antenna to be different. The method of this control is as described in the first embodiment. In other words, at least one of the communication inhibition period, transmission period, preparation period, and transmission power control period related to the waveform attenuation method executed by the TX at each transmission antenna has different timing for at least one transmission antenna.

In the example of FIG. 14(A), the periods related to the transmission power control for the three transmitting antennas selected by the TX are set to be different lengths. In S1908, the TX executes the transmission power control for the three selected transmitting antennas based on the respective set periods. Then, the process proceeds to S1909.

As described above, the detection processing period related to the waveform attenuation method executed by each transmitting antenna is set to a different length for all transmitting antennas for which the waveform attenuation method is executed, or for at least some of the transmitting antennas.

Next, the processing performed by RX will be explained using FIG. 16. The processing from S1601 to S1605 and S1608 to S1612 is the same as in the first embodiment, so the explanation of those will be omitted.

If in S1605 the RX determines to request foreign object detection using the waveform attenuation method from the TX (Yes in S1605), the process proceeds to S1606. In S1606, the RX determines the length and timing of the detection processing period related to the foreign object detection process. For example, the detection processing period is a period including a preparation period, a transmission power control period, a communication prohibition period, and a power transmission period.

In S1607, RX transmits to TX an execution request packet including information for determining each period related to transmission power control. The information included in the execution request packet is, for example, information for determining the length of the transmission power control period and the length of the communication prohibition period.

Here, we will explain the execution request packet that the RX sends to the TX, which contains information for determining each period related to the transmission power control. The RX sends execution request packets to the TX the same number of times as the number of transmitting antennas related to the execution of the waveform attenuation method. The transmitting antennas related to the execution of the waveform attenuation method are the first to third transmitting antennas, and the RX sends the first to third execution request packets to each transmitting antenna.

The first to third execution request packets each include information for determining each period related to the transmission power control of the first to third power transmitting antennas. At least some of this information is set differently for the first to third power transmitting antennas. The RX sets each period of the detection processing period one by one using the method described in the first embodiment.

RX shifts each period of the detection processing period by a specified amount based on each set period, and sets two new periods for each detection processing period. As a result, three periods of the detection processing period are determined by RX. Each period of the detection processing period determined by RX is of a different length (time).

The RX allocates the determined detection processing period to each of the first to third power transmitting antennas. In this way, the detection processing period related to the waveform attenuation method executed by each power transmitting antenna is set to a different length for all power transmitting antennas involved in the execution of the waveform attenuation method, or for at least some of the power transmitting antennas.

Note that, as in the first embodiment, the first to third execution request packets may be sent as separate execution request packets or as a single execution request packet from RX to TX.

Next, referring to FIG. 21 and FIG. 16, another method for setting the detection processing period for the three transmitting antennas involved in the execution of the waveform attenuation method will be described. In S1606, the RX determines each of the detection processing periods one by one by the method described in the first embodiment. In S1607, the RX transmits one execution request packet including information on the determined detection processing period to the TX.

In S1905, the TX receives the execution request packet, that is, a packet including one piece of time information (information representing a representative value) for each period of the detection processing period, from the RX. In S1906, the TX selects, from among the multiple power transmitting antennas, a power transmitting antenna that will perform the foreign object detection operation.

The method for selecting the transmitting antenna is the method described in the first embodiment (FIG. 15: S1506). In S1907, the TX shifts each of the detection processing periods by a predetermined time based on each of the detection processing periods based on the acquired time information, and sets two new detection processing periods for each period.

The TX determines three periods each. The lengths of the three sets of periods determined by the TX are different. The TX sets each of the determined detection processing periods (each of the three sets of periods) as detection processing periods corresponding to the first to third transmitting antennas, respectively. In this way, it is possible to set each period to a different length for all transmitting antennas involved in the execution of the waveform attenuation method, or for at least some of the transmitting antennas.

Next, referring to Fig. 22 and Fig. 14B and Fig. 18, an example in which TX transmits power to RX using three power transmitting antennas and RX wirelessly receives power using three power receiving antennas will be described in this embodiment. Fig. 22 is a flowchart for explaining the processing of the power receiving device in the second embodiment, and shows the processing of RX. Note that the processing of S1701 to S1704 and S1708 to S1715 in Fig. 18 is the same as in the first embodiment, and therefore the description thereof will be omitted.

After S1704, the process proceeds to S1705. The TX waits until it receives a packet requesting execution of foreign object detection from the RX (No in S1705). If the TX receives a packet requesting execution of foreign object detection from the RX (Yes in S1705), it proceeds to S1706.

Here, the TX sets each period related to the transmission power control for each transmitting antenna using the method described above, based on the time information in the execution request packet received from the RX. Each period related to the transmission power control for the three transmitting antennas selected by the RX is set to a different length.

In S1707, the TX performs transmission power control for the three transmitting antennas selected by the execution request packet based on the set periods. For example, the RX can control the timing of the waveform attenuation method that the TX executes for each transmitting antenna so that they are the same.

The method of this control is as described in the first embodiment. In this case, the communication prohibition period, power transmission period, preparation period, and power transmission power control period related to the waveform attenuation method are the same for each power transmission antenna. Alternatively, the RX may control the timing of the waveform attenuation method executed by the TX for each power transmission antenna to be different.

The method of this control is as described in the first embodiment. In this case, at least one of the communication inhibition period, power transmission period, preparation period, and power transmission control period related to the waveform attenuation method has different timing for at least one power transmission antenna.

Next, the processing performed by RX will be described with reference to FIG. 22. Note that the processing of S2201 to S2206 and S2209 to S2214 in FIG. 22 is similar to the processing of S1801 to S1806 and S1809 to S1814 in FIG. 19, respectively, and therefore the description thereof will be omitted.

In S2207, the RX determines the detection processing period for the foreign object detection processing using the waveform attenuation method. The detection processing period is a period that includes the preparation period, the transmission power control period, the communication prohibition period, and the power transmission period.

In S2208, RX transmits to TX an execution request packet including information for determining each period related to transmission power control. The information is, for example, information for determining the length of the transmission power control period and the length of the communication prohibition period. The execution request packet may be RP0, RP1, or RP2, or individual packets may be used.

The RX transmits an execution request packet (first to third execution request packets) to each of the three transmitting antennas (first to third transmitting antennas) selected in S2206. The first to third execution request packets each include information for determining each period related to the transmission power control for the first to third transmitting antennas.

These pieces of information are set so that at least some of them are different for the first to third power transmitting antennas. For example, the RX sets each period of the detection processing period one by one using the method described in the first embodiment. The RX shifts each period of the detection processing period by a predetermined time based on each set period, and sets two new periods of the detection processing period each.

As a result, three periods are determined by the RX, and each of the three periods has a different length. The RX allocates the determined detection processing periods (each of the three sets of periods) to the first to third transmitting antennas. The detection processing periods related to the waveform attenuation method executed by each of the multiple transmitting antennas are set to different lengths for all transmitting antennas involved in the execution of the waveform attenuation method, or for at least some of the transmitting antennas.

The RX transmits an execution request packet including time information for determining each period related to the transmission power control from each of the three receiving antennas facing the transmitting antenna selected in S2206 to each of the three opposing transmitting antennas.

Alternatively, the RX transmits to the TX, for all transmitting antennas involved in the execution of the waveform attenuation method, an execution request packet including one piece of time information (information representing a representative value) for each period of the detection processing period set by the above-mentioned method. The TX receives from the RX an execution request packet including time information of the detection processing period for each transmitting antenna that executes the waveform attenuation method.

The TX sets two new detection processing periods each based on the received time information and shifts each detection processing period by a specified time, using each period as a reference. As a result, three periods each are determined by the TX.

The three detection processing periods determined by the TX are of different lengths. The TX sets each of the three detection processing periods determined as the detection processing periods for each of the first to third power transmitting antennas. Note that in the above example, the TX and RX are described as performing control through communication based on the first standard (WPC standard) between the first communication unit 104 of the TX and the first communication unit 204 of the RX.

The TX and RX may perform control through communication based on a second standard (a standard other than the WPC standard) performed between the second communication unit 109 of the TX and the second communication unit 212 of the RX. The TX may have a second communication unit 109 in each of the

power transmitting units

power receiving units

In this embodiment, the set value of the detection processing period related to the waveform attenuation method executed for each power transmitting antenna is set to a different value. In other words, the detection processing period is set to a different length for all power transmitting antennas involved in the execution of the waveform attenuation method, or at least for some of the power transmitting antennas. According to this embodiment, it is possible to achieve more reliable foreign object detection while suppressing noise in specific frequency bands other than the frequency band used for power transmission.

[Third embodiment]
Next, a third embodiment of the present disclosure will be described. In this embodiment, a method of switching between the method described in the first embodiment and the method described in the second embodiment according to a predetermined condition will be described. In the method of the first embodiment, the length of each period related to the transmission power control is set to the same value for each selected power transmitting antenna.

When foreign object detection using the waveform attenuation method is performed at multiple selected transmitting antennas, the TX sets the length of each period related to the transmission power control to an optimal value and performs transmission power control at the selected transmitting antenna. Compared to the method of the second embodiment, this method has the advantages of enabling more accurate foreign object detection, enabling foreign object detection in a shorter time, enabling more stable communication, and enabling faster communication.

On the other hand, in the method of the second embodiment, the length of each period related to the transmission power control is set to a different value for each selected power transmitting antenna. This method has the advantage that, compared to the method of the first embodiment, noise can be suppressed in a specific frequency band when foreign object detection is performed using the waveform attenuation method with multiple selected power transmitting antennas.

The above "predetermined condition" is a condition corresponding to whether the power transmitted from TX to RX or its set value is less than a threshold value or greater than or equal to a threshold value. For example, even if the method of the first embodiment is used when the power transmitted from TX to RX or its set value is less than a predetermined value, noise in a particular frequency band may not be so large that no problem occurs.

Therefore, if the transmission power or its set value is smaller than a predetermined value, the method of the first embodiment can be used, and if the transmission power or its set value is equal to or greater than the predetermined value, the method of the second embodiment can be used. Note that, as described above, the set value of the transmission power can be the set value related to the transmission power determined by negotiation between the TX and the RX.

Alternatively, the information stored in RP0, RP1, and RP2 that the RX transmits to the TX may be used. The information on the RX's received power value stored in these packets may be used in place of the transmitted power. Alternatively, the load power consumed by the RX's load may be used in place of the transmitted power.

Another example of the above "predetermined condition" is a condition that corresponds to the strength of the electromagnetic coupling between the TX transmitting antenna and the RX receiving antenna. For example, if the electromagnetic coupling between the two antennas is strong and it is determined that the power leaking between the antennas is less than a reference value (threshold value), the method of the first embodiment can be used.

The reason for this is that noise in a particular frequency band may not be a problem. If the values of the coupling state index for both antennas are within the reference range and the leaking power is less than the reference value, the method of the first embodiment can be used. Also, if the values of the coupling state index for both antennas are outside the reference range and the leaking power is equal to or greater than the reference value, the method of the second embodiment can be used.

The strength of the electromagnetic coupling between the transmitting antenna and the receiving antenna can vary due to the following reasons. The first reason is related to the performance of the transmitting antenna and the receiving antenna. For example, the greater the difference between the size (antenna diameter) of the transmitting antenna and the size (antenna diameter) of the receiving antenna, the weaker the electromagnetic coupling between the two antennas may be.

When multiple types of transmitting antennas and receiving antennas exist, the RX mounted on the TX controls switching between the method of the first embodiment and the method of the second embodiment. For example, when a first type of transmitting antenna (or receiving antenna) is used, the method switches to the method of the first embodiment, and when a second type of transmitting antenna (or receiving antenna) is used, the method switches to the method of the second embodiment.

The second cause is related to misalignment of the RX placed on the TX. For example, if the position of the RX is misaligned from its initial position relative to the TX, the relative positions of the transmitting antenna and the receiving antenna change, and the electromagnetic coupling between the two antennas may become weaker than before the misalignment.

The TX or RX detects a change in the relative position between the TX and RX, and performs control to switch to the method of the first embodiment if the amount of positional deviation is within a specified range, and to switch to the method of the second embodiment if the amount of positional deviation is not within the specified range.

Methods for detecting changes in the relative position between TX and RX include using the results of measurements made by photoelectric sensors, eddy current displacement sensors, contact displacement sensors, ultrasonic sensors, image discrimination sensors, weight sensors, etc., mounted on the TX or RX.

Alternatively, there is a method of measuring the change in the Quality Factor of the transmitting antenna or the receiving antenna measured in the time domain, or the change in the Quality Factor of the transmitting antenna or the receiving antenna measured in the frequency domain.

The quality factor of a transmitting antenna can be measured by the Q value measurement method, the waveform attenuation method, etc. Alternatively, there is a method of measuring the change in the coupling condition index (coupling coefficient) between the transmitting antenna and the receiving antenna.

Methods for measuring the Quality Factor used to detect misalignment include, for example, transmitting a signal at a resonant frequency (sine wave, square wave, etc.) and measuring the Quality Factor at that resonant frequency. Another method is to transmit signals at multiple frequencies near the resonant frequency multiple times and measure their Quality Factors.

Alternatively, when measuring electrical characteristics, a signal (e.g., a pulse wave) containing all or some of the frequency components of multiple frequencies is sent once, and the measurement results are processed (e.g., a Fourier transform). Then, the Quality Factor at multiple frequencies is measured.

Alternatively, a method may be used that uses the resonant frequency of the power transmitting antenna, the sharpness of the resonant curve, or the inductance value of the power transmitting antenna, the coupling coefficient between the power transmitting antenna and an object placed on the TX, or the measurement results of the electrical characteristics of the power transmitting unit including the power transmitting antenna of the TX. In addition, a determination may be made based on the measurement results of the electrical characteristics at one or more frequencies.

In addition, a method for measuring electrical characteristics at multiple frequencies can be achieved by transmitting signals of each frequency (sine wave, square wave, etc.) multiple times and measuring the electrical characteristics of the signals of each frequency. This method has the advantage that measurements can be made with relatively little calculation processing in the power transmission device.

Alternatively, when measuring electrical characteristics, a signal (e.g., a pulse wave) having all frequency components at multiple frequencies can be transmitted once, and the measurement results can be processed (e.g., a Fourier transform) to calculate the electrical characteristics at multiple frequencies.

Alternatively, when measuring electrical characteristics, a signal having some frequency components at multiple frequencies can be transmitted multiple times, and the measurement results can be processed (e.g., a Fourier transform) to calculate the electrical characteristics at multiple frequencies.

This method has the advantage that the number of times signals need to be transmitted for measurement can be reduced, allowing measurements to be made in a relatively short time. Alternatively, a method may be used in which the change in the relative position between the TX and RX is detected by measuring the change over time in the received power value of the RX.

Furthermore, the TX and RX may perform wireless communication according to a standard different from the WPC standard. In this case, if the method of the first embodiment is used, noise generated by the transmission power control of the TX may affect the communication. Therefore, if the TX and RX do not perform wireless communication according to a standard different from the WPC standard, control is performed to switch to the method of the first embodiment, and if the TX and RX perform wireless communication according to a standard different from the WPC standard, control is performed to switch to the method of the second embodiment.

In this embodiment, by selectively using the method of the first embodiment and the method of the second embodiment according to predetermined conditions, it is possible to appropriately control each period related to the transmission power control. The control entity that decides to change from the method of the first embodiment to the method of the second embodiment (or vice versa) may be either the control unit of the TX or the control unit of the RX.

[Applications of the present disclosure]
The contents of the first to third embodiments may be implemented in any combination. In addition, other known measurement methods related to the Quality Factor, which is one of the waveform attenuation indexes, can also be applied to the above embodiments. In addition, the processing described in the embodiments may be performed by devices different from the RX and TX.

For example, another device may measure the voltage or current during the period when the TX limits power transmission, and/or determine the presence or absence of a foreign object based on the measurement results. The other device may also determine the length of the detection processing period. The other device may also control the RX and TX to perform the processing described in the above embodiment.

When the TX or RX detects the possible presence of a foreign object by the foreign object detection method, the TX or RX performs a first notification process for the user. The notification to the user is a notification encouraging the removal of the foreign object that is between the power transmitting antennas or on the power transmitting antenna. This can be realized, for example, by using the UI unit 202 of the RX to perform various outputs to the user.

The various outputs include the screen display on the LCD panel, the blinking or color change of the LED, the audio output from the speaker, and the vibration of the RX body by the vibration motor. By notifying the user, if the foreign object is removed, the possibility of more appropriate power transmission from the TX to the RX increases. Alternatively, the TX may have the same function as the UI unit 202 of the RX, and may notify the user to encourage the removal of the foreign object on the TX.

Alternatively, the coupling between the transmitting antenna and the receiving antenna may be weakened due to misalignment between the two antennas. If the measured value of the antenna coupling state index falls below a predetermined threshold, the RX performs a second notification process to prompt the user to reposition the RX on the TX. This can be achieved by using the UI unit to provide various outputs to the user as described above.

If the RX on the TX is in the optimal position as a result of the notification to the user, the possibility of appropriate power transmission from the TX to the RX increases. Note that the first notification process and the second notification process may have different notification contents so that the user can distinguish between them.

For example, there are ways to make the LED blink or change color differently, to make the sound output from the speaker different, and to make the vibration pattern of the RX body using a vibration motor, etc.

Some (or in some cases, all) of the configurations in the above embodiment may be replaced with other configurations that perform similar functions, or may be omitted, or other configurations may be added. Furthermore, without being limited by the WPC standard, it is possible to apply the present invention to other systems that use electromagnetic induction, magnetic field resonance, electric field resonance, microwaves, lasers, etc.

The power transmitting device and the power receiving device may be, for example, a tablet device, a hard disk device, a memory device, or an information processing device such as a personal computer (PC). They may also be imaging devices such as a still camera or a video camera, image input devices such as a scanner, or image output devices such as a printer, a copier, or a projector.

The power receiving device of the present disclosure may also be an information terminal device. For example, the information terminal device has a display unit (display) that displays information to a user and is supplied with power received from the power receiving antenna.

The power received from the power receiving antenna is stored in a power storage unit (battery), and power is supplied from the battery to the display unit. In this case, the power receiving device may have a communication unit that communicates with other devices different from the power transmitting device. The communication unit may be compatible with communication standards such as NFC communication and the fifth generation mobile communication system (5G).

The power receiving device of the present disclosure may also be a vehicle such as an automobile. For example, an automobile serving as a power receiving device may receive power from a charger (power transmitting device) via a power transmitting antenna installed in a parking lot. Also, an automobile serving as a power receiving device may receive power from a charger (power transmitting device) via a power transmitting antenna embedded in the road.

In such automobiles, the received power is supplied to a battery. The power from the battery may be supplied to a driving unit (motor, electric unit) that drives the wheels, or it may be used to drive sensors used for driving assistance or a communication unit that communicates with external devices.

In other words, in this case, the power receiving device may have, in addition to the wheels, a battery, a motor or sensor that is driven using the received power, and even a communication unit that communicates with devices other than the power transmitting device. Furthermore, the power receiving device may have a housing unit for housing a person. For example, the sensor may be a sensor used to measure the distance between the vehicle and other obstacles.

The communication unit may be compatible with, for example, the Global Positioning System (GPS). The communication unit may also be compatible with communication standards such as the fifth generation mobile communication system (5G). The vehicle may also be a bicycle or a motorcycle.

The power receiving device of the present disclosure may also be an electric tool, a home appliance, etc. These devices, which are power receiving devices, may have a battery as well as a motor that is driven by the received power stored in the battery. These devices may also have a notification means for notifying the remaining battery charge, etc. These devices may also have a communication unit that communicates with other devices other than the power transmitting device.

The communication unit may be compatible with communication standards such as NFC and the fifth generation mobile communication system (5G). The power transmission device disclosed herein may be an in-vehicle charger that transmits power to a mobile information terminal device such as a smartphone or tablet that supports wireless power transmission within an automobile.

Such an on-board charger may be installed anywhere in the vehicle. For example, the on-board charger may be installed in the vehicle's console, instrument panel (dashboard), between the passenger seats, on the ceiling, or in the door. However, it is best not to install it in a location that interferes with driving.

In addition, while the power transmission device has been described as an example of an on-board charger, such chargers are not limited to those installed in vehicles, and may also be installed on transport vehicles such as trains, airplanes, and ships. In this case, the charger may also be installed in a position between passenger seats, on the ceiling, or in the door.

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

[Other embodiments]
The present disclosure can also be realized by supplying a program that realizes one or more functions of the above-described embodiments to a system or device via a network or storage medium, and having one or more processors in a computer of the system or device read and execute the program.

It can also be realized by a circuit (e.g., an ASIC) that realizes one or more functions. Also, some of the processing described with reference to the flowcharts of this disclosure may be realized by hardware.

In this case, for example, a specific compiler can be used to automatically generate a dedicated circuit on the FPGA from a program for implementing each step. Also, a gate array circuit can be formed in the same way as an FPGA, and implemented as hardware.

The present invention has been described above in detail based on a preferred embodiment, but the present invention is not limited to the above embodiment, and various modifications are possible based on the spirit of the present invention, and are not excluded from the scope of the present invention. Furthermore, the present invention includes, for example, implementations that use at least one processor or circuit to realize the functions of the above embodiment. It is also possible to use multiple processors to perform distributed processing.

CROSS-REFERENCE TO RELATED APPLICATIONS
This application claims the benefit of earlier filed Japanese Patent Application No. 2022-176565, filed on November 2, 2022. The contents of the above Japanese patent application are incorporated herein by reference in their entirety.

Claims

A power transmitting means for wirelessly transmitting power to a power receiving device using a plurality of power transmitting coils;
A communication means for communicating with the power receiving device;
A measuring means for measuring a voltage or a current, or both the voltage and the current, associated with the power transmitting coil;
a control unit that controls power transmission from the power transmitting unit to the power receiving device by using a power transmitting coil selected from the plurality of power transmitting coils,
The control means, when the communication means receives a request from the power receiving device to execute a detection process for an object different from the power receiving device, performs control to limit power transmission to a plurality of selected power transmitting coils, and sets a processing period for the measurement process performed by the measurement means for each of the power transmitting coils based on information on the processing period determined by the power receiving device for each of the power transmitting coils.
The measurement means performs the measurement at two or more points during a period in which the power transmitted from the power transmitting means to the power receiving device is limited by the control means,
the communication means receives first information on a processing period during which the measurement means performs a first measurement process on a first power transmitting coil among the plurality of power transmitting coils, and second information on a processing period during which the measurement means performs a second measurement process on a second power transmitting coil,
The power transmitting device according to claim 1, characterized in that, when the communication means receives the execution request from the power receiving device, the control means sets a processing period for the measurement means to perform the first measurement processing based on the first information, and sets a processing period for the measurement means to perform the second measurement processing based on the second information.
3 . The power transmitting device according to claim 1 , wherein the control means sets a length or timing of the processing period based on information received by the communication means from the power receiving device. 4 .
The power transmitting device according to claim 2, characterized in that the control means performs a first setting in which the processing period during which the measurement means performs the first measurement processing and the processing period during which the second measurement processing are performed are the same length, or a second setting in which the processing periods are different lengths.
The power transmitting device according to claim 4 , wherein the control means performs control for switching between the first setting and the second setting.
The power transmission device according to claim 5, characterized in that the control means performs control to set the first setting when a condition is met that the transmission power or its set value is less than a threshold value, or a value of an index representing the electromagnetic coupling state between the transmission coil and the receiving coil of the power receiving device is within a predetermined range, and performs control to set the second setting when the condition is not met.
The power transmission device according to claim 1, characterized in that, when the communication means receives from the power receiving device a request to execute a detection process for the object based on the attenuation state of the transmission wave output by the power transmitting means, the control means limits power transmission by a selected power transmitting coil, and performs a detection process for the object corresponding to the power transmitting coil using an index representing the attenuation state obtained by measurement performed by the measurement means on the power transmitting coil.
a power receiving unit that wirelessly receives power from a power transmitting device having a plurality of power transmitting coils by using a power receiving coil;
A communication means for communicating with the power transmitting device;
a control unit that controls transmission of an execution request to the power transmitting device via the communication unit to request the power transmitting device to execute a detection process for an object different from the power receiving device;
The control means, when transmitting the execution request to the power transmitting device via the communication means, determines information on a processing period related to a measurement process performed by a measuring means of the power transmitting device for each of the selected power transmitting coils during a period in which power transmission is restricted for the selected power transmitting coils, and controls the information to be transmitted to the power transmitting device via the communication means.
the control means determines first information on a processing period during which the measurement means performs a first measurement process on a first power transmitting coil among the plurality of power transmitting coils, and second information on a processing period during which the measurement means performs a second measurement process on a second power transmitting coil;
The power receiving device according to claim 8 , wherein the communication means transmits the first and second information to the power transmitting device.
The power receiving device according to claim 8 , wherein the information on the processing period is information for the power transmitting device to set a length or timing of the processing period.
The power receiving device according to claim 9 , characterized in that the first and second information are information for the power transmitting device to set a processing period for performing the first measurement processing and a processing period for performing the second measurement processing to have the same length.
The power receiving device according to claim 9 , characterized in that the first and second information are information for the power transmitting device to set a processing period for performing the first measurement processing and a processing period for performing the second measurement processing to different lengths.
The power receiving device according to claim 8, characterized in that the control means controls the communication means to transmit to the power transmitting device a request to execute the object detection process based on the attenuation state of the transmitted radio wave output by the power transmitting device, and controls the communication means to receive from the power transmitting device the detection results of the object detection process.
A wireless power transmission system including a power transmitting device and a power receiving device,
The power transmitting device is
A power transmitting means for wirelessly transmitting power to the power receiving device using a plurality of power transmitting coils;
A first communication means for communicating with the power receiving device;
A measuring means for measuring a voltage or a current, or both the voltage and the current, associated with the power transmitting coil;
a first control means for limiting power transmission from the power transmitting means to the power receiving device by controlling power transmission performed by the power transmitting means using a power transmitting coil selected from the plurality of power transmitting coils;
The power receiving device is
power receiving means for wirelessly receiving power from the power transmitting device using a power receiving coil;
A second communication means for communicating with the power transmitting device;
a second control unit that controls transmission of an execution request to the power transmitting device via the second communication unit to request the power transmitting device to execute a detection process for an object different from the power receiving device;
when transmitting the execution request to the power transmitting device via the second communication means, the second control means performs control to determine information on a processing period related to a measurement process to be performed by the measurement means for each of the selected power transmitting coils during a period in which power transmission to the selected power transmitting coils is restricted, and to transmit the information to the power transmitting device via the second communication means;
The wireless power transmission system is characterized in that, when the first communication means receives the execution request from the power receiving device, the first control means performs control to limit power transmission to the selected plurality of power transmitting coils, and sets a processing period for the measurement process performed by the measurement means for each of the power transmitting coils based on information of the processing period determined by the power receiving device for each of the power transmitting coils.
A method for controlling wireless power transmission in which power is wirelessly transmitted from a power transmitting device to a power receiving device, comprising:
a power transmitting step of wirelessly transmitting power to the power receiving device using a plurality of power transmitting coils by a power transmitting unit of the power transmitting device;
a measuring step of measuring a voltage or a current, or both the voltage and the current, associated with the power transmitting coil by a measuring means of the power transmitting device;
a first control step of controlling power transmission performed by the power transmitting means using a power transmitting coil selected from the plurality of power transmitting coils by a first control means included in the power transmitting device;
a second control step of controlling, by a second control means of the power receiving device, to transmit an execution request to the power transmitting device to request the power transmitting device to execute a detection process for an object different from the power receiving device, and determining information on a processing period related to a measurement process to be performed by the measurement means for each of the selected power transmitting coils during a period in which power transmission to the selected power transmitting coils is restricted, and transmitting the information to the power transmitting device;
a first control means, when the power transmitting device receives the execution request from the power receiving device, performing control to limit power transmission to the selected power transmitting coils, and setting a processing period for the measurement process performed by the measuring means for each of the power transmitting coils based on information on the processing period determined by the power receiving device for each of the power transmitting coils.
A method for controlling wireless power transmission in which power is wirelessly transmitted from a power transmitting device to a power receiving device, comprising:
a power transmitting step of wirelessly transmitting power to the power receiving device using a plurality of power transmitting coils by a power transmitting unit of the power transmitting device;
a measuring step of measuring a voltage or a current, or both the voltage and the current, associated with the power transmitting coil by a measuring means of the power transmitting device;
a first control step of controlling power transmission performed by the power transmitting means using a power transmitting coil selected from the plurality of power transmitting coils by a first control means included in the power transmitting device;
a second control step of controlling, by a second control means of the power receiving device, to transmit an execution request to the power transmitting device to request the power transmitting device to execute a detection process for an object different from the power receiving device, and determining information on a processing period related to a measurement process to be performed by the measurement means for each of the selected power transmitting coils during a period in which power transmission to the selected power transmitting coils is restricted, and transmitting the information to the power transmitting device;
A computer-readable storage medium storing a program for causing each computer of the power transmitting device and the power receiving device to execute each step of a control method for wireless power transmission, characterized in that in the first control step, when the power transmitting device receives the execution request from the power receiving device, the first control means performs control to limit power transmission to the selected plurality of power transmitting coils, and sets a processing period for the measurement process performed by the measurement means for each of the power transmitting coils based on information of the processing period determined by the power receiving device for each of the power transmitting coils.