Wireless power transmitting device, wireless power receiving device, and wireless power transmission system

A wireless power receiving device that transmits power by wireless from a feeding coil to a receiving coil, the wireless power receiving device comprising:

• the receiving coil;
• and
• a metallic foreign object detector,
• wherein the metallic foreign object detector includes:
• a sensor part having at least one antenna coil that receives a magnetic field or current to generate a vibration signal;
• a vibration time length measurement circuit that measures a vibration time length indicating a length of time required for a vibration of the vibration signal output from the sensor part corresponding to a predetermined wavenumber larger than 1;
• and
• a determination circuit that determines a presence/absence of a metallic foreign object approaching the antenna coil based on the vibration time length and a criterion vibration time length which is a vibration time length obtained in an absence of the approaching metallic foreign object, and
• wherein a measurement time of the vibration time length is less than a period of a power transmission frequency.

A wireless power transmission system that transmits power by wireless from a feeding coil to a receiving coil, the wireless power transmission system comprising:

• a wireless power transmitting device having the feeding coil;
• and
• a wireless power receiving device having the receiving coil,
• wherein at least one of the wireless power transmitting device and wireless power receiving device has a metallic foreign object detector,
• wherein the metallic foreign object detector includes:
• a sensor part having at least one antenna coil that receives a magnetic field or current to generate a vibration signal;
• a vibration time length measurement circuit that measures a vibration time length indicating a length of time required for a vibration of the vibration signal output from the sensor part corresponding to a predetermined wavenumber larger than 1;
• and
• a determination circuit that determines a presence/absence of a metallic foreign object approaching the antenna coil based on the vibration time length and a criterion vibration time length which is a vibration time length obtained in an absence of the approaching metallic foreign object, and
• wherein a measurement time of the vibration time length is less than a period of the power transmission frequency.

A wireless power transmitting device that transmits power by wireless from a feeding coil to a receiving coil, the wireless power transmitting device comprising:

• the feeding coil;
• and
• a metallic foreign object detector,
• wherein the metallic foreign object detector includes:
• a sensor part having at least one antenna coil that receives a magnetic field or current to generate a vibration signal;
• a vibration time length measurement circuit that measures a vibration time length indicating a length of time required for a vibration of the vibration signal output from the sensor part corresponding to a predetermined wavenumber larger than 1;
• a determination circuit that determines a presence/absence of a metallic foreign object approaching the antenna coil based on the vibration time length and a criterion vibration time length which is a vibration time length obtained in an absence of the approaching metallic foreign object;
• a drive circuit that applies voltage to the at least one antenna coil;
• a detection circuit that measures a power transmission frequency and detects a phase of voltage generated in the at least one antenna coil by a power transmission;
• and
• a control circuit that controls a timing of a voltage application performed by the drive circuit based on the power transmission frequency measured by the detection circuit and the phase of voltage detected by the detection circuit.

A wireless power receiving device that transmits power by wireless from a feeding coil to a receiving coil, the wireless power receiving device comprising:

• the receiving coil;
• and
• a metallic foreign object detector,
• wherein the metallic foreign object detector includes:
• a sensor part having at least one antenna coil that receives a magnetic field or current to generate a vibration signal;
• a vibration time length measurement circuit that measures a vibration time length indicating a length of time required for a vibration of the vibration signal output from the sensor part corresponding to a predetermined wavenumber larger than 1;
• a determination circuit that determines a presence/absence of a metallic foreign object approaching the antenna coil based on the vibration time length and a criterion vibration time length which is a vibration time length obtained in an absence of the approaching metallic foreign object;
• a drive circuit that applies voltage to the at least one antenna coil;
• a detection circuit that measures a power transmission frequency and detects a phase of voltage generated in the at least one antenna coil by a power transmission;
• and
• a control circuit that controls a timing of a voltage application performed by the drive circuit based on the power transmission frequency measured by the detection circuit and the phase of voltage detected by the detection circuit.

A wireless power transmission system that transmits power by wireless from a feeding coil to a receiving coil, the wireless power transmission system comprising:

• a wireless power transmitting device having the feeding coil;
• and
• a wireless power receiving device having the receiving coil,
• wherein at least one of the wireless power transmitting device and wireless power receiving device has a metallic foreign object detector, and
• wherein the metallic foreign object detector includes:
• a sensor part having at least one antenna coil that receives a magnetic field or current to generate a vibration signal;
• a vibration time length measurement circuit that measures a vibration time length indicating a length of time required for a vibration of the vibration signal output from the sensor part corresponding to a predetermined wavenumber larger than 1;
• a determination circuit that determines a presence/absence of a metallic foreign object approaching the antenna coil based on the vibration time length and a criterion vibration time length which is a vibration time length obtained in an absence of the approaching metallic foreign object;
• a drive circuit that applies voltage to the at least one antenna coil;
• a detection circuit that measures a power transmission frequency and detects a phase of voltage generated in the at least one antenna coil by a power transmission;
• and
• a control circuit that controls a timing of a voltage application performed by the drive circuit based on the power transmission frequency measured by the detection circuit and the phase of voltage detected by the detection circuit.