METALLIC FOREIGN OBJECT DETECTOR, WIRELESS POWER TRANSMITTING DEVICE, WIRELESS POWER RECEIVING DEVICE, AND WIRELESS POWER TRANSMISSION SYSTEM

A metallic foreign object detector is used in a wireless power transmission system that transmits power by wireless from a feeding coil to a receiving coil and includes an antenna coil, a capacitor that forms a resonance circuit together with the antenna coil, a vibration detection circuit configured to detect generation of a vibration signal in the resonance circuit, and a determination circuit that detects the presence/absence of a metallic foreign object according to the vibration signal. The vibration detection circuit is configured to output a detection state signal indicating the detection state of generation of the vibration signal. The determination circuit is configured to execute an operation of detecting the presence/absence of a metallic foreign object according to the detection state signal.