Metal detection method, metal detection device, metal detection method for wireless power supply device, and wireless power supply device

A metal detection device comprising:

• a metal detection coil arranged in a metal detection area, wherein the metal detection coil is excited, and an electromagnetic wave radiated from the metal detection coil is used to detect whether or not metal exists in the metal detection area;
• an oscillation circuit that generates a sinusoidal oscillating current having a single fundamental frequency, wherein the oscillation circuit supplies the oscillating current to the metal detection coil to excite the metal detection coil;
• a harmonic level detection circuit that detects a harmonic component of the fundamental frequency component of the oscillating current and generates a detection signal;
• a comparison circuit that compares a signal level of the detection signal and a reference value, which is set in advance;
• and
• a processing circuit that determines whether or not metal exists in the metal detection area based on a comparison result, wherein when determining that metal exists in the metal detection area, the processing circuit drives a notification unit to issue a notification indicating detection of metal.

A contactless power supplying device comprising:

• a primary coil arranged in a power supplying area, wherein when an electric instrument is placed in the power supplying area, the primary coil arranged in the power supplying area is excited to cause electromagnetic induction at a secondary coil of a power receiving device arranged in the electric instrument to supply power to the electric instrument;
• a metal detection coil arranged in the power supplying area;
• an oscillation circuit that generates a sinusoidal oscillating current having a single fundamental frequency and supplies the oscillating current to the metal detection coil to excite the metal detection coil;
• a harmonic level detection circuit that detects a harmonic component of the fundamental frequency component of the oscillating current and generates a detection signal;
• a comparison circuit that compares a signal level of the detection signal and a reference value, which is set in advance;
• and
• a control circuit that determines whether or not metal exists in the power supplying area based on a comparison result, wherein when determining that metal exists in the power supplying area, the control circuit causes the oscillation circuit to stop the excitation of the metal detection coil.

A contactless power supplying device comprising:

• a primary coil arranged in a power supplying area, wherein when an electric instrument is placed in the power supplying area, the primary coil arranged in the power supplying area is excited to cause electromagnetic induction in a secondary coil of a power receiving device arranged in the electric instrument to supply power to the electric instrument;
• an excitation circuit that generates a sinusoidal oscillating current having a single fundamental frequency and supplies the oscillating current to the primary coil to excite the primary coil;
• a harmonic level detection circuit that detects a harmonic component of the fundamental frequency component of the oscillating current to generate a detection signal;
• a comparison circuit that compares a signal level of the detection signal with a reference value, which is set in advance;
• and
• a processing circuit that determines whether or not metal exists in the power supplying area based on a comparison result, wherein when determining that metal exists in the power supplying area, the processing circuit drives a notification unit to issue a notification indicating detection of metal.