Method for detecting metal foreign object on contactless power supply device, contactless power supply device, contactless power reception device, and contactless power supply system
First Claim
1. A method for detecting whether or not a metal foreign object is present on a contactless power supply device that supplies power to a power reception device included in an electrical appliance using an electromagnetic induction phenomenon, the method comprising:
- transmitting an oscillation signal from the contactless power supply device to the power reception device;
detecting, from the oscillation signal received by the power reception device, a modulating wave based on a change in magnetic flux caused by the presence of a metal foreign object;
generating a modulated wave signal by modulating a carrier signal in accordance with the modulating wave to transmit the modulating wave to the contactless power supply device, and transmitting the modulated wave signal from the power reception device to the contactless power supply device; and
receiving the modulated wave signal transmitted from the power reception device with the contactless power supply device, and determining whether or not a metal foreign object is present based on comparison between a reference cycle and the cycle of a demodulated signal demodulated from the modulated wave signal, the cycle of the demodulated signal corresponding to the cycle of the modulating wave.
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Accused Products
Abstract
With a metal foreign object detecting method, a metal detection circuit arranged in a contactless power supply device transmits an oscillation signal to a modulation circuit of an electric appliance. The modulation circuit generates a square wave pulse signal from the oscillation signal. The cycle of the oscillation signal received by the modulation circuit changes in accordance with whether or not a metal piece is present. The modulation circuit modulates the square wave pulse signal to generate a modulated wave signal and transmits the modulated wave signal to the metal detection circuit of the power supply device. The metal detection circuit demodulates the modulated wave signal and determines whether or not a metal piece is present based on the cycle of the demodulated signal corresponding to the square wave pulse signal.
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Citations
12 Claims
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1. A method for detecting whether or not a metal foreign object is present on a contactless power supply device that supplies power to a power reception device included in an electrical appliance using an electromagnetic induction phenomenon, the method comprising:
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transmitting an oscillation signal from the contactless power supply device to the power reception device; detecting, from the oscillation signal received by the power reception device, a modulating wave based on a change in magnetic flux caused by the presence of a metal foreign object; generating a modulated wave signal by modulating a carrier signal in accordance with the modulating wave to transmit the modulating wave to the contactless power supply device, and transmitting the modulated wave signal from the power reception device to the contactless power supply device; and receiving the modulated wave signal transmitted from the power reception device with the contactless power supply device, and determining whether or not a metal foreign object is present based on comparison between a reference cycle and the cycle of a demodulated signal demodulated from the modulated wave signal, the cycle of the demodulated signal corresponding to the cycle of the modulating wave. - View Dependent Claims (2, 3, 4)
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5. A contactless power supply device that supplies power to a power reception device included in electric appliance using an electromagnetic induction phenomenon, the contactless power supply device comprising:
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an oscillation circuit that transmits an oscillation signal to the power reception device; a wave detection circuit that receives, from the power reception device receiving the oscillation signal, a modulated wave signal obtained by modulating the oscillation signal with a modulating wave based on a change in magnetic flux, detects the modulated wave signal, and demodulates the modulated wave signal detected by the power reception device; a frequency detection circuit that detects a frequency of the modulating wave demodulated by the wave detection circuit; and a determination circuit that determines whether or not a metal foreign object is present based on comparison between a reference cycle and the cycle corresponding to the frequency of the demodulated modulating wave detected by the frequency detection circuit, the cycle of the demodulated modulating wave corresponding to the cycle of the modulating wave. - View Dependent Claims (6, 7, 8)
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9. A contactless power supply system comprising a power reception device, which is included in an electric appliance, and a contactless power supply device, which supplies power to the power reception device using an electromagnetic induction phenomenon, wherein
the contactless power supply device includes an oscillation circuit that transmits, to the power reception device, an oscillation signal having a fixed frequency used to detect whether or not a metal foreign object is present, a wave detection circuit that receives, from the power reception device receiving the oscillation signal, a modulated wave signal obtained by modulating the oscillation signal with a modulating wave based on a change in magnetic flux, detects the modulated wave signal, and demodulates the modulated wave signal detected by the power reception device, a frequency detection circuit that detects a frequency of a demodulated modulating wave demodulated by the wave detection circuit, and a determination circuit that determines whether a metal foreign object is present based on comparison between a reference cycle and the cycle corresponding to the frequency of the demodulated modulating wave detected by the frequency detection circuit, the cycle of the demodulated modulating wave corresponding to the cycle of the modulating wave, and the power reception device includes an oscillation signal receiving circuit that receives the oscillation signal transmitted from the contactless power supply device, a modulating wave signal generation circuit that generates, from the oscillation signal received by the oscillation signal receiving circuit, the modulating wave, and a modulated wave signal generation circuit that generates a modulated wave signal by modulating a carrier signal in accordance with the modulating wave to transmit the modulating wave to the contactless power supply device.
Specification