Wireless charging system with object detection
First Claim
1. A wireless power transmitting device, comprising:
- a coil;
wireless power transmitting circuitry coupled to the coil and configured to transmit wireless power signals to a wireless power receiving device with a receiving coil in a wireless power receiving circuit that is configured to resonate at a wireless power receiving circuit resonant frequency;
control circuitry configured to control transmission of the wireless power signals;
an oscillator coupled to the coil that is configured to apply a probe signal to the coil at a probe frequency; and
an analog-to-digital converter configured to measure signals at the probe frequency, wherein the control circuitry is configured to;
in a standby mode, determine whether an external object is present by directing the oscillator to supply the probe signal to the coil in bursts separated by respective periods of time in which no probe signals are supplied to the coil by the oscillator, wherein the probe frequency of the probe signal is the same during each of the bursts, wherein the probe frequency is equal to 101% to 150% of the wireless power receiving circuit resonant frequency, wherein each burst has a first duration greater than 0.5 milliseconds, and wherein each period of time in which no probe signals are supplied to the coil by the oscillator has a second duration greater than 100 milliseconds.
1 Assignment
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Accused Products
Abstract
A wireless power transmitting device transmits wireless power signals to a wireless power receiving device. The wireless power receiving device has a wireless power receiving coil in a resonant circuit that resonates at a wireless power receiving circuit resonant frequency. The wireless power transmitting device has coils. The coils are supplied with a drive signal in bursts to detect external objects. Measurement circuitry includes an oscillator for supplying the drive signals and a peak detector and analog-to-digital converter for gathering measurements on the coils to which the drive signals have been supplied. Rate-based-filtering is applied to output signals from the analog-to-digital converter to distinguish between temperature drift effects and object placement effects. The frequency of the drive signals is slightly greater than the wireless power receiving circuit resonant frequency.
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Citations
20 Claims
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1. A wireless power transmitting device, comprising:
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a coil; wireless power transmitting circuitry coupled to the coil and configured to transmit wireless power signals to a wireless power receiving device with a receiving coil in a wireless power receiving circuit that is configured to resonate at a wireless power receiving circuit resonant frequency; control circuitry configured to control transmission of the wireless power signals; an oscillator coupled to the coil that is configured to apply a probe signal to the coil at a probe frequency; and an analog-to-digital converter configured to measure signals at the probe frequency, wherein the control circuitry is configured to; in a standby mode, determine whether an external object is present by directing the oscillator to supply the probe signal to the coil in bursts separated by respective periods of time in which no probe signals are supplied to the coil by the oscillator, wherein the probe frequency of the probe signal is the same during each of the bursts, wherein the probe frequency is equal to 101% to 150% of the wireless power receiving circuit resonant frequency, wherein each burst has a first duration greater than 0.5 milliseconds, and wherein each period of time in which no probe signals are supplied to the coil by the oscillator has a second duration greater than 100 milliseconds. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A wireless power transmitting device, comprising:
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a coil; wireless power transmitting circuitry coupled to the coil and configured to transmit wireless power signals to a wireless power receiving device with a receiving coil in a wireless power receiving circuit that is configured to resonate at a wireless power receiving circuit resonant frequency; control circuitry configured to control transmission of the wireless power signals; and measurement circuitry coupled to the coil that is used by the control circuitry to detect external objects, wherein the measurement circuitry includes an oscillator configured to apply a probe signal at a probe frequency that is larger than the wireless power receiving circuit resonant frequency and includes an analog-to-digital converter configured to measure signals at the probe frequency, wherein the probe frequency is equal to 101% to 150% of the wireless power receiving circuit resonant frequency, and wherein the control circuitry is configured to process output from the analog-to-digital converter to distinguish between temperature drift effects and object placement effects.
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10. A method of using a wireless power transmitting device having wireless power transmitting circuitry that transmits wireless power signals to a wireless power receiving device using a coil, wherein the wireless power receiving device has a wireless power receiving circuit with an associated wireless power receiving circuit resonant frequency, the method comprising:
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in a standby mode, monitoring the coil for presence of an external object by periodically supplying, with an oscillator, a probe signal to the coil at a probe frequency equal to 101% to 150% of the wireless power receiving circuit resonant frequency; in response to detecting the external object, obtaining measurements to determine whether the external object is the wireless power receiving device; and in response to determining that the external object is the wireless power receiving device, wirelessly transmitting power from the coil to the wireless power receiving device. - View Dependent Claims (11, 12, 13, 14, 15, 16, 17, 18, 19, 20)
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Specification