Systems and Methods of Detecting a Change in Object Presence in a Magnetic Field
First Claim
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1. A system comprising:
- a primary coil driven by an injected signal at a substantially constant frequency to create a magnetic field and configured to receive a response during a driving phase of the injected signal; and
a controller configured to monitor a response to the injected signal and to determine a change in a presence of an object in the magnetic field emitted from the primary coil, the determination based on the monitored response.
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Abstract
The systems and methods of detecting a change in object presence in a magnetic field disclosed herein inject a low amplitude signal near the resonant frequency into the coil until the system comes to equilibrium. At this point the feedback is measured. The feedback signal can be measured as at least one of several signals, for example, but not limited to the voltage on the resonant capacitor, the current in the coil, and the voltage between the resonant capacitor and the coil. A change in the steady state response indicates a change in device presence.
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Citations
20 Claims
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1. A system comprising:
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a primary coil driven by an injected signal at a substantially constant frequency to create a magnetic field and configured to receive a response during a driving phase of the injected signal; and a controller configured to monitor a response to the injected signal and to determine a change in a presence of an object in the magnetic field emitted from the primary coil, the determination based on the monitored response. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A method of determining change in object presence in a magnetic field comprising:
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driving a primary coil with an injected signal at a substantially constant frequency to create a magnetic field; receiving a response during a driving phase of the injected signal; monitoring the response; and determining a change in object presence in the magnetic field emitted from the primary coil based on the monitored response. - View Dependent Claims (10, 11, 12, 13, 14, 15)
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16. A wireless charging system comprising:
a charger comprising; a power control circuit; a primary coil driven by an injected signal from the power control circuit at a substantially constant frequency to create a magnetic field and configured to receive a response during a driving phase of the injected signal; and a controller configured to monitor a response to the injected signal and to determine a change in presence of an object in the magnetic field emitted from the primary coil, the determination based on the monitored response. - View Dependent Claims (17, 18, 19, 20)
Specification