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Power transmission device and wireless power transmission system

  • US 9,866,040 B2
  • Filed: 11/18/2015
  • Issued: 01/09/2018
  • Est. Priority Date: 09/12/2013
  • Status: Active Grant
First Claim
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1. A power transmission device for transmitting power via electric field coupling to a power reception device having a pair of power reception electrodes, the power transmission device comprising:

  • first and second power transmission electrodes that respectively oppose the pair of power reception electrodes with a gap therebetween, when the power reception device is positioned adjacent to the power transmission device;

    a voltage detection circuit configured to monitor a voltage of one of the first and second power transmission electrode; and

    a control circuit configured to determine an absolute value of a change per a time interval in the monitored voltage and to stop power transmission to the power reception device when the absolute value exceeds a predetermined threshold,wherein the control circuit determines the absolute value by;

    detecting an initial voltage of the one of the first and second power transmission;

    detecting a subsequent voltage of the one of the first and second power transmission electrode after the time interval; and

    determining the absolute value by calculating a difference between the initial voltage and the subsequent voltage.

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