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Detection apparatus for a capacitive proximity sensor

  • US 7,616,011 B2
  • Filed: 04/05/2007
  • Issued: 11/10/2009
  • Est. Priority Date: 04/05/2007
  • Status: Active Grant
First Claim
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1. A capacitance detection apparatus for a capacitive proximity sensor having at least one sensing element, comprising:

  • a switching means for alternately charging and discharging said sensing element;

    an operational amplifier responsive to a detection voltage developed during the charging of said sensing element for developing an output voltage that varies in relation to a capacitance of said sensing element;

    a detection means responsive to said output voltage for detecting the capacitance of said sensing element; and

    a timing signal generator for developing timing signals for timing the alternate charging and discharging of said sensing element, where said detection means controls a frequency of the timing signals produced by said timing signal generator so that the detected capacitance is substantially insensitive to capacitive effects due to moisture on said sensor.

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