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Method and apparatus for detecting a change in capacitance of a capacitive proximity sensor

  • US 20030071639A1
  • Filed: 05/10/2002
  • Published: 04/17/2003
  • Est. Priority Date: 10/17/2001
  • Status: Active Grant
First Claim
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1. A method for detecting a change in capacitance of a capacitive sensing element having a nominal capacitance value, the method comprising:

  • coupling the sensing element to a first oscillator, said first oscillator generating a first frequency dependent upon the capacitance value of the sensing element; and

    comparing said first frequency to a reference frequency, said reference frequency being a second frequency generated by a second oscillator;

    wherein the change in capacitance from the nominal capacitance value is detected if said first frequency differs from said reference frequency by a determined frequency value.

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