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Pulsed antenna capacitive touch switch

  • US 8,203,466 B2
  • Filed: 04/18/2008
  • Issued: 06/19/2012
  • Est. Priority Date: 04/20/2007
  • Status: Active Grant
First Claim
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1. A capacitive touch switch comprising:

  • an electrically insulating touch surface providing touch area for activation of the touch switch;

    a sense electrode positioned behind the touch surface at the touch area;

    an antenna electrode positioned behind the touch surface proximate to the sense electrode;

    a reference electrode positioned behind the touch surface proximate to the antenna electrode but removed from the touch area relative to the sense electrode;

    a detector circuit monitoring the capacitive coupling between the antenna electrode and each of the sense electrode and reference electrode to provide a switch output based on a comparison of the capacitive coupling between the antenna electrode and the sense electrode compared to a threshold that is a function of the capacitive coupling between the antenna electrode and the reference electrode;

    whereby effects of capacitive coupling to surface contamination on the touch surface may be minimized.

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