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CAPACITIVE SENSOR CONFIGURED FOR USING HEATING ELEMENT AS ANTENNA ELECTRODE

  • US 20150345998A1
  • Filed: 12/19/2013
  • Published: 12/03/2015
  • Est. Priority Date: 12/19/2012
  • Status: Active Grant
First Claim
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1. A capacitive sensor, configured for being connected between a heating element and a heating current supply and for using said heating element as antenna electrode, comprisinga common mode choke having first and second inductively coupled windings, said first winding for being connected between a first terminal of said heating current supply and a first terminal of said heating element and said second winding for being connected between a second terminal of said heating element and a second terminal of said heating current supply;

  • said common mode choke further comprising a third winding inductively coupled with said first and second windings, anda control and evaluation circuit configured to inject an AC signal into said heating element via a measurement node, to measure a voltage on and/or a current across said measurement node, and to derive an impedance between said heating element and a counter electrode from said measured voltage and/or current, andwherein said measurement node is operatively coupled to said third winding for inductively injecting said AC signal into said heating element.

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