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Capacitive sensing

  • US 9,531,380 B2
  • Filed: 06/29/2012
  • Issued: 12/27/2016
  • Est. Priority Date: 03/02/2009
  • Status: Active Grant
First Claim
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1. A multi-channel capacitive sensor comprising:

  • a sample capacitor coupled to a first sense electrode and to a second sense electrode, the first sense electrode associated with a first sense capacitor and a first diode and the second sense electrode associated with a second sense capacitor and a second diode, the first sense capacitor being distinct from the second sense capacitor, the sample capacitor configured for use in measuring a capacitance of the first sense capacitor and in measuring a capacitance of the second sense capacitor; and

    a control circuit programmed to;

    apply, at a first time via a drive channel, a first drive signal to the sample capacitor;

    apply, while allowing the first drive signal received from the sample capacitor to be conducted by the first diode to the first sense electrode associated with the first sense capacitor, a first signal to the second sense capacitor to prevent the first drive signal from being conducted by the second diode to the second sense electrode associated with the second sense capacitor;

    apply, at a second time via the drive channel, a second drive signal to the sample capacitor of the multi-channel capacitive sensor; and

    apply, while allowing the second drive signal received from the sample capacitor to be conducted by the second diode to the second sense electrode associated with the second sense capacitor, a second signal to the first sense capacitor to prevent the second drive signal from being conducted by the first diode to the first sense electrode associated with the first sense capacitor.

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