Capacitive sensor systems and methods with increased resolution and automatic calibration

  • US 6,661,239 B1
  • Filed: 01/02/2002
  • Issued: 12/09/2003
  • Est. Priority Date: 01/02/2001
  • Status: Active Grant
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First Claim
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1. A capacitive sensing system comprising:

  • a microcontroller, operable to receive electrical power from an electrical power source, and having at least one digital logic input/output (I/O) port;

    a conductive sense element in electrical communication with the port; and

    a resistance element in electrical communication with the sense element to form an electrical pathway from the sense element to an electrical discharge point;

    wherein the microcontroller is further operable to;

    at a first time, charge the sense element by causing a selected voltage to be place on the port;

    at a second time, cease placing the selected voltage on the port;

    thereafter, measure voltage at the port, the voltage at the port being representative of voltage at the sense element; and

    measure a parametric value required for voltage at the sense element to decline to a value below a threshold value, the parametric value being representative of an effective capacitance formed by at least the sense element and a first object that may be in contact or proximity with the sense element, whereby the parametric value is representative of contact or proximity between the sense element and the first object; and

    wherein the microcontroller is further operable to perform digital signal processing on signals derived from the sense element, such signal processing including pattern recognition comprising the synthesis of at least one virtual sensor capable of detecting selected patterns of contact or proximity between the first object and the sense element; and

    wherein the selected patterns of contact or proximity include any of activity, hold, squeeze, tickle, pet, slap, rhythm or bounce patterns; and

    wherein the capacitive sensing system is adapted for embedding in a second object.

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