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Self-calibrating variable pressure touch key system employing transducers subject to parameter drift

  • US 5,345,807 A
  • Filed: 06/08/1993
  • Issued: 09/13/1994
  • Est. Priority Date: 10/01/1991
  • Status: Expired due to Fees
First Claim
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1. A variable pressure touch key system comprising:

  • a pressure transducer device for producing an output signal having a value dependent on touch pressure applied to said transducer device;

    means for periodically reading the output signal value to establish a calibration reference value; and

    means for periodically reading the output signal value and comparing the output signal value to a plurality of comparison values respectively determined by applying each of a plurality of predetermined change threshold values to the calibration reference value to recognize a particular one of a plurality of potential operation values depending on the amount of touch pressure applied to said pressure transducer device.

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