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Periodic sensor autocalibration and emulation by varying stimulus level

  • US 20080309622A1
  • Filed: 06/13/2007
  • Published: 12/18/2008
  • Est. Priority Date: 06/13/2007
  • Status: Active Grant
First Claim
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1. A method for calibrating a mutual capacitance touch sensor, comprising:

  • during pre-delivery calibration, determining a no-touch to full-touch full-scale output value range FS_targ_cal from an analog channel coupled to the sensor, and determining a sensor stimulus voltage amplitude value Vstim_cal at which the full-scale output value of the analog channel is approximately equivalent to FS_targ_cal; and

    during field calibration, applying Vstim_cal to the sensor and obtaining a full-scale output value range FS_targ_current from the analog channel, and tuning the analog channel in accordance with any difference between FS_targ_current and FS_targ_cal.

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