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Sensor and sensing method utilizing symmetrical differential readout

  • US 8,056,413 B2
  • Filed: 09/11/2008
  • Issued: 11/15/2011
  • Est. Priority Date: 09/11/2007
  • Status: Active Grant
First Claim
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1. A sensor adapted to achieve differential symmetry at an output thereof, the sensor comprising:

  • a sensing element that responds with motion to an environmental input;

    a plurality of sense electrodes capacitively coupled to the sensing element to generate a corresponding plurality of capacitive outputs that vary in response to motion of the sensing element, the sense electrodes being electrically separable into at least two pairs of differential sense electrodes, the differential sense electrodes of each pair detecting motion of the sensing element at different locations of the sensing element;

    differential readout means for performing a sampling sequence comprising at least two sampling cycles during which the differential readout means samples the capacitive outputs of the sense electrodes and produces at least two differential outputs based on the difference between the capacitive outputs within each pair of the differential sense electrodes, calculating an average of the at least two differential outputs of the sampling sequence to produce an output of the differential readout means, and then repeating the sampling sequence and calculation; and

    means for connecting different pairs of the differential sense electrodes at a sampling rate and at instances to achieve dynamically generated symmetry at the output of the differential readout means.

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