Differential touch sensor and control circuit therefor

  • US 6,310,611 B1
  • Filed: 12/08/1997
  • Issued: 10/30/2001
  • Est. Priority Date: 12/10/1996
  • Status: Expired due to Term
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First Claim
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1. A sensor apparatus for generating a control signal on a sense line, said apparatus comprising:

  • at least one first electrode;

    at least one second electrode positioned in proximity to said first electrode;

    a differential measuring circuit in close proximity to said first and second electrodes, said differential measuring circuit having first and second input nodes connected to said first and second electrodes, respectively, and an output node connected to the sense line;

    a signal source for providing electrical signals to said first and second electrodes;

    wherein an electric field is generated between said first and said second electrodes in response to the signals provided to at least one of said first and second electrodes by said signal source;

    wherein said first and second electrodes are arranged such that the electric field is affected by the presence of a stimulus in proximity to at least one of said first and second electrodes;

    wherein said differential measuring circuit generates a control signal on the sense line related to the difference in electrical potential between said first and second electrodes related to the electric field; and

    wherein the output voltage of the control signal produced by the differential measuring circuit on the sense line rises to a maximum only when a stimulus is applied to the electric field affecting the first electrode and a lesser stimulus is applied to the electric field affecting the second electrode.

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