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Touch panel coordinate determination

  • US 6,646,634 B2
  • Filed: 01/31/2001
  • Issued: 11/11/2003
  • Est. Priority Date: 01/31/2001
  • Status: Expired due to Fees
First Claim
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1. A method for determining coordinates of a contact point on a touch screen that comprises first and second input layers, spaced apart by a selected small distance, each layer containing a sequence of resistive lines that extend between an input layer voltage source and a no-current-flow point, the method comprising:

  • providing a first selected voltage source, connected across a resistive line in the first input layer to an electrical contact point, common to the first input layer and the second input layer;

    providing a second selected voltage source, connected in series across a selected resistance and a resistive line in the second input layer to the contact point;

    measuring a current value for at least one resistive line that passes through the contact point;

    measuring a voltage value at the contact point;

    calculating a resistance of a resistive line that extends from the contact point to the first voltage source; and

    calculating a resistance of a resistive line that extends from the contact point to the second voltage source.

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