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Systems and methods for assessing locations of multiple touch inputs

  • US 8,493,355 B2
  • Filed: 05/13/2009
  • Issued: 07/23/2013
  • Est. Priority Date: 05/14/2008
  • Status: Active Grant
First Claim
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1. For use in a matrix capacitive touch screen system that includes a sensor having a plurality of x-electrodes for providing x-signals based on capacitance-to-ground measurements and indicative of x-coordinates of touch inputs, and a plurality of y-electrodes for providing y-signals based on capacitance-to-ground measurements and indicative of y-coordinates of touch inputs, a method for assessing touch locations of two or more temporally overlapping touch inputs, the method comprising:

  • responsive to capacitance-to-ground x-signals, determining valid x-coordinates of the two or more temporally overlapping touch inputs;

    responsive to capacitance-to-ground y-signals, determining valid y-coordinates of the two or more temporally overlapping touch inputs;

    assessing the capacitance-to-ground x-signals and the capacitance-to-ground y-signals as a function of a timing sequence associated with at least one of the touch inputs;

    in response to the steps of determining and of assessing, forming valid x-y pairs, the valid x-y pairs being indicative of the touch locations and the remaining touch inputs being unresolved;

    in response to forming the valid x-y pairs, forming additional valid x-y pairs for one or more of the remaining unresolved touch inputs, as additional valid x-y pairs are formed, they are determined as pertaining to a valid touch which can then be discriminated as corresponding to a real touch, as opposed to a phantom touch; and

    discriminating each valid x-y pair as corresponding to a real touch as opposed to a phantom touch, even as the touch is moved across the touch surface.

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