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Hadamard matrix based projected mutual capacitance touch panel decoding

  • US 8,982,091 B1
  • Filed: 05/24/2012
  • Issued: 03/17/2015
  • Est. Priority Date: 05/24/2012
  • Status: Active Grant
First Claim
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1. A method of decoding a touch upon a touch panel, by a touch panel decoding circuit coupled to the touch panel, the touch panel comprising M drive channels and N sense channels, the method comprising a scan of the touch panel, a scan comprising the steps, for each column Ci of an excitation matrix E, and i=1 to N:

  • a. generating a product of Ci and a cover code, the cover code comprising a matrix, CC, having M rows and N columns, where generating the product of Ci and the cover code comprises generating the product of Ci and the ith column, CCi, of the cover code matrix, and where coefficients of the cover code comprise at least one of real-values, complex values, or a value that is one of −

    1, +1, and 0;

    b. driving the M drive channels with M drive signals generated by the product of Ci and the cover code; and

    c. receiving and demodulating the N sense channels to form an M×

    N matrix of touch panel decoding data, wherein the demodulating is performed using the inverse matrix, E

    1
    , of the excitation matrix, E.

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