Patent ID: 8890849

Claim:
A method of enabling touch determination based on an output signal from a touch-sensitive apparatus, the touch-sensitive apparatus comprising a panel configured to conduct signals from a plurality of incoupling points to a plurality of outcoupling points, thereby defining detection lines that extend across a surface portion of the panel between pairs of incoupling and outcoupling points, at least one signal generator coupled to the incoupling points to generate the signals, and at least one signal detector coupled to the outcoupling points to generate the output signal which represents a time-sequence of signal values for the detection lines, wherein the method comprises the steps of in each iteration of a sequence of iterations: obtaining, based on the output signal, a current signal value for each detection line; retrieving a current reference value for each detection line, the current reference value being representative of the current signal value obtained in a preceding iteration in the sequence of iterations; calculating a change value for each detection line as a function of the current signal value and the current reference value; operating a reconstruction algorithm on the change values to determine a differential interaction pattern on the surface portion; updating a tracking pattern as a function of the differential interaction pattern; generating a current accumulated touch interaction pattern as a function of the tracking pattern; and providing the current accumulated touch interaction pattern for identification of touches on the surface portion.