Patent ID: 8314779

Claim:
A controller for detection of touches by a single finger or multiple fingers on a touch panel, the touch panel including a first group of electrodes arranged in a first direction and a second group of electrodes arranged in a second direction, thereby forming a plurality of crossover points, the controller comprising: a plurality of signal drivers coupled to the first group of electrodes and configured to excite the first group of electrodes sequentially using a spread spectrum driving signal provided by an analog waveform generator using no code division multiplexing; a plurality of signal sensors coupled to the second group of electrodes and configured to detect peaks and troughs of capacitive coupled signals at the second group of electrodes, the detecting being performed simultaneously for the crossover points along a current one of the first group of electrodes that is being excited; and a signal processing device comprising an analog to digital converter (ADC) to convert analog signals from the signal sensors into digital data and a digital signal processing (DSP) unit configured to compensate the digital data, and to detect the touches, calculate touch positions, and generate touch images based on the compensated digital data, wherein the DSP unit comprises: an image segmentation component configured to divide into groups ones of the plurality of crossover points at which the capacitive coupled signals have variations, each of the groups corresponding to an approximated finger touch image, thereby to generate a plurality of approximated finger touch images; a finger windowing component configured to reshape the approximated finger touch images to generate reshaped finger touch images; and a center of mass calculation component configured to determine the touch positions by determining a center of mass for each of the reshaped finger touch images.