TOUCH PANEL SYSTEM USING MODULATED SIGNALS AS DRIVE SIGNALS

A touch panel includes a first plurality of electrodes and a second plurality of electrodes. A plurality of transmitters generate a plurality of transmit signals by modulating a common sine wave signal with a set of orthogonal modulation signals, and drive each transmit signal onto a corresponding electrode of the first plurality of electrodes. Each transmit signal is generated by modulating the common sine wave signal with a unique orthogonal modulation signal of the set of orthogonal modulation signals. At least two of the plurality of transmit signals are not orthogonal. Each receiver of a plurality of receivers senses a receive signal on a corresponding electrode of the second plurality of electrodes and generates a set of correlation signals by correlating the receive signal with each transmit signal of the plurality of transmit signals. The sets of correlation signals are used to detect a touch event on the touch panel.