Apparatus and method for digitally driving touchscreen panels with transmit signals based on pulse width modulated (pwm) signals

Abstract

A touchscreen display including a touchscreen panel with a set of spaced-apart electrically-conductive transmit lines and a set of spaced-apart electrically-conductive receive lines extending in orthogonal directions. A set of class-D transmit drivers generate transmit signals applied to the transmit lines based on a driving pulse-width-modulated (PWM) signals, respectively. The PWM signals control the amplitude, phase, and slew rate of the pulses of the transmit signals, respectively. The parameters of the pulses are controlled so that the transmit signals arrive with substantially the same amplitude, phase, and slew rate at each receiver regardless of which transmit driver generated the transmit signal. This allows a single anti-phase signal at each receiver to substantially cancel out the receive signal during no panel load.

Dependencies are inferred from the claim text.