Adaptive high dynamic range surface capacitive touchscreen controller

摘要

A system for controlling a touch screen. A touch screen element having a plurality of contacts, such as one contact electrode at each of four corners. A multiplexer coupled to the touch screen element for forming a plurality of connections, such as various combinations of the contact electrodes to allow measurements to be made of the impedance of the touch screen element from the left side to the right side, from the top to the bottom, and do forth. A touch screen processor coupled to the touch screen element for determining an oscillation frequency of the touch screen element as a function of the electrode connections.

主权项

1. A system for controlling a touch screen comprising: a touch screen element having a plurality of contacts;
a multiplexer coupled to the touch screen element for forming a plurality of connections; and a touch screen processor coupled to the touch screen element and configured to determine an oscillation frequency of the touch screen element, the touch screen processor further comprising:
a difference amplifier configured to receive a touch screen element input signal and a touch screen element output signal and to generating a difference signal;an integrator configured to receive a difference signal input and to generate an integrated difference signal output;a reset pulse generator coupled to the integrator and configured to reset the integrator;an integrator hold coupled to the integrator and configured to compensate the integrator noise signal; anda second integrator configured to receive the output of the integrator and to generating an input to a reset pulse generator.