Texas Instruments Incorporated
Mutual-capacitance sensing with conductive overlay

Abstract:

A device includes an electrical circuit and a mutual-capacitance sensing circuit coupled to the electrical circuit. The mutual-capacitance sensing circuit includes mutual-capacitance sensing electrodes including a transmitter electrode and receiver electrode. The device also includes a conductive overlay over the mutual-capacitance sensing electrodes. The mutual-capacitance sensing circuit is configured to detect deflection of a portion of the conductive overlay relative to the mutual-capacitance sensing electrodes. The receiver electrode has a shape with an inner edge, and the transmitter electrode has a shape with an outer edge that is at least partially surrounded by the inner edge of the receiver electrode.