Apple Inc.
BALANCED MUTUAL CAPACITANCE SYSTEMS AND METHODS

Abstract:

In some examples, a touch screen can include touch electrodes that can function as drive (Tx) electrodes and sense (Rx) electrodes during a touch sensing operation of the electronic device. The drive electrodes can include +Tx electrodes and -Tx electrodes that can receive drive signals that can have the same amplitude and frequency and opposite phases, for example. In some examples, the surface areas of the +Tx electrodes and the -Tx electrodes can be the same and the distances of the +Tx electrodes and -Tx electrodes from the Rx electrodes can be different. In some examples, the total charge coupled to a proximate or touching object can be zero, which can mitigate problems associated with ungrounded or poorly grounded objects in contact with the touch screen.