CAPACITANCE-BASED PROXIMITY SENSORS WITH INTERFERENCE REJECTION APPARATUS AND METHODS

摘要

Apparatus and method for a capacitance-based proximity sensor with interference rejection. A pair of electrode arrays (90) establishes a capacitance on a touch detection pad (12), the capacitance varying with movement of a conductive object near the pad (12). The capacitance variations are measured synchronously with a reference frequency signal to thus provide a measure of the position of the object. Electrical interference is rejected by producing a reference frequency signal which is not coherent whith the interference.