CAPACITIVE SENSING APPARATUS AND METHODS

摘要

A capacitive sensor comprising: a first electrode; a displacement element moveably mounted relative to the first electrode; and a second electrode coupled to the displacement element so that displacement of the displacement element along a displacement direction changes a separation between the first electrode and the second electrode; and a controller element configured to selectively operate in a displacement sensing mode and in a proximity sensing mode, wherein in the displacement sensing mode, the controller element is configured to electrically couple the second electrode to a reference potential and to electrically couple the first electrode to capacitance measurement circuity to measure a capacitance characteristic of the first electrode to determine a displacement of the displacement element relative to the reference electrode; and in the proximity sensing mode, the controller element is configured to electrically couple the second electrode to capacitance measurement circuity to measure a capacitance characteristic associated with the second electrode to detect the presence of an object in proximity to the second electrode; and in the displacement sensing mode, the controller element is configured to electrically couple the second electrode to a reference potential signal.