Capacitance scanning proximity detection

摘要

A method and apparatus for scanning a first set of electrodes of a capacitive sense array using a first sensing mode to identify a presence of an object in proximity to the capacitive sense array, where scanning using the first sensing mode identifies objects not in physical contact with the capacitive sense array. The first set of electrodes is scanned using a second sensing mode to determine a location of the object in relation to the capacitive sense array, where rescanning using the second sensing mode determines locations of objects in physical contact with the capacitive sense array.

主权项

1. A method for detecting an object on a capacitance sensing array, the method comprising:
in a first mode:
configuring a capacitance sensing circuit to measure self capacitance,measuring a first self capacitance of a first electrode,measuring a second self capacitance of a second electrode,detecting, based on at least one of the first self capacitance of the second self capacitance, the object being proximate to a surface intermediate to the object and the first and second electrodes;responsive to detecting, configuring the capacitance sensing circuit to measure mutual capacitance of at least the first electrode and the second electrode;transmitting a transmit (TX) signal on the first electrode;receiving a receive (RX) signal on the second electrode, the RX signal responsive to a mutual capacitance between the first and second electrode; andcalculating a position of the object proximate to, but not contacting, the substrate; and in a second mode:
configuring the capacitance sensing circuit to measure mutual capacitance;transmitting a transmit (TX) signal on the first electrode;receiving a receive (RX) signal on the second electrode, the RX signal responsive to a mutual capacitance between the first and second electrode; andcalculating a position of the object in physical contact with the substrate intermediate to the object and the first and second electrodes.