Multi-stage stylus scanning

摘要

A system comprises a processing device and a capacitive sense array that includes a plurality of electrodes. The system performs a first scan of a plurality of electrodes in a capacitive sense array to determine a position of a stylus. The system also performs one or more additional scans of subsets of the plurality of electrodes to determine additional positions of the stylus. The system may continually perform the additional scans on of the subsets of the plurality of electrodes until the stylus is no longer detected.

主权项

1. An apparatus comprising:
a capacitive sense array comprising a plurality of rows and columns of electrodes, wherein the capacitive sense array is configured to detect a presence of a passive touch object and a stylus; and a processing device coupled to the capacitive sense array, the processing device configured to:
perform an initial scan of the plurality of rows and columns of electrodes to determine an initial position of the stylus;in response to determining the initial position of the stylus:
select subsets of the plurality of rows and columns of electrodes having increased capacitance signal strength around the initial position of the stylus;perform one or more additional scans of the selected subsets to determine additional positions of the stylus; andafter performing the initial scan and the one or more additional scans:
determine a trajectory of the stylus based on the initial position and the one or more additional positions of the stylus; andselect respective subsets of the plurality of electrodes for subsequent scans based on the determined trajectory of the stylus in combination with capacitance signal strengths received during the initial scan and the one or more additional scans.