Synaptics Incorporated
Fast finger settlement detection for fingerprint sensors

Abstract:

Low power input object settlement detection systems and methods for operating a capacitive sensor having a plurality, M, of transmitter electrodes and a plurality, N, of receiver electrodes, wherein N and M are integer values. A plurality of input object settlement scans are captured, when a presence of an input object is detected, or in response to a presence of an input object being detected, wherein capturing each input object settlement scan includes driving all or a portion of the plurality, M, of transmitter electrodes simultaneously and detecting receiver signals from at least a subset of the plurality, N, of receiver electrodes simultaneously. When a difference between subsequent input object settlement scans is below a threshold value, a full input object image is acquired.