Synaptics Incorporated
Low power baseline tracking for fingerprint sensor

Abstract:

Low power consumption baseline tracking systems and methods for automatically tracking a baseline input into a capacitive sensor having a plurality of transmitter electrodes and a plurality of receiver electrodes. A partial baseline scan is captured by driving all or a portion of the plurality of transmitter electrodes simultaneously and detecting receiver signals from a subset of the at least one receiver electrode simultaneously, and the partial baseline scan is compared with a stored baseline image. When a difference between the captured partial baseline scan and the stored baseline image exceeds a threshold value, a full baseline image scan is acquired, and the stored baseline image is updated.