Synaptics Incorporated
Compensating force baseline artifacts in a capacitive sensor

Abstract:

An example processing system for a capacitive input device includes sensor circuitry configured to drive a plurality of sensor electrodes with capacitive sensing signals over time to acquire capacitive values of a plurality of capacitive frames. The processing system includes a determination module configured to analyze a first capacitive frame of the plurality of capacitive frames to identify a force event by detecting that a rate of change of a first capacitive value in the first capacitive frame exceeds a first threshold. The determination module is configured to determine a change in capacitance between the first capacitive value and a baseline value, and analyze a second capacitive frame of the plurality of capacitive frames acquired after the force event to adjust the baseline value responsive to a difference between the baseline value and a second capacitive value in the second capacitive frame falling below a second threshold.