Patent ID: 10505564

Abstract:
Touch/key sensing with N-1 key scan averaging, for use with an N-key touch input apparatus, including a key matrix of N touch-key sense circuits, including: (a) continuously scanning the key matrix at a first bandwidth to determine a respective touch-key baseline sense signal, independent of a key-press condition, and a related touch-key baseline value based on successive baseline sense signals; and (b) during successive key-scan periods, scanning the key matrix at a second bandwidth greater than the first bandwidth, and for each touch key N, determining a touch-key sense signal, generating an N-1 key-scan average value by averaging the touch-key baseline values for the other N-1 touch keys, comparing the Nth touch-key sense signal to a key-press threshold based on the N-1 key-scan average value; and (c) signaling a key-press condition if the touch-key sense signal is greater in magnitude than the N-1 key-scan average value by the key-press threshold.