Pressure sensing apparatus and method

Abstract

An apparatus (73) for processing signals from a touch panel (10) is described. The touch panel (10) includes a layer of piezoelectric material (16) disposed between a number of sensing electrodes (14, 20) and one or more common electrodes (105). The apparatus (73) includes a capacitive touch controller (69) for connection to the sensing electrodes (14, 20). The apparatus (73) also includes a switch network (74) including a number of inputs for connection to some or all of the sensing electrodes (14, 20), and an output connected to system ground or a common mode voltage (VCM). The apparatus (73) also includes a second circuit (24, 44) for connection to the one or more common electrodes (105) and configured to generate, for each common electrode, a corresponding a second pressure signal (30) indicative of a pressure applied to the touch panel (10) proximate to that common electrode (105). The apparatus (73) also includes a controller (25) configured to control the switch network (74) to couple any connected sensing electrodes (14, 20) to system ground or the common mode voltage (VCM) during a pressure measurement period, and to sample the one or more second pressure signals during the pressure measurement period.

Dependencies are inferred from the claim text.