PRESSURE SIGNAL PROCESSING

A method of processing signals from a touch panel for combined capacitive and force sensing includes receiving, from the touch panel, pressure signals from a plurality of piezoelectric sensors and capacitance signals from a plurality of capacitive touch sensors. The method also includes determining, based on the capacitance signals, a user interaction period during which a user interaction with the touch panel occurs. The method also includes generating processed pressure signals based on the received pressure signals. The method also includes measuring a force applied to each of the plurality of piezoelectric sensors by the user interaction during the user interaction period by conditionally integrating the corresponding processed pressure signals according to a state register corresponding to the user interaction. The state register takes one of two or more values. Each user interaction is initialised in a first state value. The user interaction transitions between state register values in dependence upon the current state register value, and one or more pressure signal properties.