US 11,693,504 B2
Force signal processing
Riccardo Micci, Cambridge (GB); and Arokia Nathan, Cambridge (GB)
Assigned to Cambridge Touch Technologies Ltd., Cambridge (GB)
Filed by Cambridge Touch Technologies Ltd., Cambridge (GB)
Filed on Dec. 27, 2021, as Appl. No. 17/562,261.
Application 17/562,261 is a continuation of application No. 16/909,248, filed on Jun. 23, 2020, granted, now 11,249,575.
Claims priority of application No. 1909827 (GB), filed on Jul. 9, 2019.
Prior Publication US 2022/0164056 A1, May 26, 2022
Int. Cl. G06F 3/041 (2006.01); G06F 3/044 (2006.01)
CPC G06F 3/0414 (2013.01) [G06F 3/0418 (2013.01); G06F 3/044 (2013.01)] 20 Claims
OG exemplary drawing
 
1. A method of processing signals from a touch panel which comprises a layer of piezoelectric material arranged between a plurality of first electrodes and at least one second electrode, the method comprising:
receiving one or more piezoelectric signals from the first electrodes, and correcting each piezoelectric signal to remove a first DC offset;
integrating the one or more corrected piezoelectric signals to determine respective force values;
maintaining a buffer storing buffer values, the buffer values corresponding to a preceding period;
determining whether one or more user interactions are occurring based on a gradient and a variance calculated for the buffer values; and
in response to determining that no user interactions are occurring, updating a second DC offset value; and
calculating corrected force values based on the force values and the second DC offset value.