US 9,811,181 B2
Noise correction for a stylus touch device
Apexit Shah, Cupertino, CA (US); and Seyed M. Navidpour, Cupertino, CA (US)
Assigned to Apple Inc., Cupertino, CA (US)
Filed by Apple Inc., Cupertino, CA (US)
Filed on Feb. 24, 2016, as Appl. No. 15/52,435.
Prior Publication US 2017/0242499 A1, Aug. 24, 2017
Int. Cl. G06F 3/0354 (2013.01)
CPC G06F 3/03545 (2013.01) 20 Claims
OG exemplary drawing
 
1. A method for mitigating LCD circuitry noise in a stylus touch device, comprising:
storing a sign of a peak magnitude signal of a plurality of signals measured at a plurality of electrodes;
determining a set of core electrodes of the plurality of electrodes and a set of non-core electrodes of the plurality of electrodes;
for each core electrode of the plurality of electrodes, determining a noise estimate for the core electrode based on a corresponding core electrode mitigation set determined by a position of the core electrode;
for each non-core electrode of the plurality of electrodes, determining a noise estimate based on a corresponding non-core electrode mitigation set determined by a position of the non-core electrode;
determining a plurality of corrected signals, wherein for each core electrode and each non-core electrode a corresponding corrected signal of the plurality of corrected signals is determined based on the noise estimate and the signal measured at the electrode;
for each of the plurality of corrected signals, setting the corrected signal to zero if the sign of the corrected signal is not the same as the stored peak magnitude signal sign; and
determining a position of an active stylus based on the plurality of corrected signals.