Correction of parasitic capacitance effect in touch sensor panels

摘要

Compensation of pixels included in a touch sensor panel that generate erroneous readings (so called “negative pixels”) due to a poor grounding condition of the object touching the touch sensor panel is disclosed herein. To compensate for the erroneous readings, sense lines of the touch sensor panel can include reverse driving circuits to facilitate calculation of an object-to-ground capacitance. If the calculated object-to-ground capacitance indicates the presence of a poor grounding condition, then the object-to-ground capacitance and detected pixel touch output values are used to estimate new pixel touch output values that are used instead of the detected pixel touch output values to determine touch event(s).

主权项

1. A method for compensating for negative pixel effects on a touch sensor panel, comprising:
estimating an object-to-ground capacitance of an object in contact with the touch sensor panel, wherein the estimation is made by simultaneously stimulating a plurality of drive lines to obtain a first measurement and simultaneously stimulating a plurality of sense lines to obtain a second measurement; and determining an effective pixel touch output value for each pixel of the touch sensor panel based on the estimated object-to-ground capacitance and measured pixel touch output values when the estimated object-to-ground capacitance is at or below a predetermined threshold.