Display guarding techniques

摘要

Embodiments described herein mitigate the effect of a coupling capacitance between a sensor electrode in a touch sensor and a display electrode in a display screen. An input device, which includes the touch sensor and display screen, may transmit a guarding signal on the display electrodes when performing capacitive sensing. In one embodiment, the guarding signal may have similar characteristics as a modulated signal (e.g., similar amplitude and/or phase) driven on the sensor electrode to detect interaction between the input device and an input object. By driving a guarding signal that is similar to the modulated signal onto the display electrodes, the voltage difference between the sensor electrode and display electrode remains the same. Accordingly, the coupling capacitance between the sensor electrode and the display electrode does not affect a capacitance measurement used to detect the user interaction.

主权项

1. An input device comprising:
a plurality of sensor electrodes each comprising at least one of a plurality of common electrodes of a display, wherein the plurality of common electrodes are configured for display updating and capacitive sensing; a plurality of display electrodes; and a processing system coupled to the plurality of sensor electrodes and the plurality of display electrodes, the processing system is configured to:
drive a modulated signal onto a first sensor electrode of the plurality of sensor electrodes to acquire a change of capacitance during a first period, andoperate a first display electrode of the plurality of display electrodes in a guard mode to mitigate an effect of a coupling capacitance between the first sensor electrode and the first display electrode during the first period, wherein mitigating the effect of the coupling capacitance comprises maintaining a constant voltage difference between the first sensor electrode and the first display electrode during the first period.