MODULATING A REFERENCE VOLTAGE TO PERFORM CAPACITIVE SENSING

摘要

This disclosure generally provides an input device that includes a reference voltage modulator that modulates reference voltage rails when performing capacitive sensing. In one embodiment, reference voltage rails are coupled to a DC power source which provides power to operate a panel that includes a display screen integrated with a touch sensing region. Before performing capacitive sensing, the input device may isolate the DC power source from the reference voltage rails and use the reference voltage rails to modulate the rails—e.g., VDD and VGND. The input device may include a receiver that simultaneously acquires resulting signals from a plurality of display and/or sensor electrodes when modulating the reference voltage rails. The resulting signals can then be processed to determine if an input object is interacting with the input device.

主权项

1. An input device, comprising:
a plurality of display electrodes; a plurality of sensor electrodes; and a processing system, comprising:
a reference voltage modulator configured to modulate the reference voltage rails during a first time period, wherein the processing system is configured to:update a display using the display electrodes and the reference voltage rails of the processing system during a second time period that is non-overlapping with the first time period, wherein the reference voltage rails are held at unmodulated, constant voltages during the first time period, andacquire resulting signals from the plurality of sensor electrodes during the first time period.