SENSING FRAME AVERAGING FOR CANCELLING DISPLAY NOISE IN SIMULTANEOUS DISPLAY AND TOUCH SENSING

摘要

Techniques for removing display-based corrupting components from a capacitive sensing signal when display and capacitive sensing is performed at or nearly at the same time. A routing carrying display related signals (e.g., a source signal for sub-pixel updating) may induce a corrupting current into a routing for carrying capacitive sensing signals. This corrupting current would reduce the ability to determine presence of an input object via the sensing signal. Therefore, the corrupting signal is effectively removed by averaging sensing signals from two consecutive frames together. Because displays perform frame inversion, in which the voltage polarity provided to a sub-pixel for updates is reversed each frame, the corrupting current reverses in polarity each frame. Therefore, adding two subsequent frames together cancels out the corrupting signal.

主权项

1. A processing system configured for simultaneously updating a display and performing capacitive sensing, the processing system comprising:
a source driver configured to drive a source line with a first source driver voltage during a first time period and to receive resulting signals on a routing trace coupled to a sensor electrode during a second time period that at least partially overlaps with the first time period, the routing trace and the source line being routed proximate each other; and an interference remover configured to acquire first resulting signals during a first display update period and second resulting signals during a second display update period, and to remove display interference from the second resulting signals by combining the first resulting signals and the second resulting signals, wherein first display signals provided for display updates during the first display update period are frame-inverted with respect to second display signals provided for display updates during the second display update period.