Noise reduction in capacitive touch sensors

摘要

In touch sensitive display devices, the display scanning circuitry responsible for driving images of the panel screen can cause noise on the electrodes of nearby touch sensors. The display controller circuit and/or the touch sensor controller circuit of the exemplary touchscreen display devices may be configured to reduce such noise during the touch sensor acquisition cycle by implementing one or more of several techniques in which a portion of each of the sensor acquisition cycles occurs within a period of reduced noise from a cycle of the scanning of the display.

主权项

1. A touch sensing display device, comprising:
a display; a display controller circuit including display scanning circuitry and a controller arranged to control a duty cycle of scanning of the display; a capacitive touch sensor comprising at least one electrode in proximity to the display; and a touch sensor controller circuit arranged to control a sensor acquisition duty cycle with respect to a signal from the capacitive touch sensor, wherein at least one of the controller circuits is configured such that a portion of the sensor acquisition duty cycle occurs within a period of reduced noise from the duty cycle of the scanning of the display; wherein the touch sensor controller circuit is configured to: monitor, during the duty cycle of scanning of the display, noise on the capacitive touch sensor; initiate, in response to detecting an absence of noise from the display, the sensor acquisition duty cycle; and communicate, in response to completion of the sensor acquisition duty cycle, an acquisition complete signal to the display controller circuit to cause the display controller circuit to initiate another duty cycle of the scanning of the display.