High noise immunity sensing methods and apparatus for a capacitive touch device

摘要

High noise immunity sensing methods and apparatus are provided for a capacitive touch device, which sense the capacitive touch device for self capacitance or mutual capacitance or both with different scan frequencies in a frame, to thereby suppress certain frequency noise interference. By combining time domain and space domain noise-eliminating approaches, probabilities of noise interference are reduced, without compromising other parameters.

主权项

1. A high noise immunity sensing method for a capacitive touch device, the improvement comprising steps of:
applying a first excitation signal to a first trace in the capacitive touch device with a first scan frequency and sampling a first sensed signal of the first trace to obtain a first self capacitance of the first trace in the capacitive touch device; and applying a second excitation signal to a second trace in the capacitive touch device with a second scan frequency and sampling a second sensed signal of the second trace to obtain a second self capacitance of the second trace in the capacitive touch device, wherein the second scan frequency is different from the first scan frequency.