Interference estimation and adaptive reconfiguration of a capacitive touch controller

摘要

Adaptive reconfiguration of a capacitive touch controller is implemented by estimating the interference spectrum of the signal received by the touch controller. The spectrum of the received signal is used to determine a desired frequency, and the touch panel transmitter is configured to use that desired frequency. The spectrum of the received signal is also used to determine an desired filter transfer function. A filter in the touch panel received signal path is configured to use that desired filter transfer function. The adaptive reconfiguration is focused on improving the signal to noise ratio of the received signal without the need for shielding the touch panel, performing additional scans of the touch panel, or using components that operate at higher power levels.

主权项

1. A method for reconfiguring a capacitive touch controller, the method comprising:
detecting a triggering event for reconfiguring the capacitive touch controller; measuring a received signal from a capacitive touch panel; determining an auto-correlation of the received signal; determining a filter transfer function for rejecting interference from a subsequently received signal, where the filter transfer function is based on the auto-correlation of the received signal; determining a transmit frequency for stimulating the capacitive touch panel, where the transmit frequency is based on the auto-correlation of the received signal, including determining an optimal transmit frequency from a range of available frequencies, where each available frequency has a mean square error (MSE), where the MSE is determined by the inner product of the auto-correlation of the received signal and auto-correlation of the filter transfer function, and where the optimal transmit frequency is the available frequency having the minimum MSE; stimulating the capacitive touch panel using the transmit frequency by applying to the capacitive touch panel a time varying signal having the transmit frequency, and subsequently receiving a signal from the capacitive touch panel, the subsequently received signal being indicative of a response of the capacitive touch panel to the time varying signal; and filtering a subsequently received signal using the filter transfer function.