Baseline recalculation after frequency reconfiguration of a mutual capacitive touch controller

摘要

Systems and methods are provided that allow a touch sensor, such as a mutual capacitive touch panel, to switch from an operative transmit (TX) frequency at which the mutual capacitive touch panel is driven to an alternative TX frequency. When switching to an alternative TX frequency, an alternative baseline capacitance value corresponding to the alternative TX frequency may be utilized to determine whether a touch event has occurred on the mutual capacitive touch panel. Frame scans can be repeatedly performed at the operative TX frequency and the alternative TX frequency in rapid succession, and an average difference of the frame scans can be calculated and utilized to generate the alternative baseline capacitance value which may be insensitive to sudden ambient changes and moving touch events affecting the mutual touch capacitive panel.

主权项

1. A method, comprising:
determining a first plurality baseline capacitance values of a capacitive touch panel corresponding to a first frequency; capturing in rapid succession, a first frequency frame scan of the capacitive touch panel at the first frequency and a second frequency frame scan of the capacitive touch panel at a second frequency; calculating differences in capacitance values of the capacitive touch panel between the first frequency frame scan and the second frequency frame scan; repeating, for a predetermined number of times:
the capturing of the first frequency frame scan;the capturing of the second frequency frame; andthe calculation of the differences in capacitance values of the capacitive touch panel between the first frequency frame scan and the second frequency frame scan, determining average differences in capacitance values of the capacitive touch panel between the first frequency frame scans and the second frequency frame scans; and generating a second plurality of baseline capacitance values of the capacitive touch screen corresponding to the second frequency by adding the determined average differences in capacitance values of the capacitive touch panel to the first plurality of baseline capacitance values of the capacitive touch screen corresponding to the first frequency.