Dual Capacitive Touch Sensing for Moisture Rejection

The touch interface system segments the sensing function into two distinct measurement modes: self-capacitance sensing and mutual capacitance sensing. Each mode is optimized for specific detection requirements - self-capacitance for high sensitivity to bare and gloved fingers, and mutual capacitance for proximity rejection. The system processes measurements from both modes separately and combines them to achieve both high sensitivity and reliable proximity rejection simultaneously.

The system introduces mutual capacitance sensing as an intermediary measurement mode that acts as a filter against moisture-induced false touches. While self-capacitance sensing is highly sensitive to all capacitive changes including moisture, mutual capacitance sensing requires direct finger contact through the display surface. By using mutual capacitance measurements as a verification layer, the system distinguishes between valid touches and invalid moisture detections, eliminating false positives while preserving high sensitivity for legitimate touches.

The system merges two different capacitance sensing approaches - self-capacitance and mutual capacitance - into a unified touch detection system. Self-capacitance sensing provides high sensitivity by detecting changes in self-capacitance values, while mutual capacitance sensing provides proximity rejection by detecting changes in mutual capacitance between transmitter and receiver electrodes. By combining measurements from both sensing modes and requiring agreement between them, the system achieves both high touch detection sensitivity and reliable proximity rejection without compromising either function.