An efficient detection on capacitive touch screens using bandwidth expansion

This paper presents a new efficient detection method on capacitive touch screens by mixing multi-channel inputs and expanding the sensing bandwidth. Multi-channel touch signals can be combined with a modulation scheme which allows an overlap in spectral domain. By expanding the sensing bandwidth, the overlapped region can be minimized which leads to more accurate detection. The touch-detection problem is formulated as an event detection problem which decides touch-input status under Gaussian noise. We provide the numerical analysis of the proposed scheme, and show the relation between the detection performance and the bandwidth expansion rates. The simulation result confirms that slight increase in sensing bandwidth yields an accurate touch detection using the proposed sensing and detection schemes.