A crosstalk error correction algorithm for Capacitive Sensor panels

Projected Capacitive Sensors can be found in many applications in portable devices, integrated in touch screen sensor panels. In these systems, crosstalk between sensors can lead to inaccurate touch location. Parasitic capacitances in the sensor routing can cause shifts in the final capacitance measurements. In this paper, a novel algorithm is presented aimed at tackling this problem. With the sole knowledge of the panel layout, a simple correcting matrix is derived and applied to the readings, producing a more precise touch placement. No prior knowledge of the active circuitry or the parasitic capacitances is needed. This makes the approach “driver-independent”, meaning that the resulting matrix is only linked to the actual panel layout. The effectiveness of the algorithm is demonstrated with a full custom Controller IC and sensor panel.