The electroquasistatics of the capacitive touch panel
Philip T. Krein, R.D. Meadows · IEEE Transactions on Industry Applications · 1990
The capacitive touch panel, a high-resolution position sensor intended for computer displays, must be safe and inexpensive and must sense position accurately in spite of electrical noise, dirt, or direct electrostatic discharge. The implementation discussed uses a quasi-static electric field, applied to a semiconducting coating on the panel surface. A touch draws current from the surface. This current can be used to compute position. If the computation is performed properly, the computed position is independent of touch current and panel coating resistivity. The electroquasistatic basis for position measurement with a capacitive touch panel and a system to implement it are described.>