Capacitive proximity sensing is carried out by detecting a relative change in the capacitance of a "scoop" capacitor formed by a conductor and a surrounding ground plane. The conductor may be a plate provided in the form of an adhesive label printed with conductive ink. Charge is transferred between...http://www.google.de/patents/US6661410?utm_source=gb-gplus-sharePatent US6661410 - Capacitive sensing and data input device power management
