A combined passive and active object sensing system (30; 50; 70) employing electric field sensing is described. An electric field sensing transmission electrode (2) generates a first electric field (11, 12, 13) that induces a current in an electric field sensing reception electrode (4). A passive object...http://www.google.de/patents/US7109726?utm_source=gb-gplus-sharePatent US7109726 - Object sensing
