Patent ID: 7180306

Claim:
An electric field sensor, comprising: at least one electrode; a first reference capacitor; a second reference capacitor; and a sensing circuit comprising a plurality of states, wherein in a first state said sensing circuit is operatively coupled to at least one said electrode so as to provide for generating a first signal responsive to the capacitance of said at least one said electrode, in a second state said sensing circuit is operatively coupled to said first reference capacitor so as to provide for generating a second signal responsive to the capacitance of said first reference capacitor, in a third state said sensing circuit is operatively coupled to said second reference capacitor so as to provide for generating a third signal responsive to the capacitance of said second reference capacitor, and said sensing circuit is adapted to provide for generating a measure responsive to the capacitance of said at least one said electrode responsive to said first signal, said second signal and said third signal.