Patent ID: 6348862
Filing Date: 2002-02-19
Classification: B60N,B60R,G01B,G01V,G08B,H03K

Abstract:
A proximity sensor for sensing an electric-field-influencing media within a region of space, comprising:a. a first electrode, wherein said first electrode is conductive; b. a first oscillatory signal operatively connected to said first electrode; c. at least one second electrode separated from and located proximate to said first electrode so that an electric field between said first electrode and said at least one second electrode occupies said region of space, wherein said electric field is responsive to said first oscillatory signal, and said at least one second electrode is conductive; d. at least one second oscillatory signal operatively connected to said at least one second electrode, wherein said at least one second oscillatory signal is coherent with said first oscillatory signal, and said at least one second oscillatory signal comprises a plurality of second signal components each selected from the group consisting of a signal level and a signal phase relative to a phase of said first oscillatory signal, wherein each signal component is at a distinct time; and e. a circuit operatively connected to said first electrode, wherein said circuit senses a third signal from said first electrode, wherein said third signal comprises a plurality of third signal components, said third signal is responsive to said first oscillatory signal, said third signal is responsive to said at least one second oscillatory signal, said third signal is responsive to a proximity to said first electrode of the electric-field-influencing media, said third signal is selected from the group consisting of a current of said first oscillatory signal, a voltage of said first oscillatory signal, and a capacitance of said first electrode, respective third signal components are respectively responsive to respective signal components of said plurality of second signal components applied to said at least one second electrode, and said circuit generates from said plurality of third signal components a measure of the proximity of the electric-field-influencing media to said first electrode.