Patent ID: 6424146
Filing Date: 2002-07-23
Classification: G01B,G01D,G01V

Abstract:
A proximity sensor comprising:a detector which changes AC conductance as the gap distance between the detector and a target changes; DC conductance measuring means connected to the detector via one or more wires having a length sufficient to cause a non-negligible phase shift in an AC signal traveling therethrough, the DC conductance measuring means producing a first output indicative of the DC conductance of the detector and the one or more wires; AC conductance measuring means connected to the detector via the one or more wires, the AC conductance measuring means producing a second output indicative of the AC conductance of the detector and the one or more wires; susceptance measuring means connected to the detector via the one or more wires to produce a third output indicative of the susceptance of the detector and the one or more wires; and, data processing means connected to receive the first, second, and third outputs and operable to calculate the gap distance between the detector and the target, the data processing means using at least one equation and/or at least one database entry that is at least indirectly dependent on the first, second and third outputs to calculate the gap distance.