Patent ID: 7078915
Filing Date: 2006-07-18
Classification: G01D

Abstract:
1. A system for outputting signals representative of an angular position, comprising: a vehicle steering column; a rotor made of dielectric material and coupled to the steering column such that the rotor rotates with the steering column, the rotor defining opposed semicircularly-shaped first and second surfaces; an excitation electrode member closely spaced from the first surface of the rotor and not contacting the rotor, the excitation electrode member not rotating when the rotor rotates, the excitation electrode member including plural excitation electrodes; a receiver electrode member closely spaced from the second surface of the rotor and not contacting the rotor, the receiver electrode member not rotating when the rotor rotates; a circuit, wherein the circuit includes at least one select switch operating at a frequency lower than an excitation frequency, supplying excitation signals to the excitation electrode member and receiving signals from the receiver electrode member, the signals from the receiver electrode member being useful in determining an angular position of the steering column; and wherein the switch has a first configuration in which first and second excitation electrodes are connected together to establish a first capacitance relative to the receiver electrode member and third and fourth excitation electrodes are connected together to establish a second capacitance relative to the receiver electrode member, a difference between the first and second capacitances being representative of the angular position of the rotor, the switch being configurable in a second configuration in which the first and fourth excitation electrodes are connected together to establish a third capacitance relative to the receiver electrode member and the second and third excitation electrodes are connected together to establish a fourth capacitance relative to the receiver electrode member, a difference between the third and fourth capacitances being representative of the angular position of the rotor.