Patent ID: 7135874

Claim:
A capacitive rotation angle sensor for measuring a movement in a rotational rheometer, comprising: an excitation array having a plurality of first emitters and a plurality of second emitters, the plurality of first emitters emitting a first sinusoidal signal, and the plurality of second emitters emitting a second sinusoidal signal, the second sinusoidal signal being out of phase with the first sinusoidal signal; a measurement array arranged opposite to the excitation array and having a plurality of first detectors and a plurality of second detectors, the plurality of first detectors sensing a first voltage of the first and second sinusoidal signals and the plurality of second detectors sensing a second voltage of the first and second sinusoidal signals; and an active rotor array that is adapted to be mechanically coupled to a drive shaft of the rotational rheometer and rotationally moved between the excitation array and the measurement array, the active rotor array having a plurality of first movable elements and a plurality of second movable elements, the plurality of first movable elements being driven by the first voltage and the plurality of second movable elements being driven by the second voltage, wherein movement of the active rotor array varies the first and second voltages and the active rotor array determines the movement of the drive shaft of the rotational rheometer from the first and second voltages.