Patent ID: 6426635
Filing Date: 2002-07-30
Classification: G01D

Abstract:
A capacitive sensing system for detecting the angular position of a rotatable member of a motor comprising:(a) a motor having a rotor comprising: 1. an armature; and 2. a shaft extending from the armature; (b) a stator having a housing; (c) a cylindrical pin fixedly attached to the housing and connected to a source of oscillating electric energy; (d) a segmented tubular plate, having a plurality of sensing surfaces on an interior surface of the plate, fixedly attached to the housing and arranged to surround the cylindrical pin, thereby creating an annular space between the cylindrical pin and the segmented tubular plate; and (e) a lobed dielectric, affixed to an end of the shaft remote from the armature, said lobed dielectric residing in the annular space between the cylindrical pin and the tubular plate, whereby rotation of the armature changes the relative capacitances between the pin and the respective sensing surfaces.