Patent ID: 6803685
Filing Date: 2004-10-12
Classification: G01D,H01R,H02K,Y10T

Abstract:
An encoder device incorporated in a miniature motor, the encoder device being incorporated in a miniature motor having an end cap fitted to a metallic case in such a manner as to close an opening of the metallic case, a rotor configured such that a rotor magnetic-pole and a motor commutator are integrally mounted on a rotatably supported shaft, and two motor brushes abutting the commutator;the encoder device comprising a rotary contact portion provided on the rotor shaft, and a pair of rotation-detecting brushes in sliding contact with the rotary contact portion; wherein a plurality of rotary contact pieces are arranged on an outer circumferential surface of the rotary contact portion such that slits are formed therebetween; the paired rotation-detecting brushes are each formed of a resilient metal and each assume the shape of a cantilever plate or wire spring whose side surface portion is subjected to sliding contact; and an inter-brush angle corresponding to an arcuate angle between contact points at which the paired rotation-detecting brushes abut the rotary contact portion is less than an arcuate angle corresponding to a single rotary contact piece, whereby a plurality of pulses are generated while the rotor shaft rotates one revolution.