Slip ring with balanced center of gravity for use in detecting rotation of motor

摘要

A slip ring with which a pair of brushes make contact includes a conducting portion which extends along an outer periphery of the slip ring over an angle of preferably about 210 degrees, and a non-conducting portion which extends over an angle of about preferably 150 degrees. A conductor which forms the conducting portion has a ring-like shape and also forms the non-conducting portion. The portion of the conductor which corresponds to the non-conducting portion has a small radius such that it is buried in an insulating resin material, a window through which an insulating resin material is exposed, or a recess through which an insulating resin material is exposed. The ring-like conductor provides a balanced center of gravity to the slip ring. The conductor may also include two or more conducting portions and two or more non-conducting portions.