The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Mar. 01, 1994
Filed:
Aug. 23, 1991
Seiki Shiotsuki, Yokohama, JP;
Shingo Sanbe, Yokohama, JP;
Shinichi Kanaya, Tokyo, JP;
Masamichi Furukawa, Tokyo, JP;
Shigeru Taneichi, Yokohama, JP;
Canon Seiki Kabushiki Kaisha, Tokyo, JP;
Canon Kabushiki Kaisha, Tokyo, JP;
Abstract
A stepping motor having two stator units axially arranged. Each of the stator units includes an inner yoke and an outer yoke having a plurality of pole teeth circumferentially formed at a predetermined pitch around a rotor having magnetic poles. The outer yoke of one of the stator units is asymmetrically arranged so that the pole teeth thereof are shifted from center between the pole teeth of the inner yoke in a specific direction. As a result, a cogging torque is reduced, constant speed rotation is attained and variations in the output torque are eliminated. Variation in the generated torque are also reduced by controlling the drive pulse width, the drive voltage or the drive current during the driving operation in accordance with the number of excitation phases.