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:
Nov. 09, 1993
Filed:
Jul. 17, 1991
OKI Electric Co., Ltd., Tokyo, JP;
Abstract
A permanent magnet type stepping motor comprising first and second stator assemblies arranged coaxially about a longitudinal axis. Each assembly includes first and second ring-shaped stators made of magnetic material. The first ring-shaped stator has a central portion with an opening therein, an annular yoke surrounding the periphery of the central portion and a plurality of pole pieces distributed about the circumference of the opening and extending toward a plane transverse to the axis. The second ring-shaped stator has a central portion with an opening therein, an annular substantially planar yoke surrounding the periphery of the central portion and a plurality of pole pieces distributed about the circumference of the opening and extending away from the transverse plane so as to interleave with the pole pieces of the first stator. The central portion of the second stator protrudes from the plane of the yoke in a direction away from the transverse plane. A coil is interposed between the first and second ring-shaped stators and surrounds the pole pieces. The first and second stator assemblies are arranged with respect to the transverse plane so that the second ring-shaped stator of the first stator assembly is adjacent the second ring-shaped stator of the second stator assembly at the transverse plane thereby forming a gap between the protruding central portions of the second stators of the first and second stator assemblies. A permanent magnet having N and S poles distributed alternately about the outer circumference thereof is rotatably supported within the openings in the central portions of the first and second stators of the first and second stator assemblies.