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. 16, 2004
Filed:
Dec. 03, 2001
Japan Servo Co., Ltd., Tokyo-to, JP;
Abstract
A stator of the stepping motor of the invention includes an annular shaped yoke portion, a stator iron-core having twelve stator main poles each having a plurality of small teeth on the tip end thereof and stator coils wound in the stator iron-core as three-phase winding. The stator rotatably supports a hybrid type rotor having a cylindrical permanent magnet that is sandwiched between a pair of rotors each having pole teeth around the circumferential surface to be opposite to the small teeth. Second, third, fourth and fifth harmonic components are removed by composing cogging torque of the respective phases by means of the three-phase twelve-pole construction. Any one harmonic component of the cogging torque among the second to fifth harmonic components is independently erased by making a difference between the small teeth pitch and the rotor teeth pitch, thereby the selected harmonic component is doubly erased.