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:
Sep. 15, 2009
Filed:
Nov. 22, 2006
Shoji Oiwa, Kiryu, JP;
Masafumi Sakamoto, Kiryu, JP;
Toru Kobayashi, Kiryu, JP;
Masahiko Azegami, Kiryu, JP;
Yasuaki Motegi, Kiryu, JP;
Takaya Kato, Kiryu, JP;
Yasuo Matsuda, Kiryu, JP;
Kazuo Onishi, Kiryu, JP;
Naoyuki Kanamori, Kiryu, JP;
Tadashi Fukushima, Kiryu, JP;
Shoji Oiwa, Kiryu, JP;
Masafumi Sakamoto, Kiryu, JP;
Toru Kobayashi, Kiryu, JP;
Masahiko Azegami, Kiryu, JP;
Yasuaki Motegi, Kiryu, JP;
Takaya Kato, Kiryu, JP;
Yasuo Matsuda, Kiryu, JP;
Kazuo Onishi, Kiryu, JP;
Naoyuki Kanamori, Kiryu, JP;
Tadashi Fukushima, Kiryu, JP;
Nidec Servo Corporation, Kiryu-shi, JP;
Abstract
A stepping motor includes: a stator having main magnetic poles each having small stator teeth on its tip, a core-back portion that connects outer portions of the poles, and windings wound around the poles; and two sets of rotor units that are arranged in an axial direction and face the stator with an air gap therebetween. Each rotor unit consists of two rotor cores that are separated in the axial direction and a magnet sandwiched thereby and magnetized in the axial direction. Each rotor core has small rotor teeth around its outer surface. The rotor cores of each rotor unit are deviated by ½ pitch of the small rotor teeth, and the two rotor units are arranged to make the magnetic polarities of the small rotor teeth of the adjacent two rotor cores identical. A magnet thickness Tm and a rotor core thickness Tc satisfy 0.25≦Tm/Tc≦0.45.