| US 7,612,479 B2 | ||
| Scanner for equalizing torque constant and reducing torque constant variation | ||
| Akira Doi, Hitachinaka (Japan); Haruaki Otsuki, Hitachinaka (Japan); Atsushi Sakamoto, Hitachinaka (Japan); Souichi Toyama, Ebina (Japan); and Yaichi Okubo, Ebina (Japan) | ||
| Assigned to Hitachi Via Mechanics, Ltd., Ebina-shi (Japan) | ||
| Filed on Jun. 23, 2006, as Appl. No. 11/473,110. | ||
| Claims priority of application No. 2005-184253 (JP), filed on Jun. 24, 2005. | ||
| Prior Publication US 2007/0007828 A1, Jan. 11, 2007 | ||
| Int. Cl. H02K 21/12 (2006.01) | ||
| U.S. Cl. 310—156.38 [310/36] | 5 Claims |
| 5. A scanner comprising:
a rotor formed from permanent magnets having N poles and S poles disposed alternately in a circumferential direction,
wherein each of the permanent magnets forming the N poles and the S poles is formed so that the outer diameter of a circumferential
intermediate portion of the permanent magnet is smaller than the outer diameter of a circumferential end portion of the permanent
magnet, and
wherein each permanent magnet further has small-diameter portions which are formed in such a manner that a portion with a
diameter substantially equal to those of the opposite end portions is formed in the intermediate portion smaller in diameter.
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