Patent ID: 7760059
Filing Date: 2010-07-20
Classification: G01R,H01F

Abstract:
1. A permanent magnet type magnetic field generating apparatus comprising: a plurality of permanent magnet pieces disposed in a ring shape so that a substantially unidirectional magnetic field is generated in a space within the ring, the permanent magnet pieces having the magnetization direction undergoing one rotation over a half-circumference of the ring, the permanent magnet pieces having substantially the same magnetic strength, and the permanent magnet pieces each having an outer side defining an outer surface of the ring, and an opposite inner surface facing towards a center axis of the ring, wherein each of the outer sides of the permanent magnet pieces includes a pair of ends that are each in an abutting relation with the end of an outer side of an adjacent permanent magnet pieces such that the outer side of each permanent magnetic piece is coterminous with the outer side of an adjacent permanent magnetic piece, the permanent magnet pieces being disposed so as to form indentations and protrusions toward the center axis of the ring, or having a shape having indentations and protrusions facing the center axis, wherein each of the permanent magnet pieces is unseparated as to a radial direction of the ring.