Electromagnetic drive unit

摘要

In an electromagnetic drive unit including; a nearly E-shaped yoke having first and second concentric circular arc shaped side yokes respectively inside and outside an arc-shaped center yoke, a first arc-shaped permanent magnet fixed to said first side yoke so as to form a first magnetic gap inside said center yoke, a second arc-shaped permanent magnet fixed to said second side yoke so as to form a second magnetic gap outside said center yoke, and a movable coil member disposed in said magnetic gaps, said first and second permanent magnets are so provided with anisotropy in directions which are different each other that the magnetic flux density in said first magnetic gap will be nearly equal to that in said second magnetic gap.