US Patent 7317273 Electromagnetic actuator and portable device having the same

An electromagnetic actuator includes a cylindrical stator made of a permanent magnet and having annular end faces magnetized to plural magnetic poles, a coil securely disposed in a hollow portion of the stator via a bobbin on which the coil is wound and which is fixed to the stator's hollow portion, a rotary shaft put through the coil in the direction of the center axis thereof in such a way as to be rotatably supported at the bobbin, and a rotor of a soft magnetic material provided in such a way as to rotate together with the rotary shaft and having plural rotor arms radially extending from both end portions of the rotary shaft and facing the respective annular end faces of the stator.