Patent ID: 7242123
Filing Date: 2007-07-10
Classification: H02K

Abstract:
1. An actuator, comprising: a magnet which is formed in a ring shape, in which at least one surface perpendicular to a central axis thereof is divided in a circumferential direction and alternately plane-magnetized in different poles; a stator including a plurality of magnetic pole teeth opposed to the magnetized surface of the magnet; a rotor which includes a shaft portion held to be rotatable around the central axis, and a disk portion whose surface perpendicular to the shaft portion is bonded to the magnet, and which is made of a soft magnetic material for passage of magnetic fluxes of a magnetic circuit; a bearing which is fixed to the stator, rotatably supports the shaft portion of the rotor, and is made of a soft magnetic material; and a coil which is coaxially located at inner circumference side of the magnet, is located at substantially the same position of the magnet in a direction along the central axis, is fixed to the stator, and excites the stator and the disk portion, wherein the magnet is fixed to a surface which is a surface of an outer circumference side of the disk portion of the rotor, and which is opposed to the stator, the coil is fixed to a surface which is a surface on an inner circumference side of the stator, and which is opposed to the magnet, and the rotor is positioned in an axial direction by making a tip protruding portion of the axis portion be in contact with a bottom side of the bearing and the bearing is extended such that a tip end surface thereof is close to the disk portion of the rotor.