Patent ID: 7446443

Claim:
An electromagnetically-driving device, comprising: a rotor with a hollow, cylindrical permanent magnet having a rotation center in a center of the magnet, an outside yoke disposed on an external circumference side of the rotor, the outside yoke comprising a soft magnetic member having a pair of magnetic pole-guide pieces opposed to each other in locations between which magnetic poles of the permanent magnet are sandwiched, an inside yoke disposed on an internal circumference side of the rotor, the inside yoke having a shaft portion shaped into a circular sectional form provided in at least a portion thereof, and secured and disposed in a central portion between the magnetic pole-guide pieces, and a coil for magnetically exciting the inside and outside yokes, wherein the rotor is integrally provided with a transmission member for transmitting rotation outside thereof, and comprises a bearing portion in an internal circumference face, the bearing portion being fitted to the shaft portion of the inside yoke, and the bearing portion of the rotor is rotatably fitted and supported to the shaft portion of the inside yoke.