| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a technology by which a DC motor of low cogging torque can be provided at a low cost. <P>SOLUTION: A groove 101 is installed in the outer peripheral surface of the axial direction center of a cylindrical magnet 100 functioning as a field magnet of a DC motor, and this can suppress the phenomenon that the magnetic flux density of a magnetic field formed within the cylindrical magnet is relatively higher in the neighborhood of both ends of the axial direction while the magnetic flux density is relatively lower in the neighborhood of the center. Thus the DC motor of low cogging torque can be provided at a low cost. <P>COPYRIGHT: (C)2012,JPO&INPIT |
