| 摘要 |
PROBLEM TO BE SOLVED: To improve precision in detecting a rotational speed by reducing noise superimposed on an FG signal, while securing high driving efficiency.SOLUTION: A stator 13 on whose outer circumference a plurality of magnetic poles 13a are arranged is mounted on a substrate 11, and a rotor 14 is rotatably disposed around the stator. The inner circumferential face of the rotor is provided with a magnet 15 magnetized to have alternately opposite polarities in a direction opposing the stator, and magnetized to have alternately opposite polarities in a direction opposing the substrate. The outer circumferential ends of the magnetic poles of the stator are provided with a first extended portion 13c that extends from a magnetic pole base 13d to the substrate side, and a second extended portion 13b that extends from the magnetic pole base to a side opposite the substrate side. A face of the substrate opposing the rotor is provided with an FG pattern 19 outside the outer circumferential face of the stator such that the FG pattern opposes the magnet. |
