| 摘要 |
PURPOSE:To reduce cogging ripple, by providing tooth sections and slot sections for a substrate for frequency signal generation, and by arranging the sections making them get out of position of the corresponding sections of an armature core roughly at half a pitch. CONSTITUTION:A printed wiring substrate 8 is fitted on the lower face of a lower cylinder, and position-detecting elements 9 of Hall elements or the like and circuit components are arranged. And on the periphery of the lower bearing shell section of the lower cylinder, an armature core 10 is supported via cylindrical supporting member and is wound up with an armature coil 12. And a substrate 13 for frequency signal generation is fixed confronting the armature core 10 coaxially. On the outer periphery of the substrate 13, tooth sections 13a and slot sections 13b similar to the tooth sections 10a and the slot sections 10b of the armature core 10 respectively in the shapes are formed, and a pattern 13c for frequency signal generation is formed inside the substrate 13. Then, the sections corresponding to the armature core 10 and the substrate 13 are set to get out of position roughly at half a pitch in the peripheral direction. Then, the components get out of phase at the angle of 180 deg., and cogging ripple is reduced. |
