| 摘要 |
PURPOSE:To correct output distortion, by lowering the magnetic field strength of the narrow section of a gap, and by heightening the magnetic field strength of the wide section. CONSTITUTION:A brushless motor 11 provided with a frequency power generator 21 as a rotational speed detector comprises a stator base 12, a rotor 15 with a rotor magnet 17 fitted on a rotary shaft 14, and a stator frame 19 with a fitted driving coil 18. The rotor 15 is provided with a bearing slot 15b in the axial center direction with a given spreading angle theta, and the rotary shaft 14 inserted into the slot 15b and the rotor 15 are fixed with a screw 20. Besides, the frequency power generator 21 is provided with its stator 22 and rotor 23, and between the rotor 23 and the upper surface of a magnet frame 16, there is a specified gap. Then, narrow and wide sections are formed on the gap, and so each magnetic field strength can be cancelled out, and output distortion due to the surface run-out of the rotor 23 can be corrected.
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