| 摘要 |
PURPOSE:To achieve miniaturization by providing a stator with a driving coil constituting a motor in a nut member, and providing a rotor in a screw shaft which has been screwed directly in the nut member or indirectly in it via balls respectively. CONSTITUTION:A step motor is comprised of a screw shaft 20 on which a projected thread body 23 is integrally provided, and a stator 40 which is arranged in a nut member 30 in which the screw shaft is screw-fitted via balls B, and when the driving coil 43 of the stator 40 is electrified to excite T-shaped project ed pieces 41, the screw shaft 20 being commonly used for a rotor is turned in a prescribed direction, consequently the nut member 30 moves in the axial direction. In this movement, when the detecting part 50 in the nut member 50 detects the part to be detected 24 on the screw shaft 20, the electrification is stopped by the signal to prevent overrun. Thus, the miniaturization of a feed screw device can be enabled.
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