| 摘要 |
PROBLEM TO BE SOLVED: To provide a motor which can generate sufficient torque and reduce vibration and noise. SOLUTION: A stepping motor 100 has a cylindrical magnet 13 comprising 2n long magnetic segments 13a which are arranged circumferentially and have widths equal to circular arc lengths corresponding to opening angles of 180/n degrees, and a coil bobbin device 19 mainly comprising an outer stator yoke 21, coils 22, and an inner stator yoke 24. The outer stator yoke 21 has n magnetic yokes which face the outside in the radial direction of the magnet 13 at positions corresponding to every other 2n pole segments 13a respectively with gaps between to constitute a magnetic circuit with the magnet 13 and the inner stator yoke 24. Each magnetic yoke has a portion whose width a is wider than a circular arc length corresponding to an opening angle of 180/n degrees and narrower than the circular arc length corresponding to an opening angle of 270/n degrees and a portion whose width c is narrower than a circular arc length corresponding to an opening angle of 90/n degrees.
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