| 摘要 |
PROBLEM TO BE SOLVED: To realize miniaturization and the reduction of cost by providing a motor having a specified rotor. SOLUTION: A stepper motor 113 includes the rotor 130. The rotor 130 is produced as one integrated part made of the same magnetic material. The rotor 130 is moved by magnetic field supplied by a stator 120, and formed in the shape of a ring having a cylindrical outer surface 130a and a cylindrical inner surface 130b forming a hollow center part 130c. In such a case, the rotor 130 is provided in the stator 120 in order to reduce the mass of the rotor 130. It is desirable to make the rotor 130 as small as possible and the hollow center part 130c as large as possible so as to keep the stepper motor 113 compact. However, if the rotor 130 is too small, it is hardly rotated because the sufficient magnetic field is not generated. Therefore, it is desirable to set the thickness of the rotor 130 to about 0.5 to 1.5 mm and the length of the rotor 130 to 2.5 to 5 mm.
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