| 摘要 |
PROBLEM TO BE SOLVED: To obtain a micromotor whose diameter and length are both about 1 cm, the motor being increased in torque without altering a driving circuit nor varying the shape and size large. SOLUTION: A magnetic sheet which is magnetized along the thickness is arranged between a driving coil and a yoke forming an external case to produce a composite magnetic field by a rotor made of a permanent magnet and the magnetic sheet, and thus magnetic flux crossing the driving coil is increased in density to improve the torque. In addition, a metal piece having the same magnetic characteristics as the yoke is arranged halfway in a magnetic path formed at an intermediate position between the driving coil and a damping coil and reluctance effect generated thereby is used to improve the torque. Alternatively, the driving coil and damping coil are formed in double-winding structure and the coil in the double-winding structure is divided into two parts, which are arranged symmetrically about the axis of rotation of the rotor. COPYRIGHT: (C)2007,JPO&INPIT
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