| 摘要 |
A synchronous motor device for a timepiece including a synchronous motor for the timepiece having a rotor with a pair of magnetized rotor poles around its circumference, a stator consisting of a pair of stator plates with a plurality of stator poles arranged around the vicinity of said rotor separated by an air gap, and an energizing coil supplying alternating magnetic flux to said stator. The synchronous motor for timepiece includes main stator poles, first supplementary stator poles and second supplementary stator poles. The main stator poles are further provided with both of the stator plates at the facing position against the rotor shaft and mainly forms the static stable position of the rotor. The first supplementary stator poles are facingly positioned against the rotor shaft and provided with both of the stator plates at separate positions from said main stator poles. This first supplmentary stator poles form the dynamic stable position of the rotor in the cooperation with the main stator poles and have wider gaps than the main stator poles. The second supplementary stator poles are facingly positioned against the rotor shaft and provided in the vicinity of the dynamic stable position of the rotor in order to place the predetermined braking force on the rotor which rotates over the dynamic stable position. This second supplementary stator poles have wider air gaps than the main stator poles and the first supplementary stator poles. Consequently the synchronous motor can achieve the properties of smooth self-starting rotation.
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