| 摘要 |
The motor includes a coil (16), a stator (11) made of one piece, a rotor (18) and positioning means (20a, 20b) for affording the rotor two rest positions in which its axis of magnetisation (A) is directed along an axis of static equilibrium YY'. The stator has two pole parts (11a, 11b) which are interconnected by two intermediate parts (21a, 21b) and by four isthmus (12a - 12d) so that the intermediate parts are cut by the axis YY' and that two isthmus which are opposite with respect to the axis of rotation (Z) of the rotor are situated in a direction (VV', respectively WW') making an angle ( alpha , respectively beta ) of between 30 DEG and 60 DEG with the axis YY'. Two of these isthmus (12a, 12c) which are situated in the same direction (VV') have a width (l) such that they are very rapidly saturated with magnetic flux when the coil creates a field in the stator enabling the rotor to be turned in one direction (D) whereas the other two isthmus (12b, 12d) have a width (l') which is two to four times greater so that when the coil generates a field which takes the rotor in the other direction, the wide isthmus or, here also, the narrow isthmus saturate but less rapidly, so as to obtain a difference of current shape in the coil which allows determination of the direction in which the rotor is ready to turn in response to a motive pulse applied to it and to thus avoid any unintentional reversal of the direction of rotation of the motor. <IMAGE>
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