| 摘要 |
The armature (1) of the stator has the shape of an isosceles trapezium whose base is divided at (2a) and has three polar outgrowths (1a, 1b and 1c). The rotor comprises a permanent magnet (4). The stator includes two coils (5 and 6), one of which is arranged between the polar outgrowths (1a and 1c) and the other between the stator and the polar outgrowth (1b). When the coils (5 and 6) are traversed by currents, they subject the rotor to magnetic fields whose directions are oblique and symmetrical with respect to a diameter of the rotor. The sense of the currents determines the sense of the fields. The arrangement is such that it is possible to create in the region of the rotor a magnetic field which can take four different directions depending on the senses of the currents flowing in the coils. By appropriately switching the senses of these two currents, this field can be rotated in one sense or the other, thus driving the rotor in one or the other, but always the same, sense. Thus, the rotor always rotates in the desired sense, even if it misses a step or makes one too many. <IMAGE>
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