DISPOSITIF MOTEUR, NOTAMMENT POUR L'HORLOGERIE

A magnet (11) for positioning the rotor (9) is arranged so that in the absence of pulses in the drive coil (5) the straight line defined by the pair of NS poles of the rotor (9) is perpendicular to the principal direction of the lines of force of the magnetic field leaving the armature (7) and produced in the latter by the field of the coil (5). The control means of the motor are arranged so that the pulses are delivered in pairs, and with opposite polarities in each pair, the order of sequence of the polarities in a pair determining the direction of rotation of the rotor. Through this arrangement, if the rotor, following a knock for example, makes an accidental half-revolution or has not reacted to the despatching of a drive pulse, its direction of rotation does not reverse.