Eta Sa Fabriques D'ebauches

Yves Guerin

Daho Taghezout

Fridolin Wiget

Remy Grandjean

An electromechanical transducer (1), in particular a motor used in timepieces, having a stator (2) and two rotors (14 and 15). The two rotors (14 and 15) are situated respectively in two stator holes (4 and 6) each defined by three stator poles (8a, 10a, 12a; 8b, 10b, 12b). The transducer (1) is capable of functioning as a stepping motor, each of the two rotors being capable of rotating in the two possible rotational directions independently of the other rotor.

Electromechanical transducer comprising two rotors

The control device is intended to supply a stepping motor with driving pulses during which the mean value of the voltage applied to the coil of this motor is independent from the voltage of the power supply source of the device. For that purpose, the control device comprises a driving circuit which connects or disconnects the coil of the motor to or from the power supply source when a control signal has a first state or a second state respectively, and a control circuit which produces this control signal with its first state or its second state in dependency on the difference between a reference voltage and the voltage across the coil.

Control circuit for a stepping motor

The invention concerns a method for controlling a bidirectional stepping motor having two windings and three pole faces. The invention comprises applying current pulses alternately to only one of the motor windings to cause it to rotate in one direction and to only the other of the motor windings to cause it to rotate in the other direction. The invention is used for controlling bidirectional motors which are employed in particular in timepieces.

Method and device for controlling a bidirectional stepping motor

The rotor of a stepping motor may remain blocked in an intermediate position different from a rest position if its control circuit adjusts the electric energy of the driving pulses to the minimum corresponding to the actual mechanical load of the motor determined by a measuring circuit. To remove this risk, the method consists in producing with the aid of a generator and applying to the motor, pulses which allow release of the rotor when it has remained blocked in an intermediate position in response to a driving pulse. The release pulses are distinct from any correction pulses which are applied in known manner to make up a lost step. The release pulses precede the correction pulses and are preferably of such polarity as to return the rotor to its starting position to ensure correct action of the ensuing correction pulses. This method applies in particular to the control of the stepping motor of an electronic timepiece.

Method and device for controlling a stepping motor

The motor unit comprises a stator, two independent rotors having each a permanent magnet located in a cylindrical space defined by three pole faces of the stator, two windings and at least a positioning magnet for holding both rotors, in the absence of current in the windings, in a position in which the magnetic axes of their magnets are each coincident with a rest axis. The field produced by the flow of a current in one of the windings is always at an obtuse angle to one of the rest axes and at an acute angle to the other. The two rotors perform steps of 360.degree. independently of each other in response to pairs of current pulses, the first of which is applied to one of the windings and the second of which is applied to the other winding. The direction of the current pulses determines which of the rotors performs a step, and the order in which the current pulses are applied to the windings determines the direction of rotation of that rotor. The motor unit can be used in particular in an electronic timepiece.

Stepping motor unit

The present invention comprises measuring, upon application of a drive pulse to the actuating coil 5 of the stepping motor, the variation in the magnetic induction flux in the stator of the motor, and interrupting the drive pulse when the variation in flux reaches a predetermined value. Measurement of the variation in flux may be effected, for example, by detecting the current in the actuating coil and integrating the difference between the supply voltage of the actuating coil and the product of the current by the d.c. resistance of the coil, or by providing an auxiliary detection coil 71 and integrating the voltage induced therein in an integrator 73, 74. When the integrator outputs exceeds the magnitude of either a positive or negative reference voltage, a comparator circuit 78, 79, 81 provides the signal to a circuit 13 to terminate the drive pulse. The foregoing abstract is not to be taken as limiting the invention described herein, and in order to understand the full nature and extent of the technical disclosure herein, reference should be made to the accompanying drawings and detailed description.

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Granges, Switzerland

Yves Guerin