EP0108711B1 - Method and device for controlling a step motor - Google Patents

Method and device for controlling a step motor Download PDF

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Publication number
EP0108711B1
EP0108711B1 EP83810453A EP83810453A EP0108711B1 EP 0108711 B1 EP0108711 B1 EP 0108711B1 EP 83810453 A EP83810453 A EP 83810453A EP 83810453 A EP83810453 A EP 83810453A EP 0108711 B1 EP0108711 B1 EP 0108711B1
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EP
European Patent Office
Prior art keywords
rotor
pulse
duration
circuit
winding
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EP83810453A
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German (de)
French (fr)
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EP0108711A1 (en
Inventor
Yves Guerin
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ETA Manufacture Horlogere Suisse SA
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ETA Manufacture Horlogere Suisse SA
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    • G—PHYSICS
    • G04—HOROLOGY
    • G04C—ELECTROMECHANICAL CLOCKS OR WATCHES
    • G04C3/00—Electromechanical clocks or watches independent of other time-pieces and in which the movement is maintained by electric means
    • G04C3/14—Electromechanical clocks or watches independent of other time-pieces and in which the movement is maintained by electric means incorporating a stepping motor
    • G04C3/143—Means to reduce power consumption by reducing pulse width or amplitude and related problems, e.g. detection of unwanted or missing step

Definitions

  • One of the objects of the present invention relates to a method of controlling a stepping motor having a coil, a rotor magnetically coupled to the coil and means for bringing or holding the rotor in at least one rest position determined in the absence of current in the coil, consisting in applying to the coil a driving pulse having a first duration each time the rotor must turn by one step, to produce a detection signal if the rotor has not turned correctly in response to the driving pulse, to apply a catch-up pulse to the coil having a second duration greater than the first duration in response to the detection signal, and to apply to the coil, before the catch-up pulse, a release pulse having a third duration less than the first duration intended to cause the rotation of the rotor to the rest position if the latter has been locked in another position.
  • Another object of the present invention relates to a device for controlling a stepping motor having a coil, a rotor magnetically coupled to the coil and means for bringing or maintaining the rotor in at least one rest position determined in the absence of current in the coil, comprising means for applying a driving pulse having a first duration to the coil each time the rotor must turn one step, means for producing a detection signal if the rotor has not not turned correctly in response to the driving pulse, means for applying to the coil a catch-up pulse having a second duration greater than the first duration in response to the detection signal, and means for applying to the coil, before the catch-up pulse, an unlocking pulse having a third duration less than the first duration intended to cause the rotation of the rotor to the rest position if the latter has been locked in another position.
  • the electrical energy required to drive the mechanical elements connected to a stepping motor which can be, for example, the elements for displaying the time information of an electronic timepiece constituted by hands and / or discs, it is generally supplied to it by a control circuit which delivers a driving impulse each time it has to advance one step.
  • a significant reduction in this electrical energy consumed by the motor can be obtained by providing in the control circuit a circuit which adjusts the energy of the driving pulses to the minimum corresponding to the actual mechanical load driven by the motor.
  • US-A-4,212,156 for example, describes a control circuit in which the duration of each driving pulse is already determined before it begins.
  • a detector circuit measures the time which elapses between the end of each driving pulse and the appearance of the first minimum of the current induced in the coil by the oscillations of the rotor around its equilibrium position.
  • control circuit does not modify the duration of the following driving pulses, or, as the case may be, decreases this duration.
  • the control circuit then sends a catch-up pulse of long duration and of the same polarity as the driving pulse which has just ended and increases the duration of the following driving pulse.
  • the detection of the rotation or of the non-rotation of the rotor is therefore carried out immediately, or almost, after each driving pulse.
  • Patent US-A-4,300,223 describes another kind of control circuit in which the duration of each driving pulse is predetermined.
  • a detector circuit measures the intensity of the current flowing in the motor coil about two milliseconds after the start of each driving pulse. If this intensity is less than a predetermined value, this indicates that the rotor is in the correct position to turn in response to this driving pulse, and therefore that it has rotated in response to the previous driving pulse. If this intensity is greater than the predetermined value, this indicates that the rotor is not in the correct position, and therefore that it has not rotated in response to the previous driving pulse. In this case, the control circuit then interrupts the current driving pulse, sends the motor a catch-up pulse of the same polarity as the previous driving pulse, then sends the normal driving pulse again.
  • Patent application EP-A-22 270 describes another control circuit in which the duration of each driving pulse is predetermined. At the end of each driving pulse, the motor coil is placed in open circuit, and the voltage induced by the rotation of the rotor is measured. If this voltage is greater than a predetermined value, it means that the rotor has turned correctly in response to this driving pulse. If, on the other hand, this tension is lower than this predetermined value, it means that the rotor was not in the position which it should have occupied at the beginning of this driving impulse, and therefore that it did not turn in response at the previous driving impulse nor in response to this driving impulse. The control circuit then applies to the motor two take-up pulses having a long duration and intended to cause the rotor to perform the rotations which it has not carried out in response to these two driving pulses.
  • Patent application EP-A-24 737 describes a circuit of the same kind as the previous one, but in which the detection of the rotation, or not, of the rotor is made by determining whether the integral of the voltage induced in the coil of the engine for a specified period exceeds or does not exceed a predetermined value.
  • the duration of the driving pulses is generally less than the time taken by the rotor to perform its pitch.
  • the electric energy supplied to the motor by each driving pulse is, in principle, sufficient for the rotor to end its step thanks to the kinetic energy which it has accumulated and to a positioning torque which tends to bring it back or to maintain it , in the absence of current in the coil, in a rest, or equilibrium, stable and determined position.
  • This positioning torque is created by a particular shape given to the pole pieces which surround the rotor of the motor, or by one or more positioning magnets.
  • Curve 1 in FIG. 1 schematically illustrates the variation of this positioning torque as a function of the angle of rotation of the rotor, between two positions of stable equilibrium corresponding to points A and B.
  • this torque When this torque is positive, it tends rotating the rotor in the increasing direction of the angle a and, when it is negative, it tends to rotate it in the decreasing direction of this angle a.
  • the rotor rotates in 180 degree steps, which means that it has two stable equilibrium positions per revolution.
  • the rotor pitch corresponds to a rotation of 360 degrees, which means that the rotor has only a stable equilibrium position.
  • the period of the positioning torque is equal to the angle which separates two successive stable equilibrium positions of the rotor.
  • a position of the rotor represented by the 'point C in Figure 1, and which corresponds approximately to a rotation of half a step, for which this couple is canceled and changes sign.
  • This point C therefore corresponds to an unstable equilibrium position of the rotor.
  • the mechanical load driven by the motor is made up for a large part by the resistant torque due to the inevitable friction of the pivots of the rotor and the toothed wheels which it drives in their bearings, as well as by the friction of the teeth of these wheels between them.
  • This friction torque is represented diagrammatically by curves 2 and 3 in FIG. 1.
  • the rotor If the energy supplied to the rotor by a driving pulse is sufficient for the rotor to reach point D but is not sufficient for it to reach and exceed point E, the rotor therefore remains locked in an intermediate position which can be located anywhere between these points D and E.
  • FIG. 2 schematically illustrates an engine of the type most commonly used in electronic timepieces in the situation where its rotor is locked in such an intermediate position.
  • This figure 2 shows the coil 11, two pole pieces 12 and 13 which are part of the stator of the motor, and the magnet 14 of the rotor.
  • the magnetization axis of this magnet 14 is represented by the arrow 15 which is directed from its south pole towards its north pole.
  • the positioning torque of the rotor is created, in this example, by the notches 16 and 17 formed respectively in the pole pieces 12 and 13.
  • the motor control circuit In normal operation, the motor control circuit, not shown in this FIG. 2, delivers driving pulses to the coil 11 in response to control pulses supplied, for example, by a time base circuit each time the rotor must take a step forward.
  • point A in FIG. 1 corresponds to the position of the rotor where the magnetization axis of its magnet is represented by the arrow 15 'drawn in dotted lines in FIG. 2, and that the rotor has has been brought to the position represented by the arrow 15 by a driving pulse designated by the reference 18 in FIG. 3 and applied to the coil 11 so that the pole piece 12 plays the role of a south magnetic pole and that the pole piece 13 plays the role of a north magnetic pole.
  • the energy supplied to the motor by this pulse was sufficient for the rotor to reach a position situated beyond point D in FIG. 1, but, for some reason, it was insufficient for this rotor to exceed the position corresponding to the point E.
  • the rotor therefore remained locked in the intermediate position shown in FIG. 2.
  • this control circuit sends the motor a catch-up pulse as soon as it detects that the rotor has not finished its pitch.
  • This catch-up pulse which is designated by the reference 19 in FIG. 3, has the same polarity as the driving pulse 18 and a determined duration for turning the rotor by a full step, from point A to point B.
  • this catch-up pulse is not yet finished when the rotor reaches a point B 'which is the point where the positioning torque and the torque created by the current in the coil cancel each other.
  • the rotor oscillates around this point B ', and at the moment when the catch-up pulse ends, it is very possible that it has a speed and a direction of rotation such that it starts again in the direction of point A and repeat a complete step in reverse.
  • FIG. 3 This case is illustrated in FIG. 3 where the references 18 and 19 respectively designate the driving pulse which brought the rotor into the position of FIG. 2 and the catch-up pulse, and where the curve 20 schematically represents the angular position of the rotor as a function of time.
  • the catch-up pulse does not reach its goal, which is to replace a previous driving pulse whose energy was insufficient to turn the rotor correctly.
  • the detector circuit may not provide its detection signal if the rotor has locked in an intermediate position close to position B.
  • the driving pulse which follows that during which the rotor is locked is not interrupted, and the rotor returns to its starting position.
  • the control circuit sends a catch-up pulse, the effect of which can be the same as in the cases described above.
  • Patent application EP-A-62 273 state of the art according to art. 54 (3) (BE) describes, among other things, a method of controlling a stepping motor which solves this problem. This process consists in sending to the motor, after each driving pulse, a short pulse. If the rotor remains blocked in an intermediate position in response to a driving pulse, this short pulse unlocks it and brings it, depending on its polarity, to one or other of its rest positions.
  • each unlocking pulse A certain amount of electrical energy is consumed by each unlocking pulse.
  • the fact of applying an unlocking pulse after each driving pulse represents an electrical energy consumption which unnecessarily reduces the life of the battery supplying the device.
  • An object of the present invention is to provide a method of controlling a stepping motor which avoids this unnecessary consumption of electrical energy.
  • Another object of the present invention is to provide a device for controlling a stepping motor for the implementation of this method.
  • FIG. 4 is a block diagram of an electronic timepiece taken as a nonlimiting example of a device in which the method according to the invention is implemented.
  • This timepiece comprises a stepping motor 101 which drives the hands for displaying the hour, minute and second, not shown, by means of a gear train also not represented.
  • FIG. 4 shows a control circuit according to the invention designated by the reference 102, which supplies driving pulses to the motor 101 in response to a control signal delivered by a time base circuit 103 each time that the rotor of the motor must turn one step, that is to say every second in this example.
  • the time base circuit 103 conventionally comprises an oscillator circuit and a frequency divider circuit which are not shown.
  • the control circuit 102 consists, in this example, of a formatter circuit 104, a detector circuit 105 and a pulse generator 106.
  • the detector circuit 105 is connected to the motor 101 and provides at its output a detection signal if the rotor has not rotated in response to the previous driving pulse.
  • the training circuit 104 uses this detection signal in particular to determine the amount of electrical energy supplied to the motor by each driving pulse.
  • the pulse generator 106 supplies the forming circuit 104 with pulses which are transmitted to the motor 101 to unlock its rotor if necessary.
  • Figure 5 illustrates the operation of the circuit of Figure 4 in the case where the detector circuit 105 is of the same kind as that described in the patent US-A-4,212,156 mentioned above, that is to say a immediate detection circuit.
  • the diagrams designated by the references 103 to 106 represent the signals measured at the outputs of the circuits designated by the same references in FIG. 4.
  • the trainer circuit 104 delivers to the motor 101 a driving pulse of predetermined duration.
  • the detector circuit 105 only delivers a signal if the rotor of the motor 101 does not correctly complete its rotation in response to one of these driving pulses.
  • the trainer circuit 104 supplies the motor 101 with driving pulses of alternating polarities and of predetermined and equal durations.
  • the generator 106 which in this case is connected to the measurement circuit 105 by the link 107 drawn in dotted lines in FIG. 4, does not deliver a pulse either. This situation, which is the normal situation, is not illustrated.
  • FIG. 5 illustrates a case where the rotor does not correctly end its rotation in response to a driving pulse designated by the reference 111, having a duration which is, for example, the minimum duration that these driving pulses can take.
  • the detector circuit 105 delivers a signal 112 which indicates that the rotor has not finished its pitch.
  • This signal 112 causes the generator 106 to form a pulse 113.
  • This pulse 113 is transmitted by the forming circuit 104 to the motor 101 in the form of a pulse 114 having the opposite polarity to that of the driving impulse 111.
  • the signal 112 also causes the formation by the control circuit 104, after the pulse 114, of a pulse 115 having a duration greater than the duration of the pulse 111, and the same polarity as this pulse 111.
  • the pulse 114 unlocks it and causes it to return to its starting position.
  • the rotor is thus in a well-determined position when the forming circuit 104 delivers the pulse 115 intended to make it catch up with the step it has just missed.
  • the signal 112 also acts on the forming circuit 104 so that the latter increases the duration of the driving pulses which it then delivers.
  • a pulse of duration greater than the duration of the pulse 111, is represented in FIG. 5 with the reference 111 '. It obviously has the opposite polarity to that of pulse 111.
  • the detector circuit 105 delivers a signal such as the signal 112 each time the rotor does not finish its pitch correctly.
  • Each signal 112 causes the formation of an unblocking pulse such as the pulse 114 and of a catch-up pulse such as the pulse 115.
  • the forming circuit 104 delivers at least a predetermined number d 'motor pulses of the same duration as pulse 111'. When this number is reached, the forming circuit 104 reduces the duration of the driving pulses to that of the pulse 111.
  • the forming circuit 104 it would be possible to arrange the forming circuit 104 so that it delivers unblocking pulses having the same polarity as the previous driving pulse. These pulses would have the effect of unlocking the rotor and making it complete its rotation. It would then obviously no longer be necessary to provide the catch-up pulses such as the pulses 115.
  • Curve 4 in FIG. 1 schematically represents the torque created by an unlocking pulse having the same polarity as the driving pulse which brought the rotor into the position where it got stuck, between points D and E.
  • This torque decreases during the rotation it causes in the direction of point B and becomes less than the friction torque represented by curve 3. It could therefore happen that this impulse does not fully unlock the rotor.
  • the torque created by an unlocking pulse having the opposite polarity to that of the driving pulse in response to which the rotor is blocked which is represented diagrammatically by curve 5, increases during the rotation which it causes. in the direction of point A. This pulse therefore safely releases the rotor.
  • FIG. 6 illustrates an example of a control circuit of a stepping motor according to the invention, in which the detection of the rotation or of the non-rotation of the rotor takes place immediately after each driving pulse,. as in the circuit which is described in the patent US-A-4,212,156 already cited.
  • Figures 7a and 7b show signals measured at some points of the circuit of Figure 6 in two cases of operation of this circuit. Each diagram of these Figures 7a and 7b is designated by the reference to the point in Figure 6 where the signal it represents is measured, and the diagram designated by the reference 11 represents the voltage measured across the motor coil.
  • the motor coil 11 is conventionally connected in a bridge formed by 4 MOS transistors 21 to 24.
  • An oscillator 34 is connected to the input of a frequency divider 51 whose outputs 51a to 51e for example deliver signals having frequencies of 0.5 Hz, 1 Hz, 8 Hz, 16 Hz and 1'024 respectively Hz.
  • a control circuit 52 which includes doors, flip-flops and counters, the arrangement of which is described in detail in the patent US-A-4,212,156 already cited. Some of these doors use the signals supplied in particular by the outputs 51f of the divider 51 to form pulses having various durations.
  • the circuit 52 delivers a pulse on its output 52a or on its output 52b according to whether the output 51 a of divider 51 is in state "0" or in state "1". This pulse is selected from among the pulses of different durations mentioned above according to the state of an input 52e of circuit 52.
  • This input 52e is connected to the output of a circuit detecting the rotation of the rotor which will be described below.
  • Each pulse delivered by the output 52a of the circuit 52 is transmitted to the gates of the transistors 21 and 23 via an OR gate 53.
  • the coil 11 therefore receives a driving pulse which causes the passage, in this coil 11, of a current in the direction of the arrow 39.
  • each pulse delivered by the output 52b is transmitted to the gates of the transistors 22 and 24 via an OR gate 54, which causes the application to the coil 11 of a driving pulse having the reverse polarity of the previous one and the passage through this coil 11 of a current in the opposite direction to that of arrow 39.
  • the input 52e of the circuit 52 is in the logic state "0", and the pulses delivered by the outputs 52a or 52b have a short duration, of 5.1 milliseconds for example.
  • the output of the rotation detector, and therefore the input 52e of the circuit 52 pass to the state "1" about ten milliseconds after the start of this pulse motor.
  • the output 51 c of the divider 51 changes to the state "1", that is to say 62.5 milliseconds after the start of the driving pulse
  • the output 52a or 52b which delivered the last pulse delivers a new pulse, with a duration of, for example, 7.8 milliseconds.
  • This pulse called the catch-up pulse, is intended to cause the rotor to execute the step it has just missed.
  • the duration of the pulses delivered alternately by the outputs 52a and 52b in response to the transition to the state "1" of the signal at 1 Hz is increased to, for example, 7, 8 milliseconds. If the input 52e remains in the state "0" for all the predetermined time, that is to say if the rotor has rotated correctly, the duration of the pulses delivered by the outputs 52a and 52b is reduced to 5.1 milliseconds.
  • the circuit 52 also includes two outputs 52c and 52d which each deliver a pulse each time the output 52a or the output 52b delivers a normal pulse.
  • the pulse delivered by the output 52c has a duration of approximately ten milliseconds, and the pulse delivered by the output 52d has a duration equal to that of the pulses delivered by the output 52a or 52b.
  • the terminals of the coil 11 are connected to the inputs 55a and 55b of a circuit 55, which is also described in patent US-A-4,212,156.
  • This circuit 55 includes a differentiator circuit and transmission gates controlled by the signal at 0.5 Hz which is applied to an input 55c. According to the state of this signal at 0.5 Hz, the differentiator circuit is connected to one or the other of the terminals of the coil 11. This differentiator circuit is arranged so as to supply a pulse to the output 55d each time that the current in the coil 11 passes through a minimum.
  • This pulse is applied to a first input of an AND gate 56, a second and a third input of which are respectively connected to output 52c and, via an inverter 57, to output 52d of the control circuit 52.
  • the output of gate 56 is connected to the clock input CI of a type T flip-flop 58.
  • the output ⁇ of the flip-flop 58 is connected to a first input of an AND gate 59 whose second input is connected to output 52c of circuit 52 by means of an inverter 60.
  • gate 59 is connected to the clock input CI of a flip-flop 61, also of type T, the output Q of which is connected to the input 52e of circuit 52.
  • the reset inputs R of the flip-flops 58 and 61 are connected to the output 51 b of the divider 51 by means of an inverter 62.
  • the flip-flop 58 is therefore still in its rest state when the output 52c of the circuit 52 returns to the state "0". This change to state "0" causes the flip-flop 61 to topple over through the inverter 60 and the gate 59.
  • the input 52e of the circuit 52 which is connected to the output Q of the flip- flop 61, therefore goes to state "1", with the consequences described above.
  • the flip-flop 58 or the flip-flop 61 which has rocked as described above is returned to its rest state by the state "1" which is applied to its input R by the inverter 62 when the signal at 1 Hz returns to state "0".
  • the circuit of FIG. 6 comprises an AND gate 71 having two inputs connected respectively to the output Q of the flip-flop 61 and to the output 51 d of the divider 51.
  • the output of this gate 71 is connected to the clock input CI of a flip-flop 72, of type T.
  • the clock input CI of a flip-flop 73 is connected to the output 51e of the divider 51, and its input D is connected to the output Q of the flip-flop 72.
  • the output Q of the flip-flop 73 is connected to the first inputs of two AND gates 74 and 75.
  • the output 51 a of the divider 51 is connected to the second input of door 74 and, by means of an inverter 76, to the second input of door 75.
  • the outputs of these doors 74 and 75 are connected respectively at the second entrances of doors 53 and 54.
  • the reset flip-flop input R 72 is connected to the output of an AND gate 77 of which a first input is connected to the output of flip-flop 73 and of which a second input is connected to output 51 e of the divider 51 by means of an inverter 78.
  • the pulse delivered by the output Q of the flip-flop 73 is transmitted to the gates of the transistors 22 and 24 through the gates 75 and 54. This case is illustrated in FIG. 7b.
  • the pulse delivered by the output Q of the flip-flop 73 is transmitted to the gates of the transistors 21 and 23 through the gates 74 and 53.
  • this pulse delivered by the output Q of the flip-flop 73 causes the passage through the coil 11 of a current pulse in the opposite direction to that of the driving pulse which has failed to rotate. the rotor correctly.
  • this pulse of about a millisecond causes the rotor to be released and rotated in the direction which brings it back to its starting position.
  • the circuit 52 delivers the catch-up pulse described above, the rotor is in the position where this catch-up pulse causes it to advance with a single step, with safety.

Abstract

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.

Description

Un des objets de la présente invention concerne un procédé de commande d'un moteur pas-à-pas ayant une bobine, un rotor couplé magnétiquement à la bobine et des moyens pour amener ou maintenir le rotor dans au moins une position de repos déterminée en l'absence de courant dans la bobine, consistant à appliquer à la bobine une impulsion motrice ayant une première durée chaque fois que le rotor doit tourner d'un pas, à produire un signal de détection si le rotor n'a pas tourné correctement en réponse à l'impulsion motrice, à appliquer à la bobine une impulsion de rattrapage ayant une deuxième durée supérieure à la première durée en réponse au signal de détection, et à appliquer à la bobine, avant l'impulsion de rattrapage, une impulsion de déblocage ayant une troisième durée inférieure à la première durée destinée à provoquer la rotation du rotor jusqu'à la position de repos si celui-ci a été bloqué dans une autre position. Un autre objet de la présente invention concerne un dispositif de commande d'un moteur pas-à-pas ayant une bobine, un rotor couplé magnétiquement à la bobine et des moyens pour amener ou maintenir le rotor dans au moins une position de repos déterminée en l'absence de courant dans la bobine, comportant des moyens pour appliquer à la bobine une impulsion motrice ayant une première durée chaque fois que le rotor doit tourner d'un pas, des moyens pour produire un signal de détection si le rotor n'a pas tourné correctement en réponse à l'impulsion motrice, des moyens pour appliquer à la bobine une impulsion de rattrapage ayant une deuxième durée supérieure à la première durée en réponse au signal de détection, et des moyens pour appliquer à la bobine, avant l'impulsion de rattrapage, une impulsion de déblocage ayant une troisième durée inférieure à la première durée destinée à provoquer la rotation du rotor jusqu'à la position de repos si celui-ci a été bloqué dans une autre position.One of the objects of the present invention relates to a method of controlling a stepping motor having a coil, a rotor magnetically coupled to the coil and means for bringing or holding the rotor in at least one rest position determined in the absence of current in the coil, consisting in applying to the coil a driving pulse having a first duration each time the rotor must turn by one step, to produce a detection signal if the rotor has not turned correctly in response to the driving pulse, to apply a catch-up pulse to the coil having a second duration greater than the first duration in response to the detection signal, and to apply to the coil, before the catch-up pulse, a release pulse having a third duration less than the first duration intended to cause the rotation of the rotor to the rest position if the latter has been locked in another position. Another object of the present invention relates to a device for controlling a stepping motor having a coil, a rotor magnetically coupled to the coil and means for bringing or maintaining the rotor in at least one rest position determined in the absence of current in the coil, comprising means for applying a driving pulse having a first duration to the coil each time the rotor must turn one step, means for producing a detection signal if the rotor has not not turned correctly in response to the driving pulse, means for applying to the coil a catch-up pulse having a second duration greater than the first duration in response to the detection signal, and means for applying to the coil, before the catch-up pulse, an unlocking pulse having a third duration less than the first duration intended to cause the rotation of the rotor to the rest position if the latter has been locked in another position.

L'énergie électrique nécessaire à l'entraîment des éléments mécaniques reliés à un moteur pas-à-pas, qui peuvent être, par exemple, les éléments d'affichage des informations horaires d'une pièce d'horlogerie électronique constitués par des aiguilles et/ou des disques, lui est généralement fournie par un circuit de commande qui délivre une impulsion motrice chaque fois qu'il doit avancer d'un pas.The electrical energy required to drive the mechanical elements connected to a stepping motor, which can be, for example, the elements for displaying the time information of an electronic timepiece constituted by hands and / or discs, it is generally supplied to it by a control circuit which delivers a driving impulse each time it has to advance one step.

Une diminution importante de cette énergie électrique consommée par le moteur peut être obtenue en prévoyant dans le circuit de commande un circuit qui ajuste l'énergie des impulsions motrices au minimum correspondant à la charge mécanique réelle entraînée par le moteur.A significant reduction in this electrical energy consumed by the motor can be obtained by providing in the control circuit a circuit which adjusts the energy of the driving pulses to the minimum corresponding to the actual mechanical load driven by the motor.

Il existe différents types de circuits de mesure de cette charge mécanique réelle et d'ajustement de l'énergie des impulsions motrices.There are different types of circuits for measuring this real mechanical load and for adjusting the energy of the driving pulses.

Le brevet US-A-4,212,156, par exemple, décrit un circuit de commande dans lequel la durée de chaque impulsion motrice est déjà déterminée avant qu'elle ne commence. Un circuit détecteur mesure le temps qui s'écoule entre la fin de chaque impulsion motrice et l'apparition du premier minimum du courant induit dans la bobine par les oscillations du rotor autour de sa position d'équilibre.US-A-4,212,156, for example, describes a control circuit in which the duration of each driving pulse is already determined before it begins. A detector circuit measures the time which elapses between the end of each driving pulse and the appearance of the first minimum of the current induced in the coil by the oscillations of the rotor around its equilibrium position.

Si ce temps est faible, cela indique que la charge entraînée par le rotor pendant cette impulsion motrice était également faible, et donc que le rotor a certainement terminé son pas. Le circuit de commande ne modifie pas la durée des impulsions motrices suivantes, ou, selon les cas, diminue cette durée.If this time is low, this indicates that the load driven by the rotor during this driving pulse was also low, and therefore that the rotor has certainly finished its pitch. The control circuit does not modify the duration of the following driving pulses, or, as the case may be, decreases this duration.

Si par contre ce temps est long, cela indique que la charge entraînée par le rotor était importante, et que le rotor n'a peut-être pas tourné en réponse à cette impulsion motrice. Le circuit de commande envoie alors une impulsion de rattrapage de longue durée et de même polarité que l'impulsion motrice qui vient de se terminer et augmente la durée de l'impulsion motrice suivante. Dans de tels circuits, la détection de la rotation ou de la non-rotation du rotor est donc effectuée immédiatement, ou presque, après chaque impulsion motrice. Ces circuits seront appelés circuits à détection immédiate dans la suite de cette description.If, however, this time is long, this indicates that the load driven by the rotor was high, and that the rotor may not have rotated in response to this driving impulse. The control circuit then sends a catch-up pulse of long duration and of the same polarity as the driving pulse which has just ended and increases the duration of the following driving pulse. In such circuits, the detection of the rotation or of the non-rotation of the rotor is therefore carried out immediately, or almost, after each driving pulse. These circuits will be called immediate detection circuits in the remainder of this description.

Le brevet US-A-4,300,223 décrit un autre genre de circuit de commande dans lequel la durée de chaque impulsion motrice est prédéterminée. Dans ce circuit, un circuit détecteur mesure l'intensité du courant circulant dans la bobine du moteur deux millisecondes environ après le début de chaque impulsion motrice. Si cette intensité est inférieure à une valeur prédéterminée, cela indique que le rotor se trouve dans la position correcte pour tourner en réponse à cette impulsion motrice, et donc qu'il a tourné en réponse à l'impulsion motrice précédente. Si cette intensité est supérieure à la valeur prédéterminée, cela indique que le rotor ne se trouve pas dans la position correcte, et donc qu'il n'a pas tourné en réponse à l'impulsion motrice précédente. Dans ce cas, le circuit de commande interrompt alors l'impulsion motrice en cours, envoie au moteur une impulsion de rattrapage de même polarité que l'impulsion motrice précédente, puis envoie à nouveau l'impulsion motrice normale.Patent US-A-4,300,223 describes another kind of control circuit in which the duration of each driving pulse is predetermined. In this circuit, a detector circuit measures the intensity of the current flowing in the motor coil about two milliseconds after the start of each driving pulse. If this intensity is less than a predetermined value, this indicates that the rotor is in the correct position to turn in response to this driving pulse, and therefore that it has rotated in response to the previous driving pulse. If this intensity is greater than the predetermined value, this indicates that the rotor is not in the correct position, and therefore that it has not rotated in response to the previous driving pulse. In this case, the control circuit then interrupts the current driving pulse, sends the motor a catch-up pulse of the same polarity as the previous driving pulse, then sends the normal driving pulse again.

La demande de brevet EP-A-22 270 décrit un autre circuit de commande dans lequel la durée de chaque impulsion motrice est prédéterminée. A la fin de chaque impulsion motrice, la bobine du moteur est mise en circuit ouvert, et la tension induite par la rotation du rotor est mesurée. Si cette tension est supérieure à une valeur prédéterminée, cela signifie que le rotor a correctement tourné en réponse à cette impulsion motrice. Si par contre, cette tension est inférieure à cette valeur prédéterminée, cela signifie que le rotor ne se trouvait pas dans la position qu'il aurait dû occuper au début de cette impulsion motrice, et donc qu'il n'a pas tourné en réponse à l'impulsion motrice précédente ni en réponse à la présente impulsion motrice. Le circuit de commande applique alors au moteur deux impulsions de rattrapage ayant une longue durée et destinées à faire effectuer au rotor les rotations qu'il na pas effectuées en réponse à ces deux impulsions motrices.Patent application EP-A-22 270 describes another control circuit in which the duration of each driving pulse is predetermined. At the end of each driving pulse, the motor coil is placed in open circuit, and the voltage induced by the rotation of the rotor is measured. If this voltage is greater than a predetermined value, it means that the rotor has turned correctly in response to this driving pulse. If, on the other hand, this tension is lower than this predetermined value, it means that the rotor was not in the position which it should have occupied at the beginning of this driving impulse, and therefore that it did not turn in response at the previous driving impulse nor in response to this driving impulse. The control circuit then applies to the motor two take-up pulses having a long duration and intended to cause the rotor to perform the rotations which it has not carried out in response to these two driving pulses.

La demande de brevet EP-A-24 737 décrit un circuit du même genre que le précédent, mais dans lequel la détection de la rotation, ou non, du rotor est faite en déterminant si l'intégrale de la tension induite dans la bobine du moteur pendant une période déterminée dépasse, ou non, une valeur prédéterminée.Patent application EP-A-24 737 describes a circuit of the same kind as the previous one, but in which the detection of the rotation, or not, of the rotor is made by determining whether the integral of the voltage induced in the coil of the engine for a specified period exceeds or does not exceed a predetermined value.

Dans les circuit décrits par les trois derniers documents mentionnés ci-dessus, la détection de la rotation ou de la non-rotation du rotor en réponse à une impulsion motrice est donc effectuée longtemps après la fin de cette impulsion motrice. Ces circuits seront appelés circuits à détection différée dans la suite de cette description.In the circuits described by the last three documents mentioned above, the detection of the rotation or of the non-rotation of the rotor in response to a driving pulse is therefore carried out long after the end of this driving pulse. These circuits will be called deferred detection circuits in the remainder of this description.

Il faut noter que, quel que soit le genre de circuit de commande et d'ajustement utilisé, la durée des impulsions motrices est généralement inférieure au temps mis par le rotor pour effectuer son pas. L'énergie électrique fournie au moteur par chaque impulsion motrice est, en principe, suffisante pour que le rotor termine son pas grâce à l'énergie cinétique qu'il a accumulée et à un couple de positionnement qui tend à le ramener ou à le maintenir, en l'absence de courant dans la bobine, dans une position de repos, ou d'équilibre, stable et déterminée.It should be noted that, whatever the type of control and adjustment circuit used, the duration of the driving pulses is generally less than the time taken by the rotor to perform its pitch. The electric energy supplied to the motor by each driving pulse is, in principle, sufficient for the rotor to end its step thanks to the kinetic energy which it has accumulated and to a positioning torque which tends to bring it back or to maintain it , in the absence of current in the coil, in a rest, or equilibrium, stable and determined position.

Ce couple de positionnement est créé par une forme particulière donnée aux pièces polaires qui entourent le rotor du moteur, ou par un ou plusieurs aimants de positionnement.This positioning torque is created by a particular shape given to the pole pieces which surround the rotor of the motor, or by one or more positioning magnets.

La courbe 1 de la figure 1 illustre schématiquement la variation de ce couple de positionnement en fonction de l'angle a de rotation du rotor, entre deux positions d'équilibre stable correspondant aux points A et B. Lorsque ce couple est positif, il tend à faire tourner le rotor dans le sens croissant de l'angle a et, lorsqu'il est négatif, il tend à le faire tourner dans le sens décroissant de cet angle a.Curve 1 in FIG. 1 schematically illustrates the variation of this positioning torque as a function of the angle of rotation of the rotor, between two positions of stable equilibrium corresponding to points A and B. When this torque is positive, it tends rotating the rotor in the increasing direction of the angle a and, when it is negative, it tends to rotate it in the decreasing direction of this angle a.

Dans la plupart des moteurs utilisés actuellement dans les pièces d'horlogerie, le rotor tourne par pas de 180 degrés, ce qui signifie qu'il a deux positions d'équilibre stable par tour. Dans d'autres types de moteur, le pas du rotor correspond à une rotation de 360 degrés, ce qui signifie que le rotor n'a qu'une position d'équilibre stable.In most motors currently used in timepieces, the rotor rotates in 180 degree steps, which means that it has two stable equilibrium positions per revolution. In other types of motor, the rotor pitch corresponds to a rotation of 360 degrees, which means that the rotor has only a stable equilibrium position.

La période du couple de positionnement est égale à l'angle qui sépare deux positions d'équilibre stable successives du rotor. Il existe donc une position du rotor, représentée par le ' point C de la figure 1, et qui correspond approximativement à une rotation d'un demi-pas, pour laquelle ce couple s'annule et change de signe. Ce point C correspond donc à une position d'équilibre instable du rotor.The period of the positioning torque is equal to the angle which separates two successive stable equilibrium positions of the rotor. There is therefore a position of the rotor, represented by the 'point C in Figure 1, and which corresponds approximately to a rotation of half a step, for which this couple is canceled and changes sign. This point C therefore corresponds to an unstable equilibrium position of the rotor.

La charge mécanique entraînée par le moteur est constituée pour une grande partie par le couple résistant dû au frottement inévitable des pivots du rotor et des roues dentées qu'il entraîne dans leurs paliers, ainsi que par le frottement des dents de ces roues entre elles. Ce couple de frottement est représenté schématiquement par les courbes 2 et 3 de la figure 1.The mechanical load driven by the motor is made up for a large part by the resistant torque due to the inevitable friction of the pivots of the rotor and the toothed wheels which it drives in their bearings, as well as by the friction of the teeth of these wheels between them. This friction torque is represented diagrammatically by curves 2 and 3 in FIG. 1.

Autour du point C d'équilibre instable mentionné ci-dessus, il existe une zone, délimitée par les points D et E, dans laquelle le couple de frottement est supérieur au couple de positionnement.Around the unstable equilibrium point C mentioned above, there is a zone, delimited by points D and E, in which the friction torque is greater than the positioning torque.

Si l'énergie fournie au rotor par une impulsion motrice est suffisante pour que le rotor atteigne le point D mais n'est pas suffisante pour qu'il atteigne et dépasse le point E, le rotor reste donc bloqué dans une position intermédiaire qui peut être située n'importe où entre ces points D et E.If the energy supplied to the rotor by a driving pulse is sufficient for the rotor to reach point D but is not sufficient for it to reach and exceed point E, the rotor therefore remains locked in an intermediate position which can be located anywhere between these points D and E.

La figure 2 illustre schématiquement un moteur du type le plus couramment utilisé dans les pièces d'horlogerie électroniques dans la situation où son rotor est bloqué dans une telle position intermédiaire. Cette figure 2 montre la bobine 11, deux pièces polaires 12 et 13 qui font partie du stator du moteur, et l'aimant 14 du rotor.FIG. 2 schematically illustrates an engine of the type most commonly used in electronic timepieces in the situation where its rotor is locked in such an intermediate position. This figure 2 shows the coil 11, two pole pieces 12 and 13 which are part of the stator of the motor, and the magnet 14 of the rotor.

L'axe d'aimantation de cet aimant 14 est représenté par la flèche 15 qui est dirigée de son pôle sud vers son pôle nord.The magnetization axis of this magnet 14 is represented by the arrow 15 which is directed from its south pole towards its north pole.

Le couple de positionnement du rotor est créé, dans cet exemple, par les encoches 16 et 17 ménagées respectivement dans les pièces polaires 12 et 13.The positioning torque of the rotor is created, in this example, by the notches 16 and 17 formed respectively in the pole pieces 12 and 13.

En fonctionnement normal, le circuit de commande du moteur, non représenté dans cette figure 2, délivre des impulsions motrices à la bobine 11 en réponse à des impulsions de commande fournies, par exemple, par un circuit de base de temps chaque fois que le rotor doit avancer d'un pas.In normal operation, the motor control circuit, not shown in this FIG. 2, delivers driving pulses to the coil 11 in response to control pulses supplied, for example, by a time base circuit each time the rotor must take a step forward.

Toutes les explications qui vont suivre seront données en prenant pour exemple un tel moteur. Toutefois, l'homme du métier constatera qu'elles s'appliquent sans difficulté à n'importe quel type de moteur pas-à-pas.All the explanations which will follow will be given using such an engine as an example. However, those skilled in the art will find that they apply without difficulty to any type of stepping motor.

Pour ces explications, on admettra que le point A de la figure 1 correspond à la position du rotor où l'axe d'aimantation de son aimant est représenté par la flèche 15' dessinée en pointillés à la figure 2, et que le rotor a été amené à la position représentée par la flèche 15 par une impulsion motrice désignée par la référence 18 à la figure 3 et appliquée à la bobine 11 de manière que la pièce polaire 12 joue le rôle d'un pôle magnétique sud et que la pièce polaire 13 joue le rôle d'un pôle magnétique nord. L'énergie fournie au moteur par cette impulsion a été suffisante pour que le rotor atteigne une position située au delà du point D de la figure 1, mais, pour une raison quelconque, elle a été insuffisante pour que ce rotor dépasse la position correspondant au point E. Le rotor est donc resté bloqué dans la position intermédiaire représentée à la figure 2.For these explanations, it will be assumed that point A in FIG. 1 corresponds to the position of the rotor where the magnetization axis of its magnet is represented by the arrow 15 'drawn in dotted lines in FIG. 2, and that the rotor has has been brought to the position represented by the arrow 15 by a driving pulse designated by the reference 18 in FIG. 3 and applied to the coil 11 so that the pole piece 12 plays the role of a south magnetic pole and that the pole piece 13 plays the role of a north magnetic pole. The energy supplied to the motor by this pulse was sufficient for the rotor to reach a position situated beyond point D in FIG. 1, but, for some reason, it was insufficient for this rotor to exceed the position corresponding to the point E. The rotor therefore remained locked in the intermediate position shown in FIG. 2.

Si cette situation se présente avec un circuit de commande à détection immédiate du genre de celui qui est décrit par le brevet US-A- 4,212,156 cité ci-dessus, ce circuit de commande envoie au moteur une impulsion de rattrapage dès qu'il a détecté que le rotor n'a pas terminé son pas. Cette impulsion de rattrapage, qui est désignée par la référence 19 à la figure 3, a la même polarité que l'impulsion motrice 18 et une durée déterminée pour faire tourner le rotor d'un pas complet, du point A au point B. Comme le rotor est, dans ce cas, dans une position située entre les points A et B, cette impulsion de rattrapage n'est pas encore terminée lorsque le rotor atteint un point B' qui est le point où le couple de positionnement et le couple créé par le courant dans la bobine s'annulent. Le rotor oscille autour de ce point B', et à l'instant où l'impulsion de rattrapage se termine, il est très possible qu'il ait une vitesse et une direction de rotation telles qu'il reparte en direction du point A et refasse un pas complet en sens inverse.If this situation arises with an immediate detection control circuit of the kind described by US-A-4,212,156 cited above, this control circuit sends the motor a catch-up pulse as soon as it detects that the rotor has not finished its pitch. This catch-up pulse, which is designated by the reference 19 in FIG. 3, has the same polarity as the driving pulse 18 and a determined duration for turning the rotor by a full step, from point A to point B. As the rotor is, in this case, in a position located between points A and B, this catch-up pulse is not yet finished when the rotor reaches a point B 'which is the point where the positioning torque and the torque created by the current in the coil cancel each other. The rotor oscillates around this point B ', and at the moment when the catch-up pulse ends, it is very possible that it has a speed and a direction of rotation such that it starts again in the direction of point A and repeat a complete step in reverse.

Ce cas est illustré à la figure 3 où les références 18 et 19 désignent respectivement l'impulsion motrice qui a amené le rotor dans la position de la figure 2 et l'impulsion de rattrapage, et où la courbe 20 représente schématiquement la position angulaire du rotor en fonction du temps.This case is illustrated in FIG. 3 where the references 18 and 19 respectively designate the driving pulse which brought the rotor into the position of FIG. 2 and the catch-up pulse, and where the curve 20 schematically represents the angular position of the rotor as a function of time.

Dans un tel cas, l'impulsion de rattrapage n'atteint pas son but, qui est de remplacer une impulsion motrice précédente dont l'énergie a été insuffisante pour faire tourner le rotor correctement.In such a case, the catch-up pulse does not reach its goal, which is to replace a previous driving pulse whose energy was insufficient to turn the rotor correctly.

La même situation peut se présenter si le rotor n'est pas vraiment resté bloqué à la fin d'une impulsion motrice, mais si sa rotation a été simplement retardée, pour une raison ou une autre. Dans ce cas également l'impulsion de rattrapage envoyée par le circuit de commande provoque des oscillations du rotor autour du point B', et le rotor peut très bien être renvoyé au point A à la fin de cette impulsion de rattrapage.The same situation can arise if the rotor is not really blocked at the end of a driving impulse, but if its rotation has been simply delayed, for one reason or another. In this case also the catch-up pulse sent by the control circuit causes the rotor to oscillate around point B ', and the rotor can very well be returned to point A at the end of this catch-up pulse.

Dans le cas où le circuit de commande du moteur est à détection différée, comme celui qui est décrit par le brevet US-A- 4,300,223 déjà cité, le circuit détecteur peut ne pas fournir son signal de détection si le rotor s'est bloqué dans une position intermédiaire proche de la position B. L'impulsion motrice qui suit celle pendant laquelle le rotor s'est bloqué n'est alors pas interrompue, et le rotor retourne à sa position de départ.In the case where the motor control circuit is delayed detection, such as that described by the patent US-A-4,300,223 already cited, the detector circuit may not provide its detection signal if the rotor has locked in an intermediate position close to position B. The driving pulse which follows that during which the rotor is locked is not interrupted, and the rotor returns to its starting position.

Si la position où le rotor est bloqué est telle que le circuit détecteur réagit à cette situation, le circuit de commande envoie une impulsion de rattrapage dont l'effet peut être le même que dans les cas décrits ci-dessus.If the position where the rotor is locked is such that the detector circuit reacts to this situation, the control circuit sends a catch-up pulse, the effect of which can be the same as in the cases described above.

En résumé, on voit que si le rotor du moteur reste bloqué dans une position intermédiaire, les circuits de commande connus décrits ci-dessus comprenant un circuit détecteur de la non-rotation du rotor ne garantissent pas un fonctionnement parfait du moteur dans tous les cas.In summary, it can be seen that if the motor rotor remains locked in an intermediate position, the known control circuits described above comprising a circuit for detecting the non-rotation of the rotor do not guarantee perfect operation of the motor in all cases. .

La demande de brevet EP-A-62 273 état de la technique selon l'art. 54 (3) (BE) décrit, entre autres, un procédé de commande d'un moteur pas-à-pas qui résout ce problème. Ce procédé consiste à envoyer au moteur, après chaque impulsion motrice, une impulsion courte. Si le rotor reste bloqué dans une position intermédiaire en réponse à une impulsion motrice, cette impulsion courte le débloque et le ramène, selon sa polarité, à l'une ou l'autre de ses positions de repos.Patent application EP-A-62 273 state of the art according to art. 54 (3) (BE) describes, among other things, a method of controlling a stepping motor which solves this problem. This process consists in sending to the motor, after each driving pulse, a short pulse. If the rotor remains blocked in an intermediate position in response to a driving pulse, this short pulse unlocks it and brings it, depending on its polarity, to one or other of its rest positions.

Une certaine quantité d'énergie électrique est consommée par chaque impulsion de déblocage. Comme les cas où le rotor reste bloqué dans une position intermédiaire sont assez rares, le fait d'appliquer une impulsion de déblocage après chaque impulsion motrice représente une consommation d'énergie électrique qui diminue inutilement la durée de vie de la pile alimentant le dispositif.A certain amount of electrical energy is consumed by each unlocking pulse. As the cases where the rotor remains locked in an intermediate position are quite rare, the fact of applying an unlocking pulse after each driving pulse represents an electrical energy consumption which unnecessarily reduces the life of the battery supplying the device.

Un but de la présente invention est de proposer un procédé de commande d'un moteur pas-à-pas qui évite cette consommation inutile d'énergie électrique.An object of the present invention is to provide a method of controlling a stepping motor which avoids this unnecessary consumption of electrical energy.

Un autre but de la présente invention est de proposer un dispositif de commande d'un moteur pas-à-pas pour la mise en oeuvre de ce procédé.Another object of the present invention is to provide a device for controlling a stepping motor for the implementation of this method.

Ces buts sont atteints par le procédé et par le dispositif de commande revendiqués.These aims are achieved by the method and by the claimed control device.

L'invention va maintenant être décrite en détail à l'aide du dessin dans lequel:

  • - la figure 1, déjà citée, représente la variation du couple de positionnement d'un moteur pas-à-pas en fonction de l'angle de rotation du rotor entre deux positions d'équilibre stable;
  • - la figure 2, déjà citée, illustre schématiquement un moteur pas-à-pas, du type le plus fréquemment utilisé dans les pièces d'horlogerie électroniques, dont le rotor est bloqué dans une position intermédiaire;
  • - la figure 3, déjà citée, illustre l'effet d'une impulsion de rattrapage appliquée à un moteur pas-à-pas dont le rotor est bloqué dans la position illustrée par la figure 2;
  • - la figure 4 est un schéma bloc d'un circuit permettant la mise en oeuvre du procédé selon l'invention;
  • - la figure 5 illustre des signaux mesurés en quelques points du circuit de la figure 4;
  • - la figure 6 représente le schéma détaillé d'une première forme d'exécution d'un circuit de commande selon l'invention; et
  • - les figures 7a et 7b dont des diagrammes représentant des signaux mesurés en quelques points du circuit de la figure 6.
The invention will now be described in detail using the drawing in which:
  • - Figure 1, already cited, shows the variation of the positioning torque of a stepping motor as a function of the angle of rotation of the rotor between two stable equilibrium positions;
  • - Figure 2, already cited, schematically illustrates a stepping motor, of the type most frequently used in electronic timepieces, whose rotor is locked in an intermediate position;
  • - Figure 3, already cited, illustrates the effect of a catch-up pulse applied to a stepping motor whose rotor is locked in the position illustrated in Figure 2;
  • - Figure 4 is a block diagram of a circuit for implementing the method according to the invention;
  • - Figure 5 illustrates signals measured at some points of the circuit of Figure 4;
  • - Figure 6 shows the detailed diagram of a first embodiment of a control circuit according to the invention; and
  • - Figures 7a and 7b including diagrams representing signals measured at some points of the circuit of Figure 6.

La figure 4 est un schéma bloc d'une pièce d'horlogerie électronique prise comme exemple non limitatif de dispositif dans lequel le procédé selon l'invention est mis en oeuvre.FIG. 4 is a block diagram of an electronic timepiece taken as a nonlimiting example of a device in which the method according to the invention is implemented.

Cette pièce d'horlogerie comporte un moteur pas-à-pas 101 qui entraîne des aiguilles d'affichage de l'heure, de la minute et de la seconde, non représentées, par l'intermédiaire d'un train d'engrenage également non représenté.This timepiece comprises a stepping motor 101 which drives the hands for displaying the hour, minute and second, not shown, by means of a gear train also not represented.

La figure 4 montre un circuit de commande selon l'invention désigné par la référence 102, qui fournit des impulsions motrices au moteur 101 en réponse à un signal de commande délivré par un circuit de base de temps 103 chaque fois que le rotor du moteur doit tourner d'un pas, c'est-à-dire chaque seconde dans cet exemple. Le circuit de base de temps 103 comporte, de manière classique, un circuit oscillateur et un circuit diviseur de fréquence qui ne sont pas représentes.FIG. 4 shows a control circuit according to the invention designated by the reference 102, which supplies driving pulses to the motor 101 in response to a control signal delivered by a time base circuit 103 each time that the rotor of the motor must turn one step, that is to say every second in this example. The time base circuit 103 conventionally comprises an oscillator circuit and a frequency divider circuit which are not shown.

Le circuit de commande 102 se compose, dans cet exemple, d'un circuit formateur 104, d'un circuit détecteur 105 et d'un générateur d'impulsions 106.The control circuit 102 consists, in this example, of a formatter circuit 104, a detector circuit 105 and a pulse generator 106.

Le circuit détecteur 105 est relié au moteur 101 et fournit à sa sortie un signal de détection si le rotor n'a pas tourné en réponse à l'impulsion motrice précédente.The detector circuit 105 is connected to the motor 101 and provides at its output a detection signal if the rotor has not rotated in response to the previous driving pulse.

Le circuit formateur 104 utilise ce signal de détection notamment pour déterminer la quantité d'énergie électrique fournie au moteur par chaque impulsion motrice.The training circuit 104 uses this detection signal in particular to determine the amount of electrical energy supplied to the motor by each driving pulse.

Dans des conditions qui seront précisées ci-dessous, le générateur d'impulsions 106 fournit au circuit formateur 104 des impulsions qui sont transmises au moteur 101 pour débloquer son rotor si nécessaire.Under conditions which will be specified below, the pulse generator 106 supplies the forming circuit 104 with pulses which are transmitted to the motor 101 to unlock its rotor if necessary.

La figure 5 illustre le fonctionnement du circuit de la figure 4 dans le cas où le circuit détecteur 105 est du même genre que celui qui est décrit dans le brevet US-A-4,212,156 mentionné ci-dessus, c'est-à-dire un circuit à détection immédiate.Figure 5 illustrates the operation of the circuit of Figure 4 in the case where the detector circuit 105 is of the same kind as that described in the patent US-A-4,212,156 mentioned above, that is to say a immediate detection circuit.

Dans cette figure 5, les diagrammes désignés par les références 103 à 106 représentent les signaux mesurés aux sorties des circuits désignés par les mêmes références dans la figure 4.In this FIG. 5, the diagrams designated by the references 103 to 106 represent the signals measured at the outputs of the circuits designated by the same references in FIG. 4.

Chaque fois que le circuit de base de temps 103 fournit un signal de commande, le circuit formateur 104 délivre au moteur 101 une impulsion motrice de durée prédéterminée. Le circuit détecteur 105 ne délivre un signal que si le rotor du moteur 101 ne termine pas correctement sa rotation en réponse à une de ces impulsions motrices.Each time the time base circuit 103 supplies a control signal, the trainer circuit 104 delivers to the motor 101 a driving pulse of predetermined duration. The detector circuit 105 only delivers a signal if the rotor of the motor 101 does not correctly complete its rotation in response to one of these driving pulses.

Tant que le circuit détecteur 105 ne délivre pas de signal, le circuit formateur 104 délivre au moteur 101 des impulsions motrices de polarités alternées et de durées prédéterminées et égales. Le générateur 106, qui est dans ce cas relié au circuit de mesure 105 par la liaison 107 dessinée en pointillés à la figure 4, ne délivre pas non plus d'impulsion. Cette situation, qui est la situation normale, n'est pas illustrée.As long as the detector circuit 105 does not deliver a signal, the trainer circuit 104 supplies the motor 101 with driving pulses of alternating polarities and of predetermined and equal durations. The generator 106, which in this case is connected to the measurement circuit 105 by the link 107 drawn in dotted lines in FIG. 4, does not deliver a pulse either. This situation, which is the normal situation, is not illustrated.

La figure 5 illustre un cas où le rotor ne termine pas correctement sa rotation en réponse à une impulsion motrice désignée par la référence 111, ayant une durée qui est, par exemple, la durée minimum que peuvent prendre ces impulsions motrices.FIG. 5 illustrates a case where the rotor does not correctly end its rotation in response to a driving pulse designated by the reference 111, having a duration which is, for example, the minimum duration that these driving pulses can take.

Un certain temps après le début de l'impulsion motrice 111, le circuit détecteur 105 délivre un signal 112 qui indique que le rotor n'a pas terminé son pas. Ce signal 112 provoque la formation par le générateur 106 d'une impulsion 113. Cette impulsion 113, de faible durée, est transmise par le circuit formateur 104 au moteur 101 sous la forme d'une impulsion 114 ayant la polarité inverse de celle de l'impulsion motrice 111.A certain time after the start of the driving pulse 111, the detector circuit 105 delivers a signal 112 which indicates that the rotor has not finished its pitch. This signal 112 causes the generator 106 to form a pulse 113. This pulse 113, of short duration, is transmitted by the forming circuit 104 to the motor 101 in the form of a pulse 114 having the opposite polarity to that of the driving impulse 111.

Le signal 112 provoque également la formation par le circuit de commande 104, après l'impulsion 114, d'une impulsion 115 ayant une durée plus grande que la durée de l'impulsion 111, et la même polarité que cette impulsion 111.The signal 112 also causes the formation by the control circuit 104, after the pulse 114, of a pulse 115 having a duration greater than the duration of the pulse 111, and the same polarity as this pulse 111.

Si le rotor n'a pas terminé son pas parce qu'il est resté bloqué dans une position intermédiaire telle que celle qui est représentée à la figure 2, l'impulsion 114 le débloque et le fait revenir à sa position de départ. Le rotor se trouve ainsi dans une position bien déterminée au moment où le circuit formateur 104 délivre l'impulsion 115 destinée à lui faire rattrapper le pas qu'il vient de rater.If the rotor has not finished its pitch because it has been blocked in an intermediate position such as that shown in FIG. 2, the pulse 114 unlocks it and causes it to return to its starting position. The rotor is thus in a well-determined position when the forming circuit 104 delivers the pulse 115 intended to make it catch up with the step it has just missed.

Si le rotor est revenu à sa position de départ avant que l'impulsion 114 soit délivrée, cette dernière n'a aucun effet, et l'impulsion de rattrapage 115 provoque normalement la rotation du rotor.If the rotor has returned to its starting position before the pulse 114 is delivered, the latter has no effect, and the catch-up pulse 115 normally causes the rotor to rotate.

Si enfin le rotor a simplement été retardé et qu'il termine son pas après que le circuit détecteur 105 a délivré le signal 112, les impulsions de déblocage 114 et de rattrapage 115 n'ont pas d'effet.If finally the rotor has simply been delayed and it finishes its pitch after the detector circuit 105 has delivered the signal 112, the unlocking 114 and catch-up 115 pulses have no effect.

Le signal 112 agit également sur le circuit formateur 104 de manière que ce dernier augmente la durée des impulsions motrices qu'il délivre ensuite. Une telle impulsion, de durée supérieure à la durée de l'impulsion 111, est représentée à la figure 5 avec la référence 111'. Elle a évidemment la polarité inverse de celle de l'impulsion 111.The signal 112 also acts on the forming circuit 104 so that the latter increases the duration of the driving pulses which it then delivers. Such a pulse, of duration greater than the duration of the pulse 111, is represented in FIG. 5 with the reference 111 '. It obviously has the opposite polarity to that of pulse 111.

Il est évident que, quelle que soit la durée des impulsions motrices 111 ou 111', le circuit détecteur 105 délivre un signal tel que le signal 112 chaque fois que le rotor ne termine pas son pas correctement. Chaque signal 112 provoque la formation d'une impulsion de déblocage telle que l'impulsion 114 et d'une impulsion de rattrapage telle que l'impulsion 115. Après chacun de ces signaux 112, le circuit formateur 104 délivre au moins un nombre prédéterminé d'impulsions motrices de même durée que l'impulsion 111'. Lorsque ce nombre est atteint, le circuit formateur 104 ramène la durée des impulsions motrices à celle de l'impulsion 111.It is obvious that, whatever the duration of the driving pulses 111 or 111 ′, the detector circuit 105 delivers a signal such as the signal 112 each time the rotor does not finish its pitch correctly. Each signal 112 causes the formation of an unblocking pulse such as the pulse 114 and of a catch-up pulse such as the pulse 115. After each of these signals 112, the forming circuit 104 delivers at least a predetermined number d 'motor pulses of the same duration as pulse 111'. When this number is reached, the forming circuit 104 reduces the duration of the driving pulses to that of the pulse 111.

Dans le cas décrit ci-dessus, il serait possible d'agencer le circuit formateur 104 de manière qu'il délivre des impulsions de déblocage ayant la même polarité que l'impulsion motrice précédente. Ces impulsions auraient pour effet de débloquer le rotor et de lui faire terminer sa rotation. Il ne serait évidemment alors plus nécessaire de prévoir les impulsions de rattrapage telles que les impulsions 115.In the case described above, it would be possible to arrange the forming circuit 104 so that it delivers unblocking pulses having the same polarity as the previous driving pulse. These pulses would have the effect of unlocking the rotor and making it complete its rotation. It would then obviously no longer be necessary to provide the catch-up pulses such as the pulses 115.

Il est cependant préférable, pour des raisons de sécurité de fonctionnement, de faire fonctionner le circuit de la manière décrite à l'aide de cette figure 5.However, for operational safety reasons, it is preferable to operate the circuit as described using this figure 5.

La courbe 4 de la figure 1 représente schématiquement le couple créé par une impulsion de déblocage ayant la même polarité que l'impulsion motrice qui a amené le rotor dans la position où il s'est bloqué, entre les points D et E. Ce couple diminue pendant la rotation qu'il provoque en direction du point B et devient inférieur au couple de frottement représenté par la courbe 3. Il pourrait donc arriver que cette impulsion ne débloque pas complètement le rotor. Par contre, le couple créé par une impulsion de déblocage ayant la polarité inverse de celle de l'impulsion motrice en réponse à laquelle le rotor s'est bloqué, qui est représenté schématiquement par la courbe 5, augmente pendant la rotation qu'il provoque en direction du point A. Cette impulsion provoque donc avec sécurité le déblocage du rotor.Curve 4 in FIG. 1 schematically represents the torque created by an unlocking pulse having the same polarity as the driving pulse which brought the rotor into the position where it got stuck, between points D and E. This torque decreases during the rotation it causes in the direction of point B and becomes less than the friction torque represented by curve 3. It could therefore happen that this impulse does not fully unlock the rotor. On the other hand, the torque created by an unlocking pulse having the opposite polarity to that of the driving pulse in response to which the rotor is blocked, which is represented diagrammatically by curve 5, increases during the rotation which it causes. in the direction of point A. This pulse therefore safely releases the rotor.

La figure 6 illustre un exemple de circuit de commande d'un moteur pas-à-pas selon l'invention, dans lequel la détection de la rotation ou de la non-rotation du rotor a lieu immédiatement après chaque impulsion motrice, . comme dans le circuit qui est décrit dans le brevet US-A- 4,212,156 déjà cité. Les figures 7a et 7b montrent des signaux mesurés en quelques points du circuit de la figure 6 dans deux cas de fonctionnement de ce circuit. Chaque diagramme de ces figures 7a et 7b est désigné par la référence du point de la figure 6 où le signal qu'il représente est mesuré, et le diagramme désigné par la référence 11 représente la tension mesurée aux bornes de la bobine du moteur.FIG. 6 illustrates an example of a control circuit of a stepping motor according to the invention, in which the detection of the rotation or of the non-rotation of the rotor takes place immediately after each driving pulse,. as in the circuit which is described in the patent US-A-4,212,156 already cited. Figures 7a and 7b show signals measured at some points of the circuit of Figure 6 in two cases of operation of this circuit. Each diagram of these Figures 7a and 7b is designated by the reference to the point in Figure 6 where the signal it represents is measured, and the diagram designated by the reference 11 represents the voltage measured across the motor coil.

La bobine 11 du moteur est branchée de manière classique dans un pont formé par 4 transistors MOS 21 à 24.The motor coil 11 is conventionally connected in a bridge formed by 4 MOS transistors 21 to 24.

Un oscillateur 34 est relié à l'entrée d'un diviseur de fréquence 51 dont les sorties 51a à à 51e délivrent par exemple des signaux ayant respectivement des fréquences de 0,5 Hz, 1 Hz, 8 Hz, 16 Hz et 1'024 Hz. D'autres sorties, désignées ensembles par la référence 51f, délivrent des signaux ayant d'autres fréquences, qui ne seront pas détaillés ici.An oscillator 34 is connected to the input of a frequency divider 51 whose outputs 51a to 51e for example deliver signals having frequencies of 0.5 Hz, 1 Hz, 8 Hz, 16 Hz and 1'024 respectively Hz. Other outputs, designated together by the reference 51f, deliver signals having other frequencies, which will not be detailed here.

Tous ces signaux sont appliqués aux entrées d'un circuit de commande 52 qui comprend des portes, des flip-flops et des compteurs dont l'agencement est décrit en détail dans le brevet US-A-4,212,156 déjà cité. Certaines de ces portes utilisent les signaux fournis notamment par les sorties 51f du diviseur 51 pour former des impulsions ayant diverses durées. Chaque fois que le signal à 1 Hz délivré par la sortie 51 b du diviseur 51 passe à l'état "1 ", par exemple, le circuit 52 délivre une impulsion sur sa sortie 52a ou sur sa sortie 52b selon que la sortie 51 a du diviseur 51 est à l'état "0" ou à t'état "1". Cette impulsion est sélectionnée parmi les impulsions de durées différentes mentionnées ci-dessus en fonction de l'état d'une entrée 52e du circuit 52. Cette entrée 52e est reliée à la sortie d'un circuit détecteur de la rotation du rotor qui sera décrit ci-dessous.All these signals are applied to the inputs of a control circuit 52 which includes doors, flip-flops and counters, the arrangement of which is described in detail in the patent US-A-4,212,156 already cited. Some of these doors use the signals supplied in particular by the outputs 51f of the divider 51 to form pulses having various durations. Each time the signal at 1 Hz delivered by the output 51 b of the divider 51 passes to the state "1", for example, the circuit 52 delivers a pulse on its output 52a or on its output 52b according to whether the output 51 a of divider 51 is in state "0" or in state "1". This pulse is selected from among the pulses of different durations mentioned above according to the state of an input 52e of circuit 52. This input 52e is connected to the output of a circuit detecting the rotation of the rotor which will be described below.

Chaque impulsion délivrée par la sortie 52a du circuit 52 est transmise aux grilles des transistors 21 et 23 par l'intermédiaire d'une porte OU 53. La bobine 11 reçoit donc une impulsion motrice qui provoque le passage, dans cette bobine 11, d'un courant dans le sens de la flèche 39. De même, chaque impulsion délivrée par la sortie 52b est transmise aux grilles des transistors 22 et 24 par l'intermédiaire d'une porte OU 54, ce qui provoque l'application à la bobine 11 d'une impulsion motrice ayant la polarité inverse de la précédente et le passage dans cette bobine 11 d'un courant dans le sens inverse de celui de la flèche 39.Each pulse delivered by the output 52a of the circuit 52 is transmitted to the gates of the transistors 21 and 23 via an OR gate 53. The coil 11 therefore receives a driving pulse which causes the passage, in this coil 11, of a current in the direction of the arrow 39. Similarly, each pulse delivered by the output 52b is transmitted to the gates of the transistors 22 and 24 via an OR gate 54, which causes the application to the coil 11 of a driving pulse having the reverse polarity of the previous one and the passage through this coil 11 of a current in the opposite direction to that of arrow 39.

Normalement, l'entrée 52e du circuit 52 est à l'état logique "0", et les impulsions délivrées par les sorties 52a ou 52b ont une durée faible, de 5,1 millisecondes par exemple. Lorsque le rotor ne termine pas correctement son pas en réponse à une impulsion motrice, la sortie du détecteur de rotation, et donc l'entrée 52e du circuit 52, passent à l'état "1" dix millisecondes environ après le début de cette impulsion motrice. Lorsque, après ce passage à l'état "1", la sortie 51 c du diviseur 51 passe à l'état "1", c'est-à-dire 62,5 millisecondes après le début de l'impulsion motrice, la sortie 52a ou 52b qui a délivré la dernière impulsion délivre une nouvelle impulsion, d'une durée de, par exemple, 7,8 millisecondes. Cette impulsion, dite impulsion de rattrapage, est destinée à faire exécuter au rotor le pas qu'il vient de rater.Normally, the input 52e of the circuit 52 is in the logic state "0", and the pulses delivered by the outputs 52a or 52b have a short duration, of 5.1 milliseconds for example. When the rotor does not correctly complete its pitch in response to a driving pulse, the output of the rotation detector, and therefore the input 52e of the circuit 52, pass to the state "1" about ten milliseconds after the start of this pulse motor. When, after this transition to the state "1", the output 51 c of the divider 51 changes to the state "1", that is to say 62.5 milliseconds after the start of the driving pulse, the output 52a or 52b which delivered the last pulse delivers a new pulse, with a duration of, for example, 7.8 milliseconds. This pulse, called the catch-up pulse, is intended to cause the rotor to execute the step it has just missed.

A partir de ce moment, et pour un temps prédéterminé, la durée des impulsions délivrées alternativement par les sorties 52a et 52b en réponse au passage à l'état "1" du signal à 1 Hz, est augmentée à, par exemple, 7,8 millisecondes. Si l'entrée 52e reste à l'état "0" pendant tout le temps prédéterminé, c'est-à-dire si le rotor a tourné correctement, la durée des impulsions délivrées par les sorties 52a et 52b est ramenée à 5,1 millisecondes.From this moment, and for a predetermined time, the duration of the pulses delivered alternately by the outputs 52a and 52b in response to the transition to the state "1" of the signal at 1 Hz, is increased to, for example, 7, 8 milliseconds. If the input 52e remains in the state "0" for all the predetermined time, that is to say if the rotor has rotated correctly, the duration of the pulses delivered by the outputs 52a and 52b is reduced to 5.1 milliseconds.

Le circuit 52 comporte également deux sorties 52c et 52d qui délivrent chacune une impulsion chaque fois que la sortie 52a ou la sortie 52b délivre une impulsion normale. L'impulsion délivrée par la sortie 52c a une durée de dix millisecondes environ, et l'impulsion délivrée par la sortie 52d a une durée égale à celle des impulsions délivrées par la sortie 52a ou 52b.The circuit 52 also includes two outputs 52c and 52d which each deliver a pulse each time the output 52a or the output 52b delivers a normal pulse. The pulse delivered by the output 52c has a duration of approximately ten milliseconds, and the pulse delivered by the output 52d has a duration equal to that of the pulses delivered by the output 52a or 52b.

Les bornes de la bobine 11 sont reliées aux entrées 55a et 55b d'un circuit 55, qui est également décrit dans le brevet US-A-4,212,156. Ce circuit 55 comprend un circuit différenciateur et des portes de transmission commandées par le signal à 0,5 Hz qui est appliqué à une entrée 55c. Selon l'état de ce signal à 0,5 Hz, le circuit différenciateur est relié à l'une ou l'autre des bornes de la bobine 11. Ce circuit différenciateur est agencé de manière à fournir une impulsion à la sortie 55d chaque fois que le courant dans la bobine 11 passe par un minimum.The terminals of the coil 11 are connected to the inputs 55a and 55b of a circuit 55, which is also described in patent US-A-4,212,156. This circuit 55 includes a differentiator circuit and transmission gates controlled by the signal at 0.5 Hz which is applied to an input 55c. According to the state of this signal at 0.5 Hz, the differentiator circuit is connected to one or the other of the terminals of the coil 11. This differentiator circuit is arranged so as to supply a pulse to the output 55d each time that the current in the coil 11 passes through a minimum.

Cette impulsion est appliquée à une première entrée d'une porte ET 56 dont une deuxième et une troisième entrée sont respectivement reliées à la sortie 52c et, par l'intermédiaire d'un inverseur 57, à la sortie 52d du circuit de commande 52. La sortie de la porte 56 est reliée à l'entrée d'horloge CI d'un flip-flop 58 de type T.This pulse is applied to a first input of an AND gate 56, a second and a third input of which are respectively connected to output 52c and, via an inverter 57, to output 52d of the control circuit 52. The output of gate 56 is connected to the clock input CI of a type T flip-flop 58.

La sortie Ö du flip-flop 58 est reliée à une première entrée d'une porte ET 59 dont la deuxième entrée est reliée à la sortie 52c du circuit 52 par l'intermédiaire d'un inverseur 60.The output Ö of the flip-flop 58 is connected to a first input of an AND gate 59 whose second input is connected to output 52c of circuit 52 by means of an inverter 60.

La sortie de la porte 59 est reliée à l'entrée d'horloge CI d'un flip-flop 61, également de type T, dont la sortie Q est reliée à l'entrée 52e du circuit 52.The output of gate 59 is connected to the clock input CI of a flip-flop 61, also of type T, the output Q of which is connected to the input 52e of circuit 52.

Les entrées R de remise à zéro des flip-flops 58 et 61 sont reliées à la sortie 51 b du diviseur 51 par l'intermédiaire d'un inverseur 62.The reset inputs R of the flip-flops 58 and 61 are connected to the output 51 b of the divider 51 by means of an inverter 62.

Le circuit 55, les portes 56 et 59, les inverseurs 57 et 60 et les flip-flops 58 et 61 se retrouvent, avec d'autres références, dans le brevet US-A-4,212,156, et forment un détecteur de rotation du rotor qui fonctionne de la manière suivante:The circuit 55, the doors 56 and 59, the inverters 57 and 60 and the flip-flops 58 and 61 are found, with other references, in patent US-A-4,212,156, and form a rotor rotation detector which works as follows:

L'impulsion fournie normalement par la sortie 55d du circuit 55 pendant chaque impulsion motrice au moment où le courant dans la bobine 11 passe, de manière bien connue, par un minimum est bloquée par la porte 56 dont l'entrée reliée à l'inverseur 57 est à l'état "0" à ce moment.The pulse normally supplied by the output 55d of the circuit 55 during each driving pulse at the moment when the current in the coil 11 passes, in a well known manner, through a minimum is blocked by the gate 56 whose input connected to the inverter 57 is in state "0" at this time.

Si le rotor termine correctement son pas, le courant induit dans la bobine 11 par les oscillations qu'il exécute après la fin de l'impulsion motrice présente un minimum à un instant situé moins de dix millisecondes après le début de cette impulsion motrice. L'impulsion fournie à cet instant par la sortie 55d du circuit 55 passe par la porte 56 et fait basculer le flip-flop 58, dont la sortie Q passe à l'état "0". Cet état "0" bloque la porte 59. Le flip-flop 61, dont la sortie Q constitue la sortie du détecteur de rotation, ne peut donc pas basculer lorque la sortie 52c du circuit 52 passe à l'état "0" dix millisecondes environ après le début de l'impulsion motrice. L'entrée 52e du circuit 52 reste donc à l'état "0" avec les conséquences décrites ci-dessus. Ce cas est illustré par la figure 7a.If the rotor completes its pitch correctly, the current induced in the coil 11 by the oscillations it executes after the end of the driving pulse has a minimum at an instant situated less than ten milliseconds after the start of this driving pulse. The pulse supplied at this instant by the output 55d of the circuit 55 passes through the gate 56 and causes the flip-flop 58 to switch, the output Q of which goes to the state "0". This state "0" blocks the gate 59. The flip-flop 61, the output Q of which constitutes the output of the rotation detector, cannot therefore switch when the output 52c of the circuit 52 goes to the state "0" ten milliseconds approximately after the start of the motor impulse. The 52e input of the circuit 52 therefore remains in the "0" state with the consequences described above. This case is illustrated in Figure 7a.

Si par contre le rotor ne tourne pas correctement en réponse à une impulsion motrice, à cause d'une charge mécanique trop élevée, le minimum du courant induit dans la bobine 11 par les oscillations du rotor se produit plus de dix millisecondes après le début de l'impulsion motrice. Le flip-flop 58 est donc encore dans son état de repos au moment où la sortie 52c du circuit 52 repasse à l'état "0". Ce passage à l'état "0" provoque le basculement du flip-flop 61 par l'intermédiaire de l'inverseur 60 et de la porte 59. L'entrée 52e du circuit 52, qui est reliée à la sortie Q du flip-flop 61, passe donc à l'état "1", avec les conséquences décrites ci-dessus.If, on the other hand, the rotor does not rotate correctly in response to a driving impulse, because of too high a mechanical load, the minimum of the current induced in the coil 11 by the oscillations of the rotor occurs more than ten milliseconds after the start of the driving impulse. The flip-flop 58 is therefore still in its rest state when the output 52c of the circuit 52 returns to the state "0". This change to state "0" causes the flip-flop 61 to topple over through the inverter 60 and the gate 59. The input 52e of the circuit 52, which is connected to the output Q of the flip- flop 61, therefore goes to state "1", with the consequences described above.

Cette situation se présente également dans le cas où le rotor reste bloqué dans une position telle que celle qui est représentée à la figure 2. Dans ce cas, la sortie 55d du circuit 55 ne produit pas d'impulsion, car le courant circulant dans la bobine 11 ne présente pas de minimum. Ce cas est illustré par la figure 7b.This situation also arises in the case where the rotor remains locked in a position such as that which is represented in FIG. 2. In this case, the output 55d of the circuit 55 does not produce a pulse, since the current flowing in the coil 11 has no minimum. This case is illustrated in Figure 7b.

Le flip-flop 58 ou le flip-flop 61 qui a basculé comme décrit ci-dessus est remis dans son état de repos par l'état "1" qui est appliqué à son entrée R par l'inverseur 62 lorsque le signal à 1 Hz repasse à l'état "0".The flip-flop 58 or the flip-flop 61 which has rocked as described above is returned to its rest state by the state "1" which is applied to its input R by the inverter 62 when the signal at 1 Hz returns to state "0".

En plus de ces circuits, qui se retrouvent dans le brevet US-A-4,212,156 avec d'autres références, le circuit de la figure 6 comporte une porte ET 71 ayant deux entrées reliées respectivement à la sortie Q du flip-flop 61 et à la sortie 51 d du diviseur 51. La sortie de cette porte 71 est reliée à l'entrée d'horloge CI d'un flip-flop 72, de type T. L'entrée d'horloge CI d'un flip-flop 73, de type D, est reliée à la sortie 51e du diviseur 51, et son entrée D est reliée à la sortie Q du flip-flop 72. La sortie Q du flip-flop 73 est reliée aux premières entrées de deux portes ET 74 et 75. La sortie 51 a du diviseur 51 est reliée à la deuxième entrée de la porte 74 et, par l'intermédiaire d'un inverseur 76, à la deuxième entrée de la porte 75. Les sorties de ces portes 74 et 75 sont reliées respectivement aux deuxièmes entrées des portes 53 et 54.In addition to these circuits, which are found in patent US-A-4,212,156 with other references, the circuit of FIG. 6 comprises an AND gate 71 having two inputs connected respectively to the output Q of the flip-flop 61 and to the output 51 d of the divider 51. The output of this gate 71 is connected to the clock input CI of a flip-flop 72, of type T. The clock input CI of a flip-flop 73 , of type D, is connected to the output 51e of the divider 51, and its input D is connected to the output Q of the flip-flop 72. The output Q of the flip-flop 73 is connected to the first inputs of two AND gates 74 and 75. The output 51 a of the divider 51 is connected to the second input of door 74 and, by means of an inverter 76, to the second input of door 75. The outputs of these doors 74 and 75 are connected respectively at the second entrances of doors 53 and 54.

L'entrée R de remise à zéro du flip-flop 72 est reliée à la sortie d'une porte ET 77 dont une première entrée est reliée à la sortie du flip-flop 73 et dont une deuxième entrée est reliée à la sortie 51 e du diviseur 51 par l'intermédiaire d'un inverseur 78.The reset flip-flop input R 72 is connected to the output of an AND gate 77 of which a first input is connected to the output of flip-flop 73 and of which a second input is connected to output 51 e of the divider 51 by means of an inverter 78.

Ces circuits forment un générateur d'impulsions qui joue le rôle du générateur 106 de la figure 4 et qui fonctionne de la manière suivante:

  • Si le rotor ne tourne pas correctement en réponse à une impulsion motrice, la sortie Q du flip-flop 61 passe à l'état "1" de la manière décrite ci-dessus, et la sortie de la porte 71 passe également à l'état "1" au moment où la sortie 51 d passe elle-même à l'état "1", c'est-à-dire trente millisecondes environ après le début de l'impulsion motrice. Le flip-flop 72 bascule donc à ce moment, et sa sortie Q passe à l'état "1 ".
These circuits form a pulse generator which plays the role of the generator 106 in FIG. 4 and which operates as follows:
  • If the rotor does not rotate correctly in response to a driving impulse, the output Q of the flip-flop 61 changes to state "1" as described above, and the output of gate 71 also changes to state "1" when the output 51 d itself goes to state "1", that is to say about thirty milliseconds after the start of the driving pulse. The flip-flop 72 therefore switches at this time, and its output Q changes to state "1".

Lorsque l'entrée CI du flip-flop 73 passe également à l'état "1" une demi-milliseconde environ plus tard, ce flip-flop 73 bascule également et sa sortie Q passe à l'état "1". Lorsque la sortie 51 e du diviseur 51 repasse à l'état "0", une autre demi-milliseconde plus tard, l'entrée R de remise à zéro du flip-flop 72 passe à l'état "1", et sa sortie Q passe à l'état "0". Lorsque, encore une demi-milliseconde plus tard, la sortie 51e du diviseur 51 repasse à l'état "1", la sortie Q du flip-flop 73 repasse à l'état "0". Cette sortie Q du flip-flop 73 délivre donc une impulsion d'une durée de une milliseconde environ qui commence trente millisecondes environ après le début de l'impulsion motrice. Cette impulsion correspond à l'impulsion 113 de la figure 5.When the CI input of flip-flop 73 also changes to state "1" about half a millisecond later, this flip-flop 73 also switches and its output Q changes to state "1". When the output 51 e of the divider 51 returns to the state "0", another half-millisecond later, the input R for resetting to zero of the flip-flop 72 passes to the state "1", and its output Q goes to state "0". When, even half a millisecond later, the output 51e of the divider 51 returns to the state "1", the output Q of the flip-flop 73 returns to the state "0". This output Q of the flip-flop 73 therefore delivers a pulse with a duration of around one millisecond which begins around thirty milliseconds after the start of the driving pulse. This pulse corresponds to the pulse 113 of FIG. 5.

Si la sortie 51 a du diviseur 51 est à l'état "0", c'est-à-dire si c'est la sortie 52a du circuit de commande 52 qui a délivré l'impulsion en réponse à laquelle le rotor n'a pas tourné correctement, l'impulsion délivrée par la sortie Q du flip-flop 73 est transmise aux grilles des transistors 22 et 24 à travers les portes 75 et 54. Ce cas est illustré par la figure 7b.If the output 51 a of the divider 51 is in the state "0", that is to say if it is the output 52 a of the control circuit 52 which delivered the pulse in response to which the rotor does not has not turned correctly, the pulse delivered by the output Q of the flip-flop 73 is transmitted to the gates of the transistors 22 and 24 through the gates 75 and 54. This case is illustrated in FIG. 7b.

Si au contraire la sortie 51 a du diviseur 51 est à l'état "1", c'est-à-dire si c'est la sortie 52b du circuit de commande 52 qui a délivré l'impulsion en réponse à laquelle le rotor n'a pas tourné correctement, l'impulsion délivrée par la sortie Q du flip-flop 73 est transmise aux grilles des transistors 21 et 23 à travers les portes 74 et 53.If on the contrary the output 51 a of the divider 51 is in the state "1", that is to say if it is the output 52b of the control circuit 52 which delivered the pulse in response to which the rotor has not turned correctly, the pulse delivered by the output Q of the flip-flop 73 is transmitted to the gates of the transistors 21 and 23 through the gates 74 and 53.

Dans les deux cas, cette impulsion délivrée par la sortie Q du flip-flop 73 provoque le passage dans la bobine 11 d'une impulsion de courant dans le sens inverse de celui de l'impulsion motrice qui n'a pas réussi à faire tourner le rotor correctement.In both cases, this pulse delivered by the output Q of the flip-flop 73 causes the passage through the coil 11 of a current pulse in the opposite direction to that of the driving pulse which has failed to rotate. the rotor correctly.

Si le rotor est resté bloqué dans une position intermédiaire en réponse à cette impulsion motrice, cette impulsion de une milliseconde environ provoque le déblocage du rotor et sa rotation dans le sens qui le ramème à sa position de départ. Lorsque, environ trente millisecondes plus tard, le circuit 52 délivre l'impulsion de rattrapage décrite ci-dessus, le rotor se trouve dans la position où cette impulsion de rattrapage provoque son avance d'un seul pas, avec sécurite.If the rotor has remained blocked in an intermediate position in response to this driving pulse, this pulse of about a millisecond causes the rotor to be released and rotated in the direction which brings it back to its starting position. When, approximately thirty milliseconds later, the circuit 52 delivers the catch-up pulse described above, the rotor is in the position where this catch-up pulse causes it to advance with a single step, with safety.

Claims (4)

1. Method for controlling a stepping motor having a winding, a rotor comprising a permanent magnet (14) magnetically coupled to the winding (11) and means (16, 17) for bringing to or maintaining the rotor in a rest position in the absence of current in the winding (11) consisting in applying to the winding (11) a drive pulse (111, 111') having a first duration each time the rotor is to turn through a step, producing a detection signal (112) if the rotor has not turned correctly in response to the drive pulse (111, 111'), applying to the winding (11) a catch-up pulse (115) having a second duration greater than the first duration in response to the detection signal (112) and applying to the winding (11) before the catch-up pulse (115) a release pulse (114) having a third duration less than the first duration intended to cause rotation of the rotor to the rest position if the rotor has been blocked in another position, furthermore consisting in applying the release pulse (114) solely in response to the detection signal (112).
2. Method according to claim 1 characterized by the fact that it consists in applying the release pulse (114) to the winding (11) with polarity inverted from that of the immediately preceding drive pulse (111, 111').
3. Control arrangement for a stepping motor having a winding (11), a rotor comprising a permanent magnet (14) magnetically coupled to the winding (11) and means (16, 17) for bringing to or maintaining the rotor in a rest position in the absence of current in the winding (11), the arrangement comprising means (34, 51, 52) for applying to the winding (11) a drive pulse (111, 111') having a first duration each time the rotor is to turn through a step, means (55 to 62) for producing a detection signal (112) if the rotor has not turned correctly in response to the drive pulse (111, 111'), means for applying to the winding a catch-up pulse (115) having a second duration greater than the first duration in response to the detection signal (112) and means (71 to 78) for applying to the winding (11) a release pulse (114) having a third duration less than the first duration intended to cause rotation of the rotor to the rest position if the rotor has been blocked in another position, in which the means (71 to 78) for applying the release pulse (114) include means (71) for producing a control signal in response to the detection signal (112) and means (72, 73, 77, 78) for producing the release pulse (114) solely in response to the control signal.
4. Arrangement according to claim 3 characterized by the fact that each release pulse (114) is applied to the winding (11) with polarity inverted from that of the immediately preceding drive pulse (111, 11T).
EP83810453A 1982-10-13 1983-10-05 Method and device for controlling a step motor Expired EP0108711B1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
CH5974/82 1982-10-13
CH597482A CH649187GA3 (en) 1982-10-13 1982-10-13

Publications (2)

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EP0108711A1 EP0108711A1 (en) 1984-05-16
EP0108711B1 true EP0108711B1 (en) 1987-06-10

Family

ID=4302369

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Application Number Title Priority Date Filing Date
EP83810453A Expired EP0108711B1 (en) 1982-10-13 1983-10-05 Method and device for controlling a step motor

Country Status (5)

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US (1) US4507599A (en)
EP (1) EP0108711B1 (en)
JP (1) JPS5989596A (en)
CH (1) CH649187GA3 (en)
DE (1) DE3372022D1 (en)

Families Citing this family (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4598240A (en) * 1984-08-29 1986-07-01 Eaton Corporation Self synchronous motor sensor switching arrangement
FR2668866B1 (en) * 1990-11-07 1992-12-31 Ebauchesfabrik Eta Ag METHOD FOR CONTROLLING A STEPPER MOTOR AND DEVICE FOR CARRYING OUT SAID METHOD.
JP3256342B2 (en) * 1993-08-04 2002-02-12 ティーアールダブリュ オートモーティブ ジャパン株式会社 Stepping motor step-out detection device
KR20110002204A (en) * 2009-07-01 2011-01-07 삼성전자주식회사 Motor controlling apparatus and method for controlling thereof

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0022270A1 (en) * 1979-07-09 1981-01-14 Societe Suisse Pour L'industrie Horlogere Management Services S.A. Position detector for a stepping motor
EP0024737A1 (en) * 1979-09-04 1981-03-11 Societe Suisse Pour L'industrie Horlogere Management Services S.A. Detector for the movement of a stepping motor
EP0082821A1 (en) * 1981-12-23 1983-06-29 Eta SA Fabriques d'Ebauches Electronic watch provided with detection means for the passage across a reference position

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2007409B (en) * 1977-09-02 1982-04-15 Ebauches Sa Driving device especially for a timepiece
JPS5477169A (en) * 1977-12-02 1979-06-20 Seiko Instr & Electronics Ltd Electronic watch
FR2450527A1 (en) * 1979-03-01 1980-09-26 Suisse Horlogerie NON REVERSIBLE STEPPER MOTOR
CH644983GA3 (en) * 1981-03-31 1984-09-14

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0022270A1 (en) * 1979-07-09 1981-01-14 Societe Suisse Pour L'industrie Horlogere Management Services S.A. Position detector for a stepping motor
EP0024737A1 (en) * 1979-09-04 1981-03-11 Societe Suisse Pour L'industrie Horlogere Management Services S.A. Detector for the movement of a stepping motor
EP0082821A1 (en) * 1981-12-23 1983-06-29 Eta SA Fabriques d'Ebauches Electronic watch provided with detection means for the passage across a reference position

Also Published As

Publication number Publication date
CH649187GA3 (en) 1985-05-15
JPS5989596A (en) 1984-05-23
JPH0116119B2 (en) 1989-03-22
US4507599A (en) 1985-03-26
EP0108711A1 (en) 1984-05-16
DE3372022D1 (en) 1987-07-16

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