EP3629104B1 - Mechanical timepiece comprising an electronic device for regulating the time keeping precision of the timepiece - Google Patents

Description

Technical area

The present invention relates to a timepiece comprising a mechanical oscillator, the average frequency of which is synchronized to a reference frequency determined by an auxiliary electronic oscillator. To this end, the timepiece comprises a regulating device capable of correcting any time drift in the operation of the mechanical oscillator, which rates the rate of the mechanical movement which incorporates it.

• un mécanisme indicateur d'au moins une donnée temporelle,
• un résonateur mécanique susceptible d'osciller autour d'une position neutre correspondant à son état d'énergie potentielle minimale, et
• un dispositif d'entretien du résonateur mécanique formant avec ce résonateur mécanique un oscillateur mécanique qui est agencé pour cadencer la marche du mécanisme indicateur.

More particularly, the timepiece is provided with a mechanical movement which comprises:

• a mechanism indicating at least one temporal datum,
• a mechanical resonator capable of oscillating around a neutral position corresponding to its state of minimum potential energy, and
• a device for maintaining the mechanical resonator forming with this mechanical resonator a mechanical oscillator which is arranged to rate the operation of the indicator mechanism.

• un capteur pour pouvoir détecter un nombre de périodes ou d'alternances dans l'oscillation du résonateur mécanique dans une plage de fonctionnement utile de l'oscillateur mécanique,
• un oscillateur auxiliaire,
• un dispositif de freinage qui est agencé pour pouvoir appliquer momentanément une force de freinage au résonateur mécanique, et
• un circuit de régulation comprenant un dispositif de mesure agencé pour pouvoir mesurer, sur la base d'un signal de détection fourni par le capteur, une dérive temporelle de l'oscillateur mécanique relativement à l'oscillateur auxiliaire, ce circuit de régulation étant agencé pour déterminer si la dérive temporelle mesurée correspond à au moins une certaine avance ou à au moins un certain retard et pour pouvoir, si c'est le cas, générer un signal de commande qui active sélectivement le dispositif de freinage en fonction de la dérive temporelle mesurée, de manière à engendrer au moins une impulsion de freinage qui est appliquée au résonateur mécanique pour corriger au moins partiellement cette dérive temporelle.

This timepiece is further provided with a regulating device designed to regulate the average frequency of the mechanical oscillator and comprising:

• a sensor to be able to detect a number of periods or alternations in the oscillation of the mechanical resonator in a useful operating range of the mechanical oscillator,
• an auxiliary oscillator,
• a braking device which is arranged to be able to momentarily apply a braking force to the mechanical resonator, and
• a regulation circuit comprising a measuring device arranged to be able to measure, on the basis of a detection signal supplied by the sensor, a time drift of the mechanical oscillator relative to the auxiliary oscillator, this regulation circuit being arranged to determining whether the measured time drift corresponds to at least a certain advance or at least a certain delay and in order to be able, if so, to generate a control signal which selectively activates the braking device as a function of the measured time drift , so as to generate at least one braking pulse which is applied to the mechanical resonator to at least partially correct this time drift.

Technological background

Timepieces of the type defined above in the field of the invention have recently been disclosed in patent applications. CH 713306 A2 , EP 3339982 A1 and EP 1 241 538 A1 .

The timepiece disclosed in the document CH 713306 A2 comprises a mechanical movement, provided with a mechanical oscillator, and an electromagnetic system formed of at least one magnet mounted on the balance of a mechanical oscillator and of a coil carried by a support of the balance. The electromagnetic system is part of a regulation device intended to regulate the average frequency of the mechanical oscillator in the case where this oscillator has a positive time drift relative to an auxiliary oscillator, for example a crystal oscillator, as in the case where it presents a negative time drift. After observing that a braking pulse, applied to the resonator forming the mechanical oscillator in an alternation of its oscillation, generates a negative phase shift when it occurs before the resonator passes through its neutral position and a positive phase shift when it occurs after the resonator has passed through its neutral position, this document proposes a solution in which the time drift is measured and the movement oscillation of the resonator is observed so that the regulation device can selectively apply one or more braking pulses to it, respectively via one or more short-circuits of the coil, in one or more respective first half-waves (located before the passage of the resonator by its neutral position) when the measured time drift corresponds to at least a certain advance and in one or more respective second half-waves (located after the resonator has passed through its neutral position) when the time drift corresponds to at least one some delay. To do this, the electronic circuit of the regulation device comprises a time counter or a timer making it possible to determine, on the basis of detections of voltage pulses induced in the coil, whether an induced voltage pulse occurs in a first half-wave. or in a second half-cycle so as to be able to selectively apply the braking pulses as indicated above. The regulation method implemented in this document, although remarkable, requires a relatively complex electronic circuit which therefore consumes a certain electrical energy which is taken from the mechanical oscillator, which tends to reduce its oscillation amplitude and therefore the duration of the oscillation. normal operation for a certain mechanical energy stored in a barrel of the mechanical movement.

The timepiece disclosed in the document EP 3339982 A1 is remarkable for the system designed to generate mechanical braking pulses applied to the balance of the mechanical oscillator. However, the regulation process is similar to that of the previous document. A sensor is provided which is designed to be able to detect the passages of the resonator through its neutral position. On the basis of the knowledge of the setpoint period for the mechanical oscillator and of the detections made by the sensor, a control logic circuit determines with the aid of a time counter the instants at which the braking pulses must be triggered for that they intervene selectively before or after the passage of the mechanical resonator by its neutral position in corresponding vibrations, that is to say to apply the mechanical braking pulses either in first half-cycles or in two second half-vibrations. In this case too, a relatively complex electronic circuit is necessary.

Summary of the invention

The main aim of the present invention is to simplify the electronic circuit of the device for regulating the average frequency of a mechanical oscillator, by providing an alternative to the regulating devices of the prior art, described in the technological background, which is easy to implement in a timepiece.

To this end, the invention relates to a timepiece as defined above in the field of the invention and which is characterized in that the regulation circuit comprises a device generating at least one frequency which is arranged in so as to be able to generate a periodic digital signal at a frequency F _SUP ; and by the fact that the regulation circuit is designed to be able to supply, when it determines a time drift corresponding to at least a certain delay in the operation of the timepiece, momentarily to the braking device a first control signal for activate this braking device so that the braking device generates, during a first correction period, a series of periodic braking pulses which are applied to the mechanical resonator at the frequency F _SUP . This frequency F _SUP and the duration of the first correction period are provided and the braking device is arranged so that the series of periodic braking pulses at the frequency F _SUP can generate, during the first correction period, a synchronous phase in which the mechanical oscillator is synchronized to a correction frequency which is greater than a reference frequency F0c provided for the mechanical oscillator.

In a main embodiment, the frequency F _SUP is included in a first range of values extending between (M + 1) / M and (M + 2) / M, inclusive, multiplied by a frequency Fz (N) equal twice a reference frequency F0c for the mechanical oscillator divided by a positive integer N, that is to say [(M + 1) / M] · Fz (N) <F _SUP = <[(M + 2) / M ] · Fz (N) with Fz (N) = 2 · F0c / N, M being equal to one hundred times two to the power K with K equal to a positive integer greater than zero and less than thirteen, that is to say 0 <K < 13 and M = 100.2 ^K , and N being expected to be less than M divided by thirty, i.e. N <M / 30.

In the case where the regulation circuit determines a time drift corresponding to at least a certain advance in the operation of the timepiece, two general embodiments are provided. In the first general embodiment, the regulation circuit is arranged to be able, after having detected said at least a certain advance, to stop the mechanical oscillator and then to temporarily block the mechanical resonator so as to at least partially correct said at least one. certain advance detected.

In the second general embodiment, said device for generating at least one frequency is a device for generating frequencies arranged so as to be able, moreover, to generate a periodic digital signal at a frequency F _INF and the regulation circuit is arranged to be able to supply , when it determines a time drift corresponding to at least a certain advance in the operation of the timepiece, momentarily to the braking device a second control signal to activate this braking device so that the braking device generates, during a second correction period, a series of periodic braking pulses which are applied to the mechanical resonator at the frequency F _INF . This frequency F _INF and the duration of the second correction period are provided and the braking device is arranged so that the series of periodic braking pulses at the frequency F _INF can generate, during the second correction period, a phase synchronous in which the mechanical oscillator is synchronized on a correction frequency which is lower than the reference frequency F0c.

The frequency F _INF is advantageously included in a second range of values extending between (M-2) / M, inclusive, and (M-1) / M multiplied by the frequency Fz (N), that is to say [(M-2 ) / M] · Fz (N) = <F _INF <[(M-1) / M] · Fz (N).

• un premier signal d'activation périodique du dispositif de freinage, qui est déterminé par ledit signal digital périodique à ladite fréquence F_INF, lorsque la dérive temporelle correspond à ladite au moins une certaine avance, de manière à générer une première série d'impulsions de freinage périodiques qui sont appliquées au résonateur mécanique à la fréquence F_INF, et
• un deuxième signal d'activation périodique du dispositif de freinage, qui est déterminé par ledit signal digital périodique à ladite fréquence F_SUP, lorsque la dérive temporelle correspond audit au moins un certain retard, de manière à générer une deuxième série d'impulsions de freinage périodiques qui sont appliquées au résonateur mécanique à la fréquence F_SUP.

In a main variant of the second general embodiment, the regulation circuit is designed to be able to supply, each time the measuring circuit determines a time drift corresponding to at least a certain advance or at least a certain delay, momentarily to the device. brake a control signal which is selectively formed by:

• a first periodic activation signal of the braking device, which is determined by said periodic digital signal at said frequency F _INF , when the time drift corresponds to said at least a certain advance, so as to generate a first series of pulses of periodic braking which are applied to the mechanical resonator at the frequency F _INF , and
• a second periodic activation signal of the braking device, which is determined by said periodic digital signal at said frequency F _SUP , when the time drift corresponds to said at least a certain delay, so as to generate a second series of braking pulses periodic which are applied to the mechanical resonator at the frequency F _SUP .

In particular, the braking pulses have a duration T _P less than a quarter of a setpoint period T0c, ie T _P <T0c / 4, T0c being by definition the inverse of the setpoint frequency F0c.

In a preferred variant, the positive integer K is greater than two and less than ten, ie 2 <K <10, and the number N is less than the number M divided by one hundred (N <M / 100).

In a general variant, the regulation circuit is arranged so that the control signal is supplied to the braking device, each time this regulation circuit determines that the time drift corresponds to said at least a certain advance or to said at least one certain delay, during a correction period during which the frequency of the mechanical oscillator is synchronized respectively on a first correction frequency Fcor1 which is in said second range of values calculated with Fz (N = 2) = F0c or on a second correction frequency Fcor2 which is in said first range of values calculated with Fz (N = 2) = F0c.

In a preferred variant, the duration of the synchronous phase is provided to be much greater than a maximum duration of a transient phase generally occurring at the start of the correction periods before the synchronous phase.

Brief description of the figures

• La Figure 1 montre, en partie schématiquement, un premier mode de réalisation d'une pièce d'horlogerie selon l'invention ;
• La Figure 2 montre le schéma du circuit électronique d'une variante du dispositif de régulation du premier mode de réalisation ;
• La Figure 3 est un organigramme d'un mode de fonctionnement du dispositif de régulation de la Figure 2 implémenté dans son circuit logique de commande ;
• La Figure 4 donne, pour un premier mode de régulation selon l'invention mis en œuvre dans le premier mode de réalisation de l'invention et dans le cas d'une pièce d'horlogerie dont le mécanisme indicateur d'une donnée temporelle présente de l'avance, des graphes représentant l'évolution temporelle de la position angulaire du résonateur mécanique, une première série d'impulsions de freinage appliquées à ce résonateur mécanique, dans une période de correction, en fonction d'une dérive temporelle également représentée, ainsi qu'un graphe de l'évolution de la fréquence instantanée de l'oscillateur mécanique dans une zone temporelle englobant la période de correction considérée ;
• La Figure 5 donne, pour le premier mode de régulation et dans le cas d'une pièce d'horlogerie dont le mécanisme indicateur d'une donnée temporelle présente du retard, des graphes représentant l'évolution temporelle de la position angulaire du résonateur mécanique, une deuxième série d'impulsions de freinage appliquées à ce résonateur mécanique, dans une période de correction, en fonction d'une dérive temporelle également représentée, ainsi qu'un graphe de l'évolution de la fréquence instantanée de l'oscillateur mécanique dans une zone temporelle englobant la période de correction considérée ;
• La Figure 6 montre, en partie schématiquement, un deuxième mode de réalisation d'une pièce d'horlogerie selon l'invention ;
• La Figure 7 montre le résonateur mécanique et un dispositif de freinage électromagnétique formant le dispositif de régulation du deuxième mode de réalisation ;
• La Figure 8 montre le schéma du circuit électronique d'une variante du dispositif de régulation du deuxième mode de réalisation ; et
• La Figure 9 donne, dans le cadre du deuxième mode de réalisation, les graphes de la position angulaire du résonateur mécanique sur une période d'oscillation, de la tension induite dans une bobine du dispositif de freinage électromagnétique et d'un intervalle de temps distinct au cours duquel un court-circuit est appliqué à la bobine, dans un régime stable d'une synchronisation entre un générateur de fréquence du dispositif de régulation et le résonateur mécanique oscillant qui est obtenue au cours d'une série d'impulsions de freinage appliquées au résonateur mécanique.

The invention will be described below in more detail with the aid of the appended drawings, given by way of non-limiting examples, in which:

• The Figure 1 shows, in part schematically, a first embodiment of a timepiece according to the invention;
• The Figure 2 shows the electronic circuit diagram of a variant of the regulation device of the first embodiment;
• The Figure 3 is a flowchart of an operating mode of the device for regulating the Figure 2 implemented in its control logic circuit;
• The Figure 4 gives, for a first regulation mode according to the invention implemented in the first embodiment of the invention and in the case of a timepiece for which the mechanism indicating a time datum has an advance , graphs representing the temporal evolution of the angular position of the mechanical resonator, a first series of braking pulses applied to this mechanical resonator, in a correction period, as a function of a temporal drift also represented, as well as a graph of the evolution of the instantaneous frequency of the mechanical oscillator in a time zone including the considered correction period;
• The Figure 5 gives, for the first regulation mode and in the case of a timepiece whose mechanism indicating a temporal datum has a delay, graphs representing the temporal evolution of the angular position of the mechanical resonator, a second series of braking pulses applied to this mechanical resonator, in a correction period, as a function of a time drift also represented, as well as a graph of the evolution of the instantaneous frequency of the mechanical oscillator in a time zone encompassing the correction period considered;
• The Figure 6 shows, in part schematically, a second embodiment of a timepiece according to the invention;
• The Figure 7 shows the mechanical resonator and an electromagnetic braking device forming the regulating device of the second embodiment;
• The Figure 8 shows the electronic circuit diagram of a variant of the regulation device of the second embodiment; and
• The Figure 9 gives, in the context of the second embodiment, the graphs of the angular position of the mechanical resonator over a period of oscillation, of the voltage induced in a coil of the electromagnetic braking device and of a distinct time interval during which a short circuit is applied to the coil, in a stable state of synchronization between a frequency generator of the regulating device and the oscillating mechanical resonator which is obtained during a series of braking pulses applied to the mechanical resonator .

Detailed description of the invention

To the Figure 1 is shown a timepiece according to the present invention. Apart from the arrangement of the regulation circuit and the operating mode of this control circuit, which implements a regulation method according to the present invention, this timepiece essentially corresponds to the first embodiment of the timepiece described in the document EP 3,339,982 using figures 1 and 2 of this document, so that reference will be made to the teaching of this document and all the variant embodiments will not be described here.

The timepiece 2 comprises a mechanical watch movement 4 which incorporates a mechanism 6 arranged to indicate at least one time datum, a mechanical resonator 14, formed by a balance 16 mounted to pivot on the plate 5 and a balance spring 18, and a device maintenance of the mechanical resonator forming with this mechanical resonator a mechanical oscillator which rates the operation of the indicator mechanism of a temporal datum. The maintenance device comprises an escapement 12, formed by an anchor and an escape wheel which is kinematically connected to the barrel 8 by means of the gear 10. The mechanical resonator is capable of oscillating along an axis d oscillation, here a circular geometric axis, around a neutral position corresponding to a state of minimum mechanical potential energy. Each oscillation of the mechanical resonator defines an oscillation period and two vibrations.

The timepiece 2 further comprises a device for regulating the average frequency of the mechanical oscillator, this regulating device 20 comprising an electronic regulating circuit 22 which is associated with a reference time base constituted by an auxiliary oscillator 36 This auxiliary oscillator is formed by a quartz resonator 23 and a clock circuit 38 which maintains the quartz resonator and receives from the latter a reference frequency signal which this clock circuit outputs. in the form of a digital periodic reference signal S _Q. It will be noted that other types of auxiliary oscillators can be provided, in particular an oscillator fully integrated into the regulation circuit. By definition, the auxiliary oscillator is more precise than the mechanical oscillator. The regulation device 20 also comprises a sensor 24 for detecting at least one angular position of the balance when it oscillates, making it possible to detect, for a useful operating range of the mechanical oscillator, a number of alternations or periods in the oscillation of the mechanical resonator. The regulating device also comprises a mechanical braking device 26 designed to be able to momentarily apply a braking force to the mechanical resonator 14, in particular mechanical braking pulses to its balance. Finally, the watch assembly comprises an energy source 32 associated with a device 34 for storing the electrical energy generated by the energy source. The energy source is for example formed by a photovoltaic cell or by a thermoelectric element, these examples not being in any way limiting. In the case of a battery, the energy source and the storage device together form one and the same electrical component.

In general, the regulation device 20 also comprises a measuring device arranged to measure, on the basis of position signals supplied by the sensor, a time drift D _T of the mechanical oscillator relative to the auxiliary oscillator (base of reference time 36). It will be understood that such a measurement is easy when a sensor is provided which is capable of detecting the passage of the mechanical resonator through a certain angular position, in particular through its neutral position. Such an event takes place in all alternations (half-periods of oscillation) of the mechanical oscillator. The measurement circuit will be described in more detail below.

The sensor 24 is designed to be able to detect the passage of at least one reference point of the balance 16 through a certain given angular position relative to a support of this mechanical resonator. In advantageous variant, the sensor is arranged to detect the passage of the mechanical resonator through its neutral position. It will be noted that, in this variant, the sensor can be associated with the anchor of the escapement so as to detect the tilting of this anchor during the oscillation sustaining pulses which are provided substantially when the mechanical resonator passes through. its neutral position.

In a particular variant, the sensor 24 is an optical sensor, of the photoelectric type, which comprises a light source, arranged so as to be able to send a beam of light in the direction of the balance, and a light detector, arranged to receive in return a light signal the intensity of which varies periodically depending on the position of the balance. For example, the beam is sent to the lateral surface 15 of the rim 17, this surface having a limited zone with a reflectivity different from the two neighboring zones, so that the sensor can detect the passage of this limited zone and provide the device with regulating a position signal when this event occurs. It will be understood that the circular surface having a variable reflection for the light beam can be located at other places of the balance. The variation can in a particular case be produced by a hole in the reflecting surface. The sensor can also detect the passage of a certain part of the balance, for example an arm, the neutral position corresponding for example to the middle of a signal reflected by this arm. It is therefore understood that the modulation of the light signal makes it possible to detect in various ways at least one angular position of the balance, by a negative or positive variation of the light picked up. In other variants, the position sensor may be of the capacitive type or of the inductive type and thus be arranged so as to be able to detect a variation in capacitance, respectively inductance, as a function of the position of the balance. The sensor comprises means for converting the analog light signal into a digital signal Sc. It can also include a rocker which makes it possible to divide by two the frequency of the light signal when the latter occurs once per alternation, so that the signal Sc corresponds to the oscillation frequency F0 of the mechanical oscillator. Those skilled in the art are aware of numerous sensors which can easily be incorporated into the watch assembly according to the invention.

The mechanical braking device 26 is designed to be able to apply mechanical braking pulses to the balance 16 so as to regulate the frequency of the mechanical oscillator when a certain time drift D _T of this mechanical oscillator is observed. In an advantageous variant, a braking torque applied to the mechanical resonator by any mechanical braking pulse is provided less than a locking torque of the mechanical oscillator and the duration of the braking pulses is provided so as to take a certain maximum. energy to the mechanical resonator so that the amplitude of the oscillation remains greater than a given minimum value. In other words, the braking torque is expected to be less than the torque exerted by the hairspring at the minimum expected amplitude and the duration of the pulses is such that this minimum amplitude is respected for a predefined minimum torque which is exerted by the barrel (note that the mechanical oscillator is maintained by the barrel via the escapement), in order not to momentarily block the oscillating movement of the mechanical resonator during braking pulses and to keep the mechanical oscillator within its range useful operating mode as soon as the barrel exerts a torque greater than the minimum torque expected. In another more general variant, it is possible to apply a braking torque greater than the torque exerted by the hairspring at the minimum amplitude provided, but the duration of the pulses is determined, taking into account the maintenance of the mechanical oscillator, to so that this minimum amplitude is maintained for the minimum torque of the barrel from which the timepiece is expected to be functional and for any angular position of the mechanical resonator during the application of a braking pulse. Note that the energy taken from the resonator mechanical is maximum when the braking pulse occurs during the passage of this resonator through its neutral position.

To the Figure 1 , the mechanical braking device is formed by an actuator 26 which comprises a mechanical braking member 28 arranged to be actuated, in response to a control signal S _F supplied by the regulation circuit to the control circuit 30 of this actuator, of so as to exert, during the braking pulses, a mechanical braking torque on a braking surface 15 of the pivoting balance 16. In the variant shown, the braking surface is circular and defined by the outer lateral surface of the rim 17 of the balance . The mechanical braking member 28 comprises a movable part (defined by the free end of this member) which defines a braking shoe arranged so as to be able to exert a certain pressure against the circular braking surface during the application of the brakes. braking pulses to the mechanical resonator.

The actuator 26 comprises a piezoelectric element supplied by a control circuit 30 which applies an activation electric voltage to it as a function of the control signal S _F supplied by the regulation circuit 22. When the piezoelectric element is momentarily placed under tension, the braking member comes into contact with a braking surface of the balance to brake it. In the example shown in Figure 1 , the blade forming the braking member is curved and its end part presses against the circular lateral surface 15 of the rim 17 of the balance 16. The end part of the blade therefore defines a movable brake shoe. In a preferred variant, the pivoting balance and the mechanical braking member are arranged so that the braking pulses can be applied mainly by dynamic dry friction between the mechanical braking member and the braking surface 15. In another variant, one can provide a viscous friction between the braking member and a braking part of the balance.

In a particular variant (not shown), the balance comprises a central shaft which defines or which carries a part other than the rim of the balance defining a circular braking surface. In this case, a shoe of the braking member is arranged so as to exert pressure against this circular braking surface during the application of the mechanical braking pulses.

A circular braking surface, for an oscillating member which is pivoted (balance wheel), associated with at least one braking shoe, carried by the braking device of the regulating device, constitutes a mechanical braking system which has decisive advantages. Indeed, thanks to such a system, braking pulses can be applied to the mechanical resonator at any moment of the oscillations, and this independently of the amplitude of oscillation of the balance. It will also be noted that the pad of the braking member can also have a circular contact surface, of the same radius as the braking surface, but a flat surface has the advantage of leaving a certain margin in the positioning of the brake member. braking relative to the balance, which makes it possible to have greater tolerances in the manufacture and assembly of the braking device in the watch movement or at its periphery.

Advantageously, the various elements of the regulation device 20 form a module independent of the watch movement. Thus, this module can be assembled or associated with the mechanical movement 4 only during their assembly, in particular in a watch case. In particular, such a module can be fixed to a casing circle which surrounds the watch movement. It will be understood that the electronic regulation module can therefore be advantageously associated with the watch movement once the latter has been fully assembled and adjusted, the assembly and disassembly of this module being able to take place without having to intervene on the mechanical movement itself.

In general, the regulation circuit 22 is designed to be able to determine whether a time drift, which is measured by the measuring device on the basis of the signals that it receives from the sensor 24 and from the reference time base 36, corresponds at least a certain advance or at least a certain delay and in order to be able, if this is the case, to generate a control signal which selectively activates the braking device, to generate periodic braking pulses which are applied to the mechanical resonator with a braking frequency which is a function of the measured time drift, so as to at least partially correct this measured time drift.

In a main variant, the regulation circuit 22 comprises a frequency generator device arranged so as to be able to generate a first periodic digital signal S _FI at a first frequency F _INF (first braking frequency) and a second periodic digital signal S _FS at a second frequency F _SUP (second braking frequency).

The first frequency F _INF is included in a range of values extending between (M-2) / M, inclusive, and (M-1) / M multiplied by a frequency Fz (N) which is equal to twice a reference frequency F0c, for the mechanical oscillator, divided by a positive integer N, i.e. Fz (N) = 2 F0c / N and [(M-2) / M] Fz (N) = <F _INF < [(M-1) / M] · Fz (N), M being equal to one hundred times two to the power K with K equal to a positive integer greater than zero and less than thirteen, that is to say 0 <K <13 and M = 100 · 2 ^K , and N being expected to be less than M divided by thirty, i.e. N <M / 30. The second frequency F _SUP is included in a range of values extending between (M + 1) / M and (M + 2) / M, inclusive, multiplied by the frequency Fz (N), with M and N as defined above, or [(M + 1) / M] · Fz (N) <F _SUP = <[(M + 2) / M] · Fz (N). The operator '= <' means 'equal to or less than', the limit in question being within the range of values.

• le premier signal digital périodique S_FI lorsque la dérive temporelle correspond au moins à la certaine avance, de manière à générer une première série d'impulsions de freinage 60 qui sont appliquées au résonateur mécanique 14 avec une première fréquence de déclenchement F1_D égale à la première fréquence F_INF (première fréquence de freinage), et
• le deuxième signal digital périodique S_FS lorsque la dérive temporelle correspond au moins au certain retard, de manière à générer une deuxième série d'impulsions de freinage 61 qui sont appliquées au résonateur mécanique avec une deuxième fréquence de déclenchement F2_D égale à la deuxième fréquence F_SUP (deuxième fréquence de freinage).

The regulation circuit 22 is arranged to supply, each time it determines that the time drift D _T of the mechanical oscillator corresponds at least to a certain advance or at least to a certain delay, momentarily to the braking device 26 a signal control S _F during a correction period, this control signal S _F being selectively formed by:

• the first periodic digital signal S _FI when the time drift corresponds at least to the certain advance, so as to generate a first series of braking pulses 60 which are applied to the mechanical resonator 14 with a first triggering frequency F1 _D equal to the first frequency F _INF (first braking frequency), and
• the second periodic digital signal S _FS when the time drift corresponds at least to the certain delay, so as to generate a second series of braking pulses 61 which are applied to the mechanical resonator with a second trigger frequency F2 _D equal to the second frequency F _SUP (second braking frequency).

In a preferred variant, the positive integer K is greater than two and less than ten, ie 2 <K <10 and the number N is less than the number M divided by one hundred (N <M / 100).

The braking pulses have a duration T _P less than half of a setpoint period T0c, i.e. T _P <T0c / 2, T0c being by definition the inverse of the setpoint frequency F0c for the mechanical oscillator formed by the resonator 14 and of the exhaust 12. Preferably, in this first embodiment, the braking pulses have a duration T _P less than a quarter of the reference period T0c, ie T _P <T0c / 4.

• deux étages DIV1 et DIV2 d'un diviseur de fréquence qui reçoit en entrée de la base de temps de référence 36 le signal périodique digital de référence S_Q et qui fournit en sortie un signal d'horloge S_H à une moindre fréquence,
• un compteur différentiel bidirectionnel CB qui reçoit à une entrée le signal d'horloge S_H et à une seconde entrée le signal digital Sc du capteur 24, lequel fournit via ce signal digital Sc une impulsion digitale à chaque alternance ou à chaque période de l'oscillation du résonateur mécanique 14, et qui fournit en sortie un signal de mesure S_D correspondant à une valeur représentative de la dérive temporelle D_T de l'oscillateur,
• un circuit logique de commande 40 qui reçoit en entrée seulement le signal de mesure S_D (hormis un signal de cadencement à une fréquence généralement bien supérieure à celle de l'oscillateur à quartz, soit bien supérieure à la fréquence du signal de référence S_Q) et qui fournit en sortie, en fonction de la valeur du signal de mesure S_D, sélectivement un signal de commande S_R et un signal de commande S_A (lesquels seront décrits par la suite lors de la description d'un premier mode de régulation selon l'invention en référence aux Figures 3 à 5),
• un premier générateur de fréquence 42 fournissant, lorsqu'il est activé par le signal de commande S_A, momentanément le premier signal digital périodique S_FI et un deuxième générateur de fréquence 44 fournissant, lorsqu'il est activé par le signal de commande S_R, momentanément le deuxième signal digital périodique S_FS, les premier et deuxième générateurs de fréquence formant ensemble le dispositif générateur de fréquences mentionné précédemment, et
• une porte logique 'OR' qui est connectée en entrée aux sorties respectives des deux générateurs de fréquence 42 et 44 et qui fournit en sortie le signal de commande S_F.

The Figure 2 shows in detail the regulation circuit 22 and the control circuit 30 of the actuator 26 forming the mechanical braking device characterizing the first embodiment. The regulation circuit comprises:

• two stages DIV1 and DIV2 of a frequency divider which receives at input of the reference time base 36 the digital periodic reference signal S _Q and which provides at output a clock signal S _H at a lower frequency,
• a bidirectional differential counter CB which receives at one input the clock signal S _H and at a second input the digital signal Sc of the sensor 24, which supplies via this digital signal Sc a digital pulse at each alternation or at each period of the oscillation of the mechanical resonator 14, and which outputs a measurement signal S _D corresponding to a value representative of the time drift D _T of the oscillator,
• a control logic circuit 40 which receives as input only the measurement signal S _D (apart from a timing signal at a frequency generally much higher than that of the crystal oscillator, that is to say much higher than the frequency of the reference signal S _Q ) and which outputs, as a function of the value of the measurement signal S _D , selectively a control signal S _R and a control signal S _A (which will be described below during the description of a first mode of regulation according to the invention with reference to Figures 3 to 5 ),
• a first frequency generator 42 supplying, when it is activated by the control signal S _A , momentarily the first periodic digital signal S _FI and a second frequency generator 44 supplying, when it is activated by the control signal S _R , momentarily the second periodic digital signal S _FS , the first and second frequency generators together forming the previously mentioned frequency generator device, and
• a logic gate “OR” which is connected as an input to the respective outputs of the two frequency generators 42 and 44 and which provides the control signal S _{F as} an output.

If the digital signal Sc supplied by the sensor 24 has a period corresponding to an alternation of the mechanical oscillator, a rocker can be arranged in the regulation circuit 22 upstream of the counter CB so as to divide by two the periodic pulses of the signal Sc and supply at the input of the counter CB a single pulse per oscillation period T0.

The control circuit 30 of the braking device comprises a source of supply voltage V _ACT which supplies the braking member to actuate it via a switch 50, which is controlled by a periodic signal S _P supplied by a built-in timer 48. in the control circuit to manage the duration of the braking pulses. The timer selectively receives, via the control signal S _F , the first periodic digital signal S _FI and the second periodic digital signal S _FS which activate it periodically during a correction period according to a detection of a certain advance or a certain delay in the operation of the mechanical oscillator and therefore in the operation of the timepiece, and this repeatedly during distinct and successive correction periods when a time drift continues. Thus, the timer 48 makes the switch 50 periodically conductive during each correction period to generate, as the case may be, either a first series of braking pulses 60 or a second series of braking pulses 61 (see Figures 4 and 5 ).

In a preferred variant, the braking surface of the balance 16 is configured so as to allow the braking device to start, in a useful operating range of the mechanical oscillator, a braking pulse of each first series of braking pulses. and a braking pulse of every second series of braking pulses at any angular position of the mechanical resonator 14 between the two extreme angular positions that it can occupy when it oscillates within the useful operating range of the part d watchmaking. As the amplitude of oscillation of the sprung balance is generally greater than 180 ° (+/- 180 °) in a conventional mechanical movement, the aforementioned condition implies, in the variant shown in Figure 1 , that the lateral surface 15 of the balance is circular and substantially continuous over the entire perimeter of the balance, so that the movable braking member 28 can come to bear against the circular lateral surface substantially at any point.

The Figure 3 gives the flowchart of a first regulation mode implemented in the regulation circuit 22 of the first embodiment. After activation of the circuit at the start of its electrical supply or as part of an initialization occurring during this activation, the counter CB is reset to zero and it begins to count any difference between the first number of pulses included in the signal Sc received from the sensor 24 and the second number of pulses included in the clock signal S _H. The divider DIV1 & DIV2 is arranged so that the clock signal supplies a reference signal with a number of pulses per unit of time corresponding to the number of pulses provided in the signal Sc per unit of time for a correct operation of the timepiece, that is to say without time drift.

• dans le graphe supérieur 54B, la position angulaire θ du résonateur mécanique 14 sur une pluralité de périodes d'oscillation au cours de laquelle intervient une première série d'impulsions de freinage 60,
• dans le graphe intermédiaire 56A, l'évolution correspondante de la fréquence de l'oscillateur mécanique (la fréquence de consigne F0c est égale à 4 Hz dans l'exemple traité, soit F0c = 4 Hz), et
• dans le graphe inférieur 58A, l'évolution correspondante de la dérive temporelle D_T de l'oscillateur mécanique.

In each sequence of the first regulation mode, the logic circuit 40 firstly determines whether the value of the counter CB is greater than a positive integer N1 _H (corresponding to an advance of the mechanical oscillator) or less than a negative integer -N2 _H (corresponding to a delay of the mechanical oscillator). If CB> N1 _H (first case considered), the logic circuit activates the frequency generator 42 via a control signal S _A and this frequency generator begins to supply the first periodic digital signal S _FI , at the first defined _{frequency F INF} previously, to the control circuit 30 of the braking device via the logic gate 46. The result is that the braking device then begins to generate a first series of braking pulses 60 periodically at the first frequency F _INF . Such a situation is shown in the Figure 4 which shows :

• in the upper graph 54B, the angular position θ of the mechanical resonator 14 over a plurality of oscillation periods during which a first series of braking pulses 60 occurs,
• in the intermediate graph 56A, the corresponding evolution of the frequency of the mechanical oscillator (the reference frequency F0c is equal to 4 Hz in the example treated, i.e. F0c = 4 Hz), and
• in the lower graph 58A, the corresponding evolution of the time drift D _T of the mechanical oscillator.

It will be noted that, in order to have a visible representation of the angular position of the mechanical resonator and of the braking pulses, the Figure 4 shows in fact only a truncated series of braking pulses with a much smaller number of pulses than in reality, so that the time drift D _T corresponds here to a fraction ε1 _H of the time drift N1 _H. But this makes it possible to clearly expose the operating principle. In the first case, in the example given, the natural frequency F0 = 4.0005 Hz, which corresponds to an advance of about ten seconds per day. When the time drift reaches or exceeds a value ε1 _H , namely in reality a value N1 _H , the braking device is actuated via the frequency generator 42 and it begins to periodically apply to the mechanical resonator braking pulses 60 at a frequency F _INF defined previously (for the sake of clarity of the drawing, all the pulses are shown in the Figure 4 as they occur during a stable / synchronous phase discussed below). It will be noted that, in the example given, the braking pulses intervene in each oscillation period and therefore with a frequency F0c, so that the frequency Fz (N) = 2F0c / N, which is used to define the ranges for braking frequencies, is provided with N = 2. For example, as shown in Figure 4 , the first braking frequency F _INF is equal to 0.99975 F0c = 3.9990 Hz, i.e. F _INF = Fz (2) (L-1) / L = F0c (L-1) / L with L = 4'000 . This first frequency F _INF is in the range [(M-2) / M] · Fz (2) to [(M-1) / M] · Fz (2) with K = 6, or M = 100 · 2 ⁶ .

During the activation phase of the frequency generator 42, the logic circuit 40 waits for the value of the counter CB to become equal to or less than an integer N1 _L , which is less than the number N1 _H and preferably less in absolute value than N1 _H. In the example shown in Figure 4 , N1 _L is equal to zero so that the fraction ε1 _L of the time drift N1 _L given on this Figure 4 is also zero. As soon as the logic circuit has detected the expected event, or when the value of the counter CB becomes equal to or less than an integer N1 _L , the logic circuit puts an end to the activation of the generator 42 so that the latter is deactivated. , which ends a correction sequence / correction period. If the value N1 _H = 4 and the counter CB counts the vibrations of the mechanical oscillator, this corresponds to a time drift of half a second. In the example given, the duration D _PC of a correction period is equal to at least the above-mentioned number L multiplied by the _{corrected time drift D T} , i.e. D _PC = L · D _T = 4'000 · 0.5 = 2 '000 seconds. Thus, the correction periods each last approximately 34 minutes, including the initial transient phase.

To the Figure 4 , the graph 56A of the frequency of the mechanical oscillator, formed by the mechanical resonator 14 and the escapement 12, shows the evolution of this frequency resulting from a sequence of the first regulation mode in the first case described above . While the frequency of the mechanical oscillator is greater than the setpoint frequency F0c in the absence of braking pulses, this frequency decreases as soon as a first series of braking pulses 60 occurs. A transient phase is observed before that the oscillation frequency stabilizes at a first correction frequency Fcor1 which is equal to the first frequency F _INF with Fz (N = 2) = F0c, i.e. Fcor1 = F _INF (N = 2), and therefore that a synchronous phase appears. Thus, during this synchronous phase, one observes a synchronization of the mechanical oscillator on the first correction frequency Fcor1 which is slightly lower than the reference frequency, which makes it possible to carry out a correction of the time drift, as shown in lower graph 58A of the Figure 4 . At the end of a sequence of first regulation mode, the value of the time drift is reduced and is here equal to the integer N1 _L which corresponds to a lower threshold for the time drift, while the integer N1 _H , which generates the triggering of a first series braking pulses, corresponds to an upper threshold of the time drift.

It will be noted that, in absolute values, the difference between F _INF (N = 2) and F0c is preferably expected to be greater than a typical difference between F0 and F0c. Thus, the braking device is generally activated less than half the time, or less than 12 hours per day. In the example given here, assuming that the natural frequency F0 remains stable over time, the braking device must be actuated for approximately 8 hours per day.

• dans le graphe supérieur 54B, la position angulaire du résonateur mécanique 14 sur une pluralité de périodes d'oscillation au cours de laquelle intervient une seconde série d'impulsions de freinage 61,
• dans le graphe intermédiaire 56B, l'évolution correspondante de la fréquence de l'oscillateur mécanique, et
• dans le graphe inférieur 58B, l'évolution correspondante de la dérive temporelle D_T de l'oscillateur mécanique.

In each sequence of the regulation mode, if CB <-N2 _H (second case considered), the logic circuit 40 activates the frequency generator 44 via a control signal S _R and this frequency generator begins to supply the second periodic digital signal S _FS , at the second frequency F _SUP defined above, to the control circuit 30 of the braking device via the logic gate 46. The result is that the braking device then begins to generate a second series of braking pulses 61 in such a manner periodic at the second frequency F _SUP . Such a situation is shown in the Figure 5 which shows :

• in the upper graph 54B, the angular position of the mechanical resonator 14 over a plurality of oscillation periods during which a second series of braking pulses 61 occurs,
• in the intermediate graph 56B, the corresponding evolution of the frequency of the mechanical oscillator, and
• in the lower graph 58B, the corresponding evolution of the time drift D _T of the mechanical oscillator.

It will be noted that, in order to have a visible representation of the angular position of the mechanical resonator and of the braking pulses, the Figure 5 , as the Figure 4 , shows in fact only a truncated series of braking pulses with a much smaller number of pulses than in reality, so that the time drift D _T corresponds here to a fraction -ε2 _H of the time drift -N2 _H . In the second case, in the example given, the natural frequency F0 = 3.9995 Hz, which corresponds approximately to a delay of ten seconds per day. When the time drift reaches or becomes less than a value -ε2 _H , namely in reality a value -N2 _H , the braking device is actuated via the frequency generator 44 and it begins to periodically apply braking pulses to the mechanical resonator 61 at a frequency F _SUP defined previously (for the sake of clarity of the drawing, all the pulses are shown in Figure 5 as they occur during a stable / synchronous phase discussed below). In the example shown, as in the first case, the frequency Fz (N) = 2 · F0c / N is provided with N = 2, so that the frequency Fz (2) = F0c. The second braking frequency F _SUP is equal to 1.00025 · F0c = 4.001, i.e. to F _SUP = F0c · (L + 1) / L with L = 4'000. This second frequency F _SUP is in the range [(M + 1) / M] · Fz (2) to [(M + 2) / M] · Fz (2) with K = 6, or M = 100 · 2 ⁶ . It will be noted that nothing makes it necessary to take the same value for N and the same value L in the second case (correction of a delay) as in the first case (correction of an advance).

During the activation phase of the frequency generator 44, the logic circuit 40 waits for the value of the counter CB to become equal to or greater than an integer N2 _L , which is greater than the number N2 _H and preferably less in absolute value than N2 _H. In the example shown in Figure 5 , N2 _L is equal to zero, like N1 _L , so that the fraction ε2 _L of the time drift N2 _L given on this Figure 5 is also zero. As soon as the logic circuit has detected the expected event, either when the value of the counter CB becomes equal to or greater than the integer N2 _L , the logic circuit puts an end to the activation of the generator 44 so that the latter is deactivated, which ends a correction sequence. The correction sequence is provided in a loop, so that the logic circuit 40 returns then at the start of a next sequence and it waits for the detection of a new time drift. Each correction sequence corresponds to a correction period.

To the Figure 5 , the graph 56B of the frequency of the mechanical oscillator shows the evolution of this frequency resulting from a sequence of the first regulation mode in the second case considered. While in the absence of braking pulses, the frequency of the mechanical oscillator is here lower than the setpoint frequency F0c = 4 Hz, the frequency of the mechanical oscillator increases as soon as a second series of braking pulses occurs. 61. As in the first case, we observe a transient phase before the frequency of the mechanical oscillator stabilizes at a second correction frequency Fcor2 equal to the second frequency F _SUP with Fz (N = 2) = F0c, or Fcor2 = F _SUP (N = 2) and therefore that a synchronous phase appears during the second series of braking pulses 61. Thus, during this synchronous phase, a synchronization of the mechanical oscillator on the second frequency of correction Fcor2 which is slightly higher than the reference frequency F0c, which makes it possible to perform a correction of the time drift D _T , as shown in the lower graph 56B of the Figure 5 . In this second case, at the end of a sequence of the first regulation mode, the absolute value of the time drift is reduced relative to the start of the sequence and is here equal to the integer N2 _L which corresponds to a lower threshold for the time drift, while the integer N2 _H , which triggers a second series of braking pulses, corresponds to an upper threshold for the time drift (note that the concept of lower threshold and upper threshold is considered in absolute values).

The regulation circuit is arranged so that each correction period has a sufficient duration to establish the synchronous phase in which the frequency of the mechanical oscillator is synchronized, as a function of a detected positive or negative drift, respectively on a first correction frequency Fcor1 which is equal to the frequency F _INF calculated with Fz (N = 2) = F0c or on a second correction frequency Fcor2 which is equal to the frequency F _SUP calculated with Fz (N = 2) = F0c.

In a preferred variant, the duration of the synchronous phase is expected to be much greater than a maximum duration of the transient phase, in particular at least ten times greater.

The timepiece according to the invention is remarkable in that a correction of a time drift, detected by the regulation circuit in association with a sensor, is carried out by the generation of a series of braking pulses. periodically at a selected frequency close to but different from a frequency Fz (N) = 2F0c / N, N being a positive integer, which makes it possible to regulate the average frequency of the mechanical oscillator so that it equals a reference frequency F0c without having to manage the instants of triggering of the braking pulses relative to the angular position of the mechanical oscillator as in the prior art. Provision could be made to determine the instant of a first braking pulse of each series of pulses relative to the angular position of the mechanical oscillator to ensure a relatively short transient phase before the stable phase of the synchronization, but such a variant is not necessary.

• une base de temps de référence 36,
• un dispositif de freinage électromagnétique 76 pour freiner le résonateur mécanique 14A au cours de périodes de correction, et
• un circuit de régulation 74 qui reçoit un signal périodique digital S_Q de la base de temps de référence et qui est agencé pour engendrer des séries d'impulsions 84 de court-circuit de la bobine 78 via un interrupteur 50 (voir Figures 8 et 9) respectivement au cours de périodes de correction de dérives temporelles détectées successivement par ce circuit de régulation.

With reference to Figures 6 to 9 , a second embodiment of the invention and a second regulation mode according to the invention will be described below. To the Figure 6 , the elements of the watch movement 4A of the timepiece 3 already described above will not be described here again. The regulation device 72 of this second embodiment comprises:

• a reference time base 36,
• an electromagnetic braking device 76 for braking the mechanical resonator 14A during correction periods, and
• a regulation circuit 74 which receives a digital periodic signal S _Q from the reference time base and which is arranged to generate series of pulses 84 short-circuiting coil 78 via a switch 50 (see Figures 8 and 9 ) respectively during periods of correction of temporal drifts detected successively by this regulation circuit.

By 'electromagnetic braking' is understood a braking of the mechanical resonator generated via an electromagnetic interaction between at least one permanent magnet, carried by the mechanical resonator or a support of this mechanical resonator, and at least one coil carried respectively by the support or the resonator mechanical and associated with an electronic circuit in which a current induced in the coil by the permanent magnet can be generated.

In a general variant (not shown), the electromagnetic braking device is formed by an electromagnetic system which comprises a coil 78 carried by a support 5 of the mechanical resonator 14A and at least one permanent magnet carried by a balance of this mechanical resonator, this electromagnetic system being arranged so that an induced voltage is generated between the two terminals 78A & 78B of the coil in each alternation of the oscillation of the mechanical resonator for a useful operating range of the mechanical oscillator. The regulation device is arranged so as to allow the regulation circuit to temporarily reduce the impedance between the two terminals of the coil, during distinct time intervals T _P , to generate electromagnetic braking pulses of the mechanical resonator. In the advantageous variant of the second embodiment described with reference to Figures 8 and 9 , a short-circuit of the coil is carried out during each distinct time interval T _P.

In the particular variant shown in Figures 6 and 7 , the electromagnetic system of the electromagnetic braking device comprises a first pair of bipolar magnets 64 & 65 axially magnetized and of opposite polarities. These two bipolar magnets are arranged on the balance 16A symmetrically relative to a semi-axis of reference 68 of this balance, this reference semi-axis defining a zero angular position ('0') when the mechanical resonator is in its neutral position (minimum potential energy state). We consider here a polar coordinate system centered on the axis of oscillation of the mechanical resonator 14A and fixed relative to the plate 5 of the watch movement 3. In general, the coil 78 is arranged with an angular offset relative to the angular position. zero so that a voltage induced in the coil intervenes substantially, when the mechanical oscillator oscillates in its useful operating range, in each half-wave alternately before and after the passage of the mechanical resonator through its neutral position in this half-wave. The angular offset of the coil is defined as the minimum angular distance between the zero angular position and the angular position of the center of the coil. In the useful operating range of the timepiece 3, the extreme angular positions (oscillation amplitudes) of the mechanical resonator are provided, in absolute values, substantially equal to or greater than the angular offset of the coil. Preferably, as shown in Figure 7 , the angular offset is expected to be substantially equal to 180 °. It will be noted that the balance 16A is represented on the Figure 7 in an angular position θ equal to 90 ° (θ = 90 °).

To the Figure 9 are shown, for an angular offset of 180 ° and for an oscillation amplitude of the mechanical resonator in the useful operating range of the oscillator, the angular position of the balance 16A (curve 82) over a period of oscillation and the voltage induced (curve 86) generated in coil 78 during this period of oscillation. In the useful operating range of the mechanical oscillator, the electromagnetic system formed by the coil and the first pair of magnets 64 & 65 generates, in each half-wave of this mechanical oscillator, two induced voltage pulses 88 _A and 88 _B , namely an 88 _A pulse in each first half-wave A1 ₁ , A2 ₁ and an 88 _B pulse in each second half-wave A1 ₂ , A2 ₂ . Note that the pulses 88 _A and 88 _B are separated in pairs by time zones without induced voltage in coil 28. Thanks to the positioning of the coil with an angular shift of 180 °, the two induced voltage pulses 88 _A and 88 _B occurring in each half-wave have a symmetry relative to the instant of passage of the mechanical resonator 14A through its neutral position.

In an advantageous variant shown in Figures 8 and 9 , electromagnetic braking pulses are generated by a short circuit of the coil 78 during distinct time intervals T _P which are substantially equal to or greater than the time zones without voltage induced in the coil around the two extreme positions of the mechanical resonator for the useful operating range of the mechanical oscillator. In the preferred case (angular shift of 180 ° of the coil), the temporal zones without voltage induced in the coil around the two extreme positions of the mechanical resonator are substantially equal.

Preferably, the regulation device 72 comprises a supply circuit formed by a storage capacitor C _AL and a rectifier circuit of a voltage induced (signal S _B ) in the coil 78 by a second pair of bipolar magnets 66 & 67 carried for this purpose by the balance 16A. To the Figure 8 , this supply circuit is represented as part of the regulation circuit 74. However, it can also be considered as a specific circuit which is associated with the regulation circuit in order to supply it. The second pair of bipolar magnets 66 & 67 is momentarily coupled to coil 28 in each half-wave of the mechanical resonator oscillation and therefore serves primarily to supply power to the regulator, although it may occur in one phase. initial transient of each correction period which will be described later. The second pair of bipolar magnets has a middle half-axis 69 between its two magnets which is offset by the angular offset that the coil 78 has relative to the reference half-axis 68, so that this half-axis 69 is aligned with the center of the coil when the mechanical resonator is in its home position.

The power supply circuit is connected, on the one hand, to a terminal of the coil and, on the other hand, to a reference potential (ground) of the regulation device at least periodically when the mechanical resonator passes through its position. neutral, but preferably constantly. The second pair of magnets generates induced voltage pulses 90 _A and 90 _B when the balance 8B passes through the zero angular position, these pulses having a greater amplitude than the induced voltage pulses generated by the first pair of magnets. 64 & 65 and used to supply the storage capacity, the voltage of which is represented by curve 94 at Figure 9 . The rectifier is provided here in half-wave, so that each central peak of the pulses 90 _A and 90 _B recharges the supply capacity.

The regulation circuit 74 of an advantageous variant of the second embodiment, which implements a second regulation mode of the invention, is shown in Figure 8 . It receives as input, on the one hand, the periodic reference signal S _Q supplied by the clock circuit 38 and, on the other hand, an induced voltage signal S _B (curve 86 shown in Figure 9 ) supplied by coil 78. On the basis of these two signals, the regulation circuit performs the desired regulation of the operation of the timepiece. To do this, it comprises a measuring device which comprises a divider DIV1 & DIV2 supplying a clock signal S _H , a bidirectional counter CB with two inputs (of the differential type), and a comparator 52 which receives a voltage of reference U _Ref and the induced voltage signal S _B.

As shown in Figure 9 , provision is made to detect in each oscillation period, for the useful operating range of the mechanical oscillator, a negative central peak of an induced voltage pulse 90A occurring once in each oscillation period. Comparator 52 indicates if the voltage induced in the coil becomes lower than the reference voltage U _Ref (which is negative). It is understood that the value of U _Ref is selected here to be, in absolute values, greater than the amplitudes of the induced voltage pulses 88 _A and 88 _B which are generated by the first pair of magnets 64 & 65 and less than the amplitude central peaks of the 90 _A pulses (note that, relative to the amplitudes of the induced voltage pulses 88 _A and 88 _B , the central peaks have a higher maximum value than shown in Figure 9 in the case of an angular offset of 180 ° for the coil). Thus, in the second embodiment, the sensor is preferably formed by an electromagnetic system comprising the coil 78 and an additional pair of magnets 66 & 67 relative to the magnetic system of the braking device.

By analogy with the first embodiment as described, comparator 52 can also be considered as part of the sensor and not of the measuring device. It will be noted that, in general, an additional pair of magnets is advantageous but not essential, because in another variant the pulses 88 _A and 88 _B can also be used for the power supply of the regulation device and also for the detection of the number of alternations or periods of oscillation of the mechanical resonator. In general, the reference voltage is selected so that, in the useful operating range of the mechanical oscillator, the comparator 52 supplies a first input of the counter CB with a predetermined number of pulses per period of oscillation of the resonator. mechanical, and the clock signal S _H is provided so that it delivers the same number of pulses per setpoint period T0c (inverse of the setpoint frequency F0c) to a second input of the counter CB. This counter CB, as in the first embodiment, outputs a signal corresponding to its state and which gives a measurement of the time drift D _T of the mechanical oscillator relative to the auxiliary oscillator 36.

The state of the counter CB is supplied to two comparators 82 and 84. The first comparator 82 performs a comparison of the state of the counter CB with a first integer N1 greater than zero, to determine whether the measured time drift is greater or not. to this first number N1, and thus detects whether at least a certain advance has occurred in the operation of the mechanical oscillator. The second comparator 84 performs a comparison of this state with a second negative integer -N2, N2 being greater than zero, to determine whether or not the measured time drift is less than this second number -N2, and thus detects whether at least one some delay has occurred in the operation of the mechanical oscillator. The output of the first comparator 82 is supplied to a first frequency generator 42A arranged to generate a first periodic digital signal S _FI at the first frequency F _INF during a correction period each time that this output indicates that the state of the counter CB is greater than the number N1. More particularly, the first generator 42A of the frequency F _INF comprises means arranged to enable it to be activated and then to deactivate it, the signal supplied by the first comparator being supplied to a 'start' input of the first generator to activate it. as soon as this first comparator indicates that the state of the counter CB is greater than the number N1. Similarly, the output of the second comparator 84 is supplied to a second frequency generator 44A arranged to generate a second periodic digital signal S _FS at the second frequency F _SUP during a correction period whenever this output indicates that the state of the counter CB is less than the number -N2. More particularly, the second generator 44A of the frequency F _SUP comprises means arranged to enable it to be activated and then to deactivate it, the signal supplied by the second comparator being supplied to a 'start' input of the second generator to activate it. as soon as the second comparator indicates that the state of the counter CB is less than the number -N2. The first and second periodic digital signals S _FI and S _{FS as} well as the frequencies F _INF and F _SUP have already been described in the context of the first embodiment and present in the second embodiment the same characteristics as in this first embodiment, so that these signals and these frequencies will not be described here again. The control signal S _F is similar to that described in the first embodiment; it is formed by the signal S _FI when the first frequency generator is activated and by the signal S _FS when the second frequency generator is activated.

It is understood that the two frequency generators are never activated simultaneously. The electrical connection point 86 corresponds in practice to an electronic element, for example an 'OR' logic gate, or to an electronic circuit, for example a multiplexer with two or three input positions and a single output (this is so here a switch with two or three inputs). In the case of three input positions, a neutral position is advantageously provided in which the switch is not connected to either of the two frequency generators. As in the first embodiment, the control signal S _F is supplied to a timer 48 which outputs the periodic signal S _P already described above. For each elementary pulse of the signal S _FI or of the signal S _FS , corresponding to a period of the respective frequency, the timer generates an activation pulse of the switch 50 which is here a short-circuit switch of the coil 78. Thus, in each period of the signal S _FI and of the signal S _FS is generated a short-circuit pulse during a time interval distinct from a duration T _P.

A counter at N (referenced CN) also receives the control signal S _F and it counts the number of elementary pulses (number of periods) in this control signal S _F from the start of each correction period. It is therefore reset to zero at the start of any correction period, simultaneously with the activation, as the case may be, of the first or second frequency generator. This counter at N stops the frequency generator which was activated in the correction period considered as soon as it has counted N elementary pulses (i.e. N periods) via a 'Stop' input that each of the two frequency generators comprises, N being an integer greater than one (N> 1). In an advantageous variant, the counter at N is then deactivated until the start of a next correction period. Preferably, the number N is much greater than '1', this number N being for example between 100 and 10,000. In each correction period are therefore generated N short-circuit pulses of coil 78 during N respective distinct time intervals each having a duration T _P.

It will be noted that it is possible to know approximately which time drift D _T (absolute time error) is corrected by a certain number N of short-circuit pulses generated in a correction period, so that it is easy to select a number N which is related to the time drift D _T detected. In a preferred variant where the two frequency differences between the reference frequency F0c and respectively the first frequency F _INF and the second frequency F _SUP are provided to have the same value and where the number N1 is equal to the number N2, the number N is chosen. so that a detected time drift, negative or positive, is substantially corrected during a correction period which follows its detection. The same result can be obtained with a number N1 different from the number N2 if the two above-mentioned frequency differences are not expected to have the same value.

In general, on the basis of the teaching given in the document CH 713 306 , it is understood that, on the one hand, the induced voltage pulses 88 _A generate, if the short-circuit pulses 84 of the coil 78 occur at least partially during these pulses 88 _A , distinct electromagnetic braking pulses which generate negative phase shifts in the oscillation of the mechanical resonator 14A, so that they can generate a delay in the operation of the timepiece to correct an advance. On the other hand, the induced voltage pulses 88 _B generate, if the pulses 84 short-circuit the coil 78 At least partially intervene during these pulses 88 _B , distinct electromagnetic braking pulses which generate positive phase shifts in the oscillation of the mechanical resonator, so that they can generate advance in the operation of the timepiece to correct a delay. It will be noted that an angular offset of 180 ° has the advantage of being very efficient in generating the braking pulses by the short-circuit pulses 84, which makes it possible to effectively correct an advance or a delay in the operation of the motor. timepiece.

As in the first embodiment, during a correction period during which is generated either a first series of braking pulses by a first corresponding series of coil short-circuit pulses, or a second series of braking pulses by a second corresponding series of short-circuit pulses of the coil, a transient phase is observed in a first part of the correction period (longer or shorter depending on the case and in particular depending on the moment at which the first short-circuit pulse of the N short-circuit pulses generated at each correction period) during which the instantaneous frequency of the mechanical oscillator changes from the frequency it has before the correction period in question to the selected correction frequency, namely either the frequency F _INF (N = 2) or the frequency F _SUP (N = 2) as a function of the detected time drift which is corrected. Following the transient phase, a stable phase / synchronous phase occurs in a second part of the correction period. During the synchronous phase, the frequency of the oscillator is synchronized on the selected correction frequency, namely either on the first correction frequency Fcor1 or on the second correction frequency Fcor2. It is therefore observed that, provided that the natural time drift of the timepiece remains within a nominal range for which the electromagnetic braking device of the mechanical resonator has been dimensioned, in each correction period a synchronous phase occurs in which the mechanical oscillator presents the correction frequency selected through the selection of the braking frequency F _INF or F _SUP , and this regardless of the angular position of the balance 16A during a first short-circuit pulse in any one correction period. In the synchronous phase, if no particular external disturbance occurs (for example a shock or a certain acceleration of the balance wheel due to a sudden movement), each short-circuit pulse generates an electromagnetic braking pulse, which is not always the case in the transitional phase.

In the synchronous phase, we observe at the Figure 9 that the short-circuit pulses 84 are wedged between two induced voltage pulses 88 _B and 88 _A surrounding an extreme angular position of the mechanical resonator and two distinct braking pulses occur respectively at the start and at the end of each time interval T _P , these two distinct braking pulses corresponding to two quantities of energy which are taken from the mechanical resonator during a braking pulse corresponding to a short-circuit pulse and which are variable (the variation of one being opposite to the variation of the other, so that if one of the two quantities of energy increases or decreases the other respectively decreases or increases) as a function of the frequency difference between the natural frequency F0 of the mechanical oscillator and the frequency of selected correction and selected braking frequency. Two braking pulses are distinct when they are separated by a time zone having a non-zero duration. By natural frequency F0, we understand the frequency that the mechanical oscillator would naturally present during the correction period considered, that is to say in the hypothetical case of an absence of short-circuit pulses.

It will be noted that, in the definition of the present invention in the descriptive text and the claims, the braking pulses in the second embodiment correspond respectively to the pulses short-circuit which produce them, so that each braking pulse of a first series of braking pulses and of a second series of braking pulses encompasses all of the distinct braking pulses that may occur during the time interval T _P of the corresponding short-circuit pulse. It will also be noted that, in the transient phase, if the time intervals Tp are less than time zones without voltage induced in the coil, it is possible that no braking pulse appears in the initial short-circuit pulses. In the synchronous phase of a correction period, a braking pulse may contain only one distinct braking pulse, which is the case when the time interval T _P has a duration less than those of the time zones without induced voltage located around extreme angular positions. In the advantageous variant shown in Figure 9 , each braking pulse occurring in the synchronous phase of a correction period has two distinct braking pulses, respectively at the start and at the end of each corresponding short-circuit pulse which is generated during a time interval T _P.

The Figure 9 corresponds to a situation where the natural oscillation frequency F0 of the mechanical oscillator is a little lower than the reference frequency F0c, so that the timepiece lags in the absence of regulation. In this case, in each period of oscillation during synchronous phases of successive correction periods for a certain delay in the operation of the timepiece, a first distinct braking pulse, generated in the initial zone of each pulse short-circuit 84 and occurring in the second half-wave A1 ₂ of a first oscillating half-wave A1 (at the start of the separate time intervals Tp), is greater than a second separate braking pulse generated in the zone end of each short-circuit pulse and occurring in the first half-wave A2 ₁ of a second half-wave A2 (at the end of the distinct time intervals T _P ). The first and second pulses of distinct braking are generated respectively by the induced voltage pulses 88 _B and 88 _A during each short-circuit pulse 84 (respectively at the start and at the end of the distinct time intervals T _P ). Thus, in this case, the positive phase shift generated by a voltage pulse 88 _B in a half-wave A1 ₂ is greater than the negative phase shift generated by the voltage pulse 88 _A in the next half-wave A2 ₁ , so that A small correction of the detected delay occurs during each short-circuit pulse.

In the situation where the timepiece advances naturally, the reverse is observed, namely that in the synchronous phase of the correction period, the aforementioned second separate braking pulse is stronger than the first pulse separate braking effect during each short-circuit pulse, so that a small correction of the detected advance occurs during each short-circuit pulse.

Claims (17)

1. Timepiece (2; 3) provided with a mechanical movement (4) which includes:

   - a mechanism (6) for indicating at least one time data item,

   - a mechanical resonator (14; 14A) capable of oscillating around a neutral position corresponding to its state of minimum potential energy, and

   - a device (12) for maintaining the oscillation of the mechanical resonator forming with said mechanical resonator a mechanical oscillator which is arranged to pace the running of the indicator mechanism ;

   the timepiece being also provided with a control device arranged to control the mean frequency of the mechanical oscillator and which includes:

   - a sensor (24; 66, 67, 78) arranged to be capable of detecting a number of periods or vibrations in the oscillation of the mechanical resonator in a useful operating range of the mechanical oscillator,

   - an auxiliary oscillator (23),

   - a braking device (26; 64, 65, 78) which is arranged to be capable of momentarily applying a braking force to the mechanical resonator,

   - a control circuit (22; 74) including a measuring device (DIV1 & DIV2, CB) arranged to be capable of measuring, on the basis of a detection signal (Sc) provided by the sensor, a temporal drift of the mechanical oscillator relative to the auxiliary oscillator, this control circuit being arranged to determine whether a measured temporal drift corresponds to at least a certain gain or to at least a certain loss and if so, to be capable of generating a control signal which selectively activates the braking device as a function of the measured temporal drift in order to generate at least one braking pulse which is applied to the mechanical resonator to at least partially correct the measured temporal drift ;

   characterized in that the control circuit (22; 74) includes a device for generating at least a frequency F_SUP which is arranged to be capable of generating a periodic digital signal at this frequency F_SUP ; and in that, when the control circuit determines a temporal drift corresponding to at least a certain loss in the operation of the timepiece, the control circuit is arranged to be capable of momentarily providing to the braking device a first control signal to activate said braking device such that the braking device generates, during a first correction period, a series of periodic braking pulses which are applied to the mechanical resonator at said frequency F_SUP; this frequency F_SUP and the duration of the first correction period being provided and the braking device being arranged so that the series of periodic braking pulses at frequency F_SUP is capable to generate, in the first correction period, a synchronous phase in which the mechanical oscillator is synchronized to a correction frequency (Fcor2) which is greater than a set point frequency F0c provided for the mechanical oscillator.
2. Timepiece according to claim 1, characterized in that said frequency F_SUP is comprised in a first range of values extending from (M+1)/M to (M+2)/M inclusive multiplied by a frequency F_Z (N) equal to twice the set point frequency F0c divided by a positive integer number N, that is to say [(M+1)/M]·F_Z (N) < F_SUP =< [(M+2)/M]·F_Z (N) where F_Z (N) = 2·F0c/N, M being equal to one hundred times two to the power of K where K is equal to a positive integer number greater than zero and less than thirteen, that is to say 0 < K < 13 and M = 100·2^K, and N being less than M divided by thirty, that is to say N < M/30.
3. Timepiece according to claim 1 or 2, characterized in that said device for generating at least one frequency is a frequency generator device arranged also to be capable of generating a periodic digital signal at a frequency F_INF ; and in that, when the control circuit determines a temporal drift corresponding to at least a certain gain in the operation of the timepiece, the control circuit is arranged to be capable of momentarily providing to the braking device a second control signal to activate said braking device such that the braking device generates, during a second correction period, a series of periodic braking pulses which are applied to the mechanical resonator at said frequency F_INF; this frequency F_INF and the duration of the second correction period being provided and the braking device being arranged so that the series of periodic braking pulses at frequency F_INF is capable to generate, in the second correction period, a synchronous phase in which the mechanical oscillator is synchronized to a correction frequency (Fcor1) which is less than set point frequency F0c.
4. Timepiece according to claim 3, characterized in that said frequency F_INF is comprised in a second range of values extending from (M-2)/M to (M-1)/M inclusive multiplied by the frequency F_Z (N), that is to say [(M-2)/M]·F_Z (N) =< F_INF < [(M-1)/M]·F_Z (N).
5. Timepiece according to claim 3 or 4, characterized in that each time that the measuring circuit determines a temporal drift corresponding to at least a certain gain or to at least a certain loss, the control circuit is arranged to be capable of momentarily providing to the braking device a control signal which is selectively formed by:

   - a first periodic braking device activation signal, which is determined by said periodic digital signal at said frequency F_INF, when the temporal drift corresponds to said at least a certain gain, in order to generate a first series of periodic braking pulses which are applied to the mechanical resonator at said frequency F_INF, and

   - a second periodic braking device activation signal, which is determined by said periodic digital signal at said frequency F_SUP, when the temporal drift corresponds to said at least a certain loss, in order to generate a second series of periodic braking pulses which are applied to the mechanical resonator at said frequency F_SUP.
6. Timepiece according to claim 2 or 4, characterized in that the positive integer number K is greater than two and less than ten, that is to say 2 < K < 10, and the number N is less than the number M divided by a hundred (N < M/100).
7. Timepiece according to any of the preceding claims, characterized in that the braking device (26) is formed by an actuator which includes a mechanical braking member (28) arranged to be actuated, in response to said control signal (S_F), in order to exert, during the braking pulses, a mechanical braking torque on a braking surface (15) of a pivoting balance (16) comprised in the mechanical resonator (14).
8. Timepiece according to claim 7, characterized in that the pivoting balance includes a rim (17) which forms the braking surface, which is circular; and in that the mechanical braking member (28) includes a movable portion which forms a brake pad arranged to be capable of exerting a certain pressure against the circular braking surface (15) during the application of braking pulses to the mechanical resonator.
9. Timepiece according to claim 8, characterized in that the pivoting balance and the mechanical braking member are arranged such that the mechanical braking pulses can be applied mainly by dynamic dry friction between the mechanical braking member and the braking surface.
10. Timepiece according to any of claims 7 to 9, characterized in that the braking surface (15) is configured to allow the braking device to start, in a useful operating range of the mechanical oscillator, a braking pulse of each first series of braking pulses and a braking pulse of each second series of braking pulses in any angular position of the mechanical resonator along said axis of oscillation.
11. Timepiece according to any of the preceding claims, characterized in that the mechanical braking pulses have a duration T_P less than a quarter of a set point period T0c, that is to say T_P < T0c/4, T0c being by definition the inverse of set point frequency F0c.
12. Timepiece according to any of claims 1 to 6, characterized in that the braking device (76) is formed by an electromagnetic system which comprises a coil (78) carried by the mechanical resonator (14A) or a support (5) of said mechanical resonator and at least one permanent magnet (64, 65) respectively carried by said support or said mechanical resonator, the electromagnetic system being arranged such that an induced voltage is generated by said at least one permanent magnet between the two coil terminals (78A, 78B) in each vibration of oscillation of the mechanical resonator for a useful operating range of the mechanical oscillator; and in that the control device is arranged to allow the control circuit to periodically decrease the impedance between the two coil terminals during distinct time intervals (T_P) to generate said first series of periodic braking pulses at the first frequency F_INF and said second series of braking pulses at the second frequency F_SUP.
13. Timepiece according to claim 12, characterized in that the electromagnetic system comprises a pair of bipolar magnets (64, 65) with axial magnetization and opposite polarity, said two bipolar magnets being symmetrically arranged on a balance (16A) with respect to a reference half-axis (62A) of said balance, this reference half-axis defining a zero angular position when the mechanical resonator is in its neutral position; and in that the coil is arranged on said support and has an angular offset relative to the zero angular position such that a voltage induced in said coil occurs substantially, when the mechanical oscillator oscillates in its useful operating range, in each vibration alternately prior to and after the passage of the mechanical resonator through its neutral position in said vibration, the extreme angular positions of the mechanical resonator in said useful operating range being, in absolute value, greater than said angular offset which is defined as the minimum angular distance between the zero angular position and the angular position of the centre of the coil.
14. Timepiece according to claim 13, characterized in that said angular offset is substantially equal to 180°.
15. Timepiece according to claim 13 or 14, characterized in that the electromagnetic braking pulses are generated by a short circuit of the coil during the distinct time intervals (T_P) which are substantially equal to or greater than the maximum duration of time portions with no voltage induced in the coil around the two extreme positions of the mechanical resonator for the useful operating range of the mechanical oscillator.
16. Timepiece according to any of claims 13 to 15, characterized in that the timepiece includes a power supply circuit formed by a storage capacitor (C_AL) and a rectifier circuit for a voltage induced in the coil (78) by at least one permanent magnet (66, 67) carried by the balance (16A) and coupled to the coil.
17. Timepiece according to any of claims 13 to 15, characterized in that the sensor is formed by the coil and at least one permanent magnet (66, 67) carried by the balance and coupled to the coil, said sensor further comprising a comparator (52) receiving, at a first input, a signal (S_B) representative of the voltage induced by said at least one permanent magnet and, at a second input, a reference voltage, the latter being selected such that the comparator supplies to a bidirectional counter (CB) of the measuring device a predetermined number of pulses per oscillation period of the mechanical oscillator for the useful operating range of said mechanical oscillator.

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