EP3339982B1 - Regulation by mechanical breaking of a horological mechanical oscillator - Google Patents

Description

Technical area

• un mécanisme, lequel forme notamment en partie un mouvement mécanique,
• un résonateur mécanique susceptible d'osciller le long d'un axe d'oscillation autour d'une position neutre correspondant à son état d'énergie mécanique potentielle minimale,
• un dispositif d'entretien du résonateur mécanique formant avec ce dernier un oscillateur mécanique agencé pour cadencer la marche du mécanisme, chaque oscillation du résonateur mécanique présentant deux alternances successives entre deux positions extrêmes sur l'axe d'oscillation qui définissent l'amplitude d'oscillation de l'oscillateur mécanique,
• un dispositif de régulation agencé pour réguler la fréquence de l'oscillateur mécanique, ce dispositif de régulation comprenant un oscillateur auxiliaire, généralement plus précis que ledit oscillateur mécanique, et un dispositif agencé pour appliquer sur commande des impulsions de régulation au résonateur mécanique qui le freinent momentanément.

The present invention relates to a watch assembly, in particular a timepiece, comprising:

• a mechanism, which in particular partly forms a mechanical movement,
• a mechanical resonator capable of oscillating along an axis of oscillation around a neutral position corresponding to its state of minimum potential mechanical energy,
• a device for maintaining the mechanical resonator forming with the latter a mechanical oscillator arranged to rate the operation of the mechanism, each oscillation of the mechanical resonator having two successive alternations between two extreme positions on the axis of oscillation which define the amplitude of oscillation of the mechanical oscillator,
• a regulating device arranged to regulate the frequency of the mechanical oscillator, this regulating device comprising an auxiliary oscillator, generally more precise than said mechanical oscillator, and a device arranged to apply regulation pulses on command to the mechanical resonator which slow it down momentarily.

In particular, the mechanical resonator is a sprung balance and the maintenance device comprises a conventional escapement, for example with a Swiss lever. The auxiliary oscillator is formed in particular by a quartz resonator or by a resonator integrated in an electronic circuit.

Technological background

Movements forming watch assemblies as defined in the field of the invention have been proposed in a few documents. earlier. the patent CH 597 636, published in 1977 , offers such a movement in reference to its figure 3 . The movement is equipped with a resonator formed by a sprung balance and a conventional maintenance device comprising an anchor and an escape wheel in kinematic connection with a barrel provided with a spring. This watch movement comprises a device for regulating the frequency of the mechanical oscillator. This regulation device comprises an electronic circuit and a magnetic assembly formed of a flat coil, arranged on a support under the rim of the balance, and two magnets mounted on the balance and arranged close to each other so as to both pass over the coil when the oscillator is on.

The electronic circuit comprises a time base comprising a quartz resonator and serving to generate a reference frequency signal FR, this reference frequency being compared with the frequency FG of the mechanical oscillator. The detection of the FG frequency of the oscillator is carried out via the electrical signals generated in the coil by the pair of magnets. The regulation circuit is designed to be able to momentarily generate a braking torque via a magnet-coil magnetic coupling and a switchable load connected to the coil. The document CH 597 636 gives the following teaching: "The resonator thus formed must have a variable oscillation frequency according to the amplitude on either side of the frequency FR (isochronism defect)". It is therefore taught that a variation in the oscillation frequency of a non-isochronous resonator is obtained by varying its oscillation amplitude. An analogy is made between the amplitude of oscillation of a resonator and the angular speed of a generator comprising a rotor provided with magnets and arranged in a cog of the watch movement in order to regulate its rate. As a braking torque decreases the speed of rotation of such a generator and thus its frequency of rotation, it is only envisaged here to be able to reduce the oscillation frequency of a necessarily non-isochronous resonator by applying a torque. brake reducing its amplitude of oscillation.

In order to effect electronic regulation of the frequency of the generator, respectively of the mechanical oscillator, provision is made in a given embodiment for the load to be formed by a switchable rectifier via a transistor which charges a storage capacitor during the pulses of braking, to recover electrical energy in order to supply the electronic circuit. The constant teaching given in the document CH 597 636 is the following: When FG> FR the transistor is conducting; a power Pa is then taken from the generator / oscillator. When FG <FR, the transistor is non-conductive; no more energy is therefore taken from the generator / oscillator. In other words, one regulates only when the frequency of the generator / of the oscillator is higher than the reference frequency FR. This regulation consists in braking the generator / oscillator in order to reduce its frequency FG. Thus, in the case of the mechanical oscillator, a person skilled in the art understands that regulation is only possible when the barrel spring is strongly armed and the free oscillation frequency (natural frequency) of the oscillator mechanical is greater than the reference frequency FR, as a result of a desired isochronism defect of the selected mechanical oscillator. We therefore have a double problem, namely the mechanical oscillator is selected for what is normally a fault in a mechanical movement and the electronic regulation is only functional when the natural frequency of this oscillator is greater than a nominal frequency.

In conclusion, the teaching generally given to those skilled in the art is as follows: If we want to electronically regulate the frequency of a sprung balance of a classic watch movement, we must change the sprung balance to first arrange at least a magnet on it and secondly to modify its natural frequency so that this natural frequency is higher than the desired frequency. The consequence of such a teaching is clear: We must deregulate the mechanical resonator so that it oscillates at too high a frequency so as to allow the regulating device to constantly bring its frequency back to a frequency lower, corresponding to the desired theoretical frequency, by a succession of braking pulses. Consequently, the resulting watch movement is deliberately adjusted so that a precise rate depends on electronic regulation, otherwise such a watch movement would have a very significant time drift. Thus, if for one reason or another the regulating device is deactivated, in particular due to deterioration, then the watch equipped with such a movement will no longer be precise, and this to such an extent that it is in fact no longer precise. more functional. Such a situation is problematic.

The document EP 1 214 538 discloses a watch movement comprising a mechanical oscillator and a device for correcting the rate of this watch movement. The correction device comprises an electromagnetic braking system for the spring balance of the mechanical oscillator, this electromagnetic braking system being formed of a plurality of magnets arranged circularly on the balance and a plurality of coils arranged on the plate. of the watch movement so as to be able to present a magnetic coupling with the magnets. The correction device comprises a device for determining the duration of a setpoint period and a device for determining the duration of a period of oscillation of the mechanical oscillator. A circuit is provided to be able to measure the time difference between the setpoint period and the oscillation period. Depending on the result and in particular on the mathematical sign of this difference which indicates whether the mechanical oscillator has an instantaneous frequency that is too high or too low, an electromagnetic braking pulse is generated via the coils respectively before or after the oscillator passes through its central position.

The use of an electromagnetic system of the magnet-coil type to couple the sprung balance with the electronic regulation circuit gives rise to various problems. First, the arrangement of permanent magnets on the balance wheel results in a magnetic flux being constantly present in the watch movement and that this magnetic flux varies spatially periodically. Such a magnetic flux can have a harmful action on various organs or elements of the watch movement, in particular on elements made of magnetic material such as parts made of ferromagnetic material. This can have repercussions on the proper functioning of the watch movement and also increase wear of pivoted elements. We can certainly think of shielding the magnetic system in question to a certain extent, but shielding requires special elements which are carried by the balance. Such shielding tends to increase the size of the mechanical resonator and its weight. In addition, it limits the possibilities of sleek aesthetic configurations. In addition, a strong external magnetic field can damage the magnetic elements of the electromagnetic system.

Those skilled in the art are aware of proposals for making mechanical horological movements, comprising a device for regulating the frequency of the sprung balance, in which provision is made to act on the oscillating balance by an electromechanical system formed, on the one hand, by a stop which is arranged on the balance and, on the other hand, by an actuator provided with a movable finger which is actuated at a determined braking frequency in the direction of the stop. This concept aims to synchronize the frequency of the oscillator on that of a crystal oscillator by an alleged interaction between the finger and the stopper when the mechanical oscillator exhibits a time drift relative to the crystal oscillator, the finger coming from either momentarily block the balance which is then stopped in its movement for a certain time interval (the stop pressing against the finger moved in its direction during the return of the balance towards its neutral position), or limit the amplitude of oscillation when the finger comes up against the stop while the balance turns towards its position of maximum amplitude.

Such a control system has many drawbacks and one can seriously doubt that it can form a functional system. The 'blind' action of the finger relative to the movement of the stopper and to any potential initial phase shift of the oscillation of the stopper with respect to that of the finger poses many problems. In addition, the action is limited to an angular position given by the position of the actuator relative to the sprung balance. Thus, the effect of the interaction between the finger and the stopper depends on the amplitude of oscillation of the sprung balance and on the position of the actuator. In conclusion, such achievements appear to a person skilled in the art as highly improbable, and such a person skilled in the art shies away from such teaching. Moreover, the present inventors are not aware of watches equipped with such an electromechanical system which would have been placed on the market.

Summary of the invention

An aim of the present invention is to find a solution to the technical problems and drawbacks mentioned above in the technological background.

A first objective, within the framework of the development which led to the present invention, was to provide a watch assembly comprising a mechanical movement, with a conventional mechanical resonator of the sprung balance type, and a regulation device which does not use a system. coil magnet for coupling the mechanical resonator to this regulation device, in particular which does not require arranging at least one permanent magnet on the balance. It will be noted that, in the context of the description of the present invention, such a magnet-coil system generates magnetic braking pulses, a magnetic flux generated by at least one coil being coupled to the magnetic flux of said at least one permanent magnet on board. the mechanical resonator.

A second objective, within the framework of the development which led to the present invention, was to produce a watch assembly comprising a mechanical movement with a mechanical oscillator and a device for regulating this mechanical oscillator, but without having to initially adjust the mechanical oscillator. , to have a timepiece which has the precision of an auxiliary electronic oscillator (in particular fitted with a quartz resonator) when the regulating device is functional and the precision of the mechanical oscillator when this regulating device is deactivated or off, but with a precision which may correspond to the best standard in the latter case. In other words, an attempt is made to add electronic regulation to a mechanical movement which is moreover regulated as precisely as possible so that it remains functional, with the best possible operation, when the electronic regulation is inactive.

Another object of the present invention is to provide a watch assembly which meets at least the first objective and which is robust, that is to say which can maintain high precision even after an external disturbance such as a shock.

To this end, the present invention relates to a watch assembly as defined in claim 1, as well as to a regulation module as defined in claim 16. Various embodiments and variants are the subjects of the dependent claims.

The term “mechanical braking pulse” is understood to mean braking of a mechanical nature and not only a mechanical effect resulting from the braking. Thus, this expression excludes in the first sense given to it a contactless braking via an electromechanical coupling between a stationary coil and at least one magnet mounted on the mechanical resonator, because in the latter case, the braking is magnetic and operated through of an electromagnetic system, one element of which, namely said at least one magnet, is fixed to an oscillating member of the mechanical resonator, thus changing the conventional arrangement of the oscillating member, for example a balance. Admittedly, the final effect of magnetic braking is a reduction in the mechanical energy of the oscillating member, but the braking is not mechanical in its nature. The aforementioned expression also excludes a braking resulting from an electrical coupling between the oscillating member and a stationary unit of the regulating device. On the other hand, obviously, this expression does not exclude electrical and / or magnetic elements incorporated in the electromechanical device which generates mechanical braking pulses applied to the mechanical resonator. On the contrary, the term 'electromechanical' indicates that at least one electrical element forms the device for applying regulating pulses.

Thanks to the characteristics of the invention, it is possible to add to a basic mechanical movement a module for regulating its mechanical oscillator (comprising a sprung balance) without having to modify this basic mechanical movement. This is a great advantage. In particular, the watch assembly according to the invention can be produced without having to vary the kinematic properties of the mechanical oscillator. If necessary, a surface treatment (generally partial) of the balance can be provided for the operation of the sensor. Such processing may be limited to affixing a black dot on an arm of the balance or under the rim of this balance in the case of an optical sensor. Thus, the design of the basic mechanical movement does not have to be changed in order to produce a watch assembly according to the invention. In a first case where the watch assembly is produced entirely as new, it is therefore possible to take an existing caliber which has already proved its worth in production and associated with it an additional regulation module according to the invention, by arranging the corresponding watch movement on the periphery. to this caliber the regulation module so as to allow the application of mechanical braking pulses to the mechanical resonator. It is at the level of the cladding of the watch assembly that it may be necessary to provide an adaptation to allow the incorporation of the additional regulation module. In a second case, the watch assembly according to the invention is formed by a basic watch movement already placed, initially, on the market in a watch and to which is added, in a second stage, a regulation module according to invention to increase its precision. An adaptation to the level of the watch casing may prove to be necessary, but is not necessarily obligatory. For example, machining at the level of a casing circle may prove to be sufficient to allow the incorporation of the watch assembly in the watch case already in the possession of a user, that is to say with the addition of a regulation module according to the invention, the subject of the appended claims.

According to a main embodiment, the measuring device is arranged to determine whether the time drift of the mechanical oscillator corresponds to at least one advance or to at least one delay. Then, the control circuit and the regulation pulse application device are arranged to be able to selectively apply to the mechanical resonator, when the measured time drift corresponds to a certain advance, a first mechanical braking pulse, at least a major part of which occurs between the initial instant and the median instant of an alternation (first half-wave) and, when the measured time drift corresponds to a certain delay, a second mechanical braking pulse, at least a major part of which occurs between the median instant and the final instant of an alternation (second half-alternation). It will be noted that each period of oscillation of the mechanical oscillator defines a first half-wave followed by a second half-wave and each half-wave has a passage of the mechanical resonator through its neutral position at said middle instant.

Thus, in summary, the control circuit and the regulation pulse application device are arranged to selectively apply to the mechanical resonator, when the measured time drift corresponds to a certain advance, a mechanical braking pulse in a first half. alternation of the oscillation of the mechanical resonator and, when the measured time drift corresponds to a certain delay, a mechanical braking pulse in a second half-wave.

In a main variant, the regulation device comprises a device for determining the temporal positions of the mechanical resonator which is arranged to be able to determine, in an alternation of an oscillation of the mechanical resonator, a first instant which occurs before the median instant and after. the initial moment of this alternation and, also in a alternation of an oscillation of this mechanical resonator, a second instant which occurs after the median instant and before the final instant of this alternation. Then, the control circuit is arranged to be able to selectively trigger a first mechanical braking pulse substantially at the first instant and a second mechanical braking pulse substantially at the second instant. Finally, the braking surface of the mechanical resonator comprises a first sector, along its axis of oscillation, for the application of the first mechanical braking pulse starting substantially at the first instant and a second sector, along the axis. oscillation, for the application of the second mechanical braking pulse starting substantially at the second instant, regardless of the oscillation amplitude of the mechanical oscillator in its useful operating range.

Brief description of the figures

• La Figure 1 est une vue de dessus d'un ensemble horloger selon l'invention,
• La Figure 2 montre un premier mode de réalisation d'un dispositif de régulation pour réguler la fréquence d'oscillation d'un balancier-spiral d'un ensemble horloger selon l'invention,
• La Figure 3 montre le signal de position fourni par un capteur détectant le passage du balancier-spiral par sa position neutre et l'application d'une première impulsion de freinage dans une certaine alternance avant que le balancier-spiral passe par sa position neutre, ainsi que la vitesse angulaire du balancier et sa position angulaire dans un intervalle temporel au cours duquel intervient la première impulsion de freinage,
• La Figure 4 est une figure similaire à celle de la Figure 3 avec l'application d'une deuxième impulsion de freinage dans une certaine alternance après que le balancier-spiral a passé par sa position neutre,
• La Figure 5 montre le schéma électronique d'un deuxième mode de réalisation du dispositif de régulation de l'oscillateur mécanique selon l'invention,
• La Figure 6 est un organigramme d'un mode de fonctionnement du dispositif de régulation de la Figure 5,
• La Figure 7 montre le schéma électronique d'une variante du deuxième mode de réalisation du dispositif de régulation de l'oscillateur mécanique,
• La Figure 8 montre deux signaux digitaux intervenant dans le circuit électronique de la Figure 7,
• La Figure 9 est un organigramme d'un mode de fonctionnement du dispositif de régulation de la Figure 7,
• La Figure 10 montre un troisième mode de réalisation d'un dispositif de régulation selon l'invention, et
• La Figure 11 montre un mode de réalisation particulier du dispositif de freinage d'un dispositif de régulation selon l'invention.

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 is a top view of a watch assembly according to the invention,
• The Figure 2 shows a first embodiment of a regulating device for regulating the oscillation frequency of a sprung balance of a watch assembly according to the invention,
• The Figure 3 shows the position signal supplied by a sensor detecting the passage of the sprung balance through its neutral position and the application of a first braking pulse in a certain alternation before the sprung balance passes through its neutral position, as well as the angular speed of the balance and its angular position in a time interval during which the first braking pulse occurs,
• The Figure 4 is a figure similar to that of the Figure 3 with the application of a second braking pulse in a certain alternation after the sprung balance has passed through its neutral position,
• The Figure 5 shows the electronic diagram of a second embodiment of the device for regulating the mechanical oscillator according to the invention,
• The Figure 6 is a flowchart of an operating mode of the device for regulating the Figure 5 ,
• The Figure 7 shows the electronic diagram of a variant of the second embodiment of the device for regulating the mechanical oscillator,
• The Figure 8 shows two digital signals intervening in the electronic circuit of the Figure 7 ,
• The Figure 9 is a flowchart of an operating mode of the device for regulating the Figure 7 ,
• The Figure 10 shows a third embodiment of a regulation device according to the invention, and
• The Figure 11 shows a particular embodiment of the braking device of a regulating device according to the invention.

Detailed description of the invention

To the Figure 1 is shown a watch assembly 2 according to the present invention. It comprises a mechanical watch movement 4 which is formed at least by a mechanism comprising a gear train 10 driven by a mainspring arranged in a barrel 8 (this mechanism is shown partially in Figure 1 ). The watch movement comprises a mechanical resonator 14, formed by a balance 16 and a hairspring 18, and a device for maintaining the mechanical resonator forming with this mechanical resonator a mechanical oscillator which controls the operation of the mechanism. The maintenance device comprises an escapement 12, formed here by an anchor and an escape wheel which is kinematically connected to the barrel via of the gear train 10. The mechanical resonator is capable of oscillating along an axis of oscillation, in particular a circular axis, around a neutral position corresponding to a state of minimum mechanical potential energy. Each oscillation of the mechanical resonator defines an oscillation period.

The watch assembly 2 further comprises a device 6 for electronically regulating the frequency of the mechanical oscillator, this regulating device comprising an electronic regulating circuit 22 associated with an auxiliary oscillator formed by a quartz resonator 23. It will be noted that d 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 device 6 also comprises a sensor 24 for detecting at least one angular position of the balance when it oscillates and a device 26 for applying regulating pulses to the mechanical resonator 14. Finally, the watch assembly comprises a source of energy. 28 associated with a device 26 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 being in no 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 6 comprises in its regulation circuit an electronic control circuit arranged to generate a control signal, which is supplied to the regulation pulse application device which is arranged so as to be able to generate, in response to this control signal, successive regulation pulses each exerting a certain force torque on the mechanical resonator. According to the invention, 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 position relative to a support of this mechanical resonator. Preferably, the sensor is arranged to detect at least the passage of the mechanical resonator by its neutral position. It will be noted that, in this preferred 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 resonator passes through. its neutral position.

The detection of the neutral point of the resonator makes it possible to generate a useful and stable time reference within the oscillations. Indeed, in the absence of disturbances (in particular caused by the braking pulses provided for the regulation), the passage through the neutral point always occurs exactly in the middle of the half-waves, independently of the oscillation amplitude. On the other hand, the detection of another angular position of the balance does not give a stable and well-defined time reference, in particular in relation to the events of the passage of the sprung balance through its neutral position and the start or end of the vibrations, to know the times when the balance is at maximum amplitude and at zero angular speed (corresponding to the reversal of the direction of oscillation). In addition, as the angular speed of the sprung balance is maximum during its passage through its neutral position, the precision of this detection and thus the detection of the corresponding instant are better. The benefit of the detection of the passage of the sprung balance through its neutral position during the presentation of the preferred regulation method, which will be made with reference to the following, will be better understood later. Figures 3 and 4 , and the following embodiments.

In general, the regulation device 6 also comprises a measuring device arranged to measure, on the basis of position signals supplied by the sensor, a time drift of the mechanical oscillator relative to the auxiliary oscillator. It will be understood that such a measurement is easy when a sensor capable of detecting the passage of the mechanical resonator through its neutral point is provided. Such an event occurs every half-cycle of oscillation of the mechanical oscillator. The measurement circuit will be described in more detail below.

The device 26 for applying regulating pulses is arranged to be able to apply to the balance 16 mechanical braking pulses to regulate the frequency of the mechanical oscillator when a certain time drift of this mechanical oscillator is observed. In a particular variant, the braking energy which is taken from the mechanical resonator by any mechanical braking pulse is provided less than the blocking energy of the mechanical oscillator, in order not to temporarily stop the oscillation movement. of the mechanical resonator during the regulation pulses. Blocking energy is normally defined as the kinetic energy of the mechanical resonator at the start of the braking pulse minus the difference in potential energy of this mechanical resonator between the end and the start of the braking pulse in question. , provided that the mechanical oscillator does not receive any sustaining energy during this braking pulse. In this particular variant, therefore, it is a question of reducing, during the braking pulse, the angular speed of the sprung balance without stopping it for a longer or shorter time. It will be noted that in order to guarantee the correct functioning of the Swiss lever escapement of a usual horological oscillator, it is preferable that the braking impulses do not take place during the tilting of the anchor, tilting during which a contribution intervenes. maintenance energy of the oscillator. As the tilting of the anchor generally takes place around the neutral position of the mechanical resonator, one will therefore avoid disturbing by a braking pulse the oscillating movement of the sprung balance as it passes through this neutral position.

According to a first embodiment shown in Figure 2 , the device for applying regulating pulses comprises an actuator 36 having a movable braking member 38, which is actuated in response to a control signal so as to exert on the oscillating member, here the balance, of the mechanical resonator a certain mechanical force during mechanical braking pulses. The actuator 36 comprises a piezoelectric element supplied by a circuit 39 which generates an electric voltage as a function of a control signal supplied by the regulation circuit 22. When the piezoelectric element is momentarily energized, the braking member comes into contact with a braking surface of the balance to brake it. In the example shown in Figure 2 , the blade 38 forming the braking member is curved and its end part presses against the circular lateral surface 40 of the rim 17 of the balance 16. Thus, the rim 17 defines, at least over a certain angular sector, a substantially circular braking surface. Then, the braking member comprises a movable part, here the end part of the blade, which defines a braking shoe arranged so as to exert pressure against the substantially circular braking surface during the application of the pulses. mechanical braking. Preferably, it is provided within the scope of the present invention that the oscillating member and the braking member are arranged so that the mechanical braking pulses are applied by dynamic dry friction or viscous friction between the control member. braking and a braking surface of the oscillating member.

In an advantageous variant (not shown), the balance comprises a central shaft which defines, respectively which carries a part other than the rim of the balance defining, at least over a certain angular sector, 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. Then, the correction generated by a braking pulse can be precisely managed, in particular by an appropriate selection of its duration and by the braking force torque applied. It is also possible, in particular by virtue of the position measurement carried out by the sensor, to determine the instants during the alternations for applying the braking pulses. Thus, at least the braking torque, the duration of the pulses and the respective instants at which they are generated can be selected and vary as a function of the time drift of the mechanical oscillator. In particular, it is thus possible to generate small corrections for fine and precise regulation of the oscillation frequency.

Note that the oscillation amplitude generally varies depending on the degree of winding of the barrel (unless a specific device to produce a constant force is provided). Thus, at a given non-zero instant before or after the resonator has passed through its neutral position in any alternation of its oscillation movement, the angular position of the balance varies as a function of the amplitude of oscillation. If one chooses for example to give braking pulses to regulate the oscillation frequency always at a fixed time interval determined before or after the resonator passes through its neutral position (see the preferred regulation principle explained below), the braking surface must then extend over a certain angular length so that the pad can in all cases exert a braking force on the balance at different angular positions along this braking surface. Thus, the mechanical resonator has a braking surface which extends over at least a certain angular sector having a certain angular length which is not zero (that is to say that an angular sector is considered to be non-point), to allow the application of mechanical braking pulses at least at some given time in the oscillation periods of the mechanical oscillator, whatever the amplitude of oscillation of the mechanical resonator for a useful operating range of the mechanical oscillator.

It will be noted that, according to the aforementioned time interval or according to a time range chosen to apply braking pulses before or after the instants of passage of the mechanical resonator through its neutral position in various alternations of its oscillation movement, instants which are detected by the sensor 34, it suffices that two determined angular sectors of the balance have or respectively define two circular surfaces for the shoe of the braking member so that the braking pulses can be applied within a useful operating range of the oscillator mechanical, that is to say over a certain angular range useful for the amplitude of its oscillations (for example between 200 ° and 300 °). In general terms, provision is made for the braking surface of the mechanical resonator to include at least a first angular sector for the application, in alternations, of first mechanical braking pulses substantially at a first instant situated before the median instant of passage. of the mechanical resonator by its neutral position and a second angular sector for the application, in alternations, of second mechanical braking pulses substantially at a second instant located after the median instant, whatever the amplitude of oscillation of the resonator mechanical in a useful operating range of the mechanical oscillator considered. It will be noted that, in a specific case where the first instant and the second instant are provided in the alternations at the same temporal distance from the median instant and on the same side of the neutral position, the first and second angular sectors are substantially coincident and define thus one and the same angular braking sector. In other cases, the first and second angular sectors have a common part or are distinct. The same considerations apply to a first time interval and a second time interval in which can be provided to apply the first and second braking pulses respectively. In the variant shown in Figure 2 , the braking surface has an extent allowing the application of mechanical braking pulses at any time of the oscillations of the mechanical resonator.

It will also be noted that the shoe of the braking member can also have a circular contact surface, of the same radius as the braking surface, but such a configuration is not required. The contact surface may in particular be flat, as shown in the figures. A flat surface has the advantage of leaving a certain margin in the positioning of the braking member relative to the balance, which makes it possible to have greater tolerances in the manufacture and assembly of the braking device in the or at the periphery of the watch movement.

The sensor 34 is an optical sensor of the photoelectric type. It 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 whose intensity varies periodically as a function of the position of the balance. In the schematic example shown in Figure 2 , the beam is sent to the lateral surface of the rim 17, this surface having a limited area with a reflectivity different from the two neighboring areas, so that the sensor can detect the passage of this limited area and provide the regulating device with a signal position 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 or to the start, respectively to the end of such a signal. We therefore understand that the modulation of the light signal, which can consist of a succession of light pulses received in return by the photo-detector, can define the angular position of the balance in various ways, 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 inductive sensor preferably operates without the presence of magnetized material on the resonator, for example by detecting the presence of a non-magnetic material or simply of a variation in distance between such material and the sensor. Those skilled in the art are aware of numerous sensors which can easily be incorporated into the watch assembly according to the invention.

Advantageously, the various elements of the regulation device 6 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.

Hereinafter, with reference to Figures 3 and 4 , a regulation method which constitutes a remarkable improvement of the invention, then embodiments of watch assemblies according to the invention in which this very advantageous regulation method is implemented.

The Figure 3 shows four graphs. The first graph gives the digital signal supplied over time by the sensor 34 when the resonator 14 oscillates, that is to say when the mechanical oscillator of the watch assembly is activated. It will be noted that the digital signal can be supplied in a first variant directly by the sensor, but in a second variant the sensor provides an analog signal and it is the regulation circuit which converts it into a digital signal, in particular by means of a comparator. As explained above, the sensor and the balance are arranged so as to allow the sensor to detect the successive passages of the sprung balance through its neutral position. Such an event occurs twice per period of oscillation, once in each of the two half-waves at an instant tzn at which the sensor supplies a pulse 42.

Each period of oscillation of the mechanical oscillator defines a first alternation followed by a second alternation between two extreme positions defining the amplitude of oscillation of this mechanical oscillator, each alternation having a passage of the mechanical resonator through its neutral position to a median instant t _Zn and a duration between an initial instant t _An-1 , respectively t _D1 for the alternation A1 at the Figure 3 and t _D2 for the alternation A2 at the Figure 4 , and a final instant t _An , respectively t _F1 for the alternation A1 at the Figure 3 and t _F2 for the alternation A2 at the Figure 4 . These initial and final instants are defined respectively by the two extreme positions occupied by the mechanical resonator respectively at the start and at the end of each half-wave. The second graph indicates the instant t _{P1 at} which a braking pulse is applied to the mechanical resonator 14 in order to make a correction in the operation of the mechanism clocked by the mechanical oscillator. The instants at which rectangular shaped pulses (i.e. of a binary signal) occur are defined at Figures 3 and 4 by the temporal positions of the middle of these pulses. However, one can also consider, according to the variant and the embodiment of the regulation circuit, the start or the end of a pulse as the instant which characterizes it, namely either the rising edge or the falling edge of this pulse. This is particularly the case for the braking pulses, the start of which (that is to say the triggering) and the duration of which are generally determined.

There is a variation in the oscillation period during which the braking pulse occurs and therefore a punctual variation in the frequency of the mechanical oscillator. In fact, as we see on the last two graphs of the Figure 3 , which show respectively the angular speed (values in radians per second: [rad / s]) and the angular position (values in radians: [rad]) of the balance over time, the temporal variation concerns the only alternation during which intervenes the braking impulse. It will be noted that each oscillation has two successive alternations which are defined in the present text as the two half-periods during which the balance wheel respectively undergoes an oscillating movement in one direction and then an oscillating movement in the other direction. In other words, an alternation corresponds to a swing of the balance in one direction or the other direction between its two extreme positions defining the amplitude of oscillation.

By braking pulse, one understands an application, substantially during a limited time interval, of a certain torque of force to the mechanical resonator which brakes it, that is to say of a torque of force which opposes the oscillation movement of this mechanical resonator. In the context of the invention, each braking pulse is generated by mechanical braking which exerts a mechanical braking torque on the mechanical resonator, as shown in the third graph representing the angular speed of the balance.

In the Figures 3 and 4 , the oscillation period T0 corresponds to a "free" oscillation (that is to say without application of regulation pulses) of the mechanical oscillator of the watch assembly. The two half-waves of an oscillation period each have a duration T0 / 2 without disturbance or external constraint (in particular by a regulation pulse). The time t = 0 marks the start of a first alternation. It will be noted that the 'free' frequency F0 of the mechanical oscillator is here approximately equal to four Hertz (F0 = 4 Hz), so that the period T0 = approximately 250 ms.

We will first describe the behavior of the mechanical oscillator in a first case of correction of its oscillation frequency, which corresponds to that shown in Figure 3 . After a first period T0 then begins a new period T1, respectively a new alternation A1 during which a braking pulse P1 occurs. At the initial instant t _D1 the alternation A1 begins, the resonator 14 occupying a maximum positive angular position corresponding to an extreme position. Then comes the braking pulse P1 at the instant t _P1 which is situated before the median instant t _{N1 at} which the resonator passes through its neutral position. Finally, the alternation A1 ends at the final instant t _F1 . The braking pulse is triggered after a time interval T _A1 following the last median instant t _Zn detected by the sensor before the alternation A1. The duration T _A1 is selected to be greater than one half-wave T0 / 4 and less than one half-wave T0 / 2 reduced by the duration of the braking pulse P1. In the example given, the duration of this braking pulse is much less than one half-wave T0 / 4. By median instant ', we understand an instant occurring substantially in the middle of the alternations. This is precisely the case when the mechanical oscillator oscillates freely. On the other hand, for the half-waves during which regulation pulses are supplied, it will be noted that this median instant no longer corresponds exactly to the middle of the duration of each of these half-waves due to the disturbance of the mechanical oscillator generated by the device. regulation.

In this first case, the braking pulse is generated between the start of an alternation and the passage of the resonator through its neutral position in this alternation. As expected, the angular speed in absolute value decreases at the moment of the braking pulse P1. Such a braking pulse induces a negative temporal phase shift T _C1 in the oscillation of the resonator, as shown by the two graphs of the angular speed and of the angular position at the Figure 3 , or a delay relative to the theoretical undisturbed signal (shown in broken lines). Thus, the duration of the alternation A1 is increased by a time interval Tci. The period of oscillation T1, comprising the alternation A1, is therefore prolonged relative to the value T0. This causes a punctual reduction in the frequency of the mechanical oscillator and a momentary slowing down of the rate of the associated mechanism.

With reference to the Figure 4 , the behavior of the mechanical oscillator will be described below in a second case of correction of its oscillation frequency. The graphs of this Figure 4 show the temporal evolution of the same variables as at the Figure 3 . After a first period T0 then begins a new oscillation period T2, respectively an alternation A2 during which a braking pulse P2 occurs. At the initial instant t _D2, the alternation A2 begins, the mechanical resonator then being in an extreme position (maximum negative angular position). After a quarter of a period (T0 / 4) corresponding to a half-wave, the resonator reaches its neutral position at the median instant t _N2 . Then comes the braking pulse P2 at the instant t _P2 which is located after the median instant t _{N2 at} which the resonator passes through its neutral position in the halfwave A2. Finally, after the braking pulse P2, this alternation A2 ends at the final instant t _{F2 at} which the resonator again occupies an extreme position (maximum positive angular position in the period T2). The braking pulse is triggered after a time interval T _A2 following the median instant t _N2 of the halfwave A2. The duration T _A2 is selected to be less than one half-wave T0 / 4 reduced by the duration of the braking pulse P2. In the example given, the duration of this braking pulse is much less than half a wave.

In the second case considered, the braking pulse is therefore generated, in an alternation, between the median instant at which the resonator passes through its neutral position and the final instant at which this alternation ends and at which the resonator occupies an extreme position . As expected, the angular speed in absolute value decreases at the moment of the braking pulse P2. Remarkably, the braking pulse here induces a positive temporal phase shift T _C2 in the oscillation of the resonator, as shown by the two graphs of the angular speed and of the angular position at the Figure 4 , or an advance relative to the theoretical undisturbed signal (shown in broken lines). Thus, the duration of the alternation A2 is reduced by the time interval T _C2 . The oscillation period T2 including the alternation A2 is therefore shorter than the value T0. This consequently generates a punctual increase in the frequency of the mechanical oscillator and a momentary acceleration of the rate of the associated mechanism. This phenomenon is surprising and not intuitive, which is why those skilled in the art have ignored it in the past.

This regulation process is remarkable in that it takes advantage of a surprising physical phenomenon of mechanical oscillators. The inventors arrived at the following observation: Contrary to general teaching in the watchmaking field, it is not only possible to decrease the frequency of a mechanical oscillator by braking pulses, but it is also possible to increase the frequency of such a mechanical oscillator also by braking pulses. A person skilled in the art expects to be able to practically only reduce the frequency of a mechanical oscillator by braking pulses and, as a corollary, to be able only to be able to increase the frequency of such a mechanical oscillator by the application of driving pulses. when energy is supplied to this oscillator. Such an intuition, which has imposed itself in the watchmaking field and therefore comes first on board in the mind of a person skilled in the art, turns out to be false for a mechanical oscillator. Although such behavior is correct for a micro-generator, whose rotor rotates continuously in the same direction, this is on the other hand not true for a mechanical oscillator because it oscillates.

Indeed, it is possible to regulate electronically, via an auxiliary oscillator comprising for example a quartz resonator, an otherwise very precise mechanical oscillator, which it momentarily presents a frequency slightly too high or too low. To do this, provision is made to select the right moment, as a function of the rate of the mechanism in question and therefore of the frequency of the mechanical oscillator which punctuates this rate, for applying a mechanical braking pulse. The inventors have observed that the effect produced by a regulation pulse on a mechanical resonator depends on the moment when it is applied in an alternation relative to the moment when this mechanical resonator passes through its neutral position. According to this principle brought to light by the inventors and used in a watch assembly according to the invention, a braking pulse applied, in any alternation between the two extreme positions of the mechanical resonator, substantially before the passage of the mechanical resonator through its neutral position (rest position) produces a negative temporal phase shift in the oscillation of this resonator and therefore a delay in the operation of the mechanism clocked by the resonator, while a braking pulse applied in this alternation substantially after the passage of the mechanical resonator through its neutral position produces a positive temporal phase shift in the oscillation of this resonator and therefore an advance in the operation of the mechanism. It is thus possible to correct too high a frequency or too low a frequency only by means of braking pulses. In summary, the application of a braking torque during an alternation of the oscillation of a sprung balance causes a negative or positive phase shift in the oscillation of this sprung balance depending on whether this braking torque is applied respectively before or after the sprung balance has passed through its neutral position.

By exploiting the physical phenomena described above, a main embodiment of the watch assembly according to the invention is characterized by a particular arrangement of the device for regulating the mechanical oscillator and in particular the electronic regulating circuit. Generally, this regulating device comprises a measuring device arranged to measure, where appropriate, a time drift of the oscillator. mechanical relative to an auxiliary oscillator, which is implicitly more precise than the mechanical resonator, and to determine whether this time drift corresponds to at least a certain advance or at least a certain delay. Then, the regulation device comprises a control circuit connected to the device for applying regulation pulses described above, which are arranged to be able to apply to the mechanical resonator, when the time drift of the mechanical oscillator corresponds to at least a certain advance, a first braking pulse substantially in a first half-wave before the median instant of passage of the mechanical resonator through its neutral position and, when the time drift of the mechanical oscillator corresponds to at least a certain delay, a second pulse braking substantially in a second half-wave after the median instant of passage of the mechanical resonator through its neutral position.

In a preferred embodiment which will be described later in more detail, the regulation device comprises a device for determining the temporal positions of the mechanical resonator, this determining device being arranged to be able to determine, in an alternation of an oscillation, a first instant which occurs before the median instant of passage of the mechanical resonator through its neutral position and after the initial instant at which this alternation begins, as well as, in the same alternation or another alternation of an oscillation, a second instant which occurs after the median instant of passage of the mechanical resonator through its neutral position and before the final instant at which this alternation ends. Then, the control circuit is arranged to selectively trigger a first braking pulse substantially at the first instant and a second braking pulse substantially at the second instant.

It should be noted that the device for determining the temporal positions of the mechanical resonator may have elements or organs in common with the measuring device, in particular the position measuring sensor, and with the control circuit, for example a logic circuit and possibly a counter. However, such embodiments are in no way limiting in the context of the present invention.

With reference to Figures 5 and 6 , a second embodiment of a watch assembly according to the invention, in particular of its regulating device, will be described below. The regulation device 46 comprises an electronic regulation circuit 48 and an auxiliary resonator 23. This auxiliary resonator is for example an electronic quartz resonator. The sensor 24 here provides an analog signal consisting of pulses occurring at the successive passages of the sprung balance through its neutral position. This analog signal is compared with a reference voltage UREF by means of a hysteresis comparator 50 (Schmidt trigger) arranged in circuit 48 in order to generate a digital signal 'Comp' for the digital electronics of the regulation circuit. This digital signal 'Comp' consists of a succession of digital pulses 42 whose respective rising edges occur respectively at times tzn, n = 1, 2, ..., N, ... (see Figures 3 and 4 ).

The comparator is an element of a measurement circuit 52 described below. Since there are two pulses 42 per period of oscillation of the mechanical resonator, the digital signal 'Comp' is supplied to a flip-flop 54, which regularly supplies one pulse per period of oscillation. The flip-flop increments, at the instantaneous frequency of the mechanical oscillator, a bidirectional counter C2, which is decremented to a nominal frequency / setpoint frequency by a clock signal S _hor derived from the auxiliary oscillator which generates a digital signal at a reference frequency. This auxiliary oscillator is formed by the auxiliary resonator 23 and a clock circuit 56. For this purpose, the relatively high frequency reference signal generated by the clock circuit is divided beforehand by the dividers DIV1 and DIV2 (these two dividers that can form two floors of the same divider). Thus, the state of counter C2 determines the advance or delay accumulated over time by the relatively mechanical oscillator. to the auxiliary oscillator with a resolution corresponding substantially to a set period, the state of the counter being supplied to a control logic circuit 58. The state of the counter C2 corresponds to the time drift of the mechanical oscillator.

As indicated in the organizational chart of the Figure 6 , when the regulation device is activated and its regulation circuit 48 is switched on, this circuit is initialized in step POR. In particular, a reset ('reset') of the counter C2 is carried out. Then, we wait for the detection of a first rising edge of the digital signal 'Comp'. At this instant, the control circuit 58 resets ('reset') the counter C1. At the same time, the control circuit checks whether a certain time drift has been observed. More particularly, it determines whether the possible time drift corresponds to a certain advance (C2> N1?) Or to a certain delay (C2 <- N2?). Note that N1 and N2 are natural numbers (positive whole numbers other than zero). In the case where such an advance, respectively such a delay, is not observed, the control circuit ends the sequence (implemented in a loop) and it waits for the appearance of a new pulse 42 in the signal from the sensor.

If the condition C2> N1 is verified ('true'), then the control circuit waits until the counter C1 has measured a first time interval T _A1 (see Figure 3 ) and then it sends a control signal to a timer 60 ('Timer') which immediately closes a switch 62 (which then goes to the 'ON' state) to energize the mechanical braking device, more precisely to that the latter activates its mechanical braking member during a braking period T _R. In the case of a piezoelectric element used to move the movable end part of the blade 38 in the direction of the rim or the balance shaft (see Figure 2 ), the switch 62 then controls the energization of this piezoelectric element. The first interval T _A1 is selected greater than one half-wave T0 / 4 and less than one half-wave T0 / 2 reduced at least by the duration of the braking pulse, so that the whole of this braking pulse is applied in an alternation before the passage of the mechanical resonator through its neutral position, to generate a decrease in the instantaneous frequency of the mechanical oscillator, given that the time drift indicates that its free frequency is higher on average than the nominal frequency, namely higher than the reference frequency determined by the auxiliary oscillator. Following the generation of a braking pulse (duration T _R ), the sequence is terminated and a new sequence is started while waiting for the appearance of a new pulse 42 in the signal supplied by the sensor.

If the condition C2 <- N2 is verified ('true'), then the control circuit waits for the counter C1 to have measured a second time interval T _A2 (see Figure 4 ) and then it sends a control signal to the timer 60 ('Timer') which immediately closes the switch 62 so that the mechanical braking device activates its mechanical braking member during a braking period T _R. Following the generation of a braking pulse (duration T _R ), the sequence is terminated and a new sequence is started while waiting for the appearance of a new pulse 42 in the signal supplied by the sensor. The second interval T _A2 is selected less than one half-wave T0 / 4 minus the duration of the braking pulse, so that the entire of this braking pulse is applied in one half-wave after the mechanical resonator has passed through its neutral position and before the end of the half-wave in question to generate an increase in the instantaneous frequency of the mechanical oscillator, given that the time drift indicates that its free frequency is lower on average than the setpoint frequency.

It will be noted that, in the Figures 3 and 4 , the time intervals T _A1 and T _A2 begin exactly when the mechanical resonator passes through its neutral position. However, if the pulses 42 are centered on such an event and have a certain non-zero duration, the detection of their rising edge or their falling edge then exhibits a certain time lag with respect to this event. Consequently, it will be understood that the ranges of values for the intervals T _A1 and T _A2 can be here a little different from those resulting from Figures 3 and 4 (small variations of the limit values, approximately half the duration of the position pulses) to satisfy the two main conditions of the control process.

It will be noted that, in the case where C2> N1 or C2 <- N2, it is possible, in a variant, to provide a plurality of successive control pulses at a plurality of times t _Zn + T _A1 , respectively t _Zn + T _A2 according to the method described. This amounts to inhibiting the interrogation of the state of counter C2 during a certain number of sequences. Such a variant makes it possible to provide a succession of low energy braking pulses. To limit the possible range for the time drift of the oscillator, preferably small values are taken for N1 and N2. For example N1 = N2 = 1 or 2.

The sensor, the comparator 50, the control circuit 58 and the counter C1, incremented by the clock circuit 60 via the divider DIV1, together form a device for determining the temporal positions of the mechanical resonator which makes it possible to apply pulses of mechanical braking in various alternations selectively before and after the passage of the mechanical resonator through its neutral position. Thus, the preferred regulation method described above can be implemented efficiently and safely, so as to correct a natural frequency of the mechanical oscillator which is too high or too low relative to the setpoint frequency generated by the clock circuit. 60 via the dividers. The device for determining temporal positions is therefore arranged to measure, following the detection of a passage of the resonator through its neutral position, a first time interval and a second time interval whose respective ends respectively define a first instant and a second instant which are located temporally, in any alternation of the oscillation of the mechanical resonator, respectively before and after the instant of passage of this resonator through its neutral position.

With reference to Figures 7 to 9 , a variant of the second embodiment of the invention will be described, which defines an improvement of the regulation device according to the invention in relation to management of the electrical energy consumed by the sensor. The elements of the regulation circuit 48A, which are identical with those of the variant described with reference to Figures 5 and 6 , will not be described again here, the same for the regulation method which corresponds to that of this variant described previously. The regulating device 66 differs from the regulating device 46 by the fact that the sensor 24 has a standby mode or that it can even be switched off. Thus, by the “OFF” state, it is understood that the sensor is temporarily made inactive and that it is then in a state of lower power consumption than in its “ON” state in which it detects the swaying of the mechanical resonator.

In the present variant, provision is made to put the sensor in its “OFF” state during the major part of each oscillation of the mechanical oscillator. For this purpose, the control circuit 58A is arranged to supply a control signal S _CAP to a switch 68 which controls the supply of the sensor 24, respectively which controls the state of this sensor between its 'ON' state and its state. 'OFF'. As indicated by the S _CAP and Comp signals at Figure 8 , provision is made to put the sensor in its 'OFF' state during a time interval T _OFF T0 and in its 'ON' state during a time interval T _ON in each oscillation period T0 (note that T0 = T _OFF + T _ON ). Preferably, the duration of T _ON is provided for less than half a half-wave T0 / 4 in order to minimize the energy consumption of the sensor. Indeed, it is possible that the digital signal 'Comp' presents pulses of relatively short duration, so that the detection of a pulse 42 per period of oscillation requires only a relatively small time window T _ON . In this case, the comparator 50 delivers only one pulse 42 per period of oscillation, so that the flip-flop provided in the previous variant is eliminated. The comparator 50 directly supplies its output signal to the counter C2.

In the organization chart of the Figure 9 , the management of the sensor power supply appears by placing the sensor in its “OFF” state in each sequence of the regulation process after the detection of the falling edge of a pulse 42 of the “Comp” signal. It will be noted that in this variant, the falling edge of the pulses 42 of the position signal is detected. The sensor can thus detect the whole of a position pulse 42 in the interval T _ON . However, for the regulation itself, the detection of the rising edge or the falling edge does not change anything. For the detection of the position of the balance, the detection of the rising edge of the pulses is also possible to trigger the switch of the sensor from its 'ON' state to its 'OFF' state. In the latter case, the duration of the pulses 42 is greatly reduced since the sensor is made inactive directly after the start of these pulses. Such an implementation variant makes it possible to further reduce the consumption of the sensor.

When the regulation device is activated, the sensor is put directly into its 'ON' state pending detection of the falling edge of a first pulse 42 (corresponding to a passage through the neutral position of the mechanical resonator) . As soon as this detection has been made, the sensor is put in its 'OFF' state (sensor OFF) and the regulation sequence continues as in the previous variant. On the other hand, whether or not a braking pulse is generated, the control circuit 58A continues to follow the incrementation of the counter C1 until its value corresponds to the expected _{time interval T OFF.} Then the sequence ends with a new activation of the sensor (Sensor ON) which also marks the start of a following sequence. The algorithm as given in Figure 9 provides that the duration T _OFF is greater than the duration T _A1 . This condition indicates that the T _OFF interval is appreciably greater than an alternation T0 / 2. In another variant, provision is made to detect the passage through the neutral position only once in a time interval nT0 corresponding to several oscillation periods (n> 1). In such a variant, the measuring device is modified accordingly so that the counter C2 receives only one setpoint pulse, derived from the auxiliary oscillator, in successive intervals nT0.

With reference to the Figure 10 , a third embodiment of a watch assembly 72 will be described below, which differs from the previous embodiments by the arrangement of its braking device 74. The actuator of this braking device comprises two braking modules 76 and 78 each formed by a blade 38A, respectively 38B actuated by a magnet-coil magnetic system 80A, respectively 80B. The coils of the two magnetic systems are respectively controlled by two supply circuits 82A and 82B which are electrically connected to the regulation circuit 22. The blades 38A and 38B define a first brake shoe and a second brake shoe. These two brake pads are arranged so that, when the mechanical braking pulses are applied, they exert on the balance respectively two radial forces diametrically opposed relative to the axis of rotation of the balance 16 and in opposite directions. Of course, the torque force exerted by each of the two pads during a braking pulse is expected to be substantially equal to the other. Thus, the resultant of the forces in the general plane of the balance is substantially zero so that no radial force is exerted on the shaft of the balance during the braking pulses. This avoids mechanical stresses for the pivots of this balance shaft and more generally at the level of the bearings associated with these pivots. Such an arrangement can advantageously be incorporated in a variant where the braking is performed on the balance shaft or on a relatively small diameter disc carried by this shaft.

In an alternative embodiment, the braking force exerted on the balance can be provided axial. In such a variant, it is advantageous to provide a braking device of the type proposed in Figure 10 . In this case, the actuator is arranged so that, when the braking pulses are applied, the first shoe and the second shoe exert on the balance two axial forces that are substantially aligned and in opposite directions. The torque force exerted by each of the two pads during a braking pulse is provided here also to be substantially equal to the other.

An actuator forming a particular braking device is shown in Figure 11 . The actuator comprises a motor of the watchmaker type 86 and a braking member 90 which is mounted on a rotor 88, with a permanent magnet, of this motor so as to exert a certain pressure on the balance 16 of the resonator 14 when the rotor performs a certain rotation, which is generated by a supply of a motor coil during the braking pulses in response to a control signal supplied by the regulation circuit.

Claims (20)

1. Timepiece assembly (2), comprising:

   - a mechanism,

   - a mechanical resonator (14) suitable for oscillating along an oscillation axis about a neutral position corresponding to the minimum potential mechanical energy state thereof,

   - a device (8,10,12) for maintaining the mechanical resonator forming with the latter a mechanical oscillator for defining the working rate of the mechanism, each oscillation of the mechanical resonator exhibiting two successive alternations between two end positions on the oscillation axis defining the oscillation amplitude of the mechanical oscillator,

   - a device for regulating the frequency of the mechanical oscillator, this regulating device comprising an auxiliary oscillator (23), a device (26,60,62) for applying regulation pulses to the mechanical resonator and an electronic control circuit (58, 58A) suitable for generating a control signal which is supplied to the regulation pulse application device for the activation thereof,

   - a sensor (24, 34) suitable for detecting the passage of the mechanical resonator via at least a certain given position on the oscillation axis;

   the regulating device also comprising a measuring device (50, C2) suitable for measuring, on the basis of position signals supplied by said sensor, a time drift of the mechanical oscillator relative to the auxiliary oscillator; the timepiece assembly being characterised in that the regulation pulse application device is formed by an actuator (36, 76, 78, 86)suitable for generating, in response to the control signal which is dependent on the time drift measured, mechanical braking pulses applied on a braking surface of the mechanical resonator, particularly at least one mechanical braking pulse applying a certain braking force on this braking surface, when at least a certain time drift of the mechanical oscillator is detected; and in that the braking surface has a certain extent along said oscillation axis and is arranged in such a way as to enable the application of said mechanical braking pulse with the triggering thereof at a certain given time during an alternation, regardless of the oscillation amplitude of this mechanical oscillator in an amplitude range having a certain extent and corresponding to a usable operating range of the mechanical oscillator, said given time being selected such that the passage via the neutral position of the mechanical resonator does not occur during said mechanical braking pulse.
2. Timepiece assembly according to claim 1, characterised in that said actuator (36, 76, 78, 86) comprises a braking member (38, 38A,38B, 90) suitable for being actuated, in response to said control signal, to apply to an oscillating member of the mechanical resonator, defining said braking surface, a certain mechanical braking force during said mechanical braking pulses.
3. Timepiece assembly according to claim 2, characterised in that the regulation pulse application device is arranged such that the braking energy of each mechanical braking pulse is less than a locking energy, so as not to stop the mechanical resonator momentarily during the mechanical braking pulses; and in that the oscillating member and the braking member are arranged such that the mechanical braking pulses can be applied essentially by dynamic dry friction between the braking member and said braking surface of the oscillating member.
4. Timepiece assembly according to claim 2 or 3, characterised in that said actuator is suitable for actuating said braking member via a piezoelectric element or via an electromagnetic system.
5. Timepiece assembly according to claim 4, characterised in that said actuator comprises a timepiece type motor, said braking member being mounted on a rotor of this motor so as to apply a certain pressure on the oscillating member when the rotor performs a certain rotation induced by a power supply of a motor coil in response to said control signal.
6. Timepiece assembly according to any one of claims 2 to 5, characterised in that the oscillating member is formed by a pivoting balance comprising a felloe which defines said braking surface, which is substantially circular; and in that the braking member comprises a movable part which defines a braking pad suitable for applying a certain pressure against the circular braking surface during the application of the mechanical braking pulses.
7. Timepiece assembly according to any one of claims 2 to 5, characterised in that the oscillating member is formed by a pivoting balance comprising a central shaft which defines, respectively which bears a part other than the felloe of the balance defining said braking surface, which is substantially circular; and in that the braking member comprises a movable part which defines a braking pad suitable for applying a certain pressure against the circular braking surface during the application of the mechanical braking pulses.
8. Timepiece assembly according to claim 6 or 7, wherein said movable part is a first part and said braking pad is a first pad, characterised in that said braking member or another braking member also forming said actuator comprises at least a second movable part which defines a second brake pad; and in that said actuator is arranged in such a way that, during the application of said mechanical braking pulses, the first and second pads apply to the balance two diametrically opposed radial forces relative to the axis of rotation of the balance and of opposite directions.
9. Timepiece assembly according to claim 6 or 7, wherein said movable part is a first part and said braking pad is a first pad, characterised in that said braking member or another braking member also forming said actuator comprises at least a second movable part which defines a second brake pad; and in that said actuator is arranged in such a way that, during the application of said braking pulses, the first and second pads apply to the balance two substantially axial forces of opposite directions.
10. Timepiece assembly according to any one of the preceding claims, wherein each oscillation period of the mechanical oscillator has a first alternation followed by a second alternation, each first alternation and each second alternation having a passage of the mechanical resonator via the neutral position thereof at a median time and a duration between an initial time and an end time defined respectively by the two end positions occupied by the mechanical resonator respectively at the start of and at the end of the alternation; characterised in that said measuring device is suitable for determining whether the time drift of the mechanical oscillator corresponds to at least a certain advance or to at least a certain delay; and in that said control circuit and said regulation pulse application device are suitable for selectively applying to the mechanical resonator, when the time drift measured corresponds to said at least a certain advance, a first mechanical braking pulse (P1) wherein at least a main part occurs between said initial time (t_D1) and said median time (t_N1) of an alternation (A1) and, when the time drift measured corresponds to said at least a certain delay, a second mechanical braking pulse (P2) wherein at least a main part occurs between said median time (tN2) and said end time (tF2) of an alternation (A2).
11. Timepiece assembly according to claim 10, characterised in that the regulation device comprises a device for determining time positions of the mechanical resonator, this determining device being suitable for determining, in an alternation of an oscillation of the mechanical resonator, a first time which occurs prior to said median time and after said initial time of this alternation and, also in an alternation of an oscillation of this mechanical resonator, a second time which occurs after said median time and prior to said end time of this alternation; in that said control circuit is suitable for selectively triggering said first mechanical braking pulse substantially at said first time and said second mechanical braking pulse substantially at said second time; and in that said braking surface of the mechanical resonator comprises a first sector, along said oscillation axis, for applying the first mechanical braking pulse starting substantially at said first time and a second sector, along said oscillation axis, for applying the second mechanical braking pulse starting substantially at said second time, regardless of the oscillation amplitude of said mechanical oscillator in said usable operating range thereof.
12. Timepiece assembly according to any one of the preceding claims, characterised in that said sensor is suitable for detecting at least the passage of the mechanical resonator via the neutral position thereof.
13. Timepiece assembly according to claim 12 dependent on claim 11, characterised in that said device for determining time positions is suitable for measuring, following the detection of a passage of the resonator via the neutral position thereof, a first time interval (T_A1) and a second time interval (T_A2) wherein the respective ends define respectively said first time and said second time.
14. Timepiece assembly according to any one of the preceding claims, characterised in that said sensor is either an optical sensor comprising a light source, suitable for sending a light beam towards the mechanical resonator, and a light detector, suitable for receiving a light signal in return, the intensity whereof varies periodically according to the position of the mechanical resonator, or a capacitive sensor or an inductive sensor suitable for detecting a variation in capacitance, respectively of inductance according to the position of the mechanical resonator, the inductive sensor functioning preferably without magnetised material on the resonator.
15. Timepiece assembly according to any one of the preceding claims, characterised in that said braking surface has an extent enabling the application of said mechanical braking pulses with a triggering thereof substantially at any time of the respective alternations of said mechanical oscillator.
16. Module for regulating the medium frequency of a mechanical oscillator fitted in a timepiece mechanical movement, this regulation module comprising:

    - a regulating device comprising an auxiliary oscillator (23), a device (26,60,62) suitable for applying regulation pulses to a mechanical resonator forming said mechanical oscillator and an electronic control circuit (58, 58A) suitable for generating a control signal which is supplied to the regulation pulse application device for the activation thereof,

    - a sensor (24, 34) suitable for detecting the passage of the mechanical resonator via a certain given position on the oscillation axis thereof;

    the regulating device also comprising a measuring device (50, C2) suitable for measuring, on the basis of position signals supplied by said sensor, a time drift of the mechanical oscillator relative to the auxiliary oscillator; the module being characterised in that the regulation pulse application device is formed by an actuator (36, 76, 78, 86) arranged so as to be able to generate, in response to the control signal which is dependent on the time drift measured, mechanical braking pulses on a braking surface of the mechanical resonator when at least a certain time drift of the mechanical oscillator is detected; and in that the regulating device is suitable for triggering said mechanical braking pulse at a certain given time during an alternation of the mechanical oscillator, this given time being selected such that the passage via the neutral position of the mechanical resonator does not occur during said mechanical braking pulse.
17. Regulation module according to claim 16, characterised in that said actuator (36, 76,78, 86) comprises a braking member (38, 38A,38B, 90) suitable for being actuated, in response to said control signal, so as to be able to apply to the oscillating member of the mechanical resonator, defining said braking surface, a certain mechanical braking force during said mechanical braking pulses.
18. Regulation module according to claim 17, characterised in that the braking member is arranged such that the mechanical braking pulses can be applied essentially by dynamic dry friction between said braking member and said braking surface of the oscillating member.
19. Regulation module according to claim 18, characterised in that the braking member comprises a movable part which defines a brake pad suitable for applying a certain pressure on said braking surface during the application of the mechanical braking pulses.
20. Regulation module according to claim 19, wherein said movable part is a first part and said brake pad is a first pad, characterised in that said braking member or another braking member also forming said actuator comprises at least a second movable part which defines a second brake pad; and in that said actuator is arranged in such a way that, during the application of said mechanical braking pulses, the first and second pads apply to the mechanical resonator two substantially aligned forces of opposite directions.

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