CH713332A2 - Clock assembly comprising a mechanical oscillator associated with a regulating device. - Google Patents

Abstract

The watch assembly comprises a mechanical movement equipped with a mechanical oscillator, formed by a resonator (14) of the spring-balance type, and a device for regulating its oscillation frequency with the aid of an auxiliary oscillator provided with a quartz resonator. The regulating device comprises a sensor (34), arranged to be able to detect the passage of the resonator by its neutral position, a measuring device arranged to be able to measure, on the basis of position signals supplied by the sensor, a time drift of the mechanical oscillator relative to the auxiliary oscillator, and a device (36) for applying to the resonator mechanical braking pulses when a certain time drift is detected. For this purpose, the resonator has a braking surface that extends over at least one sector having a certain length along the axis of oscillation and against which a braking member (38) can come to rest for momentary braking. resonator.

Description

TECHNICAL FIELD [0001] The present invention relates to a watch assembly, in particular a timepiece, comprising: a mechanism, which partly forms part of a mechanical movement; a mechanical resonator capable of oscillating along an axis; oscillating about a neutral position corresponding to its state of minimum potential mechanical energy, - a maintenance device of the mechanical resonator forming with the latter a mechanical oscillator arranged to start-running the mechanism, each oscillation of the resonator mechanical device having two successive alternations between two extreme positions on the axis of oscillation which define the oscillation amplitude of the mechanical oscillator, - a regulation device arranged to regulate the frequency of the mechanical oscillator, this control device comprising an auxiliary oscillator, generally more accurate than said oscillator m echanique, and a device arranged to apply on command control pulses to the mechanical resonator which momentarily restrains it.

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

BACKGROUND [0003] Motion forming watch assemblies as defined in the field of the invention have been proposed in some previous documents. Patent CH 597 636, published in 1977, proposes such a movement with reference to FIG. 3. The movement is equipped with a sprung balance resonator and a conventional maintenance device comprising an anchor and an escape wheel in kinematic connection with a spring-loaded barrel. This watch movement comprises a device for regulating the frequency of the mechanical oscillator. This control device comprises an electronic circuit and a magnetic assembly formed of a flat coil, arranged on a support under the beam shank, 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 for generating a reference frequency signal FR, this reference frequency being compared with the frequency FG of the mechanical oscillator. The detection of the frequency FG of the oscillator is performed via the electrical signals generated in the coil by the pair of magnets. The control circuit is arranged to be able momentarily to generate a braking torque via a magnet-coil magnetic coupling and a switchable load connected to the coil. 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 of the oscillation frequency of a non-isochronous resonator is obtained by varying its amplitude of oscillation. An analogy is made between the amplitude of oscillation of a resonator and the angular velocity of a generator comprising a rotor provided with magnets and arranged in a cog of the watch movement to regulate its operation. As a braking torque decreases the rotational speed of such a generator and thus its rotation frequency, it is here only considered to be able to reduce the oscillation frequency of a necessarily non-isochronous resonator by applying a torque braking decreasing its amplitude of oscillation.

To perform an electronic control of the frequency of the generator, respectively the mechanical oscillator, it is provided in a given embodiment that the charge is formed by a switchable rectifier via a transistor which charges a storage capacity when braking pulses, for recovering the electrical energy in order to supply the electronic circuit. The constant teaching given in document CH 597 636 is as follows: When FG> FR the transistor is conductive; a power Pa is then taken from the generator / oscillator. When FG <FR, the transistor is non-conductive; no more energy is drawn from the generator / oscillator. In other words, it regulates only when the frequency of the generator / oscillator is greater than the reference frequency FR. This regulation consists of braking the generator / oscillator in order to reduce its frequency FG. Thus, in the case of the mechanical oscillator, those skilled in the art understand that regulation is possible only when the mainspring is heavily 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. There is therefore a double problem, namely the mechanical oscillator is selected for what is normally a defect in a mechanical movement and the electronic control is functional only 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 the following: If we want to electronically regulate the frequency of a sprung balance of a classic watch movement, it is necessary to change the sprung balance for first arrange at least one magnet on it and secondly to modify its natural frequency so that this natural frequency is greater than the desired frequency. The consequence of such a teaching is clear: The mechanical resonator must be de-tuned to oscillate at a frequency that is too high to allow the regulating device to constantly reduce its frequency to a lower frequency, corresponding to the desired theoretical frequency. , by a succession of braking pulses. Consequently, the resulting clock movement is voluntarily adjusted so that a precise step depends on the electronic regulation, otherwise such a watch movement would have a very important time drift. Thus, if for one reason or another the regulating device is deactivated, in particular because of deterioration, then the watch equipped with such a movement will no longer be precise, and this to an extent that it is in fact more functional. Such a situation is problematic.

The use of an electromagnetic magnet-coil type system for coupling the sprung balance with the electronic control circuit generates various problems. First, the arrangement of permanent magnets on the balance means that a magnetic flux is constantly present in the watch movement and that this magnetic flux spatially varies periodically. Such a magnetic flux can have a detrimental effect on various members or elements of the watch movement, in particular on magnetic material elements such as parts made of ferromagnetic material. This can have repercussions on the smooth running of the watch movement and also increase the wear of pivotal elements. One can certainly think to shield to a certain extent the magnetic system in question, but a shielding requires particular elements that are carried by the pendulum. Such shielding tends to increase the bulk of the mechanical resonator and its weight. In addition, it limits the possibilities of refined aesthetic configurations. In addition, a strong external magnetic field can damage the magnetic elements of the electromagnetic system.

The skilled person knows proposals for producing mechanical watch movements, comprising a device for regulating the frequency of the sprung balance, where it is intended to act on the oscillating balance by an electromechanical system formed of firstly, 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 with that of a quartz oscillator by an alleged interaction between the finger and the stop when the mechanical oscillator has a time drift relative to the quartz oscillator, the finger coming either momentarily block the rocker which is then stopped in its movement during a certain time interval (the abutment bearing against the finger moved in its direction during the return of the rocker in the direction of its neutral position), or limit the amplitude of oscillation when the finger comes against the stop while the rocker rotates towards its position of maximum amplitude.

Such a control system has many disadvantages and can seriously doubt that it can form a functional system. The "blind" action of the finger relative to the movement of the stop and any potential initial phase shift of the oscillation of the abutment relative to that of the finger poses multiple 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 stop depends on the oscillation amplitude of the sprung balance and the position of the actuator. In conclusion, such achievements appear to those skilled in the art as highly improbable, and this skilled person turns away from such teaching. Moreover, the present inventors are not aware of watches equipped with such an electromechanical system that would have been placed on the market. SUMMARY OF THE INVENTION [0010] An object of the present invention is to find a solution to the technical problems and disadvantages mentioned above in the technological background.

A first objective, in the context of the development that led to the present invention, was to propose a watch assembly comprising a mechanical movement, with a conventional mechanical resonator of the spring-balance type, and a control device that does not use not a magnet-coil system for coupling the mechanical resonator to this control device, in particular that does not require to arrange 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 that 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 initially having to mechanical oscillator, to have a timepiece which has the precision of an auxiliary electronic oscillator (in particular equipped with a quartz resonator) when the regulating device is functional and the accuracy of the mechanical oscillator when this device of The control is deactivated or deactivated, but with a precision which may correspond to the best standard in the latter case. In other words, it seeks to add an electronic control to a mechanical movement also set as precisely as possible so that it remains functional, with the best possible operation, when the electronic control is not active.

The present invention also aims to provide a watch assembly responding to at least the first objective and which is robust, that is to say, which can maintain a high accuracy even after an external disturbance as a shock.

For this purpose, the present invention relates to a watch assembly as defined in claim 1, and a control module as defined in claim 16. Various embodiments and variants are the objects of the dependent claims. Thus, the watch assembly according to the invention comprises an electronic control circuit, arranged to be able to generate a control signal which is supplied to the regulation pulse application device to activate it, and a sensor arranged to be able to detect the passage of the mechanical resonator by a certain given position on the axis of oscillation. The control device of this watch assembly comprises a measurement device arranged to be able to measure, on the basis of position signals supplied by the sensor, a time drift of the mechanical oscillator relative to the auxiliary oscillator. Advantageously, the device for applying control pulses of the watch assembly is an electromechanical device arranged so as to be able to generate, in response to the above-mentioned control signal which is a function of the measured time drift, braking pulses. mechanics applied to the mechanical resonator and each exerting a certain force torque on the mechanical resonator, for regulating the average frequency of the mechanical oscillator, when at least a certain time drift of this mechanical oscillator is detected. Finally, the mechanical resonator defines a braking surface having a certain extent along the axis of oscillation of the mechanical resonator and arranged so as to allow at least the application of a mechanical braking pulse with its release at a given instant. during alternation, among the two alternations of an oscillation of the mechanical oscillator, regardless of the amplitude of oscillation of this mechanical oscillator in a range of amplitude having a certain extent and corresponding to a range of useful operation of the mechanical oscillator, said given instant being selected so that the passage through the neutral position of the mechanical resonator does not occur during the mechanical braking pulse.

By 'mechanical braking pulse', one understands a braking of mechanical nature and not only a mechanical effect resulting from the braking. Thus, this expression excludes in the first direction which is given a non-contact 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 an electromagnetic system of which an element, namely said at least one magnet, is attached to an oscillating member of the mechanical resonator, thereby changing the conventional arrangement of the oscillating member, for example a balance. Admittedly, magnetic braking has the ultimate effect of reducing the mechanical energy of the oscillating member, but braking is not mechanical in nature. The aforementioned expression also excludes braking resulting from electrical coupling between the oscillating member and a stationary unit of the regulating device. By cons, obviously, this expression does not exclude electrical and / or magnetic elements incorporated in the electromechanical device that 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 control pulses.

In a preferred embodiment, the regulation pulse application device is formed by a neural action comprising at least one braking member which is arranged to be actuated, in response to the above-mentioned control signal, of in order to exert on the oscillating member of the mechanical resonator a certain torque of mechanical force during the mechanical braking pulses. Braking is thus obtained by physical contact between the braking member and the oscillating member.

In an advantageous variant of the aforementioned preferred embodiment, the regulation pulse application device is arranged in such a way that the braking energy of each mechanical braking pulse is less than a blocking energy, so that not momentarily stop the mechanical resonator during the braking pulses. Then, the oscillating member and the braking member are arranged so that the mechanical braking pulses can be applied mainly by a dynamic dry friction between the braking member and the braking surface of the oscillating member.

Thanks to the features of the invention, it is possible to add to a basic mechanical movement a control module of its mechanical oscillator (comprising a sprung-balance) without having to modify this basic mechanical movement. This is a big advantage. In particular, it is possible to produce the watch assembly according to the invention without having to vary the kinematic properties of the mechanical oscillator. If necessary, a surface treatment (usually partial) of the balance may be provided for the operation of the sensor. Such a treatment can be limited to affixing a black dot on an arm of the balance or under the serge of this balance in the case of an optical sensor. Thus, the design of the basic mechanical movement does not have to be changed to produce a watch assembly according to the invention. In a first case where the entire watch is made completely new, it can take an existing caliber that has already been proven in production and associated with it an additional regulation module according to the invention, by arranging the periphery of the corresponding watch movement 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 ensemble that it will eventually 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 put, at first, on the market in a watch and which is added, in a second step, a control module according to the invention to increase its accuracy. An adaptation to the level of the dressing of the watch may be necessary, but is not necessarily mandatory. For example, a machining at a casing circle may be sufficient to allow the incorporation of the watch assembly into the watch case already in the possession of a user, that is to say with an addition of a regulation module according to the invention, object of 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 at least one delay. Then, the control circuit and the regulation pulse application device are arranged to be able to apply selectively to the mechanical resonator, when the measured time drift corresponds to a certain advance, a first mechanical braking pulse of which at least a major part intervenes between the initial moment and the median moment of an alternation (first half-cycle) and, when the measured time drift corresponds to a certain delay, a second mechanical braking pulse of which at least a major part intervenes between the median moment and the final moment of alternation (second half-alternation). It will be noted that each oscillation period of the mechanical oscillator defines a first alternation followed by a second alternation and each alternation has a passage of the mechanical resonator by its neutral position at said median instant.

Thus, in summary, the control circuit and the regulation pulse application device are arranged to apply selectively to the mechanical resonator, when the measured time drift corresponds to a certain advance, a mechanical braking pulse in a first half-wave 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 control 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 moment which occurs before the instant median and after the initial moment of this alternation and, also in an alternation of an oscillation of this mechanical resonator, a second moment which intervenes after the median moment and before the final moment 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 moment and a second sector, along the axis. oscillator, for the application of the second mechanical braking pulse beginning substantially at the second instant, regardless of the oscillation amplitude of the mechanical oscillator in its useful operating range.

BRIEF DESCRIPTION OF THE FIGURES [0022] The invention will be described in more detail below with reference to the accompanying drawings, given by way of non-limiting examples, in which: FIG. 1 is a top view of a watch assembly according to the invention, FIG. 2 shows a first embodiment of a regulating device for regulating the oscillation frequency of a spiral balance of a watch assembly according to the invention, FIG. 3 shows the position signal provided by a sensor detecting the passage of the sprung balance by 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 beam and its angular position in a time interval during which the first braking pulse occurs, FIG. 4 is a figure similar to that of FIG. 3 with the application of a second braking pulse in a certain alternation after the sprung balance has passed through its neutral position, FIG. 5 shows the electronic diagram of a second embodiment of the device for regulating the mechanical oscillator according to the invention, FIG. 6 is a flowchart of an operating mode of the control device of FIG. 5, fig. 7 shows the electronic diagram of a variant of the second embodiment of the device for regulating the mechanical oscillator, FIG. 8 shows two digital signals occurring in the electronic circuit of FIG. 7, FIG. 9 is a flowchart of an operating mode of the control device of FIG. 7, FIG. 10 shows a third embodiment of a regulating device according to the invention, and FIG. 11 shows a particular embodiment of the braking device of a control device according to the invention.

Detailed Description of the Invention [0023] In FIG. 1 is shown a watch unit 2 according to the present invention. It comprises a mechanical watch movement 4 which is formed at least by a mechanism comprising a gear 10 driven by a motor-spring arranged in a barrel 8 (this mechanism is partially shown in Fig. 1). The watch movement comprises a mechanical resonator 14, formed by a rocker 16 and a hairspring 18, and a maintenance device of the mechanical resonator forming with this mechanical resonator a mechanical oscillator which controls the operation of the mechanism. The maintenance device comprises an exhaust 12, formed here by an anchor and an escape wheel which is kinematically connected to the cylinder via the gear 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 minimum mechanical potential energy state. Each oscillation of the mechanical resonator defines a period of oscillation.

The watch assembly 2 further comprises a device 6 for electronically regulating the frequency of the mechanical oscillator, this control device comprising an electronic control circuit 22 associated with an auxiliary oscillator formed by a quartz resonator 23. On note that other types of auxiliary oscillators can be provided, including an oscillator fully integrated in the control circuit. By definition, the auxiliary oscillator is more accurate than the mechanical oscillator. The device 6 also comprises a sensor 24 for detecting at least one angular position of the pendulum when it oscillates and a device 26 for applying regulation 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 control circuit an electronic control circuit arranged to generate a control signal, which is supplied to the regulation pulse application device which is arranged in such a way as to in response to this control signal, it is possible to generate successive control pulses each exerting a certain force torque on the mechanical resonator. According to the invention, the sensor 24 is arranged to be able to detect the passage of at least one reference point of the balance 16 by 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. Note that, in this preferred embodiment, the sensor may be associated with the anchor of the exhaust so as to detect the tilting of this anchor during the oscillation maintenance pulses which are provided substantially when the resonator passes through. neutral position.

The detection of the neutral point of the resonator makes it possible to generate a reference of useful and stable time within the oscillations. Indeed, in the absence of disturbances (in particular caused by the braking pulses provided for regulation), the passage through the neutral point always occurs exactly in the middle of the alternations, regardless of the amplitude of oscillation. On the other hand, the detection of another angular position of the balance does not give a stable and well-defined temporal reference, in particular with regard to the events that are the passage of the balance-spring by its neutral position and the beginning or the end of the alternations, to know the moments when the balance is at maximum amplitude and at zero angular velocity (corresponding to the inversion 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 accuracy of this detection and thus the detection of the corresponding instant are better. The benefit of detecting the passage of the sprung balance by its neutral position will be better understood subsequently in the description of the preferred control method which will be made with reference to FIGS. 3 and 4, and embodiments that follow.

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

The device 26 for applying control 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 noted. In a particular variant, the braking energy that is taken by the mechanical resonator by any mechanical braking pulse is lower than the blocking energy of the mechanical oscillator, so as not to momentarily stop the oscillation movement. mechanical resonator during control pulses. The blocking energy is normally defined as the kinetic energy of the mechanical resonator at the beginning of the braking pulse minus the potential energy difference of this mechanical resonator between the end and the beginning of the braking pulse in question. as long as the mechanical oscillator does not receive maintenance energy during this braking pulse. It is therefore in this particular embodiment to reduce, during the braking pulse, the angular speed of the sprung balance without stopping more or less long. It should be noted that, in order to guarantee the proper operation of the Swiss lever escapement of a conventional watch oscillator, it is preferable that the braking pulses do not take place during the tilting of the anchor, tilts during which a contribution is made of maintenance energy of the oscillator. Since the tilting of the anchor generally occurs around the neutral position of the mechanical resonator, it will therefore be avoided to disturb by a braking pulse the oscillation movement of the balance spring as it passes through this neutral position.

According to a first embodiment shown in FIG. 2, the regulation pulse application device 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, the resonator mechanical a certain mechanical force during the mechanical braking pulses. The actuator 36 comprises a piezoelectric element powered 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 slow it down. In the example shown in FIG. 2, the blade 38 forming the braking member curves and its end portion presses against the circular lateral surface 40 of the serge 17 of the balance 16. Thus, the serge 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 portion of the blade, which defines a braking pad arranged to exert a pressure against the substantially circular braking surface during the application of the pulses. mechanical braking. Preferably, it is provided in the context of the present invention that the oscillating member and the braking member are arranged in such a way that the mechanical braking pulses are applied by a dynamic dry friction or a 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 beam of the beam defining, at least over a certain angular sector, a circular braking surface. In this case, a pad of the braking member is arranged to exert a 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), associated with at least one braking pad, carried by the braking device of the control device, constitutes a mechanical braking system which has advantages. determinants. Indeed, thanks to such a system, braking pulses can be applied to the mechanical resonator at any time oscillations, and this independently of the oscillation amplitude of the balance. Then, it is possible to precisely manage the correction generated by a braking pulse, in particular by an appropriate selection of its duration and by the applied braking force torque. It is also possible, in particular by virtue of the position measurement performed by the sensor, to determine the instants during alternations to apply the braking pulses. Thus, at least the braking torque, the duration of the pulses and the respective times at which they are generated can be selected and vary according to 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.

It will be noted that the amplitude of oscillation generally varies according to the degree of winding of the barrel (unless a specific device to produce a constant force is provided). Thus, at a given non-zero time before or after the passage of the resonator by 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, for example, braking pulses are chosen to regulate the oscillation frequency always at a determined fixed time interval before or after the resonator has passed through its neutral position (see the preferred regulation principle explained later), 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 the braking surface. Thus, the mechanical resonator has a braking surface that extends over at least a certain angular sector having a certain angular length that is non-zero (that is to say, an angular sector is considered as non-punctual), to allow the application of mechanical braking pulses at least at a given moment in the oscillation periods of the mechanical oscillator, regardless of the oscillation amplitude of the mechanical resonator for a useful operating range of mechanical oscillator.

It will be noted that, according to the above-mentioned time interval or according to a time range chosen to apply braking pulses before or after the moments of passage of the mechanical resonator by its neutral position in various alternations of its oscillation movement, instants that are detected by the sensor 34, it is sufficient that two defined angular sectors of the beam present or define respectively two circular surfaces for the brake member pad so that the braking pulses can be applied in a useful operating range of the mechanical oscillator, 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, it is provided that the braking surface of the mechanical resonator comprises 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 time 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 after the median instant, irrespective of the oscillation amplitude 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 with the same temporal distance of the median instant and the same side of the neutral position, the first and second angular sectors are substantially merged and define thus one and the same angular sector of braking. In other cases, the first and second angular sectors have a common portion or are distinct. The same considerations apply to a first time interval and a second time interval in which provision can be made to respectively apply the first and second braking pulses. In the variant shown in FIG. 2, the braking surface has an extent permitting the application of mechanical braking pulses at any time oscillations of the mechanical resonator.

Note also that the pad of the braking member may 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 manufacturing and mounting tolerances of the braking device in or on 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 beam, and a light detector, arranged to receive a remote light signal whose intensity varies periodically depending on the position of the beam. In the schematic example shown in FIG. 2, the beam is sent on the lateral surface of the serge 17, this surface having a limited area with a reflectivity different from the two neighboring zones, so that the sensor can detect the passage of this limited area and provide the control device with a position signal when this event occurs. It will be understood that the circular surface having a variable reflection for the light beam may be located at other points of the beam. The variation can in a particular case be produced by a hole in the reflective surface. The sensor can also detect the passage of a certain portion of the beam, for example an arm, the neutral position corresponding for example in the middle of a signal reflected by the arm or at the beginning, respectively at the end of such a signal. It is therefore understood that the modulation of the light signal, which may consist of a succession of light pulses received in return by the photodetector, may define the angular position of the beam in various ways, by a negative or positive variation of the light captured. .

In other variants, the position sensor may be of the capacitive type or of the inductive type and thus be arranged so as to detect a variation in capacitance or inductance respectively as a function of the position of the balance. The inductive sensor preferably operates without presence of magnetized material on the resonator, for example by detecting the presence of a non-magnetic material or simply a variation in distance between such a material and the sensor. Those skilled in the art know many sensors that can easily be incorporated into the watch assembly according to the invention.

Advantageously, the various elements of the control device 6 form a module independent of the watch movement. Thus, this module can be assembled or associated with the mechanical movement 4 that during their assembly in particular in a watch case. In particular, such a module can be attached to a casing ring that surrounds the watch movement. It is understood that the electronic control module can be advantageously associated with the watch movement once the latter fully assembled and adjusted, the assembly and disassembly of this module can occur without having to intervene on the mechanical movement itself.

We will describe below, with reference to FIGS. 3 and 4, a control method which constitutes a remarkable improvement of the invention, then embodiments of watch assemblies according to the invention in which this very advantageous control method is implemented.

FIG. 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. Note that the digital signal can be provided in a first variant directly by the sensor, but in a second variant the sensor provides an analog signal and it is the control circuit that converts it into a digital signal, in particular by means of a comparator. As explained above, the sensor and the balance are arranged to allow the sensor to detect the successive passages of the sprung balance by its neutral position. Such an event occurs twice per oscillation period, once in each of the two half-waves at a time tz "at which the sensor provides a pulse 42.

Each oscillation period of the mechanical oscillator defines a first alternation followed by a second alternation between two extreme positions defining the oscillation amplitude of this mechanical oscillator, each alternation having a passage of the mechanical resonator by its position. neutral at a median time tzn and a duration between an initial instant tA ^, respectively tD1 for the alternation A1 in FIG. 3 and tD2 for the alternation A2 in FIG. 4, and a final instant tAn, respectively tF1 for the alternation A1 in FIG. 3 and tF2 for the alternation A2 in FIG. 4. These initial and final instants are respectively defined by the two extreme positions occupied by the mechanical resonator respectively at the beginning and the end of each alternation. The second graph indicates the instant t ^ at which a braking pulse is applied to the mechanical resonator 14 to make a correction in the operation of the mechanism clocked by the mechanical oscillator. Moments in which pulses of rectangular shape (i.e., a binary signal) occur are defined in FIGS. 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 control circuit, the beginning or the end of a pulse as the moment that characterizes it, namely either the rising edge or the falling edge of this pulse. This is particularly the case for the braking pulses which are generally determined the beginning (that is to say the trigger) and the duration.

There is a variation of the oscillation period during which the braking pulse occurs and therefore a point variation of the frequency of the mechanical oscillator. In fact, as seen in the last two graphs of FIG. 3, which respectively show the angular velocity (values in radians per second: [rad / s]) and the angular position (values in radian: [rad]) of the pendulum over time, the temporal variation relates to the only alternation during from which intervenes the braking pulse. 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 rocker is respectively subjected to an oscillation movement in one direction and then an oscillation movement in the other direction. In other words, an alternation corresponds to a rocking of the rocker in one direction or the other direction between its two extreme positions defining the amplitude of oscillation.

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

In figs. 3 and 4, the oscillation period TO corresponds to a "free" oscillation (that is to say without application of regulation pulses) of the mechanical oscillator of the watch assembly. The two alternations of one oscillation period each have a duration TO / 2 without disturbance or external stress (in particular by a regulation pulse). The time t = 0 marks the beginning of a first alternation. It will be noted that the "free" frequency FO of the mechanical oscillator is here approximately equal to four Hertz (FO = 4 Hz), so that the period TO = 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 FIG. 3. After a first period TO then begins a new period T1, respectively a new alternation A1 during which a braking pulse P1 occurs. At the initial time tD1 starts the alternation A1, the resonator 14 occupying a maximum positive angular position corresponding to an extreme position. Then comes the braking pulse P1 at time tP1 which is located before the median time tNi at which the resonator passes through its neutral position. Finally the alternation A1 ends at the final moment îfi. The braking pulse is triggered after a time interval TAi following the last median time tzn detected by the sensor before the alternation A1. The duration TA1 is selected greater than a half-alternation TO / 4 and less than an alternation TO / 2 less the duration of the braking pulse P1. In the example given, the duration of this braking pulse is much less than a half-alternation TO / 4. By "median moment", we understand a moment intervening substantially in the middle of the alternations. This is precisely the case when the mechanical oscillator oscillates freely. On the other hand, for the alternations during which regulation pulses are provided, it will be noted that this median instant no longer corresponds exactly to the middle of the duration of each of these alternations due to the disturbance of the mechanical oscillator generated by the device. regulation.

In this first case, the braking pulse is generated between the beginning of an alternation and the passage of the resonator by its neutral position in this alternation. As expected, the angular velocity in absolute value decreases at the moment of the braking pulse P1. Such a braking pulse induces a negative temporal phase shift TCi in the oscillation of the resonator, as shown by the two graphs of the angular velocity and the angular position in FIG. 3, a delay relative to the undisturbed theoretical signal (shown in broken lines). Thus, the duration of the alternation A1 is increased by a time interval TCi. The oscillation period T1, comprising the alternation A1, is therefore extended relative to the value TO. This causes a specific decrease in the frequency of the mechanical oscillator and a momentary slowing of the operation of the associated mechanism.

[0046] Referring to FIG. 4, will be described below the behavior of the mechanical oscillator in a second case of correction of its oscillation frequency. The graphs of this fig. 4 show the temporal evolution of the same variables as in fig. 3. After a first period TO then starts a new oscillation period T2, respectively an alternation A2 during which a braking pulse P2 intervenes. At the initial time tb2 starts the alternation A2, the mechanical resonator then being in an extreme position (maximum negative angular position). After a quarter period (TO / 4) corresponding to a half-wave, the resonator reaches its neutral position at the median time tN2. Then comes the braking pulse P2 at time tp2 which is located after the median time tN2 at which the resonator passes through its neutral position in the alternation A2. Finally, after the braking pulse P2, this alternation A2 ends at the final time tF2 at which the resonator again occupies an extreme position (maximum positive angular position in the period 12). The braking pulse is triggered after a time interval Tt0 following the median time tN2 of the alternation A2. The duration TA2 is selected less than half-alternation TO / 4 less the duration of the braking pulse P2. In the example given, the duration of this braking pulse is much less than half a half cycle.

In the second case considered, the braking pulse is 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 phase shift Tea in the oscillation of the resonator, as shown by the two graphs of the angular velocity and the angular position in FIG. 4, an advance relative to the undisturbed theoretical signal (shown in broken lines). Thus, the duration of the alternation A2 is reduced by the time interval TC2. The oscillation period T2 comprising the alternation A2 is therefore shorter than the value TO. This therefore generates a point increase in the frequency of the mechanical oscillator and a momentary acceleration of the operation of the associated mechanism. This phenomenon is surprising and unintuitive, which is why the skilled person ignored it in the past.

This control method is remarkable in that it takes advantage of a surprising physical phenomenon of mechanical oscillators. The inventors have arrived at the following observation: Contrary to the general education in the horological field, it is possible not only to reduce the frequency of a mechanical oscillator by braking pulses, but it is also possible to increase the frequency such a mechanical oscillator also by braking pulses. The 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 increase the frequency of such a mechanical oscillator by the application of driving pulses. when an energy input to this oscillator, Such an intuition, which has imposed itself in the field of watchmaking and therefore comes first on board in the mind of a person skilled in the art, proves false for an oscillator mechanical. Although such behavior is correct for a micro-generator, whose rotor turns continuously in the same direction, this is 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, a mechanical oscillator, moreover very precise, that momentarily has a frequency slightly too high or too low. To do this, it is expected to select, depending on the operation of the mechanism in question and therefore the frequency of the mechanical oscillator that paces this step, the moment to apply a mechanical braking pulse. The inventors have observed that the effect produced by a control 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 by 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 by its neutral position produces a positive temporal phase shift in the oscillation of this resonator and thus an advance in the operation of the mechanism. It is thus possible to correct a frequency that is too high or a frequency that is too low 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 mechanical oscillator control device and in particular the electronic control circuit. Generally, this control device comprises a measurement device arranged to measure, if necessary, a time drift of the mechanical oscillator relative to an auxiliary oscillator, which is implicitly more accurate than the mechanical resonator, and to determine whether this temporal drift at least some advance or at least some delay. Then, the control device comprises a control circuit connected to the regulating pulse application device 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 some advance, a first braking pulse substantially in a first half-wave before the median time of passage of the mechanical resonator by 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 time of passage of the mechanical resonator by its neutral position.

In a preferred embodiment which will be described later in more detail, the control device comprises a device for determining the temporal positions of the mechanical resonator, this determination device being arranged to be able to determine, in an alternation of an oscillation, a first moment which occurs before the median moment of passage of the mechanical resonator by its neutral position and after the initial moment at which this alternation begins, and, in the same alternation or another alternation of an oscillation, a second moment which intervenes after the median moment of passage of the mechanical resonator by its neutral position and before the final moment 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 members 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 FIGS. 5 and 6, there will be described hereinafter a second embodiment of a watch assembly according to the invention, in particular its control device. The regulator device 46 comprises an electronic control 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 involved in the successive passages of the sprung balance by its neutral position. This analog signal is compared with a reference voltage UREf by means of a hysteresis comparator 50 (Schmidt trigger) arranged in the 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 intervene respectively at times tz ", n = 1.2 ..... N, ... (see FIG. 4).

The comparator is an element of a measurement circuit 52 described hereinafter. Since there are two pulses 42 per oscillation period of the mechanical resonator, the digital signal "Comp" is supplied to a flip-flop 54, which regularly provides a pulse per oscillation period. The flip-flop increments, at the instantaneous frequency of the mechanical oscillator, a bidirectional counter C2, which is decremented at a nominal frequency / setpoint frequency by a clock signal Sh0r derived from the auxiliary oscillator which generates a digital signal at a frequency of reference frequency. This auxiliary oscillator is formed of 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 the counter C2 determines the advance or the delay accumulated over time by the mechanical oscillator relative 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 flowchart of FIG. 6, during the activation of the regulation device and the powering up of its regulation circuit 48, this circuit is initialized at the step POR. In particular a reset ("reset") of the counter C2 is performed. Next, the detection of a first rising edge of the digital signal "Comp" is awaited. At this time, the control circuit 58 resets ("reset") the counter C1. Simultaneously, the control circuit checks whether a certain time drift has been observed. More particularly, it determines whether the eventual 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 integers not equal to zero). In the case where such an advance, respectively such a delay is not noted, the control circuit terminates the sequence (implemented in loop) and it waits for the appearance of a new pulse 42 in the sensor signal.

If the condition C2> N1 is satisfied ("true"), then the control circuit waits for the counter C1 to measure a first time interval TAi (see Fig. 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 switch on the mechanical braking device, specifically for the latter to activate its mechanical braking member during a braking period TR. In the case of a piezoelectric element used to move the movable end portion of the blade 38 towards the serge or the balance shaft (see Fig. 2), the switch 62 then controls the power up. of this piezoelectric element. The first interval TAi is selected greater than a half-alternation TO / 4 and less than an alternation TO / 2 decreased by at least the duration of the braking pulse, so that the integer of this braking pulse is applied in an alternation before the passage of the mechanical resonator by its neutral position, to generate a decrease in the instantaneous frequency of the mechanical oscillator, since the time drift indicates that its free frequency is higher on average than the nominal frequency, namely greater at the reference frequency determined by the auxiliary oscillator. Following the generation of a braking pulse (duration TR), the sequence is completed and a new sequence is started with the expectation of the appearance of a new pulse 42 in the signal provided by the sensor.

If the condition C2 <- N2 is verified ("true"), then the control circuit waits for the counter C1 to measure a second time interval TA2 (see Fig. 4) and then it sends a control signal timer 60 ("Timer") which immediately closes the switch 62 so that the mechanical braking device activates its mechanical braking member during a braking period TR. Following the generation of a braking pulse (duration TR), the sequence is completed and a new sequence is started with the expectation of the appearance of a new pulse 42 in the signal provided by the sensor. The second interval Tt0 is selected less than a half-alternation TO / 4 minus the duration of the braking pulse, so that the integer of this braking pulse is applied alternately after the passage of the mechanical resonator by its neutral position and before the end of the alternation in question to cause an increase in the instantaneous frequency of the mechanical oscillator, since the time drift indicates that its free frequency is lower on average than the reference frequency.

It will be noted that in FIGS. 3 and 4, the time intervals TA1 and TA2 start exactly at the passages of the mechanical resonator by 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 has a certain time offset with respect to this event. Therefore, it will be understood that the ranges of values for the intervals TA1 and TA2 may here be a little different from those resulting from FIGS. 3 and 4 (small variations of the limit values, substantially half of 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 tzn + TA1, respectively tzn + TA2 according to the method described. This amounts to inhibiting the interrogation of the state of the 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, small values for N1 and N2 are preferably selected. 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 mechanical braking pulses in various alternations selectively before and after the mechanical resonator passes 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 reference frequency generated by the clock circuit 60 via the dividers. The time position determining device is thus arranged to measure, following the detection of a passage of the resonator by its neutral position, a first time interval and a second time interval whose respective ends respectively define a first time and a second time interval. second instant which are located temporally, in any alternation of the oscillation of the mechanical resonator, respectively before and after the moment of the passage of this resonator by its neutral position.

With reference to FIGS. 7 to 9, there will be described a variant of the second embodiment of the invention, which defines an improvement of the control device according to the invention in connection with a 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 FIGS. 5 and 6, will not be described again here, the same for the control method that corresponds to that of this variant described above. The regulating device 66 differs from the regulating device 46 in that the sensor 24 has a standby mode or can even be de-energized. Thus, by state "OFF, it is understood that the sensor is temporarily rendered inactive and that it is then in a state of lower power consumption than in its" ON "state in which it detects the rocking of the mechanical resonator.

In the present variant, provision is made to put the sensor in its "OFF" state during most of each oscillation of the mechanical oscillator. For this purpose, the control circuit 58A is arranged to supply a control signal SCap to a switch 68 which controls the supply of the sensor 24, respectively which controls the state of this sensor between its state "ON" and its state " OFF. " As indicated by the signals SCap and Comp in FIG. 8, it is intended to put the sensor in its "OFF" state during a time interval T0ff TO and in its "ON" state during a time interval Ton in each oscillation period TO (note that TO = Toff + Tone) · Preferably, the Tone duration is predicted to be less than half-wave TO / 4 to minimize the energy consumption of the sensor. Indeed, it is possible that the digital signal "Comp" has pulses of relatively short duration, so that the detection of a pulse 42 per oscillation period only requires a relatively small time window T0n- In this case the comparator 50 delivers only one pulse 42 per oscillation period, so that the latch provided in the previous variant is removed. The comparator 50 directly supplies its output signal to the counter C2.

In the flowchart of FIG. 9, the power management of the sensor appears by putting the sensor in its "OFF" state in each sequence of the control method after detecting 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 integer of a position pulse 42 in the Ton range. However, for the regulation itself, the detection of the rising edge or the falling edge does not change anything. For the detection of the balance position, detection of the rising edge of the pulses is also possible to trigger the passage 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 rendered inactive directly after the start of these pulses. Such an implementation variant makes it possible to further reduce the consumption of the sensor.

When activating the regulating device, the sensor is put directly in its "ON" state pending the 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 is carried out, the sensor is put in its "OFF" state (OFF sensor) and the control sequence continues as in the previous variant. On the other hand, whether a braking pulse is generated or not, the control circuit 58A continues to follow the incrementation of the counter C1 until its value corresponds to the expected time interval T0ff. Then the sequence ends with a new sensor activation (Sensor ON) which also marks the beginning of a next sequence. The algorithm as given in FIG. 9 provides that the duration T0ff is greater than the duration Tal This condition indicates that the interval T0ff is substantially greater than an alternation TO / 2. In another variant, it is intended to detect the passage through the neutral position only once in a time interval nTO 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 the successive nTO intervals.

[0065] Referring to FIG. 10, there will be described hereinafter a third embodiment of a watch assembly 72, which differs from the previous modes in 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 magnetic magnet-coil system 80A, respectively 80B. The coils of the two magnetic systems are respectively controlled by two power supply circuits 82A and 82B which are electrically connected to the control circuit 22. The blades 38A and 38B define a first braking pad and a second braking pad. These two braking pads are arranged so that, during the application of the mechanical braking pulses, they come to exert on the balance respectively two radial forces diametrically opposed relative to the axis of rotation of the balance 16 and opposite directions. Of course, the force torque exerted by each of the two pads during an impulse

Claims (20)

braking is provided substantially equal to the other. Thus, the resultant forces in the general plane of the balance is substantially zero so that no radial force is exerted on the balance shaft during the braking pulses. This avoids mechanical stresses for the pivots of this balance shaft and more generally at the bearings associated with these pivots. Such an arrangement may advantageously be incorporated in a variant where braking is performed on the balance shaft or on a disc of relatively small diameter carried by this shaft. In an alternative embodiment, the braking force exerted on the rocker may be provided axially. In such a variant, it is advantageous to provide a braking device of the type proposed in FIG. 10. In this case, the actuator is arranged so that, during the application of the braking pulses, the first pad and the second pad come to exert on the balance two axial forces substantially aligned and in opposite directions. The force torque exerted by each of the two pads during a braking pulse is provided here also substantially equal to the other. An actuator forming a particular braking device is shown in FIG. 11. The actuator comprises a clock-type motor 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 rocker 16 of the resonator 14 when the 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 provided by the control circuit. claims 1. watch assembly (2), comprising: - a mechanism, - a mechanical resonator (14) capable of oscillating along an axis of oscillation around a neutral position corresponding to its state of minimum mechanical potential energy - A maintenance device (8, 10, 12) of the mechanical resonator forming with this mechanical resonator a mechanical oscillator which is arranged to clock the operation of said mechanism, each oscillation of the mechanical resonator defining two successive alternations between two extreme positions on the oscillation axis which define 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 control pulses to the mechanical resonator and an electronic control circuit (58, 58A) arranged to generate a co signal. which is supplied to the regulating pulse application device for activating it, - a sensor (24, 34) arranged to be able to detect the passage of the mechanical resonator by at least a certain given position on the oscillation axis ; the watch assembly being characterized in that the regulating device comprises a measuring device (50, C2) arranged to be able to measure, on the basis of position signals supplied by said sensor, a temporal drift of the mechanical oscillator relative to the auxiliary oscillator; in that the regulating pulse application device is formed by an electromechanical device arranged so as to be able to generate, in response to the control signal which is a function of the measured time drift, mechanical braking pulses applied to the mechanical resonator. , in particular at least one mechanical braking pulse exerting a certain force torque on the mechanical resonator when at least a certain time drift of the mechanical oscillator is detected; and in that the mechanical resonator defines a braking surface having a certain extent along said axis of oscillation and arranged so as to allow at least the application of said mechanical braking pulse with its triggering at a given instant in the course of time. an alternation among the two alternations of an oscillation of the mechanical oscillator regardless of the amplitude of oscillation of this mechanical oscillator in a range of amplitude having a certain extent and corresponding to a useful operating range of the mechanical oscillator, said given instant being selected so that the passage through the neutral position of the mechanical resonator does not occur during said mechanical braking pulse. Clock assembly according to claim 1, characterized in that the regulating pulse application device is formed by an actuator (36, 76, 78, 86) comprising a braking member (38, 38A, 38B, 90 ) which is arranged to be actuated, in response to said control signal, so as to be able to exert on a mechanical resonator oscillating member, defining said braking surface, a certain torque of mechanical force during said mechanical braking pulses. 3. Watchmaking assembly according to claim 2, characterized in that the regulating pulse application device is arranged in such a way that the braking energy of each mechanical braking pulse is less than a blocking energy, so as not to momentarily stop the mechanical resonator during the mechanical braking pulses; and in that the oscillating member and the braking member are arranged so that the mechanical braking pulses can be applied mainly by a dynamic dry friction between the braking member and said braking surface of the oscillating member. 4. Watchmaking assembly according to claim 2 or 3, characterized in that said actuator is arranged to actuate said braking member via a piezoelectric element or via an electromagnetic system. 5. watch assembly according to claim 4, characterized in that said actuator comprises a clock-type motor, said braking member being mounted on a rotor of the motor so as to exert a certain pressure on the oscillating member when the rotor performs a certain rotation generated by a supply of a motor coil in response to said control signal. 6. Horological assembly according to any one of claims 2 to 5, characterized in that the oscillating member is formed by a pivoting rocker comprising a serge which defines said braking surface, which is substantially circular; and in that the braking member comprises a movable part which defines a braking pad arranged so as to exert a certain pressure against the circular braking surface during the application of the mechanical braking pulses. 7. Watchmaking assembly according to any one of claims 2 to 5, characterized in that the oscillating member is formed by a pivoting rocker comprising a central shaft which defines, respectively which carries a part other than the beam of the beam defining said surface brake, which is substantially circular; and in that the braking member comprises a movable part which defines a braking pad arranged so as to exert a certain pressure against the circular braking surface during the application of the mechanical braking pulses. 8. Horological assembly according to claim 6 or 7, wherein said movable portion is a first portion and said braking pad is a first pad, characterized in that said braking member or another braking member also forming said actuator comprises minus a second moving part which defines a second braking pad; and in that said actuator is arranged so that, during the application of said mechanical braking pulses, the first and second pads come to exert on the balance wheel two diametrically opposite radial forces relative to the axis of rotation of the balance and of direction opposed. Clock assembly according to claim 6 or 7, wherein said moving part is a first part and said braking pad is a first pad, characterized in that said braking member or another braking member also forming said actuator comprises minus a second moving part which defines a second braking pad; and in that said actuator is arranged so that, during the application of said braking pulses, the first and second pads come to exert on the balance two substantially aligned axial forces and in opposite directions. 10. Watchmaking 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 by its neutral position at a median instant and a duration between an initial instant and a final instant respectively defined by the two extreme positions occupied by the mechanical resonator respectively at the beginning and at the end of the alternation; characterized in that said measuring device is arranged to be able to determine whether said time drift corresponds to at least some advance or at least some delay; and in that said control circuit and said control pulse applying device are arranged to be able to selectively apply to the mechanical resonator, when the measured time drift corresponds to said at least some advance, a first mechanical braking pulse ( P1) of which at least a major part intervenes between said initial moment (you) and said median moment (tNi) of an alternation (A1) and, when the measured time drift corresponds to said at least a certain delay, a second braking pulse mechanical mechanism (P2) at least a major part of which intervenes between said median instant (tN2) and said final instant (tF2) of an alternation (A2). 11. watch assembly according to claim 10, characterized in that the regulating device comprises a device for determining the temporal positions of the mechanical resonator, said determination device being arranged to be able to determine, in an alternation of an oscillation of the mechanical resonator, a first instant which occurs before said median instant and after said initial moment of this alternation and, also in an alternation of an oscillation of the mechanical resonator, a second instant which occurs after said median instant and before said final instant of this alternation; in that said control circuit is arranged to be able to selectively trigger said first mechanical braking pulse substantially at said first instant and said second mechanical braking pulse substantially at said second instant; and in that said braking surface of the mechanical resonator comprises a first sector, along said axis of oscillation, for the application of the first mechanical braking pulse starting substantially at said first instant and a second sector, according to said axis of oscillation , for the application of the second mechanical braking pulse beginning substantially at said second instant, regardless of the oscillation amplitude of said mechanical resonator in said useful operating range. 12. Horological assembly according to any one of the preceding claims, characterized in that said sensor is arranged to detect at least the passage of the mechanical resonator by its neutral position. 13. Horological assembly according to claim 12 dependent on claim 11, characterized in that said time position determining device is arranged to be able to measure, following the detection of a passage of the resonator by its neutral position, a first interval of time (TAi) and a second time interval (TA2) whose respective ends respectively define said first instant and said second instant. 14. Watchmaking assembly according to any one of the preceding claims, characterized in that said sensor is either an optical sensor comprising a light source, arranged so as to be able to send a light beam towards the mechanical resonator, and a detector of light, arranged to receive in return a light signal whose intensity varies periodically depending on the position of the mechanical resonator, either a capacitive sensor or an inductive sensor arranged so as to detect a variation of capacitance, respectively of inductance according to the position of the mechanical resonator, the inductive sensor preferably operating without magnetized material on the resonator. 15. Horological assembly according to any one of the preceding claims, characterized in that said braking surface has an extent allowing the application of said mechanical braking pulses with a trigger substantially at any time respective alternations of said mechanical oscillator. 16. Module for regulating the average frequency of a mechanical oscillator fitted with a clockwork mechanical movement, this regulation module comprising: a regulating device comprising an auxiliary oscillator (23), a device (26,60,62) arranged to be able to apply control pulses to a mechanical resonator forming said mechanical oscillator and an electronic control circuit (58,58A) arranged to generate a control signal which is supplied to the control pulse application device for the activate, - a sensor (24, 34) arranged to be able to detect the passage of the mechanical resonator by at least a certain given position on its axis of oscillation; characterized in that the regulating device comprises a measuring device (50, C2) arranged to be able to measure, on the basis of position signals supplied by said sensor, a temporal drift of the mechanical oscillator relative to the auxiliary oscillator; in that the regulating pulse application device is formed by an electromechanical device arranged in such a way as to generate, in response to the control signal which is a function of the measured time drift, mechanical braking pulses which can be applied to said mechanical resonator, in particular at least one mechanical braking pulse capable of exerting a certain braking force 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 arranged to allow the triggering of said mechanical braking pulse at a given instant during an alternation of the mechanical oscillator, this given instant being selected so that the passage through the neutral position of the mechanical resonator does not occur during said mechanical braking pulse. 17. Control module according to claim 16, characterized in that the regulating pulse application device is formed by an actuator (36, 76, 78, 86) comprising a braking member (38, 38A.38B, 90) which is arranged to be actuated, in response to said control signal, so as to be able to exert on a mechanical resonator oscillating member, defining said braking surface, a certain mechanical force during said mechanical braking pulses. 18. Control module according to claim 17, characterized in that the braking member is arranged so that the mechanical braking pulses can be applied mainly by a dynamic dry friction between said braking member and said braking surface of the braking element. oscillating organ. 19. Control module according to claim 18, characterized in that the braking member comprises a movable part which defines a braking pad arranged so as to be able to exert a certain pressure against said braking surface during the application of the mechanical braking pulses. 20. Control module according to claim 19, wherein said movable part is a first part and said braking pad is a first pad, characterized in that said braking member or another braking member also forming said actuator comprises at least a second moving part which defines a second braking pad; and in that said actuator can be arranged so that, during the application of said braking pulses, the first and second pads come to exert on the mechanical resonator two forces substantially aligned and in opposite directions.