EP3584645B1 - Timepiece comprising a mechanical movement of which the operation is controlled by an electromechanical device - Google Patents

Description

Technical area

• un mécanisme permettant d'indiquer une donnée temporelle,
• 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, chaque alternance présentant une première demi-alternance intervenant avant le passage du résonateur mécanique par sa position neutre et une seconde demi-alternance intervenant après le passage du résonateur mécanique par sa position neutre, et
• un dispositif pour réguler la fréquence moyenne de l'oscillateur mécanique, ce dispositif de régulation comprenant un oscillateur auxiliaire et un dispositif agencé pour appliquer sur commande des impulsions de régulation au résonateur mécanique.

The present invention relates to a timepiece comprising:

• a mechanism making it possible to indicate temporal data,
• 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 oscillation axis, which define the amplitude of oscillation of the mechanical oscillator, each half-wave having a first half-cycle occurring before the passage of the mechanical resonator through its neutral position and a second half-cycle occurring after the passage of the mechanical resonator through its neutral position, and
• a device for regulating the average frequency of the mechanical oscillator, this regulating device comprising an auxiliary oscillator and a device arranged to apply regulation pulses to the mechanical resonator on command.

By "timing the operation of a mechanism" is understood the fact of timing the movement of the movable elements of this mechanism when it is operating, in particular to determine the rotational speeds of its wheels.

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

Those skilled in the art are familiar with mechanical watch movements with which a device for regulating the frequency of their sprung balance which is of the electromechanical type is associated. More precisely, the regulation intervenes via a mechanical interaction between the sprung balance and the regulation device, the latter being arranged to act on the oscillating balance by a system formed by a stop arranged on the balance and an actuator provided with 'a movable finger which is actuated at a braking frequency in the direction of the stop, without however touching the rim of the balance. Such a timepiece is described in the document FR 2,162,404 . According to the concept proposed in this document, the aim is to synchronize the frequency of the mechanical oscillator with that of a quartz oscillator by an interaction between the finger and the stop when the mechanical oscillator exhibits a time drift relative to a frequency of instruction, the finger being provided to be able to either momentarily block the balance which is then stopped in its movement for a certain time interval (the stop resting against the finger moved in its direction during a return of the balance in the direction of its neutral position), or limit the amplitude of oscillation when the finger arrives against the stop while the balance turns in the direction of one of its two extreme angular positions (defining its amplitude), the finger then stopping the oscillation and the balance starting directly in the opposite direction.

Such a control system has many drawbacks and one can seriously doubt that it can form a functional system. The periodic actuation of the finger relative to the oscillating movement of the stopper and also a potentially large initial phase shift, for the oscillation of the stopper relative to the periodic movement of the finger in the direction of this stopper, pose several problems. It will be noted that the interaction between the finger and the stopper is limited to a single angular position of the balance, this angular position being defined by the angular position of the actuator relative to the axis of the sprung balance and the angular position stop on the balance at rest (defining its neutral position). In fact, the movement of the finger is provided to make it possible to stop the balance by contact with the stop, but the finger is arranged so as not to come into contact with the rim of the balance. In addition, it will be noted that the instant of an interaction between the finger and the stopper also depends on the amplitude of the oscillation of the sprung balance.

It will be noted that the desired synchronization appears improbable. This is because, in particular for a sprung balance whose frequency is greater than the setpoint frequency timing the back and forth movements of the finger and with a first interaction between the finger and the stopper which momentarily retains the balance returning from one of its two extreme angular positions (correction reducing the error), the second interaction, after numerous oscillations without the stop touching the finger during its reciprocating movement, will certainly be a stop of the balance by the finger with immediate reversal of its direction of motion. oscillation, by the fact that the stop abuts against the finger while the balance rotates in the direction of said extreme angular position (correction increasing the error). Thus, not only is there an uncorrected time drift during a time interval which may be long, for example several hundred periods of oscillation, but certain interactions between the finger and the stopper increase the time drift instead of the reduce! It will also be noted that the phase shift of the oscillation of the stop, and therefore of the sprung balance, during the second aforementioned interaction can be significant depending on the relative angular position between the finger and the stop (balance in its neutral position).

One can thus doubt that the desired synchronization is obtained. In addition, in particular if the natural frequency of the sprung balance is close to but not equal to the setpoint frequency, situations where the finger is blocked in its movement towards the balance by the stop which is located at this instant in front of the finger are predictable. Such parasitic interactions can damage the mechanical oscillator and / or the actuator. In addition, this practically limits the tangential extent of the finger. Finally, the duration of keeping the finger in the position of interaction with the stop must be relatively short, therefore limiting a correction causing a delay.

In conclusion, the operation of the timepiece proposed in the document FR 2,162,404 seems to the skilled person to be highly improbable, and he shies away from such teaching.

The document EP 1164441 A1 describes a mechanical timepiece associated with an electromechanical device for correcting a temporal drift of its sprung balance forming, with a conventional escapement, a mechanical oscillator. In a first embodiment, provision is made to measure an advance taken by the analog display over a given period, for example one hour, via a measurement of the time required for a wheel set, driving the analog display, to perform a number of revolutions corresponding in theory to this given period, and to carry out a correction by the electromechanical device which then comes to block the escape wheel during a time interval corresponding to said advance. By blocking the escape wheel during said time interval, the sprung balance is stopped in its oscillation just before it reaches its neutral position during a first half-cycle (as defined in the technical field) . This first embodiment has various drawbacks, in particular because it is only capable of correcting an advance in the rate of the timepiece; which requires adjusting the mechanical oscillator so that its frequency is greater than a nominal frequency. Then, stopping the sprung balance close to its neutral position generates a relatively large shock between the balance and the fork of the anchor. In addition, when the escape wheel is released again, the sprung balance is initially stationary because it will have almost no initial amplitude. Although the sprung balance is stopped indirectly since the electromechanical correction device provided blocks the escape wheel, the preamble of claim 1 appended refers to this first embodiment.

The second embodiment described in the document EP 1164441 A1 has the advantage of allowing a correction of an advance or a delay in the operation of the timepiece. To this end, this second embodiment relates to a relatively complex electromechanical correction device which is arranged so as to be able to vary the active length of the hairspring forming the sprung balance.

Finally, we know the document EP 1241538 A1 which describes a watch movement whose mechanical resonator is associated with an electromagnetic device for regulating the average frequency of this mechanical resonator, this electromagnetic regulating device being arranged to be able to apply electromagnetic braking to the mechanical resonator. In particular, depending on whether an advance or a delay is detected in the operation of the mechanical movement, the instants provided for the braking pulses are selected respectively before and after a passage of the mechanical resonator through its neutral position to respectively decrease and increase the frequency. instantaneous of this mechanical resonator, as the Airy theorem teaches.

Summary of the invention

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

In the context of the present invention, it is generally sought to improve the precision of the rate of a mechanical watch movement, that is to say to reduce the daily time drift of this mechanical movement. In particular, the present invention seeks to achieve such an aim for a mechanical watch movement, the rate of which is initially adjusted as well as possible. Indeed, a general aim of the invention is to find a device for correcting a temporal drift of a movement. mechanical, namely a device for correcting its rate to increase its precision, without however renouncing that it can operate independently with the best precision that it is possible for it to have thanks to its own characteristics, c 'that is to say in the absence of the correction device or when the latter is inactive.

To this end, the present invention relates to a timepiece as defined in claim 1 attached.

Thanks to the characteristics of the invention, it is possible to reliably and efficiently regulate the rate of the mechanical movement, whether the latter has a time drift corresponding to a certain delay or to a certain advance.

In a main embodiment, the electromechanical device is formed by an actuator comprising a stop member defining a movable stop for a projecting part of the mechanical resonator, the stop member being arranged movable between a non-interaction position, where it is outside a space swept by the protruding part when the mechanical resonator oscillates with an amplitude in the useful operating range, and an interaction position where it is partially located in this space swept by the protruding part. The stop member can be actuated on command to stop, via the protruding part abutting against the stop member then placed in its interaction position, the oscillating movement of the mechanical resonator in the direction of alternation given and selectively in the first half-wave or the second half-wave of this half-wave according to whether, respectively, at least a certain advance or at least a certain delay has been detected.

Thus, in the main embodiment, on the one hand, the electromechanical device is arranged so that, when the stop member is actuated to stop the mechanical resonator in a first half-wave, the stop member momentarily prevents, after the projecting part has abutted against this stop member, the mechanical resonator from continue the movement of natural oscillation specific to this first half-cycle, so that this movement of natural oscillation during the first half-cycle is momentarily interrupted before it is continued, with a certain time phase shift, after removal of the shut-off device. On the other hand, the electromechanical device is arranged so that, when the stop member is actuated to stop the mechanical resonator in a second half-wave, it thus prematurely ends this second half-wave without blocking the resonator. mechanical but by reversing the direction of the oscillation movement of the mechanical resonator, so that this mechanical resonator begins, following an instantaneous or almost instantaneous stop caused by the collision of the protruding part with the stop member, directly an alternation next.

Brief description of the figures

• La Figure 1 est une vue, en partie schématique, d'un mode de réalisation principal d'une pièce d'horlogerie selon l'invention,
• La Figure 2 montre le résonateur mécanique de la pièce d'horlogerie de la Figure 1 et schématiquement les éléments du dispositif de régulation,
• La Figure 3 montre le schéma électrique du circuit de régulation incorporé dans le dispositif de régulation de la Figure 2,
• Les Figures 4A et 4B représentent graphiquement le mouvement d'oscillation du résonateur mécanique de la Figure 3, dans le cas d'un premier mode d'interaction prévu entre le résonateur mécanique et un actionneur du dispositif de régulation, lors d'une correction d'un certain retard, respectivement d'une certaine avance détecté(e) dans la marche de la pièce d'horlogerie,
• Les Figures 5A et 5B sont des graphes similaires à ceux des Figures 4A et 4B dans le cas d'un deuxième mode d'interaction prévu entre le résonateur mécanique et un actionneur du dispositif de régulation, et
• La Figure 6 est un organigramme décrivant un mode de fonctionnement du dispositif de régulation du mode de réalisation principal.

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 view, in part schematic, of a main embodiment of a timepiece according to the invention,
• The Figure 2 shows the mechanical resonator of the timepiece of the Figure 1 and schematically the elements of the regulation device,
• The Figure 3 shows the electrical diagram of the regulation circuit incorporated in the regulation device of the Figure 2 ,
• The Figures 4A and 4B graphically represent the oscillation movement of the mechanical resonator of the Figure 3 , in the case of a first mode of interaction provided between the mechanical resonator and an actuator of the regulation device, during a correction of a certain delay, respectively of a certain advance detected in the operation of the timepiece,
• The Figures 5A and 5B are graphs similar to those of Figures 4A and 4B in the case of a second mode of interaction provided between the mechanical resonator and an actuator of the regulation device, and
• The Figure 6 is a flowchart describing a mode of operation of the controller of the main embodiment.

Detailed description of the invention

With reference to the appended figures, a main embodiment of a timepiece 2 according to the invention will be described. It comprises a watch movement 4 and a regulating device 22 designed to be able to generate phase shifts in the oscillation movement of a mechanical resonator 6 arranged to clock the rate of the watch movement 4.

The mechanical movement 4 comprises at least one mechanism 12 indicating a temporal datum, this mechanism comprising a gear 16 driven by a barrel 14. The mechanical resonator 6 is formed by a balance 8 and a hairspring 10. The indicator mechanism 12 comprises a maintenance device of the mechanical resonator, this maintenance device being formed by an escapement 18. The escapement and the mechanical resonator constitute a mechanical oscillator. The escapement conventionally comprises an anchor and an escape wheel, the latter being kinematically connected to the barrel via the gear 16. The mechanical resonator is capable of oscillating around a neutral position (rest position / angular position zero), corresponding to its state of minimum potential energy, along a circular geometric axis, that is to say to present an angular oscillation movement around the axis of rotation 9 of the balance. As the position of the balance is given by its angular position, it is understood that the radius of the circular geometric axis is unimportant. Generally, the axis of oscillation defines a direction of oscillation which indicates the nature of the movement of the mechanical resonator, which may be linear in another specific embodiment. Each oscillation of the mechanical resonator has two successive alternations between two extreme positions on the axis of oscillation, these extreme positions defining the amplitude of oscillation of the mechanical oscillator from the neutral position.

• un oscillateur auxiliaire 26 formé par un résonateur à quartz,
• un dispositif électromécanique, formé par un actionneur 28, qui est susceptible d'arrêter au cours d'une alternance au moins momentanément le mouvement d'oscillation du résonateur mécanique 6 dans le sens naturel qu'il présente au cours de cette alternance,
• un circuit de régulation 24 associé à l'oscillateur auxiliaire 26 et agencé pour pouvoir générer un signal de commande Sc destiné à l'actionneur pour l'activer, et
• un capteur 32 agencé pour pouvoir détecter le passage du résonateur mécanique par au moins une certaine position angulaire donnée.

The timepiece comprises a system for regulating the frequency of the mechanical oscillator, this regulation system being formed on the one hand by a projecting part 20 arranged on the rim of the balance 8 and, on the other hand, by a device. regulation 22 comprising:

• an auxiliary oscillator 26 formed by a quartz resonator,
• an electromechanical device, formed by an actuator 28, which is capable of stopping during an alternation at least momentarily the oscillation movement of the mechanical resonator 6 in the natural direction that it presents during this alternation,
• a regulation circuit 24 associated with the auxiliary oscillator 26 and arranged to be able to generate a control signal Sc intended for the actuator to activate it, and
• a sensor 32 arranged to be able to detect the passage of the mechanical resonator through at least a certain given angular position.

The actuator 28 comprises an electrical actuation circuit 29 and a stop member 30 of the mechanical resonator which is formed by a movable stop, which is defined in the variant of Figure 2 by a finger arranged at the end of a bar 31 made of piezoelectric material. This bar flexes when an electric voltage is applied by the electric circuit 29 between two electrodes arranged on two opposite faces of its side faces. The circuit 29 is connected to the regulation circuit 24 which supplies it with a control signal Sc to actuate the movable stop 30 in the direction of the rim of the balance without however touching it. In another embodiment, the actuator comprises an electromagnetic system arranged to be able to move the stop member on command between a position of interaction with the projection 20 and a position of non-interaction. This system electromagnetic can be formed by a fixed coil and a magnet placed on a flexible bar carrying a finger defining the stop, or vice versa. Alternatively, the movable stopper can be formed by a core made of ferromagnetic material which penetrates inside a coil, which moves this core along its central axis when it is supplied (a return spring is for example associated with the core) .

In the variant shown, the sensor 32 is an optical sensor comprising a light source, arranged so as to be able to send a beam of light in the direction of the rim of the balance whose lateral surface 48 is reflective (in particular polished), and a detector light arranged to receive in return a light signal 33 reflected by the side surface. The optical sensor is provided here to detect the passage of the mechanical resonator through its neutral position and also to detect the direction of the oscillation movement so as to determine in which alternation of the oscillation, among the two alternations defining each oscillation period , this detection takes place. For this purpose, provision is made to vary the intensity of the detected optical signal S _L as a function of the angular position of the mechanical resonator. More specifically, the side surface 48 comprises a marking 50 (shown in Figure 2 on the rim for the purpose of explaining the detection) consisting of two absorbent zones of different widths. For example, the zero crossing is defined by the interior line (relative to the pattern formed by the two absorbent zones) of the zone of greatest width. It will be understood that the different widths of the two absorbent zones easily make it possible to determine the direction of rotation of the balance 8. The detection circuit 36 arranged in the regulation circuit 24, on the one hand, detects the passage of the marking in front of the sensor. and supplies at each detection a signal S _P to a flip-flop 38 of a measuring device 34 and, on the other hand, performs the detection of the direction of the oscillation of the balance during each detection of the passage of the marking opposite the sensor and supplies a signal S _N to a logic control circuit 42 relating to the current alternation.

It will be noted that the signal S _N can indicate for each detection of the marking the direction of oscillation to the logic circuit 42 or indicate to it only when a predefined alternation per period of oscillation is in progress, given that the interaction between the actuator and the balance is provided here only between the passage of the balance through the neutral position in a predefined alternation, selected from the first alternation and the second alternation of a period of oscillation, and the passage of this balance through the neutral position of the 'alternation which succeeds it, as will be clearly understood in the remainder of the description of the invention. It will therefore be noted that, in a variant, the flip-flop 38 can be omitted because the detection circuit can easily transmit a single pulse per period of oscillation via the signal S _P. In another variant, either a capacitive sensor or an inductive sensor is provided, arranged so as to be able to detect a variation in capacitance, respectively inductance, as a function of the angular position of the mechanical resonator. Regarding the power supply to the regulation device, there is provided an energy source associated with a device 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.

Next, the regulation device comprises a measuring device 34 arranged to be able to measure, on the basis of a detection signal S _L supplied by the sensor 32, a time drift of the mechanical oscillator relative to the auxiliary oscillator 26. The measuring device is formed of the detection circuit 36 already described, of a flip-flop 38 and of a bidirectional counter C2 which receives at one of its two inputs the signal S _P , which supplies one pulse per period of oscillation. detected using the sensor, and at the other of its inputs a clock signal S _hor generated by the auxiliary oscillator 26, the clock circuit 40 of which supplies a reference signal to a divider having two stages DIV1 and DIV2. The first stage of the divider supplies a frequency signal to a time counter C1 and to a timer 44. The state of the counter C2 thus gives the time drift of the mechanism 12 in absolute value since the activation of the regulation device. The state of the counter C2 is supplied to the logic control circuit 42 which is arranged to be able to determine whether the time drift corresponds to at least a certain advance or at least a certain delay, by a comparison with reference values N1 and N2. , as shown in Figure 6 .

In general, according to the invention, the regulation circuit 24 and the actuator 28 are designed to be able to stop during at least one given half-wave, when the mechanical resonator oscillates with an amplitude included in a useful operating range, the oscillation movement of the mechanical resonator in the direction of this given half-wave and selectively either during a first half-cycle of a given half-wave, occurring before the passage of the mechanical resonator through its neutral position in this given half-wave, when the measured time drift corresponds to at least a certain advance; or during a second half-cycle of at least one given half-cycle, occurring after the mechanical resonator has passed through its neutral position in each given half-cycle, when the measured time drift corresponds to at least a certain delay. In the latter case, the oscillation movement is stopped so as to prematurely end each second half-cycle, relative to the nominal duration of a natural half-cycle, and to start the next half-cycle at an intervening time. before this nominal duration has been reached since the last passage of the mechanical resonator through its neutral position. To do this, in the embodiment described here, the stop member 30 of the actuator 28 defines a movable stop for a projecting part 20 of the mechanical resonator. It will be noted that, preferably, the pendulum is designed so as to be balanced.

The stop member is arranged to be movable between a non-interaction position, where it is outside a space swept by the projecting part when the mechanical resonator oscillates with an amplitude in the useful operating range, and an interaction position where it is located partially in this space swept by the projecting part so as to be able to stop the balance 8 in the direction of its oscillation movement when the projecting part 20 abuts against the stop member. The stop member 30 (which is movable along a substantially radial displacement axis) is positioned angularly, relative to the axis of oscillation of the balance, so that it presents, when it is in its position of 'interaction, a _{non-zero angular offset θ B} with the projecting part 20 of the balance when the mechanical resonator is in its neutral position, which corresponds to the Figure 2 to a positioning of the protrusion 20 at an angular position '0'. This angular position is detected by the sensor 32 via the marking 50, which appears opposite this sensor when the protruding part is positioned at the zero angle. The angular offset θ _B is expected to be less than the minimum amplitude of the useful operating range of the mechanical oscillator so as to allow correction of a time drift in all of this useful operating range. For example, the value of the angular offset is between 60 ° and 150 °, preferably between 90 ° and 120 °.

According to the invention, as already indicated, provision is made to actuate the stop member 30 on command to stop the balance 8 during a first half-cycle or at least one second half-cycle depending on whether , respectively, at least some advance or at least some delay has been detected. Hereinafter, with reference to Figures 4A to 6 , two modes of interaction ( Figures 4A, 4B ; Figures 5A, 5B ) provided between the stop member (movable stop) and the projecting part of the balance to regulate the frequency of the mechanical oscillator and therefore the running of the watch movement, selectively generating a positive phase shift in the oscillation of the balance to correct some delay ( Figures 4A , 5A ) and a negative phase shift to correct a certain lead ( Figures 4B , 5B ).

To the Figures 4A to 5B the angular position θ of the balance 8 as a function of time is shown. As indicated in Figure 6 , when the sensor detects a passage of the balance through its neutral position and a counterclockwise direction of the oscillation movement (counterclockwise for the variant shown, given that here the interaction between the stop member and the protruding part can occur only after a passage of this protruding part by the angle '0' in the counterclockwise direction), the logic circuit 42 reinitializes the time counter C1 and detects whether the bidirectional counter C2 has at least a certain advance, that is to say C2> N1, or at least a certain delay, namely C2 <- N2; N1 and N2 being natural numbers greater than zero.

Each period of natural oscillation T0 of the mechanical oscillator comprises a first natural half-wave A1, of nominal duration T0 / 2 (oscillation movement in a first direction between two extreme angular positions of the mechanical resonator), and a second natural half-wave A2 (oscillation movement in the opposite direction to the first direction between the two extreme angular positions) of the same nominal duration T0 / 2. The first natural half-wave A1 consists of a first half-wave D1 ₁ , of nominal duration T0 / 4 and occurring before the passage of the mechanical resonator through its neutral position (angular position '0'), and of a second half-wave. half-wave D2 ₁ of the same nominal duration T0 / 4 and occurring after the mechanical resonator has passed through its neutral position. Likewise, the second natural half-wave A2 consists of a first half-wave D1 ₂ , of nominal duration T0 / 4 and occurring before the passage of the mechanical resonator through its neutral position, and of a second half-wave D2 ₂ of same nominal duration T0 / 4 and occurring after the mechanical resonator has passed through its neutral position.

To the Figure 4A , the regulation device performs a correction following the detection of a certain delay. To this end, during a second alternation A2 *, the stop device is actuated directly after detection of the passage of the balance through the neutral position (signal Sc), for a period of T0 / 4 corresponding to that of a half-wave, to stop the mechanical resonator during the second half-wave D2 ₂ * of the second half-wave A2 *, that is to say after passing through the neutral position and before reaching the extreme angular position of the natural oscillation (undisturbed oscillation). To do this, after the logic control circuit 42 has received from the detection circuit 36, via the signal S _N , the information that a second half-wave of a half-wave in the counterclockwise direction begins, this logic circuit 42 generates a signal S _D for triggering a timer 44 which is arranged so as to supply, following reception of the trigger signal, a control signal Sc to the electric circuit 29 of the actuator 28 to activate the latter for an interval of time T _R equal to T0 / 4 in the variant described here. Thus, the stop member 30 is actuated and placed in its interaction position during the time interval T _R. The result of this action is that the projecting part 20 of the balance comes into abutment against the stop member during the second half-cycle in question when the projecting part of the balance reaches the angular position θ _B. This event prematurely ends this second half-wave by reversing the direction of the oscillation movement of the mechanical resonator without blocking it, so that this mechanical resonator then directly begins a following half-wave A1 ^F. Thus, a positive phase shift DP is obtained, as shown by the graph of the Figure 4A , and the duration of the alternation A2 * is equal to T3, this value being less than the nominal value T0 / 2. This positive phase shift makes it possible to compensate for a certain delay. It will be noted that this corrective action is generally carried out successively in several periods of oscillation or alternations as a function of the delay detected.

To the Figure 4B , the regulating device performs a correction following the detection of a certain advance. To this end, during a first alternation A1 *, the stop device is actuated after a time delay of T0 / 4 following detection of the passage of the balance through the neutral position, for a period T0 / 4 corresponding to that of a half-wave, to thus stop the mechanical resonator during the first half-wave D1 ₁ * of the first half-wave A1 *, that is to say between the extreme angular position of the natural oscillation ending the previous natural half-wave A2 and the passage through the neutral position of the mechanical resonator during the first half-wave A1 *. To do this, after the logic control circuit 42 has received from the detection circuit 36, via the signal S _N , the information that a second half-wave of a half-wave (counterclockwise) begins, this logic circuit 42 resets time counter C1 and waits for the latter to measure a time interval equal to T0 / 4. Then, it generates a signal S _D to trigger the timer 44 which then supplies a control signal Sc to the electric circuit 29 of the actuator 28 to activate the latter during a time interval T _R equal to T0 / 4 in the variant described. here. In another variant, it will be noted that this time interval can be provided much longer in order to effect a greater correction. In a specific variant, the duration of this time interval can be varied as a function of different values detected for the advance of the mechanical oscillator.

Thus, at the end of the time delay which allows the natural alternation A2 in progress to end, the stop member 30 is actuated substantially at the start of the alternation A1 * and placed in its interaction position during l time interval T _R. The result of this action is that the projecting part 20 of the balance comes into abutment against the stop member during the first half-cycle in question when the projecting part of the balance reaches the angular position θ _B while moving towards the position neutral. This event stops the balance and the stop member momentarily blocks the mechanical resonator so that the first half-wave D1 ₁ * is momentarily interrupted before it is continued. A negative phase shift DN is thus obtained, as shown by the graph of the Figure 4B , and the duration of the alternation A1 * is equal to T4, this value being greater than the nominal value T0 / 2. This negative phase shift makes it possible to compensate for a certain advance. This corrective action can be carried out successively in several oscillation periods according to the detected advance.

In the first mode of interaction of Figures 4A and 4B , when the stop member ends a second half-wave to correct a delay, it substantially absorbs the kinetic energy of the sprung balance, so that the next first half-wave D1 ₁ ^F is started with a speed substantially zero and has substantially a nominal duration T0 / 4. Thus, the alternation A1 ^F has substantially a nominal duration T0 / 2 and a lesser amplitude, which depends on the angular offset θ _B. In the case of the correction of an advance, the interrupted alternation is continued following the withdrawal of the stop member by a recovery alternation having a lesser amplitude and substantially a nominal duration T0 / 2. The amplitude of this alternation of recovery is substantially equal to that of the alternation A1 ^F.

To the Figures 5A and 5B is shown the angular position of the balance during an interaction with the stop member in the case of a second mode of interaction to correct respectively a delay and an advance in the rate of the watch movement. While in the first mode of interaction the kinetic energy of the mechanical resonator is absorbed by the actuator, the stop member and the projecting part of the balance are arranged in the second mode of interaction so as to present between them , when the stop member is placed on command in its interaction position, an elastic shock to stop the oscillating movement of the mechanical resonator in the natural direction of the considered alternation, the stop thus generated being instantaneous or almost instantaneous and a reversal of the direction of the oscillation movement occurring with a certain kinetic energy given back to the mechanical resonator by the stop member following the instantaneous or almost instantaneous stopping of this mechanical resonator. It will be noted that the 'almost instantaneous' alternative mentioned indicates that practically the stopping may have a very short duration even if no specific member comes to block the balance. Thus, stopping (zero speed) may take a few milliseconds before the balance starts up again in the opposite direction.

To the Figure 5A where a positive phase shift is generated as in Figure 4A to at least partially correct a delay, it can be seen that the first half-cycle D1 ₁ ^F following the elastic stop of the balance has a greatly shortened duration, its value being substantially equal to that of the second half-cycle D2 ₂ * during from which the balance has stopped. It follows from this situation that the duration T6 of the halfwave A1 ^F is substantially equal to the shortened duration T5 of the halfwave A2 *, so that the positive phase shift generated in the oscillation of the mechanical resonator is here greater than that obtained in the case of Figure 4A .

To the Figure 5B where a negative phase shift is generated as at Figure 4B to correct an advance, we see that the first half-wave D1 ₁ * during which the stopping of the mechanical resonator occurs is greatly disturbed by the fact that the elastic shock generates an angular backward movement, in the opposite direction to that of 'a first natural alternation A1, so that the alternation A1 * presents after the elastic shock an angular path greater than that of a natural alternation and therefore a total duration T7 much greater than the nominal duration T0 / 2 and greater than the duration T4 ( Figure 4B ). Thus, the negative phase shift obtained here is greater than that obtained in the case of Figure 4B .

Finally, it will be noted that the projecting part of the balance can be arranged differently in other variant embodiments. Thus, in a particular variant, the protruding part is arranged axially below the rim, the stop member being movable in a geometric plane situated below that of the balance and crossed by the protruding part. Other variants can be provided by those skilled in the art while remaining within the scope of the present invention. In particular, other mechanical resonators can be provided. In various variants, other electromechanical devices capable of stopping the mechanical resonator during a first half-cycle and a second half-cycle can be arranged in the timepiece.

Claims (10)

1. Timepiece (2) comprising:

   - a mechanism for indicating a temporal data item,

   - a mechanical resonator (6) suitable for having an oscillation movement along a given oscillation axis about a neutral position corresponding to the minimum potential energy state thereof,

   - a maintenance device (18) of the mechanical resonator forming with this mechanical resonator a mechanical oscillator arranged to pace the working of said mechanism, each oscillation of the mechanical resonator having two successive alternations (A1, A2) between two extreme positions, on the oscillation axis, which define the oscillation amplitude of the mechanical oscillator from the neutral position, each alternation having a first half-alternation and a second half-alternation occurring respectively before and after the passage of the mechanical resonator via the neutral position,

   - a device (22) for regulating the mean frequency of the mechanical oscillator, this regulation device comprising an auxiliary oscillator (26), an electromechanical device (28) suitable for stopping during an alternation at least momentarily the oscillation movement of the mechanical resonator in the direction of this alternation, and a regulation circuit (24) arranged to be able to generate a control signal intended for the electromechanical device to activate same;

   the regulation device comprising a sensor (32), arranged to be able to detect the passage of the mechanical resonator via at least a certain given position on the oscillation axis, and a measuring device (34) arranged to be able to measure, on the basis of a detection signal (S_P) supplied by the sensor, a potential time drift of the mechanical oscillator relative to the auxiliary oscillator; the measuring device and the regulation circuit being arranged to be able to determine whether the time drift corresponds to at least a certain gain; the regulation circuit and the electromechanical device being arranged to be able, when the time drift measured corresponds to said at least a certain gain, to stop momentarily, during the first half-alternation of a given alternation, the oscillation movement of the mechanical resonator in the direction of this alternation, so as to prolong this first half-alternation relative to a nominal duration (T0/4) envisaged for each natural half-alternation;
   characterised in that the measuring device and the regulation circuit are arranged to further be able to determine whether the time drift corresponds at least a certain loss, and in that the regulation circuit and the measuring device are arranged to further be able, when the mechanical resonator oscillates with an amplitude within a useful operating range and the time drift measured corresponds to said at least a certain loss, to stop the oscillation movement of the mechanical resonator during the second half-alternation of at least a given alternation so as to prematurely put an end to this second half-alternation, relative to said nominal duration, and to start a next alternation at a time occurring before this nominal duration has been attained since the last passage of the mechanical resonator via the neutral position thereof.
2. Timepiece according to claim 1, characterised in that the electromechanical device is formed by an actuator comprising a stopping member (30) defining a mobile banking for a projecting part (20) of the mechanical resonator, the stopping member being arranged mobile between a non-interaction position, where the stopping member is outside an area swept by the projecting part when the mechanical resonator oscillates with an amplitude in said useful operating range, and an interaction position where the stopping member is situated partially in this area swept by the projecting part; and in that the stopping member may be actuated on command to stop, via the projecting part abutting against the stopping member then placed in the interaction position thereof, the oscillation movement of the mechanical resonator in the direction of the given alternation and selectively in the first half-alternation or the second half-alternation of this alternation according to whether, respectively, at least a certain gain or at least a certain loss has been detected.
3. Timepiece according to claim 2, characterised in that the electromechanical device is arranged such that, when the stopping member (30) is actuated to stop the mechanical resonator in a first half-alternation, this stopping member locks momentarily the mechanical resonator (6), such that the oscillation movement during this first half-alternation is momentarily interrupted before the oscillation movement is continued after removing the stopping member, and such that, when the stopping member is actuated to stop the mechanical resonator in a second half-alternation, this stopping member prematurely puts an end to this second half-alternation without locking the mechanical resonator but by inverting the direction of the oscillation movement of the mechanical resonator, so that the mechanical resonator then directly starts a next alternation, following an instantaneous or quasi-instantaneous stoppage of this mechanical resonator induced by a shock of the projecting part against the stopping member.
4. Timepiece according to claim 3, characterised in that, when the stopping member prematurely puts an end to a second half-alternation, this stopping member absorbs substantially the kinetic energy of the mechanical resonator such that the next alternation is started with a substantially zero speed.
5. Timepiece according to claim 2, characterised in that said stopping member and said projecting part of the mechanical resonator are arranged so as to exhibit therebetween, when the stopping member is placed on command in the interaction position thereof, a substantially elastic shock to stop the oscillation movement of the mechanical resonator in the direction of the given alternation, the stoppage thus induced being instantaneous or quasi-instantaneous and an inversion of the direction of the oscillation movement occurring with a certain kinetic energy restored to the mechanical resonator following the instantaneous or quasi-instantaneous stoppage of this mechanical resonator.
6. Timepiece according to any one of claims 2 to 5, characterised in that the actuator comprises a piezoelectric element or an electromagnetic system arranged to be able to move the stopping member (30) between the interaction and non-interaction positions thereof on command.
7. Timepiece according to any one of claims 2 to 6, characterised in that the sensor (32) is arranged to detect at least the passage of the mechanical resonator via the neutral position thereof; and in that the regulation circuit (24) is arranged such that, when at least a certain gain is detected, this regulation circuit sends a control signal (Sc) to the electromechanical device directly after a detection of a passage of the mechanical resonator (6) via the neutral position thereof so that the electromechanical device actuates the stopping member (30) by placing this stopping member in the interaction position thereof for a duration substantially equal to the nominal duration (T0/4) of a natural half-alternation.
8. Timepiece according to claim 7, characterised in that said regulation circuit (24) comprises a time counter (C1) and is arranged so as to be able, when at least a certain gain is detected, to reset the time counter after detection of a passage of the mechanical resonator via the neutral position thereof to measure a time delay period before sending the control signal (Sc) to the electromechanical device so that this electromechanical device actuates the stopping member thereof by placing this stopping member in the interaction position thereof for a predefined or determined duration.
9. Timepiece according to any one of claims 2 to 8, wherein said mechanical resonator is formed by a balance (8) and a balance-spring (10), the balance bearing said projecting part (20); characterised in that said stopping member (30) is positioned angularly, relative to the oscillation axis (9) of the balance, so that this stopping member has, when in the interaction position thereof, an angular lag (θ_B) different to zero with the projecting part when the mechanical resonator is in the neutral position thereof, this angular lag being envisaged to be less than the minimum amplitude of said useful operating range.
10. Timepiece according to any one of the preceding claims, characterised in that the sensor is either an optical sensor (32) comprising a light source, arranged so as to be able to send a light beam towards the mechanical resonator, and a light detector arranged to receive in return a light signal the intensity whereof varies according to the position of the mechanical resonator along said oscillation axis, or a capacitive sensor or an inductive sensor arranged to be able to detect a variation of capacitance, respectively inductance according to the position of the mechanical resonator along said oscillation axis.

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