EP2908191B1 - Adjustment of the frequency of a clock resonator by changing the rigidity of a resilient return means - Google Patents

Description

Field of the invention

The invention relates to a method of maintenance and frequency regulation, around its natural frequency, of a clock resonator mechanism comprising at least one elastic return means which comprises at least one hairspring or a twist wire or a flexible guidance, in which at least one regulating device is used which acts on said resonator mechanism with a periodic movement.

The invention also relates to a timepiece movement comprising at least one clock resonator mechanism designed to oscillate at a natural frequency, said clock resonator mechanism comprising at least one elastic return means comprising at least one hairspring or wire. torsion or flexible guidance.

The invention also relates to a timepiece, more particularly a watch, comprising at least one such timepiece movement.

The invention relates to the field of time bases in mechanical watchmaking, in particular based on a balance-spring balance spring mechanism.

Invention background

The quest to improve the performance of watch time bases is a constant concern. An important limitation to the chronometric performance of mechanical watches lies in the use of conventional impulse escapements, and no exhaust solution has ever been able to avoid this type of disturbance.

The document EP 1 843 227 A1 from the same applicant describes a coupled resonator comprising a first low frequency resonator for example of the order of a few hertz and a second higher frequency resonator, for example of the order of a kilohertz. The invention is characterized in that the first resonator and the second resonator comprise permanent mechanical coupling means, said coupling making it possible to stabilize the frequency in the event of external disturbances, for example in the event of shocks.

The document CH 615 314 A3 on behalf of PATEK PHILIPPE SA describes a mobile clock movement regulation assembly, comprising an oscillating balance mechanically maintained by a spiral spring, and a vibrating member coupled magnetically with a fixed member for synchronizing the balance. The balance and the vibrating member are constituted by a single mobile element vibrating and oscillating simultaneously. The vibration frequency of the vibrating member is an integer multiple of the balance's oscillation frequency.

Summary of the invention

The invention proposes to manufacture the most precise time base possible.

To this end, the invention relates to a method of maintenance and frequency regulation, around its natural frequency, of a clock resonator mechanism, according to claim 1.

The invention also relates to a timepiece movement comprising at least one clock resonator mechanism designed to oscillate at a natural frequency, said clock resonator mechanism comprising at least one elastic return means comprising at least one hairspring or wire. torsion or flexible guide according to claim 7.

The invention also relates to a timepiece, more particularly a watch, comprising at least one such timepiece movement.

Brief description of the drawings

• la figure 1 représente, de façon schématisée, un pendule dont on fait varier la longueur ;
• la figure 2 représente, de façon schématisée, un diapason avec deux balanciers-spiraux attachés l'un à l'autre
• la figure 3 représente, de façon schématisée, et partielle, le spiral d'un ensemble balancier-spiral, avec une spire additionnelle fixée à ce spiral et venant en doublure localement avec la courbe terminale externe du spiral, et un dispositif régulateur pour effectuer des torsions de sens opposés sur la courbe terminale externe et sur cette spire additionnelle ;
• la figure 4 représente, de façon similaire à la figure 3, une spire additionnelle et un dispositif régulateur actionnant une extrémité de cette spire additionnelle ;
• la figure 5 représente un spiral auquel est fixé un bras, et un dispositif régulateur actionnant une extrémité de ce bras ;
• la figure 6 illustre un spiral avec, au voisinage de sa courbe terminale externe, une autre spire qui est maintenue à une première extrémité par un appui manœuvré par un dispositif régulateur, et qui est libre à une deuxième extrémité agencée pour venir périodiquement en contact avec la courbe terminale externe sous l'action du dispositif régulateur sur cet appui ;
• la figure 7 illustre un spiral comportant deux lames conductrices séparées par des éléments isolants, et les figures 7A et 7B montrent, en coupe, deux sections de ce spiral selon les champs électriques appliqués à ce spiral ;
• la figure 8 illustre un dispositif régulateur comportant un mobile rotatif équipé d'aimants à sa périphérie et dont le champ coopère périodiquement avec un aimant placé sur la courbe terminale externe d'un spiral ;
• la figure 9 illustre un mécanisme résonateur comportant un balancier comportant une virole maintenant un fil de torsion, dont un dispositif régulateur commande une variation périodique de la tension ;
• la figure 10 représente, sous forme d'un schéma-blocs, une montre comportant un mouvement mécanique avec un mécanisme résonateur régulé selon l'invention.

Other characteristics and advantages of the invention will appear on reading the detailed description which follows, with reference to the appended drawings, where:

• the figure 1 shows, schematically, a pendulum whose length is varied;
• the figure 2 shows schematically a tuning fork with two balance springs attached to each other
• the figure 3 represents, schematically, and partially, the hairspring of a balance-hairspring assembly, with an additional turn fixed to this hairspring and coming in lining locally with the external end curve of the hairspring, and a regulating device for effecting twists of direction opposite on the external terminal curve and on this additional turn;
• the figure 4 represents, similarly to the figure 3 , an additional turn and a regulating device actuating one end of this additional turn;
• the figure 5 represents a hairspring to which is fixed an arm, and a regulating device actuating one end of this arm;
• the figure 6 illustrates a hairspring with, in the vicinity of its external terminal curve, another turn which is held at a first end by a support maneuvered by a regulating device, and which is free at a second end arranged to come periodically into contact with the terminal curve external under the action of the regulating device on this support;
• the figure 7 illustrates a hairspring comprising two conductive strips separated by insulating elements, and the Figures 7A and 7B show, in section, two sections of this hairspring according to the electric fields applied to this hairspring;
• the figure 8 illustrates a regulating device comprising a rotary mobile equipped with magnets at its periphery and whose field cooperates periodically with a magnet placed on the outer terminal curve of a hairspring;
• the figure 9 illustrates a resonator mechanism comprising a balance comprising a ferrule holding a torsion wire, of which a regulating device controls a periodic variation of the voltage;
• the figure 10 represents, in the form of a block diagram, a watch comprising a mechanical movement with a regulated resonator mechanism according to the invention.

Detailed description of preferred embodiments

The object of the invention is to manufacture a time base to make a mechanical timepiece, in particular a mechanical watch, as precise as possible.

One way to do this is to combine different resonators, either directly or via the exhaust.

To overcome the instability factor linked to the escapement mechanism, a parametric resonator system makes it possible to reduce the influence of the escapement and thus make the watch more precise.

According to the invention, a parametric oscillator uses, for the maintenance of the oscillations, a parametric actuation which consists in varying one of the parameters of the oscillator with a regulation frequency ωR between 0.9 times and 1.1 times the value of a multiple integer of the natural frequency ω0 of the oscillator system to be regulated, this integer being greater than or equal to 2, and which is preferably an integer multiple, in particular double, of the natural frequency ω0.

By convention and in order to clearly distinguish them, here we call "regulator" 2 the oscillator which is used for the maintenance and frequency regulation of the other maintained system, which is called "the resonator" 1.

où T est l'énergie cinétique et V l'énergie potentielle et l'inertie I(t), la rigidité k(t) et la position de repos x ₀(t) dudit résonateur sont une fonction périodique du temps. x est la coordonnée généralisée du résonateur.
L'équation du résonateur paramétrique forcé et amorti est obtenue par l'équation de Lagrange pour la lagrangienne L en ajoutant un forçant f(t) et une force de Langevin prenant en compte les mécanismes dissipatifs : $$\frac{{\partial }^{2}x}{{\partial }^{2}t}+\gamma \left(t\right)\frac{\partial x}{\partial t}+{\omega }^2\left(t\right)\left[x-x_0\left(t\right)\right]=f\left(t\right)$$

où le coefficient de la dérivée du premier ordre en x est : $$\gamma \left(t\right)=\left[\beta \left(t\right)+\dot{I}\left(t\right)\right]/I\left(t\right),$$

β(t) > 0 étant le terme décrivant les pertes, et où le coefficient du terme d'ordre nul dépend de la fréquence du résonateur $\omega \left(t\right)=\sqrt{k\left(t\right)/I\left(t\right)}.$

La fonction f(t) prend la valeur 0 dans le cas d'un oscillateur non-forcé.
Cette fonction f(t) peut, encore, être une fonction périodique, ou encore être représentative d'une impulsion de type Dirac.The Lagrangian L of a parametric resonator of dimension 1 is: $$L=T-V=\frac{1}{2}I\left(t\right){\dot{x}}^2-\frac{1}{2}k\left(t\right){\left[x-x_0\left(\mathrm{<figure-callout\; id="2"\; label="t"\; filenames="imgf0001.png,imgf0002.png"\; state="\{\{state\}\}">t</figure-callout>}\right)\right]}^2$$

where T is the kinetic energy and V the potential energy and inertia I ( t ), the stiffness k ( t ) and the rest position x ₀ ( t ) of said resonator are a periodic function of time. x is the generalized coordinate of the resonator.
The equation of the forced and damped parametric resonator is obtained by the Lagrange equation for the Lagrangian L by adding a forcing f (t) and a Langevin force taking into account the dissipative mechanisms: $$\frac{{\partial }^{2}x}{{\partial }^{2}t}+\gamma \left(t\right)\frac{\partial x}{\partial t}+{\omega }^2\left(t\right)\left[x-x_0\left(t\right)\right]=f\left(t\right)$$

where the coefficient of the first order derivative in x is: $$\gamma \left(t\right)=\left[\beta \left(t\right)+\dot{I}\left(t\right)\right]/I\left(t\right),$$

β ( t )> 0 being the term describing the losses, and where the coefficient of the zero order term depends on the frequency of the resonator $\omega \left(t\right)=\sqrt{k\left(t\right)/I\left(t\right)}.$

The function f (t) takes the value 0 in the case of a non-forced oscillator.
This function f (t) can also be a periodic function, or even be representative of a Dirac type pulse.

The invention consists in varying, by the action of a maintenance oscillator or regulator, one or the other, or all, the terms β (t), w (t), by modifying at least the real part of the stiffness, with a regulation frequency wR which is between 0.9 times and 1.1 times the value of an integer multiple, this integer being greater than or equal to 2, in particular double, of the natural frequency ω0 of the oscillator system at regulate.

In a particular embodiment, the regulation frequency ωR is an integer multiple, in particular double, of the natural frequency ω0 of the resonator system to be regulated.

In a variant, the rest position x ₀ (t), varies simultaneously with the parameters β (t), ω (t), with a regulation frequency ωR which is between 0.9 times and 1.1 times the value of a multiple integer, this integer being greater than or equal to 2, in particular double, of the natural frequency ω0 of the oscillator system to be regulated.

Preferably, all the terms β (t), ω (t), x ₀ (t), vary with a regulation frequency wR which is preferably an integer multiple, in particular double, of the natural frequency ω0 of the resonator system to be regulated.

Generally, the maintenance oscillator or regulator, in addition to modulating the parametric terms, also introduces a non-parametric maintenance term f (t), the amplitude of which is negligible once the parametric regime is reached [ WB Case, The pumping of a swing from the standing position, Am. J. Phys. 64, 215 (1996 )].
Alternatively, the forcing term f (t) can be introduced by a second maintenance mechanism.

avec L la longueur du pendule, et g l'attraction de la pesanteur.The parameters of this equation are the frequency term ω and the loss and friction term β. The quality factor of the oscillator is defined by Q = ω / β.
To better understand the phenomenon, we can approach the example of a pendulum whose length is varied. In that case, $${\mathrm{<figure-callout\; id="2"\; label="\omega "\; filenames="imgf0001.png,imgf0002.png"\; state="\{\{state\}\}">\omega </figure-callout>}}^2=\frac{g}{L}$$

with L the length of the pendulum, and g the attraction of gravity.

In this particular example, if the length L is modulated in time periodically with a frequency 2w and a sufficient amplitude of modulation δL (δL / L> 2β / ω), the system oscillates at the frequency ω without damping. [ D. Rugar and P. Grutter, Mechanical parametric amplification and thermomechanical noise squeezing, PRL 67, 699 (1991 ), AH Nayfeh and DT Mook, Nonlinear Oscillations, Wiley-Interscience, (1977 )].

The principle can be taken up in a timepiece or a watch which includes a mechanical balance-spring with a balance spring, with one end of the balance spring fixed to a ferrule secured to the balance, and the other end fixed to a stud.

Parametric maintenance of such a balance-spring system can in particular be achieved by making this peg movable, periodically.

The oscillation can be maintained and the accuracy of the system is notoriously improved.

The choice of a frequency of an excitation oscillator to double the frequency of the system which one wants to stabilize in regularity of oscillation allows to perform the modulation on a full half-wave, and to obtain zero or negative damping.

The industrialization of such parametric oscillator systems is linked to two essential functions: energy supply and metering.

These two functions can be separated, as illustrated by the figure 2 , using a tuning fork with two balance springs attached to each other, where one oscillating at a frequency 2ω is linked to the exhaust, and the other oscillating at a frequency w is linked to the counting.

It is still possible to favor a modification of the losses by friction in the air, rather than making the frequency term oscillate, or even to modify the inertia of the balance wheel by an unbalance.

For maximum efficiency, maintenance is advantageously carried out with a whole multiple frequency, in particular double, of the frequency of the resonator maintained. Mechanical means of maintenance can take different forms.

A variant of the present invention consists in varying the rigidity of the hairspring.

Excitation at twice the frequency can be carried out with a square signal, or even with a pulse signal, it is not essential to have a sinusoidal excitation.

The maintenance regulator does not need to be very precise: its possible lack of precision results only in a loss of amplitude, but without variation of the frequency (except of course if this frequency is very variable, which is to be avoided). In fact, these two oscillators, maintenance regulator and maintained resonator, are not coupled, but one maintains the other, in one direction.

In a preferred embodiment, there is no coupling spring between these two oscillators.

It is easy to understand that the invention differs from coupled oscillators known elsewhere: in fact, in the implementation of the invention, one does not want reversibility of the transfer of energy between two oscillators, but rather, in the wherever possible, a one-way energy transfer from one oscillator to the other.

The invention relates more particularly to the frequency regulation of a timepiece resonator by action on the rigidity of an elastic return means.

Thus, the invention relates to a method for regulating the frequency of a clockwork resonator mechanism 1 around its natural frequency ω0. This method implements at least one regulating device 2 which prints a periodic movement to at least one component of the resonator mechanism 1 or to a tool influencing the position or the rigidity of such a component of the resonator mechanism 1.

And this periodic movement requires periodic modulation at least of the resonance frequency of the resonator mechanism 1, by acting at least on the rigidity of an elastic return means that this resonator mechanism 1 comprises, with a regulation frequency wR which is understood between 0.9 times and 1.1 times the value of an integer multiple of the natural frequency ω0, this integer being greater than or equal to 2 and less than or equal to 10.

In a particular implementation of the invention, the periodic movement imposes a periodic modulation of the resonance frequency of the resonator mechanism 1, by imposing both a modulation of the rigidity of the resonator mechanism 1 and an inertia modulation of the mechanism resonator 1.

In a similar embodiment of the invention, the periodic movement requires a periodic modulation of the resonance frequency of the resonator mechanism 1, by imposing a modulation of the section of an elastic return means, in particular but not limited to a spring, which comprises said resonator mechanism 1 and / or a modulation of the modulus of elasticity of an elastic return means that comprises the resonator mechanism 1, and / or a modulation of the shape of an elastic return means that includes the resonator mechanism 1.

In a particular application, this periodic movement can, again, impose a periodic modulation of the resonance frequency of the resonator mechanism 1, by imposing, again, a modulation of the active length of an elastic return means, in particular of a spring. , which includes this resonator mechanism 1.

In a particular implementation of the invention, the periodic movement requires a periodic modulation of the resonance frequency of the resonator mechanism 1 by imposing both a modulation of the rigidity of the resonator mechanism 1, and a modulation of the position of the point of the resonator mechanism 1.

In a particular application illustrated by the figures, at least one said regulating device 2 is implemented which imparts a periodic movement to at least one component of the resonator mechanism 1, or to a tool influencing the position of such a component of the resonator mechanism 1, and this periodic movement is printed on a resonator mechanism 1 comprising at least one elastic return means 40 comprising at least one hairspring 4 or a twist wire 46, or a flexible elastic guide, in particular with virtual pivot (such as butterfly guide, or RCC 4 necks, combination of flexible blades, or set of crossed blades, or similar, achievable in a single piece by technologies of micro-machinable materials, "MEMS", "LIGA" or similar), and at least one said regulating device 2 by controlling a periodic variation in the rigidity of the elastic return means 40 by modulating its section and / or its modulus of elasticity and / or its form e and / or the constraints at its fixing points.

By shape modulation is meant here a deformation, under the effect of an external stress, compared to the empty form of the elastic return means, and not the normal deformation in service that takes for example a spiral spring during its contraction and its elongation. It is for example a deformation induced by a contact, by an aerodynamic friction, a contactless force such as a force of magnetic or electrostatic origin, or other.

Naturally, the elastic return means 40 considered here is the means used to ensure the frequency of oscillation of the resonator mechanism 1.

The preferred application of the invention relates to watches, particularly for an application where the elastic return means 40 is constituted by a twist wire.

According to the invention, this method is applied to a resonator mechanism 1 comprising at least one elastic return means 40 comprising at least one hairspring 4 or a twist wire 46 or a flexible guide 46, and at least one such device is operated. regulator 2 by controlling a periodic variation of the real part and / or the imaginary part of the rigidity of this elastic return means 40, the real part of the rigidity defining the frequency of this resonator mechanism 1, and the imaginary part of the rigidity defining the quality factor of this resonator mechanism 1.

In the variants illustrated in figures 3 to 8 (where the pendulum is not shown so as not to clutter the figures), this method is applied to a balance-spring assembly 3, the hairspring 4 of which constitutes the elastic return means 40 and is held between a stud 5 at a first external end 6 and a ferrule 7 at a second internal end 8, and at least one such is acted regulating device 2 by controlling a periodic variation of the real part and / or the imaginary part of the stiffness of the hairspring 4.

In the variant of the figure 3 , the external terminal curve 17 of the hairspring 4 is locally doubled by an additional turn 18 fixed to this hairspring 4 at at least a first junction point 19, and twists in opposite directions are made periodically with the regulating device 2 external terminal curve 17 and on the additional turn 18, acting on the stud 5 for the external terminal curve 17, and on an end 18A opposite this first junction point 19 of the additional turn 18 for the additional turn 18. This double torsion has the advantage of allowing the modification of the stiffness of the balance spring, without modifying its position in its plane.

In the variant of the figure 4 , the external terminal curve 17 of the hairspring 4 is locally doubled by an additional turn 18 fixed to this hairspring 4 at at least a first junction point 19, and a movement is made periodically with the regulating device 2 a movement on an opposite end 18A at this first junction point 19 of the additional turn 18. This modifies the rigidity of the external terminal curve, and therefore that of the hairspring. It is also possible to use the regulating device 2 to move the stud 5 and the end 18A.

• ou bien on choisit une telle spire additionnelle 18 de souplesse équivalente à celle de la courbe terminale externe 17,
• ou bien on choisit une telle spire additionnelle 18 plus rigide que la courbe terminale externe 17.

One can choose to give a particular rigidity to this additional turn 18, and in particular:

• or else such an additional turn 18 of flexibility equivalent to that of the external terminal curve 17 is chosen,
• or else one chooses such an additional turn 18 which is more rigid than the external terminal curve 17.

In the variant of the figure 5 , an arm 20 is fixed to the external terminal curve 17 of the hairspring 4 at at least a second junction point 21, and a movement is made periodically with the regulating device 2 on an end 22 of the arm 20 opposite this second point junction 21. In a particular variant, the arm 20 is chosen which is more rigid than the external terminal curve 17.

In the variant of the figure 6 , we position, in the vicinity of the outer terminal curve 17 of the hairspring 4, another turn 23, which in the resting state of the resonator mechanism 1 is completely independent of the elastic return means 40, and at a distance from the latter, and which is held at a first end by a support 24 operated by the regulating device 2, and which is free at a second end 25 arranged for periodically come into contact with the external terminal curve 17 under the action of the regulating device 2 on this support 24. This other curve 23 turn thus comes closer, and possibly stick, periodically to the hairspring 4, to modify the rigidity of the return component .

In the variant of the figure 7 , the hairspring 4 is produced with at least two conductive strips 41, 42, separated by insulating elements 43 and such a regulating device 2 is used to periodically apply a field to the two strips 41, 42, so as to modify the difference E1 (( figure 7A ) or E2 ( figure 7B ) between these two blades 41,42, and thus to modify the total section and the rigidity of the hairspring 4. In a variant, a different field is periodically applied to them.

In particular, the two blades 41, 42 are subjected to a different electromagnetic and / or electrostatic and / or magnetostatic field by a movement imparted to a ferromagnetic or magnetized polar mass or electrostatically conductive or electrified (in particular magnets or electrets) nearby. immediate of each blade so as to give rise to an electric or magnetic or electrostatic or magnetostatic force between them, and to approach or distance them from each other. The rigidity of hairspring 4 is modified because its section varies. The movement is preferably printed mechanically on these polar masses.

In a variant, the two blades 41, 42 are subjected to an electric or electrostatic field so as to locally polarize the hairspring 4 and locally modify its rigidity 4.

In the variant of the figure 8 , such a regulating device 2 is used comprising a rotary mobile 28 equipped with magnets 29 at its periphery and whose field cooperates periodically with at least one magnet 45 placed on the hairspring 4 (one can imagine placing the magnet on the side of the ferrule), to periodically change the stiffness of the balance spring 4. The prestress of the balance spring and the radial position of the counting point are also changed periodically.

In another variant, a rotary mobile 28 inhomogeneously magnetized is used to periodically modify the stiffness of the hairspring 4 by the phenomenon of magnetostriction.

In an electrostatic variant, use is made of such a regulating device 2 comprising a similar rotary mobile 28, this time fitted with electrons at its periphery, and whose electric field cooperates periodically with at least one electret placed on the external terminal curve 17 of the hairspring 4, to periodically modify the stiffness of the hairspring 4, by the phenomenon of piezoelectricity.

In yet another variant, the rigidity is modulated through a variation in temperature.

In an advantageous implementation of this process, valid for all the variants exposed above, the regulation frequency ωR is twice the natural frequency wO.

In an advantageous implementation of the method, the relative amplitude of the modulation of the real part of the rigidity of the resonator mechanism 1 is greater than twice the inverse of the quality factor of the resonator mechanism 1.

The invention also relates to a clockwork movement 10, comprising at least one clockwork resonator mechanism 1 designed to oscillate at a natural frequency ω0, this clockwork resonator mechanism 1 comprising at least one elastic return means 40 comprising at least a hairspring 4 or a twist wire 46 or a flexible guide. According to the invention, this movement 10 comprises at least one regulating device 2 controlling a periodic variation in the rigidity of the elastic return means 40 with a regulating frequency wR, which is between 0.9 times and 1.1 times the value of an integer multiple of the natural frequency ω0 of the resonator 1, said integer being greater than or equal to 2 and less than or equal to 10.

In the variants illustrated in figures 3 to 8 , the clockwork resonator mechanism 1 comprises at least one balance-spring assembly 3, the spring 4 of which constitutes the elastic return means 40 and is held between a stud 5 at a first external end 6 and a ferrule 7 at a second internal end 8, and the regulating device 2 controls a periodic variation of the stiffness of the hairspring 4.

In the variant of the figure 3 , the movement 10 comprises an additional turn 18 fixed to this hairspring 4 at at least a first junction point 19, and coming into local lining with the external terminal curve 17 of the hairspring 4. And the regulating device 2 performs periodic twists opposite directions on the external terminal curve 17 and on the additional turn 18, by acting on the pin 5 for the external terminal curve 17, and on one end 18A of the additional turn 18 opposite this first junction point 19.

In the variant of the figure 4 , the movement 10 comprises an additional turn 18 fixed to this hairspring 4 at at least a first junction point 19 and coming into local lining with the external terminal curve 17 of the hairspring 4, and the regulating device 2 periodically performs a movement on one end 18A of the additional turn 18 opposite this first junction point 19.

The additional turn 18 is either of flexibility equivalent to that of the external terminal curve 17, or even more rigid than the external terminal curve 17.

In the variant of the figure 5 , the movement 10 comprises an arm 20 fixed to the external end curve 17 of the hairspring 4 at at least a second junction point 21, and the regulating device 2 periodically performs a movement on one end 22 of the arm 20 opposite this second junction point 21.

In a particular embodiment, the arm 20 is more rigid than the external terminal curve 17.

In the variant of the figure 6 , the movement 10 comprises, in the vicinity of the external terminal curve 17 of the hairspring 4, another turn 23 which is held at a first end by a support 24 operated by the regulating device 2, and which is free at a second end 25 arranged to periodically come into contact with the external terminal curve 17 under the action of the regulating device 2 on this support 24.

In the variant of the figure 7 , the hairspring 4 comprises at least two conductive blades 41, 42, separated by insulating elements 43, and the regulating device 2 is arranged to periodically subject the two blades 41, 42, to an electric and / or magnetic field (in the broad sense , according to the definition of fields above), so as to modify the difference E1, E2, between the two blades 41, 42, and thus to modify the total section and the rigidity of the hairspring 4. In particular, the regulator 2 is arranged to periodically subject the two blades 41, 42 to a different electric field.

In the variant of the figure 8 , the regulating device 2 comprises a rotary mobile 28 equipped with magnets 29 at its periphery and whose magnetic field cooperates periodically with at least one magnet 45 placed on the external terminal curve 17 of the hairspring 4, to periodically modify the stiffness of the hairspring 4 .

In the variant of the figure 9 , the resonator mechanism 1 comprises at least one balance 26 comprising a ferrule 7 holding a torsion wire 46 which constitutes the elastic return means 40, and the regulating device 2 controls a periodic variation of the tension of the torsion wire 46.

In yet another variant, electrostatic layers or elements can be used to vary the rigidity of a spring or hairspring by partially or completely covering it with a piezoelectric layer activated by a small electronic module.

Preferably, the regulation frequency ωR of the regulating device 2 is twice the natural frequency ω0 of the resonator mechanism 1.

The invention also relates to a timepiece, more particularly a watch, 30 comprising at least one such timepiece movement 10.

Claims (8)

1. A method of maintaining and regulating the frequency of a timepiece resonator mechanism (1) about the natural frequency (ω0) thereof, the mechanism including at least one elastic return means (40) that includes at least one balance spring (4) or torsion wire (46) or flexible guide member, where at least one regulator device (2) is implemented, acting on said resonator mechanism (1) with a periodic motion, said periodic motion imposing a periodic modulation of the resonant frequency of said resonator mechanism (1), which is a parametric resonator, with a regulation frequency (ωR) that is comprised between 0.9 times and 1.1 times the value of an integer multiple of said natural frequency (ω0), said integer being greater than or equal to 2 and less than or equal to 10, characterized in that said at least one regulator device (2) is made to act by controlling a periodic variation in the real part of the rigidity of at least one said elastic return means (40), said real part of the rigidity defining the frequency of said resonator mechanism (1).
2. The method according to claim 1, characterized in that said periodic motion imposes a periodic modulation of the resonant frequency of said resonator mechanism (1), by imposing a modulation of the modulus of elasticity of at least one said elastic return means (40).
3. The method according to claim 1, characterized in that said periodic motion imposes a periodic modulation of the resonant frequency of said resonator mechanism (1), by imposing a modulation of the shape of at least one said elastic return means (40).
4. The method according to one of claims 1 to 3, characterized in that said method is applied to a said resonator mechanism (1), an elastic return means (40) whereof includes at least one torsion wire (46), and in that at least one said regulator device (2) is made to act by controlling a periodic variation of the rigidity of said elastic return means (40) by periodically modulating the tension of said torsion wire (46).
5. The method according to one of claims 1 to 3, characterized in that said method is applied to a said resonator mechanism (1), an elastic return means (40) whereof includes at least one balance spring (4), said balance spring (4) includes at least two conductive strips (41; 42), at least one whereof constitutes said component, and which are separated by isolating elements (43), and in that said regulator device (2) is arranged to periodically apply an electrical and/or magnetic field to said two strips (41; 42) so as to modify the distance (E1; E2) between the two said strips (41; 42).
6. The method according to one of claims 1 to 3, characterized in that said periodic motion imposes a periodic modulation of the resonant frequency of said resonator mechanism (1) by imposing both a modulation of the rigidity of an elastic return means comprised in said resonator mechanism (1) and a modulation of the inertia of said resonator mechanism (1).
7. A timepiece movement (10) including at least one timepiece resonator mechanism (1) devised to oscillate at a natural frequency (ω0), said timepiece resonator mechanism (1) including at least one sprung balance assembly (3), the balance spring (4) whereof forms the elastic return means (40) and is held between a balance spring stud (5) at a first outer end (6) and on a collet (7) at a second inner end (8), characterized in that said movement (10) comprises at least one regulator device (2) arranged to implement the method according to one of claims 1 to 6, and arranged to act on said resonator mechanism (1) with a periodic motion imposing a periodic modulation of the resonant frequency of said resonator mechanism (1), which is a parametric resonator, said at least one regulator device (2) being arranged to control a periodic variation in the real part of the rigidity of said elastic return means (40) with a regulation frequency (ωR) that is comprised between 0.9 times and 1.1 times the value of an integer multiple of said natural frequency (ω0) of said resonator (1), said integer being greater than or equal to 2 and less than or equal to 10, characterized in that said regulator device (2) is arranged to impart a periodic motion to at least one component of said resonator mechanism (1) to exert on said component a twisting or traction or compression force, and/or to impart a periodic motion to at least one tool affecting the position of such a component of said resonator mechanism (1), and in that:

   - either said resonator mechanism (1) comprises an additional coil (18), forming said component, and fixed to said balance spring (4) at at least a first attachment point (19) and locally lining the outer terminal curve (17) of said balance spring (4), said regulator device (2) being arranged so as to periodically create twists in opposite directions on said outer terminal curve (17) and on said additional coil (18), by acting on said balance spring stud (5) for said outer terminal curve (17), and on one end (18A) of said additional coil (18) opposite said first attachment point (19), or so as to periodically perform a motion on an end (18A) of said additional coil (18) opposite said first attachment point (19);

   - or said resonator mechanism (1) includes an arm (20), forming said component, and which is fixed to the outer terminal curve (17) of said balance spring (4) at at least a second attachment point (21), and said regulator device (2) is arranged so as to periodically perform a motion on an end (22) of said arm (20) opposite said second attachment point (21);

   - or said resonator mechanism (1) includes, in proximity to the outer terminal curve (17) of said balance spring (4), another coil (23) which forms said component, and which is held at a first end by a support (24) operated by said regulator device (2), and which is free at a second end (25) arranged to periodically come into contact with said outer terminal curve (17) under the action of said regulator device (2) on said support (24);

   - or said resonator mechanism (1) includes a rotating wheel set (28) provided with magnets (29) at the periphery thereof and whose field periodically cooperates with at least one magnet (45) forming said component, and which is placed on the outer terminal curve (17) of said balance spring (4), to periodically modify the rigidity of said balance spring (4).
8. A timepiece (30) including at least one timepiece movement (10) according to claim 7, characterized in that the timepiece is a watch.

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