EP4202565A1 - Use of frequency of a timepiece oscillator by opto-mechanical deformations - Google Patents

Abstract

One aspect of the invention relates to a method for fine adjustment of the rate of a mechanical oscillator (100) with oscillating inertial mass (1), which is fitted, in the first step (801), with an actuator ( 35) in material capable of irreversible local micro-expansion under the action of laser shots, to give a counterweight (3) a radial stroke during appropriate laser shots on a writing area (39; 391; 392) of said actuator (35), in the second step (802) the initial rate of said oscillator (100) is adjusted and measured, in the third step (803) the direction and the value of the difference necessary to reach a predetermined rate range are calculated, and from the stroke to be printed to the weights (3), in the fourth step (804) a writing area (39; 391; 392) is subjected to femtosecond laser shots to create expansion lines (390) by molecular dilation local to radially deform the actuator (35), in the fifth step (805) the rate is measured and the third step (803) and fourth step (804) are repeated if necessary.

Description

Technical field of the invention

The invention relates to a method for fine adjustment of the rate of a mechanical clock oscillator comprising at least one inertial mass arranged to oscillate around an axis of rotation and returned to a rest position by elastic return means. .

The invention also relates to a mechanical clock oscillator suitable for implementing this method.

The invention also relates to a timepiece, in particular a watch, comprising such a mechanical clock oscillator.

The invention relates to the field of adjusting the rate of a mechanical watch oscillator, and in particular of an oscillator already fitted into a watch head.

Technology background

The modification of the frequency of a mechanical oscillator almost always passes by a change of the rigidity of the elastic part, in particular a spring, or by a change of its inertia / of its mass. For example, in the balance-springs of mechanical watches, there are currently devices for adjusting the stiffness of the balance-spring, such as the variation of its active length by moving pins. Another commonly used method is the modification of the inertia of the balance by moving small masses towards the outside or the inside of the balance, such as screws, or eccentric rotating weights.

However, these operations require opening the watch and taking out the movement, which tends to falsify the result once the case is closed, with a drift sometimes of up to 10 seconds per day, which is unfortunate for movements that must be regulated from 0 to +2 seconds per day. Moreover, these delicate mechanisms are generally dependent on mechanical games which are all sources of drift, once the adjustment tool - and the force used for adjustment - are removed.

Summary of the invention

The invention proposes to precisely adjust the frequency of a mechanical clock oscillator, for example a watch balance-spring, without having to disassemble the watch, or more generally the timepiece carrying this oscillator.

To this end, the invention relates to a method for fine adjustment of the rate of a mechanical clock oscillator, according to claim 1.

The invention also relates to a mechanical clock oscillator suitable for implementing this method.

The invention also relates to a timepiece, in particular a watch, comprising such a mechanical clock oscillator.

Brief description of figures

• la figure 1 représente, de façon schématisée et en vue en plan, une montre, avec une tête de montre comportant un élément transparent transmissif qui sépare l'extérieur de la montre et l'intérieur de la montre. Cet élément transparent transmissif, ici représenté sous la forme d'un fond, permet un accès optique à l'utilisateur et à une source optique vers tout ou partie de l'oscillateur de la montre, qui est ici un balancier-spiral dont seul est représenté le balancier, le spiral n'étant pas représenté pour ne pas surcharger les figures. Cette figure 1 représente, en trait interrompu, un rayon laser incident et rencontrant ce balancier;
• la figure 2 représente, de façon schématisée et en vue en plan comme la figure 1, le détail du balancier selon l'invention. Ce balancier comporte, depuis sa serge vers l'élément transparent transmissif, une pluralité de supports disposés par paires symétriques par rapport à l'axe de rotation du balancier. Ces supports supportent, du côté de l'élément transparent transmissif, chacune au moins une masselotte qui est mobile radialement par rapport à l'axe de rotation du balancier. La figure montre, pour chaque support, trois positions différentes d'une telle masselotte, l'une médiane en hachures intermédiaire entre deux positions extrêmes en trait interrompu;
• la figure 3 représente le balancier de la figure 2, en coupe perpendiculaire à l'élément transparent transmissif, lequel sépare, d'une part en partie supérieure de la figure le milieu extérieur dans lequel est positionnée au moins une source laser, et d'autre part en partie inférieure de la figure l'intérieur de la tête de montre qui comporte le balancier. La figure montre la serge portant un support supportant, du côté de l'élément transparent transmissif une telle masselotte qui est mobile radialement par rapport à l'axe de rotation du balancier, sous l'action d'un faisceau émis par la source laser. La figure est centrée sur une masselotte représentée en hachures, et montre une autre position radiale de cette masselotte, représentée en trait interrompu;
• la figure 4 est un graphe qui indique en ordonnée l'écart de marche en secondes par jour, et en abscisse la valeur du déplacement radial symétrique de deux masselottes, en micromètres, et superpose les résultats obtenus pour quatre valeurs de masse de masselotte, de 1,20 mg à 2,40 mg;

• la figure 5 représente, de façon schématisée, et en vue en plan, le principe de la mise en œuvre d'un actionneur opto-mécanique pour faire mouvoir une masselotte: le support porte des fixations, dont l'une porte l'actionneur opto-mécanique proprement dit, qui comporte deux bras parallèles, formant un U car reliés en bout par un segment commun, le premier bras s'étendant entre une fixation au support et le segment commun, et le deuxième bras s'étendant entre le segment commun et un point de sortie, ici constitué par un col d'un mécanisme amplificateur destiné à amplifier la course de sortie de l'actionneur opto-mécanique pour procurer une course suffisante à la masselotte;
• la figure 6 représente, de façon schématisée, et en vue en plan, une autre variante de l'actionneur opto-mécanique de la figure 5, dont la course de sortie selon une direction linéaire est amplifiée par un amplificateur mécanique, ici un mécanisme de type parallélogramme à quatre cols, qui permet de transformer l'allongement global, ou la rétraction globale, mesurable au point de sortie du deuxième bras, en une course de la masselotte qui soit suffisante pour influencer notablement la marche de l'oscillateur;
• la figure 7 illustre schématiquement le cas où les impulsions attaquent la zone d'écriture du deuxième bras, en haut sur la figure, le mouvement global du point de sortie est alors vers la gauche de la figure, dans un mouvement de poussée de la masselotte;
• la figure 8 illustre le cas opposé à celui de la figure 7, où les impulsions attaquent la zone d'écriture du premier bras, en bas sur la figure, le mouvement global du point de sortie est alors vers la droite de la figure, dans un mouvement de rétraction de la masselotte;
• la figure 9 représente, de façon similaire aux figures 5 à 8, une variante où une masselotte et le support correspondant forment un ensemble monobloc constitué par un chip, sur un niveau unique, le support est alors limité à une zone de fixation pour la fixation sur le balancier; cette variante convient en particulier à l'application de l'invention au cas particulier d'un balancier d'un diamètre de 10,6 mm, porteur de chips de 2 x 2 mm intégrant support et masselotte;
• la figure 10 représente, de façon similaire à la figure 3, une vue en plan du balancier équipé de deux chips selon la figure 9;
• la figure 11 est une vue schématisée, en coupe passant par l'axe de rotation du balancier, et montrant la serge de ce balancier, portant un support, la masselotte n'étant pas représentée, et la source laser d'écriture émettrice pour l'écriture sur les zones d'écriture, ainsi que, monté obliquement en partie gauche de la figure, un laser de détection, dont le rayon réfléchi par le balancier et les éléments qu'il comporte est recueilli en partie droite de la figure par un moyen de recueil tel qu'un photo-détecteur;
• la figure 12 représente, de façon schématisée et en plan, un détail de l'agencement selon la figure 11 avec une source d'écriture laser et une source de détection laser, pour le cas où le balancier oscille, et où le tir laser est synchronisé avec sa position angulaire; la figure représente une partie de la serge du balancier, portant un chip selon la figure 9; l'arc représenté en trait interrompu correspond à la position instantanée de la source d'écriture laser, qui tire perpendiculairement au plan de la figure, et qui peut ainsi écrire dans la zone d'écriture du premier bras inférieur dans le cas d'espèce, pour créer une dilatation moléculaire symbolisée par une petite flèche dans cette zone d'écriture, les petites flèches voisines correspondant à des écritures déjà effectuées dans la même zone avec des positionnements différents en x de la source d'écriture, correspondant à des rayons différents par rapport à l'axe de rotation du balancier; en partie inférieure de la figure est visible depuis la gauche vers la droite une source de détection laser, une lentille convergente, le rayonnement incident vers le balancier, le point de réflexion sur le balancier ou sur les organes qu'il porte, le rayonnement réfléchi, une lentille convergente, et le photo-détecteur;
• la figure 13 juxtapose trois graphes temporels, établis avec en abcisses des échelles de temps différentes, mais qui sont agencés l'un par rapport à l'autre pour mettre en évidence des instants particuliers et les phénomènes qui s'y produisent : le graphe supérieur affiche en ordonnée la vitesse angulaire oméga OME du balancier, le graphe médian affiche en ordonnée la valeur du signal VPD du photo-détecteur, et le graphe inférieur affiche en ordonnée l'intensité optique IIE émise par la source laser d'écriture;
• la figure 14 est un schéma-blocs montrant les liens entre des moyens de pilotage, une table à mouvements croisés pour la manœuvre du laser d'écriture, ce dernier, un laser de détection, le moyen de recueil du rayonnement réfléchi, et des moyens de mise en mouvement ou d'arrêt de l'oscillateur;
• la figure 15 est un schéma-blocs regroupant les cinq étapes principales du procédé d'ajustement de marche selon l'invention.

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

• there figure 1 shows, schematically and in plan view, a watch, with a watch head comprising a transparent transmissive element which separates the outside of the watch and the inside of the watch. This transparent transmissive element, here represented in the form of a bottom, allows optical access to the user and to an optical source towards all or part of the oscillator of the watch, which is here a balance-spring which alone is represented the balance wheel, the hairspring not being represented for do not overload the figures. This figure 1 represents, in broken line, an incident laser beam and meeting this pendulum;
• there figure 2 represents, schematically and in plan view as the figure 1 , the detail of the balance according to the invention. This balance comprises, from its rim towards the transparent transmissive element, a plurality of supports arranged in pairs symmetrical with respect to the axis of rotation of the balance. These supports support, on the side of the transparent transmissive element, each at least one flyweight which is radially movable with respect to the axis of rotation of the balance. The figure shows, for each support, three different positions of such a flyweight, one middle hatched intermediate between two extreme positions in broken lines;
• there picture 3 represents the pendulum of the picture 2 , in section perpendicular to the transparent transmissive element, which separates, on the one hand in the upper part of the figure the external environment in which at least one laser source is positioned, and on the other hand in the lower part of the figure the interior of the watch head which contains the balance wheel. The figure shows the rim carrying a support supporting, on the side of the transparent transmissive element, such a counterweight which is radially movable with respect to the axis of rotation of the balance, under the action of a beam emitted by the laser source. The figure is centered on a weight shown in hatching, and shows another radial position of this weight, shown in dashed lines;
• there figure 4 is a graph which indicates on the ordinate the rate difference in seconds per day, and on the abscissa the value of the symmetrical radial displacement of two flyweights, in micrometers, and superimposes the results obtained for four mass values of feeder, from 1.20 mg to 2.40 mg;

• there figure 5 represents, in a schematic way, and in plan view, the principle of the implementation of an opto-mechanical actuator to move a flyweight: the support carries fasteners, one of which carries the opto-mechanical actuator itself said, which comprises two parallel arms, forming a U because connected at the end by a common segment, the first arm extending between a fixing to the support and the common segment, and the second arm extending between the common segment and a point output, here consisting of a neck of an amplifying mechanism intended to amplify the output travel of the opto-mechanical actuator to provide sufficient travel for the flyweight;
• there figure 6 represents, schematically, and in plan view, another variant of the opto-mechanical actuator of the figure 5 , whose output stroke in a linear direction is amplified by a mechanical amplifier, here a parallelogram-type mechanism with four necks, which makes it possible to transform the overall elongation, or the overall retraction, measurable at the exit point of the second arm, in a travel of the flyweight which is sufficient to notably influence the course of the oscillator;
• there figure 7 schematically illustrates the case where the pulses attack the writing area of the second arm, at the top in the figure, the overall movement of the exit point is then towards the left of the figure, in a pushing movement of the weight;
• there figure 8 illustrates the opposite case to that of figure 7 , where the impulses attack the writing area of the first arm, at the bottom in the figure, the overall movement of the exit point is then towards the right of the figure, in a movement of retraction of the flyweight;
• there figure 9 represents, similarly to figures 5 to 8 , a variant where a flyweight and the corresponding support form a one-piece assembly consisting of a chip, on a single level, the support is then limited to an attachment zone for attachment to the balance wheel; this variant is particularly suitable for the application of the invention to the particular case of a balance wheel with a diameter of 10.6 mm, carrying chips of 2 x 2 mm integrating support and flyweight;
• there figure 10 represents, similarly to the picture 3 , a plan view of the balance equipped with two chips according to the figure 9 ;
• there figure 11 is a diagrammatic view, in section passing through the axis of rotation of the balance wheel, and showing the rim of this balance wheel, carrying a support, the flyweight not being shown, and the transmitting laser writing source for writing on the writing areas, as well as, mounted obliquely in the left part of the figure, a detection laser, the ray of which reflected by the pendulum and the elements it comprises is collected in the right part of the figure by a collection means such as a photo-detector;
• there figure 12 represents, schematically and in plan, a detail of the layout according to the figure 11 with a laser writing source and a laser detection source, for the case where the pendulum oscillates, and where the laser firing is synchronized with its angular position; the figure represents part of the balance rim, carrying a chip according to the figure 9 ; the arc shown in dashed lines corresponds to the instantaneous position of the laser writing source, which shoots perpendicular to the plane of the figure, and which can thus write in the writing zone of the first lower arm in the present case, to create a molecular dilation symbolized by a small arrow in this writing zone, the small neighboring arrows corresponding to writings already carried out in the same zone with different positions in x of the writing source, corresponding to different radii with respect to the axis of rotation of the balance wheel; in the lower part of the figure is visible from left to right a laser detection source, a converging lens, the incident radiation towards the balance, the point of reflection on the balance or on the organs it carries, the reflected radiation , a converging lens, and the photo-detector;
• there figure 13 juxtaposes three time graphs, established with different time scales on the abscissa, but which are arranged relative to each other to highlight particular instants and the phenomena that occur there: the upper graph displays on the ordinate the angular velocity omega OME of the pendulum, the middle graph displays on the ordinate the value of the signal VPD from the photo-detector, and the lower graph displays on the ordinate the optical intensity IIE emitted by the writing laser source;
• there figure 14 is a block diagram showing the links between control means, a cross-movement table for operating the writing laser, the latter, a detection laser, the means for collecting the reflected radiation, and means for movement or stoppage of the oscillator;
• there figure 15 is a block diagram grouping together the five main steps of the rate adjustment method according to the invention.

Detailed description of the invention

The invention proposes to induce permanent mechanical tensions, and therefore a volume expansion, in particular by femtosecond laser excitation, in a flexible micro-mechanism machined in a support made of glass (fused silica) or the like.

The support is embedded on the inertial mass of the oscillator, in particular the balance wheel, of a mechanical watch. The displacement of part of the mechanism will modify the inertia of this inertial mass, therefore the frequency of the oscillator, in particular of the balance-spring. Displacements of the order of several micrometers can be obtained in such glass microstructures by writing lines of expansion of parallel internal tensions, as can be read in particular in the article “Non-contact sub-nanometer optical repositioning using femtosecond lasers”, by Y. Bellouard, in “Optic Express, 2 November 2015, volume 23, N° 22” .

The microstructures themselves are produced using a cutting process precise to +/-1 micrometer, and using the same type of laser, followed by chemical attack, as read in the aforementioned article, or in the article “Fabrication of high-aspect ratio, micro-fluidic channels and tunnels using femtosecond laser pulses and chemical etching”, by Y. Bellouard et al., in “Optics Express, 2004, 12, pages 2120-2129 », or on the website of FEMTOprint SA, 6933 Muzzano (CH), on the page https://www.femtoprint.ch/devices-photos.

The absence of pivots or any other rubbing guidance guarantees high positioning accuracy and zero hysteresis. The optical excitation is direct through a glass or any non-absorbent interlocking separation for the wavelength of the laser, or even defocused at the point of passage.

The invention is illustrated more particularly, and not limitatively, for the case where the oscillator is a watch oscillator, and is a balance-spring.

The invention relates to a method for fine adjustment of the rate of a mechanical clock oscillator 100, comprising at least one inertial mass 1 arranged to oscillate around an axis of rotation D and returned to a rest position by elastic return means.

According to the invention, and as visible on the figure 15 , in a first step 801, the oscillator 100 is equipped with at least one inertial mass 1 comprising an actuator 35 in a material capable of irreversible local micro-expansion under the action of laser shots. This actuator 35 is arranged to give a flyweight 3 a radial linear stroke with respect to the axis of rotation D, directly or via at least one stroke amplifier 36, when a writing zone 39, or more particularly a first writing zone 391 on a first arm 33, or a second writing zone 392 on a second arm 34, which the actuator 35 comprises is subjected to appropriate laser shots. It will be seen later that each writing area 39, 391, 392 is capable of receiving expansion lines 390 by laser writing.

The designation "writing area 39" relates to the generic case, and the designations "first writing area 391" and "second writing area 392" relate to the preferred, but not limiting, application on respectively a first arm 33 , and a second arm 34 of the flyweight 3.

More particularly, when an inertial mass 1, subjected to a rotational movement, extends on either side of the axis of rotation D, this inertial mass 1 is equipped with at least one pair of diametrically opposed actuators 35 , in a material capable of irreversible local micro-expansion under the action of laser shots. This is particularly the case when an inertial mass 1 is a balance wheel of a balance-spring type oscillator.

More particularly, when an inertial mass 1 is cantilevered with respect to the axis of rotation D, like the inertial masses suspended by flexible blades, which are symmetrical with respect to a plane passing through the axis of rotation D, this inertial mass 1 is equipped with at least one pair of actuators 35 symmetrical with respect to this plane of symmetry.

More particularly, this method is applied to an oscillator 100 with at least two inertial masses 1 each comprising such an actuator 35.

In a second step 802, a first adjustment, in particular coarse, of the initial rate of the oscillator 100 is carried out in a first rate range and the rate is measured.

In a third step 803, the direction and the value of the running deviation to be printed on the oscillator 100 are calculated to bring it into a second predetermined running range, and the direction and the value of the stroke are calculated. print to each flyweight 3 that comprises the oscillator 100.

In a fourth step 804, at least one writing area 39, 391, 392 is subjected to femtosecond laser shots to create at least one line of expansion 390 by local molecular expansion of the material to deform the actuator 35 radially by relative to the axis of rotation D.

In a fifth step 805, the rate of the oscillator 100 is measured, and the third step 803 and the fourth step 804 are repeated if necessary until the rate of the oscillator 100 is in the second predetermined operating range .

More particularly, during the fourth step 804, a femtosecond laser source 700 is used, mounted on a table with crossed movements 710, or with radial travel, so as to increment different series of shots on different radii with respect to the axis of rotation D, to create a series of expansion lines 390 in close proximity to each other.

More particularly, during the fourth step 804, a femtosecond laser source 700 is used to fire in each direction of rotation of the inertial mass 1.

More particularly, during the fourth step 804, control means 790 are used to control the firings of the femtosecond laser source 700, according to the information on the presence or absence of material provided by the combination of a detection laser 750 and a collection means 760 or a photo-detector.

More particularly, during the first step 801, an actuator 35 is chosen comprising, on a first arm 33 a first writing zone 391, and on a second arm 34 parallel to the first arm 33 in a radial linear direction L and joining it at a common segment 334 a second writing area 392. The actuator 35 is thus mounted in an "S" between, on the one hand an attachment area 30 fixed to a support 2 mounted on the inertial mass 1 or directly fixed on the inertial mass 1, and on the other hand an exit point or a connection neck 32 for connection with an amplifier mechanism 36. The actuator 35 is arranged to act in two opposite directions along the linear direction L, according to that, during the fourth step 804, the writing by femtosecond laser shots takes place in the first writing zone 391 on the first arm 33 for advance adjustment, or in the second writing zone 392 on the second arm 34 for delay adjustment.

More particularly, during the first step 801, an actuator 35 is chosen with an exit point or a connection neck 32 for connection with an amplifier mechanism 36 which is arranged to amplify the output stroke of the actuator 35, to print an amplified stroke on the flyweight 3.

More particularly, this amplifier 36 is of the parallelogram type, and comprises a linkage system with connecting rods 310 arranged between flexible necks 31 forming a linear guide in a radial linear direction L.

More particularly, during the first step 801, an actuator 35 is chosen comprising an attachment zone 30 integral with a support 2 mounted on the inertial mass 1. And the support 2 forms a one-piece assembly constituting a flexible micro-mechanism, with the actuator 35, an amplifier 36 and the flyweight 3 connected in series with each other.

More particularly, during the first step 801, an actuator 35 comprising an attachment zone 30 fixed to a support 2 mounted on the inertial mass 1 or secured to a support 2 is chosen, and the actuator 35 and/or the support 2 is glass.

More particularly, during the first step 801, the inertial mass 1 is chosen in the form of a balance wheel, which comprises at least one pair of flyweights 3 which are identical and diametrically opposed with respect to the axis of rotation D.

More particularly, during the first step 801, the oscillator 100 is integrated into a watch head 500 of a watch 1000, which watch head 500 comprises at least one transparent transmissive element 600, which separates the outside and the inside the watch 1000, and allows optical access to at least one laser to at least the inertial mass 1 of the oscillator 100 of the watch.

In a static variant, during the first step 801, the oscillator 100 is equipped with stop means or a stop-seconds arranged to rest on an inertial mass 1, and the fourth step 804 is carried out in a position blocked from the inertial mass 1.

In a dynamic variant, during the fourth step 804 the femtosecond writing laser shots are performed during the oscillation of the inertial mass 1, the angular position and the shots of which are synchronized.

More particularly, during the fourth step 804, the firings are carried out with a femtosecond laser, for example and not limited to a wavelength between 900 and 1100 nm, a pulse duration between 200 and 350 fs, an energy of a pulse approximately between 200 and 300 nJ, with a repetition rate of 700 to 900 kHz. It is quite obvious that a different femtosecond laser (wavelength, pulse duration and energy) can be used, provided that it can modify matter in the same way described before.

The invention also relates to a mechanical clock oscillator 100 comprising at least one inertial mass 1 arranged to oscillate around an axis of rotation D and returned to a rest position by elastic return means, suitable for the implementation of this process. According to the invention, at least one inertial mass 1 comprises an actuator 35 in a material capable of irreversible local micro-expansion under the action of laser shots. The actuator 35 is arranged to impart to a counterweight 3 a radial linear stroke with respect to the axis of rotation D, directly or via at least one stroke amplifier 36, when a writing zone 39 , 391, 392, which comprises the actuator 35 is subjected to appropriate laser shots.

More particularly, the actuator 35 comprises, on a first arm 33 a first writing area 391, and on a second arm 34 parallel to the first arm 33 in a radial linear direction L and joining it at a common segment 334 a second writing zone 392, the actuator 35 thus being mounted in an "S" between on the one hand a fixing zone 30 fixed to a support 2 mounted on the inertial mass 1 or directly fixed on the inertial mass 1, and on the other hand, an exit point or a connection neck 32 for connection with an amplifier mechanism 36, the actuator 35 being arranged to act in two opposite directions along the linear direction L, depending on whether femtosecond laser shots are applied in the first writing area 391 on the first arm 33 for advance adjustment, or in the second write area 392 on second arm 34 for delay adjustment.

More particularly, the actuator 35 comprises an exit point or a connection neck 32 for connection with an amplifier mechanism 36 arranged to amplify the output stroke of the actuator 35, to impart an amplified stroke to the flyweight 3. And the amplifier 36 is of the parallelogram type, and comprises a linkage system with connecting rods 310 arranged between flexible necks 31 forming a linear guide in a radial linear direction L.

More particularly, the actuator 35 comprises an attachment zone 30 secured to a support 2 mounted on the inertial mass 1, and the support 2 forms a one-piece assembly constituting a flexible micro-mechanism, with the actuator 35, an amplifier 36 and the flyweight 3 mounted in series with each other.

More particularly, the actuator 35 comprises an attachment zone 30 fixed to a support 2 mounted on the inertial mass 1 or secured to a support 2, and the actuator 35 and/or the support 2 is made of glass.

More particularly, the inertial mass 1 is a pendulum, which comprises at least one pair of identical and diametrically opposed weights 3 with respect to the axis of rotation D.

The invention also relates to a timepiece, in particular a watch 1000, comprising at least one such mechanical oscillator 100. According to the invention, the watch 1000 comprises a watch head 500 comprising at least one transparent transmissive element 600, which separates the exterior and the interior of the watch 1000, and allows optical access to at least one laser towards at least the inertial mass 1 of the oscillator 100 of the watch.

The figures illustrate non-limiting embodiments of the invention, in the particular case where the inertial mass 1 is a pendulum.

There figure 1 represents a timepiece 1000, in particular a watch, with a watch head 500, comprising a transparent transmissive element 600, such as a bottom, a crystal, or the like, which separates the outside of the watch and the inside of the watch. This transparent transmissive element 600 allows optical access to the user and to an optical source to all or part of the oscillator 100 of the watch, and, in the case in point, at least the balance wheel 1, the hairspring n' not being shown so as not to overload the figures. This figure 1 represents, in broken lines, an incident laser beam RL and meeting the balance 1.

The invention proposes to adjust precisely, and through a casing that is at least locally transparent or of low optical absorption such as this transparent transmissive element 600, the frequency of a balance-spring by means of a laser beam focused. Oscillator 100 is either already roughly adjusted to +/- 15 seconds per day, for example using screws not shown, or precisely paired with a suitable hairspring in this range. The action of the laser allows fine adjustment towards 0-2 seconds per day, by moving small weights towards the outside or the inside of the balance wheel 1, thus modifying its inertia, and therefore modifying the frequency of the oscillator , and thus allowing precise adjustment of the rate of the watch.

There figure 2 shown, in plan view as the figure 1 , the detail of the balance wheel 1 according to the invention. This balance 1 comprises, from its rim 19 towards the transparent transmissive element 600, a plurality of supports 2 arranged in pairs symmetrical with respect to the axis of rotation D of the balance. These supports 2, in particular chips, support, on the side of the transparent transmissive element 600, each at least one flyweight 3 which is radially movable with respect to the axis of rotation D of the balance 1. The picture 2 shows, for each support 2, three different positions of such a flyweight 3, one midline in hatching intermediate between two extreme positions in dashed lines, at a radial distance X from the position intermediate. This limited number of radial positions of the flyweights 3 is only a particular case to leave the figure legible.

The figures illustrate particular variants where each support 2 is attached to the balance 1, for convenience of execution; another variant where the supports 2 and the pendulum 1 form a one-piece assembly is possible, although more expensive to produce.

There picture 3 is a section perpendicular to the transparent transmissive element 600, which separates, on the one hand in the upper part of the figure the external environment in which at least one laser source 700 is positioned, and on the other hand in the lower part of the figure inside the watch head which comprises the balance wheel 1. This balance wheel 1 comprises, from its rim 19 towards the transparent transmissive element 600, a plurality of supports 2 arranged in symmetrical pairs with respect to the axis of rotation D of the pendulum. These supports 2 support, on the side of the transparent transmissive element 600, each at least one flyweight 3 which is radially movable with respect to the axis of rotation D of the balance 1, under the action of a beam emitted by the source laser 700. The picture 3 is centered on a flyweight 3 shown in hatching, and shows another radial position of this flyweight 3, shown in dashed lines. The flyweights 3 are thus secured to a support 2, itself fixed to the rim 19 towards the outside of the rocker arm 1 as illustrated.

The displacement amplitude depends on several parameters of the laser exposure. This amplitude can be controlled very precisely, and the weights 3 remain in place after an exposure, and it is possible to move the weights 3 in both directions over a fixed number of cycles. In order not to disturb the unbalance, the supports 2 must be grouped in pairs, diametrically opposed, and they must be adjusted simultaneously to the same amplitude. THE figures 2 and 3 illustrate the simplest case with a single pair of supports 2. Another variant consists in arranging an even number 2N of supports 2, N being an integer ranging from 1 to typically 10, and depending above all on the diameter of the pendulum 1 and on the possibility of geometrically implanting these pairs of supports 2. In this configuration with a plurality of supports 2, not only the frequency but also the unbalance can be adjusted.

• écart de marche ΔM = 86400 * x *(2R+x) / (R² + Io/2m),
• avec R la valeur en mètres du rayon neutre de giration de la masselotte 3, Io l'inertie de base du balancier sans masselottes, en kg*m², et m la masse d'une masselotte en kg.

For the simple particular case of two diametrically opposed supports 2, illustrated by the figures, the relationship between the rate deviation (deviation from the ideal frequency) of the oscillator 100, in seconds per day, and the radial displacement X of two flyweights 3, in meters, is given by the following equation:

• rate deviation ΔM = 86400 * x *(2R+x) / (R ² + Io/2m),
• with R the value in meters of the neutral radius of gyration of the flyweight 3, Io the base inertia of the balance without flyweights, in kg*m ² , and m the mass of a flyweight in kg.

• rayon extérieur du balancier = 5.3 mm;
• giration à R = 4 mm;
• inertie du balancier sans masselottes: 2^e-9 kg*m²;
• masse d'une masselotte: 1.2 ≤ m ≤ 2.4 mg;
• plage visée +/- 15 secondes par jour.

There figure 4 illustrates the numerical application of the previous equation to a classic mechanical watch balance wheel, with the following characteristics:

• outside radius of the balance wheel = 5.3 mm;
• gyration at R = 4 mm;
• inertia of the balance without weights: 2 ^e-9 kg*m ² ;
• mass of a flyweight: 1.2 ≤ m ≤ 2.4 mg;
• target range +/- 15 seconds per day.

• courbe C1 pour m= 1,20 mg;
• courbe C2 pour m= 1,60 mg;
• courbe C3 pour m= 2,00 mg.
• courbe C4 pour m= 2,40 mg.

The graph of the figure 4 indicates on the ordinate the rate difference ΔM in seconds per day, and on the abscissa the value of the symmetrical radial displacement of two flyweights, in micrometers, and superimposes the results obtained for four flyweight mass values:

• curve C1 for m=1.20 mg;
• curve C2 for m=1.60 mg;
• curve C3 for m=2.00 mg.
• curve C4 for m=2.40 mg.

For example, curve C2, relating to flyweights 3 with a mass of 1.6 mg, corresponds to the displacement of +/- 10 micrometers of a glass parallelepiped of 0.30×1.33×1.70 mm ³ , on either side of its zero position. The frequency adjustment obtained here is +/- 11 seconds per day. This range can be easily extended, either by increasing the mass of the flyweights, or by increasing the peak-to-peak travel. A variant consists in particular in embarking, on this glass plate, an additional mass, in metal or any other ad hoc material.

The choice of the opto-mechanical actuator is essential for obtaining a reproducible and precise result. The publication already mentioned “Non-contact sub-nanometer optical repositioning using femtosecond lasers”, by Y. Bellouard, in “Optic Express, 2 November 2015, volume 23, N° 22 describes an ultra-precise positioning device, capable of being used for the alignment of fiber optic axes, which requires positioning to within a few nanometers. This is a demonstrator produced in a glass wafer, with a thickness of about 500 micrometers, commonly used in packaging and in microfluidic applications.

There figure 5 exposes, in a schematic way, the principle: the support 2 carries fasteners 30, one of which carries the opto-mechanical actuator 35 itself, which comprises two parallel arms 33 and 34, forming a U because connected at the end by a common segment 334, the first arm 33 extending between a binding 30 and the common segment, and the second arm 34 extending between the common segment 334 and an exit point, here not limited to a connecting neck 32 with an amplifying mechanism 36. The other attachment 30 carries the flyweight 3, connected by the neck 31, acting as a center of rotation.

THE figures 2, 3 , And 5 illustrate particular variants where each flyweight 3 is attached to a support 2 at its fixings 30, for ease of execution.

Another variant, visible on the figure 6 And 9 to 12 , where the flyweight 3 and the corresponding support 2 form a one-piece assembly, in particular a chip, which makes it possible to produce the flyweight 3 and the support 2 on the same level, the support 2 is then limited to an attachment zone 30 for the fixing on the pendulum 1.

In the same way it is still conceivable that the weights 3, the supports 2, and the balance 1, form a one-piece assembly, although this variant is even more expensive to produce.

According to the invention, this first arm 33 and this second arm 34 are intended to receive laser pulses, and comprise write zones 391, 392 respectively, at the level of which bursts of very brief laser pulses, emitted by the laser source 700, will create, in the thickness of the material, a local modification of its structure by molecular dilation, this dilation being quickly stopped by stopping the pulses, and the deformation therefore remaining a permanent deformation. These core deformations are infinitesimal, and therefore the method consists in locally juxtaposing a large quantity of zones thus expanded, to achieve a cumulative expansion sufficient to move the flyweight 3 sufficiently in a linear direction L. Advantageously, a mechanical amplifier 36, for example a parallelogram type mechanism with four necks as seen on the figure 6 , makes it possible to transform the overall elongation, or the overall retraction, measurable at the exit point of the second arm 34, into a stroke of the counterweight 3 which is sufficient to significantly influence the operation of the oscillator 100.

It is understood that the movement is different, depending on whether the laser pulses attack the first arm 33 or the second arm 34: the figure 7 illustrates the case where the pulses attack the second write area 392 of the second arm 34, the overall movement of the exit point is then in the direction of the arrow B, in a pushing movement of the flyweight 3. While the figure 8 illustrates the case where the pulses attack the first writing area 391 of the first arm 33, the overall movement of the exit point is then in the direction of the arrow A, contrary to the direction of the arrow B, in a retraction movement of the counterweight 3. It is thus possible to move a counterweight 3 radially in one direction or the other.

The action of the laser does not cause any cutting, nor even a superficial engraving, the goal is a molecular reordering at the heart of the material, in its thickness. The notion of writing expansion lines is a periphrasis to describe the application of series of impulses according to a network whose projection of the trajectories on the plane of the flyweight is presented as a series of very close parallel expansion lines , or very sharp zig-zag expansion lines, or the like; the aim is in fact to expand the material to the core, and to accumulate in the same linear direction L very close expansions.

By writing lines of expansion in the volume of the material at the level of the writing zones 39, in particular first writing zone 391, second writing zone 392, this material expands following the action of these zones subject to compressive stresses. This state results from a very intense point heating, but brief enough not to liquefy the material. There is just a very slight expansion of the volume, the material remaining solid. This punctual heating is carried out by a burst of very short pulses of a femtosecond laser, for example what is described, but not limited to, by the article already cited “Non-contact sub-nanometer optical repositioning using femtosecond lasers”, by Y. Bellouard, in “Optic Express, 2 November 2015, volume 23, N° 22 (Yb-fiber amplified laser, from Amplitude Systems SA, wavelength=1030 nm, pulse duration 270 fs, pulse energy approximately 250 nJ, repetition rate 800 kHz). The ray is focused through a lens into a spot of a few micrometers, at a working distance of the order of 6 mm. A three-dimensional scan precise to a few micrometers from these pulses thus makes it possible to define one or more volume zones under stress. It is obvious that a different femtosecond laser (wavelength, pulse duration, energy and repetition rate) can be used provided that it can modify the material in the same way described before. The working distance of the focusing lens can be varied depending on the shaping optics and the focusing of the laser beam.

The non-limiting mechanism of figures 5 to 8 presented here because of its great simplicity, comprises an "S" shaped actuator 35 along a radial linear direction L, and arranged to act in two opposite directions along this same direction, depending on whether the writing takes place in the upper zone of the second arm 34 (advance) or lower arm of the first arm 33 (retreat). The amplifier 36 comprises, without limitation, a crank system with connecting rods 310 between flexible necks 31 forming a linear guide in the linear direction L, and makes it possible to amplify the stroke of the actuator by a multiplying factor Km, so that the on-board square table, that is to say the counterweight 3, moves by an amplitude of a few micrometers.

According to information from the article already mentioned above (Y. Bellouard, 2015), for blocks of 200 parallel planes written in a volume with an overall length of approximately 1 mm along the linear direction L, we obtain, with the laser parameters above and according to the figures: a multiplier factor Km of 6, an amplified travel of the flyweight 3 of approximately 5 micrometers, for 200 lines of expansion written over a length of 1 mm; the actual displacement at the level of the actuator 35, in the linear direction L, is therefore worth, per written line: 5/(200*6)=4.167 nm/line (or plane).

The same technique can be used to cut the microstructure itself, according to the articles cited above. A first step consists in writing, according to the same process of core dilation under the action of a laser, volume zones to be removed in a glass plate (molten silica). In a second step, the plate is subjected to etching, which selectively removes the parts under stress. The machining obtained is also precise to the micrometer, and makes it possible to produce these glass microstructures.

THE figures 9 and 10 illustrate the application of the invention to the particular numerical example presented above, with a balance wheel with a diameter of 10.6 mm (external diameter of the rim 19); the diameter 190, here 8.0 mm, corresponds to the diameter of gyration of the centers of mass of the flyweights. The actuator 35 and the amplifier 36 are adapted to limit the flat dimensions of the supports 2 to a square of 2.0 mm side, in particular a glass chip, 0.3 mm thick, which is carrier, on the same single level, of the counterweight 3 and of the support 2 limited to at least one fixing zone 30, for the fixing to the balance 1 and for the suspension of the actuator 35, of the amplifier 36, and of the counterweight 3 .

The mechanism schematized on the figures 5 to 8 is thus modified for reasons of compactness and adaptation to the typical dimensions of a balance-spring. We hypothesize that the same sigma stresses, applied to a smaller section actuator beam, result in the same linear displacement of 4.167 nm/line, under Hooke's law: dl/l = E*sigma , with dl = increase in length, l = length of the zone, E = Young's modulus of the material. To obtain the same amplitude as the previous actuator, the writing length of the 200 expansion lines must therefore be identical and equal to 1 mm in the linear direction L.

As illustrated in figure 9 , for a glass support 2 with a thickness of 0.3 mm, the mass of the rectangular pallet which constitutes the flyweight 3 is equal to 1.6 mg, which corresponds to the walking-displacement relation C2 of the graph of the figure 4 .

The distance between the middle of two bending necks 31 delimiting a connecting rod 310 is, in this example, 1.40 mm, and the distance between the middle of the lower bending neck 31 and the connecting neck 32 is 0.14 mm. These passes bending 31 or connection 32 here have a width of 20 micrometers, which is acceptable from the technological point of view. The multiplier factor Km between the stroke of the actuator and that of the mass is, by virtue of the ratio of the lever arms: Km = 1.400 mm / 0.140 mm = 10

The maximum linear amplitude of the structure is: +/- x = Km * 200 expansion lines * 4.167 nm/line = 2000*4.167 nm = +/-8.33 micrometers, which corresponds, via graph C2, to approximately +/- Δon = +/- 9 seconds per day.

The resolution of the adjustment per line written and considering 200 lines of expansion for each of the two ranges of 9 seconds per day is therefore equal to d_marche (1 line) = 9/200 = 0.045 seconds per day and per line, which is largely sufficient to adjust a step within a range of 0 - 2 seconds per day.

It is noted that two zones 1 mm long along the linear direction L allow a single advance correction of +9 seconds per day and a delay correction of −9 seconds per day. To have several write cycles, it is possible either to increase the number of supports 2, or to increase the mass, which has the effect of having to write fewer expansion lines for the same displacement, and therefore of reserving place on the first arm 33 and on the second arm 34 for subsequent writes.

As regards the implementation of rate adjustment, a starting state is considered where, before correction, the rate of the watch is assumed to be known and measured, case closed. To perform the correction, a dedicated fitting is used to precisely position the watch head. A microscopic objective and a positioning stage with crossed movements xy then allows the centering of the laser source 700, in particular a femtosecond laser, on the balance wheel 1.

From this stage, two options present themselves: either the balance wheel is immobilized by a blocking/braking lever, such as a stop-seconds or the like, or an oscillator spatial stop and hold mechanism, and the laser shot is performed on a stationary target, or the pendulum 1 is still oscillating, and the laser shot must then be synchronized with its position angular.

The case where the pendulum is immobilized, and the laser firing carried out on a stationary target, can be solved with semi-automatic positioning for example and not limited to piloting means managing a camera with image recognition software which center on the axis of rotation D of the balance wheel.

In the case where the balance 1 oscillates, and where the laser firing is synchronized with its angular position, the method is more complex, but more advantageous because the adjustment is carried out in flight, without the need to stop the balance. The firing can be started with the beginning of the passage of the support 2 through a laser beam of detection 750, as illustrated on the figures 11 and 12 .

There figure 11 is a diagrammatic view, in section passing through the axis of rotation D of the balance 1, and showing the rim 19 of this balance, carrying a support 2, the flyweight 3 not being represented, and the laser source 700 for writing for writing on the writing areas 39, 391, 392, as well as, mounted obliquely in the left part of the figure, such a detection laser 750, the ray of which is reflected by the pendulum 1 and the elements it comprises is collected in the right part of the figure by a collection means 760 such as a photo-detector.

There figure 12 illustrates the detail of the layout according to the figure 11 with a laser writing source 700 and a laser detection source 750, for the case where the pendulum 1 oscillates, and where the laser firing is synchronized with its angular position; the serge 19 of the pendulum 1 carries a chip according to the figure 9 ; the arc shown in dashed line corresponds to the instantaneous position of the laser writing source 700, which shoots perpendicular to the plane of the figure, and which can thus write in the first writing zone 391 of the first arm lower 33 in this case, to create an expansion line 390, that is to say a molecular expansion symbolized by a small arrow in this first writing area 391, the small neighboring arrows corresponding to d' other expansion lines 390, i.e. writes already performed in the same area with different positionings in x of the write source 700, corresponding to different radii with respect to the axis of rotation D of the balance 1. In the lower part of the figure is visible from left to right a laser detection source 750, a converging lens 770, the incident radiation towards the balance 1, the point of reflection on the balance 1 or on the organs it carries, the reflected radiation, a converging lens 780, and the photo-detector 760.

On the figure 12 , the left edge of rim 19 of balance wheel 1 oscillates up and down in its circular trajectory. Chip 2 is attached to pendulum 1 by its base. The optics are composed of a writing laser source 700 to carry out the optical axis writing along the direction z perpendicular to the plane of the balance beam 1, and of a detection laser 750, for example inclined at an angle of 45° with respect to the plane of the pendulum, the axes of the incident and reflected beams of which are included in the xz plane. Their respective spots may be slightly offset in x, but must remain on the same dimension in z.

There figure 13 juxtaposes three time graphs, established with different time scales on the abscissa, but which are arranged relative to each other to highlight particular instants and the phenomena that occur there: the upper graph displays on the ordinate the angular velocity omega OME of the pendulum 1, the middle graph displays on the ordinate the value of the signal VPD of the photo-detector 760, and the lower graph displays on the ordinate the optical intensity IIE emitted by the writing laser source 700.

When pendulum 1 oscillates, its angular velocity OME is maximum near the neutral point, i.e. between times t1 and t4 of the graph superior of the figure 13 , which corresponds to a balance-spring oscillating at a few Hz. This zone is interesting, because the speed does not vary much so it can be considered as quasi-constant. The detection laser 750 is thus used to turn on and off a burst of write pulses, coming from the write laser source 700.

The VPD signal of the photo-detector 760 associated with the detection laser 750 is at the value 1 when its spot is on a solid zone of the chip 2, that is to say successively fixing zone 30 / first lower arm 33 / second upper arm 34/ weight 3, as visible both on the median graph of the figure 13 and on the figure 12 , and the VPD signal is at the value 0 in a slot. Thus, this signal can be used to trigger and trigger the writing of the burst by the writing laser source 700, that is between times t2 and t3, and more exactly in a first writing zone 391 for the adjustment of advance on the first arm 33, or in a second writing zone 392 for the delay adjustment on the second arm 34. In the example illustrated by the figure 12 , four expansion lines 390 are written in the first advance zone on the first arm 33, which will pull the flyweight 3 towards the axis of rotation D of the balance 1, and cause a march advance by increasing the frequency. The start of the IIE optical intensity bursts is triggered by the positive edge of the VPD signal at the instant TON, and their termination is triggered by the negative edge of the VPD signal at the instant TOFF. One can, for example, use an alternation, that is to say a half-period, to write an expansion line 390, then shift by an increment x with the write laser source 700, to write the next adjacent expansion line to the next alternation, and so on. The direction of rotation is detected using the VPD signal, the pattern of which is different depending on the direction. This allows the writing laser source 700 to always be turned on in the correct area.

• Te = Le / (R*A*2π*F), avec R = rayon de giration, A= amplitude angulaire du balancier et F= fréquence de l'oscillateur.

The writing duration Te (passage) in the first advance zone on the first arm 33, or in the second delay zone on the second arm 34, which is a zone of length Le, is given by:

• Te = Le / (R*A*2π*F), with R = radius of gyration, A= angular amplitude of the balance and F= frequency of the oscillator.

In this example, Le = 190 um, R = 4 mm, A = 270°, F = 4 Hz, hence Te = 0.40 ms.

The repetition frequency of the write pulses being 800 kHz in this example, the number of pulses per pass is therefore equal to 800 * 0.40 = 320, and therefore the maximum (cumulative) error of the rate is therefore equal to: 1 /320 * (+/-9 seconds per day) = +/- 0.03 seconds per day, which is perfectly satisfactory for the application.

The technique of glass machining by femtosecond laser and chemical attack, which makes it possible to produce three-dimensional structures precise to the nearest micrometer, is a proven technique.

This technique makes it possible to produce 2 millimeter chips with flexible elements that can move over micrometric amplitudes, with nanometric precision. Actuation of the nano-displacement of the actuator part 35 is performed by laser writing of internal stresses. A system of flexible necks 31 and rods 310 makes it possible to increase the amplitudes in the linear direction L.

The production of such a chip 2 is suitable for the precise and reliable adjustment of the rate of a balance-spring, with an accuracy of 0.03 seconds per day, and a resolution of 0.09 seconds per day, in a range of typically +/-10 seconds per day. Of course, the range amplitude and the resolution can be easily varied by adapting the design.

It can be noted that the invention offers the possibility of carrying out an infinitesimal and irreversible expansion, which, in theory, could allow, by a series of shots on the elastic return element of the oscillator, such as spiral spring, flexible blade or similar, to modify its stiffness; however, the creation of these deformed zones harms the homogeneity of the component, and the risk is an alteration of the elastic properties of this elastic return element. This is why the invention is presented here preferentially for action on the inertial element, regardless of whether it is suspended by a spiral spring, or by elastic blades.

The adjustment system is compact and does not require any additional complications in the watch 1000, other than the mounting of two or more glass chips 2 on the balance wheel 1.

This adjustment can be carried out directly on a complete watch 1000, on condition that the watch head 500 comprises a transparent transmissive element 600, such as a bottom, crystal, or other, which is transparent or non-absorbent for the laser. writing in optical access on the oscillator. The invention naturally relates to a watch 1000 thus equipped.

There figure 14 illustrates the peripherals and their links: the piloting means 790, a cross-movement table 710 for operating the writing laser 700, a detection laser 750, the means for collecting the reflected radiation 760, and means 720 for stop and release of oscillator 100.

The external part of the adjustment (setup, microscope, optics and lasers) typically occupies the volume of an office, which allows quick and user-friendly adjustment, both in production and in the shop for customer service.

The implementation of the invention is all the better if optimization of the absorption of radiation is achieved by the separation of physical protection (box, casing), if a reliable positioning system of the laser spots. Naturally, it is advisable to adopt an appropriate dimensioning for the live zones, above certain dimensions determined experimentally, to avoid a increased fragility of these areas under tension, which could cause premature rupture during shocks.

Claims (23)

Process for fine adjustment of the rate of a mechanical clock oscillator (100) comprising at least one inertial mass (1), for example but not limited to: a balance wheel, arranged to oscillate around an axis of rotation ( D) and returned to a rest position by elastic return means, characterized in that , in a first step (801), said oscillator (100) is equipped with at least one said inertial mass (1) comprising an actuator (35 ) in a material capable of irreversible local micro-expansion under the action of laser shots, said actuator (35) being arranged to impart to a flyweight (3) a radial linear stroke with respect to said axis of rotation (D), directly or via at least one stroke amplifier (36), when a writing area (39; 391; 392) that said actuator (35) comprises is subjected to appropriate laser shots, in a second step (802) a first coarse adjustment of the initial rate of said oscillator (100) is carried out in a first rate range and said rate is measured, in a third step (803) the direction and the value of the rate deviation are calculated to print on said oscillator (100) to bring it into a second predetermined operating range, and the direction and the value of the stroke to be printed on each said flyweight (3) that said oscillator (100) comprises, in a fourth step (804) subjecting at least one said write zone (39; 391; 392) to femtosecond laser shots to create at least one expansion line (390) by local molecular expansion of said material to deform said actuator (35) radially relative to said axis of rotation (D), in a fifth step ( 805) the rate of said oscillator (100) is measured and said third step (803) and said fourth step (804) are repeated if necessary until the rate of said oscillator (100) is in said second rate range. Method according to claim 1, characterized in that said method is applied to a said oscillator (100) with at least two said inertial masses (1) each comprising a said actuator (35). Method according to claim 1 or 2, characterized in that , during said fourth step (804), a femtosecond laser source (700) is used mounted on a table with crossed movements (710) or with radial travel, so as to juxtapose different series of shots on different radii from said axis of rotation (D) to create a series of said expansion lines (390) in close proximity to each other. Method according to one of Claims 1 to 3, characterized in that , during said fourth step (804), a femtosecond laser source (700) is used to perform laser shots in each direction of rotation of said inertial mass (1) . Method according to one of Claims 1 to 4, characterized in that , during the said fourth step (804), piloting means (790) are used to pilot the shots from the said femtolaser source (700) according to the presence information or absence of material provided by the combination of a detection laser (750) and a collection means (760) or a photo-detector. Method according to one of Claims 1 to 5, characterized in that , during said first step (801), a said actuator (35) is chosen comprising, on a first arm (33), a first writing zone (391) , and on a second arm (34) parallel to the first arm (33) in a radial linear direction (L) and joining it at a common segment (334) a second writing area (392), said actuator ( 35) being thus mounted in an "S" between on the one hand an attachment zone (30) fixed to a support (2) mounted on said inertial mass (1) or directly fixed on said inertial mass (1), and on the other hand an exit point or a connection neck (32) for connection with an amplifier mechanism (36), said actuator (35) being arranged to act in two opposite directions along said linear direction (L), depending on whether, during said fourth step (804), writing by femtolaser shots takes place in said first writing zone (391 ) on said first arm (33) for advance setting, or in said second write area (392) on said second arm (34) for lag setting. Method according to one of Claims 1 to 6, characterized in that , during said first step (801), a said actuator (35) is chosen with an exit point or a connection neck (32) for connection with a mechanism amplifier (36) arranged to amplify the output stroke of said actuator (35), to impart an amplified stroke to said flyweight (3). Method according to Claim 7, characterized in that the said amplifier (36) is of the parallelogram type, and comprises a crankshaft system with connecting rods (310) arranged between flexible necks (31) forming a linear guide in a linear direction ( L) radial. Method according to one of Claims 1 to 8, characterized in that , during said first step (801), a said actuator (35) is chosen comprising an attachment zone (30) integral with a support (2) mounted on said inertial mass (1), and in that said support (2) forms a one-piece assembly constituting a flexible micro-mechanism, with said actuator (35), an amplifier (36) and said flyweight (3) connected in series with each other with the others. Method according to one of Claims 1 to 9, characterized in that , during the said first step (801), a said actuator (35) is chosen comprising a fixing zone (30) fixed to a support (2) mounted on the said inertial mass (1) or secured to a said support (2) and in that said actuator (35) and/or said support (2) is made of glass. Method according to one of Claims 1 to 10, characterized in that , during the said first step (801), the said inertial mass (1) is chosen in the form of a pendulum, which comprises at least one pair of said flyweights (3) which are identical and diametrically opposed with respect to said axis of rotation (D). Method according to one of Claims 1 to 10, characterized in that , during the said first step (801), the said oscillator (100) is integrated into a watch head (500) of a watch (1000), which watch head watch (500) comprises at least one transparent transmissive element (600), which separates the outside and the inside of said watch (1000) and allows optical access to at least one laser towards at least said inertial mass (1) of said oscillator (100) of the watch. Method according to one of Claims 1 to 12, characterized in that , during the said first step (801), the said oscillator (100) is fitted with stop means or with a stop-seconds arranged to bear on a said inertial mass (1), and in that said fourth step (804) is carried out in a locked position of said inertial mass (1). Method according to one of Claims 1 to 12, characterized in that , during said fourth step (804), said writing femtosecond laser shots are carried out during the oscillation of said inertial mass (1), the position of which is synchronized angular and said shots. Method according to one of Claims 1 to 14, characterized in that , during the said fourth step (804), the said firings are carried out with a femtosecond laser. Method according to claim 15, characterized in that , during said fourth step (804), said shots are carried out with a femtosecond laser, of wavelength between 900 and 1100 nm, of pulse duration between 200 and 350 fs, energy of a pulse approximately between 200 and 300 nJ, repetition frequency of 700 to 900 kHz., Clockwork mechanical oscillator (100) comprising at least one inertial mass (1) arranged to oscillate around an axis of rotation (D) and returned to a rest position by elastic return means, characterized in that at least one said inertial mass (1) comprises an actuator (35) in a material capable of irreversible local micro-expansion under the action of laser shots, said actuator (35) being arranged to impart to a flyweight (3) a radial linear stroke with respect to said axis of rotation (D), directly or via at least one stroke amplifier (36 ), when a writing area (39; 391; 392) that said actuator (35) comprises is subjected to appropriate laser shots. Mechanical oscillator (100) according to Claim 17, characterized in that the said actuator (35) comprises, on a first arm (33) a first writing zone (391) and on a second arm (34) parallel to the first arm ( 33) in a radial linear direction (L) and joining it at a common segment (334) to a second writing zone (392), said actuator (35) thus being mounted in an "S" shape between on the one hand a fixing zone (30) fixed to a support (2) mounted on said inertial mass (1) or directly fixed on said inertial mass (1), and on the other hand an exit point or a connecting neck (32) for connection with an amplifier mechanism (36), said actuator (35) being arranged to act in two opposite directions along said linear direction (L), depending on whether said femtosecond laser shots are applied in said first write zone (391) on said first arm (33) for advance setting, or in said second write area (392) on said second arm (34) for lag setting. Mechanical oscillator (100) according to claim 17 or 18, characterized in that said actuator (35) comprises an exit point or a connection neck (32) for connection with an amplifier mechanism (36) arranged to amplify the exit stroke said actuator (35), to impart an amplified stroke to said flyweight (3), and in that said amplifier (36) is of the parallelogram type, and comprises a system crankshaft with connecting rods (310) arranged between flexible necks (31) forming a linear guide in a radial linear direction (L). Mechanical oscillator (100) according to one of Claims 17 to 19, characterized in that the said actuator (35) comprises an attachment zone (30) integral with a support (2) mounted on the said inertial mass (1), and in that said support (2) forms a one-piece assembly constituting a flexible micro-mechanism, with said actuator (35), an amplifier (36) and said flyweight (3) connected in series with each other. Mechanical oscillator (100) according to one of Claims 17 to 20, characterized in that the said actuator (35) comprises a fixing zone (30) fixed to a support (2) mounted on the said inertial mass (1) or integral with a said support (2) and in that said actuator (35) and/or said support (2) is made of glass. Mechanical oscillator (100) according to one of Claims 17 to 21, characterized in that the said inertial mass (1) is a pendulum, which comprises at least one pair of said flyweights (3) which are identical and diametrically opposed with respect to the said axis of rotation (D). Watch (1000) comprising at least one mechanical oscillator (100) according to one of Claims 17 to 22, characterized in that the said watch (1000) comprises a watch head (500) comprising at least one transparent transmissive element (600) , which separates the outside and the inside of said watch (1000) and allows optical access by at least one laser to at least said inertial mass (1) of said oscillator (100) of the watch.

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