EP2808745B1 - Striking mechanism provided with means for selecting chime vibration mode - Google Patents

Description

The invention relates to a striking mechanism, which is provided with means for selecting at least one vibratory mode of a stamp or several stamps. The striking mechanism, especially for a watch, further comprises at least one stamp attached to a stamp holder, and at least one hammer for striking the stamp at predetermined times.

Document is known US 2,727,423 a chime, which comprises at least one stamp attached to a stamp holder, at least one hammer for striking the stamp at predetermined times, and means for selecting at least one vibratory mode of the stamp. In particular, these selection means, mobile or fixed, comprise at least one selector element disposed in contact on a part of the patch and held on a vibration node of one of the vibratory modes of the stamp so as to completely or partially remove the others vibratory modes.

In the field of watchmaking, a traditional architecture is used to perform movements, which are provided with striking mechanisms, such as minute repetitions. In these embodiments, the stamp used is a metal wire, which may be circular or rectilinear. This circular-shaped wire may be arranged around the movement in the watch cage. This stamp is attached to at least one stamp holder, which is itself secured to a watch plate. The vibration of the stamp is produced by the impact generally near the stamp holder of at least one hammer. This vibration is composed of several eigenfrequencies, whose number and intensity, especially in the audible range, depend on the geometry of the patch, the conditions of fixation or support of the patch, shock conditions and physical properties. of the material. The vibration of the stamp is also transmitted to the downstream elements in the watch case via the stamp holder, and radiated into the air.

An example of such a traditional clock mechanism is given by the document EP 1 906 267 A1 .

However, the document EP 2 463 732 A1 describes a striking clock mechanism in which the striking of the stamp is produced by a magnetic hammer.

When the hammer of the striking mechanism strikes the stamp (s) in a ring mode, the tone will vibrate with a superposition of all its own modes of vibration. The timbre can thus vibrate with different modes of vibration in the frequency range from 100 Hz to 20 kHz. For a gold or steel stamp, for example 0.6 mm in diameter and length close to 90 mm, a first natural mode of vibration is generally close to 100 Hz, and the density of vibration modes can rise to 3 kHz ^-1 in the frequency range between 3 kHz and 10 kHz in particular. The first modes of vibration below 1 kHz can not generally be effectively radiated by the elements of the watch. Their activation therefore represents a loss of acoustic energy, which is a drawback. In addition, too much spectral density can create a sound too rich, which can become cacophonic, which is also a disadvantage of traditional ringing mechanisms.

To generate a harmonious sound, it is generally necessary to control the frequency contribution of the vibration generated during the punching. The optimization of the impact conditions of the hammer on said stamp is not sufficient to select the desired frequency composition, so the harmonic agreement. In particular, it does not increase the purity of the sound produced.

The invention therefore aims to overcome the drawbacks of the state of the art by providing a striking mechanism, in particular for a watch, capable of selecting a particular mode of vibration of at least one stamp struck by a hammer, which is simple to achieve.

To this end, the invention relates to a striking mechanism cited above, which comprises the features defined in the independent claims 1 and 2.

Particular embodiments of the striking mechanism are defined in dependent claims 3 to 16.

An advantage of the striking mechanism according to the present invention is that it makes it possible to obtain an original sound during the striking of the patch by positioning at least one selector element at a node of a vibratory mode. at least one stamp. Activation of this mode is favored by said selector. Such a sound can thus present a dominant recognizable note. Such a vibratory mode selector element has the additional advantage of considerably limiting the parasitic vibrations of the timbre during accidental micro-shocks. It thus makes it possible to suppress the parasitic noises.

Another advantage of the striking mechanism according to the present invention is that there is a better use of energy. Vibration modes at low frequency can be blocked by the selector element and thus do not consume energy.

Another advantage of the striking mechanism according to the present invention is that it is also possible to create various notes with several selector elements arranged on a stamp. This allows a choice of the note by the use and a differentiation of the sound for example between midnight and noon and between noon and midnight. In addition, the means for selecting a vibratory mode can be made at low cost or conversely, if desired, they can be made of precious materials. This makes it possible to contribute actively to the aesthetic value and the preciousness of the watch.

Advantageously, the displacement of the selector element on one or more stamps can be operated mechanically by a rack arrangement or magnetically by an arrangement of magnetic components between the selector element and a means of movement of the striking mechanism.

• la figure 1 représente un graphique simplifié de la déformée d'un timbre fixé à une extrémité avec différents modes de vibration suite à l'impact d'un marteau et l'emplacement des éléments sélecteurs de mode de vibration,
• la figure 2 représente une vue tridimensionnelle simplifiée d'une première forme d'exécution du mécanisme de sonnerie avec des moyens de sélection de mode vibratoire d'un ou deux timbres selon l'invention,
• les figures 3a et 3b représentent une vue tridimensionnelle simplifiée et une vue simplifiée de dessus d'une seconde forme d'exécution du mécanisme de sonnerie avec des moyens de sélection magnétique de mode vibratoire d'un ou deux timbres selon l'invention, et
• les figures 4a et 4b représentent deux vues simplifiées de dessus d'une troisième forme d'exécution du mécanisme de sonnerie avec des moyens de sélection magnétique de mode vibratoire d'au moins un timbre selon l'invention.

The purposes, advantages and characteristics of the striking mechanism of a watch will appear better in the following description especially with regard to the drawings in which:

• the figure 1 represents a simplified graph of the deformation of a stamp fixed at one end with different modes of vibration following the impact of a hammer and the location of the vibration mode selectors,
• the figure 2 represents a simplified three-dimensional view of a first embodiment of the striking mechanism with vibratory mode selection means of one or two stamps according to the invention,
• the figures 3a and 3b represent a simplified three-dimensional view and a simplified view from above of a second embodiment of the striking mechanism with magnetic vibration mode selection means of one or two stamps according to the invention, and
• the Figures 4a and 4b represent two simplified views from above of a third embodiment of the striking mechanism with vibratory mode magnetic selection means of at least one stamp according to the invention.

In the following description, all parts of the striking mechanism of a watch, which are well known in this technical field, will be described only briefly. Reference will be made exclusively to the means for selecting at least one vibratory mode of a stamp or several stamps without mentioning in detail the hammer or the hammers and their arrangement in the mechanism to be able to strike the stamp or stamps.

The figure 1 is a graph of the deformation of a stamp of length L, which is embedded for example at one of its ends to a stamp holder attached to an inner portion of a watch, for example a platen. On this figure 1 , it is shown different modes of vibration of the stamp following the impact of a hammer. Without vibration mode selection means, the timbre is capable of vibrating with the combination of a first vibration mode indicated by n = 1, a second vibration mode indicated by n = 2 and a third mode of vibration. vibration indicated by n = 3. Several other modes of vibration can still be combined with the first three modes of vibration, but are not shown so as not to overload said figure.

The graph of the figure 1 is for example defined for a stamp with a diameter of less than 1 mm, for example at 0.6 mm, and a length by example of the order of 90 mm. The stamp is in this example embedded at one of its ends to a stamp holder as shown by the graph at the origin of the x-axis. The stamp material may be selected from steel or gold or metal glass, i.e. metal or amorphous metal alloy. This metal glass may for example be based on zirconium, gold, platinum or gold with palladium, platinum and silver or any other metal capable of solidifying in amorphous form.

The striking mechanism therefore comprises means for selecting at least one vibration mode of the stamp. These selection means comprise at least one selector element or two selector elements as symbolically represented on the figure 1 . It can also be provided a means for moving and positioning the selector element or elements. These selector elements are arranged at the location of the vibration nodes of the third vibratory mode, that is to say a nip can be operated by these selector elements vibration nodes of the third mode. Under these conditions, all the other modes of vibration are pushed at higher frequency and thus strongly suppressed by these selector elements. The timbre thus vibrates mainly according to that which would be its third vibratory mode in the absence of a selector element.

Of course, the deletion of the lower frequency modes, particularly that which would be the fundamental mode without nodes in the absence of the selector element, can also be accomplished by a single selector element disposed at the first vibration node of the third vibratory mode. It can also be selected another vibratory mode having a higher or lower frequency than the third mode by one or more selector elements arranged differently. In the embodiments discussed below, it is thus referred to only a vibrating mode selector element, but also several selector elements can also be provided for each stamp as mentioned on the figure 1 .

$$\left({\mathrm{w}\prime \left(\mathrm{X}0,\mathrm{t}\right)|}_{\mathrm{x}=\mathrm{X}0}\right)\ne 0$$

w(x, t) étant le déplacement du timbre dans une des deux directions orthogonales à l'axe du timbre, w'(x, t) étant la dérivée première du déplacement en fonction de la coordonnée x et t étant le temps. La condition (1) impose que le timbre ne soit pas mobile en correspondance de l'élément sélecteur, tandis que la condition (2) garantit que l'axe du timbre puisse être incliné par rapport à sa position de repos en correspondance de l'élément sélecteur.It should also be noted that the striking mechanism of the invention is characterized by the presence of at least one mode selector element, at least one stamp having conditions of the flush-free or recessed-supported type edges. or recessed-recessed. A mode selector element is physically defined as a component, fixed or mobile, allowing the realization of a simple mechanical support condition of the stamp in a position corresponding to a node of one of the free modes of the flush-free stamp, recessed -supported or recessed-recessed. Mathematically, a mode selector element positioned in correspondence of the X0 position on the main axis of the stamp, which is oriented in the x direction, is defined by the following simple mechanical support conditions: $$\mathrm{<figure-callout\; id="0"\; label="w\; X"\; filenames="imgf0001.png"\; state="\{\{state\}\}">w\; </figure-callout>}\left(\mathrm{X}\right)\left(\mathrm{}0,\mathrm{t}\right)=0$$

$$\left({\mathrm{w}\text{'}\left(\mathrm{<figure-callout\; id="0"\; label="X"\; filenames="imgf0001.png"\; state="\{\{state\}\}">X</figure-callout>}0,\mathrm{t}\right)|}_{\mathrm{x}=\mathrm{<figure-callout\; id="0"\; label="X"\; filenames="imgf0001.png"\; state="\{\{state\}\}">X</figure-callout>}0}\right)\ne 0$$

w (x, t) being the displacement of the timbre in one of the two directions orthogonal to the axis of the timbre, w '(x, t) being the first derivative of the displacement as a function of the coordinate x and t being the time. Condition (1) imposes that the patch is not mobile in correspondence of the selector element, while condition (2) ensures that the axis of the stamp can be inclined relative to its rest position in correspondence of the selector element.

The introduction of a mode selector element modifies the frequency and the modal form of all modes of the timbre except those of the selected mode, having a node corresponding to the position of the selector element and thus making it possible to respect the conditions ( 1 and 2).

The figure 2 represents a first embodiment of the striking mechanism 1 with means for selecting at least one vibratory mode of at least one stamp. In this first embodiment, there are two stamps 3, 3 'of rectilinear shape and each fixed at one of their ends to the same stamp holder 2. Both stamps 3, 3 'are thus arranged parallel to one another. The two stamps may have a length and a cross section, which may preferably be identical or different depending on the note to be radiated when striking either hammer provided. The stamp holder 2, and the rotary hammer or not shown, are generally mounted on a not shown watch plate.

The vibratory mode selection means of the striking mechanism 1 comprise firstly a selector element 4 disposed on the stamps 3, 3 '. The selector element 4 may be arranged at a location of the stamps corresponding to a node of a vibration mode of the stamps to be selected so as to eliminate unwanted vibratory modes of one or the other vibration stamp. This selector element 4 can thus be moved along the length of the timbres 3, 3 'to occupy a position defined according to the vibratory mode to be selected by a moving or positioning means. Preferably, this selector element 4 consists of two rings joined by a central piece. The two parallel rings may have the same inner diameter, which is close to or slightly greater than the diameter of the cross section of each patch. The distance between the centers of the two rings is identical to the distance between the centers of the two stamps. The two rings are initially introduced or inserted from a free end of each patch to allow the selector element 4 to slide along the length of the stamps 3, 3 '.

The inner portions 4a of the two rings of the selector element 4, which come into contact with the outer surface of each patch can be made with olive stones. This facilitates the sliding of the selector element on the stamp or stamps 3, 3 'and also to generate a contact point or a contact line on each stamp to select the desired vibratory mode. Instead of the olive stones, it can also be used microbeads. These microbeads guarantee punctual contacts and allow locking in translation according to the direction orthogonal to the axis of the stamp in correspondence of the vibration node (relation 1) without rotation lock (relation 2).

The vibratory mode selection means further comprise a wheel 6, the periphery of which can come into contact with a rectilinear extension 5 of the central part of the selector element 4. The axis of rotation 7 of the wheel 6 is disposed of preferably perpendicular to the stamps 3, 3 'so that the wheel 6 in rotation r drives the selector element 4 by its rectilinear extension 5 in a direction d along the length of the stamps 3, 3'. The rectilinear extension 5 extends parallel between the two timbres 3, 3 'and is of a length allowing in cooperation with the wheel 6 to move the selector element 4 on at least one position of the stamps relative to the selection of a vibratory mode of the stamps.

In the first embodiment of the striking mechanism 1, the wheel 6 is a toothed wheel 6a, while the extension 5 comprises a series of teeth 5a in the direction of the extension length, which can mesh with the teeth of the tooth wheel. In this way, the extension 5 can be moved in the direction d of the two stamps 3, 3 'by a rack arrangement. The wheel 6 is rotated by a winding stem 7, which ends towards the outside of the watch case by a ring 8. This ring 8 can normally be pulled or pushed from outside the case of the watch. to allow the rotation of the wheel 6 and the positioning of the selector element 4 on the stamps 3, 3 '.

It should be noted that the selector element 4 may also be of another form than that mentioned above. It may be provided to have a parallelepiped shaped selector element 4 with two through openings of diameter equal to or slightly greater than the diameter of the cross section of each patch. The distance between the centers of the two openings is identical to the distance between the centers of the two stamps so as to allow the selector element to slide on the stamps. The two openings can also be lined with olive stones to ensure contact on the outer surface of each patch.

For the movement of the selector element by means of the rack arrangement and the winding stem, a push button can be provided. This push button can be connected to an activation rod to allow the mode selector element to be positioned at a desired location on the stamp or stamps and this with each press of the button. With this, it is possible to change the ring tone on demand or to generate a different sound depending on the night or the day of the watch with the striking mechanism 1.

It can also be provided a selector element 4 in the form of a single ring or a parallelepiped shaped block with a through opening to come on a single stamp. The opening of the ring or the block may be of a shape other than circular, for example rectangular or hexagonal depending on the cross section of the stamp. A rectilinear extension can be arranged on an outer portion of the ring or the block and arranged parallel to the length of the stamp. The selector element 4 can be driven by the wheel 6 via the extension to move it along the timbre. The extension may include a series of teeth meshing with the teeth of the tooth wheel. The driving of the wheel 6 can be carried out by a gear arrangement, activated by the mainspring of the watch until the position of the selector element to the desired vibratory mode is reached. Two selector elements may also be provided to slide independently of each other on each respective timbre, to select the same vibratory mode or two different vibratory modes.

The figures 3a and 3b represent a second embodiment of the striking mechanism 1 with means of magnetic selection of at least one vibratory mode of one or more stamps. It should be noted that the elements of figures 3a and 3b , which correspond to those of the figure 2 , bear identical reference signs. Therefore for simplification, it will not be described in detail all these same elements. In this second embodiment, there are therefore two stamps 3, 3 'of rectilinear shape and each fixed at one of their ends to a same stamp holder 2.

The difference of this second embodiment with respect to the first embodiment lies in the fact that magnetic components are used for the displacement of the selector element 4 on the stamp or stamps 3, 3 '. In this second embodiment, it is preferable that the stamps are made of a non-ferromagnetic material, for example gold or metal glass, so as not to influence the movement of the selector element. The selector element 4 is represented in the form of two rings joined by a central piece. As for the first embodiment, the two rings furnished or not with olive stones allow the selector element 4 to slide on the stamps 3, 3 '. A magnetic element, which may be a permanent magnet 15, is disposed in the central part of the selector element or is made in the material of the central part. The north-south magnetic polarization direction of this magnet is in the direction of the length of the stamp (s).

The selection means further comprises a screw 16 having a magnetized end portion 16a or provided with a first permanent magnet 16a at the end of the screw opposite to the screw head. The direction of magnetic polarization of the end portion of the screw is in the direction of the length of the stamps 3, 3 ', but of opposite polarization to that of the magnet 15 of the selector element 4. This screw 16 passes in a tapped support 17. This support can be fixedly mounted on a platen of the watch. The longitudinal axis of the screw is arranged parallel to the stamps. The rotation r of the screw 16 in the tapping of the support 17 makes it possible to move the magnetized portion 16a of the screw 16 in the direction of the selector element 4 or in the opposite direction. When the magnetized portion 16a of the screw approaches the magnet 15 of the selector, this has the effect of pushing it back as represented by the arrow in dashed lines on the figure 3b , and slide the selector element 4 on the stamps.

In order to maintain the selector element in a specific position on the timbres 3, 3 ', the vibratory mode selection means further comprise a second permanent magnet 18 placed between the embedding of the two stamps 3, 3' in the holder. 2. The direction of magnetic polarization of this second permanent magnet 18 is also in the direction of the length of the stamps and polarization opposite to that of the magnet 15 of the selector element 4. This second permanent magnet 18 repels the selector element, just like the first magnet 16a of the screw as represented by the arrows in dashed lines on the figure 3b . An equilibrium is established when the repulsive force generated by the first permanent magnet 16a on the magnet 15 of the selector element is equal to the repulsive force generated by the second permanent magnet 18 on the magnet 15. Thus a position determined selector element 4 can be performed to select a vibratory mode of the vibration stamps.

The Figures 4a and 4b schematically represent a third embodiment of the striking mechanism 1 with magnetic selection means of at least one vibratory mode of at least one stamp. It should be noted that the elements of Figures 4a and 4b , which correspond to those of Figures 2, 3a and 3b bear identical reference signs. Therefore for simplification, it will not be described in detail all these same elements.

The striking mechanism 1 of this third embodiment comprises a single rectilinear stamp 3 fixed at one of its ends to a stamp holder 2. A selector element 4 in the form of a ring or a parallelepipedic opening block 1. This selector element 4 comprises a permanent magnet, which can be made directly in a part of the material of the selector element 4 or be fixed on a part of the selector element. The direction of north-south magnetic polarization of this magnet of the selector element 4 is in the direction of the length of the stamp 3.

The striking mechanism 1 further comprises, as selection means, a screw 16 having a magnetized end portion 16a or provided with a magnet 16a at the end of the screw opposite to the screw head. This screw 16 passes through a threaded support 17, which can be mounted on the watch plate. The direction of magnetic polarization of the magnetized end portion of the screw or magnet at the end of the screw is in the direction of the length of the patch 3, but of magnetic polarization opposite to that of the magnet of the selector element 4. The screw is arranged in parallel with the stamp with the magnet 16a next to the magnet of the selector element and without contact with the magnet of the selector element 4.

To the figure 4a as the magnet 16a of the screw 16 is next to the magnet of the selector element with an opposite magnetic polarization direction, a magnetic attraction between the two magnets occurs. In a position of rest without displacement of the selector element 4, the position of this selector element is well defined by the magnetic interaction or attraction in connection with the magnet 16a of the screw 16. The magnetic forces existing between the two magnets , in combination with the elastic return force of the patch, suppress the translation movements of the magnet of the selector element 4, that is to say the movements in the direction of the length of the stamp 3, as well as in the direction perpendicular to the stamp 3. On the contrary, the rotational movements of the stamp are not removed, because they do not substantially modify the magnetic co-energy of the system consisting of the two antiparallel magnets. During the impact of the hammer against the timbre, the selector element must be positioned on a vibratory mode node to be selected.

To the figure 4b , it is shown a displacement of the magnet 16a of the screw 16 following a rotation of said screw in the support 17. Under these conditions, there is a force of attraction F on the magnet of the element selector 4 imposing a displacement with sliding on the stamp 3 to be next to the magnet 16a of the screw 16. At equilibrium, the selector element 4 can be in a position corresponding to the vibratory mode selected.

It should be noted that the principle of moving the selector element or the selector elements by the arrangement of magnetic components is quite generalizable to a not shown circular shape stamp. Under these conditions, it can be provided a magnet on a disk centered with respect to the center of the circular shape of the stamp. When rotating the disc with the magnet, the selector element with another magnet on the patch can be moved by the magnetic repulsion of the magnet on the disc.

It should also be noted that the selector element 4 of one or other of the embodiments presented above may be in the form of a clamp, as selection means. This clamp can thus sandwich the stamp or stamps 3, 3 'to at least one node of a vibratory mode of the stamps. This type of clip-shaped selector element can be chosen instead of the contact made with the olive stones. The clip-shaped selector element minimizes the contact area between the patch (s) and the vibratory mode selector element. This selector element 4 may be in the form of a flexible guide, which is composed of two or more blades of micrometric thickness made of silicon, or of silicon oxide or NiP, such as LIGA. Each of these blades is embedded in two supports, and deformed in flexion to allow to firmly sandwich one or more stamps 3, 3 'to at least one node of a vibratory mode of the stamp or stamps. The contact width for such a clamp may be of the order of 5 microns or less.

Instead of olive stones in the selector element 4, two micro-magnets may be provided arranged on either side of the stamp 3, which is made of ferromagnetic material or which is coated with a ferromagnetic material such as the Nickel. In this way, the plan defined by the two micro-magnets and the stamp is orthogonal to the vibration plane of the stamp.

All the embodiments described above relate to one or more stamps type recessed to a stamp holder at one of their ends and whose other end is free movement. However, it can also be envisaged to have one or more stamps with both ends attached to a first stamp holder and a second stamp holder. It can also be envisaged to have one or more stamps with a fixed end to a stamp holder and the other end supported on a support to define a single support condition. The mode selector systems described herein can be applied directly to this different stamp typology without major modification.

Instead of a selector element consisting of olive stones, it can be provided one or more tubes without support, sliding on the stamp or stamps. These tubes make it possible to suppress the bending of the patch over a length greater than 50 μm. Under these conditions, only the modes having a knot in correspondence of the tubes are activatable during the striking of the hammer, because in correspondence of a node, the bending of the stamp is minimal.

For such a striking mechanism, two hammers may strike the stamp. The first hammer may be positioned between the fixed recess and the movable recess of the selector element, while the second hammer is between the movable recess and the free end of the stamp. The advantage of this solution is that the sound of the hours and minutes can be obtained by the striking of the same stamp.

From the description that has just been given, several variants of the striking mechanism provided with means for selecting at least one vibratory mode of a stamp or several stamps may be designed by the person skilled in the art without leaving of the scope of the invention defined by the claims. All the solutions described can be applied without major modification in the case of one or more inhomogeneous cross-section stamps. Without major modification, it can be used also one or more two-material stamps or with an outer coating.

Claims (16)

1. Striking mechanism (1), which includes at least one gong (3) fixed to a gong-carrier (2), at least one hammer for striking the gong at predetermined times, and a means of selecting at least one mode of vibration of the gong, the movable or fixed selection means including at least one selector element (4) arranged in contact on one part of the gong and held on a vibration node of one of the modes of vibration of the gong so as to remove completely or partially the other modes of vibration, wherein the selector element (4) is slidably mounted on the gong (3),
   characterized in that the selection means further includes a screw (16) having an end portion which is magnetised (16a) or provided with a magnet (16a) at the opposite end of the screw to the screw head, and a fixed threaded support (17) for receiving the screw, the screw having a longitudinal shaft arranged parallel to the gong, and capable of being moved in the length direction of the gong following a rotation of the screw in the threaded support, and the direction of magnetic polarisation of the magnetised end portion of the screw or of the first magnet (16a) being in the length direction of the gong, and in that the selector element (4) includes a selector permanent magnet (15) of opposite magnetic polarisation to that of the magnetised end portion of the screw or of the permanent magnet of the screw in the length direction of the gong so as to be situated, via an attraction force, next to the magnetised end portion of the screw or of the permanent magnet of the screw, a rotational movement of the screw in the threaded support allowing the selector element (4) to be positioned on a vibration node of a mode of vibration to be selected.
2. Striking mechanism (1), which includes at least one gong (3) fixed to a gong-carrier (2), at least one hammer for striking the gong at predetermined times, and a means of selecting at least one mode of vibration of the gong, the movable or fixed selection means including at least one selector element (4) arranged in contact on one part of the gong and held on a vibration node of one of the modes of vibration of the gong so as to remove completely or partially the other modes of vibration,
   characterized in that the selector element (4) includes an extension (5) on an external portion of the selector element, which is parallel to the gong, and in that the selection means includes a wheel (6) in contact with the extension (5) and rotatably mounted about an axis of rotation (7) in the striking mechanism so as to move the selector element (4) on the gong and to hold the selector element on a vibration node of a mode of vibration of the gong to be selected.
3. Striking mechanism (1) according to any of claims 1 and 2, characterized in that the selector element (4) is capable of being moved on the gong (3) by a means of moving the selection means to position said element on a vibration node of a mode of vibration of the gong to be selected.
4. Striking mechanism (1) according to any of claims 1 and 2, characterized in that the selector element (4) includes a through aperture (4a) allowing said element to be arranged and to slide on the gong.
5. Striking mechanism (1) according to claim 2, characterized in that the extension (5) of the selector element (4) includes a series of teeth (5a) for meshing with teeth (6a) of the toothed wheel (6).
6. Striking mechanism (1) according to claim 2, characterized in that the gong (3) is rectilinear and parallel to the rectilinear extension (5) of the selector element (4), and in that the axis of rotation (7) of the wheel is arranged perpendicular to a length of the gong (3).
7. Striking mechanism (1) according to any of claims 1 and 2, characterized in that the striking mechanism includes two parallel gongs (3, 3') fixed at one end to the gong-carrier (2), and in that the selector element (4) includes two through apertures (4a) allowing said element to be arranged and to slide on the two gongs.
8. Striking mechanism (1) according to claim 7, characterized in that the two gongs are rectilinear, and in that the selector element (4) includes two rings joined by a central piece.
9. Striking mechanism (1) according to claim 8, characterized in that the two parallel rings have an internal diameter equal to or greater than the diameter of a cross-section of each gong (3, 3').
10. Striking mechanism (1) according to claim 8, characterized in that the selector element (4) includes a rectilinear extension (5) on the central piece, which is parallel to the gongs (3, 3'), and in that the selection means includes a wheel (6) in contact with the rectilinear extension (5) and rotatably mounted about an axis of rotation (7) in the striking mechanism so as to move the selector element (4) on the gongs and hold the selector element on a vibration node of a mode of vibration of the gongs to be selected.
11. Striking mechanism (1) according to claim 10, characterized in that the extension (5) of the selector element (4) includes a series of teeth (5a) for meshing with teeth (6a) of the toothed wheel (6).
12. Striking mechanism (1) according to claim 10, wherein the striking mechanism is arranged to be mounted in a watch case, characterized in that the wheel (6) is arranged to be driven in rotation by a winding stem (7) having a drive crown (8).
13. Striking mechanism (1) according to claim 7, when it depends on claim 1, characterized in that the screw has a longitudinal axis arranged parallel to the gongs, and is capable of being moved between the two gongs following a rotation of the screw in the threaded support, and the direction of magnetic polarisation of the magnetised end portion of the screw or of the first magnet (16a) is in the length direction of the gongs, and in that the gong-carrier (2) includes a second permanent magnet (18) of identical magnetic polarisation to that of the magnetised end portion or of the first magnet (16a) of the screw, and in that the selector element (4) includes between the two apertures a selector permanent magnet (15) arranged between the magnetised end portion or the first magnet (16a) of the screw, and the second permanent magnet (18), and having opposite magnetic polarisation to the first and second magnets, the selector element being positioned and held on the gongs by a repulsion force of the first magnet (16a) identical to a repulsion force of the second magnet (18).
14. Striking mechanism (1) according to any of claims 4 and 7, characterized in that the aperture or the apertures (4a) of the selector element (4) include olive jewel holes or micro-balls to come into isolated or lineic contact with the gong or gongs, on which the selector element is mounted.
15. Striking mechanism (1) according to any of claims 1 and 2, characterized in that the selector element (4) is in the form of a clamp for fixedly sandwiching one or more gongs (3, 3') on at least one vibration node of a mode of vibration of the gong or gongs.
16. Striking mechanism (1) according to any of claims 1 and 2, characterized in that the selector element (4) takes the form of a flexible guide member formed of two or more strips of micrometric thickness made of silicon, or silicon oxide, or NiP, each of said strips being fixed to two supports, and deformed in bending to fixedly sandwich one or more gongs (3, 3') on at least one node of a mode of vibration of the gong or gongs.

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