METHOD FOR REDUCING OUT-OF-PLANE VIBRATIONS IN A FLEXIBLE ROTARY RESONATOR MECHANISM

Description

Technical field of the invention

[0001] The invention relates to a method for developing a clockwork resonator mechanism, comprising a structure and an anchor block from which is suspended at least one inertial element, a virtual pivot comprising a plurality of substantially longitudinal elastic blades, each fixed, at a first end to said anchor block, and at a second end to said inertial element.

[0002] The invention relates to the field of watchmaking resonators, and particularly those which include elastic blades acting as means of return for the operation of the oscillator. Technological background

[0003] The torsional stiffness of the suspension is a critical factor for most watch oscillators with at least one balance spring or elastic leaves providing flexible guidance, particularly for resonators with crossed leaves. Shock resistance also depends on this torsional stiffness; indeed, during impacts, the stress on the leaves quickly reaches very high values, thus reducing the travel the component can undergo before failing. Shock absorbers for watch components come in numerous variations. However, their primary purpose is to protect the fragile pivots of the resonator shaft, not the elastic elements, such as the traditional balance spring.

[0004] New mechanism architectures allow for maximizing the quality factor of a resonator through the use of flexible guidance and an anchor escapement with a very small lift angle, as per Swiss patent application CH15442016 filed by ETA Manufacture Horlogère Suisse and its derivatives. The principles of this patent are directly applicable to the present invention, and the resonator can be further improved with regard to its shock sensitivity in certain specific directions. The aim is to protect the blades from breakage in the event of impacts. It has been observed that the shock-absorbing systems currently available for resonators with flexible guidance only protect the blades from impacts in certain directions, not all, or that they have the drawback of allowing slight movement of the virtual pivot's mounting as it oscillates, which should be avoided as much as possible.

[0005] Application CH5182018 or application EP3561609A1 in the name of ETA Manufacture Horlogère Suisse describes a watchmaking resonator mechanism, comprising a structure carrying, by a flexible suspension, an anchor block from which is suspended an inertial element oscillating according to a first degree of freedom in rotation RZ, under the action of restoring forces exerted by a virtual pivot comprising first elastic blades each fixed to said inertial element and said anchor block, the flexible suspension being arranged to allow a certain mobility of the anchor block in all degrees of freedom other than the first degree of freedom in rotation RZ in which only the inertial element is mobile to avoid any disturbance of its oscillation, and the stiffness of the suspension in the first degree of freedom in rotation RZ is much greater than the stiffness of the virtual pivot in this same first degree of freedom in rotation RZ.

[0006] Application CH715526 or application EP3561607 in the name of ETA Manufacture Horlogère Suisse describes a watchmaking resonator mechanism, comprising a structure and an anchor block from which is suspended at least one inertial element arranged to oscillate in a first degree of freedom in rotation RZ around a pivot axis extending in a first direction Z, said inertial element being subjected to restoring forces exerted by a virtual pivot comprising a plurality of substantially longitudinal elastic blades, each fixed, at a first end to said anchor block, and at a second end to said inertial element, each said elastic blade being deformable essentially in a plane XY perpendicular to said first direction Z.

[0007] When the resonator mechanism is operating, the inertial element oscillates around the Z-direction in the XY plane with a reference oscillation frequency. In addition, the inertial element undergoes secondary rotational oscillations around the X-direction on one hand, and around the Y-direction on the other. These secondary oscillations are called "out-of-plane" oscillation modes, meaning they occur outside the XY plane.

[0008] These secondary "out-of-plane" oscillations have a more or less limited effect on the operation of the regulating organ.

[0009] However, if the frequency of these secondary oscillations is a multiple of the reference frequency of the inertial element in the XY plane, the secondary oscillations are larger and disrupt the oscillator's operation. Therefore, care must be taken to ensure that the frequency of the secondary oscillations differs from the reference frequency by a multiple of the reference frequency. Summary of the invention

[0010] The invention aims to improve the resonator mechanism of application CH715526 or application EP3561607 in the name of ETA Manufacture Horlogère Suisse to improve the flexible suspension and avoid the disadvantages mentioned above.

[0011] To this end, the invention relates to a method for developing a clockwork resonator mechanism, comprising a structure and an anchor block from which is suspended at least one inertial element arranged to oscillate in a first degree of freedom in rotation RZ around a pivot axis extending in a first direction Z, said inertial element being subjected to restoring forces exerted by a virtual pivot comprising a plurality of substantially longitudinal elastic blades, each fixed, at a first end to said anchor block, and at a second end to said inertial element, each said elastic blade being deformable essentially in a plane XY perpendicular to said first direction Z, said anchor block being suspended from said structure by a flexible suspension arranged to allow the mobility of said anchor block.

[0012] The invention is remarkable in that the method comprises: a first step of measuring a reference oscillation frequency of the inertial element around the Z direction in the XY plane; a second step of measuring at least one secondary oscillation frequency of the inertial element around the X direction in the YZ plane, or around the Y direction in the XZ plane; a third step of comparing the secondary oscillation frequency to the reference oscillation frequency, to verify that the secondary oscillation frequency has a value substantially different from a multiple of the reference oscillation frequency;and in the case where the secondary oscillation frequency has a value close to or substantially equal to a multiple of the reference oscillation frequency, a fourth step of adapting the flexible suspension or substituting the flexible suspension with another flexible suspension, so as to have a modified flexible suspension configuration so that the secondary oscillation frequency is substantially different from a multiple of the reference oscillation frequency.

[0013] This process allows for the development of a resonator mechanism that controls and prevents significant secondary oscillations around the X and Y directions in planes perpendicular to the XY oscillation plane, such as the XZ or YZ planes. This results in a more precise resonator mechanism.

[0014] Furthermore, modifying or substituting the flexible suspension described in this method has no significant effect on the reference oscillations around the Z direction.

[0015] According to a particular embodiment of the invention, said flexible suspension comprising, between said anchor block and a first intermediate mass, which is fixed to said structure directly or via a flexible plate along said first direction Z, a flexibleally guided transverse translation table comprising at least two transverse flexible blades or rods, preferably straight, extending along said second direction X and symmetrically around a transverse axis intersecting said pivot axis, the first secondary oscillation frequency measured in the second stage is around the Y direction in the XZ plane.

[0016] According to a particular embodiment of the invention, the fourth step consists of substituting or adapting said flexible suspension by modifying the number of transverse flexible blades or rods of the transverse translation table.

[0017] According to a particular embodiment of the invention, the fourth step consists of substituting or adapting said flexible suspension, by modifying the stiffness of the transverse flexible blades or rods of the transverse translation table to be different.

[0018] According to a particular embodiment of the invention, the stiffness is modified by changing the thickness or length of the transverse flexible blades or rods of the transverse translation table.

[0019] According to a particular embodiment of the invention, the fourth step consists of substituting or adapting said flexible suspension by increasing the distance between at least two transverse flexible blades or rods of the transverse translation table, or even between all the transverse flexible blades or rods of the transverse translation table.

[0020] According to a particular embodiment of the invention, said flexible suspension comprising, between said anchor block and a second intermediate mass, a longitudinal translation table with flexible guidance, and comprising at least two longitudinal flexible blades or rods, preferably straight, and extending along said third direction Y and symmetrically around a longitudinal axis crossing said pivot axis, the secondary oscillation frequency measured in the second stage is around the direction X in the YZ plane.

[0021] According to a particular embodiment of the invention, the fourth step consists of substituting or adapting said flexible suspension by modifying the number of longitudinal flexible blades or rods of the longitudinal translation table.

[0022] According to a particular embodiment of the invention, the fourth step consists of substituting or adapting said flexible suspension by modifying the stiffness of the longitudinal flexible blades or rods of the longitudinal translation table.

[0023] According to a particular embodiment of the invention, the stiffness is modified by changing the thickness or length of the longitudinal flexible blades or rods of the longitudinal translation table.

[0024] According to a particular embodiment of the invention, the fourth step consists of substituting or adapting said flexible suspension by increasing the distance between at least two longitudinal flexible blades or rods, or even between all the longitudinal flexible blades or rods of the longitudinal translation table.

[0025] According to a particular embodiment of the invention, the same reference oscillation frequency is maintained in the fourth step as that measured in the first step. Brief description of the figures

[0026] Other features and advantages of the invention will become apparent upon reading the detailed description that follows, with reference to the attached drawings, where: there figure 1 represents, schematically and in perspective, a resonator mechanism with elastic leaves, comprising an inertial mass suspended from an anchoring block by a virtual pivot; the figure 2represents, schematically and in perspective, a mechanism with the different degrees of freedom of the inertial mass that comprise the resonator mechanism of the figure 1 The rocker arm is removed to reveal the flexible guidance system with its two crossed elastic blades in projection, as well as the two translation tables; figure 3 represents a part of the elastic leaf resonator mechanism of the figure 2 , in particular the flexible suspension and the flexible pivot; the figure 4 represents, in schematic form, a diagram of the steps in the process of developing the resonator mechanism according to the invention; the figure 5 represents a first embodiment of a flexible suspension potentially used in the process according to the invention; the figure 6 represents a second embodiment of a flexible suspension potentially used in the process according to the invention; and the figure 7represents a third embodiment of a flexible suspension potentially used in the process according to the invention. Detailed description of the invention

[0027] The invention relates to a method 40 for developing a clockwork resonator mechanism, for example such as that shown in the figures 1 to 3 The development method 40 according to the invention is described in detail below in the description.

[0028] Represented on the figures 1 to 3This embodiment of a clockwork resonator mechanism 100 comprises a structure 1 and an anchor block 30, from which is suspended at least one inertial element 2 arranged to oscillate in a first degree of freedom in rotation RZ about a pivot axis D extending in a first direction Z. The inertial element 2 comprises a balance wheel 20. The balance wheel has a bone-like shape, the balance wheel comprising a straight segment with a bulb at each end. Each bulb can include small weights 29 to adjust the inertia of the inertial element 2. This inertial element 2 is subjected to restoring forces exerted by a virtual pivot 200 comprising a plurality of substantially longitudinal elastic blades 3, each fixed at one end to the anchor block 30, and at one end to the inertial element 2. Each elastic blade 3 is deformable essentially in an XY plane perpendicular to the first direction Z.

[0029] The anchor block 30 is suspended from the structure 1 by a flexible suspension 300, which is arranged to allow the anchor block 30 to move according to five flexible degrees of freedom of the suspension, which are: a first degree of freedom in translation along the first direction Z; a second degree of freedom in translation along a second direction X orthogonal to the first direction Z; a third degree of freedom in translation along a third direction Y orthogonal to the second direction X and to the first direction Z; a second degree of freedom in rotation RX around an axis extending along the second direction X; and a third degree of freedom in rotation RY around an axis extending along the third direction Y.

[0030] The principle is to use the torsional flexibility of a translation table to better manage the torsional stiffness of the suspension. To achieve this, the blades of the XY tables are oriented so that the direction of greatest torsional flexibility points towards the axis of rotation of the resonator. Their torsional flexibility is controlled by bringing the blades closer together.

[0031] Thus, the flexible suspension 300 comprises, between the anchor block 30 and a first intermediate mass 303, which is fixed to the structure 1 directly or via a flexible plate 301 along the first direction Z, a transverse translation table 32 with flexible guidance, and which comprises transverse blades 320 or transverse flexible rods, straight and extending along the second direction X.

[0032] In a particular, non-limiting embodiment, and as illustrated by the figures, the flexible suspension 300 further comprises, between the anchor block 30 and a second intermediate mass 305, a longitudinal translation table 31 with flexible guidance, and which comprises longitudinal blades 310 or longitudinal flexible rods, straight and extending along the third direction Y. And, between the second intermediate mass 305 and the first intermediate mass 303, the transverse translation table 32 with flexible guidance comprises transverse blades 320 or transverse flexible rods, straight and extending along the second direction X.

[0033] More specifically, the longitudinal axis D1 intersects the transverse axis D2, and in particular the longitudinal axis D1, the transverse axis D2, and the pivot axis D are concurrent.

[0034] In a more particular way, the longitudinal translation table 31 and the transverse translation table 32 each comprise at least two flexible blades or rods, each blade or rod being characterized by its thickness along the second direction X when the blade or rod extends along the third direction Y or vice versa, by its height along the first direction Z, and by its length along the direction in which the blade or rod extends, the length being for example at least five times greater than the height, the height being at least as great as the thickness, and more particularly at least five times greater than this thickness, and more particularly still at least seven times greater than this thickness.

[0035] More specifically, the transverse translation table 32 comprises at least two transverse flexible blades or rods, parallel to each other and of the same length. figures 1 to 3illustrate a non-limiting variant with four parallel transverse blades, and, more particularly, each consisting of two half-blades arranged on two superimposed levels, extending one beyond the other along the first Z direction. These half-blades may be either entirely free relative to one another, or joined by bonding or similar means, or by SiO2 growth in the case of a silicon embodiment, or similar. Naturally, the longitudinal translation table 31, when present since it is optional, may follow the same construction principle. The number, arrangement, and cross-section of these blades or rods may vary without departing from the present invention.

[0036] The principle is to use the torsional flexibility of a translation table to better manage the torsional stiffness of the suspension. To achieve this, the blades of the XY tables are oriented so that the direction of greatest torsional flexibility points towards the axis of rotation of the resonator. Their torsional flexibility is controlled by moving the blades closer together or further apart.

[0037] Thus, the flexible suspension 300 comprises, between the anchor block 30 and a first intermediate mass 303, which is fixed to the structure 1 directly or via a flexible plate 301 along the first direction Z, a transverse translation table 32 with flexible guidance, and which comprises transverse blades 320 or transverse flexible rods, straight and extending along the second direction X.

[0038] In a particular, non-limiting embodiment, and as illustrated by the figures, the flexible suspension 300 further comprises, between the anchor block 30 and a second intermediate mass 305, a longitudinal translation table 31 with flexible guidance, and which comprises longitudinal blades 310 or longitudinal flexible rods, straight and extending along the third direction Y. And, between the second intermediate mass 305 and the first intermediate mass 303, the transverse translation table 32 with flexible guidance comprises transverse blades 320 or transverse flexible rods, straight and extending along the second direction X.

[0039] More specifically, the longitudinal axis D1 intersects the transverse axis D2, and in particular the longitudinal axis D1, the transverse axis D2, and the pivot axis D are concurrent.

[0040] In a more particular way, the longitudinal translation table 31 and the transverse translation table 32 each comprise at least two flexible blades or rods, each blade or rod being characterized by its thickness along the second direction X when the blade or rod extends along the third direction Y or vice versa, by its height along the first direction Z, and by its length along the direction in which the blade or rod extends, the length being for example at least five times greater than the height, the height being at least as great as the thickness, and more particularly at least five times greater than this thickness, and more particularly still at least seven times greater than this thickness.

[0041] More specifically, the transverse translation table 32 comprises at least two transverse flexible blades or rods, parallel to each other and of the same length. figures 1 to 3illustrate a non-limiting variant with four parallel transverse blades, and, more particularly, each consisting of two half-blades arranged on two superimposed levels, extending one beyond the other along the first Z direction. These half-blades may be either entirely free relative to one another, or joined by bonding or similar means, or by SiO2 growth in the case of a silicon embodiment, or similar. Naturally, the longitudinal translation table 31, when present since it is optional, may follow the same construction principle. The number, arrangement, and cross-section of these blades or rods may vary without departing from the present invention.

[0042] More specifically, the transverse blades or rods of the transverse translation table 32 have a first plane of symmetry, which is parallel to the transverse axis D2, and which passes through the pivot axis D.

[0043] More specifically, the transverse blades or rods of the transverse translation table 32 have a second plane of symmetry, which is parallel to the transverse axis D2, and orthogonal to the pivot axis D.

[0044] In a variant, not shown in the figures, the longitudinal blades or straight flexible rods 310 are rods with a square or circular cross-section whose height is equal to the thickness.

[0045] In a particular embodiment, the resonator mechanism 100 includes a plate 301, comprising at least one flexible blade 302 extending in a plane perpendicular to the pivot axis D, and fixed to the structure 1 and the first intermediate mass 303, and arranged to allow mobility of the first intermediate mass 303 along the first direction Z. More specifically, the plate 301 comprises at least two coplanar flexible blades 302. Such a plate 301 is, however, optional if the height of the blades of the translation tables XY is small compared to the height of the flexible blades 3, in particular less than one-third of the height of the flexible blades 3.

[0046] In one particular variant, the flexible suspension 300 is a single piece, preferably made of silicon.

[0047] In an advantageous embodiment, the resonator mechanism 100 comprises a single-piece assembly, which includes at least the anchoring block 30, a base of at least one inertial element 2, the flexible pivot 200, the flexible suspension 300, the first intermediate mass 303, and the transverse translation table 32, and includes at least one breakable element 319 arranged to secure the components of the single-piece assembly during their assembly on the structure 1, and whose breaking releases all the moving components of the single-piece assembly.

[0048] More specifically, the monobloc assembly still includes at least the second intermediate mass 305 and the longitudinal translation table 31.

[0049] As explained above, the manufacturing technology allows for two distinct blades within the height of a silicon wafer, which promotes torsional flexibility of the table without compromising its flexibility for translation. The resonator mechanism 100 can thus advantageously comprise at least two superimposed elementary monoblock assemblies, each of which includes one level of the anchoring block 30, and / or a base of at least one inertial element 2, and / or the flexible pivot 200, and / or the flexible suspension 300, and / or the first intermediate mass 303, and / or the transverse translation table 32, and / or a breakable element 319; each elementary monoblock assembly can be joined to at least one other elementary monoblock assembly by bonding or similar means, by mechanical assembly, or by SiO2 growth in the case of a silicon embodiment, or similar.

[0050] More specifically, such an elementary monobloc assembly still includes at least one level of the second intermediate mass 305 and / or the longitudinal translation table 31.

[0051] According to the invention, a method of adjusting 40 of the clockwork resonator mechanism is used to avoid significant secondary oscillations in planes perpendicular to the XY plane.

[0052] Represented on the figure 4 The method 40 comprises a first step 41 of measuring a reference oscillation frequency of the inertial element 2 around the Z direction in the XY plane. To this end, the number of oscillations of the inertial element 2 per second is measured. For example, a measurement method using a laser system, which is known to those skilled in the art, is employed.

[0053] In a second step 42, a secondary oscillation frequency of the inertial element 2 is measured in a plane substantially perpendicular to the XY plane. For example, the oscillation frequency of the inertial element 2 is measured either around the X direction in the YZ plane, or around the Y direction in the XZ plane. Preferably, the secondary oscillation frequency is measured around both the X and Y directions in both the XZ and YZ planes.

[0054] A third step, 43, involves comparing the secondary oscillation frequency(ies) to the reference oscillation frequency. Specifically, it is checked whether the secondary oscillation frequency is significantly different from the reference oscillation frequency by a multiple of the reference oscillation frequency. If the secondary oscillation frequency is significantly different from the reference oscillation frequency by a multiple of the reference oscillation frequency, the flexible suspension 300 does not require modification or replacement.

[0055] On the other hand, if the secondary oscillation frequency has a value close to or substantially equal to a multiple of the reference oscillation frequency, the process 40 includes a fourth step 44. The fourth step 44 consists either of adapting the flexible suspension 300, or of substituting the flexible suspension 300 with another flexible suspension, so as to have a geometric configuration different from the flexible suspension 300.

[0056] Thanks to this new geometry, the secondary oscillation frequency changes, so that one can choose a secondary oscillation frequency that is substantially different from a multiple of the reference oscillation frequency.

[0057] Preferably, the same reference oscillation frequency is maintained in the fourth step as that measured in the first step. In other words, only the secondary oscillation frequency or frequencies are modified by changing or substituting the flexible suspension, but the reference frequency remains unchanged.

[0058] Preferably, in the event of a substitution, the flexible suspension 300 is substituted with another flexible suspension whose oscillatory properties are already known, in particular the secondary oscillation frequency or frequencies.

[0059] Thus, the method 40 may include a preliminary step 39 of measuring the reference frequency and the secondary oscillation frequency(ies) of a plurality of flexible suspensions having different configurations or geometries. The flexible suspensions are, for example, classified according to their oscillatory properties, in particular according to their secondary oscillation frequencies.

[0060] The method 40 may further include a fifth verification step 45 in which the secondary oscillation frequency is measured after the adaptation or substitution of the flexible suspension 300 to verify that a value other than a multiple of the reference oscillation frequency is obtained. Thus, if necessary, the flexible suspension 300 can again be modified or substituted if the measured secondary oscillation frequency is not satisfactory.

[0061] In the adaptation variant of the flexible suspension 300, the geometry of the flexible suspension 300 is modified. For example, by acting on the flexible blades or flexible rods.

[0062] In a first embodiment, the fourth step consists of substituting or adapting said flexible suspension 300 by modifying the number of transverse 320 and / or longitudinal 310 flexible blades or rods. In each translation table 31, 32, there may be more or fewer flexible blades or rods 310, 320 than the original configuration of the flexible suspension 300.

[0063] For the case where the secondary oscillation frequency is in the XZ plane, the number of transverse flexible blades or rods 320 of the transverse translation table 32 is modified. For the case where the secondary oscillation frequency is in the YZ plane, the number of longitudinal flexible blades or rods 310 of the longitudinal translation table 31 is modified.

[0064] There figure 5 The diagram shows a flexible suspension 300 equipped with a longitudinal translation table 31 comprising six longitudinal flexible blades or rods 310 between the anchor block 30 and the second intermediate mass 305. The flexible suspension 300 is also equipped with a transverse translation table 32 comprising six transverse flexible blades or rods 320 between the first intermediate mass 303 and the second intermediate mass 305. Thus, each translation table 31, 32 comprises one or two additional flexible blades or rods 310, 320 compared to the original flexible suspension of the figure 3 .

[0065] A second embodiment of the fourth step 44 consists of substituting or adapting said flexible suspension 300 by modifying the stiffness of the longitudinal flexible blades or rods 310 or transverse flexible 320 of the flexible suspension 300.

[0066] For example, the thickness of the longitudinal 310 or transverse 320 flexible blades or rods can be adjusted, or the length of the longitudinal 310 or transverse 320 flexible blades or rods can be adjusted to modify their stiffness. On the figure 6 The 310, 320 flexible blades or rods of the 300 flexible suspension are thicker than the flex blades of the original flexible suspension.

[0067] In a third embodiment, the fourth step 44 consists of increasing the distance between at least two longitudinal 310 and / or transverse 320 flexible blades or rods of the longitudinal 31 and / or transverse 32 translation table of the flexible suspension 300. By moving two flexible blades or rods 310, 320 apart, the secondary oscillation frequencies are modified.

[0068] For example, on the figure 7The flexible suspension 300 comprises, for each longitudinal translation table 31 or transverse translation table 32, two groups of flexible blades or rods 310, 320, separated from each other. The first three blades or rods have a spacing of the same initial distance between them, and the last three blades have a spacing of the same initial distance between them.

[0069] To separate the two groups of blades, the third and fourth flexible blades are moved apart by a distance of two, respectively. d X and / or dy, which is greater than the first distance. Other flexible suspension 300 configurations are of course possible. For example, the distances between all the leaves are equal, but with a greater or lesser distance than the original configuration.

[0070] Regardless of the embodiment, through these adaptations or substitutions, the secondary oscillation frequencies are modified so that they are far from the value of a multiple of the reference oscillation frequency of the inertial element in the XY plane.

[0071] Naturally, the invention is not limited to the embodiments described with reference to the figures and variants could be envisaged without departing from the scope of the invention.

Claims

1. Method (40) of setting up a resonator mechanism (100) for a timepiece, comprising a structure (1) and an anchoring block (30) from which at least one inertial element (2) is suspended arranged to oscillate with a first degree of freedom in rotation RZ about a pivot axis (D) extending in a first direction Z, said inertial element (2) being subjected to return forces exerted by a flexible pivot (200) comprising a plurality of substantially longitudinal resilient blades (3), each fixed at a first end to said flexible pivot (200), each fixed at a first end to said anchoring block (30), and at a second end to said inertial element (2), each said elastic blade (3) being deformable essentially in a plane XY perpendicular to said first direction Z, said anchoring block (30) being suspended from said structure (1) by a flexible suspension (300) arranged to allow mobility of said anchoring block (30), characterised in that it comprises: - a first step (41) of measuring a reference oscillation frequency of the inertial element (2) about the Z direction in the XY plane; - a second step (42) of measuring at least one secondary oscillation frequency of the inertial element (2) about the X direction in the YZ plane or about the Y direction in the XZ plane; - a third step (43) of comparing the secondary oscillation frequency with the reference oscillation frequency, to verify that the secondary oscillation frequency has a value substantially different from a multiple of the reference oscillation frequency; and - in the case where the secondary oscillation frequency has a value close to or substantially equal to a multiple of the reference oscillation frequency, a fourth step (44) of adapting flexible suspension (300) or substituting flexible suspension (300) with another flexible suspension, so as to have a configuration of flexible suspension (300) modified such that the secondary oscillation frequency is substantially different from a multiple of the reference oscillation frequency.

2. A method of setting up according to claim 1, characterised in that said flexible suspension (300) comprising, between said anchoring block (30) and a first intermediate mass (303), which is fixed to said structure (1) directly or by means of a plate (301) flexible in said first direction Z, a transverse translation table (32) with flexible guidance and comprising at least two transverse flexible blades or rods (320), preferably rectilinear, and extending in said second direction X and symmetrically about a transverse axis (D2) crossing said pivot axis (D), the first secondary oscillation frequency measured in the second step (42) is about the direction Y in the plane XZ.

3. The tuning method according to claim 2, wherein the fourth step (44) consists in substituting or adapting said flexible suspension (300) by modifying the number of transverse flexible blades or rods (320) of the transverse translation table (32).

4. The tuning method according to claim 2, characterised in that the fourth step (44) consists in substituting or adapting said flexible suspension (300), by modifying the stiffness of the transverse flexible blades or rods (320) of the transverse translation table (32).

5. A setting method according to claim 4, characterised in that the stiffness of the transverse flexible blades or rods (320) is modified by changing the thickness or length of the transverse flexible blades or rods (320) of the transverse translation table (32).

6. A setting method according to claim 2, characterised in that the fourth step (44) consists in substituting or adapting said flexible suspension (300) by increasing the distance (dy) between at least two transverse flexible blades or rods (320) of the transverse translation table (32), or even between all transverse flexible blades or rods (320) of the transverse translation table (32).

7. The tuning method according to any one of the preceding claims, characterised in that said flexible suspension (300) comprising, between said anchoring block (30) and a second intermediate mass (305), a longitudinal translation table (31) with flexible guidance and comprising at least two longitudinal flexible blades or rods (310), preferably rectilinear, and extending in said third direction Y and symmetrically about a longitudinal axis (D1) crossing said pivot axis (D), the secondary oscillation frequency measured in the second step (42) is about the direction X in the plane YZ.

8. The tuning method according to claim 7, wherein the fourth step (44) consists in substituting or adapting said flexible suspension (300) by modifying the number of longitudinal flexible blades or rods (310) of the longitudinal translation table (31).

9. The tuning method according to claim 7, wherein the fourth step (44) consists in substituting or adapting said flexible suspension (300) by modifying the stiffness of the longitudinal flexible blades or rods (310) of the longitudinal translation table (31).

10. A setting method according to claim 9, characterised in that the stiffness of the longitudinal flexible blades or rods (310) is modified by changing the thickness or length of the longitudinal flexible blades or rods (310) of the longitudinal translation table (31).

11. A setting method according to claim 7, characterised in that the fourth step (44) consists in substituting or adapting said flexible suspension (300) by increasing the distance (dX) between at least two longitudinal flexible blades or rods (310), or even between all the longitudinal flexible blades or rods (310) of the longitudinal translation table (31).

12. The tuning method according to any one of the preceding claims, characterised in that the same reference oscillation frequency is maintained in the fourth step (44) as that measured in the first step (41).