Micromechanical actuation system with flexible guide for watchmaking

Abstract

To provide a high-precision actuation system for a horological movement that allows an actuator to assume multiple precise positions.SOLUTION: An actuation system for a horological movement is configured to displace, at least in part, a part between multiple positions, and includes a micromechanical actuator 30 intended to be engaged with the part. The micromechanical actuator 30 includes: a part 33 intended to be mounted such that it remains stationary with respect to a plate of the horological movement; and a part 37 that is movable with respect to the stationary part 33. The actuator 30 includes a spring part 35 connecting the movable part 37 to the stationary part 33. The spring part 35 carries the movable part 37. The actuation system further includes setting means cooperating with the actuator 30 so as to be able to displace the movable part (37) of the actuator (30) between multiple positions. The spring part 35 includes a guide with multiple flexible blades.SELECTED DRAWING: Figure 7

Description

[Technical field]

[0001] The present invention relates to the field of mechanical watchmaking.

[0002] The invention relates in particular to a micromechanical actuation system with flexible guides for watchmaking. [Background technology]

[0003] In the technical field of micromechanical devices, micromechanical actuation systems are used to transmit motion between two elements of a micromechanical device.

[0004] For example, in the field of watchmaking, push buttons, levers or rockers are known for triggering or activating certain timekeeping modules of the movement, which are placed in a mechanical movement and allow the transmission of a movement or force between two parts of the movement.

[0005] Such an actuation system in particular comprises an actuator engaged with a part to be actuated, which may be a gear wheel or a setting element.

[0006] Such actuators typically need to be sufficiently precise for a given application, where the displacement of the actuator needs to be very precisely controlled.

[0007] Furthermore, to obtain the desired precision and to prevent hysteresis phenomena, play between the parts of the actuator must be avoided. In particular, some actuation systems include several parts connected by contacts.

[0008] Some actuators include a stationary part mounted on a support, for example a pivot mounted on a plate, and a part that can move relative to the stationary part, for example a lever that pivots about the pivot. To move the moving part while avoiding play between the parts, a spring exerts a return force on the moving part that holds or pushes it in place. In the case of a lever, the spring holds the lever in a reference position.

[0009] To displace the lever, the support piece pushes the lever from the reference position to the module operating position. When the support piece is pulled out, the lever is returned to the initial position by the action of the spring.

[0010] However, for certain functions, especially setting devices where the actuator needs to assume multiple precise positions, these actuation systems may not be accurate and sensitive enough. Summary of the Invention

[0011] SUMMARY OF THE PRESENT EMBODIMENT The object of the present invention is to overcome some or all of the above mentioned drawbacks by providing a high precision actuation system for a clock movement.

[0012] To this end, the invention relates to an actuation system for a clock movement, the actuation system being at least in part configured to be able to displace a part between a number of positions, the actuation system comprising a micromechanical actuator intended to engage with said part, the micromechanical actuator comprising a part intended to remain stationary, for example mounted relative to a plate of the clock movement, and a part movable relative to said stationary part, the actuator comprising a spring part connecting the movable part to the stationary part, the spring part carrying the movable part, the actuation system further comprising setting means cooperating with the actuator to be able to displace the movable part of the actuator between a number of positions.

[0013] The invention is characterized in that the spring portion includes a guide having a flexible blade.

[0014] That is, the present invention provides an actuation system having a high precision actuator capable of multiple closely spaced positions, and further, the spring portion of the actuation system avoids problems associated with play.

[0015] According to a particular embodiment of the invention, the flexible blade guide includes at least two translation stages arranged in series, with a first translation stage connected to a stationary part and a final translation stage connected to a movable part.

[0016] According to a particular embodiment of the invention, each translation stage includes a pair of substantially parallel flexible blades and a rigid section on which the pair of flexible blades are mounted.

[0017] According to a particular embodiment of the invention, two successive translation stages are arranged in series with respect to each other.

[0018] According to a particular embodiment of the invention, there is an even number of translation stages.

[0019] According to a particular embodiment of the invention, the rigid section is made to a length such that adjacent translation stages can be associated with it.

[0020] According to a particular embodiment of the invention, at least the spring portion is defined substantially in one plane, preferably either the moving portion or the stationary portion, so as to be substantially flat.

[0021] According to a particular embodiment of the invention, at least a second translation stage is arranged on a first side of the first translation stage, on an opposite side of the movable part relative to the first translation stage.

[0022] According to a particular embodiment of the invention, at least the final translation stage is arranged on a second side of the first translation stage facing towards the movable part.

[0023] According to a particular embodiment of the invention, a rigid section of a translation stage arranged on a first side furthest from the first translation stage extends to a translation stage arranged on a second side to form a peripheral side of the spring portion.

[0024] According to a particular embodiment of the invention, each rigid section of a translation stage extends beyond a pair of flexible blades of that translation stage.

[0025] According to a particular embodiment of the invention, the spring portion is arranged below the stationary portion.

[0026] According to a particular embodiment of the invention, the flexible blades of the translation stage of the spring portion are substantially parallel when the actuator is in the rest position.

[0027] According to a particular embodiment of the invention, the movable part comprises a hook.

[0028] According to a particular embodiment of the invention, the actuator is made in one piece, for example obtained using a LIGA or DRIE type process.

[0029] According to a particular embodiment of the invention, the movable part has the shape of an elbow formed by a first segment aligned perpendicular to the rigid section of the final translation stage and a second segment at a right angle to the first segment.

[0030] The invention further relates to a clock movement including such an actuation system.

[0031] The invention further relates to a timepiece, such as a wristwatch, comprising such a timepiece movement. [Brief description of the drawings]

[0032] The advantages and features of the present invention will become apparent from the detailed description of some embodiments, given by way of non-limiting example only, with reference to the accompanying drawings, in which:

[0033] [Figure 1] 1 shows a schematic perspective view of an adjustment member including an actuation system according to an embodiment of the present invention, the adjustment member being arranged in a timepiece movement; [Diagram 2] FIG. 2 shows a perspective view of a portion of the adjustment member shown in FIG. 1, diagrammatically without the balance bridge; [Diagram 3] FIG. 2 shows a schematic top view of a portion of the adjustment member shown in FIG. 1 without the balance bridge and without the bearings. [Figure 4] FIG. 2 shows a schematic top view of the balance spring of the adjustment member shown in FIG. [Diagram 5] 2 shows a schematic side view of an actuator of the actuation system of the adjustment member in FIG. 1; [Figure 6] FIG. 6 shows a schematic side view of an actuator of the actuation system in FIG. 5 mounted on a balance bridge. [Figure 7] 13A and 13B are schematic diagrams of an enlarged perspective view of an actuator and an offset lever of an actuation system of an adjustment member; [Figure 8] 2 shows a schematic bottom view of the adjustment member in FIG. 1; [Figure 9] 1 shows a schematic diagram of an enlarged perspective view of the actuator and offset lever of the actuation system of the adjustment member in a first position. [Figure 10] 13A and 13B are schematic diagrams of an enlarged perspective view of the actuator and offset lever of the actuation system of the adjustment member in a second position. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0034] In the following description, the subject of the invention, which is an actuation system, is adapted to actuate the means for adjusting the speed of a timepiece adjusting member, however, such an actuation system may also be used for other applications in timepiece movements and is by no means limited to application in adjusting members.

[0035] 1 to 3 show diagrammatically an embodiment of an adjustment member 1 intended to be arranged in a timepiece movement comprising a plate (not shown in the drawings) provided with a recess, such a movement being arranged in a timepiece, for example a wristwatch.

[0036] The adjustment member 1 comprises an inertial mass, in this case an annular balance 23, a hairspring 25 as an elastic return element for the inertial mass, arranged to oscillate the inertial mass, a balance staff 24 and a balance bridge 22. These elements are stacked from bottom to top in the following order: balance 23, hairspring 25 and balance bridge 22.

[0037] The balance staff 24 passes through the balance, the hairspring 25 and the center of the balance bridge 22. The balance staff 24 is supported by two shock absorbing bearings 28 arranged at both ends of the balance staff 24. The first bearing is arranged below the balance bridge 22 and the second bearing 28 is arranged inside the balance bridge 22. The balance bridge 22 has a through hole, and the second bearing 28 is supported inside the through hole.

[0038] As shown in Figures 3 and 4, the hairspring 25 preferably extends substantially in one plane. The hairspring 25 comprises a flexible ribbon 2 wound around itself with a number of turns, the ribbon 2 having a predefined stiffness. An inner end 9 of the ribbon 2 is integral with or assembled with a rigid support 3, typically called a collet. The rigid support 3 is substantially triangular in shape and is screwed around the staff of the balance 24.

[0039] The balance spring 25 further comprises means for adjusting its stiffness, which can for example be actuated by the user, in particular when the adjustment member is mounted on a plate of the timepiece movement.

[0040] The adjustment means comprises a flexible element 5 arranged in series with, i.e. from, and preferably as an extension of, the ribbon 2, which connects the outer end 4 of the ribbon 2 to the rigid support 17. The flexible element 5 is integral with the outer end 4 of the ribbon 2. The flexible element 5 is a distinct element from the ribbon 2.

[0041] The flexible element 5 adds additional stiffness to that of the ribbon 2. The flexible element 5 is preferably stiffer than the ribbon 2. In this case, the flexible element 5 is arranged as an extension of the ribbon 2. Preferably, the adjustment means and the ribbon 2 are integral or may be made from the same material, e.g. silicone.

[0042] The flexible element 5 of the hairspring 25 comprises a first flexible blade 19 and a movable semi-rigid portion 18, which extends from the outer end of the ribbon 2 and is connected to the first flexible blade 19, preferably on the same side of the rigid portion 18. The first flexible blade 19 is also connected to the rigid support 17.

[0043] The rigid support 17 is L-shaped, with a first leg 46 of the L acting as a connection with the first flexible blade 19 and a second leg 47 of the L facing away from the first flexible blade 19 for assembly with the clock movement.

[0044] The means for adjusting the hairspring 25 further comprise compressive stress means 6 which exert a variable force or torque on the flexible element 5. In this way the stiffness of the hairspring can be adjusted. The torque or force is continuously adjustable thanks to the compressive stress means 6; in other words the torque or force is not limited to discrete values. The stiffness of the flexible element 5 can thus be adjusted very precisely.

[0045] The compressive stress means 6 comprises a secondary flexible blade 21 which is arranged on the opposite side to the rigid portion 18 in the extension of the first flexible blade 19.

[0046] The other end of the secondary flexible blade 21 is connected to a curved lever 14 that extends around the ribbon 2. In addition to the secondary flexible blade 21, the lever 14 is also connected to a semi-rigid structure 27 that is attached to the rigid support 17. The semi-rigid structure 27 has a portion that deforms when the lever 14 is actuated by a force or torque.

[0047] This force or torque is exerted on the free end 15 of the lever 14. In this way, the lever 14 of the compression stress means 6 transmits the force or torque to the flexible element 5 via the secondary flexible blade 21 and the semi-rigid structure 27 in order to modify the stiffness of the balance spring 25.

[0048] In order to be able to exert a variable force or torque on the balance spring 25, the adjustment member comprises a particular actuation system 20 according to the invention.

[0049] The actuation system 20 is at least partially configured to be able to displace a part, which in this embodiment is the lever 14 of the compressive stress means 6, between a number of positions.

[0050] In the embodiment shown in Figures 1 to 3, the adjustment member 1 comprises a stud holder 31 provided with a suspension stud 34. The stud holder 31 is mechanically connected to the flexible element 5 but does not block the ribbon 2. The stud holder 31 surrounds the second bearing 28. For this purpose, the stud holder 31 comprises a central ring 38 arranged around the second bearing 28. This central ring 38 rests on the balance bridge 22.

[0051] The stud 34 cooperates with a second leg 47 of the rigid support 17. In this way, the compressive stress means 6 and the flexible element 5 are supported by and suspended from the stud holder 31.

[0052] Furthermore, the stud 34 is rigidly attached to the rigid support 17. In other words, the stud 34 is integrated into the rigid support 17. The stud 34 and the hairspring 25 are assembled, for example, by gluing, brazing, welding, deformation of a metallic glass or mechanical fastening.

[0053] The stud 34 is movable relative to the balance bridge. To this end, the stud holder 31 is rotatable about the second bearing 28 relative to the balance bridge 22. The stud holder 34 can be displaced over an angular range of, for example, 20° or better 10°.

[0054] By displacing the pin 34 relative to the balance bridge 22 the pulsation of the adjustment member 1 can be adjusted.

[0055] The actuation system 20 further comprises an actuator 30 configured to actuate the lever 14. The actuator 30 is mechanically connected to the compressive stress means 6. The actuator 30 is configured to provide at least a portion thereof, preferably a substantially linear displacement, or more suitably a straight-line displacement, to actuate the compressive stress means 6.

[0056] In other words, at least a part of the actuator 30 moves substantially along a straight line, unlike the stud holder 31 which rotates, for example, by rotating about an axis. In this way, at least a part of the actuator 30 moves towards or away from the balance spring 25 in a direction oriented substantially towards the balance spring.

[0057] Preferably, the direction of displacement of the actuator 30 is substantially radial with respect to the balance 23 and the hairspring 25. In this way, the straight line along which the actuator 30 moves is directed towards the centre of the balance 23 and the hairspring 25. This also makes the speed setting independent of the pulsation setting.

[0058] The actuator 30 is eccentric with respect to the adjustment member, i.e. it is mounted at a distance from the centre of the adjustment member 1 and is only connected to the lever 14 of the adjustment means. The actuator 30 is therefore not directly mounted to the adjustment member 1, e.g. as a stud holder on the bearing 28 of the adjustment member 1.

[0059] In this embodiment, the actuator 30 is mounted to the balance bridge 22. Preferably, the actuator 30 is mounted substantially perpendicular to the plane of the balance bridge 22. In particular, the actuator 30 is assembled to an edge of the balance bridge 22.

[0060] 5 and 6, the actuator 30 comprises in detail a part 33 intended to be mounted stationary, for example relative to a plate of a watch movement, a part 37 movable relative to the balance bridge 22 and connected to the lever 14, and a spring part 35 joining the movable part 37 to the stationary part 33. The stationary part 33 is in this case mounted to the balance bridge 22 and therefore stationary relative to it. The stationary part 33 and the movable part 37 are preferably rigid. The stationary part 33, the spring part 35 and the movable part 37 are arranged in the same plane. The actuator 30 is therefore generally flat and extends substantially in one plane. The actuator 30 is preferably made in one piece. The actuator 30 is obtained, for example, by a LIGA type lithography process or by a DRIE type deep reactive ion etching process.

[0061] To actuate the lever 14, the actuator 30 includes a hook 39 that is engaged with the lever 14. The hook 39 is mounted on the movable part 37. The hook 39 at least partially surrounds the lever 14, but may close around the lever 14.

[0062] The radial displacement of the movable part 37 of the actuator 30 pulls or pushes the lever 14 radially against the balance spring 25. This causes the displacement of the lever 14 to exert a greater or lesser force or torque on the flexible element 5, thereby changing the stiffness of the flexible element 5 and, as a result, the overall stiffness of the balance spring 25. The actuation system 20 thus allows the speed of the adjustment member 1 to be adjusted.

[0063] Here, the stationary part 33 has a substantially square shape and comprises at least one mounting notch 41, preferably two mounting notches 41, 42 for receiving pads 43, 44 respectively extending from the balance bridge 22. The mounting notches 41, 42 are, for example, arranged on two diagonally opposite sides of the stationary part 33.

[0064] Each notch 41, 42 is provided with a flexible tongue 48, 49 arranged in the notch 41, 42. The first notch 41 is open at its side so that it can slide laterally around the first pad 43. The second notch 42 is closed and can receive the second pad 44 by inserting it into the second notch 42. The flexible tongues 48, 49 deform when the pad 43, 44 enters the notch 41, 42 and act as support means to hold the pad 43, 44 in the notch 41, 42. Furthermore, the flexible tongues 48, 49 make it possible to improve the positioning accuracy by overcoming play when positioning the pads 43, 44 in the notches 41, 42, preferably in the same direction.

[0065] As shown in the drawings, the actuator 30 is mounted to the balance bridge 22 such that it is substantially perpendicular to the plates and balance bridge 22. The actuator 30 is therefore mounted to an edge of the balance bridge 22.

[0066] The spring portion 35 is arranged below the stationary portion 33 and therefore extends below the level of the balance bridge 22 .

[0067] According to the present invention, the spring portion 35 comprises a flexible guide, in this case including a number of translation stages 51, 52, 53, 54 having a number of flexible blades arranged in series, one after the other, which are defined as being in series because the displacements of each translation stage are at least partially cumulative.

[0068] Each translation stage 51, 52, 53, 54 includes a pair of substantially parallel flexible blades 61, 62, 63, 64 and a rigid section 56, 57, 58, 59 on which the pair of flexible blades 61, 62, 63, 64 are mounted.

[0069] The first translation stage 51 is arranged below the stationary portion 33 and has a first rigid section 56 of a length associated with a second translation stage 52 arranged in series with the first translation stage 51. In this manner, the second pair of flexible blades 52 are substantially parallel to the first pair of flexible blades 51. The second rigid section 57 is substantially parallel to the first rigid section but offset by half the length of the first rigid section 56.

[0070] The second rigid section 57 is also of a length such that it associates a third translation stage 53 arranged in series with the second translation stage 52 such that it is substantially parallel to the first translation stage 51. The third pair of flexible blades 63 are substantially parallel to the first pair of flexible blades 61 and the second pair of flexible blades 62.

[0071] The actuator 30 includes a fourth translation stage 54 arranged on the opposite side of the first translation stage 5 from the second translation stage 52 and the third translation stage 53. The fourth translation stage 54 is arranged in series with the third translation stage 53.

[0072] In this manner, the fourth pair of flexible blades 64 are substantially parallel to the other pairs of flexible blades, and the fourth section 59 is aligned in substantially the same direction as the second section 57 .

[0073] The third translation stage 53 and the fourth translation stage 54 are connected by an arm 55. The arm 55 extends from the third section 58 and passes below the first rigid section 56 of the first translation stage 51.

[0074] This arrangement of translation stages 51 , 52 , 53 and 54 enables the moveable portion 37 to be displaced in a substantially linear, preferably rectangular, manner while maintaining a compact actuator 30 .

[0075] Preferably, the actuator 30 includes an even number of translation stages, since two translation stages arranged in series can mutually compensate for the vertical deviation of the hook 39 caused by each of them, thus keeping the hook 39 at substantially the same height during movement.

[0076] The movable part 37 extends from the fourth section 59. The movable part 37 is preferably rigid. In this case, the movable part 37 has the shape of an elbow formed by a first segment 66 arranged perpendicular to the fourth section 59 and a second segment 67 at a right angle to the first segment 66.

[0077] The hook 39 of the actuator 30 is located at the end of the second segment 67. At the free end of the first segment 66, a bulge 68 serves as a support for the movement of the mobile part 37.

[0078] By pressing more or less hard on the bulge 68 , the mobile part 37 moves more or less close to the stationary part 33 thanks to the deformation of the translation stages 51 , 52 , 53 , 54 of the spring part 35 .

[0079] In this way, the hook 39 pulls the lever 14 more or less tightly, activating a means for adjusting the stiffness of the flexible element 5 .

[0080] The direction of displacement of the movable part 39 of the actuator 30 and the direction of displacement of the lever 14 are substantially perpendicular to the direction of the lever 14 .

[0081] Furthermore, the lever 14 is preferably slidably movable on the hook 39 when performing the angular displacement. To this end, the lever 14 comprises a free end 15 cooperating with the hook 39.

[0082] For example, in order to adjust the pulsation of the adjustment member 1, the stud holder 31 must be rotatable, so that the balance spring 25 rotates together with the stud holder 31 and the free end 15 of the lever 14 slides on the hook 39.

[0083] Thanks to such an actuation system 20, the pulsation can be adjusted without having to modify the position of the actuator 30, in particular its position relative to the plate of the movement. The mechanical link between the actuator 30 and the lever 14 is maintained regardless of the position of the lever 14 relative to the actuator 30.

[0084] That is, the actuation system 20 allows the speed and pulsation to be adjusted independently of each other while maintaining a constant, pre-determined position of the actuator in the movement, for example in relation to the plate and balance bridge 22.

[0085] The actuation system 20 further includes adjustment means cooperating with the actuator 30 to enable the displacement of a moveable part 37 of the actuator 30 .

[0086] As shown in Figures 7 to 10, the adjustment means comprises a pivoting control lever 45 arranged to displace the movable part 37 of the actuator 30. The control lever 45 is preferably arranged in a plane substantially perpendicular to the plane of the bulge 68 of the movable part 37 and in contact with this bulge 68.

[0087] The control lever 45 has a pivot arm 69 and a support arm 71 connected to a hub 72 of the pivot control lever 45 .

[0088] The support arm 71 cooperates with the movable part 37 of the actuator 30 to mechanically displace it by contact. The support arm 71 pushes against the bulge 68 of the movable part 37, moving it to a greater or lesser extent. That is, the hook 39 pulls to a greater or lesser extent the lever 14 of the balance spring 25. The control lever 45 is arranged to pivot in a plane substantially perpendicular to the plane of the actuator 30.

[0089] The control lever 45 is arranged to be mounted to a plate of the movement via a hub 72. This hub 72 can rotate about a screw body 73, which is mounted to the plate.

[0090] That is, by rotating the control lever 45 about the screw body 73, the movable part 37 moves towards or away from the stationary part 33 by deforming the spring part 35 of the actuator 30 to a greater or lesser extent, thereby modifying the position of the lever 14.

[0091] The adjustment means further includes a control screw 70 mechanically connected to the pivot arm 69 for controlling the pivoting of the control lever 45. The axis of the control screw 70 is aligned in the plane of the control lever 45 in the direction of the pivot arm 69.

[0092] That is, by screwing or unscrewing the control screw 70 , the control lever 45 and the actuator 30 are actuated to move the hook 39 and thus the lever 14 of the compressive stress means 6 .

[0093] The return force of the spring portion 35 of the actuator 30 presses the control lever 45 against the control screw 70. In this way, the pivot arm 69 of the control lever 45 is held against the control screw 70.

[0094] In Figure 9, the control screw 70, the control lever 45, the movable part 37 of the actuator 30 and the lever 15 are all in a first position, with the hook 39 pulling lightly on the lever 15. The dotted lines show the control lever 45, the movable part 37 of the actuator 30 and the lever 15 in a second position corresponding to the positions in Figure 10.

[0095] 10, the control screw 70, the control lever 45, the movable part 37 of the actuator 30 and the lever 15 are all in their second positions and the hook 39 pulls the lever 15 harder than in FIG.

[0096] In the second position, the control screw 70 presses against the pivot arm 69 of the control lever 45, so that the support arm 71 in contact with the bulge 68 in turn presses the movable part 37 of the actuator 30 towards the stationary part 33 due to the deformation of the spring part 35. In this way, the hook 39 pulls on the lever 14, which causes a centrifugal displacement.

[0097] In the deformed configuration of spring portion 35, the flexible blades of first translation stage 51 and third translation stage 53 deform in the same first direction, while the flexible blades of second translation stage 52 and fourth translation stage 54 deform in the same second direction, where the second direction is opposite to the first direction.

[0098] A spring 74 is arranged around the screw body 73 to bias the actuator 30 against the balance bridge 22 so that it does not become dislodged.

[0099] The spring 74 clamps the screw body 73. The spring 74 is U-shaped and surrounds the screw body 73, where one leg of the U extends from the stationary part 33 of the actuator 30 to which it is attached.

[0100] It goes without saying that the invention is not limited to the embodiment of the adjustment member described with reference to the drawings, but alternatives are possible without departing from the scope of the invention.

Claims

1. 1. An actuation system for a timepiece movement, comprising: said actuation system (20) is at least partially configured to be able to displace a part between a plurality of positions, said actuation system (20) comprising a micromechanical actuator (30) intended to engage with said part, said micromechanical actuator (30) comprising a part (33) intended to be mounted to remain stationary, for example relative to a plate of said timepiece movement, and a part (37) movable relative to said stationary part (33), said actuator (30) comprising a spring part (35) connecting said movable part (37) to said stationary part (33), said spring part (35) carrying said movable part (37), said actuation system further comprising setting means cooperating with said actuator (30) to be able to displace the movable part (37) of said actuator (30) between a plurality of positions, An actuation system characterized in that said spring portion (35) includes a guide having a plurality of flexible blades.

2. 2. The actuation system of claim 1, wherein the flexible blade guide comprises at least two translation stages (51, 52, 53, 54) arranged in series, a first translation stage (51) being connected to the stationary part (33) and a final translation stage (54) being connected to the movable part (37).

3. 3. The actuation system of claim 2, wherein each translation stage (51, 52, 53, 54) comprises a pair of substantially parallel flexible blades (61, 62, 63, 64) and a rigid section (56, 57, 58, 59) on which the pair of flexible blades (61, 62, 63, 64) are mounted.

4. 3. An actuation system according to claim 2, characterized in that two successive translation stages (51, 52, 53, 54) are arranged in series with respect to each other.

5. 3. An actuation system according to claim 2, characterised in that it comprises an even number of translation stages (51, 52, 53, 54).

6. 3. An actuation system according to claim 2, characterized in that the rigid sections (56, 57, 58, 59) are of a length such that adjacent translation stages (51, 52, 53, 54) can be associated therewith.

7. 3. An actuation system according to claim 2, characterized in that at least the spring part (35) is defined in a substantially planar manner so as to be substantially flat, preferably also with respect to the movable part (37) or even with respect to the stationary part (33).

8. 3. An actuation system according to claim 2, characterized in that at least a second translation stage (52) is arranged on a first side of the first translation stage (51) opposite the movable part (37).

9. 3. An actuation system according to claim 2, characterized in that at least the final translation stage (54) is arranged on a second side of the first translation stage (51) facing towards the movable part (37).

10. 3. The actuation system according to claim 2, characterized in that a rigid section (55) of the translation stage (53) arranged on the first side furthest from the first translation stage (51) extends to a translation stage (54) arranged on the second side to form a peripheral side of the spring portion (35).

11. 3. The actuation system of claim 2, wherein each rigid section (56, 57, 58, 59) of a translation stage (51, 52, 53, 54) extends beyond the pair of flexible blades of said translation stage (51, 52, 53, 54).

12. 3. An actuation system according to claim 2, characterized in that said spring portion (35) is arranged below said stationary portion (33).

13. 3. The actuation system according to claim 2, characterized in that the flexible blades of the translation stages (51, 52, 53, 54) of the spring portion (35) are substantially parallel when the actuator is in the rest position (30).

14. 3. An actuation system according to claim 2, characterized in that said movable part (37) comprises a hook (39).

15. 2. An actuation system according to claim 1, characterized in that said actuator (30) is made in one piece, said actuator (30) being obtained, for example, by a LIGA or DRIE process.

16. A clock movement, characterized in that it includes an actuation system (20) according to claim 1.

17. A timepiece, such as a wristwatch, characterized in that it includes a timepiece movement according to claim 16.

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