Device for pinning a hairspring for a clock movement to a stud and adjusting its effective length, and method for setting the effective length

Abstract

To provide a simpler and more economical device for pinning a balance-spring for a timepiece movement to a stud and for setting the effective length thereof.SOLUTION: The present invention relates to a device 1 for pinning a balance-spring 2 for a timepiece movement to a stud and for setting the effective length thereof. The balance-spring 2 is arranged in the shape of a coil along a predetermined length and the device 1 has a pressing button 6 arranged to mechanically hold the balance-spring 2 in a position of the length of the balance-spring 2.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a device for pinning a hairspring for a timepiece movement to a stud and for adjusting its effective length. [Background technology]

[0002] Hereinafter, as is customary, the term "component" refers to a spare part used in the construction of a device for pinning a hairspring on a stud and for adjusting its effective length according to the invention, and "part" refers to an assembly of two or more "components".

[0003] In a watch with a mechanical movement, the setting mechanism consists of a balance spring assembly with an escapement. These different elements work thanks to the mechanical energy provided by the barrel spring and perform the counting and division of time into seconds. It is therefore understood that the accuracy of the setting function of the balance spring assembly depends on the accuracy of the time display provided by the watch with a mechanical movement.

[0004] A first known technique for ensuring the accuracy of the rate of the balance spring assembly is to provide the balance with inertia blocks adjustably fastened, for example to the outer rim of the balance. By adjusting the position of these inertia blocks, the inertia of the balance is influenced and the rotational frequency of the balance spring assembly is modified.

[0005] Another known technique for ensuring the accuracy of the rate of a hairspring assembly consists in providing said hairspring assembly with an index assembly including at least one index and an index key supported by the index and provided with a slot in which the hairspring is attached. The index key can rotate on its own, while the index can rotate around the axis of rotation of the hairspring assembly, on a shoulder of a bridge or around a shock-absorbing bearing.

[0006] The portion of the balance spring that extends from the index key to the center of the balance spring, as defined by the free end of the inner last coil of the balance spring, determines the effective length of the balance spring.

[0007] The part of the balance spring extending between the balance spring stud, to which the free end of the outer final coil of the balance spring is fastened, and the index key is considered mechanically rigid and has no effect on the oscillations of the balance.

[0008] The position of the index key defines a so-called count point, the position of which can be changed by rotating the index. Changing the position of the count point changes the available length of the balance spring and therefore the frequency of the beat of the balance spring assembly. Rotating the index key on itself limits the movement of the balance spring in the slot located in this index key, taking care, of course, not to completely lock this balance spring. This has the effect of improving the accuracy of the setting of the beat frequency of the balance spring assembly and therefore of improving the rate accuracy of this assembly.

[0009] As can be seen from the above, in many mechanical movements of timepieces, equipping the balance spring assembly with the means for setting its frequency requires a considerable number of components (balance spring stud for pinning the free end of the outer final coil of the balance spring to a stud, optionally a stud support, an index, an index tail and an eccentric screw for finely adjusting the position of the index, an index key), which is expensive and requires a relatively long setting time to precisely adjust the rotational frequency. The other solution, which consists in adjusting the inertia of the balance by means of a setting screw, is even more expensive in terms of machining operations and the setting time for the rotational frequency of the balance spring assembly. Summary of the Invention

[0010] SUMMARY OF THE PRESENT EMBODIMENT It is an object of the present invention to remedy the above mentioned drawbacks and others by providing a simpler and more economical device for both pinning the balance spring of a timepiece movement to a stud and for setting its effective length.

[0011] To this end, the invention relates to a device for pinning a hairspring for a timepiece movement to a stud and setting its effective length, the hairspring being formed from a helical strip of a predetermined length, the device comprising a push button arranged to mechanically hold the hairspring in position on the length of the strip of the hairspring.

[0012] According to a particular embodiment of the invention, the push button is composed of a button and a tube, said button being slidable, said button being elastically returned to a locked position by an elastic mechanism, said button being maintained away from said locked position in the operating position by inserting a part of a strip of the hairspring between said button and said tube, thereby ensuring mechanical retention of the hairspring.

[0013] According to another particular embodiment of the invention, the button extends between a head and a foot and is arranged with a groove extending at least partially around said foot, engaging a portion of the hairspring in a position intended to stop it by gripping along two different points between said foot and the end of said button facing the tube, such that said push button is able to transmit a holding torque to said hairspring, so that said hairspring does not rotate or slide around its fastening point over the life of the watch.

[0014] According to another particular embodiment of the invention, said groove extends along the entire circumference of said button.

[0015] According to another particular embodiment of the invention, said elastic mechanism is a spring.

[0016] According to another particular embodiment of the invention, said spring is an elastic strip.

[0017] According to another particular embodiment of the invention, said button is provided with a groove which engages with a portion of the strip of the balance spring, the presence of which holds said button in said operating position.

[0018] According to another particular embodiment of the invention, said groove extends along the entire circumference of said button.

[0019] According to another particular embodiment of the invention, said push button is fastened to a receiver of said timepiece movement.

[0020] According to another particular embodiment of the invention, the device for pinning to the stud and for setting the effective length of the hairspring comprises a push element support supporting the push button, the push element support being arranged rotatably around the axis of rotation of the hairspring assembly of the timepiece movement.

[0021] According to another particular embodiment of the invention, said push element support is rotatably mounted on a support.

[0022] According to another particular embodiment of the invention, said support is a balance cock or a bearing supported by said cock.

[0023] According to another particular embodiment of the invention, said bearing is a shock absorbing bearing.

[0024] According to another particular embodiment of the invention, a scale with a number of graduations, each corresponding to an amount of time gain or loss of said clock movement, is attached to a receiver or to the plate of said clock movement.

[0025] According to another object of the invention, the invention relates to a balance spring for a clock movement formed from a length of a spiral strip, at least a portion of said strip being provided with a scale comprising a number of graduations each corresponding to an amount of gain or loss of time for said clock movement.

[0026] According to another embodiment of the invention, the scale comprises graduations each representing 0.1 seconds.

[0027] The invention also relates to a method for setting the effective length of a hairspring of a timepiece movement by means of a device according to the invention, comprising temporarily releasing said hairspring by pressing a push-button to adjust its effective length, then rotating the balance whose beat is given by said hairspring through the desired angle, then stopping the hairspring again by releasing the pressure on the push-button, rotating the balance causing a displacement of guide marks which are subsequently realigned by rotating the device.

[0028] Thanks to these characteristics, the invention provides a device that makes it possible to pin the hairspring of a timepiece movement to a stud and to set its effective length in order to precisely adjust the frequency of the hairspring. Since the hairspring is pinned to the stud without the need for adhesive, it can be repositioned at any time, if necessary, so that the frequency of the hairspring can be set over the life of the watch, for example when it is returned to the factory. Moreover, the watch designer enjoys complete freedom in terms of the choice of material from which the hairspring is manufactured, considering that no constraints are imposed by considerations related to the choice of adhesive.

[0029] In its simplified embodiment, the device according to the invention thus advantageously makes it possible to combine the functions of a balance spring stud and an index, which makes it possible to reduce the number of components required and simplifies the integration of the device according to the invention into a watch movement for compactness reasons.

[0030] Furthermore, in a preferred embodiment of the invention, the device comprises a push element support, by means of which the device for pinning and adjusting on the stud can be mounted rotatably about the axis of rotation of the balance spring assembly, which makes it possible to set guide marks for the balance.

[0031] The invention thus very remarkably provides a device which makes it possible to combine in a single part four separate functions of a hairspring of a watch movement which at first glance seem mutually exclusive: namely, pinning to the stud, mounting the stud support to the support, setting the effective length and setting the guide marks.

[0032] It should be noted that in the prior art, the fastening point of the hairspring was traditionally provided by a hairspring stud, while the setting of the counting point was achieved by an indexing key. In contrast, the device according to the invention makes it possible to combine both the fastening point of the hairspring and the counting point in a single point. One advantage of this device is that in a simplified embodiment of the invention, it becomes possible to use a balance of a hairspring assembly that does not have special means for setting its inertia, allowing considerable savings. [Brief description of the drawings]

[0033] Other particular embodiments and advantages of the present invention will be better understood by reading the following detailed description of an embodiment of a device for adjusting the effective length of a hairspring by pinning on a stud according to the invention, an example of which is provided for illustrative purposes only and is not intended to limit the scope of the invention, and is provided with reference to the accompanying drawings, in which: [Figure 1] FIG. 2 is a top view of a device for pinning a hairspring to a stud and setting its effective length for a timepiece movement according to the invention; [Diagram 2] FIG. 2 is a cross-sectional view taken along the section line II-II in FIG. [Diagram 3]FIG. 2 is a perspective view of a particular embodiment of a terminal curve of a hairspring, particularly adapted to cooperate with a device according to the invention; [Figure 4] FIG. 4 is a bottom perspective view showing the arrangement between the push button of the device according to the invention and the balance spring of FIG. [Diagram 5] 1 is a schematic diagram of a device according to the invention fastened by means of a screw to a bridge of a watch movement; DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0034] The invention derives from a general inventive concept consisting of combining in a single component at least some of the functions relating to a hairspring intended to provide an isochronous beat of the balance of a hairspring assembly of a watch movement. To this end, the invention provides, firstly, a device comprising a push button arranged to stop the hairspring of a watch movement at a position of its length without the use of adhesives. The watch designer therefore enjoys complete freedom in terms of the choice of material from which the hairspring is manufactured and, moreover, considering that the hairspring is not glued, the device according to the invention can be dismantled at any time, for example when the watch is returned to the factory. The device according to the invention therefore firstly allows a repositionable pinning of the hairspring on a stud. On the other hand, by using the push button, the hairspring can be stopped at any position of its length, which makes it possible to set the effective length of this hairspring, i.e. the distance from the free end of the first coil in this hairspring to the point at which the hairspring is stopped by the push button. The device according to the invention therefore makes it possible to freely set the rotational frequency of a hairspring assembly equipped with a device according to the invention. Finally, in a preferred embodiment, the device according to the invention comprises a push element support which allows for fixed mounting to a bridge of a watch movement or for rotation to a support such as a balance bridge or a bearing supported in this bridge. In this embodiment, the device according to the invention thus performs four separate functions: repositionable pinning of the balance spring to a stud, mounting of the stud support to its support, setting the effective length of said balance spring and setting the guide marks of the balance.The device according to the invention, in a simplified alternative embodiment, consists of a single part formed from the tube, the button and the elastic body, and therefore advantageously replaces the assembly of prior art components such as the stud of the hairspring, the stud support, the index, the index key, the index tail and the eccentric, which reduces the number of components required for fastening the hairspring and for setting the rotational frequency of the hairspring assembly, and facilitates the installation of the device according to the invention in a watch movement due to its reduced size. Another main advantage of the invention lies in the fact that the use of adhesives can be avoided.

[0035] An apparatus according to the invention, generally designated by the general reference number 1, is shown in a top view in FIG. 1 and in a cross-sectional view along the line II-II in FIG.

[0036] In its simplified embodiment, the device 1 according to the invention allows the pinning of a hairspring 2 for a timepiece movement onto a stud and the setting of the effective length of this hairspring 2 .

[0037] The hairspring 2, which is arranged in a coil, has a length between the free end of the inner first coil and the free end of the outer final coil 3. By way of example only, the hairspring 2 may be formed in the form of a flat strip bounded by first and second faces extending parallel to and at a distance from each other.

[0038] More specifically, the device 1 according to the invention makes it possible to advantageously and removably stop the hairspring 2 at any position of its length and to set the length separating the point 4 at which this hairspring 2 is stopped from the free end of the first coil in the hairspring 2, as will be explained below.

[0039] For this purpose, the device 1 according to the invention firstly comprises a push button 6 arranged to releasably hold the balance spring 2 at a position on the length of the strip of this balance spring 2 .

[0040] As shown in Figure 2, the push button 6 basically comprises a button 8 and a tube 10, the button 8 being slidable. Advantageously, the button 8 is elastically returned to the locked position by an elastic mechanism 12, such as a spring or an elastic strip (see in particular Figure 1).

[0041] Furthermore, in the operating position, the button 8 can be kept away from the locked position by inserting part of the hairspring 2 between the button 8 and the tube 10, thereby ensuring a mechanical stop of the hairspring 2.

[0042] It is easy to see that one of the fundamental advantages of the invention is that the hairspring 2 can be released from its engagement with the pushbutton 6 at any time. For this, it is only necessary to apply pressure to the button 8 so as to pull it further out of the tube 10 against the return force of the elastic organ 12. Furthermore, by suitable selection of the stiffness coefficient of the elastic organ 12, the gripping force applied to the hairspring 2 when it is held immobile between the button 8 of the pushbutton 6 and the tube 10 can be precisely controlled. The risk of breakage of the hairspring 2, in particular when it is made of silicon, can thus be limited.

[0043] As shown in figure 2, the button 8 extends between the head 14 and the foot 16 and is provided with a groove 18 which passes at least partially around the foot 16. The hairspring 2 is then passed around the foot 16 of the button 8 in the part that is to be stopped by the push button 6, by gripping it between the foot 16 of the button 8 and its end facing the tube 10. The hairspring 2 is thus gripped along two points between the foot 16 of the button 8 and its end facing the tube 10, so that the push button 6 can transmit a holding torque to the hairspring 2, which will not rotate or slide around its fastening point over the life of the watch.

[0044] According to a simplified embodiment of the invention shown in FIG. 5, the device 1 according to the invention and its push button 6 are simply fastened, typically by means of a screw 21, to a receiver 20 on the plate of the clock movement.

[0045] According to an improved embodiment of the invention, the device 1 for pinning a hairspring 2 on a stud and setting its effective length further comprises a push element support 22 supporting the push button 6, and a balance 24 forming part of a hairspring assembly 26. The push element support 22 is arranged to be rotatable around the axis of rotation D of the hairspring assembly 26 of the timepiece movement.

[0046] For this purpose, the push element support 22 is provided with an opening 28 whose inside diameter is adjusted to the outside diameter of the rotation axis D of the balance spring assembly 26. In this way, the device 1 according to the invention advantageously performs the functions of both balance spring stud and stud support.

[0047] As shown in FIGS. 1 and 2, the balance spring assembly 26 preferably rotates within a shock absorbing bearing 30 which includes a setting 32, a jewel 34, a jewel 36 and a spring 38, in a conventional manner.

[0048] The invention is not limited to the embodiments described herein, and it goes without saying that a person skilled in the art can consider various simple alternatives and modifications without departing from the scope of the invention as defined in the appended claims. In particular, in order to facilitate the setting of the effective length of the hairspring 2, at least a part of the helical strip forming this hairspring 2 can be provided with a scale 40, as shown in figures 3 and 4, in which each graduation represents a change of, for example, 0.1 seconds. To adjust the effective length of the hairspring 2, it is only necessary to press the button 8 of the push-button 6 to momentarily release the hairspring 2 and then rotate the balance 24 by the desired angle to correct a known advance or delay. For example, if the clock movement advances by one second per day, the hairspring assembly 26 is moved to induce a delay by moving 10 graduations of 0.1 seconds in front of the index 42. Then the pressure on the button 8 of the push-button 6 is released and the hairspring 2 stops again. The rotation of the balance 24 also causes a displacement of the guide mark, which can then be readjusted by rotating the device 1 consisting of the push button 6 and the push element support 22 supporting the push button 6. It is clear that this action is not possible in the case of the simplified embodiment of the invention shown in FIG. 5. It should be noted that in the present invention, the push button refers to an assembly formed by a cylinder and a tube inside which the cylinder can slide against the elastic return force of a spring. Similarly, the stopping of the balance spring 2 is performed along two points, one of which is provided on the terminal curve and the other in the area where the scale can be provided, as mentioned above. [Explanation of symbols]

[0049] 1 device 2. Hairspring 3. Outer final coil 4 points 6 Push Button 8 Buttons 10 Tubes 12 Elastic engine 14 Head 16 Foot 18 groove 21 Screw 22 Push element support 24 Temp D Rotational Axis 26 Hairspring assembly 28 Opening 30 Shock absorbing bearing 32 Setting section 34 Anaishi 36 Support Stone 38 Spring 40 Scale 42 Index

Claims

1. A device (1) for stopping the free end of an outer final coil of a hairspring (2) for a timepiece movement and for setting the effective length of said hairspring (2), comprising: The hairspring (2) is arranged in a coil along a predetermined length, said device (1) comprising a push button (6) arranged to mechanically hold said balance spring (2) in the position of said length of said balance spring (2), The push button (6) is composed of a button (8) and a tube (10); The device (1), characterized in that the button (8) is slidable, the button (8) is elastically returned to a locked position by an elastic mechanism (12), and the button (8) is maintained away from the locked position in an operating position in which the engagement between the balance spring (2) and the push button (6) is released by inserting a part of the balance spring (2) between the button (8) and the tube (10), thereby ensuring a mechanical retention of the balance spring (2).

2. The button (8) extends between a head (14) and a foot (16); 2. A device (1) according to claim 1, characterized in that a groove (18) extending at least partially around the foot (16) is arranged so that the push button (6) engages a part of the hairspring (2) in a position where it is intended to stop the hairspring (2) by gripping it along two different points between the foot (16) and the end of the button (8) facing the tube (10) so as to be able to transmit a holding torque to the hairspring (2), so that the hairspring (2) does not rotate or slide around its fastening point over the life of the watch.

3. 3. The device (1) according to claim 2, characterized in that said groove (18) extends along the entire circumference of said button (8).

4. 2. The device (1) according to claim 1, characterized in that the elastic mechanism (12) is a spring.

5. 5. The device (1) according to claim 4, characterized in that the spring is an elastic strip.

6. 2. The device (1) according to claim 1, characterized in that the button (8) is provided with a groove (18) which engages with a portion of the balance spring (2) thereby holding the button (8) in the operating position.

7. 2. Device (1) according to claim 1, characterized in that the push button (6) is fastened to a balance cock (20) of the watch movement.

8. The device (1) described in claim 1, further comprising a push element support (22) supporting the push button (6), the push element support (22) being rotatably arranged around the rotation axis (D) of the hairspring assembly (26) of the watch movement.

9. 9. Apparatus (1) according to claim 8, characterized in that the push element support (22) is rotatably mounted on a support.

10. 10. Device (1) according to claim 9, characterized in that the support is a balance cock (20) or a bearing supported by said cock.

11. 11. Device (1) according to claim 10, characterized in that the bearing is a shock absorbing bearing (30).

12. 2. The device (1) according to claim 1, characterized in that a scale (40) with a number of graduations, each of which corresponds to an amount of time advance or delay of the clock movement, is attached to a receiver (20) of or to the plate of the clock movement.

13. 1. A hairspring (2) for a clock movement, the effective length of which is set by a device (1) according to claim 1, the hairspring (2) being formed from a spiral strip of a predetermined length, at least a portion of said strip being provided with a scale (40) comprising a number of graduations each corresponding to an amount of gain or loss of time of the clock movement.

14. 14. The balance spring (2) according to claim 13, characterized in that the scale (40) comprises graduations each representing 0.1 seconds.

15. 2. A method for setting the effective length of a hairspring (2) of a timepiece movement by means of a device (1) according to claim 1, comprising: To adjust the effective length of the hairspring (2), the hairspring (2) is temporarily released by pressing the push button (6), Next, the balance (24), the beat of which is given by the balance spring (2), is rotated through the desired angle, The pressure on the push button (6) is then released to stop the balance spring (2) again, 4. A method according to claim 1, wherein rotating said balance (24) causes a movement of a guide mark of said balance (24), said guide mark being subsequently realigned by rotating said device (1).

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