Hairspring driving cord

Abstract

The present invention relates to a method of depositing (500) an electroconductive layer electrically connecting at least one outer coil (105) and a stud (102) and representing at least 1%, in particular 5%, preferably 10% and / or at most 90%, in particular at most 75%, preferably at most 50% of at least one dimension of a watch spiral (101).

Description

technical field

[0001] The present invention relates to an oscillating system for a watch movement. The present invention relates in particular to an oscillating system comprising a watch balance spring from which electrostatic charges can be eliminated. Technological background

[0002] In the field of watchmaking, balance springs, which together with the balance wheel form the timekeeping basis of mechanical timepieces, are well known. These balance springs are schematically represented as very thin springs wound in concentric coils, with one end connected to a ferrule and the other end to a stud.

[0003] The material used for making balance springs is usually an alloy based on iron, cobalt, nickel, and chromium. Being ductile, such an alloy must be corrosion-resistant. Recent developments propose making balance springs from silicon. Due to their very small size and friction with air and between the coils, balance springs tend to accumulate static electricity, causing the coils to stick together. The balance springs then become unusable as is.

[0004] Furthermore, current methods for discharging electrostatic charges in the movement via the stud involve an electroconductive adhesive bonding the stud and the spiral. This adhesive is generally a mixture of a photo- or UV-curable glue and conductive particles. However, these conductive particles hinder the cross-linking of the assembly. This can lead to partial cross-linking and therefore a separation of the stud and spiral, which is detrimental to the oscillator's operation. Another solution is to significantly increase the cross-linking time, but this conflicts with industrial production rates. Document WO 2014 / 023584 proposes an alternative, in which the spiral is bonded to the stud using a drop of non-conductive adhesive that is polymerized, and then conductive particles are sprayed onto the drop of adhesive.This technique is not easy to implement, and it is difficult to ensure a good conductive connection between the spiral and the eyelet using these conductive particles deposited on the outer surface of the glue droplet. Furthermore, the spraying of the conductive particles is not controlled, so there is a risk of them reaching the spiral in various unplanned locations.

[0005] Finally, in some cases, electrostatic charges can be located elsewhere than on the spiral itself, but in its immediate vicinity, for example, a component made of insulating material that was initially charged during assembly or during transport. These charges, generally associated with an element significantly more massive than the spiral, will therefore attract the spiral and cause malfunctions by introducing internal stresses and thus altering its natural frequency.

[0006] To overcome these problems, various solutions, ranging from simple to complex, have been proposed. These include applying a thin layer of a material, preferably stainless and non-magnetic, such as gold, platinum, rhodium, or silicon, to all or part of the surface of the balance springs. Document EP 1837722 proposes such a technique, and document WO 2014 / 023584 also mentions it. However, such techniques require additional manufacturing steps, which are notably costly. Furthermore, these techniques tend to slow down production rates. To address these drawbacks, the present invention proposes an oscillating system for watch movements comprising a balance spring from which electrostatic charges can be eliminated. Summary of the invention

[0007] To overcome these drawbacks, the present invention proposes a method for depositing an electroconductive layer onto an oscillating system of a watch movement comprising a balance spring with at least one outer coil fixed by a stud; said deposition method comprising a step of: Supply of said oscillating system; Deposition of at least one first electroconductive layer electrically connecting said at least one outer coil and said stud and representing at least 1%, in particular 5%, preferably 10% and / or at most 90%, in particular at most 75%, preferably at most 50% of at least one dimension of said watch spiral, the deposition of the first electroconductive layer being carried out by an atomizer in liquid form surrounded by a sheathing gas so as to be unidirectional.

[0008] Thanks to this arrangement, an oscillating system for watch movement comprising a watch balance spring from which electrostatic charges can be eliminated.

[0009] According to one embodiment, said watch spiral comprises at least one inner coil fixed by a ferrule and at least one outer coil fixed by said stud.

[0010] According to one embodiment, said at least one first electroconductive layer is deposited on the outside of said pin.

[0011] Thanks to this arrangement, at least one first electroconductive layer can be easily deposited.

[0012] According to one embodiment, said first electroconductive layer comprises a continuous electroconductive layer and / or a plurality of discrete electroconductive layers so as to form a continuous electroconductive layer.

[0013] By means of either of the preceding provisions, a continuous electroconductive layer and / or a plurality of discrete electroconductive layers can be deposited in a targeted or unidirectional manner. In one embodiment, said at least one dimension is the length of said watch spiral.

[0014] Thanks to this arrangement, an oscillating system for watch movement comprising a watch balance spring from which electrostatic charges can be eliminated. Brief description of the figure

[0015] The invention will be described in more detail below with the aid of the attached drawing, given by way of non-limiting example, which represents a method of depositing (500) an electroconductive layer on an oscillating system (100) of a watch movement. Detailed description of the invention

[0016] There figure 1 illustrates a deposition process 500 of an electrically conductive layer on an oscillating system100 of a watch movement including a watch balance spring 101 with at least one inner coil secured by a ferrule and at least one outer coil 105 secured by a hook 102.

[0017] One of the steps in the said deposit process 500 is the supply 510 said oscillating system 100. This is followed by the deposition of at least one first electroconductive layer 110 by an atomizer 900 electrically connecting said at least one outer loop 105 and the said peak 102. Preferably, said first electroconductive layer 110 includes a continuous electrically conductive layer 111 and / or a plurality of discrete electrically conductive layers 115 so as to form a continuous electrically conductive layer 111.

[0018] Said at least one first electroconductive layer 110,more specifically, said continuous electrically conductive layer 111 is deposited and / or said plurality of discrete electroconductive layers 115 are deposited on the outside of said peak 102, more precisely on the part of said peak 102 being external to said clock spiral 101 because it is more easily accessible than the part facing the coils of said clockwork spiral 101.

[0019] The said atomizer 900 is configured to deposit said at least one first electroconductive layer 110 in liquid form surrounded by a sheathing gas 119 so as to be unidirectional and thus deposit said first electroconductive layer 110 on said at least one dimension, preferably the length of said clock spiral 101,and representing at least 1%, in particular 5%, preferably 10% and / or at most 90%, in particular at most 75%, preferably at most 50% of at least one dimension of said watch spiral 101. Furthermore, the said atomizer 900 being unidirectional, the deposition of said at least a first electroconductive layer 110 may only partially cover the width of said clockwork spiral 101 but perhaps not the entire width of said clockwork spiral 101 which prevents a change in the characteristics of the said watch spiral 101 such as its inertia or frequency, or a change in its elastic response.

[0020] Thus, thanks to this arrangement, the conduction of electrical charges is made possible by the deposition of said at least one first electroconductive layer. 110 on its surface.

[0021] Furthermore, the deposition process is economical due to its simplicity and the small amount of material deposited. Moreover, unlike adhesives containing silver or carbon nanoparticles, for example, this deposition process does not expose employees to potentially hazardous particles during the preparation or application of these adhesives due to inhalation, as the spraying is rarely directional, or even unidirectional. Another disadvantage of conventional spraying is that it can contaminate nearby moving components such as the exhaust or balance shaft, thus disrupting their tribological functions.

Claims

1. Deposition method (500) of an electroconductive layer on an oscillating system (100) of a horological movement comprising a horological balance-spring (101) with at least one outer coil (105) attached by a collet (102); said deposition method comprising the following steps: - Providing (510) said oscillating system (100); - Depositing at least a first electroconductive layer (110) electrically connecting said at least one outer coil (105) and said balance-spring stud (102) and representing at least 1%, particularly 5%, preferably 10% and / or at most 90%, particularly at most 75%, preferably at most 50% of at least one dimension of said horological balance-spring (101); characterised in that the deposition of said first electroconductive layer (110) is carried out by an atomiser (900) in liquid form surrounded by a sheathing gas (119) so as to be unidirectional.

2. Deposition method (500) according to claim 1, wherein said at least a first electroconductive layer (110) is deposited on the outside of said balance-spring stud (102).

3. Deposition method (500) according to claim 1, wherein said atomiser (900) is unidirectional.

4. Deposition method (500) according to any one of claims 1 to 3, wherein said first electroconductive layer (110) comprises a continuous electroconductive layer (111) and / or a plurality of discrete electroconductive layers (115) so as to form a continuous electroconductive layer (111).

5. Deposition method (500) according to any one of the preceding claims, wherein said at least one dimension is the length of said horological balance-spring (101).

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