EP0913106B1 - Foldable fastener for a bracelet - Google Patents

Abstract

Bracelet clasp comprises rigid base (1) with two side members (4), two folding arms (2) pivoted at one end of base and adapted to be folded down between the side members, and clevis (3) connecting the arm to a strand of the bracelet. The arm has two parallel branches (10) each with a hook (30) hooking onto the side members. The heads (14) of branches are separated by spring slide (23) and each has pivoting journal.

Description

The present invention relates to a folding clasp for a strap, especially for a watch strap, comprising a rigid base provided with two longitudinal members, at minus a yoke arranged to be attached to a strand of the bracelet, and at least one folding arm having a rear end attached to one end of the base by a first articulation and a front end attached to said strand of the bracelet by a second joint and clevis, and in which the arm leaflet has two juxtaposed branches, the front ends are separated by an elastic element, the folding arm having a closed position in which it is retained between the side members by these.

Patent EP 0 115 740 relates to a clasp of this type. kind, provided with two folding arms, each articulated at one end of the base and one strand of the bracelet. AT their front end, the two arms of each arm leaflet are attached to respective hollow cylinders which carry pins and contain the spring, these pins used to attach the arm to the strand matching bracelet. One of these cylinders has a reduced diameter extension which fits into the other cylinder to link the two branches while allowing them to be brought together slightly. This allows for a system of elastic retention of each arm in the closed position, each arm branch having a profiled outer edge protruding, for example in very open V, which engages in a profile complementary to the inner edge of the adjacent spar. So, just press on the folding arm so that it hangs between the side members and thus be retained in the closed position, and it suffices to pull it up so that it opens unhooking from the base thanks to the elasticity of the spring and the inclination of its contact surfaces with the based.

However, such a restraint system has the risk of accidental opening of the clasp, for example example if the bracelet hangs on an external element in the region of the clasp.

To prevent this risk, we know clasps leaflets with a locking mechanism ensuring their blocking in the closed position by organs to positive engagement, the release of which is ordered using pushers. Such mechanisms are provided in the yoke to hang it at the base, in the case of the patents CH 646 314, CH 665 101, CH 668 353 and GB 2 301 616. Their disadvantages lie in a relatively complicated construction, which takes time places and increases manufacturing and assembly costs.

A simpler locking mechanism is described in FIG. 3 of patent EP 0 383 039. In this case, the two base rails are flexible transversely, this base being long enough to carry two arms flyers. In the closed position, the two branches of each arms are placed on either side of the side members and hang on hooks provided on the latter. Of them opposite lifters are attached to the side members in the region hooks. To open the clasp, the user must press the two pushers at the same time to unlock the clasp, then it must grab and lift the corresponding yoke or strand of the bracelet. Indeed, as such a clasp is curved to follow the shape of the wrist of the user, usually it does not open spontaneously after unlocking. This manipulation with plug change is a disadvantage. In moreover, as the pushers pass under the branches of the folding arm, they increase the thickness of the clasp and protrude against the wearer's skin there. On the other hand, this system requires fairly long beams to be flexible enough and therefore not suitable for clasps with a single folding arm.

The subject of the present invention is a clasp leaflet to avoid inconvenience mentioned above, in particular thanks to a construction simple, thin and inexpensive to manufacturing and mounting, ensuring both effective locking in the closed position and a easy handling for opening the clasp. Of preferably, the invention should also be applicable well to a clasp having a single folding arm than to a two-arm clasp.

To this end, the invention relates to a clasp such as defined in claim 1. The claims dependents define embodiments advantageous.

Thus, the construction according to the invention is particularly simple since the organs of the mechanism are all integrated into the parts main clasps and therefore require no parts additional. In particular, the pushers are integral parts of the branches of each arm and can each serve as a trunnion engaged in the yoke to form the second joint. As they emerge on each side of the screed, the user can press towards each other, grasp the yoke and the lift in one movement to open the clasp.

• la figure 1 représente en perspective une première forme de réalisation d'un fermoir dépliant selon l'invention, dans sa position ouverte;
• la figure 2 représente le fermoir de la figure 1 dans sa position fermée;
• la figure 3 est une vue en coupe verticale suivant la ligne III-III de la figure 2;
• la figure 4 est une vue analogue à la figure 3, montrant le mode d'ouverture du fermoir,
• les figures 5 et 6 représentent en perspective une deuxième forme de réalisation d'un fermoir selon l'invention, respectivement en position ouverte et en position fermée,
• la figure 7 représente en coupe partielle une troisième forme de réalisation d'un fermoir selon l'invention, comportant un organe de blocage,
• la figure 8 est une vue en coupe partielle suivant la ligne VIII-VIII de la figure 7, et
• la figure 9 représente en perspective une extrémité de l'organe de blocage représenté aux figures 7 et 8.

Other characteristics and advantages of the present invention will appear in the following description, given by way of nonlimiting example with reference to the appended drawings, in which:

• Figure 1 shows in perspective a first embodiment of a folding clasp according to the invention, in its open position;
• Figure 2 shows the clasp of Figure 1 in its closed position;
• Figure 3 is a vertical sectional view along line III-III of Figure 2;
• FIG. 4 is a view similar to FIG. 3, showing the method of opening the clasp,
• FIGS. 5 and 6 show in perspective a second embodiment of a clasp according to the invention, respectively in the open position and in the closed position,
• FIG. 7 shows in partial section a third embodiment of a clasp according to the invention, comprising a blocking member,
• FIG. 8 is a partial section view along line VIII-VIII of FIG. 7, and
• FIG. 9 shows in perspective one end of the blocking member shown in FIGS. 7 and 8.

The example illustrated by FIGS. 1 to 4 relates to to a watch strap clasp which includes: rigid curved base 1, one end of which is arranged for be attached to a strand of the bracelet, one arm leaflet 2, the rear end of which is hinged at the other end of the base 1, and a yoke 3 articulated to the front end of arm 2 and arranged to be attached to the other side of the bracelet (not shown). Of preferably, all parts of the clasp are metallic, but other suitable materials can be used, especially synthetic or composite materials.

The base 1 has two substantially spars parallels 4, which are curved to apply comfortably against the wearer's wrist. AT the front end of the base, the side members 4 are rigidly assembled by a cross member 5 having a part raised with a transverse hole 6 for attach the base 1 to the corresponding strand of the bracelet by known means. The cross 5 can for example be welded to the two beams 4, or be made in one piece with them. At their rear end, the side members 4 are assembled by a cylindrical transverse rod 7 which can be chased, riveted or welded and serves as a hinge axis of arm 2 on base 1.

The arm 2 has two curved branches 10 and substantially parallel, taking place between the two side members 4 of the base in the closed position of the clasp, as shown in Figure 2. Each branch 10 has a middle part 11 thinned to be flexible laterally. The rear ends 12 of the two branches 10 are contiguous and pivotally mounted on the rod 7, thus forming a first articulation 13 of the arm 2. Note however that arm 2 could be made in one piece in the form of a tuning fork having an effect of stands out by its own elasticity, but the construction two pieces is easier and allows the use of stiffer temples if given a slight play lateral in joint 13. At the front end of the arm 2, each branch 10 has an enlarged head 14 ending, on the outside, with a cylindrical pusher 15 which is engaged in the manner of a journal in a corresponding hole in the yoke 3 to form a second articulation 16 of the arm 2.

In known manner, the yoke 3 comprises a plate central 17, which covers the connection zones between the clasp and bracelet strands, and two sides parallel 18 provided with several holes 19 allowing attach the clevis 3 to the other strand of the bracelet length adjustable way. In this case, at in the vicinity of the corresponding push-button 15, a hollow 20 is formed in each side 18 so that the pushers 15 do not are not prominent compared to the rest of the screed.

As seen particularly in Figure 3, the head 14 of each branch 10 present, opposite the other head 14, a blind and cylindrical hole 22 which is preferably aligned with the pushers 15. A bar cylindrical 23 is slidably engaged in the two holes 22 and thus holds the two arms 10 of the arm 2 substantially in the same plane. In addition, the bar 23 ends with two sliding points 24 which are pushed back by a spring 25 housed inside of the bar 23 and thus apply to the bottom of the holes 22. Spring 25 therefore tends to separate the two branches 10 in the front part of arm 2, until the heads 14 abut against the sides 18 of the yoke 3. In this position, i.e. when the pushers do not are not in a hurry, the two branches 10 are separated by an interval E greater than the length L of one of their pushers 15 crossing the yoke, so that the yoke can be mounted and dismounted on the arm by approximation of said branches.

To allow the clasp to be locked in position closed, each branch 10 of arm 2 present on its side outside, below the yoke 3, a projecting member hook shape 30. A corresponding recess 31 is formed in the inner side of each beam 4 for receive the hook 30 when the arm 2 is folded between the side members. Each hook 30 has a surface upper support 32 which will cooperate with a surface upper support 33 in the recess 31, and preferably the two surfaces 32 and 33 are substantially perpendicular to the direction of arm opening leaflet 2. Each hook 30 also has on the below an inclined plane 34 bearing against the corresponding beam 4 to push the hook against the force of the spring 25 when the arm 2, which is folded down then automatically attaches to base 1. The organs hooking thus ensure automatic locking at positive engagement which prevents opening of the clasp by any force, as long as we have not brought together the branches 10 of the folding arm 2.

In the closed position thus obtained, an opening involuntary clasp is impossible. Even if one of hooks 30 was released by an accidental impact on one pushers 15, the other hook 30 would continue ensure positive locking of the clasp.

The only possible way to unlock the clasp to unfold it is illustrated in Figure 4. The user laterally enters the yoke 3, for example between thumb and forefinger, so as to press simultaneously the two pushers 15 according to the arrows A against the force of the spring 25. The rods 24 retract then in the bar 23, the two branches 10 are close together and their hooks 30 emerge from the recesses 31. Without changing the socket, the user can then lift the yoke 3 and the folding arm 2 following the arrow B. As soon as this uprising is initiated, the tension of the bracelet is generally enough to fully unfold the clasp. To close the clasp and lock it, it just press on the top of the yoke 3.

In the embodiment shown in the figures 5 and 6, the clasp has two folding arms 2 identical to the one just described, and two yokes 3 each connecting one of the arms to a strand of the bracelet (not represented). The arms 2 are each attached to a corresponding end 52, 53 of the base 51. The latter has two parallel curved beams 54 playing the same role as the beams 4 of the previous example and each comprising two recesses 31 as described more high, for hooking the hooks 30 of each arm 2. The longitudinal members 54 are rigidly connected to each other by a median cross member 55 and by the articulation rods arranged at the ends of the base, so that the two folding arms 2 can take place between the side members in the closed position shown in Figure 6, the two yokes 3 being adjacent. The clasp then presents a small thickness, as in the previous example. We note that this two-arm clasp has two locking mechanisms, each of which can operate independently as described above.

Figures 7 to 9 show a variant of clasps illustrated in Figures 1 to 6, where we added a blocking member 60 intended to prevent the clasp could open by accidental pressure on the pushers 15. In this example, the head 14 of each branch 10 of the folding arm 2 has a radial collar 61 which abuts against the corresponding side 18 of the yoke 3. The locking member 60 is mounted in the yoke 3 so pivoting by means of a transverse bar 62 whose ends 63 are engaged by springs in clevis holes 3. This member 60 has a general shape approximately cylindrical, with a control finger 64 which emerges through an upper opening 65 of the yoke 3. Its underside has two notches 66 and 67 arranged to engage on another transverse bar 68 fixed in yoke 3, to define two positions different from organ 60.

As seen in particular in Figures 7 and 9, on each end of the blocking member 60, it is provided a lateral shoulder 70 capable of being placed the along the corresponding collar 61 to prevent the pusher 15 can move towards the inside of the clevis. This shoulder is interrupted by a recess in arc of a circle 71 which, when it is opposite the collar 61, on the contrary allows movement of the pusher 15 inward to unlock the clasp. This corresponds to the operating position of the blocking 60, drawn in solid line in FIG. 8. When the user pushes the control finger forward 64 to rotate the member 60 to the position of blocking shown in phantom, the two shoulders 70 are placed between the two collars 61 of the pushers 15 and thus prevent any bringing together of the branches 10 of the folding arm, i.e. an unlocking is impossible, even accidentally.

The foregoing description shows that the present invention allows for a low folding clasp thickness, composed of a small number of parts which can be manufactured and assembled in a simple and inexpensive manner expensive, and that this clasp has a mechanism for locking providing high operational safety and easy handling.

In addition, this clasp can be made entirely or partially made of composite materials, to present remarkable properties of lightness, rigidity, resistance to wear and reduction of friction. A such an achievement is made possible economically thanks to to the one-piece construction of the arms of the folding arm with their trunnion serving as a pusher and thanks to the fact that maintaining in the closed position is not ensured by a friction coupling (commonly called "clipping"), but by a positive locking of the arm on the base, opposing any opening force. It is necessary note that previously the use of synthetic materials in the folding clasps had resulted in failures either by wear of the clipping systems, either due to a lack of rigidity.

Claims (14)

1. Unfolding clasp for a wristlet, including:

   a rigid base (1, 51) provided with two side elements (4, 54),

   at least one cap (3) arranged for being attached to a strand of the wristlet, and

   at least one unfolding arm (2) having a back end attached to an end of the base via a first hinge and having a front end attached to said strand of the wristlet via a second hinge and the cap,

      and wherein the unfolding arm includes two juxtaposed branches (10) whose front ends are pushed apart by an elastic element (25), the unfolding arm (2) having a closed position in which it is held between the side elements (4, 54) by said elements,
      the clasp being characterized in that it includes a locking mechanism, arranged for holding the unfolding arm (2) in the closed position against any opening force, said mechanism including catching elements (30, 31) on the mutually facing sides of the side elements (4, 54) and branches (10), and in that the front ends of said branches (10) are provided with respective opposite push buttons (15) which are engaged in the cap (3) to attach it to the unfolding arm and which project respectively from each side of the cap, said push buttons (15) allowing a user to bring the branches (10) towards each other by pressure on the push buttons so as to unlock said mechanism by gripping the cap (3) to open the clasp.
2. Clasp according to claim 1, characterized in that the catching elements (30) of each branch are arranged in proximity to the cap (3).
3. Clasp according to claim 1 or 2, characterized in that the catching elements each include a support surface (32, 33) substantially perpendicular to the direction of opening of the unfolding arm.
4. Clasp according to claim 3, characterized in that the catching elements include a projecting hook (30) on each branch (10) and a recess (31) arranged in the corresponding side element (4, 54).
5. Clasp according to any of the preceding claims, characterized in that the front end of the unfolding arm (2) is attached to the cap (3) via the second hinge, each of the two push buttons (15) including a journal engaged in the cap in order to form the second hinge.
6. Clasp according to any of the preceding claims, characterized in that the two branches (10) of the unfolding arm are connected to each other, in proximity to the cap (3), by a tubular bar (23) containing a spring (25) and engaged so as to slide in respective blind holes (22) of the two branches.
7. Clasp according to claim 6, characterized in that, when the push buttons (15) are not pressed, the two branches (10) are separated by a gap (E) greater than the length (L) of one of their push buttons passing through the cap (3), so that the cap can be mounted and dismantled from the arm by moving said branches towards each other.
8. Clasp according to any of the preceding claims, characterized in that the two branches (10) of the arm are separate parts which, in the area of the first hinge (13), are contiguous and assembled to the base by a common articulation shaft (7).
9. Clasp according to any of the preceding claims, characterized in that a median portion (11) of each branch (10) is flexible laterally.
10. Clasp according to any of the preceding claims, characterized in that the locking mechanism also includes a blocking element (60) arranged for being moved by a user between two positions, namely a blocking position in which the blocking element prevents said branches (10) moving towards each other and a maneuvering position in which said movement towards each other is allowed.
11. Clasp according to claim 10, characterized in that the blocking element is pivotably mounted on the cap (3) and includes a pair of lateral shoulders (70) which are engaged between said branches (10) or projecting portions (61) of the latter in the blocking position, but not in the maneuvering position.
12. Clasp according to claim 10 or 11, characterized in that it includes a notch device (66-68) defining the two positions of the blocking element.
13. Clasp according to any of claims 1 to 12, characterized in that it includes a single unfolding arm (2), the other end of the base (1) being arranged for being attached to another wristlet strand.
14. Clasp according to any of claims 1 to 12, characterized in that it includes two unfolding arms (2) each attached to an end of the base (51) and to a corresponding cap (3), each arm having its own locking mechanism.

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