EP0914781A1 - Folding fastener for a bracelet - Google Patents

Abstract

The clasp comprises a rigid base (1) with two side frames (4). It has a folding arm (2) hinged at one end of the base and foldable between the two beams. A clevis (3) connects the arm to a strand of the bracelet. The arm has two parallel branches (10) each provided with a hook (30) hooking on to the side frames. The heads (14) of the branches are separated by a spring clip (23) and each have an external push button (15) serving as a pivot for the clevis.

Description

• une base rigide pourvue de deux longerons,
• au moins une chape agencée pour être rattachée à un brin du bracelet, et
• au moins un bras dépliant une extrémité arrière rattachée à une extrémité de la base par une première articulation et ayant une extrémité avant rattachée à la chape par une seconde articulation ,
  et dans lequel le bras dépliant comporte deux branches juxtaposées dont les extrémités avant sont écartées par un élément élastique et ont chacune un tourillon opposé à celui de l'autre branche et engagé dans la chape pour former ladite seconde articulation, le bras dépliant ayant une position fermée dans laquelle il est retenu entre les longerons par ceux-ci.

The present invention relates to a folding clasp for a bracelet, in particular for a watch bracelet, comprising:

• a rigid base provided with two beams,
• at least one yoke arranged to be attached to a strand of the bracelet, and
• at least one arm folding out a rear end attached to one end of the base by a first articulation and having a front end attached to the yoke by a second articulation,
  and in which the folding arm comprises two juxtaposed branches, the front ends of which are separated by an elastic element and each have a journal opposite that of the other branch and engaged in the yoke to form said second articulation, the folding arm having a position closed 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. Their front end, the two arms of each folding arm are attached to respective hollow cylinders which carry said pins and contain the spring. 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 an elastic restraint system of each arm in the closed position, each arm branch having a protruding profiled outer edge, for example V very open, which engages in a complementary profile of inner edge of the adjacent spar. So, just press on the folding arm so that it hangs between the side members and is thus retained in the closed position, and just 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 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 further, 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 the drawbacks mentioned above, in particular thanks to a simple construction, of thin and inexpensive to manufacture and mounting, ensuring both effective locking in closed position and easy handling for opening of the clasp. Preferably, the invention should be applicable both to a clasp with one arm fold-out than a two-arm clasp.

To this end, the invention relates to a clasp of the type indicated in the preamble, characterized in that it includes a locking mechanism, arranged to hold the arm leaflet in closed position against force any opening, said mechanism comprising side hooks facing each other mutually spars and branches, and that said pins are projecting on each side of the yoke to form lifters allowing a user to bring the branches together by pressing the pushers so as to unlock said mechanism by grabbing the clevis to open the clasp.

Thus, the construction according to the invention is particularly simple since the organs of the mechanism are all integrated into the main rooms of the clasp and therefore do not require any additional parts. In particular, the pushers are integral parts branches of each arm and each serve trunnion. As they emerge on either side of the yoke, the user can press them towards each other, enter the yoke and lift it 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, et
• les figures 5 et 6 représentent en perspective une autre forme de réalisation d'un fermoir selon l'invention, respectivement en position ouverte et en position fermée.

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

• 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, and
• Figures 5 and 6 show in perspective another embodiment of a clasp according to the invention, respectively in the open position and in the closed position.

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, yes 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 shape of a tuning fork having an effect of stands out by its own elasticity, but the construction in two pieces is easier and allows to use stiffer temples if they are 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 like a trunnion 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 assembled and disassembled 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 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 that 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 51 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.

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 offering 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 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 (11)

Folding clasp for bracelet, comprising: a rigid base (1, 51) provided with two longitudinal members (4, 54), at least one yoke (3) arranged to be attached to a strand of the bracelet, and at least one folding arm (2) having a rear end connected to one end of the base by a first articulation and a front end connected to the yoke by a second articulation,
and in which the folding arm comprises two juxtaposed branches (10), the front ends of which are separated by an elastic element (25) and each have a journal opposite that of the other branch and engaged in the yoke to form said second articulation, the folding arm (2) having a closed position in which it is retained between the side members (4, 54) by them,
the clasp being characterized in that it comprises a locking mechanism, arranged to keep the folding arm (2) in the closed position against any opening force, said mechanism comprising hooking members (30 , 31) on the mutually facing sides of the side members (4, 54) and of the branches (10), and in that said pins are projecting on each side of the yoke to form pushers (15) allowing a user to bring the branches (10) together by pressing on the pushers so as to unlock said mechanism by grasping the clevis (3) to open the clasp. Clasp according to claim 1, characterized in what the hooking members (30) of each branch are arranged in the vicinity of the yoke (3). Clasp according to claim 1 or 2, characterized in that the fastening members include each a support surface (32, 33) substantially perpendicular to the direction of arm opening leaflet. Clasp according to claim 3, characterized in that the hooking members have a hook protruding (30) on each branch (10) and a recess (31) formed in the corresponding spar (4, 54). Clasp according to claim 1, characterized in what the two arms (10) of the folding arm are connected to each other, in the vicinity of the yoke (3), by a tubular bar (23) containing a spring (25) and slidingly engaged in blind holes respective (22) of the two branches. Clasp according to claim 5, characterized in that, when the pushers (15) are not pressed, the two branches (10) are separated by an interval (E) greater than the length (L) of one of their pushers crossing the yoke (3), so that the yoke can be mounted and dismounted on the arm by bringing said branches. Clasp according to claim 5, characterized in the two arms (10) of the arms are parts separate which in the region of the second joint (13), are contiguous and assembled at the base by a rod joint joint (7). Clasp according to claim 1, characterized in what a middle part (11) of each branch (10) is laterally flexible. Clasp according to one of claims 1 to 8, characterized in that it is made of materials metallic, synthetic or composite. Clasp according to one of claims 1 to 8, characterized in that it has a single folding arm (2), the other end of the base (1) being arranged to be attached to another strand of the bracelet. Clasp according to one of claims 1 to 8, characterized in that it comprises two folding arms (2) each attached to one end of the base (51) and to a corresponding clevis (3), each arm having its own locking mechanism.

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