Abstract:
A bracelet clasp having two branches ( 1, 2 ) which are articulated to one another by a respective first one of their ends in order to make it possible to fold a first one of these branches over and/or into the second of said branches, and to unfold it in order to place it substantially in the extension of this second branch, while their respective second ends are intended to be connected to two ends of a bracelet. These two branches ( 1, 2 ) include mutual attaching structures ( 4, 10 ) for holding them in the folded position. The second end of the first articulated branch ( 1 ) includes linking structure ( 9 ) having parallel axes of articulation, one for connecting these linking structures to this first articulated branch ( 1 ) and at least a second one for connecting these linking structures ( 9 ) firstly to one end of the bracelet and secondly to an actuating member ( 18 ) for exerting a force capable of separating said mutual attaching structures ( 4, 10 ).

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application claims priority of European Patent Application No. 00810993.6 filed Oct. 26, 2000. 
     BACKGROUND OF THE INVENTION 
     The present invention relates to a bracelet clasp comprising two branches articulated to one another by a respective first one of their ends in order to make it possible to fold a first one of these branches over and/or into the second of said branches, and to unfold it in order to place it substantially in the extension of this second branch, while their respective second ends are intended to be connected to two ends of a bracelet, particularly a bracelet for a wrist watch, these two branches including mutual attaching means for holding them in the folded position. 
     PRIOR ART 
     This type of clasp is well known and exists in the form of a number of variants. In certain clasps, one end of the bracelet is connected to the branch of the clasp which is folded over or into the other branch by a cover the parallel lateral faces of which, which are on either side of the clasp in the closed position, include several pairs of transversely aligned and longitudinally spaced holes which are intended to receive the articulation pin at the end of the bracelet. These pairs of holes make it possible to adjust the length of the bracelet. In other clasps of this type, the end of the bracelet is articulated directly to the second end of this first branch so that, in the closed position, the bracelet hides the clasp. 
     In some bracelets of this type, the branches which are articulated to one another are made from stamped sheet metal and cover one another in the folded position. These branches are curved in order to match the shape of the wrist. The attachment of these branches to one another is a function of the radius of curvature of the curve. Given that these blades are made from sheet metal, it is possible to modify the radius of curvature of the curve in one direction or in the other in order to adjust the force of attachment between these blades. 
     A bracelet of this type has already been proposed, particularly in EP 0865742, in which the branches of the clasp are machined in a thicker and therefore more rigid material which allows no further adjustment of the attaching force by modifying the curves of these branches. With such a clasp, as the attaching force of the branches is no longer adjustable by the abovementioned simple means, it is therefore necessary to design precise and durable attaching means. This is why this clasp includes attaching elements which are added to the cover of the clasp and positioned inside it, firstly by means of their shape, which matches a portion of the inside of the cover, and, secondly, by a rod traversing these attaching elements and fixed to their two ends in the lateral faces of the clasp cover which are arranged on either side of the clasp. 
     This arrangement presents various drawbacks, one of which arises from the fact that this clasp has to be a clasp with a cover, since it is this which serves to receive the attaching elements. A further drawback arises from the fact that all the force required to separate the attaching elements is supplied directly by the user, so it is impossible to exceed a certain limit, to the detriment of the security of the closure. A further drawback arises from the fact that, as in the majority of clasps of this type, opening is obtained directly by pulling on the cover, as this offers a large gripping surface, which increases the risk of unexpected opening of the clasp. 
     SUMMARY OF THE INVENTION 
     The object of the present invention is to improve the closure security of this type of clasp against unexpected opening both on account of a catching and on account of a pulling force in the wake of a blow to the wrist or of violent impacts such as those which may arise when the user applauds or when he strikes his fist on a table, for example. The object of this invention is also to facilitate opening of the bracelet while still making it possible simultaneously to increase the force necessary for separating the attaching elements. A further object of this invention is to allow the branches of the clasp and the bracelet connected to these branches to pivot through at least 180° in order to obtain maximum opening of the clasp and thus to facilitate the passage of the hand through the bracelet. A yet further object of the invention is to make it possible to have a clasp with a base which is substantially identical when the clasp includes a cover and when it does not include one. 
     To this end, the subject of the present invention is a bracelet clasp of the abovementioned type. 
     One of the advantages of the proposed solution, in addition to those ensuing from the abovementioned objects, lies in its simplicity and the small number of parts required. Indeed, despite the various improvements of the clasp according to the invention, it may be observed that these are not obtained to the detriment of the simplicity and thus of the reliability of the solution proposed. For the user, handling of such a clasp is characterized by a high level of convenience, giving him a sensation of great security, which is enhanced by the appearance of the clasp, which constitutes a veritable small precision mechanism. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The appended drawing illustrates, diagrammatically and by way of example, an embodiment and several variant embodiments of the clasp which is the subject of the present invention. 
     FIG. 1 is an exploded perspective view of this embodiment; 
     FIG. 2 is a perspective view of the clasp of FIG. 1, with the branches folded; 
     FIGS. 3,  4  and  5  are three views through three different longitudinal sections of FIG. 2; 
     FIG. 6 is a view similar to FIG. 3, in the position in which the attaching elements are separated; 
     FIG. 7 is a sectional view similar to FIG. 5, in the position in which the articulated branches are unfolded; 
     FIG. 8 is an exploded perspective view of a variant embodiment of the clasp of FIGS. 1-7; 
     FIG. 9 is an assembled longitudinal sectional view of the clasp of FIG. 8, in the position in which the attaching elements are separated; 
     FIG. 10 is a perspective view of the variant element of FIGS. 8 and 9, in the position in which the articulated branches are unfolded; 
     FIG. 11 is a longitudinal sectional view of a variant embodiment with supplementary security means and means for adjusting the clasp according to the invention; 
     FIG. 12 is a longitudinal sectional view of a further variant embodiment of a clasp with supplementary security means and adjusting means; 
     FIG. 13 is a longitudinal sectional view of yet a further variant embodiment with supplementary security means; 
     FIGS. 14 and 15 are longitudinal sectional views of a final variant embodiment of this clasp, in the position in which the supplementary security means are separated and attached, respectively; and 
     FIG. 16 is a top view of FIG.  15 . 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The clasp illustrated by FIGS. 1 to  7  includes two curved branches  1 ,  2  which are articulated to one another by one of their respective ends about a rod  3 . These curved branches  1 ,  2  are preferably machined parts rather than stamped sheet metal, so that they are made relatively rigid. So that the clasp does not become over-thick, as shown in FIG. 2, the thickness of the branch  1  in the folded position is totally accommodated in a central recess  2   a  provided in the center of the branch  2 . 
     The bottom  2   b  of the recess  2   a  has an attaching stud  4 , the attaching face of which forms an angle α with the tangent to the circle centered on the articulation pin  3  of the curved branches  1 ,  2  and the radius of which corresponds to the distance between this pin and the point furthest from the attaching stud  4 . In order to accommodate the attaching members between the curved branches  1 ,  2 , the radius of curvature of the bottom  2   b  of the branch  2  diminishes slightly and then the curvature is reversed, thus providing a recess portion  2   a  which is slightly higher at the end of this branch  2  opposite the end articulated to the other branch  1 . 
     A rectangular recess  1   a  (FIG. 1) is provided at the end of the branch  1  opposite that articulated to the branch  2 , forming two parallel arms  1   b ,  1   c  on either side of this recess  1   a . Each arm includes two holes  5   a ,  5   b  and  6   a ,  6   b , respectively, which are aligned in pairs and intended to receive pivoting rods  7 ,  8  set into these holes  5   a ,  6   a  and  5   b ,  6   b , respectively. The pivoting rod  7  passes through an opening  9   a  in a linking and articulation member  9 , while the pivoting rod  8  passes freely through the cylindrical opening of a tube  10 , constituting the attaching element of the branch  1  of the clasp which is intended to attach against the inclined face of the attaching stud  4  of the branch  2  (FIG.  5 ). 
     The linking and articulation member  9  has a main part  9   c  of semicylindrical general shape oriented transversely to the branches  1 ,  2  of the clasp. The opening  9   a  for the pivoting rod  7  is provided in a semicylindrical appendix  9   b  which is off center relative to the main part  9   c , projecting under this main part  9   c.    
     The main part  9   c  of the linking member  9  is traversed by two openings  9   d ,  9   e  which are parallel to the longitudinal axis of this semicylindrical part  9   c  and to the opening  9   a  of the appendix  9   b . The opening  9   e  is intended for the linking and the articulation of one end of the bracelet (not shown) by a spindle  11  traversing a semicylindrical assembly element  12  which is oriented transversely and aligned with the linking member  9 . The spindle  11  is screwed into a second assembly element  13 , which is the counterpart of the element  12 . 
     The assembly element  12  carries an articulation rod  14  parallel to the spindle  11 , set in a blind hole of this element  12 , and the other end of which is intended to be fixed in a corresponding blind hole of the second assembly element  13 . This articulation rod  14  passes through the opening  9   d  in the linking member  9 , thus securing this linking member and the two assembly elements together. 
     This articulation rod  14  also passes freely through a member  15  for actuating the opening of the clasp, i.e. for separating the attaching members  4  and  10 , which is articulated about the second articulation pin of the linking member  9 , consisting of the axis of the opening  9   d.    
     This actuating member  15  includes two opening levers  16 ,  17 , each comprising a semicylindrical element  16   a  and  17   a , respectively, each traversed by an opening, of which only the opening  17   b  can be seen in FIG. 1, for the passage of the articulation rod  14 . The transverse distance separating the respective outer lateral faces of the two semicylindrical elements  16   a ,  17   a  is very slightly shorter than the width of the recess  2   a  of the branch  2  of the clasp, in order to allow the pivoting of these elements  16   a ,  17   a  about the articulation rod  14 . These levers  16 ,  17  are formed from two bearing elements  16   c  and  17   c , respectively, secured to the respective semicylindrical elements  16   a ,  17   a.  These bearing elements  16   c ,  17   c  extend outside the respective outer lateral faces of the semicylindrical elements  16   a ,  17   a  such that they bear on the upper face of the branch  2 , on either side of the recess  2   a , as illustrated in FIG.  3 . These two bearing elements extend in the opposite direction from the respective semicylindrical elements  16   a ,  17   a  relative to the longitudinal axis of the articulation rod  14 . Given that these bearing elements  16   c ,  17   c  extend laterally outside the semicylindrical elements  16   a ,  17   a , the assembly elements  12 ,  13  include a recessed part, of which the recessed part  13   a  of the assembly element  13  can be seen in FIG. 1, while the recessed part  12   a  of the element  12  can be seen in FIG.  3 . 
     A gripping member  18  is fixed between the two semicylindrical elements and serves for maneuvering the opening levers  16  and  17  by causing them to pivot about the articulation rod  14 . The angle of pivoting of these opening levers  16  and  17  is limited by the edges of the recessed parts  12   a ,  13   a.    
     The branch  2  of the clasp is secured to two elements  19 ,  20  in the form of a bracelet link which are aligned longitudinally with the assembly elements  12  and  13 , respectively, of the same shape which are secured to the branch  1  of this clasp (FIGS.  1  and  2 ). A stop  21 , also secured to the branch  2 , is located at an equal distance from the elements  19 ,  20 , between these elements. A spindle  22  extends between the elements  19 ,  20 , passing through the stop  21 . This spindle serves for connecting the branch  2  of the clasp to the other end of the bracelet (not shown). 
     As may be observed by examining FIG. 5 in particular, the engagement of the tube  10  pivoted on the rod  8  of the branch  1 , on the inclined face of the angle α relative to the tangent to a circle centered on the axis of the pivoting rod  3  between the two branches  1 ,  2  of the clasp, is obtained by subjecting the blade  1  to a pulling force, while the blade  2  is subjected to a compression force. As the two blades are slightly curved in order to match the shape of the wrist, these forces may be reflected in an elastic deformation of these blades  1 ,  2 , and as these blades are produced by machining in the mass and not simply from sheet metal, the force required for the attachment of the tube  10  onto the stud  4  may be relatively high, which makes it possible to guarantee satisfactory behavior in the event of impacts. Moreover, the presence of the tube  10  facilitates the elastic deformation of the blade  1  and also makes closure independent of the way in which pressure is exerted on this blade  1  during closure of the clasp. 
     This force required for attaching may be higher if opening of the clasp is facilitated by the mechanism of levers  16 ,  17  actuated by the gripping member  18 , reducing the force required during lifting of the branch  1  in order to release the tube  10  from the attaching stud  4 . Indeed, as may be observed in particular in FIG. 6, when the levers  16 ,  17  are pivoted about the articulation rod  14 , raising the gripping member  18 , the elements  16   c ,  17   c  of these levers bear on the upper surface of the branch  2  of the clasp, on either side of the recess  2   a  in which the branch  1  is embedded in the closed position, and form a lever arm which increases the force exerted on the rod  14  and therefore on the linking member  9  to which the end of the branch  1  is articulated. 
     Once the two branches  1 ,  2  of the clasp are separated, the semicylindrical appendix  9   b  of the linking member  9  allows the latter to turn about the attaching tube  10  such that it passes from a position in which it is to the left of the attaching tube  10  (FIG. 5) to a position in which it passes to the right of this same tube  10  (FIG.  7 ), allowing optimum opening of the clasp by a pivoting of at least 180° of the branch  1  relative to the branch  2  of the clasp and also a free pivoting of the links of the bracelet relative to the branches of the clasp. This is important: with this type of clasp, the ends of the bracelet are never separated from one another and it is only by an increase in the length of the bracelet following on from the pivoting of the blades  1 ,  2  that the hand is able to pass through the bracelet. It is therefore important that the bracelet should be able to pivot freely during opening of the branches  1 ,  2  and that the end links between the bracelet and the branches  1 ,  2  of the clasp are also free to pivot relative to these branches. This is made possible in the case of the clasp according to the invention by virtue of the linking member  9  which connects the end of the bracelet (not shown) to the branch  1  via the spindle  11  and which can itself turn freely through at least 180° about the pivoting rod  7 . 
     Mention may also be made of the fact that, in the open position of the clasp, illustrated in FIG. 7, no element of the clasp&#39;s mechanism projects from its inner face, so that the user cannot injure himself by passing his hand through the open bracelet or catch parts of garments and risk spoiling them. In fact, the attaching stud  4  projects on the upper face of the branch  2  of the clasp and the cylindrical attaching tube  10  is accommodated in the thickness of the branch  1 . 
     This linking member also allows the independent pivoting of the opening mechanism, consisting of the levers  16 ,  17  and the gripping member  18  of the rest of the clasp and of the bracelet, which reduces the risks of unexpected opening, particularly in the variant embodiment of the clasp with a cover, which will be described below. 
     The fact that the attaching tube  10  is mounted so as to pivot on the pivoting rod  8  makes it possible to reduce wear of this part as a consequence of the multiple attaching and separation operations to which it is intended to be subjected. Moreover, in the event of wear, it is easy to change this tube  10 . 
     A further advantage of this clasp arises from the fact that the lower face of the branch  2 , which is intended to abut against the wrist of the wearer, is closed and that the entire closure mechanism is located in the recess  2   a  of this branch  2  such that the risk of pinching hairs during closure of the clasp is reduced. 
     The variant illustrated in FIGS. 8 to  10  is distinguished from the embodiment in FIGS. 1 to  7  essentially by the fact that the linking member  9  of this embodiment consists of two distinct linking elements  23  and a cover  24  comprising an upper wall  24   a  and two parallel lateral walls  24   b ,  24   c.  The linking element  23  is traversed by two parallel openings  23   a ,  23   b  (FIGS.  8  and  9 ), corresponding to the openings  9   a  and  9   d,  respectively, of the linking member  9 . As may be seen, in particular, in FIG. 9, a spring bar  25  traverses the opening  23   b  of the linking element  23  of the linking member  23 ,  24 , and its ends engage in blind holes (not visible) provided in the inner faces of the lateral walls  24   b ,  24   c  of the cover  24 , forming the other linking element. These blind holes are similar to the blind holes  24   d  which are seen in FIG.  9  and which serve for connecting the bracelet (not shown) to the linking member  23 ,  24 . As shown by FIG. 9, when the linking elements  23 ,  24  of the linking member are assembled by the bar  25 , the upper face  23   c  of the linking element  23  is applied against the inner face of the upper wall of the cover  24 , immobilizing these two linking elements  23 ,  24  relative to one another, so that the member resulting from this assembly has the same functions as the linking member  9  of the embodiment in FIGS. 1 to  7 . Furthermore, the presence of the cover  24  makes it possible to adjust the length of the bracelet by virtue of the series of holes  24   d , something the linking member  9  does not make it possible to do. 
     Like the articulation rod  14  of FIGS. 1 to  7 , the bar  25  also allows the pivoting of the opening levers  66 ,  67  arranged on either side of the linking element  23  and which bear on the upper face of the branch  2  of the clasp. These levers work just like the levers  16  and  17  in FIGS. 1 to  7 . In this variant embodiment, the gripping member  68  integral with the levers  66 ,  67  has a shape other than but a function which is identical to that of the member  18  of the preceding embodiment. The rest of the clasp is quite similar to the clasp of FIGS. 1 to  7 , so there is no purpose in describing it further. 
     FIG. 10 shows the clasp with its branches  1  and  2  in the unfolded position, and it is possible to observe that the cover  24  and the linking element  23  can pivot integrally through at least 180° at the end of the branch  1  by turning about the attaching tube  10 . In this variant embodiment, the independence between the opening mechanism  66 ,  67 ,  68  and the cover  4  offers the advantage of preventing unexpected opening of the clasp by catching the cover  24 , since the latter, integral with the linking element  23 , pivots about the articulation rod  7  which does not play a role in the separation of the attaching tube  10  from the attaching stud  4 . 
     The clasps described hitherto include neither adjustment means nor security device. Indeed, various tests carried out on a series of prototypes corresponding to the clasp illustrated in FIGS. 1 to  7  have shown that it offers excellent security regarding behavior in the event of impacts and pulling forces. The design of this clasp, however, makes it possible for use to be made of means for adjusting the force required for closing it, and may also be associated with security devices. 
     FIG. 11 illustrates a variant embodiment of a clasp comprising two branches  26 ,  27  articulated to one another as in the preceding embodiments. The stud  4  of the lower branch is replaced in this case by a system of an adjustable stud  28  held on the branch  27  by a screw  29 . This adjustable stud is intended to engage with the attaching tube  30  pivoted on a transverse pivoting rod  31  integral with the branch  26 . 
     An adjusting member  32  which includes, at its periphery  32   a , for example four circular recesses of the same radius as the outer surface of the adjustable stud  28 , but the respective radial distance of which relative to the axis of the adjusting member  32  varies slightly relative to one another, makes it possible to adjust the penetration of this stud  28  in the trajectory of the attaching tube  30 , and consequently, the force of closure of the clasp. 
     This also includes a security closure comprising a linking and attaching link  33  traversed by two bores with parallel transverse axes, one receiving an articulation rod  34  integral with the branch  26  and the other receiving a spindle or a bar  35  for the articulation of the first link  36  of the bracelet. This linking and attaching link  33  also includes a transverse recess  37  providing an attaching finger  38  intended for hooking over a transverse attaching cylinder  39 . This linking and attaching link  33  is further secured to a gripping element  40  intended to pivot the link  33  clockwise in order to release the attaching finger  38  from the attaching cylinder  39 . An inclined face  26   a  integral with the branch  26  limits the degree of pivoting of the link  33  such that, by continuing to exert a pulling force on the gripping member  40 , it is possible to separate the attaching tube  30  from the stud  28  and to separate the two branches  26 ,  27  of the clasp. 
     As in the preceding embodiments, the linking link  33  with its two pivoting axes allows opening of the clasp to at least 180°, without restriction of rotation for the links  36  of the bracelet. 
     The variant embodiment of FIG. 12 differs from the preceding one only in that the adjustment of the attaching stud  41  is fixed on an adjusting member  42  mounted rotatably on the branch  27 , in an eccentric manner, such that, by turning the adjusting member  42 , for example with the aid of a screwdriver or a similar tool, it is possible to modify the penetration of the attaching stud relative to the attaching tube  30 . 
     The variant embodiment of FIG. 13 differs essentially from the preceding two in that there is a linking member  43  with three transverse axes of articulation, one about the pivoting rod  44  at the end of the branch  45  of the clasp, another for receiving an articulation spindle  46  of the bracelet, and the third for the articulation of an opening member  47 , integral with a gripping member  48 . This opening member  47  also includes a transverse rod  49  on which a tube  50  pivots, intended to be hooked in a housing  51  in an element  52  for connecting to the other end of the bracelet, and including, to this end, a bore  52   a . This connecting element  52  is integral with the branch  53  of the clasp. As may be observed, the base of the opening member  47  has an inclined part  47   a  intended to limit its degree of pivoting. This face has exactly the same function as the inclined face  26   a  in FIG.  11 . 
     Main closure is always provided by a tube  54  pivoted on a transverse rod  55  integral with the branch  45  of the clasp. This tube attaches on an attaching stud  56  integral with the branch  53 . 
     The variant embodiment of FIGS. 14 to  16  differs from the preceding ones firstly in that the pivoting axis of the attaching tube  58  is combined with that of the linking and attaching link  57 , while the first link  59  of one end of the bracelet is pivoted about the second articulation pin  60  of this linking and attaching link  57 . The attaching element  57   a  of this linking and attaching link  57  attaches to the end of a piston  61  which is subject to an elastic return member  62 . As shown in FIG. 15, when the attaching element  57   a  engages on the end of the piston  61 , its other end is applied against the attaching tube  58  and prevents it from pivoting about the pivoting rod  63 . 
     To hold this pivoting rod  63 , two hinges  64  are fixed to the end of the branche  65  of the clasp (FIG.  16 ), on either side of the attaching stud  69  of the attaching tube  58 .