System for connecting a bracelet to a watch case

A system connects a bracelet to a watch case by a link. The watch case includes a caseband and a back cover. The link includes a first hollow element and a second element partly nesting in the first hollow element. The first hollow element carries a first device to fasten to the watch case. The second element carries a second device to fasten to an adjacent bracelet link. The watch case includes a mechanical device arranged to pivot the first hollow element so that the first hollow element is pressed against the caseband of the watch case.

This application claims priority from European Patent Application No. 12188014.0 filed Oct. 10, 2012, the entire disclosure of which is incorporated herein by reference.

FIELD OF THE INVENTION

The present invention concerns a system for connecting a bracelet or strap to a watch case including external elements made of a hard material such as a ceramic. More specifically, the present invention concerns a link arranged to connect a bracelet or strap to a watch case, said link comprising a first hollow element and a second element nesting in the first element, the first hollow element carrying a first means of fastening to the case and the second element carrying a second means of fastening to an adjacent link of the bracelet.

BACKGROUND OF THE INVENTION

Very generally speaking, the invention concerns the field of watch bracelets made of a hard material such as ceramic material and intended to be assembled to watches whose case includes an exterior made of hard material.

These structures have certain limits as to their application precisely because of the techniques used to manufacture them. Indeed, exterior parts made of hard materials, for example of ceramic material, are obtained by methods comprising a moulding step followed by a sintering step. During the sintering operation, these parts are subject to shrinkage, i.e. they undergo a significant reduction in volume under the combined action of heat and pressure. This shrinkage may represent more than 30% of the initial volume of the parts. Commonly employed methods currently enable these parts to be manufactured with tolerances on dimensions of around 0.5 to 1%, since the sintering step makes it difficult to obtain lower tolerances. It may be noted that these tolerances fluctuate according to the batches of raw material used.

By way of example, manufacturing tolerances involved by sintering operations may result in uncertainty of around 0.2 mm over the length of a 3 centimeter ceramic watch case. Given that ceramic watches are in the high end of watchmaking production, such uncertainties are difficult for manufacturers to accept.

To overcome this problem, the most commonly used solution for taking up play between the various ceramic elements used to make the watches consists in carrying out manual machining after the sintering step. However, faced with the increasing demand of clients for ceramic timepieces, manual machining steps have become more and more laborious given the number of timepieces to be treated. Further, manual machining steps are made even more difficult as the complexity of the geometry of the watch cases continues to increase.

It will be noted that the tolerance problem caused by sintering operations becomes more inconvenient the larger the dimensions of the external parts to be manufactured. In particular, these manufacturing tolerances have a detrimental effect on watch cases whose dimensions are generally greater than those of the bracelet links. It will also be clear that the more the manufacturers of ceramic watches wish to make bracelet links of large dimensions, the more difficulty they have in forming satisfactory attractive joins between the watch case and the bracelet or between the bracelet links.

SUMMARY OF THE INVENTION

It is an object of the present invention to overcome the aforementioned drawbacks in addition to others by providing aesthetically enhanced timepieces.

The present invention therefore concerns a system for connecting a bracelet to a watch case by means of a link, the watch case comprising a caseband and a back cover, the link comprising a first hollow element and a second element partly nesting in the first hollow element, the first hollow element carrying a first means of fastening to the watch case and the second element carrying a second means of fastening to an adjacent bracelet link, characterized in that the watch case includes a mechanical device arranged to pivot the first hollow element about a transverse axis to the longitudinal direction of the bracelet, and to press the first hollow element against the watch case.

As a result of these features, the present invention provides a system for connecting a bracelet to a watch case by means of a link which enables the position of the bracelet to be adjusted relative to the watch case. It is therefore possible to overcome the inherent problems of manufacturing tolerances and to obtain an uninterrupted join between the bracelet and the watch case without having to manually finish the external parts, which is advantageous from an aesthetic and economical point of view.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention proceeds from the general inventive idea which consists in providing a system for connecting a bracelet to a watch case by means of a link, said system comprising means which enable the link to be pressed against the watch case. Since it is possible to bring the end link of the bracelet closer to the watch case, any play between the bracelet and the watch case inherent to the sintering manufacturing technique can be compensated for and an uninterrupted join can be obtained between the bracelet and the watch case, which is very advantageous from an aesthetic point of view.

FIG. 1shows a wristwatch according to the prior art designed as a whole by the general reference numeral1. This wristwatch1includes a ceramic bracelet2connected to a watch case4which is also made of ceramic. It is noted inFIG. 1that, on both sides of watch case4, there is play, noted d1and d2, at the join between watch case4and the first links6of bracelet2.

As explained in the introductory part of this Patent Application, these plays d1and d2occur because of the manufacturing tolerances of watch case4and of links6of bracelet2. Indeed, the manufacturing tolerances result in dimensional variations in the various external elements causing discontinuities to appear at the join between bracelet2and watch case4. These discontinuities are unattractive, not least because they reveal the means8of fastening bracelet2to watch case4.

The present invention overcomes this problem by providing a link having a particular structure for establishing the play-free mechanical connection between the bracelet and the watch case.

FIG. 2is a cross-section, along the median axis of the bracelet, of the end link which enables the bracelet to be connected to the watch case; andFIG. 3is an exploded perspective view of the mechanical device for moving the link arranged to connect the bracelet to the watch case closer to the watch case.

Designated as a whole by the general reference numeral10, the link according to the invention includes a first hollow element12and a second element14partly nesting inside first hollow element12. Link10is provided for connecting a bracelet, whose first link16is shown in the drawing, to an external element which at least partially defines a watch case18. Watch case18includes a middle part20extended in the longitudinal direction of the bracelet by horns22in each of which a hole24is made. Watch case18is conventionally delimited on the bottom by a back cover26.

According to the invention, the first hollow element12carries a first means28of fastening to watch case18and second element14carries a second means30of fastening to the adjacent bracelet link16. More specifically, second element14takes the form of a plate32of generally rectangular shape which, on the watch case18side, is provided with a hollow cylindrical hinge34allowing a fastening pin36, the role of which will be described below, to pass through, and which, on the bracelet side, is provided with an ordinary means of fastening to the adjacent bracelet link16, such as hinge pins38, used in conjunction with an ordinary type of bar (not shown).

The first hollow element12forms an envelope of substantially trapezoidal cross section delimited by a front face40, a rear face42and two lateral faces44. A housing46is arranged in first hollow element12to enable second element14to slide inside the envelope. Housing46passes right through the first hollow element12and, at the front, opens out in the front face40side and at the rear, in the rear face42side of first hollow element12. Housing46is sized so that the hinge pins38of plate32project from first hollow element12. Finally, the first means28of fastening first hollow element12to watch case18includes a bore48which opens out in housing46and which is made in lateral faces44of first hollow element12, transversely to the longitudinal direction of the bracelet. This bore48is provided for receiving fastening pin36.

As seen particularly inFIG. 2, the profile of the front face40of first hollow element12matches the contour of caseband20of watch case18. In order to start assembling link10to watch case18, first of all, second element14is inserted into first hollow element12so that hinge pins38of plate32project from first hollow element12. Next, first hollow element12is slid between the horns22of watch case18. When this assembling step is finished, the holes24made in horns22, bore48machined into first hollow element12and hollow cylindrical hinge34are all aligned. To finish the assembly, fastening pin36merely has to be passed in succession through hole24of one of horns22, then through bore48and hollow cylindrical hinge34until fastening pin36emerges in hole24of the other horn22. To ensure a good coupling between link10and watch case18, fastening pin36has, at one end thereof, an increased diameter50and at the other end, a threaded hole for screwing in a screw52which locks fastening pin36.

This assembly is supplemented by a mechanical adjusting device comprising one and preferably two adjusting screws54. Adjusting screws54are each screwed into a threaded hole56made in the bottom face58of back cover26on the side of the user's wrist. Screws54comprise a head60which is embedded in the bottom face58of back cover26of watch case18and extended by a threaded shank62. The screws cooperate, via head60thereof, with a surface64of complementary shape arranged in first hollow element12as described below.

To adjust the position of link10with respect to watch case18and to compensate for any play between these two elements, the following steps are performed. Adjusting screw54is accessible through threaded hole56which ends in the bottom face58of back cover26of watch case18. Adjusting screw54is screwed in so that it moves in translation from bottom to top along arrow A in threaded hole56. Via the head60thereof, adjusting screw54presses on the opposite surface64arranged in first hollow element12so as to pivot said first hollow element12anti-clockwise along arrow B. In pivoting in this manner, first hollow element12moves closer to watch case18. Adjusting screw54ceases to be screwed in when the front face40of first hollow element12matches the contour of caseband20of watch case18. It will be clear that by screwing in adjusting screw54farther or less far, the position of first hollow element12can be very precisely adjusted with respect to caseband20of watch case18. Moreover, a captive adjustment is obtained.

It goes without saying that this invention is not limited to the embodiment that has just been described and that various simple alterations and variants can be envisaged by those skilled in the art without departing from the scope of the invention as defined by the claims annexed to this Patent Application. In particular, it will be clear that, although described with reference to a bracelet link and a watch case at least partially made of ceramic material, the present invention may be applied in an identical manner to links and to cases made of another hard material, such as steel.