0001 The present invention relates to wristwatches. It concerns, more particularly, watches formed of a case provided with a slide-way and a wristlet engaged in the slide-way and able to move in translation. Watches of this type are known, for example, from European Patent No. 0 264 874, GB Patent No. 2 217 577, U.S. Pat. No. 5,068,840 or Belgian Patent No. 545 237. Such a solution allows a wristlet with a single strand to be made. Moreover, the case may be moved on the wristlet, so as to place it in a position chosen by the person wearing the watch, in particular to facilitate reading the time. 0002 In these watches, the wristlet or watch strap is made of a flexible material, generally leather or fabric. This may result in rapid wear, due to the friction of the slide-way on the wristlet. However, if the case can move too easily along the wristlet, it is liable to move when worn, frequently obliging the person wearing it to put it back in place. 0003 The main object of the invention is to overcome these drawbacks. This object is achieved by the watch defined by claim 1. 0004 Particularly good results have been obtained using a strap made of a knitted thread, in particular a metal thread, for example defining a so-called Milanese structure. 0005 Tests have shown that the two rolls forming the wristlet can be obtained by permanently deforming the strap formed by bending, the longitudinal edges of the latter being in contact with its median portion. It is thus not necessary to weld or bond the edges of the strap to guarantee the shape of the wristlet. Moreover, the structure thereby obtained has great flexibility and rounded edges, making it more comfortable for the person wearing it. 0006 In the watch according to the invention, it is desirable for the wristlet to be easily moved in the slide-way when it is in an extended position, so as to be able to position it quickly. When the watch is being worn, however, it is preferable for the case to be able to slide only insofar as the person wearing it wishes. This is why, in an advantageous manner, the wristlet and the case are arranged so that, in the extended position, the wristlet can slide freely on the case, while in the bent position, the case can only be moved on the wristlet via the action of force which is higher the lower the radius of curvature of the wristlet. 0007 This feature may be obtained when the rolls define a resilient structure which forms rough portions intended to co-operate with the walls of the slide-way when the wristlet is bent. Thus, the rough portions, by co-operating with the walls of the slide-way, assure proper positioning of the case, without thereby blocking it. 0008 In known watches, the slide-way is formed of loops which define a rectangular opening delimited by walls on four sides. With such a structure, applied to a watch in which friction is defined by the rough portions of the wristlet on the walls of the slide-way, the latter is liable to prevent any movement of the watch when it is being worn. This is why, in an advantageous manner, the case is of generally parallelepiped shape, including in particular two large faces and two small faces, in which: 0009 one of the large faces, the top one, is provided with a crystal through which the time can be read; 0010 the other large face, the bottom one, forms one of the walls of the slide-way, and 0011 the two small faces extend beyond the large bottom face and form claws which constitute, with the bottom face, the walls of the slide-way. 0012 In order to assure comfortable wear, aesthetic appearance and longevity, both the wristlet and the case are made of metal. 0013 The invention also concerns a wristlet, in particular a watch wristlet, according to claim 10.

0014 Other advantages and features of the invention will appear from the following description, made with reference to the annexed drawing, in which: 0015 FIG. 1 shows a preferred embodiment of the watch according to the invention, seen from below; 0016 FIG. 2 is a cross-section of this watch along the line 11-11 of FIG. 1; 0017 FIGS. 3 and 4 illustrate the manufacturing steps of a wristlet according to the invention; and 0018 FIGS. 5 and 6 show schematically the way in which the case and the wristlet co-operate with the wristlet respectively in the open and closed position.

0019 The watch shown in FIG. 1 includes a case 10 and a wristlet 12, of width I, mounted so as to be able to slide, as will be explained with reference to FIG. 2. The latter is a cross-section of the watch of FIG. 1, shown on a substantially larger scale. 0020 Case 10 includes a middle part 14, a back cover 16, both made of stainless steel, and a crystal 18 made of a transparent material, which together define a housing 20 inside which is located a watch movement 22 carrying a dial 24 and hands 26. 0021 Case 10 is generally parallelepiped shape. It includes two large faces 10a and 10b, two small faces 10c and 10d and two medium faces 10e and 10f. 0022 Top face 10a is essentially formed of crystal 18 through which the time can be read. Bottom face 10b is defined by back cover 16. 0023 The two small faces 10c and 10d are arranged parallel to the edges of wristlet 12. They extend beyond bottom face 10b and from claws 28 which constitute, with the bottom face, the walls of a slide-way 30 in which wristlet 12 is engaged. Each claw 28 is provided with a raised portion 32, the raised portions facing each other, so as to prevent wristlet 12 from coming out of slide-way 30. 0024 As FIG. 3 shows, wristlet 12 is formed from a woven sheet 34 manufactured from a stainless steel thread, the diameter of which is comprised between 0.1 and 0.3 mm. The structure of the woven mesh is only shown schematically, to facilitate the drawing, since it is well known to those skilled in the art. The sheet 34 is cut into straps 36. 0025 The cutting operation causes the wire to be crushed on the edges 36a and 36b, which prevents the woven mesh from coming undone. These edges however have a relatively sharp structure, which is uncomfortable to touch. In the wristlet according to the invention, strap 36 is cut to a width L lightly greater than twice the width I of the wristlet (FIG. 2). 0026 In order to avoid this sharp structure, the two edges 36a and 36b are rolled across their entire length and held in shape by bending, in median portion 36c of the strap, thus forming two hollow scrolls or rolls 36d and 36e. 0027 Making rolls 36d and 36e causes a slight transverse deformation of median portion 36c, which bends slightly. The wristlet thereby made has a structure which is particularly pleasing to touch, not only because the sharp edges have been concealed, but also because all the surfaces are rounded. 0028 After edges 36a and 36b have been welded, wristlet attachments are secured, in a conventional manner, to the ends of the strap thereby formed, to allow the wristlet to be placed and removed on the arm of a wearer. 0029 The dimensions of wristlet 12 are chosen so that, when it is extended, it can slide freely in slide-way 30, as can be seen in FIG. 5. 0030 When the watch is secured to a wearer's wrist, the wristlet is bent longitudinally (FIG. 6). As a result the median portion of the wristlet comes into contact with back cover 16 of case 10 and rolls 36d and 36e with raised portions 32. The knitted structure, in which the mesh forms rough portions, generates friction of the wristlet on the case. The friction is greater the more wristlet 12 is bent. 0031 Because of the shape of rolls 36d and 36e, the curvature of the wristlet may be more or less pronounced, without posing any problem, since each of them can easily be resiliently deformed. 0032 The present invention may be subject to numerous variants. It is thus possible to make a watch with a round case. In such case, there is a certain rupture between the shape of the case in the portion housing the movement and that forming the slide-way. Such a solution can offer interesting aesthetic possibilities. 0033 A watch of this type may also be made of plastic material. It is then advantageous for the face of the wristlet intended to be in contact with the arm of the person wearing it to have a rough surface, which thus forms rough portions co-operating with the claws to perform the friction function. 0034 One may envisage making the wristlet from a knitted sheet manufactured by means of a plastic or synthetic thread of the semi-rigid type. In such case, the rolled longitudinal edges of the wristlets could be held in this position for example by welding or bonding. Of course, in such case, the watch case will preferably be made of plastic material to prevent the wristlet being worn out too quickly.