WATCH CASE WITH A BACK ALIGNED IN A PREDEFINED ANGULAR POSITION

Description

Technical field of the invention

[0001] The invention relates to the field of watchmaking, and in particular to the components of a watch case.

[0002] More particularly, the invention relates to a watch case comprising a bottom oriented in a predefined angular position. Technological background

[0003] Watch cases have a case middle on either side of which a glass and a back are fixed.

[0004] The caseback can be fixed to the caseband by screwing, by bayonet type assembly or by tight fitting by press mounting, i.e. by driving.

[0005] In the case of fixing the case back to the caseband by driving, a gasket is arranged in the caseband and is compressed radially by the case back against the caseband when the caseback is driven into the caseband. The gasket has the effect of giving the case a desired level of water and air tightness, as well as ensuring the mechanical strength of the assembly, as disclosed by document GB1042457A for example.

[0006] When it presents, on a visible surface, a pattern such as a brand logo, it is desirable that the background be oriented so that said pattern is aligned with respect to a vertical axis 6 o'clock - 12 o'clock, for reasons of perceived quality in particular.

[0007] The orientation of the back in relation to the caseband is generally carried out manually by adequately pre-positioning the back in relation to the caseband before press fitting, using visual markers on the caseband or the back, for example using a notch for the adjustment rod.

[0008] In the case of this type of fixing of the back to the caseband, the precision of the orientation of the backband therefore depends essentially on the skill of the operator carrying out the pre-positioning of the backband in relation to the caseband.

[0009] It is understood that the level of quality of the assemblies produced can vary significantly.

[0010] There is therefore a need to produce watch case assemblies in which the orientation of the back in relation to the case middle is controlled, so as to obtain a high and consistent level of quality. Summary of the invention

[0011] The invention solves the aforementioned drawbacks by proposing a solution making it possible to control the orientation of the back in relation to the caseband when it is fixed by tight fitting.

[0012] To this end, the present invention relates to a watch case comprising a back cover driven into a caseband by means of a gasket, the back cover comprising a body from which a lip extends radially, said body comprising an axial annular bearing surface and said lip comprising a radial annular bearing surface.

[0013] The case has an axial opening and has an axial annular bearing surface extending opposite the axial annular bearing surface of the body of the back, and a radial annular bearing surface bearing against the radial annular bearing surface of the lip.

[0014] The joint is interposed between the axial annular bearing surfaces of the caseband and the back, said axial annular bearing surfaces having peripheral profiles of complementary shapes, substantially circular, each comprising a first portion in the shape of an arc of a circle having a first radius R1, R2, and a second portion in the shape of an arc of a circle to which the first portion is connected, having a second radius r1, r2 whose value is less than that of the first radius R1, R2.

[0015] In particular embodiments, the invention may further comprise one or more of the following features, taken individually or in any technically possible combination.

[0016] In particular embodiments, the value of the second radius r1, r2 is greater than half the value of the first radius R1, R2.

[0017] In particular embodiments, the peripheral profile of the axial annular bearing surfaces of the middle and the back cover comprise first and second portions in the form of arcs of circles distributed alternately, one after the other.

[0018] In particular embodiments, the axial annular bearing surfaces of the caseband and the back cover are configured so that the arrows of the first and second portions in the form of circular arcs are separated from each other by an angle of 60 degrees.

[0019] In particular embodiments, the axial annular bearing surfaces of the caseband and the back cover are configured so that the arrows of the portions in the shape of circular arcs define segments of intersecting lines at a point materializing the center of the opening.

[0020] In particular embodiments, the shape defined by the peripheral profile of the axial annular bearing surfaces is convex.

[0021] In particular embodiments, the seal has a profile complementary to those of the axial annular bearing surfaces of the case and the back. Brief description of the figures

[0022] Other characteristics and advantages of the invention will appear on reading the following detailed description given by way of non-limiting example, with reference to the appended drawings in which: there figure 1 represents a sectional view along a radial plane of a part of a box according to a preferred embodiment of the invention; the Figures 2 and 3 respectively represent a top view of a bottom of the box of the figure 1 and a bottom view of a case middle of the figure 1 . Detailed description of the invention

[0023] The present invention relates to a watch case 10, a portion of which is shown in the sectional view along a radial plane of said watch case 10 of the figure 1 .

[0024] The watch case 10 comprises a caseband 20 of generally circular shape comprising an axial opening 21 receiving a glass (not shown) at one of its ends called the “upper end”, opposite a back cover 30 driven into another end of said caseband 20, called the “lower end”. The glass, the back cover 30 and the caseband 20 define a volume inside which a watch movement is arranged, in a manner known to those skilled in the art.

[0025] The watch movement and the other watch components used in a watch case 10 being known to those skilled in the art and not forming part of the present invention, they are not shown in the figures, nor described below.

[0026] The bottom 30 has a generally circular shape and comprises a body 31 from which a lip 32 extends radially forming a peripheral shoulder relative to said body 31. More precisely, as shown in the sectional view of the figure 1 , the shoulder is formed by an axial annular surface 310 of the body 31 and by a radial annular surface 320 of the lip 32.

[0027] Said axial 310 and radial 320 annular bearing surfaces are provided to constitute bearing surfaces as described in more detail below.

[0028] The axial and radial directions are defined in the present text relative to the watch case 10, and in particular relative to the opening 21 of the caseband 20. In a manner known in the field of watchmaking, the axial direction extends from one to the other of the upper and lower ends of the caseband 20 and the radial direction extends perpendicular to said axial direction.

[0029] At its lower end, the middle part 20 has an axial annular bearing surface 200 extending opposite the axial annular bearing surface 310 of the bottom 30. This axial annular bearing surface 200 is connected to a radial annular bearing surface 201 bearing against the radial annular bearing surface 320 of the lip 32. The radial annular bearing surface 201 of the middle part 20 forms an end surface of said middle part 20 in the preferred embodiment of the invention shown in the figures.

[0030] An annular seal 40 is advantageously interposed between the axial annular bearing surfaces 200 and 310 respectively of the middle part 20 and the bottom 30, and is compressed by one and the other of said axial annular bearing surfaces 200 and 310, as shown in the figure 1 This compression of the seal 40 makes it possible to provide water and air tightness to the watch case according to a desired level and generates a tightening force allowing the bottom 30 to be fixed to the middle 20.

[0031] Advantageously, the axial annular bearing surfaces 200 and 310 of the middle part 20 and the bottom 30 are of complementary shapes, and do not have a shape of revolution. On the contrary, although it has a substantially circular shape, as shown in Figures 2 and 3 , their respective peripheral profile comprises a first portion in the shape of an arc of a circle having a first radius R1, R2 and a second portion in the shape of an arc of a circle connected to the first portion and having a second radius r1, r2 less than the first radius R1, R2. The first portions of the middle 20 and the bottom 30 are intended to rest opposite each other, just as the second portions of the middle 20 and the bottom 30 are intended to rest opposite each other.

[0032] The first and second rays R1, R2 and r1, r2 are represented on the Figures 2 and 3 by arrows.

[0033] The term “peripheral profile” defines in the present text the projection of the axial annular bearing surfaces 200 and 310 respectively of the middle 20 and the bottom 30 onto a plane P perpendicular to the axial direction and parallel to the radial direction. In other words, the plane P is parallel to the radial annular bearing surfaces 201 and 320 of the middle 20 and the lip 32, as shown in the Figures 1 and 2 .

[0034] The term "complementary" means that the shapes of the axial annular bearing surfaces 200 and 310 are identical, only the dimensions of said axial annular bearing surfaces varying relative to each other.

[0035] These conformations of the bottom 30 and the middle 20, visible respectively on the Figures 2 and 3, make it possible to guarantee the performance of the watertightness of the watch case 10 to water and air by preserving the peripheral profile of the axial annular bearing surfaces 200 and 310 from any angle, broken line or edge, etc., by the continuity of the curved surfaces, while playing a foolproof role in the orientation of the back cover 30 with respect to the caseband 20 when they are assembled together.

[0036] Indeed, to drive the back cover 30 into the middle part 20, it is then only possible to orient the back cover 30 in a position in which the shapes of the axial annular bearing surfaces 200 and 310 are aligned with each other, that is to say a position in which the first portions are arranged opposite each other and the second portions are arranged opposite each other.

[0037] Advantageously, to guarantee a high level of water and air tightness, the shape defined by the peripheral profile of the axial annular bearing surfaces 200 and 310 of the middle 20 and the back 30 is convex, in the sense that said axial annular bearing surfaces 200 and 310 are respectively located entirely on the same side of a tangent line applied at any point of their peripheral profile. The term “convex” is used here in its definition specific to the field of geometry.

[0038] Preferably, in a preferred embodiment of the invention, the values ​​of the second radii r1, r2 of the second portions of the axial annular bearing surfaces 200 and 310 of the middle 20 and the bottom 30 are respectively greater than half the values ​​of the first radii R1, R2 of the first portions of the middle 20 and the bottom 30.

[0039] This characteristic contributes to the continuity of the curved surfaces and therefore to preventing the shape of the peripheral profile of the axial annular bearing surfaces 200 and 310 from having a broken line angle or edge.

[0040] In particular, the difference between the values ​​of the first and second radii R1 and r1 of the axial annular bearing surface 200 of the middle part 20, as well as the difference between the values ​​of the first and second radii R2 and r2 of the axial annular bearing surface 310 of the bottom 30, is of the order of a few millimeters or tenths of millimeters.

[0041] As shown by the Figures 2 and 3, the shape of the axial annular bearing surfaces 200 and 310 of the middle 20 and the back 30 comprises several first and second portions in the form of arcs of circles distributed alternately, one after the other. In other words, two successive first portions in the form of an arc of circle are connected to each other by a second portion in the form of an arc of circle and two successive second portions in the form of an arc of circle are connected to each other by a first portion in the form of an arc of circle.

[0042] In the preferred embodiment of the invention, the axial annular bearing surfaces 200, 310 of the caseband 20 and the back cover 30 are configured so that the arrows of the first and second portions in the form of arcs of circles are separated from each other by an angle of 60 degrees. The concept of the arrow of an arc of a circle is known to those skilled in the art. This angle easily acts as an effective error-proof device for orienting a back cover in a caseband. An orientation defect would be quickly perceptible and correctable for the operator.

[0043] In other words, the axial annular bearing surfaces 200 and 310 of the middle 20 and the back 30 comprise three first portions and three second portions in the form of arcs of circles alternately distributed one after the other.

[0044] Furthermore, the arrows of the portions in the form of arcs of circles define segments of intersecting lines at a point materializing the center of the opening 21.

[0045] Preferably, the seal 40 has a peripheral profile complementary to those of the axial annular surface 310 of the lip 32 and the axial annular surface 200 of the middle 20.

[0046] On the figure 1 , the seal 40 has been shown with a rectangular cross-section. In other embodiments of the invention, it may have a circular or other cross-section.

[0047] Advantageously, the radial annular bearing surface 320 of the base 30 may include an annular excess thickness 321 to receive the seal 40 in support, as shown in Figures 1 and 3 . Thus, the radial annular bearing surface 201 of the middle part 20 rests against an end portion of the radial annular bearing surface 320 of the bottom 30.

[0048] The bottom 30 and the middle 20 may be made of any suitable material, for example metal, such as steel or precious metal, ceramic, etc.

[0049] The seal 40 may also be made of any suitable material, such as polymer, having a hardness of 75 ± 10 Shore D.

[0050] More generally, it should be noted that the methods of implementation and embodiment considered above have been described as non-limiting examples, and that other variants are consequently conceivable.

[0051] For example, it is conceivable that the peripheral profile of the axial annular bearing surfaces 200 and 310 of the middle 20 and the back 30 has more than two portions in the form of arcs of circles whose radii are different and / or that it comprises more than three first portions and more than three second portions in the form of arcs of circles alternately distributed one after the other.

Claims

1. Watch case (10) comprising a back (30) driven into a middle (20) by means of a joint (40), the back (30) including a body (31) from which radially extends a lip (32), said body (31) comprising an axial annular shoulder (310) and said lip (32) comprising a radial annular shoulder (320), the middle (20) including an axial opening (21) and has an axial annular shoulder (200) extending opposite the axial annular shoulder (310) of the body (31) of the back (30), and a radial annular shoulder (201) resting against the radial annular shoulder (320) of the lip (32), the joint (40) being interposed between the axial annular shoulders (200, 310) of the middle (20) and of the back (30), and where the axial annular shoulders (200, 310) of the middle (20) and of the back (30) have peripheral profiles of complementary shapes, substantially circular, comprising one and the other, a first circular-arc-shaped portion having a first radius (R1, R2), and a second circular-arc-shaped portion to which is connected the first portion, having a second radius (r1, r2) the value of which is lower than that of the first radius (R1, R2).

2. Watch case (10) according to claim 1, wherein the value of the second radius (r1, r2) is greater than half the value of the first radius (R1, R2).

3. Watch case (10) according to one of claims 1 or 2, wherein the peripheral profile of the axial annular shoulders (200, 310) of the middle (20) and of the back (30) comprise a plurality of first and second circular-arc-shaped portions alternately distributed, one after another.

4. Watch case (10) according to one of claims 1 to 3, wherein the axial annular shoulders (200, 310) of the middle (20) and of the back (30) are configured so that the sagittas of the first and second circular-arc-shaped portions are separated from one another by an angle of 60 degrees.

5. Watch case (10) according to one of claims 1 to 4, wherein the axial annular shoulders (200, 310) of the middle (20) and of the back (30) are configured so that the sagittas of the circular-arc-shaped portions define segments of intersecting lines in a point materialising the centre of the opening (21).

6. Watch case (10) according to one of claims 1 to 5, wherein the shape defined by the peripheral profile of the axial annular shoulders (200, 310) is convex.

7. Watch case (10) according to one of claims 1 to 6, wherein the joint (40) has a profile complementary to those of the axial annular shoulders (200, 310) of the middle (20) and of the back (30).