CH718724A2 - Watch box fitted with a crystal. - Google Patents

Abstract

The watch case according to the invention comprises an opening (6), a crystal (3) closing the opening, a peripheral bearing surface (9) bordering the opening, a crystal notch (7) surrounding the bearing surface and the opening , and a gasket (5) surrounding the crystal and compressed radially between the crystal (3) and the notch (7). The seat (9) has a peripheral groove (13) adjacent to the notch (7), and the seal (5) is received in the groove (13) so that its lower edge is positioned at least 80 microns lower than the seat device (9).

Description

The present invention relates to a watch case comprising an opening, a crystal closing the opening, a peripheral bearing surface bordering the opening, a notch of glass surrounding the bearing surface and the opening, and a seal surrounding the crystal and compressed radially between the crystal and the notch, the seal comprising a lower edge and an upper edge. The present invention relates more particularly to such a watch case in which the thickness of the crystal is less than 1.1 mm, the crystal being made of a hard material (mineral glass, sapphire, etc.).

PRIOR ART

[0002] Mineral glass and sapphire are the materials of choice for producing quality watch crystals. In fact, these materials in particular show excellent resistance to abrasion. In addition, their solidity and their high rigidity offer the possibility of using thin crystals (in other words, crystals whose thickness is less than 1.1 mm), which makes it possible in particular to reduce the thickness of the assembled watch cases. . Thin and rigid crystals also have the advantage of better transmitting sound.

[0003] Various techniques are known for allowing the fitting of a crystal of hard material on a watch case. One of these techniques consists of driving the ice out of a seal previously inserted into a notch of ice surrounding the opening of the watch case. The seal has a double function, it holds the glass in place and it seals by radial compression of the seal between the glass and the notch. The technique of driving on gasket is the preferred technique for thick glass (thickness greater than 1.1mm).

[0004] On the other hand, it is considered that the technique of driving in on a joint is not suitable for the installation of thin glass. Indeed, with this type of assembly, it is in principle necessary to provide a minimum contact height between the inner face of the seal and the side of the glass. The thickness of the ice should therefore be at least equal to this minimum contact height. On the other hand, the fact of compressing the seal radially during driving in causes it to extend in the direction of the height. However, for aesthetic reasons, the seal should not protrude above the glass after assembly. It will therefore be understood that the height of the uncompressed seal must be chosen small enough so that the seal remains less high than the glass after assembly. A seal whose dimensions are suitable for driving out thin ice will therefore have a height which is barely greater than its width. Due to its shape, this seal will tend to roll up on itself when driving out. It is very difficult to chase ice on such a joint, without the latter being injured or crushed.

BRIEF DESCRIPTION OF THE INVENTION

An object of the present invention is to remedy the drawbacks of the prior art which have just been explained. The present invention achieves this and other objects by providing a watch case according to appended claim 1.

According to the invention, the bearing has a peripheral groove adjacent to the notch, and the seal is received in the peripheral groove so that the lower edge of the seal is positioned at least 80 microns below the peripheral bearing. It will be understood that the presence of the groove makes it possible in particular to use a seal whose height after assembly is greater than the thickness of the glass, without the seal protruding above the glass.

According to an advantageous embodiment, the watch case of the invention is the case of a striking watch. As already mentioned, a thin and rigid ice transmits sound better than a thicker ice. The invention therefore makes it possible to provide a striking watch case which has the advantage of being waterproof.

BRIEF DESCRIPTION OF FIGURES

Other characteristics and advantages of the present invention will appear on reading the following description, given solely by way of non-limiting example, and made with reference to the accompanying drawings in which: Figure 1 is a partial sectional view of the bezel of a watch case according to a particular embodiment of the invention; Figure 2 is a partial sectional view of the bezel of Figure 1, the bezel being shown without the crystal and without the gasket; FIG. 3 is a partial cross-sectional view of the bezel of FIGS. 1 and 2 in progress, before fitting the glass by driving it onto the seal.

DETAILED DESCRIPTION OF EMBODIMENTS

The attached Figure 1 is a partial sectional view of the bezel of a watch case according to an exemplary embodiment of the invention. According to the illustrated embodiment, the watch case is formed of several component parts, including a detachable bezel (referenced 1), a watch crystal (referenced 3) and a seal (referenced 5). Crystal 3 is mounted in bezel 1 using seal 5. The watch crystal in the example shown is curved. It thus has an outer face which is convex and an inner face which is generally concave, except at the location of a narrow peripheral strip (referenced 11), where it is flat. It will however be understood that, in accordance with other embodiments, the glass could be completely flat. Whether curved or flat, the ice usually still has two bevels, the cumulative height of which typically corresponds to substantially 40% of the total height of the ice.

Still referring to Figure 1, we can still see that the bezel 1 has an opening (referenced 6), and a notch (referenced 7) which is arranged concentrically around the opening. The bezel 1 further comprises a peripheral bearing surface (referenced 9) which extends between the notch 7 and the edge of the opening 6. It can also be seen that the opening 6 of the bezel 1 is covered by the crystal 3 , and that the flat peripheral strip of the glass bears on the bearing surface 9. It can also be seen on the one hand that the seal 5 is compressed radially between the side of the glass 3 and the notch 7, and on the other except that its upper edge is flush with the top of the bezel 1. In the example shown, the seal 5 is of substantially rectangular section, and in a manner known per se, it can be produced for example by injection of elastomer ( TPEE) or polymer (PA or PTFE).

Figure 2 is a partial sectional view similar to that of Figure 1, but in which the ice and the seal have been omitted to facilitate understanding. Referring to this figure, it can be seen that the bearing surface 9 has a peripheral groove (referenced 13) which is backed against the notch 7. It can be seen that in the illustrated embodiment the groove 13 has a flat bottom, and that its inner edge is bevelled. It will however be understood that according to other embodiments, the bottom of the groove could not be flat and/or the inner edge of the groove could be straight. Still referring to Figure 2, we can still see that the outer edge of the groove 13 has a corner stitching (or corner stitching) referenced 15.

[0012] Figure 3 is a partial sectional view similar to those of Figures 1 and 2, but showing the watch case being assembled, at a time after the installation of the seal 5, but before the installation ice by flushing out the gasket. It can be seen that the latter is supported by its outer side against the notch 7, while its lower edge is placed at the bottom of the groove 13. Although the notch 7 and the seal 5 have substantially the same height, the upper edge of the seal is below the upper part of the bezel 1, due to the insertion of the seal in the groove 13. We can still see that the seal 5 has two chamfers (not referenced) facing its inner side. It will be understood that the fact of providing two chamfers rather than a single one makes the upper and lower edges of the seal symmetrical, which reduces the risk of error when installing the glass.

[0013] An elastomer or polymer seal is easily deformable, but not very compressible. This is the reason why, if we compare FIG. 3 and FIG. 1, we can see that the effect of the driving out of glass 3 on seal 5 is twofold. On the one hand, the seal 5 is compressed radially between the glass 3 and the notch 7, and on the other hand its height is increased. Moreover, as the lower edge of the seal is retained in the groove 13 and therefore cannot be lowered any further, it is the upper edge of the seal which rises. As shown in Figure 1, once the glass is in place, the upper edge of seal 5 is flush with the top of the bezel.

As already mentioned, the outer edge of the groove 13 has a corner stitching. The corner stitching 15 contributes to facilitating the driving of the glass 3 onto the seal 5. Indeed, when the glass 3 is driven onto the elastic seal 5 from the top, its bevelled edge scrapes the inner side of the seal and pushes the lower part of the latter down. This phenomenon causes the temporary appearance of a bead of material which is likely to prevent the ice from being driven to the bottom. Thanks to the presence of the puncture 15, the glass can be lowered completely inside the seal by pushing the bead of material into the puncture.

[0015] It will also be understood that various modifications and/or improvements obvious to a person skilled in the art can be made to the embodiments which are the subject of the present description without departing from the scope of the present invention defined by the appended claims.

Claims (7)

1. Watch case comprising an opening (6), a glass (3) closing the opening, a peripheral bearing (9) bordering the opening, a notch of glass (7) surrounding the bearing and the opening, and a gasket (5) surrounding the crystal and compressed radially between the crystal (3) and the notch (7), the gasket (5) comprising a lower edge and an upper edge; characterized in that the seat (9) has a peripheral groove (13) adjacent to the notch (7), and in that the seal (5) is received in the groove (13) so that the lower edge of the seal is positioned at least 80 microns, preferably at least 100 microns, lower than the peripheral bearing (9). 2. Watch case according to claim 1, characterized in that it is formed of several component parts, and in that the opening (6), the peripheral surface (9) and the notch (7) are formed in the same constituent part (for example the bezel (1), the caseband, the back, etc.) 3. Watch case according to claim 1 or 2, characterized in that the seal (5) has an "I" shaped section. 4. Watch case according to any one of claims 1, 2 and 3, characterized in that the crystal (3) is round in shape. 5. Watch case according to one of the preceding claims, characterized in that the base of the outer flank of the peripheral groove (13) is dug with a lateral recess (corner stitch) (15) which runs through the groove ( 13) following the intersection between said outer flank and the bottom of the groove. 6. Watch case according to one of the preceding claims, characterized in that the crystal (3) is a thin crystal whose thickness is less than or equal to 0.7 mm. 7. Watch case according to one of the preceding claims, characterized in that the case is that of a striking watch.