Horology: time measuring systems or devices – Cases
Patent
1998-06-01
1999-05-04
Miska, Vit
Horology: time measuring systems or devices
Cases
368281, 368309, G04B 3760
Patent
active
059011173
DESCRIPTION:
BRIEF SUMMARY
The present invention concerns a watch case including a water resistant casing formed of several stacked parts, which together define a housing intended to contain a watch movement, and a support device which keeps said casing parts assembled, the casing having a transparent upper face, the support device including at least one rigid clamp formed of an upper portion and a lower portion which are removably fixed to each other by assembly means arranged to produce gripping of the casing between the two portions of the clamp in an axial direction, perpendicular to said upper face.
The invention applies more particularly to watch cases whose external casing containing the movement is principally formed of parts made of hard materials which are thus difficult to machine, such as sapphire, the "hard metals" or metal carbides, ceramics or even mineral glass.
U.S. Pat. No. 4,390,288 discloses a watch case of this type, wherein the crystal and the back cover are made of hard material such as sapphire and pressed against the middle part by external clamps provided with gripping screws. The upper and lower surfaces of the middle part each have, for their junction respectively with the crystal or the back cover, a rabbet and a groove for a sealing gasket. The middle part also includes two pairs of horns for attaching a wristlet. It is clear that a middle part thus formed cannot be economically manufactured in a hard material. Moreover, the fact that the sealing gaskets are clearly visible through the crystal and the back cover made of sapphire is detrimental to the aesthetics of the watch case.
Another watch case of this kind is disclosed in CH Patent No 622 151 where it is mentioned that the use of hard scratch proof materials for making various parts of watch cases poses numerous manufacturing problems. Since machining of such materials is difficult, the design and execution of assembling the various parts of the case, the sealing and aesthetic appearance of the case, especially when transparent or translucent materials are used, require special solutions. Generally, one seeks to reduce to a minimum machining of recesses or holes, which is particularly expensive, and to use simple external shapes, which are easier to polish.
The watch case disclosed in CH Patent No 622 151 essentially consists of three parts stacked axially, namely a substantially flat metal back cover provided with four horns for attaching a wristlet, an annular middle part made of a hard material, and a crystal formed by an entirely flat sapphire plate. The middle part is fixed to the back cover by means of axial screws passing into holes in these two parts. Then the crystal, provided with a metallized strip along the edge of its lower face, is glued to the middle part so as to cover the heads of the screws and assure a water-tight connection. Sealing of the back cover is assured by a conventional annular sealing gasket housed in a recess of the metal back cover.
One drawback of this design obviously lies in the cost of machining through holes in the middle part. Moreover, the numerous machining operations necessary on the back cover prevent the economical manufacture thereof in a hard material, for example the same material as the middle part, which would be more aesthetically pleasing. If the material of the middle part is translucent, the screws which it contains and the sealing gasket can unfortunately be seen. Finally, the fact that the wristlet attachment horns are situated in the vicinity of the back cover is detrimental to the aesthetic appearance of the watch.
CH Patent No 632 374 discloses a watch case whose casing is formed of two parts made of transparent or translucent mineral material, one of which is a hollowed part forming the crystal and the middle part, and the other is a flat back cover assuring sealing of the case via a sealing gasket housed in a groove of the middle part. These two parts are held together by means of two opposite metal elements each having two horns for attaching a wristlet. Each element has an upper claw and
REFERENCES:
patent: 4390288 (1983-06-01), Arnoux
patent: 4464063 (1984-08-01), Goghiat
patent: 4620798 (1986-11-01), Scarzini
patent: 4696577 (1987-09-01), Muller et al.
patent: 4924453 (1990-05-01), Ray et al.
Comadur S.A.
Miska Vit
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