US3676997A - Structure for sealing a watch crystal in a waterproof watch - Google Patents

Abstract

A watch crystal is sealed into a watch by means of an annular gasket of a relatively hard material such as a synthetic resin or soft metal. The parts comprising the seal are so dimensioned that the crystal seats in the gasket in an interference fit and the gasket fits in the case body in an interference fit. Such gaskets, while providing an effective seal even when subjected to high pressure, have long life, and hold the crystal sufficiently strongly so that a bezel is not needed.

Description

United States Patent Fujimori [45] July 18, 1972 [54] STRUCTURE FOR SEALING A WATCH 254,004 4/1948 Switzerland ..58/91 CRYSTAL IN A WATERPROOF WATCH 282,140 4/1952 Switzerland ....58/90 R 296,071 l/l954 Switzerland ..58/9] Inventor: Ymhhki Fujimori, Suwa, Japan 343,948 2/1960 Switzerland ..58/91 73 A K b kl ssrgnee Jalaulshl Kaisha Suwa Seikosha, Tokyo, Primary Examiner stephen J Tomsky Assistant ExaminerGeorge H. Miller, Jr. [22] Filed: Aug. 16, 1971 Attorney-Alex Friedman et al. [2!] App]. No.: 171,871 [57] ABSTRACT A A watch crystal is sealed into a watch by means of an annular Q Foreign Application Priority Data gasket of a relatively hard material such as a synthetic resin or Aug: [7, 1970 Japan ..45/71598 soft metal. The parts comprising the seal are so dimensioned 4 that the crystal seats in the gasket in an interference fit and the [52] US. Cl. ..58/90 R, 58/91 gasket fits in the case body in an interference fit. Such gaskets, [5 1] Int. Cl. ..G04b 37/08, G04b 39/00 while providing an effective seal even when subjected to high [58] Field of Search ..58/90 R, 91, 105 pressure, have long life, and hold the crystal sufficiently strongly so that a bezel is not needed. [56] References Cited 7 Clams, 3 Drawing figures FOREIGN PATENTS OR APPLICATIONS 846,977 6/1952 Germany ..-..s8/91 STRUCTURE FOR SEALING A WATCH CRYSTAL IN A WATERPROOF WATCH BACKGROUND OF THE INVENTION In conventional constructions for sealing a watch crystal into a waterproof watch, a relatively soft gasket is inserted between the crystal and the case body. Where such soft gaskets are used, it is necessary to provide a bezel to prevent disengagement of the glass from the case body. In such a construction, the packing is deformed to a considerable extent, particularly where it is to be maintained in waterproof condition against relatively high pressure. Under such circum stances, the packing is apt to cold-flow and deteriorate so that the maintenance of the waterproof condition is of relatively shortduration.

The use of a bezel increases the cost of the watch and has disadvantages with respect to design. In order to avoid these disadvantages, attempts have been made to use materials which are harder than rubber. However, these have not been successful because the gasket material has been found to break or to deform excessively during assembly.

SUMMARY OF THE INVENTION In accordance with the present invention, it has been found to be possible to use gasket materials harder than rubber by proper design of the pertinent components, namely the watch crystal, the gasket and the interior of the case body.

To effect a waterproof seal between the watch crystal and the gasket, the gasket, which is annular, has a frustoconical interior surface into which the watch crystal can be inserted to form an interference fit. Similarly, the interior of the case body also has a frustoconical inner surface into which the gasket, holding the watch crystal, can be inserted to form an interference fit. The gasket, preferably, is made of a synthetic resin or a soft metal. The watch crystal, the exterior of the gasket and the interior of the case body may be provided with guide surfaces to facilitate assembly. The dimensions of the components can be matched to the hardness of the gasket so that the watch crystal may be of an inorganic glass without encountering the problem of breakage during assembly.

Accordingly, an object of the present invention is to provide a structure for sealing a watch glass to a waterproof watch where the structure will have long life.

Another object of the invention is to provide a structure for sealing a watch glass to a waterproof watch while eliminating the need for a bezel.

A further object of the invention is to provide a structure for sealing a watch crystal to a waterproof watch where the assembly must withstand high pressure.

Still other objects and advantages of the invention will in part be obvious and will in part be apparent from the specification.

The invention accordingly comprises the features of construction, combination of elements, and arrangement of parts which will be exemplified in the construction hereinafter set forth, and the scope of the invention will be indicated in the claims.

BRIEF DESCRIPTION OF THE DRAWING For a fuller understanding of the invention, reference is had to the following description taken in connection with the accompanying drawing, in which:

FIG. 1 is a cross sectional view of a gasket in accordance with the present invention;

DESCRIPTION OF PREFERRED EMBODIMENTS A gasket I1 is shown in FIG. 1 prior to assembly. The gasket I1 is essentially L-shaped with lower arm 12 having an inner base 12 which is planar. Angle 6 between peripheral lip 13 and inner base 12' is less than 90 is subject to a further restriction which will be described below.

Watch crystal 14 also has a planar base 15 designed to seat against inner base 12 of gasket 11. Angle 6 between the base 15 of watch crystal l4 and periphery 16 of the watch crystal is such that upper arm 17 of gasket 11 is deformed outwardly during insertion of the watch crystal. To form an effective seal, angle 0 must be larger than angle 6,. Angle 0, may suitably lie in the range of about to and preferably is 9020 The amount by which angle 0, is less than 0 will depend on the hardness and deformability of gasket 1 I. As part of the gasket design, outer surface 18 of upper arm 17 is so shaped that when the watch crystal is inserted in the gasket, outer surface 18 will become cylindrical in shape.

To effect a tight seal between gasket 11 and case body [9, angle 0 between inner bottom 21 and inner periphery 22 of case body 19 is made less than 90. The inner periphery 22 of case body 19 is frustoconical and has a minimum diameter in the plane indicated in FIG. 3 by the reference letters xx. As can be seen, the plane of the minimum circle intersects periphery 16 of the watch crystal.

To facilitate assembly of the structure, watch glass 14 is provided with a guide surface 23, gasket 11 is provided with an exterior guide surface 24 and case body 19 is provided with an interior guide surface 25.

It is important in order to achieve proper sealing that the inner surface 13 and the exterior surface 17 of gasket 11 be smooth in finish. The same is true of inner periphery 22 of case body 19. The inner periphery 22 is preferably finished with a buff cloth. The outer surface 18 of gasket 11 can be rendered cylindrical by finishing while deformed by the watch crystal.

In forming the guide surface 24, the plane at its maximum diameter should lie within the lower arm 12, i.e., below the plane of inner base 12. The distance between these two planes is indicated by the reference letter b in FIG. 1 and is not critical. By locating the maximum circle of the guide surface 24 within the lower arm 12, pressure on the watch glass 14 during assembly of the gasket into the case body 19 is avoided.

Suitable materials for the gasket 1 l are synthetic resins such as polycarbonate and ABS resin. The gasket may also be made of a soft metal such as copper or silver.

Despite the fact that relatively hard gaskets of synthetic plastic or soft metal are used in the present structure, forces on the watch crystal are compressive and symmetrical. Consequently, the watch crystal may be of inorganic glass and yet the assembly operation can be carried out without breaking said crystal.

The structure disclosed herein, using a gasket of synthetic resin or soft metal, and with interference fits between watch crystal and gasket and case body provides resistance to the entry of water for long periods of time while eliminating problems of breakage during assembly. Moreover, since the necessity for a bezel is eliminated, the structure is simplified and cost of the final watch is decreased.

It will thus be seen that the objects set forth above, among those made apparent from the preceding description, are efficiently attained and, since certain changes may be made in the above construction without departing from the spirit and scope of the invention, it is intended that all matter contained in the above description or shown in the accompanying drawing shall be interpreted as illustrative and not in a limiting sense.

It is also to be understood that the following claims are intended to cover all of the generic and specific features of the invention herein described, and all statements of the scope of the invention which, as a matter of language, might be said to fall therebetween.

What is claimed is:

1. A structure for sealing a waterproof watch comprising a watch glass having a base perpendicular to the axis of said glass and a periphery making an angle 0 with said base of said glass, and annular gasket having an inner base perpendicular to the axis of said gasket and an inner peripheral lip making an angle 6 with said inner base, where is less than 0, and the dimensions of said glass and said gasket are such that said glass can be seated firmly against the inner base and the inner peripheral lip of said gasket by deforming said gasket outwardly, the outer surface of said gasket being cylindrical when said gasket is deformed by said glass, and a metallic case body having an inner bottom against which said gasket can be firmly seated and a frustoconical inner surface tapering inwardly away from said inner bottom, said inner surface having a circle of minimum diameter dimensioned for receiving said gasket in an interference fit, the plane of said circle of minimum diameter intersecting said periphery of said glass.

2. The structure of claim 1, wherein 0, lies between 90 and about 85.

3. The structure ofclaim 1, wherein said glass is inorganic.

4. The structure of claim 1, wherein said glass has a frustoconical guide surface to facilitate insertion of said glass into said gasket.

5. The structure of claim 1, wherein said gasket has an exterior frustoconical guide surface to facilitate insertion of said gasket into said case body, and said case body has an interior frustoconical guide surface to facilitate the insertion of said gasket into said case body.

6. The structure of claim 1, wherein said gasket is of a material selected from the group consisting of synthetic resin and a soft metal. 7

7. The structure of claim 6, wherein said synthetic resin is selected from the group consisting of polycarbonate and ABS.

Claims (7)

1. A structure for sealing a waterproof watch comprising a watch glass having a base perpendicular to the axis of said glass and a periphery making an angle 1 with said base of said glass, and annular gasket having an inner base perpendicular to the axis of said gasket and an inner peripheral lip making an angle theta 2 with said inner base, where theta 2 is less than theta 1 and the dimensions of said glass and said gasket are such that said glass can be seated firmly against the inner base and the inner peripheral lip of said gasket by deforming said gasket outwardly, the outer surface of said gasket being cylindrical when said gasket is deformed by said glass, and a metallic case body having an inner bottom against which said gasket can be firmly seated and a frustoconical inner surface tapering inwardly away from said inner bottom, said inner surface having a circle of minimum diameter dimensioned for receiving said gasket in an interference fit, the plane of said circle of minimum diameter intersecting said periphery of said glass.

2. The structure of claim 1, wherein theta 1 lies between 90* and about 85*.

3. The structure of claim 1, wherein said glass is inorganic.

4. The structure of claim 1, wherein said glass has a frustoconical guide surface to facilitate insertion of said glass into said gasket.

5. The structure of claim 1, wherein said gasket has an exterior frustoconical guide surface to facilitate insertion of said gasket into said case body, and said case body has an interior frustoconical guide surface to facilitate the insertion of said gasket into said case body.

6. The structure of claim 1, wherein said gasket is of a material selected from the group consisting of synthetic resin and a soft metal.

7. The structure of claim 6, wherein said synthetic resin is selected from the group consisting of polycarbonate and ABS.

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