GB2052113A

GB2052113A - A structure for a timepiece and a method of manufacturing the structure

Info

Publication number: GB2052113A
Application number: GB8020342A
Authority: GB
Original assignee: Citizen Watch Co Ltd; Kawaguchiko Seimitsu KK
Current assignee: Citizen Watch Co Ltd; Kawaguchiko Seimitsu KK
Priority date: 1979-06-29
Filing date: 1980-06-20
Publication date: 1981-01-21
Also published as: JPS569074U; GB2052113B

Abstract

A dial for a timepiece is formed of a display plate 3 of a material to which a metal cannot readily be secured by soldering or welding, a metal film deposited on at least part of the display plate, the metal film comprising a first layer 10 formed of a metal such as nickel which has excellent adhesion with respect to the material of the display plate and deposited thereon by vapour deposition or sputtering and a second metal layer 11 superimposed on the first layer by electrolytic thick plating, and a metal body 9 secured by soldering to the second layer. As described the body 9 is a leg for attachment to a watch movement. A dial plate 3 of a material such as precious stone, ceramic, plastics or hard alloy can thus be used without unduly increasing the dial thickness. <IMAGE>

Description

SPECIFICATION A structure for a timepiece and a method of manufacturing the structure This invention relates to a method of securing a metal body to a thin display plate to form a structure suitable for use as part of a timepiece and to a structure so formed.

When a display plate of a timepiece, for example, a dial or partition plate, comprises a thin plate formed of precious stone, ceramic or extra hard alloy, it is virtually impossible to directly weld or solder a metal body to the display plate to form a structure suitable for use as part of a timepiece.

As a result, it has heretofore been necessary for the metal body to be secured to a supporting plate of brass or the like and the display plate is then superimposed on and secured to the metal supporting plate. The metal supporting plate and the display plate each have a minimum thickness and, as a result, the total thickness of the supporting plate and the display plate is approximately twice the size of the display plate alone. If the supporting plate and the display plate are each of the order of 400 to 450 microns, then the total thickness of the combined supporting plate and display plate is of the order of 800 to 900 microns. Such thick plates provide an obstacle in the desire to make the thickness of a timepiece as small as possible.Furthermore, if the timepiece movement is designed to be used with a dial of a thickness of say 450 y then it is necessary to redesign the timepiece movement if it is used with a combined supporting plate and dial having a thickness of approximately 900 St.

This necessarily increases the manufacturing cost of the timepiece.

An object of the present invention is to provide a method of securing a metal body to a display plate without the necessity of using a thick metal supporting plate.

According to a first aspect of the present invention, a method of securing a metal body to a thin display plate to form a structure for use as part of a timepiece, the display plate being formed of a material to which a metal body cannot readily be secured directly by welding or soldering, has a first metal layer deposited on at least part of a surface of the plate by vapour deposition or sputtering, a second metal layer superimposed on the first layer by electrolytic thick plating and the metal body is soldered to said second layer.

According to a second aspect of the invention, a structure suitable for use as part of a timepiece comprises a thin display plate of a material to which a metal body cannot readily be secured directly by welding or soldering, a first metal layer deposited on at least part of a surface of the plate by vapour deposition or sputtering, a second metal layer superimposed on the first layer by electrolytic thick plating and a metal body soldered to said second layer..

The metal body is conveniently a leg for use in fitting the structure in a timepiece casing.

The first and second layers may be provided over the entire rear face of the display plate and the total thickness of the first and second metal layers is between 50 and 1 50 zt.

In order that the invention may be more readily understood it will now be described, by way of example only, with reference to the accompanying drawing, in which: Figure 1 is a partial longitudinal sectional view of a timepiece showing a structure in accordance with the present invention, and Figure 2 is an enlarged sectional view of the essential parts of the structure shown in Figure 1.

Figure 1 shows a part of a wrist watch having a general construction and comprising a timepiece case 1, a movement 2 enclosed in the case 1 and a dial 3. The timepiece case 1 comprises an annular portion 4, a rear cover 5 and a glass 6. The movement 2 is located in a given position in the case by means of an intermediate frame 7 and suitable sealing ring 8.

The dial 3 forms part of a structure and comprises a thin plate having a thickness of 300 ( to 450 flt and formed of a material to which a metal body cannot readily be welded or soldered, such a material being a precious stone, ceramic, plastic or extra hard alloy. The dial 3 is provided on its front surface with the necessary display means, such as letters, symbols, marks and the like, and is provided on its rear surface with a metal body which serves as a fitting leg 9.

As shown in detail in Figure 2, the display plate 3 is provided on part of its rear surface with a metal film 10 to which the fitting leg 9 is secured by means of a solder 1 The metal film 10 comprises a first metal layer deposited on the surface of the dial 3 by vapour deposition or sputtering and a second metal layer superimposed on the first metal layer by a thick plating. The first metal layer is formed of a metal such as nickel having an excellent adhesive property with respect to the material of the dial 3 and operative as an electrode when the second metal layer is formed by electrolytic plating. In the embodiment shown in Figure 2 the metal film 10 is provided on only a portion of the rear surface of the dial 3, whereas it may be provided over the entire surface.If it is provided over the entire surface, then the metal film has a reinforcing effect and improves the resistance of the dial 3 to bending or shock.

The metal film 10 has a thickness which is sufficient to firmly secure the fitting leg thereto by soldering and experimental tests have shown that the metal film should have a thickness of between 50 and 1 50 , z, preferably about 100 ,u. Such a relatively large thickness cannot be obtained by vapour deposition or sputtering alone and the use of the second metal layer superimposed on the first layer by a thick plating process provides the important advantage that it is possible to easily provide the film of such a thickness that the fitting leg 9 can be secured thereto by soldering.

Since the thickness of the metal film 10 is considerably less than that of a supporting plate, which has heretofore been used, it results in a structure in accordance with the present invention which can be readily exchanged with a structure in which the leg 9 is soldered or welded directly to the display plate.

Although in this specification the invention has been described mainly with respect to a dial for a timepiece, the invention is also applicable to any other form of display plate, such as a partition plate or the like.

Claims

1. A method of securing a metal body to a thin display plate to form a structure suitable for use as part of a timepiece, the display plate being formed of a material to which a metal body cannot readily be secured directly by welding or soldering, wherein a first metal layer is deposited on at least part of a surface of the plate by vapour deposition or sputtering, a second metal layer is superimposed on the first layer by electrolytic thick plating and the metal body is soldered to said second layer.

2. A method as claimed in claim 1, in which the display plate is of a precious stone, ceramic or extra hard alloy and the first metal layer is of nickel.

3. A structure suitable for use as part of a timepiece comprising a thin display plate of a material to which a metal body cannot readily be secured directly by welding or soldering, a first metal layer deposited on at least part of a surface of the plate by vapour deposition or sputtering, a second metal layer superimposed on the first layer by electrolytic thick plating and a metal body soldered to said second layer.

4. A structure as claimed in claim 3, in which the metal body is a leg for use in fitting the structure in a timepiece casing.

5. A structure as claimed in claim 3 or 4, in which the first and second layers are provided over the entire rear face of the display plate.

6. A structure as claimed in claim 3, 4 or 5, wherein the total thickness of the first and second metal layers is between 50 and 150 ,.

7. A method of securing a metal body to a thin display plate to form a structure suitable for use as part of a timepiece substantially as hereinbefore described with reference to the accompanying drawing.

8. A structure suitable for use as part of a timepiece substantially as hereinbefore described with reference to the accompanying drawing.