GB2073231A - Laminate for use in instrument dials or hands and method of making laminate - Google Patents

Abstract

A translucent sheet of PVC (1) has a coating (4) e.g. of black ink or luminous material, with apertures (3) and optionally luminous or non- luminous indicia (6). Behind the apertures there are tritium-activated luminous indicia or markings (8) which are covered by an opaque white sheet 9. A self-adhesive protective film (7) may be temporarily applied to the coating (4). The laminated structure may be used for faces or hands in time-pieces or other instruments. The use of sheet 9 and film 7 prevents operatives coming into contact with luminous materials. <IMAGE>

Description

SPECIFICATION Laminate for use in instrument dials or hands and method of making laminate The present invention relates to a laminate suitable for use in the production of time pieces or other instruments having dials and/or hands, with luminous markings.

Conventionally the luminous markings are applied to instrument dials and hands by manual painting of luminous compound on to the dial or hand. Since some luminous materials are radio-active to a greater or lesser extent, such an operation exposes the operative to a significant health hazard so that special precautions need to be taken to provide a safe working environment to protect the operative making the instrument. In addition, when such materials are applied in conventional manner to the outer face of the dial or hand they protrude significantly therefrom due to their substantial depth.

This makes them more susceptible to mechanical damage and also results in a less aesthetic appearance.

It has also been proposed in Patent Specification No. 1,372,542 to make an instrument dial by printing or applying both luminous and non-luminous indicia in their entirety on an inner face of a transparent synthetic resin material so as to be visible from the outer face thereof and subsequently applying backing material such as paint or ink and optionally adhesive. Such backing materials are not however normally sufficient to protect an operative handling the dial against contamination by the luminising compound. This is because the latter is somewhat porous and tends to absorb ink and other materials applied thereto so that a coherent protective coating is not obtained in practice. Such absorption also may result in degrading of the luminance of the luminous indicia.

Even if a satisfactory coating were to be obtained though this would still not overcome the problem of contamination of the outer surface during the luminising operation. Unless particular safeguards (involving increased production costs) are taken there is a danger of an operative picking up radioactive contamination from the outer face even after the luminous indicia have been coated.

Moreover by printing the non-luminous indicia on the inner face these become significantly less visible even if the resin material has maximum transparency due to losses of the definition etc. Also, where a conventional transparent resin material is used there are difficulties in reading the dial due to reflections from the relatively highly reflective outer face.

As used herein the expressions inner and outer face refer to those faces which are, in use in an instrument, remote from and disposed towards the viewer, respectively.

It is an object of the present invention to minimise one or more of the above disadvantages.

The present invention provides a method of making a laminate suitable for use in the production of timepieces or other instruments having dials and/or hands with luminous markings comprising the steps of applying to a first zone on the outer face of a sheet of a translucent sheet material having an outer face and an inner face as defined hereinbefore, a coating of at least one first material to provide a background defining at least one window in the remainder of said outer face and optionally to provide one or more indicia, the remainder of said outer face substantially constituting a second zone; applying to those areas of the inner face immediately behind said second zone a layer of a second luminous material as defined hereinbelow; and applying over said inner face and said layer of luminous material a sheet of a protective material in sealing engagement with said inner face for sealing the luminous material layer therebetween.

The present invention also provides a laminate for use in the production of timepieces or other instruments having dials and/or hands with luminous markings said laminate comprising a sheet of a translucent sheet material having an outer face and an inner face as defined hereinbefore, with a coating of a first material providing a background and optionally one or more indicia on a first zone on the outer face, the remainder of said outer face substantially constituting a second zone; those areas of the inner face immediately behind said second zone having a layer of a second luminous material as defined hereinbelow providing one or more luminous indicia or other markings, and a sheet of a protective material extending over said inner face and said layer of luminous material in sealing engagement with said inner face for sealing the luminous material layer therebetween.

As used herein the expression luminous material is used to indicate any material which emits light without being heated and in particular includes luminous (radioactive), phosphorescent and fluorescent paints. One example of a suitable luminous paint is one containing radioactive tritium.

By applying the background, optionally with some indicia, to the outer face of the sheet material reflections are minimised and ease of readability of these indicia is maximised. The luminous markings on the other hand are fully enclosed between the sheets of material thereby reducing the risks of operator contamination, whilst at the same time being readily visible, especially with the assistance of their luminance, through the windows in the translucent sheet material provided at the second zone of said sheet material.A particular advantage of the invention is that, with the choice of suitable materials and coating application techniques, it is possible to make a laminate in which the luminous markings on the inner face are practically indistinguishable to the naked eye from non-luminous indicia on the outer face, even where the luminous markings have a substantial depth relative to the total thickness of the laminate.

In a further aspect the present invention provides a method of making an instrument dial and/or hand with luminous markings characterised in that a laminate of the invention is applied to the instrument face and/or hand respectively. Alternatively if the laminate has adequate rigidity, it can itself be used directly as an instrument dial or hand, after removal of extraneous portions if any, e.g. by trimming or by punching out the dial or hand.

The first and second sheet materials may be any material that can be formed into a sheet, provided that in the case of the first sheet material a sufficient degree of light transmission is provided.

Most desirably in the case of the first sheet material, the material is a substantially transparent plastics material, e.g. polyvinyl chloride, having at least one face, preferably the outer face, provided with a matt finish.

Advantageously the sheet materials are selected to as to be reasonably impermeable to minimise physical leakage of luminising compound from within the laminate. The sheet material may also be selected to minimise leakage of radioactivity from one or other side of the laminate.

In general, particuiarly suitable sheet materials are plastics materials. In addition to having some or all of the desirable features mentioned above, they are generally readily tractable, economic to use and provide good strength whilst enabling the production of laminates ranging from flexible to substantially rigid. In general, thin flexible laminates are preferable when these are to be applied to a rigid substrate such as an instrument face or hand. On the other hand where a laminate is sufficiently thick and/or rigid this can itself be used to form the instrument face or hand.

Conveniently additional indicia and/or other markings such as decorative material may be provided in non-luminous compound on the outer face either alongside or on top of the background. This can be particularly advantageous in the production of instrument dials where only some of the markings are desired to be luminous. Although normally the background and any outer face markings will be in nonluminous first material(s), it may in certain circumstances be desirable to employ a non-radioactive compound containing luminous first material for either or both of the background and outer face markings, e.g. a phosphorescent material.

The laminate may be made in any desired shape or form. Thus, for example, the laminate may be made in the form of a single dial or hand; or in the form of a larger sheet which can be subsequently cut down to provide one or more "dials" (including laminate portions suitable for forming dials or for application to dials) and/or one or more hands (including laminate portions suitable for forming hands or for application to hands).

Whilst the laminate will generally be made in the form of a flat sheet it can also be made in nonplanar forms, e.g. as a convex dish-shape suitable for application to a convex instrument face.

It will be appreciated that the laminate of the invention provides a safe and ready-to-use component in the assembly of instruments and that any operations involving the direct exposure of operatives to luminising compound may be separated entirely from any instrument assembly areas thereby facilitating the maintenance of safe working conditions as far as possible.

As a further contribution to safety though, a detachable protective film or sheet may be applied to the outer face prior to the application of the luminous material. Once the latter has been enclosed by the protective material sheet the protective film may be removed along with any traces of luminous material that may have become attached to its outside during the application of luminous material to the inner face. There is then obtained a laminate which is for practical purposes substantially free of luminous material on both its inner and outer faces and therefore quite safe to handle thereafter without the need for any special safety precautions.

One way of carrying out the invention is described in detail below with reference to the accompanying drawings which illustrate only one specific embodiment, in which: Figures 1 to 5 illustrate successive stages of a method of making a laminate of the invention with Figure 5 showing a completed laminate prior to removal of the outer face protective film in crosssection and each of the Figures 1 to 4 showing a corresponding transverse section. (Note -- these are not to scale.) Figure 1 shows a sheet 1 of substantially transparent polyvinylchloride (PVC) having an inner face 2 and an outerface 3 as defined hereinbefore. The outer face has a matt finish and has had printed onto a first zone thereof a coating 4 of a non-luminous first material comprising a black ink.This coating 4 provides a background and defines a plurality of windows 5 at second zones constituted by the remainder of the outer face.

A plurality of non-luminous indicia 6 are then printed onto the black background coating 4 in another lighter coloured first material and a self-adhesive protective film 7 is then applied over the printed outer face 3.

A luminous radioactive tritium containing second material 8 is then painted onto the inner face 2 over the windows 5 (i.e. behind the second zones) and slightly beyond (i.e. partially behind the first zones where they adjoin the second zones) to provide luminous indicia and/or other luminous markings.

A second sheet 9 of an opaque light-coloured, e.g. white, plastics material is then applied to the inner face 2 over the luminous material markings 8 to enclose them. The protective film 7 is then peeled off to provide a laminate substantially ready for mounting (apart from any trimming or cutting out that may be necessary -- e.g. as where a single sheet of laminate contains a plurality of separate dials). Insofar as both the inner and outer faces 2, 3 will be free of any traces of luminous material it will be appreciated that this operation may be carried out quite safely without the need for any special safety precautions.

It will of course be appreciated that although normally the background and outer face markings will be applied to the first zone before the second material is applied behind the second zone, this order may readily be reversed if desired.

Finally as has already been pointed out the drawings are not to scale -- especially as regards to the thickness of the various component layers. In-a typical example the thickness of the various items would be as follows:- outer face markings: 0.0125-0.05 mm e.g. 0.025 mm background: 0.0125-0.05 mm e.g. 0.025 mm translucent sheet: 0.05 -0.375 mm e.g. 0.25 mm luminous material markings: 0.0125-0.125 mm e.g. 0.05 mm protective sheet material: 0.05 -0.5 mm e.g. 0.125 mm

Claims (18)

1. A method of making a laminate suitable for use in the production of timepieces or other instruments having dials and/or hands with luminous markings comprising the steps of applying to a first zone on the outer face of a sheet of a translucent sheet material having an outer face and an inner face as defined hereinbefore, a coating of at least one first material to provide a background defining at least one window in the remainder of said outer face and optionally to provide one or more indicia, the remainder of said outer face substantially constituting a second zone; applying to at least part of the area of the inner face immediately behind said second zone a layer of a second luminous material as defined hereinbefore; and applying over said inner face and said layer of luminous material a sheet of a protective material in sealing engagement with said inner face for sealing the luminous material layer therebetween.

2. A method according to claim 1 wherein each said at least one first material is non-luminous.

3. A method according to claim 1 wherein a said at least one first material is a non-radioactive compound containing luminous material.

4. A method according to any one of claims 1 to 3 wherein the second luminous material is a radioactive compound containing luminous material.

5. A method according to any one of claims 1 to 3 wherein the second luminous material is a phosphorescent material.

6. A method according to any one of the preceding claims wherein said at least one first material is applied before the second luminous material.

7. A method according to claim 6 which includes the steps of applying a detachable protective film or sheet to the outer face after the application of said at least one first material thereto and before the application of the second luminous material to the inner face; and removing said protective film or sheet after application of the protective material sheet to the inner surface over the luminous material applied thereto.

8. A laminate for use in the production of timepieces or other instruments having dials and/or hands with luminous markings said laminate comprising a sheet of a translucent sheet material having an outer face and an inner face as defined hereinbefore, with a coating of a first material providing a background and optionally one or more indicia on a first zone on the outer face, the remainder of said outer face substantially constituting a second zone; those areas of the inner face immediately behind said second zone having a layer of a second luminous material as defined hereinbefore providing one or more luminous indicia or other markings; and a sheet of a protective material extending over said inner face and said layer of luminous material in sealing engagement with said inner face for sealing the luminous material layer therebetween.

9. A laminate according to claim 8 wherein said at least one first material is non-luminous.

1 0. A laminate according to claim 8 wherein said at least one first material is a non-radioactive compound containing luminous material.

11. A laminate according to any one of claims 8 to 10 wherein the second Iuminous material is a radioactive compound-containing luminous material.

12. A laminate according to any one of claims 8 to 10 wherein the second luminous material is a phosphorescent material.

13. A laminate according to any one of claims 8 to 12 wherein the translucent sheet material is of a substantially clear plastics material.

14. A laminate according to any one of claims 8 to 13 wherein said sheet material has a matt finish on said outer face.

1 5. An instrument having on each of a face and/or hand thereof, a laminate according to any one of claims 8 to 14.

1 6. A method of making an instrument according to claim 1 5 which includes the steps of removing any extraneous material from the laminate and securing the laminate to each said face and/or dial thereof.

1 7. A method of making a laminate suitable for use in the production of timepieces or other instruments having dials and/or hands with luminous markings, according to claim 1, substantially as described hereinbefore with particular reference to the accompanying drawings.

18. A laminate for use in the production of timepieces or other instruments having dials and/or hands with luminous markings, according to claim 8, substantially as described hereinbefore with particular reference to Figure 5 of the accompanying drawings.