CH710326A2 - Watch dial and watch equipped with such a dial. - Google Patents

Abstract

The invention relates to a watch face characterized in that it is formed of a self-supporting diamond film (5, 6, 8) making it possible to leave the mechanism of the watch visible, by offering an improved transparency. The invention also relates to a watch provided with such a dial.

Description

Technical area

The present invention relates to the field of watchmaking and relates, more particularly, a watch face. The invention also relates to a watch equipped with one or more of these dials.

State of the art

The use of fully or partially transparent watch dials is known and its main purpose is to allow to view the mechanism of the watch by transparency through the watch glass and dial. These transparent dials are for example made of organic polymeric material, glass or sapphire, the material is generally chosen according to the target market segment. The object of the present invention is to propose a new alternative for producing transparent watch dials.

Disclosure of the invention

More specifically, the present invention relates to a watch face characterized in that it is made of a self-supporting diamond film. In the present application, self-supporting means that the diamond film is not deposited on a substrate, but has a mechanical rigidity allowing it to stand autonomously.

The dial advantageously comprises a polycrystalline diamond layer having a thickness of between 0.05 and 3 millimeters.

[0005] Alternatively, the dial comprises a single diamond single crystal having a thickness of between 0.05 and 3 millimeters.

The invention also relates to a method of producing a watch dial as proposed above, characterized in that the dial is synthesized by chemical vapor deposition (CVD).

According to this method, the dial is made by monocrystalline diamond growth in the gas phase on a composite monocrystalline diamond mosaic assembled from a plurality of monocrystalline diamond substrates. A treatment is then carried out to obtain a diamond film and to eliminate the substrate, the film having a thickness of between 0.05 and 5 millimeters.

The dial can also be achieved by monocrystalline diamond growth in the gas phase on a single crystal monocrystalline substrate, then treatment to obtain a diamond film and remove the substrate and having a thickness between 0.05 and 5 millimeters.

The dial can also be made by growth of polycrystalline diamond gas phase on a substrate, then treatment to obtain a diamond film and remove the substrate and having a thickness between 0.05 and 5 millimeters.

Diamond is a material that can be synthesized by chemical vapor deposition (CVD) on different types of substrates and on large surfaces.

In its polycrystalline form, the diamond generally grows according to a columnar structure and the size of the diamond grains increases gradually with the increase in the thickness of the film. For thick diamond layers (> 100 μm), the large size of the diamond grains makes the surface of the material take on a shimmering gray appearance, more and more scintillating as the thickness of the layer increases. After separation of the diamond film from the substrate, it is therefore possible to obtain self-supporting large-area polycrystalline diamond films synthesized by the CVD method. After polishing, these diamond windows can for example be used as an optical window in different applications and they offer a good quality of transparency.

It is also possible to synthesize large diamond single crystals (several square centimeters), either from a single diamond seed, or from a composite mosaic of monocrystalline diamond seeds, thanks to the CVD method by plasma activation of a gaseous mixture containing at least one precursor of carbon and hydrogen. This method ensures the rapid growth of a monocrystalline layer of transparent diamond of high quality and on a surface of several square centimeters.

The present invention also relates to a watch provided with one or more of these dials made of diamond.

On the basis of the above, the present invention aims to describe the use of these transparent polycrystalline diamond or monocrystalline films for decorative purposes as a watch dial.

Brief description of the drawings

Other details of the invention will appear more clearly on reading the description which follows, made with reference to the accompanying drawing in which FIG. 1 schematically shows several examples of synthesis of a diamond layer free of any support (self-supporting) and its use as a base element of a watch dial.

Embodiment of the invention

Many materials are used in their massive version or in thin layers to make watch dials for the Haute Horlogerie segment.

The search for new solutions for high-end watchmaking has revealed that the use of diamond layers produced by chemical vapor deposition (CVD) is particularly advantageous to the constitution of aesthetic watch dials with varied properties. for watches of high-end segments.

These diamond layers may be polycrystalline and deposited on a substrate. In this case, they are obtained by chemical vapor deposition with an activation of the gas phase which can be carried out by microwave plasma, hot filament or any other mode of activation, by growth of the diamond film on a substrate which can be of natures after it has been seeded with nanometric diamond particles.

These polycrystalline diamond layers can then be separated from their substrate to be made self-supporting, that is to say without substrate and therefore maintained only by their own structure. To obtain this type of self-supporting layer, it is possible for example to prepare a plane silicon substrate. The upper face of this substrate being polished, it is coated with a polycrystalline diamond layer by chemical vapor deposition. During this deposition operation a layer of polycrystalline diamond grows on the silicon surface to the desired thickness. Once the desired thickness is reached, the polycrystalline diamond layer is then polished and, if necessary, finalized. The polycrystalline diamond layer is finally disconnected from the substrate, for example by chemical removal of the substrate. The diamond blade thus produced is of course completely transparent in the visible spectrum after polishing.

It is also possible to produce monocrystalline diamond blades by chemical vapor deposition by homoepitaxial growth of the monocrystalline diamond film from diamond seeds. This growth is followed by the necessary operations of cutting the substrate having served as a precursor (seed) and polishing to obtain a piece of single crystal diamond shaped and sized for the intended use. The synthesis of these large diamond single crystals is possible, either from a single diamond seed or from a composite mosaic of monocrystalline diamond seeds, thanks to the chemical vapor deposition (CVD) method. ) by plasma activation of a gaseous mixture containing at least one precursor of carbon and hydrogen. This method makes it possible to ensure the rapid growth of a monocrystalline diamond layer of high quality and over a surface of several square centimeters (between 1 and 20 cm 2).

These different growths are followed by necessary cutting operations and possible polishing and other post-treatments to obtain a piece of shape and dimensions perfectly suited to its use as a watch dial. This dimensioning step is for example performed by laser machining.

The present invention also relates to a watch case characterized in that the case comprises a dial which is made wholly or partially of a diamond layer synthesized by chemical vapor deposition.

According to the invention, it is also possible to synthesize a polycrystalline or monocrystalline diamond layer on a plane substrate 1, 2 or 3. Such a substrate may be made of a material chosen from the following materials: silicon and compounds based on silicon, diamond, refractory metals and derivatives, transition metals and derivatives, stainless steels, titanium alloys, superalloys, cemented carbides, polymers, ceramics, glasses, oxides (fused silica, alumina), semiconductors of columns III- V or II-VI of the Periodic Table. The part to be deposited may also include a base made of any material, coated with a thin layer of the above-mentioned materials which defines the substrate for diamond deposition.

A polycrystalline layer of diamond without a substrate intended for the manufacture of the transparent dial C can be obtained by a growth of a diamond layer 4 on a substrate 1 composed of one of the above materials and inoculated using of diamond nanoparticles in a microwave or hot filament CVD reactor, followed by removal of the substrate or separation of the diamond film obtained from its substrate, size and eventual polishing of the resulting diamond . The skilled person knows this type of diamond growth, as well as methods of releasing the diamond layer from its substrate and it is needless to describe it more explicitly here.

A large-size transparent monocrystalline diamond intended for the manufacture of the perfectly transparent dial C can be obtained by homoepitaxial growth on a monocrystalline diamond (seed) 2 substrate in a microwave plasma CVD reactor, followed by a separation of the diamond obtained 6 from its seed 2, a size and a polishing of the diamond obtained. This produces a single diamond single crystal. The skilled person knows this type of diamond growth and it is useless to describe it more explicitly here.

A large-size transparent monocrystalline diamond can also be obtained by vapor phase diamond growth from a mosaic of juxtaposed square monocrystalline substrates 3. This composite monocrystalline diamond mosaic is assembled from a plurality of diamond substrates monocrystalline having uniform plane orientations, arranged side by side and integrated in the assembly by growth of diamond single crystals thereon by vapor phase synthesis. These diamond monocrystals juxtaposed in mosaic are then grown by vapor phase synthesis so that a diamond single crystal grown from said single diamond substrate covers diamond single crystals grown on the other substrates to achieve integration. in the set 7. A method of this type is described in patent EP 1 553 215. The growth phase is followed by a separation of the diamond obtained 8 from its composite mosaic seed 3 to eliminate the substrate, a size and polishing. In a rigorous crystallographic approach, the diamond thus obtained is a single crystal, even if the designation of monocrystalline diamond can be objected, because of crystallographic defects present at the junctions between the elements forming the mosaic.

This monocrystalline diamond of large size can of course also be obtained by any other method or means for manufacturing it.

The diamond layer may be of monocrystalline or polycrystalline structure and its thickness greater than 100 microns.

In a particular example, using a monocrystalline silicon substrate that has been seeded with nanodiamond by a method of the state of the art. A 500 μm layer of polycrystalline diamond was then deposited using the microwave assisted chemical vapor deposition method using a dedicated installation. At the end of the growth of the diamond layer, the silicon substrate is dissolved using a method of the state of the art, in order to recover the self-supporting diamond film, free of the substrate which has served as a support during its growth.

The self-supporting diamond film 500 μm thick thus obtained is translucent and has a scintillating appearance related to its constitution made of diamond crystals of the order of 75 microns. This film is used as is to make a diamond dial with the features of being transparent and scintillating.

This self-supporting diamond film of 500 microns thick can also be polished so as to achieve a surface roughness of less than 0.01 .mu.m. The diamond film thus obtained is then used to produce a perfectly transparent diamond dial which allows to visualize the mechanism of mounting it by transparency.

In the case of the dial C, the shape is circular, but the dial can of course take any parallelepipedal or free form, and possibly be non-plan, for example curved or hollow, or a combination of these variants.

Although the present invention has been described rather in connection with a particular example of a dial C using a diamond layer produced by CVD, it is however clear that it is not limited to said examples and that it is susceptible many variations and modifications without going beyond its scope. For example, watch dials made according to the invention could be of more complex shapes, or include for example, but not limited to, all kinds of inserts, etchings, deposits of thin-film materials, etc. representing for example but not limited to numbers, letters, symbols, drawings or others. Similarly, the dial C can hold or support all types of miniature dials, hands, date window, or any other device or mechanism.

The total thickness of the dial C according to the invention will generally be between 0.05 and 5 mm.

Claims (8)

1. Watch dial characterized in that it is formed of a self-supporting diamond film. 2. Watch dial according to claim 1, characterized in that it comprises a polycrystalline diamond layer having a thickness of between 0.05 and 5 millimeters, preferably between 0.1 and 3 millimeters. 3. Watch dial according to claim 1, characterized in that it comprises a single diamond single crystal on a substrate having a thickness between 0.05 and 5 millimeters, preferably between 0.1 and 3 millimeters. 4. A method of producing a watch dial according to one of the preceding claims, characterized in that the dial is synthesized by chemical vapor deposition (CVD). 5. Method according to claim 4, characterized in that the dial is made by growth of monocrystalline diamond gas phase on a composite monocrystalline diamond mosaic assembled from a plurality of monocrystalline diamond substrates, then treatment to obtain a film of diamond and remove the substrate, the film having a thickness between 0.05 and 5 millimeters. 6. Method according to claim 4, characterized in that the dial is made by growth of monocrystalline diamond gas phase on a single substrate of monocrystalline diamond, then treatment to obtain a diamond film and eliminate the substrate, the film having a thickness between 0.05 and 5 millimeters, preferably between 0.1 and 3 millimeters. 7. Method according to claim 4, characterized in that the dial is made by growth of polycrystalline diamond gas phase on a substrate, then treatment to obtain a diamond film and remove the substrate, the film having a thickness between 0.05 and 5 millimeters, preferably between 0.1 and 3 millimeters. 8. Watch characterized in that it comprises a dial according to one of the preceding claims.