Coloured timepiece component

Abstract

The invention relates to a timepiece component, in particular an external timepiece component, in particular a dial, characterised in that it comprises a transparent or partially transparent body, one surface of which is at least partially covered by a coating forming an optical colouring device, characterised in that the coating comprises a stack of the following successive layers on the surface: - one or more oxide layers; - a third layer having at least one metal material; - a second layer made of semiconductor material; - optionally a repetition of the second and third layers; - a first layer having at least one metal material; - optionally, one or more layers of a metal material, in particular chromium, or even titanium, inserted between two of the layers of the coating defined hereinbefore, such a layer promoting adhesion and / or partial absorption of light.

Description

[0001] Colorful watch component

[0002] The invention relates to a watch component comprising a coating that forms an optical device for coloring or, more generally, decorating the watch component. It also relates to a timepiece comprising at least one such watch component. Furthermore, it relates to a method for manufacturing such a watch component.

[0003] There are ancient and traditional methods of coloring watch components, for example by applying paint, varnish, lacquer or enamel.

[0004] The general object of the invention is to propose a colouring solution for a watch component which improves existing solutions.

[0005] More specifically, a first object of the invention is to propose a colouring solution for a watch component which makes it possible to achieve a predefined colour in a durable, robust and repeatable manner.

[0006] A second object of the invention is to offer a solution for coloring a watch component by a simple process compatible with industrial manufacturing.

[0007] To this end, the invention is based on a watch component, in particular a watch component for the casing, in particular a dial, a crystal, a transparent back, a bezel, a bezel disc, characterized in that it comprises a transparent or partially transparent body, a surface of which is at least partially covered with a coating forming an optical coloring device, characterized in that said coating comprises a stacking of the following successive layers on said surface: - one or more layers of oxides;

[0008] - a third layer consisting of at least one metallic material;

[0009] - a second layer made of semiconductor material;

[0010] - optionally repeating the second and third layers;

[0011] - a first layer consisting of at least one metallic material;

[0012] - optionally, one or more layers of a metallic material, in particular chromium or even titanium, intercalated between two of said layers of the coating defined above, such a layer promoting adhesion and / or partial absorption of light.

[0013] The invention also relates to a method for manufacturing a watch component, in particular a transparent or partially transparent watch component, in particular a dial, a crystal, a transparent case back, a bezel or a bezel disc, comprising a preliminary step of manufacturing a body of the watch component, characterized in that it comprises the deposition of a coating on at least a part of a surface of said body, this deposition of a coating comprising the following steps:

[0014] - deposition of one or more layers of oxides;

[0015] - deposition of a third layer consisting of at least one metallic material;

[0016] - deposition of a second layer of semiconductor material;

[0017] - optionally repeating the deposition of the second and third layers;

[0018] - deposition of a first layer consisting of at least one metallic material;

[0019] - optionally, deposition of one or more layers of a metallic material, in particular chromium, or even titanium, intercalated between two of the said coating layers defined above, such a layer of chromium and / or titanium having a very small thickness less than or equal to 2 nm to promote the adhesion of the said two coating layers or such a layer of chromium and / or titanium having a thickness greater than 2 nm to form a partial absorption layer.

[0020] The invention is more precisely defined by the claims.

[0021] These objects, features and advantages of the present invention will be described in detail in the following description of particular embodiments, given by way of non-limiting example, in relation to the accompanying figures, among which:

[0022] Figures 1 a, 1 b schematically represent cross-sectional views of watch components according to two variants of a first embodiment of the invention.

[0023] Figures 2a and 2b schematically represent cross-sectional views of watch components according to two variants of a second embodiment of the invention.

[0024] Figure 3 schematically represents a cross-sectional view of a watch component according to a third embodiment of the invention.

[0025] Figures 4a to 4d schematically represent cross-sectional views of watch components according to four variants of a fourth embodiment of the invention.

[0026] By convention, we will use the adjectives "superior" and "inferior," "high" and "low," and the expressions "above" and "below" throughout the description, according to the orientations used in the figures. Note that in these figures, the lowest layer is the one intended to be applied directly to the surface of the watch component's body, and the highest layer is the one facing outwards, forming the final external surface of the watch component.

[0027] We will subsequently use the simplified term "component" to refer to a watch component, and the simplified term "body" (or "substrate") to refer to a transparent or partially transparent body of such a component.

[0028] The aim of the invention is therefore to generate a chosen color on the surface of a component, particularly as perceived through a transparent or partially transparent body forming an integral part of said component. The invention is based on the use of a coating comprising several superimposed thin layers, which together form an optical device whose effect is coloration; that is to say, the effect consists of modulating the reflective behavior of light so as to favor certain wavelengths over others.

[0029] The objective of this effect is naturally to allow a user to perceive a predefined color and / or, more generally, a decorative effect. This effect therefore occurs in the visible spectrum. We will subsequently refer to the visible spectrum as the entire range of visible wavelengths, or a significant portion thereof. Thus, the expression "visible spectrum" may, for example, refer to a range of wavelengths between 380 and 780 nm, or even between 380 and 650 nm, or between 380 and 550 nm. The term "visible spectrum" can therefore, somewhat inaccurately, refer to only a portion of the theoretical visible spectrum. As will be detailed later, the optical effect according to the concept of the invention is obtained by stacking thin films with chosen optical properties.The overall optical effect results from the various absorption, reflection, and interference phenomena induced by the superimposed layers and the transparent or partially transparent body of the watch component. Specifically, the material chosen for each layer, its thickness, and its associated refractive index will define the desired optical property of each layer and the overall optical effect resulting from the combination of the different layers and the transparent or partially transparent body.

[0030] The refractive index is often a complex number, composed in a known way of a real part n, which defines, among other things, the deviation of an incident light ray by an interface between two given layers, and an imaginary part k, which defines an extinction coefficient, which accounts, among other things, for the attenuation of the incident light wave. These values ​​depend on the wavelength, and refractive indices will therefore be considered hereafter in the visible range.

[0031] On the other hand, we will use the expression "based on a material" to designate the use of at least 50% by weight of said material.

[0032] As explained previously, the invention is based on the combination of a particular coating, which will be detailed below, and a body or substrate of a watch component that is transparent or partially transparent. In a preferred embodiment, this transparent or partially transparent body extends through the entire thickness of the component, excluding the coating, over at least a portion of the component, so that the combined optical effect can be seen from the underside of the component, opposite the coating, through the transparent or partially transparent body. In one embodiment, an optical effect is also obtained from the top side of the component, i.e., the coated side.

[0033] On the other hand, we define "transparent or partially transparent" as the property of allowing all or part of visible light to pass through. Advantageously, a partially transparent substrate (or layer) allows at least 5%, or even at least 10%, or at least 25%, or even at least 50% of the incident light intensity to pass through. A partially transparent substrate (or layer) advantageously allows at least 5%, or even at least 10%, or even at least 25%, or even at least 50% of the incident light intensity to pass through for at least one given wavelength in the visible spectrum, as mentioned above. A transparent substrate (or layer) advantageously exhibits a transmittance of at least 99%, or even at least 99.5% or 99.9%, of the incident light intensity for at least one given wavelength in the visible spectrum. A partially transparent substrate (or layer), as described above, can thus be translucent.

[0034] As mentioned above, the invention is based on the use of a particular coating, which forms an optical coloring device, which is disposed on all or part of a surface of a transparent or partially transparent body of a component to be colored, which can serve as a substrate.

[0035] More specifically, the invention relies on the use of a particular coating, comprising a first group including at least two reflective layers surrounding a layer of semiconductor material, and a second group including at least one oxide layer. The first group of the coating comprises, in order from bottom to top, the first layer being the topmost, highest layer of the stack:

[0036] - a third layer consisting of one or more metallic materials;

[0037] - a second layer made of semiconductor material;

[0038] - a first layer consisting of one or more metallic materials.

[0039] The first and third layers thus form reflective layers, meaning their primary effect is to reflect incident light. Preferably, the first and third layers, and even any other optional reflective layers of the coating, are characterized by the fact that they form a medium whose refractive index in the visible range comprises a real part less than 3.5 and an imaginary part, i.e., an extinction coefficient, greater than 1. This real part may have a maximum value (less than 3.5) in the visible range and form a function of wavelength that is initially increasing up to this maximum value, then decreasing with increasing wavelength. The imaginary part may increase with wavelength.

[0040] Preferably, these layers are made of one or more metallic materials. Each of these layers can be entirely composed of a single metallic material, or even a mixture of two or more metallic materials, arranged within a single layer or in a succession of superimposed layers. In advantageous embodiments, the metallic material(s) are chosen from gold, platinum, titanium, palladium, chromium, rhodium, silver, copper, tungsten, and aluminum, the latter being encapsulated by a very thin layer of ALOs deposited by an ALD (Atomic Layer Deposition) process. Alternatively, any metallic material can be used. In a simple embodiment, each of the first and third layers is a metallic layer, entirely composed of a single metallic material, which may be the same for both layers or different materials.

[0041] Furthermore, in one embodiment, the first layer has a thickness greater than or equal to 100 nm. It is opaque and optically isolates the coating from the air above it. It also contributes significantly to the overall optical performance of the coating. This first layer may be thicker than the other layers of the coating.

[0042] In another embodiment, the first layer is less than 100 nm thick. It is partially transparent and allows visible light to pass through, which can interact with the other layers of the coating. Specifically, it allows at least 5%, or even at least 10%, 25%, or 50% of the incident light intensity to pass through for at least one given wavelength in the visible spectrum. It also contributes significantly to the overall optical performance of the coating. Furthermore, it creates an optical effect visible from the top of the coating, i.e., from the side opposite the substrate.

[0043] According to one embodiment, the third layer has a thickness between 2 and 50 nm, or even between 5 and 50 nm, or even between 30 and 40 nm, and / or a thickness greater than or equal to 20 nm.

[0044] As examples of implementation, the third layer can be chosen from:

[0045] - a layer of gold with a thickness between 5 and 50 nm, or even between 30 and 40 nm, and / or a thickness greater than or equal to 20 nm, or - a layer of platinum or titanium or palladium or chromium or rhodium or silver with a thickness between 5 and 50 nm, or even between 30 and 40 nm, and / or a thickness greater than or equal to 20 nm, or

[0046] - a layer comprising gold and / or platinum and / or titanium and / or palladium and / or chromium and / or rhodium and / or silver between 5 and 50 nm, or even between 30 and 40 nm, and / or with a thickness greater than or equal to 20 nm.

[0047] In an advantageous embodiment, gold is used as a metallic layer for the first and / or third layer, possibly combined with chromium as will be detailed later. Gold is indeed a material that is easy to deposit, robust, and exhibits good reproducibility from one manufacturing cycle to the next.

[0048] Advantageously, the second layer of semiconductor material is characterized by the fact that it forms a medium whose refractive index in the visible range comprises a real part greater than 2.5 and an imaginary part, i.e., an extinction coefficient, greater than 0.05. This real part can have a maximum value (greater than 2.5) in the visible range and form a function of wavelength that is initially increasing up to this maximum value, then decreasing with increasing wavelength. The imaginary part can decrease with wavelength. The extinction coefficient is notably greater than 0.05 for wavelengths below 550 nm, and even for wavelengths between 380 and 550 nm, between 380 and 650 nm, and between 380 and 780 nm.

[0049] The second layer is based on one or more semiconductor materials. It can be entirely composed of a single semiconductor material, or even a mixture of two semiconductor materials arranged within the same layer or in two superimposed sublayers. In advantageous embodiments, the semiconductor material(s) are chosen from silicon (Si), germanium (Ge), a combination of silicon (Si) and germanium (Ge), a semiconductor material from the III-V families such as gallium arsenide (GaAs), or tantalum oxynitride (TaOxNy). It should be noted that this last material can be alternatively insulating, semiconductor, or electrically conductive, depending on its degree of nitriding and oxidation, respectively characterized by the values ​​of y and x. This implies that its refractive index can vary over a wide range of values.It is possible to form layers in this TaOxNy material exhibiting optical behavior similar to that of a semiconductor, or even similar to that of silicon (Si). Alternatively, any semiconductor material can be used, advantageously with an absorption coefficient greater than 0.05.

[0050] According to an advantageous embodiment, the second layer has a thickness between 5 and 50 nm.

[0051] The use of silicon, and more generally of a semiconductor material, offers several advantages. The optical behavior of the second layer varies little with the angle of incidence, which is not the case, for example, with silicon dioxide. Indeed, since the refractive index of semiconductor materials is generally high (the real part greater than 2.5, or even 3, in the visible range), the path of light rays is naturally forced back towards the vertical when they enter the material. Furthermore, the non-zero imaginary part of the refractive index of these materials implies an important role for interfaces in the phenomenon of optical interference. This notably allows for a significant reduction in the iridescence of the resulting color. It should be noted that the semiconductor material used is unoxidized, or at least unintentionally oxidized. Similarly, this semiconductor material is unintentionally amorphous and non-hydrogenated.

[0052] The structure of this first coating group, which uses two metallic layers surrounding a layer of semiconductor material, is advantageous because it allows for the modulation of the amount of light transmitted and reflected, and in particular the intensity of light interacting with the semiconductor layer. Furthermore, the thickness of the third metallic layer can be chosen to decouple the semiconductor layer of the second coating group. Indeed, even for a relatively transparent metal like gold in thin layers, a thickness of approximately 20 nm is sufficient to significantly attenuate electromagnetic radiation. The third layer thus allows for the determination of the amount of light reaching the semiconductor layer.

[0053] Ultimately, the inventors surprisingly discovered that this combination of the first group exhibits highly advantageous properties, allowing for flexible, robust, reproducible, and iridescent-free modulation of optical properties across the entire visible spectrum. This result cannot be achieved using the individual layers.

[0054] This first group can thus be based on a multitude of material combinations, among which (in order from top to bottom, i.e. 1 ière layer / 2 ième layer / 3 ièmelayer): Au (opaque or partially transparent) / Si / Au, Au (opaque or partially transparent) / Si / Ag, Ag (opaque or partially transparent) / Si / Au, Rh (opaque or partially transparent) / Si / Au, (Rh / Au) (opaque or partially transparent) / Si / Au, Cr (opaque or partially transparent) / Si / Au, etc. Optionally, this structure of the first group can be modified to incorporate one or more layers of chromium (Cr), or more generally of metal, notably intercalated between two of the three layers described above. Such a chromium layer can fulfill two different functions.

[0055] A thin layer of chromium, or more generally of metal, less than 2 nm thick, advantageously between 0.5 and 2 nm, has little optical effect and primarily serves as an adhesion layer. It can be sandwiched between any two coating layers to improve their adhesion.

[0056] A thicker layer of chromium, or more generally of metal, exceeding 2 nm, further contributes to the coating's optical effect. Specifically, it partially absorbs incident light. It can be associated with the first or third layer, as previously mentioned. This allows, for example, for controlled and versatile modification of the reflection at the interface between the semiconductor material layer and the third layer. Such a layer can be sandwiched between two layers of the first group or positioned beneath the first group to interface with a second group of the coating, described later.

[0057] Alternatively, any metal can be used as a replacement for chromium depending on the desired effect, such as titanium Ti which can fulfill the functions of an adhesion layer and / or partial absorption.

[0058] The first group of the coating can thus have a structure enriched by the presence of one or more layers of metal, such as chromium. Its structure can therefore, for example, consist of combinations such as (in order from top to bottom): Au(opaque or partially transparent) / Si / Cr-Au-Cr, Au(opaque or partially transparent) / Si / Au-Cr, Au(opaque or partially transparent) / Si / Cr-Au, Au(opaque or partially transparent)-Cr / Si / Au, Au(opaque or partially transparent)-Cr / Si / Cr-Au, Au(opaque or partially transparent)-Cr / Si / Au-Cr, or even Au(opaque or partially transparent) / Si / Cr, the chromium layer here forming the third layer mentioned above.

[0059] Alternatively, instead of a sequential combination of layers involving a chromium layer such as Cr-Au-Cr, it is also possible to deposit a mixed Au layer x Cr yby co-deposition of two different materials simultaneously on the same area. The sequential Cr-Au-Cr version is simpler and more robust to implement in practice and remains the preferred variant.

[0060] According to one embodiment, the structure formed by the first group could be repeated, i.e. the first group could comprise the additional superposition of a layer of semiconductor material and a reflective layer, according to a structure alternating a layer of semiconductor material and a reflective layer, in which each layer of semiconductor material is sandwiched between two reflective layers.

[0061] In addition, the coating includes a second group, positioned beneath the first group described above. This second group comprises at least one oxide layer. This second group allows, in particular, for modulating the coating's reflectivity, and for example, increasing the perceived brightness of the surface. The refractive index in the visible range of each of this oxide layer(s) preferably includes a real part less than 3 and an imaginary part less than 0.05, or even less than 0.01.

[0062] According to one embodiment, said one or more layers of oxides of this second group comprise two layers respectively of two different materials, whose refractive indices are different.

[0063] According to one embodiment, each of the oxide layers in this second group consists of, or is based on, a material chosen from among SiU2, TiU2, AhOs, SisN4, Ta2Os, TaOxNy, AlOxNy, and TiOxNy. In the case of these latter ternary materials, the stoichiometry will be chosen so that the material exhibits optical properties similar to those of the other oxides.

[0064] According to one embodiment, the second group consists of:

[0065] - a silicon dioxide (SiO2) layer with a thickness between 20 and 140 nm, preferably between 40 and 75 nm, and / or

[0066] - a layer of titanium oxide TiU2 with a thickness between 5 and 100 nm, preferably between 5 and 50 nm.

[0067] In all cases, the thicknesses of the oxide layers are minimized, kept low, in order to minimize the iridescence they cause and to have good industrial robustness.

[0068] The second group preferably does not include a metallic layer producing an optical effect. Only a thin metallic layer, for example of chromium and / or titanium, less than 2 nm thick, can be used, for its function of strengthening the adhesion between layers. Generally, certain parts of the stack forming the coating can be duplicated to modulate or enhance their effect. For example, it is possible to duplicate the first group of layers, and thus have, for example, an Au(opaque) / Si / Au / Si / Au stack, with or without intervening Cr layers, at some or all of the interfaces, as described previously. In such a structure, the thicknesses of the layers can be different for the same material; for example, the thickness of the first Si layer can be different from that of the second Si layer.On the other hand, whether intentionally or not, the second Si layer can have a different residual oxidation state than the first. Similarly, it is possible to split the second group of layers, and thus have, for example, a TiO2 / SiO2 / TiO2 / SiO2 stacking instead of TiC / SiC, or a SiO2 / TiO2 / SiO2 / TiO2 stacking instead of SiC / TiC.

[0069] The coating according to the invention allows for numerous combinations of layers, which makes it possible to obtain a wide range of colors and finishes, including colors in shades of red, purple, blue, green or brown.

[0070] The table below gives some examples of layers created, with the colors obtained.

[0071] Color Stacking Thicknesses (nm)

[0072] Green Au (opaque) / Si / Cr / Au / >100 / 35 / 3 / 7 / 32

[0073] TiCh / sapphire (transparent substrate) Green Au (opaque) / Cr >100nm / 0.3 / 30 / 2.1 / 8 /

[0074] (Membership) / If / Cr / 2.1 / 33 / 0.5

[0075] Au / Cr / TiO2 / Cr (adhesion) / sapphire (transparent substrate)

[0076] Green Au (opaque) / Si / Au / TiO2>100 / 39 / 34 / 17 / 41 dark / SiO2 / sapphire (transparent substrate)

[0077] Blue Au(opaque) / Si / Au / SiO2>100 / 29 / 25 / 75 / 47 clear / TiO2 / sapphire (transparent substrate)

[0078] Brown Au (opaque) / Cr / Si / Au / >100 / 17 / 12 / 15 / 8

[0079] TiO2 / sapphire (transparent substrate)

[0080] Brown Au (opaque) / Cr / Si / Cr / >100 / 17 / 12 / 3 / 14 / 3 / 6 clear Au / Cr / TiO2 / sapphire

[0081] (transparent substrate)

[0082] In general, our approach allows us to obtain a very wide range of colors through optical interference of light, including colors other than black. Black can be defined as colors with L*a*b* coordinates such that -2 < a* < 2 and -2 < b* < 2 and L* < 30.

[0083] Figures 1a and 1b schematically represent variants of a first embodiment of a coating according to the invention. In all these variants, the first group of the coating comprises the same structure of two gold layers surrounding a silicon layer. Both variants include a second group composed of two oxide layers, respectively silicon dioxide (SiO2) and titanium dioxide (TiC2), the order of which is reversed in the second variant.

[0084] Figures 2a and 2b schematically represent variations of a second embodiment of a coating according to the invention. According to the embodiment shown in Figure 2a, the first group of the coating comprises a structure of two gold layers surrounding a silicon layer. The second group comprises an oxide layer, in this case titanium dioxide (TiC₂). Figure 2b represents a variation of the embodiment shown in Figure 2a, in which a thin layer of chromium is intercalated between each pair of adjacent successive layers in the embodiment shown in Figure 2a, to increase the adhesion between these layers.

[0085] Figure 3 schematically represents a third embodiment of a coating according to the invention. The first group incorporates three relatively thick chromium layers, respectively positioned beneath each of the three base layers of the first group, to provide optical complementarity to the first group. In other words, the first layer, forming the top layer, comprises a thick gold layer complemented by a chromium layer beneath the thick gold layer, and the third gold layer is complemented by its positioning between two chromium layers. The second group is identical to that of the embodiment shown in Figure 1a.

[0086] Figures 4a to 4d schematically represent variations of a fourth embodiment of a coating according to the invention. According to the embodiment shown in Figure 4a, the first group of the coating comprises a structure of two gold layers surrounding a silicon layer, the upper gold layer being opaque. The second group comprises two oxide layers, in this case titanium dioxide (TiU2) followed by silicon dioxide (SiU2) (from bottom to top). Figure 4b shows a variation of the embodiment shown in Figure 4a, in which the upper gold layer is partially transparent, this variation being intended to be viewed from below, through the transparent or partially transparent substrate.Figure 4c represents a variant embodiment of that of Figure 4b, in which the upper gold layer is partially transparent, said gold layer being covered by an opaque layer, this latter opaque layer being a metallic layer, a lacquer, or any other type of opaque layer. Figure 4d represents a variant embodiment of that of Figure 4a, in which the upper surface of the transparent or partially transparent body (substrate) is structured, for example, by sunburst, sandblasting, guilloché, spraying, satin finishing, brushing, snailing, at least one Geneva stripe, perlage, rimming, and / or any type of decoration with repeating patterns.

[0087] The coating according to the invention described above can be combined with other features contributing to a coloring effect or, more generally, to the decoration of the component. For example, the surface to be decorated on the component may include a surface texture, wholly or partially covered by the coating described above. This coating has a total thickness sufficiently small to conform to and retain the contours of the surface texture. A surface texture may consist, for example, of sunburst finishing, sandblasting, guilloché work, spraying, satin finishing, brushing, spiraling, at least one Geneva stripe, beading, rimming, and / or any type of repeating pattern decoration.

[0088] Such structuring can improve the surface finish. Indeed, with a polished surface, the resulting color can vary depending on the viewing angle. Structuring creates a diffusing effect and a color that exhibits much less variation depending on the viewing angle than with a polished surface. Surprisingly, the type of structuring also allows for modulation of the color intensity. For example, sandblasting or spraying produces a pastel color, while guilloché work, sunburst finishing, or machining with a cutting tool produces a vibrant color.

[0089] The transparent or partially transparent body can be made of numerous materials, including quartz, sapphire, diamond, glass, acrylic glass (PMMA - polymethyl methacrylate), polycarbonate (PC), PET (polyethylene terephthalate), PDMS (polydimethylsiloxane), or other transparent or partially transparent mineral, ceramic, or polymeric materials. It may be entirely made of a single material or composed of several materials. Specifically, the surface to be colored may include a layer of material, for example, to facilitate the creation of a surface texture as described above. Such a layer may, for example, be made of PDMS. The thickness of the transparent or partially transparent body is preferably greater than 100 µm.

[0090] The use of a PDMS element (or any other transparent polymer allowing the replicating of the structure of a surface), associated or not with another transparent or partially transparent element, makes it possible to obtain a guilloché, sunburst, or other type of surface by replicating a metallic surface with the desired characteristics.

[0091] The component may be a watch component, for example, a watch case component such as a dial, bezel, bezel disc, crystal, case back, case, or strap, or a watch movement component, such as a rotor, blank, bridge, barrel cover, or ratchet cover. The invention also relates to a method for manufacturing a watch component, in particular a watch case component, especially a dial, comprising a preliminary step of manufacturing a transparent or partially transparent body of the watch component, characterized in that it comprises the application of a coating to at least a portion of a surface of said body, this application of a coating comprising the following steps:

[0092] - deposition of one or more layers of oxides;

[0093] - deposition of a third layer consisting of at least one metallic material;

[0094] - deposition of a second layer of semiconductor material;

[0095] - optionally repeating the deposition of the second and third layers;

[0096] - deposition of a first layer consisting of at least one metallic material;

[0097] - optionally, deposition of one or more layers of a metallic material, in particular chromium, or even titanium, intercalated between two of the said coating layers defined above, such a chromium layer having a very small thickness less than or equal to 2 nm to promote the adhesion of the said two coating layers or such a chromium layer having a thickness greater than 2 nm to form a partial absorption layer.

[0098] The deposition of the various layers, as described above, is carried out in the order indicated, with the different layers being superimposed on one another, starting from the surface of the transparent or partially transparent body of the component. These layers are therefore superimposed and adjacent, arranged in the order indicated, with the exception of any intermediate metal layers, particularly chromium, which may be inserted between these different layers, depending on the optional deposition mentioned.

[0099] According to an advantageous embodiment, all or part of the coating layers are deposited by physical vapor deposition PVD, for example by vacuum evaporation or sputtering or by ion beam, by chemical vapor deposition CVD, or by atomic layer deposition ALD.

[0100] Furthermore, and even more advantageously, all the coating layers could be deposited using the same technique in a single manufacturing cycle. These deposits are preferably made without airing between the deposition of two successive layers.

[0101] Alternatively, different deposition techniques can be used, including PVD, CVD or ALD techniques, for different layers of the coating, provided they are compatible.

[0102] As a first example of implementing the manufacturing process, vacuum evaporation is used, which allows for the deposition of thin layers of the elements Si, Cr, Au, TiU2, and SiU2 with very precisely controlled thickness. The semiconductor layer is then made of Si, the metallic layers of Au, and possibly Cr, the optional adhesion layers of Cr, and the oxide layers of TiU2 and SiU2.

[0103] As a second example of manufacturing process implementation, sputtering is used, which also allows for the deposition of thin layers of Si, Cr, Au, TiC, and SiU2 with very precisely controlled thickness. The semiconductor layer is then made of Si, the metallic layers of Au, and possibly Cr, the optional adhesion layers of Cr, and the oxide layers of TiU2 and SiU2. As a third example of manufacturing process implementation, sputtering is used, which allows for the deposition of thin layers of TaOxNy, Cr, and Au with very precisely controlled thickness. The semiconductor layer is then made of TaOxNy, the metallic layers of Au, and possibly Cr, the optional adhesion layers of Cr, and the top layers of TaOxNy.

[0104] Various deposition techniques, familiar to those skilled in the art, can be used. For example, argon (Ar) can be sprayed onto the components during deposition, which densifies the layers, according to the ion beam-assisted PVD technique. The same ion beam can also be supplied with oxygen (O2) or nitrogen (N2) to promote oxidation and / or nitriding of the coating, respectively.

[0105] The characteristics of the deposited layers can be observed during deposition using known methods. For example, a quartz crystal microbalance placed within the deposition chamber allows for highly accurate monitoring of the deposited thickness. Similarly, it is possible to analyze the optical transmission or optical reflection of the deposited layer during deposition, enabling the targeting of optical properties rather than thickness.

[0106] Indeed, the chambers of deposition machines are kept under vacuum during the deposition cycles. However, the residual atmosphere invariably contains residual gases such as O2, H2O, or N2, which means that a certain degree of oxidation and / or partial nitriding of the layers is possible, unintentionally. This unintentional phenomenon can be minimized, or even eliminated, by properly preparing the deposition machine, particularly through cleaning. This partial oxidation and / or nitriding can influence the optical properties and therefore potentially the overall appearance of the deposited coating. If necessary, it is possible to adjust the layer thicknesses to compensate for and eliminate this unintentional optical effect and achieve the desired result.

[0107] Measurements have shown that the Si semiconductor material deposited according to the invention has optical behavior close to that of pure, unoxidized Si. Indeed, refractive index measurements in a "clean" machine (long pumping time), with a low residual oxygen partial pressure, give a refractive index n of 4.04 for an incident wavelength of 550 nm and 3.87 for an incident wavelength of 630 nm, which is very close to the values ​​for pure silicon (4.39 for amorphous silicon and 4.08 for crystalline silicon at 630 nm). In a "dirty" machine (shorter pumping time), the refractive index measurements are 3.35 for an incident wavelength of 550 nm and 3.20 for an incident wavelength of 630 nm, which is lower but still far from the value of 1.47 for silicon dioxide SiU2. Similarly, the extinction coefficients k remain very high, and well above 0.05 over a large part of the visible part of the spectrum. The Si-based material deposited by the process of the invention therefore always behaves as a semiconductor, regardless of the state of the deposition machine and any possible natural, unintentional oxidation phenomenon.

[0108] In summary, the preceding considerations show that it is therefore possible to implement the invention as described, based on a coating comprising a first group with a second layer of semiconductor material. This semiconductor material may undergo oxidation, including unintentional oxidation, which is either negligible or compensated for by adjusting the thicknesses of the coating layers to obtain the desired result, in particular the desired color.

[0109] Finally, the invention offers the advantage of simplifying the manufacturing process, particularly through the use of a second layer of semiconductor material. Furthermore, the semiconductor material provides advantageous optical properties: it has a high refractive index, is partially absorbent (extinction coefficient k > 0.05 over a large part of the visible spectrum), and is robust (allowing for industrial and reproducible deposition that is stable over time).

[0110] The invention has many other advantages. Beyond the spectrum obtained in reflection (with a first opaque or partially transparent layer) or in transmission (with a first partially transparent layer), the durability of the stack, i.e. the consistency of the rendering over time, or its manufacturing robustness (reproducibility from one production batch to another, number of layers if possible low and thin thicknesses, deposition techniques if possible compatible, or even a single one for the whole stack) will be just as important.

[0111] It is also possible to list the following advantages of the invention:

[0112] ► Usable on small and large series in an industrial and reproducible manner;

[0113] ► Stacking of layers that can be easily deposited in the same deposition equipment during the same cycle;

[0114] ► Robustness and durability;

[0115] ► Many possible colors on the same basis, due to the multitude of influencing parameters; ► Obtaining a rendering target, in particular of color, for example of color according to the CIE L*a*b* reference, in particular of color other than black, i.e. a color outside the domain defined by -2 < a* < 2 and -2 < b* < 2 and L* < 30;

[0116] ► Optimization across the entire visible spectrum, not just on a single wavelength or a restricted range;

[0117] ► Little to no iridescence.

[0118] As a side note, as previously described, it is possible to use an ultrathin metal layer, less than 2 nm thick, in particular a layer of chromium or titanium, at least one of the interfaces between two layers of a coating, to promote adhesion between said two layers.

[0119] The invention has been described based on a coating that includes a second group comprising one or more oxide layers. In all cases, each oxide layer of this second group could be replaced by a layer of a semiconductor material to take advantage of the beneficial properties of a semiconductor material, as described above. Thus, in one embodiment, the coating includes a second group arranged beneath a first group as described, this second group comprising one or more layers of semiconductor material, such as, for example, a TaOxNy layer.

[0120] The different variants described above can of course be combined with each other.

Claims

26 Demands 1. Watch component, in particular a watch case component, in particular a dial, a crystal, a transparent case back, a bezel or a bezel disc, characterized in that it comprises a transparent or partially transparent body, a surface of which is at least partially covered with a coating forming an optical coloring device, characterized in that said coating comprises a stacking of the following successive layers on said surface: - one or more layers of oxides; - a third layer consisting of at least one metallic material; - a second layer made of semiconductor material; - optionally repeating the second and third layers; - a first layer consisting of at least one metallic material; - optionally, one or more layers of a metallic material, in particular chromium or even titanium, intercalated between two of said layers of the coating defined above, such a layer promoting adhesion and / or partial absorption of light.

2. Watch component according to the preceding claim, characterized in that - the first and / or third layer is made of a material having a refractive index in the visible range that includes a real part less than 3.5 and an extinction coefficient greater than 1; and / or - the second layer is made of a material having a refractive index in the visible range which includes a real part greater than 2.5 and an extinction coefficient greater than 0.05; and / or - the oxide layer(s) is in a material having a refractive index in the visible range which includes a real part less than 3 and an extinction coefficient less than 0.05, or even less than 0.

01.

3. Watch component according to one of the preceding claims, characterized in that the first layer has a thickness greater than or equal to 100 nm and / or is entirely in one or more metallic materials selected from gold, platinum, titanium, palladium, chromium, rhodium, silver, copper, tungsten, aluminium and / or is an opaque or partially transparent layer.

4. Watch component according to one of the preceding claims, characterized in that the second layer has a thickness between 5 and 50 nm and / or is entirely made of a semiconductor material selected from silicon Si, germanium Ge, a combination of silicon Si and germanium Ge, a semiconductor material of the III-V families such as gallium arsenide GaAs, tantalum oxynitride (TaOxNy).

5. Watch component according to one of the preceding claims, characterized in that the third layer has a thickness of between 2 and 50 nm, or even between 5 and 50 nm, and / or in that the third layer is entirely made of one or more metallic materials selected from gold, platinum, titanium, palladium, chromium, rhodium, silver, copper, tungsten, aluminium or in that the third layer is a layer of gold with a thickness of between 5 and 50 nm, or even between 30 and 40 nm, and / or a thickness greater than or equal to 20 nm.

6. Watch component according to any one of the preceding claims, characterized - in that said one or more layers of oxides comprise two layers respectively made of two different transparent materials, whose refractive indices are different, - or in that it comprises one or more layers of material selected from SiC2, Ti2, AlOs, SisN4, Ta2Os, TaOxNy, AlOxNy, TiOxNy, - or in that said one or more layers of oxides or semiconductor material comprise: - a silicon dioxide (SiO2) layer with a thickness between 40 and 140 nm, preferably between 40 and 75 nm, and / or - a layer of titanium oxide TiU2 with a thickness between 5 and 100 nm, preferably between 5 and 50 nm, with a layer of chromium with a thickness less than or equal to 2 nm optionally added to promote the adhesion of one or more layers.

7. Watch component according to any one of the preceding claims, characterized in that it comprises at least one layer of a metallic material, in particular chromium, of thickness between 0.5 and 2 nm, disposed between two layers of the coating to promote the adhesion of said two layers of the coating, and / or in that it comprises at least one layer of a metallic material, in particular chromium, of thickness greater than 2 nm, disposed between two layers of the coating to form a partial absorption layer modifying the optical behavior at the interface of said two layers of the coating.

8. A watch component according to any one of the preceding claims, characterized in that it comprises a surface texture applied to all or part of said body surface, in particular a surface texture such as sunburst finishing, sandblasting, guilloché work, satin finishing, a 29 brushing, a spiral, at least one Geneva coast, a beading, a ringing, and / or any type of decoration with repeated patterns, the coating being at least partially placed on said surface structure and of sufficient thickness to follow and retain reliefs of the surface structure.

9. Watch component according to any one of the preceding claims, characterized in that the transparent or partially transparent body is made of quartz, sapphire, diamond, glass, acrylic glass (PMMA - polymethyl methacrylate), polycarbonate (PC), PET (polyethylene terephthalate), PDMS (polydimethylsiloxane) or a mineral material, ceramic, or polymer, and / or in that the watch component is a dial, a bezel, a bezel disc, a case back, a crystal, a case, a bracelet, a watch movement component, such as a weight or blank or a bridge or a barrel cover or a ratchet cover.

10. Watch component according to any one of the preceding claims, characterized in that said coating forms an optical device of distinct colouring from black defined as colours having coordinates L*a*b* -2 < a* < 2 and -2 < b* < 2 and L* < 30.

11. Timepiece, in particular watch, characterized in that it comprises a timepiece component according to one of the preceding claims.

12. A method for manufacturing a watch component, in particular a watch case component, in particular a dial, a crystal, a transparent case back, a bezel or a bezel disc, comprising a preliminary step of manufacturing a transparent or partially transparent body of the watch component, characterized in that it comprises the 30. Deposition of a coating on at least part of a surface of said transparent or partially transparent body, this deposition of a coating comprising the following steps: - deposition of one or more layers of oxides; - deposition of a third layer consisting of at least one metallic material; - deposition of a second layer of semiconductor material; - optionally repeating the deposition of the second and third layers; - deposition of a first layer consisting of at least one metallic material; - optionally, deposition of one or more layers of a metallic material, in particular chromium, or even titanium, intercalated between two of the said coating layers defined above, such a chromium layer having a very small thickness less than or equal to 2 nm to promote the adhesion of the said two coating layers or such a chromium layer having a thickness greater than 2 nm to form a partial absorption layer.

13. Manufacturing process according to the preceding claim, characterized in that all or part of the coating layers are deposited by physical vapor deposition PVD, in particular by vacuum evaporation, or sputtering, or by chemical vapor deposition CVD, or by atomic layer deposition ALD.

14. Manufacturing process according to any one of claims 12 or 13, characterized in that all layers of the coating are deposited by the same process in the same manufacturing cycle.

15. A manufacturing method according to any one of claims 12 to 14, characterized in that it comprises a step of measuring the thickness of a 31 deposited layer and / or measurement of the optical transmission or optical reflection of a deposited layer during a deposition step, so as to determine the end of said deposition step based on the measurement(s).

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