CH715862A2 - Colorful watch glass. - Google Patents

Abstract

The invention relates to a transparent watch component, in particular a watch crystal, which comprises an interior surface (1) which is substantially flat or curved, and a transparent material, colored by a zone of modified chemical composition (30) within said component by a providing at least one coloring chemical element to said transparent material, this zone of modified chemical composition extending in only part of the total thickness (e) of the watch component. The invention also relates to a method of manufacturing a watch component comprising a step of supplying at least one coloring chemical element, in particular by depositing a coating or ion implantation, and a step of heat treatment.

Description

Introduction

The present invention relates to a transparent and colored watch component, in particular a watch crystal. The invention also relates to a timepiece, such as a watch, comprising such a timepiece component. It also relates to a method of manufacturing a watch component, particularly comprising a phase of coloring a transparent substrate.

State of the art

[0002] A sapphire watch crystal is by nature transparent and colorless, and it is sometimes desired to modify its appearance to make it colored. For this, there is a process for synthesizing sapphire by coloring it simultaneously. This process produces a ball of sapphire, colored in the mass, in which watch glasses are then cut. Such a method is, for example, described in document WO2017187647. This solution of the state of the art has many drawbacks: <tb> - <SEP> it requires a complex study during each color change; <tb> - <SEP> it does not allow to partially color the component, nor to combine several colors; <tb> - <SEP> it is not compatible with certain colors, which cannot be obtained, or with insufficient quality rendering; it may therefore be incompatible with a horological application.

[0003] In addition to the previous remarks, it should be noted that any manufacturing process for a watch component must comply with numerous constraints and that the modification of a process to integrate a coloring step must not degrade the overall quality of the watch component obtained. For example, in the case of a watch crystal, the following horological requirements must be met: <tb> - <SEP> The crystal must have sufficient transparency to allow the time to be read; <tb> - <SEP> The glass must have a high overall mechanical resistance, as well as a surface resistance to scratches; <tb> - <SEP> The coloring of such ice must make it possible to achieve a predictable and repeatable result; <tb> - <SEP> The perceived color must present a quality rendering, flawless, with perfect homogeneity or with a precise heterogeneous distribution according to a predefined choice; <tb> - <SEP> The color obtained must be suitable for the watch, in particular the dial which will be visible through the glass.

[0004] This technical problem also applies to other transparent watch components, in particular having a substantially planar shape, in particular having a substantially planar or curved inner surface and / or occurring in a mineral material, such as sapphire or glass.

[0005] The general objective of the invention is to offer a solution for obtaining a transparent and colored watch component, which does not include all or part of the drawbacks of the state of the art.

[0006] More particularly, an object of the invention is to offer a solution for a transparent and colored watch component, making it possible to achieve a repeatable and precise visual appearance, of high quality.

Brief description of the invention

[0007] To this end, the invention is based on a transparent watch component, in particular watch crystal, characterized in that it comprises a substantially flat or curved inner surface, and in that it mainly comprises a transparent, colored material. by a zone of modified chemical composition within said component by a contribution of at least one coloring chemical element to said transparent material, this zone of modified chemical composition extending in only part of the total thickness of the watch component. Advantageously, this zone of modified chemical composition does not extend throughout the entire volume of the watch component. Again advantageously, it does not extend over its entire thickness. Again advantageously, it extends over a small part of its thickness and / or of its volume.

[0008] The invention also relates to a method of manufacturing a colored and transparent horological component, characterized in that it comprises the following steps: <tb> a. <SEP> Providing an initial substrate which comprises a substantially planar or curved interior surface composed primarily of a transparent material; <tb> b. <SEP> Contribution of at least one coloring chemical element by at least one exterior or interior surface of said initial substrate; <tb> c. <SEP> Heat treatment of said substrate resulting from the supply step comprising at least one coloring chemical element to obtain a transparent and colored part.

[0009] Advantageously, the supply step comprises the deposition of a coating comprising the at least one coloring chemical element.

[0010] The invention is more precisely defined by the claims.

Brief description of the figures

These objects, characteristics and advantages of the invention will be explained in detail in the following description of a particular embodiment made without limitation in relation to the accompanying figures including: <tb> <SEP> FIGS. 1a to 1e schematically show cross-sectional views in the thickness of substrates prefiguring watch components, according to several variants of the embodiment of the invention. <tb> <SEP> Figures 2a and 2b schematically represent cross-sectional views through the thickness of a substrate foreshadowing a watch component, respectively after implementation of a first manufacturing step and then of a second manufacturing step of the manufacturing process according to the embodiment of the invention. <tb> <SEP> FIG. 3a represents a comparison of the transmittance (T) as a function of the wavelength (L) of different sapphire crystals according to a first example, obtained by different variants of the manufacturing process depending on the mode embodiment of the invention. <tb> <SEP> Figure 3b is an enlargement of the previous figure. <tb> <SEP> FIG. 3c represents an image taken with a Transmission Electron Microscope (TEM) on a thin slide taken from a colored transparent part at the end of the implementation of the manufacturing process according to the embodiment of invention. An inset represents an electron diffraction image acquired in the area close to the surface (at a distance from the surface less than the distance d). <tb> <SEP> FIG. 4 represents the transmittance (T) as a function of the wavelength (L) of different sapphire crystals according to a second example, obtained by different variants of the manufacturing process according to the embodiment of the 'invention. <tb> <SEP> FIG. 5 represents the transmittance (T) as a function of the wavelength (L) of different sapphire crystals according to a third example, obtained by different variants of the manufacturing process according to the embodiment of the 'invention. <tb> <SEP> FIGS. 6a to 6c represent the transmittance (T) as a function of the wavelength (L) of different sapphire crystals according to a fourth example, obtained by different variants of the manufacturing process according to the embodiment of the invention. <tb> <SEP> FIG. 7 represents the transmittance spectra (T) as a function of the wavelength (L) of different sapphire crystals according to a fifth example, obtained by different variants of the manufacturing process according to the embodiment of the invention.

[0012] For the fluidity of the description, we will use the same references for the different variant embodiments to designate identical or equivalent characteristics.

[0013] In addition, to simplify the following description, we will designate by the adjective "outside" a volume or a surface of a watch component intended for an outward orientation of a timepiece, in particular including a volume or a surface directly visible to an observer of the timepiece. On the contrary, the adjective “interior” will designate a volume or a surface of a watch component intended for orientation towards the interior of a timepiece. In an abusive manner, we will extend the use of the adjectives "exterior" and "interior" to a component which would be entirely placed inside a timepiece, its external surface then being that which would be positioned closest to the outer limit of the timepiece.

On the other hand, we will use the adjective "transparent" to denote the property of a material when the material considered causes transmission, evaluated by the transmission factor Y, greater than 68% inclusive, or even greater. at 79% inclusive, of light radiation comprising at least visible wavelengths. By "transparent material", we consider a material whose nature, combined with the thickness used, allows at least partial transmission of the aforementioned light radiation. Advantageously, the transparent material used also allows at least partial transmission of radiation comprising ultraviolet wavelengths.

We will now describe an embodiment of the invention of a method of manufacturing a sapphire crystal for a timepiece. This same process will be applicable to other watch components, as will be detailed later. This manufacturing process comprises the following two main steps, which form a coloring phase or a coloring process, following a prior step of providing E0 a transparent substrate, that is to say mainly comprising a material transparent: <tb> - <SEP> E1 supply of at least one coloring chemical element on at least one exterior or interior surface of said substrate, otherwise called initial substrate, made available; <tb> - <SEP> Heat treatment E2 of said substrate resulting from the supply step comprising at least one coloring chemical element to obtain a transparent and colored part.

As mentioned above, the method implements a prior step of making available E0 an initial substrate 10. This substrate is advantageously in a substantially planar shape, comprising an outer surface, intended for orientation towards the exterior of a timepiece, and a substantially flat or curved interior surface intended for orientation towards the interior of a timepiece. This substrate is advantageously provided entirely in a transparent material. This transparent material may be colorless. Alternatively, it can be colored. The method could however be applied to a transparent portion of a substrate which would only be locally transparent.

In the embodiment, the transparent material is sapphire, more precisely a monocrystalline synthetic alumina. As a variant, the material could be any other transparent material composed at least partially of inorganic and / or mineral material, such as glass (borosilicate, photostructurable, etc.), corundum, alumina, yttrium garnet and aluminum (YAG), glass ceramic and / or mono or polycrystalline ceramic. The transparent material can also be colored alumina or any other previously colored transparent material.

The initial substrate more advantageously has a shape identical to that of the future glass, or even a similar shape, which may be modified by subsequent steps, for example machining. The substrate more advantageously has a surface condition identical to that of the future ice. Its outer and / or inner surface is preferably polished. As a variant, it can have another surface condition, in particular locally.

[0019] The outer and / or inner surface can be flat. Alternatively, it can be curved, for example concave or convex. It can be curved and preferably continuous, that is to say not composed of juxtaposed facets. It can however include a bevel or a chamfer, in particular at its peripheral part, as will be detailed below.

[0020] As a variant, at least one interior or exterior surface may comprise patterns, which may in particular include time indications or derived from the time, for example machined, forming zones structured in relief and / or recessed.

Figures 1a to 1e illustrate examples of substrates, called initial substrates, proposed in a preliminary step, with a view to manufacturing a watch crystal, according to several variant embodiments.

FIG. 1a thus represents an initial substrate 10 according to a first variant comprising a flat outer surface 2 forming a plane P2, parallel to a flat inner surface 1 forming a plane P1. The substrate further comprises at the periphery a sidewall 3, forming a third planar cylindrical surface which extends from the exterior surface 2 to the interior surface 1, perpendicularly to these two surfaces, over the entire periphery of the substrate. The total thickness e of the initial substrate is defined as the distance between the exterior surface 2 and the interior surface 1. In particular, the total thickness e is measured perpendicular to the interior surface 1 in a direction p perpendicular to the plane P1, in particular at the edges. plans P1, P2. The substrate can of course have any shape, advantageously corresponding to the future timepiece on which it will be mounted, for example circular, ellipsoidal, rectangular, etc. It advantageously has an interior surface with an area greater than or equal to 20 mm <2>, with a view to manufacturing a cyclops or a magnifying glass, or greater than or equal to 80 mm <2>, or even greater or equal to 200 mm <2>, or even greater than or equal to 300 mm <2>, with a view to manufacturing a watch crystal.

Figure 1b shows an initial substrate 10 according to a second variant, which differs from the substrate of the first variant in that the sidewall 3 comprises a part 4 forming a bevel, arranged at the periphery of its outer surface 2. This part 4 bevelled is frustoconical and extends between the outer surface 2 and the rest of the sidewall 3 (between the plane P2 and an intermediate plane P3 parallel to the plane P2). The rest of the sidewall 3 is always perpendicular to the inner surface 1. Advantageously, this bevelled part extends over the entire periphery of the substrate. The bevelled part 4 extends over a thickness f of the substrate, measured perpendicularly to the planes P2, P3, which corresponds substantially to a little less than half of the total thickness e of the substrate. Preferably, the thickness f is between 0.07 and 0.6 times the total thickness e of the substrate. The bevelled part 4 forms a constant angle α with the direction p. Advantageously, the angle α is between 30 ° and 80 °. Alternatively, the angle α and / or the thickness f could vary on the circumference of the ice.

FIG. 1c shows an initial substrate 10 according to a third variant, which forms an intermediate solution between the two previous variants. The at least partly flat sidewall 3 is replaced by a curved sidewall 3, which connects the two outer and inner surfaces by a continuous curve. The curve forming the flank 3 can be characterized at each point by an angle α defined by the angle between the tangent of said curve and the direction p. This angle α is variable, but remains greater than 30 ° on a first part of the flank 3, on the side of the outer surface 2. The rest of the curve forming the flank 3, on the side of the inner surface 1, can be perpendicular or substantially perpendicular to the interior surface 1, with an angle α equal to 0 ° or tending towards 0 °. This first part of the sidewall 3 is similar to the bevelled surface 4 of the second variant.

FIG. 1d shows an initial substrate 10 according to a fourth variant, in which the two outer 2 and inner 1 surfaces are curved, in the same parallel shape. The outer wall is symmetrically arranged around a central axis and the vertex is defined as being the outermost point of the outer surface 2, and the plane P2 as the plane tangent to this curved outer surface 2 and passing through level of this summit. The plane P2 thus corresponds to the outermost plane of the outer surface 2. Likewise, the most inner points of the inner surface 1, that is to say the points defining the periphery of the inner surface , can define a plane P1 tangent to the interior surface 1, and which is parallel to the plane P2. The direction p is defined as the direction perpendicular to the plane P1, in particular to the planes P1, P2. The total thickness e of the substrate then remains defined as the distance between the two planes P1, P2, the total thickness e being measured perpendicular to the plane P1, in the direction p. The sidewall 3 constitutes the peripheral surface which connects the two surfaces. This sidewall 3 comprises a first curved part 4, at the level of the outer surface 2, extended by a part perpendicular to the planes P1, P2 as far as the inner surface 1. The first curved part 4 extends generally between the planes P2 ' and P3, parallel to the planes P1, P2, and has a thickness f, measured perpendicular to the planes P2 ′, P3, strictly less than the total thickness e. Alternatively, a substrate with a flat interior surface 1 and geometric criteria which are moreover equivalent to those of FIG. 1d, can be considered.

Figure 1e shows an initial substrate 10 according to a fifth variant, in which the two outer surfaces 2 and inner 1 are plane and parallel. The sidewall 3 comprises a first part corresponding to a bevel 4, similar to that of the second variant, and a second part comprising a groove. This side also includes a few rounded corners.

In all cases, the total thickness e of the initial substrate 10, and therefore of the watch crystal, is between 0.2 mm and 15 mm, or even between 0.85 mm and 15 mm, or even between 1.45 mm and 11 mm . In addition, whatever the geometric configurations of the ice, an angle α of a sidewall 3, greater than or equal to 10 °, preferably greater than or equal to 15 °, or even greater than or equal to 30 °, will allow a visual effect of modulation of coloring. In addition, whatever the geometric configurations of the ice, the particular part 4 of the sidewall 3 may have a variable area relative to the area of the interior surface 1, and may represent from 1% to 30% of this interior surface 1. , or even between 1% and 18%, or even preferably between 10% and 18% of this interior surface 1.

When the substrate is made available at the end of this preliminary step, the manufacturing method then implements the two main steps of the method, which form a coloring phase of the initial substrate.

The first step consists in providing E1 at least one coloring chemical element.

According to a first variant embodiment, this contribution is made by depositing a coating comprising at least one coloring chemical element on at least one of the two interior or exterior surfaces of the initial substrate. For this, this coating can be deposited by one of the following methods: <tb> - <SEP> A physical vapor deposition (PVD), and particularly magnetron sputtering (MS for Magnetron Sputtering); or <tb> - <SEP> Physical vapor deposition (PVD), and particularly thermal evaporation; or <tb> - <SEP> Chemical vapor deposition (CVD); or <tb> - <SEP> An atomic layer deposition (ALD for Atomic Layer Deposition); or <tb> - <SEP> A liquid phase deposit of the spin-coating, dip-coating or sol-gel type.

According to a second variant embodiment, this supply is carried out by ion implantation by recoil, in particular in the case where the diffusion into the substrate of the coloring chemical element provided in the form of a coating is slow or requires too high a temperature. By "ion implantation by recoil", it is meant a deposition of a thin coating composed of at least one coloring chemical element by PVD, CVD and / or ALD, combined with an ion implantation of said coating by bombardment by a gas such as than argon and / or nitrogen and / or oxygen.

In these variants of providing at least one coloring chemical element, a coating is produced on at least one of the surfaces of the initial substrate, in particular on at least one of the exterior or interior surfaces. This coating can be homogeneous or consist of a superposition of layers made up of different elements. FIG. 2a represents the result obtained after providing a coating 20 on the interior surface 1 of the substrate. This step makes it possible to deposit a coating thickness e ′ very precisely. The coating thickness e ′ may be between 1 nm and 10 μm, in particular between 1 nm and 1 μm. This thickness e 'makes it possible to define the future color as well as the resulting transparency of the colored transparent part, in particular of the watch crystal. A compromise will therefore be made. Too small a coating thickness does not allow coloring, which defines the lower limit of the thickness e '. Too great a thickness does not make it possible to maintain sufficient transparency of the substrate, which defines the upper limit of the thickness e ′. This thickness range depends on the coloring chemical element, the transparent material of the substrate, and the heat treatment that will be applied, detailed below.

On the other hand, the coating can be uniform, that is to say of constant thickness over the entire surface of the substrate, to achieve a homogeneous result. Alternatively, it may be desired to obtain a heterogeneous result; in this case, the coating may be non-uniform.

[0034] For example, the coating can be discontinuous. For this, the method comprises a preliminary step consisting in depositing a mask, for example a resin, on the surface or surfaces concerned by the addition of the coating, in order to obtain only a partial coating, outside the masked areas. Then, after applying the coating, the mask is removed. The masking can be more or less dense, to form a color gradient depending on the masking density. An alternative could consist in coating the surface of the substrate without taking the patterns into account and in removing the layer selectively in order to draw the patterns. For example, it is possible to obtain the deposition of a coating of variable thickness, by a directional vacuum method, such as MS PVD deposition. A thickness gradient of a coating 20 can be obtained by tilting the substrate during deposition or by suitable masking or any other suitable approach.

As an alternative, the contribution of at least one coloring chemical element can be done by direct ion implantation, without the intermediary of a coating. The drawback of this latter alternative lies in the difficulty of controlling the quantity of coloring chemical elements which may be introduced into the substrate, and in the difficulty of obtaining a precise definition of a pattern by masking.

Preferably, the contribution of at least one coloring chemical element is made on a single internal or external surface of the substrate. As a variant, this addition can be carried out on the two inner and outer surfaces, or even on all or part of the sidewall 3.

The coloring chemical element can be chosen from the following non-exhaustive list: <tb> - <SEP> A metallic element, chosen in particular from transition metals; or <tb> - <SEP> An oxide, in particular metallic, formed in particular based on transition metals; or <tb> - <SEP> A metal alloy; or <tb> - <SEP> a metalloid, a non-metal or a gas.

The coloring chemical element is associated with the material of the substrate to obtain a desired color. In particular, for the blue coloring of an alumina substrate, it is known to use cobalt. Of course, the coloring elements such as iron, titanium, gold, chromium, vanadium, copper, manganese, magnesium, zinc, silver, boron, nitrogen, etc. ., can be used to obtain other colors, alone or in combination. Thus, it is possible to combine several distinct elements, for example several coloring chemical elements from the preceding list. For example, adding chromium or gold to alumina can give a red color, and additions of titanium and iron combined can give blue.

As a note, before the step of supplying coloring chemical element (s), the method advantageously comprises a step of cleaning the substrate. Cleaning can consist of a laundry wash followed by rinsing (s) and drying (s).

Then, the method comprises the implementation of a second main step of heat treatment E2 of said substrate resulting from the supply step E1, comprising at least one dye chemical element. This heat treatment comprises the implementation of a step of heating the substrate resulting from the preceding step, then a step of maintaining the substrate at a plateau temperature for a plateau period, before a step of cooling the substrate.

The maximum bearing temperature is especially important to fulfill the function of transferring the coloring chemical element (s) within the initial substrate. The duration of the plateau makes it possible to impact the quantity of chemical coloring elements diffused and / or having reacted, and therefore to modulate the final color, more or less intense. This duration can therefore be chosen over a very wide range. Finally, the rates of temperature change are secondary in the coloring function, and will be chosen to avoid any attack on the initial substrate, in particular to avoid any thermal shock.

Advantageously, the bearing temperature is between 500 ° C and 1850 ° C, or even between 800 ° C and 1400 ° C; more particularly, the bearing temperature is between 900 ° C. and 1200 ° C. for the case of an initial substrate of monocrystalline alumina comprising a coating of cobalt at the end of the supply step E1. The duration of the associated plateau can be very long (up to several days); it is advantageously between 0.5 and 48 hours for the particular case of an initial substrate of monocrystalline alumina comprising a coating of cobalt at the end of step E1, or more generally between 0.5 hour and four days.

[0043] The heat treatment can be done in ambient air. According to one variant, it is carried out in a controlled, inert, oxidizing or reducing atmosphere, or even under vacuum. In particular, the heat treatment can be carried out under a nitrogen atmosphere. According to still other variants, the gas flows and pressures can be varied. In addition, this second heat treatment step E2 can be implemented in a second device separate from a first device provided for the implementation of the first supply step E1. Alternatively, this second step E2 can be implemented within the same equipment as that used for the first supply step E1.

Figure 2b schematically illustrates the result obtained after heat treatment of the substrate resulting from the first step, shown in Figure 2a. At the end of the heat treatment, a zone of modified chemical composition 30 of thickness d is obtained within the volume of the substrate, near the interior surface 1. This zone of modified composition fulfills the coloring function. For example, crystallized alumina of composition Al2O3, initially colorless and transparent, can turn blue with a metered addition of cobalt, forming a zone of composition modified to CoAl2O4 and / or can turn green with a metered addition of cobalt, forming a zone of composition modified by substitution of cobalt in alumina. According to another example, an addition of magnesium to the alumina Al2O3 makes it possible to obtain the magnesium aluminate MgAl2O4. According to yet another example, adding gold to alumina Al2O3 makes it possible to obtain coloring by plasmonic effect. Coloring by the formation of intermetallic compounds can also be considered. This step finishes transforming the initial substrate into a transparent and colored part. The zone of modified chemical composition 30 is thus colored and surprisingly produces the same visual effect as a mirror which would have been colored in the mass, therefore in its entire volume, over its entire thickness. However, the zone of modified chemical composition extends only over a very small thickness d, between 30 and 500 nm, representing on average a maximum of 25% inclusive, or even a maximum of 2% inclusive, or even a maximum of 0.2% inclusive, and preferably at most 0.07% inclusive of the total thickness e of the watch component in the case of coloring carried out on a single surface, interior or exterior. The transparent and colored part thus formed thus always consists mainly of the transparent material coming from the initial substrate 10, and of a small volume of chemically modified and colored transparent material.

By the method thus implemented, a transparent and colored part is obtained, which does not require recovery of its surface condition, not even of the treated surface. Indeed, the thickness e 'of coating in chemical coloring element (s) can be provided so that the coloring chemical element (s) diffuse fully in the substrate 10 and / or react entirely with the substance (s). substrate 10 during heat treatment. Potentially, therefore, it is not necessary to remove an excess of coloring chemical element since the process can be arranged so that the entire amount of coloring chemical element is consumed by the process during the treatment. thermal. Alternatively, it is possible to proceed with the elimination of a possible residue of chemical coloring element on the surface of the part if necessary, by any means known to those skilled in the art (pickling, dissolution, chemical attack, polishing, etc. ).

At the end of this second step, the method can include steps for finalizing the watch component, in particular the watch crystal. For example, if the initial substrate is not a finished watch crystal, for example if it did not have the desired shape, the watch crystal can be obtained by machining the transparent and colored part obtained, in particular by machining ice flanks. For example, a large sapphire plate can be produced and colored, then machined for example with a laser to obtain smaller watch components such as pallets, wheels, glasses, etc. Preferably, a finalization step does not modify the zone of modified chemical composition within said component.

Alternatively, an additional machining step can be performed to finalize the watch component, in particular the watch crystal, for example simply to form a bevel or any peripheral part 4, in particular an inclined part, as illustrated by Figures 1b to 1e, and / or to form a groove or a cyclops or a magnifying glass. As a variant, this step may consist of structuring a pattern in the colored transparent piece, for example with a laser, for purely decorative or marking purposes. Thus, advantageously, laser engraving within the watch crystal does not require any adjustment of parameters, since it acts on the colorless zone of the crystal, that is to say outside the zone of modified chemical composition. , whatever the color of the ice obtained according to the invention.

As a variant, this step can consist in forming a structuring of the colored part. A “structuring” can form raised and / or recessed areas on at least one exterior or interior surface of the colored part, so as to create a perceptible relief or else to modify the colored thickness so as to create one or more color patterns or color gradients or the color of the initial substrate. A structuring can be any non-through opening formed on the surface or in the thickness of the colored part. Such an opening may be a micro-opening or a nano-opening, preferably of a size small enough to be invisible or substantially invisible to the naked eye. Alternatively, such an opening can have a larger dimension, macroscopic, to make it intentionally visible. In all cases, the openings can have any section, not necessarily circular. This section can in fact be rectangular or star, for example, or have any other suitable geometry. Such a structuring can be obtained in particular by any conventional machining technique, or by laser machining, in particular by femtosecond laser machining, or by deep reactive ion etching (DRIE) or even by chemical attack. As a note, a structuring step could be carried out in the initial phase of the method, directly on the initial substrate made available, before the implementation of the two main steps of the method according to the invention. As a variant, a structuring step can be carried out after the first input step E1 of the method, directly on the coating deposited on the substrate, and before the implementation of the second heat treatment step E2 of the method according to the invention. .

An additional step can also consist in assembling the transparent and colored part obtained with another component, obtained by the same process or not. For example, this additional step may consist in assembling a mirror with a cyclops or a magnifying glass or in assembling, in particular gluing, a mirror with a support provided with a skirt for assembling said crystal on a watch case, or in assemble several ice creams together.

Finally, the manufacturing process according to the invention has the following advantages: <tb> - <SEP> The input of chemical coloring element (s) is perfectly controlled, in quantity and location, which allows it to be calibrated and repeated to obtain a desired and identical result at each execution; <tb> - <SEP> Likewise, the heat treatment is controlled and repeatable, in order to obtain a colored transparent part desired and identical for each execution; <tb> - <SEP> The process is therefore compatible with large-scale industrialization and with watchmaking requirements.

The method applies in the same way to the manufacture of any transparent watch component and makes it possible to manufacture a transparent watch component, which comprises a substantially planar or curved inner surface, and which mainly comprises a transparent material, colored by a zone of chemical composition modified within said component by a contribution of at least one coloring chemical element, this zone of modified chemical composition extending over only part of the total thickness of the watch component, that is to say not over its entire thickness, this part representing on average a maximum of 25% inclusive, or even a maximum of 2% inclusive, or even a maximum of 0.2% inclusive, and preferably a maximum of 0.07% inclusive of the total thickness of the watch component, the total thickness of the horological component being measured perpendicular to the interior surface of said component or perpendicular to the tangent formed at the top of the interior surface of said component. Advantageously, the zone of modified chemical composition extends on average over a thickness representing at least 0.0002% of the total thickness of the watch component. As a note, this thickness of the watch component will advantageously be substantially that of the initial substrate. As an alternative embodiment, this thickness of the timepiece component can be reduced compared to the initial total thickness of the initial substrate, but so as to retain the above-mentioned ranges of the thickness of the zone of modified chemical composition.

Thus, the invention applies, for example, to the manufacture of a watch crystal, of a cyclops, of a magnifying glass, of part of a case back, of a dial , a date disc, a watch movement stone, pallets, wheels.

Thanks to the method according to the invention, the watch component obtained has the following advantages: <tb> - <SEP> The coloring is predictable (in hue, particularly blue, and in saturation), repeatable, distributed as desired: it is either homogeneous over the whole of the target area, which can be very large, for example in the case of a sapphire crystal, either heterogeneous and controlled, for example by following a controlled gradient, or predefined patterns or inscriptions. It gives an impression of coloring in the mass, despite the fineness of the zone of modified colored chemical composition. It also gives a visual impression independent of the interior or exterior surface which is treated, and independent of the total thickness of the watch component; <tb> - <SEP> Transparency is guaranteed, to allow, in the case of a watch crystal, the reading of the time or indications derived from the time, the view on the dial, the view on the flange of the caseband, etc. In addition, this transparency also allows a possible charge (excitation) and discharge (emission) of luminescent material, in particular photoluminescent (phosphorescent and / or fluorescent) which would be present under the glass (on / in appliques, needles, decals , ...); <tb> - <SEP> The overall mechanical strength of the initial substrate is maintained at the end of the process: no deterioration of the mechanical properties is induced by the process; <tb> - <SEP> The hardness of the surface of the initial substrate is maintained at the end of the process, on the colored transparent part; <tb> - <SEP> The appearance of the watch component is free from defects, such as non-colored, differently colored, “over-colored” point areas, pitting, localized milky aspects, opening porosities, halos. This absence of defect is obtained over the entire surface of the colored transparent part obtained, which can be large, and perfectly observable by a user, possibly even backlit; <tb> - <SEP> The effects can be modulated by an additional inclined surface, at the level of the side of the watch component, which can, for example, take the form of a bevel; <tb> - <SEP> Other geometric considerations can modulate these effects, such as structured areas in relief and / or recessed on at least one surface of the watch component and / or structured areas within the thickness of the watch. watch component.

The invention will now be illustrated by the implementation of a few series of exemplary embodiments.

In a first series of exemplary embodiments, the substrate 10 of colorless transparent monocrystalline alumina has a geometry corresponding to a final geometry of a finished watch crystal suitable for mounting on a timepiece. This transparent embodiment corresponds to the so-called “reference” embodiment in the table below and in the various examples which follow.

According to this example, the reference watch crystal measures 29.5 mm in diameter and has a total thickness of 1.8 mm. It has a geometry close to that shown in Figure 1e, with a chamfer around the periphery of its outer surface inclined by 36 °, over a height f of 0.8 mm as well as a groove and various machining operations over the rest of the height of the sidewall 3. Its exterior and interior surfaces are polished.

The initial substrate, corresponding to the reference watch crystal specified above, is washed in a detergent bath then rinsed and dried, then placed in an enclosure of PVD thermal evaporation equipment. A metallic cobalt coating is thus deposited on the interior surface of the initial substrate, which corresponds to the first main step of the process described above. The speed and duration of deposition are calibrated so that the coating measures a determined thickness. The deposition thickness is confirmed by X-ray reflectometry. This operation is repeated to form a series of colored pieces comprising several different coating thicknesses e '(set value), which vary from 5 to 80 nm, as summarized in the table below. The heat treatment according to the second main stage of the process is carried out in an identical manner for all the parts of the series, with a plateau at a temperature of 1060 ° C. for 2 hours.

Spectrophotocolorimetric measurements, carried out in transmission on the colored parts resulting from the method according to the embodiment, forming several samples 1.1 to 1.9 at the end of the heat treatment step, are carried out. The results in the CIELab space are presented in the table below. The transmittance measurements are carried out between 360 nm and 740 nm with the observer at 2 ° and the illuminant D65. The brightness L *, the chromatic values a * and b *, the saturation C * and the hue h * (or hue angle) are measured. The transmittance values (T in%) are recorded at 360 nm and 460 nm. The Y is a transmission factor; it takes into account the sensitivity of the eye and the type of lighting: it is calculated by integrating the transmittance spectrum weighted by the response function of the human eye (which is centered on the green part of the visible spectrum) and by the spectrum of the illuminant D65 as defined in the "Technical Report of Colorimetry" CIE 15: 2004. These results show in particular that the difference in coating thickness e 'directly impacts the saturation and the hue of the blue color obtained. , perceptible to the naked eye. At the end of the supply step E1, the ice obtained has an increasingly metallic gray appearance and is less and less transparent, as this thickness e 'increases. At the end of the heat treatment step E2, the ice has an increasingly saturated blue appearance while remaining transparent in a range of cobalt thickness e ′ between 5 nm and 45 nm. Beyond this thickness, for the given heat treatment, the transparency and therefore the transmittance drop.

For example, for sample 1.9 (e '= 80 nm), the transmittance is: <tb> - <SEP> 55.0% at 460 nm, so that the readability through this glass is no longer sufficient and, <tb> - <SEP> 38.0% at 360 nm, so that the charge of a photoluminescent material (phosphorescent and / or fluorescent) through this glass is no longer sufficient.

In the specific case of this series of examples, it is noted that the samples with a thickness e 'less than or equal to 12 nm allow excellent readability. Those which have a thickness e 'less than or equal to 45 nm allow acceptable readability. For a thickness e 'of 80 nm, the sample allows a cloudy reading, because the ice is translucent. For a thickness e 'of 80 nm, the reading becomes more difficult, because the ice becomes less transparent.

The table below gives the results obtained for the samples of this series according to the first example: <tb> Reference <SEP> 0 <SEP> 93.5 <SEP> 1 0.0 <SEP> 0.4 <SEP> 0.4 <SEP> 87.0 <SEP> 82.1 <SEP> 83.6 <SEP> 86.0 <SEP> Colorless <tb> 1.1 <SEP> 5 <SEP> 92.8 <SEP> -1.1 <SEP> -1.3 <SEP> 1.7 <SEP> 227.8 <SEP> 82.6 <SEP> 84.3 <SEP> 81.3 <SEP> Blue <tb> 1.2 <SEP> 6 <SEP> 92.7 <SEP> -1.1 <SEP> -1.7 <SEP> 2.0 <SEP> 235.5 <SEP> 82.7 <SEP> 84.4 <SEP> 82.3 <SEP> Blue <tb> 1.3 <SEP> 8 <SEP> 92.4 <SEP> -1.5 <SEP> -2.1 <SEP> 2.6 <SEP> 234.7 <SEP> 82.6 <SEP> 84.4 <SEP> 81.4 <SEP> Blue <tb> 1.4 <SEP> 9 <SEP> 92.1 <SEP> -1.7 <SEP> -2.4 <SEP> 3.0 <SEP> 234.8 <SEP> 82.6 <SEP> 84.1 <SEP> 80.8 1 <SEP> Blue <tb> 1.5 <SEP> 10 <SEP> 91.9 <SEP> -1.8 <SEP> -2.7 <SEP> 3.3 <SEP> 235.5 <SEP> 82.6 <SEP> 84.0 <SEP> 80.4 <SEP> Blue <tb> 1.6 <SEP> 12 <SEP> 91.5 <SEP> -2.0 <SEP> -3.2 <SEP> 3.8 <SEP> 237.9 <SEP> 82.9 <SEP> 84.0 <SEP> 79.7 <SEP> Blue <tb> 1.7 <SEP> 30 <SEP> 88.6 <SEP> -3.3 <SEP> -8.0 <SEP> 8.6 <SEP> 247.2 <SEP> 81.0 <SEP> 83.6 <SEP> 73.3 <SEP> Blue <tb> 1.8 <SEP> 45 <SEP> 86.2 <SEP> -5.0 <SEP> -11.8 <SEP> 12.8 <SEP> 247.0 <SEP> 78.6 <SEP> 83.5 <SEP> 68.4 <SEP> Blue <tb> 1.9 <SEP> 80 <SEP> 71.7 <SEP> -7.7 <SEP> -8.0 <SEP> 11.1 <SEP> 225.5 <SEP> 38.0 <SEP> 55.0 <SEP> 43.2 <SEP> Blue-gray

To illustrate these results, FIG. 3a represents the transmittance spectra (T in%) as a function of the wavelength (L in nm) for several coating thicknesses according to the series of this first example. FIG. 3b is an enlargement of this FIG. 3a.

In addition, we note that when we observe the ice, the coloring appears more intense through the peripheral bevel than through its flat outer surface. In other words, the color effect is modulated by the angle a. This effect has its origin in the geometry of the part. This makes it possible to illustrate the advantage of providing an inclined portion at the level of the outer surface of the ice, as was mentioned previously and is illustrated in FIGS. 1b to 1e.

As a note, the observed blue tint comes from a chemical reaction of cobalt, alumina and oxygen, giving a cobalt aluminate, potentially CoAl2O4, during the heat treatment, at the level of the composition zone chemical modification of the colored transparent part obtained. FIG. 3c is an image taken with a Transmission Electron Microscope (TEM) on a thin slide taken by a focused ion beam (FIB) on the colored transparent part, perpendicular to the inner surface of the colored transparent part obtained. An insert in this figure shows an electron diffraction image acquired in the area close to the treated interior surface, and more precisely at a distance less than d from this surface. This image makes it possible to confirm the formation of cobalt aluminate during the coloring phase of the sapphire crystal as well as the thickness d.

The overall mechanical properties of the glasses obtained are not degraded by the implementation of the method according to the invention. This result is verified on a batch of additional samples of watch glasses, still obtained from the same reference substrate, coated by magnetron sputtering with layers of different thicknesses of cobalt, then heat treated with a three hour step at 1000 ° C. The tensile strength and hardness of the glasses are not affected by the presence of the colored chemically modified zone.

In a second series of exemplary embodiments, the initial substrate 10 made of colorless transparent monocrystalline alumina used has a geometry corresponding to a final geometry of a finished watch crystal, called reference, in an identical manner to the series according to the first example described above. Samples of colored parts are formed by varying the heat treatment applied, more specifically by varying the temperature of the three hour bearing. All these samples were previously coated by thermal evaporation with a 10 nm deposit of metallic cobalt on the interior surface of the substrate.

The table below summarizes the results obtained for these samples: <tb> Reference <SEP> / <SEP> 93.5 <SEP> 0 <SEP> 0.4 <SEP> 0.4 <SEP> 87.0 <SEP> 82.1 <SEP> 83.6 <SEP> 86.0 <SEP> Colorless <tb> 2.1 <SEP> 900 <SEP> 89 <SEP> -2.6 <SEP> 3.6 <SEP> 4.8 <SEP> 137.7 <SEP> 65.8 <SEP> 70.2 <SEP> 74.2 <SEP> Green <tb> 2.2 <SEP> 1000 <SEP> 91.8 <SEP> -1.8 <SEP> -2.7 <SEP> 3.2 <SEP> 236.3 <SEP> 81.5 <SEP> 83.9 <SEP> 80.3 <SEP> Blue <tb> 2.3 <SEP> 1200 <SEP> 92 <SEP> -1.7 <SEP> -2.6 <SEP> 3.1 <SEP> 236 <SEP> 82.9 <SEP> 84.1 <SEP> 80.7 <SEP> Blue <tb> 2.4 <SEP> 1400 <SEP> 94.1 <SEP> 0 <SEP> 0.1 <SEP> 0.2 <SEP> 80 <SEP> 84.7 <SEP> 85.2 <SEP> 85.4 <SEP> Colorless

In addition, FIG. 4 represents the transmittance spectra (T in%) as a function of the wavelength (L in nm) for several plateau temperatures (Tp in ° C) according to the series of this second example .

It is noted in particular that the samples 2.1 to 2.3 have a tint angle which increases with the plateau temperature, that the sample 2.1 is green while the samples 2.2 and 2.3 are blue. Beyond a treatment at 1400 ° C (sample 2.4), the sapphire crystal becomes transparent and colorless, similar to an untreated sapphire crystal (reference sample).

A third series of exemplary embodiments makes it possible to obtain samples in a manner similar to the second series, but by varying the duration of the heat treatment stage applied from 30 minutes to 48 hours, for a stage temperature still equal to 900 ° C. All these samples were previously coated by thermal evaporation with a 5 nm deposit of metallic cobalt on the interior surface of the substrate.

The table below summarizes the results obtained for these samples: <tb> Reference <SEP> 0 <SEP> 93.5 <SEP> 0.0 <SEP> 0.4 <SEP> 0.4 <SEP> 87.0 <SEP> 82.1 <SEP> 83.6 <SEP> 86.0 <SEP> Colorless <tb> 3.1 <SEP> 0.5 <SEP> 90.2 <SEP> -1.6 <SEP> 3.3 <SEP> 3.7 <SEP> 116.3 <SEP> 70.2 <SEP> 74.4 <SEP> 78.3 <SEP> Gray-green <tb> 3.2 <SEP> 1 <SEP> 92.3 <SEP> -1.4 <SEP> 0.4 <SEP> 1.5 <SEP> 165.6 <SEP> 77.1 <SEP> 81.1 <SEP> 81.4 <SEP> Green <tb> 3.3 <SEP> 3 <SEP> 92.9 <SEP> -1.0 <SEP> -1.3 <SEP> 1.6 <SEP> 230.3 <SEP> 81.9 <SEP> 84.5 <SEP> 82.7 <SEP> Blue <tb> 3.4 <SEP> 48 <SEP> 93 <SEP> -1.0 <SEP> -1.3 <SEP> 1.6 <SEP> 234.6 <SEP> 82.8 <SEP> 84.7 <SEP> 82.8 <SEP> Blue

In addition, FIG. 5 represents the transmittance spectra (T in%) as a function of the wavelength (L in nm) for several durations (t in h) of plateau according to the series of this third example.

It is observed in particular that with the increase in the duration of the heat treatment, the coating reacts more effectively with the ice, which results in an increase in the transmittance and the establishment of the blue color. After three hours of thermal treatment (sample 3.3), the sapphire crystal is blue and sufficiently transparent in the wavelengths allowing both good readability and the possible charge and discharge of photoluminescent material.

In a fourth series of exemplary embodiments, the initial substrate 10 used still corresponds to the finished reference watch crystal, in an identical manner to the series according to the first example described above. Samples are made by varying the heat treatment applied, more precisely the temperature and / or the duration of the applied plateau (s). All these samples were previously implanted with iron, cobalt or titanium, by an ionic implantation process using an ion beam (direct implantation of the ions from the ion beam).

The table below summarizes the results obtained by these samples: <tb> reference <SEP> none <SEP> none <SEP> 94.2 <SEP> 0.1 <SEP> 0.2 <SEP> 0.2 <SEP> 69.7 <SEP> 85.3 <SEP> 85.6 <SEP> 85.8 <SEP> Colorless <tb> 4.1 <SEP> Iron <SEP> none <SEP> 75.2 <SEP> 0.4 <SEP> 7.5 <SEP> 7.5 <SEP> 86.9 <SEP> 32.0 <SEP> 42.4 <SEP> 48.5 <SEP> Brown <tb> 4.2 <SEP> Iron <SEP> 900 ° C 30 min <SEP> 86.3 <SEP> 2.0 <SEP> 16.7 <SEP> 16.8 <SEP> 83.3 <SEP> 36.5 <SEP> 52.7 <SEP> 68.5 <SEP > Orange <tb> 4.3 <SEP> Iron <SEP> 1000 ° C 3h <SEP> 87.0 <SEP> 1.9 <SEP> 16.7 <SEP> 16.8 <SEP> 83.5 <SEP> 42.1 <SEP> 53.7 <SEP> 70.0 <SEP> Orange <tb> 4.4 <SEP> Iron <SEP> 1600 ° C 3h <SEP> 94.1 <SEP> 0.0 <SEP> 0.1 <SEP> 0.1 <SEP> 80.0 <SEP> 85.0 <SEP> 85.2 <SEP> 85.4 <SEP> Colorless <tb> 4.5 <SEP> Cobalt <SEP> 900 ° C 30 min <SEP> 86.5 <SEP> -2.7 <SEP> 5.5 <SEP> 6.1 <SEP> 116.0 <SEP> 57.5 <SEP> 62.9 <SEP> 69.0 < SEP> Grisvert <tb> 4.6 <SEP> Cobalt <SEP> 1000 ° C 3h <SEP> 92.0 <SEP> -1.8 <SEP> -2.9 <SEP> 3.4 <SEP> 238.5 <SEP> 83.0 <SEP> 84.7 <SEP> 80.8 < SEP> Blue <tb> 4.7 <SEP> Cobalt <SEP> 1600 ° C 3h <SEP> 94.2 <SEP> 0.0 <SEP> 0.2 <SEP> 0.2 <SEP> 84.6 <SEP> 85.3 <SEP> 85.5 <SEP> 85.7 <SEP> Colorless <tb> 4.8 <SEP> Titanium <SEP> 900 ° C 30 min <SEP> 91.8 <SEP> -3.6 <SEP> 5.7 <SEP> 6.7 <SEP> 121.9 <SEP> 41.2 <SEP> 74.1 <SEP> 80.3 < SEP> Yellow <tb> 4.9 <SEP> Titanium <SEP> 1000 ° C 3h <SEP> 91.8 <SEP> -5.0 <SEP> 10.1 <SEP> 11.3 <SEP> 116.5 <SEP> 37.4 <SEP> 69.1 <SEP> 80.2 <SEP > Yellow

In addition, FIGS. 6a to 6c represent the transmittance spectra (T in%) as a function of the wavelength (L in nm) for the samples forming the series of this fourth example.

It is observed in particular that iron gives an orange color (at 900 ° C and 1000 ° C), that cobalt gives a gray color at 900 ° C and blue at 1000 ° C, titanium gives a slight yellowing (at 900 ° C and 1000 ° C). Whether with iron or cobalt, the treatment at 1600 ° C gives a transparent and colorless ice.

The hardness and elastic modulus values obtained by nano-indentation on the samples forming the series of this fourth example make it possible to conclude that the mechanical properties (hardness and elasticity) of the sapphire crystal are not influenced by the process of staining involving ion implantation and heat treatments, under the conditions tested.

In a fifth series of exemplary embodiments, the initial substrate 10 made of colorless transparent monocrystalline alumina used has a geometry corresponding to a final geometry of a finished watch crystal, called reference, in an identical manner to the series according to the first example described above. The initial substrate, corresponding to the reference watch crystal, is washed in a detergent bath then rinsed and dried, then placed in an enclosure of PVD thermal evaporation equipment. A metallic cobalt coating is thus deposited on the interior 1 or exterior surface and bevel 2 + 4, of the initial substrate. This operation is repeated to form a series of colored pieces comprising several different thicknesses of coating e '(set value), of 3, 6 or 9 nm, as summarized in the table below. Implantation by recoil is implemented in a similar manner for all the parts of the series, in the same equipment, by the plasma immersion method, with bombardment by argon ions; only the dose of implanted ions (D expressed in atoms / cm <2> with an energy of 10 kV) changes, as summarized in the table below. These operations correspond to the first main step of the method described above. The heat treatment according to the second main step of the process is implemented in an identical manner for all the parts of the series, with a plateau at a temperature of 1000 ° C for 3 hours.

The table below summarizes the results obtained for these samples: <tb> Reference <SEP> 0 <SEP> / <SEP> / <SEP> 93.5 <SEP> 0.0 <SEP> 0.4 <SEP> 0.4 <SEP> 87.0 <SEP> 82.1 <SEP> 83.6 <SEP> 86.0 <SEP > Colorless <tb> 5.1 <SEP> 3 <SEP> 3.0 10 <15> <SEP> 1 <SEP> 93.4 <SEP> -0.6 <SEP> -0.9 <SEP> 1.0 <SEP> 236.4 <SEP> 83.4 <SEP> 85.2 <SEP> 83.9 <SEP> Blue <tb> 5.2 <SEP> 6 <SEP> 1.0 10 <16> <SEP> 1 <SEP> 93.2 <SEP> -0.8 <SEP> -1.6 <SEP> 1.8 <SEP> 242.4 <SEP> 84.0 <SEP> 85.6 <SEP> 83.4 <SEP> Blue <tb> 5.3 <SEP> 9 <SEP> 1.0 10 <16> <SEP> 1 <SEP> 92.0 <SEP> -1.8 <SEP> -2.3 <SEP> 2.9 <SEP> 233.0 <SEP> 81.6 <SEP> 83.9 <SEP> 80.8 <SEP> Blue <tb> 5.4 <SEP> 3 <SEP> 3.0 10 <15> <SEP> 2 + 4 <SEP> 93.4 <SEP> -0.6 <SEP> -0.8 <SEP> 1.0 <SEP> 236.3 <SEP> 83.4 <SEP > 85.2 <SEP> 84.0 <SEP> Blue <tb> 5.5 <SEP> 6 <SEP> 1.0 10 <16> <SEP> 2 + 4 <SEP> 93.2 <SEP> -0.7 <SEP> -1.5 <SEP> 1.6 <SEP> 245.4 <SEP> 84.3 <SEP > 85.4 <SEP> 83.4 <SEP> Blue <tb> 5.6 <SEP> 9 <SEP> 1.0 10 <16> <SEP> 2 + 4 <SEP> 92.2 <SEP> -1.7 <SEP> -2.3 <SEP> 2.9 <SEP> 234.2 <SEP> 82.1 <SEP > 84.3 <SEP> 81.1 <SEP> Blue

In addition, FIG. 7 represents the transmittance spectra (T in%) as a function of the wavelength (L in nm) for several values of coating thickness e 'and doses of implanted ions D according to the series of this fifth example.

It is observed in particular that the samples obtained are blue; samples 5.1 to 5.3 and 5.4 to 5.6 have a saturation C * which increases with the coating thickness e '. With identical treatment parameters, the results are similar regardless of the treated surface (surface 1 or surfaces 2 + 4).

The sixth example is particularly interested in the impact of a colored watch crystal, blue in this example, on the charging (excitation) and discharging (emission) performance of a photoluminescent material which would be placed on a dial under the inner surface of the watch crystal. A blue ice (sample 6) is prepared according to the embodiment in which a deposit of 9 nm of cobalt is carried out by thermal evaporation on a substrate 10 in colorless transparent monocrystalline alumina, and followed by a thermal treatment comprising a stage of 2 hours at 1060 ° C.

The results of spectrophotocolorimetric transmission measurements carried out on sample 6 and on the reference glass are given in the table below. <tb> Reference <SEP> 0 <SEP> 93.5 <SEP> 0.0 <SEP> 0.4 <SEP> 0.4 <SEP> 87.0 <SEP> 85.3 <SEP> 85.6 <SEP> 86.0 <SEP> - <SEP> - <SEP > Colorless <tb> 6 <SEP> 9 <SEP> 92.1 <SEP> -1.7 <SEP> -2.4 <SEP> 2.9 <SEP> 235.1 <SEP> 82.7 <SEP> 84.3 <SEP> 80.9 <SEP> 1060 <SEP> 2 <SEP> Blue

The two glasses (reference and of sample 6) are mounted successively on the same watch, comprising appliques and hands with a commercial photoluminescent material. The luminous performances of the assembly with the blue lens (sample 6) and with the reference lens are compared after keeping the watch in the dark for more than 24 hours, followed by standardized illumination (20 minutes at 400 lux with illuminant D65). The luminous decay [nCd] as a function of the dwell time in the dark is measured by photometry. The relative drop in luminous performance of the blue ice (sample 6) is evaluated in percent of the light intensity of the reference glass. The relative drop in luminous performance due to the coloring of sample 6 is 0.8% from 0 to 8 hours and 1.7% from 0 to 22 hours. By comparison with a colorless reference lens, the use of a blue lens according to sample 6 therefore has no perceptible influence by the wearer of the watch on the performance of the photoluminescent material tested.

Naturally, the preceding examples are carried out in a nonlimiting manner, to illustrate the results obtained with the implementation of the concept of the invention. They could be reproduced on any other transparent watch component than a watch crystal, with similar effects.

The results clearly illustrate the advantages obtained by the process of the invention. On this basis, a person skilled in the art will know how to adapt the deposit thicknesses e ′, the materials to be used, and the heat treatment parameters as a function of the result he wishes to achieve, in particular in terms of color and transparency. In particular, it will be advantageous to choose to achieve a transmission factor (Y) greater than or equal to 68% inclusive, or even greater than or equal to 79% inclusive. A substrate may also be chosen such that the watch component obtained has an average hardness of the outer surface greater than or equal to 30 GPa and / or greater than or equal to 2016 HV0.2, particularly in the case of a watch crystal.

Claims (20)

1. Transparent watch component, in particular watch crystal, characterized in that it comprises a substantially flat or curved inner surface, and in that it mainly comprises a transparent material, colored by a zone of modified chemical composition within said component by adding at least one coloring chemical element to said transparent material, this zone of modified chemical composition extending over only part of the total thickness of the watch component. 2. Watch component according to the preceding claim, characterized in that the zone of modified chemical composition extends over a thickness representing on average at most 25% inclusive, or even at most 2% inclusive, or even at most 0.2% inclusive, or even at most. maximum 0.07% inclusive of the total thickness of the watch component. 3. Watch component according to one of the preceding claims, characterized in that the zone of modified chemical composition extends over a thickness representing on average at least 0.0002% of the total thickness of the watch component. 4. Watch component according to one of the preceding claims, characterized in that said transparent material, colorless or previously colored, is an inorganic and / or mineral material, such as monocrystalline or sapphire synthetic alumina, corundum, or in this that said transparent material is a material composed at least partially of inorganic and / or mineral matter, such as glass, corundum, alumina, a material based on yttrium and aluminum garnet (YAG), glass ceramic and / or mono or polycrystalline ceramic. 5. Watch component according to one of the preceding claims, characterized in that at least one coloring chemical element is chosen from a metal, and / or a metal oxide, and / or a metal compound, and / or a metal alloy, and / or a transition metal, and / or a transition metal oxide and / or a metalloid and / or a non-metal and / or a gas. 6. Watch component according to the preceding claim, characterized in that at least one coloring chemical element is chosen from cobalt, and / or iron, and / or chromium, and / or gold, and / or titanium. , and / or vanadium, and / or copper, and / or manganese, and / or magnesium, and / or zinc, and / or silver, and / or boron, and / or nitrogen . 7. Watch component according to one of the preceding claims, characterized in that the zone of modified chemical composition comprises cobalt aluminate and / or cobalt so as to obtain a watch component of blue and / or green color or in that the zone of modified chemical composition comprises gold so as to obtain a watch component of pink or red color. 8. Timepiece component according to one of the preceding claims, characterized in that it has an inner surface having an area greater than or equal to 20 mm <2> and a thickness greater than or equal to 0.85 mm. 9. Watch component according to one of the preceding claims, characterized in that it is a watch crystal having an inner surface having an area greater than or equal to 80 mm <2> or even greater than or equal to 200 mm <2>, or even greater than or equal to 300 mm <2>, and a thickness greater than or equal to 0.2 mm and / or less than or equal to 15 mm. 10. Watch component according to claim 8 or 9, characterized in that it is transparent so as to allow the reading of indications, in particular time, through its thickness and optionally so as to allow charging and / or discharging. of a photoluminescent material through its thickness, and / or in that it comprises a transmission factor (Y) greater than or equal to 68%. 11. Watch component according to the preceding claim, characterized in that it is a watch crystal which comprises an outer surface and which comprises a lateral surface inclined with respect to said outer surface, of inclination greater than or equal to 10 degrees, or even greater than or equal to 15 degrees, or even greater than or equal to 30 degrees, relative to the direction perpendicular to the interior surface, so as to modulate the coloring effect of the watch crystal and / or in that it comprises structured areas in relief and / or recessed on at least one surface of the watch component and / or structured areas within the thickness of the watch component. 12. Timepiece component according to the preceding claim, characterized in that the inclined lateral surface represents between 1% and 30% of the surface area of the interior surface or even between 1% and 18% of the surface area of the interior surface, or even between 10%. and 18% of the area of the interior surface. 13. Timepiece component according to one of the preceding claims, characterized in that it comprises all or part of the following characteristics: at. A thickness gradient of the zone of modified chemical composition, so as to modulate the coloring effect of the watch component; and or b. A discontinuity of the zone of modified chemical composition, in particular forming a pattern. 14. Timepiece, characterized in that it comprises a watch component according to one of the preceding claims. 15. A method of manufacturing a colored and transparent watch component, characterized in that it comprises the following steps: at. Providing (E0) an initial substrate which comprises a substantially planar or curved interior surface composed mainly of a transparent material; b. Supply (E1) of at least one coloring chemical element by at least one exterior or interior surface of said initial substrate; vs. Heat treatment (E2) of said substrate resulting from the supply step (E1) comprising at least one coloring chemical element to obtain a transparent and colored part. 16. A method of manufacturing a watch component according to the preceding claim, characterized in that the supply step (E1) comprises a step of depositing a coating comprising at least one chemical coloring element on at least one surface of the initial substrate, in particular by physical vapor deposition (PVD) by magnetron sputtering (MS) and / or by thermal evaporation, and / or by atomic layer deposition (ALD) and / or by chemical vapor deposition (CVD) , and / or in that the supply step (E1) comprises an ion implantation step by retraction of at least one dye chemical element. 17. A method of manufacturing a watch component according to the preceding claim, characterized in that the watch component is a watch crystal and in that the supply step (E1) comprises a step of depositing a coating of 'thickness between 1 nm and 10 μm inclusive, or even between 1 nm and 1 μm. 18. A method of manufacturing a watch component according to one of claims 15 to 17, characterized in that the supply step (E1) comprises a step of depositing a coating and a prior step of masking a surface of the substrate to prevent it from receiving said coating and / or to form a coating of varying thickness. 19. A method of manufacturing a watch component according to one of claims 15 to 18, characterized in that the heat treatment step (E2) comprises a bearing at a bearing temperature of between 500 ° C and 1850 ° C. , or even between 800 ° C and 1400 ° C, or even between 900 ° C and 1200 ° C and a period of between 0.5 and 48 hours, or even between 0.5 hour and four days. 20. A method of manufacturing a watch component according to one of claims 15 to 19, characterized in that it comprises all or part of the following additional steps: at. Machining of the transparent and colored part to form the watch component; and or b. Machining of at least one surface of the transparent and colored part to modify its shape and / or form a pattern and / or form a lateral surface inclined relative to an external surface of the watch component, with an inclination greater than or equal to 10 degrees , or even greater than or equal to 15 degrees, or even greater than or equal to 30 degrees, relative to the direction perpendicular to the interior surface so as to modulate the effect of coloring of the watch component; and or vs. Assembly of the transparent and colored part with another watch component; and or d. Removal of a coloring chemical element residue from a surface of the transparent and colored part, in particular by chemical etching or a mechanical action such as polishing; and or e. Engraving of a pattern within the watch component.