CH719162A2 - Watch case comprising a covering component on which is deposited a stack of thin layers. - Google Patents

Abstract

The invention relates to a watch case (10) comprising a middle part (11) to which is attached a crystal (12) and a back (13) so as to form an internal volume, said watch case (10) comprising, in said internal volume, a covering component (14) on which is deposited a stack of thin layers (15) comprising a substrate layer, a phase-switched layer in the solid state interposed between a transparent encapsulation layer and a spacer layer separating said phase-switched layer from the substrate layer, the phase-switched layer being configured to have an index of refraction which is able to vary under exposure of light rays so as to impart to the stack of thin layers (15) of at least two interference colors. The invention also relates to a process for decorating the trim component consisting in exposing the stack of thin layers to light rays, so as to locally change phase and thus generate a pattern.

Description

Technical field of the invention

The invention relates to the field of watchmaking, and relates more particularly to a watch case comprising a covering component on which is deposited a stack of thin layers.

Technology background

[0002] Thin layers are commonly used in the field of watchmaking to modify the surface properties of watch components. They are used in particular for decorative purposes.

Several methods can be implemented to deposit thin layers: physical vapor deposition, known by the acronym "PVD" for "physical vapor deposition" in English, chemical vapor deposition, known as acronym „CVD“ for „chemical vapor deposition“, the deposition of atomic layers, known under the acronym „ALD“ for „Atomic Layer Deposition“, or galvanic growth.

[0004] The thin layers can be made of pure metal, of metal alloys, or of ceramic materials.

[0005] Nevertheless, these thin layers offer a relatively limited range of intrinsic colors depending on their composition and their thickness. Moreover, these layers are more or less translucent depending on their composition and their thickness, and their color is not very saturated.

[0006] A greater range of colors and more saturated colors can be obtained thanks to the interference colors obtained by stacking different thin layers, typically made of semi-transparent dielectric material, deposited on a reflective layer formed by a metallic mirror .

[0007] Nevertheless, the color of these stacks strongly depends on the optical thickness of the thin layers, which is typically of the order of a quarter of the wavelengths of the visible spectrum, which requires precise control of the thickness of the deposit and limits their application to substrates in flat form, that is to say in two dimensions. Also, the color of these thin layers perceived by a user varies greatly depending on his viewing angle because the length of the optical path changes, which represents a major drawback for certain aesthetic applications.

[0008] All the aforementioned thin layers are monochrome and a multicolored decoration requires as many deposition steps as there are colors desired, said deposition steps being followed by intermediate structuring steps typically carried out by photolithography and chemical etching, a so-called "lift" process. -off“, „shadow mask“, or laser ablation.

[0009] These structuring steps often prove to be tedious and costly in order to comply with the tolerance requirements. Moreover, they are messy, in particular because they use chemical baths or because they produce gases, dust and other residues. The structuring steps are therefore followed by a washing step before the assembly, in the watch, of the component produced.

[0010] There is therefore a need to provide a component with bright and saturated colors over a wide range of colors, the appearance of which is not or is only slightly dependent on the viewing angle of the component, and whose structuring of these colors is not messy or likely to release gas, dust or other residues.

Summary of the invention

[0011] The present invention relates to a watch case comprising a middle part to which is fixed a crystal and a bottom so as to form an internal volume, said case comprising, in said internal volume, a covering component on which is deposited a stacking of thin layers.

[0012] The stack of thin layers comprises a layer of substrate, a phase-switching layer in the solid state interposed between a transparent encapsulation layer and a spacer layer separating said phase-switching layer from the layer of substrate.

[0013] Thanks to the particular arrangement of the stack of thin layers, the covering component has optical properties producing interference colors.

[0014] In the present text, “interferential color” is called a color generated by an optical phenomenon of interference.

The phase-switched layer is configured so as to present a crystallographic phase change by thermal effect, in particular under the exposure of locally absorbed light rays. The crystallographic phase change of the phase-switched layer involves a change in its refractive index so as to give the stack of thin layers at least two different interferential colors between the zones exposed to light rays and the non-exposed zones to light rays.

[0016] Thus, a wide range of saturated and intense colors can be generated, in particular by varying the thicknesses of the phase-switched layer and of the spacer layer, and a multicolored decoration of the covering component can be obtained.

[0017] It should be noted that the light rays pass through the glass or the bottom if the latter comprises a glass, and depending on where the trim component is placed.

[0018] As the phase switching does not produce any gaseous, solid or liquid release, the production of at least two interference colors, and consequently the decoration of the covering component, does not require any subsequent cleaning operation.

[0019] Thus, it is possible to decorate the trim component at the end of production of the watch case, when the watch case is sold, or in an after-sales period. This aspect authorizes any customization of the decoration of the covering component.

[0020] In particular embodiments, the invention may also comprise one or more of the following characteristics, taken in isolation or in all technically possible combinations.

In particular embodiments, the phase-switched layer is configured to have two reversibly switchable phase states, said phase states being a crystalline phase and an amorphous phase.

[0022] The decoration of the covering component is thus reversible.

[0023] In particular embodiments, the encapsulation layer is transparent to the wavelength of the light rays under whose exposure the refractive index of the phase-switched layer is able to vary.

In particular embodiments, the substrate layer is formed by a reflective layer.

In particular embodiments, the stack of thin layers is deposited on a support consisting of all or part of the covering component, the substrate layer being deposited on said support so as to separate the spacer layer of said medium.

In particular embodiments, the substrate layer is made of transparent or translucent material.

In particular embodiments, the stack of thin layers is deposited on a support consisting of all or part of the covering component, the substrate layer or the encapsulation layer being formed by the support.

[0028] In particular embodiments, the covering component is a dial, a structure of a watch movement, a crystal, a hand, an applique, a logo, a disc or an oscillating mass.

Another aspect of the invention relates to a process for decorating the covering component of a watch case as described above, consisting in exposing the stack of thin layers to light rays on an exposure zone predefined, so as to locally change the phase of the phase-switched layer, and consequently its refractive index, and consequently also the interference color of the stack in said exposure zone, and thus to generate a two-color pattern on said trim component.

[0030] Thus it is possible to produce a two-tone decoration on the covering component of the watch case when the latter is assembled, and therefore to personalize the decoration of the covering component at any time in the life of said case. of watch.

In embodiments of the invention, the light rays are generated by a laser beam controlled by a control unit, so as to control the localized rise in the temperature of the phase-switched layer, the exposure time and shape of the predefined exposure area

[0032] Thanks to this characteristic, the patterns can be generated very precisely, so as to allow a very wide variety of possible decorations and to allow a high quality of production of these decorations.

Brief description of figures

Other characteristics and advantages of the invention will appear on reading the following detailed description given by way of non-limiting example, with reference to the accompanying drawings in which: - Figure 1 schematically represents a sectional view of a watch case according to the present invention; - Figure 2 schematically shows a sectional view of a trim component of the watch case of Figure 1 according to an embodiment of the invention; - Figure 3 schematically shows a sectional view of a covering component of the watch case of Figure 1 according to another embodiment of the invention in which the covering component forms a support constituting a layer of encapsulation; - Figure 4 schematically shows a sectional view of a covering component of the watch case of Figure 1 according to yet another embodiment of the invention in which the support constitutes a substrate layer; - Figure 5 schematically shows a sectional view of a covering component of the watch case of Figure 4 according to yet another embodiment of the invention in which the substrate layer is transparent; - Figure 6 schematically shows a sectional view of a covering component of the watch case of Figure 3 according to yet another embodiment of the invention in which the substrate layer is transparent.

Detailed description of the invention

Figure 1 shows a schematic representation of a sectional view of a watch case 10 according to the present invention. The watch case 10 comprises a middle part 11 to which is attached a crystal 12 and a back 13 so as to form an internal volume.

The watch case 10 comprises, in said internal volume, a covering component 14 on which is deposited a stack of thin layers 15. In other words, the stack of thin layers 15 constitutes a coating of the covering component 14.

The stack of thin layers 15 is configured so as to give the covering component 14, on a surface of the latter intended to be visible to a user, several predetermined interference colors as described in more detail below.

Advantageously, the covering component 14 can be formed by a dial, as shown in Figure 1, by a structure of a watch movement 17, for example a bridge or a plate, by an oscillating mass, a flange, or by any other component housed in the internal volume of the watch case 10 or on said watch case 10, such as the back 13, the crystal 12, a bezel, etc.

It should be noted that, in this text, the term ice is used hereafter to designate the ice 12 or a possible bottom ice 13.

The stack of thin layers 15 comprises a substrate layer 150, a phase switching layer 151 in the solid state interposed between a transparent encapsulation layer 152 and a spacer layer 153 separating said switching layer phase 151 of the substrate layer 150.

[0040] It should be noted that the term “transparent” designates in the present text a capacity of a material to allow all or part of a light radiation to pass, in particular light visible to the naked eye.

The interference colors are generated by an interference effect produced by the arrangement of the encapsulation layer 152, the phase switching layer 151, the spacing layer 153 and the substrate layer 150 , in a reflective or transmissive manner according to the embodiment of the present invention considered.

In the exemplary embodiment of the invention shown in Figure 2, the stack of thin layers 15 can be deposited on a support, made of any suitable material, said support being constituted by all or part of the component of dressing 14. In other words, the substrate layer 150 is arranged against the support and separates the spacer layer 153 from the support.

For example, the support can be made of metallic material, silicon with native oxide, glass, quartz, sapphire, polyethylene terephthalate, for example in the form of a film.

In the embodiment shown in Figure 2, the substrate layer 150 may be formed by a reflective layer, for example made by a metal mirror, preferably made of a material having a high reflection factor, for example platinum, rhodium, silver, aluminum, etc. This layer can have a thickness, defined here as being the dimension along the direction in which the thin layers are superimposed on each other, of about 100 nm.

The spacing layer 153 is made of transparent dielectric material. Such a material can be indium-tin oxide, silicon dioxide or zinc sulfide. Preferably, the spacing layer 153 has a thickness of between 50 nm and 200 nm.

The phase-switched layer 151 has the ability, due to the material that constitutes it, to change from a crystalline or amorphous phase to a respectively amorphous or crystalline phase, under the exposure of suitable light rays.

Such light rays are shown in Figure 1 by the arrow in broken lines.

In particular, the phase switching layer 151 is configured to have two switchable phase states, preferably reversibly. In other words, the phase-switched layer 151 is configured to be able to pass, following exposure to light rays, from an initial crystalline or amorphous phase to a respectively final amorphous or crystalline phase, and to return to its phase. initial.

More specifically, the exposure of the stack of thin layers 15 to light rays locally generates a localized rise in temperature of the phase-switched layer 151. A temperature located above the glass transition point applied for a fairly long time, for example several seconds or tens of seconds, induces crystallization of the phase-switched layer 151, that is to say a change from the amorphous phase to the crystalline phase, and a temperature situated above of the melting point applied for a sufficiently short time to freeze the amorphous phase without recrystallization induces an amorphization of the phase-switched layer 151, that is to say a change from the crystalline phase to the amorphous phase.

[0050] As a preferred example, the phase-switched layer 151 has an amorphous phase after having been deposited, so that the initial phase is the amorphous phase.

The phase switching layer 151 does not have the same refractive index depending on whether it has a crystalline phase or an amorphous phase. Thus, the phase change of the phase-switched layer 151 varies its refractive index, and therefore the perception of its visual appearance for a user insofar as the interference color of the stack is dependent on the index of refraction of the phase-switched layer 151.

In other words, the phase-switched layer 151 is configured so that its refractive index has one or the other of two values following exposure to light rays. It should be noted that the light rays are generated so as to locally impact the stack of thin layers 15 from the encapsulation layer 152 so that the covering component has two different interference colors.

Advantageously, the phase switching layer 151 is made of a phase change material such as Ge2Sb2Te5 or AgInSbTe. Preferably, the phase switching layer 151 has a thickness of between 5 nm and 20 nm.

In a process for decorating the covering component 14, the light rays are applied locally to a predefined exposure zone 16 on the surface of the stack of thin layers 15, so as to generate a predetermined pattern on the trim component 14. Such a pattern therefore has an interference color different from that of the rest of the trim component and can be in the form of a logo, a text or any other graphic representation.

In other words, a portion of the phase switching layer 151 has an amorphous or crystalline phase, the rest of said layer having a different phase, and thus a different refractive index, which allows the generation of two interference colors. different.

The light rays are preferably generated by a laser beam controlled by a control unit known per se to those skilled in the art, so as to control at least the localized rise in the temperature of the phase-switched layer 151 , the exposure time and the shape of the predefined exposure zone 16 on the surface of the stack of thin layers 15.

Preferably, the laser beam emits light rays whose wavelength is in the infrared range, the invention can also be implemented with lasers whose beam emits light rays whose wavelength is in the visible range or in the ultraviolet range. The working power of the laser is relatively low, preferably around 50 mW with a pulse duration of the order of 5 ms, that is to say a pulse energy of the order of 250 μJ, in order to to carry out the phase switching of the phase-switched layer 151 without the risk of damaging it by the effects of overheating, ablation, etc.

The encapsulation layer 152 makes it possible to protect the stack of thin layers 15 and in particular the phase-switched layer 151 against in particular oxygen and humidity. It is through this encapsulation layer 152 that the phase switching layer 151 is visible to a user.

Furthermore, the encapsulation layer 152 is transparent to the wavelength of the light rays to which the phase switching layer 151 is exposed.

The encapsulation layer 152 may in particular be made of indium-tin oxide, silicon dioxide or zinc sulphide.

The thickness and the material of the encapsulation layer 152 and of the spacing layer 153 are chosen according to the desired color of the stack of thin layers 15. Indeed, the thickness and the material of the layers encapsulation 152 and spacing 153 vary their respective refractive index, and therefore, the interference color.

Preferably, the encapsulation layer 152 has a thickness of about 10 nm.

[0063] The stack of thin layers 15 advantageously has a very small thickness and consequently can be applied to the covering component 14 of the watch case 10 without modifying the design of said watch case 10 or of said component of dressing 14.

Advantageously, in another exemplary embodiment of the present invention represented in FIG. 3, the encapsulation layer 152 can be formed by the support, which is then made of a transparent material.

The visualization of the stack of thin layers 15, by a user, then takes place from the support.

The covering component 14 is in this case for example constituted by a crystal or by a dial made of a transparent material. Advantageously, the stack of thin layers 15 is thus located in the internal volume of the watchcase 10 and is not exposed to any friction.

Advantageously, in another exemplary embodiment of the present invention represented in FIG. 4, the substrate layer 150 can be formed by the support, that is to say by the covering component 14, which is then made of reflective material, for example platinum, rhodium, silver, aluminum, etc.

In the embodiments of the present invention shown in Figures 2 and 3, since the substrate layer 150 is formed by a reflective layer, the stack of thin layers 15 is likely to reflect the light to which it is exposed, and to generate an aesthetic appearance of solid, opaque interference colors.

In still other exemplary embodiments of the invention, represented respectively in FIGS. 5 and 6, the substrate 150 is not formed by a reflective layer, unlike the exemplary embodiments described previously and illustrated in the figures. 2 to 4, but is transparent or translucent. More precisely, the substrate layer 150 is formed by a transparent or translucent material, such as polyethylene terephthalate, glass, sapphire, etc.

More particularly, in the exemplary embodiment of the invention visible in Figure 5, the substrate layer 150 is formed by the support, and in the exemplary embodiment of the invention visible in Figure 6, the encapsulation layer 152 is formed by the support.

In these exemplary embodiments of the invention, the interference effect produced by the arrangement of the phase switching layer 151, of the spacing layer 153 and of the substrate layer 150, is transmissive type.

In the embodiments shown in Figures 5 and 6, the decoration generated by the stack of thin layers 15 can be observed by the user both through the encapsulation layer 152 and through the layer of substrate 150.

In these exemplary embodiments of the invention, the covering component 14 can advantageously be constituted by a crystal or a dial.

More generally, it should be noted that the modes of implementation and embodiment considered above have been described by way of non-limiting examples, and that other variants are therefore possible.

In general, the different thin layers of the stack of thin layers 15 can be deposited by a sputtering method, or by any other suitable deposition method.

Claims (11)

1. Watch case (10) characterized in that it comprises a middle part (11) to which is fixed a crystal (12) and a bottom (13) so as to form an internal volume, said watch case (10) comprising, in said internal volume, a covering component (14) on which is deposited a stack of thin layers (15) comprising a substrate layer (150), a phase-switched layer (151) in the solid state interposed between a transparent encapsulation layer (152) and a spacer layer (153) separating said phase-switched layer (151) from the substrate layer (150), the phase-switched layer (151) being configured so as to present a refractive index able to vary under the exposure of light rays so as to give the stack of thin layers (15) at least two interference colors. 2. Watch case (10) according to claim 1, wherein the phase switching layer (151) is configured to have two reversibly switchable phase states, said phase states being a crystalline phase and an amorphous phase. 3. Watch case (10) according to one of claims 1 to 2, in which the encapsulation layer (152) is transparent to the wavelength of the light rays under the exposure of which the refractive index of the phase-switched layer (151) is dimmable. 4. Watch case (10) according to one of claims 1 to 3, wherein the substrate layer (150) is formed by a reflective layer. 5. Watch case (10) according to claim 4, in which the stack of thin layers (15) is deposited on a support consisting of all or part of the covering component (14), the substrate layer (150) being deposited on said support so as to separate the spacer layer (153) from said support. 6. Watch case (10) according to claim 4, in which the stack of thin layers (15) is deposited on a support consisting of all or part of the covering component (14), the encapsulation layer (152 ) being formed by the support. 7. Watch case (10) according to one of claims 1 to 3, wherein the substrate layer (150) is made of transparent or translucent material. 8. Watch case (10) according to claim 7, in which the stack of thin layers (15) is deposited on a support consisting of all or part of the covering component (14), the substrate layer (150) or the encapsulation layer (152) being formed by the support. 9. Watch case (10) according to one of claims 1 to 8, in which the covering component (14) is a dial, a structure of a watch movement (17), a crystal, a display, a hand, an applique, a logo or an oscillating weight. 10. A method of decorating the covering component (14) of a watch case (10) according to one of claims 1 to 9, consisting in exposing the stack of thin layers (15) to light rays, on a predefined exposure area (16), so as to locally change the phase of the phase-switched layer (151) and to generate a pattern on said dressing component (14). 11. Decoration method according to claim 10, in which the light rays are generated by a laser beam controlled by a control unit, so as to control the localized rise in the temperature of the phase-switched layer (151), the exposure time and the shape of the predefined exposure zone (16).