Item with backlit plique-a-jour enamel decoration and method for manufacturing same

Abstract

To provide a method for manufacturing an article including a through-decoration forming a backlit plique-a-jour enamel.SOLUTION: A method includes the steps of: acquiring a blank 5; removing a part of the blank from an inner surface 5b of the blank to produce a decoration 2a that does not pass through to an outer surface 5a; depositing, from the inner surface, one or more layers of enamel 3 within the non-through decoration; depositing, from the inner surface, a layer of a luminescent material 4 on the enamel; depositing a protective layer 6 on the one layer of luminescent material; and machining the outer surface to expose the enamel. Moreover, the present invention relates to an article 1 including a through-decoration made of a backlit plique-a-jour enamel.SELECTED DRAWING: Figure 1e

Description

[Technical Field]

[0001] The present invention relates to a method for producing an article having a backlit plique-à-jour enamel decoration. The method according to the invention allows for mass production at reduced costs. The invention also relates to an article produced by this method. [Background technology]

[0002] Plique-à-jour is a technique of applying enamelling to a substrate that has no base at the enamel level. The absence of a base allows light to pass through the transparent or translucent enamel, resulting in a miniature stained-glass effect.

[0003] The traditional plicat-à-jour technique involves forming welded septa using a metal that remains stable during the enamel firing.During the successive firings of the deposited layers, due to their properties, metal septa, mainly made from yellow or white gold, can deform or separate from the substrate, greatly limiting the number of passes through the firing furnace and the range of designs that can be produced.

[0004] Furthermore, a substrate is required to ensure that the enamel does not flow beyond the partition walls during deposition and firing. Because the substrate is made of quartz, this operation is very difficult to perform on non-planar shapes. Traditionally, enamel is deposited manually using a brush or oiler. The layers deposited using these methods are very thin, typically requiring the deposition of dozens of layers to achieve a total thickness of less than 0.5 mm. Due to its thinness, the resulting enamel is quite brittle.

[0005] Because this technique is laborious and unreproducible, watches with plique-à-jour dials are one-offs or produced in extremely limited series at prohibitive cost. To this day, this lack of reproducibility prevents watch manufacturers from mass-producing the watches.

[0006] In addition to this production aspect, luminous effects may be desired in the decoration, especially for the bezel or dial indices. Summary of the Invention

[0007] The object of the present invention is to overcome the above-mentioned drawbacks by proposing a manufacturing method that allows for the mass production of pieces with plique-à-jour enamel decorations at low cost and with increased enamel strength, and also to give said plique-à-jour enamel decorations a luminous effect.

[0008] For this purpose, the invention relates to a method for manufacturing an article comprising at least one enamel and a through-hole filled with a luminescent material to form a so-called backlit plicajour enamel, the method comprising: obtaining a blank defined by an outer surface facing the viewer and an inner surface opposite the outer surface; removing a portion of the blank from the inner side to generate a decorative portion that does not penetrate all the way to the outer side, or alternatively obtaining the blank in a previous step so that it directly has the decorative portion that does not penetrate all the way to the outer side; depositing one or more layers of enamel from the inner surface into the non-penetrating decorative portion and firing the enamel after each layer is deposited; depositing a layer of luminescent material onto the enamel from the inner surface; depositing a protective layer on the layer of luminescent material from the inner surface; machining the outer surface, preferably by grinding, to expose the enamel, thereby producing an article with through decoration.

[0009] Preferably, the through decoration is then polished.

[0010] The method is highly reproducible and allows large scale production to be achieved at very low cost.

[0011] This method allows for the deposition of thick, multi-layer enamel, making it possible to obtain enamel with a total thickness of 0.5 mm or more using a limited number of layers, typically less than 10. This greater thickness compared to prior art enamels means that the enamel is less brittle and can be used on exterior parts such as bezels that are subject to significant stress.

[0012] Furthermore, the use of enamel rather than lacquer typically provides superior chemical and mechanical resistance compared to standard lacquered bezels. Enamel, unlike lacquer, is also one of the more noble materials in watchmaking and jewelry.

[0013] The polymerization of the luminescent material during the multiple deposition steps and the polymerization of the protective layer are carried out at very low temperatures, typically around 80°C, which does not damage the enamel. The protective layer, typically a lacquer, not only protects the luminescent material from the external environment but also reflects the emitted light towards the enamel. The outer enamel protects the luminescent decoration from mechanical wear.

[0014] The invention is also based on the ability to simultaneously grind the substrate and enamel while ensuring an optimal surface finish for both materials. Polishing the enamel also means that it does not need to be reheated in a kiln to achieve its final glossy transparency.

[0015] The transparent enamel decoration provides a depth that is not achievable today. Furthermore, the recessed position of the luminescent material makes the luminous effect perceptible even in brightly lit environments. The colors of the luminescent material and the translucent enamel can also be combined to obtain new luminous color panels. Color gradients can be deposited in the enamel, for example by spraying. [Brief explanation of the drawings]

[0016] [Figure 1a]Figures 1a to 1f show six steps of the method according to the invention. In each figure, a schematic cross-section of a portion of an article or blank and a three-dimensional view of a portion of the article or blank are shown. The three-dimensional views of Figures 1a and 1f are views from above, i.e., from the outside, of the blank or article, respectively, while Figures 1b to 1e are views from below, i.e., from the inside, of the blank. [Figure 1b] Figures 1a to 1f show the six steps of the method according to the invention. [Figure 1c] Figures 1a to 1f show the six steps of the method according to the invention. [Figure 1d] Figures 1a to 1f show the six steps of the method according to the invention. [Figure 1e] Figures 1a to 1f show the six steps of the method according to the invention. [Figure 1f] Figures 1a to 1f show the six steps of the method according to the invention. [Figures 2a-2c] Figures 2a to 2c show diagrammatically cross-sectional views of an article for additional and optional steps in a method according to the invention. [Figure 3] FIG. 3 is a three-dimensional view of an article produced by this method. DETAILED DESCRIPTION OF THE INVENTION

[0017] The present invention relates to a method for manufacturing an article having a backlit plique-à-jour enamel decoration. The article may be, for example, a watch part. In particular, it may be an external part selected from a non-exhaustive list including a middle part, a case back, a bezel, a crown, a push piece, a bracelet link, a bracelet, a tongue buckle, a clasp, a dial, and hands. It may also consist of movement parts such as an oscillating weight. The method is particularly well suited to the manufacture of articles subject to high stresses, such as exterior parts. The invention will be specifically described below with reference to a bezel.

[0018] This manufacturing method is suitable for any substrate with a melting point higher than the enamel firing temperature, which is typically between 650°C and 1100°C, depending on the enamel composition. This method is particularly suitable for substrates made of hard materials, such as ceramics, such as silicon nitride, zirconium oxide, or aluminum oxide, or sapphire or cermets. Some ceramics, particularly ZrO2, have excellent mechanical and chemical adhesion to the enamel, and the thermal expansion coefficients of the two are very similar, allowing openwork articles to retain excellent mechanical strength. These materials can withstand firing cycles up to 1000°C for high-fired enamels and are also resistant to thermal shock during rapid firing cycles.

[0019] The method is shown in six steps a) to f) for the bezel in Figures 1a to 1f. In the first step a), an article without any decoration, referred to as the blank 5, is obtained. Then, in the second step b), a blind decoration 2a is generated on the inner surface 5b of the blank 5. This blind decoration can be generated, for example, by laser ablation. Optionally, this step b) can be omitted if a blank provided with the blind decoration 2a is directly obtained in step a), which is generated, for example, by injection molding. In the third step c), enamel 3 is deposited on the decoration 2a, also from the inside of the blank 5. Although not shown in Figure 1c, during this step, the inner surface 5b is preferably in an upward position to allow the enamel to be deposited. Ideally, the deposition is performed by liquid spraying, with a view to industrial production. Alternatively, it can be quickly deposited by hand using a brush or by sprinkling powder. The blank 5 is then fired to vitrify the deposited enamel. Preferably, multiple layers of enamel are deposited, with a firing cycle after each deposition step to ensure the enamel is bubble-free. Different colored enamel layers may be deposited, and / or the color of the enamel deposited in each layer may be varied. Typically, the total thickness of the enamel layers is 0.5 mm or more, preferably 0.8 mm or more, with a maximum total thickness of 1.5 mm or more, depending on production time. In the fourth step d), once the decorative portion is at least partially filled with enamel and fired, a layer of luminescent material 4 is deposited on the enamel 3, i.e., again from the inside of the blank, preferably with the inner surface facing up. For example, the luminescent material may be Super-LumiNova®, a phosphorescent pigment incorporated into lacquer or adhesive. This material offers a wide range of luminescent colors, including blue, green, purple, white, yellow, orange, pink, etc. In a fifth step e), a protective layer 6, such as a lacquer, is deposited on the layer of luminescent material 4, again with the inner surface preferably in the upper position.A sixth machining step f) is then carried out on the upper surface 5a of the blank 5, preferably by grinding, to expose the enamel 3, resulting in a through-hole 2 backlit from the inside by the luminescent material 4. A final polishing operation is then carried out to bring the ground surface to a perfect shine and to ensure good transparency of the enamel. The resulting bezel is shown in Figure 3.

[0020] Optionally, the exterior surface may receive a finish such as a satin finish or laser texturing, as described below. The enamel may also be textured on the interior surface or within the enamel.

[0021] Optional texturing steps are shown in Figures 2a to 2c. These steps involve texturing the enamel 3, for example by laser engraving, to create structures 7. This structure may be left as is to provide a particular aesthetic effect, or it may subsequently be filled with a material, for example, luminescent material 4. In Figure 2a, the enamel 3 is textured after the machining step of the visible surface, and the luminescent material 4 is added to the structures 7. In Figure 2b, the structures 7 are created in the enamel 3. In Figure 2c, the structures 7 are created in the final layer of enamel 3 deposited underneath the blank before the layer of luminescent material 4 is deposited.

[0022] The obtained article 1 has the following characteristics: it is provided with at least one decorative through-hole 2 filled with a laminate of layers, from the outer surface to the inside, which are one enamel layer 3 obtained by depositing and firing one or more enamel layers, one layer of luminescent material 4, and a protective layer 6. The number of deposited enamel layers is typically between 2 and 15, preferably between 3 and 10, and the total thickness of the obtained enamel is typically at least 0.5 mm, preferably at least 0.8 mm, and can reach a maximum of 1.5 mm, or even exceed this thickness if the production time is long.

[0023] Optionally, with reference to the additional steps of Figures 2a to 2c, the article 1 includes one or more structures 7 on its surface or in the enamel layer 3 that can be filled with a material, in particular a luminescent material 4. These structures can be located on the visible surface, facing the inner surface opposite the visible surface, or located between the two.

Claims

1. A method for manufacturing an article (1) comprising a through-hole (2) filled with at least one enamel (3) and one luminescent material (4) to form a so-called backlit plicajour enamel, comprising: obtaining a blank (5) defined by an outer surface (5a) facing the viewer and an inner surface (5b) opposite said outer surface (5a); - removing a portion of the blank (5) from the inner side (5b) to generate a non-penetrating decorative portion (2a) on the outer side (5a), or alternatively obtaining the blank (5) in a previous step so that it directly has the non-penetrating decorative portion (2a); depositing one or more layers of enamel (3) from said inner surface (5b) into said non-piercing decorative portion (2a) and firing said enamel (3) after each layer is deposited; - depositing a layer of luminescent material (4) onto the enamel (3) from the inner surface (5b); - depositing a protective layer (6) on said layer of luminescent material (4) from said inner surface (5b); - machining said outer surface (5a), preferably by grinding, to expose said enamel (3), thereby producing said article (1) with said through-decoration (2); A method comprising:

2. 2. The method according to claim 1, further comprising, after the machining step, polishing the outer surface (5a) so as to add brightness to the through-decoration (2).

3. 2. The method according to claim 1, wherein the blank (5) is made from a material having a melting point above 650°C.

4. 2. The method according to claim 1, wherein the deposition of one or more layers of enamel (3) is carried out by liquid spraying, by using a brush or by dusting with powder.

5. 2. The method according to claim 1, wherein the number of layers of the deposited enamel (3) is between 2 and 15, preferably between 3 and 10.

6. 2. The method according to claim 1, wherein during the step of depositing one or more layers of enamel (3), layers of enamel (3) of different colors are deposited and / or the colors within the same layer are adjusted.

7. 2. The method according to claim 1, further comprising the step of texturing the enamel (3) during the deposition of the one or more layers of enamel (3) to form structures (7) in the surface of the enamel (3) at the outer side (5a) and / or in the surface of the enamel (3) at the layer of luminescent material (4).

8. 8. The method of claim 7, comprising filling the structure (7) with the luminescent material (4).

9. The article (1) comprises an outer surface (5a) intended to be directed towards the viewer and an inner surface (5b) opposite said outer surface (5a), the article (1) comprising a through-hole decorative part (2) made from backlit plicajour enamel.

10. 10. The article (1) according to claim 9, characterized in that the decorative through-hole (2) comprises, from the outer surface (5a), a layer of enamel (3), a layer of luminescent material (4) and a protective layer (6).

11. 10. An article (1) according to claim 9, wherein said layer of enamel (3) has a thickness of at least 0.5 mm, preferably at least 0.8 mm.

12. 10. The article (1) according to claim 9, wherein said article (1) is an external watch part or a part of said movement.

13. 10. The article (1) according to claim 9, wherein said article (1) is an external watch part.

14. 10. The article (1) according to claim 9, wherein the article (1) is made from ceramic, sapphire or cermet.

15. 15. The article (1) according to claim 14, wherein said article (1) is made from zirconium oxide.

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