ITEM WITH A BACKLIT PLIQUE-À-JOUR ENAMEL DECORATION AND METHOD FOR MANUFACTURING SAME

Abstract

A method for manufacturing an item (1) comprising a through-decoration (2) forming a so-called backlit plique--jour enamel, the method including obtaining a blank (5); removing part of the blank (5) from the inner face (5b) of the blank (5) to produce a decoration (2a) that does not pass through to the outer face (5a); depositing, from the inner face (5b), one or more layers of enamel (3) within the non-through decoration (2a); depositing, from the inner face (5b), a layer of luminescent material (4) on the enamel (3); depositing a protective layer (6) on the layer of luminescent material (4); and machining the outer face (5a) to reveal the enamel. Also, the related item.

Claims

1. A method for manufacturing an item (1) comprising a through-decoration (2) filled with at least one enamel (3) and a luminescent material (4) to form a backlit plique--jour enamel, the method comprising the steps of: obtaining a blank (5) defined with an outer face (5a), which is the face intended to face an observer, and with an inner face (5b), which is an opposite face to the outer face (5a); removing part of the blank (5) from the inner face (5b) to produce a decoration (2a) that does not pass through to the outer face (5a) or, alternatively, in the previous step, obtaining said blank (5) directly with the non-through decoration (2a); depositing, from the inner face (5b), one or more layers of enamel (3) within the non-through decoration (2a) and firing the enamel (3) after each layer has been deposited; depositing, from the inner face (5b), a layer of luminescent material (4) on the enamel (3); depositing, from the inner face (5b), a protective layer (6) on the layer of luminescent material (4); and machining, preferably by grinding, the outer face (5a) to reveal the enamel (3) and thus produce the item (1) with the through-decoration (2).

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

3. The method according to claim 1, wherein said blank (5) is made of a material with a melting point greater than or equal to 650 C.

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

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

6. 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 colours are deposited and/or the colour within the same layer is modulated.

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

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

9. An Item (1) comprising an outer face (5a) intended to face an observer and an inner face (5b) opposite to the outer face (5a), said item (1) comprising a through-decoration (2) made of backlit plique--jour enamel.

10. The item (1) according to claim 9, wherein the through-decoration (2) comprises, from the outer face (5a), a layer of enamel (3), a layer of luminescent material (4) and a protective layer (6).

11. The item (1) according to claim 9, wherein the layer of enamel (3) has a thickness greater than or equal to 0.5 mm, preferably greater than or equal to 0.8 mm.

12. The item (1) according to claim 9, said item (1) being an external timepiece component or component of the movement.

13. The item (1) according to claim 9, said item (1) being an external timepiece component.

14. The item (1) according to claim 9, said item (1) being made of a ceramic, a sapphire or a cermet.

15. The item (1) according to claim 14, said item (1) being made of zirconium oxide.

Description

BRIEF DESCRIPTION OF THE FIGURES

[0023] FIGS. 1a to 1f show the 6 steps of the method according to the invention. In each figure, a diagrammatic cross-sectional view of part of the item or blank and a three-dimensional view of part of the item or blank are shown. The three-dimensional views in FIGS. 1a and 1f are views from above the blank or item respectively, i.e. from the outer face, whereas views 1b to 1e are views from below the blank, i.e. from the inner face.

[0024] FIGS. 2a to 2c diagrammatically show cross-sectional views of the item for the additional and optional steps in the method according to the invention.

[0025] FIG. 3 is a three-dimensional view of the item produced by the method.

DETAILED DESCRIPTION OF THE INVENTION

[0026] The invention relates to a method for manufacturing an item with a backlit plique--jour enamel decoration. The item can, for example, be a timepiece component. More specifically, it can be an external component chosen from the non-exhaustive list that includes a middle, a back, a bezel, a crown, a push-piece, a bracelet link, a bracelet, a tongue buckle, a clasp, a dial and a hand. It may also consist of a component of the movement such as an oscillating weight. The method is particularly well suited to the manufacture of items subject to high stresses, such as an external component. Hereafter, the invention will be more specifically described for a bezel.

[0027] The manufacturing method is suitable for any substrate with a melting point higher than that of the enamel firing temperature, which is typically between 650 C. and 1100 C. depending on the composition of the enamel. The method is particularly well suited to a substrate made of a hard material such as ceramic, for example silicon nitride, zirconium oxide or aluminium oxide, or such as a sapphire or like a cermet. Some ceramics, particularly ZrO.sub.2, have excellent mechanical-chemical adhesion with enamel, and their coefficients of expansion are very close, which causes the openwork item to retain excellent mechanical strength. These materials withstand firing cycles of up to 1000 C. for high-fire enamels, for example, and resist thermal shock for rapid firing cycles.

[0028] The method is illustrated in FIGS. 1a to 1f in 6 steps from a) to f) for a bezel. In a first step a), the item without any decoration, which will be referred to as a blank 5, is obtained. Then, in a second step b), a non-through decoration 2a is produced from the inner face 5b of the blank 5. The non-through decoration can, for example, be produced by laser ablation. Optionally, this step b) can be omitted if a blank provided with the non-through decoration 2a is directly obtained in step a), this blank being produced by injection moulding for example. In a third step c), the enamel 3 is deposited within the decoration 2a, again from the inside of the blank 5. Although not illustrated in FIG. 1c, during this step, the inner face 5b is preferably placed in the upper position to allow the enamel to be deposited. Ideally, the deposit is carried out by liquid spraying with a view to industrial production. Alternatively, it can be deposited quickly by hand using a brush or by sprinkling a powder. The blank 5 is then fired to vitrify the deposited enamel. Preferably, a plurality of layers of enamel are deposited with, after each deposition step, a firing cycle to ensure that the enamel is bubble-free. Enamel layers of different colours can be deposited and/or the colour of the enamel deposited for each layer can be varied. Typically, the total thickness of the enamel layers is greater than or equal to 0.5 mm, preferably greater than or equal to 0.8 mm, with a maximum total thickness of 1.5 mm or more depending on production times. In a fourth step d), once the decoration has been 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, again with the inner face preferably in the upper position. For example, the luminescent material can be Super-LumiNova, which is a phosphorescent pigment charged in a lacquer or an adhesive. This material offers a wide range of emission colours, including blue, green, purple, white, yellow, orange and 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 face preferably in the upper position. A sixth machining step f) is then carried out, preferably by grinding, on the upper face 5a of the blank 5 to reveal the enamel 3, thus obtaining the through-decoration 2 backlit from the inside by the luminescent material 4. A final polishing operation can then be carried out to make the ground surface perfectly shiny and guarantee good transparency of the enamel. The resulting bezel is shown in FIG. 3.

[0029] Optionally, the outer face can be subjected to finishing treatments such as satin-finishing or laser texturing as described below. The enamel can also be textured on the inner face or within the enamel.

[0030] The optional texturing steps are illustrated in FIGS. 2a to 2c. These steps involve texturing the enamel 3, for example by laser engraving, to produce a structure 7. This structure can be maintained as such to give a particular aesthetic effect or can then be filled with material, for example luminescent material 4. In FIG. 2a, the enamel 3 is textured after the machining step on the visible face and luminescent material 4 is added to the structure 7. In FIG. 2b, the structure 7 is produced within the enamel 3. In FIG. 2c, the structure 7 is produced on the last layer of enamel 3 deposited under the blank before the layer of luminescent material 4 is deposited.

[0031] The item 1 obtained has the following features. It is provided with at least one through-decoration 2 filled with a stack of layers which are, from the outer face inwards: an enamel layer 3 resulting from the deposition and firing of one or more enamel layers, a layer of luminescent material 4 and a protective layer 6. The number of enamel layers deposited is typically between 2 and 15, preferably between 3 and 10, and the total thickness of the enamel obtained is typically greater than or equal to 0.5 mm, preferably greater than or equal to 0.8 mm with a maximum value that can reach 1.5 mm, or even more for longer production times.

[0032] Optionally, with reference to the additional steps in FIGS. 2a to 2c, the item 1 comprises, on its surface or in the enamel layer 3, one or more structures 7 which can be filled with a material, and more specifically with a luminescent material 4. These structures can be arranged at the visible surface, facing the inner surface opposite the visible surface, or between the two.