Method of decorating an external part for a timepiece, piece of jewellery or clothing accessory, and such an external part

Abstract

To provide a method for decorating an exterior component for a watch, jewelry or clothing accessory.SOLUTION: The method comprises the following steps: a first interferential layer 110 of titanium oxide is formed over the decorative face 101 of the titanium substrate 100 by anodizing said decorative face at a voltage V1; a portion of said first interferential layer is machined to form at least one opening leading to a portion of said decorative face; and a second interferential layer 120 of titanium oxide is formed by anodizing said portion at a voltage V1 lower than said voltage V2.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to the field of watches, jewellery or clothing accessories.

[0002] More particularly, the present invention relates to a method for decorating exterior parts, which can be advantageously applied to any exterior part in the fields of watchmaking, jewellery, clothing accessories, such as leather goods, spectacles, writing instruments or portable electronic devices.

[0003] More specifically, in the field of watchmaking, an exterior part may consist of a dial, a plate, a bar, a gear train, an oscillating weight, a bezel, a middle case, a link or other part of a bracelet, or any other visible part of a watch. [Background technology]

[0004] In the fields of watchmaking, jewellery and clothing accessories, market participants are constantly looking for new decorative methods to change the appearance of their products in order to increase their appeal or to differentiate them from competitors.

[0005] For example, exterior parts are commonly colored by spraying varnishes, particularly in the field of watchmaking, but these varnishes mask decorations created by surface structuring, such as sunray brushing.

[0006] Thin film vacuum deposition methods are also used to color exterior parts. However, these deposition methods have the drawback of not uniformly coloring the exterior parts, which limits the decorative possibilities or makes their use more complicated. Furthermore, these deposition methods are relatively expensive.

[0007] The present invention addresses the need for multiple color pigmentation of exterior components without the drawbacks mentioned above. Summary of the Invention

[0008] The present invention achieves the aforementioned object and, to this end, relates to a method for decorating an exterior part for a watch, jewellery or clothing accessory, said method comprising: forming a first interference layer of titanium oxide over the entire decorative surface of the titanium substrate by anodizing said decorative surface at a voltage V1; machining a portion of the first interference layer to form at least one opening that communicates with a portion of the decorative surface; forming a second interference layer of titanium oxide by anodizing the portion at a voltage V2 lower than the voltage V1; Includes.

[0009] One of the advantages of the present invention is that it preserves the appearance of the physical features on the decorative surface of the exterior part body, in other words, any decoration created by the surface structuring on the decorative surface of the exterior part body remains visible due to the minimal thickness of the thin decorative layer.

[0010] The present invention also allows for the coloring of exterior parts without the addition of colorants.

[0011] Additionally, the present invention allows for the exterior components to be colored in a wide range of colors.

[0012] In particular embodiments, the invention may further comprise one or more of the following features, taken individually or in any technically possible combination:

[0013] In certain embodiments, the voltages V1 and V2 are comprised between 1 and 150 volts and are applied for a period of 1 to 10 minutes, or even 2 to 5 minutes.

[0014] In a particular embodiment, the first interference layer has a maximum thickness of 200 nm and the second interference layer has a minimum thickness of 1 nm.

[0015] In certain embodiments, the machining is performed to create a material removal gradient in the plane in which the decorative surface extends.

[0016] In certain embodiments, after the step of forming the second interference layer of titanium oxide, an additional step is performed of machining a portion of the first interference layer and / or a portion of the second interference layer to form at least one additional opening that opens into a portion of the decorative surface, followed by a step of forming an additional interference layer by anodizing at a voltage V3 that is lower than voltage V2.

[0017] According to another aspect, the present invention relates to an exterior part for a watch, jewelry or clothing accessory, comprising a titanium substrate having a decorative surface, a first interference layer of titanium oxide extending over a first portion of the decorative surface, and a second interference layer of titanium oxide extending over a second portion of the decorative surface, the first and second interference layers being adjacent and having different thicknesses. [Brief explanation of the drawings]

[0018] Other characteristics and advantages of the invention will become apparent from the following detailed description, given by way of non-limiting example, with reference to the following drawings, in which:

[0019] [Figure 1] 1 to 3 show diagrammatically the successive steps involved in carrying out a decoration method according to an exemplary embodiment of the present invention. [Figure 2] 1 to 3 show diagrammatically the successive steps involved in carrying out a decoration method according to an exemplary embodiment of the present invention. [Figure 3] 1 to 3 show diagrammatically the successive steps involved in carrying out a decoration method according to an exemplary embodiment of the present invention. [Figure 4] FIG. 1 is a front view of an exterior part decorated using the method shown in steps 1 to 3. [Figure 5] 5 and 6 are diagrams showing schematically additional steps according to another exemplary embodiment of the decoration method according to the invention, which are carried out after the steps shown in FIGS. 1 to 3. In FIG. [Figure 6]5 and 6 are diagrams showing schematically additional steps according to another exemplary embodiment of the decoration method according to the invention, which are carried out after the steps shown in FIGS. 1 to 3. In FIG. [Figure 7] FIG. 2 is a diagram schematically illustrating a front view of an exterior part decorated using the method shown in steps 1 to 3, 5 and 6.

[0020] Please note that for clarity, the drawings are not drawn to scale. DETAILED DESCRIPTION OF THE INVENTION

[0021] One aspect of the present invention relates to an exterior part 10 for a watch, jewelry or clothing accessory, comprising a titanium substrate 100 having a decorative surface 101. A first interference layer 110 of titanium oxide extends over a first portion of the decorative surface 101, and a second interference layer 120 of titanium oxide extends over a second portion of said decorative surface.

[0022] Advantageously, the first interference layer 110 and the second interference layer 120 are adjacent and have different thicknesses, so that the decorative surface 101 has two different interference colors.

[0023] The present invention also relates to a method for decorating such exterior components 10 to obtain the aforementioned interference colors.

[0024] Preferably, in an exemplary embodiment of the present invention, as shown in Figures 3, 4, 6 and 7, the exterior part 10 is a watch face and therefore has a disk-shaped body. Preferably, the body of the exterior part 10 is made entirely from titanium and forms the substrate 100. Alternatively, the body may have a titanium layer a few tenths of a millimeter or a few millimeters thick that forms the substrate 100.

[0025] As used herein, the term "titanium" refers to pure titanium and titanium alloys.

[0026] The method according to the invention comprises the step of forming a first interference layer 110 of titanium oxide over the entire decorative surface 101 of the substrate 100 by anodizing said decorative surface 101 at a voltage V1. This step is shown diagrammatically in Figure 1.

[0027] Anodization is carried out in a manner known per se to those skilled in the art by applying an electric current and a defined voltage in an acidic or basic electrolytic bath at a constant and controlled temperature.

[0028] The bath may be composed of sulfuric acid, phosphoric acid, or oxalic acid, or a mixture of these acids. Alternatively, the bath may be composed of sodium silicate, potassium hydroxide, sodium hydroxide, or a mixture of these alkaline solutions. The concentration of the acid(s) or basic solution(s) in the electrolytic bath may be achieved by one skilled in the art.

[0029] Next, a step of machining a portion of the first interference layer 110 is performed to form at least one opening 111 that leads to a portion of the decorative surface 101. Thus, the machining is performed to penetrate the entire thickness of the first interference layer 110, as can be seen in Figure 2. In other words, the machining can be performed to remove only the first interference layer 110, or to remove the first interference layer 110 and a portion of the substrate 100, thereby cutting out a pocket in the substrate 100.

[0030] It should be noted that in this specification the term "machining" refers to any operation that involves the removal of material.

[0031] Such machining steps can therefore be carried out by any suitable material removal technique, for example by laser machining, in particular by selective laser ablation, by mechanical machining, in particular by cutting tools or sandblasting, by chemical machining or by photolithography.

[0032] Next, as can be seen in FIG. 3, a second interference layer 120 of titanium oxide is formed on the part of the decorative surface 101 exposed by the machining process by anodizing at a voltage V2 lower than voltage V1.

[0033] Therefore, the second interference layer 120 is thinner than the first interference layer 110, and as a result, the first and second interference layers 110 and 120 are colored differently. The interference phenomenon is well known per se to those skilled in the art and will not be described here.

[0034] Advantageously, as long as voltage V2 is less than voltage V1, the thickness of first interference layer 110 does not change when second interference layer 120 is formed.

[0035] Thus, the decoration created by the combination of the first interference layer 110 and the second interference layer 120 is defined by the pattern into which the first interference layer 110 is machined. This allows for the easy creation of rich and varied decorations in at least two different colors. In an exemplary embodiment, the first interference layer 110 can be machined using a material removal gradient, as shown schematically in Figures 2 and 3, thereby producing a color gradient, as shown schematically in Figures 4 and 7.

[0036] More specifically, the material removal gradient is created in the plane of the decorative surface and is characterized by a change in the amount of material present in the first interference layer 110 on the decorative surface 101 in one or more given directions. In particular, in FIGS. 4 and 7 , the material gradient extends radially, with the material of the first interference layer 110 completely covering the decorative surface at the center of the exterior part 10 and then gradually covering less and less of the surface of the decorative surface 101 as one moves away from the center of the exterior part 10. Because the second interference layer 120 is formed on the portion of the decorative surface 101 exposed during the machining process, its distribution on the decorative surface corresponds inversely to that of the first layer 110. The junction between these two layers has a melted appearance, resulting in a gradational appearance of the colors of the first interference layer 110 and the second interference layer 120.

[0037] This type of machining can be performed using lasers, sandblasting, sunray brushing, grinding, or any other material removal technique mentioned previously in this document.

[0038] For example, the voltages V1 and V2 applied when forming the first interference layer 110 and the second interference layer 120 are comprised between 1 and 150 volts and are applied for 1 to 10 minutes, or even 2 to 5 minutes.

[0039] The voltage values ​​applied to the first interference layer 110 and the second interference layer 120 are determined according to the type of electrolytic bath and the desired color of each of these layers.

[0040] For example, the first interference layer 110 can have a maximum thickness of 200 nm, and the second interference layer 120 can have a minimum thickness of 1 nm. For example, the second interference layer 120 is 5 nm thinner than the first interference layer 110.

[0041] It should be noted that the parameters that allow the thickness of the interference layer formed by anodization to be varied are the value of the applied voltage and the composition of the electrolytic chemical bath, so that to obtain an interference layer with the desired thickness and color, it is necessary to vary at least one of these parameters.

[0042] In particular, one of these interference layers can be produced by applying a voltage of 50 volts for 3 minutes during anodization in an acidic electrolytic bath, for example a 200 g / L sulfuric acid bath. The resulting layer is approximately 80 nm thick and light blue in color.

[0043] Alternatively, one of these interference layers can be produced by applying a voltage of 40 volts for 3 minutes during anodization in an acidic electrolytic bath, e.g., a 200 g / L sulfuric acid bath. The resulting layer is approximately 60 nm thick and blue in color.

[0044] In yet another example, one of these interference layers can be produced by applying a voltage of 20 volts for 3 minutes during anodization in an acidic electrolytic bath, e.g., a 200 g / L sulfuric acid bath. The resulting layer is approximately 35 nm thick and purple in color.

[0045] In an exemplary embodiment of the invention, after the step of forming the titanium oxide second interference layer 120, the method can include the additional step of machining a portion of the first interference layer 110 and / or a portion of the second interference layer 120. This additional machining step is performed to form at least one additional opening 121 that opens into a portion of the decorative surface 101, as shown in FIG. 5. The machining can be performed to extend only through the first interference layer 110 and / or the second interference layer 120, as seen in FIG. 5, or to extend into a portion of the substrate 100, thereby hollowing out a pocket in the substrate 100. The additional machining step can be performed, for example, to create a material removal gradient in the plane in which the decorative surface 101 extends, in addition to any gradient formed during the step of machining the portion of the first interference layer 110.

[0046] As shown in Figure 6, this additional machining step is followed by a step of forming an additional interference layer 130 by anodizing at a voltage V3 lower than voltage V2. Thus, the exterior part 10 can be decorated to have three colors.

[0047] Of course, the method according to the invention may include any desired number of machining steps followed by interference layer formation steps, it being understood that the anodization voltage of one layer must be lower than the voltage applied to form the previous layer. In view of the above, it is clear that each machining step may or may not be performed so as to create a material removal gradient in the plane in which the decorative surface 101 extends.

[0048] In addition, once the interference layers have been formed, they may be protected by a transparent protective layer applied by a vacuum deposition method, such as physical or chemical vapor deposition, for example. The protective layer may alternatively be a layer of varnish (e.g., a cellulose-based varnish such as Zapon, an acrylic or epoxy varnish) with a thickness comprised between 3 and 20 μm, or a layer of lacquer with a thickness comprised between 100 and 500 μm.

[0049] More generally, it should be noted that the variant embodiments discussed above are described as non-limiting examples, and that other variants are therefore possible.

[0050] Of course, the method may include a preliminary step, in other words a preliminary step prior to the step of forming the first interference layer 110. This preliminary step consists of preparing the decorative surface 101 by conventional surface structuring methods such as Côtes de Genève, sunray brushing, sandblasting, polishing, etc.

Claims

1. A method for decorating an exterior part (10) for a watch, jewellery or clothing accessory, comprising: - forming a first interference layer (110) of titanium oxide over the entire decorative surface (101) of the titanium substrate (100) by anodizing said decorative surface (101) at a voltage V1; - machining a portion of the first interference layer (110) to form at least one opening (111) leading to a portion of the decorative surface (101), said machining being carried out so as to create a material removal gradient in a plane in which the decorative surface extends; forming a second interference layer (120) of titanium oxide by anodizing said portion at a voltage V2 lower than said voltage V1; A method comprising:

2. 2. The method of claim 1, wherein the voltages V1 and V2 are comprised between 1 and 150 volts and applied for a time period between 1 and 10 minutes, or even between 2 and 5 minutes.

3. 2. The method of claim 1, wherein the first interference layer (110) has a maximum thickness of 200 nm and the second interference layer (120) has a minimum thickness of 1 nm.

4. 2. The method according to claim 1, wherein after the step of forming the second interference layer (120) of titanium oxide, an additional step of machining a portion of the first interference layer (110) and / or a portion of the second interference layer (120) is carried out to form at least one additional opening (121) leading to a portion of the decorative surface (101), followed by a step of forming an additional interference layer (130) by anodizing at a voltage V3 lower than voltage V2.

5. An exterior part (10) for a watch, jewelry or clothing accessory, comprising a titanium substrate (100) having a decorative surface (101), a first interference layer (110) of titanium oxide extending across a first portion of the decorative surface, and a second interference layer (120) of titanium oxide extending across a second portion of the decorative surface, the first interference layer (110) and the second interference layer (120) being adjacent and having different thicknesses.

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