HK1244069B - Method for fabrication of a metal-based component with at least one optical illusion pattern - Google Patents

Description

Method for manufacturing a metal-based component having at least one optical illusion pattern

Technical Field

The present invention relates to a method for manufacturing a metal-based component having a flat surface, the flat surface including at least one optical illusion pattern, more particularly, including at least one pattern that makes the flat surface appear uneven.

Background Art

It is known to form external parts with faceted and/or beveled upper surfaces in order to improve the aesthetics of a timepiece. Patent EP1557729 discloses a method for producing faceted parts without requiring a finishing step, and in particular discloses the great difficulties in implementing the method.

Summary of the Invention

The object of the present invention is to overcome all or some of the above-mentioned drawbacks by proposing a manufacturing method requiring neither faceting nor finishing to obtain a simple metal-based part providing the illusion of being faceted and/or beveled.

To this end, the present invention relates to a method for producing at least one metal-based component having at least one optical illusion pattern, comprising the following steps:

a) forming a substrate having a flat upper surface that is electrically conductive and comprising negative ribs of the at least one optical illusion pattern of the at least one component to be manufactured;

b) forming a mold on the substrate, the mold comprising at least one cavity, wherein a bottom of the at least one cavity is formed by the upper surface of the substrate;

c) filling the at least one mold cavity by electrodeposition or electroplating to form the at least one metal-based component having a flat surface, the flat surface including at least one optical illusion pattern that makes the flat surface appear uneven;

d) releasing the substrate and the at least one component formed thereby from the mold.

It will thus be appreciated that the manufacturing method allows components to be formed with flat surfaces as a result of the flatness of the substrate, without the need for subsequent faceting or more generally subsequent finishing.

Furthermore, the manufacturing method provides for extremely high dimensional accuracy and extremely high reproducibility of one-piece metal-based components of the same type or of a plurality of different one-piece metal-based components on the same substrate.

Finally, advantageously according to the invention, the extreme precision and reproducibility of the manufacturing method make it possible to obtain very simple parts provided with at least one very fine and easily reproducible pattern, said pattern making a flat surface appear uneven even after machining, for example by beveling or chamfering.

According to other advantageous variants of the invention:

- according to a first embodiment, the ribs form at least two sets of parallel segments, a first set of parallel segments joining a second set of parallel segments at an angle of 10° to 170°, so that the at least one component gives the illusion that the flat surface comprises two inclined surfaces forming an edge;

- According to a second embodiment, said ribs form at least one set of curved segments, so that said at least one component gives the illusion that said flat surface is domed;

- According to a third embodiment, the convex ribs form at least one group of recesses arranged symmetrically to each other, and the at least one group of recesses is formed adjacent to a portion of the upper surface of the substrate having no negative convex ribs, so that the at least one component gives the illusion that the flat surface includes two inclined surfaces forming an edge; preferably, the at least one group of recesses is arranged symmetrically to each other and is formed adjacent to the portion of the upper surface of the substrate having no negative convex ribs.

- According to a fourth embodiment, the ribs are arranged on the periphery of the at least one mold cavity and form at least two groups of parallel segments, the parallel segments of a first group being perpendicular to the parallel segments of a second group and joining at an angle so that the at least one component gives the illusion that the flat surface is beveled;

- Regardless of the embodiment, the ribs may have a height between 2 and 100 microns;

- the method further comprises, between step c) and step d), a step e) of selectively machining a portion of said at least one metal-based component to form said at least one component with fastening means;

- making the upper surface of the substrate conductive by doping the silicon substrate and/or by depositing a conductive layer on the silicon substrate,

- the substrate has a thickness of 0.3 to 1 mm;

Step b) comprises: stage f): depositing a layer of photosensitive resin on the conductive upper surface of the substrate, step g): selectively illuminating a portion of the photosensitive resin, and step h): shaping the photosensitive resin to form the at least one cavity of the mold;

- said at least one component is formed from a nickel or nickel-phosphorus substrate;

- Multiple components are formed on the same substrate;

- the at least one component forms all or part of a dial, window decoration, flange, bezel, push-pin, crown, case back, hands, bracelet or strap, links, clasp, decoration, automatic weight or appliqué.

The invention also relates to an exterior part of a timepiece comprising a metal base component obtained by a method according to any of the previous variants, wherein said component has a substantially flat surface having at least one optical illusion pattern making said flat surface appear uneven.

BRIEF DESCRIPTION OF THE DRAWINGS

Other characteristics and advantages will become apparent from the following description, given in a non-limiting manner with reference to the accompanying drawings, in which:

- Figures 1 to 5 schematically illustrate the steps of the method according to the invention;

- Figures 6 to 9 show examples of pointers obtained according to the invention;

- Figures 10 to 15 show examples of hour markings obtained according to the invention;

- Figure 16 shows an example of a window decoration obtained according to the invention.

DETAILED DESCRIPTION

The present invention relates to a method for manufacturing a one-piece, simple-shaped, metal-based component that provides the illusion of faceting and/or beveling, intended to form all or part of the exterior of a timepiece. By way of non-limiting example, the component may form all or part of a dial, a window decoration, a flange, a bezel, a push-pin, a crown, a caseback, a commutator, a hand, a bracelet or strap, a link, a clasp, a decoration, or an appliqué.

Naturally, such a component is not limited to the field of horology. As a non-limiting example, such a component could instead form all or part of a jewelry piece.

The method is used to manufacture at least one metal-based component. The term "metal-based" refers to the presence of one or more metals in the composition of the component. Thus, as a non-limiting example, the component may be formed from a nickel or nickel-phosphorus substrate.

Advantageously, according to the invention, each metal-based component obtained by the method comprises at least one optical illusion pattern. More specifically, advantageously, each component comprises a substantially flat surface having at least one optical illusion pattern that makes the flat surface appear uneven, which allows obtaining simple components that, for example, give the illusion of being faceted and/or beveled.

For the sake of simplicity, the figures shown represent the production of only one component on a substrate. Advantageously, however, according to the invention, the method can also form a plurality of identical or different components on the same substrate.

As shown in FIG1 , the method according to the present invention comprises a first step a) of forming a substrate 1 having a flat upper surface 3 that is electrically conductive and includes negative ribs 5 of the at least one optical illusion pattern of the component to be manufactured. The general shape of the at least one optical illusion pattern will be further explained below. For a better understanding, in FIG1 , the ribs 5 are schematically represented by three studs protruding from the upper surface 3 of the substrate 1.

There are various substrates 1. Preferably, the material of the substrate 1 is selected based on its ability to be made flat and its low roughness, ie, its natural characteristic of having a smooth surface. As an example, a silicon-based substrate 1 has these advantages.

In the case where substrate 1 is made of silicon, step a) may thus include a first stage of covering substrate 1 with a mask having openings that leave the upper portion of substrate 1 uncovered. In a second stage, etching may be performed in the mask openings. This etching may be wet or dry. Finally, in a third stage, shown in FIG1 , the mask is removed, leaving only the ribs 5 formed on the upper surface 3 of substrate 1.

In the case where the substrate 1 is made of silicon, the upper surface 3 of the substrate 1 can be made conductive by doping the silicon, i.e. by using a substrate 1 that is already doped before etching or by doping the substrate 1 subsequently, and/or by depositing a conductive layer.

Furthermore, the substrate 1 may have a thickness of 0.3 to 1 mm, and the ribs 5 may extend from the upper surface 3 of the substrate 1 to a height of 2 to 100 micrometers.

As shown in FIG2 , the method continues with a second step b) for forming a mold 7 on the substrate 1. It will be understood that the mold 7 comprises at least one cavity 6 (i.e., depending on the shape of the desired component, the mold 7 comprises one or more cavities), the bottom of said at least one cavity being formed by the upper surface 3 of the substrate 1.

Step b) preferably comprises three stages f) to h). Step b) comprises a first stage f) for depositing a layer of photosensitive resin on the conductive upper surface 3 of substrate 1. This stage f) can be carried out by spin coating or spray coating. The second stage g) is for selectively illuminating a portion of the photosensitive resin. It is clear that, depending on the nature of the photosensitive resin, i.e., whether it is positive or negative, the illumination will be concentrated on the at least one cavity 6 to be formed later, or on a portion other than the at least one cavity 6 to be formed later.

Finally, step b) ends with a third stage h) for setting the selectively illuminated photosensitive resin, that is, for hardening the remaining photosensitive resin around or between the at least one cavity 6, so as to form the mold 7. This third stage h) is generally achieved by a heat treatment to harden the resin and thus set the shape to form the at least one cavity 6.

As shown in FIG3 , the method continues with a third step c) of filling the at least one cavity 6 of the mold 7 by means of an electro-deposition or electroplating technique to form a blank or metal-based part having a flat surface including the at least one optical illusion pattern 14 that makes the surface appear uneven. According to the invention, the metal-based part has the same relief/raised pattern when viewed in projection. However, during the construction of the substrate 1, in step c), the ribs 5 will form recesses 15 on one side of the blank or metal-based part. Furthermore, as explained below, an optional step e) may be performed after step c).

Advantageously according to the invention, as a result of the very precise photolithographic technique of step b), the method makes it possible to produce a metal base part 9 with highly precise external and possibly internal dimensions capable of meeting the extremely high tolerances required for parts in the horology sector. "Internal dimensions" means that, depending on the configuration of the resin portion 7 inserted into the at least one cavity 6, openings and/or holes can be formed directly in the metal base part in step c).

As explained above, the electrodeposition or electroplating filling of each cavity 6 in step c) can be carried out, for example, using an alloy formed of nickel and phosphorus (NiP), and in particular an alloy of this type having a phosphorus proportion approximately equal to 12% (NiP12).

Finally, the method ends with a fourth and final step d) for releasing the component thus formed from the substrate 1 and the mold 7. Thus, in the example described above in which the substrate 1 is made of silicon, step d) may comprise selective etching of the silicon and selective etching of the material of the mold 7. Silicon etching may be achieved, for example, by chemical etching using a bath containing potassium hydroxide (abbreviated to KOH).

According to a variant of the invention shown in FIGS. 4 and 5 , the method further comprises, between steps c) and d), an optional step e) of selectively machining a portion of the metal-based component in order to form a component 11 having at least one fastening device 16 .

As described above, the thickness of the block 9 having the same relief pattern is then modified to form at least one fastening means 16. Component 11 is thus obtained without the need to form multiple functional layers arranged one above the other or to finish the surface of the component comprising the at least one optical illusion pattern 14.

Due to the precise positioning of each block 9 on the substrate 1, in step e), each block 9 can be processed with precise dimensions using a programmable automated machine while the block is still on the substrate 1. It is worth noting that although step e) is used to process one or more blocks 9, it is also possible to process a portion of the resin 7 due to stress caused by the size of the tool used or the volume to be removed, as shown by the visible clear space in Figure 4. Of course, this step e) can also be used to form other functional layers and/or layer molds 7 and blocks 9 by polishing.

It will thus be understood that, in addition to the flat surface 13 and the recesses 15 forming the at least one optical illusion pattern 14, the component 11 may comprise at least one fastening means 16 for attaching the metal base component 11. The fastening means 16 may thus be in the form of a foot or a tube.

Figures 6 to 16 show examples of components obtained by this method, in order to better illustrate the optical illusion pattern according to the invention. As non-limiting examples, four embodiments of the optical illusion pattern are described.

According to a first embodiment, the substrate 1 comprises ribs for obtaining the examples of Figures 6, 7, 10 and 12. The optical illusion patterns 114, 214, 514 and 714 of Figures 6, 7, 10 and 12 thus form at least two groups 118, 120, 218, 220, 518, 520, 718, 720 of parallel segments 119, 121, 219, 221, 519, 521, 719, 721. Preferably, according to a first embodiment, the first group 118, 218, 518, 718 of parallel sections 119, 219, 519, 719 is joined to the second group 120, 220, 520, 720 of parallel sections 121, 221, 521, 721 at an angle of 10 to 170°, so that the component 111, 211, 511, 711 presents the illusion that the visible surface has two inclined surfaces forming an edge when the visible surface is flat.

According to a second embodiment, substrate 1 includes ribs for obtaining the examples of Figures 8, 13, and 15. The optical illusion patterns 314, 814, and 1114 of Figures 8, 13, and 15 thus form at least one group 318, 320, 818, 820, 1118 of curved segments 319, 321, 819, 821, 1119, which gives the illusion of a dome-shaped visible surface when the visible surface is flat. According to a variation of the second embodiment seen in Figures 8 and 13, a first group 318, 818 of curved segments 319, 819 joins a second group 320, 820 of curved segments 321, 821 at an angle of 10 to 170°, which gives the illusion that the visible surface of the component has two dome-shaped surfaces connected to form a groove when the visible surface is flat.

According to a third embodiment, substrate 1 includes raised ribs in the form of pillars for obtaining the examples of Figures 9 and 11. The optical illusion patterns 414 and 614 of Figures 9 and 11 thus form at least one group 418, 618 of recesses 419, 619 arranged symmetrically with one another. Preferably, according to the third embodiment, the at least one group 418, 618 of recesses is formed adjacent to a portion 432, 632 of the surface of the component 411, 611 that does not have the optical illusion pattern, so that when the visible surface of the component is flat, it gives the illusion that the visible surface has two inclined surfaces forming an edge. Preferably, the at least one group 418, 618 of recesses 419, 619 is arranged symmetrically with the adjacent portion 432, 632 of the surface of the component 411, 611 that does not have the optical illusion pattern.

9 and 11 , the recesses 419, 619 have a circular cross-section and are spaced a fixed distance from one another. Of course, the geometry and arrangement of the recesses 419, 619 may vary depending on the desired effect without departing from the scope of the present invention.

According to a fourth embodiment, the substrate 1 includes ribs arranged on the periphery of the mold cavity for obtaining the examples of Figures 14 and 16. The optical illusion patterns 914 and 1014 of Figures 14 and 16 thus form at least two groups 918, 920, 922, 1018, 1020, 1022, 1024 of parallel segments 919, 921, 923, 1019, 1021, 1023, 1025, wherein the parallel segments 919, 923, 1019, 1023 of the first group 918, 922, 1018, 1022 are perpendicular to the parallel segments 921, 1021, 1025 of the second group 920, 1020, 1024 and are joined at 90 degrees, thereby giving the component the illusion of a visible surface surrounded by a portion 932, 1032 of the surface of the component 911, 1011 without the optical illusion pattern.

Of course, the invention is not limited to the examples shown, but encompasses various variants and modifications that will occur to a person skilled in the art. In particular, the components 1, 111, 211, 311, 411, 511, 611, 711, 811, 911, 1011, 1111 may undergo a final hardening step, as disclosed, for example, in EP 3009896, which is incorporated herein by reference.

It is also conceivable that, alternatively, the ribs 5 are formed by photolithography of a photosensitive resin on the flat upper surface of the substrate.

In a particular alternative, the substrate 1 may also be selected from those presented in Figures 1 to 4 to form ribs 5 having different geometries. Thus, as a non-limiting example, the substrate 1 may be made of single-crystal silicon with a (100) crystal orientation and may be subjected to potassium hydroxide (KOH) wet etching to form etched elements whose sides are inclined rather than vertical as shown in Figures 1 to 4.

Finally, the optical illusion patterns are not limited to those described above. Therefore, other embodiments are possible without departing from the scope of the present invention. Furthermore, the four embodiments presented above can be combined with one another, i.e., multiple different patterns can appear on the same component.

Claims (13)

1. A method for manufacturing at least one metal-based component (11, 111, 211, 311, 414, 514, 614, 714, 814, 914, 1014, 1114) having at least one optical illusion pattern (14, 114, 214, 314, 411, 511, 611, 711, 811, 911, 1011, 1111) is characterized in that the manufacturing method comprises the following steps: a) Forming a substrate (1) having a flat upper surface (3) that is conductive and includes a negative rib (5) of the at least one optical illusion pattern of the at least one metal base component to be manufactured; b) A mold (7) is formed on the substrate (1), the mold (7) including at least one cavity (6), the bottom of the at least one cavity being formed by the upper surface (3) of the substrate (1); c) The at least one cavity (6) of the mold (7) is filled by electrodeposition on the substrate having negative ribs to form the at least one metal base component having a flat surface, the flat surface including the at least one optical illusion pattern that makes the flat surface appear uneven. d) Selectively process one surface of the at least one metal-based component to include a single fastening protrusion extending from the remainder of the one surface, the one surface being the surface of the metal-based component opposite the surface including the optical illusion pattern; e) Release the at least one metal base component (11, 111, 211, 311, 411, 511, 611, 711, 811, 911, 1011, 1111) thus formed from the substrate (1) and the mold (7), wherein the rib (5) forms at least two sets of parallel segments, the first set of parallel segments engaging the second set of parallel segments at an angle of 10° to 170°, such that the at least one metal base component presents the illusion that the flat surface includes two inclined surfaces forming the edge. 2. The manufacturing method according to claim 1, wherein the rib (5) forms at least one set of curved segments, such that the at least one metal base component presents the illusion that the flat surface is dome-shaped. 3. The manufacturing method according to claim 1, characterized in that the ribs (5) form at least one set of recesses arranged symmetrically to each other, the at least one set of recesses being formed adjacent to the portion of the upper surface of the substrate that does not have negative ribs, such that the at least one metal base component presents the illusion that the flat surface includes two inclined surfaces forming the edges. 4. The manufacturing method according to claim 1, characterized in that the rib (5) is arranged on the outer periphery of the at least one mold cavity and forms at least two sets of parallel sections, the first set of parallel sections being perpendicular to the second set of parallel sections and engaging at an angle, such that the at least one metal base component presents the illusion that the flat surface has been beveled. 5. The manufacturing method according to claim 1, wherein the height of the rib (5) is between 2 and 100 micrometers. 6. The manufacturing method according to claim 1, characterized in that the upper surface (3) of the substrate (1) is made conductive by doping the silicon substrate and/or by depositing a conductive layer on the silicon substrate. 7. The manufacturing method according to claim 1, wherein the substrate (1) has a thickness between 0.3 and 1 mm. 8. The manufacturing method according to claim 1, characterized in that step b) comprises the following stages: f) Deposit a layer of photosensitive resin on the conductive upper surface (3) of the substrate (1); g) Selectively illuminate a portion of the photosensitive resin; h) The photosensitive resin is shaped to form the at least one cavity (6) of the mold (7). 9. The manufacturing method according to claim 1, wherein the at least one metal base component (11, 111, 211, 311, 411, 511, 611, 711, 811, 911, 1011, 1111) is formed of a nickel or nickel-phosphorus substrate. 10. The manufacturing method according to claim 1, characterized in that a plurality of metal base components are formed on the same substrate. 11. The manufacturing method according to claim 1, characterized in that the at least one metal base component (11, 111, 211, 311, 411, 511, 611, 711, 811, 911, 1011, 1111) forms all or part of a dial, flange, bezel, push pin, crown, case back, hands, bracelet, links, clasp, decoration, or automatic hammer. 12. The manufacturing method according to claim 11, wherein the decoration includes window decoration or inlay. 13. The manufacturing method according to claim 11, wherein the at least one metal base component (11, 111, 211, 311, 411, 511, 611, 711, 811, 911, 1011, 1111) forms all or part of the watch strap.