CN220894575U

CN220894575U - Articles with iridescent colours obtained by interference effects

Info

Publication number: CN220894575U
Application number: CN202321607460.1U
Authority: CN
Inventors: B·贝歇特; J·林泰默; J·梅尔; G·里提纳
Original assignee: Comadur SA
Current assignee: Comadur SA
Priority date: 2022-06-24
Filing date: 2023-06-21
Publication date: 2024-05-03
Anticipated expiration: 2033-06-21
Also published as: DE202023103227U1

Abstract

The utility model relates to an article with iridescent colours obtained as a result of interference effects, said article (1) comprising a substrate (2) covered by a single layer (4) or by a stack (3) of layers (4) having at least two layers (4), said single layer (4) or said stack (3) having a variable thickness giving the iridescent colours.

Description

Articles with iridescent colours obtained by interference effects

Technical Field

The present utility model relates to an article having an iridescent effect and in particular to an external component or movement assembly having an iridescent effect. The utility model also relates to a method for manufacturing said article.

Background

It is known to produce color by interference of light reflected on a multilayer structure. In the prior art, many documents are known that use interference effects to produce articles in a given color. For example, document EP 3 608 728 may be mentioned, which discloses a thermally compensated and coloured hairspring for a timepiece, comprising a core made of silicon, having on at least one face (which is intended to be visible after the core is assembled in the timepiece) an interference layer made of silicon oxide, having a thickness less than or equal to 1 μm, imparting to said face a colour due to the interference effect.

None of these known documents proposes a multi-coloured article.

Disclosure of utility model

It is therefore an object of the present utility model to propose a multi-coloured article. More particularly, the present utility model relates to an article having iridescent color due to interference effects. The adjective "iridescent" or the term "iridescent" means that the article has a reflection similar to a rainbow color.

More particularly, the utility model relates to an article with iridescent color obtained by interference effect, comprising a substrate covered by a monolayer or by a stack (EMPILEMENT DE couches) of layers having at least two layers, said monolayer or said stack having a variable thickness giving the iridescent color.

In fact, the path travelled by the light in the material should be different in order to produce an iridescence effect. This is the case, for example, in the use of prisms to split light into various colors. The optical path difference caused by the refractive index makes it possible to decompose light into blue to red. By depositing a transparent thin layer on a substrate with a stack of layers of non-constant thickness, different interference colours can be obtained depending on the position relative to the stack. To achieve this effect, the method must be controlled to reproduce these thickness variations from article to article, or vice versa, in order to create a unique component.

The utility model therefore also relates to a method for manufacturing said article. According to one variant, a variable thickness of the monolayer or stack is obtained during deposition, by using a cover or mask to mask one or more locations during deposition of each or some of the layers of the stack, or by placing the substrate on an uneven support. According to another variant, the stack of monolayers or layers obtained at the end of the deposition step has a substantially constant thickness, and the variation in thickness is achieved by subsequently structuring (structurer) the stack of monolayers or layers.

The utility model also relates to the following technical scheme:

1. A method for manufacturing the article having iridescent color comprising the steps of:

-providing a substrate, wherein,

-Depositing a layer of said monolayer or stack, said monolayer or stack having a variable thickness, wherein the maximum thickness is Y, and in one or more positions the thickness is less than or equal to 0.98 x Y, to obtain said article with iridescent color.

2. The manufacturing method according to the previous claim, characterized in that a variable thickness is obtained during deposition by using a cover or mask to mask one or more locations during deposition of each or some of the layers of the stack, or by placing the substrate on an inclined support.

3. A method for manufacturing the article having iridescent color comprising the steps of:

-providing a substrate, wherein,

Depositing a layer of said monolayer or stack having a substantially constant thickness,

-Structuring said single layer or stack of layers to obtain a stack having a variable thickness, wherein the maximum thickness is Y, and in one or more positions the thickness is less than or equal to 0.98 x Y.

4. The manufacturing method according to the previous claim, characterized in that structuring is performed by laser etching or photolithography.

5. A manufacturing method according to any one of claims 1 to 3, characterized in that the deposition of each layer of the stack is performed by PVD, CVD, sol-gel or ALD.

Other features and advantages of the present utility model will become apparent upon reading the following detailed description with reference to the accompanying drawings.

Drawings

Fig. 1 schematically shows a stack of layers according to the utility model with variable thickness to obtain an iridescent effect.

Fig. 2 shows a schematic diagram of the steps of depositing layers to form a stack.

Fig. 3 schematically shows the step of depositing a layer using a blanket or mask to alter the thickness of the deposited layer.

Fig. 4 is another variation in which the substrate is placed on an inclined support to vary the thickness of the layer.

Fig. 5 shows an iridescent bezel produced using the method according to the utility model.

Detailed Description

The present utility model relates to an article with iridescent colours obtained by interference effects. As regards the article, it may relate to a constituent element of a watch, jewelry, wristband or the like, or more generally an external part of a portable element such as a mobile phone casing. In the field of watches, the item may be an external component such as an intermediate component, a watch back, a watch bezel, a button, a wristband, a dial, a pointer, a dial indicator (index de cadran), or the like. Preferably, it relates to a transparent bezel having this iridescence effect. By way of illustration, a table frame 1 according to the utility model with iridescent colours is schematically shown in fig. 5. It may also relate to components of the movement, such as plates, a balance weight or a balance spring.

According to the utility model, the article is provided with a substrate 2 on which at least one layer 4 is deposited. The assembly of layers 4 forms a stack 3. By extension, in the following, even if only a single layer is present will be referred to as a stack. According to the utility model, the stack has a variable thickness, as illustrated in fig. 1. It will be more emphasized here that the utility model is defined in terms of the thickness of the stack rather than the thickness of each layer. In practice, it may be complicated to determine the thickness or even the average thickness or also the composition of each layer for each individual layer on the final product. This requires techniques such as Tof-SIMS, SEM with Wavelength Dispersive Spectroscopy (WDS), etc. to analyze each cross-sectional layer.

Thus, the stack has a non-constant thickness that gives the iridescence effect to the article. Non-constant refers to a variation of at least 2% relative to the maximum thickness. Thus, if Y is the maximum thickness of a layer, the thickness of the layer is considered to be non-constant if the thickness of the layer is less than or equal to 0.98 x Y in one or more locations. For example, if the maximum thickness is 10 μm, the layer is considered to have a non-constant thickness if it is less than or equal to 9.8 μm at one or more points of the stack. Typically, the stack has a maximum thickness Y between 200nm and 20 μm, between 200nm and 10 μm, between 200nm and 5 μm, between 200nm and 1.5 μm. Preferably, it has a maximum thickness Y between 500nm and 1.5. Mu.m. The stack has a variable thickness between 0 and 20 μm,10 μm, 5 μm and 1.5 μm of this maximum value over the entire surface of the substrate. In fact, it cannot be excluded that in some points the substrate has no deposited layer. Preferably, the stack has a variable thickness between 100nm and 20 μm. More preferably, it has a variable thickness between 500nm and 10 μm (or even 5 μm). Even more preferably, it has a variable thickness between 500nm and 1.5 μm.

Preferably, the number of layers within the stack is between 1 and 1000, preferably between 2 and 100, and more preferably between 20 and 50. Typically, each layer has an average thickness between 1nm and 900nm, preferably between 100nm and 500 nm. Within the stack, each layer has a variable thickness. It is also possible that some layers have a constant thickness, as long as the stack eventually has a variable thickness.

The profile of the stack may be varied. Fig. 1 shows by way of illustration a sinusoidal shape. Any shape is possible as long as the stack has a non-constant thickness. For example, it may relate to a shape having a thickness that varies in a linear manner or may also be triangular.

Each layer may be a transparent, semi-transparent (translucide) or translucent layer. It may relate to, for example, oxides, nitrides, fluorides selected from TiO₂、Ta₂O₅、SiO₂、Al₂O₃、MgF₂、AlN、Ta₂O₅、Si₃N₄、ZnS、ZnO、ZrO₂、Cr₂O₃、CeO₂、Y₂O₃、HfN、HfC、HfO₂、La₂O₃、MgO、Sb₂O₃、SiO、Se₂O₃、SnO₂ and WO ₃. It may also relate to a metal layer having a metal selected from, for example Au, cr, ti, al and Ta, or may also relate to a semiconductor such as Si.

Preferably, the stack alternates (alterner) layers having a high refractive index (i.e., greater than 2 (for a wavelength of 550 nm)) with layers having a low refractive index (i.e., less than 1.7 (for a wavelength of 550 nm)). For example, it may involve the alternation of layers of TiO ₂/SiO₂ or Ta ₂O₅/SiO₂. It is also possible to overlap a layer with a high refractive index, i.e. greater than 2, with a layer with a medium refractive index, i.e. between 1.7 and 2, and a layer with a low refractive index, i.e. less than 1.7, still for a wavelength of 550 nm. For example, it may involve an alternation of the layers of TiO ₂/Al₂O₃/SiO₂.

The substrate may be of any type, for example metal, ceramic or polymer. It may also relate to a substrate made of precious or semi-precious stone, such as sapphire. If the substrate is transparent, the various layers may be deposited directly on the substrate. Iridescence effects may be visible on the side where the various layers are deposited or through the substrate. If the substrate is opaque, as in the case of ceramics or metals, it is necessary to have a specular interface in order to produce reflection of light on the surface and to have interference colors. Typically, it involves a metal layer of Ti, cr or Ag to create the specular interface.

Deposition of the layers may be performed by various methods, including Physical Vapor Deposition (PVD), chemical Vapor Deposition (CVD), sol-gel, or Atomic Layer Deposition (ALD). The variation in thickness can be achieved during deposition, or subsequently by structuring the layer when a monolayer is present, or by structuring the deposited layer when multiple layers are present. According to a first variant involving varying the thickness during deposition, there are a number of techniques. One technique involves tilting the component in a manner that produces a more or less linear change in thickness. Thus, as illustrated in fig. 4, the substrate 2 is deposited on the inclined support 6. Another technique involves using a mask or cover 5 to block certain areas during deposition (fig. 3). The mask may be paint, adhesive, photosensitive film, or the like. It may be deposited by digital or manual printing of, for example, photolithography, stereolithography, adhesives or films (then similar to a cover). Another technique involves creating shadows of the substrate during deposition by using a mask that alters the dynamics of the material flow to the surface and thus the thickness. According to a second variant, after deposition, the monolayer or deposited layer may be structured using a variety of techniques. Among these, laser etching, photolithography may be mentioned.

The bezel with the substrate made of sapphire was tested. Alternating layers of silicon dioxide (SiO ₂) and tantalum pentoxide (Ta ₂O₅) were deposited by PVD. The number of layers is between 20 and 50, wherein the maximum thickness Y of the stack is between 800nm and 1.5 μm. The resulting bezel has a very attractive iridescent effect.

Claims

1. An article with iridescent color obtained by interference effect, characterized in that it comprises a substrate (2) covered by a single layer (4) or by a stack (3) of layers (4) with at least two layers (4), said single layer (4) or said stack (3) having a variable thickness giving said iridescent color.

2. The article according to claim 1, wherein the monolayer (4) or the stack (3) has a maximum thickness Y, and wherein in one or more positions the thickness is less than or equal to 0.98 x Y.

3. The article according to claim 2, wherein the maximum thickness Y is between 200nm and 20 μιη.

4. An article according to claim 3, characterized in that said thickness is between 0 and said maximum thickness Y within said single layer (4) or said stack (3).

5. Article according to any one of claims 1 to 4, characterized in that the number of layers (4) within the stack (3) is between 2 and 1000.

6. The article according to any one of claims 1 to 4, wherein each layer (4) can be a transparent, semi-transparent or translucent layer, with one material selected from: oxide, nitride, fluoride, metal or semiconductor.

7. The article according to any one of claims 1 to 4, wherein the stack (3) alternates layers (4) having a refractive index greater than 2 with layers (4) having a refractive index less than 1.7.

8. The article according to claim 7, wherein the stack (3) comprises an alternation of layers (4) of TiO ₂/SiO₂ or Ta ₂O₅/SiO₂.

9. Article according to any one of claims 1 to 4, characterized in that the stack (3) alternates a layer (4) having a refractive index greater than 2 with a layer (4) having a refractive index between 1.7 and 2 and a layer (4) having a refractive index less than 1.7.

10. The article according to claim 9, characterized in that the stack (3) comprises an alternation of layers (4) of TiO ₂/Al₂O₃/SiO₂.

11. Article according to any one of claims 1 to 4, characterized in that each layer (4) has an average thickness between 1nm and 900 nm.

12. Article according to any one of claims 1 to 4, characterized in that the substrate (2) is opaque and comprises a metal layer between the substrate (2) and the stack (3).

13. The article according to any one of claims 1 to 4, wherein the article relates to a timepiece external part or movement assembly.

14. The article according to claim 13, characterized in that it relates to a transparent bezel (1).

15. An article according to claim 3, wherein the maximum thickness Y is between 200nm and 1.5 μm.

16. The article according to claim 15, wherein the maximum thickness Y is between 500nm and 1.5 μm.

17. Article according to claim 5, characterized in that the number of layers (4) in the stack (3) is between 2 and 100.

18. The article according to claim 17, characterized in that the number of layers (4) within the stack (3) is between 20 and 50.

19. Article according to claim 11, characterized in that each layer (4) has an average thickness between 100nm and 500 nm.