DE202023103227U1 - Item iridescent in rainbow colors - Google Patents

Abstract

Object with an iridescent color obtained by interference effect, said object comprising a substrate (2) covered with a single layer (4) or a stack (3) of layers (4) with at least two layers (4), the single layer (4) or the stack (3) has a variable thickness that gives this iridescent color.

Description

Technical field of the invention

The present invention relates to an article and in particular to a watch component for the fittings or movement which has an iridescent effect.

Technical background

The generation of colors by interference of reflected light on multi-layer structures is known. Several documents are known in the prior art that use the interference effect to produce an object of a specific color. For example, you can use the document EP 3 608 728 cite which discloses a thermo-compensated and colored hairspring for a watch comprising a silicon core with an interference layer of silicon oxide on at least one side intended to be visible within the watch after assembly, the interference layer having a thickness of less than or is equal to 1 µm and imparts a color to said side by the interference effect.

None of these known documents suggest a multicolored article.

Summary of the Invention

The present invention is therefore based on the object of creating a multicolored object. More specifically, it refers to an object that has an iridescent color due to interference effects. The adjective iridescent or the noun iridescent means that the object has a reflection reminiscent of the colors of the rainbow.

In particular, the present invention relates to an article having an iridescent color obtained by the interference effect, the article comprising a substrate covered with a single layer or a stack of layers having at least two layers, the single layer or the stacking has a variable thickness that gives this iridescent color.

In order to create an iridescence effect, the path that the light travels in the material must be different. This is the case, for example, when using a prism to separate light into different colors. Due to the different path due to the refractive index, the light is broken down into blue to red. By depositing transparent thin films on the substrate with a stack of layers of non-constant thickness, a different interference color can be obtained depending on the position in which one faces the stack. In order to achieve this effect, these differences in thickness must be able to be reproduced from one item to another, or if not, to produce unique pieces.

According to one embodiment, the variable thickness of the individual layer or stack is achieved by means of a deposition using a cover or mask to hide one or more locations in the deposition of each layer or specific layers of the stack, or by laying the substrate on an uneven surface. According to another embodiment, the single layer or stack of layers obtained after the deposition step has a substantially constant thickness and the change in thickness is achieved by later patterning of the single layer or stack of layers.

Further features and advantages of the invention will become apparent from the following detailed description with reference to the accompanying drawings.

character list

• 1 shows schematically stacked layers with different thicknesses to achieve the iridescent effect according to the invention,
• 2 shows a schematic view of the laying down of layers to form a stack,
• 3 shows schematically the formation of the layers using a cover or a mask to vary the thickness of the deposited layer,
• 4 Figure 13 is another embodiment with the positioning of the substrate on an inclined support to vary the thickness of the layer,
• 5 shows a rainbow-colored bezel according to the invention.

Detailed description of the invention

The present invention relates to an object iridescent in rainbow colors, ie with an iridescent color obtained by the interference effect. In terms of the object, it can be a component of watches, jewellery, bracelets, etc., or more generally an external part of a wearable item such as a mobile phone case. In the In the field of watchmaking, this object can be a piece of equipment such as a case-back, a back, a bezel, a push-piece, a bracelet link, a dial, a hand, a dial index, etc. It is preferably a transparent bezel that shows this iridescent effect. By way of illustration, a bezel 1 with an iridescent color according to the invention is shown in 5 shown schematically. It can also be a component of the clockwork, e.g. B. a circuit board, a flywheel or a spiral spring.

According to the invention, the subject is provided with a substrate 2 on which at least one layer 4 is applied. All of the layers 4 form a stack or a stack 3. In the broader sense, a stack is also referred to below when there is only a single layer. According to the invention, this stacking has a different thickness, as in 1 is shown schematically. Here the invention is defined in terms of the thickness of the stack rather than the thickness of the individual layers. In fact, in the final product, it could be difficult to determine the thickness or even the average thickness for each individual layer, or even the composition of each layer. This requires techniques such as Tof-SIMS (Time-of-Flight-SIMS), SEM with wavelength dispersive X-ray spectroscopy or Wavelength Dispersive spectroscopy (WDS) to analyze each layer in cross-section.

Thus the stack has a non-constant thickness which gives the object this iridescent effect. Not constant means a deviation of at least 2% from the maximum thickness. Thus, if Y is the maximum thickness of the layer, the thickness of the layer is not considered constant if that thickness is less than or equal to 0.98*Y at one or more locations. For example, if the maximum thickness is 10 µm, the layer is not considered to be of constant thickness if it is less than or equal to 9.8 µm at one or more points in the stack. Typically, the stack has a maximum thickness Y between 200 nm and 20 μm, between 200 nm and 10 μm, between 200 nm and 5 μm, between 200 nm and 1.5 μm. It preferably has a maximum thickness Y between 500 nm and 1.5 μm. Over the entire surface of the substrate, the stacking has a variable thickness between 0 and this maximum value of 20 μm, 10 μm, 5 μm and 1.5 μm. This is because it cannot be ruled out that the substrate does not have any deposited layers at certain points. Preferably, the stack has a variable thickness between 100 nm and 20 μm. Even more preferably, it has a variable thickness between 500 nm and 10 μm or even 5 μm. Even more preferably, it has a thickness variable between 500 nm 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 1 nm and 900 nm, preferably between 100 nm and 500 nm of stacking, each layer has a variable thickness. It is also conceivable that some layers have a constant thickness, as long as the stack up has a variable thickness at the end.

The stacking profile can vary. In 1 it is shown with a sinusoidal shape for illustration. Any shape is conceivable as long as the thickness of the stack is not constant. For example, it can be a shape with a linearly varying thickness or a triangular shape.

Each layer can be a transparent, translucent or semi-transparent layer. For example, they can be oxides, nitrides, fluorides selected from TiO ₂ , Ta ₂ O ₅ , SiO ₂ , Al ₂ O ₃ , MgF ₂ , AlN, Ta ₂ O ₅ , Si ₃ N ₄ , ZnS, ZnO , ZrO ₂ , Cr ₂ O ₃ , CeO ₂ , Y ₂ O ₃ , HfN, HfC, HfO ₂ , La ₂ O ₃ , MgO, Sb ₂ O ₃ , SiO, Se ₂ O ₃ , SnO ₂ and WO ₃ . It could also be metal layers with a metal selected z. B. from Au, Cr, Ti, Al and Ta, or a semiconductor such as Si.

Preferably, the stacking alternates a layer with a high index of refraction, ie greater than 2 (at a wavelength of 550 nm) with a layer with a low index, ie less than 1.7 (at a wavelength of 550 nm). For example, the TiO ₂ /SiO ₂ or Ta ₂ O ₅ /SiO ₂ layer can be alternated. It is also conceivable to combine a layer with a high refractive index, ie greater than 2, with a layer with a medium index, ie between 1.7 and 2, with a layer with a low index, ie less than 1.7 (always at a wavelength of 550 nm), alternate. For example, the layers of TiO ₂ /Al ₂ O ₃ /SiO ₂ can be alternated.

The substrate can be formed from any type of material, e.g. B. made of metal, ceramic or polymer. It could also be a substrate of a precious or semi-precious stone such as sapphire. If it is transparent, the individual layers can be applied directly to the substrate. The iridescent effect can be visible on the side where each layer is applied or through the substrate. If the substrate is opaque, e.g. B. with ceramic or metal, a mirror surface is required to create a reflection of the light on the surface and get the interference colors. Typically is a metal layer of Ti, Cr or Ag to create this mirror interface.

The layers can be deposited by various methods, including PVD (Physical Vapor Deposition), CVD (Chemical Vapor Deposition), Sol-Gel or ALD (Atomic Layer Deposition). The variation in thickness can be done during deposition or later by patterning the layer when a single layer is present, or the deposited layers when multiple layers are present. According to the first variant, in which the thickness is varied during deposition, there are several techniques. One technique consists in tilting the workpiece so that a more or less linear variation in thickness is obtained. So will, as in 4 is shown schematically, the substrate 2 is placed on an inclined support 6 . Another technique is to use a mask or cover 5 to occlude certain areas during deposition ( 3 ). The mask can be a varnish, an adhesive, a photosensitive film, etc. It can be applied, for example, by photolithography, stereolithography, digital printing or manually on an adhesive or a film that then resembles a cover. Another technique consists in creating a shading of the substrate during deposition, using a mask that modifies the dynamics of the flows of material that reach the surface, and therefore the thickness. According to the second variant, several techniques can be used to pattern the single layer or layers deposited after deposition. Examples include laser engraving and photolithography.

Trials were conducted on bezels with a sapphire substrate. Alternating layers of silicon dioxide (SiO ₂ ) and tantalum pentoxide (Ta ₂ O ₅ ) were deposited by PVD. The number of layers was between 20 and 50 with a maximum thickness Y of the stacking between 800 nm and 1.5 μm. The bezels produced in this way showed a very nice iridescent effect.

QUOTES INCLUDED IN DESCRIPTION

This list of documents cited by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent Literature Cited

• EP 3608728 [0002]

Claims (18)

Object with an iridescent color obtained by interference effect, said object comprising a substrate (2) covered with a single layer (4) or a stack (3) of layers (4) with at least two layers (4), the single layer (4) or the stack (3) has a variable thickness that gives this iridescent color. Object according to the preceding claim, characterized in that the single layer (4) or stack (3) has a maximum thickness Y and in that at one or more points the thickness is less than or equal to 0.98*Y. Object according to the preceding claim, characterized in that the maximum thickness Y is between 200 nm and 20 µm, preferably between 200 nm and 1.5 µm, particularly preferably between 500 nm and 1.5 µm. Article according to the preceding claim, characterized in that within the single layer (4) or stack (3) the thickness is between 0 and the maximum thickness Y. Object according to one of the preceding claims, characterized in that the number of layers (4) within the stack (3) is between 2 and 1000, preferably between 2 and 100, particularly preferably between 20 and 50. Article according to any one of the preceding claims, characterized in that each layer (4) is a transparent, translucent or semi-transparent layer with a choice of materials from oxides, nitrides, fluorides, metals and semiconductors. Object according to one of the preceding claims, characterized in that the stack (3) comprises a layer (4) with a refractive index greater than 2 alternating with a layer (4) with a refractive index less than 1.7. Object according to the preceding claim, characterized in that the stack (3) comprises alternating layers (4) of TiO ₂ /SiO ₂ or Ta ₂ O ₅ /SiO ₂ . item after one of Claims 1 until 6 , characterized in that the stack (3) has a layer (4) with a refractive index greater than 2 alternating with a layer (4) with a refractive index between 1.7 and 2 with a layer (4) with a refractive index less than 1.7. Object according to the preceding claim, characterized in that the stack (3) has alternating layers (4) of TiO ₂ /Al ₂ O ₃ /SiO ₂ . Object according to one of the preceding claims, characterized in that each layer (4) has an average thickness of between 1 nm and 900 nm, preferably between 100 nm and 500 nm. Article according to one of the preceding claims, characterized in that the substrate (2) is opaque and has a metal layer between the substrate (2) and the stack (3). Object according to the preceding claim, characterized in that the metal layer forms a mirror surface. Object according to one of the preceding claims, characterized in that it is a component of the equipment or of the clockwork in watchmaking. Object according to the preceding claim, characterized in that it is a transparent bezel (1). Object according to one of the preceding claims, characterized in that the variable thickness during deposition is achieved by using a cover or mask (5) to hide one or more places during deposition of each layer (4) or certain layers (4) of the stack (3) or is determined by placing the substrate (2) on an inclined base (6). Object according to the preceding claim, characterized in that the individual layer (4) or the stack (3) is structured by laser engraving or photolithography. Object according to one of the preceding claims, characterized in that each layer (4) of the stack (3) is deposited by PVD, CVD, sol-gel or ALD.

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