Method for processing mirrored optical articles

Abstract

The invention relates to a method for treating a mirror optical article comprising: - a substrate (10), - a mirror stack (21) carried by the substrate (10) having at least two interference layers (M1 to M6) which thereby increase reflection and having: * an interference layer (M1) remote from the substrate (10) and having a first initial thickness and a first refractive index, and * at least one near interference layer (M2) arranged between the substrate (10) and the remote interference layer (M1) and having a second thickness and a second refractive index different from the first refractive index, the mirror stack (21) imparting to the mirror optical article (1) a first color according to the CIELAB space by the interference phenomenon, the method comprising a step (103) of removing a thickness of the mirror stack in at least one first predetermined zone (Z1) by ion bombardment, the thickness being less than the sum of the initial thicknesses involved in the removal step, the mirror optical article having a second color different from the first color in the CIELAB space by the interference phenomenon.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of treatment of optical articles, in particular to the field of treatment of mirror effect ophthalmic lenses, in particular to the field of treatment of mirror effect ophthalmic lenses coated with a multilayer interference coating. BACKGROUND

[0002] The optical article is in particular a corrective or non-corrective lens that can be used as a spectacle lens, for example in eyeglasses, in particular in sunglasses or goggles, etc.

[0003] Currently, optical articles, in particular ophthalmic lenses, more particularly sunglasses, are not only intended to protect the eyes from sunlight, but also have an aesthetic appearance that is important to the wearer of these optical articles.

[0004] Thus, for example, the wearer of eyeglasses needs individualized optical articles in order to stand out through the appearance of the optical article, in particular through the appearance in terms of color and reflection.

[0005] However, as is often the case in industry, individualization greatly increases the cost price of the articles produced and is generally contrary to the low cost price of standardized production.

[0006] In the present example, the mirror effect optical article, i.e. the optical article comprising a multilayer interference coating, has a uniform appearance.

[0007] In order to individualize such an optical article, it is possible to consider, for example, using a pad printing mask made of silicone to modify the thickness of one or more layers of the multilayer interference coating in certain areas. However, such a process lacks precision with respect to the profile (creep problem) and with respect to repeatability. In addition, adhesion problems of the layers subsequently deposited on the pad printing areas are observed and thus an increase in the rejection rate is observed.

[0008] Thus, laser engraving of certain layers of the multilayer interference coating seems to be an attractive option. However, such laser engraving can create micro-cracks in the optical article, thus reducing the lifetime of the optical article. In addition, such engraving is not carried out under a controlled atmosphere and particles can be deposited on the optical article thus treated, subsequently leading to visible defects, and for example, the anti-fouling treatment can no longer adhere successfully.

[0009] Document WO2018015650 describes a method for marking an optical article in which laser ablation is used. DE10 2011 119598 describes a multilayer deposition process. SUMMARY

[0010] The object of the present application is therefore to at least partially alleviate the aforementioned drawbacks by providing a method for processing a mirroring optical article comprising:

[0011] - a substrate,

[0012] - a mirror stack having at least two interference layers carried by the substrate, which thereby increases the reflectivity and which has:

[0013] o an interference layer, remote from the substrate, and having a first initial thickness and a first refractive index, and

[0014] o at least one near-interference layer, placed between the substrate and the remote interference layer, and having a second thickness and a second refractive index different from the first refractive index,

[0015] the mirror stack imparting, via an interference effect, a first color in the CIELAB space to the mirroring optical article,

[0016] the method comprising a step of removing, via ion bombardment, at least from a first predetermined zone, a mirror stack thickness which is less than the sum of the initial thicknesses involved in the removal step, the mirroring optical article presenting, via an interference effect, a second color in the CIELAB space different from the first color.

[0017] Thus, using a standardized production process, it is possible to personalize the mirroring optical article in a very precise and reproducible manner.

[0018] The method according to the application can have one or more of the following aspects, alone or in combination:

[0019] In the step of removal via ion bombardment, the initial thickness of the remote interference layer can be reduced by a value less than its initial thickness. The mirror stack comprises for example two interference layers (exactly two) or at least three interference layers, and the reduction of the thickness of the remote interference layer is for example determined so that the difference in hue angle between the first color and the second color is less than 2% and the difference in chroma is greater than 10%. The difference in lightness between the first color and the second color is in particular less than 10%, more particularly less than 5%.

[0020] The b* / a* ratio in the CIELAB space can be constant within a tolerance of 10%, in particular within a tolerance of 5%.

[0021] The reduction in thickness is uniform in each of the predetermined zones.

[0022] A step of determining the ion bombardment time required to obtain the second color in the first predetermined area can be provided before the step of removing via ion bombardment.

[0023] The step of removing via ion bombardment in particular causes the mirror effect optical article to exhibit, via interference effects, a mirror effect in the first predetermined area having a different reflectivity than the areas not treated by the ion bombardment.

[0024] The mirror effect article can comprise the first predetermined area and areas not treated by the ion bombardment, one of the two areas corresponding to a near vision area, the mirror effect of which has a lower reflectivity than the mirror effect of the other areas corresponding to far vision areas.

[0025] The area of the first predetermined area is for example less than the area of the mirror effect optical article, and the method can further comprise a second step of removing via ion bombardment at least from a second predetermined area of the mirror effect optical article different from the first predetermined area (additional removal step), in which second removal step a second predetermined thickness of the far interference layer is removed from the second predetermined area, the second predetermined thickness being less than the first initial thickness of the far interference layer and different from the thickness removed in the first removal step, the mirror effect optical article exhibiting, via interference effects, a third color in the CIELAB space different from the first color and the second color in the CIELAB space.

[0026] The step of removing via ion bombardment can be carried out in a box coater equipped with an ion gun.

[0027] In particular, a mask is placed between the mirror effect optical article and the ion gun to prevent the ions from reaching the interference layer outside the predetermined area.

[0028] The mask in particular comprises an adhesive attached to the mirror effect optical article.

[0029] The mask can comprise a shield, in particular a metal shield placed between the ion gun and the mirror effect optical article.

[0030] The ion bombardment can be carried out under vacuum or in an atmosphere containing an inert gas at a pressure lower than or equal to atmospheric pressure. After the step of removing via ion bombardment, an anti-fouling treatment is in particular applied to the entirety of the mirror effect optical article.

[0031] The invention also relates to a mirror effect optical article obtained by the method presented above and having at least two different colors in the CIELAB space.

[0032] The mirror effect article notably comprises said first predetermined area and an area not treated by said ion bombardment, one of the two areas corresponding to a near vision area, the reflectance of the mirror effect of said near vision area being lower than the reflectance of the mirror effect of the other area corresponding to a far vision area. BRIEF DESCRIPTION OF DRAWINGS

[0033] Other features and advantages of the application will become more apparent on reading the following description given by way of illustrative and non-limiting example, and on examination of the attached drawings in which:

[0034] Figure 1A a mirror effect optical article is schematically represented,

[0035] Figure 1B a cross section along the axis of the mirror effect article is shown, Figure 1A Figure 1A a mirror effect article of the application,

[0036] Figure 2 a layer stack of the mirror effect optical article according to the first embodiment is schematically represented, Figure 1A and 1B a layer stack of the mirror effect optical article,

[0037] Figure 3 a layer stack of the mirror effect article according to the second embodiment is schematically represented,

[0038] Figure 4 a front face of the mirror effect optical article is shown according to examples of embodiments of Figure 1A , 1B , 2 and 3,

[0039] Figure 5 is a simplified side view of a partial cross section of a treatment chamber that can be used to treat a mirror effect optical article,

[0040] Figure 6 a flow chart of an example of implementation of a method for treating a mirror effect optical article is shown,

[0041] Figure 7 is a first variant of Figure 4 ,

[0042] Figure 8 is a second variant of Figure 4 ,

[0043] Figure 9 is a third variant of Figure 4 ,

[0044] Figure 10 ​Regions of a mirroring optical article according to one example are shown before and after performing a treatment method in terms of reflectivity. DETAILED DESCRIPTION

[0045] Examples of one embodiment will now be described with reference to the accompanying drawings. In all drawings, like reference numerals are used to denote like elements.

[0046] Thus, for Figure 2 and Figure 3 schematic examples of a layer stack can be easily derived from Figure 1A and 1B similar figures by adding or removing various layers thereto.

[0047] The following examples are illustrative. Although described with reference to one or more embodiments, this does not necessarily mean that every reference is to the same embodiment or that features only apply to a single embodiment. Individual features of the various embodiments can also be combined to create further embodiments.

[0048] The “front” or “back” face of a layer refers to the propagation of light rays towards the eye. Thus, the “front” face is always the face closest to the field of view of the user, while the “back” face is always the face closest to the eye of the user.

[0049] “Upstream” or “downstream” of two elements or layers refers to the propagation of light rays towards the eye. Thus, when light first passes through a first element and then a second element in its path towards the eye of the user, the first element is placed “upstream” of the second element. By contrast, when light first passes through the second element and then the first element in its path towards the eye of the user, the first element is placed “downstream” of the second element.

[0050] In the present specification, the UV domain of ultraviolet rays comprises wavelengths less than 380 nm.

[0051] In the present specification, the visible domain comprises wavelengths between about 380 nm and about 800 nm, in particular between about 400 nm and 750 nm.

[0052] Reflectivity is defined as the average light reflectance p V as defined in standard ISO 12311 :2013 section 7.7.

[0053] The percentage value of p V is obtained by calculating the ratio of the light flux F R reflected by the filter to the incident light flux F I as follows:

[0054]

[0055] wherein:

[0056] λ is the wavelength in nanometers;

[0057] ρ(λ) is the spectral reflectance of the filter at wavelength λ;

[0058] V(λ) is the relative sensitivity of the human eye as defined in ISO 11664-1;

[0059] S D65 (λ) is the spectral power distribution of the CIE standard illuminant D65 as defined in ISO 11664-2.

[0060] Hue angle and chroma are defined by standard NF ISO 11664-4:2011-07 section 4.2.

[0061] It is known that a* and b* are CIELAB color coordinates.

[0062] Chroma is defined as:

[0063] C* ab = [(a*) 2 +(b*) 2 ]1 / 2.

[0064] Hue angle is defined as: h ab = arctan(b* / a*).

[0065] If a* and b* are both positive, the hue angle must be between 0° and 90°; if b* is positive and a* is negative, the hue angle must be between 90° and 180°; if b* and a* are both negative, the hue angle must be between 180° and 270°; if b* is negative and a* is positive, the hue angle must be between 270° and 360°.

[0066] Luminance is defined by BYK calculation.

[0067] The expression "reflectance" is used, and "reflectance" is defined by or equivalent to the average light reflectance such as the one defined above.

[0068] Figure 1A and 1B The mirror effect optical article 1 is for example intended to be used in eyeglasses, in particular sunglasses or goggles, in particular as ophthalmic lenses. To this end, it is only necessary to trim the outer edge 3 to the shape required by the rim of the eyeglasses or of a pair of goggles.

[0069] In Figure 1A and 1BIn the middle, an arrow 5 representing light incident on the mirror effect article 1 and an eye 7 of a user have been shown. Thus, the field of view 13 is located on one side of the arrow 7 and the user looks through the mirror effect optical article 1 with his eye 7.

[0070] The mirror effect article 1 refers in particular to a finished or semi-finished, corrective or non-corrective lens, able to be mounted in a frame, such as a spectacle frame, eyeglasses or a visor intended to be placed in front of the eyes and forming a visual protection screen. The mirror effect optical article 1 is a starting product that will be subjected to the following treatments.

[0071] The mirror effect article 1 can be made of mineral glass or organic glass or a combination of mineral glass and organic glass.

[0072] The mirror effect optical article 1 can optionally be tinted or have a tint gradient, and it can comprise, alone or in combination, other solar-related functions, such as a polarizing function and / or a photochromic function, as will be seen below. The mirror effect optical article belongs for example to class 2, 3 or 4 according to standard ISO 12312.

[0073] It can also comprise, alone or in combination, other additional functions from the following non-exhaustive list: impact resistance, scratch resistance, wear resistance, anti-reflective properties, anti-fouling properties, anti-fog properties, anti-static properties. These additional functions can be produced using conventional methods (dip coating, vacuum deposition, spin coating, spray coating, etc.).

[0074] Reference is made to Figure 1A and 1B The mirror effect optical article 1 comprises a transparent substrate 10.

[0075] This transparent substrate 10 has a back face 10 AR and a front face 10 AV The back face 10 AR is intended to be oriented towards the eye 7 of the user and is intended to form the back outer face of the mirror effect article 1, i.e. the surface oriented towards the user's eye, the front face 10 AV being oriented towards the field of view 13 of the user.

[0076] Transparent means that the layer allows the incident light to pass through completely or at least partially. The transparent substrate 10 can be tinted, i.e. for example comprise or not comprise a tinting agent and / or a pigment.

[0077] More generally, the material(s) of certain layers of the mirror effect optical article 1 can be made of any material commonly used in the field of optics, in particular in the field of ophthalmology.

[0078] For example, the thermoplastic can be chosen from the following non-exclusive group: poly(methyl) methacrylate, polycarbonate, polycarbonate / polyester blends, polyamide, polyester, cyclic olefin copolymer, polyurethane, polysulfone, cellulose triacetate (CTA), polyimide, polyurethane; polyethylene terephthalate and poly(methyl methacrylate) (PMMA); and copolymers and combinations thereof.

[0079] For example, the thermoset can be chosen from the following non-exclusive group: cellulose acetate butyrate (CAB), ethylene / norbornene copolymer or ethylene / cyclopentadiene copolymer; homopolymers and copolymers of allyl carbonates of aliphatic or aromatic linear or branched polyols, such as homopolymers of diethylene glycol bis(allyl carbonate) (CR ) ; homopolymers and copolymers of methacrylic acid and esters, which can be derivatives of bisphenol A; polymers and copolymers of thiomethacrylic acid and esters, (polymers and copolymers of urethane and thiourethane), (polymers and copolymers of epoxy resins), (polymers and copolymers of sulfides and episulfides) and combinations thereof.

[0080] In order to color the thermoplastic, a pigment or a colorant can be added. As regards the pigments, the latter can be organic or mineral pigments.

[0081] The material of the substrate 10 is for example chosen from the group of the following materials: poly(methyl) methacrylate, polycarbonate, polycarbonate / polyester blends, polyamide, polyester, cyclic olefin copolymer, polyurethane, polysulfone, cellulose triacetate (CTA) or cellulose acetate butyrate and combinations thereof.

[0082] The back face 10 AR The fact of forming an outer surface does not prevent it from being treated, for example by a scratch-resistant and / or anti-fouling and / or anti-reflective treatment.

[0083] The mirror stack 21 is placed upstream of the substrate 10.

[0084] According to the embodiments of Figure 1A , 1B and 2, a polarizing assembly 31, for example comprising a polarizing film, in particular a polarizing film of polyvinyl alcohol (PVA) doped with iodide and axially stretched, of the type well known for its polarizing properties, can be placed between the mirror stack 21 of one aspect and the substrate 10 of the other aspect and fixed to the mirror stack 21 and to the substrate 10 by means of adhesive layers 33 and 35. In the polarizing assembly 31, the polarizer film can be sandwiched between two thin layers, in particular made of thermoplastic material, dedicated to the protection of the polarizer film. The polarizing assembly 31 can also be formed solely by the polarizer film.

[0085] The polarizing assembly 31 is adhesively joined to the back face 21 of the mirror stack 21 AR and the front face 10 of the substrate 10 AV .

[0086] According to a first variant (not shown), an adhesive layer is placed between the polarizing assembly 31 and the substrate 10.

[0087] According to a second variant (not shown), a scratch-resistant layer is placed between the polarizing assembly 31 and the mirror stack 21.

[0088] In addition, a varnish can be placed on the polarizing assembly 31 so that the varnish is located between the polarizing assembly 31 and the mirror stack 21.

[0089] In the polarizing assembly 31, if the polarizer film is sandwiched between two thin layers, in particular two thin layers made of thermoplastic, the most downstream layer can also serve as an adhesive layer as described above.

[0090] Figure 2 The mirror stack 21 is shown in more detail in Figure 2. It comprises, for example, a series of thin layers M1, M2, M3, M4, M5 and M6. Adjacent thin layers have different refractive indices from one another. However, two non-adjacent thin layers can have the same refractive index as one another.

[0091] The layer M1 is a far interference layer, remote from the substrate 10, having a first initial thickness e 1-init and a first refractive index n1.

[0092] The layers M2 to M6 are near interference layers, placed between the substrate 10 and the far interference layer M1, having respectively an initial thickness e j-init and a refractive index n j (in the present example, j is an integer from 2 to 6).

[0093] In particular, the layer M2 has a second initial thickness e 2-init and a refractive index n2 different from the first refractive index n1.

[0094] The mirror stack 21, of course in agreement with the layer located far downstream in the direction of the eye of the user 7, imparts a first color in the CIELAB space to the mirror effect optical article 1 via the interference effect. The number, the refractive indices and the thicknesses of the layers in the stack are determined beforehand, by experiment, by calculation or by computer or simulator, in order to obtain said first color having a predetermined reflectance.

[0095] Of course, the number of thin layers M j may vary, for example there can be only two, four or eight layers.

[0096] The first thin layers M1, M3 and M5 are made of silicon dioxide (SiO2), for example, while the second thin layers M2, M4 and M6 are made of titanium oxide (Ti3O5), for example.

[0097] Other materials may be selected, for example, such that in the visible light domain, the first thin layers M1, M3 and M5 have a first refractive index n1 less than or equal to 1.5, and the second thin layers M2, M4 and M6 have a second refractive index n2 greater than 2, in particular, a second refractive index n2 equal to or greater than 2.3.

[0098] Typically, the first thin layers M1, M3 and M5 have a thickness between 70 nm and 250 nm, and the second thin layers M2, M4 and M6 have a thickness between 40 nm and 80 nm.

[0099] According to a very specific example, the mirror stack 21 is formed in the following way:

[0100]

[0101]

[0102] like Figure 2 As shown, the first thin layers M1, M3 and M5 and the second thin layers M2, M4 and M6 are therefore arranged alternately.

[0103] Mirror stacks 21 are typically manufactured by vacuum deposition of thin layers in a box coater.

[0104] As a result, for example, the polarization component 31, including the polarizer film, is adhesively bonded to the second thin layer M6 and the front side 10 of the substrate 10. AV .

[0105] Figure 3 Implementation examples and Figure 2 The only difference in this embodiment is that the polarizer assembly 31 is not provided. The substrate 10 is then fixed to the back 21 of the mirror stack 21. AR Downstream of.

[0106] The substrate 10 can be fixed to the back side 21 of the mirror stack 21 using adhesive 35. AR .

[0107] According to one variant (not shown), an adhesive layer (specifically, an adhesive layer made of thermoplastic) may be placed between the mirror stack 21 and the substrate 10.

[0108] According to one embodiment (not shown), a photochromic layer that can be activated in the UV and / or visible light domains can be used instead of polarization component 31.

[0109] The photochromic layer can be a thermoplastic including known photochromic dyes. By way of example, mention is simply made of the following families commonly used in ophthalmic lenses: spirooxazines, spirodihydroindolino[2,3']benzoxazines, chromenes, diazepinophenoxazinones, spirofluorene-(2H)- benzopyrans, naphtho[2,1-b]pyrans and naphtho[1,2-b]pyrans.

[0110] Figure 4 The front face (i.e. in the direction of the arrow 5) of the mirror effect optical article 1 is shown, according to the example of embodiment of the preceding figures.

[0111] In this figure, the first zone Z1 to be treated according to the method of the application has been drawn with dotted lines. In the present example, the area of the zone Z1 is less than the area of the mirror effect optical article 1. Its extent is thus less than the diameter of the mirror effect optical article 1.

[0112] Before carrying out the treatment process, the non-treated zone(s) located outside the first zone Z1 are protected, for example by the application of at least one protective adhesive film Fp to the thin layer M1. Thus, this Figure 4 The protective film Fp and the layers M1 of the mirror stack 21 in the zone Z1 are shown.

[0113] According to another example, the zone Z1 covers the entirety of the mirror effect article 1, so that, after the treatment process, the appearance of the mirror effect article 1 will change, in particular its colour.

[0114] According to yet another example, a plurality of zones, for example Z1, Z2, etc., can be provided, as will be seen hereafter.

[0115] To this end, the mirror effect optical article 1 is for example placed in a tool 220 allowing the mirror effect optical article 1 to be treated by ion bombardment.

[0116] This tool 220 comprises a treatment chamber 221 and an emission source 222 emitting ions for bombarding the mirror effect optical article 1, for example in the form of an evaporation cone 224.

[0117] The treatment chamber 221 can be hermetically sealed and connected to a vacuum generator (not shown), for example a vacuum pump, to reduce the pressure inside the treatment chamber 221 to a pressure suitable for the treatment to be applied and generally of the order of 3x10 -5 mbar.

[0118] Alternatively, the ion bombardment can be carried out in an atmosphere containing an inert gas at a pressure lower than or equal to atmospheric pressure.

[0119] The emission source 222 comprises for example an ion gun or holder on which the material to be evaporated is placed, an ion source or a plasma generator, and for example a crucible or a target, in order to evaporate the material, for example it is necessary to subject the material to a Joule heating, an electron bombardment or a cathodic sputtering effect. The ion source can be a tungsten wire forming a cathode. The gas diffuser or plasma generator can be formed by a graphite anode. In this case, such an emission source 222 does not require a crucible or a target.

[0120] The rotating holder 226 for the mirror effect optical articles 1 is placed above the emission source 222.

[0121] To this end, the rotating holder 226 comprises individual housings 228 for the mirror effect optical articles 10.

[0122] The individual housings 228 are for example arranged on concentric tracks.

[0123] It will be understood that each of the individual housings 228 makes a 360° rotation when the holder 226 rotates.

[0124] The rotating holder 226 has for example a concave shape or more particularly a skull-cap shape, so that the individual housings 228 of the mirror effect optical articles 1 are located at an equal distance from the sub-emission sources 222.

[0125] The rotating holder 226 can rotate around an axis A corresponding to the axis of symmetry of the rotating holder and passing through its center, which allows to increase the uniformity of the exposure of the mirror effect optical articles to the ion bombardment.

[0126] The tool 220 is for example a box coater, which is specially equipped with ion guns and also allows the application of other treatments, in particular treatments for finishing the mirror effect optical articles 1, for example anti-smudge treatments. As mentioned above, the box coater can also be used to produce the mirror stack 21.

[0127] The tool 220 thus makes it possible to perform in the same machine the various steps in the manufacture of optical articles, in particular even certain steps preceding those involved in the method of the application.

[0128] One or more areas of the mirror effect optical articles 1 which are not necessarily treated are thus protected by a shield, for example an adhesive film Fp, before being introduced into the tool 222.

[0129] Alternatively, instead of a protective film Fp, a mask, in particular a shield, in particular made of metal, can be provided in the tool 220 between the mirror effect optical articles 1 and the ion guns, in order to prevent the ions from reaching the interference layer outside the predetermined areas Z1.

[0130] The method comprises a first step 103 (see Figure 6 ) which consists in removing, via ion bombardment, a thickness et of the mirror stack 21 in at least a first predetermined zone Z1, this thickness being less than the sum of the initial thicknesses involved in the removal step.

[0131] More particularly, the treatment process aims to remove the thin layers M j , and, where appropriate, completely, the one or more thin layers M1 to M j-1 which are furthest from the substrate 10. i For the purposes of the present application, for i < j, the layer M j is further from the substrate 10 than the layer M t .

[0132] For example, according to a first embodiment, the tool 220 is configured to remove from the thin layer M1 a thickness e 1-init , i.e. the initial thickness e 1-init of the far interference layer M1 is reduced by a value et which is less than the initial thickness e 1-init . A remaining thickness e r of the layer M1 will thus be obtained, equal to e 1-init – e t . This example is most relevant generally in the case where the mirror stack 21 has two or more than three thin interference layers M j .

[0133] More generally, if a portion of the layer M k (k is an integer, in the present example k = 1 to 6, preferably k = 1 or 2) is removed, the thickness removed from the predetermined zone Z1 via ion bombardment is defined by the following equation:

[0134]

[0135] The remaining thickness of the layer M r is thus comprised between 0.05 e k-init and e r .

[0136]

[0137] For example, the remaining thickness e r of the layer M k-init is comprised in the range 0.05 e r < 0.95 e k-init .

[0138] The mirror effect optical article 1 thus has, in this predetermined zone Z1, a second colour in the CIELAB space via the interference effect, which is different from the first colour of the mirror effect optical article 1 or of the untreated zones of the mirror effect optical article 1.

[0139] The ongoing advantage is thus the precision of the removal of a certain thickness and its repeatability on an industrial scale, thus making it possible to obtain predictable high-quality results in terms of the second color.

[0140] According to one example, the mirror stack 21 comprises at least three interference layers (for example in the case of a mirror stack 21 comprising a first mirror layer M1, a second mirror layer M2 and a third mirror layer M3) and the ion bombardment removes only some of the thin layer M1. Figure 2 and 3 In the case where the ion bombardment removes only some of the thin layer M1, the reduction et of the thickness of the far interference layer M1 is determined so that the difference in the hue angle between the first color and the second color is less than 2% and the difference in chroma is greater than 10%.

[0141] According to another example, the reduction et of the thickness of the far interference layer M1 is determined so that the difference in luminance between the first color and the second color is less than 10%, in particular less than 5%.

[0142] According to yet another example, the reduction et of the thickness of the far interference layer M1 is determined so that the ratio b* / a* in the CIELAB space is constant within a tolerance of 10%, in particular within a tolerance of 5%, between the first and second colors.

[0143] After this first step 103, it is observed that the reduction in thickness is uniform in the predetermined region Zi or in each predetermined region Zi.

[0144] According to one variant, step 103 is preceded by an optional step 101 of determining the ion bombardment time T required to obtain the second color in the first predetermined region Z1.

[0145] According to another example, the reduction et of the thickness of the far interference layer M1 is determined so that the mirror effect optical article 1 exhibits, via the interference effect, a mirror effect with a different reflectance in the first predetermined region Z1 than in the region not treated by the ion bombardment.

[0146] In the variant of Figure 4 , the mirror effect optical article comprises said first predetermined region Z1 and a region not treated by the ion bombardment, protected by a protective film Fp, and one of these two regions, here the region Z1, corresponds to a near vision region, the reflectance of the mirror effect of which is lower than the reflectance of the mirror effect of the other region (not treated) corresponding to a far vision region. Figure 7 According to the variant of

[0147] , the mirror effect optical article comprises said first predetermined region Z1 and a region not treated by the ion bombardment, protected by a protective film Fp, and one of these two regions, here the region Z1, corresponds to a near vision region, the reflectance of the mirror effect of which is lower than the reflectance of the mirror effect of the other region (not treated) corresponding to a far vision region. Figure 8In another variant illustrated, in which the area of the first predetermined zone Z1 is smaller than the area of the mirroring optical article 1, the method can also comprise a second step of removal 105 via ion bombardment at least from a second predetermined zone Z2 of the mirroring optical article 1 different from the first predetermined zone Z1. In this second removal step 105, the zone Z1 can be protected, for example by an additional adhesive film Fp, and a second predetermined thickness of the far interference layer M1 is removed, which is smaller than the first initial thickness of this far interference layer and different from the thickness removed in the first removal step 103. The result is that, in the second predetermined zone Z2, the mirroring optical article 1 presents, via interference effects, a third color in the CIELAB space different from the first and second colors in the CIELAB space. A trichromatic mirroring optical article is thus obtained.

[0148] According to Figure 9 In another variant illustrated, in which the area of the first predetermined zone Z1 is smaller than the area of the mirroring optical article 1, the method can also comprise a second step of removal 105 via ion bombardment at least from a second predetermined zone Z2 of the mirroring optical article 1 different from the first predetermined zone Z1. In this second removal step 105, the zone Z1 can be protected, for example by an additional adhesive film Fp, and a second predetermined thickness of the far interference layer M1 is removed, which is smaller than the first initial thickness of this far interference layer and different from the thickness removed in the first removal step 103. The result is that, in the second predetermined zone Z2, the mirroring optical article 1 presents, via interference effects, a third color in the CIELAB space different from the first and second colors in the CIELAB space. A trichromatic mirroring optical article is thus obtained.

[0149] In the second removal step 105, the adhesive protection film Fp protects all the zones of the mirroring optical article except the predetermined zone Z2, and a predetermined second thickness of the far interference layer M1 is removed, which is smaller than the difference between the first initial thickness of this far interference layer and the thickness removed in the first removal step. In the second predetermined zone, the mirroring optical article 1 thus presents, via interference effects, a third color in the CIELAB space different from the first and second colors in the CIELAB space.

[0150] It will thus be understood that the method for treating a mirroring optical article 1 allows certain parameters, in particular the color, to be changed accurately and repeatedly, to obtain a personalized product with a cost price included.

[0151] Figure 10 The reflectance of the mirroring optical article 1 as a function of the wavelength is illustrated, for example, in the predetermined zone Z1, before (curve C1) and after (curve C2) the step 103 of the treatment process. Before the treatment of the step 103, the entirety of the mirroring optical article 1, more particularly the predetermined zone Z1, has a “blue” appearance, whereas after the treatment, the predetermined zone Z1 has a “bronze” appearance, as illustrated in the curves C1 and C2 in FIG. 4. Figure 10The spectrum shown in Figure 6 illustrates the color change of the mirror effect optical article 1. Starting from a mirror effect optical article 1 having a predetermined color, a mirror effect optical article having another color or having two or even three different colors is obtained. According to some examples, the change of color can be less apparent and lead to a "pastel" effect for example.

[0152] Furthermore, by examining the mirror effect optical article treated according to the above method, in particular using an electron microscope, it can be observed that the thickness of the stack of mirrors has been removed from the predetermined area by ion bombardment. In particular, in the predetermined area Z1 for example, it can be observed that the layers subjected to ion bombardment become denser with respect to the areas in which the layers are not subjected to ion bombardment.

Claims

1. A method for treating a mirror effect optical article comprising: - a substrate (10), - a mirror stack (21) having at least two interference layers (M1 to M6) carried by the substrate (10), which thereby increases the reflectivity and has: o a far interference layer (M1) distal from the substrate (10) and having a first initial thickness and a first refractive index, and o at least one near interference layer (M2) placed between the substrate (10) and the far interference layer (M1) and having a second thickness and a second refractive index different from the first refractive index, the mirror stack (21) imparting a first color in the CIELAB space to the mirror effect optical article (1) via an interference effect, the method comprising a first removal step (103) of mirror stack thickness via ion bombardment at least from a first predetermined zone (Z1), the mirror stack thickness being less than the sum of the initial thicknesses involved in the first removal step, the mirror effect optical article presenting a second color in the CIELAB space different from the first color via an interference effect.

2. The method of claim 1, wherein, In the first removal step (103) via ion bombardment, the initial thickness of the far interference layer is reduced by a value less than its initial thickness.

3. The method of claim 2, wherein, The mirror stack (21) comprises two interference layers (M1, M2) or at least three interference layers (M1 to M6) and wherein the reduction of the thickness of the far interference layer is determined so that the difference in hue angle between the first color and the second color is less than 2% and the difference in chroma is greater than 10%.

4. The method of claim 2, wherein, The difference in lightness between the first color and the second color is less than 10%.

5. The method of claim 2, wherein, The b* / a* ratio in the CIELAB space is constant within a tolerance of 10%.

6. The method of any one of claims 1 to 5, wherein, The reduction in thickness is uniform in each of the predetermined zones.

7. The method of any one of claims 1 to 5, wherein, The first removal step via ion bombardment is preceded by a step (101) of determining the ion bombardment time required to obtain the second color in the first predetermined zone.

8. The method of any one of claims 1 to 5, wherein, The first removal step via ion bombardment causes the mirror effect optical article to present, in the first predetermined zone, a mirror effect via an interference effect having a reflectivity different from that of the zones not treated by the ion bombardment.

9. The method of any one of claims 1 to 5, wherein, The mirror effect optical article comprises the first predetermined zone and zones not treated by the ion bombardment, one of the two zones corresponding to a near vision zone (Z1), the reflectivity of the mirror effect of the near vision zone (Z1) being lower than that of the mirror effect of the other zone corresponding to a far vision zone.

10. The method of any one of claims 1 to 5, wherein, The first predetermined area has an area smaller than the area of the mirroring optical article, and wherein the method further comprises a second step of removal via ion bombardment from a second predetermined area (Z2) of the mirroring optical article (1) different from the first predetermined area, in which second removal step a second predetermined thickness of the far interference layer is removed from the second predetermined area, the second predetermined thickness being smaller than the first initial thickness of the far interference layer and different from the thickness removed in the first removal step, the mirroring optical article (1) presenting a third color in the CIELAB space via interference effects, the third color being different from the first and second colors in the CIELAB space.

11. The method of any one of claims 1 to 5, wherein, A mask is placed between the mirroring optical article and the ion gun to prevent ions from reaching the interference layer outside the predetermined area.

12. The method of any one of claims 1 to 5, wherein, The ion bombardment is carried out under vacuum or in an atmosphere containing an inert gas at a pressure lower than or equal to atmospheric pressure.

13. The method of any one of claims 1 to 5, wherein, After the first removal step via ion bombardment, an anti-fouling treatment is applied to the entirety of the mirroring optical article.

14. A mirroring optical article (1) obtained by the method according to any one of claims 1 to 5 and having at least two different colors in the CIELAB space.

15. The mirroring optical article according to claim 14, wherein, The mirroring optical article comprises the first predetermined area (Z1) and an area not treated by the ion bombardment, one of the two areas corresponding to a near vision area, the reflectance of the mirroring effect of the near vision area being lower than the reflectance of the mirroring effect of the other area corresponding to a far vision area.

Images