An ophthalmic lens configured to assume a transparent state and an optional dark state

Abstract

The present invention relates to an ophthalmic lens which is configured to exhibit a transparent state and optionally at least one darker state. The lens has a front surface and a rear surface (Cx and Cc), the front surface and the rear surface respectively defining a front side and a rear side of the lens, the lens having a visual transmittance greater than 81% in the transparent state (FS) at an AOI of 0°, and the lens comprising: - a substrate having a front major surface and a rear major surface adjacent to the front surface and the rear surface respectively, and - at least one multilayer interference coating, the at least one multilayer interference coating including a front multilayer interference coating which is on the front major surface and includes at least one absorbing front layer in the visible region. In the said transparent state, the total visual reflectance Rv_t_rear measured from the rear side at an AOI of 35° from the rear surface and the front surface of the lens is less than 5.0%, and in the said transparent state, the difference R v _t_front - R v _t_rear is greater than 1.0%.

Description

Technical Field

[0001] The present invention relates to an ophthalmic lens configured to exhibit a transparent state and optionally at least one darker state by means of a substrate, which may advantageously be photochromic or electrochromic. The ophthalmic lens may in particular be an eyewear lens that provides a sufficient light transmittance for the wearer together with an acceptable light reflectance in the transparent state, and which advantageously forms a sunglass lens (i.e., for sunglasses) having a front surface that provides a mirror effect for an observer in the at least one darker state. Background Art

[0002] Multilayer interference coatings for ophthalmic lenses are well known in the art, and such coatings can form, for example, an antireflection coating or a reflective (i.e., mirror) coating.

[0003] Antireflection coatings are typically composed of interference thin layers, which are usually based on an alternation of layers of dielectric materials with a high refractive index and dielectric materials with a low refractive index. When deposited on a transparent substrate, the function of such a coating is to reduce its light reflection and thus increase its light transmission, thereby improving the visibility of objects placed behind it. According to the ISO 8980-4 standard, such a coating must have an average light reflection coefficient of less than 2.5% in order to be rated as antireflective. Generally, the average light reflection coefficient R in the visible area on the front and / or back of an ophthalmic lens v is between 1.5% and 2.5%.

[0004] Reflective coatings are typically composed of interference thin layers having the opposite effect (i.e., increasing light reflection). For example, this type of coating is used to provide a sunglass lens with a mirror effect.

[0005] US 2017 / 003520 A1 discloses a mirror-coated lens having a high transmittance and capable of suppressing flare and ghosting phenomena. The mirror-coated lens includes a lens substrate material, a functional film including a low refractive index layer, a high refractive index layer, and a metal layer on the front surface of the lens substrate material, and a functional film including a low refractive index layer and a high refractive index layer on the back surface of the lens substrate material. The light reflectance on the front surface side is from 3% to 30%, the transmittance of the eyewear lens is from 55% to 80%, and the light reflectance on the back surface side is from 0.1% to 9%. The disclosed mirror-coated lens is colored (i.e., always in a relatively dark state) and does not have a transparent (i.e., faded) state because, as disclosed in §

[0014] , its light transmittance does not exceed 80%.

[0006] WO 02 / 14930 A1 discloses an optical lens that has a light-reflective or mirror coating on the rear or intermediate surface and an anti-reflective coating on the front surface. This arrangement helps protect the mirror coating from abrasion and also prevents ghosting due to internal reflection. The lens is suitable for sunglasses and may include a rear lens wafer and a front lens wafer. The disclosed lens also does not have a transparent (i.e., faded) state. Summary of the Invention

[0007] An object of the present invention is to overcome the above-mentioned drawbacks related to the transparent state of ophthalmic lenses, and in particular to obtain for the lens:

[0008] - In the transparent (i.e., faded) state, acceptable anti-reflectivity (i.e., sufficiently low back-side light reflection) and sufficiently high light transmission performance, and advantageously

[0009] - In the dark (i.e., activated) state, acceptable anti-reflectivity (i.e., sufficiently low back-side light reflection) and higher front-side reflection (mirror effect) performance.

[0010] Another object of the present invention is to provide an ophthalmic lens that achieves different and optimized visual performances for the wearer and the observer in both the transparent and dark states, that is, specifically, the total visual reflectance is different when observed from the front side or the back side of the lens in the transparent state and in the dark state, and more specifically, the difference between the total visual reflectance for the observer (mirror effect) and the wearer (anti-reflection characteristics) is maximized in the transparent state and optionally further in the dark state.

[0011] To this end, an ophthalmic lens according to the present invention has a front surface and a rear surface that respectively define the front side and the rear side of the ophthalmic lens. The ophthalmic lens is configured to exhibit a transparent state in which the ophthalmic lens has a visual transmittance greater than 81% in the visible region at an incident angle of 0°. The ophthalmic lens includes:

[0012] - A substrate that has a front principal surface and a rear principal surface adjacent to the front surface and the rear surface respectively, and

[0013] - At least one multi-layer interference coating that includes a front multi-layer interference coating that is on the front principal surface and includes at least one absorption front layer in the visible region,

[0014] Wherein, in the transparent state, the total visual reflectance Rv_t_rear measured from the rear side at an incident angle of 35° in the visible region from both the rear surface and the front surface of the ophthalmic lens is less than 5.0%, and

[0015] Wherein, in the transparent state, the total visual reflectance R v _t_front measured from the front side at an incident angle of 15° in the visible region from both the rear surface and the front surface and the total visual reflectance R v _t_rear measured from the rear side at incident angles between 0 and 15° in the visible region from both the rear surface and the front surface, the difference R v _t_front - R v _t_rear is greater than 1.0%.

[0016] As explained below, the at least one multilayer interference coating may include at least one LI (low refractive index) layer, at least one HI (high refractive index) layer, and the at least one pre-absorbing layer in the visible region, and may further include the at least one pre-absorbing layer at least for the front multilayer interference coating in the visible region.

[0017] It should be noted that the at least one multilayer interference coating may be formed on at least one major surface of a bare substrate (i.e., an uncoated substrate), or on at least one major surface of a substrate that has been coated with one or more functional coatings (such as an anti-abrasion coating or a hard coating).

[0018] In the present specification, the rear (i.e., inner) major surface of the substrate is intended to mean the surface that is closest to the wearer's eyes when the lens is in use; this surface is usually concave. Conversely, the front major surface of the substrate is the surface that is farthest from the wearer's eyes when the lens is in use; this surface is usually convex. Nevertheless, the rear surface of the lens may be convex in some cases, for example, for a biconvex lens used for stronger hyperopia correction.

[0019] As for the substrate, it may be organic or not, especially in the electrochromic embodiment of the lens, the substrate does not have to be organic. By an organic substrate, thermoplastic or thermosetting plastic materials may be mentioned.

[0020] According to another feature of the present invention, the at least one pre-absorbing layer may have an absorptance greater than 3% in the visible region. Advantageously, the at least one pre-absorbing layer may be composed of at least one metal or metal oxide, such as a metal and dielectric mixture or indium tin oxide (ITO).

[0021] According to a preferred embodiment of the present invention, the at least one multilayer interference coating further includes a rear multilayer interference coating, which is on the rear major surface and includes at least one post-absorbing layer in the visible region, and the at least one post-absorbing layer is preferably composed of at least one metal or metal oxide.

[0022] Regarding any one of the above features of the present invention (including the preferred embodiment):

[0023] (i) In the transparent state, the ophthalmic lens can have a visual transmittance of greater than or equal to 85% in the visible region at an incident angle of 0°.

[0024] (ii) The ophthalmic lens can be further configured to exhibit at least one darker state, in which the ophthalmic lens has a visual transmittance between 8% and 80% in the visible region at an incident angle of 0°, and the at least one multilayer interference coating can form a visible reflection coating on the front surface in the at least one darker state, and the visible reflection coating is defined by the total visual reflectance R v _t_front measured from the front side at an incident angle of 15° in the visible region from both the rear surface and the front surface of the ophthalmic lens, and the total visual reflectance can be greater than 2.5%.

[0025] (iii) The ophthalmic lens according to (ii) above can have a visual transmittance between 8% and 43%, preferably between 8% and 20%, in the visible region at an incident angle of 0°.

[0026] (iv) In the at least one darker state, the total visual reflectance R v _t_front of the ophthalmic lens according to (ii) or (iii) above, measured from both the rear surface and the front surface at an incident angle of 15° in the visible region from the front side, can be equal to or greater than 4.0%, preferably greater than 5.0%.

[0027] (v) The ophthalmic lens according to any one of (ii) to (iv) above can satisfy at least one, preferably two, of the following conditions:

[0028] - In the transparent state, the total visual reflectance R v _t_rear of the ophthalmic lens measured from both the rear surface and the front surface at an incident angle of 35° in the visible region from the rear side is less than 2.5%; and

[0029] - In the transparent state, the difference R v _t_front between the total visual reflectance R v _t_rear measured from both the rear surface and the front surface at an incident angle of 15° in the visible region from the front side and the total visual reflectance R v _t_front - R v _t_rear measured from both the rear surface and the front surface at an incident angle between 0 and 15° in the visible region from the rear side is greater than 2.0%.

[0030] (vi) In said at least one darker state, the total visual reflectance R_t_rear measured from the rear side at an incident angle of 35° in the visible region from both the rear surface and the front surface of the ophthalmic lens according to any one of (ii) to (v) above may be less than 1.5%, preferably less than 1.0%. v _t_rear can be less than 1.5%, preferably less than 1.0%,

[0031] (vii) According to any one of (ii) to (vi) above, said at least one multilayer interference coating may be on a hard coating covering an organic support and may include at least one high refractive index stratified unit preferably selected from ZrO 2 , TIO 2 , ITO, SnO 2 and Ta 2 O 5 with a refractive index greater than 1.55 and at least one low refractive index stratified unit preferably selected from SiO 2 , L5 (i.e., "Lima 5"), MgO and MgF 2 with a refractive index below 1.55, said at least one multilayer interference coating preferably having a total thickness of less than 800 nm.

[0032] (viii) According to the preferred embodiment and any one of (ii) to (vii) above, the front multilayer interference coating may have a thickness of less than 550 nm and the rear multilayer interference coating may have a thickness of less than 250 nm.

[0033] (ix) According to any one of (ii) to (viii) above, the ophthalmic lens may be configured to exhibit said transparent state and said at least one darker state by means of said substrate, which is photochromic or electrochromic.

[0034] (x) According to any one of (ii) to (ix) above, the ophthalmic lens may be configured to form a sunglass lens with a front mirror surface in said at least one darker state, and

[0035] (xi) According to any one of the above features (including the preferred embodiment), in the ophthalmic lens, the front surface may be a convex surface and the rear surface may be a concave surface or a convex surface.

[0036] It should be noted that the photochromic or electrochromic lens according to the present invention, due to said at least one absorption front layer (preferably due to both the absorption front layer and the absorption rear layer), may advantageously have an asymmetric stack of different multilayer interference coatings on the rear principal surface and the front principal surface of the lens substrate, wherein the achievement of the asymmetric property includes different total reflectances in the transparent (faded) and darker (activated) states when observed from the front side or the back side of the lens.

[0037] Thus, such a multi-layer interference coating is asymmetric in its structure and in the properties it imparts to the lens, such that different visual performances can be achieved simultaneously for the wearer and the observer in both a transparent and a darker state.

[0038] The ophthalmic lens of the present invention can be an eyeglass lens, such as a polarizing lens, which can be, for example, a photochromic or electrochromic lens, and which can be corrective or non-corrective.

[0039] Furthermore, the ophthalmic lens of the present invention can be inserted into an eyeglass frame or a head-mounted device (HMD). Non-limiting examples of HMDs include immersive and non-immersive devices, particularly see-through devices and surround-view devices. The HMD can be an augmented reality device or a virtual reality device.

[0040] The method for manufacturing an ophthalmic lens as defined above can include depositing the at least one multi-layer interference coating by physical vapor deposition (PVD), but other techniques for producing an interference stack (such as sputtering, sol-gel, etc.) can also be implemented in the present invention, for example by:

[0041] - Optionally ion beam-assisted evaporation,

[0042] - Ion beam sputtering,

[0043] - Cathodic sputtering, or

[0044] - Plasma-assisted chemical vapor deposition.

[0045] These different methods are described respectively in the following reference documents "Thin Film Processes" and "Thin Film Processes II", edited by Vossen & Kern, Academic Press, 1978 and 1991. The method particularly recommended is evaporation under vacuum. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] The present invention will be described in more detail with reference to the accompanying drawings, in which:

[0047] Figure 1 is a diagrammatic side view of a photochromic eyeglass lens in a transparent (faded) state, showing the reflectance Rv and transmittance Tv of the visible light radius through both the rear surface and the front surface of the lens in this state, and

[0048] Figure 2 is Figure 1Diagrammatic side view of a photochromic ophthalmic lens in the dark (activated) state, showing the reflectance Rv and transmittance Tv of the visible light radius through both the rear and front surfaces of the lens in this state. Detailed Description

[0049] The terms "comprises" (and any grammatical variations thereof such as "comprises" and "comprising"), "has" (and any grammatical variations thereof such as "has" and "having"), "contains" (and any grammatical variations thereof such as "contains" and "containing"), and "includes" (and any grammatical variations thereof such as "includes" and "including") are open-ended linking verbs. They are used to specify the presence of the stated features, integers, steps, or components or groups thereof, but do not preclude the presence or addition of one or more other features, integers, steps, or components or groups thereof. Thus, a method or a step in a method that "comprises", "has", "contains", or "includes" one or more steps or elements has those one or more steps or elements, but is not limited to having only those one or more steps or elements.

[0050] Unless otherwise indicated, all numbers or expressions used herein to represent amounts of ingredients, ranges, reaction conditions, etc. are to be understood in all cases as being modified by the term "about". Similarly, unless otherwise indicated, an indication of a value range of "X to Y" or "between X and Y" according to the present invention means a value range that includes X and Y.

[0051] In the present application, when an ophthalmic lens includes one or more coatings on its surface, the expression "depositing a layer or coating onto the lens" is intended to mean depositing the layer or coating onto the outer (exposed) surface of the outer coating of the lens, i.e., the coating that is farthest from the substrate.

[0052] A coating that is said to be "on" a substrate or deposited "onto" a substrate is defined as a coating that (i) is positioned above the substrate, (ii) does not necessarily contact the substrate, i.e., one or more intermediate coatings may be disposed between the substrate and the coating in question, and (iii) does not necessarily completely cover the substrate.

[0053] In a preferred embodiment, a coating on a substrate or deposited onto a substrate is in direct contact with this substrate.

[0054] When "layer 1 is located below layer 2", it is intended to mean that layer 2 is farther from the substrate than layer 1.

[0055] Unless otherwise specified, all thicknesses disclosed in this application refer to physical thicknesses.

[0056] General abbreviations and definitions used in this specification:

[0057] Rv(%) - Visual reflectance (average light reflectance coefficient in the visible domain calculated using the equation given in ISO 13666:1998 and measured according to ISO 8980-4 standard, which is the weighted average of spectral reflectances over all visible spectra between 380 nm and 780 nm).

[0058] Rm(%) - Average reflectance (average of spectral reflectances in the wavelength range from 400 nm to 700 nm).

[0059] Tv(%) - Visual transmittance (light transmittance in the visible domain calculated using the equation given in ISO 13666:1998, which refers to the average relative light transmittance coefficient in the wavelength range from 380 nm to 780 nm, weighted according to the sensitivity of the eye at each wavelength in the range and measured under D65 illumination conditions).

[0060] FS - Faded state (e.g., the state of an unactivated photochromic lens).

[0061] DS - Dark state (e.g., the state of an activated photochromic lens).

[0062] Cc - Concave side (usually the back side of an ophthalmic lens).

[0063] Cx - Convex side (usually the front side of an ophthalmic lens).

[0064] Specific abbreviations and definitions used in this specification in the exemplary and non-limiting case where the back side of the lens is concave:

[0065] Tv_cc_FS - Visual transmittance observed / measured from the Cc (back) side in the faded state.

[0066] Tv_cx_FS - Visual transmittance observed / measured from the Cx (front) side in the faded state.

[0067] Tv_cc_DS - Visual transmittance observed / measured from the Cc (back) side in the dark state.

[0068] Tv_cx_DS - Visual transmittance observed / measured from the Cx (front) side in the dark state.

[0069] Rv_cc_FS - Visual reflectance measured only on the Cc side in the faded state.

[0070] Rv_cx_FS - Visual reflectance measured only on the Cx side in the faded state.

[0071] Rv_cc_DS - Visual reflectance of only the Cc side measured in the dark state.

[0072] Rv_cx_DS - Visual reflectance of only the Cx side measured in the dark state.

[0073] Rv_t_cc_FS - Total visual reflectance: Reflectance of both sides observed / measured from the Cc (back) side in the faded state.

[0074] Rv_t_cx_FS - Total visual reflectance: Reflectance of both sides observed / measured from the Cx (front) side in the faded state.

[0075] Rv_t_cc_DS - Total visual reflectance: Reflectance of both sides observed / measured from the Cc (back) side in the dark state.

[0076] Rv_t_cx_DS - Total visual reflectance: Reflectance of both sides observed / measured from the Cx (front) side in the dark state.

[0077] General available features of the lens according to the invention:

[0078] Thermoplastic materials that can be used for organic substrates can be selected, for example, from: polyamides; polyimides; polysulfones; polycarbonates and their copolymers; poly(ethylene terephthalate) and polymethyl methacrylate (PMMA). As used herein, polycarbonate (PC) is intended to mean homopolycarbonate or copolycarbonate and block copolycarbonate.

[0079] Thermosetting materials that can be used for substrates can be selected, for example, from: cycloolefin copolymers, such as ethylene / norbornene or ethylene / cyclopentadiene copolymers; homopolymers and copolymers of allyl carbonates of straight-chain or branched aliphatic or aromatic polyols, such as the homopolymer of diethylene glycol bis(allyl carbonate) (CR ) ; homopolymers and copolymers of (meth)acrylic acid and its esters that can be derived from bisphenol A; polymers and copolymers of thio(meth)acrylic acid and its esters, polymers and copolymers that can be derived from bisphenol A or phthalic acid and allyl esters of aromatic hydrocarbons such as styrene, polymers and copolymers of urethane and thiourethane, polymers and copolymers of epoxy resins, and polymers and copolymers of sulfides, disulfides, and episulfides, and combinations thereof.

[0080] Preferably, the homopolymer of diethylene glycol bis(allyl carbonate) (CR ) and allyl and (meth)acrylic acid copolymers (refractive index between 1.54 and 1.58).

[0081] As used herein, (co)polymer is intended to mean copolymer or polymer. As used herein, (meth)acrylate is intended to mean acrylate or methacrylate.

[0082] Particularly recommended substrates include those obtained by (co)polymerization of diethylene glycol bis allyl carbonate (e.g., sold under the trade name by PPG Industries) ( lenses, Essilor), or polythiourethane / polysulfide (e.g., sold by Mitsui in the MR series), or allyl and (meth)acrylic acid copolymer (refractive index between 1.54 and 1.58).

[0083] Before depositing a multilayer interference coating onto an optional coated substrate (e.g., having an anti-wear layer and / or anti-scratch coating or having sub-layers), the surface of the optional coated substrate is typically subjected to physical or chemical surface activation treatment to enhance the adhesion of the anti-reflection coating. This pretreatment is usually carried out under vacuum. This pretreatment can be bombardment with high-energy and / or reactive components, such as by ion beam ("ion pre-cleaning" or "IPC") or by electron beam, corona discharge treatment, ion spallation treatment, ultraviolet radiation treatment, or plasma-mediated treatment under vacuum (usually using oxygen or argon plasma). This pretreatment can also be acidic or alkaline treatment and / or solvent-based treatment (water, hydrogen peroxide, or any organic solvent).

[0084] The multilayer interference coating can be deposited onto a sub-layer, which does not belong to the multilayer interference coating.

[0085] Due to its relatively high thickness, the sub-layer usually does not participate in the optical activity of the multilayer interference coating, especially when its refractive index is close to that of the underlying coating (usually the anti-wear and anti-scratch coating), or if the sub-layer is directly deposited onto the substrate, when its refractive index is close to that of the substrate.

[0086] The thickness of the sub-layer should be sufficient to enhance the anti-wear property of the multilayer interference coating, but preferably not to an extent that would cause light absorption, which may significantly reduce the relative transmission coefficient τ v . The thickness of this sub-layer is usually less than 300 nm, more preferably less than 200 nm, and usually greater than 90 nm, more preferably greater than 100 nm.

[0087] The sub-layer is preferably based on SiO 2a layer which preferably comprises at least 80% by weight, more preferably at least 90% by weight, and even more preferably consists of a silica layer, based on the total weight of the layer. The thickness of such a silica-based layer is generally less than 300 nm, more preferably less than 200 nm, and generally more than 90 nm, more preferably more than 100 nm.

[0088] The ophthalmic lens of the present invention may comprise an additional antistatic layer to not retain and / or not form a large amount of static charge by incorporating at least one charge dissipating conductive layer into the stack present on the lens surface.

[0089] The ability of a glass lens to empty the static charge obtained after rubbing it with a cloth or using any other procedure that generates static charge (charge applied by corona, etc.) can be quantified by measuring the time required for the dissipation of said charge. Thus, an antistatic glass lens has a discharge time of about a few hundred milliseconds, preferably 500 ms or less, while an electrostatic glass lens is about a few tens of seconds. In the present application, the discharge time is measured according to the method disclosed in French application FR 2 943 798.

[0090] As used herein, a "conductive layer" or an "antistatic layer" is intended to mean a layer that, due to its presence on the surface of a non-antistatic substrate (i.e., having a discharge time greater than 500 ms), is capable of having a discharge time of 500 ms or less after applying a static charge on its surface.

[0091] The conductive layer may be located at different positions in the stack, generally in or in contact with the interference coating, provided that its properties are not affected. The conductive layer is preferably located between two layers of the interference coating and / or adjacent to the layer of the interference coating having a high refractive index. Preferably, the conductive layer is directly located below the layer of the interference coating having a low refractive index, and most preferably is the penultimate layer of the interference coating (directly below the silica-based outer layer of the interference coating).

[0092] Generally, the front main surface and / or the rear main surface of the substrate on which the multi-layer interference coating will be deposited is coated with an impact-resistant primer layer, an anti-wear coating and / or an anti-scratch coating or an impact-resistant primer layer coated with an anti-wear coating and / or an anti-scratch coating.

[0093] The anti-wear coating and / or the anti-scratch coating is preferably a hard coating based on poly(meth)acrylate or silane, and these hard coatings generally comprise one or more mineral fillers, which are intended to increase the hardness and / or refractive index of the coating once cured. The hard anti-wear coating and / or anti-scratch coating is preferably prepared from a composition comprising at least one alkoxysilane and / or its hydrolysis product, which hydrolysis product is obtained, for example, by hydrolysis with a hydrochloric acid solution and an optional condensation and / or curing catalyst.

[0094] The antiwear coating and / or the anti-scratch coating composition can be deposited onto the main face of the substrate by dip coating or spin coating. It is then cured by a suitable method (preferably using heat or ultraviolet radiation). The thickness of the antiwear coating and / or the anti-scratch coating generally varies from 2 μm to 10 μm, preferably from 3 μm to 5 μm.

[0095] Before depositing the antiwear coating and / or the anti-scratch coating, a primer coating can be applied to the substrate to improve the impact resistance and / or adhesion of the subsequent layers in the final product.

[0096] The ophthalmic lens according to the invention can also comprise a coating formed on the multilayer interference coating and capable of modifying its surface properties, such as a hydrophobic coating and / or an oleophobic coating (antifouling top coating). These coatings are preferably deposited onto the outer layer of the multilayer interference coating, especially when the outer layer of the multilayer interference coating is based on silica. Generally, the thickness of these coatings is less than or equal to 10 nm, preferably in the range from 1 nm to 10 nm, more preferably from 1 nm to 5 nm.

[0097] Instead of a hydrophobic coating, a hydrophilic coating providing anti-fogging properties, or an anti-fogging precursor coating providing anti-fogging properties when associated with a surfactant, can be used. Examples of such anti-fogging precursor coatings are described in the patent application WO2011 / 080472.

[0098] Reference Figure 1 , in the faded (i.e., transparent) state, the photochromic lens behaves as a transparent lens with negligible absorbance.

[0099] The visual transmittance Tv measured from the front (Cx) side or the back (Cc) side of the lens is always equal for any corresponding angle of incidence (AOI):

[0100] Tv_cc_FS = Tv_cx_FS.

[0101] If an antireflection (AR) coating with negligible absorbance is applied to the lens (usually on both sides), it will reduce the reflections for the wearer of the lens (from the back side or Cc side) and for the observer (from the front side or Cx side).

[0102] In this case, the total visual reflectance perceived by the wearer (from the back side) and the observer (from the front side), measured from the Cc side or the Cx side respectively, will be the same:

[0103] Rv_t_cc_FS = Rv_t_cx_FS, and it should have:

[0104] ● Rv_t_cc_FS ~ Rv_Cc_FS + Rv_Cx_FS

[0105] ●Rv_t_cx_FS to Rv_Cx_FS + Rv_Cc_FS

[0106] This is the desired feature for improving the transparency (visual transmittance) of the lens.

[0107] In this case, the total visual reflectance Rv_t_cc_FS or Rv_t_cx_FS ranges from approximately 1% to 5% and depends on the specific anti-reflective coating applied.

[0108] Reference Figure 2 , in the dark (i.e., activated) state, the photochromic layer should be activated and absorb the light passing through the lens. Due to the absorption of the photochromic layer, the total reflectance in the dark state is reduced.

[0109] The visual transmittance Tv measured from the front (Cx) side or the back (Cc) side is always equal for any corresponding angle of incidence (AOI):

[0110] Tv_t_cc_DS = Tv_t_cx_DS

[0111] The total visual reflectance Rv_t_cx_DS observed / measured from the Cx (front) side in the dark state will be mainly determined by the visual reflectance Rv_Cx_DS (only the Cx side):

[0112] ●Rv_t_cx_DS to Rv_Cx_DS.

[0113] The total visual reflectance Rv_t_cc_DS observed / measured from the Cc (back) side in the dark state will be mainly determined by the visual reflectance Rv_Cc_DS (only the Cc side):

[0114] ●Rv_t_cc_DS to Rv_Cc_DS.

[0115] If a mirror effect is required in the dark state as in the case of the present invention, it seems that a standard ordinary anti-reflective coating (AR) would be insufficient, and increasing the reflection from the front side of the lens to increase this mirror effect would undesirably increase the reflection for the wearer in the faded state, which is unacceptable for the wearer due to the desired AR performance.

[0116] The following examples illustrate the present invention in a more detailed but non-limiting manner.

[0117] Example

[0118] All the tested comparative lenses C1 - C3 and the lenses L1 - L8 according to the present invention were fabricated as follows:

[0119] - Organic lens substrate, based on polycarbonate (PC) and known as PC Transitions T7 (Grey), Ct = 2 mm,

[0120] - Hard coating (V): Mithril 1.6,

[0121] - An interference stack (i.e., a multi-layer interference coating) on both the back and front sides of each lens (except for the comparison lens C1), where two absorption layers are respectively on the back side (Cc) and the front side (Cx) of the inventive lenses I1 - I4 (the inventive lenses L5 - L8 only include one front-side absorption layer), and both stacks are deposited by physical vapor deposition (PVD), using the following PVD evaporation material abbreviations (all refractive indices of the materials are available):

[0122] P: PC T7 substrate

[0123] V: Hard coating of Mithril 1.6

[0124] Q: SiO 2 (Refractive index less than 1.55)

[0125] Z: ZrO 2 (Refractive index greater than 1.55)

[0126] I: Absorption layer of ITO (antistatic, refractive index greater than 1.55)

[0127] T: Ta 2 O 5 (Refractive index greater than 1.55)

[0128] L: Lima 5 (refractive index less than 1.55)

[0129] U: SiO 2 + Inert O 2 (Refractive index less than 1.55)

[0130] G: Absorption layer "Grey A" (a mixture of metal and dielectric from UMICORE).

[0131] The calculation / measurement environment used is as follows:

[0132] - Light source: D65 - Observer: Light adapted,

[0133] - R v is measured for lenses C1 - C3 and L1 - L2 for AOI Cc = 35° (angle of incidence on the concave back side for the wearer) and for AOI Cx = 15° (angle of incidence on the convex front side for the observer), and also for lenses L3 - L8 for AOI Cc = 15° and AOI Cx = 35°,

[0134] -R m is measured for the lenses L3 - L8 for AOI Cc = 15° and 35° and for AOI Cx = 15° and 35°, and

[0135] -T v is measured under D65 illumination conditions (daylight: AOI = 0, 15° or 35°),

[0136] In the following examples of the test lenses C1 - C3 and L1 - L8, the materials used and the corresponding thicknesses (in nanometers (nm)) are given in the direction from the back side (Cc) to the front side (Cx) of each lens, and the optical properties of these test lenses are listed in the following table.

[0137] 1. First series of examples including three comparative lenses C1 - C3 of the prior art and two lenses L1 - L2 of the present invention: Examples:

[0138] Comparative lens C1:

[0139] A conventional lens PCT7 Mi1.5 that has only a substrate (P: PC T7) and a hard coating (V: Mi1.5) and no interference stack applied, see the following structure with thickness (in nanometers):

[0140] Back side - 4500V - P - 4500V - Front side.

[0141] Comparative lens C2:

[0142] A conventional lens PC T7 Mi1.6 MC3h that has a substrate (P: PC T7), a hard coating (V: Mi1.6), and interference stacks (MC3h) applied on both sides, see the following structure with thickness (in nanometers):

[0143] Back side - 91.6Q 62.9Z 16.2Q 37.6Z 4500V - P - 4500V 37.6Z 16.2Q 62.9Z 91.6Q - Front side.

[0144] Comparative lens C3:

[0145] A conventional lens PC T7 Mi1.6 BlueS0 - BlueS2 that has a substrate (P: PC T7), a hard coating (V: Mi1.6), an interference stack BlueS0 applied on the back (Cc) side, and an interference stack BlueS2 applied on the front (Cx) side, see the following structure with thickness (in nanometers):

[0146] Dorsal - 89.52Q 7.34I 79.05Z 23.48Q 20.62Z 148.87U 5.93Z 57.09Q 4500V - P - 4500V 20.6Z 135.8U 23.7Z 34.7Q 65.9Z 6.5I 81.6Q - Frontal side.

[0147] Inventive lens I1:

[0148] A lens having a substrate (P: PC T7), a hard coating (V: Mi1.6), a 5 - layer interference stack ASY v1 s09 cc applied on the dorsal (Cc) side, and a 7 - layer interference stack ASY v1 s09 cx applied on the frontal (Cx) side, see the following structure with thickness (in nanometers):

[0149] Dorsal - 98.891Q 79.263Z 14.494Q 8.291I 7.098Z 4500V - P - 4500V 53.553Z45.775I 65.337Q 10.713Z 110.72Q 110.13Z 98.476Q - Frontal side.

[0150] Therefore, L1 includes a front absorption layer (I) and a rear absorption layer (I).

[0151] Inventive lens L2:

[0152] A lens having a substrate (P: PC T7), a hard coating (V: Mi1.6), a 5 - layer interference stack ASY v4 s05 cc applied on the dorsal (Cc) side, and a 7 - layer interference stack ASY v4 s05 cx applied on the frontal (Cx) side, see the following structure with thickness (in nanometers):

[0153] Dorsal - 89.508Q 78.72Z 19.553Q 1.729I 15.83Z 4500V - P - 4500V 51.289Z14.047G 76.252Q 9.862Z 111.728Q 114.892Z 83.474Q - Frontal side.

[0154] Therefore, L2 includes a front absorption layer (G) and a rear absorption layer (I).

[0155] Table 1 below lists seven parameter values measured for lenses C1 - C3 and L1 - L2. The values shown in bold mean the limit values that meet the corresponding standards. In contrast, the values shown in italics indicate that those standards are not met. These seven parameters are:

[0156] 1. The visual transmittance should be >81%, preferably >85% at 0° AOI (CAT 0) in the faded state.

[0157] 2. The visual transmittance should be >8% at 0° AOI (CAT 3) in the dark state.

[0158] 3. Rv_t_cx_FS - The total visual reflectance measured at 0° from the Cx (front) side in the faded state, no requirement.

[0159] 4. Rv_t_cc_FS - The total visual reflectance measured from the Cc (back) side in the faded state should be <5.0%, preferably <2.5% at 35° AOI.

[0160] 5. Rv_t_cx_DS - The total visual reflectance measured from the Cx (front) side in the dark state should be >2.5%, preferably >5.0% at 15° AOI.

[0161] 6. Rv_t_cc_DS - The total visual reflectance measured from the Cc (back) side in the dark state should be <1.5%, preferably <1.0% at 35° AOI.

[0162] 7. δRv_t_cx / cc_FS: The difference between the total visual reflectance measured from the front side and the total visual reflectance measured from the back side for the same lens, this difference is Rv_t_t_cx_FS - Rv_t_cc_FS: should be >1.0%, preferably >2.0% at AOI from 0° to 15°.

[0163] [Table 1]:

[0164]

[0165] 2. Second series of examples including six other lenses L3 - L8 of the present invention:

[0166] Inventive lens L3:

[0167] A lens having a substrate (P: PC T7), a hard coating (V: Mi1.6), a 5 - layer interference stack ASY v5 s02 cc applied on the back (Cc) side, and a 7 - layer interference stack ASY v5 s02 cx applied on the front (Cx) side, see the following structure with thickness (in nanometers):

[0168] Back side - 96.967L 95.497T 7.641L 30.224I 0T 4500V - 2P - 4500V 41.087Z 42.938I 66.888Q 12.96Z 113.216Q 112.502Z 92.483Q - Front side.

[0169] Therefore, L3 includes a front absorption layer (I) and a rear absorption layer (I).

[0170] Table 2 and 2a below list the Tv, Rv_t, δRv_ts, and other parameter values measured for lens L3, including Rm, hue h (°), and chromaticity C*, where "observer" and "wearer" refer to the front (Cx) side and the rear (Cc) side, respectively (the values shown in bold mean the limit values that meet the corresponding standards).

[0171] [Table 2]

[0172]

[0173] [Table 2a]

[0174]

[0175]

[0176] Invented lens L4:

[0177] A lens having a substrate (P: PC T7), a hard coating (V: Mi1.6), a 5-layer interference stack ASY v5 s07 cc applied on the back (Cc) side, and a 7-layer interference stack ASY v5 s07 cx applied on the front (Cx) side. See the following structure with thickness (in nanometers):

[0178] Back side - 92.539Q 6.382I 62.249Z 14.489Q 34.248Z 4500V - 2P - 4500V 43.74Z 17.237G 64.688L 16.527Z 105.746L 109.899Z 74.296Q - Front side.

[0179] Therefore, L4 includes a front absorption layer (G) and a rear absorption layer (I).

[0180] Table 3 and 3a below list the Tv, Rv_t, δRv_ts, and other parameter values measured for lens L4, including Rm, hue h (°), and chromaticity C*, where "observer" and "wearer" refer to the front (Cx) side and the rear (Cc) side, respectively (the values shown in bold mean the limit values that meet the corresponding standards).

[0181] [Table 3]

[0182]

[0183] [Table 3a]

[0184]

[0185] Invented lens L5:

[0186] A lens having a substrate (P: PC T7), a hard coating (V: Mi1.6), a 4 - layer interference stack ASY v6 s02 cc applied on the back (Cc) side, and a 5 - layer interference stack ASY v6 s02 cx applied on the front (Cx) side. See the following structure with thickness (in nanometers):

[0187] Back side - 88.803Q 83.51Z 22.15L 21.511Z 4500V - 2P - 4500V 84.965Z 17.41G 111.073L 111.045Z 59.398Q - Front side.

[0188] Therefore, L5 only includes the front absorption layer (G).

[0189] Table 4 and 4a below list the measured values of Tv, Rv_t, δRv_ts, and other parameter values for lens L5, including Rm, hue h (°), and chromaticity C*, where "observer" and "wearer" refer to the front (Cx) side and the back (Cc) side respectively (the values shown in bold mean the limit values that meet the corresponding standards).

[0190] [Table 4]

[0191]

[0192]

[0193] [Table 4a]

[0194]

[0195] Invented lens L6:

[0196] A lens having a substrate (P: PC T7), a hard coating (V: Mi1.6), a 4 - layer interference stack ASY v7v2 cc applied on the back (Cc) side, and a 6 - layer interference stack ASY v7v2 cx applied on the front (Cx) side. See the following structure with thickness (in nanometers):

[0197] Back side - 87.019Q 92.054Z 19.68L 15.442Z 4500V - 2P - 4500V 12.205G 89.078L 47.744Z 49.716L 132.202Z 72.328Q - Front side.

[0198] Therefore, L6 only includes the front absorption layer (G).

[0199] Table 5 and 5a below list the values of Tv, Rv_t, δRv_ts and other parameter values measured for lens L6, including Rm, hue h (°) and chromaticity C*, where "observer" and "wearer" refer to the front (Cx) side and the back (Cc) side respectively (the values shown in bold mean the limit values that meet the corresponding standards).

[0200] [Table 5]

[0201]

[0202]

[0203] [Table 5a]

[0204]

[0205] Inventive lens L7:

[0206] A lens having a substrate (P: PC T7), a hard coating (V: Mi1.6), a 4-layer interference stack ASYv8 s01 cc applied on the back (Cc) side, and a 3-layer interference stack ASY v8 s01 cx applied on the front (Cx) side. See the following structure with thickness (in nanometers):

[0207] Back side - 80.846Q 99.749Z 5.848Q 5Z 4500V - 2P - 4500V 13.262G 9.147Z 148.873Q - Front side.

[0208] Therefore, L7 only includes a front absorption layer (G).

[0209] Table 6 and 6a below list the values of Tv, Rv_t, δRv_ts and other parameter values measured for lens L7, including Rm, hue h (°) and chromaticity C*, where "observer" and "wearer" refer to the front (Cx) side and the back (Cc) side respectively (the values shown in bold mean the limit values that meet the corresponding standards).

[0210] [Table 6]

[0211]

[0212] [Table 6a]

[0213]

[0214] Inventive lens L8:

[0215] A lens having a substrate (P: PC T7), a hard coating (V: Mi1.6), a 4-layer interference stack ASYv8 s02 cc applied on the back (Cc) side, and a 3-layer interference stack ASY v8 s02 cx applied on the front (Cx) side, see the following structure with thickness (in nanometers):

[0216] Back side - 89.863Q 89.672Z 23.844Q 19.547Z 4500V - 2P - 4500V 11.581G 3Z166.571Q - Front side.

[0217] Therefore, L8 only includes the front absorption layer (G).

[0218] Tables 7 and 7a below list the measured values of Tv, Rv_t, δRv_ts, and other parameter values for the lens L8, including Rm, hue h (°), and chromaticity C*, where "observer" and "wearer" refer to the front (Cx) side and the back (Cc) side respectively (the values shown in bold mean the limit values that meet the corresponding standards).

[0219] [Table 7]

[0220]

[0221] [Table 7a]

[0222]

[0223] The conclusion drawn from the above results is that the ophthalmic lens according to the present invention appears to be able to meet the above-defined standards, which are related to the visual transmittance in the faded state and the dark state, the total visual reflectance in the faded state and the dark state, and the difference between the total visual reflectance measured from the front side and the total visual reflectance measured from the back side. Such an inventive lens can therefore advantageously be used as a photochromic or electrochromic antireflection lens for sunglasses, which has a front surface of the lens that provides a mirror effect for the observer.

Claims

1. An ophthalmic lens having a front surface and a rear surface, the front surface and the rear surface respectively defining a front side and a rear side of the ophthalmic lens, the ophthalmic lens being configured to exhibit a transparent state in which the ophthalmic lens has a visual transmittance greater than 81% in the visible region at an incident angle of 0°, the ophthalmic lens comprising: - a substrate having a front major surface and a rear major surface adjacent to the front surface and the rear surface respectively, and - at least one multilayer interference coating including a front multilayer interference coating disposed on the front major surface and including at least one absorption front layer in the visible region, wherein, in the transparent state, the total visual reflectance Rv_t_rear measured from the rear side at an incident angle of 35° in the visible region from both the rear surface and the front surface of the ophthalmic lens is less than 5.0%, and Wherein, in the transparent state, the total visual reflectance R v _t_front measured from the front side at an incident angle of 15° in the visible region from both the rear surface and the front surface and the total visual reflectance R v _t_rear measured from the rear side at an incident angle between 0 and 15° in the visible region from both the rear surface and the front surface, the difference R v _t_front - R v _t_rear is greater than 1.0%.

2. The ophthalmic lens according to claim 1, wherein, the at least one absorption front layer has an absorption rate greater than 3% in the visible region.

3. The ophthalmic lens according to claim 1, wherein, the at least one absorption front layer is composed of at least one metal or metal oxide.

4. The ophthalmic lens according to claim 1, wherein, the at least one multilayer interference coating further includes a rear multilayer interference coating disposed on the rear major surface and including at least one absorption rear layer in the visible region.

5. The ophthalmic lens according to claim 1, wherein, in the transparent state, the ophthalmic lens has a visual transmittance greater than or equal to 85% in the visible region at an incident angle of 0°.

6. The ophthalmic lens according to claim 1, wherein, The ophthalmic lens is further configured to exhibit at least one darker state, in which the ophthalmic lens has a visual transmittance in the visible region between 8% and 80% at an angle of incidence of 0°, and wherein the at least one multilayer interference coating forms a visible reflective coating on the front surface in the at least one darker state, and the visible reflective coating is defined by a total visual reflectance R v _t_front measured from the front side at an angle of incidence of 15° in the visible region from both the rear surface and the front surface of the ophthalmic lens, and the total visual reflectance is greater than 2.5%.

7. The ophthalmic lens according to claim 6, wherein, in the at least one darker state, the ophthalmic lens has a visual transmittance between 8% and 43% in the visible region at an incident angle of 0°.

8. The ophthalmic lens according to claim 6, wherein, In the at least one darker state, the total visual reflectance R v _t_front of the ophthalmic lens from both the rear surface and the front surface in the visible region, measured from the front side at an incident angle of 15°, is equal to or greater than 4.0%.

9. The ophthalmic lens according to claim 6, wherein, the ophthalmic lens satisfies at least one of the following conditions: - In the transparent state, the total visual reflectance R v _t_rear measured from the rear side at an incident angle of 35° in the visible region from both the rear surface and the front surface of the ophthalmic lens is less than 2.5%; and - the difference Rv_t_front - Rv_t_rear between the total visual reflectance Rv_t_front measured from the front side at an incident angle of 15° in the visible region from both the rear surface and the front surface and the total visual reflectance Rv_t_rear measured from the rear side at incident angles between 0 and 15° in the visible region from both the rear surface and the front surface is greater than 2.0%. - Rv_t_rear 10. The ophthalmic lens according to claim 6, wherein, In the at least one darker state, the total visual reflectance R v _t_rear of the ophthalmic lens from both the rear surface and the front surface in the visible region, measured from the rear side at an angle of incidence of 35°, is less than 1.5%.

11. The ophthalmic lens according to claim 6, wherein, the at least one multilayer interference coating is disposed on a hard coating covering an organic support and includes an alternation of at least one high refractive index layer unit having a refractive index greater than 1.55 and at least one low refractive index layer unit having a refractive index lower than 1.

55.

12. The ophthalmic lens according to claim 6, Wherein, the at least one multi-layer interference coating further includes a rear multi-layer interference coating, the rear multi-layer interference coating being on the main front surface and including at least one absorption rear layer in the visible region, and wherein the front multi-layer interference coating has a thickness of less than 550 nm and the rear multi-layer interference coating has a thickness of less than 250 nm.

13. The ophthalmic lens according to claim 6, Wherein, the ophthalmic lens is configured to exhibit the transparent state and the at least one darker state by means of the substrate, the substrate being photochromic or electrochromic.

14. The ophthalmic lens according to claim 6, Wherein, the ophthalmic lens is configured to form a sunglass lens having a front surface of the lens in the at least one darker state.

15. The ophthalmic lens according to claim 1, Wherein, in the ophthalmic lens, the front surface is a convex surface and the rear surface is a concave surface or a convex surface.

16. The ophthalmic lens according to claim 4, Wherein, the at least one absorption rear layer is composed of at least one metal or metal oxide.

17. The ophthalmic lens according to claim 7, Wherein, in the at least one darker state, the ophthalmic lens has a visual transmittance in the visible region between 8% and 20% at an incident angle of 0°.

18. The ophthalmic lens according to claim 8, Wherein, In the at least one darker state, the total visual reflectance R v _t_front measured from the front side at an incident angle of 15° in the visible region from both the rear surface and the front surface of the ophthalmic lens is equal to or greater than 5.0%.

19. The ophthalmic lens according to claim 10, Wherein, In the at least one darker state, the total visual reflectance R v _t_rear of the ophthalmic lens from both the rear surface and the front surface in the visible region, measured from the rear side at an angle of incidence of 35°, is less than 1.0%.

20. The ophthalmic lens according to claim 11, Wherein, The at least one high refractive index stratified unit is selected from ZrO 2 , TIO 2 , ITO, SnO 2 and Ta 2 O 5 , and the at least one low refractive index stratified unit is selected from SiO 2 , L5, MgO and MgF 2 , and the at least one multi-layer interference coating has a total thickness of less than 800 nm.

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