LIGHT-ABSORBENT GLAZING

Abstract

The present invention relates to a luminous glazing comprising: - a first substrate coated with a functional coating, said substrate having two faces and an edge; - a light source comprising an emitting surface, optically coupled with the substrate such that the light enters the substrate through an entrance face and the substrate forms a light guide; - a light extracting element for extracting the light and forming a luminous pattern; the glazing being characterized in that it comprises at least one light polarizer located between the emitting surface of the light source and the light entry face in the substrate.

Description

Title of the invention: LIGHT-ABSORBENT GLAZING TECHNICAL FIELD OF THE INVENTION

[0001] The technical field of the invention is that of luminous or illuminating glazing. Luminous glazing is glazing that emits light. It comprises a light source and a substrate having, on one of its principal faces, a light-extracting element such as a diffusing layer forming a pattern. The light source is optically coupled to the substrate, for example, edge-on. The light injected at the edge of the substrate propagates within the substrate by total internal reflection. The substrate acts as a light guide. This is therefore referred to as the "guided mode."

[0002] The invention finds a particularly advantageous application in the production of glazing for vehicles or buildings. INTRODUCTION

[0003] According to the present invention, the mode of light propagation within the substrate by total internal reflection is called the "guided mode." The guided mode thus corresponds to the use of light at grazing incidence within a substrate. The critical parameter for the guided mode is the critical angle of total internal reflection. This corresponds to the angle with respect to the normal to the substrate above which any light ray arriving at a separating surface or interface, from a medium with a higher refractive index to a medium with a lower refractive index, is totally reflected by said surface or interface. The critical angle (0c) is determined by applying Snell's law. It corresponds to the angle (within the substrate) for which the light ray is refracted at 90° (into the medium with a lower refractive index than the substrate).

[0004] For luminous glazing, the surrounding medium can be air, another substrate, or a polymer interlayer. For example, the critical angle of total internal reflection at the interface between a glass substrate with a refractive index of 1.51 and air is approximately 40°. In the case of a glass / polyvinyl butyral (PVB) polymer interlayer interface, the critical angle is approximately 80°.

[0005] All light rays injected into the substrate having an angle of incidence: - above this critical angle are reflected and continue to propagate in the substrate, - below this critical angle, they are partially refracted and gradually exit the substrate.

[0006] In the case of luminous glazing, the light sources used are preferably inorganic light-emitting diodes (LEDs, as opposed to OLEDs). The light is extracted at the level of the extraction layer. which allows a luminous pattern to be formed. TECHNOLOGICAL BACKGROUND OF THE INVENTION

[0007] It is known to integrate inorganic light-emitting diodes, also called LEDs, at the edge of single or laminated glass panes, so that the light emitted by the diodes enters through the edge of a sheet of glass and is guided by it to a diffusing element, also called a light-extracting layer. Reference may be made to patent application WO2010049638.

[0008] These luminous glazings essentially serve an ambient lighting or signaling function, which is achieved with low-power diodes. The luminous efficacy of such edge-lit glazings is generally limited due to light losses caused by light absorption by the glass acting as a waveguide and / or the materials in its vicinity.

[0009] It is also known, particularly from documents WO 2013 / 110885 and WO 2018 / 178591, to drill a hole in the glass sheet and place the diodes therein. This hole is made close to the extraction means, specifically so as to shorten the optical path traveled by the light between the diodes and the extraction means. This makes it possible to reduce losses due to light absorption.

[0010] The light emitted by the diodes is injected into the glass sheet through an additional slice formed by the hole. The light then bounces between the two main faces of the glass sheet until it reaches the extraction element.

[0011] These luminous glazings do not include a functional coating (low emissivity, solar control or absorption).

[0012] There are many applications where the glazing has a functional coating. In the following description, the term "functional" qualifying a coating or layer means "capable of acting on solar radiation and / or infrared radiation".

[0013] This may be a coating with a low-emissivity, absorbing, or solar control function.

[0014] The "low-emissivity" function or property refers to the ability of glazing to prevent heat loss by reflecting infrared radiation. To this end, functional coatings with infrared (IR) radiation reflection properties are used.

[0015] The "solar control" function or property corresponds to the ability of glazing to reduce heat gain due to solar radiation, while maximizing the amount of visible light entering the glazing. This ability is also achieved by adding a functional coating to the glazing that reflects infrared radiation, based on the same principle as the low-emissivity function.

[0016] Glazing with a functional coating is used both for automotive applications, for example for car roofs, and for building applications.

[0017] There is a growing demand for luminous glazing. This can be single, double or laminated glazing.

[0018] As a coating capable of acting on solar radiation, we can also mention functional coatings comprising a layer absorbing in the visible.

[0019] As an example of an IR-reflecting functional coating, functional coatings comprising a conductive oxide layer disposed between two dielectric coatings may be cited, as described in patent application WO2018 / 206236. This application discloses, starting from the substrate, functional coatings comprising:

[0020] - a dielectric coating comprising dielectric layers such as layers of silicon nitride and / or silicon oxide, - a functional layer based on a transparent conductive oxide (TCO) such as an indium tin oxide (ITO) layer, - a dielectric coating comprising dielectric layers such as silicon nitride and silicon oxide layers.

[0021] The absorption of visible light by the conductive oxide-based functional layers of these functional coatings is significant, particularly in the red region. However, the absorption of visible light at normal incidence remains low because the light passes perpendicularly through the conductive oxide-based functional layer. The interaction between the radiation and the functional layer occurs only along the thickness of the functional layer.

[0022] The situation is different for light in guided mode. As explained above, "guided mode" refers to the mode of light propagation in the substrate by total internal reflection.

[0023] When functional coatings are placed close to the substrate in which guided-mode light propagates, the light propagating in the substrate is likely to interact with the functional layer. The interaction angles between the guided-mode light and the substrate are defined directly within the substrate into which the light is injected. The guided-mode rays are therefore largely grazing (0° greater than 80°) with respect to the normal to the substrate in which they propagate.

[0024] A ray of the guided mode therefore traverses the functional layer over a distance corresponding to: Thickness of the functional layer (ef) / cos (0). The more grazing the angle, the smaller cos (0), the greater the distance the rays of the guided mode interact with the functional layer, and therefore the greater the proportion of rays absorbed are also important.

[0025] In conclusion, when the substrate in which the light propagates includes or is in contact with a functional coating, a significant part of the light comes into contact with this functional coating at a grazing angle and is therefore likely to be absorbed when the functional coating includes absorbing layers.

[0026] This is why, depending on the injected light, we observe an alteration, a chromatic change, a decrease or even an erasure of the pattern as we move away from the point of light injection due to the high absorption in guided mode at grazing angles of the functional layer.

[0027] This problem is particularly pronounced at long wavelengths in the visible spectrum because absorption by conductive oxide layers, and in particular by ITO, increases with wavelength. Therefore, in the case of luminous glazing, the guided-mode optical properties of the functional coating are crucial.

[0028] This phenomenon is not limited to functional coatings comprising conductive oxide layers but can also occur for other functional coatings, such as absorbent or solar control coatings.

[0029] When using light sources emitting red light (red LEDs), guided-mode absorption of wavelengths corresponding to red results in a color (or brightness) that diminishes along the pattern (as one moves away from the light source). When using light sources emitting white light, guided-mode absorption of wavelengths corresponding to red results in a color that changes and a light intensity that diminishes along the pattern. Summary of the invention

[0030] The present invention aims to remedy at least one of the drawbacks that have just been mentioned.

[0031] According to the invention this goal is achieved by providing a luminous glazing comprising: - a first substrate coated with a functional coating (5), said substrate comprising two faces and an edge (8); - a light source (7) comprising an emitting surface, optically coupled with the substrate such that the light enters the substrate through an entrance face and the substrate forms a light guide;

[0032] - a light-extracting element (6) for extracting light and forming a pattern luminous;

[0033] the glazing being characterized in that it comprises at least one light polarizer located between the emitting surface of the light source (7) and the light entry face in the substrate.

[0034] This is therefore the guided mode in which the light injected into the substrate propagates in the substrate by total internal reflection, forming a beam of guided light.

[0035] A polarizer is an optical instrument well known to those skilled in the art. It filters a preferred polarization direction in an incident light wave. The polarizer is available, for example, in the form of a semi-transparent plastic film or sheet. Polarizers are available on the market, for example, from brands such as Techspec or 3M.

[0036] In the context of the invention, the term "transparent" means that the light transmission in the visible spectrum is greater than 50%. However, in applications where visibility through the glazing is not a determining factor, the light transmission may be much lower, for example, greater than 5%.

[0037] Throughout the description and in the claims, "substantially orthogonal" means an angle between 85° and 95°.

[0038] According to one embodiment of the invention, the light entry face in the substrate is the slice (8) of the substrate.

[0039] According to another embodiment of the invention, the substrate has a hole and the light entry face in the substrate is a wall delimiting the hole.

[0040] Preferably, the light source (7) is an inorganic light-emitting diode (LED).

[0041] In the illuminating glazing of the present invention, preferably, a large number of diodes, for example at least three, preferably at least five and more preferably at least ten diodes are placed opposite the light entry face(s) of the waveguide.

[0042] The inlet face can be: - spaced from the polarizer, in particular by several centimeters, at most 10 mm, at most 5 mm or at most 1 mm, or - in optical contact with the polarizer by means of an adhesive or - in physical contact with the polarizer.

[0043] The polarizer can be: - spaced from the light-emitting surface, in particular by several centimeters, at most 10 mm, at most 5 mm or at most 1 mm, or - in optical contact with the emitting surface, by means of an adhesive or - in physical contact with the emitting surface.

[0044] According to preferred modes of the invention, the polarizer (9) is glued to the emitting surface of the light source (7) or glued to the light entry face in the substrate.

[0045] According to a preferred embodiment of the invention, the substrate is coated with a re low-emissivity functional clothing (5), in particular having a transparent conductive oxide layer. Such conductive layers are known as TCOs (transparent conductive oxide), they can be composed of mixed indium tin oxide (ITO), fluorine-doped tin oxide or antimony-doped tin oxide.

[0046] According to one embodiment of the invention, the polarizer is of type S.

[0047] According to another embodiment of the invention, the polarizer is of type P.

[0048] The type of polarizer, S or P, must be chosen according to the coating present on the substrate.

[0049] According to a particular embodiment, the coating has low emissivity properties, for example a coating comprising a TCO layer and the polarizer is of type S.

[0050] According to one embodiment, the luminous glazing is a single glazing.

[0051] According to a preferred embodiment of the invention, the luminous glazing is a laminated glazing. It further comprises a second substrate (10, 20) and a lamination interlayer (30), in particular of PVB, arranged between the two substrates to form a laminated glazing, the different faces of the substrates being numbered from 1 to 4 from the outside to the inside of the passenger compartment or building.

[0052] Conventionally, the faces of a glazing are designated from the outside by numbering the surfaces of the substrates from the outside towards the inside of the passenger compartment or room it equips. This means that the incident sunlight passes through the surfaces in ascending order of their number.

[0053] In the case of laminated glazing, all the faces of the substrates are numbered from 1 to 4, but the faces of the lamination interlayers are not numbered. The first coated substrate (10) is located further inside the building or the passenger compartment than the second substrate.

[0054] In the case of laminated glazing according to the invention, it comprises a face 1 located on the outside of the building or vehicle it equips, faces 2 and 3 in contact with the lamination interlayer, and a face 4 on the inside of the building or vehicle. The functional coating is preferably positioned on face 4.

[0055] The extractor element (6) is preferably disposed on face 3 or 4, even more preferably on face 3.

[0056] In the case of laminated glazing according to the invention, the light entry face into the substrate (10) is preferably the edge (8) of the substrate coated with the functional coating (5).

[0057] According to another embodiment of the invention, the glazing further comprises a second glass substrate, separated from the first by a gas layer so as to form a double glazing.

[0058] The invention also relates to: - a luminous glazing according to the invention mounted on a vehicle or on a building, and - the use of luminous glazing according to the invention as low-emissivity glazing for the building or vehicles, - a building, a vehicle comprising luminous glazing according to the invention.

[0059] The luminous glazing according to the invention is preferably automotive glazing such as automotive roof glazing. The luminous glazing of the invention can be selected from a side window, a rear window, a roof window or a windshield.

[0060] The light source can be linear, such as a strip of diodes.

[0061] The light source can be coupled directly to the substrate material or via a guide, a collimation optic.

[0062] The light source is preferably optically coupled to the substrate of the material according to the invention. The optical coupling can be achieved: - by the slice of the substrate of the material of the invention, - by a wall delimiting a hole, preferably through, in the substrate of the material, or - by redirecting light for example, the source can be on the F4 side (offset or opposite the F4 face) and a light redirecting element such as a prismatic reflector film is positioned on the F3 face.

[0063] The light source capable of emitting light is preferably an electroluminescent element such as light-emitting diodes (LEDs).

[0064] The light source can be polychromatic (white light) or monochromatic, in particular red.

[0065] According to the invention, when a polarizer is used, the power of the light source located opposite the polarizer is reduced, in particular by almost a factor of 2. To compensate for this power loss, several options are possible. One option is to double the number of light-emitting diodes used.

[0066] White light-emitting diodes are generally obtained by combining three LEDs of primary colors: red + green + blue. According to the invention, it would be possible to manufacture "white" LED lamps comprising twice as many LEDs of the color absorbed in guided mode and to place polarizers only with respect to those LEDs exhibiting the color absorbed in guided mode. For example, in the case of a functional coating based on a conductive oxide that absorbs in the red in guided mode, the number of red diodes could be doubled and each coupled to a polarizer.

[0067] The light source may be located opposite or near the edges of the substrate to be coupled by the substrate edge. See patent application WO2010049638.

[0068] The light source can also be placed in a hole made in the glazing (circular or oblong). Reference may be made to patent applications WO2013110885 and WO2018178591.

[0069] The light source may be located nearby, for example on face 4 (offset or opposite face 4), and a light redirection element such as a prismatic reflector film is positioned to redirect the light (for example on face 3). See patent application WO2022096365.

[0070] Several light sources can be used, for example near opposite edges of the substrate.

[0071] The diode(s) may be front-emitting (“top-emitting LED”) or side-emitting (“side-emitting LED”).

[0072] The diode(s) are preferably on a diode support such as an electronic circuit board, for example a printed circuit board (PCB for "Printed Circuit Board")

[0073] The diode support is preferably common to several diodes. The diode support may be opaque, for example by being coated with a layer of varnish or paint, and may even obscure the diodes. It may comprise a substrate made of a plastic material.

[0074] When the light-entry face of the substrate is the wall of a hole, the diode holder for side-emitting diodes can follow the general shape of the hole and have a main face fixed to the bottom of the hole, either directly or indirectly, for example via a mounting bracket. The diode holder common to several side-emitting diodes can be a disc (or oblong) or a ring within the circular (or oblong) hole.

[0075] According to one embodiment, the diodes are powered by means of a current supply integrated into the laminated glazing. For example, an electrical wire can be incorporated into the laminate interlayer.

[0076] The substrates may be mineral glass or transparent polymer material. The substrates are preferably mineral glass.

[0077] The mineral glass substrates that constitute the glazing can be made of soda-lime glass, aluminosilicate or borosilicate.

[0078] The substrates may be made of transparent polymer material which include poly(methyl methacrylate) (PMMA), polycarbonate (PC), polyurethane or polyurea (PU) or poly(ethylene terephthalate) (PET) substrates.

[0079] Preferably, the first substrate is colorless soda-lime mineral glass such as clear or extra-clear glass like Planiclear® marketed by the Applicant. In the case of single glazing, the first substrate is preferably made of glass and has a thickness preferably between 1 mm and 6 mm. In the case of laminated glazing, the thickness of the first substrate, preferably made of glass, is preferably between 0.6 mm and 3.2 mm, and more preferably between 1.4 mm and 2.2 mm.

[0080] The second substrate can of course be as transparent and colorless as the first substrate. According to a particular embodiment, a laminated glazing according to the invention consists of two colorless Planiclear® substrates.

[0081] According to another embodiment, the second substrate is made of tinted glass, for example, tinted glass having a light absorption greater than 10%, such as Venus®, TSA3+ or TSA4+, also marketed by the Applicant. The second substrate preferably has a thickness between 1.4 mm and 2.1 mm.

[0082] The luminous glazing according to the invention can be curved.

[0083] Preferably, the lamination interlayers comprise one or more sheets of organic polymers.Organic polymers are selected from polyvinyl butyral (PVB), polyurethanes (PU), polyureas, ethylene vinyl acetate (EVA), polyolefins (including polyethylene (PE), polypropylene (PP), and polyisobutylene (P-IB)), polyvinyl chloride and its derivatives (e.g., poly(vinyl dichloride) (PVDC)), styrenic polymers (e.g., polystyrene (PS), acrylostyrene butadiene (ABS), and styrene acrylonitrile (SAN)), polyacrylics (including polyacrylonitrile (PAN) and poly(methyl methacrylate) (PMMA)), polyesters (including poly(ethylene terephthalate) (PET) and poly(butylene terephthalate) (PBT)), polyoxymethylene (POM), polyamides (PA), and fluoropolymers such as polychlorotrifluoroethylene (PCTFE), polycarbonates (PC), aromatic polysulfones including polysulfone (PSU), polyphenylene ether (PPE), epoxies (EP) alone or in mixtures and / or copolymers of several of them. The lamination interlayer may be tinted.

[0084] The lamination interlayer preferably has a thickness between 0.2 mm and 1.1 mm. Preferably, the lamination interlayer is transparent.

[0085] The lamination interlayer can be colorless or tinted.

[0086] The invention comprises a light-extracting element, preferably a layered diffusing element forming a pattern. The layered diffusing element may be an enamel in contact with the substrate or formed on the surface of a substrate of the luminous glazing by a surface treatment such as sandblasting, acid etching, or the deposition of a diffusing layer. The light-extracting element (6) may be a layered diffusing element, in particular a patterned enamel.

[0087] Examples of diffusing layer elements include acid-treated frosted glass, SAINT-GOBAIN GLASS Satinovo® glass and glass with the SAINT-GOBAIN GLASS Smoothlite® diffusing layer.

[0088] In the case of laminated glazing, the diffusing layer element can be formed within the mass of a substrate or interlayer, for example by a laser etching process. The diffusing layer element in the form of a substrate or interlayer is then attached to the surface of the substrate of the material according to the invention, for example by lamination.

[0089] The layer diffusing element can be placed on the substrate of the material according to the invention, in particular on the face opposite to that of the functional coating.

[0090] In laminated glazing, preferably, the functional coating will be on face 4 and the diffusing element on face 3. According to another embodiment, the functional coating may be on face 3 and the diffusing element on face 4. Finally, if for certain applications it is envisaged to illuminate the exterior, the coating and the diffusing element may then each be on face 1 or 2.

[0091] The layered diffusing element can be a self-supporting diffusing film, preferably bonded to a glazing substrate.

[0092] The diffusing layer may be a layer deposited on a substrate. The layer may be based on a diffusing enamel. It may be deposited discontinuously on one face of a substrate so as to form a pattern. The layer may be a diffusing ink printed on a substrate or an interlayer.

[0093] The diffusing layer may comprise an organic or mineral matrix and diffusing particles, for example, of a metal oxide such as titanium dioxide. An example of a transparent mineral diffusing layer is the transparent enamel as described in application FR3084355. An example of a transparent organic diffusing layer is the transparent layer as described in application WO2022023638.

[0094] The diffusing elements are placed at the desired locations for light extraction. It is thus possible to trace the path of light on the surface of the glazing by diffusing it through diffusing surfaces with well-defined areas and contours, according, for example, to geometric patterns or even text.

[0095] The layer diffusing element can be opaque or transparent.

[0096] The diffusing layer may comprise a matrix (organic or mineral) and diffusing particles, for example of metal oxide (TiO2 etc).

[0097] As an example of a transparent mineral diffusing layer, transparent enamel as described in application FR3084355 can be cited.

[0098] As an example of an organic transparent diffusing layer, we can cite the transparent layer as described in application WO2022023638.

[0099] The preferred characteristics that appear in the following description are applicable both to the material according to the invention and, where applicable, to the glazing, the process, the use, the building or the vehicle according to the invention.

[0100] All the luminous characteristics described are obtained according to the principles and methods of ISO 9050 relating to the determination of the luminous and solar characteristics of glazing used in glass for construction.

[0101] Conventionally, refractive indices are measured at a wavelength of 550 nm.

[0102] According to the invention: - Light reflection corresponds to the reflection of solar radiation in the visible part of the spectrum. - Light transmission corresponds to the transmission of solar radiation in the visible part of the spectrum. - Light absorption corresponds to the absorption of solar radiation in the visible part of the spectrum. BRIEF DESCRIPTION OF THE FIGURES

[0103] The invention and its various applications will be better understood upon reading the following description and examining the accompanying figure:

[0104] Fig. 1 represents very schematically a luminous laminated glazing according to an embodiment of the invention.

[0105] The glazing comprises two sheets of glass or substrate. The lower substrate 10 is directed towards the interior of the passenger compartment or building, and the upper substrate 20 is directed towards the exterior of the passenger compartment or building. The two substrates 10, 20 are separated by a PVB-type laminate interlayer 30. The different faces of the substrates are conventionally numbered from the outside in: 1, 2, 3, 4. In [Fig. 1], a functional coating 5 is disposed on face 4. A light extraction means 6 is disposed on face 3; this is a layer forming a pattern.

[0106] A light-emitting diode 7 is shown schematically. Its emitting surface faces the edge 8 of the lower substrate 10. A polarizer 9 is arranged between the emitting surface of the diode 7 and the edge 8 of the lower substrate 10. EXAMPLES OF IMPLEMENTATION 1. Functional materials and coatings

[0107] In these examples, the glass substrates are alumino-silicate type glass substrates. The laminate interlayers are 0.76 mm thick Poly(vinyl butyral) (“PVB”) interlayers.

[0108] Functional coatings include a functional layer located between two dielectric coatings. The functional layers (F) are layers of tin and indium oxide. Dielectric coatings include: - layers based on silicon nitride (Si3N4, n550 = 2.0), - layers based on silicon oxide (SiO2, n550 = 1.5). The deposition conditions of the layers, which were deposited by sputtering (so-called "magnetron cathode sputtering"), are summarized in Table 1.

[0109] [Tables 1] Target Coating Used Deposition Pressure Gas ITO In2O3 90%, SnO2 10% wt 2.103 mbar Ar / (Ar + O2) at 99% SiO2 Si:Al at 92:8% wt 2.103 mbar Ar / (Ar + O2) at 62.5% Si3N4 Si:Al at 92:8% wt 3.2103 mbar Ar / (Ar + N2) at 55%

[0110] Rev. 1: This functional coating comprises the following layer sequence: Glass / / Si3N4 30 nm / SiO2 17 nm / ITO 72 nm / Si3N4 9 nm / SiO2 50 nm

[0111] ITO means: Indium Tin Oxide (InO2:Sn)

[0112] Rev.2: Glass / / Si3N4 88 nm / SiO2 150 nm / ITO 75 nm / Si3N4 68 nm / SiO2 200 nm

[0113] The thicknesses of the layers of this coating were chosen to optimize the optical properties when using an S-type polarizer.

[0114] Rev.3: Glass / / Si3N4 68 nm / SiO2 128 nm / ITO 75 nm / Si3N4 5 nm

[0115] The thicknesses of the layers of this coating were chosen to optimize the optical properties when using a P-type polarizer.

[0116] 2. Description of the tested luminous laminated glazing

[0117] The laminated glazing tested includes: - a first substrate of ordinary 2mm soda-lime glass and - a second 2 mm soda-lime glass substrate, the two substrates are separated by a 0.76 mm thick Polyvinyl Butyral (PVB) laminate interlayer, - the functional coating is located on the first substrate and positioned on face 4.

[0118] The first substrate according to the invention is the substrate located furthest inside the passenger compartment or building.

[0119] The first substrate further comprises on face 3 a layer diffusing element forming a pattern (6).

[0120] A commercially available Spechtech polarizing film 9 was used. It is a linear polarizing laminated film. It belongs to the category of polymer absorbing polarizers. Its characteristics are: - a thickness of approximately 0.43 mm, - an extinction coefficient of approximately 44:1,

[0121] - a transmission factor of unpolarized light in the range of wavelengths wavelength of 400 to 700 nm of 38%. It can be attached to it by any means, including gluing or the use of mechanical means.

[0122] The light source 8 is a white LED lamp capable of injecting light into the first substrate from the edge. The light therefore first passes through the polarizer before entering the first substrate. The entry face is thus the edge of the substrate.

[0123] III. Characterization of the effect of guided mode absorption

[0124] Simulations were carried out on laminated luminous glazing coated on face 4 with the functional coatings with low emissivity properties defined above.

[0125] The simulation calculates the change in the light ray, in polarized or unpolarized light, after reflection on the surface of the functional coating. In particular, it calculates the level of light reflection and absorption at all wavelengths. Estimating these levels makes it possible to predict the brightness and color of the light extracted by the extraction elements at any point on the glazing.

[0126] The parameters Rgm, a*gm and b*gm correspond to the reflections and the a* and b* colors in guided mode reflection at the substrate / functional coating interface at an angle of 80° in the glass substrate.

[0127] The light absorption characteristics are obtained by simulation considering the illuminant D65 at 80° perpendicular to the mounted material, and after reflection on the functional coating of the inside of the glass in single or laminated glazing (unless otherwise specified): - AL corresponds to the light absorption in the visible spectrum in %, - a*abs and b*abs correspond to the colors of absorptions a* and b* by the coating

[0128] - L*a*b*observer inside the glass.

[0129] They are summarized in the table below. Ex 1 Ex 2 Ex 3 Coating Rev.1 Rev.2 Rev.3 With s-type polarizer Rgm (%) 94.1 99.2 96.6 a*gm -2.4 -0.2 -6.7 b*gm -1.5 0.4 18.2 AL (%) 5.9 0.1 3.4 a*abs 13.9 3.4 47.4 b*abs 11.1 0.6 -65.6 With P-type polarizer Rgm (%) 88.2 96.6 98.2 a*gm -5.5 -3 -0.7 b*gm -5 -0.2 1 AL (%) 11.8 4.5 1.9 a*abs 19.1 39.7 7.5 b*abs 25.6 37.6 6.1 Without polarizer Rgm (%) 91.1 97.7 97.4 a*gm -3.9 -3.2 -3.6 b*gm -3.2 -1.4 8.4 AL (%) 8.9 2.3 2.6 a*abs 16.9 31.7 32.5 b*abs 19.4 25.8 -45.4

[0130] The Rgm, a*gm and b*gm values ​​in guided mode reflection at the substrate / functional coating interface were determined. This reflection corresponds to an angle of incidence of 80° in the glass substrate. By definition of guided mode, where the propagation angle is greater than the critical angle of the system, light cannot be transmitted through the coating. What is not reflected is therefore absorbed. According to the invention, it is very useful to have the highest possible Rgm value because this parameter denotes low absorption. Indeed, the conservation of energy in a guided mode requires Rgm + Agm = 1, where Agm is the absorption of the guided mode. Low absorption results in high Rgm values. A high Rgm value indicates both lower absorption, particularly in the red region of the guided mode, and better preservation of the guided mode in terms of its total intensity. The parameters a*gm and b*gm indicate the change in colorimetric parameters of light at reflection, for a white incident light, of the type of illuminant D65. A positive a*gm value means that the reflection becomes redder than the incident ray. A negative a*gm value means that the reflection becomes greener than the incident ray. A positive b*gm value means that the reflection becomes yellower than the incident ray. A negative b*gm value means that the reflection becomes bluer than the incident ray. Reflection of a certain color indicates light absorption of the complementary color. Thus, for example, a negative a*gm value signifies green reflection and absorption in the red range. The higher the absolute values ​​of parameters a* and b*, the more the color of the re- flexions / absorptions will itself be pronounced. According to the invention, we are looking for less negative, or even neutral, values ​​of a*gm and b*gm. However, this must be considered in relation to the Rgm values. As explained above, a high Rgm value indicates low absorption. Therefore, it can be advantageous to have structures with high Rgm values ​​even if the associated a*gm and b*gm values ​​are higher in absolute terms, as these colors will be less intense.

[0131] It can be seen that for examples 1 and 2, the optical properties and colors are improved with the use of an S-type polarizer, compared to the optical properties and colors obtained without a polarizer. Light reflection is increased and light absorption is decreased. The colors are more neutral (closer to zero).

[0132] For example 3, the optical properties and colors are improved with the use of a P-type polarizer.

[0133] Depending on the coating used, it is appropriate to choose a type of polarizer and thus improve the intensity and colors of the light pattern.

[0134] The invention also applies to other glazing structures, for example single or double glazing.

[0135] In the case of single glazing, the critical angle of total internal reflection is no longer 80° but approximately 40°

[0136] Other coatings could be used, whether they have low emissivity properties or not.

[0137] Other positions can be considered for the coating and the extraction elements. For example, it is possible to place the coating on face 3 and the extraction elements on face 4.

[0138] With the use of RGB LEDs, it could be considered to place the polarizer in front of the red light emission only. This arrangement would have the advantage of further reducing color variation and increasing the light output.

Claims

Demands

1. Luminous glazing comprising: - a first substrate coated with a functional coating (5), said substrate having two faces and an edge (8), - a light source (7) comprising an emitting surface, optically coupled with the substrate such that the light enters the substrate through an entry face and the substrate forms a light guide, - a light extracting element (6) for extracting the light and forming a luminous pattern, the glazing being characterized in that it comprises at least one light polarizer (9) located between the emitting surface of the light source (7) and the entry face of the light into the substrate.

2. Luminous glazing according to the preceding claim, characterized in that the light entry face into the substrate is the slice (8) of the substrate.

3. Luminous glazing according to claim 1, characterized in that the substrate has a hole and the light entry face into the substrate is a wall delimiting the hole.

4. Luminous glazing according to any one of the preceding claims, characterized in that the light source (7) is an inorganic light-emitting diode (LED).

5. Luminous glazing according to any one of the preceding claims, characterized in that the substrate is coated with a low-emissivity functional coating (5).

6. Luminous glazing according to the preceding claim, characterized in that the low emissive coating (5) comprises a transparent conductive oxide (TCO) layer, in particular ITO.

7. Luminous glazing according to any one of the preceding claims, characterized in that the polarizer is of type S.

8. Luminous glazing according to any one of claims 1 to 6, characterized in that the polarizer is of type P.

9. Glazing according to any one of the preceding claims, characterized in that the polarizer (9) is glued to the emitting surface of the light source (7).

10. Glazing according to any one of claims 1 to 8, characterized in that the polarizer (9) is bonded to the light-entry face in the substrate.

11. Glazing according to any one of claims 1 to 8, characterized in that the emitting surface is spaced away from the light entry face in the substrate.

12. Glazing according to any one of the preceding claims, characterized in that the extracting element (6) is a diffusing, layered element, in particular an enamel forming a pattern.

13. 3Glazing according to any one of the preceding claims, characterized in that it is curved.

14. 4Glazing according to any one of claims 1 to 12, characterized in that it is a single glazing.

15. 5Glazing according to any one of claims 1 to 12, characterized in that it further comprises a second glass substrate, separated from the first by a gas layer so as to form a double glazing.

16. 16. Glazing according to any one of claims 1 to 13, characterized in that it further comprises a second substrate (10, 20) and a lamination interlayer (30), in particular of PVB, arranged between the two substrates to form a laminated glazing.

17. 17. Glazing according to the preceding claim, characterized in that it is mounted on a passenger compartment or building, the different faces of the substrates are numbered from 1 to 4 from the outside to the inside of the passenger compartment or building.

18. 18. Glazing according to the preceding claim, characterized in that the first coated substrate (10) is located further inside the building or the passenger compartment than the second substrate.

19. 19. Glazing according to any one of claims 17 or 18, characterized in that the extracting element (6) is arranged on face 3 or 4, preferably 3.

20. 20. Glazing according to any one of claims 17 to 19, characterized in that the light entry face into the substrate is the slice (8) of the substrate (10) coated with the functional coating (5).

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