TRANSPARENT SUBSTRATE FOR LAMINATED GLAZING FOR HEAD-UP DISPLAYS AND LAMINATED GLAZING

Abstract

Transparent substrate for laminated glazing (10) for head-up display having a reflective coating (18) configured to reflect p-polarized light (28), the reflective coating (18) comprising a first reflective module including, from the substrate, a first nitride-based dielectric layer, an oxide-based layer having a refractive index having a minimum between 800 and 1600 nm and an extinction coefficient increasing monotonically with the wavelength of the light and a second nitride-based dielectric layer and a second reflective module including, from the substrate, a high refractive index layer and a low refractive index layer, the refractive index of the low refractive index layer being less than 1.9 at 550 nm and the refractive index of the high refractive index layer being greater than 2.1 at 550 nm,the first reflective module being arranged between the substrate and the second reflective module. Laminated glazing (10) for head-up display comprising the transparent substrate provided with a reflective coating (18). Figure for the abstract: Fig. 1,

Description

Title of the invention: TRANSPARENT SUBSTRATE FOR LAMINATED GLAZING FOR HEAD-UP DISPLAYS AND LAMINATED GLAZING technical field

[0001] The present disclosure relates to a transparent substrate for laminated glazing for head-up display and laminated glazing comprising the substrate. Previous technique

[0002] Modern vehicles are now equipped with display systems or devices called "head-up display", also known as HUD in accordance with the English acronym for Head-Up Display.

[0003] These systems or devices include a projector, generally located near the vehicle's dashboard, configured to project an image onto an area of ​​the vehicle's windshield. The projected image appears to the driver as a virtual image behind the windshield, allowing information such as vehicle speed, navigation instructions, or warnings to be displayed directly in their field of vision. The driver no longer needs to take their eyes off the road to consult this information and remains alert to events occurring outside the vehicle. HUD systems or devices thus contribute to improved road safety.

[0004] Most HUD devices rely on the emission of electromagnetic radiation polarized with an s-type polarization and an angle of incidence of approximately 65° to the normal to the windshield. This angle is close to the Brewster angle for a glass-air interface, which is approximately 56.5° for soda-lime glass. The projected image is then reflected by the two main external surfaces of the windshield. In addition to the main image, a secondary image also appears, more or less offset and partially overlapping the main image. This secondary image is called a "ghost image," "double image," or simply "ghost image."

[0005] To mitigate this unwanted ghosting phenomenon, it is common practice to arrange the main surfaces of the windshield at different angles by inserting a laminated interlayer of varying thickness so as to cause the ghost image and the main image to overlap. This type of glazing is generally known as "wedge glazing" or "wedge windshield".

[0006] By way of example, EP 0 420 228 describes a windshield comprising a laminated interlayer whose thickness gradually decreases between a first and a second windshield side so that the two sheets of glass in adhesive contact with said interlayer have two different angles of inclination relative to the projector.

[0007] This type of glazing is however expensive to manufacture, limited to certain viewing angles of the projected image and does not prevent the formation of a ghost image when the glazing includes a functional coating.

[0008] It is common alternative practice to use HUD devices whose implementation is based on the emission of electromagnetic radiation polarized according to a p-type polarization and on a windshield comprising a functional coating adapted to the formation of a new reflective interface within said windshield for this type of radiation.

[0009] When p-polarized electromagnetic radiation is emitted towards the windshield at an angle of incidence close to Brewster's angle, it is weakly reflected by the glass-air interfaces. Reflection occurs only at the reflective interface formed by the functional coating. Different types of functional coatings can be used.

[0010] WO 2005 / 017600 describes a polarizing optical film comprising a plurality of individual layers having different optical refractive indices. The film is intended to be laminated into laminated glass to form a head-up display windshield comprising an area that predominantly reflects visible light polarized according to a p-polarization. The film can also reflect infrared radiation in order to reduce greenhouse effects in a vehicle.

[0011] DE 102014220189 describes a laminated glazing comprising a metallic layer based on silver or aluminium and of a thickness between 5 nm and 9 nm. The metallic layer allows the reflection of visible light polarized according to a p polarization. Description of the invention

[0012] The present exposition aims to remedy at least some of these drawbacks.

[0013] To this end, the present description relates to a transparent substrate for laminated glazing for head-up displays, equipped with a reflective coating configured to reflect p-polarized light. The reflective coating comprises a first reflective module including, from the substrate, a first nitride-based dielectric layer, an oxide-based layer having a refractive index having a minimum between 800 and 1600 nm and an extinction coefficient increasing monotonically with the wavelength of the light, and a second nitride-based dielectric layer and a second reflective module including, from the substrate, a layer with a refractive index high refractive index and low refractive index layer, the refractive index of the low refractive index layer being less than 1.9 at 550 nm and the refractive index of the high refractive index layer being greater than 2.1 at 550 nm, the first reflective module being arranged between the substrate and the second reflective module.

[0014] The reflective coating makes it possible to obtain a reflected image of polarized light p of satisfactory quality and superior to known reflective coatings.

[0015] Indeed, since the coating is a reflective coating, at least 15%, or even 18%, of an incident light ray will be reflected even though the incident angle of the light ray is close to the Brewster angle.

[0016] When the transparent substrate with the reflective coating is used in laminated glazing, the light ray diffracted in the transparent substrate with the reflective coating passes through the laminated glazing. Since the angle of the diffracted light ray is close to the Brewster angle, a small proportion of the diffracted ray is reflected back towards the transparent substrate with the reflective coating. The formation of a so-called "ghost" image due to the reflection of the diffracted ray at the interface between the outer glass sheet and the atmosphere is therefore greatly reduced.

[0017] Moreover, the refractive index of the oxide-based layer passes through a minimum and the extinction coefficient increases with the wavelength of the light.

[0018] By modifying the deposition conditions of the oxide-based layer, it is possible to modify the characteristics of the reflective coating.

[0019] It is understood that the refractive index of the oxide-based layer passing through a minimum, the value of the refractive index increases with the wavelength of the light after passing through the minimum value.

[0020] The presence of the first nitride-based dielectric layer and the second nitride-based dielectric layer sandwiching the oxide-based layer makes it possible to limit, or even avoid, the oxidation of the oxide-based layer and thus to preserve the properties of the oxide-based layer by avoiding the oxidation of the oxide-based layer.

[0021] By “light transmission”, TL, means light transmission, denoted TL, as defined and measured and / or calculated in ISO 13837:2021.

[0022] By “solar factor”, TTS, it is understood that the solar factor is as defined according to ISO 13837:2021-. It is equal to the sum of the direct solar transmittance, TE, and the secondary heat flux, qi.

[0023] By “direct solar transmittance”, TE means direct solar transmittance as defined and calculated according to ISO 13837:2021.

[0024] By “solar selectivity”, SE, it is understood that the ratio between the light transmission, TL, and the direct solar transmittance, TE.

[0025] By "selectivity", s, it is understood that the ratio of light transmission, TL, to the solar factor TTS is meant.

[0026] By “light reflection” R, light reflection is understood as defined and measured and / or calculated in ISO 13837:2021.

[0027] By transparent substrate, it is understood that the substrate is preferably colorless, non-opaque and non-translucent in order to minimize the absorption of light and thus maintain maximum light transmission in the visible electromagnetic spectrum.

[0028] In some embodiments, the refractive index of the oxide-based layer has a difference between the minimum and a value at 400 nm greater than or equal to 0.8, in particular greater than or equal to 1.0.

[0029] In some embodiments, the extinction coefficient is less than 0.2, or even 0.1 at 500 nm and less than 2.0, or even less than 1.5 at 1200 nm.

[0030] In some embodiments, the extinction coefficient is greater than or equal to 0.5 at 1600 nm.

[0031] In some embodiments, the extinction coefficient has a difference between 400 nm and 1200 nm greater than or equal to 0.5.

[0032] Selectivity can thus be favorably increased.

[0033] In some embodiments, the substrate comprises a third reflective module comprising, from the substrate, a layer with a high refractive index and a layer with a low refractive index, the refractive index of the layer with a low refractive index being less than 1.9 at 550 nm and the refractive index of the layer with a high refractive index being greater than 2.1 at 550 nm, the second reflective module being disposed between the first reflective module and the third reflective module.

[0034] In some embodiments, the oxide is a substoichiometric tungsten oxide, preferably of chemical formula WOS, x being between 2.55 and 2.98.

[0035] The presence of substoichiometric tungsten oxide makes it possible to obtain a light transmission ratio to solar factor, i.e. a selectivity of satisfactory quality and superior to known reflective coatings.

[0036] In some embodiments, a physical thickness of the oxide-based layer is greater than or equal to 5 nm and less than or equal to 40 nm.

[0037] In some embodiments, the oxide is a doped tungsten oxide of formula MVW| yO3, M representing at least one dopant element selected from the chemical elements of group 1 according to the IUP AC nomenclature and y being between 0.01 and 0.4, preferably between 0.01 and 0.2, even more preferably between 0.01 and 0.1.

[0038] According to the IUPAC nomenclature, group 1 of the chemical elements includes hydrogen and the alkali elements, i.e. lithium, sodium, potassium, rubidium, cesium and francium.

[0039] The presence of doped tungsten oxide makes it possible to obtain a light transmission ratio to solar factor, i.e. a selectivity of satisfactory quality and superior to known reflective coatings.

[0040] In some embodiments, the doped tungsten oxide has the formula CsyW i yO3, y being between 0.01 and 0.4, preferably between 0.01 and 0.2, even more preferably between 0.01 and 0.1.

[0041] In some embodiments, a physical thickness of the layer based on doped tungsten oxide is greater than or equal to 5 nm and less than or equal to 40 nm.

[0042] In some embodiments, the first and / or second nitride-based dielectric layer is a silicon nitride-based dielectric layer and has a physical thickness greater than or equal to 5 nm.

[0043] In some embodiments, the low refractive index layer is silica-based.

[0044] In some embodiments, the low refractive index layer is silica-based comprising alumina.

[0045] In some embodiments, the low refractive index layer has a physical thickness greater than or equal to 30 nm and less than or equal to 140 nm.

[0046] In some embodiments, the high refractive index layer is based on sub-stoichiometric titanium oxide.

[0047] In some embodiments, the substoichiometric high refractive index layer of the second reflective module has a physical thickness strictly less than the physical thickness of the substoichiometric high refractive index layer of the third reflective module, preferably the thickness of the substoichiometric high refractive index layer of the second reflective module is strictly less than 0.5 times the thickness of the substoichiometric high refractive index layer of the third reflective module.

[0048] In some embodiments, the substrate is a sheet of mineral glass or glass-ceramic.

[0049] By way of non-limiting examples, the glass may be a soda-lime silico-glass, borosilicate, aluminosilicate or alumino-borosilicate type glass.

[0050] In some embodiments, the substrate is a tinted mineral glass in the mass.

[0051] Colouring can generally be achieved by adding colouring oxides to the chemical composition of the glass. Examples of colouring oxides include iron(II) oxide, copper oxide, chromium oxide, nickel oxide, gold oxide, manganese oxide, cobalt oxide, uranium oxide, neodymium oxide, and erbium oxide. Mixtures of oxides such as copper and tin oxide, or ionic complexes such as iron-sulfur or cadmium-sulfur complexes, can also be used.

[0052] In some embodiments, the reflective coating includes a protective coating for the reflective coating disposed opposite the substrate.

[0053] The protective coating may comprise several protective layers.

[0054] The present disclosure also relates to laminated glass for head-up displays comprising: - an outer sheet of glass; - an internal sheet of glass; - an intermediate adhesive layer of lamination placed between the outer glass sheet and the inner glass sheet; the inner glass sheet being a transparent substrate provided with a reflective coating as defined above, one inner face of the inner glass sheet being provided with the reflective coating, the inner face being opposite the intermediate adhesive layer of lamination

[0055] Since the inner surface of the inner glass sheet is equipped with the reflective coating, the light ray diffracted at the interface between the reflective coating and the inner glass sheet is of reduced intensity compared to the intensity of the light ray diffracted in the absence of the reflective coating. The formation of a so-called "ghost" image due to the reflection at the interface between the outer glass sheet and the atmosphere of the diffracted ray at the interface between the reflective coating and the inner glass sheet is reduced. The reduction in the intensity of the reflected light ray is also reduced because the angle of the diffracted light ray is close to the Brewster angle, which reduces the reflection of the diffracted light ray at the interface between the outer glass sheet and the atmosphere.

[0056] In some embodiments, the glazing is devoid of a metallic solar control functional layer.

[0057] Laminated glazing has a light transmission greater than or equal to 71% and is neutral in color in reflection and transmission.

[0058] In some embodiments, the selectivity of the laminated glazing is greater than or equal to 1.05, in particular greater than or equal to 1.10.

[0059] In some embodiments, the ratio of the light reflection of the reflective coating to the light reflection of an external face of the external glass sheet is greater than or equal to 26, or even greater than or equal to 27.

[0060] The higher the ratio, the better the quality of the head-up display, i.e. the "ghost" image will be of very low intensity compared to the image reflected by the reflective coating.

[0061] In some embodiments, the outer glass sheet and / or the inner glass sheet has a thickness of between 0.4 and 1.1 mm, in particular between 0.4 and 0.7 mm.

[0062] In some embodiments, the intermediate adhesive layer of lamination comprises one or more layers of thermoplastic material.

[0063] Examples of thermoplastic material are polyurethane, polycarbonate, polyvinyl butyral (PVB), polymethyl methacrylate (PMMA), ethylene vinyl acetate (EA) or an ionomer resin.

[0064] In some embodiments, the intermediate adhesive layer of lamination has acoustic properties.

[0065] In some embodiments, the intermediate adhesive layer of lamination is anti-UV. Brief description of the drawings

[0066] Other features and advantages of the subject matter of this presentation will become apparent from the following description of embodiments, given by way of non-limiting examples, with reference to the attached figures.

[0067] [Fig.1] Fig.1 is a schematic view of laminated glazing according to one embodiment.

[0068] [Fig.2] The [Fig.2] is a schematic cross-sectional view of a substrate equipped with a reflective coating according to one embodiment.

[0069] [Fig.3] The [Fig.3] is a schematic cross-sectional view of a substrate equipped with a prior art reflective coating.

[0070] [Fig.4] The [Fig.4] is a graph representing the refractive index (unitless) as a function of the wavelength of light (in nm).

[0071] [Fig.5] The [Fig.5] is a graph representing the extinction coefficient (unitless) as a function of the wavelength of the light (in nm).

[0072] Throughout all the figures, the common elements are identified by identical numerical references. Detailed description

[0073] In what follows, the elements common to the different embodiments are identified by the same numerical references.

[0074] Fig. 1 is a schematic cross-sectional view of laminated glazing according to one embodiment.

[0075] In the embodiment of [Fig. 1], the laminated glass 10 is laminated glass for head-up displays. The laminated glass 10 comprises an outer glass sheet 12 and an inner glass sheet 14. The laminated glass 10 includes an adhesive intermediate layer of lamination 16 disposed between the outer glass sheet 12 and the inner glass sheet 14. The outer glass sheet 12 has an outer face 20 and an inner face 22, and the inner glass sheet 14 has an outer face 24 and an inner face 26.

[0076] The outer face 20 of the outer glass sheet 12 is opposite the intermediate adhesive layer of lamination 16, i.e. the inner face 22 of the outer glass sheet 12 is closer to the intermediate layer of lamination 16 than the outer face 20 of the outer glass sheet 12.

[0077] The inner face 26 of the inner glass sheet 14 is opposite the adhesive intermediate layer of lamination 16, i.e. the outer face 24 of the inner glass sheet 14 is closer to the intermediate layer of lamination 16 than the inner face 26 of the inner glass sheet 14.

[0078] In this description, the terms "internal" and "external" are used in relation to laminated glazing when the latter is installed on a motor vehicle, for example. The term "external" refers to an element closer to the exterior of the vehicle and the term "internal" to an element closer to the interior of the vehicle.

[0079] In the embodiment of [Fig.1], the inner face 26 of the inner glass sheet 14 is provided with a reflective coating 18.

[0080] In the embodiment of [Fig.1], the laminated glazing is devoid of a functional layer, for example a metallic solar control functional layer.

[0081] As illustrated in [Fig.1], an incident light ray 28 of p-polarized light is reflected by the reflective coating 18 to form a reflected light ray 30. The incident light ray 28 is oriented at approximately 65° with respect to the bisector 34 of the angle formed between the incident light ray 28 and the reflected light ray 30.

[0082] In the embodiment of [Fig. 1], the outer glass sheet 12, the inner glass sheet 14, and the intermediate adhesive lamination layer 16 have similar or even equal refractive indices. Therefore, the diffracted light ray 56 is only slightly modified when passing through the interfaces between the inner glass sheet 14, the intermediate adhesive lamination layer 16, and the outer glass sheet 12. When the diffracted light ray 56 reaches the interface between the outer glass sheet 12 and the external atmosphere, the diffracted light ray is reflected bythe outer face 20 of the outer glass sheet 12 towards the inner glass sheet 14. The light ray reflected 58 by the outer face 20 of the outer glass sheet 12 is only slightly modified when passing through the interfaces between the outer glass sheet 12, the intermediate adhesive lamination layer 16 and the inner glass sheet 14. At the interface between the reflective coating 18 and the interior atmosphere, the reflected light ray 58 is diffracted and forms a secondary light ray 32. The intensity of the secondary light ray 32 creates, for an observer located on the inner face 26 of the inner glass sheet 14, i.e. inside the vehicle, a low-intensity secondary image, also called a ghost image, which is superimposed on the image created by the light ray reflected 30 by the reflective coating 18.The potentially created "ghost" images at the interfaces with the intermediate adhesive layer of lamination 16 are negligible compared to the light ray reflected 30 by the reflective coating 18 and the secondary light ray 32.

[0083] Fig. 2 is a schematic cross-sectional view of a transparent substrate 42 equipped with the reflective coating 18.

[0084] In the embodiment of [Fig.2], the transparent substrate 42 is a glass sheet, in particular the internal glass sheet 14 of the embodiment of [Fig.1].

[0085] In the embodiment of [Fig.2], the reflective coating 18 comprises three reflective modules, a first reflective module 36, a second reflective module 38 and a third reflective module 40.

[0086] The reflective coating 18 may comprise two reflective modules, the first reflective module 36 and the second reflective module 38.

[0087] The first reflective module 36 is arranged between the transparent substrate 42 and the second reflective module 38. When the reflective coating 18 comprises three reflective modules, the second reflective module 38 is arranged between the first reflective module 36 and the third reflective module 40.

[0088] The reflective module 36, comprises, from the transparent substrate 42, a first nitride-based dielectric layer 44, an oxide-based layer 46, having a refractive index having a minimum between 800 and 1600 nm and an extinction coefficient increasing with the wavelength of the light, a second nitride-based dielectric layer 48.

[0089] Each reflective module 38, 40, comprises, from the transparent substrate 42, a layer of high refractive index 52A, 52B, and a layer of low refractive index 54A, 54B.

[0090] The refractive index of the low refractive index layer 54A, 54B is less than 1.9 at 550 nm and the refractive index of the high refractive index layer 52A, 52B is greater than 2.1 at 550 nm.

[0091] Figure 3 is a schematic cross-sectional view of a substrate with a prior art reflective coating 50 (Comparative Example). The prior art reflective coating 50 comprises two reflective modules, each reflective module comprising, from the transparent substrate 42, a high refractive index layer 52A, 52B and a low refractive index layer 54A, 54B, for example, of silica containing alumina. The refractive index of the low refractive index layer 54A, 54B is less than 1.9 at 550 nm and the refractive index of the high refractive index layer 52A, 52B is greater than 2.1 at 550 nm.

[0092] By way of example, the deposition of a reflective coating comprising thin layers on a glass substrate is carried out by successive deposits of each thin layer by passing the glass substrate through a succession of deposition cells adapted to deposit a given thin layer.

[0093] Deposition cells can use deposition methods such as magnetic field assisted sputtering (also called magnetron sputtering), ion beam assisted deposition (IBAD), evaporation, chemical vapor deposition (CVD), plasma-assisted chemical vapor deposition (PECVD), low-pressure chemical vapor deposition (LPCVD), etc.

[0094] The magnetic field assisted spray deposition process is particularly used.

[0095] The tungsten oxide target may in particular contain one or more dopant elements in the proportions as described for the doped tungsten oxide layer.

[0096] The tungsten oxide-based layer can be deposited by sputtering using the aforementioned target under a deposition atmosphere composed of 20 to 100% argon and 0 to 80% dioxygen, preferably 30 to 90% argon and 10 to 70% dioxygen.

[0097] The tungsten oxide-based layer can be deposited under a pressure of between 1 and 20 mTorr, preferably from 3 to 15 mTorr.

[0098] Preferably, the deposition can be carried out cold, i.e. at a temperature below 100°C, in particular between 20°C and 60°C, for the substrate.

[0099] The deposition can also be carried out hot, in particular at a temperature between 100°C and 400°C.

[0100] The transparent substrate 42 with reflective coating 18 can undergo annealing heat treatment. The annealing temperature can be between 450°C and 800°C, in particular between 550°C and 750°C, or even between 600°C and 700°C. The annealing time can be between 5 min and 30 min, in particular between 5 min and 20 min, or even between 5 min and 10 min.

[0101] In the examples below, the thin films are deposited by magnetic field assisted sputtering.

[0102] For example 1, example 2 and the comparative example, the outer glass sheet 12 is a soda-lime silico-glass with a thickness of 1.6 mm, the intermediate adhesive lamination layer 16 is a PVB with a thickness of 0.76 mm and the inner glass sheet 14 is a soda-lime silico-glass with a thickness of 2.1 mm.

[0103] The outer glass sheet 12 can undergo annealing heat treatment. The annealing temperature can be between 450°C and 800°C, in particular between 550°C and 750°C, or even between 600°C and 700°C. The annealing time can be between 5 min and 30 min, in particular between 5 min and 20 min, or even between 5 min and 10 min.

[0104] Example 1

[0105] The first dielectric layer based on nitride 44 and the second dielectric layer based on nitride 48 are aluminum-doped silicon nitride. The target used is a Si:Al target comprising 92% by weight of silicon and 8% by weight of aluminum. The layer is deposited at a pressure between 3.2 x 10³ and 6 x 10³ mbar in an argon-nitrogen atmosphere with an Ar / (Ar+N₂) ratio of 55 (by volume%).

[0106] The oxide-based layer 46 is made of substoichiometric tungsten oxide WOX. The target used is a tungsten target. The layer is deposited at a pressure of 12 mTorr in an atmosphere containing 60% by volume of dioxygen.

[0107] The high refractive index layer 52A, 52B is made of substoichiometric titanium oxide TiOw and is deposited using a titanium oxide target at a pressure of 2.10-3 mbar in an argon and nitrogen atmosphere with an Ar / (Ar+N2) ratio of 95 (by volume%). The titanium oxide obtained is stoichiometric or close to it (x equal to 2 or nearly so).

[0108] The low refractive index layer 54A, 54B is made of silica comprising alumina. The target used is a Si:Al target comprising 92% by weight of silicon and 8% by weight of aluminum. The layer is deposited at a pressure of 4.103 mbar in an atmosphere of argon and dioxygen with an Ar / (Ar+O2) ratio of 36 (by volume%).

[0109] After deposition of the first reflective module 36, the second reflective module 38 and the third reflective module 40, the transparent substrate 42 with the reflective coating 18 is annealed at 650°C for 10 min. The substoichiometric tungsten oxide WOX has an x ​​value of approximately 2.9.

[0110] Example 2

[0111] The first nitride-based dielectric layer 44 and the second nitride-based dielectric layer 48 are aluminum-doped silicon nitride. The target used is a Si:Al target comprising 92% by weight silicon and 8% by weight of aluminium. The layer is deposited at a pressure between 3.2.10 3 and 6.103 mbar in an atmosphere of argon and nitrogen with an Ar / (Ar+N2) ratio of 55 (in flight%).

[0112] The oxide-based layer 46 is made of cesium-doped tungsten oxide. The target used is a Cs / W / O ceramic target with a Cs / W ratio between 0.3 and 0.4. The layer is deposited at a pressure of 4 mTorr in an atmosphere containing 20% ​​by volume of dioxygen.

[0113] The high refractive index layer 52A, 52B, is made of substoichiometric titanium oxide TiOw and is deposited using a titanium oxide target at a pressure of 2.103 mbar in an argon and nitrogen atmosphere with an Ar / (Ar +N2) ratio of 95 (by volume%). The titanium oxide obtained is stoichiometric or close to it (x equal to 2 or nearly so).

[0114] The low refractive index layer 54A, 54B is made of silica comprising alumina. The target used is a Si:Al target comprising 92% by weight of silicon and 8% by weight of aluminum. The layer is deposited at a pressure of 4.103 mbar in an atmosphere of argon and dioxygen with an Ar / (Ar+O2) ratio of 36 (by volume%).

[0115] After deposition of the first reflective module 36, the second reflective module 38 and the third reflective module 40, the transparent substrate 42 with the reflective coating 18 is annealed at 650°C for 10 min. Cesium-doped tungsten oxide CsyWi yO3 has a y value of approximately 0.05-0.06.

[0116] Comparative example

[0117] The high refractive index layer 52A, 52B, for example of sub-stoichiometric titanium oxide TiOw, is deposited by means of a titanium oxide target at a pressure of 2.103 mbar in an atmosphere of argon and nitrogen with an Ar / (Ar +N2) ratio of 95 (by volume%). The titanium oxide obtained is stoichiometric or close to it (x equal to 2 or nearly so).

[0118] The low refractive index layer 54A, 54B, is for example made of silica comprising alumina. The target used is a Si:Al target comprising 92% by weight of silicon and 8% by weight of aluminum. The layer is deposited at a pressure of 4.103 mbar in an atmosphere of argon and dioxygen with an Ar / (Ar+O2) ratio of 36 (by volume%).

[0119] After deposition of the layers of high refractive index and low refractive index, the transparent substrate 42 provided with the coating is annealed at 650° C. for 10 min.

[0120] Table 1 gives the physical thicknesses of each layer, the thicknesses being expressed in nm, for example 1, example 2 and the comparative example as well as the values ​​of the selectivity and the ratio R3o / R32 65°.

[0121] R30 / R32 65° represents the ratio between the light reflection of the light ray reflected 30 by the reflective coating 18 and the secondary light ray 32 measured with an angle of the incident light ray 28 of 65° with respect to the normal, i.e. the bisector 34, to the laminated glazing 10.

[0122] [Tables 1] Example 1 Example 2 Comparative Example 44 56 nm 75 nm 46 20 nm 15 nm 48 53 nm 5 nm 52A 38 nm 26 nm 18 nm 54A 120 nm 89 nm 120 nm 52B 86 nm 99 nm 65 nm 54B 68 nm 102 nm 85 nm Selectivity 1.11 1.15 1.03 R30 / R32 65° 30.0 23.8 25.0

[0123] Figure 4 is a graph representing the refractive index (unitless) as a function of the wavelength of light (in nm). Curve 60 represents the evolution of the refractive index of substoichiometric tungsten oxide as a function of the wavelength of light, curve 62 the evolution of the refractive index of cesium-doped tungsten oxide as a function of the wavelength of light, and curve 64 represents the evolution of the refractive index of stoichiometric tungsten oxide as a function of the wavelength of light. Curve 64 for stoichiometric tungsten oxide is given for illustrative and comparative purposes. It is observed that, unlike curve 60 of substoichiometric tungsten oxide and curve 62 of cesium-doped tungsten oxide, curve 64 of stoichiometric tungsten oxide does not pass through a minimum and varies little as a function of the wavelength of light.

[0124] Figure 5 is a graph representing the extinction coefficient (unitless) as a function of the wavelength of light (in nm). Curve 66 represents the evolution of the extinction coefficient of substoichiometric tungsten oxide as a function of the wavelength of light, curve 68 the evolution of the extinction coefficient of cesium-doped tungsten oxide as a function of the wavelength of light, and curve 70 represents the evolution of the extinction coefficient of stoichiometric tungsten oxide as a function of the wavelength of light. Curve 70 for stoichiometric tungsten oxide is given for illustrative and comparative purposes. It can be seen that, unlike curve 66 for substoichiometric tungsten oxide and curve 68 for cesium-doped tungsten oxide, the curve 70 of stoichiometric tungsten oxide is not increasing but constant at O.

[0125] The transparent substrate 42 and the laminated glazing 10 are particularly suitable for automotive glazing applications. They can also be adapted for certain building glazing applications, particularly as laminated glazing.

[0126] Although the present description has been made with reference to a specific embodiment, it is evident that various modifications and changes can be made to these examples without departing from the general scope of the invention as defined by the claims. Furthermore, individual features of the various embodiments mentioned can be combined in additional embodiments. Therefore, the description and drawings should be considered in an illustrative rather than restrictive sense.

Claims

Demands

1. A transparent substrate (42) for laminated glazing for head-up displays, having a reflective coating (18) configured to reflect p-polarized light, the reflective coating (18) comprising a first reflective module (36) comprising, from the substrate (42), a first nitride-based dielectric layer (44), an oxide-based layer (46) having a refractive index having a minimum between 800 and 1600 nm and an extinction coefficient increasing monotonically with the wavelength of the light, and a second nitride-based dielectric layer (48), and a second reflective module (38) comprising, from the substrate (42), a high-refractive-index layer (52A) and a low-refractive-index layer (54A), the refractive index of the low-refractive-index layer (54A) being less than 1.9 at 550 nm and the refractive index of the high-refractive-index layer (54A) being less than 1.9 at 550 nm. high refractive index (52A) being greater than 2.1 at 550 nm,the first reflective module (36) being arranged between the substrate (42) and the second reflective module (38).

2. Transparent substrate (42) according to claim 1, comprising a third reflective module (40) comprising, from the substrate (42), a high refractive index layer (52B) and a low refractive index layer (54B), the refractive index of the low refractive index layer (54B) being less than 1.9 at 550 nm and the refractive index of the high refractive index layer (52B) being greater than 2.1 at 550 nm, the second reflective module (38) being disposed between the first reflective module (36) and the third reflective module (40).

3. Transparent substrate (42) according to claim 1 or 2, wherein the oxide is a substoichiometric tungsten oxide, preferably of chemical formula WOS, x being between 2.55 and 2.

98.

4. Transparent substrate (42) according to claim 3, wherein a physical thickness of the oxide-based layer is greater than or equal to 5 nm and less than or equal to 40 nm.

5. Transparent substrate (42) according to claim 1, wherein the oxide is a doped tungsten oxide of formula MyWi_yO3, M representing at least one doping element selected from the chemical elements of group 1 according to the IUPAC nomenclature and being between 0.01 and 0.4, preferably between 0.01 and 0.2, even more preferably between 0.01 and 0.

1.

6. Transparent substrate (42) according to claim 4, wherein the doped tungsten oxide is of formula CsyWi yO3, y being between 0.01 and 0.4, preferably between 0.01 and 0.2, even more preferably between 0.01 and 0.

1.

7. Transparent substrate (42) according to claim 5 or 6, wherein a physical thickness of the layer based on doped tungsten oxide is greater than or equal to 5 nm and less than or equal to 40 nm.

8. Transparent substrate (42) according to any one of claims 1 to 7, wherein the first and / or second nitride-based dielectric layer is a silicon nitride-based dielectric layer and has a physical thickness greater than or equal to 5 nm.

9. Transparent substrate (42) according to any one of claims 1 to 8, wherein the low refractive index layer is silica-based.

10. Transparent substrate (42) according to claim 9, wherein the low refractive index layer is silica-based comprising alumina.

11. Transparent substrate (42) according to claim 10, wherein the low refractive index layer has a physical thickness greater than or equal to 30 nm and less than or equal to 140 nm.

12. Transparent substrate (42) according to any one of claims 1 to 11, wherein the high refractive index layer is based on sub-stoichiometric titanium oxide.

13. Transparent substrate (42) according to claim 12 in combination with claim 2, wherein the substoichiometric titanium oxide-based high refractive index layer of the second reflective module has a physical thickness strictly less than a physical thickness of the substoichiometric titanium oxide-based high refractive index layer of the third reflective module, preferably the thickness of the substoichiometric titanium oxide-based high refractive index layer of the second reflective module is strictly less than 0.5 times the thickness of the substoichiometric titanium oxide-based high refractive index layer of the third reflective module.

14. Laminated glazing (10) for head-up display comprising: - an outer glass sheet (12); - an inner glass sheet (14); - an adhesive intermediate lamination layer (16) disposed between the outer glass sheet (12) and the inner glass sheet (14); the inner glass sheet (14) being a transparent substrate (40) provided with a reflective coating (18) according to any one of claims 1 to 13, an inner face (26) of the inner glass sheet (14) being provided with the reflective coating (18), the inner face (26) being opposite the adhesive intermediate lamination layer (16).

15. Glazing according to claim 14, the glazing being devoid of a metallic solar control functional layer.

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