Glazing with diffuse reflection

Abstract

The invention relates to glazing comprising a stack of layers (40) between a lower substrate (20) and a transparent upper substrate (30). Said stack of layers comprises: - two dielectric layers, a lower layer (41) and an upper layer (42), said lower layer comprising a first layer made of adhesive material, referred to as "first adhesive layer", - an intermediate layer (43) made of polymer material, in contact with said first adhesive layer, and having a refractive index substantially identical to that of the upper layer, - a central layer (44) in contact along a textured interface with each of said intermediate and upper layers, said central layer being configured so that the glazing has diffuse reflection properties.

Description

Diffuse reflective glazing

[0001] The present invention belongs to the general field of glazing manufacturing. It relates more particularly to glazing comprising a stack of layers between two sheets of glass, so as to have diffuse reflection properties. It also relates to a method of manufacturing such glazing, as well as a screen, a system and a projection method using such glazing. The invention finds advantageous use in a plurality of industrial applications, such as in particular in the display of information on glazing for a building or for a vehicle.

[0002] Known glazings include standard transparent glazings, which give rise to specular transmission and reflection of radiation incident on the glazing, and translucent glazings, which give rise to diffuse transmission and reflection of radiation incident on the glazing.

[0003] Usually, reflection by a glazing is said to be diffuse when radiation incident on the glazing with a given angle of incidence is reflected by the glazing in a plurality of directions. Reflection by a glazing is said to be specular when radiation incident on the glazing with a given angle of incidence is reflected by the glazing with an angle of reflection equal to the angle of incidence. By analogy, transmission through a glazing is said to be specular when radiation incident on the glazing with a given angle of incidence is transmitted by the glazing with an angle of transmission equal to the angle of incidence.

[0004] A disadvantage of standard transparent glazing is that it produces sharp, mirror-like reflections, which is undesirable in some applications. Therefore, when glazing is used for a building window or display screen, it is best to limit the presence of reflections, which reduce visibility through the glazing. Sharp reflections on glazing can also generate glare risks, with safety consequences, for example when vehicle headlights are reflected on glass building facades. This problem is particularly relevant for airport glass facades. It is essential to minimize the risk of glare for pilots approaching terminals.

[0005] Translucent glazing, on the other hand, although it has the advantage of not generating sharp reflections, does not allow for a clear view through the glazing.

[0006] In order to overcome these drawbacks, it is known from the state of the art, including document WO2012104547A1, to use a transparent layered element in the manufacture of glazing, the aim being to give the latter diffuse reflection properties while maintaining specular transmission properties.

[0007] This layered element can either be inserted between two transparent substrates, so as to form said glazing, or be added, for example by gluing, to a surface of an existing glazing. Each transparent substrate can for example be made of transparent polymer, transparent glass, transparent ceramic.

[0008] More particularly, said layered element comprises a so-called “central” layer interposed between two external layers, a lower layer and an upper layer, which are made of dielectric materials having substantially the same refractive index.

[0009] The contact (i.e. the contact surface) between the central layer and each of said external layers is made according to a so-called "textured" interface (so that each external layer can be seen as a textured layer). Conversely, each external layer has, in opposition to the textured interface which separates it from the central layer, a smooth surface.

[0010] In detail, the central layer is formed either by a single layer which is a dielectric layer with a refractive index different from that of the external layers or a metallic layer, or by a stack of layers which comprises at least one dielectric layer with a refractive index different from that of the external layers or a metallic layer. Each contact surface between two adjacent layers of the layered element which are one dielectric and the other metallic, or which are two dielectric layers with different refractive indices, is textured and parallel to the other textured contact surfaces between two adjacent layers which are one dielectric and the other metallic or which are two dielectric layers with different refractive indices.

[0011] The production of such an element in layers, via a suitable manufacturing process, is not recalled here, it being understood that it is possible to consult, in particular, the document WO2012104547A1 for more details. At the very least, it is only recalled that the deposition of the central layer on the lower layer is carried out in a manner conforming to the textured surface of said lower layer (i.e. the single layer or each of the layers forming the central layer has a substantially uniform thickness over the entire extent of said textured surface).

[0012] For the entire description given herein, and unless otherwise stated, the terms and expressions cited below refer respectively to:- dielectric material or layer: a material or layer of low electrical conductivity, less than 100 S / m;- index: optical index of refraction, measured at the wavelength of 550 nm;- substantially equal refractive indices of two dielectric materials: the absolute value of the difference between said refractive indices at 550 nm is less than or equal to 0.15, preferably less than 0.05, more preferably less than 0.015;- different refractive indices of two dielectric materials: the absolute value of the difference between their refractive indices at 550 nm is strictly greater than 0.15;- transparent element: element (material, substrate, etc.) through which there is specular transmission of radiation at least in the wavelength ranges useful for the intended application of the element. For example, when the element is used as building or vehicle glazing, it is transparent at least in the visible wavelength range;- smooth surface / interface: surface / interface for which the surface / interface irregularities are smaller than the wavelength of the radiation incident on the surface / interface, so that the radiation is not deflected by these surface / interface irregularities. The incident radiation is then transmitted and reflected specularly by the surface / interface;- textured surface / interface: surface / interface for which the surface / interface irregularities vary on a scale larger than the wavelength of the radiation incident on the surface / interface.In practice, a textured surface / interface has a plurality of patterns that are recessed or projecting relative to a general plane of said surface / interface. Due to the presence of these irregularities, the incident radiation is then transmitted and reflected diffusely by the surface / interface.

[0013] Furthermore, throughout the description and with regard to the composition of the central layer, a distinction is made between metallic layers, on the one hand, for which the value of the refractive index is indifferent, and dielectric layers, on the other hand, for which the difference in refractive index compared to that of the external layers is to be considered.

[0014] Diagrammatically illustrates an example of glazing 1 of the prior art comprising a layered element 4 as mentioned above, and typically integrated into a projection screen.

[0015] As illustrated by the, the glazing 1 comprises two transparent substrates, a lower substrate 2 and an upper substrate 3. More particularly, in this example, each of said substrates 2, 3 corresponds to a sheet of glass.

[0016] The layered element 4 is formed, in particular, by a lower layer 5 made of PU (acronym for polyurethane) and an upper layer 6 made of PMMA (acronym for polymethyl methacrylate), said lower 5 and upper 6 layers having substantially equal respective refractive indices. Furthermore, said lower layer 5 is in contact along a smooth interface (more precisely here a flat interface) with the lower substrate 2.

[0017] The layered element further comprises a central layer 7 in contact according to a textured interface with each of said lower 5 and upper 6 layers. In other words, each of said lower 5 and upper 6 layers has a textured surface with which the central layer 7 is in contact (each of said lower 5 and upper 6 layers therefore corresponds to a textured layer).

[0018] In this example, and purely for illustrative purposes, said central layer 7 consists of a dielectric layer made of titanium oxide (TiO2) and whose refractive index differs from those of the lower 5 and upper 6 layers.

[0019] In addition to the layered element 4, the glazing 1 also comprises a layer 8 made of PU and in contact at a smooth interface (more precisely here a flat interface) with the upper layer 6 and the upper substrate 3 respectively. It should be noted that the refractive index of said layer 8 is indifferent given the presence of said smooth interfaces. Ultimately, the assembly formed by the layered element 4 and said layer 8 corresponds to a stack of layers which characterizes the glazing 1.

[0020] Although widely deployed today in information projection systems (examples: display screen integrated into a building, street furniture, projection screen for personal use, etc.), a configuration such as that described with reference to the proves problematic. Indeed, it is very common to observe a phenomenon called "waviness" through such glazing, tending to give a visual impression of undulation of the layers placed between the transparent substrates of the glazing.

[0021] This phenomenon of mottling is explained by the fact that the manufacture of the glazing, via a classic autoclave lamination step (for example at a temperature of 95°C and a pressure of 6 bars), causes a relative displacement between the lower 5 and upper 6 layers.

[0022] This phenomenon of mottling results in a plurality of defects, including:- defects in terms of the general visual appearance of the glazing. This is particularly true in the absence of projection when the glazing is placed in front of a black background, the undulations becoming perceptible;- defects in terms of the quality of the projected image. This is particularly true when the background of the projected image is light, the undulations can make it difficult to read the image. The visual perception of these undulations increases with the angle of observation of the projected image, which further contributes to limiting access to the information intended to be transmitted by it.

[0023] The present invention aims to overcome all or part of the drawbacks of the prior art, in particular those set out above, by proposing a solution which makes it possible to provide diffusely reflective glazing for which no mottling phenomenon can be observed, so that said glazing has qualities, in terms of visual rendering and projected image, which are far superior to those of the solutions of the prior art.

[0024] To this end, and according to a first aspect, the invention relates to a glazing comprising a stack of layers between two substrates, a lower substrate and a transparent upper substrate, each substrate comprising smooth surfaces opposite one another, said stack of layers comprising:- two dielectric layers, a lower layer and an upper layer, said lower layer comprising a first layer made of adhesive material, called "first adhesive layer", said lower and upper layers being respectively in contact along a smooth interface with the lower and upper substrates,- an intermediate layer made of a polymer material, in contact along a smooth interface with said first adhesive layer, and with a refractive index substantially identical, preferably identical, to that of the upper layer,- a central layer in contact at a textured interface with each of said intermediate and upper layers, said central layer being formed either by a single layer which is a metal layer or a dielectric layer with a refractive index different from that of said intermediate and upper layers, or by a stack of layers which comprises a metal layer or at least one dielectric layer with a refractive index different from that of said intermediate and upper layers.,

[0025] In particular embodiments, the adhesive material of the first adhesive layer is a transparent adhesive material and the first adhesive layer is referred to as a "first OCA layer."

[0026] In particular embodiments, said upper layer is made of transparent adhesive material or polyurethane.

[0027] In particular embodiments, said intermediate layer is made of polymethyl methacrylate or polycarbonate.

[0028] In particular embodiments, the lower substrate is an absorbent and / or transparent glass.

[0029] In particular embodiments, the lower substrate is an opaque glass.

[0030] In particular embodiments, at least one of the surfaces of the lower substrate is covered at least in part with a dark enamel or a dark paint, for example a black enamel or a black paint.

[0031] In particular embodiments, the surface of the first adhesive layer interfacing with the intermediate layer is covered at least in part with a dark enamel or a dark paint, for example a black enamel or a black paint.

[0032] In particular embodiments, the lower layer is made of said first adhesive layer.

[0033] In particular embodiments, the adhesive material of the first adhesive layer is a transparent adhesive material and the first adhesive layer is called “first OCA layer”, the lower layer comprising: - a second layer made of transparent adhesive material, called “second OCA layer”, and in contact at a smooth interface with the lower substrate, - a glass sheet called “intermediate” in contact at a smooth interface with each of said first (41_OCA1) and second OCA layers, said intermediate sheet being an active film, for example an electrochromic active film.

[0034] According to a second aspect, the invention relates to a glazing comprising a stack of layers between two substrates, a lower substrate and a transparent upper substrate, each substrate comprising smooth surfaces opposite each other. Said stack of layers comprises:- two dielectric layers, a lower layer and an upper layer, said lower layer comprising a first layer made of transparent adhesive material, called "first OCA layer", said lower and upper layers being respectively in contact at a smooth interface with the lower and upper substrates,- an intermediate layer made of a polymer material, in contact at a smooth interface with said first OCA layer, and with a refractive index substantially identical, preferably identical, to that of the upper layer,- a central layer in contact at a textured interface with each of said intermediate and upper layers,said central layer being formed either by a single layer which is a metallic layer or a dielectric layer with a refractive index different from that of said intermediate and upper layers, or by a stack of layers which comprises a metallic layer or at least one dielectric layer with a refractive index different from that of said intermediate and upper layers.,

[0035] The glazing according to the invention is particularly advantageous in that the lower layer comprises said first OCA layer. Indeed, it is thanks to this first OCA layer that the glazing according to the invention makes it possible to eliminate the mottling effect observed in the glazing of the prior art.

[0036] The said first OCA layer has the particularity of maintaining a constant thickness when the glazing undergoes, during its manufacture and as detailed below, an autoclave lamination step. These provisions therefore also make it possible to maintain the flatness of the intermediate layer during manufacture (at the interface between the intermediate layer and the first OCA layer), which ultimately eliminates any possibility of relative displacement of the intermediate layer with respect to the upper layer. In general, any potential problem of deformation of these layers on a short or long scale is avoided.

[0037] This results in significantly superior quality performance in terms of visual appearance and projected image compared to what previously known solutions can offer.

[0038] In particular embodiments, the glazing may further comprise one or more of the following characteristics, taken individually or in all technically possible combinations.

[0039] In particular embodiments, said upper layer is made of transparent adhesive material (OCA) or polyurethane.

[0040] The provisions according to which the upper layer is made of transparent adhesive material (OCA) ultimately make it possible to obtain a glazing comprising two OCA layers (said first OCA layer and said upper layer). However, the manufacture of such glazing proves advantageous in that it requires a reduced autoclave cycle time, but also an autoclave cycle that is less restrictive in terms of energy expended since it can be implemented at a lower temperature than that used when there is only one OCA layer.

[0041] In particular embodiments, said intermediate layer is made of polymethyl methacrylate or polycarbonate.

[0042] In particular embodiments, the lower substrate is an absorbent and / or transparent glass.

[0043] In particular embodiments, the lower substrate is an opaque glass.

[0044] In particular embodiments, at least one of the surfaces of the lower substrate is covered at least in part with a dark enamel or paint, for example a black enamel or paint.

[0045] Conventionally, color can be assessed using the colorimetric coordinates L*, a*, and b*, calculated using the illuminant D65 and the CIE-1931 reference observer. The L* component defines lightness, ranging from 0 for black to 100 for white. Therefore, "dark" refers to any element with a lightness such that the L* value measured in reflection is less than 50.

[0046] In particular embodiments, the surface of the first OCA layer interfacing with the intermediate layer is covered at least in part with a dark enamel or a dark paint, for example a black enamel or a black paint.

[0047] In particular embodiments, the lower layer is made of said first OCA layer.

[0048] In particular embodiments, the lower layer comprises: - a second layer made of transparent adhesive material, called "second OCA layer", and in contact at a smooth interface with the lower substrate, - a glass sheet called "intermediate" in contact at a smooth interface with each of said first and second OCA layers, said intermediate sheet being an active film, for example an electrochromic film.

[0049] According to a third aspect, the invention relates to a projection screen comprising glazing according to the invention.

[0050] According to a fourth aspect, the invention relates to a projection system comprising a projection screen according to the invention as well as a projector, the upper substrate being intended to be positioned opposite said projector.

[0051] According to a fifth aspect, the invention relates to a projection method.

[0052] According to a sixth aspect, the invention relates to a use implemented by means of a projection system according to the invention.

[0053] According to a seventh aspect, the invention relates to a use of a glazing according to the invention as all or part of a glazing for a vehicle, for a building, for street furniture, for interior furnishings, for a display screen, for a Head Up Display system.

[0054] According to an eighth aspect, the invention relates to a method for manufacturing a glazing unit, said method comprising steps of: - obtaining two substrates, a lower substrate and a transparent upper substrate, each substrate comprising smooth surfaces opposite one another, - forming a stack of layers between the lower and upper substrates, said stack of layers being suitable for manufacturing a glazing unit according to the invention, - autoclave lamination of the assembly formed by the lower and upper substrates as well as by the stack of layers.

[0055] In particular embodiments, the method of manufacturing a glazing unit is a method of manufacturing a glazing unit according to the invention.

[0056] In particular embodiments, said forming step comprises:- depositing the lower layer on the lower substrate,- depositing the intermediate layer on the first adhesive layer,- texturing the intermediate layer at a surface opposite the smooth interface with the first adhesive layer,- conformally depositing the central layer on the textured surface of the intermediate layer,- depositing the upper layer on the upper substrate,- texturing the upper layer at a surface opposite the smooth interface with the upper substrate,- assembling the assembly formed by the lower substrate, the lower layer, the intermediate layer and the central layer with the assembly formed by the upper substrate and the upper layer, such that the central layer is also in contact with the textured surface of the upper layer.

[0057] In particular embodiments of implementation, the step of forming the stack of layers is implemented so as to manufacture a glazing according to the invention in which the upper layer is made of transparent adhesive material.

[0058] In particular embodiments, the step of forming the stack of layers is implemented so as to manufacture a glazing according to the invention in which the upper layer is made of transparent adhesive material, said forming step comprising:- a deposition of the lower layer on the lower substrate,- a deposition of the intermediate layer on the first OCA layer,- a texturing of the intermediate layer at a surface opposite the smooth interface with the first OCA layer,- a conformal deposition of the central layer on the textured surface of the intermediate layer,- a deposition of the upper layer on the upper substrate,- a texturing of the upper layer at a surface opposite the smooth interface with the upper substrate,- an assembly of the assembly formed by the lower substrate, the lower layer,the intermediate layer and the central layer with the assembly formed by the upper substrate and the upper layer, so that the central layer is also in contact with the textured surface of the upper layer.,

[0059] In particular embodiments, the step of forming the stack of layers comprises:- adhering the lower layer to the lower substrate,- obtaining the intermediate layer comprising a smooth surface and an opposite textured surface,- conformally depositing the central layer on the textured surface of the intermediate layer, the deposited central layer comprising a first textured surface in contact with the textured surface of the intermediate layer and a second opposite textured surface,- arranging the upper layer on the upper substrate,- assembling the assembly formed by the lower layer and the lower substrate with the assembly formed by the intermediate layer and the central layer so that the lower layer extends between the smooth surface of the intermediate layer and the lower substrate,- assembling the assembly formed by the lower substrate, the lower layer,the intermediate layer and the central layer with the assembly formed by the upper substrate and the upper layer, so that the central layer is also in contact with the upper layer.,

[0060] In particular embodiments, the upper layer is made of a transparent adhesive material.

[0061] According to a ninth aspect, the invention relates to a method for producing a projection screen comprising the steps of the method for manufacturing glazing according to the invention.

[0062] According to a tenth aspect, the invention relates to a method for producing a projection system comprising the steps of the method for producing the projection screen according to the invention to obtain a projection screen, a step of providing a projector and a step of positioning the upper substrate opposite said projector.

[0063] Other characteristics and advantages of the present invention will emerge from the description given below, with reference to the appended drawings which illustrate an exemplary embodiment thereof without any limiting character.In the figures: schematically represents an example of glazing of the prior art comprising a layered element; schematically a particular embodiment of glazing according to the invention; schematically represents another particular embodiment of glazing according to the invention; schematically represents another particular embodiment of glazing according to the invention; schematically represents another particular embodiment of glazing according to the invention; schematically represents another particular embodiment of glazing according to the invention; schematically represents another particular embodiment of glazing according to the invention; schematically represents a particular embodiment of a projection system according to the invention; schematically represents, in the form of a flowchart, the main steps of a method for manufacturing glazing according to the invention; schematically represents a particular mode of implementation of the method of the; schematically represents an even more particular mode of implementation of the method of the. Description of embodiments

[0064] Several particular embodiments of the invention are presented below. More specifically, particular embodiments of glazing according to the invention are first described, then particular embodiments of manufacturing processes for such glazing.

[0065] For the remainder of the description, it is considered in no way limiting that the glazings in question are flat. It should however be noted that such provisions are not limiting of the invention, the latter being also able to apply to curved glazings according to similar technical considerations that a person skilled in the art is able to implement.

[0066] Furthermore, throughout the description, a glazing according to the invention is considered to be laid horizontally, with a first face facing downwards defining a lower external surface and a second face, opposite the first face, facing upwards defining an upper external surface. The meanings of the expressions “above” and “below” are thus to be considered in relation to this orientation. The terms “lower” and “upper” are also used here in reference to this positioning.

[0067] It schematically represents a particular embodiment of a glazing V1 according to the invention.

[0068] In the embodiment of the, the glazing V1 comprises a stack 40 of layers between two substrates: - a lower substrate 20 comprising a smooth lower surface 20_inf (this is the lower external surface V1_inf of the glazing V1), as well as a smooth upper surface 20_sup (this is the surface opposite said lower surface 20_inf), - a transparent upper substrate 30 comprising a smooth upper surface 30_sup (this is the upper external surface V1_sup of the glazing V1), as well as a smooth lower surface 30_inf (this is the surface opposite said upper surface 30_sup).

[0069] The lower surfaces 20_inf, 30_inf and upper surfaces 20_sup, 30_sup are substantially parallel to each other, preferably parallel to each other.

[0070] More particularly, in the embodiment described here, the upper substrate 30 is a transparent (mineral) glass. It should be noted that this glass can, for example, be purely transparent, or both transparent and absorbent.

[0071] Examples of glass substrates that can be used directly as the upper substrate 30 include, in particular, the glass substrates marketed by the company Saint-Gobain Glass in the PLANICLEAR® or DIAMANT® range.

[0072] However, nothing precludes considering an upper substrate 30 made of polymer material. Examples of transparent polymers suitable for the upper substrate 30 include, in particular, polycarbonate and PMMA (acronym for “polymethyl methacrylate”).

[0073] Similarly, in the present embodiment, the lower substrate 20 is a transparent (mineral) glass. Furthermore, the alternatives mentioned above concerning the upper substrate 30 (purely transparent, absorbent and transparent, made of polymer material) still apply for said lower substrate 20. Still other embodiments, in which an opaque lower substrate 20 is envisaged, are described in more detail later.

[0074] An example of a glass substrate that can be used directly as a lower substrate 20 is the glass substrate marketed by the company Saint-Gobain Glass in the PARSOL ULTRA GREY VENUS range (VG10, VG20, VG40).

[0075] It should be noted that no limitation is attached to the dimensions of the lower 20 and upper 30 substrates. Thus, by way of example, said lower 20 and upper 30 substrates may have (depending on the application envisaged) a thickness of between 1.1 mm and 12 mm, more particularly between 1.6 mm and 6 mm, even more particularly between 1.6 mm and 2.6 mm, or even for example substantially equal to, or equal to, 2 mm (the thickness being counted vertically in the plane of the).

[0076] The layered stack 40 comprises two dielectric layers, a lower layer 41 and an upper layer 42.

[0077] As illustrated by the, the lower layer 41 is made of a first layer made of transparent adhesive material, called the “first OCA layer” (the term “OCA” being the acronym for “Optical Clear Adhesive” in English literature). It should be noted that the transparent nature of said adhesive material does not exclude the possibility, according to more specific examples of embodiment, of it also being absorbent.

[0078] Furthermore, said first OCA layer 41 is in contact at a smooth interface with the lower substrate 20. In other words, said first OCA layer 41 comprises a smooth lower surface 41_inf in contact with the upper surface 20_sup of the lower substrate 20. Said first OCA layer 41 also comprises a smooth upper surface 41_sup opposite said lower surface 41_inf.

[0079] In a manner known per se, the term "OCA" designates a set of polymeric materials which, in the case of the present invention, are therefore used as transparent adhesives. Examples of polymeric materials suitable for said first OCA layer 41 include, in particular, polyurethane, preferably thermosetting polyurethane, polyepoxide, polysiloxane, polyacrylate, polyester, etc.

[0080] Furthermore, said first OCA layer 41 has, for example, a thickness of between 200 µm and 250 µm. Such thickness values ​​are, however, not limiting of the invention. More generally, no limitation is attached to the dimensions of said first OCA layer 41.

[0081] The upper layer 42, for its part, is made of polyurethane, and is in contact at a smooth interface with the upper substrate 30. In other words, said upper layer 42 comprises a smooth upper surface 42_sup in contact with the lower surface 30_inf of the upper substrate 30. The thickness of said upper layer 42 is for example between 0.2 mm and 0.8 mm.

[0082] It should be noted that considering an upper layer 42 made of polyurethane constitutes only one implementation variant of the invention. Thus, nothing excludes considering other variants, in particular an upper layer 42 made of transparent adhesive material OCA, or even of PVB (acronym for the expression “polyvinyl butyral”), EVA (acronym for the expression “ethylene-vinyl acetate”), etc. More particularly, PVB or EVA for the upper layer 42 are particularly suitable in the case where the glazing according to the invention comprises a dark enamel or a dark paint, and is intended for the manufacture of an opaque screen, as described in more detail later.

[0083] As illustrated by the, the layered stack 40 also comprises an intermediate layer 43 made of a polymer material, and in contact at a smooth interface with said first OCA layer 41. In other words, said intermediate layer 43 comprises a smooth lower surface 43_inf in contact with the smooth upper surface 41_sup of the first OCA layer. In addition, said intermediate layer 43 has a refractive index that is substantially identical, preferably identical, to that of the upper layer 42.

[0084] In the embodiment described here, said intermediate layer 43 is made of PMMA and has, for example, a thickness of between 50 µm and 250 µm. However, nothing precludes considering other materials for the production of said intermediate layer 43, such as, for example, polycarbonate. Still other examples of suitable materials for said intermediate layer 43 include, in particular, polyesters such as polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polyethylene naphthalate (PEN); polyacrylates such as polymethyl methacrylate (PMMA); polycarbonate; polyurethane; polyamides; polyimides, cellulose triacetate (TCA), etc.

[0085] As illustrated by the, the layered stack 40 also comprises a central layer 44 in contact according to a textured interface with each of said intermediate 43 and upper 42 layers. In other words, the intermediate layer 43 (respectively the upper layer 42) comprises a textured surface 43_tx opposite the lower surface 43_inf (respectively a textured surface 42_tx opposite the upper surface 42_sup) with which the central layer 44 is in contact.

[0086] Said central layer 44 is configured so that the glazing V1 has diffuse reflection properties. For this purpose, said central layer 44 is formed either by a single layer which is a metal layer or a dielectric layer with a refractive index different from that of said intermediate 43 and upper 42 layers, or by a stack of layers which comprises a metal layer or at least one dielectric layer with a refractive index different from that of said intermediate 43 and upper 42 layers.

[0087] Examples of central layers that can be interposed between the intermediate layer 43 and the upper layer 42 include thin dielectric layers, chosen from oxides, nitrides or halides of one or more transition metals, non-metals or alkaline earth metals, in particular layers of Si3N4, SnO2, ZnO, ZrO2, SnZnO x, AlN, NbO, NbN, TiO2, SiO2, Al2O3, MgF2, AlF3, or thin metallic layers, including layers of silver, gold, copper, titanium, niobium, silicon, aluminum, nickel-chromium alloy (NiCr), stainless steel, or alloys of these metals.

[0088] The texture patterns of each of the textured surfaces 42_tx, 43_tx (and also of the contact surfaces between layers when the central layer 44 is formed by a stack of layers) may be distributed randomly over the surface concerned. Alternatively, said texture patterns may be distributed periodically over the surface concerned. These patterns may be, in particular, cones, pyramids, grooves, ribs, wavelets.

[0089] It is also important to note that said central layer 44 can be deposited on only a portion of the textured surface 43_tx of the intermediate layer 43.

[0090] The configuration details of the central layer 44 are not described further here, since they are already set forth in numerous prior art documents. In this respect, it is possible to consult, for example, the document WO2012104547A1 already mentioned previously.

[0091] Other particular embodiments of glazing according to the invention are now described using other figures. The reference numbers used in these other figures, which are identical to those introduced previously, represent similar or identical elements.

[0092] Schematically represents another particular embodiment of a glazing V2 according to the invention, in which the lower layer 41 is also made up of an OCA layer, the lower substrate 20 being an opaque glass.

[0093] More particularly, in the embodiment of the, the lower substrate 20 is a glass whose upper surface 20_sup is covered with a dark black enamel or a dark paint (example: a lacquer) 50, for example black, dark gray, etc.

[0094] It should be noted that, in the example of the, the dark enamel or the dark paint 50 completely covers the upper surface 20_sup. However, nothing precludes considering other examples in which the dark enamel or the dark paint 50 only partially covers said upper surface 20_sup, such arrangements typically being advantageously applied in the field of automotive or transport glazing.

[0095] Schematically represents another particular embodiment of V3 glazing according to the invention.

[0096] In the embodiment of the, the lower layer 41 is also made of an OCA layer and the lower substrate 20 is an opaque glass. However, the glazing V3 differs from the glazing V2 of the in that, in this case, the dark enamel or dark paint 50 covers the lower surface 20_inf of said lower substrate 20.

[0097] Schematically represents another particular embodiment of V4 glazing according to the invention.

[0098] In the embodiment of the, the lower layer 41 is also made of an OCA layer. However, the glazing V4 differs from the glazing V2 of the and from the glazing V3 of the in that the upper surface 41_sup of the first OCA layer 41 is covered with a dark enamel or a dark paint 50 (in this case, the dark enamel or the dark paint 50 is included in the stack of layers 40).

[0099] It schematically represents another particular embodiment of V5 glazing according to the invention.

[0100] In the embodiment of the, the glazing V5 differs from the glazing V1 of the in that the lower layer 41 is no longer only made up of an OCA layer, but here comprises: - a first OCA layer 41_OCA1 in contact along a smooth interface with the intermediate layer 43. In other words, the first OCA layer 41_OCA1 comprises a smooth upper surface 41_OCA1_sup in contact with the smooth lower surface 43_inf of the intermediate layer, - a second layer made of transparent adhesive material, called "second OCA layer" 41_OCA2, and in contact along a smooth interface with the lower substrate 20. In other words, said second OCA layer 41_OCA2 comprises a smooth lower surface 41_OCA2_inf in contact with the upper surface 20_sup of the lower substrate 20.

[0101] Furthermore, in the embodiment of the, the lower layer 41 of the glazing V6 also comprises a so-called “intermediate” glass sheet 41_GL in contact at a smooth interface with each of said first and second OCA layers 41_OCA1, 41_OCA2. In other words, said intermediate sheet 41_GL comprises a smooth lower surface 41_GL_inf (respectively a smooth upper surface 41_GL_sup) in contact with the upper surface 41_OCA2_sup of the second layer OCA2 (respectively with the lower surface 41_OCA1_inf of the first layer OCA1).

[0102] Said intermediate sheet 41_GL is an active film, for example an electrochromic active film (for example an electrochromic active film based on anisotropic particles or liquid crystals to which dichroic dyes are added).

[0103] The invention has been described so far with reference only to the modes of Figures 2 to 6. It is important to note, however, that these modes are not restrictive of the invention, and nothing precludes the consideration of others. In particular, any technically operative combination of the modes of Figures 2 to 6 may be considered within the meaning of the present invention.

[0104] Furthermore, the invention does not only relate to glazing as described above. Thus, according to other aspects, the invention also relates to a projection screen comprising such glazing.

[0105] To this end, it may be noted that the implementation of such a screen is particularly suitable (but not restricted) to modes where the lower substrate 20 is an absorbent glass, as well as to modes where the lower substrate 20 is an opaque glass and / or the screen is a black screen due to the use of a dark paint or a dark enamel (the technical effect achieved is a strengthening of the contrast of the projected image).

[0106] The invention also relates to a projection system 100. A particular embodiment of such a projection system 100 is represented schematically, and in no way limiting, by the.

[0107] As illustrated by the, said projection system 100 comprising a projection screen 110 according to the invention. More particularly, in the mode described here, the projection screen 110 comprises a glazing V2 such as that described with reference to the.

[0108] The projection system 100 also comprises a projector 120, of a design known per se. The relative positions of the projector 120 and the projection screen 110 are such that the upper substrate 30 of the glazing integrated into the projection screen 110 is positioned opposite the projector 120 (the images are therefore projected onto said upper substrate 30).

[0109] It should be noted that, within the meaning of the present invention, a projection system refers not only to an assembly in which the screen and the projector are positioned relative to each other so as to allow the projection of images, but also to an assembly in the form of a kit whose elements, namely the screen and the projector, are to be positioned in order to allow the projection of images.

[0110] Of course, a projection system 100 as described previously can be used to project images, by implementing a projection method according to the invention (not illustrated in the figures).

[0111] The use of the glazing according to the invention is not, however, limited to that of a projection screen. Thus, the glazing according to the invention can be used for all known glazing applications, such as for vehicles, buildings, street furniture, interior furnishings, lighting, display screens, etc.

[0112] The glazing according to the invention can also be used in a head-up display system known as “HUD” (acronym for the Anglo-Saxon expression “Head Up Display”).

[0113] By "HUD" is meant a system for displaying projected information onto a window, usually the windshield of a vehicle, which is reflected back to the driver or observer. Such HUD systems are particularly useful in airplane cockpits, trains, but also today in private motor vehicles (cars, trucks, etc.). These systems make it possible to inform the driver of the vehicle without the driver having to move his or her gaze away from the field of vision in front of the vehicle, which greatly increases safety.

[0114] Embodiments of a method for manufacturing glazing according to the invention will now be described.

[0115] It represents, in the form of a flowchart, the main stages of the said manufacturing process.

[0116] As illustrated by the, the manufacturing method comprises a step E10 of obtaining the lower 20 and upper 30 substrates.

[0117] The manufacturing method further comprises a step E20 of forming the stack of layers 40 between the lower 20 and upper 30 substrates.

[0118] Once the assembly formed by the lower 20 and upper 30 substrates as well as by the stack of layers 40 is obtained, the manufacturing method comprises a step E30 of autoclave lamination of said assembly.

[0119] By way of non-limiting example, when the upper layer 42 is made of polyurethane, said autoclave cycle is carried out under temperature conditions of between 80°C and 100°C, preferably between 85°C and 95°C, and under pressure conditions of between 6 and 10 bars, in particular substantially equal to, or equal to, 6 bars.

[0120] According to another example, when the upper layer 42 is made of transparent OCA adhesive material, said autoclave cycle is carried out under temperature conditions between 30°C and 50°C, and under pressure conditions substantially equal to, or equal to, 5 bars.

[0121] It represents, in the form of a flowchart, a particular method of implementing the process.

[0122] More particularly, in the embodiment, the glazing manufactured is a glazing in which the upper layer 42 is made of transparent OCA adhesive material.

[0123] As illustrated by the, the forming step E20 comprises, in the particular embodiment described here:- a deposition E20_1 of the lower layer 41 on the lower substrate 20, so as to be in contact along a smooth interface with said lower substrate 20,- a deposition E20_2 of the intermediate layer 43 on the first layer 41_OCA1, so as to be in contact along a smooth interface with said first layer 41_OCA1,- a texturing E20_3 of the intermediate layer 43 at the surface opposite the smooth interface with the first OCA layer 41_OCA1, so as to form the textured surface 43_tx,- a conformal deposition E20_4 of the central layer 44 on the textured surface 43_tx of the intermediate layer 43,- a deposition E20_5 of the upper layer 42 on the upper substrate 30, so as to be in contact along a smooth interface with said upper substrate 30,- a texturing E20_6 of the upper layer 42 at a surface opposite the smooth interface with the upper substrate 30, so as to form the textured surface 42_tx (of course, the textured surface 42_tx is complementary to the textured surface of the central layer 44, so as to be able to be superimposed), - an assembly E20_7 of the assembly formed by the lower substrate 20, the lower layer 41, the intermediate layer 43 and the central layer 44 with the assembly formed by the upper substrate 30 and the upper layer 42, so that the central layer 44 is also in contact with the textured surface 42_tx of the upper layer 42.,

[0124] It should be noted that, in a manner known per se, the texturing of a surface can be obtained by any known texturing method, for example by embossing the surface of the layer previously heated to a temperature at which it is possible to deform it, in particular by rolling by means of a roller having on its surface a texturing complementary to the texturing to be formed on the layer; by abrasion by means of abrasive particles or surfaces, in particular by sandblasting; by chemical treatment, in particular acid treatment in the case of a glass substrate; by molding, in particular injection molding in the case of a thermoplastic polymer substrate; by etching.

[0125] The conformal deposition of the central layer 44, whether it is single-layer or formed by a stack of several layers, is for example carried out under vacuum, by cathode sputtering assisted by a magnetic field (so-called "magnetron cathode sputtering").

[0126] It is of course possible to consider other specific methods of implementing the manufacturing process, depending on the composition, in terms of layers, of the glazing manufactured.

[0127] Thus, if the glazing manufactured is of the type of that of the, the step E20 of forming the stack of layers 40 can also comprise, before the deposition E20_1 of the lower layer 41 and as illustrated in no way limiting on the, a formation E20_0 of said lower layer 41 comprising:- a deposition E20_0_1 of the second OCA layer 41_OCA2 on the lower substrate 20, so as to be in contact along a smooth interface with said lower substrate 20,- a deposition E20_0_2 of the intermediate glass sheet 41_GL on the second OCA layer 41_OCA2, so as to be in contact along a smooth interface with said second OCA layer 41_OCA2,- a deposition E20_0_3 of the first OCA layer 41_OCA1 on the intermediate glass sheet 41_GL, so as to be in contact along a smooth interface with said intermediate glass sheet 41_GL.

[0128] Furthermore, if a dark enamel or a dark paint is used in accordance with one of the embodiments described above, the manufacturing method then comprises a step of applying said dark enamel or said dark paint.

[0129] The first adhesive layer of the first lower layer 41 is adhesive before the autoclave lamination step.

[0130] According to an exemplary embodiment, the first adhesive layer is an adhesive film.

[0131] The second adhesive layer of the first lower layer 41 is adhesive before the autoclave lamination step.

[0132] According to an exemplary embodiment, the second adhesive layer is an adhesive film.

[0133] The lower surface 41_inf of the lower layer 41 is an adhesive surface and the upper surface 41_sup of the lower layer 41 is an adhesive surface.

[0134] The lower surface 41_inf and the upper surface 41_sup of the lower layer 41 are adhesive before the autoclave lamination step.

[0135] Alternatively, the step of forming the layer stack comprises:- adhering the lower layer 41 to the lower substrate 20,- obtaining the intermediate layer 43 comprising a smooth surface and an opposite textured surface,- conformally depositing the central layer 44 on the textured surface of the intermediate layer 43, the deposited central layer 44 comprising a first textured surface in contact with the textured surface of the intermediate layer 43 and a second opposite textured surface,- arranging the upper layer 42 on the upper substrate 30,- assembling the assembly formed by the lower layer 41 and the lower substrate 20 with the assembly formed by the intermediate layer 43 and the central layer 44 so that the lower layer 41 extends between the smooth surface of the intermediate layer 43 and the lower substrate 20,- assembling the assembly formed by the lower substrate 20,the lower layer 41, the intermediate layer 43 and the central layer 44 with the assembly formed by the upper substrate 30 and the upper layer 42, so that the central layer 44 is also in contact with the upper layer 42.,

[0136] For example, the adhesion of the lower layer 41 to the smooth surface of the intermediate layer 43 and the lower substrate 20 is achieved by pressing the lower layer 41 onto the intermediate layer 43 and the lower substrate 20.

[0137] During the autoclave lamination step, the top layer 42 is textured at a surface opposite the smooth interface with the upper substrate 30 so as to form the textured surface 42_tx.

[0138] In particular, during the autoclave rolling step the lower layer 41 remains flat.

Claims

Glazing (V1, V2, V3, V4, V5) comprising a stack of layers (40) between two substrates, a lower substrate (20) and a transparent upper substrate (30), each substrate having smooth surfaces opposite each other, said stack of layers comprising: - two dielectric layers, a lower layer (41) and an upper layer (42), said lower layer comprising a first layer made of adhesive material, called the "first adhesive layer", said lower and upper layers being respectively in contact via a smooth interface with the lower and upper substrates, - an intermediate layer (43) made of a polymer material, in contact via a smooth interface with said first adhesive layer, and having a refractive index substantially identical, preferably identical, to that of the upper layer,- a central layer (44) in contact via a textured interface with each of said intermediate and upper layers, said central layer being formed either by a single layer which is a metallic layer or a dielectric layer having a refractive index different from that of said intermediate and upper layers, or by a stack of layers which includes a metallic layer or at least one dielectric layer having a refractive index different from that of said intermediate and upper layers. Glazing (V1, V2, V3, V4, V5) according to claim 1, wherein the adhesive material of the first adhesive layer is a transparent adhesive material and the first adhesive layer is called "first OCA layer". Glazing (V1, V2, V3, V4, V5) according to claim 1 or 2, wherein said upper layer (42) is made of transparent adhesive material or polyurethane. Glazing (V1, V2, V3, V4, V5) according to any one of claims 1 to 3, wherein said intermediate layer (43) is made of polymethyl methacrylate or polycarbonate. Glazing (V1, V2, V3, V4, V5) according to any one of claims 1 to 4, wherein the lower substrate (20) is an absorbent and / or transparent glass. Glazing (V1, V2, V3, V4, V5) according to any one of claims 1 to 4, wherein the lower substrate (20) is an opaque glass. Glazing (V2) according to claim 6, wherein at least one of the surfaces of the lower substrate (20) is covered at least in part with a dark enamel or dark paint (50), for example a black enamel or black paint. Glazing (V4) according to any one of claims 1 to 7, wherein the surface of the first adhesive layer interfacing with the intermediate layer (43) is covered at least in part with a dark enamel or dark paint (50), for example a black enamel or black paint. Glazing (V1) according to any one of claims 1 to 8, wherein the lower layer (41) is made up of said first adhesive layer. Glazing (V5) according to any one of claims 1 to 9 taken in combination 2, wherein the lower layer (41) comprises: - a second layer (41_OCA2) made of transparent adhesive material, referred to as "second OCA layer", and in contact via a smooth interface with the lower substrate (20), - a glass sheet (41_GL) referred to as "intermediate" in contact via a smooth interface with each of said first (41_OCA1) and second OCA layers, said intermediate sheet being an active film, for example an electrochromic active film. Projection screen (110) comprising a glazing (V1, V2, V3, V4, V5) according to any one of claims 1 to 10. Projection system (100) comprising a projection screen (110) according to claim 11 and a projector (120), the upper substrate (30) being intended to be positioned opposite said projector. Projection method implemented by means of a projection system (100) according to claim 12. Use of glazing (V1, V2, V3, V4, V5) according to any one of claims 1 to 10 as all or part of glazing for vehicles, buildings, street furniture, interior furnishings, display screens, Head Up Display systems. A method for manufacturing a glazing (V1, V2, V3, V4, V5) according to any one of claims 1 to 10, said method comprising the steps of: - obtaining (E10) two substrates, a lower substrate (20) and a transparent upper substrate (30), each substrate having smooth surfaces opposite each other, - forming (E20) a stack of layers (40) between the lower and upper substrates, said stack of layers being adapted for the manufacture of said glazing, - autoclave lamination (E30) of the assembly formed by the lower and upper substrates and by the stack of layers. A method according to claim 15, wherein said formation step comprises: - a deposition (E20_1) of the lower layer (41) onto the lower substrate (20), - a deposition (E20_2) of the intermediate layer (43) onto the first adhesive layer, - a texturing (E20_3) of the intermediate layer on a surface opposite the smooth interface with the first adhesive layer, - a conformal deposition (E20_4) of the central layer (44) onto the textured surface of the intermediate layer, - a deposition (E20_5) of the upper layer (42) onto the upper substrate (30), - a texturing (E20_6) of the upper layer (42) on a surface opposite the smooth interface with the upper substrate, - an assembly (E20_7) of the assembly formed by the lower substrate, the lower layer, the intermediate layer and the central layer with the assembly formed by the upper substrate and the upper layer,so that the middle layer is also in contact with the textured surface of the top layer. A method according to claim 15, wherein said formation step comprises: - the adhesion of the lower layer (41) to the lower substrate (20), - the formation of the intermediate layer (43) comprising a smooth surface and an opposing textured surface, - the conformal deposition of the central layer (44) onto the textured surface of the intermediate layer (43), the deposited central layer (44) comprising a first textured surface in contact with the textured surface of the intermediate layer (43) and a second opposing textured surface, - the arrangement of the upper layer (42) onto the upper substrate (30), - the assembly of the assembly formed by the lower layer (41) and the lower substrate (20) with the assembly formed by the intermediate layer (43) and the central layer (44) such that the lower layer (41) extends between the smooth surface of the intermediate layer (43) and the lower substrate (20),the assembly of the set formed by the lower substrate (20), the lower layer (41), the intermediate layer (43) and the central layer (44) with the set formed by the upper substrate (30) and the upper layer (42), such that the central layer (44) is also in contact with the upper layer (42). Method (200) according to claim 16 or 17, wherein the upper layer (42) is made of a transparent adhesive material. Method for making a projection screen (110) comprising the steps of the glazing manufacturing process according to any one of claims 15 to 18. Method of making a projection system (100) comprising the steps of the method of making the projection screen according to claim 19 to obtain a projection screen, a step of supplying a projector (120) and a step of positioning the upper substrate (30) opposite said projector.

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