Multilayer polychromatic light module with a stack of multiple electroluminescent films

Abstract

The invention relates to a light module (1) comprising: a stack of n flexible superimposed electroluminescent films (2A, 2B,... 2n), where n ≥ 2, and wherein the last electroluminescent film (2n) is located above the first (2A), and each comprising: • a flexible support layer (5); and • an intermediate layer (6) located on the support layer (5) comprising multiple electroluminescent elements (7); - a transparent protective layer (3) located on the intermediate layer (6) of the last electroluminescent film; - a pair of electrical connection elements (4a, 4b) connected to each electroluminescent element (7) and connected to a power supply (15); wherein - each electroluminescent film after the first comprises at least one transparent exposure portion (T) without any electroluminescent elements that is positioned and dimensioned such that electroluminescent elements of an electroluminescent film are not masked by an electroluminescent element belonging to an electroluminescent film located above.

Description

DESCRIPTION TITLE: Multi-layer, polychrome light module with superposition of several electroluminescent films TECHNICAL FIELD OF THE INVENTION

[0001] The technical field of the invention is that of polychrome light modules.

[0002] The present invention applies in particular, but not exclusively, to the display of static, dynamic or animated information from polychrome light patterns generated by electroluminescent films. TECHNOLOGICAL BACKGROUND OF THE INVENTION

[0003] Nowadays, it is known to use screens, such as LCD screens, to create such displays in many equipment, for signaling, information, aesthetic purposes of personalization or creating an atmosphere.

[0004] However, such technology is not only expensive, but also sensitive to environmental conditions such as temperature, humidity or UV radiation.

[0005] Furthermore, these screens are not very flexible and therefore cannot be integrated into any type of equipment.

[0006] There is therefore a need for a flexible light module capable of producing a polychrome display or animation, and being robust, inexpensive and easy to integrate into any type of equipment.

[0007] Advantageously, such a flexible and polychrome light module can also be transparent.

[0008] Advantageously, such a flexible and polychrome luminous film is also transparent. SUMMARY OF THE INVENTION

[0009] The invention offers a solution to the problems mentioned above, by providing a light module, preferably transparent, comprising several electroluminescent films each comprising at least one layer of electroluminescent elements capable of each emitting a color different from those of the i electroluminescent films, the light module being thin, flexible and very bright when powered by alternating current.

[0010] One aspect of the invention relates to a light module comprising: a stack of n flexible electroluminescent films superimposed on each other, such that n > 2, such that the set of n electroluminescent films comprises a first and a last electroluminescent film, with the last electroluminescent film being located above the first electroluminescent film; each electroluminescent film comprising: a flexible support layer, and a flexible intermediate layer located on the support layer and comprising several distinct electroluminescent elements, spaced longitudinally and laterally in a plane of the electroluminescent film and electrically insulated from each other; a flexible and transparent protective layer located on the intermediate layer of the last electroluminescent film;a pair of electrical connection elements per electroluminescent element, comprising a first and a second electrical connection element each electrically connected to the electroluminescent element and each adapted to be connected to an alternating current power supply; wherein each electroluminescent film at least after the first comprises at least one transparent exposure portion devoid of electroluminescent element, positioned longitudinally and laterally contiguous in the plane of the electroluminescent film to at least two electroluminescent elements, and dimensioned such that electroluminescent elements of an electroluminescent film are not masked by an electroluminescent element belonging to an electroluminescent film located above.;

[0011] The use of superimposed electroluminescent films having transparent exposure parts revealing the electroluminescent elements of the lower films advantageously allows for a polychrome display or animation, particularly in the case where each film is designed to emit a different color. The use of flexible electroluminescent films also allows for a flexible light module to be obtained, therefore adaptable to numerous functionalities, to be able to be applied to complex concave and / or convex surfaces, its integration into any type of equipment being facilitated. In addition, the power consumption of electroluminescent films is more than three times lower than that of LEDs.

[0012] According to one aspect of the invention, for at least one electroluminescent film, an electroluminescent element successively comprises: a first flexible electrode layer made of conductive material, located on the flexible support layer of said electroluminescent film; a flexible electrically insulating layer made of dielectric material, located on the first electrode layer; a flexible electroluminescent layer located on the electrically insulating layer and comprising a phosphor layer having a refractive index rn U m; and a second flexible and transparent electrode layer made of conductive material having a neiec refractive index and located on the electroluminescent layer.

[0013] This type of electroluminescent element advantageously has a very high luminosity, allowing it to contrast with ambient light. In addition, it is advantageously robust, inexpensive and easy to implement. Finally, the nature and low thickness of each of the electroluminescent elements allow it to be thin and flexible, but they can also allow it to be completely transparent.

[0014] According to another aspect of the invention, at least one electroluminescent layer also comprises at least one refractive index matching element having a refractive index n ng such that nium > n ng > néiec. Thus, since light travels preferentially in the neighboring material with the nearest lower refractive index, the light emitted by the phosphor layer passes primarily through the material of the adaptation element of the refractive index, then passes through the second electrode layer to be emitted towards the top of the electroluminescent element. The refractive index of the matching element being intermediate between that of the adjacent layers for which it serves as an interface, its presence advantageously reduces any effect of refraction and / or reflection of light coming from the phosphor layer towards the second electrode layer.

[0015] According to a further aspect of the invention, at least one layer of phosphor comprises zinc sulfide doped with at least one metal including copper. Indeed, this type of phosphor is advantageously very bright and can in particular provide all the lighting colors of the visible spectrum.

[0016] According to one aspect of the invention, within the same electroluminescent film, the phosphor layers emit a different color from those of the other electroluminescent film(s). Thus, each electroluminescent film of the light module can advantageously generate light patterns of a certain color, and the superposition of the electroluminescent films then makes it possible to display a polychrome image element.

[0017] According to another aspect of the invention, each support layer, each first electrode layer, each electrically insulating layer and each phosphor layer are transparent. Thus, all layers of the films are transparent, which advantageously makes it possible to provide a completely transparent electroluminescent film assembly.

[0018] According to a further aspect of the invention, for electroluminescent elements, the pair of electrical connection elements associated with a electroluminescent element is supplied with electricity independently of the other electroluminescent elements. The selective excitation of at least one electroluminescent element advantageously makes it possible to produce images or animations based on light patterns with a very great freedom of shapes and dimensions, these images or animations being defined by the light patterns produced by the electroluminescent elements supplied with electricity, each light pattern being able to be an element of an image or an animation.

[0019] According to one aspect of the invention, for electroluminescent elements, the pair of electrical connection elements associated with an electroluminescent element is supplied with electricity via a control unit connected to the power supply. Thus, the control unit can advantageously control the light patterns and therefore the image elements defined by the electroluminescent elements depending on whether the control unit supplies them with electricity or not, which in particular allows the creation of displays and animations based on image elements formed from light patterns.

[0020] According to another aspect of the invention, within at least one electroluminescent film, the space E located between neighboring electroluminescent elements is occupied by a flexible insulating material made of dielectric material. Thus, such an electroluminescent film is more homogeneous, has no hollow volume and the electroluminescent elements it comprises are better immobilized and protected.

[0021] According to a further aspect of the invention, within at least one electroluminescent film, the space E located between neighboring electroluminescent elements is occupied by polyethylene terephthalate, polymerized silicon monoxide-based siloxane, polymethyl methacrylate, polycaprolactone, polycarbonate, cycloolefin polymer or by a mixture of at least two of these products. Indeed, these materials are advantageously flexible and transparent insulating materials.

[0022] According to one aspect of the invention, within at least one electroluminescent film, the space E located between neighboring electroluminescent elements is occupied by the same material as that forming the protective layer. Thus, in addition to the advantages provided by a flexible insulating material made of dielectric material, the manufacture of the electroluminescent film is simplified and less expensive.

[0023] According to another aspect of the invention, electroluminescent elements have a top face in the form of a dot, a circle, an oval, a chevron, an oblong, a square, a rectangle, a triangle, a star, a cross, a diamond, a polygon, a honeycomb, an alphanumeric character, or in the form of a combination of two or more of these patterns. In this way, the light patterns generated by the electroluminescent elements can have any shape, and their combination makes it possible to generate any displays and animations.

[0024] According to a further aspect of the invention, electroluminescent elements are arranged in a matrix of pixels. Thus, these electroluminescent elements make it possible in particular to generate matrix digital displays and animations.

[0025] According to one aspect of the invention, electroluminescent elements each have an upper face whose surface area is between 5 mm 2 and 1 cm 2 These dimensions correspond to large electroluminescent elements, for example deposited on the support layer using a bar coating technique, this deposition technique advantageously having low manufacturing costs.

[0026] According to another aspect of the invention, electroluminescent elements each have an upper face whose surface area is between 100 pm 2 and 10000 pm 2These dimensions correspond to small electroluminescent elements, for example deposited on the support layer using an atomic thin film deposition (ALD) technique, this deposition technique advantageously offering the possibility of manufacturing electroluminescent elements with precisely controlled dimensions, even in the micrometer range.

[0027] According to a further aspect of the invention, at least one protective layer comprises a transparent anti-UV material, an anti-UV additive or a transparent anti-UV coating. Thus, in addition to its role of protection against the environment, the protective layer also protects the film against the effects of ultraviolet radiation.

[0028] According to one aspect of the invention, at least one protective layer comprises a layer of transparent anti-UV material selected from an acrylic resin, a mixture of high-density polyethylene and zinc oxide, polycarbonate, polyamide-imide and poly(vinylidene fluoride). These materials have a very effective anti-UV protection effect, and they can therefore be provided in a very thin layer contributing to the flexibility and transparency of the film.

[0029] Another aspect of the invention relates to a vehicle element, which is at least partially covered by a light module as described previously Such an element can thus be decorated with light patterns presenting all the freedoms of shapes and dimensions offered by the invention.

[0030] According to one aspect of the invention, said element is a bodywork part, a dashboard, a decorative part, a grille, a logo or an optical element. Thanks to the invention, it is advantageously possible to provide light patterns on these elements, which car manufacturers usually seek to make visually attractive.

[0031] The invention and its various applications will be better understood by reading the following description and examining the accompanying figures. BRIEF DESCRIPTION OF THE FIGURES

[0032] The figures are presented for information purposes only and do not limit the invention in any way. For reasons of readability of the figures, the size scales between the elements represented are not respected.

[0033] [Fig. 1] is a partially exploded schematic representation of an example of a light module according to the invention comprising two electroluminescent films in which the space E located between electroluminescent elements is empty.

[0034] [Fig. 2] is a schematic perspective representation of an example of a light module according to the invention comprising two electroluminescent films in which the space E located between electroluminescent elements is empty.

[0035] [Fig. 3] is a view similar to [Fig. 2], but in which the space E between electroluminescent elements is occupied by a flexible insulating material of dielectric material.

[0036] [Fig. 4] is a view similar to [Fig. 2], but in which the space E between electroluminescent elements is occupied by the same material as that forming the protective layer and the support layer.

[0037] [Fig. 5] is a schematic and simplified detail view of the part circled in [Fig. 1].

[0038] [Fig. 6] is a detail view of the circled portion in [Fig. 5] in the case where the electroluminescent layer comprises a phosphor layer located on the electrically insulating layer and a refractive index matching element layer located on the phosphor layer.

[0039] [Fig. 7] is a detail view of the circled portion in [Fig. 5] in the case where the electroluminescent layer comprises a heterogeneous layer comprising refractive index matching elements located on the electrically insulating layer and embedded in a phosphor layer.

[0040] [Fig. 8] is a schematic top face view of an exemplary light module according to the invention in which the light-emitting elements form a square pattern pixel matrix, with some light-emitting elements being off and appearing black while others are powered and appearing white, light gray or dark gray to display the number "12345".

[0041] [Fig. 9] is a schematic top face view of an example of a light module part according to the invention in which the light-emitting elements form a matrix of pixels in nested round and diamond patterns, with some light-emitting elements being off and appearing black while others are powered and appearing white or gray to display a smiley face emoticon. DETAILED DESCRIPTION

[0042] Unless otherwise specified, the same element appearing in different figures has a single reference.

[0043] By convention, in the present application, the terms "lower" and "upper", and "above" and "below" are defined with respect to the position of the light module as shown in [Fig. 1 ] to [Fig. 4]. Thus, an upper layer such as the protective layer is shown in the upper portion of the light module in [Fig. 1 ] to [Fig. 4] while a lower layer, such as the support layer of the first electroluminescent film, is shown in the lower portion of the light module, even if the light module can be used in another orientation, for example substantially vertically.

[0044] In the context of the invention, a material or a layer of material is said to be flexible if the mechanical and electrical properties of the film remain unchanged even under a significant stress of 2.5% with a concave radius of curvature and convex of 0.5 mm. In other words, an electrode layer on the support layer can be considered flexible if, after a deformation of 2.5%, this deformation has no impact on the variation of the electrical resistance of the electrode film deposited on the support layer. The deformation (flexibility) can be evaluated using the following equation:

[0045] Strain = ( ts - tp - tf ) / 2 x rc, where: ts is the thickness of the support layer; tp is the total thickness of the working layers (luminescent layer + electrically insulating layers) tf is the total thickness of the electrode layers rc is the radius of curvature.

[0046] Finally, the term "transparent" means an optically transparent material, i.e. one with a transmittance greater than 75% in the visible spectrum.

[0047] The light module 1 according to the invention comprises a set of n electroluminescent films 2A, 2B, ... 2 n superimposed on each other with n > 2, a flexible and transparent protective layer 3 located on top of the last electroluminescent film 2 n , and a set of pairs of electrical connection elements 4a and 4b. The light module 1 is preferably flexible. It can also be transparent.

[0048] In [Fig. 1] to [Fig. 4], for the purpose of simplifying said figures, the light module 1 only comprises two electroluminescent films 2A, 2B. It is understood that the light module 1 according to the invention may comprise more electroluminescent films 2. Indeed, the light module 1 preferably comprises three electroluminescent films 2, in particular when it is desired to carry out an additive synthesis of the colors by superimposing several beams of colored lights in order to mix the primary colors.

[0049] In the case where the light module 1 comprises three electroluminescent films 2, one electroluminescent film emits the red color, another the green color and yet another the blue color, in order to produce a display of the type RGB, where the addition of these three colored lights in suitable proportions gives the color white, while the color black is obtained by the absence of light.

[0050] Other color combinations are also possible depending on the phosphors used in the different electroluminescent films 2 and the number of electroluminescent films 2 .

[0051] Each electroluminescent film 2 is preferably flexible. As illustrated in [Fig. 5], each electroluminescent film 2 comprises several flexible and superimposed layers, where each layer is in contact with the adjacent layer(s), namely a flexible support layer 5, a flexible intermediate layer 6 comprising electroluminescent elements 7, and a flexible protective layer. However, the protective layer of an electroluminescent film 2 is usually constituted by the support layer 5 of the electroluminescent film 2 located immediately above, while only the last electroluminescent film 2n preferably comprises a protective layer 3 of its own.

[0052] Within each electroluminescent film 2, a first layer, preferably lower, is a flexible support layer 5, on which the other layers are deposited. This support layer 5 is preferably provided in the form of a roll film. It has for example a thickness of between 0.5 and 2.0 mm, preferably between 0.8 and 1.5 mm and more preferably equal to 1.1 mm.

[0053] The support layer 5 may be transparent, in particular when it is desired that the entirety of the light module 1 be transparent. It may also be opaque, for example when the light module 1 is intended to be applied to a surface that is also opaque.

[0054] In particular in the case where this layer is transparent, the support layer 5 is preferably made of PET (polyethylene terephthalate), Plasil (polymerized silicon monoxide-based siloxane), PMMA (polymethyl methacrylate), PCL (polycaprolactone), PC (polycarbonate), COP (cycloolefin polymer) or a mixture of at least two of these products.

[0055] Within each electroluminescent film 2, a second layer is deposited on the support layer 5, namely a preferably flexible intermediate layer 6. This intermediate layer 6 comprises a layer of electroluminescent elements 7. It comprises several separate electroluminescent elements 7, spaced longitudinally and laterally by a space E in the plane of the film, and electrically insulated from each other.

[0056] By electroluminescent elements 7 “spaced longitudinally and laterally” is meant that in the plane where the electroluminescent elements 7 are located, they are all spaced from each other, whether to the right, to the left, in front or behind.

[0057] Each electroluminescent element 7 comprises at least four flexible and superimposed layers, where each layer is in contact with the adjacent layer(s), namely a first flexible electrode layer 8 made of conductive material, a flexible electrically insulating layer 9 made of dielectric material, a flexible electroluminescent layer 10 and a second flexible and transparent electrode layer 11 made of conductive material.

[0058] The first electrode layer 8 is preferably provided in the form of a nanomesh, a metal mesh or a homogeneous flat layer. It is preferably deposited on the support layer 5.

[0059] A nanonet is a net-like nanostructure formed of nanowires in contact with each other and forming a mesh, whether these wires are, for example, intertwined, superimposed, welded or in one piece. A nanowire is a thread-like nanostructure whose diameter is on the nanometric scale, for example, less than 100 nm, and whose length is significantly greater.

[0060] Wire mesh means a net-like structure made up of interlaced, overlapped, welded or single-piece wires, these wires having a diameter of the order of a micron.

[0061] The unitary patterns of the mesh of such a nanonet or metal lattice may for example be squares, rectangles, triangles, rhombuses, hexagons or any other shapes and combinations thereof.

[0062] A homogeneous flat layer means a layer of material that is substantially flat, without significant unevenness in level, the composition and structure of which are substantially the same at all points, and which extends over a surface capable of forming an electrode of the desired surface area, for example substantially equal to the surface area of ​​the support layer 5 where it is desired to form a luminescent film.

[0063] The first electrode layer 8, when provided in the form of a nanonet or a metal mesh, preferably comprises silver nanowires (or AgNWs for Ag nanowires) or copper nanowires (or CuNWs for Cu nanowires).

[0064] It should be noted that wide bandgap nanowires composed of gallium nitride (GaN) or zinc oxide (ZnO) are materials that can also be used for nanowires.

[0065] When provided in the form of a planar layer, the first electrode layer 8 preferably comprises carbon nanotubes, graphene, a metal oxide-based material, a PEDOT [poly(3,4-ethylenedioxythiophene)]-based material, a PEDOT:PSS [poly(3,4-ethylenedioxythiophene) mixed with sodium polystyrene sulfonate]-based material or a PEDOT:TOS [poly(3,4-ethylenedioxythiophene) mixed with tosylate]-based material. Such a planar layer is as homogeneous as possible and usually unstructured.

[0066] The metal oxide materials for the first electrode layer 8 preferably include ITO (indium tin oxide), ZnO (zinc oxide), ZnO:AI (aluminum-doped zinc oxide), TiO2 (titanium dioxide) and SnO2:F (fluorine-doped tin oxide, or FTO).

[0067] The first electrode layer 8 may be transparent or opaque.

[0068] The electrically insulating layer 9 is preferentially deposited on the first electrode layer 8.

[0069] The electrically insulating layer 9 has, for example, a thickness of between 1 and 50 μm. It preferably has a thickness of between 5 and 30 μm, more preferably of between 8 and 15 μm, for example substantially equal to 10 μm.

[0070] The dielectric material of the electrically insulating layer 9 preferably comprises an epoxy resin matrix loaded with titanate particles. alkaline earth metal, which alkaline earth metal is preferably chosen from calcium titanate (CaTiOa), barium titanate (BaTiOa), strontium titanate (SrTiOa), mixed perovskites of barium and strontium titanate type (BaxSr(ix)TiO3, with 0 < x < 1) and a mixture of these products. Preferably x is such that 0 < x < 1.

[0071] The electrically insulating layer 9 may be transparent or opaque.

[0072] The flexible electroluminescent layer 10 is preferentially deposited on the electrically insulating layer 9

[0073] This electroluminescent layer 10 comprises both a phosphor material capable of generating light, and a refractive index matching material capable of directing the light emitted by the phosphor material towards the following upper layers, namely the second electrode layer 11 and the protective layer 3.

[0074] By luminophore we mean here a material comprising electroluminescent pigments emitting white or colored light after receiving energy supplied by an electric field.

[0075] Thus, the electroluminescent layer 10 comprises a phosphor layer 12 having a refractive index rn U m and at least one refractive index matching element 13 having a refractive index n ng so that nium > n ng > néiec where néiec is the refractive index of the second electrode layer 11.

[0076] Since the refractive index of the matching element 13 is intermediate between that of the adjacent layers for which it serves as an interface, its presence reduces the effects of refraction and / or reflection of light coming from the phosphor layer 12 towards the second electrode layer 11.

[0077] Laboratory tests have proven that the addition of the adaptation element 13 in a conventional electroluminescent film multiplies the luminance of the latter by a value between 1.8 and 2. Thus, for an electroluminescent film 2 according to the invention, for which the luminance is optimized, a luminance greater than 1600 cd / m is obtained. 2 , which can even be higher than 2000 cd / m 2 , values ​​which have never been achieved to date for an electroluminescent film.

[0078] According to a first variant of the invention shown in [Fig. 6], the electroluminescent layer 10 comprises two successive layers, namely a phosphor layer 12 located on the electrically insulating layer 9, and an adaptation element layer 13 located on the phosphor layer 12.

[0079] According to a second variant of the invention shown in [Fig. 7], the electroluminescent layer 10 comprises a heterogeneous layer comprising adaptation elements 13 located on the electrically insulating layer 9 and embedded in a phosphor layer 12. According to this second variant of the invention, a layer of adaptation elements 13 can also be located on said heterogeneous layer.

[0080] The phosphor layer 12 has a refractive index rn Um whose value is for example approximately equal to 4. In the context of the invention, each refractive index is measured by method A of standard NF EN ISO 489 of March 2022.

[0081] The phosphor layer 12 comprises zinc sulfide doped with at least one metal including copper.

[0082] By metallic composition doped with a material, we mean here a metallic composition integrating small quantities (generally of the order of ppm) of a material which is introduced into its matrix in order to modify its properties.

[0083] For example, the phosphor layer 12 comprises zinc sulfide, a mixture of zinc sulfide and cadmium sulfide, or a mixture of zinc sulfide, cadmium sulfide, zinc selenide and cadmium selenide. Preferably, either these metal compositions are doped with copper only, or they are doped with copper and with at least one compound selected from the group consisting of yttrium and aluminum garnet, manganese, aluminum, europium and inorganic dyes.

[0084] The color of the light emitted by each phosphor layer 12 depends on its composition. Within the same light module 1, the composition of the phosphor layer 12 may be different from one electroluminescent element 7 to another, which makes it possible to have several colors within the same light module 1.

[0085] The deposition of the phosphor layer 12 is preferably carried out by screen printing, by atomic thin layer deposition (or ALD, for the English Atomic Layer Deposition) or by a sol-gel process.

[0086] Deposition by screen printing or by ALD is preferred in the case of the first variant of the invention, where the electroluminescent layer 10 comprises two successive layers, while deposition by sol-gel process is preferred in the case of the second variant of the invention, where the electroluminescent layer 10 comprises adaptation elements 13 embedded in a phosphor layer 12.

[0087] Screen printing deposition generally makes it possible to provide a layer of phosphor 12 having, for example, a thickness of between 25 and 30 pm because the particles of the layer of phosphor 12 usually have a diameter less than or equal to 29 pm.

[0088] In the case where the deposition of the phosphor layer 12 is carried out by screen printing, the electroluminescent pigments are preferentially bound in an epoxy resin matrix.

[0089] The refractive index matching element 13 is transparent and, when in the form of a layer, the latter is flexible.

[0090] The refractive index matching element 13 has the role of directing the light emitted towards the phosphor layer 12 towards the second electrode layer 11 located above it, so that a greater part of the light emitted by the phosphor layer 12 passes through the second electrode layer 11, for greater brightness of the electroluminescent film 2.

[0091] Thus, the adaptation element 13 has a refractive index n ngwhose value is chosen so as to be between that of the two adjacent layers, namely the phosphor layer 12 and the second electrode layer 11, so as to form an intermediate layer reducing the effects of refraction and / or reflection of light. The refractive index n ng of the refractive index matching element is for example between 2 and 3.5.

[0092] The refractive index adaptation element 13 preferably comprises nano-antennas 14, also known as light nanosensors, or nano-antennas in English.

[0093] These nano-antennas 14 preferably comprise nano-objects, preferably metallic, which promote the movement of light from the phosphor layer 12 to the second electrode layer 11, at a scale lower than the wavelength, so that the adaptation element 13 is also very thin and transparent.

[0094] According to a variant of the invention, the nano-objects may be colloidal nanoparticles, preferably nano-cubes. They may also be three-dimensional elements with a round, oval, triangular, square, rectangular, diamond-shaped, polygonal, etc. section or other polygonal three-dimensional elements, such as tetrahedra, octahedra, dodecahedra, icosahedra, etc.

[0095] A nanoparticle is a nano-object whose three dimensions are on the nanometric scale, that is to say a particle whose nominal diameter is less than approximately 100 nm.

[0096] Colloidal nanoparticles are preferably based on silver, gold, platinum or their mixture.

[0097] In the case of the second variant of the invention, where the electroluminescent layer 10 comprises refractive index adaptation elements 13 embedded in a phosphor layer 12, the nanoparticles are preferably deposited on the electrically insulating layer 9 by a drop deposition process, for example randomly, but so that the nanoparticles are well dispersed, without aggregates and with the most homogeneous density possible on the phosphor layer 12.

[0098] In the case of the first variant of the invention, where the electroluminescent layer 10 comprises two successive layers, the colloidal nanoparticles are preferably embedded in a matrix, for example made of polyvinylpyrrolidone (PVP), or covered with a layer of PVP. This matrix or this layer of PVP has, for example, a thickness of approximately 1 to 10 nm, preferably approximately 3 nm.

[0099] According to another variant of the invention, the nano-objects may be nanofibers, nanotubes, nanofilaments, nanowires, nanorods, nanorods or a mixture of these nano-objects.

[0100] Nanofibers, nanotubes, nanofilaments, nanorods, and nanorods are nano-objects with two similar external dimensions on the nanoscale, less than about 100 nm, and a third dimension that is significantly larger.

[0101] These nano-objects are preferably based on zinc oxide. They are grown, for example, by hydrothermal synthesis from a layer of ZnO seeds directly deposited on the phosphor layer 12 (first variant of the invention) or on the electrically insulating layer 9 (second variant of the invention).

[0102] These nano-objects are preferably arranged in the form of a very dense network of nanowires (NWs), nanofibers, nanotubes, nanofilaments, nanorods and / or nanorods aligned vertically. They preferably have a diameter between 30 and 50 nm and a length between 400 and 500 nm.

[0103] In the case of the second variant of the invention, where the electroluminescent layer 10 comprises refractive index adaptation elements 13 embedded in a phosphor layer 12, the nanoparticles and nanoobjects can for example be deposited in the form of islands, that is to say in the form of small groups of nanoparticles and nano-objects isolated from one another, or in the form of lines, in particular parallel and / or which cross to form a network.

[0104] The refractive index adaptation elements 13, whether embedded in the phosphor layer 12 or in the form of a separate layer, may have a very low height (or thickness in the case of a layer), in particular less than 1 pm.

[0105] In particular, depending on its thickness, the phosphor layer 12 can be transparent, translucent or opaque.

[0106] The second electrode layer 11 made of conductive material is preferably deposited on the electroluminescent layer 10 and is preferably flexible and transparent.

[0107] This second electrode layer 11 may have the same characteristics as the first electrode layer 8.

[0108] It has a refractive index whose value is, for example, approximately equal to 1.5.

[0109] Within the same electroluminescent element 7, the first electrode layer 8 and the second electrode layer 11 may be identical, for example by their nature, their composition, their thickness and / or their deposition method, but they may also be different. However, it is more practical and less expensive for the manufacture of the light module 1 that the first layer and the second electrode layer 8, 11 are identical for all the electroluminescent elements 7 of the same electroluminescent film 2.

[0110] The first and second electrode layers 8, 11 of each electroluminescent element 7 are provided to be connected to an alternating current source in order to form an electrostatic field between them, capable of exciting the phosphor layer 12 provided between these two electrode layers 8, 11.

[0111] Thus, each electroluminescent element 7 is associated with a pair of electrical connection elements 4a, 4b capable of being connected to an alternating current power supply 15, where a first electrical connection element 4a of the pair of electrical connection elements is connected to the first electrode layer 8 and where a second electrical connection element 4b of the pair of electrical connection elements is connected to the second electrode layer 11 of said electroluminescent element 7.

[0112] The light module 1 is characterized in particular in that at least one, preferably each electroluminescent film 2 after the first, comprises at least one transparent exposure part T devoid of electroluminescent element 7 and provided above the electroluminescent elements 7 of the electroluminescent films 2 located below. Thus, each transparent exposure part T devoid of electroluminescent element 7 is positioned and dimensioned so that electroluminescent elements 7 of an electroluminescent film 2 are not masked by an electroluminescent element 7 belonging to an electroluminescent film 2 located above.

[0113] Within each electroluminescent film 2 having transparent exposure parts T, the latter are preferentially positioned contiguous longitudinally and laterally in the plane of said electroluminescent film 2 at least two electroluminescent elements 7.

[0114] Like a window, the transparent exposure parts T can have substantially the same shape as the electroluminescent elements 7 located below in order to leave them clearly visible from the external face, that is to say the upper face, of the light module 1.

[0115] Thus, when considering the light module 1 seen from above, none of the electroluminescent elements 7 is hidden by another electroluminescent element 7.

[0116] Due to the space E between neighboring light-emitting elements, the transparent exposure parts T are generally larger than the light-emitting elements 7 located below. This is the case when all the light-emitting elements 7 of the light module 1 have substantially the same shape and dimensions.

[0117] It will be noted, however, that whether within the same electroluminescent film 2, or within several of them, all the electroluminescent elements 7 of the light module 1 do not necessarily have the same shape and the same dimensions, they may be different, the shape and dimensions of the transparent exposure parts T then being adapted accordingly.

[0118] As described further, each transparent exposure portion T is occupied by a flexible insulating material made of dielectric material. It is preferentially occupied by the same material as that occupying the space E located between neighboring electroluminescent elements.

[0119] Preferably, most of the electroluminescent elements 7 are supplied with electricity independently of the other electroluminescent elements 7. Thus, for these electroluminescent elements 7, the pair of electrical connection elements 4a, 4b associated with them is supplied with electricity independently of those of the other electroluminescent elements 7.

[0120] Thanks to this architecture, each electroluminescent element 7 can be switched on or off individually. By “switched on” electroluminescent element 7, we mean an electroluminescent element 7 whose phosphor layer 12 is luminous due to an excitation provided by an electric field when the first and second electrode layers 8, 11 of said electroluminescent element 7 are supplied with electricity from the alternating current power supply 15 via the first and second electrical connection elements 4a, 3b. By "off" electroluminescent element 7 is meant an electroluminescent element 7 whose phosphor layer 12 is not excited by an electric field.

[0121] When an electroluminescent element 7 is lit, it has a light pattern defined by the shape of its upper face. This pattern contrasts with the electroluminescent elements 7 that are switched off, and with the environment, in particular when the electroluminescent film 2 is entirely transparent.

[0122] The electroluminescent elements 7 may have an upper face of any shape. Thus, the light pattern generated by each of them may, for example, be in the form of a point, a circle, an oval, a chevron, an oblong, a square, a rectangle, a triangle, a star, a cross, a diamond, a polygon, a honeycomb, an alphanumeric character, or in the form of a combination of at least two of these patterns. A light module 1 may comprise electroluminescent elements 7 all having an upper face of the same shape or different shapes. Thus, a part of the light module 1 may comprise electroluminescent elements 7 each capable of forming a light pattern of a certain shape, while one or more other parts of the light module 1 may comprise electroluminescent elements 7 each capable of forming a light pattern of another shape.

[0123] For example, a portion of the light module 1 may comprise electroluminescent elements 7 each capable of forming a round-shaped light pattern, each round shape being arranged substantially at a corner of a square, and electroluminescent elements 7 each capable of forming a diamond-shaped light pattern, each diamond being arranged in the empty space between four neighboring circles, i.e. substantially at the center of the preceding square. Such a portion of the light module 1 is shown in [Fig. 9], which displays a smiley face emoticon consisting of several colors, each generated by the electroluminescent elements 7 of a single electroluminescent film 2, or by the combination of the electroluminescent elements 7 of several electroluminescent films 2.

[0124] The light module 1 comprising several electroluminescent elements 7, it is possible to generate images and / or text by lighting only a part of them, each electroluminescent element 7 forming an image element when it is lit, substantially in the manner of a pixel of a conventional display device.

[0125] According to a preferred embodiment, within the same electroluminescent film 2 the phosphor layers 12 emit a color different from those of the other electroluminescent film(s) 2.

[0126] Thus, by lighting electroluminescent elements 7 of several electroluminescent films 2, the light module 1 can generate polychrome light patterns.

[0127] The greater the number of electroluminescent films 2, the greater the distance between the electroluminescent elements 7 within the same electroluminescent film 2 becomes. However, for a light module 1 comprising two to four electroluminescent films 2, the dimensions of the transparent exposure parts T are sufficiently small so that the greater the distance between the electroluminescent elements 7 does not significantly affect the quality of the images, text and / or animations that can be generated, in particular when the electroluminescent elements 7 have a very small surface area corresponding to “small pixels” (see below).

[0128] According to a preferred embodiment of the invention, at least some of the electroluminescent elements 7 of the light module 1 are arranged in a matrix of pixels.

[0129] As an example, [Fig. 8] illustrates a light module 1 comprising a matrix of 21 x 15 electroluminescent elements 7 whose upper face is square in shape, and of which 50 electroluminescent elements 7 are lit so as to generate the display of an image representing the underlined number 12345. In this figure, the electrical connection elements 4 are represented in the form of a sheet.

[0130] In this example, the odd numbers are in one color, the even numbers in another, and the underline in yet another color. These colors are each preferably generated by the electroluminescent elements 7 of the same electroluminescent film 2, or by the combination of the elements electroluminescent 7 of several electroluminescent films 2. The black color corresponds to the location of switched off electroluminescent elements 7.

[0131] If the light module 1 has a lower black layer, the location of the switched-off electroluminescent elements 7 appears black by transparency. The support layer of the first electroluminescent film 2A may, for example, have such a black layer. This colored layer may also have another color, which will be the visible base color for the switched-off electroluminescent elements 7. It may also be metallized and / or textured depending on the desired aesthetic effect.

[0132] If all the electroluminescent films 2 of the light module 1 are transparent, the location of the switched-off electroluminescent elements 7 remains transparent, which makes it possible, for example, to display images, text and / or animations within a window or any other transparent partition or display element.

[0133] It will be noted that the electrical connection elements 4 may comprise electrical wires, or any other means for conducting electricity. The electrical wires are preferably flexible and transparent. They are for example based on ITO (indium-tin oxide), ZnO (zinc oxide), ZnO:AI (aluminum-doped zinc oxide) or any other conductive electrode material described for the first and second electrode layers 8, 11.

[0134] The electroluminescent elements 7 can have very variable dimensions, including within the same light module 1.

[0135] According to a first preferred embodiment of the invention, for at least a portion of the electroluminescent elements 7, they each have an upper face whose surface is between 5 mm 2 and 1 cm 2, which allows them to be produced at a lower cost, for example using a bar coating technique. These surfaces correspond to what can be referred to as "large pixels".

[0136] According to a second preferred embodiment of the invention, for at least a portion of the electroluminescent elements 7, they each have an upper face whose surface area is between 100 μm 2 (0.0001 mm 2 ) and 10000 pm 2 (0.01 mm 2 ), which allows them to be produced in very small dimensions. precise, for example with an atomic thin layer deposition (ALD) technique. According to this second preferred embodiment of the invention, electroluminescent elements 7 may be in the form of square pixels, each having an upper face having dimensions preferably between 10 x 10 pm and 100 x 100 pm, more preferably approximately 50 x 50 pm, which corresponds approximately to the resolution of the human eye. These electroluminescent elements 7 are for example spaced from each other by a space E between 10 and 50 pm, preferably approximately 25 pm. These areas correspond to what can be referred to as "small pixels".

[0137] Of course, it is possible to produce electroluminescent elements 7 with other surfaces, in particular intermediate ones which then correspond to what can be designated as “average pixels”.

[0138] Within the same electroluminescent film 2, the electroluminescent elements 7 can all generate the same color, but not necessarily. Thus, within the same electroluminescent film 2, electroluminescent elements 7 can generate different colors, the nature of the phosphor layer 12 being different for them.

[0139] According to a preferred embodiment of the invention, the pair of electrical connection elements 4a, 4b associated with at least a portion of the electroluminescent elements 7 is connected to an alternating current power supply 15 via a control unit 16. The main role of this control unit 16 is to control the switching on and off of the electroluminescent elements 7 to which it is connected in order to generate the images, text and / or animations mentioned above.

[0140] The control unit 16 may for example comprise or be connected to a logic unit comprising a processor and / or a memory in order to manage the switching on and off of the different electroluminescent elements 7 over time, as is done for example in conventional display devices.

[0141] The same light module 1 preferably comprises a single control unit 16 allowing centralized control of the display, but it can also comprise several.

[0142] Each control unit 16 can further be connected to a processor, for example associated with a memory, to give instructions to said control unit 16 as to the display to be produced.

[0143] According to a preferred embodiment of the invention, at least some of the electroluminescent elements 7 are distant from each other. According to this embodiment, the smallest value of the space E separating two neighboring electroluminescent elements 7 is between 0.01 and 10 mm, preferably between 0.1 and 5 mm and more preferably between 0.5 and 2 mm.

[0144] According to an embodiment of the invention illustrated in [Fig. 1] and [Fig. 2], for at least a portion of the electroluminescent elements 7, the space E located between neighboring electroluminescent elements 7 and transparent exposure portions T are occupied by vacuum.

[0145] According to another embodiment of the invention illustrated in [Fig. 3], this space E and these transparent exposure parts T are occupied by a flexible insulating material made of dielectric material 17.

[0146] According to a further embodiment, the space E and the transparent exposure parts T are occupied by polyethylene terephthalate, polymerized silicon monoxide-based siloxane, polymethyl methacrylate, polycaprolactone, polycarbonate, cycloolefin polymer or by a mixture of at least two of these products.

[0147] According to yet another embodiment of the invention illustrated in [Fig. 4], the space E and the transparent exposure parts T are occupied by the same material as that forming the support layer 5 and the protective layer 3.

[0148] According to another embodiment of the invention, the space E and the transparent exposure parts T are occupied by the same material as that forming the support layer 5 or that forming the protective layer 3.

[0149] Each electroluminescent film 2 according to the invention finally comprises a flexible and transparent protective layer 3, upper and preferentially deposited on the second electrode layer 11. For the last electroluminescent film 2n, that is to say the electroluminescent film 2 n upper, this protective layer 3 is a layer having the preferential sole role of protecting the upper face of the light module 1. For the other electroluminescent films (2A, 2B, ... 2 n -he has protective layer is formed by the support layer 5 of the electroluminescent film 2 located immediately above.

[0150] This protective layer 3 has, for example, a thickness of between 0.5 and 2.0 mm, preferably between 0.8 and 1.5 mm and more preferably equal to 1.1 mm.

[0151] It is preferably deposited by printing.

[0152] The protective layer 3 is preferably made of PET (polyethylene terephthalate), Plasil (polymerized silicon monoxide-based siloxane), PMMA (polymethyl methacrylate), PCL (polycaprolactone), PC (polycarbonate), COP (cycloolefin polymer) or a mixture of at least two of these products.

[0153] The protective layer 3 preferably comprises a transparent anti-UV material, an anti-UV additive or a transparent anti-UV coating in order to protect the electroluminescent film 2 from the harmful effects of ultraviolet radiation.

[0154] Indeed, the UV protection can be embedded in the mass of the material constituting the protective layer 3, or be in the form of a coating deposited on the lower and / or upper layer of said protective layer 3.

[0155] Similarly, the material constituting the protective layer 3 may naturally have an anti-UV effect, or be modified so as to have such an effect without this significantly negatively affecting its flexibility and transparency.

[0156] Thus, the protective layer 3 comprises, for example, a layer of transparent anti-UV material chosen from an acrylic resin, a mixture of high-density polyethylene and zinc oxide, polycarbonate, polyamide-imide and poly(vinylidene fluoride).

[0157] The following materials are known to have anti-UV action: Plasil anti-UV, PC, PCL, PMMA, PET and COP.

[0158] According to a preferred embodiment of the invention, the support layer 5, each first electrode layer 8, each electrically insulating layer 9 and each phosphor layer 12 are transparent within an electroluminescent film 2. Thus, the electroluminescent film 2 can be entirely transparent. If all the electroluminescent films 2 are transparent, the light module 1 according to the invention can thus constitute or be part of a glazing or any other transparent partition element.

[0159] The light module 1 according to the invention is preferably intended to decorate the interior or exterior of a vehicle, but its applications are innumerable. It can for example be used indoors or outdoors, to decorate a building, furniture, accessories, architectural pieces, clothing, etc.

[0160] It can be placed on a support, for example to decorate it or display information, or it can be positioned at a distance from a support, for example substantially vertically, in order to serve as a display panel.

[0161] Thus, the invention also relates to a vehicle element at least partially covered by a light module 1 according to the invention, this element being for example a bodywork part, a dashboard, a decorative part, a grille, a logo, an optic or any other part of a vehicle.

Claims

CLAIMS

1. Light module (1) characterized in that it comprises: - a stack of n flexible electroluminescent films (2A, 2B, ... 2n) superimposed on each other, such that n > 2, so that the set of n electroluminescent films (2A, 2B, ... 2n) comprises a first and a last electroluminescent film (2A, 2n), with the last electroluminescent film (2n) being located above the first electroluminescent film (2A); each electroluminescent film (2A, 2B, ... 2n) comprising: o a flexible support layer (5), and o a flexible intermediate layer (6) located on the support layer (5) and comprising several distinct electroluminescent elements (7), spaced longitudinally and laterally in a plane of the electroluminescent film (2A, 2B, ... 2n) and electrically insulated from each other; - a flexible and transparent protective layer (3) located on the intermediate layer (6) of the last electroluminescent film (2n); - a pair of electrical connection elements (4a, 4b) per electroluminescent element (7), comprising a first and a second electrical connection elements (4a, 4b) each electrically connected to the electroluminescent element (7) and each adapted to be connected to an alternating current power supply (15); where - each electroluminescent film (2B, ... 2n) at least after the first (2A) comprises at least one transparent exposure part (T) devoid of electroluminescent element (7), positioned longitudinally and laterally contiguous in the plane of the electroluminescent film (2B, ... 2n) to at least two electroluminescent elements (7), and dimensioned such that electroluminescent elements (7) of an electroluminescent film (2A, 2B ... 2n-i) are not masked by an electroluminescent element (7) belonging to an electroluminescent film (2B ... 2 n ) located above.

2. Light module (1) according to claim 1, characterized in that, for at least one electroluminescent film (2A, 2B, ... 2n), an electroluminescent element (7) successively comprises: a first flexible electrode layer (8) made of conductive material, located on the flexible support layer (5) of said electroluminescent film (2A, 2B, ... 2n); a flexible electrically insulating layer (9) made of dielectric material, located on the first electrode layer (8); a flexible electroluminescent layer (10) located on the electrically insulating layer (9) and comprising a phosphor layer (12) having a refractive index rn U m; and a second flexible and transparent electrode layer (11) made of conductive material having a neiec refractive index and located on the electroluminescent layer (10).

3. Light module (1) according to claim 2, characterized in that at least one electroluminescent layer (10) also comprises at least one refractive index matching element (13) having a refractive index Hng such that nium > Hng > Hlect-

4. Light module (1) according to any one of claims 2 to 3, characterized in that at least one layer of phosphor (12) comprises zinc sulfide doped with at least one metal including copper.

5. Light module (1) according to any one of claims 2 to 4, characterized in that, within the same electroluminescent film (2A, 2B, ... 2n), the phosphor layers emit a color different from those of the other electroluminescent film(s) (2A, 2B, ... 2n) n ).

6. Light module (1) according to any one of claims 2 to 5, characterized in that each support layer (5), each first electrode layer (8), each electrically insulating layer (9) and each phosphor layer (12) are transparent.

7. Light module (1) according to any one of the preceding claims, characterized in that, for electroluminescent elements (7), the pair of electrical connection elements (4a, 4b) associated with a light-emitting element (7) is supplied with electricity independently of the other light-emitting elements (7).

8. Light module (1) according to any one of the preceding claims, characterized in that, for electroluminescent elements (7), the pair of electrical connection elements (4a, 4b) associated with an electroluminescent element (7) is supplied with electricity via a control unit (16) connected to the power supply (15).

9. Light module (1) according to any one of the preceding claims, characterized in that, within at least one electroluminescent film (2A, 2B, ... 2n), the space (E) located between neighboring electroluminescent elements (7) is occupied by a flexible insulating material made of dielectric material (17).

10. Light module (1) according to any one of the preceding claims, characterized in that, within at least one electroluminescent film (2A, 2B, ... 2n), characterized in that the space (E) located between neighboring electroluminescent elements (7) is occupied by polyethylene terephthalate, siloxane based on polymerized silicon monoxide, polymethyl methacrylate, polycaprolactone, polycarbonate, cycloolefin polymer or by a mixture of at least two of these products. [Claim 1 1 ] Light module (1 ) according to any one of the preceding claims, characterized in that, within at least one electroluminescent film (2A, 2B, ... 2n), the space (E) located between neighboring electroluminescent elements (7) is occupied by the same material as that forming the protective layer (3).

12. Light module (1) according to any one of the preceding claims, characterized in that electroluminescent elements (7) have an upper face in the form of a point, a circle, an oval, a chevron, an oblong, a square, a rectangle, a triangle, a star, a cross, a diamond, a polygon, a honeycomb, an alphanumeric character, or in the form of a combination of at least two of these patterns.

13. Light module (1) according to any one of the preceding claims, characterized in that electroluminescent elements (7) are arranged in a matrix of pixels.

14. Light module (1) according to any one of the preceding claims, characterized in that electroluminescent elements (7) each have an upper face whose surface is between 5 mm 2 and 1 cm 2 .

15. Light module (1) according to any one of the preceding claims, characterized in that electroluminescent elements (7) each have an upper face whose surface is between 100 pm 2 and 10000 pm 2 .

16. Light module (1) according to any one of the preceding claims, characterized in that at least one protective layer (3) comprises a transparent anti-UV material, an anti-UV additive or a transparent anti-UV coating.

17. Light module (1) according to any one of the preceding claims, characterized in that at least one protective layer (3) comprises a layer of transparent anti-UV material chosen from an acrylic resin, a mixture of high density polyethylene and zinc oxide, polycarbonate, polyamide-imide and poly(vinylidene fluoride).

18. Element for a vehicle, characterized in that it is at least partially covered by a light module (1) according to any one of the preceding claims.

19. Vehicle element according to the preceding claim, characterized in that said element is a bodywork part, a dashboard, a decorative part, a grille, a logo or an optical element.

Images