EP2718100A1

EP2718100A1 - Lighting device comprising light-emitting diodes

Info

Publication number: EP2718100A1
Application number: EP12731120.7A
Authority: EP
Inventors: Anne Gierens; Aude Montgermont; Jingwei Zhang
Original assignee: Saint Gobain Glass France SAS; Compagnie de Saint Gobain SA
Current assignee: Saint Gobain Glass France SAS; Compagnie de Saint Gobain SA
Priority date: 2011-06-09
Filing date: 2012-06-06
Publication date: 2014-04-16
Also published as: CN103582560A; FR2976340A1; CN103582560B; FR2976340B1; WO2012168647A1

Abstract

The invention relates to a lighting device comprising: at least one glass sheet (2, 2A, 2B) having two opposing main faces (20, 21) and a slab (22), light-emitting diodes (3) providing the lighting function, and diffusion means (4) that extract the light on one of the first or second main faces (21). The aforementioned diffusion means define one or more lighting zones and said diffusion means do not form a solid surface covering all of the first glass sheet. The device is characterised in that the diffusion means take the form of an enamel having a brightness greater than 15 and preferably greater than or equal to 20 or 30.

Description

LIGHT EMITTING DEVICE LIGHTING DEVICE

The invention relates to a lighting device using light-emitting diodes as lighting sources.

Light-emitting diodes (LEDs) were originally used to provide warning lamps or indicator lights for electrical and electronic devices, and have already been used for a few years to illuminate signaling devices such as traffic lights. signaling of motor vehicles (position lights), or portable lamps or markers.

Recently, their use has developed for lighting, in particular to replace incandescent halogen bulbs.

Thus, illuminating glazings provided with LEDs are known as a lighting system, the LEDs being arranged on the edge of the glazings. In order to extract the guided light in the glass, the LED lighting device comprises means for diffusing the light provided by sanding or acidifying the glass. However, this implementation weakens the glass, In addition the extraction performance is not always satisfactory or sustainable.

The object of the invention is therefore to propose a new LED-based lighting device on the edge of a glass which, while providing a sufficient luminous efficacy without dazzling, does not have the disadvantages of the prior art as regards its means of light scattering. According to the invention, the lighting device or luminaire comprises at least a first glass sheet having first and second opposite main faces and a wafer, light-emitting diodes providing the lighting function and with coupled light-emitting faces. optically at the edge of the first sheet of glass forming a light guide, and diffusion means ensuring the extraction of the guided light and arranged on one of the first or second main faces, the diffusion means defining one or more zones illuminating, the diffusion means not covering a full surface of the entire face of the first glass sheet, and the diffusion means are an enamel having a gloss greater than 15.

The gloss is measured in a known manner by a reflectometer or gloss meter whose values are expressed in units of gloss.

The illuminating areas are the areas from which light is extracted to the outside of the glass, and corresponding to the enamel and the surface of the glass sheet facing the enamel, while the areas adjacent to the enamel on the same surface of the glass sheet are called dark areas.

Thus, the combination of a lighting by means of LEDs, a lighting of the glass sheet by its edge, and the use of a suitable enamel as means of diffusion and forming one or more illuminating patterns, provides a bright, homogeneous and glare-free illumination.

The enamel surface facing the interior of the glass constitutes a diffuse reflective surface for the light emitted by the edge of the glass and propagating in the thickness of the glass. The light is thus reflected in direction of the face of the glass sheet which is opposite to that provided with the enamel.

The enamel must not cover the entire surface of the glass to ensure homogeneity of the lighting. Also, the light emitted by the LEDs arranged on the edge of the glass is not extracted in its entirety by the closest patterns of the glass wafer, but instead continues to propagate in the thickness of the glass in one direction. parallel to the main faces of the substrate, to the next possible patterns that will provide additional reflection.

Preferably, the enamel has a gloss greater than or equal to 20 or 30. According to one characteristic, the enamel has an optical density of at least 0.6 or even at least 0.8. In known manner, the optical density is measured using a densitometer.

The values of the gloss and / or the optical density of the enamel allow according to the invention to provide a glass surface sufficiently resistant to cleaning and scratching.

The device has a luminance of at least 1000 cd / m ² , preferably at least 2000 cd / m ² or 3000 cd / m ² .

Advantageously, in the illuminating zone or zones (on the opposite side to the enamel face and / or the side of the face with the enamel), the illumination is of the Lambertian type (and not directional, along an axis of propagation of light ). Thus, the luminance has the advantage of being substantially equal regardless of the angle of observation. The chosen enamel generates, in the zone illuminant, a difference in absolute value between the luminance at normal and the luminance at angles between 0 and 45 ° or 60 ° which is less than 30% or even 20% or 10%. According to one feature, when the device comprises only one sheet of glass, the face of the glass sheet provided with the enamel constitutes the face opposite to that forming the main (or even unique) lighting face of the device, the the luminance L2 of the opposite face being at most 0.8 times the luminance L1 of the main illumination face, or even at most 0.6 times the luminance L1.

Advantageously, the enamel is resistant to scratching, in particular is not scratched by applying a tip, for example tungsten carbide diameter 0.75 mm, with a force of 10 N or 20N.

The enamel is also chemically resistant with a cleaning product, including soap, alcohol and ammonia, especially without color change after cleaning especially with a Delta E color difference less than 1, 4.

The formula for the color difference is ΔΕ = / (AL * ² + Δα * ² + Ab * ² ).

When the lighting device is formed of a monolithic glass, its use will rather be for a privileged lighting on one side or on one side, which is the side of the face opposite to that provided with enamel. Indeed, the face provided with the enamel will extract a smaller amount of light than the opposite side, including about two times less. In an alternative embodiment, the lighting device constitutes a multiple glazing unit further comprising a second glass sheet and an internal space between the first and second sheets, the enamel being on the inner face of the first sheet of glass.

In another variant embodiment, the lighting device constitutes a laminated glazing unit comprising the first sheet of glass, a second sheet of glass and an intermediate sheet of plastic material (transparent), the enamel being arranged inside the laminated sheet. on the face of the first sheet of glass which is opposite the plastic sheet, the diodes being for example centered on the edge of the laminated glazing or facing the edge of the first sheet or the second sheet. The laminated glass lighting device is necessary in some applications to meet security needs.

Furthermore, this application of laminated glass-based lighting device may be preferred because providing optimal illumination for light extraction from both sides. Indeed, the inventors have shown that the amount of light extracted is identical for each of the sides of the device from the enamel according to the invention arranged on one of the faces of the glass and associated with the plastic sheet ensuring the foliation. The plastics material of the intermediate sheet is of the known type, for example flexible polyurethane (PU), thermoplastic without plasticizer such as ethylene / vinyl acetate copolymer (EVA), polyvinyl butyral (PVB), a polyethylene copolymer and acrylate for example sold by DuPont under the name of Butacite® or sold by the company Solutia. The plastic sheet has for example a thickness between 0.2 mm and 1.1 mm, in particular 0.38 and 0.76 mm. Other plastics can be used such as polyolefins such as polyethylene (PE), polypropylene (PP) PEN or PVC or ionomer resins.

Preferably, the first glass sheet coated with enamel has a light transmission of less than 45% or even 40% or even 35% measured using a measuring device called "Hazemeter" in English. The thickness of the enamel is adapted, preferably not exceeding 100 μιτι, in order to play its role of reflector for the light without absorbing too much. The thickness will preferably be between 8 μιτι and 40 μιτι, for example of the order of 15 μιτι. The thickness of the glass sheet or sheets is of standard size, of 3 or 4 mm. It can of course be more important for certain applications, and reach thicknesses of the order of 10 or 12 mm.

The enamel extends, preferably over the entire face of the first glass sheet, discontinuously or according to geometric shapes sparse curved lines and / or straight.

Different patterns for affixing enamel to the glass sheet can be imagined. A pattern may be unitary and repeat a plurality of times to cover the entire glass sheet.

The enamel is for example fractal geometry.

According to another characteristic, the enamel extends discontinuously and delimits dark areas including patterns of shapes. geometric sparse with curved lines and / or straight, in particular of length (greater dimension) at least centimeter.

Advantageously, an illuminating zone is a solid enamel (thus a solid zone as opposed to a network of millimeter-point type dot patterns), in particular of length (greater dimension) at least centimeter.

The illuminating zone may cover a part of the surface, thus leaving at least a first dark zone, that is to say non-illuminating, dark zone which is chosen from a transparent zone (clear of glass ...) or an area decorative by an opaque and / or colored coating, in particular or even a reflecting zone including a mirror for example formed by a silver coating covered with an oxidation protection paint ,.

The mirror is, for example, the SGG Miralite product from SAINT-GOBAIN GLASS, with an oxidation protection paint, the silvering of the mirror being disposed on the same face as the enamel or on an opposite face. In a variant, the mirror is based on chromium, such as the SGG Mirastar product from SAINT-GOBAIN GLASS, chromium being on the face of the enamel bearing glass or the face opposite to the enamel-bearing surface.

The maximum width, the width corresponding to the smallest surface dimension of this illuminating area (of any possible shape), may preferably be less than 200 mm or even less than or equal to 100 mm, in particular to leave a large dark area surface. The width is constant or variable. The illuminating zone may be a peripheral zone of one face of the first glass sheet, in particular along at least one edge of the glass surface and according to for example at least one strip or a drawing, while the dark zone is more central (and further away from the diodes), and / or the device has a plurality of illuminating areas distributed on one side of the first sheet of glass.

In the case of a dark zone decor zone, it will be preferable for this zone to be further away from the diodes than the illuminating zone in order to avoid the absorption of light.

Alternatively, the illuminating area may be in a given area of the glass, which is for example a central area, while the dark area may be more peripheral.

The enamel may be a continuous layer on the surface, of width less than 200 mm, even 100 mm and even more preferably less than or equal to 50 mm, or be discontinuous and formed of a set of fine patterns, width (dimension minimum of the pattern) less than 200 mm, or even 100 mm and even more preferably less than or equal to 50 mm.

The patterns are for example geometric: rectilinear or curved strip, concentric circles, L., etc. The patterns are identical or distinct, parallel to each other or not, with a distance between them identical or not.

According to another characteristic, the enamel is white with a clarity L ^* of at least 50. The color of the enamel defined in a known manner by the parameters L ^* , a ^* and b ^* is measured by a spectrocolorimeter. According to one characteristic, the enamel has the following composition between 20 and 60% by weight of SiO ₂ ,

10 to 45% by weight of refractory pigments, in particular of TiO ₂ , in particular of micron size

preferably not more than 20% by weight of alumina and / or zinc oxide.

In a preferred example, the composition is as follows:

between 20 and 60% by weight of SiO ₂ , preferably of the order of 45%,

10 to 45% by weight of TiO ₂ , preferably of the order of 20% not more than 10% by weight of ZnO, preferably of the order of

5%,

not more than 10% by weight of Al ₂ O ₃ , preferably of the order of 3%,

up to 30% by weight of one or more oxides, such as 5 to 25% of Na ₂ O, at most 5% of K ₂ O and at most 5% of CaO

Preferably, the enamel is deposited on the first glass sheet by screen printing and / or ink jet.

The enamel was baked after firing between a temperature between 640 and 710 ° C so that the first glass sheet reached a temperature between 630 and 700 ° C.

It is preferred to adjust the firing temperature to a gloss preferably of at least 15 or even 30 (gloss units).

Advantageously, the diodes are arranged so as to inject light through the edge of the first glass sheet on two sides parallel opposites. Alternatively, the diodes could be arranged on all sides of the glass substrate, in the manner of a frame.

According to another feature of the device, the latter comprises sections provided with housings for fixing the diodes, the sections being arranged facing the wafer and secured to the glass sheet.

Advantageously, the first glass sheet is based on a glass having a high light transmission, of at least 85%, when the measurement is carried out under illuminant D65 on a glass sheet with parallel faces 4 mm thick. Preferably, it will be a so-called extraclear glass, such as DIAMANT® glass or DIAMANT® solar glass marketed by SAINT-GOBAIN GLASS. The glass of the device can be quenched in particular after deposition of the enamel formulation (glass frit, etc.) to present a better mechanical strength.

The enamel can be divided according to one or more patterns designed to provide an aesthetic effect. One can for example consider that his impression corresponds to a drawing, a writing such as one or words.

The lighting device of the invention is used for example as a functional luminaire and for any type of destination. As examples, the glazing is intended for:

- a building glazing, such as an illuminating facade, an illuminated window, a ceiling lamp, a floor slab or lighting wall, an illuminated glass door, a light partition, a lighting ceiling, a stair step, a railing, a balustrade, a counter, a transport vehicle, such as an illuminated side window or an illuminated glass roof, or an illuminated window or a rear window, an illuminated glass door, in particular for transporting individuals, such as automobile, truck, or in common, such as a train, metro, tramway, bus or aquatic or air vehicle (plane),

- road or urban lighting,

- a glazing of street furniture, such as an illuminated glass part of a bus shelter, a railing, a display, a window, a shelf, a greenhouse,

- an interior furniture glazing, such as an illuminating bathroom wall, an illuminating mirror, an illuminated glazed part of a piece of furniture,

- a glazed part, in particular door, glass shelf, lid of refrigerated domestic or professional equipment.

For a partition wall, shelf, shop window or company premises, the geometric shape of the combination of enamel and transparent glass surface will advantageously correspond to the logo of the company.

The enamel according to the invention has the advantage of being durable, resistant to scratching and chemicals. The lighting device thus designed is suitable for both indoor and outdoor applications.

The present invention is now described with the aid of examples which are only illustrative and in no way limit the scope of the invention, and from the attached illustrations, in which: - Figures 1 to 3 show schematic sectional views of the device of the invention according to an application, respectively of monolithic glass, laminated glass, and double glazing;

FIGS. 4a to 4d illustrate schematic top views of respective variants for the arrangement of the enamel;

FIGS. 5a to 5f are top views of the device of the invention showing examples of distinct patterns for the enamel layer;

FIG. 6 illustrates luminance curves for an example of the invention and two comparative examples.

FIGS. 1 to 3 illustrate schematic views of the lighting device or luminaire 1 of the invention comprising at least one sheet or glass substrate 2, light-emitting diodes (LEDs) 3 constituting the light sources and arranged facing the wafer glass, and light diffusion means 4 consisting of enamel.

The lighting device of Figure 1 comprises a monolithic glass while the laminated device of Figure 2 comprises two glass substrates 2A and 2B assembled by an intermediate layer 6 of plastic material, such as a PVB sheet.

The device of FIG. 3, as double glazing or insulating glazing, comprises two glass substrates 2A and 2B separated by a gas strip 7, the spacing being formed by spacers 8.

Each glass substrate 2, 2A or 2B has two opposite general faces 20 and 21 and a wafer 22. The LEDs 3 are arranged according to the invention so as to inject their light in the direction of the edge of the glass according to the arrows F illustrated in FIG. 1, preferably along two opposite parallel sides. The LEDs are housed in profiles 5, here two in number, each associated with one side of the substrate, and having a U-shaped cross section facing the glass substrates.

The joining of the profiles 5 to the (x) glass substrate (s) is carried out in a known manner. Here, the U of each profile overlaps the corresponding glass sheet.

The dimensions (length and width) of the illuminating glazing are adapted to the use that is made of them, and the number of diodes is then a function of these dimensions.

The illuminating glazing can cover any geometric shape adapting to the desired design, so not necessarily rectangular or square base.

The LEDs 3 are arranged on a support 30 constituted by bars, or on a printed circuit board. The support, whether in the form of a plate or strips, is named in a known manner in English PCB for Printed Circuit Board.

Each section 5 comprises a housing 50 in which is fixed the support 30 of the LEDs, by means of securing means which are a function of the type of support used. Each diode 3 is opposite the wafer 22 of the glass and is preferably in the immediate vicinity, such as a separation distance of 1 mm. The diffusion means 4 are according to the invention affixed against one of the faces of the glass 2, or one of the glasses 2A of the laminated device.

For the monolithic glass, the diffusion means 4 are arranged on the face 21, opposite to that 20 from which the light is extracted in a diffusion advantageously Lambertian type (symbolized by the spheres G in Figure 1, the observer being in look of the face 20). .

Indeed, according to the invention, the enamel chosen by its intrinsic characteristics, in particular its brilliance, Lambertian light scattering favoring no specific direction but instead diffusing in all directions of space whatever is the viewing angle, providing the observer with homogeneous illumination in the space. Enamel by its surface 40 facing the face 21 of the glass is on the one hand a diffuse reflective surface for part of the light which is reflected in the opposite direction, towards the face 20, and on the other hand a diffuse transmission surface for another part of the light that emerges from the enamel to the outside of the glass.

For the laminated device, the diffusion means 4 are arranged indifferently on the glass substrate 2A or 2B, while being arranged on the face 21 intended to be associated with the PVB, that is to say on one of the faces of the internal glass to the lighting device and not facing the outside. The diffusion means need not be at the same time on the face 21 of the first substrate 2A and on that 21 of the second substrate 2B. The inventors have unexpectedly shown that the lighting is not more important.

As arranged on one side of the glass and inside the laminate, the amount of light extracted from the face 20 of the first substrate 2A is identical to that of the face 20 of the second substrate 2B.

The laminated lighting device thus has the advantage of illuminating as much from each of its faces.

According to the invention, the diffusion means 4 thus consist of enamel, this enamel not covering the whole of the glass sheet according to a solid surface, being arranged in particular in a discontinuous manner or according to sparse geometrical shapes, called enamel patterns.

The thickness of enamel is between 10 μιτι and 50 μιτι, for example of the order of 15 μιτι.

The enamel is preferably white. Its brightness L ^* is preferably at least 50. In the device, the illuminating zone corresponds to the enamel layer and the glass surface facing the enamel, whereas the dark zone corresponds to the surfaces adjacent to the enamel. enamel, surfaces belonging to the face of the glass on which the enamel is deposited. The illuminating zone may cover a part of the surface, thus leaving at least a first dark zone, that is to say non-illuminating, dark zone which is chosen from a transparent zone (clear of glass ...) or an area decorative by an opaque and / or colored coating or a mirror area for example formed by a silver coating covered with an oxidation protection paint, silvering deposited on the outer face.

The dark area (s) must not disturb the guidance in the glass.

The illuminating zone may be peripheral, in particular along a glazing edge and the more central dark zone, or vice versa. The layout or placement of the enamel will depend on the intended lighting application. Without being exhaustive and by way of example, FIGS. 4a to 4d show different arrangements.

In Figure 4a, the enamel 4 (grayed) is distributed in a peripheral frame, the central area being dark. The dark area may be transparent and / or a mirror or a decor.

Figure 4b illustrates enamel 4 in the central zone, while the dark zone is peripheral, transparent zone and / or mirror. The enamel can be in the form of a logo, a sign, etc.

FIG. 4c shows two enamel zones 4 corresponding to illuminating light bands, for example 40 mm wide, while the rest of the surface (dark area) is transparent. FIG. 4d illustrates an application of illuminating door (with standard door dimensions, 2460 mm by 960 mm), the enamel 4 being distributed in several frames inscribed in each other, each frame having a different width. The pattern provides an appearance of the type molding.

Figures 5a to 5e show non-limiting examples of enamel patterns 4 made on glass sheets of dimensions 1200 mm x 300 mm. The enamel patterns 4 (illuminating areas) correspond to the black patterns in Figs. 5a to 5e.

On the other hand, in FIG. 5f, the zones that are not covered with enamel correspond to the black-colored patterns, the white-colored zones correspond to the enamel 4. The patterns have curved or straight lines, are of width and length variables. They can present all geometric shapes. Each glass sheet may comprise a unitary pattern that is identically reproduced a plurality of times to cover the glass surface. The spacing between the enamel patterns is adapted to the size of the glass sheet. The larger the glass sheet, the more it is advisable not to bring the patterns too close together so that the light propagates with respect to the whole of the surface and successively reaches each of the patterns.

The enamel may extend partially on the glass continuously and solidly in at least one solid surface, for example of width less than 200 mm, even 100 mm and even more preferably less than or equal to 50 mm. Alternatively, the enamel layer may be discontinuous extending over all or part of the glass surface and formed of a set of flat areas forming narrow and for example elongated patterns. Each pattern is in a surface whose smaller dimension is less than 200 mm, even 100 mm and even more preferably less than or equal to 50 mm.

The patterns are for example geometric: rectilinear or curved strip, concentric circles, L-shaped shapes, etc. The patterns are identical or distinct, parallel to each other or not, with a distance between them identical or not.

The patterns may be identical by being reproduced over the entire glass surface at an equidistant spacing and as illustrated in Figures 5a and 5b.

By way of example, the pattern of FIG. 5a is in a surface whose width 1 is 29 mm and that of FIG. 5b has a width 2 of

63 mm. The separation distance between two adjacent patterns in the longitudinal direction of the substrate is equal to 38 mm (d1 of Figure 5a) or respectively 72.5 mm (d2 of Figure 5b).

FIG. 5c shows another example of a pattern formed of arcs of circles spaced apart and concentric from the edges of the substrate towards the center. This pattern can extend over the entire glass surface. In this embodiment, the circular arcs have variable widths (smaller dimension) and their separation distance is also variable. By way of example, with reference to FIG. 5c, the referenced dimensions are the following, the widths of the arcs of circle and the distances of separation decreasing towards the center: 3 = 19 mm, = = 29 mm, d3 = 84 mm, d4 = 55 mm, d5 = 10 mm.

FIGS. 5d and 5f also illustrate other forms of patterns respectively in rectangles of variable dimensions, in streaks or squares separated by unglazed crosses.

The enamel is able to be deposited on a glass substrate. Its composition is for example as follows: between 20 and 50% of SiO ₂ , preferably of the order of 45%,

10 to 40% of Ti0 ₂ , preferably of the order of 20%

not more than 10% of ZnO, preferably of the order of 5%, not more than 10% of Al ₂ 0 ₃ , preferably of the order of 3%, - up to 20% of one or more oxides, such as 5 to 20% of Na ₂ 0, at most 5% of K ₂ 0 and at most 5% of CAO.

By way of example of enamel compositions, mention may be made of enamel under the name Ferro 194002 marketed by FERRO and which has the following composition:

43.84% SiO ₂ ,

23.51% of TiO ₂ ,

6.1 1% ZnO,

2.81% AI ₂ O ₃ ,

18.71% of Na ₂ O,

2.51% K ₂ O,

1.85% CaO.

Enamel is associated with glass in the usual manner by being deposited by screen printing and / or inkjet, and undergoing a cooking step. As an example for the Ferro 194002 product, the cooking conditions are as follows:

oven temperature: between 640 and 710 ° C, preferably of the order of 680 ° C,

glass substrate temperature: between 630 and 700 ° C., preferably of the order of 660 ° C.,

heating time for the possible tempering of the glass after baking: 135 s.

The proportions of glass frit (SiO ₂ ) and refractory pigments (TiO ₂ or ZnO) will advantageously be combined to improve the fusibility of the enamel and lead to a sufficiently dense material (or low porosity). This density allows the enamel in particular to fulfill its optimal function of diffusing light to the outside.

Comparative tests were made to show the performance of the lighting with the device of the invention comprising Ferro enamel 194002 vis-à-vis separate glass devices each provided with a different enamel (especially at high rates of alumina) which is porous. The enamel is distributed according to the same arrangement for the example of the invention and the comparative examples.

Comparative Example 1 comprises 30% glass frit and 70% alumina.

Comparative Example 2 comprises 60% glass frit and 40% alumina. The viscosity of the layer is adapted to be deposited by screen printing. The glass substrates used in the tests are 3 mm thick Saint-Gobain Glass Diamond glass.

Table I below illustrates the comparative tests by giving for a monolithic glass the measurement of the average luminance in cd / m ² at 0 ° (normal to the glass) for the light extracted on the one hand from the side of the face 20 of the glass, and secondly on the side of the face 21 of the glass provided with the enamel.

TABLE I

It is found that the lighting with the enamel of the invention is about twice as bright as those of any enamel. Table II below illustrates the comparative tests by giving, for a laminated glass, the measurement of the maximum luminance in cd / m ² for the light extracted on the outside of each side of the laminated device, on the one hand for the glass provided with enamel, and secondly for the other glass.

TABLE II

Example Example

Ferro 194002 comparative 1 comparative 2

Face 20 for the

glass provided

Enamel 2 070 1 600 830

Face 20 for the

bare glass 1 970 1 640 820 Again for a laminated device, there is a significant increase in lighting, by a factor between 1, 2 and 2.5.

The lighting resulting from the device of the invention is thus particularly bright, while being homogeneous and very little dazzling.

In addition, the device of the invention has a lambertian type diffusion, that is to say that whatever the angle of observation of the illuminating surface, the luminance is substantially constant.

Thus, Figure 6 illustrates the maximum luminance of each device at the viewing angle between 0 and 60 °. It can be seen that the luminance of the device of the invention is substantially constant, at around 6000 cd / m ² , whereas it increases for the comparative examples as a function of the size of the observation angle.

Finally, the device of the example of the invention above advantageously has a brightness 20 times higher than that of the comparative examples and a higher optical density, providing greater resistance to cleaning and scratching. Table III below summarizes several values as to brightness, optical density, compatibility with cleaning products, "scratch" test, color measurement (L ^* , a ^* , b ^* ), for the example of the invention and Comparative Example 1 The cleaning compatibility test makes it possible to assess the chemical resistance of enamel to three families of household products: soap (for example a soap based on potassium oleate for example), alcohol (for example ethanol) and alcohol. ammonia (eg Vigor product). For example, the samples are immersed for at least 30 min or at least 1 hour. A color measurement (L ^* , a ^* , b ^* ) of the glass on the one side at the side provided with the enamel and on the other hand on the opposite side is performed before and after the test. The color of the enamel is measured by a spectrocolorimeter, for example the Minolta CM600D

The "scratch" test or test of resistance to scratching is carried out using a tip that moves on the enamel by applying an identical force for each of the tests. The sclerometer pencil sold by Elcometer is used with a 0.75mm diameter tungsten carbide tip.

The optical density is measured using the Tobias TQ densitometer. Gloss is measured with Byk-Gardner MICRO-TRI-GLOSS 4430 glossmeter.

TABLE III

Test Example of the Invention Comparative Example 1

Brightness 38 1, 6

Optical density 0.9 0.6

Compatibility with

yes no cleaning products

Scratch test yes no

Face of the glass provided with Face of the glass provided with the enamel: 78,75 the enamel: 72,58

L ^*

Opposite Face of Glass: Opposite Face of Glass:

61, 84 61, 61

Glass face provided with Glass face provided with enamel: -1, 48 enamel: -0.6

a ^*

Opposite Face of Glass: Opposite Face of Glass:

-2.04 -0.71

Glass face provided with Glass face with enamel: -0.85 enamel: -1, 71 b ^*

Opposite Face of Glass: Opposite Face of Glass:

1, 26 -0.56 At the scratch test, after the tip has passed, no scratches should be visible on the surface of the enamel. However, scratches are visible in Comparative Example 1 with an applied force of 10 N. No scratch is visible on the enamel according to the invention for a force of 10 N and even 20 N.

In addition, the wettability of the water on the enamel is visually observed using a cotton pad soaked with distilled water. Comparative Example 1 has a very poor wettability with respect to the enamel, the water infiltrates and leaves a stain on the enamel.

The example of the invention and the comparative example have been tested for compatibility with the cleaning products. It has been found that the device with enamel "Ferro 194002" (example of the invention) has resisted soap, alcohol and ammonia (Delta E less than 1, 4), while Comparative Example 1 was resistant to alcohol but exhibited a change of appearance in contact with soap (Delta E = 2.6) in a greyish-to-greyish color, and ammonia (Delta E = 6.3). . It is recalled that the Delta E is calculated in a known manner from the measurements of L ^* , a ^* , b ^* before and after the cleaning tests. If Delta E is greater than 1, 4, a color change is visible.

Other examples of enamel composition may be selected for the device of the invention: enamel under the name Ferro 19401 1 sold by FERRO, reference AF5000 sold by JM, reference VV30-244 -1 marketed by Pemco. Table IV below summarizes the main components of each enamel. Examples

according to Al ₂ 0 ₃ Bi ₂ 0 ₃ CaO Ce0 ₂ FK ₂ 0 Na ₂ O Si0 ₂ Ti0 ₂ ZnO the invention

390 - -

JM AF5000 2% 17% ppm 0.6% 7% 37% 33% 3%

Pemco 1% 600

VV30-244-1 ppm

RA 0.9% 14% 30% 17% 4%

Ferro

2% 4% 0.9%

19401 1 3% 2% 16% 38% 27% 6%

As already stated above, the inventors have shown that the brightness and the nature of the composition are of all importance.

5 The lower the gloss, the more the glaze is porous after cooking and is

therefore likely to absorb water, making it more degradable.

The TiO 2 pigments make the enamel sufficiently opaque (to visualize the enamel in the off state) and lower the TL

10

Thus, the examples of the invention (Ferro 19401 1, Ferro 194002 and JM

AF 5000, Pemco VV30-244-1 RA) are very white with a gloss greater than 20 and have a low light transmission, less than 40%. The Ferro 19401 1, Ferro 194002 and JM AF 5000 have a

15 TL light transmission less than 35%.

Claims

1. Lighting device comprising at least a first glass sheet (2, 2A, 2B) having first and second opposite major faces (20, 21) and a wafer (22), light-emitting diodes (3) providing the function of illumination and with light emitting faces optically coupled to the wafer (22) of the first light guide glass sheet, and diffusion means (4) for extracting the guided light and arranged on the one first or second main faces (21), the diffusion means defining one or more illuminating zones, the diffusion means not covering the entire surface of the first glass sheet according to a solid surface, characterized in that the means are an enamel having a gloss greater than 15.

2. Lighting device according to claim 1, characterized in that the enamel has a gloss greater than or equal to 20 or 30.

3. Lighting device according to any one of the preceding claims, characterized in that the enamel has an optical density of at least 0.6 or even at least 0.8.

4. Lighting device according to any one of the preceding claims, characterized in that the enamel is resistant to scratching, in particular is not scratched by applying a tip with a force of 10 N or 20N.

5. Lighting device according to any one of the preceding claims, characterized in that the enamel is chemically resistant with a cleaning product, including soap, alcohol and ammonia, especially without color change after cleaning. in particular with a Delta E color difference less than 1, 4.

6. Lighting device according to any one of the preceding claims, characterized in that the device has a luminance of at least 1000 cd / m ² , preferably at least 2000 cd / m ² , or 3000 cd / m ^2. m ² .

7. Lighting device according to any one of the preceding claims, characterized in that the enamel is such that, in the illuminating area, the difference in absolute value between the luminance at normal and the luminance at the angles between 0 and 45 ° or even 60 ° is less than 30% or even 20% or 10%, providing in particular Lambertian type lighting.

8. Lighting device according to any one of the preceding claims, characterized in that it comprises only one sheet of glass (2), the face (21) of the glass sheet provided with enamel is the face opposite to that (20) forming the main or even single illumination face of the device.

9. Lighting device according to any one of claims 1 to

7, characterized in that it constitutes a multiple glazing further comprising a second glass sheet and an internal space between the first and the second sheet, the enamel being on the inner face of the first sheet of glass.

10. Lighting device according to any one of claims 1 to 7, characterized in that it constitutes a laminated glazing comprising the first glass sheet, a second glass sheet (2A, 2B) and an intermediate sheet (6 ) of plastic material, the enamel (4) being arranged inside the laminate on the face (21) of the first glass sheet which is opposite the plastic sheet (6), the diodes being for example centered on the edge of the laminated glazing or or facing the edge of the first sheet or the second sheet.

1 1. Lighting device according to any one of the preceding claims, characterized in that the first glass sheet coated with enamel has a light transmission of less than 45% or even 40%.

12. lighting device according to any one of the preceding claims, characterized in that the thickness of the enamel does not exceed 100 μιτι, preferably is between 8 μιτι and 40 μιτι, in particular of the order of 15 μιτι.

13. Lighting device according to any one of the preceding claims, characterized in that the enamel extends, preferably over the whole of one face of the first glass sheet, discontinuously in particular according to geometric shapes sparse to curved and / or straight lines.

14. Lighting device according to any one of the preceding claims, characterized in that the enamel extends discontinuously and defines dark areas including patterns of geometric shapes sparse curved lines and / or straight, including length at least centimeter.

15. Lighting device according to any one of the preceding claims, characterized in that an illuminating area is a flat enamel especially of length at least centimeter.

16. Lighting device according to any one of the preceding claims, characterized in that an illuminating zone is adjacent to a functional dark zone selected from a transparent zone, a reflecting zone, in particular forming a mirror, and a decorative zone.

17. Lighting device according to any one of the preceding claims, characterized in that a lighting zone, in particular a band or a drawing is in a peripheral zone of a face of the first glass sheet, the dark zone being more central, and / or in that it comprises a plurality of illuminating zones distributed on one side of the first sheet of glass.

18. Lighting device according to any one of the preceding claims, characterized in that the enamel (4) is white by being defined by a clarity L ^* of at least 50.

19. Lighting device according to any one of the preceding claims, characterized in that the enamel (4) has the following composition

between 20 and 60% by weight of SiO ₂ ,

10 to 45% by weight of refractory pigments, in particular Ti0 ₂ .

20. Lighting device according to any one of the preceding claims, characterized in that the enamel (4) has the following composition

between 20 and 60% by weight of SiO ₂ , preferably of the order of

45%,

10 to 45% by weight of TiO ₂ , preferably of the order of 20% not more than 10% by weight of ZnO, preferably of the order of 5%,

not more than 10% by weight of Al ₂ 0 ₃ , preferably of the order of

3%,

up to 30% by weight of one or more oxides, such as 5 to 25% of Na ₂ 0, at most 5% of K ₂ 0 and at most 5% of CaO.

21. Lighting device according to any one of the preceding claims, characterized in that the enamel (4) is deposited on the first glass sheet by screen printing and / or ink jet.

22. Lighting device according to any one of the preceding claims, characterized in that the enamel (4) has undergone after baking in a furnace between a temperature between 640 and 710 ° C so that the first sheet of glass reaches a temperature of between 630 and 700 ° C.

23. Lighting device according to any one of the preceding claims, characterized in that the glass in particular with the enamel is quenched.

24. Lighting device according to any one of the preceding claims, characterized in that the diodes (3) are arranged to inject light through the wafer (22) of the first glass sheet along two parallel opposite sides. .

25. Lighting device according to any one of the preceding claims, characterized in that the first glass sheet is based on a glass having a high light transmission, of at least 85%, when the measurement is carried out under Illuminant D65 on a sheet of glass with parallel faces 4 mm thick.

26. Lighting device according to any one of the preceding claims, characterized in that it is used as a functional luminaire and for any type of destination, the glazing is intended in particular for:

- a building glazing, such as an illuminating facade, an illuminated window, a ceiling lamp, a floor slab or lighting wall, an illuminated glass door, a light partition, a lighting ceiling, a stair step, a railing, a balustrade, a counter,

a transport vehicle, such as an illuminated side window or an illuminated glazed roof or a window or a rear window, an illuminated glass door, particularly for transporting individuals, such as the automobile, truck, or in common, such as train, subway, tram, bus or aquatic or air vehicle (plane),

street or urban lighting,