WO2012168646A1

WO2012168646A1 - Lighting device comprising light-emitting diodes

Info

Publication number: WO2012168646A1
Application number: PCT/FR2012/051257
Authority: WO
Inventors: Anne Gierens; Aude Montgermont; Jingwei Zhang
Original assignee: Saint-Gobain Glass France
Priority date: 2011-06-09
Filing date: 2012-06-06
Publication date: 2012-12-13
Also published as: FR2976341A1; CN204076966U; FR2976341B1; EP2718099A1

Abstract

The invention relates to a lighting device comprising: at least one glass sheet (1) having two opposing main faces (12), light-emitting diodes (3) providing the lighting function, and light-diffusing means (11') arranged on one of the first or second main faces, said diffusion means taking 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 opposite the rear face of the glazing.

The LED lighting device further comprises light diffusion means provided by sanding or acidifying the glass to avoid glare. However, this implementation weakens the glass. In addition, broadcast performance is not always satisfactory or sustainable.

The object of the invention is therefore to propose a new LED-based lighting device coupled to glass which, while providing a sufficient luminous efficiency without dazzling, does not have the disadvantages of the prior art as regards its means of diffusing light. the light.

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 arranged on the side of the first face, and means for diffusing the light of the diodes arranged on one of the first or second main faces, the diffusion means defining one or more illuminating areas, and the diffusion means being 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 the light is diffused, corresponding to the surface of the glass sheet facing the enamel, while the areas adjacent to the enamel (and out of the light beam) on the same surface of the glass sheet are called dark areas.

Thus, the combination of lighting with LEDs, and the use of a suitable enamel as diffusion means forming one or more illuminating areas, provides a bright, homogeneous and glare-free and durable.

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 enamel, while ensuring a quality of light diffusion, is resistant to scratching, in particular is not scratched by applying a tip, for example tungsten carbide diameter 0.75 mm, with a force greater than or equal to 10 N or even 20 N. The enamel, while ensuring a quality of diffusion of light, is chemically resistant to a cleaning product, in particular soap, alcohol and ammonia, in particular without any change after cleaning, in particular with a Delta E color difference less than 1, 4.

The formula for the color difference is ΔΕ = V (AL ² + Aa ² + Ab ² ). 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 areas, the illumination is of the Lambertian type. Thus, the luminance has the advantage of being substantially equal regardless of the angle of observation. The selected enamel can cause a difference in absolute value between the luminance at normal and the luminance at angles between 0 and 45 ° or 60 ° which is lower by at least 30% or even 20% or 10%.

According to one characteristic, for optimum luminance, the face of the glass sheet provided with the enamel constitutes the first face.

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 m, in order to play its role of reflector for 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.

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.

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 an enamel or still a reflective zone including mirror for example formed by a silver coating covered with a protective paint oxidation.

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 the first glass sheet, in particular along at least one edge of the glass surface and, for example, at least one strip or a drawing, while the dark zone is more central and more away from the diodes.

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 device may comprise a plurality of illuminating zones distributed over the glass sheet.

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 ΤΊΟ 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 ΤΊΟ 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 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.

In one embodiment, the emitting faces of the diodes are opposite the first face, in particular with the main beam normal to the first glass sheet.

In one embodiment, the emitting faces of the diodes are arranged so that the main radiation of the diodes is reflected by a reflector, in particular a metal reflector and / or in particular oblique with respect to the glass sheet, on the side of the first face and the main radiation reflected is sent to the first face provided with the enamel or sent to the first face in an area opposite the enamel zone arranged on the second face.

The device may constitute a multiple glazing unit further comprising a second glass sheet and an internal space between the first and second sheets, the space containing the diodes, the enamel being preferably on the internal face of the first glass sheet .

In one embodiment, it constitutes a multiple glazing unit further comprising a second glass sheet with a third face facing the first face and a fourth main face, an internal space between the first face and the third face, space containing the diodes, the emitting faces of the diodes being arranged so that:

a part of the diode rays is reflected by a reflector in the internal space, in particular metal and / or in particular oblique with respect to the glass sheet, the reflected radiation going towards the first face provided with the enamel or the zone of the first face which is opposite the zone of the second face provided with enamel, and another part of the diode radiation is reflected by the reflector, the reflected radiation going to the third face provided with the enamel or the zone of the third face which is opposite the region of the fourth face provided enamel.

The enamel is preferably on the first face and on the third face.

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 applications both indoors and outdoors, and between the inside and the outside.

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:

^■ Figure 1 shows schematically a sectional view of the light diodes and glazed with enamel in an embodiment of the invention;

^■ Figure 1 diagrammatically shows a top view of the light glazing of Figure 1;

^■ Figures 2 and 3 schematically represent views of LED luminous glass cutting with the enamel according to the invention.

EXAMPLES OF GLAZING

It is specified that for the sake of clarity the various elements of the objects (including angles) represented are not necessarily reproduced on the scale. In addition, in the figures, the light rays do not necessarily strictly follow the laws of optics.

FIG. 1 schematically represents a partial view in longitudinal section of a multiple glazing unit with light-emitting diodes 100 in a first embodiment of the invention.

The glazing 100, here an insulating glazing unit, comprises:

a first planar glass element 1 made of mineral glass with first and second main faces 1 1, 12 for example square (or rectangular) glass sheets,

a second planar glass element 1 ', with a main face facing the first face, said third face 13, and another main face 14, said fourth face, for example square glass sheet (or rectangular etc), the first and second elements being integral and spaced,

an internal space, between the first and third faces, space in particular under vacuum or filled with a gas blade, such as rare gas (s) or air,

a spacer 2 of the first and second glass elements at the periphery of the glazing, delimiting the internal space filled with a gas blade, spacer in the form of a frame 2 of rectangular cross section and with a free face perforated to leave the desiccant in contact with the air knife or gas, and optionally in a variant is added beads and form a vacuum glazing.

In the internal space, there are four groups of diodes 3 on four bases 30, (in other words four bars of diodes), each associated with a free face of said spacer and thus distributed: a first group of light-emitting diodes along a first edge, a second group of light-emitting diodes along a second edge, a third group of light-emitting diodes along a third edge, a fourth group of light-emitting diodes along the fourth edge.

The diodes of each group each have a given principal direction of emission substantially parallel to the first face, for example equidistant from the first and third faces 1 1, 13. And thanks to the four groups of diodes:

four first light zones, associated with the first glass element 1, each provided with a first diffusing means 11 'which is the enamel according to the invention, preferably on the first face 11, for example in the form of four light bands; peripherals along the four edges (as shown in Figure 2), of identical or distinct width L1, in particular less than 200 mm or even 100 mm, and adjacent to a first central dark zone 15,

four second light zones, associated with the second glass element 1 'each provided with a second diffusing means 13', which is the enamel according to the invention, preferably on the third face, by example in the form of four peripheral bands along the four edges, of width L2 identical or distinct to each other and to L1, especially less than 200 mm or even 100 mm, opposite the first light areas, and adjacent to a second dark area adjacent central 15 opposite the first dark area.

Naturally one can use several bars of diodes for each light band, depending on the length in particular.

Naturally, the light strips may be identical or distinct in their shape, their width, their color, their nature (different diffusion means).

One can also want to delete one or two light bands.

A metal piece, anodized aluminum fixed to the glazing in the internal space is a reflector 5, which forms a beam splitter from the first group of diodes and contributes to improving the luminous efficiency and homogeneity of the first and the second light zone.

To do this, the metal part 5 has a split central reflective surface 50, 51, 52 consisting of:

a first central surface 51, oblique with respect to the first face, at a first acute angle of 30 ° to 50 ° relative to the first face 1 1, able to return first central rays of the first group of diodes on the first enamel 1 1 'of the first light zone,

- A second central surface 52, oblique with respect to the third face, at a second acute angle identical to the first acute angle of 30 ° to 50 ° relative to the third face 13 adapted to return second central radii of said group of diodes on the second enamel 13 ',

- The two surfaces 51, 52 being contiguous (here forming a point). First and second central rays include the main direction of emission (or the main directions of emission if any) and form at least 30% or even 50% or more of the total emission flux of the diodes of said first group. The main direction of emission may be reflected by the tip as shown here, or alternatively by the first central surface 51 or the second central surface 52. The main direction of emission may be normal to the base 30.

The bases 30 are preferably made of metal, in particular of aluminum, and possibly with a diffusing surface around the groups of diodes for the recycling of rays.

The bases 30 are for example fixed (by gluing, screwing ...) on the inner face 21 of the spacer, here in a frame, for example substantially perpendicular to the first face. For each diode, it is possible to define a set of so-called central light rays in an emission cone around the main transmission direction characterized by a first half-angle i31 with respect to the main direction i3o and by a second half-angle 2 compared to the main direction i3o.

The half-angle at half height -θ _Μ ι (in the direction of the first light zone) and / or ÛM2 (in the direction of the second light zone) may be at least 50 °, preferably at least 60 ° or at least 70 °. The emission cone here is Lambertian.

The set of so-called central radii are included in an emission cone corresponding to at least 30% of the total flux emitted by each of the diodes. The luminance (normal) of the first and second light bands

1 1 ', 13' may be identical for example when the emitted beam is symmetrical and separated into 2 identical beams and if the diffusing means have identical optical properties (as well as glass sheets). The reflector is for example fixed (by bonding, etc.) via two first flat lateral portions on the third face 13 and / or on the first face 1 1 outside the first light zone. These parts can be masked by extension of the first and second diffusing means that are the enamel or for example by layer (s) decor (s).

In the region of the first light strip 1 ', the reflector 5 has a cross section in M. The reflector is preferably made of aluminum, in particular anodized or even a metallized plastic part.

The reflector 5, 50 is delimited:

by a first reflecting lateral edge A, forming in particular an angle cc1 with the main direction or directions of emission, the extent of the enamel 1 'being such that all the so-called lateral radii beyond cc1 and in the direction of the first face 1 1 are diffused by the enamel 1 1 ', and, delimited by a second reflective lateral edge B, forming in particular an angle cc2 with the main direction or directions of emission, the extent of the second enamel 13' being such that all so-called lateral spokes beyond cc2 and towards the third face are diffused by the second enamel 13 '.

In particular, it is possible to recover the extreme radius touching the first face at C farthest from the first group of diodes. It is also possible to recover the other extreme radius touching the third D-face furthest from the first group of diodes.

The dark (central) areas 15 of the first and second glass elements are chosen to be transparent.

For exemple :

- the glazing surface is 600x600 mm ² with double-glazed assembly of the two extra-clear 2.9 mm thick glasses,

the diodes have an individual power of 0.4 W (approximately) over a length L 0 of 450 mm, ie a power of 20.5 W / m, each base 30 is made of aluminum and carries twenty three diodes with the dimensions 450 mm × 10 mm × 1, 9 mm,

the height of the internal space (of the spacer 2) is 22 mm,

the width L1 and L2 of the light bands is 50 mm.

It is possible to use a similar reflector for each of the other groups of diodes or a reflector of different design (shape, nature, etc.) or of a different function (for example for lighting only via the first glass element.

Note also that the reflector (the central surface 50 at least split) is between the enamels 1 1 'and 13' which can hide it from an observer in front of the glazing.

We can thus form:

- in a building application, a luminous facade, a luminous window, a ceiling lamp, a floor slab or luminous wall, a luminous glazed door, a luminous partition, a step of stairs,

- in a transport vehicle application, a bright side window or a bright glass roof, a light window, a luminous glass door, including public transport, train, metro, tramway, bus or aquatic or air vehicle (plane) ,

- in a street or urban lighting application,

- in street furniture, a luminous glass part of a bus shelter, a balustrade, a display, a window, a luminous glazed part of a shelf, a greenhouse,

- in an interior furnishing application, a luminous wall of a bathroom, a luminous glazed part of a piece of furniture,

- a glass wall of a refrigerated equipment (bins cover, glass door, shelf ...).

The first glass element 1 is for example facing inward after installation. Alternatively, the dark (central) areas 15 are chosen (independently) transparent, or with a mirror or a decoration (opaque and / or colored ...).

FIG. 2 schematically represents a partial view in longitudinal section of a light insulating glazing unit 200 with LEDs, in another embodiment of the invention.

The glazing 200 differs from the glazing 100 by the used reflector 5, 50 involving lighting on one side by the first group of diodes.

The reflector comprises a metal part 5, anodized aluminum, with

a first particularly planar wing comprising the oblique central surface 50 and a lateral reflecting zone 51 'towards the first face January 1,

- A second wing, with a reflective lateral surface 53, for example flat or concave, on the third face 13, in particular for fixing the reflector (by bonding etc.) or alternatively spaced from the third face and fixed on the spacer.

This is for example a sheet with a fold.

The extent of the central surface 50 and the extent of the reflective lateral surface 53 are such that all central and lateral spokes (toward the third face) are reflected towards the first enamel 11 '.

The second enamel 17 (rendered non-functional by the surface 53) can be preserved or replaced by a possible mirror or a decorative coating if it is desired to mask the reflector 5 on this side, in particular the lateral surface 53.

FIG. 3 schematically represents a partial view in longitudinal section of a light-emitting diode window 300 in another embodiment of the invention.

In this live lighting configuration, the glass sheet 1 carries on its first face 1 1 the diffusing enamel 1 1 'according to the invention, the diodes 3 are on PCB supports 30 reported on a fixed metal plate for example on a wall V (wall, floor, ceiling, other glass, metal ..) and diodes are next to the face 1 1. The main light (as shown by the arrow) arrives directly on the enamel January 1 delimiting the width L1 of the homogeneous illuminating area. The zones 15 are for example mirror zones, decor, transparent.

TESTS OF EMAIL

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.

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

The enamel is preferably white. Its clarity L ^* is preferably at least 50.

The enamel is able to be deposited on a glass substrate. Its composition is for example the following:

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%,

no more than 10% of ZnO, preferably of the order of 5%,

no more than 10% Al ₂ O 3, preferably of the order of 3%,

up to 20% of one or more oxides, such as 5 to 20% of Na ₂ O, at most 5% of K ₂ O 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% of 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 cooking:

135 s.

The proportions of glass frit (S1O2) and refractory pigments (ΤΊΟ2 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 enamel according to the invention (selecting the Ferro 194002) vis-à-vis separate glass devices each provided with a different enamel (especially with high alumina content) 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.

Finally, the device of the example of the invention above advantageously has a gloss at least 10 times higher than that of the comparative examples and higher optical density, providing greater cleaning and scratch resistance without compromising its diffusion performance. Table I below summarizes these values.

TABLE I

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 minutes or even at least 1 hour.

A color measurement (L ^* , a ^* , b ^* ) is performed before and after the test. The color of the enamel is measured by a spectrocolorimeter, for example the Minolta CM600D device.

The test of the invention and the comparative examples have therefore been tested for compatibility with the cleaning products. It turned out that the device with enamel "Ferro 194002" withstood soap, alcohol and ammonia (Delta E less than 1, 4), whereas comparative example 1 (like the 2) resisted alcohol but showed a change of appearance in contact with soap (Delta E = 2.6) in a 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.

The scratch test or scratch resistance test is performed using a tip that moves on the enamel by applying the desired force. The sclerometer pencil sold by Elcometer is used with a 0.75 mm diameter tungsten carbide tip.

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

After the passage of this point no scratch should be visible on the surface of the enamel. Scratches are visible in the comparative example with an applied force of 10N. No scratch is visible on the enamel according to the invention for a force of 10N and even 20N.

The wettability of the water on the enamel is visually observed using a cotton pad soaked with distilled water. The comparative example has a very poor wettability compared to the enamel, the water infiltrates and leaves a large task on the enamel.

The lighting resulting from the device of the invention is sufficiently bright, homogeneous and low glare and is durable.

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.

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 II below summarizes the main components of each enamel. TABLE II

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

The lower the gloss, the more the enamel is porous after cooking and is therefore likely to absorb water, making it more degradable.

The ΤΊΟ2 pigments make the enamel sufficiently opaque (to visualize the enamel in the off state) and lower the TL

Thus, the examples of the invention (Ferro 19401 1, Ferro 194002 and JM AF 5000, Pemco W30-244-1 RA) are very white with a gloss greater than 20 and have a low light transmission, less than 40%. Ferro 19401 1, Ferro 194002 and JM AF 5000 have a TL less than 35%.

Claims

1. Lighting device comprising at least a first glass sheet (1) having first and second opposite main faces (1 1, 12), light-emitting diodes (3) providing the lighting function arranged on the side of the first face, and means (4) for diffusing the light of the diodes and arranged on one of the first or second main faces, characterized in that the diffusion 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 greater than or equal to 10 N or from 20 N.

5. Lighting device according to any one of the preceding claims, characterized in that the enamel is chemically resistant to 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 face of the glass sheet provided with enamel constitutes the first face (1 1).

7. 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%.

8. 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.

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

10. Lighting device according to any one of the preceding claims, characterized in that the enamel defines an illuminating zone, the 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 including enamel.

1 1. Lighting device according to any one of the preceding claims, characterized in that the enamel (1 1 ') is white while being defined by a clarity L ^* of at least 50.

12. Lighting device according to any one of the preceding claims, characterized in that the enamel (1 1 ') has the following composition:

between 20 and 60% by weight of SiO ₂ ,

10 to 45% by weight of refractory pigments, in particular T1O2.

13. Lighting device according to any one of the preceding claims, characterized in that the enamel (1 1 ') 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 ΤΊΟ 2, preferably of the order of 20%,

not more than 10% by weight of ZnO, preferably of the order of 5%,

no 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.

14. Lighting device according to any one of the preceding claims, characterized in that the enamel (1 1 ') has undergone after baking in a furnace between a temperature between 640 and 710 ° C so that the first glass sheet reaches a temperature of between 630 and 700 ° C.

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

16. Lighting device according to any one of the preceding claims, characterized in that the emitting faces of the diodes are arranged so that the main radiation of the diodes is reflected by a reflector on the side of the first face and the reflected radiation being then sent on the first face provided with the enamel or on the first face in an area opposite the enamel zone arranged on the second face.

17. Lighting device according to any one of claims 1 to 16, 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 space containing the diodes, the enamel preferably being on the inner face of the first sheet of glass.

18. Lighting device according to any one of the preceding claims, characterized in that it constitutes a multiple glazing further comprising a second glass sheet with a third face facing the first face and a fourth main face, a internal space between the first face and the third face, space containing the diodes, the emitting faces of the diodes being arranged so that:

a part of the diode radiation is reflected by a reflector in the internal space, the reflected radiation going towards the first face provided with the enamel or towards the zone of the first face which is opposite the zone; the second side provided with enamel, and another part of the diode radiation are reflected by the reflector, the reflected radiation going to the third side provided enamel or towards the area of the third face which is opposite the area of the fourth face provided with enamel.

19. Lighting device according to any one of the preceding claims, characterized in that the emitting faces of the diodes (3) are opposite the first face.

20. 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 transport vehicle, such as an illuminated side window or illuminated glass roof or a light-up window or a rear window, an illuminated glass door, in particular for transporting individuals, such as cars, trucks, or in common, such as train, metro, tramway, bus or aquatic or air vehicle (plane),

- road or urban lighting,