EP1954489A1

EP1954489A1 - Laminated assembly provided with light-emitting diodes

Info

Publication number: EP1954489A1
Application number: EP06830044A
Authority: EP
Inventors: Hugues Lefevre
Original assignee: AGC Glass Europe SA
Current assignee: AGC Glass Europe SA
Priority date: 2005-11-21
Filing date: 2006-11-20
Publication date: 2008-08-13
Also published as: WO2007057454A1; KR20080079655A; EA200801387A1; CN101365582A; JP2009516924A

Abstract

The invention relates to a laminated assembly incorporating light emitting diodes comprising a first rigid film made of a dielectric material, an electric conductive circuit applied in the form of thin layers to the rigid film or to the thin non-conductive supporting film of said circuit, wherein said circuit supplies a plurality of light emitting diodes, at least one film made of a plastic non-conductive material uniformly covering the rigid film and diodes by enveloping said diodes and, possibly, a second rigid film adhered to the plastic material film. Said invention comprises at least one calendering operation for fixing films to each other and incorporating the diodes into the plastic material film.

Description

Laminated assembly with light emitting diodes

The present invention relates to laminated assemblies incorporating light emitting diodes.

Previously, laminated assemblies comprising diodes have been proposed. Various structures have been taught on this subject, with the main aim being to organize the various constituents in the products concerned. It appears that the practical methods of realization on an industrial scale are largely ignored in these publications which aim more at the principles than the practical realizations.

For these reasons, the use of light-emitting diodes as a light source has so far been limited to a few embodiments while these same diodes have important uses in the field of display. As a light source, the diodes are currently mainly used in the automotive field for the construction of brake light or for traffic lights. In these applications their own qualities of economic and monochromatic sources are particularly welcome.

As the characteristics of available diodes evolve, their use spreads as a substitute for traditional light sources such as incandescent lamps or fluorescent lamps because of the advantages associated with their very low consumption, a large proportion of the energy consumed being converted into light contrary in particular to incandescent lamps.

"Bulbs" are now proposed that include a few tens of diodes in assemblies that are more of the reproduction of earlier forms that optimization of the characteristics of the diodes used. For these reasons, the production of these lighting devices remains relatively modest in comparison with the potential represented by this new lighting mode.

4346 LAMLITE The invention proposes to produce assemblies constituting light sources comprising diodes in number, under economic industrial conditions. The invention also proposes to provide intermediate basic products that can lead to a wide variety of finished products.

For this purpose, the invention proposes to make assemblies that are capable of being split into smaller units of variable dimensions and having a desired number of diodes, thus providing lighting characteristics determined according to the use projected.

Various types of construction have been proposed previously for producing laminated glazings comprising diodes. The WO publication

2004/009349 is in this sense. However, this publication relates to finished products of limited dimensions such as automotive glazings, the diodes being essentially introduced as display means. These products, apart from their dimensions, have the particularity of implementing a limited number of diodes, unlike applications aimed at lighting. The conditions of realization are a function of these particularities.

The inventors have sought the conditions for producing large laminated assemblies.

A supposed difficulty for this approach lay in the ability to produce these laminated assemblies incorporating solid elements inside the laminate without introducing defects and without risk of modifying in a negative way the essential qualities of these laminates, in particular the qualities of mechanical resistance. . If in small size, and using techniques that are not very automated, the production is relatively easy to produce, the production of large volumes raised a priori certain difficulties.

The incorporation of solid elements in laminated glazing has often encountered the difficulty of avoiding defects such as the presence of bubbles or "delaminations". These difficulties were experienced in particular in the introduction

4346 LAMLITE in laminated glazing elements related to electrical features such as the implementation of conductors called "bus bars" when they are made of thin metal ribbons.

On the basis of these observations, the incorporation of a multiplicity of elements of much greater thickness, such as that of the light-emitting diodes, which is of the order of that of the interlayer films generally used in laminated glazings, should appear particularly delicate. The luminescent diodes available in quantity have dimensions of the order of a few millimeters and their thickness is for the smallest of a few tenths of millimeters. Their construction, including the reflective part used to direct the light produced and the envelope that protects them, makes that a reduction in thickness even if it is desired, can only be of limited extent. These dimensions are much greater than those elements introduced in prior techniques.

In spite of the prejudices that could exist for this type of production, the inventors have shown that it is possible to manufacture laminates incorporating diodes in an amount necessary to constitute sets developing significant light intensities, by using traditional industrial techniques for the production of light. production of laminates not incorporating any added element.

The formation of laminated glazing systematically comprises at least one sheet of a rigid transparent material, such as a glass sheet or a sheet of an organic glass type material such as polyacrylates or polycarbonates. In this or these sheets, is associated with a sheet that gives all of the properties of impact resistance. When two rigid sheets are used, the additional sheet called interlayer is of the thermoplastic type. It generally consists of materials such as polyvinyl acetals, especially polyvinyl butyras, which is widely used in laminated safety glass, but also polyvinyl chlorides, polyolefins, and the like. When a single rigid sheet is used, in what is commonly referred to as a two-layer glazing

4346 LAMLITE ("bilayer"), it is associated with a polyurethane material offering a certain resistance to scratches despite a substantially less hardness than that of glass sheets or organic glass.

In the traditional assemblies indicated above, the lamination is carried out either on elements with the final dimensions of the product, or on intermediate products. The formation of laminated automotive glazing is part of the first category, that of architectural glazing is usually in the second category. For the latter, foliation occurs most often on the volumes produced directly on the flat glass production lines. The traditional dimensions for the largest volumes are of the order of 3x6m or even more. After laminating these volumes are cut to the dimensions required by the building companies customers.

The modes of assembly may differ substantially depending in particular on the dimensions of the parts considered, but also the nature of the intermediate sheet. All techniques, however, involve the use of temperature and pressure. These two conditions have the effect of making the thermoplastic material more malleable, and to impose a contact of this material with the rigid substrate to obtain good adhesion.

The pressure exerted during the assembly can result from the evacuation of the assembled products, which has the additional function of eliminating the air present between the joined sheets, ie the mechanical compression of the constituent sheets, compression which can be associated with a more or less important vacuum.

For very large volumes, such as those indicated above, the only practical possibility is for the application of the pressure, to subject the sheets to one or more calendering operations, preferably under a temperature favoring the moderate softening of the thermoplastic sheet.

Unexpectedly, the inventors have shown that it is possible to assemble sheets carrying a multiplicity of light-emitting diodes,

4346 LAMLITE by techniques such as that used for large volume glazing. In particular the inventors have shown that it is possible to proceed to assembly by the techniques comprising at least one calendering operation. According to the invention this operation is performed on large volumes directly from the production or, where appropriate on elements of smaller dimensions.

When the diodes are incorporated in a laminated assembly, they are necessarily located in the thermoplastic type material. For this reason the thickness of the introduced diodes can not be greater than that of this material or this sheet. To provide a minimum of security, vis-à-vis a possible crushing of the diodes on the rigid substrate, it appears necessary to maintain a difference between the natural thickness of the diodes and that of the sheet in which these diodes are incorporated.

The tests conducted by the inventors have shown that in order to guarantee a good incorporation of the diodes and simultaneously to avoid subjecting them to mechanical stresses liable to damage them, it is preferable to have a slightly thicker material than the diodes, but this thickness additional is kept as low as possible especially for cost reasons, and by that it is generally better to have thin sets. The thickness of the material in which the diodes are incorporated is preferably not more than 50% greater than that of the diodes. More preferably this thickness is not more than 20% greater than that of the diodes, and preferably not more than 10%.

If necessary to avoid the significant pressure exerted on the diodes to make them penetrate the thermoplastic material, it is possible to form housings in the sheet of material prior to assembly. For this purpose the sheet of material is subjected to embossing in the pattern corresponding to the subsequent implantation of the diodes. This arrangement appears useful when the density of the diodes is very high and the pressure necessary to make them penetrate into the plastic material becomes too great.

4346 LAMLITE To further facilitate incorporation, the envelope of the diodes preferably has a shape that allows good penetration into the thermoplastic material.

Still to ensure that the diodes are in contact with the thermoplastic material, it is also possible to coat them in a film of the material constituting the thermoplastic sheet. Fusion then leads to perfect homogeneity.

In the above, it is a question of a laminate comprising a spacer sheet. The invention can also be implemented by using a plurality of interlayer sheets. This arrangement is particularly necessary when the thickness of the interlayer sheet is not commercially available. The use of several sheets is also advantageous when to introduce the diodes in the interlayer a first sheet is provided with "housings" cut in the sheet dimensions and locations for receiving the diodes. In this case the pierced sheet of these housings is advantageously completed by a uniform sheet which protects the diodes against a rigid contact with the glass sheet.

In order to produce the products intended for wide distribution, it is always preferred to use the most usual constituent elements available on the market. In this sense, the interlayer sheets represent a significant part of the cost price of these products. It is therefore preferable to choose the sheets on the one hand of standard thickness, and on the other hand of thickness the smallest possible. For the necessary thickness, reference is made to what is said above. Advantageously, the choice of the diodes is at least partly controlled by their thickness so that they best meet this need to use the less thick interlayer sheets.

The invention is illustrated in detail in the rest of the description with reference to the drawing board in which:

4346 LAMLITE - Figure la shows schematically in section, the constituent elements before an assembly according to the invention before;

- Figure Ib is the product structure corresponding to Figure la, after the elements have been assembled; FIG. 2 is a block diagram of a process for forming an assembly according to the invention;

FIG. 3a is another set of constituent elements before assembly according to the invention;

- Figure 3b shows the assembly of the elements shown in 3a; FIG. 4 is a variant of FIG. 3a in which an adhesive is interposed in the assembly;

- Figure 5 is an assembly variant according to the invention in which each of the glass sheets is coated with a conductive layer.

In the representation of Figure 1, the assembly consists of two sheets of glass 1 and 2 joined by means of a spacer 3 PVB type.

The glass sheet 2 is coated with a conductive thin layer 4. The layer in question is one of those commonly used on glazing. The layer is obtained for example by pyrolysis, in particular CVD, ITO type layer, or SnO ₂ doped with fluorine or antimony, or by vacuum sputtering techniques, especially those comprising one or more metal layers associated with dielectric layers. Protective and "dereflective" or is a layer formed from ink or conductive paste applied by printing or screen printing means.

The conductive thin film 4 forms a network whose pattern is obtained either directly by printing the pattern or by locally interrupting the layer initially applied uniformly. This pattern can be achieved for example by the use of masks during the application or by localized ablation. The elimination of the layer is obtained in the traditional way, for example by mechanical or chemical abrasion or by laser treatment.

4346 LAMLITE The thickness of the layer must be sufficient to minimize its electrical resistance. On the other hand, when the light is to be transmitted through the sheet 2, the layer 4 must not be an obstacle to transmission. In this case the thickness of the layer is necessarily limited. To satisfy these two contradictory requirements it is advisable to choose the best compromise solution taking into account that the nature of the material constituting this layer also offers a certain latitude, all layers not having the same conductivity.

Typically the most conductive layers, especially those based on silver, may be a few nanometers. The less conductive layers may have a thickness of a few tens or even hundreds of nanometers.

Series of light-emitting diodes 6 are arranged on the surface of the sheet 2. The diodes are connected to the conductive network formed in the layer 4. The diodes are each connected to two separate conductors connected to each of the poles of the DC power supply. .

The conductors of each diode are connected to the conductive layer for example by points 7 of conductive adhesive in a manner known per se. The glue may optionally be replaced by any other similar fastening means known per se. Given the very thin thickness of the conductive layers, the adhesive is generally preferred.

In practice, most often the bonding points of the diode conductors ensure a sufficient attachment of the diodes to the substrate to support subsequent assembly operations. It is possible, however, to further glue the body of the diode 6 directly on the substrate. If an adhesive of this type is applied, it is preferably non-conductive so as not to risk disturbing the electrical circuit. As an indication, the diodes can be

4346 LAMLITE taken from an envelope of identical or compatible material with that of the interlayer sheet in which they must be incorporated.

The model shown in FIG. 1 on which the two poles of the supply circuit are arranged on the same sheet is preferred insofar as the setting up and fixing of the diodes are carried out before assembly, which makes it possible to guarantee efficient fixing. and specifies these diodes. However, it is possible, if necessary, to arrange each of the conductive supply elements respectively on the two sheets as indicated below with respect to FIG. 5.

FIGS. 3a and 3b show another method of assembly according to the invention in which the supply circuit of the diodes is disposed on a sheet 14 subsequently incorporated into the laminated assembly.

Sheets of this type are used for supporting layers intended for example for the protection against infra-red in glazing, particularly motor vehicles. The material used most often for these sheets is both resistant and very thin. It is most commonly polyterephthalate ethylene glycol (PET).

In the presentation of the constituent elements, the intermediate sheet 3 and the sheet leaving the electrical supply circuit are arranged separately.

In addition, the PET-type sheets, which do not adhere to the glass by themselves, are usually introduced between two interlayers. The additional sheet 15 which is advantageously of the same constituent as the sheet 3, is arranged to sandwich the sheet 14 thus ensuring good adhesion to the two sheets 1 and 2.

The different sheets are presented separately, nevertheless for the convenience of the assembly it may be preferable to carry out the preliminary formation of a subassembly comprising the sheet 14 provided with the feed circuit 4, and at least one of the intermediate sheets 15 or 3.

4346 LAMLITE When the sheets are thus gathered, the assembly mode described below with reference to the structures of the type shown in Figures la and Ib, applies in the same manner for the structures of Figures 3a and 3b.

The cost of PVB interlayer sheets makes it advantageous to use only one sheet in which the diodes are inserted. If a PET-type backing sheet is used, as in FIG. 3, which sheet is not likely to adhere alone to the glass sheet 2, it is possible to coat one side of either the glass sheet or the sheet 14, a thin film of adhesive 16. In Figure 4 the adhesive is shown applied to the glass sheet.

Advantageously, the adhesive may be thermoplastic in nature so that its activation is obtained at the time of assembly of the different sheets.

The embodiment of the invention presented in FIG. 5 differs from the previous ones in that two conductive layers constituting the two diode supply poles are supported by two distinct elements. In the case presented, the conductive layers 17 and 18 are arranged on each of the glass sheets 1 and 2. To assemble the diodes are previously arranged in the intermediate sheet, the conductors of the diodes being placed on both sides. other of the leaf. Still in this configuration it goes without saying that the fixing of the conductors of the diodes can not be performed before assembly. For this reason it is necessary to ensure the necessary contacts either during the assembly itself or by a subsequent operation. The assembly according to the invention comprising the formation by calendering, it is possible due to the pressure exerted on these conductors taken between the conductive layer and the face of the intermediate sheet to ensure sufficient contact. Nevertheless it is also possible, for example, to coat the conductors of the diodes with a conductive paste melting at the temperature of the assembly so that the "bonding" takes place at the time of assembly.

4346 LAMLITE The formation of the laminated assembly of panels comprising the diodes is carried out by implementing calendering techniques used for the production of traditional laminated glazings. The calendering operations according to the invention are shown schematically by way of example in FIG.

The process comprises, after fixing the diodes on the supply circuit carried by the sheet 2 as just said, the application of an intermediate sheet 3 of thickness e sufficient to incorporate the diodes 6, and then the implementation place the second sheet 1.

The sheets 1 and 2 are advantageously those from the glass production lines. These sheets can have dimensions of the order of 3x6m.

Given the size of the sheets the assembly methods comprising a degassing of the sheets by means of bags or vacuum rings, means traditionally used for the production of laminated automotive glazing and which are recommended in the earlier document, cited above, can not be conveniently implemented. It is necessary to proceed according to the degassing techniques by calendering.

The set of superposed sheets 8 is placed on a conveyor and sent to a furnace 9 for temperature heating, improving the malleability of the interlayer sheet and increasing its ability to adhere to the glass sheets. For a PVB sheet, the temperature is advantageously of the order of 40 to 70 ^° C.

The sheets thus heated are subjected to degassing by passing through a shell 10 schematically by two rollers.

The pressure exerted on the calendering is advantageously of the order of 2 to 10 bar, and preferably of 3 to 8 bar.

Calendering by compressing the sheets causes the diodes to penetrate into the interlayer sheet which is applied to the conductive layer 4 on the one hand, and

4346 LAMLITE on the face of the second sheet 1. The calendering removes most of the air present between sheets 1 and 2 and tab 3.

As indicated the good enveloping of the diodes by the material of the interlayer sheet depends on the plasticity of this material. It also depends on the outer shape of the diodes. These shapes can vary significantly depending in particular on the dimensions of the diodes and the plasticity of the material of the interlayer. If the latter is more resistant to the penetration of the diodes it may be preferable to avoid efforts that may deteriorate the fixing of diodes to develop housing in the intermediate sheet. It is also possible alternatively to give the face of the diode which is pressed in the material of the spacer an incisive shape, for example a wedge shape.

At this stage the leaves adhere to each other in a limited way.

The operation is renewed. The leaves pass into a second oven 11 raising the temperature between about 55 and 70 ⁰ C and undergo a second calendering at 12.

After these two calenders, not only the sheets adhere firmly, but in addition the edges are sufficiently glued to seal the assembly so that the air can not be introduced again between the sheets.

The homogenization of the assembly and the obtaining of the transparency are then completed by passage to the autoclave 13 at higher temperature and under pressure. Still for an intermediate sheet of PVB, the bearing temperature in the autoclave is of the order of 120 to 150 ^° C., and is maintained between 20 and 60 minutes. The pressure is between 8 and 15 bar. These conditions not only lead the intermediate sheet to marry the sheets 1 and 2 but in addition allow the dissolution of traces of air remaining in the assembly.

4346 LAMLITE The assembly mode described above, which comprises two calendering operations, may be limited to passage in a single oven. In this case, the first calendering, which leads to keeping the sheets in position relative to one another, is carried out at ambient temperature. The passage in the single oven is performed at temperatures that do not seal the edges of the leaves to allow a good degassing. This temperature is in the range from 55 to 70 ⁰ C. The sealing of the edges occurs accordingly at later stage in the autoclave.

The tests were carried out for assemblies consisting of sheets of glass 3.15 mm thick, one of which is coated with a layer of antimony-doped tin oxide.

Different thicknesses of PVB interlayer sheets are used to determine the conditions necessary to obtain good incorporation of the diodes. The thicknesses in question are obtained by superposition of PVB sheets 0.38 mm thick. (0.76, 1.14, 1.52 ... mm).

The conductive circuit is made by laser ablation forming insulating grooves of 0.15 mm wide between the conductive zones. The diodes used are sold under the name Osram type LWL283. The dimensions of the diodes are 1.7x0.8mm for different thicknesses: 0.6mm, 0.8mm and 1.2mm.

The conductors of the diodes are glued to the conductive layer by means of a glue that is also conductive.

The diodes are arranged in a regular mesh, 5 cm apart. The assembly performed as indicated above, leads to a product in which the diodes are indeed well incorporated in the sheet without intervening bubble for the thicknesses of PVB greater than the thicknesses of the diodes.

4346 LAMLITE As a general rule, for this type of incorporation of the diodes by calendering, it is advantageous to maintain a PVB thickness of about 20% greater than the thickness of the diodes.

In a particularly surprising manner, the incorporation of the diodes is carried out without difficulty and under the conditions which are generally those used to form laminated glazings. The presence of the diodes does not significantly affect the conditions necessary for this assembly. In the same way it is remarkable that the diodes and their fasteners are resistant to the pressures exerted during calendering in particular.

4346 LAMLITE

Claims

A laminated assembly incorporating light-emitting diodes comprising a first rigid sheet of a dielectric material, at least one conductive electrical network applied in the form of a thin layer either on the rigid sheet or on a non-conducting thin sheet supporting this network, which network feeds a multiplicity of light-emitting diodes, and at least one sheet of a substantially transparent, electrically non-conductive plastic material uniformly covering the rigid sheet and the diodes, by wrapping them, possibly a second sheet rigid material adhering to the sheet of plastic material, at least one of the rigid sheets being transparent to light, the plastic material enveloping the diodes having a thickness at least equal to that of the diodes the assembly made up comprising at least one calendering operation for fixing leaves between them, and incorporate the diodes in the sheet of plastic material.

2. Laminated assembly according to claim 1 wherein the material enveloping the diodes adheres to the rigid sheet (s) is applied to the diodes so as to marry the latter under the effect of pressure and or heat.

3. Laminated assembly according to claim 1 wherein the plastic material sheet is formed on the first rigid sheet comprising the electrical network and the diodes, by crosslinking or polymerization of a liquid composition poured on said sheet.

4. An assembly according to claim 1 wherein the sheet of plastic material, prior to its application to the first rigid sheet comprising the conductive network and the diodes is subjected to embossing or cutting housing in a distribution and dimensions corresponding essentially to the distribution and dimensions of the diodes, the application of said sheet leading each diode in a housing in said sheet.

4346 LAMLITE

5. The assembly of claim 1, wherein the plastic material is one of the group comprising polyvinyl acetals, polyvinyl chlorides, polyolefins, polyurethanes, ionomer resins.

6. 6. Assembly according to one of the preceding claims wherein the two rigid sheets are constituted by glass sheets or sheets of material based on polyacrylates or polycarbonates.

An assembly according to any one of the preceding claims wherein the envelope of the light emitting diodes has a shape that facilitates a gap-free contact with the non-conductive plastic material in which they are wrapped.

8. Assembly according to claim 1 wherein the calendering is performed in a partial vacuum chamber.

9. An assembly according to claim 6 wherein the rigid sheets are two sheets of glass, the sheet of plastic material is a PVB sheet, assembly obtained by calendering the three sheets and autoclaving at a temperature and pressure leading to the homogenization and gluing of the different leaves together.

10. The assembly of claim 1 wherein before application to the first rigid sheet, the diodes and the elements ensuring electrical contact with the conductive network are supported by the plastic sheet which is associated with the sheet carrying the electrical circuit of food.

The assembly of claim 10 wherein the diode-supporting plastics material is a PVB sheet and the electrical-circuit-carrying sheet is a PET sheet.

12. An assembly according to claim 1 wherein two rigid sheets each carry a conductive layer, the diodes being in contact with each of these layers.

4346 LAMLITE