Glass panel for display system

Abstract

A glazing for information display includes an assembly of at least two transparent sheets of inorganic glass or of a plastic, connected together by a thermoplastic or adhesive interlayer or by multilayer sheets incorporating such an interlayer, at least one luminophore material being incorporated into the glazing to enable the display, wherein one of the luminophores includes a benzene ring substituted at least by: two hydroxyl OH groups, a carbon-based R group, the R group including an unsaturated heterocycle, a carbon-based R group of formula COOR, wherein R is a hydrocarbon-based group or hydrogen.

Claims

1. A glazing for information display comprising an assembly of at least two transparent sheets of inorganic glass or of a rigid plastic, connected together by a thermoplastic or adhesive interlayer or by multilayer sheets incorporating such an interlayer, at least one luminophore material being incorporated into said glazing to enable said display, wherein the at least one luminophore material comprises a benzene ring substituted at least by: two hydroxyl OH groups, a carbon-based R group, said R group comprising a heterocycle, a carbon-based R group of formula COOR, wherein R is a hydrocarbon-based group or hydrogen.

2. The glazing as claimed in claim 1, wherein said heterocycle is unsaturated.

3. The glazing as claimed in claim 2, wherein said heterocycle is aromatic.

4. The glazing as claimed in claim 3, wherein the electrons of the unsaturated or aromatic ring enter into resonance with the electrons of the benzene ring.

5. The glazing as claimed in claim 1, wherein the two hydroxyl groups are in para position with respect to one another and wherein the R and R groups are in para position with respect to one another.

6. The glazing as claimed in claim 1, wherein said heterocycle comprises at least one nitrogen atom.

7. The glazing as claimed in claim 1, wherein R is a COOR ester group, wherein R is a hydrocarbon-based chain comprising from 1 to 15 carbon atoms, limits included.

8. The glazing as claimed in claim 1, wherein R is a hydrocarbon-based chain comprising a main carbon-based chain comprising more than 5 successively bonded carbon atoms.

9. The glazing as claimed in claim 1, wherein R is a linear or branched carbon-based group comprising a main carbon-based chain comprising more than 5 consecutive carbon atoms, said R group comprising, if said chain is linear, more than 10 carbon atoms in total and, if said chain is branched, at least 7 carbon atoms in total.

10. The glazing as claimed in claim 1, wherein said R group comprises an unsaturated heterocycle and a benzene ring.

11. The glazing as claimed in claim 1, wherein said R group comprises a benzoxazole group: ##STR00007##

12. The glazing as claimed in claim 1, wherein said R group comprises a benzimidazole group: ##STR00008##

13. The glazing as claimed in claim 1, wherein the interlayer is made of thermoplastic and wherein said luminophore material is dispersed in said thermoplastic.

14. The glazing as claimed in claim 1, wherein the thermoplastic constituting said interlayer is selected from the group consisting of PVBs, plasticized PVCs, polyurethane PU and ethylene/vinyl acetates EVAs.

15. A motor vehicle or aviation windshield consisting of glazing as claimed in claim 1, comprising an assembly of two transparent sheets, consisting of inorganic glass or of plastic, connected together by a thermoplastic or adhesive interlayer.

16. A glazing for a building, in particular a store window, a spandrel glass or a dividing wall or partition, as claimed in claim 1.

17. A device for displaying an image on transparent glazing, comprising a glazing as claimed in claim 1 and a source configured to generate concentrated excitation radiation of diode type, the radiation of which is between 350 and 410 nm, the excitation radiation being directed toward an area of the glazing comprising the luminophore material.

18. The motor vehicle or aviation windshield as claimed in claim 15, wherein the plastic is PMMA or polycarbonate.

19. The device as claimed in claim 17, wherein the diode is a laser diode.

Description

BRIEF DESCRIPTION OF THE DRAWING

(1) The FIGURE is a schematic illustration of a windshield and a device positioned in a passenger compartment of a motor vehicle (not shown).

DETAILED DESCRIPTION OF THE INVENTION

(2) The invention and its advantages will be better understood on reading the following embodiment of the invention, in connection with the single appended FIGURE.

(3) The appended FIGURE makes it possible to illustrate the invention and its advantages.

(4) In this FIGURE, a windshield and a device according to the invention are schematically represented:

(5) The windshield 1 is composed of two sheets 2 and 9 typically made of glass but which could also consist of rigid and strong plastic supports or sheets, for example made of polycarbonate. Present between the two sheets is a thermoplastic interlayer sheet 3 such as PVB (polyvinyl butyral), plasticized PVC, PU or EVA or else a multilayer thermoplastic sheet incorporating for example PET (polyethylene terephthalate), the succession of the layers in which is for example PVB/PET/PVB.

(6) Particles of organic luminophore according to the invention are inserted into the interlayer thermoplastic sheet 3 before the assembly of the various sheets, either directly during the extrusion of the thermoplastic sheet, or by virtue of a deposition by one of the techniques mentioned below. The deposition is carried out over at least one portion of the inner face of the inner sheet of the glazing or over at least one portion of the inner face of the thermoplastic sheet.

(7) Preferably, the luminophore particles before lamination have a size distribution predominantly between 1 and 100 microns. The term predominantly is understood to mean that more than 90% of the particles making up the commercial powder have a diameter of between 1 and 100 microns.

(8) A source 4 that emits excitation light radiation is used to send incident concentrated radiation 7 having a wavelength close to 400 nm. The luminophore 10, present in molecular form in the interlayer thermoplastic sheet 3 after lamination, has a high absorption coefficient for the incident radiation. It therefore reemits intense radiation in the visible range.

(9) The visible radiation emitted by the luminophore is then directly observable by the eye 5 of the driver, who thus sees the object on the windshield without having to avert his eyes from the road. In this way, an image can be directly formed on a laminated windshield without it being necessary to adapt the structure of the latter, for example the thickness of the interlayer sheet, thereby enabling economical production of HUD systems.

(10) The source used for generating the concentrated radiation is for example a UV-visible source of diode, optionally laser diode, type.

(11) According to one possible embodiment, it is possible to use a DLP projector in order to modulate the excitation wave according to the method described in patent application US 2005/231652, paragraph [0021]. It is also possible according to the invention to use, as UV-visible excitation source, a device as described in patent application US 2004/0232826, in particular as described in connection with FIG. 3.

(12) As indicated above, the luminophore may be inserted into the PVB sheet during the extrusion of the latter, or else it may be deposited on the glass or the PVB sheet for example by screenprinting, spraying, roller, coating or inkjet techniques or else by techniques of the offset, flexographic or photogravure type.

(13) Preferably, the deposition by one of the preceding techniques is carried out after dissolving or dispersing the luminophore particles in a solvent that evaporates rapidly, and which may also contain, in dissolved form, material constituting the thermoplastic sheet, for example PVB, in order to facilitate the incorporation of the luminophore into the thermoplastic sheet when the latter is itself made of PVB.

(14) It has been found by the applicant that, within the context of an application for displaying an image by means of transparent glazing, the use of luminophores according to the invention makes it possible to effectively meet the following requirements, necessary for such an application: a) an acceptable sharpness of the image, b) a luminescence intensity sufficient for it to be observable by the driver, c) a light transmission greater than 70%.
The preceding embodiment obviously in no way limits the present invention, in any of the aspects described above.

EXAMPLES

(15) The following examples make it possible to illustrate an exemplary embodiment of a laminated windshield according to the present invention and the advantages thereof with respect to the prior art.

(16) In the examples, various comparative laminated glazings and laminated glazings according to the present invention are synthesized. All the glazings comprise the succession of two sheets of glass connected by a PVB interlayer sheet having a thickness of 760 microns. The assembly is carried out according to the well-known techniques of the art.

(17) Prior to the lamination, a layer of luminophores, the structural formula of which is given below, is deposited as a square with dimensions of approximately 1010 cm.sup.2 by a conventional spraying technique onto the inner glass sheet 2 and onto its side facing the PVB sheet, before the assembly step (see FIGURE).

(18) More specifically, the luminophore is diluted beforehand in a solvent of ethanol or tetrahydrofuran (THF) type. The dilution is carried out close to the maximum solubility of the luminophore in the solvent in order to minimize the volume of solution.

(19) The mixture is then deposited by spraying according to conventional techniques on the glass sheet, so as to obtain, after drying of the solvent, a weight of solids of the order of 5 g per m.sup.2 of glass.

(20) Next, the solvent is left to evaporate and then the lamination is carried out with the two glass sheets and the PVB sheet according to autoclave techniques conventional in the field. A windshield as illustrated in the FIGURE is thus obtained.

(21) The parameters described above were measured on the various glazings obtained, according to the following protocols:

(22) The heat resistance of the glazing was carried out in accordance with the test described in the European standard ECE R43 A3/5.

(23) The absolute luminescence intensities were measured by a UV-visible spectrometer and compared to one another by dividing the maximum luminescence intensity by the molecular concentration of luminophores, for all of the molecules tested. A reference intensity 100 is attributed to the reference compound according to example 1.

(24) The emissions that lie in wavelength ranges in which the sensitivity of the human eye varies greatly with the wavelength (in particular with a greater sensitivity in the green-yellow range). The relative luminances, taking into account the luminous efficacy of the human eye as a function of the emission wavelength, are also calculated on the basis of the preceding data, for all of the modules tested, for one and the same molecular concentration.

(25) The durability to incident solar UV radiation was measured by the WOM Arizona test which consists in exposing the glazing to radiation emitted by a xenon arc lamp in order to simulate solar radiation according to the ISO 4892 (part 2) standard at a temperature of 90 C. Such exposure enables accelerated aging of the luminophore by a factor of approximately 10. The measurement of the luminance after 3000 hours exposure (therefore corresponding substantially to 3 years of use under actual conditions), relative to the initial luminance, makes it possible to estimate and to compare, directly and simply, the durability properties of the various luminophores under UV radiation.

(26) The durability under excitation radiation was measured according to the following method:

(27) A power diode having an emission wavelength equal to 405 nm was directed directly onto the portion of the glazing comprising the luminophore layer, over a surface area of around 1 mm.sup.2. A luminance meter is directed at the light spot emitted and the luminance in cd/m.sup.2 is measured continuously.

(28) Measured next, after 500 h, is the relative luminance of the irradiated part, on the basis of the initial luminance, this value characterizing, according to the invention, the durability of the luminophore under the incident concentrated radiation. The continuous illumination by a fixed spot of great power may lead to a rapid degradation of the luminophore and therefore to a rapid reduction in its luminance. A relative luminance of 1 indicates in particular that the luminophore is perfectly stable under the incident UV radiation.

(29) The values measured for these various parameters are reported in table 1 below.

(30) The various molecules tested correspond to the formulations described hereinafter.

(31) The comparative compound according to example 1 is the commercial product diethyl 2,5-dihydroxyterephthalate identified under the CAS number 5870-38-2. It has been described in patent application WO 2010/139889.

(32) The other molecules are obtained by virtue of the following methods of synthesis: For the molecule according to example 2: diethyl 2,5-dihydroxyterephthalate and potassium hydroxide are refluxed in ethanol. The product obtained is treated in the presence of SOCl.sub.2, then is reacted with aminophenol in the presence of methanesulfonic acid in order to obtain the compound described below. The structure of the compound was verified by customary techniques in the field (NMR, mass spectroscopy, etc.). For the molecule according to example 3: 2,5-dihydroxyterephthalic acid is condensed with aminophenol in the presence of polyphosphoric acid. The product obtained undergoes an esterification reaction with 1-dodecanol in the presence of PTSA (para-toluenesulfonic acid) in toluene, in order to obtain the compound described below. For the molecule according to example 4: a mixture of diethyl 2,5-dihydroxyterephthalate and potassium hydroxide are refluxed in ethanol. The product obtained is treated in the presence of SOCl.sub.2, then is reacted with diaminobenzene in the presence of methanesulfonic acid in order to obtain the compound according to the example 4 described below.

(33) The molecules synthesized are: Example 1 (according to WO 2010/139889):

(34) ##STR00003## Example 2 (according to the invention):

(35) ##STR00004## Example 3 (according to the invention):

(36) ##STR00005## Example 4 (according to the invention):

(37) ##STR00006##
All of the results obtained are collated in table 1:

(38) TABLE-US-00001 TABLE 1 Example 1 Example 2 Example 3 Example 4 (reference) (invention) (invention) (invention) Color of the luminophore Very weak Light yellow Light yellow Very weak yellow yellow color color color color Heat resistance In accordance In accordance In accordance In accordance (ECE R43 A3/5) Light transmission >70% >70% >70% >70% Durability under UV radiation 100 100 100 75 (as % of the initial luminance after 3000 h) (nm) corresponding to the 450 nm 595 nm 595 nm 575 nm emission maximum under UV excitation Perceived color Blue Orange Orange Orangey yellow Absolute (molar) 100 20 35 35 luminescence intensity at emission .sub.max (.sub.exc = 405 nm) Molar relative luminance 100 55 90 160 under UV excitation

(39) The results reported in table 1, in comparison with the reference luminophore according to example 1, show that the properties of durability under UV radiation (Arizona) are satisfactory for all the compounds tested. Furthermore, all are in accordance with the heat resistance tests.

(40) The emission color of the sample according to example 4 appears to be orangey yellow, with an emission maximum centered about 575 nm, while the emission color of the samples according to examples 2 and 3 is orange, with an emission maximum centered about 595 nm. The maximum (absolute) luminescence intensity of the three compounds appears to be lower than that of the reference compound, although still high, in particular with regard to the very high Stokes shift between the absorption bands and the emission bands of the compounds according to the invention. This lower performance with respect to the reference compound is however compensated for by the greater sensitivity of the eye for yellow and orange colors. Thus, the relative luminance (i.e. taking into account the sensitivity of the eye) of the three compounds under UV excitation approaches the luminance of the reference compound, or even exceeds it.

(41) Moreover, surprisingly, it is observed that the luminance of the luminophore according to example 2 may be increased further with the lengthening of the carbon-based chain present in the ester group positioned on the benzene ring. In the end, the luminophores according to the invention appear perfectly compatible with the reference compound for allowing the display of color images on glazing according to the invention.

(42) In the foregoing description, the present invention has been described in connection with the use of glazing under laser excitation. It is very obvious that the present invention is not limited to this excitation method and that other sources of radiation, in particular power light-emitting diodes, may be used as source of excitation radiation, for example for displaying pictograms preprinted on said glazing, as described in patent application WO 2009/122094 or FR2929017.

(43) Also, the invention relates to any glazing comprising a luminophore according to the invention, optionally as a mixture with other luminophores emitting in other colors of the visible spectrum, in particular for obtaining a polychromatic image.