Glass panel for display system

Abstract

A glazing for information display includes an assembly of two transparent inorganic or plastic sheets, connected together by a thermoplastic or adhesive interlayer or by multilayer sheets incorporating the interlayer, wherein a luminophore material is incorporated to enable the display. One of the luminophores includes a benzene ring substituted at least by: a first ester COOR group, wherein R is a linear or branched carbon-based group including a main carbon-based chain of at least six consecutive carbon atoms, the R group including, if the chain is linear, more than 10 carbon atoms and, if the chain is branched, at least 7 carbon atoms, optionally a second COOR group, wherein R is another hydrocarbon-based group or hydrogen, the second group optionally being in para position on the benzene ring with respect to the first ester group, two hydroxyl OH groups that are optionally in para position on the benzene ring.

Claims

1. A glazing for information display comprising an assembly of two transparent sheets, consisting of inorganic glass or of plastic, the two sheets being connected together by a thermoplastic or adhesive interlayer or by multilayer sheets incorporating such an interlayer, at least one luminophore material enabling said display being incorporated into said glazing, wherein at least one of said luminophore materials comprises a benzene ring substituted at least by: at least a first ester COOR group, wherein R is a linear or branched carbon-based group comprising a main carbon-based chain of at least eleven carbon atoms bonded to one another consecutively, and two hydroxyl OH groups.

2. The glazing as claimed in claim 1, wherein said benzene ring is substituted by a second COOR group, wherein R is another hydrocarbon-based group or hydrogen.

3. The glazing as claimed in claim 1, wherein one of said luminophore materials comprises a benzene ring substituted by four groups, including: two ester groups, respectively COOR and COOR; R and R being linear or branched carbon-based groups comprising a main carbon-based chain of at least eleven consecutively bonded carbon atoms, and two hydroxyl OH groups.

4. The glazing as claimed in claim 2, wherein R and R are identical carbon-based groups.

5. The glazing as claimed in claim 2, wherein R and R are linear carbon-based groups, the linear carbon-based groups in R and R comprising at least eleven successive carbon atoms.

6. The glazing as claimed in claim 1, wherein said luminophore is a dialkyl 2,5-dihydroxyterephthalate corresponding to the structural formula: ##STR00011##

7. The glazing as claimed in claim 1, wherein said luminophore is a dialkyl 2,5-dihydroxyterephthalate corresponding to the structural formula; ##STR00012##

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

9. 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.

10. 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 strong plastic, connected together by a thermoplastic or adhesive interlayer.

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

12. A device for displaying an image on transparent glazing, comprising 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.

13. The glazing as claimed in claim 1, wherein the two hydroxyl groups are in para position on the benzene ring.

14. The glazing as claimed in claim 2, wherein said second group is in para position on the benzene ring with respect to said first ester group.

15. The glazing as claimed in claim 3, wherein the two ester groups, respectively COOR and COOR, of the benzene ring substituted by four groups are in para position on the benzene ring, and wherein the two hydroxyl groups of the benzene ring substituted by four groups are in para position on the benzene ring.

16. The glazing as claimed in claim 5, wherein R and R are linear carbon-based groups comprising between 11 and 15 successive carbon atoms.

17. The motor vehicle or aviation windshield as claimed in claim 10, wherein the strong plastic is PMMA or polycarbonate.

18. The device as claimed in claim 12, wherein the diode is a laser diode.

Description

(1) The invention and its advantages will be better understood on reading the following embodiment of a laminated windshield according to the invention, in connection with the single appended FIGURE.

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

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

(4) The windshield 1 is composed of two sheets 2 and 9 typically made of glass but which could also consist of strong plastic sheets of polycarbonate type. Present between the two sheets is a plastic 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.

(5) 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 above. 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.

(6) 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.

(7) A laser 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.

(8) 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.

(9) The source used for generating the concentrated radiation is for example a UV-visible source of laser type. It is for example, but not limitingly, of solid-state laser, semiconductor laser diode, gas laser, dye laser or excimer laser type. Generally, any known source that generates a concentrated and directed flux, within the meaning of the present invention, of UV-visible radiation may be used as excitation source according to the invention.

(10) 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.

(11) 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.

(12) 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.

(13) 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

(14) 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.

(15) 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.

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

(17) 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.

(18) 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.

(19) 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.

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

(21) The haze was measured according to the motor vehicle standard Ansi Z26.1 (1996).

(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 coloration of the glazing was measured by the Yellowness Index test according to the DIN 6167 standard, after 400 hours of exposure of the glazing to the Arizona test described above.

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

(28) A laser beam having a power of 200 mW and a wavelength equal to 405 nm was directed directly onto the portion of the glazing comprising the luminophore layer, over a surface area of around 2 mm.sup.2. A luminance meter is directed at the light spot emitted and the luminance in cd/m.sup.2 is measured continuously. Thus, the time needed for the initial luminance to be halved is measured, this value characterizing, according to the invention, the durability of the luminophore under the incident concentrated radiation.

(29) 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.

(30) The molecules tested all correspond to the following general formula:

(31) ##STR00004##

(32) They are obtained by esterification of 2,5-dihydroxyterephthalic acid with alcohols ROH for examples 1 to 5, or by reaction of the acid with N,N-dimethylformamide di-tert-butyl acetal for example 6.

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

(34) ##STR00005## Example 2 (according to WO 2010/139889):

(35) ##STR00006## Example 3 (comparative):

(36) ##STR00007## Example 4 (according to the invention):

(37) ##STR00008## Example 5 (according to the invention):

(38) ##STR00009## Example 6 (comparative):

(39) ##STR00010##

(40) All of the results obtained are collated in table 1:

(41) TABLE-US-00001 TABLE 1 Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 (reference) (reference) (comparative) (invention) (invention) (comparative) Yellowness index No yellowing No yellowing No yellowing No yellowing No yellowing No yellowing (DIN 6167) after 400 h Heat resistance in accordance in accordance in accordance in accordance in accordance in accordance (ECE R43 A3/5) Light transmission >70% >70% >70% >70% >70% >70% Durability under UV 100 100 100 100 100 70 radiation UV (in % of the initial luminance at 450 nm after 3000 h) Maximum emission 450 nm 450 nm 450 nm 450 nm 450 nm 450 nm (nm) under laser beam (405 nm, 200 mW) Perceived color Blue Blue Blue Blue Blue Blue Relative luminance at 100 95 100 130 180 95 450 nm (.sub.exc = 405 nm) Durability under laser >100 hours >100 hours >100 hours >100 hours >100 hours >100 hours excitation (405 nm, 200 mW)

(42) The results reported in table 1, in comparison with the reference luminophore according to example 1, show that the properties of luminescence and durability under laser excitation are similar for all the compounds tested. Furthermore, all are in accordance with the yellowness index and heat resistance tests.

(43) The (Arizona) aging tests under UV radiation also show that all the compounds are in accordance, with the exception of the comparative compound according to example 6, the hydrocarbon-based chains of which, R and R, are branched groups of tert-butyl type, not in accordance with the subject of the invention.

(44) The luminance measurements show that the compounds according to the invention, comprising a group incorporating a linear carbon-based chain of at least 6 atoms, have luminance values, at identical molar concentration, which are much higher than the reference compounds, enabling improved visualization of the information displayed, especially under conditions of strong illumination of the glazing.

(45) 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.

(46) Also, the invention relates to any glazing comprising a luminophore according to the invention, optionally as a mixture with other luminophores optionally emitting in other colors of the visible spectrum.