FR2914070A1 - HEAD VISUALIZATION DEVICE. - Google Patents

Abstract

The present invention describes a laminated window pane of automobile windshield type or building glazing component HUD, comprising an assembly of at least two transparent sheets of inorganic glass or a resistant organic material of the PC type, interconnected by an interlayer of a thermoformable material or multilayer leaflets incorporating such an interlayer, said glazing being characterized in that it further comprises, on at least a part of its structure, a thin layer less than 50 microns thick comprising at least one luminophor material in the form of particles whose size is adjusted so that the light transmission of said glazing remains greater than 70%, said phosphor material emitting a radiation in the visible range when subjected to an excitatory light incident wave in the ultraviolet range, and in that, in the assembly, said layer is positioned between the thermoformable interlayer and the passenger compartment of the vehicle or the interior of the building.

Description

FL2 HEAD VISUALIZING DEVICE HIGH

  The present invention relates to the field of visualization systems projected on transparent type screens, in particular automobile windshields or building glazings.

  In particular, even though it is not limited thereto, the present invention relates to the field of head-up display systems, called HUD or Head Up Display in the art. Such systems are useful in particular in aircraft cockpits, trains but also today in passenger cars (cars, trucks, etc.).

  In such systems, the glazing generally consists of a sandwich structure, most simply comprising two sheets of resistant material such as glass sheets or hard plastic, for example PC polycarbonate type. The sheets of resistant material are interconnected by a thermoformable interlayer sheet comprising or consisting most often of polyvinyl butyral (PVB).

  Such head-up display systems, displaying information projected on a glazing which is reflected towards the driver or the observer, are already known. These systems make it possible in particular to inform the driver of the vehicle without the driver keeping his eyes away from the field of vision in front of the vehicle, which consequently increases safety. The driver perceives a virtual image that is some distance behind the windshield. In the most conventional manner, such an additional image is obtained on a windshield by projecting information on a windshield having a laminated structure, that is to say formed of two sheets of glass and a material interlayer. plastic. However, the driver then observes a double image: a first image reflected by the surface of the windshield facing the interior of the habitable and a second image by reflection of the outer surface of the windshield, these two images being slightly offset one with respect to the other. This gap can disrupt the vision of information. To alleviate this problem, mention may be made, as a proposed solution, of US Pat. No. 5,013,134 which describes a head-up display system using a laminated windshield formed of two sheets of glass and a polyvinyl butyral interlayer (PVB) whose two faces exterior are not parallel but wedge-shaped, so that the image projected by a display source and reflected by the face of the windshield facing the cabin is almost superimposed on the same image from the same source reflected by the face of the windshield facing outward. To achieve this laminated glazing wedge is used an intermediate sheet whose thickness decreases from the upper edge of the glazing at the lower edge. However, this solution, if it is satisfactory in terms of suppression of the double image, nevertheless has disadvantages. In particular, the assembly of the laminated glazing requires greater precautions, especially when passing through a calender, because of the faces of the two nonparallel glass sheets. In addition, the angle of the corner PVB must be perfectly adjusted to the specific configuration. It is also important that the profile of the PVB is very regular and does not show variations in thickness, because they are transmitted during assembly on the windshield and lead to local variations of angle. In addition, with a laminated structure comprising two sheets of glass it is not possible to produce wedge-shaped glazing over only a portion of their height, unless machining the face of the glass sheet oriented towards the cockpit, which is very difficult to implement and almost impossible if it is a curved glass sheet.

  The present solution proposes an alternative solution in which the image of an object is formed directly on the windshield or the glazing. For this purpose, a laminated glazing unit as described above is used, but in its conventional version with a polyvinyl butyral (PVB) type interlayer whose two outer faces are parallel but in which a layer of phosphors chosen to respond to an excitatory light incident wave. in the field of the ultraviolet and re-emit radiation in the visible range, allows to restore directly on the windshield or glazing image of the object. By application of the present invention, it is for example possible to obtain a windshield or glazing for building with HUD properties, the manufacturing process is simple and economical to implement, without having to substantially modify the different components (in particular the PVB sheet or the equivalent) used in a conventional method of manufacturing said automobile windshield or said glazing, or the steps of this process.

  More specifically, the present invention relates to a laminated glazing of automotive windshield type or glazing for building with component HUD, comprising an assembly of at least two transparent sheets of inorganic glass or a resistant organic material of the PC type. , interconnected by a spacer of a thermoformable material or by multilayer sheets incorporating such an interlayer. The glazing according to the invention is characterized in that it further comprises, on at least a part of its structure, a thin layer of thickness less than 50 microns, comprising at least one phosphor material in the form of particles whose size is adjusted so that the light transmission of said glazing remains greater than 70%, said phosphor material reissuing a radiation in the visible range when it is subjected to an excitatory light incident wave in the ultraviolet range. Preferably, said thin layer has a thickness of less than 30 m, even less than 20 m or even less than 10 m.

  The glazing according to the invention is further characterized in that, in the assembly, said layer is positioned between the thermoformable interlayer and the passenger compartment of the vehicle or the interior of the building. For example, said thin layer is placed on the face of the interlayer or thermoplastic sheet facing the passenger compartment of the vehicle or the interior of the building.

  According to other embodiments, said thin layer may also be disposed on the outer or inner face of the transparent sheet positioned in the assembly on the side of the passenger compartment of the vehicle or the interior of the building. It was found by the applicant that the positioning of the phosphor layer in such a position in the stack could significantly improve the performance of the system and more particularly the quality of the image restored and materialized on the glazing, particularly in level of intensity, contrast and sharpness of said image. According to the invention, the thermoformable material constituting said interlayer can be chosen from the group of PVB, plasticized PVC, polyurethane PU or ethylene vinyl acetate EVA. Preferably, the thermoformable material is PVB.

  FL2 2007025 EN 4 Alternatively, the transparent sheets are interconnected by a multilayer sheet incorporating a PVB interlayer, for example a sheet comprising a succession of PVB / PET / PVB layers, wherein PET is polyethylene terephthalate. According to the invention, the phosphor particles are of nanometric size.

  According to an advantageous embodiment of the invention and for a given thin layer, the phosphor particles are selected according to their scattering cross section. The scattering cross section of a particle corresponds to the equivalent surface area of interaction of said particle with incident radiation for a given wavelength, in this case located in the visible range. It depends on the ratio between the refractive index of the particle and that of the thin layer as well as the ratio between the particle diameter and the wavelength of the incident radiation. One method of determining this magnitude is found in Light Scattering by Small Particles, (H.C. Van de Hulst, John W. Wiley and Sons, New York, 1957), in Chapter 9, pages 114-130.

  According to one possible embodiment, the thin film incorporated in the laminated glazing unit comprises at least one luminophor material emitting in the red, a phosphor material emitting in the blue and a phosphor material emitting in the green, under a UV excitation. Said thin film comprises different luminophores distributed randomly within said layer, arranged in successive bands in said layer or separated in different regions of said layer in the form of color pixels. The concentration of the phosphor particles in the thin layer and / or their diffusion cross section are advantageously chosen in order to limit the blur (hedge) and to ensure adequate light transmission. The product-defined parameter of the particle concentration scattering cross-section has been found to be particularly relevant for this purpose. According to advantageous embodiments of the invention, the thin layer is deposited on the thermoplastic sheet or on the transparent sheet by a technique chosen from screen-printing techniques, inkjet-type techniques or else offset-type, flexographic techniques. or gravure. The invention furthermore relates to a device for displaying an image on a transparent glazing unit comprising a laminated glazing unit as described above and a source generating UV radiation, the ultraviolet beam being directed towards the one or more areas of the glazing including the phosphor layer. The source of UV radiation can be selected from sources of the LED type, Xenon lamp, Mercury lamp, halide arc lamp. The source generating UV radiation may also according to the invention be chosen from UV laser sources, for example of the solid state laser type, semiconductor laser diode, gas lasers, dye lasers, excimer lasers. According to one possible mode, the display device may furthermore comprise means for modulating the excitation wave, said means making it possible to modulate the UV radiation for a selective excitation of the phosphors present in said layer.

  The invention and its advantages will be better understood on reading the embodiment of the invention which follows, in relation to the single figure attached. The attached figure illustrates the invention and its advantages: In this figure, a windshield and a device according to the invention are shown schematically: The windshield 1 consists of two sheets 2 and 9, typically made of glass. but which could also consist of sheets of resistant plastic of the polycarbonate type. Between the two sheets, there is a plastic interlayer 3 such as PVB (polyvinyl butyral), plasticized PVC, PU or EVA or a multilayer thermoplastic sheet incorporating for example PET (polyethylene terephthalate), the succession of layers is for example PVB / PET / PVB.

  At least a portion of the internal face 3 'of the intermediate thermoplastic sheet 3 has been deposited before lamination, ie before the assembly of the different sheets, a layer of phosphor particles of nanometric size, the characteristics of which are adjusted so that the light transmission remains greater than 70% and preferably greater than 75% and in such a way that the haze, measured according to the Anspi Z26.1 1996 standard, remains less than 2% and preferably less than at 1%. In particular, these particles are of nanometric size, that is to say that their size is of the order of a few hundred nanometers, and preferably a few tens of nanometers or even a few nanometers. Their size is chosen to be much smaller than the wavelength of the visible radiation, such that the scattering of light by the particles is minimized and the glazing remains transparent. A source of electromagnetic radiation 4 is used to send incident radiation 7 of appropriate wavelength, particularly in the ultraviolet range. The phosphors are chosen to have a high absorption coefficient of the incident radiation. They are also chosen to then re-emit radiation in the visible range, that is to say a radiation located in the 380-700 m range, preferably with a high efficiency. The visible radiation is then directly observable by the driver's eye 5, which thus visualizes the object on the windshield without having to leave the road of the eyes. In this way, an image can be directly materialized on a laminated windshield without the need to adapt the structure thereof, for example the thickness of the interlayer sheet, which allows an economical manufacture of HUD systems. In addition, it was found by the applicant that the positioning of the phosphor layer on the inside of the PVB sheet, as shown in the figure, surprisingly made it possible to substantially improve the intensity, the contrast and the sharpness of the film. the image. More particularly, visualization tests were performed on an image obtained on two windshields, one according to the invention, the other not in accordance with the invention. According to a first embodiment of a windshield according to the invention, a phosphor layer is positioned in the assembly on the inner face 3 'of an interlayer sheet 3 made of PVB, as shown in FIG. second embodiment of a windshield not in accordance with the invention, a phosphor layer identical to the previous one is this time positioned in an assembly of the same nature on the inner face 3 "of the interlayer sheet 3 PVB.

  In accordance with the foregoing description, a plurality of images at the layer 6 were then visualized with a sample of observers, positioned in the theoretical position of the driver, by means of a laser excitation source projecting thereon on the excitation UV radiation characteristic of the phosphors of the layer, the windscreen being otherwise illuminated on its other face by radiation representative of average insolation conditions during the day. All observers have selected the glazing according to the invention as that offering the best images both in terms of contrast, sharpness and intensity of the image. FL2 One possible explanation would be that the intermediate sheet makes it possible to prevent or at least limit the effects of parasitic excitation of the phosphors by the solar UV radiation, more particularly when the windshield or the glazing is subjected to an average or a strong sunshine.

  Similar results of improvement of the visualized image were observed if the phosphor layer was placed this time on the inner face or on the outer face of the glass sheet 2.

  The phosphors that can be used can be of any type known to respond to UV excitation and emission in the visible range. Such materials may for example be chosen in the field of inorganic phosphors, for example of the oxide, halide, chalcogenide, silicate, phosphate, borate or aluminate type, most often of metal type. Most often, for the purpose of obtaining fluorescence, these materials constitute matrices doped with an element selected from the group of rare earth elements, for example in the group Eu, Ce, Er, Pr, Tb, Tm, Dy) or in the group of transition metals, for example in the group Mn, Cr, Ti, Ag, Cu, Zn. Such products are already well known in the field of fluorescent lamps. The phosphors of the laser dye type can also be used according to the invention as well as organic polymers. According to the invention, it is also possible to select the phosphors in the group of nanoscale semiconductors of type II-VI or III-V, commonly called quantum dots (quantum dots) in the art. The organometallic molecules can also be used as phosphors according to the invention. These molecules consist for example of a fluorescence center consisting of at least one metal atom or a rare earth atom, surrounded by and linked to organic groups.

  Examples of phosphors that may be used according to the invention are described, for example, in US Pat. No. 7,090,355, in particular in Column 5, line 29 to Column 6, line 65 or still in US Patent Application 2004/232826, paragraphs [0025]. at [0033].

  The source used is for example a conventional UV source such as for example but not limited to the LED type, Xenon lamp, Mercury lamp, halide arc lamp or a laser UV source, for example but not limited to the solid-state laser type , semiconductor laser diode, gas lasers, dye lasers, excimer lasers. In general, any known source of UV excitation can be used according to the invention.

  It is possible to use a mixture of phosphors in the layer 6, for example a red emitting phosphor, a blue emitting phosphor and a green emitting phosphor, each of these luminophores having a wavelength of specific absorption so as to be selectively excited by appropriate choice of the incident radiation. Within the layer 6, the different phosphors can be randomly distributed, arranged in successive bands or separated in different regions, for example according to the embodiments described in application US 2005/0231652 and illustrated in FIGS. 8 of it.

  According to one possible embodiment, it is possible to use a DLP projector for modulating the excitation wave according to the mode described in application US 2005/231652, paragraph [0021]. It is also possible according to the invention to use as a UV excitation source a device as described in the application US2004 / 0232826 in particular as described in connection with FIG.

  The deposition of the layer on the thermoplastic PVB sheet (or other) is carried out under conditions chosen so that its thickness is preferably less than 30 m. The deposition can be achieved by screen printing techniques, especially if layers of thickness between 10 and 25 m are sought, by inkjet type techniques especially if layers of thickness between 5 and 10 m are or by techniques of the offset, flexo-engraving or gravure printing type if thicknesses between 1 and 5 m are desired. For example, the deposition by one of the preceding techniques is carried out by dissolving or dispersing the phosphor particles in at least one solvent which may be an aqueous or organic solvent, depending on the chemical nature of the phosphors and the technique employed.

  It has also been found by the applicant that if the particle size plays an important role in maintaining the transparency of the glazing, obtaining an image of the object on the glazing having a satisfactory optical quality even under strong external exposure of the glazing was not necessarily compatible with the choice of a phosphor based solely on size criteria. More particularly, it has been found by the applicant that in the context of an application for viewing an image through a transparent glazing, meeting all of the following criteria: a) a sharpness of the acceptable image (b) a sufficient luminescence intensity to be observable by the driver, (c) a blur caused by the application of the layer on the windscreen, measured according to the Anspi Z26.1 1996 standard, less than 2 % and preferably less than 1%, d) a light transmission greater than 70% and preferably greater than 75%, it was imperative to have the nanoscale phosphor in the form of a thin layer less than 50 thickness m in particular by one of the techniques described above, this layer to be further deposited on the inner face of the thermoplastic sheet, for example PVB sheet, facing the passenger compartment or the interior of the building.

  It has also been determined by the applicant that the best compromise between the four preceding properties is not only a function of the size of the phosphor particles used, but of their scattering cross section. By controlling this section, the applicant has been able to demonstrate a significant improvement in the image obtained, both in terms of its sharpness and its intensity, without the blur caused by the layer being greater than 2%, nor that the light transmittance of the glazing at the location of the layer is less than 70%. It has also been determined by the applicant that the methods of selective deposition at the surface and limited to the viewing zone are the only ones likely to lead to the production of the products under economically acceptable conditions for the automotive sector given the high cost of the nanoparticles in question. question.

Claims (15)

  1. Laminated glazing of automotive windscreen or HUD component glazing type, comprising an assembly of at least two transparent sheets of inorganic glass or of a resistant organic material of the PC type, interconnected by an interlayer of a thermoformable material or multilayer leaflets incorporating such an interlayer, said glazing being characterized in that it further comprises, on at least a portion of its structure, a thin layer less than 50 microns thick comprising at least one phosphor material in the form of particles whose size is adjusted so that the light transmission of said glazing remains greater than 70%, said phosphor material re-emitting radiation in the visible range when subjected to an excitatory light incident wave in the field ultraviolet, and in that, in the assembly, said layer is positioned between the thermoformable interlayer and the passenger compartment of the vehicle or the interior of the building.   2. laminated glass according to claim 1, wherein wherein said thin layer is placed on the side of the insert or thermoplastic sheet facing the passenger compartment of the vehicle or the interior of the building.   3. laminated glazing according to claim 1, wherein said thin layer is disposed on the outer or inner face of the transparent sheet positioned in the assembly on the side of the passenger compartment of the vehicle or the building interior. 25   4. laminated glass according to one of the preceding claims, wherein the thermoformable material constituting said interlayer is selected from the group of PVB, plasticized PVC, polyurethane PU or ethylene vinyl acetate EVA.   5. Laminated glazing according to one of the preceding claims, wherein the thermoformable material is PVB.   6. laminated glass according to one of the preceding claims, wherein the transparent sheets are interconnected by a multilayer sheet incorporating a FL2intercalaire PVB, for example a sheet comprising a succession of layers PVB / PET / PVB, wherein PET is the polyethylene terephthalate.   7. Laminated glazing according to one of the preceding claims, wherein the phosphor particles are nanoscale.   8. Laminated glazing according to one of the preceding claims, wherein the phosphor particles are selected according to their scattering cross section.   9. laminated glazing according to one of the preceding claims, wherein the thin film comprises at least one phosphor material emitting in the red, a phosphor material emitting in blue and a phosphor material emitting in the green, under a UV excitation.   10. Laminated glazing according to one of the preceding claims, wherein the thin film comprises different phosphors distributed randomly within said layer, arranged in successive bands in said layer or separated in different regions of said layer in the form of pixels. color.   11. Laminated glazing according to one of the preceding claims, wherein the thin layer is deposited on the thermoplastic sheet or on the transparent sheet by a technique chosen from screen printing techniques, inkjet type techniques or techniques. offset type, flexo-engraving or gravure printing.   12. An image display device on a transparent glazing unit comprising a laminated glazing unit according to one of the preceding claims and a source generating UV radiation, the ultraviolet beam being directed towards the area or zones of the glazing unit comprising the phosphors.   13. A display device according to claim 12, wherein the source generating conventional UV radiation is selected from sources of the LED type, Xenon lamp, Mercury lamp, halide arc lamp. 5   14. Display device according to claim 12, in which the source generating UV radiation is chosen from UV laser sources, for example of the solid-state laser type, semiconductor laser diode, gas lasers, dye lasers, laser lasers. to excimer.   15. A display device according to claim 12 to 14 further comprising means for modulating the excitation wave, said means for modulating the UV radiation for a selective excitation of the phosphors present in said layer.