Classifications

• • G—PHYSICS
  • G02—OPTICS
  • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
  • G02B27/00—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00
  • G02B27/09—Beam shaping, e.g. changing the cross-sectional area, not otherwise provided for
  • G02B27/0938—Using specific optical elements
• • G—PHYSICS
  • G02—OPTICS
  • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
  • G02B5/00—Optical elements other than lenses
  • G02B5/02—Diffusing elements; Afocal elements
• • G—PHYSICS
  • G02—OPTICS
  • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
  • G02B5/00—Optical elements other than lenses
  • G02B5/02—Diffusing elements; Afocal elements
  • G02B5/0205—Diffusing elements; Afocal elements characterised by the diffusing properties
  • G02B5/021—Diffusing elements; Afocal elements characterised by the diffusing properties the diffusion taking place at the element's surface, e.g. by means of surface roughening or microprismatic structures
  • G02B5/0226—Diffusing elements; Afocal elements characterised by the diffusing properties the diffusion taking place at the element's surface, e.g. by means of surface roughening or microprismatic structures having particles on the surface
• • G—PHYSICS
  • G02—OPTICS
  • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
  • G02B5/00—Optical elements other than lenses
  • G02B5/02—Diffusing elements; Afocal elements
  • G02B5/0273—Diffusing elements; Afocal elements characterized by the use
  • G02B5/0278—Diffusing elements; Afocal elements characterized by the use used in transmission
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
  • C09K2323/00—Functional layers of liquid crystal optical display excluding electroactive liquid crystal layer characterised by chemical composition
• • G—PHYSICS
  • G02—OPTICS
  • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
  • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
  • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
  • G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells
  • G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
  • G02F1/1333—Constructional arrangements; Manufacturing methods
  • G02F1/1335—Structural association of cells with optical devices, e.g. polarisers or reflectors
  • G02F1/1336—Illuminating devices
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T428/00—Stock material or miscellaneous articles
  • Y10T428/25—Web or sheet containing structurally defined element or component and including a second component containing structurally defined particles
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T428/00—Stock material or miscellaneous articles
  • Y10T428/31504—Composite [nonstructural laminate]
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T428/00—Stock material or miscellaneous articles
  • Y10T428/31504—Composite [nonstructural laminate]
  • Y10T428/31678—Of metal

Definitions

• the invention relates to improvements made to a diffusing structure, to homogenize and filter a light source.
• a diffusing structure used to homogenize the light emitted from a backlighting system.
• Such a system can in particular be a light source or “back-light” used in particular as a backlight source for liquid crystal screens.
• the invention can also be used when it comes to homogenizing the light coming from architectural flat lamps used for example on ceilings, floors, or walls. They may also be flat lamps for urban use such as lamps for advertising panels or lamps that can constitute shelves or bottoms of display cases.
• the light sources used in these backlighting systems are mainly lamps or discharge tubes commonly called CCFL for “Cold Cathode Fluorescent Lamp”, HCFL “Hot Cathode Fluorescent Lamp”, or DBDFL for
• LCD screens of the prior art incorporate: - a thick plastic diffuser (approximately 2 mm), generally made of PMMA or polycarbonate, - various optical plastic films fulfilling functions of homogenization or shaping of light or of diffusion , - and a reflective polarizer. It can be seen that the diffuser quickly takes on a yellowish color so that the desired transparency criteria are no longer met.
• the present invention therefore aims to overcome these drawbacks by proposing a diffusing structure combining long service life and good optical performance.
• the invention provides a diffusing structure comprising a diffusing layer intended to homogenize a light source and comprising at least one thermoplastic sheet suitable for filtering part of the spectrum of electromagnetic waves of said light source.
• thermoplastic sheet according to the invention effectively protects from harmful radiation all sensitive elements including optical elements: plastic film (s) diffusing, reflective polarizer .... In addition, this sheet does not yellow.
• the diffusing structure according to the invention is therefore a particularly attractive filtering diffusing structure.
• the thermoplastic sheet can receive electromagnetic radiation from the light source before or after its passage through a glass substrate (not very sensitive to UV type radiation) carrying the diffusing layer, for example essentially mineral (also not very sensitive to UV type radiation) and / or carrier of plastic film (s) to be protected acting as an additional diffusing layer or as a replacement for the essentially mineral diffusing layer.
• the thermoplastic sheet can also receive electromagnetic radiation from the light source directly or through a waveguide depending on the screen configurations.
• this thermoplastic sheet is preferably chosen so as not to significantly modify the optical characteristics of the structure in the visible.
• the thermoplastic sheet can be adapted to filter in the wave range between 0.28 ⁇ m to 0.40 ⁇ m.
• this structure comprises at least one essentially mineral element, preferably a glass substrate and / or said diffusing layer.
• the mineral element is not very sensitive to UV and therefore allows, in association with the thermoplastic filter sheet, even greater latitude in the order of the stacks (diffusing layer, polymeric optical film (s). .) forming the structure with respect to a solution
• a glass substrate provides high mechanical strength, in particular resistance to the heat emitted by the light source.
• the diagonal of which is greater than 10 "(the diagonal being in this case a characteristic dimension of the screen) the light sources are located inside an enclosure, at most close to the diffusing part (“Direct Light” type structure), which is generally not the case for small screens (diagonal less than 10 ") and for which the light sources are positioned on the side of the 'enclosure (“Edge Light” type structure), the light being conveyed towards the diffusing layer by a waveguide. Heat generation is therefore particularly sensitive.
• thermoplastic sheet may preferably be PVB based.
• the diffusing structure further comprises a reflective polarizer, of the birefringent multilayer type, of the dispersed birefringent phase type, of the cholesteric liquid crystal type or even of the wire-grid type, - the diffusing structure further comprises a plastic sheet coated with a layer transparent metal oxide, the diffusing structure comprises a plastic sheet making it possible to control the angle of view or to shape the light of the CH27 or BEF type, - the diffusing structure comprises the whole of the LCD matrix.
• the thermoplastic sheet is a laminating interlayer.
• a thin laminated filtering diffusing structure in particular by hot rolling, which comprises for example: a glass substrate, the thermoplastic sheet, preferably made of PVB, or one or more optical plastic films (diffusing. ...), optionally a reflective polarizer, or else: a mineral diffusing layer, a glass substrate, the thermoplastic sheet, preferably made of PVB, a reflective polarizer, or also: a mineral diffusing layer, a glass substrate, the thermoplastic sheet , preferably in PVB, one or more optical plastic films (diffusing, etc.), - a reflective polarizer.
• the diffusing structure incorporates a substrate, and the diffusing layer is deposited on one of the faces of said substrate, while the thermoplastic sheet is deposited on the opposite face of said substrate.
• the diffusing layer may comprise a diffusing plastic film, for example made of PET, and preferably thin, for example less than 400 ⁇ m and more preferably of the order of 100 ⁇ m.
• the diffusing layer can also comprise a diffusing layer composed of elements containing particles and a binder, the binder making it possible to agglomerate the particles together. In the latter mode: - the particles can be metallic or metallic oxides, the particle size can be between 50 nm and 1 ⁇ m, preferably the binder can be mineral for resistance to heat.
• the diffusing structure may have a thickness substantially between 0.5 and 3 mm.
• a mineral diffusing layer of approximately 10 ⁇ m is chosen, a glass substrate of approximately 2 mm, the thermoplastic sheet of approximately 500 ⁇ m and a diffusing plastic film or polarizer of approximately 100 ⁇ m.
• the diffusing structure can incorporate a coating having a functionality other than that of filtering part of the spectrum of electromagnetic waves emitted by said light source, in particular a coating with low-emissive function, with anti-static, anti-fog function, antifouling.
• the structure comprises a glass substrate on which the diffusing layer and said sheet are arranged, and a glass substrate having a light transmission TL greater than or equal to 90% and preferably greater than or equal to 91.5% (glass called extra clear).
• a glass substrate having a light transmission TL greater than or equal to 90% and preferably greater than or equal to 91.5% (glass called extra clear).
• the structure comprises a transparent polymer-based substrate on which the diffusing layer and said sheet, substrate for example of polycarbonate or PMMA. This substrate is thus protected by the thermoplastic sheet according to the invention.
• the thermoplastic sheet is a transparent substrate on which the diffusing layer is placed.
• the substrate is one of the glass sheets constituting the backlighting system and / or a flat lamp, - the substrate has a characteristic dimension suitable for “direct light” applications.
• diffusing layer means any layer which is functionally adapted to diffuse light, whatever its structure.
• the diffusing layer consists of particles agglomerated in a binder, said particles having an average diameter between 0.3 and 2 microns, said binder being in a proportion between 10 and 40% by volume and the particles forming aggregates whose size is between 0.5 and 5 microns, said layer having a contrast attenuation greater than 40% and preferably greater than 50%.
• This preferred diffusing layer is particularly described in application WO0190787.
• the particles are chosen from semi-transparent particles and preferably mineral particles such as oxides, nitrides, carbides.
• the particles will preferably be chosen from oxides of silica, alumina, zirconia, titanium, cerium, or a mixture of at least two of these oxides.
• Such particles can be obtained by any means known to those skilled in the art and in particular by precipitation or by pyrogenation.
• the particles have a particle size such that at least 50% of the particles deviate by less than 50% from the mean diameter.
• the binder has a temperature resistance sufficient to withstand the operating temperatures and / or the sealing temperature of the lamp if the layer is produced before the assembly of the lamp and in particular before the latter is sealed. When the layer is in the external position, the binder is also chosen with an abrasion resistance sufficient to undergo without damage all the manipulations of the backlight system, for example, in particular during the mounting of the flat screen.
• the binder may be chosen mineral, for example to promote resistance to the temperature of the layer, or organic, in particular to simplify the production of said layer, the crosslinking being able to be obtained simply, for example cold.
• the choice of a mineral binder whose temperature resistance is important will in particular allow the realization of very long life backlighting without any risk of seeing a degradation of the layer due for example to fluorescent tubes which cause a considerable heating.
• the binder has an index different from that of the particles and the difference between these two indices is preferably at least 0.1.
• the index of the particles is greater than 1.7 and that of the binder is preferably less than 1, 6.
• the binder is chosen from potassium silicates, sodium silicates, lithium silicates, aluminum phosphates, polymers of polyvinyl alcohol type, thermosetting resins, acrylics, etc.
• the invention provides for the addition of at least one additive leading to a random distribution of the particles in the binder.
• the additive or dispersing agent is chosen from the following agents, an acid, a base, or ionic polymers of low molecular weight, in particular less than 50,000 g / mol. It is also possible to add other agents and for example a wetting agent such as nonionic, anionic or cationic surfactants, to provide a homogeneous layer on a large scale.
• the layer thus defined can be deposited at a thickness of between 1 and 20 microns.
• the methods for depositing such a layer can be any means known to a person skilled in the art, such as screen-printing, coating of a paint, "dip-coating", “spin-coating”, “ flow-coating ”, by spraying, etc.
• a deposition process of the screen printing type is used.
• the deposition is preferably carried out by flow-coating or by spraying.
• the diffusing layer can be obtained from a glass substrate which has undergone a surface treatment.
• the diffusing layer can comprise a thin diffusing plastic film. They may, for example, be diffusing films marketed by the company 3M TM under the references 3635-30 or 3635-70. Whatever the embodiment of the diffusing layer, it is associated with at least one thermoplastic sheet suitable for filtering part of the spectrum of electromagnetic waves of said light source.
• thermoplastic sheet is suitable for making a selection from the spectrum of electromagnetic waves emitted by a light source.
• the range of waves included in the ultraviolet range is selected, namely from 0.28 to 0.40 ⁇ m.
• the thermoplastic sheet or film can be clear PVB, for example the product sold under the name Saflex, sold by the company "Solutia” or an equivalent film.
• This filtering device is preferably positioned as close as possible to the diffusing layer.
• This thermoplastic film is therefore associated with a diffusing layer, the assembly being associated with a substrate in particular made of glass or of polymer (PMMA, polycarbonate) to give a filtering diffusing structure.
• thermoplastic film covers one of the faces of the substrate, the thermoplastic film covering the other side, the diffusing layer covers one of the faces of the substrate, the thermoplastic film is associated with at least one other film providing another functionality to the system before the assembly covers, the other face of the substrate the thermoplastic film can be associated directly or indirectly with all or some of the following other films: - a reflective polarizer of the birefringent multilayer type (based on polyethylene naphthalate or PEN (for example a DBEF film sold by the company 3M), - a reflective polarizer of the dispersed birefringent phase type, - a reflective polarizer of the cholesteric liquid crystal type (for example those sold by the companies Merck, 3M, Nitto Denko or Wacker) - a reflective polarizer of the wire-grid type (for example those sold by the company Moxtek) - a coated plastic sheet a transparent metal oxide layer (for example a dTTO
• the filtering diffusing structure has a light transmission TL of at least 20%, and preferably greater than 50% and a light absorption AL less than
• the thickness of the diffusing structure thus formed is substantially between 0.5 and 3 mm.
• An alternative embodiment which can be associated with the embodiments of diffusing filtering structures described above, consists in incorporating a coating having another functionality. It may be a coating with a function of blocking wavelength radiation in the infrared (using for example one or more layers of silver surrounded by dielectric layers, or layers in nitrides such as TiN or ZrN or in metallic oxides or in steel or in Ni-Cr alloy), with a low-emissive function (for example in doped metal oxide like Sn ⁇ 2: F or indium oxide doped with tin ITO or a or several layers of silver), heating layer (doped metal oxide, Cu, Ag for example) or network of heating wires (copper wires or silk-screened strips from conductive silver paste), anti-fog (at l (using a hydrophilic layer), anti-fouling (photocatalytic coating comprising TiO2 at least partially crystallized in anatase form).
• the applications envisaged by the invention are in particular backlight systems, for example used for lighting liquid crystal screens, or even flat lamps used for architectural lighting or even urban lighting, or more generally in any system incorporating light sources capable of generating electromagnetic disturbances.
• a flat lamp is described in document WO2004 / 015739.
• the diffusing layer and the other films are deposited on a transparent or semi-transparent substrate independent of the sheets. of glass constituting the structure of the backlight system.
• Such an embodiment may consist in depositing the assembly of layers on a glass substrate kept at a distance from the front face of the backlight system; this realization allows according to the laws of physics to further improve the diffusing effect of the assembly of layers.
• the volume or size of such an embodiment increases but the optical performance is even more durable over time.
• the improved diffusing filtering structures thus presented according to the invention therefore make it possible to produce backlighting systems, for example intended for lighting liquid crystal screens.
• the diffusing filtering structure according to the invention can make it possible to reduce the size of a backlight system for given performance in terms of luminance, brightness and lifespan.
• the filtering diffusing structure is successively composed of a mineral diffusing layer, deposited on an extraclear glass substrate, laminated with the thermoplastic sheet on which is laminated a reflective polarizer or a diffusing film as described above.
• the diffusing filtering structure is successively composed of an extra-clear glass substrate, laminated with the thermoplastic sheet according to the invention, on which a diffusing plastic film is laminated as described above. You can choose an extra clear glass from the Satinovo range of Saint-

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• Optics & Photonics (AREA)
• Optical Elements Other Than Lenses (AREA)

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• 2003
  • 2003-07-02 FR FR0308022A patent/FR2857103B1/fr not_active Expired - Fee Related
• 2004
  • 2004-07-02 TW TW093120045A patent/TW200510870A/zh unknown
  • 2004-07-02 KR KR1020057025271A patent/KR20060132437A/ko not_active Application Discontinuation
  • 2004-07-02 EP EP04767558A patent/EP1654569A1/de not_active Withdrawn
  • 2004-07-02 CN CNA2004800251432A patent/CN1846153A/zh active Pending
  • 2004-07-02 US US10/563,000 patent/US20080107827A1/en not_active Abandoned
  • 2004-07-02 JP JP2006518280A patent/JP2007516455A/ja active Pending
  • 2004-07-02 WO PCT/FR2004/001717 patent/WO2005012957A1/fr active Application Filing

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