Classifications

• • 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
  • G02B5/0221—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 the surface having an irregular structure
• • 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
  • G02B5/0236—Diffusing elements; Afocal elements characterised by the diffusing properties the diffusion taking place within the volume of the element
  • G02B5/0242—Diffusing elements; Afocal elements characterised by the diffusing properties the diffusion taking place within the volume of the element by means of dispersed particles
• • 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
• • 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
  • G02F1/133308—Support structures for LCD panels, e.g. frames or bezels
  • G02F1/133334—Electromagnetic shields
• • 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
  • G02F1/133602—Direct backlight
  • G02F1/133606—Direct backlight including a specially adapted diffusing, scattering or light controlling members

Definitions

• the invention relates to improvements made to a diffusing layer, intended to be deposited on a substrate to homogenize a light source.
• Such a system can in particular be a light source or
• Back-light used in particular as a backlight source for liquid crystal displays.
• 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 backlight systems are mainly discharge lamps or tubes commonly called CCFL for “Cold Cathode Fluorescent Lamp”, HCFL “Hot Cathode Fluorescent Lamp”, or DBDFL for “Dielectric Barrier Discharge Fluorescent Lamp ". All of these systems have in common that they are supplied by a variable voltage source, the frequency of which is generally in the range 10 to 100 kHz.
• a screen of this type incorporates between the backlight system (which constitutes the electromagnetic interference generator) and the LCD screen (Liquid Cristal Display) a diffusing layer, which as its name indicates, ensures the homogeneous diffusion of the light source coming from the back-lighting systems.
• thermoplastic material PET
• ITO Indium Tin Oxide
• the nature of the material constituting the diffuser we have seen that it is generally made of plastic. However, these materials are sensitive to heat and for large screens, 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.
• Direct Light type structure
• Edge Light type structure
• the diffusing part which takes the form of a heterogeneity in the brightness of the image projected on the screen.
• thermoplastic sheet provided with its electromagnetic isolation device, which leads on the one hand to multiple reflections and on the other hand, at an additional cost during assembly.
• the inventors have therefore given themselves the task of finding a means leading to electromagnetic isolation of a large screen (diagonal greater than 10 ”) and which does not have the drawbacks of the solutions described above, in particular in terms of space and loss of image quality.
• the diffusing layer intended to homogenize a light source according to the invention is characterized in that it combines an electromagnetic isolation device whose resistance per square is greater than 100 ⁇ .
• the resistance per square is between 300 and 700 ⁇
• the isolation device consists of at least one translucent layer in the visible region of electrically conductive material, said conductive layer being deposited as close as possible to the diffusing layer, - the conductive layer is based on translucent conductive oxide,
• the diffusing layer is deposited on a substrate, and the conductive layer is deposited on said diffusing layer
• the diffusing layer is associated with uri * substrate, the conductive layer being arranged between the substrate and the diffusing layer,
• the diffusing layer is associated with a substrate, the diffusing layer being deposited on one of the faces of a substrate, while the conductive layer is deposited on the opposite face of said substrate,
• the isolation device is incorporated into the diffusing layer
• the diffusing layer consists of elements comprising particles and a binder, the binder making it possible to agglomerate the particles together, the shielding device consisting of one and the other of said elements,
• the particles are metallic or metallic oxides it contains Zr Z2 particles
• the particle size is between 50 nm and 1 ⁇ m
• the particles are based on SnO2: F or ITO - the binder is an electrically conductive binder, organic mineral
• the substrate is a glass substrate
• the substrate is a transparent polymer-based substrate, for example made of polycarbonate
• the diffusing layer incorporates a coating having a functionality other than that of insulation, in particular a coating with low-emissivity function, with anti-static function , anti-fog, anti-fouling.
• it relates to the use of a diffusing layer as previously described to produce a diffusing substrate in a backlighting system and / or a flat lamp.
• the substrate is one of the glass sheets constituting the backlighting system and / or of a flat lamp
• the substrate has a characteristic dimension suitable for “direct light” applications
• the thickness and / or the covering density of the layer varies over the deposition surface
• the thickness of the diffusing layer is between 0.5 and 5 ⁇ m.
• the diffusing layer consists of particles agglomerated in a binder, said particles having an average diameter of between 0.3 and 2 microns, said binder being in a proportion of 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 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.
• the binder When the layer is in the external position, the binder is also chosen with sufficient abrasion resistance to withstand without damage all the manipulations of the backlight system, for example, in particular when mounting 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 high will in particular allow the realization of long-life backlighting without any risk of seeing a degradation of the layer appearing for example due to fluorescent tubes which cause heating. considerable. Indeed, it has appeared with known solutions a degradation of the plastic film in temperature which therefore makes it very difficult to produce large backlight systems.
• 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 mass, in particular less than 50,000 g / mol.
• 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 according to a thickness 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, ...
• the desired thickness of the deposited layer is greater than
• the deposition is preferably carried out by flow-coating or by spraying.
• a layer whose thickness varies according to the coverage area on the surface can make it possible to correct intrinsic inhomogeneities of a light source. For example, it is possible in this way to correct the variation in the illumination of the light sources along their length.
• a layer whose covering density varies on the deposition surface it is, for example, a deposit made by screen printing, the density of points of which can vary from an area completely covered to an area of scattered points, the transition being gradual or not.
• the diffusing layer provision is made for at least one of the elements, or even at least two of the elements constituting the diffusing layer, to be electrically conductive. It can be either particles forming the aggregates, or particles forming the binder. In the case of an electrically conductive binder of mineral type
• Sn ⁇ 2 or organic it is planned, for example, to use a conductive polymer (polypyrole), or nanoparticles (Sn ⁇ 2: F, SnO2: Sb, ITO).
• a conductive polymer polypyrole
• nanoparticles Sn ⁇ 2: F, SnO2: Sb, ITO.
• the particles forming the aggregates are electrically conductive, these can be based on transparent conductive oxide powder such as for example Sn ⁇ 2: F, SnO2: Sb, In 2 O 3 : Sn, ZnO: A1.
• the diffusing layer can be obtained from a substrate which has undergone a surface treatment. It can be for example a sanded substrate, a substrate having suffered an acid attack marketed by Saint Gobain Glass
• This electromagnetic isolation device is formed from at least one electrically conductive layer which is positioned as close as possible to the diffusing layer, this conductive layer being transparent in the visible range (including with reduced or zero blurring, and in this case translucent).
• such conductive layers are deposited on transparent or semi-transparent substrates, having a planar shape or not depending on the applications.
• the conductive layer consists of transparent conductive oxides (more commonly called TCO) such as in particular SnO 2 : F, SnO 2 : Sb, ⁇ n 2 O 3 : Sn, ZnO: A1.
• TCO transparent conductive oxides
• this conductive layer can be produced using a reactive sputtering process, either from metal targets, or from oxide targets.
• the conductive layer can be produced using a pyrolytic technique. It can be pyrolysis of powder. This technique consists in projecting, by a jet of carrier gas, onto the surface of the substrate, a powder of organometallic precursors or a mixture of powders, and under the effect of the heat of the substrate the powder decomposes releasing the atoms which participate in the conductive layer. It can also be the pyrolysis of liquid. According to this process, the chemical precursors, in the form of a liquid solution or suspension, are brought into contact with the substrate for example by a spraying technique (“spray coating”) or by a “dip coating” or “spin coating” technique. . The conductive layer can also be deposited on the substrate by chemical vapor deposition (CVD “Chemical Vapor Deposition”), or by plasma-assisted CVD.
• CVD chemical vapor deposition
• the "conductive layer" can be obtained by a sol-gel technique.
• the conductive layer has a resistance per square which is greater than 100 ⁇ and preferably between 300 and 700 ⁇ .
• This conductive layer constitutes an isolation device for frequencies between 10 and 100 kHz; this conductive layer also makes it possible to produce a device for the flow of electrostatic or surface charges. (These resistance properties per square are also obtained by the intrinsically conductive diffusing layer previously described).
• This conductive layer is therefore associated with a diffusing layer, the assembly being associated with a substrate, in particular made of glass or of polymer (PMMA, polycarbonate).
• the substrate is located between the diffusing layer and the conductive layer
• the conductive layer covers one of the faces of the substrate, the diffusing layer covering the conductive layer, the diffusing layer covers one of the faces of the substrate, the conductive layer covering the diffusing layer, - the layer diffuser comprising at least one electrically conductive element (binder and / or aggregate) is in contact with one of the faces of the substrate.
• the diffusing layer alone (intrinsically conductive), the diffusing layer associated with the conducting layer, the assembly has a light transmission TL of at least 20%, and preferably greater than 50% and a light absorption AL less than 15%.
• the thickness of the diffusing layer thus formed is between 0.5 to 5 ⁇ m, including 10 nm to 1 ⁇ m for the single conductive layer.
• the value of light transmission for the conductive layer alone is at least 80% and preferably greater than 85%.
• An alternative embodiment which can be associated with the embodiments of diffusing layers having a "shielding device described above, consists in incorporating into the assembly a coating having another functionality. It may be a coating with a function of blocking of wavelength radiation in the infrared (using for example one or more silver layers surrounded by dielectric layers, or layers of nitrides such as TiN or ZrN or of metal oxides or of steel or alloy Ni-Cr), with a low-emissive function (for example in doped metal oxide such as SnO2: F or indium oxide doped with tin ITO or one or more layers of silver), heating layer
• 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.
• the assembly of layers (diffusing + electrically conductive) is deposited on the glass sheet constituting the front face of the lamp.
• the assembly of layers is deposited on the face of the glass sheet oriented towards the interior of the lamp ; according to such an embodiment, the assembly of layers (diffusing + electrically conductive) must be deposited on the glass sheet during the production of the lamp. According to this embodiment, the assembly of layers must have sufficient temperature resistance to withstand the various heat treatments necessary for the production of such a lamp, in particular for carrying out the deposits corresponding to the production of the electrodes and for carrying out the peripheral sealing of the two glass sheets constituting the structure of the flat lamp.
• the invention provides for deposition of the assembly of layers (diffusing + electrically conductive) while maintaining free zones corresponding to the locations provided for the spacers of so that the adhesion of these is not disturbed by the layer according to the invention.
• Such free spaces can easily be obtained by choosing a deposition of the layer according to a screen printing technique.
• the layer (diffusing + electrically conductive) is deposited on the face of the glass sheet oriented towards the outside of the lamp; according to this embodiment the assembly of layers (diffusing + electrically conductive) is chosen with reinforced properties of mechanical resistance and more particularly of abrasion resistance.
• said layer (diffusing + electrically conductive) is deposited on a transparent or semi-transparent substrate independent of the glass sheets constituting the structure of the flat lamp or of the backlighting system.
• Such an embodiment may consist in depositing the assembly of layers (diffusing + electrically conductive) on a glass substrate kept at a distance from the front face of the lamp or of the backlighting 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 becomes equivalent to the solutions known previously but then with diffusion performance and electromagnetic isolation much more durable over time.
• the improved layers (diffusing and insulated) thus presented according to the invention therefore make it possible to produce backlighting systems, for example intended for lighting liquid crystal screens.
• the layer according to the invention makes it possible to reduce the size of said backlight system for given performances in terms of luminance, brightness and lifespan.

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• Physics & Mathematics (AREA)
• General Physics & Mathematics (AREA)
• Optics & Photonics (AREA)
• Chemical & Material Sciences (AREA)
• Dispersion Chemistry (AREA)
• Optical Elements Other Than Lenses (AREA)
• Surface Treatment Of Optical Elements (AREA)
• Luminescent Compositions (AREA)
• Electroluminescent Light Sources (AREA)

Applications Claiming Priority (3)

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• 2002
  • 2002-07-03 FR FR0208289A patent/FR2841992B1/fr not_active Expired - Fee Related
• 2003
  • 2003-07-02 US US10/518,531 patent/US20060050395A1/en not_active Abandoned
  • 2003-07-02 JP JP2004518862A patent/JP2006504119A/ja active Pending
  • 2003-07-02 AU AU2003264685A patent/AU2003264685A1/en not_active Abandoned
  • 2003-07-02 PL PL03372722A patent/PL372722A1/xx not_active Application Discontinuation
  • 2003-07-02 EP EP03762725A patent/EP1540384A1/fr not_active Withdrawn
  • 2003-07-02 CN CNA038208776A patent/CN1678928A/zh active Pending
  • 2003-07-02 WO PCT/FR2003/002053 patent/WO2004005978A1/fr not_active Ceased

Non-Patent Citations (1)

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