Classifications

• • 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
  • G02F1/133509—Filters, e.g. light shielding masks
• • 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
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B17/00—Layered products essentially comprising sheet glass, or glass, slag, or like fibres
  • B32B17/06—Layered products essentially comprising sheet glass, or glass, slag, or like fibres comprising glass as the main or only constituent of a layer, next to another layer of a specific material
  • B32B17/10—Layered products essentially comprising sheet glass, or glass, slag, or like fibres comprising glass as the main or only constituent of a layer, next to another layer of a specific material of synthetic resin
  • B32B17/10005—Layered products essentially comprising sheet glass, or glass, slag, or like fibres comprising glass as the main or only constituent of a layer, next to another layer of a specific material of synthetic resin laminated safety glass or glazing
  • B32B17/10009—Layered products essentially comprising sheet glass, or glass, slag, or like fibres comprising glass as the main or only constituent of a layer, next to another layer of a specific material of synthetic resin laminated safety glass or glazing characterized by the number, the constitution or treatment of glass sheets
  • B32B17/10036—Layered products essentially comprising sheet glass, or glass, slag, or like fibres comprising glass as the main or only constituent of a layer, next to another layer of a specific material of synthetic resin laminated safety glass or glazing characterized by the number, the constitution or treatment of glass sheets comprising two outer glass sheets
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B17/00—Layered products essentially comprising sheet glass, or glass, slag, or like fibres
  • B32B17/06—Layered products essentially comprising sheet glass, or glass, slag, or like fibres comprising glass as the main or only constituent of a layer, next to another layer of a specific material
  • B32B17/10—Layered products essentially comprising sheet glass, or glass, slag, or like fibres comprising glass as the main or only constituent of a layer, next to another layer of a specific material of synthetic resin
  • B32B17/10005—Layered products essentially comprising sheet glass, or glass, slag, or like fibres comprising glass as the main or only constituent of a layer, next to another layer of a specific material of synthetic resin laminated safety glass or glazing
  • B32B17/10009—Layered products essentially comprising sheet glass, or glass, slag, or like fibres comprising glass as the main or only constituent of a layer, next to another layer of a specific material of synthetic resin laminated safety glass or glazing characterized by the number, the constitution or treatment of glass sheets
  • B32B17/10036—Layered products essentially comprising sheet glass, or glass, slag, or like fibres comprising glass as the main or only constituent of a layer, next to another layer of a specific material of synthetic resin laminated safety glass or glazing characterized by the number, the constitution or treatment of glass sheets comprising two outer glass sheets
  • B32B17/10045—Layered products essentially comprising sheet glass, or glass, slag, or like fibres comprising glass as the main or only constituent of a layer, next to another layer of a specific material of synthetic resin laminated safety glass or glazing characterized by the number, the constitution or treatment of glass sheets comprising two outer glass sheets with at least one intermediate layer consisting of a glass sheet
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B17/00—Layered products essentially comprising sheet glass, or glass, slag, or like fibres
  • B32B17/06—Layered products essentially comprising sheet glass, or glass, slag, or like fibres comprising glass as the main or only constituent of a layer, next to another layer of a specific material
  • B32B17/10—Layered products essentially comprising sheet glass, or glass, slag, or like fibres comprising glass as the main or only constituent of a layer, next to another layer of a specific material of synthetic resin
  • B32B17/10005—Layered products essentially comprising sheet glass, or glass, slag, or like fibres comprising glass as the main or only constituent of a layer, next to another layer of a specific material of synthetic resin laminated safety glass or glazing
  • B32B17/10165—Functional features of the laminated safety glass or glazing
  • B32B17/10174—Coatings of a metallic or dielectric material on a constituent layer of glass or polymer
  • B32B17/10201—Dielectric coatings
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B17/00—Layered products essentially comprising sheet glass, or glass, slag, or like fibres
  • B32B17/06—Layered products essentially comprising sheet glass, or glass, slag, or like fibres comprising glass as the main or only constituent of a layer, next to another layer of a specific material
  • B32B17/10—Layered products essentially comprising sheet glass, or glass, slag, or like fibres comprising glass as the main or only constituent of a layer, next to another layer of a specific material of synthetic resin
  • B32B17/10005—Layered products essentially comprising sheet glass, or glass, slag, or like fibres comprising glass as the main or only constituent of a layer, next to another layer of a specific material of synthetic resin laminated safety glass or glazing
  • B32B17/10165—Functional features of the laminated safety glass or glazing
  • B32B17/10431—Specific parts for the modulation of light incorporated into the laminated safety glass or glazing
  • B32B17/10467—Variable transmission
  • B32B17/10495—Variable transmission optoelectronic, i.e. optical valve
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B17/00—Layered products essentially comprising sheet glass, or glass, slag, or like fibres
  • B32B17/06—Layered products essentially comprising sheet glass, or glass, slag, or like fibres comprising glass as the main or only constituent of a layer, next to another layer of a specific material
  • B32B17/10—Layered products essentially comprising sheet glass, or glass, slag, or like fibres comprising glass as the main or only constituent of a layer, next to another layer of a specific material of synthetic resin
  • B32B17/10005—Layered products essentially comprising sheet glass, or glass, slag, or like fibres comprising glass as the main or only constituent of a layer, next to another layer of a specific material of synthetic resin laminated safety glass or glazing
  • B32B17/10165—Functional features of the laminated safety glass or glazing
  • B32B17/10431—Specific parts for the modulation of light incorporated into the laminated safety glass or glazing
  • B32B17/10467—Variable transmission
  • B32B17/10495—Variable transmission optoelectronic, i.e. optical valve
  • B32B17/10504—Liquid crystal layer
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B17/00—Layered products essentially comprising sheet glass, or glass, slag, or like fibres
  • B32B17/06—Layered products essentially comprising sheet glass, or glass, slag, or like fibres comprising glass as the main or only constituent of a layer, next to another layer of a specific material
  • B32B17/10—Layered products essentially comprising sheet glass, or glass, slag, or like fibres comprising glass as the main or only constituent of a layer, next to another layer of a specific material of synthetic resin
  • B32B17/10005—Layered products essentially comprising sheet glass, or glass, slag, or like fibres comprising glass as the main or only constituent of a layer, next to another layer of a specific material of synthetic resin laminated safety glass or glazing
  • B32B17/1055—Layered products essentially comprising sheet glass, or glass, slag, or like fibres comprising glass as the main or only constituent of a layer, next to another layer of a specific material of synthetic resin laminated safety glass or glazing characterized by the resin layer, i.e. interlayer
  • B32B17/1077—Layered products essentially comprising sheet glass, or glass, slag, or like fibres comprising glass as the main or only constituent of a layer, next to another layer of a specific material of synthetic resin laminated safety glass or glazing characterized by the resin layer, i.e. interlayer containing polyurethane
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B17/00—Layered products essentially comprising sheet glass, or glass, slag, or like fibres
  • B32B17/06—Layered products essentially comprising sheet glass, or glass, slag, or like fibres comprising glass as the main or only constituent of a layer, next to another layer of a specific material
  • B32B17/10—Layered products essentially comprising sheet glass, or glass, slag, or like fibres comprising glass as the main or only constituent of a layer, next to another layer of a specific material of synthetic resin
  • B32B17/10005—Layered products essentially comprising sheet glass, or glass, slag, or like fibres comprising glass as the main or only constituent of a layer, next to another layer of a specific material of synthetic resin laminated safety glass or glazing
  • B32B17/1055—Layered products essentially comprising sheet glass, or glass, slag, or like fibres comprising glass as the main or only constituent of a layer, next to another layer of a specific material of synthetic resin laminated safety glass or glazing characterized by the resin layer, i.e. interlayer
  • B32B17/10788—Layered products essentially comprising sheet glass, or glass, slag, or like fibres comprising glass as the main or only constituent of a layer, next to another layer of a specific material of synthetic resin laminated safety glass or glazing characterized by the resin layer, i.e. interlayer containing ethylene vinylacetate
• • 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 
  • G02F1/0147—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 thermo-optic effects
• • 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
  • G02F1/1334—Constructional arrangements; Manufacturing methods based on polymer dispersed liquid crystals, e.g. microencapsulated liquid crystals
• • 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
  • G02F1/133502—Antiglare, refractive index matching layers
• • 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
  • G02F2201/00—Constructional arrangements not provided for in groups G02F1/00 - G02F7/00
  • G02F2201/08—Constructional arrangements not provided for in groups G02F1/00 - G02F7/00 light absorbing layer

Definitions

• the present invention relates to electrically controllable systems with variable optical properties, and more precisely to glazing type systems, the light diffusion of which can be modified under the effect of an appropriate electrical supply, such as liquid crystal systems and optical valves.
• the invention applies similarly to systems which exhibit significant light scattering, but only within a narrow range of angles of vision incidence, such as holographic systems. It also applies to thermotropic systems, as well as systems with suspended particles (known under the English abbreviation S.P.D for "suspended particles display”).
• Liquid crystal systems use a functional film based on a polymer (s) medium in which droplets of liquid crystals, in particular nematic with positive dielectric anisotropy, are dispersed.
• the liquid crystals when the film is tensioned, orient themselves along a privileged axis, which allows vision. When switched off, in the absence of alignment of the crystals, the film becomes diffusing and prevents vision. Examples are described in patents EP-88 126, EP-268 877, EP-238 164, EP-357 234, EP-409 5 442 and EP-964 288.
• This type of film is generally placed between two substrates, for example example two sheets of polymer provided with electrodes, a structure which can then be leafed between two glasses to form a glazing.
• Optical valve systems generally use a functional film in the form of an optionally crosslinked polymer matrix, in which microdroplets are dispersed containing particles capable of being placed in a preferred direction under the action of an electric or magnetic field.
• the film will have a variable light transmission, generally associated with a variable light diffusion (under tension, the particles intercept light much less than under tension ).
• An example is described in patent WO93 / 09460, with a film comprising a crosslinkable polyorganosiloxane matrix and absorbent particles of the polyiodide type.
• the electrochromic system When the electrochromic system is switched on, it darkens and gives the image projected on the screen better contrast, and for the spectator, better visual comfort in an environment in natural or artificial light; it makes it possible in particular to absorb the stray light diffusedly reflected on the screen coming from the lighting means placed on the side of the spectator.
• the invention therefore aims to improve the performance of a variable light scattering system such as one of those described above, in particular in view of an application as a projection screen, and this by means of means simple to manufacture, simple to implement and simple to maintain, and therefore less expensive.
• a subject of the invention is first of all an element with variable optical properties comprising: (a) - a system of variable electrically controlled light diffusion, of the type with optical valve or liquid crystal system, or a system with suspended particles or a non-electrocontrolled system (a ') such as a holographic or thermotropic system or, which is associated with
• the absorbent element (b) includes an element which has the desired optical property in the visible permanently, without requiring electrical or other control.
• thermotropic systems among the electrically controlled systems when they are associated with one or more heating elements (for example a conductive layer heating by Joule effect), in order to make them switch at will, and not according to , in particular, the climatic conditions to which they are exposed.
• heating elements for example a conductive layer heating by Joule effect
• the invention therefore chose to add functionality to a system (a) or
• the system (a) is a liquid crystal system as described above, comprising a film of droplets of liquid crystals dispersed in a medium and contained by two protective sheets each provided with an electrode.
• These sheets can be chosen based on rigid substrates, preferably essentially transparent (glass, sufficiently thick PC polycarbonate), semi-rigid or flexible (thin polymer, such as thin PC).
• rigid substrates preferably essentially transparent (glass, sufficiently thick PC polycarbonate), semi-rigid or flexible (thin polymer, such as thin PC).
• a glass and a polymer substrate for example.
• the preferred variant consists in that the two protective sheets are based on flexible polymer, in particular transparent of the PET (polyethylene terephthalate) type.
• the absorbent elements (b) can be chosen from different natures. One or more can be used, of the same nature or of different natures, they will therefore "add” light absorption to the system (a) or (a '), over its entire surface or the majority of its surface.
• the absorbent element may firstly consist of a rigid or semi-rigid substrate (glass, polymer) which is dyed in the mass, by suitable dyes.
• TL light transmission glasses of 10 to 60% are chosen, for a thickness of the order of 1 to 8 mm, in particular from 1.5 to 6 mm.
• the glass or the plastic substrate may have the most neutral transmission color possible, especially in the grays. In an application as a rear projection screen, these tones are the least distorting of the original colors of the projected images.
• the absorbent element may also consist of a flexible, mass-dyed polymer sheet, in particular of thermoplastic, that is to say the type of sheet which is used as an interlayer sheet in laminated glazing. It can be polyvinyl butyral PVB, polyurethane PU, etylene vinyllacetate EVA. These tinted sheets have, for example, a light transmission T of 25 to 60%, in particular from 30 to 45% for a thickness generally between 0.2 and 0.8 mm (generally around 0.38 mm). For the same reason as above, we will preferably choose a color in neutral transmission, in gray for example. It is also possible to use a polymer-based sheet with absorbent properties which has been calendered to a clear substrate, for example a clear glass.
• the absorbent element can also be in the form of a thin absorbent layer disposed on one of the faces of a rigid (glass, polymer), semi-rigid or flexible (polymer) substrate forming part of the whole of the element with variable optical properties.
• the term “thin layer” is understood to mean a layer of interferential thickness (less than 1 ⁇ m, in particular between 1 and 100 nm or 2 and 50 nm). It can also be a superposition of thin layers, at least one of which is absorbent in the visible.
• Niobium oxide and / or iron and / or chromium can, for example, be layers based on nickel oxide and / or iron and / or chromium, which can be deposited by a thermal decomposition technique (pyrolysis in the gas phase, in the form of powder or in liquid phase), by a vacuum technique (cathode sputtering assisted in particular by magnetic field) or by sol-gel.
• a thermal decomposition technique pyrolysis in the gas phase, in the form of powder or in liquid phase
• a vacuum technique cathode sputtering assisted in particular by magnetic field
• sol-gel sol-gel.
• it can be reactive in the presence of oxidizing elements type O 2 from metallic targets or sub-stoichiometric oxide targets, or non-reactive from targets of oxide.
• the absorbent layer can also be essentially metallic, for example based on one of the following metals: nickel Ni, chromium Cr, Ni-Cr alloy, steel, Inconel alloy, Au or Au alloy, Ag silver or Ag alloy, copper. It is then preferably deposited by non-reactive sputtering. It can also be based on metallic nitride (s), of the TiN or ZrN type, which can be deposited by CVD or by reactive sputtering in the presence of nitriding elements from metallic targets.
• the absorbent layer can also be based on electrochromic material, such as possibly hydrated tungsten oxide, possibly hydrated nickel oxide, possibly hydrated iridium or tantalum oxide.
• another type of absorbent element (b) consists in using a dye within the functional film. It can very particularly be dichroic dyes which are dissolved within the droplets of liquid crystals and / or in the medium in which they are dispersed.
• dichroic dyes are for example chosen from the family of diazoquinone derivatives or from that of anthraquinone derivatives.
• the percentage or weight of dye relative to the liquid crystals, when the latter is dissolved therein, is preferably between 0.1 and 5%, in particular between 0.5 and 2%. In the variant where the dye is in the medium, its percentage by weight per contribution to the medium can be between 20 and 30% for example.
• the absorbent element may be an absorbent electrically conductive layer forming part of one of the electrodes which supply the functional film with electricity. It can be a layer based on a conductive metal oxide (which can be deposited by pyrolysis or by cathode sputtering as in the case of the absorbent layer mentioned above).
• the oxide (or mixture of oxides) is preferably doped. The fact that it is absorbent comes, in a first variant, from the fact that it is in the reduced state and / or substoichiometric in oxygen (while remaining electrically conductive).
• It can be for example indium oxide (doped with tin) and reduced, tin oxide (doped for example with fluorine) and reduced, zinc oxide (doped for example Al) and reduced.
• he can also be conductive oxides which are intrinsically absorbent, without being in the reduced state: this is the case of tin oxide doped with antimony, which at 30 nm, can have a light absorption A from 10 to about 62% depending on the percentage of dopant (2.5 to 10% of dopant).
• the conductive layer forming part of the electrode is absorbent comes from the combination of its chemical nature and the choice of its thickness.
• a layer based on metal oxide (doped) it can become sufficiently absorbent for the invention if it is sufficiently thick.
• a metal-based layer of the Ni, Cr, NiCr type, or metallic nitride (TiN, ZrN %) whose thickness is adjusted appropriately (for example, a layer of surrounding TiN 25 nm has a light absorption of around 50%).
• the absorbent element can also be a film based on a plastic material, which is absorbent and which can, for example, be calendered to a clear substrate, in particular clear glass.
• the element with optical properties due to the presence of the absorbent element or elements (b) sees its light absorption AL increase by at least 5% and / or sees its light reflection R
• the element with optical properties as a whole has a light transmission T in particular between 10 and 50%, preferably between 20 and 40%: this range of TL is adequate to obtain the desired absorption effect while keeping a level sufficient light transmission, this last point being particularly important when the electrically controllable variable diffusion system is in the "ON" state, that is to say in the live and transparent state.
• the preferred embodiment according to the invention consists in that the element with variable optical properties also comprises: (c) - at least one anti-reflective element in the visible (called anti-reflection in the following text).
• the anti-reflection element (c) can be formed, according to a first variant, of an alternation of thin layers of interferential thickness with high and low refractive indices, according to a sequence (high index layer / low index layer) n , with n> 1.
• a high index / low index sequence most particularly the first from the substrate on which the anti-reflection is located, can be replaced by a layer of a material of intermediate index.
• Each "layer” can be a single layer or a superposition of several layers respectively at high or low index.
• the layers can be deposited by pyrolysis or by sputtering, like the absorbent layers mentioned above.
• the low index layers can be made of SiO 2 , AI 2 O 3 or a mixture.
• the high index layers can be SnO 2 , Si 3 N 4j TiO 2 , Nb 2 Os, AIN, ZnO.
• the intermediate index layers can be a mixture of high and low index oxides or SiON. Examples of suitable antireflections are described in patents EP-728,712, EP-911,302, WO97 / 43224, WO00 / 72053, FR99 / 14423. An example is marketed under the name of Vision Lite by the company Saint-Gobain Glass II. It may in particular be a stack of the Si 3 N 4 or Sn ⁇ 2 / Si0 2 / Si 3 N4 or Nb 2 ⁇ 5 / S ⁇ O type.
• the anti-reflection coating may comprise an absorbent layer, for example made of nitride of the TiN or ZrN type: there are thus two functions at the same time, with a single stack of layers which can be deposited one after the other by the same deposition method: anti-reflection and absorption effect.
• the anti-reflection element is an anti-reflection film, which can be applied by calendering to the surface of a substrate of the glass or plastic type. It may, for example, be a film of polyethylene terephthalate PET provided with an anti-reflection coating or a film of cellulose triacetate.
• the anti-reflective coating is effective when it is deposited on the exterior face of at least one of the "exterior” substrates of the element with variable optical properties (the term “exterior substrate” means that which delimits the element, of which one side is accessible and facing outside).
• an anti-reflection element is very positive in the context of an application to a rear projection screen for transmission. Indeed, it will decrease the light reflection, preferably from the outside face of the element as a whole which is intended to be turned towards the viewer. It will therefore make it possible to reduce the light reflection coming from the stray lighting on the spectator side. Its effect is also beneficial, but much less marked, if it is placed on the external face which will be on the side of the projector.
• the same type of anti-reflection effect is obtained by superficially modifying the external surface of at least one of these external substrates: this modification can consist of a surface texturing, a surface etching leaving calibrated growths , as described in patent FR 00/08842 filed on July 6, 2000: at increasing depth, there is less and less material and more and more air, which creates on the surface of the material ( glass in particular) an intermediate index layer between the material in question and the air, resulting in an anti-reflection effect.
• a glazing structure can be used in the narrow sense of the term, that is to say using at least one glass substrate. It can have, in particular, one, two or three glass substrates. It is also possible to replace all or part of these glasses with other rigid substrates of the polycarbonate type. We can even consider the case where the element as a whole does not contain rigid substrates, and only includes, for example, the functional film, of the liquid crystal type, sandwiched between two sheets of flexible polymer provided with electrodes (of the type PET / ITO or PET / SnO 2 doped), without counting of course the connection elements and any peripheral seals.
• thermoplastic polymer / variable light diffusion system / sheet (s) of thermoplastic polymer / glass 2 / optional anti-reflection coating or
• a single glass configuration can be of the type: (D - Optional anti-reflective coating / glass 1 / sheet (s) of thermoplastic polymer / variable light diffusion system / sheet (s) of optional protective polymer.
• the glass 1 and / or 2 and / or 3 which can be tinted in the mass and / or be provided with an absorbent layer, or one of the sheets of thermoplastic polymer be tinted in the mass .
• a favorable configuration consists in that it is the glass closest to the spectator which is this absorbent glass (by coloring in the mass or by adding a layer).
• a preferred variant of this configuration is that it is this absorbent glass which is provided with an anti-reflective coating.
• the subject of the invention is the element as a whole described above
• this element forming part of a rear projection screen operating in transmission.
• Figure 1 a laminated glazing according to the invention with two glasses
• Figure 2 a laminated glazing according to the invention with three glasses.
• liquid crystal system 1 is of configuration: PET sheet / electrode / functional film / electrode / PET sheet, the assembly being currently used in SAINT-GOBAIN GLASS Priva-Lite glazing.
• the functional film comprising the liquid emulsion of nematic liquid crystals is approximately 10 to 30 ⁇ m thick (preferably 20 to 25 micrometers).
• the PET sheets are approximately 175 ⁇ m thick.
• the two electrodes are made of ITO (indium oxide doped with tin) with a resistivity of around 100 ohms per square.
• liquid crystals can be of the "NCAP” type, in particular those used in "Priva-Lite” or “PDLC” glazing which have been mentioned above.
• their birefringence is between 0.1 and 0.2, it is variable in particular according to the medium used, of the order of 0.1 if the polymer of the medium is of polyurethane (PU) type and l '' order of 0.2 if it is of polyvinyl alcohol (PVA) type.
• PU polyurethane
• PVA polyvinyl alcohol
• the medium is in fact preferably based on a polymer from the family of PUs (latex) and / or PVA, generally prepared in the aqueous phase in a proportion of polymers of 15 to 50% by weight relative to water. .
• the active elements vis-à-vis the light scattering are advantageously in the form of droplets of average diameter between
• Size droplets depends on a certain number of parameters, including in particular the ease of emulsion of the active elements in the medium considered.
• these droplets represent between 120 and 220% by weight of the medium, in particular between 150 and 200% by weight, apart from the solvent, generally aqueous of said medium.
• liquid crystals are chosen in the form of droplets with a diameter of approximately 2.5 ⁇ m when the medium is based on polyurethane latex (birefringence of approximately 0.1) and with a diameter d '' approximately 1 ⁇ m when the medium is rather based on polyvinyl alcohol (birefringence of approximately 0.2).
• the power supply uses voltages between 0 and 110 V.
• the clear glasses being standard soda-lime-silica glasses marketed by SAINT-GOBAIN GLASS under the name "Planilux” and 2 mm thick.
• the EVA (ethylene vinyl acetate) sheet is 380 micrometers thick.
• This VENUS glass has the following characteristics: T between 25 and 30%. In the case of the glass used here, the TL is 26.6% (according to Illuminant D65), its color is gray.
• This glazing is illustrated in Figure 1, with the liquid crystal system
• Example 3 presents a configuration with three glasses according to FIG. 2: compared to the configuration of FIG. 1, it adds a clear glass 8 4 mm thick laminated to glass 2 and provided on the outside with an anti-reflection coating 7.
• This anti-reflection coating is composed of the following stack of layers: SnO 2 / SiO 2 / Nb 2 O 5 / SiO 2 : Al
• FIG. 2 thus illustrates another embodiment, where the laminated glazing has three glasses: there is added to the configuration according to FIG. 1, on the side of the tinted glass in the mass 2, a thermoplastic interlayer sheet of polyurethane 6 of 0.76 mm thick, allowing to leaf through the third glass 8, which is a clear glass identical to clear glass 3. In the case where an antireflection coating 7 is used, it is therefore on the outer face of this third glass 8 that it is arranged.
• Example 4 repeats the configuration of Example 3, and adds a second anti-reflective coating 7 ′ (cf. FIG. 2) on the outside face of the clear glass 3.
• the coating 7 ′ is identical to the coating 7 of Example 3
• glasses 3 and 8 have a thickness of 4 mm.
• Example 5 repeats the configuration of Example 2 with two glasses according to FIG. 2, but replaces VENUS 2 glass colored in the mass with another glass tinted in the mass 2 of 5 mm thick and marketed by SAINT-GOBAIN GLASS under the name "Parsol Gris". Its characteristics are: T L of 48.5%, gray color.
• Example 6 is a configuration with three glasses according to Figure 2, taking glass 2 from the tinted glass from Example 5, and adding a clear glass 8 of 4 mm provided with an anti-reflective coating 7 as in Example 3 EXAMPLE 7
• Example 7 uses the configuration of Example 6 and adds an anti-reflective coating T (identical to that of Example 4) to the outside of the clear glass 3.
• the clear glasses 3 and 8 each have a thickness of 4 mm.
• This example is a laminated glazing of the same configuration as in Example 2, to which is added by calendering on the outside of the tinted glass 2 an anti-reflection film 7 (plastic film) sold by Murei Danki under the reference "ReaLook 2201" EXAMPLE 9
• This example is a laminated glazing of the same configuration as in Example 5, to which is added by calendering on the outer face of the tinted glass 2 an anti-reflection film 7 identical to that used in Example 8.
• Table 1 summarizes for these nine examples: - The type of glass and / or the number of anti-reflective coatings used,

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• Physics & Mathematics (AREA)
• Nonlinear Science (AREA)
• Chemical & Material Sciences (AREA)
• Crystallography & Structural Chemistry (AREA)
• Mathematical Physics (AREA)
• General Physics & Mathematics (AREA)
• Optics & Photonics (AREA)
• Liquid Crystal (AREA)
• Overhead Projectors And Projection Screens (AREA)
• Electrochromic Elements, Electrophoresis, Or Variable Reflection Or Absorption Elements (AREA)
• Laminated Bodies (AREA)
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• 2001
  • 2001-07-12 FR FR0109316A patent/FR2827397B1/fr not_active Expired - Fee Related
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