WO2013132191A1

WO2013132191A1 - Light valve and method for manufacturing same

Info

Publication number: WO2013132191A1
Application number: PCT/FR2013/050482
Authority: WO
Inventors: Jingwei Zhang; Patrick Gayout
Original assignee: Saint-Gobain Glass France
Priority date: 2012-03-08
Filing date: 2013-03-07
Publication date: 2013-09-12
Also published as: FR2987907A1; FR2987907B1; TW201351011A

Abstract

The present invention relates to a light valve (100) comprising first and second sheets of planar float glass (1, 2) sealed by a joint (7), first and second electrodes (3, 4), an SPD system (5) having a thickness E that is no higher than 100 µm, and including spacers (6). The thickness A1, A2 of each one of the first and second sheets of glass is no higher than 6.5 mm and each of the inner surfaces has a dioptric defect rating, expressed in millidiopters, which is no higher than E/3 or 2E/3 according to the light transmission TL. The invention also relates to the method for manufacturing such a light valve.

Description

OPTICAL VALVE,

ITS MANUFACTURING METHOD

The invention relates to the field of electrically controllable glazings with variable optical properties and more particularly relates to an optical valve comprising between two transparent supports carrying electrodes suspended particles whose orientation is modified by application of an alternating electric or magnetic field. , the optical valve thus reversibly alternating between a generally occulting state (the off state) to a more transparent state (the on state).

Optical valves are known more specifically under the name of SPD optical valve (for "Suspended Particles Device" in English) and are developed in particular by the company Research Frontiers®. In the off state, the valve is relatively colored (appearance blue, black, gray ...) and blackout and in the state or the valve is (more) transparent possibly slightly colored.

Film optical valves marketed for example by Hitachi

Chemicals® are composed of two polyethylene terephthalate (PET) plastic sheets carrying indium tin (ITO) mixed oxide electrodes on which the SPD system is arranged as a layer in a polymeric matrix with microdroplets containing the particles in suspension, a layer typically of thickness of 50 to 130 μηι. The manufacture of this SPD film, available in roll, is made by rolling between two rolls of PET films. To enhance stiffness and strength, PET sheets can be bonded with "holt met" resin or ethylene / vinyl acetate copolymer (EVA) interlayer to glasses.

The document EP0766121 proposes in its example 1 (b) a method of manufacturing a microdroplet-type optical valve between two glasses in which the liquid composition is applied with a drawbar (draw bar in English) on the first glass with a TCO layer (TCO for transparent conductive oxide), this composition is crosslinked and then the second glass sheet is mounted.

Document W094 / 1 1722 proposes as an example 27 a method for manufacturing a microdroplet-type optical valve between two glasses in which the liquid composition is applied to the first glass with an ITO, the second glass sheet is placed on it, and the composition is then crosslinked Moreover there is another configuration of SPD system without polymeric matrix, the suspension medium with the particles then filling the entire space between two glasses carrying ITO.

Its manufacture is for example described in several documents:

in WO2004 / 061517 (in FIG. 1), the suspension is introduced between the spaced glasses by a peripheral spacer fixed to the glasses and the optical valve is then sealed

or in WO95 / 32540, an ultraviolet (UV) cross-linked acrylic resin sealing joint including spherical glass spacers and maintains a constant gap between the 50μη "ΐ glasses, the enclosed internal space containing the suspension injected by tubes fixed in the joint at opposite corners,

or in FR2147217, a peripheral sealing joint between the glasses surrounding the liquid suspension containing plastic beads now maintains a constant spacing between the glasses, the filling of the suspension intervening via a filling tube, subsequently sealed tube.

The optical performance and reliability of these SPD fluid or microdroplet matrix optical valves between two lenses can be increased. Manufacturing methods can be further improved in particular to be reliable on an industrial scale.

The present invention relates to the development of an optical valve SPD system between two glasses of simple design while ensuring satisfactory optical performance, and whose manufacture is compatible with industrial requirements (simplicity, speed, flexibility .. ).

For this purpose, the present invention firstly proposes an optical valve comprising:

first and second sheets of float glass sealed at the periphery of their facing main faces, said internal faces, by a sealing joint, in a given sealing material, preferably essentially organic,

on a main face of the first glass sheet, preferably the inner face rather than the outer face, a first electrode, in transparent electroconductive layer (multi or monolayer),

on a main face of the second glass sheet, preferably the inner face rather than the outer face, a second electrode, in a layer transparent electroconductive, (multi or monolayer),

the first and second electrodes being provided with a power supply,

and (directly or indirectly) between the inner faces, a so-called SPD system comprising particles, micron or submicron, suspended in a suspension medium which is optionally (and preferably) in the form of (micro) droplets dispersed in a matrix of preferably cross-linked polymer, SPD system of given thickness E, the SPD system (forming a layer) incorporating spacers - in the matrix or in the medium in the absence of a matrix -,

the thickness A1 of the first glass sheet being less than or equal to 6.5 mm or even 5.5 mm,

the thickness A2 (preferably equal to A1) of the second glass sheet being less than or equal to 6.5 mm or even 5.5 mm,

when the optical valve has a TL light transmission less than 5% or even less than or equal to 3%, in particular from 0.5 to 1.5%, excluding the power supply (off state), the first and second internal faces (preferably coated with first and second electrodes) each have a note of dioptric defects, expressed in millidioptrie, which is less than or equal to E / 3 where the thickness E of the SPD system is μηη, E being less than or equal to Ι ΟΟμηη, or even 90μηι or even at 70μη "ΐ,

or when the optical valve has a light transmission TL of 5% to 15% excluding power supply (off state), the first and second internal faces (preferably coated with the first and second electrodes) each have a rating of dioptric defects, expressed in millidioptrie, which is less than or equal to 2E / 3 where the thickness E of the SPD system is μηη, E being less than or equal to 50 μηη or even 35μη "ΐ.

The Applicant has discovered the relationship between the quality of the lenses and the optical performance of the optical valve, particularly when the chosen lenses are thin and / or the thickness of the SPD system is quite low.

FIG. 1 shows, as optical comparison valve, an assembly of an optical valve with two commercially available lenses 1, 2, for example of 2.1 mm, with external faces 12, 22 and internal faces 1 1 ', 21' coated with electrodes 3, 4 facing and containing a SPD 5 system of 90 μηη suspension. The internal faces 1 ', 21' (as the electrode surfaces 31, 41) have flatness defects, the thickness E of the system fluctuates in the form of local corrugations.

In "off" state (very colored state), the TL light transmission, closely related to the thickness E, is therefore non-uniform. The quality of the product is therefore unacceptable, for causes darker visually observable areas especially for products (building facade, vehicle glazing, exterior glazing ...) where natural light passes directly through the first sheet of glass (in front 1).

Also, the Applicant has evaluated that an acceptable change in TL of the optical valve is very low, of 5% maximum. This TL variation measurement is for example performed on the majority or even the entire surface of the optical valve by "cutting", for example in 40 cm by 80 cm, or by taking statistical samples.

In order to guarantee this good optical uniformity, the glasses (coated or not) must in fact have dioptric defects that are sufficiently limited and controlled.

The glasses according to the invention guarantee a thickness E sufficiently uniform over the entire surface and therefore few variations in optical performance. This avoids a high rate of rejection of the optical valve and thus improves its reliability.

Here we define a dioptric defect and a measurement method.

The profile of the inner face of each glass sheet (coated or uncoated) in question can be described by y (x) where x denotes the position on the internal face. The variation of this profile can be characterized by the optical power in reflection POR which is defined by the following relation:

The variation of y (x) is due to the two phenomena:

- ripples of the glass sheet,

- thickness defects (non-parallelism of the 2 faces of the glass sheet). This quantity is expressed in diopter (m ^"1 ) for y (x) expressed in meters.

If the second derivative y "(x) is zero, it means that the internal face of the glass is perfectly flat, if the second derivative is less than 0 it means that the inner face of the glass is concave of the glass and if the second derivative is greater at 0 it means that the inner face of the glass is convex.

The method for measuring the flatness y (x) of the internal face of the glass is a non-contact optical measurement method which consists of analyzing the contrast at any point of a so-called ombroscopic image obtained by reflection of a homogeneous light source on the inner surface of the glass.

The unmeasured outer face of the glass sheet is wet with a liquid of index close to that of the glass in order to eliminate any reflection of the light on this face and keep only the image of the directly illuminated inner face.

The flatness is thus measured every millimeter on the illuminated surface of the internal face. Each point is quantified by physical unit of optical power in millidioptrie (mdt = diopter / 1000), comparable to convergent and divergent lenses.

The final flatness is quantified by a dioptric fault score, which corresponds to the standard deviation σ of all measurements. This note, expressed in millidioptrie (mdt), perfectly characterizes the flatness of the measured surface. The note increases when the flatness deteriorates.

For a given rating of dioptric defects, the amplitude of the variation of y (x) also depends on the periodicity or pitch.

By way of example, for a sinusoidal y (x) profile with a pitch of 30 mm, a dioptric defect of 10 mdt corresponds to a profile variation of approximately +/- 0.20μη "ΐ. cases, the variation of space of an assembly of two sheets of glasses (thus variation of the thickness E) is then doubled, of approximately +/- 0,40μη-ι.For a defect of the pitch of 15 mm , the same dioptric defect of 10 mdt corresponds to a profile variation of +/- 0.05μη-ι, and the variation of the thickness E is therefore +/- 0.10μηΊ in the worst case.

The dioptric flaw pitch of a float glass sheet covers a range of a few millimeters to a few tens of millimeters. Being closely related to the uniformity of the thickness E, the uniformity of light transmission in "off" state is the consequence of all dioptric defects at all steps. The defects of the float (ripples) are generally mainly period defects around p = 30 mm.

The uniformity of light transmission in "off" state is also conditioned by the average thickness E. The greater the thickness E, the more it is possible to tolerate a variation in the thickness of the glass. This is why according to the invention a note is established according to the average thickness.

Finally, the incidence of dioptric defects is all the higher as the light transmission is low. This is why according to the invention a note is also established as a function of the TL in the off state.

The dioptric defects of float glass are mainly related to the speed of movement of the glass (taken from the line). The faster the glass scroll speed, the greater the dioptric defects. For a capacity (or daily tonnage) and a given gross glass width, the glass scroll speed is inversely proportional to the thickness A of the glass sheet. Thus, the thinner the glass sheet, the higher the glass scroll speed and the greater the dioptric defects.

Thus, one can not use a thickness at random because it is the dioptric quality of the glass which determines the possible thickness of the glass. The invention allows us to choose glasses thinner than 6 mm guaranteeing the quality of the final product. The invention allows us for example to use a thickness as small as possible while guaranteeing the optical quality of the final product. For example, it is possible to choose 2 mm glasses provided that these glasses are produced with a firing sufficiently low to guarantee the limitation of dioptric defects.

In addition, even with a 6 mm glass if the tonnage is too high for example 2000 tons / day dioptric defects are too important.

Of course, for the sake of simplicity and economy, it is preferred to select suitable float glasses rather than having to smooth (polish, etc.) any glass obtained by another manufacturing process.

The invention also makes it possible to produce optical valves with a custom dimensioning.

With current films of the fixed sizes, when a reinforcement with glasses is envisaged, it may be necessary to cut them, which causes losses of active ingredient SPD expensive.

The use of spacers, distributed in the SPD system layer including micro-droplet matrix, is essential to fix the nominal thickness E.

The spacers are of non-conductive material. The spacers may preferably be a transparent plastic material or even glass. For example, polymethylmethacrylate (PMMA) spacers are chosen. The spacers are for example in the form of balls or ovals.

The level of spacers is preferably 0.1 to 1% by weight of the SPD system, and more preferably less than or equal to 0.5%.

The invention thus proposes a method of reliability of the optical valve with a SPD system between two glasses which comprises, for a predetermined thickness E of the SPD system (and fixed by the spacers) and a predetermined level of TL in the off state, the use of a float glass with a rating of dioptric defects σ less than or equal to E / 3 (low TL) or 2E / 3 (higher TL), and remaining thickness A1 less than 6.5mm. If possible, it is also preferable to choose a float glass obtained from a shot from 500 t / day, in particular with a gross glass width from 3 m.

Alternatively, the invention thus proposes a method of reliability of the optical valve with a SPD system between two glasses which comprises, for a float glass of given thickness A1 less than 6.5 mm, the measurement of its rating of dioptric defects σ, and the use of a SPD system of thickness E less than or equal to a maximum value 3σ (low TL) or 3σ 12 (higher TL), depending on the level of TL in the off state.

If possible, it is also preferable to choose a glass obtained from a firing from 500 t / day, in particular with a raw glass width from 3 m.

In order to gain compactness or lightness in particular, the thickness A1 of the first sheet, and preferably the thickness A2 of the second glass sheet, may be less than or equal to 4.5 mm, or even less than or equal to 3.5 mm and preferably greater than or equal to 1, 6mm ± 0.2mm.

In particular, 2.1 ± 0.2 mm, 3 ± 0.2 mm 4 ± 0.2 mm, which are conventional thicknesses, in particular glass obtained by production on a Float line with a capacity of at least 500 tonnes / day, in particular, are chosen. for a glass of at least 3m wide.

In the present invention a parameter "between terminals A and B" including values A and B.

In a preferred embodiment, when said light transmission TL is less than 5%, or even less than 3%, especially 0.5 to 1.5%:

for a thickness A1 between 5.5mm and 6.5mm and preferably for a thickness A2 between 5.5mm and 6.5mm, in particular 6 ± 0.2mm, the thickness E is less than or equal to 20μη-ι,

for a thickness A1 between 4.5mm and 5.4mm and preferably for a thickness A2 between 4.5mm and 5.4mm, in particular 5 ± 0.2mm, the thickness E is less than or equal to 30μη-ι,

for a thickness A1 between 3.5mm and 4.4mm, and preferably for a thickness A2 between 3.5mm and 4.4mm, in particular 4 ± 0.2mm, the thickness E is less than or equal to 35μηι

for a thickness A1 between 2.5 mm and 3.4 mm and preferably for a thickness A2 between 2.5 mm and 3.4 mm, in particular 3 ± 0.2 mm, the thickness E is less than or equal to δθμηι,

for a thickness A1 between 1.9mm and 2.4mm, and preferably for a thickness A2 between 1.9mm and 2.4mm, in particular 2.1 ± 0.2mm, the thickness E is less than or equal to 90μηι, or even 70μηι or even 50μη "ΐ,

for a thickness A1 between 1.3mm and 1.8mm and preferably for a thickness A2 between 1.3mm and 1.8mm, in particular 1.6 ± 0.2mm, the thickness E is less than or equal to Ι ΟΟμηη; even at 70μηι or even 50μη "ΐ,

In a preferred embodiment, when said light transmission TL of

5% to 15%, especially 8 to 12%:

for a thickness A1 between 5.5mm and 6.5mm and preferably for a thickness A2 between 5.5mm and 6.5mm, the thickness E is less than or equal to 10μπΊ

for a thickness A1 between 4.5mm and 5.4mm and preferably for a thickness A2 between 4.5mm and 5.4mm, the thickness E is less than or equal to 15μη-ι,

for a thickness A1 between 3.5mm and 4.4mm, and preferably for a thickness A2 between 3.5mm and 4.4mm, the thickness E is less than or equal to 35μηι

for a thickness A1 between 2.5mm and 3.4mm and preferably for a thickness A2 between 2.5mm and 3.4mm, the thickness E is less than or equal to 25μη-ι,

for a thickness A1 between 1.9mm and 2.4mm, and preferably for a thickness A2 between 1.9mm and 2.4mm, the thickness E is less than or equal to 45μηι

for a thickness A1 between 1.3mm and 1.8mm and preferably for a thickness A2 between 1.3mm and 1.8mm, in particular 1.6 ± 0.2mm, the thickness E is less than or equal to 50 μm. .

Preferably, none of the glasses according to the invention has an opening (closed) in the main face, generally used for filling the SPD system in the glasses already sealed together by the seal.

In the microdroplet type optical valves of the prior art, the SPD system does not have a seal, the matrix further extending to the edge. Thus the seal according to the invention provides a system protection

SPD with microdroplets.

Furthermore, the seal is of given width L and can preferably be interrupted in its width by a plurality of vents defining each of the lateral ends of the seal, and for each vent an additional sealant forms a bridge between the ends. lateral of the joint, particularly in said sealing material thus forming continuity of material.

In the suspension type optical valve of the prior art, the seal is either continuous or integral with tubes for a complex manufacturing process.

The seal is preferably free of spacers and / or injection means, in the space enclosed by the seal, the SPD system in particular in suspension.

With vents - supplemented by additional sealing - interrupting according to the invention the seal of such an optical valve, optical performance (in the off state) is also improved, by participating, in particular in the edge zones, to be distributed. uniformly the SPD system.

The use according to the invention of such vents - supplemented by additional sealing - constitutes an invention in itself. However, in a preferred embodiment, it is coupled with the glasses as previously defined of limited A1, A2 thicknesses and limited diopter scores.

The seal may be interrupted in its width by at least two

(said) vents located opposite a first edge of the optical valve and by at least two other (said) vents located opposite a second edge of the optical valve opposite the first edge

The sealing joint and / or additional sealing material may be essentially organic, for example epoxy resin.

Preferably, the light transmittance of each of the first and second electrode-coated glass sheets is at least 70%.

One or more glasses can be clear, extraclear or even tinted.

Preferably, the floated glasses are not curved and / or tempered and preferably they undergo no texturizing surface treatment on their internal faces.

On the outer side of one or more glasses you can add one of the various functional elements: tinted film, low emitting layer ...

The first or the second electrode, in particular on the internal face, can itself be low emissivity (stacking with silver, etc.) as described in the patent.

US5325220 for example.

The particles can be of any shape, of any kind and of any known size. It may be particles of colloidal size (1 μηι or less) or of polyhalide or non-polyhalide type with a maximum size of 0.3μηΊ or less, preferably 0.2μηΊ or less to limit the scattering of light. A wide variety of inorganic and organic particles are known, including mica, aluminum, graphite, metal halides and perhalides of acid salts of alkaloids.

Particles can be used in the form of needles, sticks, chopsticks or in the form of thin scales ...

The concentration of the particles (depending on their efficiency in particular) can be adjusted according to the desired optical performance and / or their size can be adjusted according to the thickness E.

The SPD system may comprise a UV agent already conventionally used. The suspension medium may contain a miscible polymer.

The suspension may also include a polymeric stabilizer dissolved in the suspending medium to prevent particles from clumping together

SPD suspension systems are described in the aforementioned patents of the prior art. Other examples of SPD suspension systems are further described in US4247175, US4407565, US4772103, US5409734, US 5461506, US5463492, US6936133.

An SPD system with a polymeric matrix (hardened, crosslinked) is preferred with the droplets than a single suspension. Examples of such droplet SPD systems are described in US5463491, US5463492, US7361252, US6301040, US6416827, US6900923.

The TL when the optical valve is electrically powered is adjustable according to requirements.

The power supply (AC) can vary from level.

Each sheet of float glass can be of any shape, according to the cut: - straight edge: rectangular, square, more polygonal ...

round edge: oval, round, ellipse ... for example for portholes (building or vehicle).

The electrode layer (s) which is preferably on the inner face of the associated glass has no significant influence on the dioptric defects. Also if a "naked" float glass is suitable, glass coated with an electrode layer will also be suitable. The electrode may be monolayer (TCO etc.) or multilayer.

The electrode, preferably on the internal face of the glass, may comprise in the last layer (directly in contact with the SPD system) a given (fine) functional layer (protection, etc.) that is electroconductive or insulating (silica, etc.), without influence. on the note. Naturally, the SPD system may extend substantially over the entire glass surface (excluding outgrowing), or on (at least) a restricted area. The SPD system may be discontinuous, in several pieces (for example of the pixel type).

The optical valve according to the invention can be used in a building, in a means of locomotion terrestrial, aerial, aquatic (between two compartments, in a taxi etc.), outdoors, including:

- as facade

- as an internal partition (between two rooms or in a space)

- as glazed door, window, ceiling, roof element (canopy ..),

- glazed part of urban furniture (bus shelter ..), external partition ...

- porthole including vehicle (airplane, boat ..)

Naturally, the optical valve according to the invention can form all or part of a partition and other window (type transom etc.), a multiple glazing (with addition of additional glazing).

If necessary, one can flip through one or the other of the glasses.

The present invention also relates to a method of manufacturing an optical valve, preferably which is a valve as defined above (therefore with glasses adapted according to E), comprising:

first and second sheets of glass (preferably floated) sealed at the periphery of their facing main faces, said internal faces, by a sealing joint, in a given sealing material, preferably essentially organic,

on the inner face, of the first glass sheet, called the first internal face, a first electrode, in electroconductive layer (monolayer or multilayer) transparent,

on the internal face, of the second glass sheet, called the second internal face, a second electrode, in electroconductive single-layer or multilayer layer), in particular transparent,

and, between the first and second electrodes provided with power supply, a so-called SPD system comprising micron and / or submicron particles, suspended in a suspension medium which is optionally (and preferably) in the form of (micro) droplets dispersed in a preferably crosslinked polymer matrix, system of thickness E given, preferably less than or equal to 150 or even 130 μηη or even 100 μηι, the SPD system incorporating spacers, in particular of type spherical, transparent and preferably made of plastic material, in the matrix or in the medium in the absence of a matrix,

the method comprising the following steps (in this order or not):

applying the liquid sealing material, on the inner face of the first glass sheet (1) provided with the first electrode (3), at the edge of the internal face, thereby forming a liquid seal,

the incorporation of the spacers in a liquid mixture with the particles, the medium or even in the typically (pre) polymer liquid matrix, before, during or after the formation of the liquid seal,

the liquid deposit of the mixture (5) with the spacers on the first glass sheet (1) provided with the first electrode (3), before, during or after the application of the sealing material,

and the following steps in this order:

after applying the sealing material and depositing the mixture of the SPD system with the spacers, bringing the first and second glass sheets into contact by lowering the second glass sheet on the first glass sheet,

the pressing of the first and second sheets of glass, which is preferably calendering,

- The hardening of the sealing material (for sealing glasses) and optionally, before, during or after curing, a polymerization or crosslinking of the mixture, in particular to form the matrix incorporating the microdroplets.

The use of a seal and spacers makes it possible to control the thickness E and to avoid the loss of SPD material.

The application of the liquid mixture on the glass before assembly of the glasses is simpler than after.

Premixing spacers is simple and allows a good distribution of spacers once the mixture applied.

The liquid sealing material is preferably essentially organic, in particular in UV curable resin

The formation of the SPD system can comprise one or more polymerizations, by any conventional means (UV, etc.), in particular to form the polymer matrix of the SPD droplet system.

Advantageously, the liquid deposit of the mixture is by drop, by lineage ...

The term lineage (or cordon) is taken broadly lines that can be straight, curved, parallel, crossed ...

The drip or lineage application gives more precision than scraping application, avoids the loss of material and / or contributes to the control of the micronic thickness E.

Calendering is preferred to plane pressing, in particular to promote a continuous process and to improve the rate.

The calendering can be adjusted to distribute the mixture by evacuating trapped air (bubbles). The first sheet of glass scrolls in translation, preferably horizontally.

Prior to pressing and preferably prior to contacting the first and second glass sheets, the method may comprise forming a plurality of vents defining each of the lateral seal ends by the discontinuous application of the liquid sealant material. and / or by the continuous application of the liquid sealing material and the creation of interruptions forming the vents.

Before calendering pressing and preferably before contacting the first and second sheets of glass, at least two vents facing the first edge of the first sheet (straight-sided sheet or curves) and at least two other vents facing a second edge opposite the first edge, these edges corresponding to the edges of the calendering direction.

Before flat pressing and preferably before contacting the first and second sheets of glass, the liquid material of the seal is interrupted in its width by at least two vents facing a first edge of the first sheet, by at least two other vents facing a second edge opposite the first edge, by at least two vents facing a third edge of the first sheet adjacent to the first edge and at least two other vents facing a fourth edge of the first sheet opposite the third edge.

The method may further comprise the application by a syringe preferably of the additional liquid sealing material, after pressing, and preferably before curing, forming a bridge between the lateral ends of the seal.

The additional sealing material may be of said sealing material thus forming continuity of material, preferably essentially organic, especially epoxy resin. It is preferred a single device or a single operation to harden the sealing material, in particular by crosslinking, (preferably UV or electron beam, heat or even air) and the additional material or even the hardenable elements of the mixture SPD, including curing a liquid matrix to form the microdroplet SPD system in a crosslinked polymer matrix.

In particular, the process comprises, in one step, the curing, in particular by crosslinking, of the sealing material and the additional sealing material and / or the curing, in particular by crosslinking, of the sealing material and a liquid matrix for forming the microdroplet SPD system in a crosslinked polymer matrix.

The SPD blend may comprise a conventional crosslinking agent.

Preferably the width between the lateral ends of the seal may be at least 5 mm, for example 10 mm.

The outer face of one of the glasses may comprise a reflective layer, for example silver for example to make a rearview mirror as already known.

Other details and characteristics of the invention will appear from the detailed description which follows, made with reference to the appended drawings in which:

FIG. 1 (already described) represents a schematic sectional view of an optical valve not according to the invention,

FIG. 2 represents a schematic sectional view of an optical valve in a first embodiment according to the invention,

FIG. 3 shows the circuit diagram of the measurement of the dioptric fault score,

FIG. 4 shows the principle of forming an ombroscopic image on a screen from a flatness profile of the glass Y (x),

FIG. 5 shows an example of local illumination profile E (x) and average illumination E0 (x),

FIG. 6 represents a schematic top view of an optical valve according to the invention showing in particular the seal and the vents,

FIG. 6bis represents a schematic top view of an optical valve, showing in particular and the seal and the vents, in a variant of FIG.

FIG. 7 represents a schematic top view of the manufacture of an optical valve according to the invention showing in particular the seal of FIG. sealing and vents.

The drawings are not to scale. For the sake of simplification only the particles and not the microdroplets are represented.

The exemplary embodiment shown in FIG. 2 shows the design of an optical valve according to the invention in a first embodiment.

On two sheets of float glass 1 and 2 are disposed on the inner faces 1 1, 21 an electrically conductive layer 3, 4 with a thickness of about 20 to 400 nm, an outer surface 31, 41 made of indium oxide and tin (ITO) for example. ITO layers have a surface electrical resistance of between 5 Ω / and 300 Ω /. Instead of the layers made of ITO, it is also possible to use for the same purpose other layers of electrically conductive oxide or silver layers whose surface resistance is comparable.

The SPD system 5, of thickness E, is located between the electrode layers 3 and 4 and can be of fluid type (suspension of particles in a suspension medium) or preferably a polymer matrix (crosslinked) incorporating microdroplets of a medium with particles in suspension.

The SPD 5 system contains spherical spacers. The spacers 6 consist of a transparent hard polymer. For example, the product of Sekisui Chemical Co., Ltd., known as "Micropearl" SP, has been found to be well suited as a spacer.

To ensure the uniformity of the thickness E and thereby ensuring the optical performance of the optical valve, glasses 1, 2 are chosen with their electrodes 3, 4 each with a rating of dioptric defects according to the invention, as measured by ombroscopy in reflection.

The basic principle is related to geometrical optics. The diagram of the assembly is shown in FIG.

A light flux is projected from a thin source, such as a projector 100, onto the face of the glass sheet 11 (coated or not with the electrode) intended to be the internal face. On a screen 300 is observed an image projected after reflection on the inner face 1 1 of the glass sheet. This image is captured by a digital camera

200 to be treated. The reflection on the second face 12 is neutralized through the use of a wet black fabric placed behind the glass 1 and on which is sticking the glass by capillarity.

FIG. 4 gives the principle of forming an ombroscopic image on the screen 300 from a flatness profile of the glass Y (x). A concave zone on the glass (Convergent defect) causes a concentration of the reflected incident light 1 10 and thus a local over-illumination on the screen 300. A convex zone on the glass (divergent defect) causes a spreading of the reflected incident light 120 and therefore a sub - local illumination on the screen 300.

FIG. 5 shows an example of local illumination profile E (x) and average illumination E0 (x).

When the local illumination E (x) is equal to the average illumination E0 (x), the contrast is zero, and consequently Y "(x) = 0 and the optical power is zero.

When the local illumination E (x) is greater than the average illumination E0 (x) the contrast is negative and Y "(x) <0. It is then a convergent defect, which corresponds to a concavity on glass.

When the local illumination E (x) is lower than the average illumination E0 (x) the contrast is positive and Y "(x)> 0. It is then a divergent defect which corresponds to a convexity on glass.

Knowing that the variations of flatness are more important in the direction of the net width, to explain the principle of operation of the apparatus we will consider a profile of flatness in the plane perpendicular to the direction of casting and perpendicular to the surface of the glass.

It can be shown from the laws of geometrical optics and the conservation of energy that there is a relation between the illuminance measured on the screen E (x) corresponding to a point of abscissa x on the glass and the Y (x) profile of the glass surface.

By means of certain geometrical simplifications made from the following elements: the montage is in quasi-normal reflection and the source is considered punctual, we have the following relation: d ² Y (x) _ 1 {E ₀ ^

dx ^L DE (x)

With:

Y (x): glass profile

D: the distance between glass and screen

E ₀ : average illumination in x (that which one would have without flatness)

That is the optical power in reflection POR (in diopter): P0R = 2 X ^ ~~ 2 X ^

dx ² D with the contrast C (x) as

E ₀ - E (x)

Ex)

The contrast corresponds to the visual perception of "lineage" (dotted here since we consider a profile and not a surface) found on the shadow image projected on the screen.

A processing software calculates for each pixel of the image, the contrast and therefore the optical power in reflection POR.

The note of dioptric defects (in millidioptria) reflects the homogeneity of the optical powers and is in fact the standard deviation σ of the distribution of the optical powers in reflection on the internal face defined by the relation:

with

(POr ² ) _ij : Average over the entire inner face, of the square of the optical powers

(POr) ^ ² : Square across the inner face of the average optical power

The rating must be less than E / 3 or 2E / 3 depending on the TL to ensure sufficient optical quality in transmission, that is to say a good homogeneity of the light transmission in "off" state.

As an example, for a Float line with a standard capacity of 600 tonnes / day with a gross glass width of 3.5 m:

- the glass mark of 2.1 mm may be less than about 22 mt,

- the note of the glass of 3 mm can be lower than 1 1 mdt approximately,

- the note of 4 mm glass may be less than 8 mt

- the note of the glass of 6 mm may be less than or equal to approximately 5 mdt.

On the edge, the SPD system is sealed by a sealing adhesive seal 5 which serves at the same time to connect the glass sheets 1, 2 provided with the electrodes firmly and permanently.

The adhesive sealing material which seals the separate glass sheets 1 and

2 on their edges contains for example an epoxy resin. As shown in FIG. 6, the seal is of width L given and interrupted in its width by a plurality of vents 81 to 84 defining each of the joint lateral ends 71 to 74 '.

More precisely, the sealing joint 7 is interrupted in its width by two vents 81 to 82 facing a first edge of the optical valve and by two other vents 83, 84 facing a second edge opposite the first edge, these edges corresponding to the edges of the assembly direction of the glasses, preferably by calendering.

For each vent an additional sealing material 7 'forms a bridge between the adjacent lateral ends of the seal, in particular said sealing material thus forming continuity of material as shown in Figure 6a.

At the initial stage ("off" state), that is to say before the application of a voltage, the optical valve 100 is preferably strongly colored (almost blackout). As soon as the current is connected, the layer passes under the action of the alternating electric field in the fairly transparent state, that is to say the one in which the vision is not prevented.

The optical valve is produced using preferably a method described in detail below.

In a continuous coating industrial plant, using the magnetic field supported reactive sputtering method, float glass sheets are coated in successive spray chambers with an ITO layer of approximately 100 nm thickness .

Two separate glass sheets of equal size and the desired dimensions are cut from a large sheet of glass coated in this manner and prepared for further processing.

The two separate glass sheets cut to the desired measurements first undergo a washing operation.

A mixture is formed containing the particles suspended in a medium or even containing a liquid prepolymer matrix and further incorporating spacers.

This mixture is then applied to one of the two glass sheets preferably on the electrode side thus treated, preferably leaving a border of the uncoated glass sheet 1 over a width of about 2 to 10 mm, for example.

The deposit is made for example using an operation called drip filling or line by line. A drip or dripping apparatus is used a pipette which allows deposition on a glass substrate, the poured amount being finely adjustable.

The liquid material (adhesive etc.) forming the sealing gasket 7 is likewise applied directly along the edge of the glass sheet 24 before or after the SPD system liquid mixture has been deposited, continuously or discontinuously. It may have a width for example of 2 to 10 mm.

Finally, the liquid mixture with the spacers is surrounded by the liquid sealing material.

As shown in FIG. 7, provision is made for forming the plurality of a plurality of vents 81 to 84 of the still liquid seal of size and distribution adapted to evacuate the excess of liquid mixture, the vents 81 to 84 each defining two adjacent lateral ends 71 to 74 'of joint 7.

Also, for this purpose, the application of the liquid sealing material is either discontinuous or continuous and then followed by the creation of the vents (by removal of material 7) before or after the deposition of the SPD mixture.

When the two separate glass sheets are then pressed preferably by calendering, the liquid layer 7 is compressed to the thickness E of the layer.

Vents 81 to 84 serve therefore:

to evacuate the excess mixture, and therefore to better control the thickness of the SPD system and thus to avoid a loss of optical quality,

degassing the mixture to prevent the subsequent formation of bubbles in the SPD system and thus again to avoid loss of optical quality.

At least two vents are preferably positioned on the front edge of the calendering and at least two vents on the rear edge of the calendering.

The width of the lateral ends is an example of 10 mm. The more the SPD mixture is viscous the more venting is used. Then we proceed to calendering

If we choose a plane pressing, we add beforehand vents on the other edges.

The application of the additional liquid sealing material 7 ', which forms a bridge between the lateral ends of the seal 71 to 74' preferably to said sealing material, is then provided with a syringe, thus forming a continuity of sealing material. For example, it is a resin that is crosslinkable, preferably UV.

Finally, the curing material and the additional sealing material are cured (UV crosslinking) and the (UV) curing of the matrix is carried out. polymeric system SPD microdroplet type.

Claims

1. An optical valve (100) comprising:

first and second sheets of float glass (1, 2) sealed at the periphery of their facing main faces, said internal faces (1 1, 21), by a sealing joint (7), into a given sealing material

on a main face (1 1) of the first glass sheet, a first electrode (3), in transparent electroconductive layer,

on a main face (12) of the second glass sheet, a second electrode (4), in transparent electroconductive layer,

the first and second electrodes being provided with a power supply,

between the inner faces (1 1, 12) a system called SPD (5) comprising particles suspended in a suspension medium, SPD system incorporating spacers (6) and having a given thickness E,

the thickness A1 of the first glass sheet being less than or equal to 6.5 mm, the thickness A2 of the second glass sheet being less than or equal to 6.5 mm when the optical valve has a TL light transmission less than 5% excluding power supply, the first and second internal faces each have a note of dioptric defects, expressed in millidioptrie, which is less than or equal to E / 3 where the thickness E of the SPD system is μηη, E being less than or equal to at Ι ΟΟμηη, or

when the optical valve has a TL light transmission of 5% to 15% excluding power supply, the first and second internal faces each have a rating of dioptric defects, expressed in millidioptrie, which is less than or equal to 2E / 3 where the thickness E of the SPD system is in μηη, E being less than or equal to δθμηι.

2. optical valve (100) according to claim 1, characterized in that the thickness A1 of the first sheet, and preferably the thickness A2 of the second sheet is less than or equal to 4.5 mm, or even less than or equal to to 3.5 mm and preferably greater than or equal to 1, 6mm ± 0.2mm.

3. optical valve (100) according to one of claims 1 or 2, characterized in that when said light transmission TL is less than 5%:

for a thickness A1 between 5.5mm and 6.5mm and preferably for a thickness A2 between 5.5mm and 6.5mm, the thickness E is less than or equal to 20μηΊ,

for a thickness A1 between 4.5 mm and 5.4 mm and preferably for a A2 thickness between 4.5mm and 5.4mm, the thickness E is less than or equal to 30μη-ι,

for a thickness A1 between 2.5 mm and 3.4 mm and preferably for a thickness A2 between 2.5 mm and 3.4 mm, the thickness E is less than or equal to δθμηι,

for a thickness A1 between 1.9 mm and 2.4 mm, and preferably for a thickness A2 between 1.8 mm and 2.4 mm, the thickness E is less than or equal to ΘΟμηι,

for a thickness A1 between 1.3mm and 1.8mm and preferably for a thickness A2 between 1.3mm and 1.8mm, the thickness E is less than or equal to 100μηι.

Optical valve (100) according to one of claims 1 to 2, characterized in that when said light transmission TL from 5% to 15%:

for a thickness A1 between 5.5mm and 6.5mm and preferably for a thickness A2 between 5.5mm and 6.5mm, the thickness E is less than or equal to 10μηι

for a thickness A1 between 3.5 mm and 4.4 mm, and preferably for a thickness A2 between 3.5 mm and 4.4 mm, the thickness E is less than or equal to 35 μm.

for a thickness A1 between 1.9mm and 2.4mm, and preferably for a thickness A2 between 1.9mm and 2.4mm, the thickness E is less than or equal to 45μη-ι,

- For a thickness A1 between 1.3mm and 1.8mm and preferably A2 between 1.3mm and 1.8mm, the thickness E is less than or equal to δθμηι.

Optical valve (100) according to one of the preceding claims, characterized in that the level of spacers (6) ranges from 0.1 to 1% by weight of the SPD system, and preferably is less than 0.5% by weight of the SPD system.

Optical valve (100) according to one of the preceding claims, characterized in that the SPD system comprises a crosslinked polymeric matrix with droplets containing the suspension medium and the particles.

Optical valve (100) according to one of the preceding claims, characterized in that the seal (7) is of width L given and interrupted in its width by a plurality of vents (81 to 84) defining each of the lateral ends seal (71 to 74 '), and for each vent a so-called additional sealing material (7') forms a bridge between the lateral ends of the seal, including said sealing material thus forming continuity of material.

Optical valve (100) according to the preceding claim, characterized in that the seal (7) is interrupted in its width by at least two of said vents (81 to 82) which are located opposite a first edge of the valve optical and by at least two other of said vents (83 to 84) which are located opposite a second edge of the optical valve opposite the first edge.

Optical valve (100) according to one of the preceding claims, characterized in that the seal (7) and / or additional sealing material (7 ') is essentially organic.

A method of manufacturing an optical valve (100), particularly as defined in one of the preceding claims, comprising first and second glass sheets (1, 2) sealed at the periphery of their main facing faces, said internal faces (1 1, 21) by a sealing joint (7), in a given sealing material,

on the inner face (1 1) of the first glass sheet, a first electrode (3),

on the inner face (12) of the second glass sheet, a second electrode (4)

and, between the first and second electrodes provided with a power supply, a system called SPD (5) comprising particles suspended in a suspension medium which is preferably in the form of (micro) droplets dispersed in a polymer matrix of cross-linked preference, system of thickness E given, the SPD system incorporating spacers (6), comprising the following steps:

applying the liquid sealing material (7) to the inner face of the first glass sheet (1) provided with the first electrode (3), the incorporation of the spacers in a liquid mixture with the particles (5) and the medium,

the liquid deposit of said mixture (5) with the spacers on the first float glass sheet (1) provided with the first electrode (3),

and the following steps in this order:

after applying the sealant material and depositing the mixture of the SPD system with the spacers, contacting the first and second glass sheets (1, 2) by lowering the second glass sheet on the first sheet of glass,

the pressing of the first and second sheets of glass,

- hardening of the sealing material.

1 1. A method of manufacturing an optical valve (100) according to claim 10 characterized in that the liquid deposition of said mixture (5) with the spacers is performed by drop by drop or lineage.

12. A method of manufacturing an optical valve (100) according to one of claims 10 or 1 1 characterized in that, before pressing and preferably before contacting the first and second glass sheets, the method comprises forming the plurality of vents (81 to 84) each defining the lateral ends (71 to 74 ') of the seal (7) by the discontinuous application of the liquid sealing material and / or the continuous application of the liquid sealing material and creating interruptions forming the vents.

13. A method of manufacturing an optical valve (100) according to the preceding claim characterized in that before the pressing which is by calendering and preferably before contacting the first and second glass sheets, the liquid material of the seal of sealing (7) is interrupted in its width by at least two vents (81 to 82) facing a first edge of the first sheet and by at least two other vents (83 to 84) facing a second edge of the optical valve opposite the first edge, these first and second edges correspond to the edges in the calendering direction.

14. A method of manufacturing an optical valve (100) according to claim 12 characterized in that, before the plane pressing and preferably before contacting the first and second glass sheets, the liquid material of the seal ( 7) is interrupted in its width by at least two vents (81 to 82) opposite a first edge of the first sheet, by at least two other vents (83 to 84) facing a second edge opposite the first edge, by at minus two vents (81 to 82) facing a third edge of the first sheet adjacent to the first edge and at least two other vents (83 to 84) facing a fourth edge of the first sheet opposite the third edge ..

15. A method of manufacturing an optical valve (100) according to one of claims 10 to 14 characterized in that it comprises the application, preferably by a syringe, of an additional sealing material (7 ') liquid, forming a bridge between the lateral ends of the seal (71 to 74 '), after pressing, and preferably before curing.

16. A method of manufacturing an optical valve (100) according to the preceding claim characterized in that the additional sealing material (7 ') is in said sealing material (7), thus forming continuity of material, preferably substantially organic , especially epoxy resin.

17. A method of manufacturing an optical valve (100) according to one of claims 10 to 16 characterized in that it comprises in one step, the curing, in particular by crosslinking, of the sealing material and the material of additional sealing and / or curing, particularly by crosslinking, of the sealing material and a liquid matrix to form the microdroplet SPD system in a crosslinked polymer matrix.