Variable transmission laminated glass

Abstract

Laminated glazing (1) with variable light transmission by liquid crystals comprising at least a first principal glass substrate (10), a second principal glass substrate (11), at least one liquid crystal cell (2) including dichroic dyes, the cell (2) being disposed between the first and second glass substrates (10, 11), and at least one UV filter (3) blocking UV up to 380 nm, characterized in that the laminated glazing further comprises a first filter element (5) that filters visible light in the wavelength range A from 380 to 450 nm, and a second filter element (6) that filters visible light in the wavelength range B from 451 to 700 nm, such that the laminated glazing, in its clear state at maximum light transmission, exhibits an average transmission T(A) of less than 30% over the wavelength range A, an average transmission T(B) of 0.1 to 40% over the B wavelength range,and colorimetric transmission coordinates a* from -6 to 5, preferably from -4 to 0, and b* from -5 to 5, preferably from -3 to 3.

Description

Title of the invention: Variable transmission laminated glazing

[0001] The invention relates to the field of electrically controlled glazing with variable optical properties, in particular laminated glazing with variable transmission by liquid crystals and comprising dichroic colorants as well as a UV filter.

[0002] An electrically controlled glazing with variable optical properties has the ability to make the transparency of the glazing opaque when an electrical voltage is applied to switchable functional elements integrated into the glazing. These functional elements are, for example, liquid crystals.

[0003] The invention will be described more particularly with regard to the use of variable transmission laminated glass using liquid crystals in an application for exterior glazing (for vehicles such as motor vehicles, trains, aircraft), but is not limited to this. It may also be applied to interior glazed surfaces (for buildings).

[0004] A variable transmission laminated glazing using liquid crystals comprises at least two main glass substrates, two interlayer laminated plastic films, very often made of polyvinyl butyral (PVB), and a liquid crystal cell placed between the two interlayer laminated films. The liquid crystal cell comprises liquid crystals, most often in combination with dichroic dyes (such a host-guest cell is called a "GHLC" for "Guest-Host Liquid Crystal"), encapsulated between two encapsulation substrates (generally polymeric encapsulation films) which are kept at a constant distance by means of spacers such as glass or plastic beads. Each of the encapsulation substrates is provided with an electrode.When a voltage is applied to the electrodes, the liquid crystals change orientation and modify the light transmission through the cell, the glazing changing from a clear state to a dark state, or vice versa. The "clear state" and "dark state" refer to the state of the glazing at its maximum and minimum light transmission, respectively.

[0005] However, in certain applications, particularly for exterior glazing, optical performance degrades over time because the dichroic colorants of the liquid crystal cell are sensitive to light irradiation and / or heat. The ultraviolet (UV) and infrared (IR) spectral components, in particular, lead to degradation of the dichroic colorants, manifesting, for example, as a change in color and resulting in unsightly discoloration of the glazing as well as reduced contrast between the two switching states.

[0006] In order to protect the dichroic dyes from UV rays (between 320 nm and 380 nm) and near-IR rays (between 0.7 and 2.5 pm), the glazing may include UV blockers or absorbers, or UV reflectors that filter ultraviolet radiation, and IR reflectors or IR absorbers are used in various applications. UV blockers or absorbers are, for example, made up of intermediate layers within the glazing or liquid crystals loaded with UV-absorbing molecules. IR reflectors, on the other hand, are layers integrated into the laminated glazing that reflect IR radiation and are known as low-emissivity or solar control coatings. However, it has been observed that the durability of liquid crystal cells with dichroic dyes is not yet what was expected.

[0007] Furthermore, significant progress has been made in the light and / or temperature stability of GHLC cells by working on the chemical formulation of dichroic dyes. Thus, some molecules have proven less sensitive to degradation by light and / or temperature, which may eliminate the need for UV filters. However, these molecules exhibit optical performance that is lower than that expected for glazing.

[0008] Consequently, liquid crystal cells which have high optical performance use dichroic dyes which unfortunately have limited stability to light and / or temperature, and the UV and IR filters which can be associated do not yet have sufficient performance with regard to the durability of liquid crystal cells with dichroic dyes.

[0009] The invention therefore aims to provide a laminated glazing with switchable functional elements of the liquid crystal and dichroic colorant type (system usually called "guest-host"), which does not have the aforementioned disadvantages, in particular a glazing whose switchable functional elements do not degrade rapidly over time.

[0010] According to the invention, the liquid crystal variable light transmission laminated glazing comprises at least a first main glass substrate, a second main glass substrate, at least one liquid crystal cell including dichroic dyes, the cell being disposed between the first and second glass substrates, and at least one UV filter blocking UV up to 380 nm, and is characterized in that the laminated glazing further comprises a first filtering element that filters visible light in the wavelength range A from 380 to 450 nm, and a second filtering element that filters visible light in the wavelength range B from 451 to 700 nm, such that the laminated glazing, in its clear state at maximum light transmission, exhibits an average transmission T(A) of less than 30% over the wavelength range A, an average transmission T(B) of 0.1 to 40% over the wavelength range B,and colorimetric transmission coordinates a* from 6 to 5, preferably from -4 to 0, and b* from -5 to 5, preferably from -3 to 3.

[0011] The light transmission (TL) through a glazing is measured according to ISO 9050:2023 with illuminant D65. An average transmission corresponds to the arithmetic mean of the transmissions over the wavelength range considered, for example with a step of 1 nm.

[0012] In the following description, "filtering" means that a portion of the light radiation is blocked or attenuated by absorption or reflection; that is, only a portion of the radiation, over the considered wavelength range, passes through the filtering element. In other words, an element that filters at least X% over a given wavelength range means that it has an average transmission of at most 100-X% over that range.

[0013] Hereafter, the expression "liquid crystal cell" means a liquid crystal cell incorporating dichroic dyes.

[0014] By intentionally adding at least one element with a visible light filter function, not only in visible light up to 450 nm but also up to 700 nm, while providing the aforementioned transmission, the inventors have demonstrated that the durability of liquid crystal glazing incorporating dichroic colorants is significantly improved. Furthermore, the glazing retains its aesthetic appearance, meaning it does not exhibit any noticeable color shift, particularly towards yellow. Finally, the choice of the combination of filtering elements according to the invention maximizes the light transmission of the glazing in the clear state, thus preserving its functional aspect: the provision of two states, clear and dark, with sufficiently differentiated light transmission.Thus, the solution of the invention makes it possible to retain a UV filter coupled to the liquid crystal cell (the UV filter being a simple and inexpensive way of protecting the glazing and therefore the liquid crystal cell from wavelengths up to 380 nm) and to further increase the durability of the liquid crystal glazing while preserving both the functional and aesthetic aspects of the glazing.

[0015] According to one feature, the second filtering element has an absorption spectrum comprising at least one absorption peak having a full width at half maximum (FWHM) L of at least 10 nm and at most 100 nm over the wavelength range B, in particular a FWHM L less than or equal to 50 nm over the wavelength range B. Furthermore, according to one feature, the absorption peak has a maximum intensity Imax between 5% and 100%. In particular, the ratio Imax / L is preferably between 10⁻¹ nm⁻¹ and 5 × 10⁴ nm⁻¹.

[0016] According to one feature, the first filtering element filters at least 40% of the visible light over the wavelength range A, in particular at least 50%, or even at least 60% over the wavelength range A between 380 nm and 450 nm, in particular at least 90%, preferably at least 95%, or even at least 98%, over the wavelength range A of 380 to 450 nm.

[0017] Achieving such high protection for the liquid crystal cell incorporating dichroic dyes with the glazing of the invention was not straightforward. The gain in durability is indeed far greater than that resulting from a simple proportional relationship of filtration percentages. For example, if 5% of the incident visible light is filtered in the wavelength range A, one would expect to reduce degradation due to visible light by approximately 5%. However, filtering less than 5% of visible light in the wavelength range A, combined with filtration in the wavelength range B, reduces the degradation of the liquid crystal cell by a factor of 4 or 5.The inventors have also highlighted that the combination of the two filtering elements with the UV filter preserves the aesthetic appearance of the glazing (without color deviation), which is greatly appreciated, particularly for vehicle or building glazing.

[0018] In one embodiment, the first filter element also filters at least 99%, preferably 100%, of wavelengths below 380 nm and thus also constitutes the UV filter. Alternatively, the first filter element is physically separate from the UV filter.

[0019] According to one feature, the first filtering element is a glass substrate colored throughout, or a thin layer deposited on a glass substrate providing a colouring of said glass substrate, or a colored plastic film.

[0020] According to one feature, the second filtering element is a glass substrate colored throughout, or a thin layer deposited on a glass substrate, or a colored plastic film.

[0021] Each of the first and second filtering elements can be a colored element comprising a coloring agent or several combined coloring agents.

[0022] According to one feature, when the first main glass substrate is turned towards the outside environment in the glazing use position, the first filter element is arranged between said first main glass substrate and the liquid crystal cell, while the second filter element is arranged between the first filter element and the liquid crystal cell, or between the liquid crystal cell and the second main glass substrate.

[0023] In one embodiment, the first filter element and the second filter element form a single plastic film. In particular, this single film absorbs, either through the plastic material from which it is made or through the presence of additives, in the wavelength range A, notably above 410 nm, so as to provide the first filter element and further comprises one or more agents dyes absorbing in the wavelength range B so as to provide the second filtering element.

[0024] In another embodiment, the UV filter, the first filter element, and the second filter element form a single plastic film. In particular, this single film comprises UV blocking agents and absorbs, either through the plastic material from which it is made or through the presence of additives (including possibly the UV blocking agents), in the wavelength range A, particularly above 410 nm, so as to provide the first filter element, and further comprises one or more coloring agents absorbing in the wavelength range B so as to provide the second filter element.

[0025] In one particular embodiment, the second filtering element is a colored plastic film (comprising a polymeric matrix and at least one coloring agent dispersed in the matrix).

[0026] In another embodiment, the first filter element is a colored glass substrate and the second filter element is a colored polymer layer deposited on a glass substrate. In particular, the polymer layer constituting the second filter element has a thickness of between 0.1 mm and 2 mm, preferably at most 1 mm.

[0027] According to one feature, the glazing has, in its clear state at maximum light transmission, a light transmission (LT) greater than 5%. In particular, for laminated glazing according to the invention in automobiles, such as a glass roof or windshield (lower and / or upper areas), the LT of the glazing is less than or equal to 5% in the dark state, preferably less than 2%, even more preferably less than 1% or even less than 0.5%, and the LT is greater than or equal to 5% in the clear state, preferably at least between 15% and 20%, and the contrast of the LT between the dark and clear states is between 2 and 100.

[0028] In one embodiment, the UV filter is a thin layer applied to the inner or outer face of the first main glass substrate (glass substrate intended to be turned outwards in the position of use of the glazing), or is a plastic film arranged between the first main glass substrate and the liquid crystal cell.

[0029] According to one feature, the UV filter and / or the first filter element and / or the second filter element is a polymer film based on at least one polymer selected from the following: polyvinyl butyral (PVB), ethylene vinyl acetate (EVA), polyurethane (PU), polyethylene terephthalate (PET), polyethylene, polycarbonate, polymethyl methacrylate, polyacrylate, polyvinyl chloride, polyacetate resin, acrylate, fluorinated ethylene propylene, polyvinyl fluoride, ethylene tetrafluoroethylene, cyclic olefin copolymer (COC), material Optical Clear Adhesive (OCA). OCAs are typically acrylic, polyvinyl acetate (PVA), polyurethane (PU), silicone, or epoxy. The transparent adhesive (OCA) material can be deposited in a solid, pressure-sensitive form (PSA film), or in a liquid form (resin) and cured during the lamination process, forming an interlayer film after curing. The thickness of the polymer film is preferably between 0.02 mm and 2 mm, and more preferably between 0.3 mm and 1 mm.

[0030] According to one embodiment, the liquid crystal cell comprises encapsulation substrates made of encapsulation films of polymeric material.

[0031] According to another embodiment, the liquid crystal cell comprises encapsulation substrates made of glass encapsulation substrates, the cell being laminated so that each of the two glass encapsulation substrates is made solid to one of the two main glass substrates via at least one plastic interlayer, at least one interlayer being the UV filter and at least one interlayer being the first filter element and / or the second filter element.

[0032] According to another feature, the laminated glazing comprises at least one infrared protective coating, in particular the infrared protective coating being disposed on the inner or outer face of the first main glass substrate and preferably on the outer or inner face of the second main glass substrate. The infrared protective coating is, for example, a thin layer applied to the inner or outer face of the first main glass substrate and / or an interlayer film arranged between the first main glass substrate and the liquid crystal cell. This configuration makes it possible to reflect IR so that heat and / or IR radiation do not degrade the dichroic coloring agents of the liquid crystal cell.

[0033] According to another feature, the liquid crystal cell incorporating dichroic dyes is a so-called "GHLC" (for "Guest-Host Liquid Crystal") or a polymer-based cell such as a PDLC (for "Polymer-Dispersed Liquid Crystal"), or a PNLC (for "Polymer Network Liquid Crystal") or a PSLC (for "Polymer stabilized liquid crystal").

[0034] Laminated glazing may include other functionalities, which are added via coatings in direct contact with the main glass substrates and / or (the encapsulating substrates of) the liquid crystal cell and / or with interlayer films, or which are provided directly by one or more interlayer films. These various functionalities include, for example, acoustic, anti-reflective, anti-stick, anti-scratch, photocatalytic, anti-fingerprint, anti-fog, light-extracting properties, etc.

[0035] The laminated glazing of the invention can constitute building glazing.

[0036] The laminated glazing of the invention can constitute vehicle glazing, in particular for a vehicle chosen from among a car, a train, a truck, an aircraft, a military vehicle, a tractor and a bus.

[0037] If it is a vehicle glazing, the laminated glazing is in particular chosen from a roof glazing, a rear window, a side window, a windscreen, and a gradient strip of the upper part of the windscreen.

[0038] Laminated glass can be flat or curved.

[0039] Laminated glazing can be used in double glazing or in triple glazing.

[0040] The present invention is now described using purely illustrative and in no way limiting examples of the scope of the invention, and from figure [Fig.1] which represents a schematic cross-sectional view of laminated glazing according to an example of an embodiment of the invention.

[0041] For the sake of clarity, the various elements shown in the figures are not reproduced to scale.

[0042] The laminated glazing 1 of the invention illustrated in [Fig. 1] is a variable transmission laminated glazing made of liquid crystals comprising a liquid crystal cell 2 incorporating dichroic dyes. The glazing of the invention is designed to effectively increase the durability and long-term stability of the dichroic dyes in the liquid crystal cell 2. To this end, in addition to a UV filter blocking UV up to 380 nm, the glazing 1 comprises a first filtering element that filters visible light in the wavelength range A from 380 to 450 nm and a second filtering element that filters visible light in the wavelength range B from 451 to 700 nm.

[0043] The laminated glass 1 is intended for building or vehicle applications. The light transmission of the laminated glass 1 is modified when an electrical voltage is applied to the electrodes of the liquid crystal cell 2. The glass 1 can be normally clear (maximum light transmission) in the absence of voltage, and it becomes dark (minimum light transmission) when a voltage is applied. Conversely, the glass can be designed to be normally dark when no voltage is applied; it then becomes clear when a voltage is applied. The normally clear or normally dark state depends on the intended use of the glass.

[0044] Depending on the uses made of the laminated glazing 1 described below with regard to [Fig.1] or in envisaged variants not illustrated, it will be used in a monobloc as such as single glazing, or will be combined with one or more other laminated or spaced glass substrates.

[0045] The laminated glazing 1 illustrated in [Fig. 1] comprises a first main glass substrate 10, a second main glass substrate 11 arranged at a distance and opposite the first substrate 10, the liquid crystal cell 2 arranged in the core of the glazing, a UV filter 3 blocking UV up to 380 nm and interlayer elements, here 40, 41 and 42, for bonding the liquid crystal cell 2 to the glass substrates 10 and 11 and / or to the first and second filter elements, and said first and second filter elements 5 and 6. Depending on the nature of the liquid crystal cell 2 and the constituent support (the matrix) of the filter elements, the bonding interlayers may, for example, be a PVB film or an OCA layer. The bonding interlayers have a thickness between 0.1 mm and 2 mm, in particular 0.38 mm or 0.76 mm.

[0046] The main glass substrates 10 and 11 have a thickness suitable for use with laminated glazing. The thickness can be between 0.3 mm and 15 mm, preferably between 1 and 5 mm; for example, it is 1.6 mm, 1.8 mm or 2.1 mm.

[0047] The liquid crystal cell 2 is, for example, a guest-host liquid crystal cell comprising a liquid volume of liquid crystals mixed with dichroic dyes. The liquid crystal cell 2 is of a known type.

[0048] The first glass substrate 10 being intended to be oriented towards the external environment, the UV filter 3 is associated with it.

[0049] The UV filter 3 is made of a polymeric material such as PVB, possessing the property of blocking ultraviolet light up to 380 nm. The ultraviolet blocking property is preferably provided by molecules dispersed in the polymeric matrix of the film, which are capable of blocking ultraviolet light and which do not absorb visible radiation.

[0050] The UV filter 3 has a transmission for each wavelength in the wavelength range from 280 nm to 380 nm of less than 1%, preferably less than 0.1%, preferably even less than 0.01%, preferably equal to 0%.

[0051] Furthermore, the glazing 1 comprises the first filter element 5 which filters visible light in the wavelength range A from 380 to 450 nm, and the second filter element 6 which filters visible light in the wavelength range B from 451 to 700 nm, the first and second filter elements 5 and 6 being such that the laminated glazing 1, in its clear state at maximum light transmission, has an average transmission T(A) of less than 30% over the wavelength range A, an average transmission T(B) of 0.1 to 40% over the wavelength range B, and colorimetric transmission coordinates a* of -6 to 5, preferably from -4 to 0, and b* of -5 to 5, preferably from -3 to 3.

[0052] The first filter element 5 is a colored glass substrate, or a thin film deposited on a glass substrate, or a colored plastic film. The second filter element 6 is a colored glass substrate, or a thin film deposited on a glass substrate, or a colored plastic film. coloring agents of the first and second filter elements 5 and 6 are selected to confer the aforementioned filtering properties for the glazing.

[0053] In order to protect the liquid crystal cell 2 from the heat of infrared radiation, the glazing 1 preferably includes an infrared protective coating 70 (solar control coating) which is arranged on the inner face (referred to as face F2) of the first main glass substrate 10 (when this first glass substrate is intended to face outwards, such as towards the exterior of the vehicle's passenger compartment). This IR protective coating protects the liquid crystal cell 2 from the heat that the glazing may receive from solar radiation.

[0054] The glazing 1 may include a low emissive layer 71 on the external face of the second main glass substrate 11 (face intended to be turned towards the passenger compartment of the vehicle, referred to as face F4) to minimize heat loss in the passenger compartment in winter and the feeling of a cold wall.

[0055] In the illustrated example of [Fig. 1], the following are stacked from the first glass substrate 10 and between said first glass substrate 10 and the liquid crystal cell 2: the infrared protective coating 70, the UV filter 3, the first filter element 5 which is a colored glass substrate, an interlayer 40 such as a PVB film, a glass substrate 60 whose TL is preferably at least 91%, the second filter element 6 with a polymer matrix deposited on the glass substrate 60, and an OCA 41. The interlayer 40 has made it possible to bond the first glass filter element 5 to the glass substrate 60. The OCA 41 has made it possible to bond the polymer matrix of the second filter element 6 to the liquid crystal cell 2 whose encapsulation substrates are polymeric. On the other side of the liquid crystal cell 2, said cell is secured to the second glass substrate 11 by an OCA 42.

[0056] In this illustrated example, - UV filter 3 is a commercial PVB film that filters ultraviolet rays, for example the film marketed under the name Saflex®PVB from the company Eastman, 0.76 mm thick, which filters 99% up to 380 nm; - The first filter element 5 is a colored glass substrate (the glass of the substrate contains a coloring agent) and has a thickness of 0.38 mm. The colored glass substrate constituting the first filter element 5 is commercially available; for example, it is the product marketed under the name GG435 by the company SCHOTT. This first filter element 5 filters visible light up to 435 nm, so that it has zero transmission for each wavelength up to 435 nm; - The second filter element 6 is a polymer layer containing a coloring agent. The coloring agent is, for example, the product marketed under the name FDG-005 by Yamada Chemicals. This FDG-005 colorant exhibits an absorbance peak at 580 nm, and a full width at half maximum of 30 nm at a concentration of 0.26% relative to the total dry weight and for a film thickness of 8 pm; - the glass substrate 60 comprising the second filter element 6 is a clear glass such as the product marketed under the name PLANICLEAR® by the company SAINT-GOBAIN; its thickness is 2.1 mm.

[0057] More specifically, in the aforementioned example for the second filter element 6, a solution is prepared comprising a solvent such as methyl ethyl ketone (MEK) at 70 wt%, polymethyl methacrylate (PMMA) at 29.3 wt%, and FDG-005 at 0.7 wt%. After mixing, the solution is deposited onto the glass substrate 60 using a film puller to obtain a layer of 8 µm. After coupling the second filter element 6 to the first filter element 5 by assembling the glass substrate 60 of the second filter element 6 to the first filter element 5 via the interlayer 40, the second filter element 6 is located on the side of the liquid crystal cell 2.

[0058] The combination of the UV filter 3 with the first filter element 5 and second filter element 6, acting respectively in the visible ranges of wavelengths A and B, effectively increases the durability and long-term stability of the dichroic colorants in the liquid crystal cell 2, while preserving its aesthetic properties. The light transmission of the glazing in the aforementioned example remains quite acceptable in the clear state, with an average transmission T(A) of 3% in the wavelength range A, an average transmission T(B) of 17% in the wavelength range B, and colorimetric transmission coordinates a* of -2 and b* of 1 according to the illuminant CIE D65 2° (CIE 1931).

[0059] Moreover, the AE color variation of the glazing in the aforementioned example is less than 5, after an accelerated aging test which corresponds to 1400 hours of operation of the liquid crystal cell 2, whereas comparatively, a glazing with the same liquid crystal cell 2 protected by the same UV filter 3 has an AE color variation of 26 after the same accelerated aging test.

[0060] Thus, the inventors have surprisingly demonstrated that by adding to the UV filter which filters up to 380 nm, the first filtering element and the second filtering element according to the invention which respectively filter in the visible beyond 380 nm up to 450 nm and between 451 nm and 700 nm, it is possible to increase the durability and stability of the liquid crystal cell 2 and the dichroic dyes, and therefore of the glazing 1, while preserving the aesthetic and functional aspects of the glazing.

Claims

Demands

1. Laminated glazing (1) with variable light transmission by liquid crystals comprising at least a first principal glass substrate (10), a second principal glass substrate (11), at least one liquid crystal cell (2) including dichroic dyes, the cell (2) being disposed between the first and second glass substrates (10, 11), and at least one UV filter (3) blocking UV up to 380 nm, characterized in that the laminated glazing further comprises a first filter element (5) that filters visible light in the wavelength range A from 380 to 450 nm, and a second filter element (6) that filters visible light in the wavelength range B from 451 to 700 nm, such that the laminated glazing, in its clear state at maximum light transmission, exhibits an average transmission T(A) of less than 30% over the wavelength range A, an average transmission T(B) from 0.1 to 40% over the wavelength range B,and colorimetric transmission coordinates a* from -6 to 5, preferably from 4 to 0, and b* from -5 to 5, preferably from -3 to 3.

2. Laminated glazing according to claim 1, characterized in that the second filtering element (6) has an absorption spectrum comprising at least one absorption peak having a full width at half maximum L of at least 10 nm and at most 100 nm over the wavelength range B, in particular a full width at half maximum L less than or equal to 50 nm over the wavelength range B.

3. Laminated glazing according to the preceding claim, characterized in that the absorption peak has a maximum intensity Imax between 5% and 100%, the Imax / L ratio preferably being between 10⁻¹ nm⁻¹ and 5 x 10⁴ nm⁻¹

4. Laminated glazing according to any one of the preceding claims, characterized in that the first filtering element (5) filters at least 40% of the visible light over the wavelength range A, in particular at least 50%, or even at least 60%, in particular at least 90%, preferably at least 95%, or even at least 98%, over the wavelength range A.

5. Laminated glazing according to any one of the preceding claims, characterized in that the first filtering element (5) filters at least 99%, preferably 100%, of wavelengths below 380 nm and also constitutes the UV filter.

6. Laminated glazing according to any one of claims 1 to 4, characterized in that the first filtering element (5) is physically distinct from the UV filter (3).

7. Laminated glazing according to any one of the preceding claims, characterized in that the first filtering element (5) is a glass substrate coloured throughout, or a thin layer deposited on a glass substrate, or a film of coloured plastic material.

8. Laminated glazing according to any one of the preceding claims, characterized in that the second filtering element (6) is a glass substrate coloured throughout, or a thin layer deposited on a glass substrate, or a coloured plastic film.

9. Laminated glazing according to any one of the preceding claims, characterized in that when the first main glass substrate (10) is facing the outside environment in the glazing use position, the first filter element (5) is arranged between said first main glass substrate (10) and the liquid crystal cell (2), while the second filter element (6) is arranged between the first filter element (5) and the liquid crystal cell (2), or between the liquid crystal cell (2) and the second main glass substrate (11).

10. Laminated glazing according to any one of the preceding claims, characterized in that the first filter element (5) and the second filter element (6) form a single film of plastic material.

11. Laminated glazing according to any one of claims 1 to 5, characterized in that the UV filter (3), the first filter element (5) and the second filter element (6) form a single plastic film.

12. Laminated glazing according to any one of claims 1 to 9, characterized in that the first filter element (5) is a glass substrate coloured in mass and the second filter element (6) is a coloured polymeric layer deposited on a glass substrate.

13. Laminated glazing according to any one of the preceding claims, characterized in that it comprises at least one coating infrared protection (70, 71), in particular the infrared protection coating being disposed on the inner or outer face of the first main glass substrate (10) and preferably on the outer or inner face of the second main glass substrate (11).

14. Laminated glazing according to any one of the preceding claims, characterized in that it is flat or curved, which can be used as single glazing, or used in double glazing or in triple glazing.

15. Laminated glazing according to any one of the preceding claims, characterized in that it is vehicle glazing selected from an automobile, a train, a truck, an aircraft, a military vehicle, a tractor and a bus.