A dynamic laminated glazing and a liquid crystal film laminated inside

Abstract

The present invention relates to a functional film (1) comprising at least a first and second substrate layers (14, 15), two electrically conductive layers (12, 13) and a functional layer (11) comprising liquid crystals defining an active region (A), the functional layer (11) laminated inbetween the first and second substrate layers (14, 15).

Description

A DYNAMIC LAMINATED GLAZING AND A LIQUID CRYSTAL FILM LAMINATED INSIDEFIELD OF THE INVENTION

[0001] The present invention relates to a functional film and a laminated glazing, in particular a laminated glazing intended to be used as a dynamic glazing, more in particular a laminated glazing having a functional film with liquid crystal layer laminated inside, more particularly a functional film comprising liquid crystal layer.BACKGROUND OF THE INVENTION

[0002] The invention is primarily intended to be used in production of automotive glazing but not limited to. The present invention relates to any glazing comprising a functional film such as a liquid crystal film. For example, in the architectural field such glazings are dynamic glazings that may be darkened at will, in particular electronically, in order to protect against the heat of the sun and glare. In the construction field, smart windows can be darkened at will when the weather is sunny in order to prevent the passage of light into a room, or lightened when the weather is cloudy in order to once more maximize the passage of light or light from display in case the dynamic glazing comprises an integrated display. In addition, in the architectural field, the glazings are generally flat or have a low curvature.

[0003] In the automotive field, such glazings are for example used as the roofs, windshields, rear windows and side windows including the quarter-lites and rear door fixes of vehicles as exterior glazings, or as the interior glazings such as the separation between the driver and the passenger part. In particular, glazed roofs are increasingly being substituted for conventional roofs, which form part of the body of vehicles. As in the architectural field, the choice of these roofs is the result of constructors offering to their customers this option, which makes a vehicle seem to open onto the exterior, like a convertible, without the disadvantages of convertibles, as these roofs maintain the comfort levels of a conventional sedan.

[0004] Moreover, it is more and more requested from designer and car manufacturers to have side or rear windows or glass roof provided with a functional film such as a switchable film to control the light level entering inside the vehicle forthermal comfort and / or for privacy and acoustic comfort. The latter is maintained, indeed even improved, by the presence of the laminated structure. It is known and common to laminate with an interlayer plastic sheet. However, it is difficult to laminate a functional film to be used in interlayer lamination, because of the sensitiveness of the functional film to high temperature and / or pressure andalso the curved nature of the glazing. Therefore, lamination of such glazing with functional films require a different method which eliminates the need of high temperature and pressure.

[0005] Such glazings with functional films are manufactured by different methods than conventional lamination production. More and more vehicles and buildings are now equipped with those type of glazings with functional films. Due to the nature of said functional films, the transparency of the glazing can be changed entirely along the whole area of glazing.

[0006] The classical known lamination processes of bent glass sheets with a functional film sensitive to pressure and temperature lead to presence of spots, optical or functional defects and unaesthetic glazings which are not acceptable for car manufacturer and customers. Thus, liquid or film adhesives are used to laminate a functional film and more particularly a pressure sensitive functional film into a laminated glazing as the bonding layer than the traditional PVB interlayer. Such methods are described in the prior art, like the WO2022218953 describes gravity filling method, pressure filling method and vacuum filling method. Such liquid adhesives are used as a bonding layer between the glass and the functional film. The liquid adhesives used as the bonding layer in the lamination process are preferably suitable to be used in a glazing in terms of optical properties, i.e., the optical properties of the liquid adhesive to be used are matching to the optical properties of the glazing.

[0007] Functional films comprise a conductive layer on the whole surface over the functional layer such as the liquid crystal layer. Current is applied overthe conductive layer and the liquid crystal layer is excited and therefore, the transparency of the glazing is changed. The functional layers are usually laminated inside two substrate layers.

[0008] Due to various reasons like high temperature fluctuations, the materials within the glazing expands and a stress / pressure on the functional film occurs, as a result of the said stress, dark spots or patches may occasionally appear on some liquid crystal films, such defects are usually called Mura effect. Mura is a result of the deterioration of the liquid crystal (LC) alignment layer; most commonly caused by long-term operation under high ambient temperatures. In laminated glazings used in vehicles and / or buildings, operation under high ambient temperatures are inevitable.

[0009] Moreover, due to lamination requirement mentioned above, different materials with different thermal expansion coefficients need to be used in the manufacturing process, such difference causes uneven stress / pressure, mainly a peripheral / lateral stress onto thefunctional films that cannot be avoided in addition to the stress / pressure on the perpendicular direction to the plane of functional film.

[0010] In the prior art, the use of liquid crystal (LC) films in glazings has been envisaged as a way of providing controllable visual isolation. In these applications, the main function is the transformation of an essentially transparent glazing into a glazing that is simply translucent. These applications also disclose how to protect the functional film from external effects.

[0011] W02022218953 describes a curved laminated glazing with a functional film and optical clear adhesives to fill between the functional film and the glazing. It describes different filling methods like gravity filling, pressure filling and vacuum filling.

[0012] EP369l892 describes a curved laminated glazing with a functional film, the functional film is adhered to the glazing surfaces by the help of a liquid adhesive. Similarly, WO2019198748 describes a glazing with a guest-host liquid crystal functional film and W02020003252 describes a switchable laminated glazing with liquid optical clear adhesives.

[0013] It is known from W02020087869 and US11243441 that a display panel comprising a peripheral area around the display area and a frame supporting structure is provided in the peripheral area that the frame supporting portion comprises an elastic material, and an elastic recovery rate of the elastic material is above about 80%.

[0014] It is also known from EP2920265 that an adhesive composition as an optical coupling material with comparable coefficient of thermal expansion to reduce the stress caused by it.

[0015] It is also known from KR20210048688 that a coupling member comprising an elastic layer in direct contact with the display panel to reduce Mura effect in multi-panel displays.

[0016] It is also known from CN118003721 that preventive measures are taken on the optical adhesive layer like providing cavities or changing its thickness to prevent and / or conceal the Mura effect.

[0017] None of the prior art above suggest a solution addressing to the functional film since the Mura effect which is inherently coupled to the functional film itself, but offering external / additional solutions to minimize Mura from occurring. Therefore solutions of the prior art requires extra process steps like preparation, alignment, positioning to solve Mura effect and thus the costs and production times are increased, moreover due to tolerances, such solutions are not bullet-proof. Apparently, there is a need for a functional film which addresses the Mura effect issue on the fundamental level, thus the functional film can be laminated inside a glazing without extra time and cost.SUMMARY OF THE INVENTION

[0018] The goal of the present invention is to provide a functional film resistant to Mura effect, especially the peripheral and lateral pressures / stresses and suitable for being laminated inside a glazing to eliminate the aforementioned problems.

[0019] The present invention provides a laminated glazing with a functional film that may be integrated into a bent shape glazing, but not limited to. More specifically, the present invention provides a laminated glazing with a functional film laminated with an optical coupling material but not limited to. The present invention relates also to an automotive laminated glazing comprising a functional film. According to the present invention, the glazing may also have a curvature.

[0020] The present invention concerns a laminated glazing, the glazing comprising at least: a. a first substrate sheet having an outer (Pl) and an inner (P2) faces, b. a functional film, c. a second substrate sheet having an outer (P3) and an inner (P4) faces,

[0021] I n a preferred embodiment, the functional film is a guest-host liquid crystal film (GHLC) used as a dynamic transparency changing mechanism for the glazing, however any functional film comprising liquid crystals may be implemented to the present invention. The laminated glazing comprises at least two substrate sheets, in different embodiments glazing may include three or more substrate sheets and more than one functional film.

[0022] More particularly, the present invention concerns a laminated glazing comprising at least: a. a first substrate sheet having an outer (Pl) and an inner (P2) faces, b. at least one functional film comprising at least a first and second substrate layers, two electrically conductive layers and a functional layer comprising liquid crystals defining an active region, the functional layer laminated inbetween the first and second substrate layers, c. a second substrate sheet having an outer (P3) and an inner (P4) faces, wherein the functional film comprising a dummy region comprising at least one substrate layer and surrounding the active region, the said dummy region acts as a buffer against the peripheral stress mentioned to prevent Mura effect from occurring.

[0023] According to the present invention, the dummy region surrounds the whole periphery of the active region that the dummy region tolerates / compensates / mitigates the peripheral pressure / stress from the lateral edges of the functional film as an outcome of the thermal expansion of the materials within the glazing that may disrupt the orientation / alignment of liquid crystals and cause Mura effect. The dummy region assists the mentioned peripheral stress to be absorbed to an optimal level that not cause the said Mura effect and may also transmitted / shifted uniformly over the active region, thereby no uneven pressure is applied onto the functional layer, meaning no disruption to the alignment / orientation of the liquid crystals. Thereby, the dummy region protects the functional layer, mainly the periphery of the functional layer from the pressure / stress caused by the thermal expansions of the materials inside the glazing.

[0024] According to one embodiment of the present invention, a functional film and particularly a functional film sensitive to pressure, and more particularly a switchable film such as a liquid crystal film may be used in a laminated glazing like a roof for automotive, a side window (lite), a rear fix for the vehicles which are subject to pressure during manufacturing or their use.

[0025] I n one aspect of the present invention, the dummy region is part of the functional film, i.e., produced as a single element, providing the functional film being laminated inside a glazing without any extra process steps.

[0026] In one aspect of the present invention, the dummy region is constructed by enlarging the substrate layers. The dummy region enables the active region being protected from the external peripheral pressure / stress caused by thermal expansions due to temperature changes, therefore eliminating the Mura effect on the active region of the functional film by facilitating the peripheral stress mainly to be absorbed and also transmitted / shifted / guided homogeneously over the active region.

[0027] Additionally since the Mura preventing / eliminating feature, i.e., the dummy region is part of the functional film, no extra alignment of the eliminating feature with respect to the functional film needed before or during lamination nor any additional step during the whole lamination process to prevent Mura effect. Thus, apart from preventing / eliminating the Mura effect, the present invention provides higher yield from manufacturing and higher production speed and reduction of costs.

[0028] I n addition to all above, the dummy region of the functional film may be hidden behind the enamel layer commonly used in vehicle glazings. Thus, the aesthetics of the glazing is not compromised by the inclusion of the functional film of the present invention.

[0029] The foregoing detailed description is given primarily for clearness of understanding and no unnecessary limitations are to be understood therefrom for modifications can be made by those skilled in the art upon reading this disclosure and may be made without departing from the spirit of the invention.BRIEF DESCRIPTION OF THE DRAWINGS

[0030] The invention will now be described further, by way of examples, with reference to the accompanying drawings, wherein like reference numerals refer to like elements in the various figures. These examples are provided by way of illustration and not of limitation. The drawings are a schematic representation and not true to scale. The drawings do not restrict the invention in any way. More advantages will be explained with examples. A better understanding of the present invention will be added upon reference to the following description in conjunction with the accompanying drawings.

[0031] Fig.l is a view of a vehicle with glazing. Fig.2 is a schematic view of the laminated glazing with a functional film.

[0032] Fig.3 and Fig. 4 illustrate schematic view of the laminated glazing with a functional film in different embodiments.

[0033] Fig. 5 to Fig. 10 are a schematic view of the cross-section of the functional film according to different embodiments of the present invention.

[0034] The elements illustrated in the figures are numbered as follows:1. Functional film11. Functional layer12. Conductive layer13. Conductive layer14. First substrate layer15. Second substrate layer2. Glazing21. Substrate sheet22. Substrate sheet23. Optical coupling materialA. Active regionD. Dummy regionDETAILED DESCRIPTION OF THE INVENTION

[0035] The present invention will be described with respect to particular embodiments and with reference to certain drawings but the invention is not limited thereto but only by the claims.

[0036] While some embodiments described herein include some but not other features included in other embodiments, combinations of features of different embodiments are meant to be within the scope of the invention, and form different embodiments, as would be understood by those in the art. For example, in the following claims, any of the claimed embodiments can be used in any combination.

[0037] As used herein, spatial ordirectional terms, such as "inner", "outer", "above", "below", "top", "bottom", and the like, relate to the invention as it is shown in the drawing figures. However, it is to be understood that the invention can assume various alternative orientations and, accordingly, such terms are not to be considered as limiting. Further, all numbers expressing dimensions, physical characteristics, processing parameters, quantities of ingredients, reaction conditions, and the like, used in the specification and claims are to be understood as being modified in all instances by the term "about". Accordingly, unless indicated to the contrary, the numerical values set forth in the following specification and claims are approximations that can vary depending upon the desired properties sought to be obtained by the present invention.

[0038] Moreover, all ranges disclosed herein are to be understood to be inclusive of the beginning and ending range values and to encompass any and all subranges subsumed therein. For example, a stated range of "1 to 10" should be considered to include any and all subranges between (and inclusive of) the minimum value of 1 and the maximum value of 10; that is, all subranges beginning with a minimum value of 1 or more, e.g., 1 to 6.1, and ending with a maximum value of 10 or less, e.g., 5.5 to 10. Further, as used herein, the terms "deposited over" or "provided over" mean deposited or provided on but not necessarily in surface contact with. For example, a coating "deposited over" a substrate does not preclude thepresence of one or more other coating films of the same or different composition located between the deposited coating and the substrate.

[0039] Where the term "comprising" is used in the present description and claims, it does not exclude other elements or steps. Where an indefinite or definite article is used when referring to a singular noun e.g., "a" or "an", "the", this includes a plural of that noun unless something else is specifically stated. In this document, "configured to (or set to)" may be interchangeably used in hardware and software with, for example, "appropriate to", "having a capability to", "changed to", "made to", "capable of", or "designed to" according to a situation. In any situation, an expression "device configured to do" may mean that the device "can do" together with another device or component.

[0040] Furthermore, the terms first, second and the like in the description and in the claims, are used for distinguishing between similar elements and not necessarily for describing a sequence, either temporally, spatially, in ranking or in any other manner. It is to be understood that the terms so used are interchangeable under appropriate circumstances and that the embodiments of the invention described herein are capable of operation in other sequences than described or illustrated herein. When it is described that a constituent element (e.g., a first constituent element) is "(functionally or communicatively) coupled to" or is "connected to" another constituent element (e.g., a second constituent element), it should be understood that the constituent element may be directly connected to the another constituent element or may be connected to the another constituent element through another constituent element (e.g., a third constituent element).

[0041] I n the following description, unless otherwise specified, expression "substantially" or "around" or "proximity" or "close to" preferably mean to within 10%, preferably to within 5% i.e., in this context the terms should be understood as in the range of ± 10%, even more ± 5%. Tolerance may be selected depending on the nature of the intended applications.

[0042] I n the following description, unless otherwise specified, expression "liquid adhesive", "optical coupling material", "optical resin", "optical coupling adhesive", "optical clear adhesive" and "liquid resin" are used interchangeably, further expression "functional film", "film", "electrically powered functional film" and "electrical functional film" and "liquid crystal film" are used interchangeably, further expression "flow", "fluidic flow", "liquid flow" and "liquid adhesive flow" are used interchangeably, further expression "segment", "region", "fragment" and "seeing window" are used interchangeably, further expression "glazing","laminated glazing" are used interchangeably, further expression "flexible connector", "end connector" are used interchangeably, further expression "functional layer", "dimming layer" are used interchangeably, further expression "pressure" and "stress" are used interchangeably, further expression "dummy region" and "buffer region" are used interchangeably, further expression "substrate layer" and "dielectric layer" are used interchangeably.

[0043] According to one example of the present invention, the Fig.l shows a laminated automotive sidelite; the sidelite is intended to be fixed on the vehicle's body. It is understood that the invention is not limited to a sidelite and in another preferred embodiment of the present invention, the laminated glazing (2) can be used in any glazing for a vehicle (V) and in another preferred embodiment of the present invention, the laminated glazing (2) can be used in outside or inside of automotive industry, i.e., anywhere where a laminated glazing (2) is needed.

[0044] A functional film (1) comprises at least a first and second substrate layers (14, 15), two electrically conductive layers (12, 13) and a functional layer (11) comprising liquid crystals defining an active region (A), the functional layer (11) laminated inbetween the first and second substrate layers (14, 15).

[0045] Such functional films (1) are comprised of several layers, a functional layer (11) is provided in the middle of the functional film (1), which can be a dimming layer in the case of the function is providing dimming effect. A conductive layer (12, 13) on each side of the functional layer (11) is provided to activate the functional layer (11), i.e., to provide current to the functional layer (11). A substrate layer preferably dielectric (14, 15) on each conductive layer (12, 13) is then provided to protect the functional film (1) from environment. Therefore, the functional film (1) comprises a functional layer (11) in the middle, a conductive layer (12, 13) on both sides of the functional layer (11) and a dielectric substrate layer (14, 15) on outer surfaces of both of the conductive layers (12, 13) as shown in Figures 3 and 4. The said layers (11, 12, 13, 14, 15) are stacked in the z-axis defining the thickness of the functional film (1), whereas the said peri phera l / latera I pressure / stress occurs mainly in the x-y plane as shown in figures, it is to be noted that the lateral stress may have components in the z-axis and the term "lateral / peripheral stress / pressure" is used to define the stress / pressure occurring on the periphery of the functional film (1) due to thermal expansion of the materials inside the glazing.

[0046] By "functional film" it is meant for example electrochromic means in which the variation is obtained by modifying the state of colored ions in compositions included in these glazing (2) and which are in general sensitive to application of high pressure and temperature. It is also a question of glazing (2) comprising, in suspension, layers of particles that, depending on the application of an electric voltage, are or are not ordered, such as the systems referred to as suspended particles devices (SPDs), or even a polymer-dispersed liquid-crystal (PDLC) film consisting of a polymer containing liquid crystals sensitive to the application of the electric voltage or even a guest-host liquid crystal film which include polymers, inorganic particles, or dichroic dye within the liquid crystal matrix. More particularly, the "electrically powered film" is a liquid crystals (LC) film providing controllable visual isolation. In these applications, the main function is the transformation of an essentially transparent glazing (2) into a glazing that is simply translucent. The electrically powered functional film (1) may be a display film which is electrically operated to illustrate pictures and / or videos to be seen from the outer and / or inner of the vehicle wherein the glazing (2) is placed. The "electrically powered functional film" may be made of OLED and more particularly well-known AMOLED. The glazing (2) according to the present invention may comprise a combination of one switchable film and OLED film. According to one embodiment of the present invention, the functional film (1) has a size smaller than the first (21) and the second sheet of glass (22). According to the present invention, the functional film (1) is electrically powered through a flexible connector (not shown in figures), where the flexible connector, or in other words, end connector, is coming out from the edges of the functional film (1). The way to connect the functional film (1) to a power source is well-known. In terms of the present invention, the functional film (1) is not limited to examples given above and it should be understood broadly that any functional film (1) configured to be used in glazing (2) which is suitable or not for interlayer lamination, like PVB lamination.

[0047] According to one embodiment of the present invention, the electrically powered film (1) is a film sensitive to pressure such as pressure applied during a classical lamination process including autoclave bend a glazing (2) or the thermal expansion of the materials withing the glazing (2). This kind of pressure is a pressure comprised between 0.04MPa and 14MPa. The functional film (1) is for example a LC (liquid crystal) film which is known to be sensitive to pressure. It is understood the functional film (1) may be a LC film, a GHLC film, an OLED film, PDLC film, SPD film or other functional film (1) sensitive to pressure as described previously.

[0048] In one version of the current embodiment of the present invention, the conductive layer (12, 13) is preferably ITO (Indium Tin Oxide). The conductive layer (12, 13) can be any suitable material for such functional films (1) like the transparent conductive oxides (TCO), the common conductive layer (12, 13) used in such functional films (1) is the ITO since it is transparent and the present invention prefers also the ITO as the conductive layer (12, 13), but not limited to.

[0049] In one version of the current embodiment of the present invention, the dielectric substrate layer (14, 15) is PET (Polyethylene terephthalate). The dielectric substrate layer (14, 15) can be any suitable material for such functional films (1) such as polycarbonate or cellulose acetate and etc., the common substrate layer (14, 15) used in such functional films (1) is the PET and the present invention prefers also the PET as the dielectric substrate layer (14, 15), but not limited to.

[0050] In another embodiment of the present invention, the functional film (1) comprises an adhesive layer (not shown in figures) inbetween conductive layer (12, 13) and dielectric substrate layer (14, 15).

[0051] Th us, the invention relates to any functional film (1) that is preferably sensitive to pressure, and the functional film (1) is configured to be laminated inside a glazing (2) which has optionally a complex curvature to fit with the design of the automotive, and the functional film (1) comprises an adhesive layer for lamination as described above, but not limited to.

[0052] The functional film (1) of the present invention further comprises a dummy region (D) surrounding the active region (A) preferably in the x-y plane, comprising at least one of the substrate layers (14, 15). The dummy region (D) provided on the periphery of the active region (A) and protects the liquid crystals from the peripheral / lateral pressure / stress, especially from the lateral external pressure that is caused due to thermal expansions of the different surrounding elements when laminated inside a glazing (2), more specifically the dummy region (D) protects the periphery of the active region (A) / functional layer (11) from the peripheral / lateral pressure / stress defined above. One example for the peripheral pressure / stress applied on the lateral edges of the functional layer (11), is caused by the thermal expansion of the optical coupling material (23) in high temperature fluctuations, the said can also be called tensile stress on the functional layer (11). The dummy region (D) acts like a buffer region as a protection means tolerates / mitigates the peripheral / lateral pressure / stress and keeps the liquid crystals oriented / aligned and eliminates / prevents liquidcrystals bulging inside the active region (A) when laminated inbetween glass sheets (21, 22), in other words, the latera l / pe rip hera I stress / pressure may still be generated due to thermal expansion but the dummy region (D) minimizes the effect ofwhich onto the functional layer (11) or eliminates the effect by absorbing and / or shifting / transmitting the stress / pressure. The periphera l / latera I pressure / stress is mainly absorbed by the dummy region (D) and also diverted / transmitted / shifted uniformly over the active region (A) thanks to the dummy region (D). Therefore the functional film (1) of the present invention does not require any extra protection means when laminated inside a glazing (2), offers an intrinsic / natural / instinctive protection to Mura effect.

[0053] In one embodiment of the present invention, the dummy region (D) is integrated to the functional film (1). The term "integrated" in this context should be understood as the dummy region (D) is a part of the functional film (1), i.e., the functional film (1) is a single unit with the dummy region (D). In other words, the dummy region (D) is unified with the functional film (1). Such integration may be realized during the production of the functional film (1), therefore eliminating the alignment need for external protection means for Mura effect during lamination.

[0054] In another embodiment of the present invention, the width of the dummy region (D) is equal or larger than 5 mm. It has been found out from various experiments that the minimum width of the dummy region (D) should be equal or larger than 5 mm in order to prevent disorientation / dislocation of the liquid crystals in the lateral axis due to peripheral / lateral pressure / stress, preferably larger than 5 mm, more preferably around 10 mm or more. The width of the dummy region (D) is defined in the x-axis or the y-axis or in the x-y plane.

[0055] In another embodiment of the present invention, the width of the dummy region (D) is proportional to the thickness of the active region (A), the thickness is defined in z-axis and the width is defined in x-y plane. When the active region (A) gets thicker, the lateral edge of the functional film (1) grows in size and subject to more force / stress from sides which leads to more Mura effect. Therefore a wider dummy region (D) acts as a stronger barrier / absorber for the external peripheral pressure / stress, the pressure / stress being external should be understood as it is generated by external features around the functional film (1).

[0056] In another embodiment of the present invention, the thickness of the dummy region (D) is at least 80% of the thickness of the active region (A), more preferably at least 100% ofthe active region (A), even more preferably thicker than the active region (A). Like the width of the dummy region (D), the thickness of the dummy region (D) also plays an important role in protecting the functional layer (11), thus a thicker dummy region (D) acts as a better protection means for the functional layer (11). The thickness of the dummy region (D) is also defined in the z-axis.

[0057] In a version of this embodiment, at least one of the substrate layers (14, 15) thickens towards the dummy region (D). The thickness profile of the functional film (1) may have a step like profile from the active region (A) to the dummy region (D) or a smooth incremental profile from active region (A) to the dummy region (D) or the thickness profile of at least one of the substrate layer (14, 15) may have a step like profile from the active region (A) to dummy region (D) or a smooth incremental profile from active region (A) to the dummy region (D). One example of such thickness profiles for both functional film (1) and substrate layer (14, 15) is shown in figure 7. In the case of a step-like thickness profile for the substrate layer (14, 15), the functional layer (11) can be provided onto the space in the middle of the substrate layer (14, 15) as illustrated in Fig. 8 or 10 and other substrate layer (15, 14) is provided on top of the functional layer (11), such configuration provides a better strength to the functional film (1) and the dummy region (D) also provides better protection to the Mura effect due to the dummy region (D) being individual element.

[0058] In another embodiment of the present invention, the young modulus of the dummy region (D) is at least 1500 MPa, more specifically more than 2 GPa, even more specifically in the range from 2 GPa to 10 GPa. In order to protect the liquid crystals from migrating due to external peripheral stress / pressure, the dummy region (D) should be resistant to the stress, i.e., the shape of the dummy region (D) should not be changing when peripheral pressure is applied. It has been found out from various experiments that the Mura effect is mainly prevented / eliminated when the young modulus of the dummy region (D) is minimum 1500 MPa and preferably in the said range.

[0059] In another embodiment of the present invention, the dummy region (D) is formed by lamination of the first and second substrate layers (14, 15). The dummy region (D) is produced at the same time with the active region (A) as the functional layer (11) with liquid crystals in the active region (A) is laminated in between the substrate layers (14, 15). Such lamination of the substrate layers (14, 15) in the dummy region (D) concludes the production of the functional film (1) without any extra process steps to prevent / eliminate Mura effect. In aversion of this embodiment, the first and second substrate layer (14, 15) are joined together by UV curing in the dummy region (D). In another version of this embodiment, the first and second substrate layer (14, 15) are joined together by heat curing in the dummy region (D). In a different version, the first and second substrate layer (14, 15) are joined with combination of UV curing and heat curing methods.

[0060] In another embodiment of the present invention, the dummy region (D) is formed by folding of at least one of the substrate layers (14, 15) over itself as illustrated in Fig. 9. One of the substrate layers (14, 15) is cut larger than the other to be able to produce the dummy region (D), said substrate layer (14, 15) is folded over itself in order to realize the dummy region (D). Folding of the substrate layer (14, 15) adds more strength / rigidity to the dummy region (D) that the dummy region (D) is more resistant to the peripheral stress / pressure, therefore the jeopardization of the functional film (1) due to Mura effect in the liquid crystals is mainly expelled. In a version of this embodiment, the dummy region (D) is formed by folding of both substrate layers (14, 15) over themselves, it may be like two concentric C-like profile when viewed from cross-section or like two C-like profile abutting each other, seen as an inverted M-like profile when viewed from cross-section.

[0061] In another embodiment of the present invention, the material of the substrate layers (14, 15) in the dummy region (D) is the same material of the substrate layers (14, 15) in the active region (D). The dummy region (D) is constructed by extending the substrate layer (14, 15) of the active region (A), i.e., the area of the substrate layers (14, 15) are manufactured larger than the functional layer (11) in order to produce the dummy region (D).

[0062] A laminated glazing (2) comprising at least a first substrate sheet (21) having an outer (Pl) and an inner (P2) faces, a second substrate sheet (22) having an inner (P3) and an outer (P4) faces, the said functional film (1) laminated between the inner faces (P2, P3) of the glass sheets (21, 22) with an optical coupling material (23). The functional film (1) of the present invention is laminated in between the substrate sheets (21, 22) and the optical coupling material (23) is used as a bonding layer for the functional film (1) and the substrate sheets (21, 22).

[0063] According to this embodiment of the invention, the substrate sheets (21, 22) may be a glass of soda-lime-silica, aluminosilicate or borosilicate type, and the like, the composition of the glazing (2) is not crucial for the purpose of the present invention. It should also be understood that the glazing (2) may comprise sheet made of suitable material like plastic orelse, the invention is not limited to glass sheets. Thus, the invention relates to any laminated glazing (2), whether tempered or not, that comprises a functional film (1), and the glazing (2) has optionally a complex curvature to fit with the design of the automotive, but not limited to.

[0064] According to this embodiment of the invention, the term "laminating" refers to a step of providing a layered structure in which the functional film (1) and more particularly the switchable film alone or in combination with another functional film (1), and one or more glass sheets (21, 22) are separated by an optional optical coupling material (23) acting as an adhesive interlayer extending across substantially the entire interface between the functional film (1) and the glass sheets (21, 22) facing the functional film (1) or by a conventional interlayer used in the technique such as PVB and EVA. For the sake of the invention, the adhesive layer or the bonding layer may be any suitable material, which is not utmost important for the present invention. According to one embodiment of the present invention, the optionally preferred optical coupling material (23) is in contact with the functional film (1) to maintain a distance between the functional film (1) and the at least the first and / or the second glass sheet (21, 22). Achieving such configuration of the glass sheets (21, 22) with the functional film (1) may be accomplished in any method.

[0065] In different embodiments, the optical clear resin and more generally the optical coupling material (23) according to the present invention, extends over the functional film (1) to cover its edges. Thus, the functional film (1) is protected from the moisture. Optical clear resin are widely used in display industry. The advantages of using them are high transparency, low haze and milder temperature and pressure process condition such as the ones applied in automotive lamination process. In different embodiments, the optical coupling material (23) and more particularly the optical clear resin is a thermal cure type, high elongation silicone gel. It can also be two-component type. The optical coupling material (23) as given in above embodiments is only for explanation and examples, the said can be a film or in liquid form, it is not utmost important for the sake of the present invention.

[0066] In a version of this embodiment, the width of the dummy region (D) is proportional to the coefficient of thermal expansion of the optical coupling material (23). When the functional film (1) laminated inbetween glass sheets (21, 22), the optical coupling material (23) surrounds the lateral edges of the functional film (1). In the case of high temperature changes, the optical coupling material (23) tends to expand more than the other elements in thelaminated glazing (2) due to its relatively high coefficient of thermal expansion, therefore imposes a higher force / pressure onto the lateral edges of the functional film (1). By having the width of the dummy region (D) proportional to the coefficient of thermal expansion of the optical coupling material (23), the external peripheral stress / pressure on the liquid crystals are effectively tolerated / absorbed, i.e., the higher coefficient of thermal expansion of the optical coupling material (23), the wider the dummy region (D) in order to eliminate Mura effect. As mentioned, the dummy region (D) both absorbs some of the stress and enables transmission the rest uniformly over the active region (A), and since the pressure is distributed uniformly, no Mura effect occurs.

[0067] Thus, the functional film (1), when it is incorporated into a laminated glazing (2) and positioned on a vehicle, in particular as glazed roof or side window, advantageously has to have a good aesthetic and a quick switch in mode ON / OFF in case of switchable film and clear image / information / video in case of integrated display such as OLED display.

[0068] With this invention, an affordable and yet simple solution is offered to the Mura effect issue occurred in laminated glazings (2) subject to high temperatures. Thanks to the dummy region (D) of the present invention, a buffer region created inbetween the periphery of the active region (A) and the peripheral stress / pressure means mainly in the x-y plane, and the stress / pressure is enabled to be absorbed and / or shifted by the dummy region (D) in order to protect the functional layer (11), mainly the periphery of the functional layer (11). Integration of the dummy region (D) into the functional film (1) itself during its production also eliminates the alignment of the functional film (1) and additional / external protection means since the need for an additional / external protection means is diminished.

[0069] While the invention has been illustrated and described in detail in the drawings and foregoing description, such illustration and description are to be considered illustrative or exemplary and not restrictive. The foregoing description details certain embodiments of the invention. It will be appreciated, however, that no matter how detailed the foregoing appears in text, the invention may be practiced in many ways. The invention is not limited to the disclosed embodiments.

Claims

CLAIMS1. A functional film (1) comprising at least a first and second substrate layers (14, 15), two electrically conductive layers (12, 13) and a functional layer (11) comprising liquid crystals defining an active region (A), the functional layer (11) laminated inbetween the first and second substrate layers (14, 15) characterized in that a dummy region (D) surrounding the active region (A), comprising at least one of the substrate layers (14, 15).

2. A functional film (1) according to claim 1, characterized in that the dummy region (D) is integrated to the functional film (1).

3. A functional film (1) according to any preceding claims, characterized in that the width of the dummy region (D) is equal or larger than 5mm.

4. A functional film (1) according to any preceding claims, characterized in that the width of the dummy region (D) is proportional to the thickness of the active region (A).

5. A functional film (1) according to any preceding claims, characterized in that the thickness of the dummy region (D) is at least 80% of the thickness of the active region (A).

6. A functional film (1) according to any preceding claims, characterized in that at least one substrate layer (14, 15) thickens towards the dummy region (D).

7. A functional film (1) according to any preceding claims, characterized in that the young modulus of the dummy region (D) is at least 1500 MPa.

8. Afunctional film (1) according to any preceding claims, characterized in that the dummy region (D) is formed by lamination of the first and second substrate layers (14, 15).

9. A functional film (1) according to claim 8, characterized in that the first and second substrate layer (14, 15) are joined together by UV curing in the dummy region (D).

10. A functional film (1) according to claim 8 or 9, characterized in that the first and second substrate layer (14, 15) are joined together by heat curing in the dummy region (D).

11. A functional film (1) according to claims 1 to 7, characterized in that the dummy region (D) is formed by folding of at least one of the substrate layers (14, 15) over itself.

12. A functional film (1) according to any preceding claims, characterized in that the material of the substrate layer(s) (14, 15) in the dummy region (D) is the same material of the substrate layers (14, 15) in the active region (A).

13. A laminated glazing (2) comprising at least two substrate sheets (21, 22), one optical coupling material (23) and the functional film (1) according to claims 1 to 12, characterized in that the functional film (1) is laminated inbetween the two substrate sheets (21, 22).

14. A laminated glazing (2) according to claim 13, characterized in that the width of the dummy region (D) is proportional to the coefficient of thermal expansion of the optical coupling material (23).

15. A vehicle comprising at least one laminated glazing (2) according to claims 13 or 14.

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