CN111356589A

CN111356589A - Composite glass pane comprising functional elements with electrically controllable optical properties and having an improved optical appearance

Info

Publication number: CN111356589A
Application number: CN201980003630.5A
Authority: CN
Inventors: J.多罗萨里奥; F.曼茨; M.勒布罗特; 张慧星
Original assignee: Saint Gobain Glass France SAS
Current assignee: Saint Gobain Glass France SAS; Compagnie de Saint Gobain SA
Priority date: 2018-10-24
Filing date: 2019-09-12
Publication date: 2020-06-30
Also published as: WO2020083561A1

Abstract

The invention relates to a composite glass pane 1 for motor vehicle glazing, having an inner surface i and an outer surface a, and having a functional element 16 comprising an active layer 10 and a polarizing layer 15, which is arranged between the active layer 10 and the outer surface a and/or the inner surface i and is designed to change the polarization direction of transmitted light. The composite glass sheet of the present invention has significantly improved optical properties. In particular, in the case of oblique light incidence, the transmission performance is significantly improved.

Description

Composite glass pane comprising functional elements with electrically controllable optical properties and having an improved optical appearance

The present invention relates to composite glass sheets comprising functional elements with electrically controllable optical properties and having an improved optical appearance.

In the case of composite glazing for vehicle glazing, it is known to use functional elements having electrically controllable optical properties, the light transmission of which can be varied by applying a voltage. The various types of functional elements that can be used in this case are known to the person skilled in the art. Electrically controllable functional elements, which are used in particular in the automotive field, comprise PDLC elements (polymer dispersed liquid crystals), the active layer of which comprises liquid crystals embedded in a polymer matrix. PDLC functional elements are known, for example, from DE102008026339 a 1. Another example is an SPD functional element (suspended particle device) which is known, for example, from EP 0876608B 1 and WO 2011033313 a 1. The transmission of visible light can be controlled by the PDLC or SPD function through the applied voltage. It is thus possible to electrically darken a glass with such functional elements in a comfortable manner.

If a voltage is applied to the polymer matrix through the planar electrodes of the PDLC functional element, the liquid crystals orient along the generated electric field and the polymer layer becomes transparent. In the absence of an applied voltage, the liquid crystals are randomly oriented, whereby the polymer layer has a scattering effect and becomes opaque. The process is reversible so that the PDLC layer can be switched between transparent and opaque modes. A glass panel comprising such a PDLC functional element may also be referred to as a PDLC glass panel or, in the case of a composite glass panel, a PDLC composite glass panel.

Depending on the manufacture, the composite glass pane can, for example, be used as a variable sun protection or assume a privacy function. They are therefore particularly suitable for use in automotive glazing, for example as a windscreen panel with an electrically adjustable sun visor, as a roof glass or for side and rear glass panels. Windscreens with electrically adjustable sun visors are known, for example, from DE 102013001334 a1, DE 102005049081B 3, DE102005007427 a1 and DE 102007027296 a 1. A vehicle roof comprising PDLC composite glass panels is known, for example, from EP 2010385B 1.

However, in the case of such PDLC composite glass plates, a problem arises in that the scattering of the active layer (here, the PDLC layer) has an angle dependence in the transparent mode. The PDLC layer has minimal scattering for light impinging perpendicularly on the PDLC layer. In contrast, light obliquely incident on the PDLC layer scatters, which increases with increasing angular deviation from the perpendicular direction. This scattering causes the PDLC layer to appear milky and turbid in the transparent mode when the PDLC layer is viewed at an oblique angle. This milky turbidity is also called white mist.

When white haze is very noticeable, the environment viewed through the PDLC layer appears only hazy, with greatly reduced contrast and color saturation. White fog thus causes the optical quality of the PDLC composite glass pane to deteriorate, and may even cause visual obstruction.

Another problem occurs with PDLC composite glass sheets when the viewer views them through sunglasses with polarizing filters. The see-through properties of the PDLC composite glass pane are significantly impaired here depending on the polarizing filter used for the sunglasses.

EP 2128688 a1 discloses glasses comprising a liquid crystal element having electrically switchable optical properties, wherein a polarizing layer may be arranged on the outside of the glass.

In document WO 2018/233989 a1, published after the priority date of the present application, a vehicle glazing comprising a liquid crystal device having electrically controllable optical properties is disclosed, which has a polarizing layer between the liquid crystal device and the outside of the glazing or between the liquid crystal device and the inside of the glazing.

In JP S58136534A vehicle glass panel is described with a liquid crystal display which is embedded between polarizing plates whose permeable axes are at right angles to each other.

US 4749261 a discloses a vehicle roof glass panel comprising a liquid crystal layer, wherein the roof glass panel comprises a polarizer between the liquid crystal layer and the inner side of the glass and a depolarizer between the liquid crystal layer and the outer side of the glass.

It is therefore an object of the present invention to provide a composite glass pane comprising functional elements with electrically controllable optical properties, which has an improved optical appearance, in particular improved transmission and scattering properties in the case of oblique light incidence.

This object is achieved by a composite glass sheet according to claim 1. Preferred embodiments follow from the dependent claims.

The composite glass sheet of the present invention includes a functional element having electrically controllable optical properties embedded in a thermoplastic interlayer of the composite glass sheet. The composite glass pane has an inner surface i and an outer surface a, wherein the inner surface i in the mounted state of the glass pane in the window opening or in the vehicle body is the surface of the composite glass pane facing in the direction of the interior space. Conversely, the outer surface a represents the surface of the composite glass sheet that faces the outside environment or the vehicle environment. The composite glass pane comprises at least one inner glass pane having an inner side III and an outer side IV and an outer glass pane having an inner side II and an outer side I. The outer side IV of the inner glass sheet corresponds to the inner surface I of the composite glass sheet and the outer side I of the outer glass sheet is the outer surface a of the composite glass sheet. The inner side III of the inner glass pane and the inner side II of the outer glass pane are joined by means of a thermoplastic interlayer. A functional element having electrically controllable optical properties is embedded in the thermoplastic interlayer, wherein the functional element comprises an active layer which upon application of a voltage causes a corresponding change in the optical properties. According to the invention, a polarizing layer is arranged between the active layer and the inner side III of the inner glass pane and/or between the active layer and the inner side II of the outer glass pane. The polarizing layer is designed to change the polarization direction of light transmitted from the outer surface a toward the inner surface i. In the sense of the present invention, a change in the polarization direction can be considered both as a proportional transmission of the polarizing layer for light of only a specific polarization direction, as a change in the orientation of the electric field vector of the incident light, and as a depolarization of the polarized light impinging on the polarizing layer. It is important for the polarization direction changing feature that the light after passing through the polarizing layer has a different proportional composition of the electric field vector than before passing through the polarizing layer.

The core idea of the invention is based on the recognition that the scattering of an active layer with functional elements having electrically controllable optical properties can be angle and polarization dependent. This effect is very pronounced, in particular in the case of PDLC layers. In the case of oblique light incidence, only light of a particular polarization contributes to the scattering fraction, while light of the other polarization undergoes minimal scattering independent of the angle of incidence. By using a polarizing layer in the composite glass sheet, this effect of deteriorating the optical properties can be suppressed or significantly minimized.

In an advantageous embodiment, the functional element is a PDLC functional element (polymer dispersed liquid crystal). The active layer of the PDLC functional element contains liquid crystals embedded in a polymer matrix. If no voltage is applied to the planar electrode, the liquid crystals are aligned disorderly, which results in strong scattering of light transmitted through the active layer. If a voltage is applied to the planar electrode, the liquid crystals are aligned toward a common direction and the transmission of light through the active layer increases. Such a functional element is known, for example, from DE102008026339 a 1.

The PDLC layer exhibits a pronounced birefringence, wherein the refractive index of the resulting light beam depends on the polarization direction of the incident light beam, and the incident light is split into two sub-beams which are polarized perpendicular to each other. Dependence on the angle of incidence can also be observed. In the case of normal light incidence, there is a good match between the refractive indices of the polymer carrier matrix and the liquid crystals contained therein. Thus, in the switched state of the PDLC functional element (liquid crystal oriented in the electric field), good transparency is achieved for normal light incidence. In contrast, for other angles of incidence, an increase in the deviation of the refractive indices of the polymer matrix and the liquid crystal is observed, so that the proportion of light scattering increases at oblique angles. In the switched transparent state of the functional element, the light scattering onto the PDLC layer depends here not only on the angle of incidence but also on the polarization direction of the incident light. Light having a polarization direction parallel to the plane of incidence of the incident light beam is also referred to as V-polarized light, and scattering different from H-polarized light having a polarization direction perpendicular to the plane of incidence occurs. In one embodiment of the composite glass pane according to the invention with a PDLC functional element, the planar electrodes of the functional element are arranged in a plane parallel to the inner and outer glass panes, wherein upon application of a voltage between the planar electrodes, the liquid crystals present in the active layer have an orientation and a so-called director (Direktor) indicating the preferred direction of the liquid crystal molecules extends substantially perpendicularly to the planar electrodes. The polarization direction of the H-polarized light is here perpendicular to the director of the liquid crystal aligned in the electric field and parallel to the rotation axis of the liquid crystal. Thus, H-polarized light does not show a refractive index change depending on the incident angle. For V-polarized light, the plane of polarization extends along the director of the liquid crystal aligned in the electric field, such that the refractive index of the V-polarized light changes with the angle of incidence. Thus, V-polarized light is scattered at oblique angles of incidence, while H-polarized light is transmitted. By means of the composite glass pane according to the invention, the optical quality of the PDLC functional element incorporated therein can be significantly improved and the proportion of scattered light reduced.

The composite glass pane preferably has at least one polarizing layer which is arranged between the inner side II of the outer glass pane and the active layer and is suitable for generating linearly polarized light. By arranging a polarizing layer in front of the active layer, the transmission of scattered light can be suppressed. The transmission properties of the composite glass, in particular in the case of oblique light incidence, are thereby improved, since the clouding in the case of oblique light incidence can be reduced. This results in a composite glass with improved optical properties, wherein the formation of white mist can be significantly reduced when viewed under oblique angles.

This embodiment with a polarizing layer for generating linearly polarized light arranged between the outer glass pane and the active layer is particularly suitable for motor vehicle glazing with PDLC functional elements, for example vehicle glazing panes or motor vehicle roof glazings. In this embodiment, the polarizing layer on the side of the PDLC layer facing the vehicle environment serves to improve the optical impression of the PDLC composite glass on the inside. As already discussed with regard to the PDLC element, V-polarized light is scattered at oblique angles of incidence, while H-polarized light is transmitted. Therefore, in order to improve the optical quality of the PDLC functional element, the polarizing layer is arranged such that it transmits only H-polarized light. Therefore, only the H-polarized light transmitted by the PDLC layer reaches the PDLC functional element itself.

The polarizing layer for producing linearly polarized light is preferably manufactured in the form of one or more retardation plates which give rise to a total retardation of ʎ/2. This can be achieved, for example, by using two ʎ/4 boards in front of each other. In a preferred embodiment, the polarizing layer for producing linearly polarized light is realized by a single ʎ/2 plate. This is advantageous because in this way the rotation of the plane of polarization to be achieved can be achieved by only a single component.

In a preferred embodiment, the composite glass pane according to the invention is composed of an inner glass pane, a thermoplastic interlayer and an outer glass pane in this order, wherein the functional element and the polarizing layer are embedded in the thermoplastic interlayer and the polarizing layer is arranged between the inner side of the outer glass pane and the active layer of the functional element. The polarizing layer includes one or more retardation plates that cause a total retardation of ʎ/2. Such a composite glass pane exhibits an advantageous minimization of undesired scattering on the functional element.

In one possible embodiment of the invention, the polarizing layer is arranged between the active layer and the inner side III of the inner glass plate and is adapted to generate depolarized light. Thereby, the light emitted from the active layer toward the building interior space or the vehicle interior space is polarized. In this case, depolarized light means light that is not linearly polarized, but contains a mixture of different vibration directions. It is preferably circularly or elliptically polarized.

Under intense solar radiation, polarized sunglasses are generally used, the lenses of which are equipped with a polarizing layer. If the composite glass with PDLC functional elements is viewed, for example, from the inside through sunglasses that filter out the light transmitted by the PDLC layer (H-polarization) and allow only the light scattered by the PDLC layer to pass through, the optical quality of the composite glass sheet is significantly deteriorated. This effect is further enhanced if a polarizing layer generating linearly polarized light is already installed between the active layer and the outer glass plate. If the polarization direction of the sunglass lens does not match the polarization direction of light linearly polarized by the polarizing layer between the outer glass plate and the functional element, the intensity of light incident through the PDLC composite glass is greatly reduced. In the extreme case, the polarization layers between the outer glass plate and the functional element and the polarization directions of the sunglass lenses are perpendicular to each other, so that the incident light is almost completely suppressed by the sunglass lenses.

This effect can be prevented by depolarizing the light transmitted through the PDLC layer, since unpolarized light always contains a proportion of the light transmitted through polarized sunglasses. The use of a polarizing layer between the functional element and the inner glass sheet, which is suitable for generating depolarized light, thus further improves the optical quality of the composite glass sheet according to the invention. Here, an improvement can be observed both in the combination of the only polarizing layer between the active layer and the inner glass plate and the further polarizing layer for generating linearly polarized light between the outer glass plate and the active layer.

Preferably, the polarizing layer used to produce the depolarized light is fabricated in the form of one or more retardation plates that cause a total retardation of ʎ/4. In a preferred embodiment, the polarizing layer for depolarization of linearly polarized light is realized by a single ʎ/4 plate producing circularly or elliptically polarized light. This is advantageous because in this way the rotation of the plane of polarization to be achieved can be achieved by only a single component.

In a preferred embodiment, the composite glass pane according to the invention consists in this order of an inner glass pane, a thermoplastic interlayer with a functional element and a polarizing layer and an outer glass pane. The polarizing layer is arranged here between the inner side of the inner glass plate and the active layer of the functional element and comprises one or more retardation plates which cause a total retardation of ʎ/4. This embodiment is optimized in such a way that a sufficient light intensity is perceived in the region of the functional element even when viewed with sunglasses.

In another preferred embodiment, the composite glass sheet of the present invention comprises, in order, an inner glass sheet, a thermoplastic interlayer having a functional element and two polarizing layers, and an outer glass sheet. One of the polarizing layers is disposed between the inner side of the outer glass plate and the active layer of the functional element and comprises one or more retardation plates which cause a total retardation of ʎ/2. The other polarizing layer is disposed between the inner side of the inner glass plate and the active layer of the functional element and comprises one or more retardation plates which cause a total retardation of ʎ/4. This embodiment is advantageous because both light scattering on the active layer is minimized by the ʎ/2 retarder plate and the optical quality can be improved when using sunglasses with a polarizing layer.

For the polarizing layer, a conventional linear polarizing filter, such as a thin film polarizer, a filter having a linear dichroic material such as an anisotropic polymer layer, a deformed metal nanoparticle, or a metal polarizer, may be used.

Preferably, the polarizing layer of the composite glass sheet of the present invention is fabricated as a polymeric retarder. Both the ʎ/2 retarder and the ʎ/4 retarder are commercially available in the form of birefringent plastic films. The polymer component is very well adapted to the possible three-dimensional bending of the glass panel and can be integrated into the composite glass panel in an easy manner.

In a preferred embodiment, at least one polarizer layer is produced in the form of a carrier film with a polarizer layer and is arranged in a layer stack of thermoplastic intermediate layers. The polarizing layer may be secured to the carrier film, for example, by a tackifier layer, such as an adhesive. The carrier film serves for mechanical stability of the polarizing layer and simplifies handling of the polarizing layer during manufacture. The connection of the carrier film is effected by means of a thermoplastic composite film which is inserted between the carrier film and the nearest glass pane and between the carrier film and the functional element. This enables the use of any polarizing layer, since the fixing in the composite glass pane can be ensured by the thermoplastic composite film.

The functional element is preferably present in the form of a multilayer film having two outer carrier films. In this multilayer film, the planar electrode and the active layer are arranged between the two carrier films. By external carrier film is meant herein that the carrier film forms both surfaces of the multilayer film. The functional element can thus be provided as a laminate film which can be processed advantageously. The functional element is advantageously protected from damage, in particular from corrosion, by the carrier film. The multilayer film contains at least a first carrier film, a first planar electrode, an active layer, a second planar electrode, and a second carrier film in the order shown.

The first carrier film and/or the second carrier film preferably comprise at least one polymer which does not melt completely in an autoclave process, preferably polyethylene terephthalate (PET). The first and second carrier films are particularly preferably made of PET film. The carrier film of the present invention is preferably transparent. The thickness of the carrier film is preferably from 0.025mm to 0.400mm, in particular from 0.050mm to 0.200 mm. The planar electrode is preferably arranged on one surface of the carrier film, i.e. on the very side of both sides of the carrier film (i.e. on its front side or its back side). The carrier film is oriented in the layer stack of the multilayer film in such a way that the planar electrode is arranged adjacent to the active layer. The carrier film on which the polarizing layer is arranged corresponds in terms of its thickness and composition to the carrier film of the functional element. The film can also have different thicknesses and compositions in the region.

Electrically adjustable optical properties are understood to mean, in the context of the present invention, steplessly adjustable properties, but may equally well mean properties which can be switched between two or more discrete states.

In addition to the active layer and the planar electrode, the functional element can of course have further layers known per se, for example barrier layers, barrier layers (blockschcht), antireflection layers, protective layers and/or smoothing layers (Gl ä ttungssccht).

In one advantageous embodiment, the cutting is performed using a laser.

The functional elements are inserted via an intermediate layer between the inner and outer glass panes of the composite glass pane. The intermediate layer here preferably comprises a first thermoplastic composite film joining the functional element to the first glass pane and a second thermoplastic composite film joining the functional element to the second glass pane. In general, the intermediate layer is formed from at least a first and a second thermoplastic composite film, which are arranged one above the other in a planar manner and are laminated to one another, with the functional element being embedded between the two layers. The region of the composite film that overlaps the functional element now forms a region that joins the functional element to the glass plate. In other regions of the glass pane in which the thermoplastic composite films are in direct contact with one another, they can melt during the lamination, so that the two original layers are sometimes no longer recognizable, but instead a homogeneous intermediate layer is present.

The thermoplastic composite film may be formed, for example, from a single thermoplastic film. The thermoplastic composite film may also be formed from portions of different thermoplastic films, the side edges of which abut one another. In addition to the first thermoplastic composite film or the second thermoplastic composite film, other thermoplastic composite films may be present. They can also be used to embed other films including functional layers, such as infrared reflecting layers or acoustic damping layers, if desired.

As already described, such additional thermoplastic composite films may also be used to embed one or more polarizing layers in the composite glass sheet of the present invention.

In a further embodiment of the invention, at least one polarizing layer is integrated in one of the carrier films of the functional element. In this case, the polarizing layer is applied, for example, to the surface of the carrier film facing away from the PDLC layer and not having planar electrodes. This can be done using a tackifier, such as an adhesive. The number of layers in the composite glass sheet can thereby be advantageously reduced.

According to the invention, it is also possible, if desired, for example, to insert one polarizing layer in the form of a carrier film into the layer stack and to provide a further polarizing layer in the form of a multilayer film with an integrated polarizing layer. It is advantageous if only a polarizing layer is optionally provided which is embedded as a carrier film in the layer stack.

Instead of using a carrier film with a polarizing layer, one or more polarizing layers can be arranged directly on the inner side of the inner glass pane and/or on the inner side of the outer glass pane. Here, not the carrier film but the glass plate itself acts as a carrier substrate for the polarizing layer.

In an advantageous embodiment, the functional element has an edge seal. The edge seal covers the side edges of the functional element in a circumferential manner and prevents, in particular, the chemical components of the thermoplastic intermediate layer, for example plasticizers, from diffusing into the active layer. At least along the lower edge of the functional element, which is visible in perspective in the case of a windscreen panel, and preferably along all side edges, the edge seal is formed by a transparent, colorless adhesive or a transparent, colorless adhesive tape. For example, acrylic-based or silicone-based tapes may be used as edge seals. A clear, colorless edge seal has the advantage that the edge of the functional element does not appear to interfere when looking through the windshield. Preferably, such edge seals are also used in the case of invisible side edges, for example in the case of a roof glass pane or on the edge region of a windshield pane covered by a print.

In a preferred embodiment, the functional elements, more precisely the lateral edges of the functional elements, are surrounded circumferentially by a thermoplastic frame film. The frame film is designed in the shape of a frame and has a recess into which the functional element is inserted. The thermoplastic framing film may be formed from a thermoplastic film in which indentations have been introduced by cutting. Alternatively, the thermoplastic frame film can also consist of a plurality of film portions which surround the functional elements. In a preferred embodiment, the intermediate layer is therefore formed from a total of at least three thermoplastic composite films arranged one above the other in the form of a surface, wherein the frame film as intermediate layer has a recess in which the functional element is arranged. In the production, a thermoplastic frame film is arranged between the first and second thermoplastic composite films, wherein the side edges of all thermoplastic films are preferably present in superposition (in Deckung). The thermoplastic framing film preferably has approximately the same thickness as the functional elements. Thereby compensating for local differences in the thickness of the composite glass sheet introduced by locally defined functional elements, so that glass breakage during lamination can be avoided.

Preferably, the side edges of the functional element which are visible when looking through the composite glass pane are preferably arranged flush with the thermoplastic frame film, so that there is no gap between the side edges of the functional element and the associated side edges of the thermoplastic frame film. This applies in particular to the lower edge of a functional element of a sun visor as a windscreen panel, in which said edge is usually visible. Thus, the boundary between the thermoplastic framing film and the functional element is less visually apparent.

The tunable functional element includes an active layer between a first planar electrode and a second planar electrode. The active layer has adjustable optical properties that can be controlled by a voltage applied to the planar electrode. The planar electrodes and the active layer are typically arranged substantially parallel to the surfaces of the first and second glass plates. The planar electrodes are electrically conductively connected to a bus via which the functional element can be connected to an external voltage source.

The busbars (busbars) are connected to the planar electrodes, for example as strips of conductive material or conductive prints. The busbar is preferably manufactured as a conductive print comprising silver.

The two planar electrodes of the functional element are each formed from a conductive layer. These conductive layers comprise at least one metal, metal alloy or transparent conductive oxide, preferably a transparent conductive oxide, and have a thickness of 10nm to 2 μm. The planar electrode is preferably transparent. Transparent here means transparent to electromagnetic radiation, preferably having a wavelength of 300nm to 1300nm, in particular to visible light. The electrically conductive layers of the invention are known, for example, from DE 202008017611U 1, EP 0847965B 1 or WO2012/052315 a 1. They generally comprise one or more, for example two, three or four, conductive functional monolayers. The functional monolayer preferably comprises at least one metal, such as silver, gold, copper, nickel and/or chromium, or a metal alloy. The functional monolayer particularly preferably comprises at least 90 wt.% of metal, in particular at least 99.9 wt.% of metal. The functional monolayer may be comprised of a metal or metal alloy. The functional monolayer particularly preferably comprises silver or a silver-containing alloy. Such a functional monolayer has a particularly advantageous electrical conductivity and at the same time a high transmission in the visible spectral range. The thickness of the functional monolayer is preferably from 5nm to 50nm, particularly preferably from 8nm to 25 nm. In this thickness range, an advantageously high transmission in the visible spectral range and a particularly advantageous electrical conductivity are achieved.

The planar electrodes can in principle be formed by electrically contactable individual conductive layers.

The electrical contact of the bus bar with the external power supply is achieved by means of suitable connecting cables, for example film conductors. Suitable external control elements are known to those skilled in the art for controlling the individual segments.

The electrical adjustment of the functional elements is effected, for example, by means of push buttons, rotary actuators or sliding actuators, which are integrated, for example, in the dashboard of the vehicle. However, switching zones for the regulation, for example capacitive switching zones, can also be integrated in the composite glass pane. Alternatively, the functional element may also be controlled by non-contact methods, for example by recognizing gestures or relying on pupil or eyelid states determined by a camera and suitable evaluation electronics.

Automotive glazing, in particular windscreens, rear screens and roof screens, usually have a circumferential outer covering print made of an opaque enamel, which serves in particular to protect the adhesive used for mounting the glazing from ultraviolet radiation and to visually conceal it. Preferably, the peripheral covering print is used to cover the edge of the functional element, which edge is located in the edge region of the glass. The busbars and the required electrical connections are also mounted in the area of the cover print. In this way, the functional element is advantageously integrated into the appearance of the composite glass pane. At least the outer glass pane preferably has such a cover print, particularly preferably both the inner and outer glass panes are printed so as to prevent perspective from both sides.

The object of the invention is also achieved by a motor vehicle glazing having a composite glass pane according to the above-described embodiment. The automotive glass may form a vehicle glazing panel, a windscreen panel with a sun visor, a panorama glazing panel, a sliding roof glazing panel, a rear glazing panel or a rear or front side glazing panel. In a particularly preferred embodiment it is a windscreen panel comprising a functional element with electrically controllable optical properties as a sun visor or a roof panel comprising a functional element with electrically controllable optical properties.

The invention is explained in more detail below by means of non-limiting examples and with reference to the attached drawings. Here:

FIG. 1a shows a schematic perspective view of normal light incidence on a PDLC composite glass sheet;

FIG. 1b shows a schematic perspective view of oblique light incidence on a PDLC composite glass sheet;

FIG. 2a is a cross-sectional view of the incidence of V-polarized light on a PDLC composite glass plate;

FIG. 2b is a cross-sectional view of the incidence of H-polarized light on a PDLC composite glass plate;

FIG. 3a shows a cross-sectional view of a PDLC composite glass sheet according to a first embodiment of the present invention;

FIG. 3b shows a cross-sectional view of a PDLC composite glass sheet according to a second embodiment of the present invention;

FIG. 4a shows a cross-sectional view of a PDLC composite glass sheet according to a third embodiment of the present invention;

fig. 4b shows a cross-sectional view of a PDLC composite glass sheet according to a fourth embodiment of the present invention.

Fig. 1a and 1b are schematic perspective views each illustrating a schematic perspective view of vertical and oblique light incidence on a composite glass sheet 1 having a PDLC layer as an active layer 10. The composite glass sheet 1 has an outer surface a and an inner surface i. The light incident on each comes from the outer surface a.

PDLC layers are known and commercially available in large quantities. The PDLC layer as the active layer 10 has two conductive layers serving as planar electrodes with a gap therebetweenA polymer matrix with embedded liquid crystal droplets. Here, a planar electrode is applied to a carrier film 11 of a polymer matrix. The planar electrode may contain a Transparent Conductive Oxide (TCO), such as indium oxide doped with tin (ITO), tin oxide doped with antimony or fluorine (SnO)₂F), zinc oxide doped with gallium or zinc oxide doped with aluminum (ZnO: Al). The thickness of the planar electrode is preferably from 10nm to 2 μm, in particular from 50 to 100 nm.

The planar electrode may also be manufactured as TCC (transparent conductive coating), i.e. a transparent metal layer, preferably a thin layer or a stack of thin layers comprising metal layers. Suitable metals are, for example, Ag, Al, Pd, Cu, Pd, Pt, In, Mo, Au, Ni, Cr, W. The thickness of the monolayer is preferably 2 to 50 nm.

By applying a voltage over the planar electrodes, the liquid crystals embedded in the polymer matrix are aligned and the PDLC layer becomes transparent. Without the application of a voltage, the liquid crystals within the liquid crystal droplets are randomly oriented and the PDLC layer becomes opaque.

A voltage is applied across the PDLC layer shown in fig. 1a and 1b as the active layer 10, thereby aligning the liquid crystals as indicated by the arrows in the active layer 10. In the case of normal light incidence, the light is always polarized perpendicular to the axis along which the liquid crystal molecules are aligned. For light polarized in this way, the refractive index of the liquid crystal is the ordinary refractive index n₀. Ordinary refractive index n of liquid crystal₀Adapted to the refractive index n of the surrounding polymer matrix_p. Thus, normally incident light is not or minimally scattered on the PDLC layer.

Fig. 1b shows the case of oblique light incidence. The plane of incidence of the light represents the plane containing the incident light beam and its projection on the composite glass sheet 1, which is identified by reference sign V. Light polarized in this plane is referred to as V-polarized light. Light polarized perpendicular to the plane of incidence as indicated by the dashed line labeled H is referred to as H-polarized light. The light beam shown in fig. 1b is V-polarized and impinges on the active layer 10 at an angle of incidence θ.

Fig. 2a shows a cross-sectional view in the plane of incidence of V-polarized light impinging on a composite glass plate 1 having a PDLC layer as the active layer 10. For polarisation of lightIndicated by arrows. It can be seen that the V-polarized light is not polarized perpendicular to the axis along which the liquid crystal molecules are aligned. Refractive index n of liquid crystal molecules_effVaries with the angle of incidence θ according to the following equation, where the value n is assumed in the case of normal light incidence₀And assumes a value n in the case of tangential light incidence_e。

This means the refractive index n_effRefractive index n with polymer matrix_pThe deviation of (a) increases with increasing oblique light incidence, i.e., with increasing value of the incidence angle theta. The smaller the incident angle θ, the stronger the scattering of the V-polarized light. This scattered light is visible on the inside as a white fog.

Fig. 2b shows a cross-sectional view in the plane of incidence of H-polarized light impinging on a composite glass plate 1 having a PDLC layer as the active layer 10. The H-polarized light is polarized perpendicular to the axis along which the liquid crystal molecules are aligned, independent of the incident angle θ. Therefore, the refractive index of the liquid crystal for H polarized light is always n₀And thus there is no angle dependent scattering on the PDLC layer.

If a polarizing layer is arranged between the outer surface a of the composite glass sheet 1 and the active layer 10 and this polarizing layer polarizes the light incident from the outer surface a linearly H, angle-dependent scattering does not occur when the angle of incidence θ varies in the plane of incidence, because V-polarized light is suppressed. Therefore, white mist occurring when the composite glass plate 1 having the PDLC layer is viewed from the inner side I at an oblique angle is suppressed.

Figure 3a shows a cross-sectional view of a composite glass sheet 1 according to a first embodiment of the invention. The composite glass pane 1 has an inner glass pane 13 and an outer glass pane 14. The inner glass sheet 13 has an inner side III and an outer side IV, while the outer glass sheet 14 comprises an inner side II and an outer side I. The inner side III of the inner glass pane 13 is joined to the inner side II of the outer glass pane 14 by means of a thermoplastic interlayer 12. In the installed state of the composite pane 1 in the vehicle body, the outer side I of the outer pane 14 is the outer surface a of the glass which is directed towards the vehicle environment, while the outer side IV of the inner pane 13 forms the inner surface I which is directed towards the vehicle interior. Embedded within the thermoplastic intermediate layer 12 is a functional element 16 comprising an active layer 10 formed by a PDLC layer. The active layer 10 is surrounded on both sides by a carrier film 11. On the surface of the carrier film 11 facing the active layer 10, in each case one conductive layer is present as a planar electrode (not shown), via which a voltage can be applied to the active layer. Furthermore, a polarizing layer 15 is embedded in the thermoplastic intermediate layer 12. The functional element 16 and the polarizing layer 15 are joined to the

glass panes

13, 14 by means of the thermoplastic composite films 12.1, 12.2, 12.3 of the thermoplastic intermediate layer 12, wherein the first thermoplastic composite film 12.1 joins the functional element 16 to the inner side III of the inner glass pane 13, the second thermoplastic composite film 12.2 joins the polarizing layer 15 to the inner side II of the outer glass pane 14, and the polarizing layer 15 is connected to the functional element 16 by means of a further thermoplastic composite film 12.3. The polarizing layer 15 is located between the active layer 10 and the outer glass pane 14 and between the two thermoplastic composite films 12.2, 12.3.

The carrier film 11 serves for stabilizing the active layer 10. They are preferably polymer layers. They preferably contain at least one thermoplastic polymer. The two protective layers may, for example, comprise polyethylene terephthalate (PET), Ethylene Vinyl Acetate (EVA), polyvinyl butyral (PVB), polypropylene, polycarbonate, polymethyl methacrylate, polyacrylate, polyvinyl chloride, polyacetate resins (polyactaatharz), casting resins, acrylates, fluorinated ethylene-propylene, polyvinyl fluoride, ethylene-tetrafluoroethylene, or mixtures thereof. The carrier film 11 is particularly preferably a PET layer. This choice is particularly advantageous for the stabilization of the active layer 10. The thickness of the individual carrier films 11, in particular of the PET carrier film, can be, for example, from 0.1mm to 1mm, preferably from 0.1mm to 0.2 mm.

In the mounted state of the PDLC composite glass 1 in the vehicle, the inner glass panel 13 faces the vehicle interior space, and the outer glass panel 14 faces the vehicle exterior space. The inner glass plate 13 and the outer glass plate 14 may be composed of the same material or of different materials.

The inner and outer glass plates may be made of inorganic glass and/or organic glass (polymer). The inner glass plate 13 and/or the outer glass plate 14 preferably contain glass and/or polymers, preferably flat glass, quartz glass, borosilicate glass, soda lime glass, alkali aluminosilicate glass (alkalliminosilikat), polycarbonate and/or polymethacrylate. The inner and

outer glass plates

13, 14 are preferably made of soda lime glass.

The inner and

outer glass sheets

13, 14 may have the same thickness or different thicknesses. The inner glass plate 13 and the outer glass plate 14 preferably have a thickness of 0.4mm to 5.0mm, for example 0.4mm to 3.9mm, preferably 1.6mm to 2.5mm, independently of each other. For mechanical reasons, the outer glass plate 14 is preferably thicker than or as thick as the inner glass plate 13.

The inner glass sheet 13 and/or the outer glass sheet 14 may be clear or tinted. The tinted glass pane is preferably grey or dark grey.

The inner glass pane 13 and/or the outer glass pane 14 can have other suitable coatings known per se, for example a release coating, a coloured coating, a scratch-resistant coating or a low-emissivity coating. An example of coated glass is low emissivity glass (low emissivity glass). Low emissivity glass is commercially available and is coated with one or more metal layers. The metal coating is very thin, for example having a thickness of about 10nm to 200nm, for example about 100 nm. When using coated glass sheets as the inner and/or

outer glass sheets

13, 14, the coating is preferably located on one of the inner sides II, III of the

glass sheets

13, 14.

The inner pane 13 and/or the outer pane 14 preferably have a low-emissivity coating, wherein it is particularly preferred that only the inner pane 13 has a low-emissivity coating.

The thermoplastic composite films 12.1, 12.2, 12.3 of the thermoplastic intermediate layer 12 serve to join the other layers to form a solid composite. The thermoplastic intermediate layer 12 comprises a thermoplastic polymer. The following description refers to all of these one or more thermoplastic composite films of the intermediate layer 12 independently of one another, unless otherwise stated. The thermoplastic composite films 12.1, 12.2, 12.3 can be identical or different.

Generally, a corresponding commercially common laminate film is used as a starting material for forming the thermoplastic interlayer 12. They are used for gluing or laminating components of a composite glass pane 1 to obtain an adhesive glass composite.

The thermoplastic composite films 12.1, 12.2, 12.3 can contain, for example, polyvinyl butyral (PVB), ethylene vinyl acetate, polyurethane, polypropylene, polyacrylate, polyethylene, polycarbonate, polymethyl methacrylate, polyvinyl chloride, polyacetate resins, casting resins, acrylates, fluorinated ethylene propylene, polyvinyl fluoride and/or ethylene tetrafluoroethylene and/or mixtures and/or copolymers thereof. The laminate layer 12 preferably comprises polyvinyl butyral (PVB), ethylene vinyl acetate, polyurethane and/or mixtures and/or copolymers thereof, with PVB laminate layers being preferred.

The thermoplastic composite film 12.1, 12.2, 12.3, preferably the PVB laminate layer preferably has a thickness of 0.1mm to 1.5mm, more preferably 0.3mm to 0.9mm, prior to lamination.

The polarizing layer 15 transmits only linearly polarized light having H polarization. For the polarizing layer, common linear polarizing filters can be used, such as thin film polarizers, filters with linear dichroic materials such as anisotropic polymer layers, deformed metal nanoparticles, or metal polarizers.

Figure 3b shows a cross-sectional view of a composite glass sheet 1 according to a second embodiment of the invention. The embodiment in fig. 3b substantially corresponds to that described in fig. 3 a. The second embodiment according to fig. 3b differs, however, in that the carrier film of the active PDLC layer 10 on the side facing the inner side II of the outer glass plate 14 is formed by a carrier film 11 with a polarizing layer 15. The polarizing layer provided as a separate layer and the thermoplastic composite film 12.3 of the first embodiment for connecting the polarizing layer can thus be dispensed with. Thus, the composite glass sheet 1 may be constructed from fewer layers.

Similarly to the embodiment shown in fig. 3a and 3b for integrating a polarizing layer 15 for generating linearly polarized light between the functional element 16 and the outer glass plate 14, a polarizing layer 15 can also be arranged between the inner glass plate 13 and the functional element 16. At this position of the layer stack, a polarizing layer 15 is used to polarize the light. The two polarizing layers 15 may be used alone or in combination with each other.

Figure 4a shows a cross-sectional view of a composite glass sheet 1 according to a third embodiment of the invention. The basic structure corresponds to that described in fig. 3 a. The layer stack between the active layer 10 and the outer glass plate 14 is identical here to the first exemplary embodiment (fig. 3 a). Between the inner side III of the inner glass pane 13 and the PDLC layer (active layer 10) and between the first thermoplastic composite film 12.1 and the further thermoplastic composite film 12.3, a polarizing layer 15 is arranged, which depolarizes light that is linearly polarized by the polarizing layer 15 embedded adjacent to the inner side II of the outer glass pane 14 again.

Here, the depolarized light means light that is not linearly polarized, that is, circularly polarized or elliptically polarized light. The depolarization may be achieved, for example, by multiple scattering of linearly polarized light as it passes through a non-uniform, non-absorbing medium. In a preferred embodiment, for depolarization, for example, a λ/4 layer is used, which converts linearly polarized light into circularly polarized light, for example.

Figure 4b shows a cross-sectional view of a composite glass sheet 1 according to a fourth embodiment of the invention. This configuration substantially corresponds to that described in fig. 3 b. The layer structure of the composite glass pane 1 of fig. 4b is identical to the structure according to fig. 3b between the active layer 10 and the outer glass pane 14. In addition to this, the carrier film 11 of the active layer 10 on the side facing the inner side III of the inner glass pane 13 is formed by the carrier film 11 with the polarizing layer 15. The polarizing layer polarizes light incident from the outer surface a. By this construction, the number of layers in the composite glass pane 1 can in turn be reduced, since the polarizing layer for depolarization, which is produced as a separate component, and the thermoplastic composite film 12.3 required for incorporating the polarizing layer are dispensed with.

It should be noted that the present invention is not limited to the above-described embodiments. The embodiments can also be combined, for example, in such a way that the polarizing layer 15 for generating linearly polarized light is arranged according to the first and third embodiments between two thermoplastic composite films, while the polarizing layer for depolarization is formed according to the fourth embodiment from the carrier film 11 of the active layer 10 with the integrated polarizing layer 15. Likewise, the construction of the composite glass pane 1 between the inner surface i and the active layer 10 can be designed according to the third embodiment, but a polarizing layer for generating linearly polarized light is provided according to the second embodiment in the carrier film 11 of the PDLC element with the polarizing layer 15.

In addition to the layers, the composite pane 1 can also have one or more additional functional layers between the inner pane 13 and the outer pane 14. For example, an acoustic film or an IR-reflective (infrared-reflective) film or a layer with such a film can be incorporated into the composite glass pane. These additional layers are advantageously arranged between the respective additional thermoplastic composite films in order to obtain a stable composite.

List of reference numerals

1 composite glass plate

10 active layer

11 carrier film

12 thermoplastic interlayer

12.1 first thermoplastic composite film

12.2 second thermoplastic composite film

12.3 other thermoplastic composite films

13 inner glass plate

14 outer glass plate

15 polarizing layer

16 functional element with electrically controllable optical properties

H. Direction of V polarization

Angle of incidence of theta

a outer surface of the composite glass sheet 1

i inner surface of the composite glass pane 1

Outside of the outer glass pane 14

II inner side of outer glass pane 14

III inner side of the inner glass plate 13

IV outside of the inner glass plate 13.

Claims

1. Composite glazing panel (1) comprising a functional element (16) having electrically controllable optical properties, having an inner surface (i) and an outer surface (a) and having at least:

-an inner glass pane (13) comprising an inner side (III) and an outer side (IV), wherein the outer side (IV) corresponds to the inner surface (i) of the composite glass pane (1),

an outer glass sheet (14) comprising an inner side (II) and an outer side (I), wherein the outer side (I) corresponds to the outer surface (a) of the composite glass sheet,

-a thermoplastic interlayer (12) joining the inner side (III) of the inner glass pane (13) with the inner side (II) of the outer glass pane (14),

-a functional element (16) with electrically controllable optical properties embedded in a thermoplastic interlayer (12), comprising an active layer (10) between an inner glass plate (13) and an outer glass plate (14), and

-at least one polarizing layer (15) designed to change the polarization direction of light transmitted from the outer surface (a) towards the inner surface (i),

wherein the at least one polarizing layer (15) is arranged between the active layer (10) and the inner side (III) of the inner glass plate (13) and/or between the active layer (10) and the inner side (II) of the outer glass plate (14).

2. Composite glass pane (1) according to claim 1, wherein the functional element (16) is a PDLC element and the active layer (10) is a PDLC layer.

3. Composite glass pane (1) according to claim 1 or 2, wherein a polarizing layer (15) is arranged between the inner side (II) of the outer glass pane (14) and the active layer (10) and is adapted to generate linearly polarized light.

4. Composite glass pane (1) according to claim 3, consisting of an inner glass pane (13), a thermoplastic intermediate layer (12) with a functional element (16) and a polarizing layer (15) and an outer glass pane (14) in this order, wherein the polarizing layer (15) is arranged between the inner side (II) of the outer glass pane (14) and the active layer (10) of the functional element (16) and comprises one or more retardation plates which bring about a retardation of ʎ/2 in total.

5. The composite glass pane (1) according to any one of claims 1 to 3, wherein a polarizing layer (15) is arranged between the active layer (10) and the inner side (III) of the inner glass pane (13) and is adapted to generate depolarized light.

6. Composite glass pane (1) according to claim 5, consisting of an inner glass pane (13), a thermoplastic intermediate layer (12) with functional elements (16) and a polarizing layer (15) and an outer glass pane (14) in this order, wherein the polarizing layer (15) is arranged between the inner side (III) of the inner glass pane (13) and the active layer (10) of the functional elements (16) and comprises one or more retardation plates which cause a retardation of ʎ/4 in total.

7. Composite glass pane (1) according to claim 5, comprising in this order an inner glass pane (13), a thermoplastic intermediate layer (12) with a functional element (16) and two polarizing layers (15) and an outer glass pane (14), wherein one polarizing layer (15) is arranged between the inner side (II) of the outer glass pane (14) and the active layer (10) of the functional element (16) and comprises one or more retardation plates which bring about a total retardation of ʎ/2, and one polarizing layer (15) is arranged between the inner side (III) of the inner glass pane (13) and the active layer (10) of the functional element (16) and comprises one or more retardation plates which bring about a total retardation of ʎ/4.

8. The composite glass pane (1) according to any one of claims 1 to 7, wherein at least one polarizing layer (15) is manufactured in the form of a carrier film (11) with a polarizing layer (15) and is embedded in a layer stack of a thermoplastic interlayer (12).

9. Composite glass pane (1) according to one of claims 1 to 8, wherein the functional element comprises in order a carrier film (11), a conductive layer as a planar electrode, an active layer (10), a further conductive layer as a planar electrode and a further carrier film (11) arranged one above the other in the form of a surface.

10. Composite glass pane (1) according to claim 9, wherein at least one polarizing layer (15) is formed by at least one of the carrier films (11) of the functional elements (16).

11. The composite glass pane (1) according to any one of claims 1 to 10, wherein the thermoplastic interlayer (12) comprises at least one first thermoplastic composite film (12.1) and at least one second thermoplastic composite film (12.2), wherein the first thermoplastic composite film (12.1) joins the functional element (16) with the inner side (III) of the inner glass pane (13) and the second thermoplastic composite film (12.2) joins the functional element (16) with the inner side (II) of the outer glass pane (14).

12. Composite glass pane (1) according to claim 11, wherein the functional element (16) is surrounded circumferentially by a thermoplastic frame film arranged between the first thermoplastic composite film (12.1) and the second thermoplastic composite film (12.2).

13. Composite glass pane (1) according to any one of claims 1 to 12, wherein the at least one polarizing filter (15) comprises a polymeric retardation plate.

14. Automotive glazing comprising a composite glazing panel (1) according to any of the preceding claims, wherein the automotive glazing is a vehicle glazing panel, a windscreen panel with sun visor, a panoramic glazing panel, a sliding roof glazing panel, a roof glazing, a rear glazing panel or a rear or front side glazing panel.