FUNCTIONAL ELEMENT HAVING ELECTRICALLY CONTROLLABLE OPTICAL PROPERTIES

Abstract

A composite pane having a functional element having electrically controllable optical properties, includes a stack sequence of an outer pane, a first intermediate layer, a second intermediate layer, and an inner pane, the intermediate layers containing a thermoplastic polymer film having a plasticizer, a functional element having electrically controllable optical properties is arranged, at least in sections, between the first and second intermediate layers, and the functional element is a polymer dispersed liquid crystal functional element and includes a second stack sequence of a first carrier film, an active layer, and a second carrier film. An exit surface of the active layer is sealed, at least in sections, on a lateral surface of the functional element by a barrier layer. The barrier layer substantially prevents the diffusion of plasticizer through the barrier layer, and is produced by a vacuum-based thin-film deposition method.

Claims

1. A composite pane having a functional element having electrically controllable optical properties, comprising: a stack sequence of an outer pane, a first intermediate layer, a second intermediate layer, and an inner pane, wherein the intermediate layers contain at least one thermoplastic polymer film having at least one plasticizer, and a functional element having electrically controllable optical properties is arranged, at least in sections, between the first intermediate layer and the second intermediate layer, and the functional element is a polymer dispersed liquid crystal (PDLC) functional element, wherein the functional element comprises a second stack sequence of at least a first carrier film, an active layer, and a second carrier film, and wherein at least one exit surface of the active layer is sealed, at least in sections, on at least one lateral surface of the functional element by at least one barrier layer, the barrier layer is implemented such that the barrier layer substantially prevents the diffusion of plasticizer through the barrier layer, and the barrier layer is produced by a vacuum-based thin-film deposition method.

2. The composite pane according to claim 1, wherein the vacuum-based thin-film deposition method is one of the following methods: physical vapor deposition (PVD) or atomic layer deposition and/or chemical vapor deposition (CVD).

3. The composite pane according to claim 1, wherein the exit surfaces are completely sealed on all lateral surfaces by the barrier layer or wherein at least one of the lateral surfaces is completely sealed by the barrier layer.

4. The composite pane according to claim 1, wherein the barrier layer is implemented such that the barrier layer prevents the diffusion of plasticizer through the barrier layer to the same extent or to a greater extent than the diffusion of plasticizer through the carrier films.

5. The composite pane according to claim 1, wherein the barrier layer is implemented single-ply from one individual layer or multi-ply from at least two individual layers.

6. The composite pane according to claim 5, wherein the individual layer or at least one individual layer of the barrier layer contains or consists of the following materials: a) metal oxide-based, metal nitride-based, or metal oxynitride-based layers, b) organometallic layers, c) amorphous hydrogenated carbon (a-C:H) and/or d) other ceramic layers and/or polymer layers producible with vapor deposition methods that reduce or substantially prevent the diffusion of plasticizers.

7. The composite pane according to claim 1, wherein the entire barrier layer has, over the exit surface, a thickness d of 10 nm to 5000 nm.

8. The composite pane according to claim 1, wherein the barrier layer is arranged directly on the lateral surface of the stack sequence of the functional element.

9. The composite pane according to claim 1, wherein the barrier layer consists at least of a first individual layer of an organosilicon compound of the type SiO.sub.xC.sub.y:H.sub.z and a second silicon oxide-based individual layer.

10. The composite pane according to claim 1, wherein the intermediate layer contains at least 3 wt.-% of a plasticizer, and the plasticizer contains or consists of aliphatic diesters of tri- or tetraethylene glycol.

11. The composite pane according to claim 1, wherein the intermediate layer contains at least 60 wt.-% polyvinyl butyral (PVB).

12. A method for producing a functional element having electrically controllable optical properties, the method comprising: a) providing a stack sequence of at least a first carrier film, an active layer, and a second carrier film, and b) sealing an exit surface of the active layer, at least in sections, on at least one lateral surface of the functional element by a barrier layer, wherein, the barrier layer is produced by a vacuum-based thin-film deposition method.

13. The method according to claim 12, further comprising the subsequent steps of c) arranging an outer pane, a first intermediate layer, the functional element having electrically controllable optical properties, a second intermediate layer, and an inner pane one above another in this order, and d) joining the outer pane and the inner pane by lamination, wherein an intermediate layer with an embedded functional element is formed from the first intermediate layer and the second intermediate layer.

14. A method comprising utilizing a composite pane according to claim 1 as a windshield or roof panel of a vehicle, wherein the functional element is used as a sun visor.

15. A method comprising utilizing a composite pane according to claim 1 as interior glazing or exterior glazing in a vehicle or a building, wherein the electrically controllable functional element is used as a sun screen or as a privacy screen.

16. The composite pane according to claim 2, wherein the physical vapor deposition is thermal evaporation, electron beam evaporation, laser beam evaporation, ion assisted deposition (IAD), arc evaporation, or magnetron sputtering, the atomic layer deposition is plasma enhanced atomic layer deposition (PEALD), and the chemical vapor deposition (CVD) is plasma enhanced chemical vapor deposition (PECVD).

17. The composite pane according to claim 6, wherein a) in the metal oxide-based, metal nitride-based, or metal oxynitride-based layers, the metal is silicon (Si), aluminum (Al), tantalum (Ta), or vanadium (V) or mixtures thereof, b) the organometallic layers are organosilicon layers of the type SiO.sub.xC.sub.y:H, with x from 0.1 to 3 and y greater than 0.3, c) the amorphous hydrogenated carbon (a-C:H) is amorphous hydrogenated nitrogen-doped carbon (a-C:N:H), or amorphous hydrogenated nitrogen- and silicon-doped carbon (a-C:N:Si:H), and/or d) the other ceramic layers and/or polymer layers are Parylene, polyvinylidene chloride (PVDC), ethylene vinyl alcohol copolymers (EVOP), or polyacrylates.

18. The composite pane according to claim 7, wherein the entire barrier layer has, over the exit surface, a thickness d of 15 nm to 500 nm.

19. The composite pane according to claim 8, wherein the barrier layer is arranged directly on the exit surface of the active layer and/or the lateral surfaces of the carrier films.

20. The composite pane according to claim 9, wherein the first individual layer is arranged directly on the stack sequence of the functional element, and the second individual layer is arranged directly on the first individual layer.

Description

[0163] The invention is explained in detail with reference to drawings and exemplary embodiments. The drawings are schematic representations and not true to scale. The drawings in no way restrict the invention. They depict:

[0164] FIG. 1A a plan view of a first embodiment of a composite pane according to the invention with a functional element according to the invention,

[0165] FIG. 1B a cross-section through the composite pane of FIG. 1A along the section line X-X′,

[0166] FIG. 1C enlarged view of the region Z of FIG. 1B,

[0167] FIG. 1D enlarged view of the region Z′ of FIG. 1C,

[0168] FIG. 1E enlarged view of the region Z″ of FIG. 1C,

[0169] FIG. 2 a schematic representation of an apparatus for depositing a barrier layer according to the invention,

[0170] FIG. 3 a flowchart of an exemplary embodiment of the method according to the invention,

[0171] FIG. 4A a plan view of another embodiment of a composite pane according to the invention using the example of a windshield with a sun visor,

[0172] FIG. 4B a cross-section through the composite pane of FIG. 4A along the section line X-X′.

[0173] FIGS. 1A, 1B, 1C, 1D, and 1E depict in each case a detail of a composite pane according to the invention 100. The composite pane 100 comprises an outer pane 1 and an inner pane 2 joined via a first intermediate layer 3a and a second intermediate layer 3b. The outer pane 1 has a thickness of 2.1 mm and is made, for example, of a clear soda lime glass. The inner pane 2 has a thickness of 1.6 mm and is likewise made, for example, of a clear soda lime glass. The composite pane 100 has a first edge referenced with D that is called the “upper edge” in the following. The composite pane 100 has a second edge referenced with M that is arranged opposite the upper edge D and is called the “lower edge” in the following. The composite pane 100 can be arranged, for example, as architectural glazing in the frame of a window with other panes to form an insulating glazing unit.

[0174] A functional element 5 that is controllable in its optical properties via an electrical voltage is arranged between the first intermediate layer 3a and the second intermediate layer 3b. For the sake of simplicity, the electrical leads are not shown.

[0175] The controllable functional element 5 is, for example, a PDLC multilayer film consisting of a stack sequence with an active layer 11 between two surface electrodes 12, 13 and two carrier films 14, 15. The active layer 11 contains a polymer matrix with liquid crystals dispersed therein that are oriented as a function of the electrical voltage applied on the surface electrodes, by which means the optical properties can be controlled. The carrier films 14, 15 are made of polyethylene terephthalate (PET) and have a thickness of, for example, 0.125 mm. The carrier films 14, 15 are provided with a coating of ITO facing the active layer 11 and having a thickness of approx. 100 nm which form the surface electrodes 12, 13. The surface electrodes 12, 13 can be connected to the vehicle's electrical system via busbars (not shown) (formed, for example, by a silver-containing screen print) and connection cables (not shown).

[0176] The intermediate layers 3a, 3b comprise in each case a thermoplastic film with a thickness of 0.38 mm. The intermediate layers 3a, 3b are made, for example, of 78 wt.-% polyvinyl butyral (PVB) and 20 wt.-% triethylene glycol bis-(2-ethyl hexanoate) as plasticizer.

[0177] The functional element 5 has, on all lateral surfaces 5.1, 5.2, 5.3, 5.4, a barrier layer 4, which covers, for example, the entire lateral surfaces 5.1, 5.2, 5.3, 5.4, the entire area of the upper side (i.e., the surface facing the first intermediate layer 3a) of the functional element 5 and, in sections, the area of the lower side (i.e., the surface facing the second intermediate layer 3b) of the functional element 5. Alternatively, the functional element 5 can be completely coated on its outer surfaces, for example, by changing the holders or by turning the functional element during coating or between two coating steps.

[0178] The barrier layer 4 reduces or prevents diffusion of plasticizer into the active layer 11, thus increasing the service life of the functional element 5. The thickness (or in other words, the material thickness) d of the barrier material 4 over (i.e., orthogonal to) the exit surface 8 is, for example, at least 50 nm.

[0179] FIGS. 1D and 1E depict an exemplary embodiment, in which the barrier layer 4 is implemented in two plies. FIG. 1D depicts an enlarged region Z′ of the upper side of the functional element 5 of FIG. 1C and FIG. 1E the enlarged region of the side edge 5.1 of the functional element 5 with the exit surface 8 of the active layer 11 of FIG. 1C.

[0180] The first individual layer 4.1 of the two-ply barrier layer 4 is arranged directly on the stack sequence of the functional element 5. It consists of an organosilicon layer with a layer thickness d.sub.1 of, for example, 50 nm. The first individual layer 4.1 is arranged on all lateral surfaces 5.1-5.4 of the functional element 5, on the surface of the upper side (i.e., the outside of the first carrier film 14) and, in sections, on the surface of the under side (i.e., on the outside of the second carrier film 15).

[0181] The second individual layer 4.2 of the two-ply barrier layer 4 is arranged directly on the first individual layer 4.1. It is based on silicon oxide and has a layer thickness d.sub.2 of, for example, 100 nm. Here, the total layer thickness d of the barrier layer 4 is, for example, d=d.sub.1+d.sub.2=150 nm.

[0182] The individual layers 4.1,4.2 are deposited on the stack sequence of the functional element 5, for example, with the method described under FIG. 2 and FIG. 3.

[0183] Both the first individual layer 4.1 and the second individual layer 4.2 are transparent and colorless such that they do not impair vision through the functional element 5 and are completely invisible to the human eye.

[0184] In aging tests, such composite panes 100 with a barrier layer 4 according to the invention show significantly reduced brightening in the edge region of the functional element 5, since diffusion of the plasticizer out of the intermediate layers 3a, 3b into the functional element 5 and resultant degradation of the functional element 5 are avoided.

[0185] FIG. 2 depicts an exemplary apparatus for producing a functional element according to the invention 5 and for the exemplary performance of the method according to the invention.

[0186] The apparatus comprises a vapor deposition system 20 using the example of a PECVD system. For this, a cathode 24 and anode 25 are arranged in a vacuum chamber 21. A plasma is ignited within a plasma zone 27 between the cathode 24 and the anode 25 by applying a high-frequency alternating field from a high-frequency generator 22 and matching electronics 23 between cathode the 24 and the anode 25. The vacuum is generated by a vacuum pump 28 connected to a gas outlet 31.

[0187] At the same time, at least one first process gas G.sub.1 is introduced into the plasma zone 27 through at least one first gas inlet 30.1.

[0188] The cathode 24 is, for example, implemented as a spray head cathode. “Spray head cathode” means that the cathode 24 has a large number of holes through which the first process gas G.sub.1 can flow. The cathode 24 is designed such that and connected to the first gas inlet 30.1 such that the first process gas G.sub.1 can flow through the cathode 24 over a wide area into the vacuum chamber 21 and in particular into the plasma zone 27.

[0189] A specimen holder 26 is arranged on the anode 25. The specimen holder 26 consists, for example, of a plate, a ring, multiple rings, a grid, or other suitable shapes.

[0190] The stack sequence of the functional element 5 to be coated is arranged on the specimen holder 26. The specimen holder 26 can, for example, be implemented in the shape of a frame, as a flat surface, or with multiple support points.

[0191] In an advantageous embodiment of a specimen holder 26 according to the invention, the specimen holder is designed such that the functional element 5 protrudes beyond the specimen holder 26 on all sides by an overhang U. This ensures that the entire lateral surfaces 5.1-5.4 are coated on all sides with the barrier material 4. In particular, PECVD methods have particularly good edge covering properties and, consequently, permit particularly good coating of the lateral surfaces 5.1-5.4 that are arranged orthogonally relative to the anode 25.

[0192] If vaporous organic precursor compounds (precursor monomers) are introduced into the plasma zone 27 as the first process gas G.sub.1, these precursor compounds are first activated by the plasma. In addition to the radicals thus formed, ions are also generated in a plasma and together with the radicals cause the deposition of layers on the substrate. The gas temperature in the plasma usually increases only slightly; thus, even temperature-sensitive materials can be coated.

[0193] Depending on the process gas, ionized molecules can develop as result of the activation which form in the gasphase, for example, molecular fragments as clusters or chains. Then, the molecular fragments condense on the substrate (here, on the functional element 5). When a suitable process gas is selected, the molecular fragments can polymerize on the surface under the influence of substrate temperature, electron and ion bombardment and form a closed layer.

[0194] A second process gas G.sub.2 can be introduced into the vacuum chamber 21 via a second gas inlet 30.2. The second gas inlet 30.2 is, for example, implemented as an annular shower. This means that the second gas inlet 30.2 is, for example, routed in a ring shape around the plasma zone 27 such that the second process gas G.sub.2 can flow laterally from all sides into the plasma zone 27 through openings in a ring-shaped tube.

[0195] It goes without saying that only the second process gas G.sub.2 can also be introduced into the vacuum chamber 21, i.e., without the simultaneous introduction of the first process gas G.sub.1.

[0196] HMDSO or TMDSO, for example, can be used as the first process gas G.sub.1, and, optionally, oxygen (O.sub.2), for example, can be used as the second process gas G.sub.2.

[0197] When a process gas G.sub.1 or G.sub.2 that is liquid at room temperature is used, it can be converted into the gas phase using an evaporation unit (not shown).

[0198] FIG. 3 depicts a schematic representation for performing the method according to the invention using the example of a PECVD method.

[0199] An exemplary embodiment of the method according to the invention for producing a functional element according to the invention (5) having electrically controllable optical properties comprises the following steps: [0200] I.) a stack sequence of at least [0201] a first carrier film (15), [0202] an active layer (11), and [0203] a second carrier film (14)  is provided, and [0204] II.) an exit surface (8) of the active layer (11) is sealed, at least in sections, on at least one lateral surface (5.1, 5.2, 5.3, 5.4) of the functional element (5) by a barrier layer (4), wherein the barrier layer (4) is deposited on the functional element (3) with a PECVD method.

[0205] The PECVD method is carried out, for example, in a vacuum chamber 21 of the apparatus depicted in FIG. 2. The energy supply is provided, for example, by multiple magnetrons, operating, for example, at 2.45 GHz, optionally in pulse mode. The standard pressure of the PECVD chamber is, for example, about 5*10.sup.−5 mbar.

[0206] PECVD methods have the particular advantage that the substrates to be coated are heated only slightly, which is particularly advantageous for temperature-sensitive PDLC films.

[0207] In a preferred exemplary embodiment, an individual layer 4.1 is deposited as the barrier layer 4 on the stack sequence of the functional element 5. For the deposition, vaporized HMDSO is introduced into the plasma zone 27 as the first process gas G.sub.1 via the gas inlet 30.1 and the spray head cathode 21. For example, no second process gas G.sub.2 or only an inert process gas G.sub.2 such as argon is supplied.

[0208] The individual layer 4.1 then contains an organosilicon coating of type SiO.sub.xC.sub.y:H. Its stoichiometric composition depends on the deposition conditions, i.e., on the process parameters during layer deposition. The organosilicon coating is preferably highly cross-linked. The organosilicon coating consists, for example, of Si.sub.1O.sub.0.7C.sub.1.7:H.

[0209] In another preferred exemplary embodiment, an alternative individual layer 4.1 is deposited as the barrier layer 4 on the stack sequence of the functional element 5. For the deposition, vaporized HMDSO is introduced into the plasma zone 27 as the first process gas G.sub.1 via the gas inlet 30.1 and the spray head cathode 21. At the same time, oxygen (O.sub.2) is introduced as a second process gas G.sub.2 into the plasma zone 27 via the second gas inlet 30.2 and the annular shower.

[0210] Advantageously, the first process gas G.sub.1 (HMDSO) is introduced at a ratio to the second process gas G.sub.2 (O.sub.2) of preferably G.sub.1:G.sub.2 of 1:5 to 1:20 and, for example, of 1:10.

[0211] As a result of the reaction of the first process gas G.sub.1 of HMDSO with the second process gas G.sub.2 of oxygen, an SiO.sub.x-based individual layer 4.1 is deposited on the stack sequence. In other words, the individual layer 4.1 consists substantially of SiO.sub.x, where, for example, x=1.9 and the individual layer 4.1 moreover contains only small amounts of carbon and hydrogen as organic residue of the organosilicon compound of the first process gases G.sub.1. Preferably, the SiO.sub.x-based individual layer 4.1 contains more than 90 wt.-%.

[0212] The respective layer thicknesses d of the barrier layer 4 and the compositions of the barrier layer 4 can be freely selected by a parameter selection familiar to the person skilled in the art, in particular by the deposition time, within the scope of the method according to the invention.

[0213] In particular, in addition to individual layers 4.1, multi-ply barrier layers 4 with different compositions can also be deposited.

[0214] In another preferred exemplary embodiment, a two-ply barrier layer 4 comprising two individual layers 4.1, 4.2 is deposited, which is depicted by way of example in FIGS. 1C and 1D.

[0215] First, a first individual layer 4.1 of, for example, Si.sub.1O.sub.0.7C.sub.1.7:H is deposited on the stack sequence. For this purpose, as described above, only a first process gas G.sub.1 of HMDSO is introduced into the plasma zone 27.

[0216] Then, an SiO.sub.x-based second individual layer 4.2 is deposited on the first individual layer 4.1. For this purpose, as described above, a first process gas G.sub.1 of HMDSO and a second process gas G.sub.2 of oxygen, for example, at a ratio of 1:10, are introduced into the plasma zone 27.

[0217] In another exemplary embodiment, the surface of the stack sequence can be pretreated before deposition of the barrier layer 4, for example, cleaned, etched, or roughened. The stack sequence can, for example, be exposed to the plasma without process gases or only with oxygen as a process gas. It is thus possible to improve the adhesion of the barrier layer 4 deposited thereon.

[0218] It goes without saying that, by means of the method according to the invention presented here, other multi-ply barrier layers 4 with different material compositions, material combinations, and material permutations can also be deposited. Thus, in a simple manner, different process gases can be fed into the PECVD system and, as a result, barrier layers with different materials can be deposited.

[0219] In particular, by a slow change in the process parameters and, in particular, by a change in the ratio of a first process gas G.sub.1 and a second process gas G.sub.2 during the deposition, gradients in the material composition of the barrier layer 4 can be produced.

[0220] The following table shows the results of an aging test for three exemplary functional elements according to the invention Example 1 to 3 with protective layers 4 according to the invention and a prior art Comparative Example without a protective layer according to the invention.

TABLE-US-00001 Protective layer 4 second Aging first individual layer 4.1 individual layer 4.2 test Example 1 SiO.sub.x-based (100 nm) — Good Example 2 SiO.sub.xC.sub.yH.sub.z (50 nm) — Good Example 3 SiO.sub.xC.sub.yH.sub.z (50 nm) SiO.sub.x-based (100 nm) Very good Comparative — — Poor Example

[0221] The aging test consists of hot storage of the laminated-in, coated functional element for 4 weeks at 90° C.

[0222] Functional elements according to the invention, in which the protective layer 4 consists of a single protective layer 4.1, show, compared to the Comparative Example, significantly improved resistance in the aging test. A two-ply protective layer 4 consisting of a first individual protective layer 4.1 made of organosilicon (SiO.sub.xC.sub.y:H) and a silicon oxide-based second individual layer 4.2 show further improved aging resistance.

[0223] FIG. 4A and FIG. 4B depict in each case a detail of an exemplary composite pane according to the invention 100 as a windshield having an electrically controllable sun visor. The composite pane 100 of FIGS. 4A and 4B corresponds substantially to the composite pane 100 of FIG. 1A-C such that, in the following, only the differences are discussed.

[0224] The windshield comprises a trapezoidal composite pane 100 with an outer pane 1 and an inner pane 2 that are joined to one another via two intermediate layers 3a,3b. The outer pane 1 has a thickness of 2.1 mm and is made of green-colored soda lime glass. The inner pane 2 has a thickness of 1.6 mm and is made of clear soda lime glass. The windshield has an upper edge D facing the roof in the installed position and a lower edge M facing the engine compartment in the installed position.

[0225] The windshield is equipped with an electrically controllable functional element 5 according to the invention as a sun visor that is arranged in a region above the central field of vision B (as defined in ECE-R 43). The sun visor is formed by a commercially available PDLC multilayer film as the functional element 5 that is embedded in the intermediate layers 3a,3b. The height of the sun visor is, for example, 21 cm. The first intermediate layer 3a is bonded to the outer pane 1; the second intermediate layer 3b is bonded to the inner pane 2. A third intermediate layer 3c positioned therebetween has a cutout, into which the cut-to-size PDLC multilayer film is inserted precisely, i.e., flush on all sides. The third intermediate layer 3c thus forms, so to speak, a sort of passe-partout for the functional element 5, which is thus encapsulated all around in a thermoplastic material and is protected thereby.

[0226] The first intermediate layer 3a has a tinted region 6 that is arranged between the functional element 5 and the outer pane 1. The light transmittance of the windshield is thus additionally reduced in the region of the functional element and the milky appearance of the PDLC functional element 5 in the diffuse state is mitigated. The aesthetics of the windshield are thus significantly more attractive. The first intermediate layer 3a has, in the region 6, for example, average light transmittance of 30%, with which good results are achieved.

[0227] The region 6 can be homogeneously tinted. However, it is often visually more appealing if the tinting decreases in the direction of the lower edge of the functional element 5 such that the tinted and the non-tinted regions transition smoothly.

[0228] In the case depicted, the lower edges of the tinted region 6 and the lower edge of the PDLC functional element 5 (here, its lateral surface 5.1) are arranged flush with the barrier layer 4. This is, however, not necessarily the case. It is also possible for the tinted region 6 to protrude beyond the functional element 5 or, vice versa, for the functional element 5 to protrude beyond the tinted region 6. In the latter case, it would not be the entire functional element 5 that would be bonded to the outer pane 1 via the tinted region 6.

[0229] The windshield has, as is customary, a surrounding peripheral masking print 9 that is formed by an opaque enamel on the interior-side surfaces (facing the interior of the vehicle in the installed position) of the outer pane 1 and of the inner pane 2. The distance of the functional element 5 from the upper edge D and the side edges of the windshield is less than the width of the masking print 9 such that the lateral surfaces of the functional element 5—with the exception of the side edge facing the central field of vision B—are concealed by the masking print 9. The electrical connections (not shown) are also reasonably mounted in the region of the masking print 9 and thus hidden.

[0230] The controllable functional element 5 is a multilayer film, consisting of an active layer 11 between two surface electrodes 12, 13 and two carrier films 14, 15. The active layer 11 contains a polymer matrix with liquid crystals dispersed therein, which align themselves as a function of the electrical voltage applied to the surface electrodes, as a result of which the optical properties can be controlled. The carrier films 14, 15 are made of PET and have a thickness of, for example, 0.125 mm. The carrier films 14, 15 are provided with coating of ITO facing the active layer 11 and having a thickness of approx. 100 nm, forming the electrodes 12, 13. The electrodes 12, 13 can be connected to the vehicle's electrical system, via a bus bar (not shown) (formed, for example, by a silver-containing screen print) and via connecting cables (not shown).

[0231] A barrier layer 4 is arranged, for example, on the lateral surfaces 5.1, 5.2, 5.3, and 5.4 of the functional element 5, analogously to FIG. 1C. In the example depicted, all lateral surfaces 5.1, 5.2, 5.3, and 5.4 are completely sealed with the barrier layer 4. Thus, the functional element 5 is particularly well protected against aging.

[0232] A so-called “high flow PVB”, which has stronger flow behavior compared to standard PVB films, can preferably be used for the intermediate layers 3a, 3b, 3c. The layers thus flow around the barrier film 4 and the functional element 5 more strongly, creating a more homogeneous visual impression, and the transition from the functional element 5 to the intermediate layer 3c is less conspicuous. The “high flow PVB” can be used for all or even for only one or more of the intermediate layers 3a, 3b, 3c.

[0233] In another example, not illustrated here, the windshield and the functional element 5 with the barrier layer 4 substantially correspond to the embodiment of FIGS. 4A and 4B. The PDLC functional element 5 is, however, divided by horizontal isolation lines into, for example, six strip-like segments. The isolation lines have, for example, a width of 40 μm to 50 μm and are spaced 3.5 cm apart. They were introduced into the prefabricated multilayer film by laser. The isolation lines separate, in particular, the surface electrodes into strips isolated from one another, which have in each case a separate electrical connection. The segments can thus be switched independently of one another. The thinner the isolation lines, the less conspicuous they are. Even thinner isolation lines can be realized by etching.

[0234] The height of the darkened functional element 5 can be adjusted by the segmentation. Thus, depending on the position of the sun, the driver can darken the entire sun visor or even only part of it.

[0235] In a particularly convenient embodiment, the functional element 5 is controlled by a capacitive switch area arranged in the region of the functional element, wherein the driver determines the degree of darkening by the location at which he touches the pane. Alternatively, the functional element 5 can also be controlled by contactless methods, for example, by gesture recognition, or as a function of the state of the pupil or eyelid determined by a camera and suitable evaluation electronics.

[0236] Another aspect of the invention comprises a functional element (5) having electrically controllable optical properties, comprising

a stack sequence of at least: [0237] a first carrier film (15), [0238] an active layer (11), and [0239] a second carrier film (14),
wherein at least one exit surface (8) of the active layer (11) on at least one lateral surface (5.1, 5.2, 5.3, 5.4) of the functional element (5) is sealed, at least in sections, by at least one barrier layer (4).

[0240] Another aspect of the invention comprises a functional element (5) having electrically controllable optical properties, comprising

a stack sequence of at least: [0241] a first carrier film (15), [0242] an active layer (11), and [0243] a second carrier film (14),
wherein at least one exit surface (8) of the active layer (11) on at least one lateral surface (5.1, 5.2, 5.3, 5.4) of the functional element (5) is sealed, at least in sections, by at least one barrier layer (4), and the barrier layer (4) is formed single ply from one individual layer (4.1) or multi-ply from at least two individual layers (4.1,4.2) ausgebildet ist,
wherein the individual layer (4.1) or at least one individual layer (4.1,4.2) of the barrier layer (4) contains or consists of the following materials:
a) metal oxide-based, metal nitride-based, or metal oxynitride-based layers, wherein the metal is preferably silicon (Si), aluminum (Al), tantalum (Ta), or vanadium (V) or mixtures thereof, preferably sub-stoichiometric or stoichiometric silicon oxide layers,
b) organometallic layers, preferably organosilicon layers of the type SiOxCy:H, preferably with x of 0.1 to 3 and y greater than 0.3,
c) amorphous hydrogenated carbon (a-C:H), preferably amorphous hydrogenated nitrogen-doped carbon (a-C:N:H) or amorphous hydrogenated nitrogen- and silicon-doped carbon (a-C:N:Si:H)
and/or
d) other ceramic layers and/or polymer layers producible with vapor deposition methods, which layers reduce or substantially prevent the diffusion of plasticizers, preferably Parylene, polyvinylidene chloride (PVDC), ethylene vinyl alcohol copolymers (EVOP), or polyacrylates, and preferably the entire barrier layer (4) has over the exit surface (8) a thickness d of 10 nm to 5000 nm (nanometers), particularly preferably of 15 nm to 1000 nm, and most particularly preferably of 15 nm to 500 nm.

[0244] Advantageously, the exit surfaces (8) on all lateral surfaces (5.1, 5.2, 5.3, 5.4) are completely sealed by the barrier layer (4) or at least one of the lateral surfaces (5.1, 5.2, 5.3, 5.4) and preferably all lateral surfaces (5.1, 5.2, 5.3, 5.4) are completely sealed by the barrier layer (4) sealed.

[0245] Advantageously, the functional element (5) is a polymer dispersed liquid crystal (PDLC)-functional element.

LIST OF REFERENCE CHARACTERS

[0246] 1 outer pane [0247] 2 inner pane [0248] 3a first intermediate layer [0249] 3b second intermediate layer [0250] 3c third intermediate layer [0251] 4 barrier layer [0252] 4.1,4.2 individual layer of the barrier layer 4 [0253] 5 functional element having electrically controllable optical properties [0254] 5.1,5.2,5.3,5.4 lateral surface of the functional element 5 [0255] 6 tinted region of the first intermediate layer 3a [0256] 8 exit surface of the active layer 11 [0257] 9 masking print [0258] 11 active layer of the functional element 5 [0259] 12 surface electrode of the functional element 5 [0260] 13 surface electrode of the functional element 5 [0261] 14 carrier film [0262] 15 carrier film [0263] 20 vapor deposition system [0264] 21 vacuum chamber [0265] 22 high-frequency generator [0266] 23 adaptation electronics [0267] 24 cathode [0268] 25 anode [0269] 26 specimen holder [0270] 27 plasma zone [0271] 28 vacuum pump [0272] 30.1 first gas inlet [0273] 30.2 second gas inlet [0274] 31 gas outlet [0275] 100 composite pane [0276] B central field of vision of the windshield [0277] D upper edge of the windshield, roof edge [0278] d thickness, material thickness [0279] G.sub.1 first process gas [0280] G.sub.2 second process gas [0281] M lower edge of the windshield, engine edge [0282] U overhang [0283] X-X′ section line [0284] Z, Z′,Z″ enlarged region