Laminated pane having an electrically switchable mirror element and reduced light transmittance

Abstract

The invention relates to a laminated pane (1) for separating an interior from an outer environment, comprising an outer pane (2) and an inner pane (3) which are rigidly interconnected by at least one thermoplastic intermediate layer (4, 4', 4''), wherein the outer pane (2) and the inner pane (3) each have a surface facing the outer environment and a surface facing the interior, wherein an electrically switchable mirror element (6, 13) is disposed between the outer pane and the inner pane, and wherein the laminated pane is designed such that it has a light transmittance of more than 70% in a first region (7) on the side of the mirror element (6, 13) facing the outer environment, and a light transmittance of at most 70% in a second region (8) on the side of the mirror element (6, 13) facing the interior.

Description

[0001] Composite pane with electrically switchable mirror element and reduced light transmission

[0002] The present invention lies in the technical field of pane manufacturing and relates to a composite pane with an electrically switchable mirror element and reduced light transmission. The invention further extends to the use of the composite pane according to the invention.

[0003] The interior of a motor vehicle or building can heat up considerably in summer due to high ambient temperatures and intense direct sunlight. In order to reduce CO2 emissions, reducing the heat generated by direct sunlight in a vehicle or building is desirable, as this can save energy required for cooling the interior. In electric vehicles, this energy saving can also increase the range. Infrared radiation and radiation in the visible wavelength range (light) are primarily responsible for heating the interior.

[0004] To counteract this problem, windows with emissivity-reducing coatings, also known as low-E coatings, which have reflective properties against thermal radiation, are known. At high outside temperatures, the emissivity-reducing coating prevents the thermal radiation emanating from the heated window from entering the interior. In addition, some of the solar infrared radiation is reflected. At low outside temperatures, the coating reduces heat transfer from the heated interior via the window into the outside environment. Overall, thermal comfort is improved by such a window with reduced emissivity. Windows with emissivity-reducing coatings are used in the automotive sector, particularly as roof windows. Suitable emissivity-reducing coatings are known, for example, from EP2141135A1, WO2011 / 105991 A1, WO2013 / 131667 A1 and WO2018 / 206236 A1.

[0005] Silver-based coatings are also used to reflect IR radiation, particularly in the near-infrared range. For example, in laminated glass, silver-based coatings are applied in combination to the interior surface (side II) of the outer pane and emissivity-reducing coatings to the interior surface (side IV) of the inner pane.

[0006] These measures allow IR radiation hitting the laminated glass to be reflected and blocked, thereby reducing the energy input into the interior.

[0007] In addition to IR radiation, radiation in the visible wavelength range (i.e. light) also has a significant influence on the energy input into the interior. This is often unavoidable, as a minimum level of transparency of the window for light may be desired or required by law. As is well known, around 44% of the energy input into an interior can be caused by visible light. Tinted thermoplastic interlayers and / or tinted windows are used to reduce light transmission. However, tinted interlayers and tinted windows can heat up considerably due to solar radiation and thus increase the energy input into an interior through the emitted thermal radiation. As practice has shown, tinted elements can sometimes become so hot that contact with a body part can cause burns.To improve the light-reflecting properties of laminated panes, it would also be possible to use electrically switchable, light-reflecting functional films.

[0008] In general, emissivity-reducing coatings have the disadvantage that they cause the windshield to reflect a certain amount of light from the interior, especially at shallow reflection angles. This can lead to distracting effects. For example, the display of the navigation system or other electronic displays can be reflected on the roof window, which can be distracting for passengers in the back seat. The same naturally applies to light-reflecting functional films.

[0009] DE 1596815 A1, JP 2006106343 A and JP 2006267670 A each show a composite pane with an electrically switchable mirror element.

[0010] In contrast, the object of the present invention is to avoid the aforementioned disadvantages and to provide an improved composite pane that reduces the energy input into the interior and also results in lower light reflection from the interior. Furthermore, the composite pane should be able to be produced using a cost-effective, industrially applicable process, while being of high quality and long-term stability. These and other objects are achieved according to the invention by a composite pane with the features of the independent patent claim. Preferred embodiments are evident from the subclaims.

[0011] The invention shows a composite pane which is intended to be installed in an opening of a vehicle or building and serves to separate an interior space from an external environment.

[0012] The composite pane comprises an outer pane with a surface facing the external environment (side I) and a surface facing the interior (side II), as well as an inner pane with a surface facing the external environment (side III) and a surface facing the interior (side VI). The outer pane and the inner pane are firmly connected to one another by at least one thermoplastic intermediate layer. Furthermore, the composite pane has an electrically switchable mirror element with light-reflecting properties between the outer pane and the inner pane, by means of which mirror element incident on the composite pane from the external environment, i.e. radiation in the visible wavelength range, can be reflected.The mirror element can typically also reflect light incident from the interior onto the composite pane, whereby, according to the invention, the incidence of light from the external environment is essential to reducing the energy input into the interior. The mirror element is suitable and intended to reflect light incident from the external environment onto the mirror element. In other words, the mirror element serves to reflect light incident from the external environment onto the mirror element. The subject matter of the invention therefore relates to a composite pane with an electrically switchable mirror element for reflecting light incident from the external environment.

[0013] The composite pane can be divided by the electrically switchable mirror element into a first region containing the outer pane on the side of the mirror element facing the outside environment, and a second region containing the inner pane on the side of the mirror element facing the interior space. The designation of the two regions of the composite pane as "first region" and "second region" serves merely to simplify differentiation. The first region can also be referred to as the outer region, and the second region as the inner region of the composite pane. The first region comprises all components of the composite pane on the side of the mirror element facing the outside environment, with the exception of an opaque masking layer (black print). Similarly, the second region comprises all components of the composite pane on the side of the mirror element facing the interior space.

[0014] The composite pane according to the invention is generally designed to have a light transmission of more than 70% in the first region and a light transmission of a maximum of 70% in the second region. For the light transmission, all components of the composite pane in the first region and second region, respectively, must be taken into account, i.e., the light transmission in the first region is the combined light transmission of all components of the composite pane in the first region, and the light transmission in the second region is the combined light transmission of all components of the composite pane in the second region.Accordingly, the composite pane has different light transmissions on both sides of the electrically switchable mirror element, wherein in the second region of the composite pane on the side of the mirror element facing the interior, the light transmission is lower than in the first region of the composite pane on the side of the mirror element facing the external environment.

[0015] Means for reducing light transmission in a laminated pane are known to the person skilled in the art.

[0016] In one embodiment, the composite pane has a tinted (colored) thermoplastic intermediate layer and / or a tinted (colored) inner pane and / or a (dark) transmission-reducing coating produced by deposition in the second region to reduce light transmission. The transmission-reducing coating is preferably deposited on the inner pane.

[0017] In one embodiment, the composite pane has a non-tinted outer pane and / or a non-tinted thermoplastic intermediate layer in the first region. Advantageously, the outer pane and / or a thermoplastic intermediate layer in the first region are clear, i.e., non-tinted or uncolored. In an alternative embodiment, the composite pane has a tinted outer pane and / or a tinted thermoplastic intermediate layer in the first region. The tinted outer pane and / or the tinted thermoplastic intermediate layer can, for example, have a lower tint in the first region than the inner pane and / or the thermoplastic intermediate layer in the second region.

[0018] The invention advantageously allows the energy input into the interior in the visible wavelength range to be reduced by the electrically switchable mirror element. Furthermore, the reduced light transmission in the second region of the composite pane on the side of the mirror element facing the interior prevents unwanted light reflections from the interior. These are major advantages of the composite pane according to the invention.

[0019] In one embodiment of the invention, the composite pane is designed such that it has a light transmission of more than 80% in the first region and, at the same time, a light transmission of a maximum of 50%, preferably a maximum of 30%, and particularly preferably a maximum of 10%, in the second region. This measure allows for particularly effective light reflection of light incident from outside, while also allowing for particularly effective prevention of interior light reflections due to the significantly reduced light transmission in the second region.

[0020] In one embodiment of the invention, the composite pane is designed to have a total light transmission (TL) of a maximum of 65%, preferably a maximum of 50%, particularly preferably a maximum of 30%, and most particularly preferably a maximum of 15%. For example, a dark roof pane with TL = 7% + IR-reflective (Ag) layer + LowE layer on side IV has a TTS of approximately 12-13% (without reflection in the visible range). TTS (Total Transferred Solar Energy) refers to the heat input by radiation at visible and non-visible wavelengths.

[0021] The electrically switchable mirror element is flat and extends over a substantial part of the surface of the composite pane, for example at least 35%, at least 40%, at least 60%, at least 70%, at least 80% or at least 90% of the surface of the composite pane.

[0022] The electrically switchable mirror element is designed such that it can be switched into a (light) non-reflective state or a (light) reflective state by applying a corresponding operating voltage. Advantageously, the electrically switchable mirror element is designed such that at least 35%, at least 40%, at least 50%, at least 60%, at least 70%, at least 80%, or at least 90% of the incident (visible) light is reflected. For the purposes of the present invention, a "reflective state" is also understood to mean a semi-reflective state in which only a portion of the incident visible light is reflected.

[0023] Electrically switchable mirror elements are known per se to those skilled in the art. In one embodiment of the invention, the electrically switchable mirror element is a prefabricated electrically switchable functional element (no coating) which is designed such that it can be electrically switched into a (light) non-reflective state or a (light) reflective state by applying an appropriate operating voltage. Such electrically switchable functional elements are typically in film form and can be easily laminated into a composite pane. The electrically switchable functional element or functional film can, for example, be arranged in a thermoplastic film which surrounds the functional element in a frame-like manner, like a passe-partout, in order to avoid local height differences in the laminate and undesired forces acting on the electrically switchable functional element.Prefabricated electrically switchable functional elements based on liquid crystals in film form are commercially available (e.g. from Kent Optronics).

[0024] In one embodiment of the invention, the electrically switchable functional element is arranged in film form between a thermoplastic intermediate layer in the first region and a thermoplastic intermediate layer in the second region, wherein the thermoplastic intermediate layer in the second region has a tint. Advantageously, the thermoplastic intermediate layer in the first region has no tint or at least a lesser tint than the thermoplastic intermediate layer in the second region. Thus, the electrically switchable functional element is embedded between two thermoplastic intermediate layers of different tints, wherein the electrically switchable functional element can additionally be arranged in a frame-like surrounding thermoplastic intermediate layer.This measure has the advantage that the thermoplastic intermediate layer used to laminate the electrically switchable functional element in the second region is simultaneously used to reduce the light transmission in the second region. In addition, the inner pane can have a tint, while the outer pane is clear or at least has a lesser tint than the inner pane. In one embodiment of the invention, the electrically switchable mirror element is in the form of an electrically switchable functional coating which is designed such that it can be switched into a (light) non-reflective state or a (light) reflective state by applying an appropriate operating voltage. Such electrically switchable functional coatings are known in the art (see, for example, AIST, Japan) and are based, for example, on an Mg-Ni alloy as the electrically switchable mirror layer.

[0025] The electrically switchable functional coating is preferably applied to the inner pane by deposition, preferably to the surface of the inner pane facing the exterior (side III). A (dark) transmission-reducing coating is preferably applied to the interior side of the electrically switchable functional coating. The electrically switchable functional coating is preferably arranged on the transmission-reducing coating. The transmission-reducing coating is preferably deposited on the surface of the inner pane facing the exterior (side III), and the electrically switchable functional coating is deposited on the transmission-reducing coating.

[0026] The transmission-reducing coating is based, for example, on titanium nitride and / or titanium carbide or is an amorphous carbon layer.

[0027] The transmission-reducing coating is typically applied over the entire surface of the inner pane, possibly with the exception of a peripheral edge area and / or other locally limited areas that may be used, for example, for data transmission. The coated portion of the inner pane's surface is preferably at least 90%.

[0028] In one embodiment, an emissivity-reducing coating is applied to the inner pane, preferably on the surface of the inner pane facing the interior (side IV). This advantageously reduces the energy input into the interior due to IR radiation. The emissivity-reducing coating can also be referred to as a heat radiation-reflecting coating or low-E coating. Emissivity is the measure that indicates how much heat radiation the pane emits into an interior in the installed position compared to an ideal heat radiator (i.e. a blackbody). The emissivity-reducing coating has the function of preventing heat from radiating into the interior (IR components of solar radiation and in particular the thermal radiation of the composite pane itself) and also preventing heat from radiating out of the interior.It has reflective properties against infrared radiation, especially against thermal radiation in the spectral range of 5 - 50 pm (cf. standard DIN EN 12898:2019-06).

[0029] Advantageously, the emissivity-reducing coating contains at least one layer of a transparent conductive oxide (TCO), for example based on indium tin oxide (ITO), indium zinc mixed oxide (IZO), aluminum-doped zinc oxide (AZO), gallium-doped zinc oxide (GZO), fluorine-doped tin oxide (FTO, SnO2:F) or antimony-doped tin oxide (ATO, SnO2:Sb).

[0030] The emissivity-reducing coating is typically applied over the entire surface of the inner pane, possibly with the exception of a peripheral edge area and / or other locally limited areas that may serve, for example, for data transmission. The coated portion of the inner pane's surface is preferably at least 90%.

[0031] Additionally or alternatively, an IR-reflecting coating is preferably applied to the surface of the outer pane facing the interior, whereby the energy input into the interior can be (further) reduced.

[0032] In the composite pane according to the invention, the light transmission in the second region of the composite pane is lower than in the first region. "Light" is understood to mean the visible spectral range from 380 nm to 780 nm.

[0033] The total light transmittance (TL) of the laminated pane and the reflected light fraction are measured in accordance with DIN ISO 5033 (old standard) and DIN EN ISO / CIE 11664 (new standard). The transmitted light fraction is determined in transmitted light, and the reflected light fraction is determined in viewed light. A standard light source (e.g. light source A, D65) is used under conditions specified in the standard, whereby the quotient of the intensity of the transmitted light to the intensity of the incident light is determined to determine the percentage of transmission. The light source is placed on one side of the laminated pane and a light sensor on the other side of the laminated pane. To determine the percentage of reflection, the quotient of the intensity of the reflected light to the intensity of the incident light is determined.Here, the light source and the light sensor are arranged on the same side of the composite pane. The light transmission of the first and second areas of the composite pane is determined in a similar manner, with the first and second areas of the composite pane being examined separately instead of the composite pane.

[0034] The first pane and the second pane of the composite pane can, in principle, have any chemical composition known to those skilled in the art. The two panes preferably contain or consist of glass, particularly preferably flat glass, float glass, quartz glass, borosilicate glass, soda-lime glass, or aluminosilicate glass. It is also conceivable for the two panes to contain or consist of a clear plastic, preferably a rigid clear plastic, in particular polyethylene, polypropylene, polycarbonate, polymethyl methacrylate, polystyrene, polyamide, polyester, polyvinyl chloride, and / or mixtures thereof.

[0035] In one embodiment of the invention, the laminated pane contains or consists of glass. The thickness of each individual pane of the laminated pane can vary widely and be adapted to the requirements of the individual case. Preferably, panes with standard thicknesses of 0.5 mm to 25 mm are used, and more preferably, 0.5 mm to 5 mm. The size of the panes can vary widely and depends on their use. The laminated pane can have any three-dimensional shape and can be planar or curved in one or more spatial directions.

[0036] The two panes of the composite pane are firmly bonded together by at least one thermoplastic intermediate layer, which is created by lamination of the two panes with one or more adhesive films. Each adhesive film preferably contains or consists of polyvinyl butyral (PVB), ethylene-vinyl acetate (EVA), thermoplastic polyurethane (TPU), polyethylene terephthalate (PET), or mixtures or copolymers or derivatives thereof, particularly preferably PVB. The thickness of an adhesive film is preferably between 0.2 mm and 1 mm, for example 0.38 mm or 0.76 mm.

[0037] Known processes for laminating composite panes can be used. Vacuum lamination is particularly well-known and common. This process takes place in a heatable and evacuatable chamber for, for example, around 60 minutes at a reduced pressure of, for example, 0.01 mbar to 800 mbar and temperatures of, for example, 80°C to 170°C. Known vacuum bag or vacuum ring processes operate, for example, at around 200 mbar and, for example, 130°C to 145°C. In roller lamination, pressing takes place in a calender between at least one pair of rollers or one roller and a solid base. The temperature during the pressing process is, for example, between 40°C and 150°C. This is well known in the art and therefore need not be discussed in detail here.

[0038] The invention also extends to the use of the composite pane according to the invention in buildings or in means of transport for traffic on land, in the air or on water, in particular in motor vehicles, for example as a roof pane, rear window and / or side window.

[0039] The various embodiments of the invention can be implemented individually or in any combination. In particular, the features mentioned above and explained below can be used not only in the specified combinations, but also in other combinations or on their own, without departing from the scope of the present invention.

[0040] The invention is explained in more detail below using exemplary embodiments, with reference to the accompanying figures. They show, in simplified form and not to scale:

[0041] Fig. 1 is a schematic cross-sectional view of a first embodiment of the composite pane according to the invention,

[0042] Fig. 2 is a schematic cross-sectional view of a second embodiment of the composite pane according to the invention.

[0043] Two different embodiments of the composite pane according to the invention, which is designated overall by the reference number 1, are explained with reference to Figures 1 and 2.

[0044] Consider Figure 1 first. Figure 1 illustrates, in a schematic cross-sectional view, a first embodiment of the composite pane 1, which is intended to be inserted into an opening of a motor vehicle or building, where it separates an interior space INT from the exterior environment AMB. The composite pane 1 is, for example, the roof pane of a motor vehicle.

[0045] The composite pane 1 comprises an outer pane 2 and an inner pane 3, which are firmly connected to one another via three thermoplastic intermediate layers 4, 4', 4". The outer pane 2 has a surface I facing the outside environment and a surface II facing the interior. Likewise, the inner pane 3 has a surface III facing the outside space and a surface IV facing the interior space. The outside surface I of the outer pane 2 and the interior surface IV of the inner pane are the exposed surfaces of the composite pane, with surface I facing the outside environment in the installed position and surface IV facing the interior of the vehicle or building. The outer pane 2 and the inner pane 3 are, for example, panes made of soda-lime glass, each with a thickness of 2.1 mm. The outer pane 2 is preferably not tinted.However, situations may also arise where a tinted outer pane 2 is advantageous, namely when the external reflection of light is visually unappealing. While this is disadvantageous with regard to thermal insulation (TTS), it represents a good compromise between reflectivity and thermal insulation. The intermediate layers 4, 4', 4" are formed, for example, by polyvinyl butyral (PVB) films.

[0046] An emissivity-reducing coating 5 (low-E coating) is applied to the exposed, interior-side surface IV of the inner pane 3. The emissivity-reducing coating 5 improves thermal comfort in the interior by reflecting heat radiation from the pane and solar radiation at high outside temperatures and by reducing the cooling of the interior at low outside temperatures. The emissivity-reducing coating 5 is based on ITO, for example.

[0047] The composite pane 1 contains, between the outer pane 2 and the inner pane 3, an electrically switchable mirror element in the form of an electrically switchable functional film 6 based on liquid crystals, which can be switched into a light-reflecting or light-reflecting state by applying a suitable operating voltage. The electrically switchable functional film 6 allows the composite pane to be divided, at least conceptually, into a first region 7 and a second region 8, with the first region 7 being located on the side of the electrically switchable functional film 6 facing the outside environment, and the second region 8 being located on the side of the electrically switchable functional film 6 facing the interior.

[0048] The electrically switchable functional film 6 is embedded between the two thermoplastic intermediate layers 4, 4', wherein the electrically switchable functional film 6 is additionally surrounded by a thermoplastic intermediate layer 4" in the manner of a passe-partout. For this purpose, the electrically switchable functional film 6 is inserted into an opening or perforation of the surrounding intermediate layer 4" (intermediate film). It is understood that the thermoplastic intermediate layers 4, 4', 4" fuse during lamination. These are provided in film form in the usual way before lamination. The electrically switchable functional film 6 has two connection electrodes (busbars) 10, through which an operating voltage for switching the functional film can be applied.

[0049] The thermoplastic intermediate layer 4 is located in the first region 7, the thermoplastic intermediate layer 4' in the second region 8.

[0050] Between the electrically switchable functional film 6 and the material of the thermoplastic intermediate layers 4, 4', 4" there is sealing material 11, which prevents diffusion processes.

[0051] Furthermore, the composite pane 1 comprises an IR-reflecting coating 9, which is based on silver, for example, on the interior surface II of the outer pane 2. Stripped or uncoated areas are possible to allow the passage of radio signals.

[0052] The composite pane 1 has a maximum light transmission of 70% in the second region 8 and a light transmission of more than 70% in the first region 7, i.e. the light transmission in the second region 8 is lower than the light transmission in the first region 7. This is achieved by a correspondingly strong tinting of the thermoplastic intermediate layer 4' in the second region 8. The thermoplastic intermediate layer 4 in the first region 7, on the other hand, is not tinted (clear) or has at least a lower tint than the thermoplastic intermediate layer 4' in the second region 8. It would also be possible for the inner pane 3 to additionally or alternatively have a corresponding tint. The outer pane 2 is clear and has no tint. The composite pane 1 is further provided with a black print 12 on the interior-side surface II of the outer pane 2, by means of which connections, sealing material and the like located underneath are concealed.

[0053] Figure 2 illustrates a second embodiment of the composite pane 1 according to the invention using a schematic cross-sectional view. To avoid unnecessary repetition, only the differences from the first embodiment explained in connection with Figure 1 are described, and otherwise reference is made to the above explanations.

[0054] Accordingly, instead of the electrically switchable functional film 6, an electrically switchable functional coating 13 is provided on the inner pane 3. The electrically switchable functional coating 13 is deposited on the surface III of the inner pane 3 facing the external environment, for example by sputtering. Between the electrically switchable functional coating 13 and the inner pane 3 there is a transmission-reducing coating 14, which is based, for example, on titanium nitride and / or titanium carbide or is an amorphous carbon layer. During production, the transmission-reducing coating 14 is first deposited on the surface III of the inner pane 3 facing the external environment, for example by sputtering, followed by a deposition of the electrically switchable functional coating 13 on the transmission-reducing coating 14, for example by sputtering.Analogous to the electrically switchable functional film 6, the electrically switchable functional coating 13 can be switched into a light-non-reflecting state or into a light-reflecting state by applying a suitable operating voltage.

[0055] In the embodiment of Figure 2, the outer pane 2 and the inner pane 3 are connected to each other only by a clear (non-tinted) intermediate layer 4.

[0056] The composite pane 1 has a maximum light transmission of 70% in the second region 8 and a light transmission of more than 70% in the first region 7, i.e. the light transmission in the second region 8 is lower than the light transmission in the first region 7. This is achieved by the transmission-reducing coating 14. Alternatively or additionally, the inner pane 3 can have a corresponding tint. The composite pane 1 of the exemplary embodiments in Figures 1 and 2 can optionally be brought into a state with light-reflective properties, wherein the first region 7 has a lower tint than the second region 8, such that a relatively large proportion of the incident sunlight is reflected. Undesirable reflections on the interior side can be avoided by the strong transmission reduction in the second region 8.

[0057] The total heat input from radiation in the visible and non-visible wavelength range (TTS) of the composite pane 1 is approximately 6%, which corresponds to a reduction of approximately 50% compared to conventional roof windows. The electrically switchable functional film 6 and the electrically switchable functional coating 13 can be designed in segmented configurations.

[0058] From the above, it can be seen that the invention provides a novel composite pane that reduces the energy input into the interior of a motor vehicle or building through strong reflection of visible light and also avoids adverse effects related to interior reflections. The composite pane can be easily manufactured using standard processes in the industrial series production of composite panes. The composite pane can be produced simply, cost-effectively, and with high quality.

[0059] List of reference symbols

[0060] 1 composite pane

[0061] 2 outer pane

[0062] 3 inner pane

[0063] 4, 4', 4" intermediate layer

[0064] 5 emissivity-reducing coating

[0065] 6 Functional film

[0066] 7 first area

[0067] 8 second area

[0068] 9 IR-reflective coating

[0069] 10 Connection electrode

[0070] 11 Sealing material

[0071] 12 Black printing

[0072] 13 Functional coating

[0073] 14 transmission-reducing coating

[0074] INT interior

[0075] AMB external environment

Claims

Patent claims 1. Composite pane (1) for separating an interior space from an external environment, comprising an outer pane (2) and an inner pane (3) which are firmly connected to one another by at least one thermoplastic intermediate layer (4, 4', 4"), wherein the outer pane (2) and the inner pane (3) each have a surface facing the external environment and a surface facing the interior space, wherein an electrically switchable mirror element (6, 13) is arranged between the outer pane (2) and the inner pane (3), wherein the composite pane is designed such that it (7) on the side of the mirror element (6, 13) facing the external environment has a light transmission of more than 70% and in a second region (8) on the side of the mirror element (6, 13) facing the interior has a light transmission of a maximum of 70%.

2. Composite pane (1) according to claim 1, which is designed such that it has a light transmission of more than 80% in the first region (7) and a light transmission of a maximum of 50%, a maximum of 30% or a maximum of 10% in the second region (8).

3. Composite pane (1) according to one of claims 1 or 2, which in the second region (8) has a tinted inner pane (3), a tinted thermoplastic intermediate layer (4') and / or a transmission-reducing coating (14).

4. Composite pane (1) according to one of claims 1 to 3, which i) has a non-tinted outer pane (2) and / or a non-tinted thermoplastic intermediate layer (4) in the first region (7), or ii) has a tinted outer pane (2) and / or a tinted thermoplastic intermediate layer (4) in the first region (7).

5. Composite pane (1) according to one of claims 1 to 4, which has a total light transmission (TL) of at most 65%, preferably of at most 50%, particularly preferably of at most 30%, and most particularly preferably of at most 15%.

6. Composite pane (1) according to one of claims 1 to 5, wherein the electrically switchable mirror element (6, 13) reflects at least 35%, at least 40%, at least 50%, at least 60%, at least 70%, at least 80%, or at least 90% of the incident light.

7. Composite pane (1) according to one of claims 1 to 6, wherein the electrically switchable mirror element is an electrically switchable functional film (6) which can be switched into a non-light-reflecting state or into a light-reflecting state.

8. Composite pane (1) according to claim 7, wherein the electrically switchable functional film (6) is arranged between a thermoplastic intermediate layer (4) in the first region (7) and a thermoplastic intermediate layer (4') in the second region (8), wherein the thermoplastic intermediate layer (4') in the second region (8) has a tint.

9. Composite pane (1) according to claim 8, wherein the thermoplastic intermediate layer (4) in the first region (7) has no tint or a lesser tint than the thermoplastic intermediate layer (4') in the second region (8).

10. Composite pane (1) according to one of claims 1 to 6, wherein the electrically switchable mirror element is an electrically switchable functional coating (13) which can be switched into a non-light-reflecting state or into a light-reflecting state.

11. Composite pane (1) according to claim 10, in which a transmission-reducing coating (14) is applied to the interior side of the electrically switchable functional coating (13).

12. Composite pane (1) according to claim 11, wherein the electrically switchable functional coating (13) is arranged on the transmission-reducing coating (14).

13. Composite pane (1) according to claim 11 or 12, wherein the transmission-reducing coating is based on titanium nitride and / or titanium carbide or is an amorphous carbon layer.

14. Composite pane (1) according to one of claims 1 to 13, in which an emissivity-reducing coating (5) is applied to the surface (IV) of the inner pane (3) facing the interior and / or an IR-reflecting coating is applied to the surface (II) of the outer pane (2) facing the interior.

15. Use of the composite pane (1) according to one of claims 1 to 14 in buildings or in means of transport for traffic on land, in the air or on water, in particular in motor vehicles, for example as a roof pane, rear window and / or side window.

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