System for illuminating optical structures in an at least partially transparent material

Abstract

The invention relates to a system comprising an illumination device and a component having a surface coating made of a material which is at least partially transparent and has structures incorporated in its inner volume following production of the material, said structures changing the volume with respect to its optical properties in relation to the non-structured volume. The system according to the invention is characterized in that the structure comprises modification bubbles which are formed in a uniform periodic or random arrangement in at least one plane in the volume, wherein the illumination device is arranged relative to the component such that it illuminates a visible side of the surface coating of the component. The invention also relates to a method for controlling the illumination in such a system and to a vehicle having such a system.

Description

[0001] P 2023-02844WO / 2023PF02404 / ILT - 2021 F66480 / Mercedes-Benz Group AG, Fraunhofer Society for the Advancement of Applied Research e. ​​V. / System and method for the periodic volume structuring of Klarlaok / ST / PM / 20250354393 / 10 December 2025

[0002] 1

[0003] System for illuminating optical structures in a material that is at least partially transparent

[0004] The invention relates to a system comprising a lighting device and a component with a surface coating made of an at least partially transparent material, which has structures introduced into its internal volume after material production that modify the volume with respect to its optical properties compared to the unstructured volume. The invention further relates to a method for controlling the lighting in such a system. The invention also relates to a vehicle with such a system.

[0005] For the state of the art, reference can be made to DE 10 2008 021 658 A1.

[0006] This describes volume modulation using a laser within a emitting body surrounding a light-emitting diode. This allows for the creation of a diffuser within the transparent part of the LED's housing, thereby increasing the LED's luminous efficacy. The structure is simply a diffuser and does not require any graphic representation.

[0007] Other materials that can be structured – for example, using laser beams – are also known from the prior art.

[0008] WO 2015 / 044168 A1 describes in its introductory section as state of the art transparent materials made of glass or glass-ceramics in which microcracks are created within the volume using a laser beam. These microcracks scatter the light, so that, with a suitable arrangement of the microcracks within the material's internal volume, three-dimensional images can be generated. WO 2015 / 044168 A1 further develops this fundamentally known process by using a laser beam to non-destructively modify the optical properties of the material in order to improve transmission. P 2023-02844WO / 2023PF02404 / ILT - 2021 F66480 / Mercedes-Benz Group AG, Fraunhofer Society for the Advancement of Applied Research e. ​​V. / System and method for the periodic volume structuring of Klarlaok / ST / PM / 20250354393 / 10 December 2025

[0009] 2. to lower remission and increase absorption coefficients. This allows the material properties to be adjusted to achieve an image quality that goes beyond simply generating microcracks.

[0010] Furthermore, reference can be made to DE 197 12 035 A1, which uses a light source and a diffuser to produce aesthetic light effects.

[0011] This includes smelted and crushed alkali silicates.

[0012] DE 10 2019 131 856 A1 describes the use of optical gratings under a translucent layer in a vehicle.

[0013] From WO 2015 / 188 908 A1, a safety element is known which uses randomized structures in the submicrometer range to achieve an angle-independent optical effect.

[0014] DE 10 2015 004 163 A1 deals with the determination of the properties of a laser beam.

[0015] From DE 20 2019 100 692 LI1, an illuminated plate with a diffraction grating in a vehicle is known.

[0016] German patent DE 10 2017 127 447 A1 describes a translucent polymer plaque. Iridescent patterns are generated using a grating and lateral illumination. German patent DE 20 2017 102 707 LI1 also describes an iridescent plaque that incorporates a diffraction grating.

[0017] DE 20 2016 105 622 LH describes a badge with a photoluminescent layer that emits light when stimulated by illumination. P 2023-02844WO / 2023PF02404 / ILT - 2021 F66480 / Mercedes-Benz Group AG, Fraunhofer Society for the Advancement of Applied Research e. ​​V. / System and method for the periodic volume structuring of clear liquid / ST / PM / 20250354393 / 10 December 2025

[0018] 3

[0019] Furthermore, a holographic lighting device for vehicles is known from DE 10 2022 131 471 A1.

[0020] From the two unpublished earlier German patent applications with file numbers 10 2024 138 585.5 and 10 2024 138 590.1, filed by the same applicants, it is known to provide materials, such as surface coatings or varnishes, with optical structures that enable graphic representation and color changes. For this purpose, modification bubbles are formed in the material in a uniform, periodic, or random arrangement in at least one plane within the volume. This allows, for example, the creation of iridescent colors in the case of periodic structures spaced on the order of the wavelength of visible light. The structures function in the manner of an optical grating.

[0021] The color intensity and brilliance of an iridescent effect based on in-volume structuring within the material can, in principle, be custom-tuned by defining specific lighting characteristics, taking into account the preferred viewing angle (e.g., the line of sight in automotive engineering) and the angle of incidence of the light. Iridescent structures exhibit their brilliance primarily at higher light intensities and at specific angles between the light source, the structure, and the viewer (or eye). Consequently, these iridescent structures are sometimes barely visible, or do not exhibit any iridescence, under poor lighting conditions, such as at night, on a dark day, or at an unsuitable angle to the sun. Other design elements that do not exhibit iridescence are also difficult to see in low light.

[0022] The object of the present invention is to create a system for improving the perception of such optical structures. P 2023-02844WO / 2023PF02404 / ILT - 2021 F66480 / Mercedes-Benz Group AG, Fraunhofer Society for the Advancement of Applied Research e. ​​V. / System and method for the periodic volume structuring of clear liquids / ST / PM / 20250354393 / 10 December 2025

[0023] 4

[0024] According to the invention, this problem is solved by a system with the features of claim 1, and in particular in the characterizing part of claim 1. Advantageous embodiments of the system according to the invention are described in the dependent claims. Furthermore, a method for controlling the lighting in such a system according to claim 10 solves the problem. Advantageous further developments of the method are described in the dependent claims. Finally, a vehicle with such a system according to claim 13 also solves the problem. Advantageous embodiments of this vehicle are also described in the dependent claims.

[0025] The system comprises a lighting device and a component with a surface coating made of an at least partially transparent material. This component features internal structures introduced into its volume after material production, which modify the optical properties of the volume compared to the unstructured volume. The surface coating of the component can preferably be designed according to the aforementioned earlier German patent applications with file numbers 10 2024 138 585.5 and 10 2024 138 590.1.

[0026] The material's structure comprises modification bubbles arranged in a uniform, periodic, or random pattern in at least one plane within the volume. This allows for the creation of white, gray, and black hues, as well as iridescent colors resembling a rainbow, in the surface coating. The resulting color effect can encompass the entire surface or only specific areas for graphic elements such as logos. The optical effect is achieved by altering transmission and, in particular, reflection using an optical grating, producing different visual impressions depending on the viewing angle and lighting conditions. For example, these changes are barely perceptible in low light.P 2023-02844WO / 2023PF02404 / ILT - 2021 F66480 / Mercedes-Benz Group AG, Fraunhofer Society for the Promotion of Applied Research e. ​​V / System and method for periodic volume structuring of Klarlaok / ST / PM / 20250354393 / 10 December 2025.

[0027] 5

[0028] The system according to the invention therefore comprises a lighting device which is arranged opposite the component in such a way that it illuminates a visible side of its surface coating. Unlike the backlighting of the emitter body in the aforementioned DE 10 2008 021 658 A1, here an incident light illumination is deliberately created which selectively highlights the desired optical properties largely independently of the natural ambient light.

[0029] A preferred embodiment of the system according to the invention provides that the lighting device comprises one or more light sources, at least some of which are designed to be variable with respect to their light color and / or light intensity. The light sources can thus be designed flexibly in order to, for example, adjust the brightness to the ambient light level and / or achieve special optical effects by varying the colors. The light sources can, for example, be in the form of LEDs whose light intensity and light color can be controlled differently.

[0030] The light sources can directly illuminate the visible side of the surface coating. To avoid reflection from individual light points, diffusing screens could also be placed between the light sources and the surface.

[0031] A particularly advantageous further development approach can also involve concealing the lighting device when viewed from the front. This makes it possible to install the lighting in such a way that it is not visible itself, but illuminates the optical structures. If these are, for example, iridescent logos in the surface coating of a car wheel rim, then the light sources could be positioned inside the fender to indirectly illuminate the rim. P 2023-02844WO / 2023PF02404 / ILT - 2021 F66480 / Mercedes-Benz Group AG, Fraunhofer Society for the Advancement of Applied Research e. ​​V. / System and Method for Periodic Volume Structuring of Klarlaok / ST / PM / 20250354393 / 10 December 2025

[0032] 6

[0033] Another very advantageous design allows the lighting device to be controlled in such a way that the angle of incidence of the emitted light relative to the visible side of the surface coating can be varied. This control can be achieved mechanically by moving the light sources or solely through the method of light control. For example, several light sources could be positioned at different angles, each controlled individually, or the combined light intensity at each angle could be varied to produce a primary light emission at a predetermined angle. This allows, for example, iridescent lighting effects to be showcased with particular brilliance.

[0034] A further highly advantageous embodiment of the system according to the invention can further provide that the structure comprises a three-dimensional grid of points originating from a plane, consisting of modification bubbles. According to an advantageous further development, the grid of points can lie in at least three parallel planes, each comprising a point matrix. The individual planes can be arranged at uniform intervals from one another or their spacing can vary. For example, it is possible to form two planes very close to each other and to position at least one further plane at a significantly greater distance from them. Different color effects can thus be implemented sequentially in different planes, resulting in a high degree of variability with regard to the white, black, and gray tones used on the one hand, and the iridescent colors on the other.In particular, these can be combined with each other in the different layers within a single viewing direction. For example, a dot grid could be generated in a lower layer, resulting in a light color perception, and in a layer above, a dot grid could be generated, resulting in an iridescent color perception, thus, for example, "underlining" an iridescent logo with a light color or shade of gray. P 2023-02844WO / 2023PF02404 / ILT - 2021 F66480 / Mercedes-Benz Group AG, Fraunhofer Society for the Advancement of Applied Research e. ​​V. / System and method for the periodic volume structuring of Klarlaok / ST / PM / 20250354393 / 10 December 2025.

[0035] 7

[0036] According to a particularly advantageous embodiment, the modification bubbles of the respective dot matrix are formed as an arrangement of parallel or intersecting lines. A line, in the sense of the present invention, means that the spacing of the modification bubbles within the line, or in the direction of the line, is smaller than the spacing perpendicular to it. This allows a predetermined optical grating to be efficiently implemented using the line structure.

[0037] According to a highly advantageous further development, the distance between the modification bubbles in one direction within the plane can be on the order of the wavelength of visible light, i.e., approximately between 400 and 780 nm. A similar spacing of the modification bubbles within the line, if the modification bubbles are arranged in lines, then creates the iridescent color effect mentioned above, which is perceptible to the human eye in different colors depending on the viewing direction and shines in the colors of the rainbow. When the material is moved, the position of the individual colors within the structure changes relative to the eye.

[0038] The structure itself can be generated within the volume of the material in any desired manner, particularly with the aid of radiation such as plasma or ion radiation. It is especially preferred that it be generated using a focused laser beam, for example, an ultrashort pulse laser. Preferably, the entire structure consists exclusively of the modification bubbles, thus dispensing with any other inclusions or the like.

[0039] According to a highly advantageous further development, the modification bubbles can have a droplet-shaped form with a diameter of 0.1 to 10 pm. Ideally, the droplet diameter is approximately 2 to 8 pm. P 2023-02844WO / 2023PF02404 / ILT - 2021 F66480 / Mercedes-Benz Group AG, Fraunhofer Society for the Advancement of Applied Research e. ​​V. / System and method for the periodic volume structuring of clear liquid / ST / PM / 20250354393 / 10 December 2025

[0040] 8

[0041] The at least one plane in which this structure is arranged can be positioned at a predetermined angle to the visible side of the surface coating. This angle can preferably range from 0° (i.e., the plane being parallel to the visible side) to 90°. Ideal angles lie between 0° and 60°. This allows certain viewing directions to favor the optical effect of the color and, in particular, the iridescent light. If the visible side is three-dimensionally curved, the predetermined angle to a flat compensating surface can be determined by this surface. If several planes are arranged one above the other, they can also be positioned at different predetermined angles to the visible side, thus producing different color effects when viewing the component obliquely compared to viewing it perpendicularly.

[0042] The inventive method for controlling the lighting in such a system provides that the lighting is adjusted with regard to its color and / or intensity over time and / or depending on detected environmental parameters. The lighting can therefore be used very flexibly. For example, it can be adjusted to the ambient brightness. It would also be conceivable to switch on and / or change the lighting whenever a person approaches. This would allow, for example, the implementation of a kind of welcome light. Detecting the person and their direction of gaze towards the component is also conceivable; then, for example, the intensity and angle of the lighting can be adjusted so that the ideal optical effect, e.g., an iridescent logo, is visible to the person.

[0043] A preferred embodiment further provides that the color and / or intensity is adjusted according to a temporal profile. This allows, for example, the implementation of pulsating colors and / or brightness levels, or the realization of targeted day and night lighting. P 2023-02844WO / 2023PF02404 / ILT - 2021 F66480 / Mercedes-Benz Group AG, Fraunhofer Society for the Advancement of Applied Research e. ​​V. / System and method for the periodic volume structuring of Klarlaok / ST / PM / 20250354393 / December 10, 2025

[0044] 9

[0045] The system according to the invention can, in principle, be used anywhere. However, as has already become clear from the examples, it is particularly suitable for use in or on a vehicle, such as a land or watercraft. According to the invention, a vehicle is therefore provided with at least one such system according to the invention. The system can be located either inside the vehicle, e.g., a passenger car, or on its exterior. Suitable components of the system according to the invention include add-on parts to the vehicle, such as rims, as well as the visible exterior surface of the vehicle itself. Inside, all surfaces of the interior fittings, but especially smooth surfaces such as those of decorative elements on the dashboard or similar, can be part of the system.

[0046] An advantageous vehicle design can further provide for the lighting system to be an existing lighting system or integrated into one. This makes the system particularly efficient. For example, interior lights can be used, or downward-facing lights in the exterior mirrors can illuminate the area in front of the open door at night. Such lights are often suitable for direct use as the system's lighting device. If not, they can be easily modified or supplemented accordingly, since the installation space and wiring are already in place. The downward-facing lights in the exterior mirrors can, for example, serve as concealed lighting for a logo or similar element embedded in the outer surface of the door.

[0047] As can already be seen from the preferred dimensions of the modification bubbles described above, the optical structure can be made extremely small. Several parallel planes can therefore be integrated into the at least partially transparent surface coating. Such a system is described in P 2023-02844WO / 2023PF02404 / ILT - 2021 F66480 / Mercedes-Benz Group AG, Fraunhofer Society for the Advancement of Applied Research e.V. / System and method for the periodic volume structuring of Klarlaok / ST / PM / 20250354393 / 10 December 2025

[0048] 10. At least partially transparent surface coatings can be achieved, in particular, on the basis of polymer materials.

[0049] According to a particularly advantageous embodiment of the vehicle, the surface coating can be formed as a partially transparent paint layer, especially a clear coat, on the vehicle or one of its attachments. Such a clear coat can be provided with the appropriate structures after its production, preferably using a laser, in order to subsequently impart a certain color to the clear coat layer, for example, by introducing gray, white, or black lettering, brand logos, and / or iridescent brand logos, lettering, or other optical representations into the already applied clear coat.

[0050] Further advantageous embodiments will also become clear from the following exemplary embodiment, which is described with reference to the figures.

[0051] This shows:

[0052] Fig. 1 shows a cross-section through a system with a lighting device and a substrate with a transparent lacquer layer having an optically effective structure inside the lacquer layer;

[0053] Fig. 2 shows a top view of the paint finish according to Fig. 1 in a first embodiment a) and a second embodiment b);

[0054] Fig. 3 shows a possible embodiment of the system in a first embodiment a) and a second embodiment b); and

[0055] Fig. 4 is a photographic illustration of a surface coating according to the invention on a section of a rim. P 2023-02844WO / 2023PF02404 / ILT - 2021 F66480 / Mercedes-Benz Group AG, Fraunhofer Society for the Advancement of Applied Research e. ​​V. / System and method for the periodic volume structuring of clear lacquer / ST / PM / 20250354393 / 10 December 2025

[0056] 1 1

[0057] Figure 1 shows a system 100 comprising a lighting device 10 and an at least partially transparent surface coating 1, in particular a clear lacquer 1, illuminated by the incident light. This clear lacquer 1 is arranged on a substrate designated 2. Within the thickness of the clear lacquer 1, structures designated 3 are arranged in three planes, one behind the other, starting from a visible side 4 of the clear lacquer 1. Each of the planes can contain a dot matrix. The illuminated visible side of the clear lacquer 1 is viewed by a person, indicated here by an eye 11.

[0058] In the two top views shown in Figure 2 a) and b), the dot matrices can be seen in two possible embodiments. In Figure 2 a), it can be seen that individual lines 6, each formed from a series of modification bubbles 5 (described in more detail in Figures 3 and 4), create a regular rectangular grid. This grid acts as an optical grating and can very precisely and homogeneously alter the optical properties, particularly the transmission and remission within the clear coat 1, across its entire extent.

[0059] The lines 6 are formed by a series of modification bubbles 5, which is indicated here by the dotted representation of the lines 6. With a spacing x of the lines 6 of a few tens of pm, e.g., approximately 30 pm, but in any case above the order of magnitude of visible light, black, white, and shades of gray can be produced. This allows for a high degree of design flexibility. The somewhat more complex optical gratings enable the achievement of very homogeneous colors (including shades of gray) or color gradients. If this is not strictly necessary, good results can also be achieved with the alternative shown in Figure 2 b). Here, individual lines replace the periodically repeating lines 6.

[0060] Modification bubbles 5, which are distributed as a random pattern. The color nuances P 2023-02844WO / 2023PF02404 / ILT - 2021 F66480 / Mercedes-Benz Group AG, Fraunhofer Society for the Advancement of Applied Research e. ​​V. / System and method for the periodic volume structuring of Klarlaok / ST / PM / 20250354393 / 10 December 2025

[0061] The 12 shades of gray result solely from an average areal density of the modification bubbles 5. However, the resulting gray tone may appear somewhat less homogeneous than in the implementation according to Figure 2 a).

[0062] With both variants, structures 3 can be subsequently introduced into an already applied clear coat layer using a laser, e.g. in the form of a brand logo.

[0063] The modification bubbles 5 themselves are droplet-shaped. Their diameter ranges from 0.1 to 10 pm, typically from approximately 2 to 8 pm. The modification bubbles 5 alter the refractive index of the clear lacquer 1 used. According to current findings, this is likely due to a reorganization / rapid solidification of the molten clear lacquer 1, as well as a local change in chemical composition caused by irradiation.

[0064] It is particularly interesting when the distance between the modification bubbles 5 of each individual line 6 in an optical grating is on the order of 400 to 780 nm. The distance x between the individual lines 6 is, for example, more than 30 pm. This allows, as detailed in the older German application with file number 10 2024 138 585.5, an iridescent color effect, i.e., a shimmering in rainbow colors, to be achieved. Especially with these iridescent colors, the color intensity and distribution perceptible to person 11 depend strongly on the viewing angle. However, by a targeted arrangement of the lighting device 10 to illuminate the viewing side 4 with incident light, it can be ensured that the iridescent effect is particularly brilliantly visible from a specific point, e.g., when standing in front of the driver's door.However, not only iridescent designs created by Structure 3, but also other non-iridescent design elements can be highlighted in this way. P 2023-02844WO / 2023PF02404 / ILT - 2021 F66480 / Mercedes-Benz Group AG, Fraunhofer Society for the Advancement of Applied Research e. ​​V. / System and method for periodic volume structuring of clear liquid / ST / PM / 20250354393 / 10 December 2025.

[0065] 13

[0066] Active illumination of an iridescent logo 12 (designated in Figure 3a) in the clear coat 1 of a vehicle 13, for example, under the lighting device 10 concealed in an exterior mirror 14, can be designed such that the direction of incidence of the light emitted by the lighting device 10 at the underside of the exterior mirror 14 results in the most intense and brilliant iridescence. Figure 3b) illustrates a similar scenario for the interior of the vehicle 13. Here, the lighting device 10 is integrated into an interior rearview mirror 15 and illuminates the logo 12 so that, for example, when viewed from the driver's seat, it exhibits maximum brilliance.

[0067] The intensity of at least one light source in the lighting device 10 can be varied depending on the desired effect. The light spectrum can also be specifically selected, e.g., only blue light. Furthermore, the light can change its intensity (e.g., pulsating) or light spectrum over time to create particularly interesting effects. The lighting device 10 can be mounted in an openly visible position or, preferably, concealed. Existing light sources (headlights, exterior ambient lighting, interior lighting, ambient lighting, etc.) can also be used directly or supplemented as described above.

[0068] Finally, Figure 4 shows a photograph of a section of a rim 7 for the vehicle 13. The rim 7 is provided with a clear coat as a transparent surface coating 1. Structures 3 are incorporated into this clear coat 1 in at least one plane, in particular parallel to the visible side 4 of the clear coat 1. These structures represent the "Maybach" brand logo (corresponding to a registered trademark of one of the co-applicants). The entire optical effect that makes the brand logo 12 visible as a structure 3 within the clear coat 1 is based on modification bubbles 5, which are formed in a lattice structure. The lighting device 10 around the logo 12 P 2023-02844WO / 2023PF02404 / ILT - 2021 F66480 / Mercedes-Benz Group AG, Fraunhofer Society for the Advancement of Applied Research e. ​​V. / System and method for the periodic volume structuring of Klarlaok / ST / PM / 20250354393 / 10 December 2025

[0069] To showcase 14 particularly well visually, for example, this can be done inside the

[0070] fender, in which the wheel with the rim 7 is arranged, is housed.

Claims

P 2023-02844WO / 2023PF02404 / ILT - 2021 F66480 / Mercedes-Benz Group AG, Fraunhofer Society for the Advancement of Applied Research e. ​​V. / System and method for the periodic volume structuring of Klarlaok / ST / PM / 20250354393 / 10 December 2025 15 Patent claims 1. System (100) comprising a lighting device (10) and a component with a surface coating (1) made of an at least partially transparent material, which has structures (3) introduced into its internal volume after the material production, which modify the volume with respect to its optical properties compared to the unstructured volume, characterized in that the structure (3) comprises modification bubbles which are formed in a uniform periodic or random arrangement in at least one plane in the volume, wherein the lighting device (10) is arranged relative to the component such that it illuminates a visible side (4) of its surface coating (1).

2. System (100) according to claim 1 , characterized in that the lighting device (10) comprises one or more light sources, at least some of which are designed to be variable with respect to the color of the light and / or the intensity of the light.

3. System (100) according to claim 1 or 2, characterized in that the lighting device (10) is arranged in a concealed position when looking at the viewing side.

4. System (100) according to claim 1, 2 or 3, characterized in that the lighting device (10) is controllable in such a way that the P 2023-02844WO / 2023PF02404 / ILT - 2021 F66480 / Mercedes-Benz Group AG, Fraunhofer Society for the Advancement of Applied Research e. ​​V. / System and method for the periodic volume structuring of Klarlaok / ST / PM / 20250354393 / 10 December 2025 16 The angle of incidence of the emitted light relative to the viewing side (4) of the surface coating (1) can be varied.

5. System (100) according to one of claims 1 to 4, characterized in that the structure (3) comprises a three-dimensional point grid of modification bubbles (5) extending from the plane, which has at least three point matrices lying in parallel planes.

6. System (100) according to claim 5, characterized in that the modification bubbles (5) of the respective point matrix have an arrangement of parallel or intersecting lines (6).

7. System (100) according to one of claims 1 to 6, characterized in that the distance between the modification bubbles (5) in a direction within the plane is on the order of the wavelength of visible light.

8. System (100) according to one of claims 1 to 7, characterized in that the structure (3) is generated by means of a focused laser beam.

9. System (100) according to one of claims 1 to 8, characterized in that the modification bubbles (5) have a droplet-shaped design with a diameter of 0.1 to 10 m.

10. Method for controlling the lighting in a system (100) according to any one of claims 1 to 9, P 2023-02844WO / 2023PF02404 / ILT - 2021 F66480 / Mercedes-Benz Group AG, Fraunhofer Society for the Advancement of Applied Research e. ​​V. / System and method for the periodic volume structuring of Klarlaok / ST / PM / 20250354393 / 10 December 2025 17 characterized in that the lighting is adjusted with regard to its color and / or intensity over time and / or depending on detected environmental parameters.

11. Method according to claim 10, characterized in that the color and / or intensity is adjusted according to a time profile.

12. Method according to claim 10 or 11, characterized in that the environmental parameters include data on ambient brightness and / or the presence or approach of persons.

13. Vehicle (13) with at least one system (100) according to any one of claims 1 to 9.

14. Vehicle (13) according to claim 13, characterized in that the lighting device (10) is an already existing Lighting device is designed or is integrated into such a device.

15. Vehicle (13) according to claim 13 or 14, characterized in that the surface coating (1) is designed as a paint layer, in particular as a clear coat.

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