Vehicle glazing with a light-scattering printing

Abstract

The invention relates to a vehicle glazing (3) with a light-guiding glass pane (8) which has a printing (11), a light input coupling for coupling light of a lighting device (4) into the glass pane (8) via an edge region (5) of the glass pane (8), and a light output coupling for coupling the coupled light out of the glass pane (8) by means of the printing (11) of the glass pane (8), wherein the printing (11), as a light-scattering structure, is made of individual ink droplets (13) and the ink droplets (13) are made of ink printed onto the glass pane (8). A polymer cover layer (10) covers the cured ink droplets (13). According to the invention, the refractive index nG of the glass pane (8), the refractive index nP of the printing (11), and the refractive index nD of the cover layer (10) are in the ratio nG > nD and nP > nD, in particular nP ≥ nG > nD.

Description

[0001] Vehicle glazing with a light-diffusing print

[0002] The invention relates to a vehicle glazing with a light-conducting glass pane having a print and with a light coupling of light from a lighting device via an edge region of the glass pane into the glass pane and with a light coupling of the coupled light out of the glass pane by means of the print on the glass pane, wherein the print is formed as a light-scattering structure from individual ink drops and the ink drops are formed from ink printed on the glass pane and wherein a polymeric cover layer covers the cured ink drops.

[0003] EP 3 702 217 A1 discloses a generic vehicle glazing with a light-conducting glass pane having a print.

[0004] The printing is done with individual ink drops that are spaced apart from each other, allowing visibility through the printed glass pane. However, such printing can cause optical distortion for a viewer looking through the printed glass pane.

[0005] The invention is based on the object of creating a vehicle glazing system as mentioned above with improved optical properties. This object is achieved according to the invention in the vehicle glazing system as mentioned above in that the refractive index nc of the glass pane, the refractive index np of the printing, and the refractive index no of the cover layer are in the ratio nc > no and np > no.

[0006] Advantageous embodiments of the invention are specified in the dependent claims.

[0007] Vehicle glazing with ambient lighting thus includes a glass pane as a light-conducting layer. The light-conducting glass pane is preferably made of a mineral glass or a plastic such as polycarbonate or a similar material. The refractive index nc in the visible range, for example for light of 589.33 nm, has a value of 1.50 to 1.58 in one embodiment. The refractive index of the cover layer no correspondingly has a value in the visible range, for example for light of 589.33 nm in one embodiment of 1.48 to 1.49, and the refractive index of the printing np has a value of 1.50 to 1.90 in a corresponding embodiment. The glass pane has a refractive index nc in the visible range, for example for light of 589.33 nm of preferably > 1.50, in particular > 1.52, for example 1.58 for polycarbonate, or > 1.50 for glass.An exemplary glass material for the glass pane has a refractive index nc in the visible range, for example, for light at 589.33 nm, of preferably 1.505. Light from a lighting device is coupled into the glass pane via an edge region of the glass pane. The lighting device contains, for example, at least one LED or RGB LED as a light source. Preferably, a lighting device is arranged on each of two opposite side edges of the glass pane or the vehicle glazing.

[0008] The glass pane includes a lower outer or main surface facing a vehicle interior and an upper outer or main surface facing an exterior environment of the vehicle glazing. The vehicle glazing is expediently formed as a laminated glass pane and thus comprises a second glass pane or outer pane laminated to the first light-conducting glass pane by means of an intermediate layer, also referred to as a cover layer, which is in particular a hot-melt adhesive film. The transparent cover layer is thus preferably a layer made of a polymeric material such as PVB (polyvinyl butyral) or EVA (ethylene-vinyl acetate). The cover layer has a refractive index n o of in particular 1.48.

[0009] It is advantageous that the refractive index nc of the glass pane, the refractive index np of the printing, and the refractive index no of the cover layer are in the ratio np > HG > no, preferably np = nc. Depending on the size, shape, and proportion of the decoupling particles arranged in the printing, which are also referred to as scattering particles, np > nc is advantageous to increase the scattering effect of the printing.

[0010] The cover layer, with its refractive index n, determines the critical angle OD of total internal reflection in the glass pane. The critical angle of total internal reflection (measured at the interface) at the interface between the glass pane and the printed structure is OD = 90°-arcsin (n / n). Light with an angle greater than OD enters the printed light-scattering structure in the area where the glass pane is covered by the printed light-scattering structure. The penetrating portion of the light guided in the glass pane is thus 1 -(n / OD). The intensity of the scattered light is determined by the refractive index of the printed light-scattering structure for given n and n.

[0011] For example, for no = 1.48 and nc = 1.52, the critical angle OD = 13.2°. Thus, at the interface between the glass pane and the cover layer, only those light rays that impinge on the interface at an angle smaller than the critical angle and are thus oriented very flatly relative to the interface are completely reflected. The glass pane acts as a light guide for such very flat light rays.

[0012] The glass pane has a print on its upper main surface. The print is formed as a light-scattering structure made up of individual ink droplets. The ink droplets are printed onto the glass pane using transparent ink, particularly digital printing (inkjet printing). The ink preferably contains scattering particles. The cover layer covers the print or the ink droplets, which are cured, for example, using UV light.

[0013] The ink droplets of the light-scattering structure are located at the interface between the glass pane and the cover layer. Light rays guided through the glass pane are scattered by the ink droplets and diffusely coupled out of the glass pane via the lower main surface into the vehicle interior, creating ambient lighting.

[0014] The refractive index np of the print or the ink droplets, together with the refractive index nc of the glass pane, determines which portions of the light rays guided in the glass pane can penetrate into the ink droplets and which portions are totally reflected at the interface.

[0015] The refractive index np of the ink droplets is a mixture of the refractive indices of an ink matrix and the scattering particles. The refractive index np of the ink droplets can be adjusted by changing the materials of the ink and the scattering particles and their mixture.

[0016] To couple light into the light-scattering structure or the ink droplets, the refractive index np of the ink droplets must be greater than the refractive index no of the cover layer (np > no). The greater the proportion of light coupled into the light-scattering structure or the ink droplets, the brighter the ink droplets of the light-scattering structure will glow.

[0017] For ambient lighting, it may be preferable to couple as much light as possible into the glass pane and to couple it out of the glass pane to the vehicle interior via light scattering. The ratio of the light coupled into the ink droplets to the light reflected at the interface and not coupled into the ink droplets is determined by the refractive indices np and n0. Maximum light coupling and light scattering is achieved when np > CIG. Minimum light coupling and light scattering by the printing is achieved when np approaches n0, up to n P < no, for which essentially no light coupling and light scattering by the printing is detectable.

[0018] For a high intensity of the ambient lighting, it is therefore advisable to set the refractive index np of the printing or the ink drops in such a way that it is significantly higher than the refractive index no of the cover layer.

[0019] The ink droplets have a thickness of, for example, 0.001 mm to 0.2 mm. The thickness of the ink droplets is understood to be the layer height formed by the ink droplets, i.e. it is a thickness or height perpendicular to the printed surface (preferably the main surface) of the glass pane. During the digital printing of the ink droplets, the light-scattering structure is printed with viscous ink and then cured with UV light. In this process, the surface of the ink droplets takes on a curved profile, at least at the edges of the ink droplets, or the ink droplet as a whole takes on an almost plano-convex shape. This shape of the ink droplet, together with the different refractive indices np and n o, leads to an optical lens effect.

[0020] Assuming a radius R for the curved surface of the ink droplet, the refractive power of the optical lens can be estimated as D = (np - no) / no / R. This means that the effect of the ink droplet as an optical lens increases linearly with increasing refractive index no. A glass pane with such a print will exhibit undesirable distortions when observing high-contrast scenes through the glass pane as the refractive index of the print increases, np.

[0021] The desired properties of high luminous intensity through light scattering and low distortion can thus be adjusted via the refractive index np of the light-scattering structure or the ink droplets, respectively. However, these properties are inversely proportional. The highest intensity is achieved when np > HG. However, this is accompanied by the highest distortion. Reducing the distortion to 50% already results in a significant loss of luminous intensity, down to 25%. Reducing the distortion solely by adjusting the refractive index np is not effective.

[0022] When printing many individual, spaced-apart ink drops, which preferably have a size or diameter in the range of approximately 0.04 mm to approximately 0.08 mm, and preferably approximately 0.05 mm to approximately 0.07 mm, and in particular approximately 0.07 mm, and a mutual spacing of, for example, 0.1 mm or less than 0.1 mm, the individual ink drops are no longer recognizable to the eye as such individual ink drops. Rather, an area with such small ink drops is perceived as a solid printed surface.

[0023] Thus, if the ink droplets are printed at such a small size that the human eye can no longer resolve them, no distortion is noticeable. The individual ink droplets act like microlenses, scattering light over a wide area, thus creating high levels of haze or turbidity. Light components that do not reach the ink droplets are transmitted undisturbed. The resulting image in transmission is thus a superposition of an undisturbed image with a blurred image.

[0024] The desired prevention of distortions can thus be achieved by printing with a light-scattering structure using individual ink drops, wherein the refractive index nc of the glass pane, the refractive index np of the printing, and the refractive index no of the cover layer are in a ratio of nc > no and np > no. Preferably, np > nc, in particular np > nc and / or np > nc > no.

[0025] In such a glass pane or vehicle glazing, a portion of the light from an external scene observed through the glass pane or vehicle glazing passes undisturbed through the spaces between spaced-apart ink droplets. Another portion of the light strikes the ink droplets and is diffracted or deflected to a greater or lesser extent due to the strong curvature of the ink droplet surface. An observer or vehicle occupant therefore sees an undisturbed image (in transmission) overlaid by a cloudy or diffuse image. Distortion due to beam deflections at large ink droplets therefore does not occur due to the lack of such large ink droplets. Large ink droplets are defined in such a way that they are perceptible to the human eye, i.e. they also noticeably influence a visible image.Typically, the optical resolution perceivable by the human eye is assumed to be 2 arcminutes, especially 1 arcminute. For example, at a standard distance of 25 cm, structures at a distance of 0.3 mm would be distinguishable.

[0026] Each individual ink droplet is expediently formed approximately in the shape of a semi-ellipsoid. The ink has a viscosity such that when applied to the glass pane, particularly in a digital printing process, the ink forms an ink droplet of this shape on the glass pane. The shape of the semi-ellipsoid is further determined by the speed of the ink as it hits the glass pane and by the hardening speed of the ink or ink droplet as the ink droplet dries. These parameters are defined such that the ink droplet has the desired shape after drying and hardening. The semi-ellipsoid has a diameter of its base area and a height that are in a ratio of, for example, 0.5 to 1.5.A flank angle of the ink drop, which is defined as the angle between a perpendicular to the glass plate at the edge of the ink drop and a tangent emanating from the glass plate at the circumference of the semi-ellipsoid, is preferably about 5° to 10° at the base of the semi-ellipsoid or the ink drop and preferably about 15° to 30° at half the height of the semi-ellipsoid or the ink drop.

[0027] The shape of the semi-ellipsoid represents an approximation of the actual shape of the ink drop for the purpose of describing it. Slight deviations of the ink drop from this shape can therefore be neglected for the description of the ink drop. An ink drop that is comparatively narrow and tall, i.e. has a smaller cross-sectional area at the interface than its height, reflects light rays incident from the glass pane at the interface between the ink droplet and the cover layer to a lesser extent than a wider and shorter ink droplet, i.e. one with a lower height, reflects the light rays incident from the glass pane over its lower main surface towards the vehicle interior. The shape of the ink droplet can therefore be used to adjust the light output as well as the light diffraction or deflection of the ink droplet, which acts as an optical lens.

[0028] The following refractive indices are provided for convenience:

[0029] - Refractive index np of the ink drops in the range of 1.51 to 1.54 and in particular 1.53,

[0030] - Refractive index HG of the light-conducting glass pane 1 ,505 and

[0031] - Refractive index no of the covering layer in the range from 1.48 to 1.49 and in particular 1.485.

[0032] It is particularly preferred that the individual ink drops, preferably printed by digital printing, have a size or diameter in the range from 0.04 mm to 0.08 mm, preferably from about 0.05 mm to about 0.07 mm and in particular about 0.07 mm.

[0033] According to a preferred embodiment, the majority of the ink droplets or all of the ink droplets have a mutual spacing of less than 0.1 mm. The spacing between any two adjacent ink droplets is thus less than 0.1 mm and preferably lies in a range of 0.02 mm to 0.08 mm.

[0034] According to a further preferred embodiment, some of the ink droplets are in mutual contact. Due to the contact, contact surfaces exist between contacting ink droplets. Furthermore, gaps exist between the spaced-apart ink droplets. The cover layer covers the entire print and thus the ink droplets themselves as well as the contact surfaces between the ink droplets and also fills the gaps. Contact with the cover layer reduces the proportion of optical interference caused by the ink droplets, which is caused for example by spurious reflections and / or spurious diffraction and / or spurious refraction and / or spurious scattering at the ink droplets, or completely eliminates this interference. Such optical interference is, for example, reflection or refraction, which results in perceptible distortion, perceptible clouding and / or perceptible opacity for the human eye.This results in a very transparent print that also exhibits good light transmission and light extraction values. This property is also achieved by the fact that light directed perpendicular to the printed glass pane covered with the cover layer is only slightly reflected, diffracted, or scattered at contact surfaces or interfaces oriented almost perpendicularly to the printed, light-conducting glass pane (especially > 70° to the contact surface or interface). Light directed flatly (especially < 20° to the contact surface or interface) through the printed glass pane covered with the cover layer is also only slightly reflected, diffracted, or scattered.Thus, a preferred embodiment is designed such that an ink droplet has a large flank angle (increasing from the boundary layer between the ink droplet and the glass pane) to its height, whereas between corresponding flanks a surface of the printing is formed which runs as parallel as possible to the boundary surface.

[0035] According to a preferred embodiment, the printing has at least two areas in which the ink droplets are arranged at different mutual distances and / or have different sizes or diameters or even different thicknesses. This makes it possible to form optically different appearing areas for displaying patterns or even a logo or the like, which are particularly visible via the scattered and decoupled light of the ambient lighting. According to a preferred embodiment, the vehicle glazing has a second glass pane or outer pane which is laminated to the glass pane on the side bearing the printing by means of the cover layer. The vehicle glazing can also comprise a further functional layer, for example a switchable layer with variable transparency or translucency.

[0036] According to a preferred embodiment, the vehicle glazing is formed as a transparent laminated glass pane. In one embodiment, the vehicle glazing can be a partially transparent laminated glass pane, for example, with a transmittance of less than 20%, preferably less than 10%.

[0037] A lighting device or at least one light source of such a lighting device for introducing light is preferably arranged on one of two lateral and opposite edges or edge regions of the glass pane or of a laminated glass pane comprising the glass pane, wherein the lateral edge refers to a left and a right side edge of the substantially rectangular glass pane or laminated glass pane arranged on a vehicle roof. The light from the light source can be coupled in via the side edge or via a side surface on the side edge of the glass pane or via an edge strip on an inner or underside main surface of the glass pane, e.g., by means of optical prisms arranged on the edge strip (as disclosed in WO 2023 / 031460 A1) or other optical light-guiding devices or light-coupling devices.

[0038] Furthermore, a generally vertical light coupling from below can be provided via the inner or underside main surface of the glass pane. In this case, an optical device is provided, for example, a diffuser layer or a diffuser element, which is arranged opposite the light coupling or a light source, for example on an inner main surface of a second glass pane. The optical device scatters or deflects coupled-in light such that the coupled-in light is redirected predominantly at an angle corresponding to the angle of total internal reflection of the second glass pane.

[0039] The invention will be explained in more detail below using exemplary embodiments of a vehicle glazing according to the invention with reference to the drawing. It shows:

[0040] Fig. 1 shows a perspective view of a vehicle with a vehicle roof having vehicle glazing;

[0041] Fig. 2 shows a schematic sectional view of an edge region of a light-conducting glass pane of the vehicle glazing with light reflection on a print on the glass pane;

[0042] Fig. 3 shows a sectional view in schematic representation of the light-conducting glass pane with light transmission and light scattering at the printing of the glass pane;

[0043] Fig. 4 shows a sectional view in schematic representation of an area of ​​the glass pane with a printed ink droplet;

[0044] Fig. 5 is a sectional view showing a schematic representation of the glass pane with ink drops of printing and the representation of scattered and unscattered light transmission;

[0045] Fig. 6 shows a sectional view in schematic representation of the glass pane with ink drops of the printing and light rays reflected by the ink drops;

[0046] Fig. 7 shows a schematic top view of the glass pane with ink drops applied by digital printing; Fig. 8 shows a schematic top view of the ink drops applied to the glass pane during curing according to Fig. 7;

[0047] Fig. 9 shows a top view in a schematic representation according to Fig. 8 of the ink drops applied and cured to the glass pane with a covering layer; and

[0048] Fig. 10 shows a sectional view in a schematic representation of the vehicle glazing in a further embodiment.

[0049] A vehicle, such as a passenger car, comprises a vehicle roof 1 (Fig. 1) with a roof opening 2, in which a vehicle glazing 3 is arranged, which is, for example, fixedly arranged in the roof opening 2 or is formed as a cover that is movably mounted in the roof opening 2 by means of a bearing device and adjustable between a closed position and ventilation or open positions in a manner known per se. The vehicle glazing 3 can also be a fixed part or section of a roof module or panoramic roof. A lighting device 4 is arranged on each of the two opposite lateral edge regions 5 of the vehicle glazing 3 and extends on the inside 6 of the pane, preferably along a respective side edge 7 of the vehicle glazing 3.

[0050] The vehicle glazing 3 comprises, in particular, a laminated glass pane with a glass pane 8 as the inner pane, an outer pane 9, and a polymeric cover layer 10 as a connecting layer, which connects the glass pane 8 to the outer pane 9 and contains, for example, a laminate layer, laminate film, or hot-melt adhesive film, in particular made of PVB or EVA. The outer pane 9 is, for example, a tinted glass pane, which can be both transparent and non-transparent. The inner glass pane 8 is, in particular, a transparent and light-conducting glass pane or clear glass pane, preferably made of low-iron glass, which forms a light-conducting layer for coupled-in light. The cover layer 10 covers a print 11 arranged on an inner main surface 12 of the glass pane 8. The print 11 is produced with ink, which is preferably sprayed or printed onto the glass pane 8 using a digital printing process.The individual ink drops 13 formed with the ink form a light-scattering structure of the print 11.

[0051] The lighting device 4 (shown schematically as a light source in Figs. 2 and 3) contains, for example, a plurality of LEDs or RGB LEDs as light sources, which are arranged along the side edge 7 of the glass pane 8 and whose light is coupled into the glass pane 8, for example, via an edge-side side surface 14 of the glass pane 8. Light rays 15 of the coupled light are reflected in the glass pane 8 at an inner boundary surface 16 and at an outer boundary surface 17. The inner boundary surface 16 corresponds to the inner main surface 12 covered by the cover layer 10. The outer boundary surface 17 corresponds to an outer or lower main surface 18 of the glass pane 8, which faces a vehicle interior.

[0052] The glass pane 8 has a refractive index HG of in particular 1.505.

[0053] The print 11 or the ink droplet 13 has a refractive index np of, in particular, 1.52 or 1.53. The cover layer 10 has a refractive index no of, in particular, 1.485.

[0054] Light rays 15 that strike the interfaces 16 and 17 at angles a that are smaller than the critical angle of total internal reflection are totally reflected in the glass pane 8 and do not exit the glass pane 8 via the lower main surface 18. The critical angle (measured between the light beam and the interface) of total internal resection is determined by a n = 90°-arcsin(n n / n“). For n n = 1 ,485 and n„ = 1 ,505 the critical angle a n= 9.35°. Thus, at this critical angle, only light rays 15 oriented very flatly relative to the interface 16 are totally reflected at the interface 16 of the glass pane 8 facing the cover layer 10. The glass pane 8 therefore acts as a light guide for such flat light rays. Light rays 15 that impinge on an ink droplet 13 of the light-scattering structure of the print 11 at the inner interface 16 enter the ink droplet 13 at corresponding angles and refractive indices and are reflected at the interface between the ink droplet 13 and the cover layer 10 covering the ink droplet 13 and are coupled out as scattered light via the lower main surface 18 toward the vehicle interior. This creates ambient lighting.

[0055] The light guided in the light-guiding glass pane 8 is limited by the critical angle α of total resection. A beam of incident light Li (Fig. 3) is totally reflected and guided further in the glass pane 8 as light beam L2 if it is incident at a shallower angle than the critical angle α, and it penetrates the cover layer 10 as light beam L3 if it is incident at a steeper angle.

[0056] The refractive index np of the scattering structure or the ink drop 13, together with the refractive index HG of the glass pane 8, determines which portions of the transmitted light L2 can penetrate into the scattering structure or the ink drop 13 as light beam L4 and which portions are totally reflected as light beam Ls at the interface 16.

[0057] The angles of incidence of the bundle of guided light L2 are limited upwards according to O(D = 90°-arcsin(nD / HG). At the same time, only light with an angle of incidence of at least ap = 90°-arcsin(np / nc) can enter the ink drop 13.

[0058] In order to couple light into the ink droplet 13, the refractive index np of the ink droplet 13 must therefore be greater than the refractive index no of the cover layer (np > no ).

[0059] The refractive index no can also be used to set the angle range between OD and a ma x, the light beam L4 enters the ink droplet 13. At a shallow angle of incidence in the range 0° to OD, it is totally reflected as a light beam Ls. The light beam Ls is therefore not coupled out of the glass pane 8.

[0060] The individual ink droplets 13 have, for example, shapes such as those shown by way of example in Figs. 3 to 6. The surface of a cured ink droplet 13 has a curved profile at least at the edges of the ink droplet 13, or the ink droplet 13 as a whole assumes, for example, an approximately plano-convex shape, a hemispherical shape, or the shape of a semi-ellipsoid. This shape of the ink droplet 13, together with the different refractive indices np and n0, results in an optical lens effect of the ink droplet 13.

[0061] The distortion of a printed structure or ink droplet13, which can be described, for example, as a piano-convex lens, can be estimated using the lens grinder formula: D = (np - n0) / n0 / R, where R is the radius of the printed structure or ink droplet (see Fig. 4). The lens effect of the ink droplet13 thus increases linearly with increasing refractive index np.

[0062] When viewing the vehicle's surroundings through the glass pane 8 of the vehicle's glazing, optical distortions can occur due to the lens effect. To avoid such distortions, when printing many individual, spaced-apart ink droplets 13, which preferably have a size or diameter in the range of approximately 0.04 mm to approximately 0.08 mm, and preferably from approximately 0.05 mm to approximately 0.07 mm, and in particular approximately 0.07 mm, and a mutual spacing of, for example, 0.1 mm or less, the individual ink droplets 13 are no longer recognizable to the eye as such individual ink droplets 13. Rather, an area with such small ink droplets 13 is perceived as a closed or closed printed surface. The individual ink droplets 13 act like microlenses, scattering the light over a wide area when they strike the strongly curved surface of the ink droplets 13.This creates haze or turbidity (schematic representation in Fig. 5). Light components that pass through the spaces between the ink droplets 13 and do not hit the ink droplets 13 are transmitted undisturbed. The image seen by the viewer through the glass pane 8 or the vehicle glazing is thus a superposition of an undisturbed image with an image blurred due to light scattering, but essentially without optical distortion.

[0063] The desired avoidance of distortions can thus be achieved with a print 11 having a light-scattering structure with individual ink drops 13, wherein the refractive index HG of the glass pane 8, the refractive index np of the print 7 or the ink drops 13 and the refractive index no of the cover layer 10 are in the ratio HG > no and np > no according to the invention.

[0064] Each individual ink droplet 13 is expediently formed approximately in the shape of a semi-ellipsoid (Fig. 6). The ink has a viscosity such that, when applied to the glass pane 8, in particular using a digital printing process, the ink prints an ink droplet 13 shaped in this way onto the glass pane 8. The shape of the semi-ellipsoid is further determined by the speed of the ink upon impact with the glass pane 8 and by the curing speed of the ink or of the ink droplet 13 upon drying of the ink droplet 13. These parameters are defined such that the ink droplet 13 has the desired shape after drying and curing. The semi-ellipsoid has a diameter of its base area and a height that are in a ratio of, for example, 0.5 to 1.5.A flank angle of the ink drop 13, which is defined as the angle between a perpendicular to the glass plate 8 at the edge of the ink drop 13 and a tangent emanating from the glass plate 8 at the circumference of the semi-ellipsoid, is preferably about 5° to 10° at the base of the semi-ellipsoid or the ink drop 13 and preferably about 15° to 30° at half the height of the semi-ellipsoid or the ink drop 13.

[0065] According to a further embodiment (Figs. 7 to 9), it is provided that some of the ink droplets 13 are in mutual contact and that contact surfaces of contacting ink droplets 13 and spaces between spaced-apart ink droplets 13 are covered and filled by the cover layer 10. Contact with the cover layer 10 reduces or eliminates optical interference. The proportion of contacting ink droplets is, for example, approximately 20% across the entire print. The contacting ink droplets can be distributed evenly or irregularly. It is also possible for all ink droplets to be in contact with neighboring ink droplets in at least one area of ​​the print.

[0066] The ink is sprayed onto the glass pane 8 in such a way that ink droplets 13 are formed with a small mutual spacing in a printing area, e.g. in a grid arrangement on the glass pane 8 (Fig. 7). Depending on the nature of the ink, e.g. its viscosity, the ink droplets 13 can change their original shape and approach each other during their hardening (Fig. 8). Once the ink droplets 13 have hardened (Fig. 9), they are in mutual contact and each form common contact surfaces.

[0067] B. Cover layer 10 applied during lamination (Fig. 9) covers both the ink drops 13 and the contact surfaces and any gaps between the ink drops 13 and fills the gaps and is in intimate contact with the ink drops 13. The cover layer 10 also covers free interfaces of the ink drops 13, which could cause undesirable optical disturbances due to total reflection, so that a more homogeneous light conduction and light extraction is achieved.

[0068] According to a further embodiment (Fig.

[0069] 10) a modified structure in which the glass pane 8 preferably has a low-emission layer or low-E layer 19 on its outer or lower main surface 18. The low-E layer 19 reduces the solar energy radiated into the vehicle and the thermal radiation emitted from the vehicle interior, thereby reducing the sensation of cold among vehicle occupants. Furthermore, the outer pane 9 contains an IR-reflecting coating 21 on its inner main surface 20 and a black print 22 in the region of the side edge 7. The intermediate layer between the outer pane 9 and the inner glass pane 8 comprises, in addition to the cover layer 10, a lamination layer 23 which is bonded to the outer pane 9 and is made of, for example, dark PVB. Furthermore, a switchable film 24 (e.g. PDLC (Polymer-Dispersed-Liquid-Crystal)) is embedded between the cover layer 10 and the lamination layer 23, which is supplied with power via a contact 25.The contact 25 is connected to a power supply (not shown) via a contact area (not shown). A frame 27, for example made of PVB or TPU, surrounds the film 24 to compensate for a thickness difference at the edge of the switchable film 24. The frame 27 has approximately the same thickness as the switchable film 24. Preferably, the frame 27 is slightly thinner than the switchable film 24 and has, for example, between 98% and 85% of the thickness of the switchable film 24.

[0070] The light is coupled in from a light source, such as at least one LED or RGB LED of the lighting device 4, via an optical prism 26, which is bonded to the lower or outer main surface 18 of the glass pane 8 in an area exposed to the low-E layer. The light is coupled in, for example, according to the method known from WO 2023 031 460 A1.

[0071] Instead of or in addition to the prism 26 shown here, a different type of light coupling into the light-guiding glass pane 8 can be selected, for example irradiation of light from a light source of a lighting device, for example a top LED, directed into the light-guiding glass pane and the use of scattering units in combination with the light source, whereby the irradiated light can be reflected and / or refracted into the glass pane in such a way as to guide the light by means of total internal reflection within the light-guiding glass pane. A top LED is characterized in that it emits light essentially perpendicular to a fastening device, for example a circuit board, of the LED, ie predominantly with a radiation cone of less than 125°, in particular less than 90°, preferably less than 60°.

[0072] The edge region 5 of the glass pane 8, through which the light is coupled, thus comprises the outer side edge 7 as well as an edge strip 28 (shown and labeled as an example in Fig. 5) in the region of the lower main surface 18 of the glass pane 8. The edge strip 28 expediently has a width in the range of, for example, 0.5 cm to 10 cm. The width depends, for example, on the design of the glass pane or the laminated glass pane in the region of its side edge or edge region.

[0073] This embodiment therefore does not provide transparent vehicle glazing. The printed light-conducting glass pane 8 is generally intended for use in both transparent and non-transparent vehicle glazing with ambient lighting.

[0074] List of reference symbols

[0075] Vehicle roof 16 inner boundary surface

[0076] Roof opening 17 outer boundary surface

[0077] Vehicle glazing 18 lower main surface

[0078] Lighting device 19 Low-E layer

[0079] Edge area 20 Main area

[0080] Inside of pane 21 coating

[0081] Page margin 22 black print

[0082] Glass pane 23 Laminating layer

[0083] Outer pane 24 switchable film

[0084] Top layer 25 contacting

[0085] Printing 26 Prism inner main surface 27 Frame

[0086] Ink drops 28 border strips

[0087] side surface

[0088] light rays

Claims

Patent claims 1 . Vehicle glazing (3) with a light-conducting glass pane (8) having a print (11) and with a light coupling of light from a lighting device (4) via an edge region (5) of the glass pane (8) into the glass pane (8) and with a light coupling of the coupled-in light from the glass pane (8) by means of the print (11) of the glass pane (8), wherein the print (11) is formed as a light-scattering structure from individual ink droplets (13) and the ink droplets (13) are formed from ink printed on the glass pane (8) and wherein a polymeric cover layer (10) covers the cured ink droplets (13), characterized in that the refractive index HG of the glass pane (8), the refractive index np of the print (11) and the refractive index no of the cover layer (10) are in the ratio HG > no and np > no, in particular np > HG > no.

2. Vehicle glazing (3) according to claim 1, characterized in that the refractive indices are: np = 1.50 to 1.90, nc = 1.50 to 1.58, no = 1.48 to 1.

49.

3. Vehicle glazing (3) according to claim 1 or 2, characterized in that the individual ink drops (13) have a diameter in the range from 0.04 mm to 0.08 mm, preferably from about 0.05 mm to about 0.07 mm and in particular about 0.07 mm.

4. Vehicle glazing (3) according to one of claims 1 to 3, characterized in that the predominant number of the ink drops (13) or all of the ink drops (13) have a mutual spacing of less than 0.1 mm and in particular in the range from 0.02 mm to 0.08 mm.

5. Vehicle glazing (3) according to one of claims 1 to 4, characterized in that each individual ink drop (13) is arranged in the form of a semi-ellipsoid on the glass pane (8) and the ratio of the diameter of the base area of ​​the semi-ellipsoid to the height of the semi-ellipsoid is in a range of 0.5 to 1.

5.

6. Vehicle glazing (3) according to one of claims 1 to 5, characterized in that some of the ink drops (13) are in mutual contact and that contact surfaces of contacting ink drops (13) and spaces between spaced-apart ink drops are covered or filled by the cover layer (10) and the contact with the cover layer (10) at least reduces or excludes interfering reflections.

7. Vehicle glazing (3) according to one of claims 1 to 6, characterized in that the printing (11) has at least two areas in which the ink drops (13) are arranged at different mutual distances and / or have different sizes or diameters.

8. Vehicle glazing (3) according to one of claims 1 to 7, characterized in that it has a second glass pane or outer pane (9) which is laminated to the glass pane (8) on its side having the printing (11) by means of the cover layer (10).

9. Vehicle glazing (3) according to one of claims 1 to 8, characterized in that it is formed as a transparent laminated glass pane.

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