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 ink printed onto the glass pane (8). A polymer cover layer (10) covers the light-scattering structure. The vehicle glazing also comprises a low-E coating (19) of the glass pane (8). According to the invention, the refractive index nc of the glass pane (8), the refractive index np of the printing (11), and the refractive index no of the cover layer (10) are in the ratio ng ≥ nD and np ≥ 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, 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 from the glass pane by means of the print on the glass pane, wherein the print is formed as a light-scattering structure of ink printed from the glass pane and wherein a polymeric cover layer covers the cured ink, and with a low-E coating on the glass pane.

[0003] EP 3 702 217 A1 discloses vehicle glazing with a printed, light-conducting glass pane. The printing is done with individual ink drops that are spaced apart from each other and allow visibility through the printed glass pane. However, such printing can cause optical distortions for a viewer viewing a scene through the printed glass pane due to the lens effect of the printed structures. Such optical distortions can occur, for example, due to different refractive indices of the printing and the polymeric cover layer.

[0004] To reduce heat radiation from a vehicle, low-emission coatings (low-E coatings) that reflect heat radiation are used on the inside of the window facing the vehicle interior. Due to non-color-neutral internal reflection at the interface between the light-conducting glass and the low-E coating, the low-E coating on the glass pane leads to a lateral color drift of the light totally reflected in the light-conducting glass pane. For example, a greater attenuation of the red light component leads to an increasingly turquoise color of white light coupled into the glass pane.

[0005] The invention is based on the object of creating a vehicle glazing as mentioned above which is improved with regard to its optical properties.

[0006] The object is achieved according to the invention in the vehicle glazing mentioned at the outset 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.

[0007] Advantageous embodiments of the invention are specified in the dependent claims.

[0008] The color drift of the light totally reflected in the light-conducting glass pane depends on the angle of reflection in such a way that light components reflected at shallower angles in the glass pane exhibit greater color drift. By defining the ratio HG ä np > no of the refractive indices nc, np, and no according to the invention, it is achieved that those light components reflected at shallower angles in the glass pane, which thus exhibit greater color drift, are not coupled into the printed light-scattering structure formed by the ink droplets. Thus, the color drift is at least reduced. Optical distortions for the viewer can thus be reduced or largely avoided.

[0009] In one embodiment, the ratio of nc and np is np > nc. Based on this ratio, the intensity of the light extraction is optimized or maximized, since as the refractive index np increases relative to the refractive index nc, more light is coupled into the print by the light-conducting glass pane and extracted via the print.

[0010] Furthermore, the use of conventional clear soda-lime silicate glass typically results in a color drift toward green due to iron oxide absorption. This color drift can be largely eliminated by using low-iron glass, such as glass with a low iron oxide content of < 0.05% and especially < 0.02%.

[0011] In one embodiment, the values ​​of the refractive indices in the visible range, for example for light of 589.33 nm, are:

[0012] HG >= 1 ,5, especially in a range of 1 ,5 to 1 ,58 n D <= 1.49 and in particular in a range from 1.48 to 1.49; and np > 1.48, and in particular in a range from 1.48 to 1.9, preferably in a range from 1.48 to 1.7; and in particular

[0013] HG = 1 .51 to 1 .52, no = 1 .48 to 1 .49 and np = 1 .51 to 1 .53.

[0014] Preferred refractive indices (at a wavelength of 589.33 nm) are, for example, nc = 1.505 for glass material and no = 1.482 for PVB (polyvinyl butyral) as a cover layer. The refractive index of the light-scattering structure is preferably set in the range np = 1.482 to 1.505.

[0015] For example, light directed at shallow angles to the interface is guided in the glass pane. Light with an angle of incidence (measured to the interface) smaller than the critical angle of total internal reflection

[0016] O(D = 90°-arcsin(nD / nc) is totally reflected and guided, while light at a larger angle penetrates the cover layer, is absorbed there and is no longer guided further in the glass. The critical angle is therefore an angle between the interface and the angle of incidence of the light. A flat angle for light is understood here to be an angle that is sufficient for the effect of total reflection and is therefore less than or equal to the critical angle of total internal reflection. The cover layer consists in particular of a thermoplastic material such as PVB (polyvinyl butyral), TPU (thermoplastic polyurethane) or EVA (ethylene vinyl acetate) and can preferably be dark tinted.

[0017] Preferred refractive indices (at a wavelength of 589.33 nm) are, for example, nc = 1.505, for PVB as a cover layer no = 1.482. The refractive index of the light-scattering structure is preferably in the range np = 1.482 to 1.505.

[0018] 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(no / nc). Light with an angle greater than OD enters the printed structure in the area where the glass pane is covered by the printed structure. The penetrating fraction of the light guided in the glass pane is thus 1 - (ap / OD). The intensity of the scattered light is determined by the refractive index of the printed structure for given nc and nc.

[0019] A printed structure is a structure applied to the surface of the glass pane. The structure can be applied directly or indirectly to the surface of the glass pane. In direct application, a structure is applied to the surface of the glass pane, in particular by a printing process. Structural elements in the form of an ink are arranged on the surface of the glass pane in such a way that they form, in particular, a light-scattering, light-refracting and / or light-diffracting structure. In direct application, ink droplets are preferably applied to the surface of the glass pane. The ink droplets can be in a solid or liquid state. In indirect application, structural elements are applied to a carrier material. The structural elements are preferably formed analogously to the previously described structural elements in direct application.The carrier material is applied to the surface of the glass pane, with the structural elements applied to the carrier material being arranged on the surface of the glass pane. In one embodiment, the carrier material is removed. The structure applied directly to the surface of the glass pane and / or the structure applied to the carrier material is produced, for example, by means of preferably digital printing such as laser printing or inkjet printing, intaglio printing, and / or screen printing.

[0020] Printed structures with rounded surfaces that are not parallel to the surface of the glass create distortion when viewed through.

[0021] The distortion of a printed structure or ink droplet, which can be described as a piano-convex lens, for example, via the local radius of curvature R, can be estimated using the lens grinder formula:

[0022] D = 1 / f = (n P / n D) / R, where R is the local radius of curvature of the interface to the top layer of the printed structure or the ink droplet.

[0023] While the distortion or refractive power decreases linearly with decreasing refractive index np in the range between the refractive index nc and the refractive index n0, the intensity of light scattering decreases more than linearly. A reduction in intensity to, for example, approximately 50% results in an improvement in refractive power of only approximately 25%. By balancing the desired intensity against tolerable optical distortions, a refractive index np of the printed structure is thus adjusted.

[0024] According to a preferred embodiment, the material of the printed structure is selected such that its refractive index np is in the range np > (HG + HD) / 2. Thus, the intensity of light scattering by scattering particles introduced into the printed structure is optimized.

[0025] In a further preferred embodiment, the refractive index np of the light-scattering structure has a value of np < (HG + HD) / 2. The optical distortions are optimized such that only a small proportion of distortions is observed. According to a preferred embodiment, the ink contains scattering particles which determine the refractive index np of the print or the light-scattering structure or the ink droplets and via whose proportion in the ink the refractive index can be advantageously adjusted. The volume fraction of the scattering particles and / or the material of the scattering particles is selected for the refractive index np of the print or the ink droplets or the light-scattering structure to be adjusted. The volume fraction of the scattering particles in the ink is, for example, 5% to 50%. A volume fraction of 30% to 40% of TiO2 particles has proven advantageous.

[0026] The transparent ink consists of a UV-curing acrylic resin with particles of oxides or nitrides, such as TiO? or Al2O3, distributed throughout. Common products contain, for example, 2-phenoxyethyl acrylates or isobornyl acrylates as a base.

[0027] Since acrylic resins typically have poor adhesion to the PVB of the top layer, it may be advantageous to add adhesion promoters to the resin to improve adhesion to the PVB.

[0028] The printed structure may consist of a plurality of individual, in particular small, discrete ink drops which do not appear to be soluble to the eye and are in particular spaced apart from one another.

[0029] The ink droplets are preferably printed in a lens-shaped or semi-ellipsoidal shape. The ink has a viscosity such that when applied to the glass pane, particularly using digital printing, the ink forms a 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 it 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 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 pane at the edge of the ink drop and a tangent emanating from the glass pane 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.

[0030] The shape of the semi-ellipsoid represents an approximation to the real shape of the ink drop for the purpose of describing it. Small deviations of the ink drop from this shape can therefore be neglected for the description of the ink drop.

[0031] Furthermore, the glass pane can be provided with a second outer glass pane or outer pane, which is laminated to the side of the glass pane bearing the printing by means of the cover layer. This creates a laminated glass pane.

[0032] The outer glass pane or outer pane of a laminated glass pane can be either transparent or non-transparent. Light transmission is generally not required if the vehicle glazing is intended to provide ambient lighting. Thus, the vehicle glazing can also be transparent or non-transparent. Preferred embodiments have light transmissions (TL according to ISO 11664) of <20%, particularly preferably <10%.

[0033] The glass pane can be quartz glass, single-pane float glass, tempered glass (ESG) or heat-strengthened glass (TVG), for example, and it can also be made of a plastic such as polycarbonate.

[0034] 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.

[0035] 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 predominantly deflected at an angle that is guided in the second glass pane by total internal reflection.

[0036] 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:

[0037] Fig. 1 shows a perspective view of a vehicle with a vehicle roof having vehicle glazing;

[0038] Fig. 2 shows a schematic sectional view of a light-conducting glass pane of the vehicle glazing with light reflection in the glass pane and light scattering on a printing of the glass pane covered by a cover layer;

[0039] Fig. 3 shows a schematic sectional view of an enlarged section of the light-conducting glass pane, showing the light reflection and light scattering at the printing on the glass pane; Fig. 4 shows a schematic sectional view of the light-conducting

[0040] Glass pane with reflected light transmission and with light scattering on the printing of the glass pane; and

[0041] Fig. 5 shows a schematic sectional view of another embodiment of the vehicle glazing.

[0042] 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.

[0043] 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, TPU, 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.

[0044] The lighting device 4 (shown schematically as a light source in Fig. 2) 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.

[0045] The glass pane 8 has a low-emission coating or low-E coating 19 on its outer or lower main surface 18. The low-E coating 19 reduces the solar energy radiated into the vehicle and the thermal radiation emitted by the vehicle interior, thereby reducing the sensation of cold among vehicle occupants.

[0046] The glass pane 8 has a refractive index HG of preferably 1.505. The print 11 or the scattering structure or the ink droplet 13 has a refractive index np of 1.485 to 1.505 and in particular 1.50. The cover layer 10 has a refractive index n0 of in particular 1.485.

[0047] 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 interfaces 16 and 18. The critical angle (measured between the light beam and the interface) of total internal reflection is determined by a D = 90°-arcsin(n D / n G ). For n D = 1 ,485 and n G = 1 ,505 the critical angle a D = 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.

[0048] 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. They are coupled out as scattered light via the lower main surface 18 toward the vehicle interior. This creates ambient lighting.

[0049] The printing 11 on the glass pane 8 is carried out with a transparent ink using inkjet digital printing. The preferably UV-curing ink contains a mixture of, for example, monomers, oligomers, photoinitiators, additives, and scattering particles. The printer sprays the ink onto the glass pane 8 in very small, spaced-apart droplets. Preferred resolutions for this digital printing are in the range of 100 dpi to 1000 dpi (dots per inch), and particularly preferably in the range of 360 dpi to 450 dpi.

[0050] In one embodiment, adjacent droplets flow into each other after printing and form a common printing surface on the glass pane 8. These adjacent droplets are therefore no longer distinguishable separately or individually. This behavior depends on the surface tensions of the ink and the glass pane.

[0051] When the ink is printed onto the glass pane 8, the resulting ink droplets 13 are irradiated with UV light to trigger the polymerization of the ink and cure the ink droplets 13. The UV light source is typically a special lamp that emits UV light at a specific wavelength tailored to the ink to achieve optimal curing. Curing can occur very quickly, usually in a few seconds. The scattering structures or ink droplets 13 can be printed over the entire printing area, e.g., in a uniform grid pattern. The ink droplets 13 can also be printed according to a desired design such that they are printed in the form of a pattern, e.g., with different sizes of ink droplets 13 and different spacing between the ink droplets. The ink droplets 13 can also be printed in different thicknesses or heights, as well as in different sizes or diameters.

[0052] The sizes or diameters of the scattering structures or the ink drops 13 are preferably in the range from 0.035 mm and in particular in the range from 0.035 mm to 0.15 mm.

[0053] The refractive index np of the scattering structures or the ink drops 13 results from a mixture of the refractive index of the matrix of the ink and the refractive index of the scattering particles contained in the ink.

[0054] By selecting the material of the matrix of the ink with the refractive index HM and the scattering particles with the refractive index HB as well as the volume fraction of the scattering particles in the ink, the refractive index np of the scattering structures is set in the range between HM and HB.

[0055] The ink used in UV-curable inkjet printing contains an ink mixture of monomers, oligomers, photoinitiators, and additives. These components create a liquid ink that is printed onto a substrate such as glass and rapidly cured with UV light. The monomers and oligomers are the essential components of the ink and form the majority of the ink's physical properties. Photoinitiators are added to the ink to initiate the curing process upon exposure to UV light. Additives can be added to improve ink adhesion, print quality, and other properties. Some common materials used for UV-curable inkjet inks include acrylates, epoxies, urethanes, and polyesters.The refractive index of UV-curing inkjet printing inks varies depending on the composition of the ink and the materials used and is generally in the range of approximately 1.40 to 1.60.

[0056] In order to achieve light scattering on the ink droplets, scattering particles are added to the ink mixture. These scattering particles have a greater refractive index difference than the surrounding matrix or liquid of the ink. These scattering particles can be made of various materials. Some examples of scattering particles and their refractive indices are: silicate (n = 1.50 to 1.54), titanium dioxide (n = 2.35 to 2.55), barium sulfate (n = approximately 1.64), and calcium carbonate (n = 1.48 to 1.66). By adding scattering particles that scatter in the visible wavelength range, the light is scattered in the ink droplets, creating diffuse ambient lighting. The size, shape, and distribution of the scattering particles influence the intensity and type of light scattering. It should be noted that an increased concentration of scattering particles can increase the viscosity of the ink and impair print quality.

[0057] The dielectric constant of the scattering structure can be calculated, for example, according to the Maxwell-Garnett theory from the dielectric constants of the matrix £ m and the inclusions a and the volume fraction öi of the inclusions:

[0058] For non-magnetic materials, the dielectric constant is equal to the square of the refractive index.

[0059] For example, for a matrix made of acrylate-based UV resin with n = 1.4, Σ = 1.96, and with the addition of TiO2 particles with TiO2 n = 2.6, Σ = 6.76, a refractive index np of the print or ink can be adjusted from 1.4 to 2.6, depending on their volume fraction. In one embodiment, the edge-side light coupling can be configured such that light coupling occurs within the vehicle glazing 3, for example, in the case of a laminated glass pane, by means of a lighting device 4 arranged within the laminated glass pane, and / or via an arrangement of the lighting device 4 at one of the interfaces 16, 17.

[0060] The light guided in the light-guiding glass pane 8 is, as explained above, limited by the critical angle α of total internal reflection. 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. It penetrates the cover layer 10 as light beam L3 if it is incident at a steeper angle, i.e., at an angle α greater than the critical angle.

[0061] 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.

[0062] 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 at least the angle of incidence ap = 90°-arcsin(np / nc) can enter the ink drop 13.

[0063] 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).

[0064] The refractive index np can also be used to set the angle range between ap and a max the light beam L4 enters the ink droplet 13. At a shallow angle of incidence in the range 0° to ap it is totally reflected as a light beam Ls. The light beam Ls is therefore not coupled out of the glass pane 8. The light guided in the glass pane 8 (see Fig. 4) is reflected at the interface 16 to the cover layer 10 and at the interface 17 to the low-E layer 19. On its way to the ink droplets 13 the light is reflected multiple times. With each reflection at the low-E layer 19 the light is reflected depending on the angle of incidence and the wavelength. Due to color-inhomogeneous reflection at the low-E layer 19 color shifts occur, which become more pronounced with each further reflection at the low-E layer 19.For example, if an RGB LED of the lighting device 4 emits white light as a combination of red, green, and blue, and less red is reflected than green or blue during reflection, then turquoise light, rather than white light, is scattered and emitted when the light is coupled to the ink droplets 13. Such color shifts should at least be reduced or completely avoided.

[0065] Experimental results and an optical simulation of internal reflection at the low-E layer 19 show that the inhomogeneity in spectral reflection increases significantly with shallower angles of incidence. It is therefore advantageous not to couple incident light into the printed structure at shallow angles of incidence, e.g., < 3°.

[0066] According to the invention, the refractive index np of the ink droplets 13 is adjusted via the volume fraction and the material of the scattering particles such that only light L4 enters the ink droplets 13 at larger reflection angles. Light impinging on the interface at shallow angles is filtered out, so that color drift is at least reduced.

[0067] The greater the proportion of light coupled into the ink droplets 13, the brighter the ink droplets 13 or the light-scattering structure glows. The dependence of the intensity of the light coupling on the refractive index np of the scattering structure or the ink droplets 13 shows that it is advantageous to couple as much light as possible. The ratio of the coupled light L4 to the uncoupled light Ls is determined by the refractive indices np and n0. It can be seen that for np >= CIG, maximum light coupling occurs, and for np = n0, no light is coupled.

[0068] For a high intensity of the ambient lighting, it is therefore advantageous to set a refractive index np of the ink drops 13 or the printing 11 that is large compared to the refractive index no of the cover layer 10 (np > no).

[0069] Thus, according to the invention, a balance between high intensity and reduced color drift leads to a determination of the refractive index np of the scattering structure or of the ink drops 13 of the print 11 between the refractive index nc of the glass pane and the refractive index no of the cover layer 10.

[0070] According to a further embodiment (Fig. 5), the vehicle glazing comprises a modified structure in which the outer pane 9 has 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 black print 22 conceals the lighting device 4 arranged there at the edge region and blocks unwanted light from the lighting device 4. The intermediate layer between the outer pane 9 and the inner glass pane 8 comprises, in addition to the cover layer 10, a laminating 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 laminating layer 23. A frame 27, for example made of PVB or TPU, surrounds the film 24 in order to compensate for a difference in thickness at the edge of the switchable film 24.The switchable foil 24 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).

[0071] 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. At least one of the cover layer 10, the lamination layer 23, or the switchable film 24 can have a low light transmission in order to achieve a total transmittance TL of <20% or <10%.

[0072] 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 resection 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°.

[0073] 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.

[0074] In principle, the printed light-conducting glass pane 8 is intended for use in both transparent and non-transparent vehicle glazing with ambient lighting. 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), 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 light out of 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 ink printed on the glass pane (8) and wherein a polymeric cover layer (10) covers the light-scattering structure, and with a low-E coating (19) of the glass pane (8), characterized in that the refractive index nc 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 nc > no and np > no.

2. Vehicle glazing (3) according to claim 1, characterized in that the refractive indices measured at 589.33 nm are: nc >1 ,5, no < 1 ,49 and np >1 ,48, in particular nc >1 ,5 and no < 1 ,49.

3. Vehicle glazing (3) according to claim 1 or 2, characterized in that the ink contains scattering particles which determine the refractive index np of the printing (11) or of the light-scattering structure, and in that the volume fraction of the scattering particles for the refractive index to be set cation index np of the printing (11) or the light-scattering structure is selected, and that the volume fraction of the scattering particles is greater than 20% and preferably lies in the range of 20% to 50%.

4. Vehicle glazing (3) according to one of claims 1 to 3, characterized in that the light-scattering structure is formed from individual ink drops (13) which are in particular spaced apart from one another.

5. Vehicle glazing (3) according to claim 4, characterized in that the individual ink drops (13) have an average diameter in the range of 0.05 mm to 0.1 mm.

6. Vehicle glazing (3) according to claim 4 or 5, characterized in that the ink drops (13) are printed in a lens-shaped manner or in the form of a semi-ellipsoid.

7. Vehicle glazing (3) according to one of claims 1 to 6, characterized in that the glass pane (8) provides a laminated glass pane with a second outer glass pane (9) which is laminated on the side of the glass pane (8) having the printing (11) by means of the cover layer (10).

8. Vehicle glazing (3) according to one of claims 1 to 7, characterized in that the glass pane (8) is formed from a low-iron glass with an iron oxide content of < 0.05% and preferably < 0.02%.

9. Vehicle glazing (3) according to one of claims 1 to 8, characterized in that an intensity of the light coupled out at the light-scattering structure is optimized by setting the refractive index of the light-scattering structure according to np > (HG + HD) / 2.

10. Vehicle glazing (3) according to one of claims 1 to 9, characterized in that optical distortions at the light-scattering structure when light passes through the vehicle glazing (3) are optimized by setting the refractive index of the light-scattering structure according to np < (nc + no) / 2.

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