WO2010034527A1

WO2010034527A1 - Optical fiber arrangement for illuminating a motor vehicle license plate fastened to a motor vehicle, and method for the production thereof

Info

Publication number: WO2010034527A1
Application number: PCT/EP2009/053693
Authority: WO
Inventors: Wolfgang Bilger; Lothar Wurmbach; Bernd Pfundstein
Original assignee: Erich Utsch Ag
Priority date: 2008-09-26
Filing date: 2009-03-27
Publication date: 2010-04-01
Also published as: DE102008049256A1

Abstract

The present invention relates to an optical fiber arrangement (5) for illuminating an optionally retroreflective motor vehicle license plate (2) fastened to a motor vehicle. The arrangement comprises a transparent optical fiber (80) extended in planar fashion, said fiber having a front-side light transmission surface (81) and a rear-side light transmission surface (83). At least one light source (22), the light of which is coupled into the optical fiber (80) and guided in said optical fiber, is coupled out of said optical fiber to illuminate the retroreflective motor vehicle license plate (2) arranged in front of or behind the optical fiber arrangement (5). The optical fiber (80) comprises structures (90) for coupling out light, said structures being arranged in the area of a light transmission surface (83) and being characterized in that the structures (90) for coupling out light comprise a plurality of raised or recessed column structures, which have the following characteristics: i) a longitudinal axis X, which is oriented substantially perpendicular to the light transmission surface (83), ii) one or more lateral surfaces, which are also oriented substantially perpendicular to the light transmission surface (83).

Description

Designation: Optical fiber arrangement for illuminating a license plate attached to a motor vehicle and method for the production thereof

The present invention is an optical fiber assembly for illuminating a mounted on a motor vehicle, possibly retroreflective license plate, a mounting device for mounting a retroreflective license plate on a motor vehicle a retroreflective shield assembly, a vehicle with a holding device for a retroreflective license plate license plate and a method for producing a light guide arrangement according to the invention.

Optical fiber assemblies for illuminating a retroreflective license plate mounted on a motor vehicle are well known in the art. For example, DE 102 58 465 A1 discloses a light guide arrangement which is intended to be arranged in front of a non-transparent license plate in order to illuminate it. The optical waveguide arrangement has an extensively extended optical waveguide which extends substantially parallel to the surface of the license plate to be illuminated, wherein the light coupled into the optical waveguide is guided by internal total reflection in the optical waveguide. To decouple light from the light guide, a scattering layer is provided on the surface of the light guide, which consists of two materials with significantly different refractive indices, for example, of high refractive index plastic particles in a low refractive index plastic matrix. Although the light guide assembly disclosed here is basically suitable for illuminating a license plate with a non-transparent board so that it can be read well even under unfavorable lighting conditions. However, it is not suitable for illuminating a retroreflective license plate while maintaining sufficient retroreflective values. The transmission of the light guide assembly is due to the design in a relatively low range, so that a arranged behind the light guide assembly retroreflective license plate no longer achieves sufficient retroreflective values.

EP 1 477 368 A1 discloses an optical waveguide arrangement for illuminating a motor vehicle license plate which is fastened to a motor vehicle and which is intended to illuminate a transparent retroreflective license plate. In connection with the optical fiber arrangement disclosed here, it is not discussed that a degree of transmittance of the optical waveguide device can be obtained in a soft manner. tion can be achieved, which would allow an arrangement of the light guide assembly in front of the retroreflective license plate. However, this is absolutely necessary if it is a non-transparent license plate, such as a license plate with a metallic plate or with a board made of an opaque plastic.

Finally, DE 10 2007 015 747 A1 teaches a light guide arrangement for illuminating a retroreflective license plate fastened to a motor vehicle. This optical fiber arrangement has such transmission values that it can also be arranged in front of a retroreflective license plate without unduly reducing its retroreflective values. However, the anisotropic coupling-out structures disclosed in this application have disadvantages in their production because of their geometry.

It is therefore an object of the present invention to provide a light guide assembly for illuminating a mounted on a motor vehicle retroreflective license plate, wherein the light guide assembly has such a high transmission that it can be easily arranged in front of a retroreflective license plate without its retroreflectivity to diminish in an inadmissible way. At the same time a sufficient and in particular homogeneous illumination of a legend of the license plate is to be ensured.

It is another object of the present invention to provide a mounting device for mounting a retroreflective license plate on a motor vehicle, which allows a homogeneous illumination of a license plate with retroreflective, possibly also optically opaque board, at the same time not the retroreflective values of the held license plate should be reduced in an inadmissible way. It is another object of the present invention to provide a lighted retroreflective automotive license plate assembly comprising a license plate with a sufficiently bright and homogeneously illuminated shield plate, in particular license plate legend. At the same time, the shield arrangement should fulfill the legally prescribed retroreflective values. A further object of the present invention is to provide a motor vehicle with a holding device for a retroreflective license plate, wherein the holding device should further comprise a lighting device that is to enable the illumination of a retroreflective, possibly optically opaque license plate without the retroreflective values of the held License plate inadmissible to influence.

Finally, the object of the present invention is to specify a method for producing a light guide arrangement for illuminating a retroreflective license plate fastened to a motor vehicle, which may possibly also be optically opaque.

This object is achieved by a light guide assembly according to claim 1, by a mounting device according to claim 26, by an illuminated retroreflective license plate assembly according to claim 27, by a motor vehicle according to claim 28 and by a method according to claim 29.

An optical waveguide arrangement according to the invention is intended to illuminate a vehicle-mounted retroreflective license plate, in particular a license plate with a non-transparent, for example metallic, board. The optical waveguide arrangement has a planarly extended transparent optical waveguide with a frontal light passage area and a rear passage area. Furthermore, at least one light source is provided, whose light is coupled into the optical waveguide and guided therein. The guided in the light guide light is coupled out to this for the illumination of the arranged before or behind the light guide assembly retroreflective license plate. For this purpose, the optical waveguide has light outcoupling structures arranged in the region of a light passage surface.

According to the invention, these light extraction structures are now formed in a plurality of raised or recessed column structures, each having a longitudinal axis X. This longitudinal axis is oriented in each case substantially perpendicular to the light passage surface on which the columnar structure is arranged. Finally, the raised or recessed column structures according to the invention have at least one or more lateral surfaces, which are oriented substantially perpendicular to the light passage surface. Such a configuration of the pillar structures has proved to be extremely advantageous with respect to the achievable transmission values through the light guide. An optical waveguide which is equipped with the light coupling-out structures according to the invention has a transmission which is only insignificantly reduced compared to a light waveguide with planar light transmission surfaces. This applies in particular to an irradiation of the radiation to be transmitted in an angular range of less than 45 ° with respect to the surface normal of the light passage surfaces. This has the immediate result that a arranged behind a light guide retroreflective license plate according to the invention undergoes only an insignificant weakening of its retroreflectivity despite twice the passage of light through the surfaces of the light guide.

In a preferred embodiment, the height or depth h of the pillar structures relative to the light transmission surface on which they are placed is in the range of 1 to 100 microns, with a range of between 5 and 25 microns having been found to be most suitable and the best practical results were achieved with a height or depth h which was about 10 microns.

In a further preferred embodiment, the raised or recessed column structures have a base area A at the light passage area to which they are arranged whose size is in the range between 50 and 50,000 square micrometres. Particularly preferred here is a range between 100 and 25,000 square micrometers, with a size of about 7,850 square microns has proven particularly useful.

The aforementioned light extraction structures can be produced in processes that are easy to control. Thus, particularly good results could be achieved with optically highly transparent light guides having a thickness of about 2.5 mm of polymethyl methacrylate (PMMA), in one surface of which the columnar structures according to the invention were molded, for example by means of LIGA technology (lithography, electroplating & impression). In the context of the LIGA technique, which is well known from the prior art, a structured mask having a possibly extremely high aspect ratio is produced by means of suitable lithographic techniques, for example by means of X-ray or UV lithography is subsequently molded by means of a galvanic deposition in a metal die. This metal matrix then serves as a template for the impression of the structure in a final plastic structure. By means of the LIGA technique, it is thus possible to provide a correspondingly structured injection-molded plastic mold, into which half-mold corresponding column-like raised or recessed master structures are introduced. In a suitable plastic injection molding process then optical fibers can be made for example of PMMA or transparent polycarbonate or polyethylene, in one surface then the aforementioned raised or recessed columnar structures are formed. The light guides produced in this way have an extremely high transparency in the optical wavelength range, so that they can be easily arranged in front of a retroreflective license plate without unduly reduce its retroreflectivity. At the same time, the columnar structures formed in the optical waveguide surface represent scattering centers for the light guided in the optical waveguide by internal total reflection, the light output ratio can be reproducibly adjusted by the concrete shape of the columnar structures, by their dimensions and by their density and arrangement on the light guide surface.

One parameter with which the achievable light output ratio can be influenced is the height or depth h of the light extraction structures relative to the light transmission surface on which they are arranged. In a particularly simple manner, light coupling-out structures can be produced, which essentially have a uniform height / depth h over the entire area of the light passage surface of the light guide. Nevertheless, under certain circumstances, it may be advantageous if the height or depth h of the light coupling-out structures varies locally, for example in order to suppress the formation of light halos in those regions of the light guide that are directly adjacent to the light sources.

Another parameter that significantly influences the locally achievable light output ratio is the size A of the base area of the light output structures. Again, in many cases, the size A of the base surface of the coupling-out structures will be essentially constant over the entire light passage area on which the light coupling-out structures are arranged. But here too can Under certain circumstances, it may be advantageous if the size A of the base area of the light coupling-out structures on the light passage area varies locally, for example in order to avoid the formation of light spots in the vicinity of the light sources. In addition to the height or the depth h of the light coupling-out structures or the size A of the base surface of the light coupling-out structures, the locally achievable light output ratio is also determined by the local density of the light coupling-out structures on the light passage surface. Again, it is readily possible to keep the density of the Lichtauskoppelstrukturen on the light passage surface substantially constant over the entire surface of the light passage surface of the light guide substantially. However, a locally varying density will be provided here in most applications, as can be minimized by means of this measure in a particularly simple manner, for example, the formation of light yards in the vicinity of light sources. On the other hand, the light intensity steadily decreasing along the running direction of the light guided in the optical waveguide can be compensated by a local increase in the degree of light output, so that overall a homogeneous illumination of the illuminated license plate is achieved. For this purpose, the density of the light coupling-out structures on the light passage surface is locally varied in such a way that it is lowest in that region of the light passage surface which adjoins the at least one light source. Due to the fact that the light output structures to be provided according to the invention also have only a practically negligible influence on the transmission of the light guide arrangement, such a locally varying density of the column structures does not lead to irregularities in the retroreflective image of the held license plate. Another parameter that determines the achievable local Lichtauskoppelgrad is the concrete shape of the invention to be provided Lichtauskoppelstrukturen. In a particularly preferred embodiment, these have a substantially constant cross section along their longitudinal axis X, for example a round cross section or a cross section in the shape of a polygon (3-corner, 4-corner, 5-corner, 6-corner, 7-corner, etc .), so that one obtains essentially columnar structures. However, it is also possible to produce coupling-out structures whose cross section tapers along its longitudinal axis, ie the columnar structures have the largest cross-sectional area A in the region of the light passage area on which they are arranged. Another variable that influences the local light output ratio is the arrangement of the coupling-out structures on the Lichtdurchtrittsf laugh relative to each other. Here, it has proven useful to realize a regular arrangement of the light coupling-out structures, for example in the form of a hexagonal or square grid, since the LIGA masks required for this purpose can be produced in the simplest manner. Somewhat more difficult to fabricate in the LIGA masks, but more flexible in the adjustment of the locally achievable Lichtauskoppelgrads is an arrangement of Lichtauskoppelstrukturen the light passage surface, which is substantially stochastic. Here too, local inhomogeneities in the density of the light coupling-out structures on the light passage surface can be provided such that, for example, the density of the light coupling-out structures is smallest in that region which adjoins the at least one but preferably a multiplicity of light sources. In addition, a stochastic distribution of the column structures on lattice sites of a regular grid is possible.

If outcoupling structures are used which have a substantially isotropic shape, ie are formed as pillar structures with a constant or tapering cross-section, the result is usually a light output ratio independent of the running direction L of the light guided in the light guide, which may be advantageous in practice , However, if a direction of light L dependent Lichtauskoppelgrad desired, which may also be advantageous under certain circumstances, this can be adjusted by the Lichtauskoppelstrukturen be formed anisotropic. For this purpose, the light extraction structures, for example, transversely to the direction L of the light in the light guide have a greater extent than in the direction L. If isotropic Auskoppelstrukturen needed, they preferably have a round base surface or a base surface in the form of a regular polygon. If, on the other hand, anisotropic light extraction structures are required, then they can have, for example, an elliptical base surface. In the latter case, the anisotropic Lichtauskoppelstrukturen it has proved to be beneficial if the extension of the Lichtauskoppelstrukturen transverse to the direction L of light guided in the light guide at least by the light factor 1.5, but preferably by a factor of 3 and in particular by a factor of 10 are greater than the dimensions of the Lichtauskoppelstrukturen in the direction L. Furthermore, it has proven in anisotropic Lichtauskoppelstrukturen when the running direction L of the light guided in the light guide when properly mounted the Optical fiber assembly is oriented on the motor vehicle substantially perpendicular to the horizontal.

It has already been mentioned above that the optical waveguide can advantageously be produced from a transparent plastic, whereby the special suitability of polymethyl methacrylate (PMMA) has already been pointed out. Extensively extended optical fibers made of PMMA can be produced excellently by injection molding. In addition, they have a very high visual transparency in the visible range and excellent aging properties under environmental influences. Furthermore, polycarbonate is basically suitable as a material for a light guide according to the invention, wherein it must be noted that on the one hand the achievable transparency in the visible spectral range is lower and on the other hand polycarbonate usually has a less high UV resistance. This can be compensated either by embedding UV-stabilizing components in the polycarbonate plastic matrix or by applying an additional UV filter, for example in the form of a separately formed UV protective screen or a UV protective coating on the surface of the polycarbonate optical fiber.

If plastics are used for the optical waveguide arrangement, the coupling-out structures can advantageously be formed integrally with the optical waveguide, for example by means of molding the structures into the optical waveguide in the production of the optical waveguide by injection molding. But also an introduction of the corresponding Lichtauskoppelstrukturen in the at least one light passage surface of the light guide by means of a stamping process is readily possible. If the LIGA technique for producing the injection mold for the light guide is used, the light extraction structures produced generally have plane surfaces. Under certain circumstances, it may be advantageous to change the shape of the flat surfaces. For this purpose, for example, a thermally activated, locally acting on the surfaces of the Lichtauskoppelstrukturen forming process can be used, which is performed on the already shaped columnar raised structures. For this purpose, the highest lying areas of the columnar structures are heated for a short time, whereby the viscosity of the plastic material decreases sharply, so that a flow process gets going. Due to the surface tension acting on the surface of the liquefied plastic, the column surfaces then become spherical Structures that significantly change the optical properties of the columnar structures. Further information on this forming process can be found, for example, in DE 10 2007 015 747 A1, the disclosure of which is incorporated by this reference in its entirety into the disclosure of the present application.

If light-outcoupling structures are used, as described above in full, it has proven to be advantageous if these light-outcoupling structures as a whole cover a proportion of not more than 25% of the surface area of the light passage area in whose area they are arranged. Higher transmission values can be achieved if the proportion does not exceed 10%. In practical tests, in particular a share of at most 5% has proven to be advantageous. Unless otherwise indicated, the density of the light extracting structures given in percent refers to the ratio of the area covered by the totality of the light coupling-out structures to the total size of the light passing area of the optical waveguide on which the light coupling-out structures are arranged.

In a particularly preferred embodiment, the light extraction structures are formed as recessed columnar structures with, for example, round cross-section. Other cross sections are possible. The columnar structures are characterized in that their longitudinal axes are oriented perpendicular to the surface of the light guide. Furthermore, it has been found that the transmission through the optical waveguide with vertical incidence with respect to the smooth optical waveguide surface is particularly little disturbed if the lateral surfaces of the columnar structures are also substantially oriented as well as their lateral surfaces perpendicular to the surface of the optical waveguide. A deviation of less than 15 ° from the vertical, preferably less than 5 ° from the vertical, and in particular less than 2 °, gives particularly good results in terms of transmission through the optical fiber, which is useful for weakening the retroreflection of the underlying retroreflective automotive License plate is essential. In practice, it is advantageous if the smallest possible angle of inclination of the lateral surface is set against the vertical on the optical waveguide surface, which is practically feasible within the framework of the light outcoupling structure formed for the optical waveguide. The depth of these columnar recessed Lichtauskoppelstrukturen is dimensioned so that up to an illumination angle of max. 30 ° to the vertical of the light guide / license plate surface, the transmission through the light guide is weakened as little as possible. In national approval procedures, a minimum value for the retroreflectivity of a license plate or an entire license plate assembly is often defined. If a commercially available retroreflective sheeting is to be used for the retroreflective license plate, in particular a sheeting of a type which is also suitable for a retroreflective license plate without an overlay (reflection) optical fiber and therefore has not too high retroreflectivity the optical waveguide necessarily have a high transmission, which also extends substantially over the entire range of illumination angle to be tested. In the German national approval procedure, it has proved sufficient for the use of a light guide according to the invention for a conventional, the provisions of the StVZO appropriate retroreflective characteristics, if the retroreflection is reduced by not more than 30%. This means that the reflection and scattering losses during a single pass through the light guide must not be significantly above 15% for all the illumination angles to be tested.

In this context, it has proven to be advantageous if the columnar recessed Lichtauskoppelstrukturen have only a relatively small depth. For structures having a diameter in the region of 100 micrometers, this is in the range of approximately 10 micrometers, in particular if the structures have a round, polygonal or elliptical cross-sectional area. For such structures, a balanced relationship between Auskoppelgrad from the light guide, transmission through the optical fiber and contrast of lying behind the light guide license plate legend results in a surface portion of the structures in the range between 5% and 20%, preferably from about 10%.

The abovementioned structures can advantageously be molded in during the production of the light guide, which is produced by injection molding. For this purpose, a lithographically produced embossing or shaping mask, which is furthermore advantageously coated with bright nickel, is incorporated in the embossing or shaping mask used to produce the light guide. turned used injection mold. The PMMA material proved to be particularly suitable for the optical waveguide because of its low optical density and the low viscosity products available, which are advantageous for injection molding of the optical waveguide. Particularly suitable is the special material of the class PMMA (polymethyl methacrylate), which is marketed by the company GE Bayer Silicones under the name "PMMA 8 N crystal clear".

Preferably, the Lichtauskoppelstrukturen are formed on that side of the light guide, which is oriented towards the illumination of a license plate to this. However, they can also be formed in the surface of the light guide facing away from the shield and on both surfaces of the light guide, possibly with different densities, shapes and dimensions.

Surprisingly, it has been found that particularly advantageous properties of a light elite, in particular of the type described above, result if at least the light guide surface in which the recessed light outcoupling structures are formed is covered with a sufficiently thin, optically transparent coating. Particular advantages arise when the coating in the μm range achieves a smoothing of the recessed light output structures generated by the impression. In this way undesirable point-like "spots" (ie undesirably high local light outcouplings at the depression) can be avoided Moreover, the overlaying with the abovementioned coating leads to an "angling" of the lateral surfaces of the light coupling-out structures which are advantageously oriented perpendicular to the light guide surface, which has the consequence in that light is increasingly coupled out of the fiber optic plane to the license plate.

This coating can be advantageously combined with an anti-scratching coating to make the light guide more suitable for outdoor use. Here, the material offered by the company GE Bayer Silicones under the name "scratch protection coating SHC 5020" has proven particularly useful.

Advantageously, the mentioned coating is applied at least on that side of the light guide in which the recessed light extraction structures are formed. are det, but preferably on both sides of the light guide. As a layer thickness, a thickness range of 1 to 15 micrometers has been found to be particularly suitable, in particular from 5 to 10 microns. If the material SHC 5020 is used, then a layer thickness in the range of about 6 micrometers has proven particularly suitable.

The coating is particularly simple when a liquid starting material is used for coating, such as the material SHC 5020. Such a method can be applied to the surface / s of the light guide in the simplest manner in a flooding process. Application by spray is also possible. A double-sided coating is advantageously produced by means of the so-called "dip-coating".

Possibly. For example, the one-sided / two-sided overlaying of the optical waveguide with the above-described coating, which may in particular be a transparent scratch-resistant coating, can be supplemented for the top-side application of a suitable antireflection coating, which is known in numerous numbers in the prior art. In connection with the light guide according to the invention, the application of an AR coating by flooding or by means of dip coatings is preferred. Of course, however, other coating methods known from the prior art can also be used for applying the AR coating.

The claimed further claimed in the present application illuminated retro-reflective license plate license plate assembly comprises a retroreflective license plate with a planar expanded shield plate, in particular a non-transparent shield plate. In particular, it may be a license plate with metallic plate, which is front laminated with a retroreflective sheeting and in which the legend legend in the form of raised or recessed alphanumeric characters is mechanically imprinted. Furthermore, the illuminated retroreflective license plate assembly according to the invention comprises a light guide arrangement according to the invention already explained above, wherein the light guide of this light guide arrangement is preferably arranged on the front side of the planar expanded shield plate to illuminate the legend of the retroreflective license plate. The further claimed mounting device is provided for mounting a retro-reflective license plate on a motor vehicle, such a retroreflective license plate may be, for example, today already used license plate with metallic plate, which front surface with a retroreflective sheeting laminated, wherein the license plate legend may be embossed, for example in the form of raised or deepened alphanumeric characters in the metallic circuit board. The mounting device according to the invention comprises a holder, which is intended to hold the retroreflective license plate with its planar expanded shield plate, wherein the holder is further intended to be attached to a motor vehicle. In this case, held in the holder retroreflective license plate is to be set mechanically on the motor vehicle. For example, reference is made to DE 20 201 853 Ul, which discloses a suitable holder based on a plastic material. But also from DE 10 2005 035 232 Al a holder for a license plate is known, which is particularly suitable, in addition to a retroreflective license plate with metal plate, for example, even a light guide to take in the front side of the license plate is. The mounting device furthermore comprises an optical waveguide arrangement according to claim 1, which has already been discussed in detail above. The disclosure content of DE 10 2005 035 232 A1 is also fully incorporated by this reference into the disclosure of the present application.

Furthermore, protection is claimed for a motor vehicle having a lighted fixture for a retroreflective license plate, said fixture comprising a license plate receptacle adapted to hold a retroreflective license plate with a planar, e.g. metallic, shield plate. The license plate holder sets the retroreflective license plate mechanically on the motor vehicle. Furthermore, the holding device provided on the motor vehicle comprises a light guide arrangement according to claim 1, which has already been discussed in detail above, wherein the optical waveguide of the light guide arrangement is arranged on the front side of the retroreflective license plate of the retroreflective license plate when the retroreflective license plate is held in the license plate holder. The method, which is also the subject of the present invention, is used to produce a light guide arrangement for illuminating a vehicle-mounted, optionally retroreflective license plate. It has at least the following process steps:

1. Providing at least one light source

2. Provision of a planarly extended transparent light guide having a front light passage surface and a rear passage surface, wherein the light guide in the region of a light passage surface arranged Lichtauskoppelstrukturen consisting of a plurality of raised or recessed column structures, comprising the following features: a. a longitudinal axis X which is oriented substantially perpendicular to the light passage surface, and b. one or more lateral surfaces, which are also oriented substantially perpendicular to the light passage surface.

3. Establishing an optical connection between the light source and the areally extended optical waveguide, such that the light emitted by the light source is coupled into the optical waveguide and guided in this via total internal internal reflection.

With regard to further advantageous features of the arranged on the light passage surface Lichtauskoppelstrukturen reference is made to the statements in connection with the claim 1. Particular advantages are obtained if, for providing a light guide having the required features, such a light guide is produced in an injection molding process, wherein advantageously the light coupling structures to be provided according to the invention are formed directly into a light passage surface of the produced light guide in the course of this injection molding process.

In the context of an alternative process control, in the provision of the areally extended transparent optical waveguide with the required features in a first method step, an optical waveguide blank is included, for example. produced by extrusion or injection molding. In a subsequent method step, the light output structures to be provided according to the invention are then introduced into at least one light passage surface of the optical waveguide by mechanical embossing of the optical waveguide blank, for example by rolling the light passage surface of the optical waveguide blank with a suitably structured roller.

Further advantages and features of the optical waveguide arrangement according to the invention, the mounting device according to the invention, the illuminating retroreflective license plate arrangement according to the invention, the motor vehicle with an illuminated holding device for a retroreflective license plate and the method according to the invention for producing a light guide arrangement emerge from the subclaims and the embodiments discussed below , which are explained in more detail with reference to the drawing:

In this show:

1 is a perspective partial sectional view of a mounting device for

Attaching a retroreflective license plate to a motor vehicle according to the prior art,

2 is an enlarged view of a section through the mounting device according to the prior art of Figure 1,

3 is an enlarged partial sectional view of the optical fiber of the mounting device according to the prior art of Figure 1,

4 shows a plan view of the light guide of a first embodiment of a light guide arrangement according to the invention,

5 is an enlarged view of a damping region of the light guide of Figure 4,

6 shows a schematic representation of the arrangement of the optical fiber coupling-out structures according to the invention on a light passage surface of the optical waveguide according to FIG. 4, FIG. FIG. 7 shows an electron microscopic representation of a light passage surface of the light guide according to FIG. 4, and FIG

8 shows an electron micrograph of a light passage surface of a light guide of a further light guide arrangement according to the invention.

Figures 1 to 3 relate to a mounting device, which are previously known from the prior art. They are taken from the German patent application DE 10 2007 015 747.0 of the same Applicant, this reference adding the entire disclosure scope of the referenced prior patent application to the disclosure of the present application.

The known from the aforementioned prior art mounting device 1 comprises a holder 10 which is adapted to hold the vehicle license plate 2. The holder 10 is further adapted to be attached to a motor vehicle (not shown) such that the retro-reflective license plate 2 held by the holder 10 is mechanically fixed to the vehicle.

In the exemplary embodiment shown, the holder 10 comprises a bottom-side mounting plate 30, which can be produced, for example, by injection molding from an impact-resistant thermoplastic such as ABS. With the rear mounting plate 30, which is intended to be mounted on a motor vehicle, a license plate unit 40 is connected at the top, which is captively connected to the mounting plate 30, wherein the connection between the mounting plate 30 and the license plate unit 40 can be solved without damage by means of a suitable tool ,

The holder 10 of the mounting device 1 thus consists of the mounting plate 30 and the license plate unit 40. Within the license plate unit 40, which forms a closed housing, a license plate 2 is supported.

Furthermore, the mounting device 1 comprises a light guide according to the invention. teranordnung 5, which will be discussed in more detail below. The optical waveguide 80 of the optical waveguide arrangement 5 is arranged on the front side of the retroreflective license plate 2 with the retroreflective license plate 2 held. In this case, the light guide assembly 5 is completely disposed within the closed housing of the license plate unit 40.

This housing is thereby covered above the salient Kfz license plate 2 from the upper side arranged areally extended light guide 80 of the light guide unit 5, which is connected by gluing or welding with the front panel 56, which is part of a frame 50 of the license plate unit 40. The front panel 56 is also made of an impact-resistant thermoplastic such as ABS and can be made for example by injection molding. The light guide 80 is made of a transparent impact-resistant plastic. Preference is given here PMMA is used due to the high transparency and high mechanical strength. However, it is also conceivable to use other transparent plastics such as polycarbonate or polyethylene.

In addition, the front light passage surface 81 of the light guide 80 can be hard-coated by the application of a hard and possibly also anti-reflection thin layer, whereby the scratch resistance of the light guide 80 can be increased while its reflectivity can be reduced, which makes the legibility of the license plate legend of the underlying license plate clearly increased.

Furthermore, 50 mounting holes 44 are provided in the front panel 56 of the frame, which allow an insertion of tools and thus allow a separation of rear mounting plate 30 and front license plate unit 40.

The use of a mounting device 1, the holder 10 is formed as a license plate unit 40 with a closed housing, which is connectable to a provided for mounting on the vehicle mounting plate 30 is optional and not essential for the realization of the advantages of the invention. The use of a compensation of the front light transmission Occurring surface 81 of the light guide 80 is optional.

The optical waveguide arrangement 5 of the illustrated mounting device 1 forms, together with the retroreflective license plate 2 arranged in the license plate unit 40, an illuminable license plate arrangement 100 according to the invention.

FIG. 2 shows an enlarged view of a section through the mounting device 1 according to the invention, which can be seen in more detail from FIG. The holder 10 includes the rear mounting plate 30, which is captively but detachably connected to the upper side plate identification unit 40.

The license plate unit 40 forms a closed housing, in which a lighting device 20 and to be held or to be illuminated license plate 2 is arranged. The vehicle license plate 2 to be held is preferably a license plate with a metal plate, in particular with an embossed metallic plate, in which the legend is introduced in the form of raised embossed numbers. The illumination device 20 comprises a plurality of light sources 22, which are supported by a common light source carrier 26 and are arranged uniformly spaced. The light sources 22 are preferably white-light LEDs (LEDs) of the SMD (surface mounted device) type, which operate with a low operating voltage and have a high optical output power. These are currently available from a number of suppliers and have the advantage of a homogeneous radiation characteristic with a long service life. The high efficiency of LED also leads to only a small heat development.

By way of example, white high-power LEDs are mentioned which have a light output of 1000 med and above. The company Oshino Lamps GmbH, Nuremberg, Germany, offers under the product name SUW 30030 white high-performance LED, which have a light output of typ. 4000 med at a beam angle of 30 °. Also, the company Candel Lights offers comparable high-performance LEDs, each having a light output of about 1300 med with an el. Power of about 2.7 W. Advantageously, the LEDs, for example, on a a Light bar forming circuit board mounted. It has proven useful additionally to apply a weathering protection in the form of a liquid coating on the LEDs, for example in the form of an approximately 10 micrometer thick layer of parylene, which is offered by the company Teutonia. Also, the application of an additional corrosion protection on the solder joints of the LEDs on the board of the light strip such as the corrosion inhibitor Terostat MS 931 Fa. Henkel has proven itself.

The use of up to 20 LED of the types mentioned leads in conjunction with the holder 10 and the mounting device 100 of the illustrated embodiment to good results. If LEDs of the SMD type are used, the use of LEDs, which has been proven by Alder Deutschland GmbH, Talstr. 55, 71522 Backnang be sold under the product name AS-1311 WCA2-C2Z.

The plurality of light sources 22 of the illumination device 20 is arranged in a longitudinal side of the license plate unit 40, wherein the beam direction of the individual light sources 22 coincides with the plane of the license plate 2.

The light sources 22 are supplied with electrical energy via a common supply line, wherein the supply line, not shown here, is led out of the license plate unit 40 via a sealed bore.

For uniform illumination of the held license plate 2, a planar extended optical fiber 80 is arranged on the upper side of the license plate 2, which is part of a light guide assembly 5 according to the invention. In this case, the light guide 80 is arranged by the embossed raised edge of the license plate license plate 2 spaced from the board of the license plate 2. In this light guide 80, which preferably consists of a transparent plastic such as polycarbonate or PMMA, the emitted light from the light sources 22 is coupled in a suitable manner. This will be discussed in more detail below. In the light guide 80, the coupled-in light of the light sources 22 is guided by total internal reflection. The (surface) nature of the light guide 80 in the region of its rear light passage surface 83 is such that at each internal total reflection by specifically introduced into the light guide 80 Lichtauskoppelstrukturen 90 coupled out a small percentage of the incident radiation and the underlying license plate license 2 is steered so that it is illuminated. These light extraction structures 90 will also be discussed in more detail below. It should firstly be mentioned that by targeted structuring of the surface 83 of the optical waveguide 80 in the regions adjacent to the light sources 22, the intensity greatly increased in the region of the light sources 22 in the optical waveguide 80 can be compensated by significantly reducing the decoupling level locally there. In principle, however, it is also possible to dispense with an inhomogeneous embodiment of the decoupling degree and to set the decoupling degree substantially homogeneous over the entire surface of the optical waveguide, as long as the applicable regulations of ECE-4 TA 22 and TA 22a are met with respect to the homogeneity of the illumination of the characteristic ,

The housing of the license plate unit 40 is formed in the embodiment shown of several components. A frame 50, which comprises a front panel 56 and a rear holder 58, which are manufactured as separate parts and in the creation of the holder 1 according to the invention are inextricably linked together, for example by welding, have a front opening, in which the area extended light guide 80 is used. The light guide 80 is, as already mentioned, inextricably connected to the front panel 56 of the frame 50, for example by means of gluing. In the embodiment shown, the front panel 56 and the rear holder 58 are each made by deep-drawing or injection molding and each consists of an impact-resistant thermoplastic such as ABS.

The frame 50 of the license plate unit 40 has an access opening 52 on the rear, which extends over the entire rear surface of the frame 50 and whose dimensions are dimensioned so that the retroreflective license plate 2 to be held is inserted into the frame 50 through the access opening 52 can. If the license plate is inserted, it comes into contact with pressure surfaces 59, which in the rear holder 58th are formed, and with the rear light passage surface 83 of the light guide 80, whereby a mechanical support is formed.

After the license plate 2 has been inserted into the frame 50, the license plate unit 40 is hermetically sealed by means of a cover 60. For this purpose, the frame 50 on the rear side a circumferential sealing strip 54. At the same time, the lid 60 forms a circumferential receiving groove 62, which is formed in its shape complementary to the circumferential sealing strip 54. The material of the lid 60 now has a relation to the material of the frame 50 increased elasticity, wherein the dimensions of the lid 60, here in particular the circumferential receiving groove 62 are dimensioned so that the cover 60 with its circumferential receiving groove 62 on the sealing strip 54 of rear holder 58 can be reared. Here, the lid 60 undergoes a certain elastic elongation, whereby the lid 60 is fixed on the circumferential sealing strip 54. Thermoplastic polyurethanes, for example the thermoplastic aliphatic polyurethane marketed by the company Bayer MaterialScience AG under the brand Desmopan®, have proved to be suitable as the material for the cover 60. This has an increased elasticity compared to ABS, so that the cover 60 can be mounted on the sealing strip 54 of the frame 50 in the manner known from plastic boxes in the food industry, resulting in a sealing seat of the sealing strip 54 in the receiving groove 62. As a result, the housing 10 formed by the license plate unit 40 is sealed by the cover 60.

As can be seen from FIG. 3, the light guide 80 forms pin-shaped fastening arms 86 on its longitudinal sides. These attachment arms 86 are passed through through holes in the light source carrier 26 and connected to this inextricably by thermal caulking. For joining the frame 50, the light guide 80 is therefore connected in a first step captive with the light source carrier 26 of the illumination device 20, on which the plurality of light sources 22 is arranged. Thereafter, this ready-made optical fiber assembly 5 is then inserted into the front panel 56. Subsequently, the rear holder 58 is placed on the back of the front panel 56 and welded to the front panel 56. As a result, the light guide assembly 5 is again set in the frame 50, in particular captively connected thereto. As can further be seen from FIG. 3, the optical waveguide 80 forms at the edge a plane coupling-in surface 84 into which the light emitted by the light sources 22 embodied as SMD LEDs in the illustrated embodiment is coupled in. For this purpose, the planar light emission surfaces of the SMD LEDs are brought into mechanical contact with the coupling surface 84 when the light conductor 80 is mounted on the illumination device. An optical coupling of the LEDs to the light guide, for example by filling the remaining air gap between the light emission surfaces of the SMD LEDs and the light coupling surface 84 with an adhesive whose refractive index is matched to the refractive index of the light guide 80 and the SMD LEDs, may be advantageous but not mandatory.

Furthermore, the geometry of the frame 50, in particular of the optical waveguide 80, is dimensioned such that when the frame 50 is assembled, an air gap remains between the front-side protective screen 70 and the optical waveguide 80, so that coupling out of the light guided in the optical waveguide 80 by coupling into the protective pane 70 is avoided as far as possible (see Fig. 2). By providing a separate protective screen 70, which itself does not function as a light guide of the illumination device 20, an unwanted increased coupling of light from the light guide 80 due to mechanical damage of the front light exit surface of the holder 1 according to the invention can be largely avoided. The arrangement of a protective screen 70 in front of the light guide 80 is to be regarded as optional. For cost reasons and because of a higher retroreflection of the entire license plate unit 40, an at least front-side compensation of the optical waveguide 80 with a scratch-resistance-increasing layer is to be preferred.

If the license plate 2 to be held is inserted at the rear into the license plate unit 40 through the access opening 52 formed in the license plate unit 40, which in the illustrated embodiment extends substantially over the entire rear surface of the rear holder 58, the access opening 52 of the frame 50 is formed by a lid 60 hermetically sealed. For this purpose, the back-side holder 58, as already mentioned, forms a peripheral sealing strip 54. Furthermore, the lid 60 forms a circumferential receiving groove 62. The shape of the sealing strip 54 and the receiving groove 62 are in this case adapted to each other so that a positive connection between the sealing strip 54 and receiving groove 62 results when the lid 60 is placed on the back of the frame 50.

After assembling the components described above, the license plate unit 40 of the mounting device 1 according to the invention is ready for operation. The completed license plate unit 40 with inserted license plate 2 can now be connected to the (for example, by screwing firmly connected to a motor vehicle) mounting plate 30 which is mechanically fixed to a motor vehicle, e.g. by screwing.

FIG. 4 shows a plan view of the light guide 80 of a light guide arrangement according to the invention, wherein a plurality of light sources 22, which are carried by a common light source support 26, are arranged on the coupling surface 84 of the light guide 80. The light emitted by the light sources 22 is thereby coupled into the coupling surface 84 of the optical waveguide 80 such that a high percentage of the light emitted by the light sources 22 is actually propagated within the optical waveguide 80 and guided there by internal total reflection. Details on this can be found again in the referenced DE 10 2007 015 747.

Of central importance for the advantageous properties of the light guide arrangement according to the invention are now the columnar Lichtauskoppelstrukturen 90, which are arranged in the rear light passage surface 83 of the light guide 80, i. in the light passage surface, which is arranged adjacent to the license plate 2 to be illuminated when the light guide arrangement 5 according to the invention is used as intended.

In FIG. 4, the region of the optical waveguide 80, which is not covered by the frame 50 of the holder 10 when the optical waveguide 80 is arranged in the assembly device 1 according to the invention, is indicated by the dashed line. Short dashed is that portion of the light guide 80 which is detected by the light emitted by the light sources 22.

Furthermore, it can be seen from FIG. 4 that attenuation regions 92 are located directly opposite the light sources 22 on the rear light passage surface 83 are formed, in which the density of the columnar Lichtauskoppelstrukturen 90 according to the invention is locally lowered, as shown in Figure 5 in more detail. In principle, the density of the light-extracting structures 90 in the rear light passage surface 83 is selected such that 10% of the rear light passage surface 83 are covered by the columnar light output structures 90 according to the invention. In practice, over the entire surface of the optical waveguide, there is a regular arrangement of the light coupling-out structures 90. In the attenuation regions 22, on the other hand, the density of the light-emitting coupling structures 90 is lowered locally from 10% to a maximum of 5% with respect to the surrounding regions of the rear light passage surface 83. That is, in the attenuation regions 92, only 5% of the optical waveguide surface is locally covered with the light outcoupling structures according to the invention. In this case, the local density of the light extraction structures 90, starting from the line of symmetry M, increases continuously from 5% on the line M up to 10% at the edge of the damping region 92 both in the direction marked X and in the opposite direction marked X '. In the direction of travel L of the light coupled into the optical waveguide 80, the density of the light outcoupling structures 90 locally increases from that edge of the attenuation region 92 which is oriented adjacent to the nearest light source 22, from there 5% to 10% on the opposite side End of the damping region 92. The density specifications here refer to a cubic lattice structure with circular structures 90, wherein edge-contacting structures 90 correspond to a density of 100%. By introducing these attenuation regions 92 in the immediate vicinity of the light sources 22 or their coupling points into the optical waveguide 80, the formation of halos in the region of the light sources 22 negatively influencing the readability of the license plate can be suppressed.

FIG. 6 shows, by way of example, a plan view of the rear light passage surface 83 of the light guide 80 from FIG. 4 in an alternative embodiment. As can be seen from FIG. 6d, this is a regular arrangement of the light extraction structures 90 on the rear light passage surface 83 in the form of a square grid. FIGS. A to d now show different densities of light-extracting structures 90 on the rear light passage surface 83, the light output structures 90 always being arranged on grid points of the square grid shown in FIG. 6 d. Here are the light-outcoupling structures 90, however, stochastically distributed on the grid points, at the same time locally results in a preset density. Thus, in FIG. 6a, a density of approximately 5% exists, ie 5% of the rear light passage surface 83 are covered by light extraction structures 90. In FIG. 6b, the density is about 35%, in FIG. 6c about 60%, and in FIG. 6d it is at the theoretical maximum of about 78.5% for a 2d cubic lattice on which structures 90 of round cross section are arranged ,

Finally, FIG. 7 shows an electron micrograph of a rear light passage surface 83 of a light guide 80 according to the invention in which light output structures 90 according to the invention are stochastically distributed on grid points of a square grid, with a density of 5% being set. As can be seen from FIG. 7, the light extraction structures 90 are columnar depressions in the rear light passage surface 83, which have a round cross section and whose lateral surfaces are oriented substantially perpendicular to the rear light passage surface 83. The diameter of the columnar light extraction structures 90 is in the range of 100 microns, their depth h measured from the rear light passage surface 83 is about 10 microns. Thus, the base area A of a columnar light extraction structure 90 shown is about 7,850 square microns.

Finally, FIG. 8 shows the arrangement of equivalent light extraction structures 90 in the rear light passage surface 83 of a light guide 80 according to the invention, the maximum practically achievable packing density of the light extraction structures 90 designed as a cylindrical depression being set here on the grid points of a square grid. As already mentioned above, the maximum achievable theoretical density of the light extraction structure 90 on the rear light passage surface 83 is about 78.5%. Also in this embodiment, the light extraction structures 90 have a round cross-section at a depth h of about 10 microns, the diameter of the structures is in the range of 100 microns. The typical minimum wall thickness between two adjacent light-outcoupling structures is here in the range of 10 micrometers so that the lattice constant of the square lattice is approximately 110 micrometers. In principle, the wall thickness can also be further reduced, but this is with manufacturing technology Difficulties connected. This results in a density of approximately 55% of the light extraction structures 90.

The transmission of the optical waveguide 80 according to the invention can be further increased if, for example, a reflection-reducing antireflective coating is applied to the front light passage surface 81 (not shown), which can be formed, for example, from one or more layer system of one or more materials having different refractive indices. In addition, it is also possible to form an antireflection coating in the form of moth-eye structures on the front-side light passage surface 81, as disclosed, for example, in DE 103 185 66 A1. A manufacturing process results e.g. from DE 100 20 877 A1. Again, the entire disclosure of the referenced publications is added by this reference to the disclosure of the present application.

The rear light passage surface 83, in which the light extraction structures 90 are formed, can also be designed to reduce reflection by embossing the aforementioned moth structure. Here, it must be ensured by suitable process control in the production of the optical waveguide 80 according to the invention that, in addition to the light outcoupling structures 90 to be provided according to the invention, the reflection-reducing moth-eye structures are impressed into the optical waveguide surface in this rear light passage area 83. This can be done, for example, by forming the reflection-reducing moth-eye structures already during the production of a light guide blank. In a subsequent production step, the light outcoupling structures 90 to be provided according to the invention are then introduced into the rear light passage surface 83 provided with moth eye structures, for example by means of a mechanical embossing process which may possibly be associated with local heating of the light conductor 80 in the area of its rear light passage surface 83.

In addition to a reflection-reducing coating, in particular the front-side light passage surface 81 of the light guide according to the invention can additionally be provided with a coating which increases the scratch resistance or with a fog-reducing "anti-fog" coating basically known from the prior art, in particular for the surface of a PMMA light guide or a light guide, which consists of transparent polycarbonate or transparent polyethylene.

In test measurements with an optical waveguide arrangement 5 according to the invention, in which the rear light passage surface 83 of the optical waveguide was provided with the light outcoupling structures 90 shown in FIGS. 7 and 8, which had a depth h of 10 micrometers with a diameter of 100 micrometers, could be coated with a white coating License plate blank or a black coated license plate blank and a density of 20 of the above-described white high-power LEDs over a length of 500 mm following luminance of the illuminated license plate blank or the following contrast ratios are achieved:

The reported percentage of the structural density refers to a square closest-circle packing, i. The lateral surfaces of the columns touch each other to correspond to a density of 100%.

It follows that with the light extraction structures 90 of the type described above, even at a density of only 10%, excellent results can be achieved with respect to the achievable luminous intensity of the license plate legend illuminated by the light guide arrangement 5 according to the invention, whereby the retroreflection of the retroreflective license plate only simultaneously was slightly reduced. With such a light guide assembly 5 thus both the legal requirements regarding the illumination of the held license plate license plate as well as with respect to the retroreflection of the held retroreflective license plate can certainly meet. When producing an individualized optical waveguide 80 according to the invention by injection molding, the light outcoupling structures 90 to be provided according to the invention can advantageously already be molded into the latter during the injection molding of the optical waveguide 80. For this purpose, it is advantageous to use a sheet steel insert for producing the light guide, which is inserted into the injection molding tool used, and which represents a die for the introduction of the light extraction structures 90 in the rear light passage surface 83 of the light guide 80. For this purpose, the steel sheet is highly polished on the side to be structured and nickel-plated. Column-like structures which are designed to be complementary to the light outcoupling structures 90 which are to be formed in the individualized light guide 80 according to the invention are subsequently deposited on this nickel-plated steel sheet by way of a lithographic method. These lithographic structures are advantageously produced in the LIGA process (LIGA: lithography, electroplating and impression molding), which is well known from the prior art. The finished structured nickel-plated steel sheet is then preferably determined by means of suitable fastening screws in a mold half of the injection molding tool as an embossing material. As a carrier for the embossing die, steel sheet offers particular because it has the same coefficient of thermal expansion as the tool steel of the injection mold. This is relevant because the temperature variations of the tool surface and the steel die during the injection molding process can be about 200 ° C per injection cycle.

Finally, it is generally stated that while the light guide assembly according to the present invention is particularly suitable for illuminating the legend of a retroreflective license plate, its use within the scope of the present invention is not limited to retroreflective license plate labels. On the contrary, a use in connection with arbitrarily designed license plates is to be encompassed, in particular optically transparent or even non-transparent signs as well as retroreflective as well as non-retroreflective signs. Furthermore, it is particularly suitable for placement in front of a license plate to be illuminated, but in principle is also an arrangement behind a transparent license plate license within the scope of the invention. An alternative independent device claim could relate to a light guide assembly 5 for illuminating a vehicle-mounted, possibly retroreflective, license plate 2, comprising:

1. a sheet-like extended transparent light guide 80 having a front light passage surface 81 and a rear light passage surface 83, and

2. at least one light source 22, the light in the light guide 80 a. coupled and guided in this, and b. for the illumination of the front or rear of the light guide assembly 5 arranged retroreflective license plate 2 is coupled out of this,

in which

3. the light guide 80 has light extraction structures 90 arranged in the region of a light passage surface 83,

characterized in that

4. the light extraction structures 90 consist of a plurality of raised or recessed column structures having the following features: a. a longitudinal axis X which is oriented substantially perpendicular to the light passage surface 83, b. one or more lateral surfaces, which are also oriented substantially perpendicular to the light passage surface 83.

An alternative independent method claim could relate to a method for producing a light guide arrangement 5 for illuminating a possibly retroreflective license plate 2 attached to a motor vehicle, which method comprises the following method steps:

1. providing at least one light source 22,

2. Providing a planar extended transparent light guide 80 with a front light passage surface 81 and a rear side Light passage surface 83, wherein the light guide 80 in the region of a light passage surface 83 arranged Lichtsauskoppelstrukturen 90, which consist of a plurality of recessed column structures having the following features: a. a longitudinal axis X which is oriented substantially perpendicular to the light passage surface 83, and b. one or more lateral surfaces, which are also oriented substantially perpendicular to the light passage surface 83, and

3. Establishing an optical connection between the light source 22 and the areally extended light guide 80, such that the light emitted by the light source 22 is coupled into the light guide 80 and guided therein.

Claims

claims

1. optical fiber arrangement (5) for illuminating a motor vehicle mounted on a possibly retroreflective license plate (2), with a. a planarly extended transparent light guide (80) having a front light passage surface (81) and a rear light passage surface (83), and b. at least one light source (22) whose light in the light guide (80) i. coupled and guided in this, and ii. for the illumination of the front or rear of the light guide assembly (5) arranged retroreflective license plate license plate (2) is coupled out of this,

in which

c. the light conductor (80) has light-outcoupling structures (90) arranged in the region of a light passage surface (83),

characterized in that

d. the light extraction structures (90) consist of a plurality of raised or recessed column structures, which have the following features: i. a longitudinal axis X which is oriented substantially perpendicular to the light passage surface (83), ii. one or more lateral surfaces, which are also oriented substantially perpendicular to the light passage surface (83), and e. that light passage surface (83, 81), in the area of which the light outcoupling structures (90) of the light guide (80) are arranged, is provided with a coating which: i. increases the scratch resistance, ii. reduces the reflectivity of the light passage surface (83, 81), iii. reduces the fogging tendency of the light passage surface (83, 81) in situations below the dew point, or iv. die- in the case of the front light passage surface (81) - reduces the adhesion of dirt on the light passage surface (81).

2. Light guide arrangement (5) according to claim 1, characterized in that all lateral surfaces of the column structures are oriented perpendicular to the light passage surface (83).

3. optical fiber arrangement (5) according to claim 1, characterized in that the height or depth h of the column structures relative to the light passage surface (83) in the range between 1 and 100 micrometers.

4. The optical fiber assembly (5) according to claim 1, characterized in that the size A of the base surface of the columnar structures is in the range between 50 and 50,000 square microns.

5. optical fiber arrangement (5) according to claim 1, characterized in that the height or depth h of the Lichtsauskoppelstrukturen (90) relative to the light passage surface (83) varies locally on this.

6. optical fiber arrangement (5) according to claim 1, characterized in that the size A of the base surface of the light extraction structures (90) on the light passage surface (83) varies locally.

7. optical fiber arrangement (5) according to claim 1, characterized in that the density of the Lichtsauskoppelstrukturen (90) on the light passage surface (83) varies locally.

8. optical fiber assembly (5) according to claim 7, characterized in that the density of the light extraction structures (90) on the light passage surface (83) is lowest in the area adjacent to the at least one light source (22).

9. optical fiber arrangement (5) according to claim 1, characterized in that the Lichtsauskoppelstrukturen (90) along its longitudinal axis X. have substantially constant cross-section.

10. optical fiber arrangement (5) according to claim 1, characterized in that the cross section of the Lichtsauskoppelstrukturen (90) along its longitudinal axis X tapers.

11. Light guide arrangement (5) according to claim 1, characterized in that the light extraction structures (90) are arranged regularly on the light passage surface (83).

12. optical fiber arrangement (5) according to claim 1, characterized in that the light extraction structures (90) stochastisch on the light passage surface (83) are arranged.

13. optical fiber arrangement (5) according to claim 1, characterized in that the Lichtsauskoppelstrukturen (90) from the running direction L of the guided light in the light guide (80) light independent Lichtauskoppelgrad.

14. optical fiber arrangement (5) according to claim 13, characterized in that the Lichtsauskoppelstrukturen (90) have a circular base surface.

15. optical fiber arrangement (5) according to claim 1, characterized in that the Lichtsauskoppelstrukturen (90) have a dependent of the running direction L of the guided light in the optical fiber (80) Lichtauskoppelgrad.

16 light guide assembly (5) according to claim 15, characterized in that the Lichtauskoppelstrukturen (90) transverse to the direction L have larger dimensions than in the direction of L.

17 light guide assembly (5) according to claim 16, characterized in that the dimensions of the Lichtauskoppelstrukturen (90) transverse to the direction L at least by a factor of 1.5, preferably by a factor of 3, more preferably by a factor of 10 are greater than the dimensions in the Direction L.

18 light guide assembly (5) according to claim 16, characterized in that the running direction L is oriented in normal use of the light guide assembly (5) substantially perpendicular to the horizontal.

19, light guide assembly (5) according to claim 15, characterized in that the Lichtsauskoppelstrukturen (90) have an elliptical base surface.

20. Light guide arrangement (5) according to claim 1, characterized in that the areally extended light guide (80) consists of plastic.

21. Light guide arrangement (5) according to claim 1, characterized in that the light extraction structures (90) are formed integrally with the light guide (80).

22, light guide assembly (5) according to claim 1, characterized in that the Lichtauskoppelstrukturen (90) form flat top surfaces, each of which is oriented substantially parallel to the Lichtdurchtrittsf laugh (83).

23, light guide assembly (5) according to claim 1, characterized in that the Lichtauskoppelstrukturen (90) form a rounded top surface.

24. optical fiber arrangement (5) according to claim 20 and 21, characterized in that a. the optical fiber (80) is made by injection molding, and b. the light extraction structures (90) during injection molding of the light guide in one of the light passage surfaces (83) are formed

25. Light conductor arrangement (5) according to claim 1, characterized in that the light extraction structures (90) cover a proportion of 5% to 20% of the surface of that light passage area (83), in whose operation rich they are arranged.

26. Mounting device (1) for fastening a possibly retroreflective license plate (2) on a motor vehicle comprising the following features: a. a holder (10) adapted to i. to hold a retroreflective license plate (2) with a two-dimensional shield plate, and ii. being attached to a motor vehicle such that the retroreflective license plate (2) held by the holder (10) is mechanically fixed to the vehicle, and, b. an optical waveguide arrangement (5) according to claim 1, wherein the optical waveguide (80) of the optical waveguide arrangement (5) is arranged with the retroreflective license plate (2) in front or on the back of the extensively extended shield plate of the retroreflective license plate (2).

27. Illuminated, optionally retroreflective automotive license plate assembly (100) comprising the following features: a. an optionally retroreflective license plate (2) with an area-wide shield plate, b. an optical fiber assembly (5) according to claim 1, wherein the optical fiber (80) of the optical fiber assembly (5) front or back of the planar extended shield plate for illumination of the retroreflective license plate (2) is arranged.

28. A motor vehicle with a holding device for an optionally retroreflective license plate (2), comprising the following features: a. a license plate holder, which is adapted to hold an optionally retroreflective license plate (2) with a planar expanded shield plate, such that the held by the license plate holder license plate (2) is mechanically fixed to the car, and, b. an optical waveguide arrangement (5) according to claim 1, wherein the optical waveguide (80) of the optical waveguide arrangement (5) is supported by a retroreflective vehicle which is held in the license plate holder. License plate (2) front or back of the planar extended shield plate of the vehicle license plate (2) is arranged.

29. A method for producing a light guide arrangement (5) for illuminating a possibly retroreflective license plate (2) attached to a motor vehicle, characterized by the following method steps: a. Providing at least one light source (22), b. Providing a planarly extended transparent light guide (80) having a front light passage surface (81) and a rear light passage surface (83), wherein the light guide (80) in the region of a light passage surface 83) arranged Lichtsauskoppelstrukturen (90), of a plurality of raised or recessed Consist of pillar structures, which have the following features: i. a longitudinal axis X which is oriented substantially perpendicular to the light passage surface (83), and ii. one or more lateral surfaces which are likewise oriented substantially perpendicular to the light passage surface (83),

c. Overlaying that light passage surface (83, 81), in whose area the light outcoupling structures (90) of the light guide (80) are arranged, with a coating which: i. increases strength, ii. reduces the reflectivity of the light passage surface (83, 81), iii. reduces the fogging tendency of the light transmission surface (83, 81) in situations below the dew point, or iv. die- in the case of the front light passage surface (81) - reduces the adhesion of dirt on the light passage surface (81).

and,

d. Producing an optical connection between the light source (22) and the planarly extended light guide (80), such that the light emitted by the light source (22) is coupled into the light guide (80) and guided therein.

30. The method according to claim 29, characterized in that all lateral surfaces of the column structures are oriented perpendicular to the light passage surface (83).

31. The method according to claim 29, characterized in that the height or depth h of the column structures relative to the light passage surface (83) in the range between 1 and 100 micrometers.

32. The method according to claim 29, characterized in that the size A of the base area of the columnar structures is in the range between 50 and 50,000 square micrometres.

33. The method according to claim 29, characterized in that the light guide (80) is produced by means of injection molding.

34. The method according to claim 33, characterized in that the light extraction structures (90) during injection molding of the light guide (80) in one or both of the light passage surfaces (81, 83) are formed.

35. The method according to claim 29, characterized in that the light guide (80) is produced by means of extrusion extrusion.

36. A method according to claim 35, characterized in that the light extraction structures (90) after extrusion of the light guide (80) by rolling with a structured roller in one of the light passage surfaces (83) are formed.