DE102011089575B3 - Lighting device for a motor vehicle with a stepped light guide - Google Patents

Abstract

The invention relates to a lighting device for a motor vehicle having an optical waveguide structure which has a planar waveguide region having a first broad side and a second broad side equidistant to the first broad side and narrow sides forming the first broad side second wide side connect, wherein a second narrow side is adapted to parallelize from a first narrow side to the second narrow side incident light and to judge a third narrow side. The illumination device is characterized in that the second narrow side has a first parallelizing partial surface and a second parallel partial surface, wherein the second parallelizing partial surface is arranged staggered relative to the first parallelizing partial surface toward the interior of the planar optical fiber region.

Description

The present invention relates to a lighting device for a motor vehicle according to the preamble of claim 1.

Such a lighting device is from the US 2010/0046242 A1 as well as from the US 6398988 B1 known.

The known illumination device has a light guide structure which has a plurality of coupling-in areas and a planar light guide area. The latter has a first wide side and a second wide side. The first page is bounded by a first edge and the second page is bounded by a second edge. The second broad side is opposite to the first broad side equidistant. Narrow sides lying between the first edge and the second edge connect the first wide side to the second wide side. Second narrow sides are so far set up to direct from a first narrow side to the second narrow side incident light of a light source on a third narrow side. The second narrow side has a first partial surface and a second partial surface, wherein the second partial surface is arranged staggered relative to the first partial surface in the direction of the interior of the planar optical waveguide region.

With regard to the light exit surface of such a light guide structure, there is the property that only those curvatures can be realized that correspond to the edge curve of a correspondingly cut planar board on which laterally emitting light-emitting diodes (LEDs) are arranged as light sources. LEDs emitting laterally to their mounting surface are not as widely available on the market as standard LEDs which radiate parallel or antiparallel to the surface normal of their mounting surface. Compared to the standard LEDs, there are only a few choices for laterally emitting LEDs. In addition, they provide a lower luminous flux, which, when summed over several LEDs requires a certain luminous flux, requires more LEDs, which in turn leads to higher costs and a higher probability of failure.

From the 5 and 6 of the DE 10 2008 048 765 A1 For example, an illumination device is known in which in each case only a very limited proportion of the luminous flux emitted by an LED impinges on a parabolic surface and is thereby deflected in the desired direction. As a result, the light exit surface appears unevenly bright, since light hits at each point, which comes directly from the LED without a light directing reflection on a parabolic surface. The non-aligned rays all have a different direction. At the points that lie in front of the parabolic surfaces, this adds up to a strong, parallel light bundle, which leads to the overall undesirable inhomogeneous appearance.

Against this background, the object of the invention in the specification of a lighting device of the type mentioned, which does not have these disadvantages or at best in a reduced form.

This object is achieved with the features of claim 1. From the aforementioned prior art, the present invention differs in that the first partial surface is bounded by the first edge and the second edge and the second partial surface is bounded by the second edge, but not by the first edge.

The second narrow side has a homogenizing effect on a part of the light. These effects are achieved by the said subdivision of the second narrow side into a first subarea and a second subarea which is arranged staggered in relation to the first parallelizing subarea toward the interior of the planar optical waveguide region and through the stated limitations.

As a result of the subdivision of the second narrow side, the light incident on the second narrow side is subdivided into sub-beams which allow an individual alignment of the light beams. Each sub-area generates its own light distribution, which in sum give a different light distribution than if the second sub-area were not present.

This makes it possible, in particular, to block light from the light bundle reflected by the first subarea through the second subarea. It is possible, in particular, to block out a part of the light of this light bundle, which would illuminate an already sufficiently bright first subregion of the light distribution generated by the first subarea even brighter without this measure. Moreover, the invention further allows to direct the light hidden from the first light bundle into a second subarea of the light distribution generated by the first subarea, which without this measure would be comparatively darker than other subareas of the first light distribution.

As a result, the homogeneity of the overall resulting light beam is significantly improved. The resulting light beam is coupled out via the third narrow side. The third narrow side then appears to the viewer with the light source switched on homogeneously, ie as a narrow band of light shining with uniformly distributed brightness. Such appearance is desired.

A preferred embodiment is characterized in that the second narrow side is adapted to parallelize light incident on the second narrow side from the first narrow side and to direct it to the third narrow side, wherein the first partial surface is a parallelizing partial surface and wherein also the second partial surface is a parallelizing partial surface.

As a result, the light exit surface from the interior of the light guide structure is illuminated with parallel light.

A further preferred refinement is characterized in that the first narrow side forms a transition of a coupling region having a light entry surface and materially connected to the planar region to the planar region, which coupling region is adapted to parallelize light of a light source coupled via its light entry surface and To direct the parallelized light on the second narrow side so that the first partial area (unless it is shaded by the second partial area) and the second partial area of the second narrow side is illuminated.

The illumination of the first partial area not shaded by the second partial area and of the second partial area avoids dark areas on the light exit area which could occur if only a part of the sum of the first partial area and the second partial area were illuminated. It is also preferred that exactly the first partial area, insofar as it is not shaded by the second partial area, and the second partial area of the second narrow side be illuminated.

The light coupled in via the coupling-in region is thus used completely for the illumination of the two partial surfaces mentioned. As a result, all coupled light is ultimately directed to the light exit surface, thus optimizing the efficiency that can be defined as the ratio of coupled light to coupled light.

It is also preferable that the width of the second partial area decreases with increasing distance from the first narrow side.

This offers another possibility for homogenizing the brightness distribution. Due to the decreasing with increasing distance from the first narrow side width of the second partial surface results in a sense below the second partial surface an expanding light guide cross-section, which ensures a desired further parallelization.

It is further preferred that the second partial surface has a trapezoidal or triangular contour.

It is also preferable that the second partial surface is arranged closer to the first narrow side than to the third narrow side.

It is further preferred that the second narrow side is divided into more than two partial surfaces.

A further preferred embodiment is characterized in that a part of the surface located further in the interior has a smaller focal length than a part of the surface lying further outside.

It is also preferable that the second narrow side has a parabolic shape. This means that the edges with which the second narrow side meets the first side and the second side are parabolas.

It is further preferred that the second narrow side comprises a series of adjacent surface segments, wherein edges with which the surface segments abut the first broad side and the second broad side have a parabola as an envelope.

A further preferred refinement is characterized in that the optical waveguide structure has a plurality of surface-connected optical waveguide regions and coupling regions, the coupling-in regions being curved so that their light entry surfaces lie in one plane.

Furthermore, it is preferred that the optical waveguide structure has an area which serves to produce a luminous light exit surface and which is a cohesive component of the optical waveguide structure and lies in the light path behind the parallelizing partial areas of the second narrow side.

Furthermore, it is preferred that the third narrow side is divided into stepwise offset partial surfaces. As a result, a curvature of a light exit surface can be reproduced with discrete steps without triggering an undesirable occurrence of internal total reflections. Internal total reflections are known to occur when the angle of incidence of the light on the curved light exit surface due to their curvature exceeds the critical angle of total reflection.

It is also preferred that the step-like offset partial surfaces are arranged, as it were, offset stepwise in the direction of a surface normal of the broad sides. By this configuration, a curvature in a be generated further spatial direction, so that there is the possibility to provide three-dimensional curved appearing luminous light exit surfaces.

Further, it is preferable that the wide sides are flat parallel surfaces. As a result, a plate-shaped optical waveguide structure is provided which is suitable in particular for stacking. An alternative embodiment is characterized in that the broad sides are surfaces which are curved in space. This is advantageous for achieving three-dimensionally curved light exit surfaces in space.

Further advantages will become apparent from subclaims, the description and the accompanying figures.

It is understood that the features mentioned above and those yet to be explained can be used not only in the particular combination given, but also in other combinations or in isolation, without departing from the scope of the present invention.

drawings

Embodiments of the invention are illustrated in the drawings and are explained in more detail in the following description. In each case, in schematic form:

1 an embodiment of a lighting device according to the invention for a motor vehicle;

2 different views of a coupling region of a light guide structure of the 1 ;

3 a coupling-in area and a planar light guide area together with exemplarily selected rays of a light bundle;

4 different views of a planar light guide region, the angle-changing second narrow side is not yet divided into a first and second partial surface;

5 a plan view of such a planar light guide area together with a resulting brightness distribution;

6 a plan view of a planar light guide region, the second narrow side is divided into two sub-areas;

7 a section through the object of 6 ;

8th a plan view of a stepped divided planar light guide region to illustrate a shading effect;

nine a plan view of such a planar light guide area together with a resulting brightness distribution;

10 a further embodiment of a light guide structure of a lighting device according to the invention in an oblique view;

11 the object of 10 in a plan view;

12 a preferred embodiment, in which the width of the second partial area decreases with increasing distance from the first narrow side;

13 a composite of several cohesively connected fiber optic structures;

14 an embodiment suitable for use in conjunction with a planar board;

15 a first possibility to generate a three-dimensionally curved luminous curve;

16 a second way to create a three-dimensionally curved luminous curve;

17 a possibility of stacking several optical waveguide structures in order to obtain complex light exit surfaces from individual optical waveguide structures; and

18 an embodiment in which the angle-changing surface is realized by planar surface segments.

In this case, the same reference numerals in the various figures denote the same or at least functionally identical elements.

In detail, the shows 1 a lighting device 1 for a motor vehicle with a light guide structure 12 , The light guide structure 12 is in a housing 2 the lighting device arranged. The housing 2 has a light exit opening, which is covered by a transparent cover.

The light guide structure 12 has a coupling-in area 14 and at least one planar light guide region 16 on. The planar light guide area 16 has a first broad side 18 on, by one first edge 18.1 is limited. In addition, has the planar light guide area 16 a second broad side equidistant from the first broad side and from a second edge 20.1 is limited. In the 1 becomes the second broad side of the volume of the sheet light guide area 16 covered. Narrow sides lie between the first edge 18.1 and the second edge 20.1 and connect the first broad side 18 with the second broad side.

A first narrow side, of which in the 1 only one edge 22.1 is shown, adjacent to the planar light guide area 16 against the coupling area 14 from.

A second narrow side 24 is set up from a first narrow side to the second narrow side 24 to parallelize incident light and onto a third narrow side 26 to judge. The third narrow side 26 represents a light exit surface of the optical waveguide structure 12 represents.

The second narrow side 24 has a first parallelizing partial surface 28 and a second parallelizing subarea 30 on. The second parallelizing subarea 30 is opposite the first parallelizing face 28 stepped towards the interior of the planar light guide area 16 staggered.

The coupling area 14 has a first end facing away from the planar light guide region and a second end facing the planar light guide region.

At the first end is a light source 32 arranged so that the light emitted by it in the the planar light guide area 16 opposite end of the coupling region 14 is coupled. At the light source 32 it is preferably a semiconductor light source, in particular a single light emitting diode or laser diode or a spatial combination of several such diodes. For motor vehicle lighting devices, and so also preferred here, light-emitting diodes are usually used, which have a quadrangular, planar light exit surface with an edge length of 0.3 mm to about 2 mm. The arrangement is such that the distance between the light exit surface of the semiconductor light source and the light entry surface of the coupling region is less than 1 mm.

It is a goal, a long and narrow light exit surface of the light guide structure 12 homogeneous with parallel light from the interior of the light guide structure 12 to illuminate. The lighting should be as efficient as possible, ie with the highest possible share of the injected light.

With respect to the light exit surface of the optical waveguide structure 12 serving third narrow side 26 and in front of it in the light direction surface light guide area 16 For example, the x direction is defined as a direction of a depth of the sheet light guide portion, the y direction as a width direction of the sheet light guide portion and the light exit surface, and the z direction as the thickness of the sheet light guide portion and height of the light exit surface.

From a viewing direction opposite to the indicated x-direction, the luminous area in the embodiment shown in FIG 1 is shown, a rectangle of the height delta z and the width delta y. In the following, the xy plane is considered a horizontal plane and the xz plane is a vertical plane. It is understood, however, that this consideration refers only to the explanation of the illustrated embodiments and thus defined in some way an entrained coordinate system. This should be the possible orientations of the illumination device in a vehicle or also the possible orientations of light guide structures 12 within a lighting device 1 do not restrict. As far as horizontal angles are concerned in the following, these should lie in the xy plane, while vertical angles should lie in the xz plane.

The indication of these directions in the various figures therefore establishes a relationship between the orientations of the objects represented in each case. The light source 32 is located at the origin of the represented coordinate system.

In preferred embodiments, the length of the third narrow side serving as light exit surface 26 in the y-direction greater than four times their width in the z-direction, in particular greater than six times their width, and more preferably greater than eight times their width. In each case, these data relate to a light conductor volume that is illuminated by a light source, be it a single semiconductor light source or a spatially combined arrangement of a plurality of semiconductor light sources. If several spatially separate light sources are used, a light guide volume is assigned to each light source, such an arrangement being considered as a unit cell. The depth of the planar light guide region is preferably a multiple, in particular at least four times its thickness, which justifies the designation as a planar light guide.

Modern automotive lighting devices provide signal light distribution and / or headlight distribution. A signal light distribution is used to indicate the presence of a motor vehicle and / or the intentions of his driver to other road users. Headlight light distributions, on the other hand, should illuminate objects in the travel path of the motor vehicle and thus make them perceptible to the driver. The generation of a light distribution is also called a light function. Frequently, a lighting device fulfills a plurality of light functions with the aid of one or more light modules, which are arranged in such a lighting device.

The invention presented here preferably fulfills signal light functions, in particular a daytime running light function, a flashing light function, a position light function, a taillight function or a brake light function. In an interconnection of multiple optical fiber structures and headlight lighting functions can be realized. It does not matter whether lighting devices according to the invention 1 in addition to fulfill a light function fulfilled by the invention still other light functions, for which they optionally have further light modules. Therefore, embodiments of lighting devices according to the invention can be, in particular, separate front lights for flashing or daytime running light lighting functions, or they can be front lights or rear lights that fulfill a plurality of light functions.

In the following, details of elements and / or configurations of optical fiber structures will be described 12 explained lighting devices according to the invention. Here, the optical waveguide structure is first based on a planar design, as they are also in the 1 is illustrated explained. Below also three-dimensionally curved configurations are presented.

In principle, an elementary cell is made up of a light guide structure 12 an embodiment of a lighting device according to the invention from the coupling region 14 , the planar light guide area 16 and possibly also a further area together, which serves to generate a predetermined contour of the light exit surface and will be discussed in more detail below.

The 2 shows in its part a) an oblique view and in its part b) a plan view of the coupling region 14 , By the light source 32 facing light entry surface enters light into the coupling region 14 and propagates within the light-conducting material of the coupling region 14 to an end surface 34 , There begins in the 2 not shown area 16 the light guide structure 12 , The coupling area 14 has a first area 14.1 and a transition area 14.2 on. In the first area 14.1 the cross-section of the coupling area widens 14 , Starting from the light entry surface to the beginning of the transition section 14.2 continuously on. In this case, the widening in the xy plane may not be identical to widening in the z direction. When going through the first area 14.1 of the coupling area 14 experiences a large proportion of the coupled light one or more internal total reflections on the longitudinal surfaces of the first area 14.1 , As a result, the light experiences a parallelization there. In this case, a parallelization is understood to mean a narrowing of the opening angle of the light cone, which, however, does not yet merge into bundling with a focusing effect, that is to say the light propagating in parallel at maximum bundle constriction has the result.

With regard to the vertical direction, the light continues to move only between the surfaces perpendicular to the z-direction, except for special cases to be described below. It therefore moves between the first surface 18 from the 1 , which is also referred to below as a lid, and the opposite surface of the lid, which is also referred to below as the bottom. This means that the distribution of the vertical angle of light passing through the end face 34 in the planar light guide area 16 transgresses when passing through the planar light guide area 16 is maintained and that the associated light rays at serving as a light exit side third narrow side of the planar light guide region 16 emerge at an angle-increasing refraction. This in turn means that at the end of the launch area 12 the vertical desired angle distribution must be present except for the angle - increasing exit refraction. It is therefore preferred that the coupling-in area is just designed so that it generates a predetermined angular distribution in the vertical direction.

With respect to the horizontal direction, the horizontal angular distribution in the area of the light guide area applies 16 is still being selectively changed. The change is made by the parallelizing effect of the second narrow side 24 of the planar light guide region 16 ,

In one embodiment, the coupling-in area has 14 a curved shape. Such a bent Einkoppellichtleiter has only two flat surfaces. In such an embodiment, it is preferred that the coupling-in section has a rectangular cross-section and that this cross-section is between the coupling-in surface and the transitional region in the form of the first narrow side 22 of the flat section 16 the optical waveguide structure increases with a quadratic dependence on the length of the coupling-in region.

In a preferred embodiment, the coupling-in area is set up to receive the light of the light source 32 parallelized just so far that the parallelized light beam from the coupling area 12 in the planar light guide area 16 exceeds, the entire angle-changing surface of the planar light guide area 16 illuminated. The light beam should not illuminate more than this area in order to avoid otherwise occurring loss of efficiency. But it should illuminate not less than this area, otherwise dark areas on serving as a light exit side third narrow side 26 may occur.

This is an independent aspect which, even without the step in the angle-changing surface, already gives a fairly good homogeneity and, above all, the same effectiveness.

In view of this aspect, the following combination of features is also considered to be a self-contained teaching solving the above object: illumination device 1 for a motor vehicle with a light guide structure 12 that has at least one coupling-in area 14 and at least one planar light guide region 16 having a first broad side 18 that is from a first edge 18.1 is limited, and a second broad side 20 which is equidistant from the first broad side and that from a second edge 20.1 is limited, as well as with narrow sides 22 . 24 . 26 . 28 that is between the first edge 18.1 and the second edge 20.1 lie and connect the first wide side with the second wide side, with a second narrow side 24 is set up from a first narrow side 22 on the second narrow side incident light on a third narrow side 26 to judge, characterized in that the second narrow side 24 is set up, from the first narrow side 22 on the second narrow side 24 to parallelize incident light and onto the third narrow side 26 to be addressed, wherein the first narrow side of a transition of a light entry surface and cohesively connected to the planar region Einkoppelbereichs 14 to the planar light guide area 16 forms, which Einkoppelbereich is set up, via its light entrance surface coupled light of a light source 32 to parallelize and direct the parallelized light on the second narrow side so that only the second narrow side is illuminated.

3 shows the coupling area 12 and the planar light guide area 16 together with exemplarily selected rays of a light bundle 36 , which is the angle-changing surface of the planar light guide region 16 serving second narrow side 24 of the planar light guide area 16 in this sense illuminates exactly fitting.

The coupling area 12 hangs in a preferred embodiment cohesively with the planar light guide region 16 together, leaving the first narrow side 22 of the planar light guide area with the end face 34 of the coupling area 12 coincides. The optical waveguide structure preferably consists of a conventional optical waveguide material such as polycarbonate (PC) or polymethyl methacrylate (PMMA) or another crystal-clear material such as glass or silicone.

The 3 shows in particular an embodiment in which the first narrow side 22 of the planar light guide region 16 a transition of a light entry surface having and cohesively with the planar light guide region 16 contiguous coupling area 14 forms the planar light guide region, which coupling region 14 is adapted to, via its light entry surface coupled light of a light source 32 to parallelize and the parallelized light on the second narrow side 24 of the planar light guide region, that the angle-changing surface of the planar light guide region, ie in particular the first partial surface 28 and the second subarea 30 the second narrow side 24 of the planar light guide region 16 is illuminated.

It does not succeed by changes in the angle of attack, with which the side surfaces of the coupling area 14 expand, the angle-changing surface 24 in the planar light guide area 16 can illuminate exactly, a rotation of the coupling area 16 be helpful by an angle α. The fulcrum lies approximately in the middle 38 the endface 34 of the coupling area 12 , If this does not lead to the goal, the width delta y must be the third narrow side of the planar light guide area 16 in the design of the optical fiber structure 12 be adjusted.

The angle-changing side 24 opposite fourth narrow side 40 of the planar light guide region 26 has no optical function in the embodiments presented here. Analogous to this area is also the section 35 that is between the coupling area 14 and the second narrow side 24 without optical function.

These sections are in preferred embodiments for the attachment of connecting and fastening elements such as the webs between the light guides according to the invention in the 13 and 14 used. Alternatively or additionally, it is preferred that the injection area required for the plastic injection molding is positioned there.

4 shows in its part a) an oblique view and in its part b) a plan view of a planar light guide region 16 in which the angle-changing second narrow side 24 not yet divided into a first and second subarea. The Angle-changing surface is obtained in a preferred embodiment by extruding a lying in the x-y plane parabola in the z direction.

The 5 shows a plan view of a planar light guide area 16 , whose angle-changing surface 24 is not yet divided into a first and second sub-area, together with a resulting distribution of the brightness H of the third narrow side 26 emerging light over the width delta y of the third narrow side 26 , The distribution is shown very schematically. The angle-changing surface here has a parabolic shape. It is essential that a closer to the angle-changing side 24 lying fourth section of the light exit surface 26 significantly brighter than the average of the other sections, while one further from the angle-changing side 24 farther away eighth section appears to be less bright than the average of the other sections. Overall, the brightness distribution thus has a pronounced and disturbing inhomogeneity.

6 again shows a plan view of a planar light guide area 16 , This differs from the flat fiber optic range from the 5 in that the second narrow side has a first parallelizing partial surface 28 and a second parallelizing subarea 30 wherein the second parallelizing partial surface 30 opposite the first parallelizing partial surface 28 stepped towards the interior of the planar light guide area 16 is arranged offset.

In a preferred embodiment, both partial surfaces 28 . 30 parabolic, the two parabolas have the same focus and the same direction. It is also preferred that the parabola of the stepwise inwardly offset partial surface 30 a compared to the focal length of the outer surface 28 has smaller focal length. A ray of light 42 , whose vertical angular distribution corresponds to that at the end of the coupling region, becomes a part 42b at the second partial surface 30 reflected, the rest 42a becomes on the first part surface 28 reflected. Overall, therefore, results in a split into two bundles 42a and 42b , which the planar light guide area 16 leave at two different y-locations.

7 shows a section through the subject of 6 along the line VII-VII. The areal light conductor area shown there 16 has a thickness d in the z direction. In this z-direction has the first partial area 28 a thickness or width a, and the second partial area 30 has a thickness or width b. The ratio a to b controls approximately the amount of light in the bundles 42a and 42b , In the case shown, where a = b, the two resulting bundles are about the same light.

Another consequence of the reduction of the layer thickness in the light path behind the classified second partial area 42b is in the 8th shown. The first part surface 28 is illuminated in the hatched area only by half the amount of light, here again a = b is assumed. If you are not just on two faces 28 . 30 limited, but also allows more classified sub-areas, the overall result is a very effective method to illuminate the exit surface over the entire width delta y homogeneous.

nine illustrates the effect of the division of the angle-changing surface on the two stepwise offset partial surfaces. How actually already that 6 shows, becomes a sub-bundle 42b of the light beam 42 that without a subdivision of the angle-changing surface 24 in the beam path of the sub-beam 42a would lie, put inside. This means that a luminous flux is shifted to the right against the y-direction. In comparison with the 5 this is reflected in the nine in that the intensity distribution in the object of nine is more homogeneous than at the subject of 5 , The excess luminous flux from the middle area in 5 has been moved into the too dimly lit right area.

The 10 shows a further embodiment of a light guide structure 12 a lighting device according to the invention in an oblique view. The 11 shows the subject of the 10 in a top view. The light guide structure 12 after the 10 and 11 has a contour generating area 44 on, which serves to generate a luminous light exit surface, preferably a cohesive component of the light guide structure 12 is, and in the light path behind the parallelizing partial surfaces 28 . 30 the second narrow side 24 lies. As the 10 and 11 show is the third narrow side 26 divided in this embodiment in stepwise offset faces.

As a result, a curved light exit surface can be reproduced with discrete steps, without triggering an undesired occurrence of total internal reflections, as occurs on actually curved surfaces, when the angle of incidence of the light on the curved light exit surface exceeds the critical angle of total reflection due to its curvature.

The light exit surfaces of the individual stages are configured in a preferred embodiment as light in predetermined directions refractive surfaces, for example as cylindrical surfaces.

The 10 shows an embodiment in which the second partial surface 30 over its entire length has a constant width in the z-direction.

The 12 on the other hand shows a preferred embodiment, in which the width of the second partial area decreases with increasing distance from the first narrow side.

This offers another possibility for homogenizing the brightness distribution. Due to the increasing distance from the first narrow side, ie from the coupling region 14 , decreasing width of the second part surface 30 results in a sense in the z-direction below the second partial surface 30 an expanding optical fiber cross-section which provides a desired further parallelization.

It is further preferred that the second partial surface has a trapezoidal or triangular contour.

It is also preferred that the second partial surface is arranged closer to the first narrow side than on the third narrow side, or, which is the same, that the second partial surface 30 closer to the coupling area 14 as at the light exit surface 26 is arranged.

14 shows how by several, here five, preferably cohesively contiguous light guide structures 12.1 . 12.2 . 12.3 . 12.4 . 12.5 Also, a spotlight lighting function can be realized. The areas for coupling light and parallelizing the light are each identical in this example, only the contour generating areas vary in length (parallel to x). The contour is formed by steps whose steps are parallel and perpendicular to x.

This is necessary so that the light can leave the light guide parallel to x. If one waived the steps, the light would remain due to total reflections on the then curved surface in the light guide.

The steps of the steps lying perpendicular to the x-direction are curved, in this case convex, in order to break the light incident parallel to the x-direction from the light guide interior into a desired light distribution.

The in the 13 arrangement shown still has the disadvantage that the light sources can not be arranged on a flat board. Level boards are above all cheaper than flexible boards, so that a use of planar and rigid boards is advantageous.

14 shows an embodiment in which the example of the first coupling region 14.1 is shown as by corresponding curvature of the same connection to a flat board, or to a mounted on a flat board standard LED as a light source 32 can be realized. A standard LED is characterized by the fact that its light-emitting surface is opposite its mounting surface, with which it is attached to a circuit board 46 is attached.

Of course, this curvature of the coupling area 14.1 also on the planar light guide area 16 and / or the contour generating area 44 be extended. Up to this point, it was only shown how with the help of the contour generation area 44 a level luminous curve can be generated.

15 shows a first way to get from a flat curve to a three-dimensional curved luminous curve. For this purpose, the contour generating area 46 divided into individual bars, which are subsequently curved so that the light exit surface 26 also follows the desired curve in the z-direction. The restriction of curvature to the contour generating area 46 took place in the 15 just for the sake of simplicity. Alternatively or additionally, those regions of the planar light guide region can also be used 16 , in which only already parallelized light propagates, be deformed in this way.

A second way to create a three-dimensionally curved luminous curve is in the three views of a three-dimensionally curved contour generating area 46 of the 16 shown. 16a) shows an oblique view, 16b shows a view from the direction of the coupling region, and 16c shows a plan view of such contour generating area. Again, for simplicity of illustration, a limitation is imposed on the contour generating area 46 , Instead of dividing the area into bars, as is the case with the object 15 is the case, and then bend the bars in the design of the light guide structure according to the contour to be achieved, is the subject of the 16 the entire area of the contour generating area 46 curved. This unfortunately has the consequence that the light propagating therein receives horizontal components in reflections on the lid and / or on the floor. As an undesirable consequence, the parallelism generated by the parabolic angle-changing reflection surface is lost. If the number of reflections on the lid and on the bottom is identical, these horizontal components cancel each other out. Those rays, in which this favorable case does not apply, receive a horizontal component, which is at least maintained even after leaving the light guide through the outlet opening or even increased by refraction. This must be taken into account in the definition of the refractive surface on the exit surfaces in the design of the light guide structure in order to avoid an undesirably large horizontal scattering effect.

17 shows one way, multiple fiber optic structures 12 to stack around complex light exit surfaces of elementary cells serving as individual light guide structures 12 to obtain. By combinations of superimpositions, juxtapositions and juxtapositions of such unit cells or even different configurations of optical waveguide structures 12 you get more options. Are the individual light guide structures 12 obliquely in the room, which can be, for example, by tilting the left upper end of the in 18 As shown downward arrangement, lying on the individual stages of the tilted light exit surface scattering elements (for example, cylinder) must be tilted in the opposite design, continue to obtain a purely horizontal scattering.

18 shows a possibility that allows a further improvement of the uniformly bright appearance of the luminous and optionally three-dimensionally curved light exit surface. For this purpose, the angle-changing second narrow side is not realized as a real parabola, but such a parabola is approximated by straight line sections or by plane surface segments. 18a) shows once again an embodiment of a planar light guide region 16 that by a real parable 52 is limited. A bundle entering from the docking area 48 is parallelized on the parabola and illuminates exactly one refracting exit element 50 , In 18b) meets the same bundle 48 on a flat area drawn for illustrative purposes with thick line width 54 , This has the consequence that the bundle 48 is not parallelized, but is deflected while maintaining its opening angle and therefore not as in the case of 18a) on exactly one exit element 50 but on an approximately two exit elements wide area of the light exit surface 26 , Since the same applies to the two adjacent bundles, not shown, the exit element becomes 50 here illuminated by three superimposed bundles. As a result, otherwise possibly visible dark stripes between the images of adjacent exit elements are blurred in the resulting light distribution. This must be taken into account when designing the refracting surfaces on the exit surfaces in order to reduce otherwise threatening horizontal dispersion.

Claims (10)

Lighting device ( 1 ) for a motor vehicle having a light guide structure ( 12 ), which has at least one coupling region ( 14 ) and at least one planar light guide region ( 16 ) having a first broad side ( 18 ) from a first edge ( 18.1 ) and a second broad side ( 20 ) that is equidistant from the first broad side and that from a second edge ( 20.1 ), as well as with narrow sides ( 22 . 24 . 26 . 28 ) between the first edge ( 18.1 ) and the second edge ( 20.1 ) and connect the first wide side to the second wide side, with a second narrow side ( 24 ) is adapted from a first narrow side ( 22 ) on the second narrow side incident light on a third narrow side ( 26 ), wherein the second narrow side is a first partial area ( 28 ) and a second subarea ( 30 ), wherein the second partial surface ( 30 ) is staggered relative to the first partial surface in the direction of the interior of the planar optical waveguide region, characterized in that the first partial surface ( 28 ) from the first edge ( 18.1 ) and the second edge ( 20.1 ) and the second subarea ( 30 ) from the second edge ( 20.1 ), but not from the first edge ( 18.1 ) is limited. Lighting device ( 1 ) according to claim 1, characterized in that the second narrow side ( 24 ) is set up from the first narrow side ( 22 ) on the second narrow side ( 24 ) to parallelize incident light and onto the third narrow side ( 26 ), the first subarea ( 28 ) is a parallelizing partial surface and wherein also the second partial surface ( 30 ) is a parallelizing partial surface. Lighting device ( 1 ) according to claim 1 or 2, characterized in that the first narrow side has a transition of a light entry surface and cohesively connected to the planar region Einkoppelbereichs ( 14 ) to the planar light guide region ( 16 ), which coupling-in area is set up, light coupled in via its light entry surface of a light source ( 32 ) and to direct the parallelized light onto the second narrow side so that the first partial area and the second partial area of the second narrow side are illuminated. Lighting device ( 1 ) according to one of the preceding claims, characterized in that the second partial surface has a constant width or that the width of the second partial surface decreases with increasing distance from the first narrow side. Lighting device ( 1 ) according to claim 4, characterized in that the second partial surface has a rectangular, trapezoidal or triangular contour. Lighting device according to ( 1 ) one of the preceding claims, characterized in that the second partial surface is arranged closer to the first narrow side than on the third narrow side. Lighting device ( 1 ) according to one of the preceding claims, characterized in that the second narrow side is divided into more than two partial surfaces. Lighting device ( 1 ) according to one of the preceding claims, characterized in that a further inner partial surface has a smaller focal length than a further outer partial surface. Lighting device ( 1 ) according to one of the preceding claims, characterized in that the second narrow side has a parabolic shape. Lighting device ( 1 ) according to one of the preceding claims, characterized in that the second narrow side has a series of adjacent surface segments, wherein edges, with which the surface segments abut the first broad side and the second broad side, have a parabola as an envelope.

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