DE102018118764A1 - Motor vehicle lighting device with a corrugated light guide - Google Patents

Abstract

A motor vehicle lighting device with a light guide is presented, which has a front side, at least part of which serves as a light exit surface, and which has a rear side opposite the light exit surface, the rear side having decoupling elements which are set up to strike it from inside the light guide To deflect light so steeply to the light exit surface that the deflected light exits the light guide via the light exit surface, characterized in that the front side has grooves running parallel to a main direction of propagation in the light guide.

Description

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

Such a motor vehicle lighting device is known per se and has a light guide which has a front side, at least some of which serves as a light exit surface, and which has a rear side opposite the light exit side, the rear side having decoupling elements which are set up to expose it to deflect the light incident on the inside of the light guide so steeply to the light exit surface that the deflected light exits the light guide via the light exit surface.

Light guide rods, the cross sections of which are rectangular transversely to their longitudinal extent and the main direction of light propagation and which have coupling-out prisms on their rear side, have long been known. The main light propagation direction extends from one end of the light guide rod to the other end of the light guide rod. If such light guide rods, which are flat in a second direction lying transverse to the main direction of propagation, have a curved course around such a second direction, their appearance, which is characterized by light emerging via the light exit side, has light and dark areas. Since the aim is to have a light exit surface that appears as evenly bright as possible, the differently bright areas represent a serious disadvantage.

From the DE 10 2015 210 372 A1 it is known in this connection to use a special coupler in connection with a homogenizer. However, this known solution for avoiding differently bright and dark areas does not work if the geometry of the light guide deviates from simple rod-shaped geometries, which is the case, for example, when the light guide rod is split into two or more branches or if there is a direction in which the Optical fiber extends, changes significantly in its course. Then certain areas of the light guide may no longer be illuminated at all.

Against this background, the object of the invention is to provide a light guide that does not collimate the light propagating in it, so that the luminous flux density is as homogeneous as possible in all cross sections of the light guide lying transverse to the main light propagation direction and the directions of the light as long as it propagates in the light guide are distributed as widely as possible, but the directions of the coupling should be distributed as narrowly as possible around a main coupling direction.

This object is achieved with the features of claim 1. The present invention differs from the prior art mentioned at the outset by the characterizing features of claim 1. These provide that the front side of the light guide, which serves as the light exit surface, has grooves running parallel to a main direction of propagation in the light guide. The grooves ensure that internal total reflections that occur on them broaden the directional distribution of the light in the light guide.

Ultimately, this has the desired consequence that the appearance of the light exit surface is more uniform for an outside observer and has no, or at least only less clearly, lighter and darker areas.

A preferred embodiment is characterized in that the light exit surface is flat in a direction running transversely to the main light propagation direction and transversely to the distance between the light exit surface and the rear side, apart from modulations of the light exit surface formed by the grooves.

It is also preferred that at least a plurality of the grooves in cross sections that are perpendicular to the main light propagation direction have a cross section with a curved edge.

It is further preferred that some of the grooves have a concavely curved edge and another part of the grooves have a convexly curved edge.

Another preferred embodiment is characterized in that all the grooves of the plurality have a convexly curved edge.

It is also preferred that all of the plurality of grooves have a concavely curved edge.

It is further preferred that the edge has a circular curvature.

It is further preferred that the edge has a free-formed curvature that deviates from a circular shape.

It is also preferred that the cross sections are all the same.

Another preferred embodiment is characterized in that the cross sections are not all the same.

It is also preferred that a light-scattering or light-reflecting surface is arranged behind the back.

It is further preferred that the light exit surface runs around a further light exit surface, the further light exit surface being a light exit surface of at least one headlight light module of the lighting device and the main light propagation directions of the light emerging from the aforementioned light exit surfaces matching.

A further preferred embodiment is characterized in that the amplitudes of the modulation of the light exit surface caused by the grooves are smaller than the amplitudes of the modulation of the rear side caused by the decoupling elements.

It is also preferred that the outcoupling elements have edges which run continuously across the directions of the grooves and over several grooves.

Further advantages result from the following description, the drawings and the subclaims. It goes without saying that the features mentioned above and those yet to be explained below can be used not only in the combination specified in each case, but also in other combinations or on their own without departing from the scope of the present invention.

• 1 eine Draufsicht (bei bestimmungsgemäßer Verwendung von oben) auf eine Anordnung eines Lichtleiters und einer Lichtquelle einer Kraftfahrzeugbeleuchtungseinrichtung;
• 2 eine Rückseite des Lichtleiters aus der 1;
• 3 eine dem Stand der Technik entsprechende Vorderansicht des Lichtleiters aus der 1;
• 4 eine Merkmale der Erfindung aufweisende Vorderansicht eines Lichtleiter, der im Übrigen dem Lichtleiter aus den 1 bis 2 entspricht;
• 5 einen Abschnitt des Lichtleiters aus der 4 in einer Ebene, die durch eine (ggf. lokale) Hauptausbreitungsrichtung des Lichtes im Lichtleiter und durch eine Hauptabstrahlrichtung des Lichtleiters definiert ist;
• 6 Abschnitte des Lichtleiters aus der 4 in einer Ebene, die durch eine Hauptabstrahlrichtung des Lichtleiters und eine quer zur (ggf. lokalen) Hauptausbreitungsrichtung des Lichtes im Lichtleiter liegende Richtung definiert ist;
• 7 verschiedene Ausgestaltungen von Profilen von Riefen in der Lichtaustrittsfläche eines Lichtleiters einer erfindungsgemäßen Kraftfahrzeugbeleuchtungseinrichtung;
• 8 eine Vorderansicht einer Ausgestaltung eines Lichtleiters einer erfindungsgemäßen Kraftfahrzeugbeleuchtungseinrichtung; und
• 9 eine Kraftfahrzeugbeleuchtungseinrichtung.

Embodiments of the invention are shown in the drawings and are explained in more detail in the following description. Show, each in schematic form:

• 1 a plan view (when used as intended from above) of an arrangement of a light guide and a light source of a motor vehicle lighting device;
• 2 a back of the light guide from the 1 ;
• 3 a front view corresponding to the prior art of the light guide from the 1 ;
• 4 a features of the invention having a front view of a light guide, the rest of the light guide from the 1 to 2 corresponds;
• 5 a section of the light guide from the 4 in a plane which is defined by a (possibly local) main direction of propagation of the light in the light guide and by a main emission direction of the light guide;
• 6 Sections of the light guide from the 4 in a plane which is defined by a main emission direction of the light guide and a direction lying transversely to the (possibly local) main direction of propagation of the light in the light guide;
• 7 different configurations of profiles of grooves in the light exit surface of a light guide of a motor vehicle lighting device according to the invention;
• 8th a front view of an embodiment of a light guide of a motor vehicle lighting device according to the invention; and
• 9 a motor vehicle lighting device.

The shows in detail 1 a plan view of an arrangement of a light guide 10 and a light source 12 a motor vehicle lighting device. A right-handed coordinate system indicates different spatial directions. The x direction should be a main emission direction of the light guide 10 and the z-direction should be a main direction of propagation of the light in the light guide 10 his. For example, the y direction should be a direction perpendicular to the x direction and the z direction. The definition of the three directions is therefore based on the shape and the course of the light guide 10 ajar. The coordinate system, which does not have to be rectangular, can be regarded as an accompanying tripod, the origin of which is a central guide line of the light guide 10 follows, with the guideline roughly a smoothed main direction of propagation of the light in the light guide 10 equivalent. Cross-sectional areas of the light guide 10 that are perpendicular to the main direction of light propagation each have a centroid. The guide line is preferably a line that runs through all the centroids. This applies to all figures in which one or more of the directions of the coordinate system are shown.

The light guide 10 has a first end 14 , a second end 16 and one between the first end 14 and the second end 16 lying lateral surface 18 on.

The outer surface 18 has a front 20 and a back 22 as well as other side faces on between the front 20 and the back 22 lie. The light guide 10 has a coupling-in area, via the light of the light source 12 in the light guide 10 can be coupled. The light source 12 lies, for example, on an end face 24 of the light guide 10 opposite and shines light when switched on 26 towards the face 24 from. At least part of this light enters the light guide 10 one and experiences on its lateral surface 18 total internal reflections that light 26 along a main direction of propagation z in the light guide 10 propagate.

On the back side 22 of the light guide 10 are decoupling elements 28 arranged the light hitting them 26 the light source 10 so steep to the front 20 redirect that the redirected light is no longer reflected there but from the light guide 10 exit. The area of the front 20 , about the light from the front 20 emerges, represents the light exit surface of the light guide.

2 shows the back 22 of the light guide 10 from the 1 with decoupling elements 28 , The decoupling elements 28 are prism-shaped elevations and / or depressions in the back 22 of the light guide 10 whose areas are delimited by edges that are in the y direction and thus transverse to the main direction of propagation z in the light guide 10 and transverse to the main emission direction x of the light guide 10 run. The edges run in a straight line. That means the back 22 has no curvature in the direction y of the edges.

3 shows the front opposite the back 20 of the light guide 10 , Even the front 20 of the light guide has no curvature in the y direction. In the prior art specified at the outset, this is part of the front 20 forming light exit surface a smooth surface.

4 shows a front 20 that of a light guide 30 10 how he is referring to the 1 and 2 has been described, but instead of a smooth front 20 as in 3 is shown a front 34 has, which is parallel to a main direction of propagation z in the light guide 30 running grooves 32 having.

In one embodiment, the in 2 visible edges of the decoupling elements 22 across the directions of the in 4 visible grooves 32 and over several grooves 32 contiguous edges.

5 shows a section of the light guide 30 from the 4 in an area through a main direction of propagation z of the light in the light guide 30 and by a main emission direction x of the light guide 30 is defined. In this view are prismatic profiles of the decoupling elements 28 visible. The decoupling elements 28 have edges running perpendicular to the plane of the drawing and thus in the y direction. An optical path shows, as in the light guide 30 propagating light 26 at the back 22 , on the front side 34 and on an end face (possibly reflecting by metallic coating) 36 (Light is coupled in here from the left) is reflected before it is at a decoupling element 22 is deflected so steeply that when it hits the light exit surface following the deflection, it passes through the light guide through it 30 exit.

6 shows in her part 6a a section of the light guide 30 from the 4 in a plane through a main emission direction x of the light guide 30 and a transverse to the (possibly local) main direction of propagation z of the light in the light guide 30 lying direction y is defined. The one in the 5 and 6 illustrated light guide 30 has striations in its light exit surface 32 on.

These screams 32 have the function of the directional distribution of the inside of the light guide 30 to the front 34 incident light and there experiencing total internal reflections 26 to broaden. This technical effect results from the fact that the grooves 32 at different points from each other in the front 34 lying light exit surface also have surface normals (plumb bobs) which point in different directions from one another.

A flat light exit surface, as in the front 20 of the light guide 10 the 4 on the other hand always has solders pointing in the same direction at different points. The same solders in different points have the effect that light rays incident on these points from the same directions are reflected in the same directions, since the solder together with the direction of the incident beam determines the direction of the reflected beam. Therefore, the width of the directional distribution of the light does not change when reflected on such a flat surface. The directional distribution is therefore only reflected as a whole in the prior art.

By making the front 34 in the invention parallel to a main direction of propagation z in the light guide 30 running grooves 32 is in the front 34 lying light exit surface is not a smooth surface and therefore has solders pointing at different points in different directions. Together with the incident rays, there are surfaces with different orientations, in each of which there is an incident ray, a plumb line and an outgoing ray. That from different points of the grooves 32 facing front 34 outgoing rays have different directions even if the rays incident at these points have the same direction. As a result, the directional distribution of the in the light guide 30 propagating light 26 widened as desired. As a result, the one in the front 34 lying light exit surface from the inside of the light guide 30 Illuminated more homogeneously than in the smooth front 20 of the light guide 10 the 3 the case is. It has desired consequence that also the appearance of the front 34 of the light guide 30 lying light exit surface is more uniform for an outside viewer and has no, or at least only less clearly defined, lighter and darker areas.

This desired effect is with grooves 32 , whose cross sections are perpendicular to the main light propagation direction z, and which have a curved edge, are even more pronounced than in the case of grooves which have a straight edge (for example a triangular profile) in such cross sections. For this reason, it is preferred that at least a plurality of the grooves 32 in cross sections that are perpendicular to the main light propagation direction z, have a curved edge.

Cross-sections of grooves 32 , which have a curved edge, are in the 6a shown. Deviating from the representation in the 6a do not have to all groves 32 of the plurality of cross sections with a curved course have a convex curvature. In the 6a is the main direction of propagation z of the light 26 perpendicular to the plane of the drawing. The in the 6a visible parts of a beam path each represent projections of a coherent beam path into the plane of the drawing. The z components of light 26 are not visible here. Analog are in the 5 the y components of light 26 not visible. The 6b differs from that 6a in that the striations 32 in an additional part 30 ' are arranged. The additional part 30 ' is arranged at a constant distance from the light exit surface of the light guide. The light guide 30 can also have a curved shape, which in the 6b through the curved and dashed line 31 is indicated. The 5 and 6 show an embodiment in which a distance between the in the front 34 lying light exit surface and the back 22 , aside from influences from through the grooves 32 and the decoupling elements 28 caused modulations in the front 34 lying light exit surface and / or the back 22 on the distance, is constant. Such a distance can, for example, be the distance between an imaginary surface, which is the tip of the decoupling elements 28 touched, and an imaginary surface, which, the tips of the grooves 32 touched, defined. The distance is preferably constant, at least in the area of the light exit surface. The distance can also vary. With the varying spacing of the grooves, the shape of the grooves can be maintained, which leads to deeper grooves. The shape of the grooves can also be variable, the depth of the grooves remaining constant. The directional distribution of the light propagating in the light guide can thus be changed in a manner that can be predetermined by the shape of the grooves.

As an amplitude A the decoupling elements 28 here is a height of the decoupling elements 28 , or a distance from a tip of a coupling element 28 understood to its base. Under a period or latitude B a decoupling element 28 here is a distance between the tips of two coupling elements that are directly adjacent to one another 28 Roger that. The amplitude A the decoupling elements 28 is typically between 0.1 mm and 1.5 mm.

Analog is here under an amplitude a of the grooves 32 a height or, depending on the consideration, a depth of the decoupling elements 28 , or a distance from the tip of a groove 32 understood at its lowest point. Under a period b or width of a groove 32 here is a distance between the peaks or the lowest points of two directly adjacent grooves 32 Roger that.

It is preferred that the amplitudes a the by the striations 32 caused modulation in the front 34 lying light exit surface are smaller than the amplitudes A through the decoupling elements 28 caused modulation of the back 22 , The amplitudes a of the grooves 32 are preferably smaller than 0.1 mm. The width b of the grooves 32 is preferably less than 0.3 mm. The width of the grooves can be constant. The width of the grooves can also be variable along the grooves.

It is also preferred that the front 34 lying light exit surface in a direction transverse to the main light propagation direction z and transverse to the distance between the light exit surface and the rear 22 direction apart from through the grooves 32 formed modulations of the light exit surface is flat.

The 5 and 6 also show an embodiment in which behind the back 22 of the light guide 30 one of the back 22 facing light-scattering or light-reflecting surface 38 is arranged. This area 38 has the task of undesirably via the decoupling elements 28 from the back 22 leaked light on the light guide 34 to reflect past so that the light has a component in the x-direction or that the light enters the light guide 34 is reflected back.

7 shows three different profiles, which are the grooves 32 in cross sections that are perpendicular to the main light propagation direction z. The presentation does not claim to be complete. In the left part of the 7 show all the striations 32 a convex curved edge. in the middle part of the 7 show all the striations 32 a concave edge. The left part and the middle part of the 7 show configurations in which the cross sections are all the same. In reality, the number of grooves is preferably greater than 3 and results as a quotient from the width of the light exit surface in the transverse to the grooves 32 lying direction in the numerator and the width b of the grooves in the denominator. For a 10 mm wide light exit surface, the number of grooves (width eg 0.1 mm) can be approx. 100.

In the right part of the 7 shows part of the grooves 32 a concave curvature, while another part of the grooves has a convex curvature. 7 on the right shows an embodiment in which the cross sections are not all the same.

Here, too, it applies that not all cross sections have to have a convexly curved edge or a concavely curved edge. In one embodiment, it is preferred that all grooves 32 the majority (of the curved cross-sections) have a convex curved edge. In an alternative embodiment, it is preferred that all grooves 32 the majority (of the curved cross-sections) have a concave curved edge. A minority of the cross-section can also have straight-edged cross-sections in both alternatives.

The curvature is preferably circular, but other forms of curvature are also conceivable. It is possible, for example, for the edge to have a curvature that deviates from a circular shape and, for example, is formed at certain points.

8th shows a light guide 30 where the front 34 , in which the light exit surface lies, appears as a line. In the embodiment shown, which is to be understood only as an example, the light exit surface extends around a further light exit surface 102 or several other light exit surfaces 104 around, with the further light exit surface 102 . 104 is a light exit surface of at least one headlight light module or signal light module and wherein the main light propagation directions x des from said light exit surfaces 102 . 104 and from the one in the front 34 lying light exit surface match emerging light. The light is in the light guide that appears linear here 30 fed in at one end. The luminous flux fed in splits at the junction 106 into a first luminous flux I1 and a second luminous flux 12 on, the first luminous flux I1 in a first branch of the light guide 30 propagated and the second luminous flux 12 in a second branch of the light guide 30 propagated. It is a particular advantage of the present invention that even with such branching 106 no pronounced light and dark spots on the lines that appear linear here and in the front 34 of the light guide 30 form lying light exit surface.

9 provides a motor vehicle lighting device 100 represents, which has a housing in which an optical fiber 30 and at least one light in the light guide 30 feeding light source 12 is arranged. A light outlet opening on the housing 110 is made of a transparent cover 112 covered. The light guide 30 has the features of a light guide described in the above description and / or shown in the figures 30 on so the 9 an embodiment of a motor vehicle lighting device according to the invention 100 shows.

QUOTES INCLUDE IN THE DESCRIPTION

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Patent literature cited

• DE 102015210372 A1 [0004]

Claims (15)

Motor vehicle lighting device (100) with a light guide (30), which has a front side (34), at least part of which serves as a light exit surface, and which has a rear side (22) opposite the light exit surface, the rear side having decoupling elements (28) which are set up to deflect light (26) incident on them from the inside of the light guide (30) so steeply to the light exit surface that the deflected light exits the light guide (30) via the light exit surface, characterized in that the front side (34) is parallel has grooves (32) running in the light guide (34) to a main direction of propagation (z). Motor vehicle lighting device (100) Claim 1 , characterized in that a distance between the light exit surface located in the front side (34) and the rear side (22), apart from influences of modulations of the light exit surface and / or the rear side caused by the grooves (32) and by the decoupling elements (28) (22) the distance is constant. Motor vehicle lighting device (100) Claim 1 or 2 , characterized in that the light exit surface lying in the front (34) in a direction transverse to the main light propagation direction (z) and transverse to the distance between the light exit surface and the rear side (22), apart from modulations of the light exit surface formed by the grooves (32) , is just. Motor vehicle lighting device (100) according to one of the preceding claims, characterized in that at least a plurality of the grooves (32) in cross sections which are perpendicular to the main light propagation direction (z) have a cross section with a curved edge. Motor vehicle lighting device (100) Claim 4 , characterized in that a part of the grooves (32) has a concavely curved edge and another part of the grooves (32) has a convexly curved edge. Motor vehicle lighting device (100) Claim 4 , characterized in that all the grooves (32) of the plurality have a convexly curved edge. Motor vehicle lighting device (100) Claim 4 , characterized in that all the grooves (32) of the plurality have a concavely curved edge. Motor vehicle lighting device (100) according to one of the Claims 4 to 7 , characterized in that the edge has a circular curvature. Motor vehicle lighting device (100) according to one of the Claims 4 to 7 , characterized in that the edge has a free-formed curvature deviating from a circular shape. Motor vehicle lighting device (100) according to one of the Claims 6 to 9 , characterized in that the cross sections are all the same. Motor vehicle lighting device (100) according to one of the Claims 6 to 9 , characterized in that the cross sections are not all the same. Motor vehicle lighting device (100) according to one of the preceding claims, characterized in that a light-scattering or light-reflecting surface (38) facing the rear side (22) is arranged behind the rear side (22). Motor vehicle lighting device (100) according to one of the preceding claims, characterized in that the front face 34 having the light exit surface extends around at least one further light exit surface (102, 104), the further light exit surface (102, 104) being a light exit surface of at least one headlight light module of the motor vehicle lighting device (100) and the main directions of light propagation (z) of the light emerging from said light exit surfaces match. Motor vehicle lighting device (100) according to one of the preceding claims, characterized in that the amplitudes (a) of the modulation of the light exit surface caused by the grooves (32) are smaller than the amplitudes (A) of the modulation of the rear side caused by the decoupling elements (28). 22). Motor vehicle lighting device (100) according to one of the preceding claims, characterized in that the outcoupling elements (28) have edges which run continuously across the directions of the grooves (32) and over several grooves (32).

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