Lighting device for vehicles

Abstract

The invention relates to a lighting device for vehicles comprising a planar light guide (1) - two opposite flat sides (2,2') for total internal reflection of light (3,3') coupled into the planar light guide (1), - a light coupling surface (4) for coupling light (3, 3') onto a narrow-sided light coupling side of the planar light guide (1), a light output surface (8) for coupling out the coupled light (3, 3') at a narrow-sided light output surface, wherein the light output surface (8) of the planar light guide (1) has a recess (10, 10') which is shaped such that an oblique total internal reflection surface (12) is formed, by means of which a part of the coupled light (3, 3') is deflected by an acute angle (φ) in a longitudinal plane (E) of the planar light guide (1).

Description

[0001] The invention relates to a lighting device for vehicles according to the preamble of claim 1.

[0002] From DE 10 2014 102 496 A1, a lighting device for vehicles is known, comprising a planar light guide with two opposing flat sides and two opposing narrow sides, wherein a light coupling surface for coupling light into the light is provided on one narrow side and a light coupling surface for coupling the coupled light out on the other narrow side. The light coupling surface has coupling optics assigned to each light source, so that the light coming from the light source is coupled in such a way that it is homogeneously transmitted to the light coupling surface in the planar light guide. A homogeneous luminous flux distribution results at the light coupling surface.

[0003] From EP 1 898 147 A1, a lighting device for vehicles is known, comprising an elongated cylindrical light guide with a light coupling surface at one end face. A lateral surface of the light guide conducts the coupled light by total internal reflection. This lateral surface has coupling means so that light is coupled out on one longitudinal side of the lateral surface to generate a first light function. Additionally, the lateral surface has a recess so that coupled light striking an oblique total internal reflection surface of the recess is coupled out at a steep angle on the opposite side of the lateral surface to generate a further light function.

[0004] From EP 1 895 228 A1, a lighting device for vehicles is known which has a planar light guide. The planar light guide has opposite flat sides. Light is coupled into one narrow side of the planar light guide, which serves as a light coupling surface. The coupled-in light is coupled out at another narrow side, which serves as a light coupling surface. Several openings are provided within the planar light guide, forming an internal lens and an internal reflector. This allows the coupled-in light to be shaped as desired so that it strikes the light coupling surface homogeneously.

[0005] The object of the present invention is to further develop a lighting device for vehicles in such a way that light coupled into a planar light guide is transformed in a simple manner in such a way that a desired luminous flux distribution is generated at the light coupling surface.

[0006] To solve this problem, the invention has the features of claim 1.

[0007] According to the invention, a recess in the light output surface of a planar optical fiber allows for the simple transformation of the light coupled into the planar optical fiber within the fiber, specifically on the path of the coupled light from the input surface to the output surface. An inclined total internal reflection surface is formed in the recess, by means of which the coupled light is deflected into a region of the output surface where a further portion of the coupled light is emitted, which is not deflected by the inclined total internal reflection surface. Advantageously, this allows for a variation of the luminous flux flowing onto the output surface in order to achieve a desired light distribution along a longitudinal direction of the output surface.In this way, inhomogeneities on the light-input side of the planar optical fiber can be compensated for during light coupling. Furthermore, differences in light values ​​along the light-output surface can be compensated for, ensuring compliance with legally prescribed light values.

[0008] In a further development of the invention, the recess on the light output side of the planar light guide is covered or concealed by a decorative aperture. In this way, the recess is not visible to an observer from the outside.

[0009] In a further development of the invention, the light output surface is segmented. Firstly, it has a first segment with a first sub-surface onto which the coupled light strikes by total internal reflection at the opposite flat surfaces. Secondly, it has a second segment with a second sub-surface onto which, firstly, a first part of the coupled light, guided exclusively by total internal reflection at the opposite flat surfaces, and secondly, a second part of the coupled light strikes, the second part of the coupled light being totally reflected at the opposite flat surfaces and deflected at the total internal reflection surface towards the first sub-surface of the light output surface. Thirdly, it has a third segment with a third sub-surface from which no coupled light is output.This allows, firstly, higher light values ​​to be generated in the second segment and, secondly, a spatial separation of the light extraction for a single, single-piece planar light guide to be realized.

[0010] According to a further development of the invention, two recesses, each with a total internal reflection surface, are arranged at a distance from each other such that coupled light, deflected at the total internal reflection surfaces, strikes different areas of the second partial surface of the light-emitting surface. In this way, the second partial surface of the light-emitting surface can be easily supplied with an increased luminous flux that is homogeneous along its length.

[0011] According to a first embodiment of the invention, a plurality of light sources are arranged in a row along the longitudinal direction of the light coupling surface of the planar light guide. Preferably, the light sources are arranged at equal intervals to ensure homogeneous, direct light coupling. Advantageously, this allows high-intensity light to be coupled into the planar light guide.

[0012] According to a second embodiment of the invention, an elongated light guide is arranged at the light coupling surface of the planar light guide, and light is coupled into its end face. The elongated light guide has output coupling elements, so that light is coupled out on a side facing the light coupling surface of the planar light guide. This results in indirect light coupling, thus reducing the number of light sources required.

[0013] According to a further development of the invention, the planar light guide is manufactured by injection molding, wherein the mold is designed such that the recess is formed during the molding of the planar light guide. This results in relatively low manufacturing costs.

[0014] Further advantages of the invention will become apparent from the further dependent claims.

[0015] Exemplary embodiments of the invention are explained in more detail below with reference to the drawings.

[0016] They show: Fig. 1 a schematic side view of a lighting device according to a first embodiment of the invention (direct radiating system), Fig. 2. A longitudinal section through a planar light guide of the lighting device along section line II-II in Fig. 1, Fig. 3 a schematic side view of a lighting device according to a second embodiment of the invention (indirectly radiating system), Fig. 4 an alternative form of a recess in the planar light guide and Fig. 5 a schematic side view of the lighting device according to a further embodiment.

[0017] A lighting device for vehicles according to the invention can be used to generate a signal light function, for example flashing light, tail light or the like.

[0018] The lighting device comprises a top-shaped housing, which is closed by a translucent end plate. The following components are arranged inside this interior space.

[0019] The lighting device comprises a planar light guide 1, preferably made of a crystal-clear or colored plastic material. The planar light guide 1 has opposing flat sides 2, 2', at which coupled light 3, 3' is totally reflected. In the present embodiment, the planar light guide 1 is flat, so that the opposing flat sides 2, 2' are not only parallel to each other but also planar. The distance between the flat sides 2, 2' can be between 4 cm and 15 cm. The planar light guide 1 is plate-shaped and rectangular.

[0020] A light coupling surface 4 is provided on one narrow side of the planar light guide 1, and a series of light sources 6 are arranged along a longitudinal direction 5 of the light coupling surface 4 or of the planar light guide 1. The light sources 6 are arranged on a common circuit board 7.

[0021] In the present embodiment, the light coupling surface 4 arranged on a light coupling side of the planar light guide 1 is planar. Alternatively, the light coupling surface 4 can be provided with coupling optic elements assigned to each of the light sources 6, so that the coupled light 3, 3' is guided, essentially by total internal reflection, along the opposite flat sides 2, 2' towards an opposite narrow side, which is designed as a light coupling surface 8. It is assumed that even with a planar design of the light coupling surface 4, the coupled light 3, 3' is guided towards the light coupling surface 8, which is indicated by corresponding arrows in Fig. 1 is made clear.

[0022] The light output surface 8 has scattering optics elements 9 by means of which the coupled light 3, 3' is emitted in a scattering manner at a light output side.

[0023] In the present embodiment, the planar light guide 1 has two planes symmetrical to a transverse central plane M. Q The recesses 10 are arranged on the light extraction surface 8. Each recess 10 has opposing walls 11 extending perpendicularly to the light extraction surface 8 and a base connecting the walls 11, which is designed to serve as a total internal reflection surface 12 for light 3' incident upon it. In the present embodiment, the total internal reflection surface 12 is planar and forms an acute angle φ with a plane extending perpendicular to the light extraction surface 8. The acute angle φ can, for example, be in a range between 40° and 50°.

[0024] According to an alternative embodiment of the invention, which is not shown, the oblique total reflection surface 12 can also be slightly curved or arc-shaped.

[0025] The recess 10 is designed such that the walls 11 are connected to each other only via the total internal reflection surface 12. Along the flat sides 2, 2', the recesses 10 are open. They thus form, as it were, incisions in the light-emitting surface 8.

[0026] Since the recesses 10 are arranged within the planar light guide 1 with their total internal reflection surface 12 inclined to the direction of light propagation L, the incident light 3' is essentially totally reflected. Only a very small fraction of the incident light 3' is allowed to pass through. To prevent the resulting scattered light from escaping, the recess 10 is covered or concealed by a decorative aperture 13. The decorative aperture 13 can, for example, be a strip of a frame (not shown) or be affixed to the light-emitting side of the planar light guide 1. The decorative aperture 13 can, for example, be designed as a chrome strip.

[0027] In the present embodiment, the total reflection area 12 of the recesses 10 extends in a central region of the planar light guide 1 between the light coupling surface 4 and the light coupling surface 8.

[0028] The planar light guide 1 has several segments that differ in that a different luminous flux is coupled out at the light coupling surface 8.

[0029] In the present embodiment, the planar light guide 1 has three different segments.

[0030] A first segment S1 of the planar light guide 1 has a first partial surface 14 of the light coupling surface 8, onto which totally reflected light 3 exclusively by total internal reflection on the opposite flat sides 2, 2' strikes and is coupled out at this surface.

[0031] A second segment S2 of the planar light guide 1 has a second partial surface 15 of the light coupling surface 8, onto which, on the one hand, totally reflected light 3 occurs exclusively by total internal reflection on the opposite flat sides 2, 2', and on the other hand, totally reflected light 3' occurs on the total internal reflection surface 12 of the two recesses 10 and is coupled out at this point.

[0032] The first segment S1 and the second segment S2 have in common that within these segments S1 and S2 there is only total internal reflection of the light 3 on the opposite flat sides 2, 2'.

[0033] A third segment S3 of the planar light guide 1 has the recess 10 with the total internal reflection surface 12. It is covered by the decorative aperture 13.

[0034] In the present embodiment, two recesses 10 are symmetrical about a transverse median plane M QThe total internal reflection surfaces 12 of the two recesses 10 are arranged such that the light 3' reflected from them is reflected to the central sub-surface 15 of the light output surface 8. The central sub-surface 15 of the light output surface 8 is located in the second segment S2 adjacent to the third segment S2, which has the total internal reflection surface 12. The light 3' reflected from the total internal reflection surface 12 strikes different areas of the second sub-surface 15, so that a uniformly increased luminous flux is present at the second sub-surface 15 of the light output surface 8 compared to the luminous flux at the first sub-surface 14 of the light output surface 8.

[0035] As from Fig. As can be seen in Figure 1, the light 3' coupled into the third segment S3 of the planar optical fiber 1 is deflected by means of the total internal reflection surface 12 in a longitudinal plane E of the planar optical fiber 1, so that it strikes the second sub-surface 15 of the second segment S2. The longitudinal plane E of the planar optical fiber 1 runs perpendicular to the transverse median plane M. Q The longitudinal plane E of the planar optical fiber 1 runs parallel to the flat sides 2, 2' of the planar optical fiber 1.

[0036] According to an alternative embodiment of a recess 10' Fig. 4. This recess 10' can have a shallower depth compared to recess 10. Recess 10' has only a single, relatively short path 11', from which the total internal reflection surface 12 extends to a plane of extension of the light coupling surface 8.

[0037] According to a further embodiment of the invention according Fig. 3. An elongated cylindrical light guide 16 is provided on a light entry side of the planar light guide 1. This light guide has a lateral surface 17 and an end surface 18 on opposite sides. A light source 6 is arranged on each end surface 18, emitting light 19 in the direction of the end surface 18. The light 19 is coupled into the light guide 16 at the end surface 18. The light guide 16 has coupling means (not shown) that deflect the coupled light 19 towards a longitudinal side 20 of the lateral surface 17 facing the light entry surface 4 of the planar light guide 1 and are coupled out at this side. This is therefore an indirectly emitting system. The embodiment according to the Fig. 1 and Fig. 2 represents a direct radiating system, since the light 3, 3' emitted by the light sources 6 is introduced directly into the light coupling surface 4 of the planar light guide 1.

[0038] The planar light guide 1 can be manufactured by injection molding. The mold of the injection molding machine is shaped such that at least one recess 10,10' is formed.

[0039] The light sources 3 are designed as LED light sources.

[0040] Another embodiment of the invention is described in Fig. 5 shown. It differs from the embodiment according to Fig. 1. This is because a light coupling surface 4' is not parallel to a light coupling surface 8 of the optical fiber 1. The light coupling surface 4' and the light coupling surface 8 are therefore not arranged parallel to each other.

[0041] In the present embodiment, the total internal reflection surface 12 is somewhat flatter and longer, with the total internal reflection surface 12 forming an angle φ' with the wall 11. A further difference from the embodiment according to Fig. The feature is that only a single recess 10 is provided. The light is deflected into the second segment S2 at the total internal reflection surface 12.

[0042] According to a further alternative embodiment of the invention, not shown, the light guide can be used in accordance with Fig. 5 also have two recesses 10, as in the embodiment according to Fig. 1.

[0043] According to a further alternative embodiment of the invention, not shown, the embodiment can be described as follows: Fig. 1 only have a single exception 10.

[0044] The number of recesses or extent and / or the relative position of the light input side and the light output side depends on the installation space of the lighting device. Reference symbol list 1. Flat optical fibers 2.2' Flat sides 3.3' light 4 Light coupling area 5 Longitudinal direction 6 light source 7 printed circuit board 8 Light extraction area 9 diffusing optical elements 10, 10' recess 11, 11' hike 12 Total internal reflection area 13 Decorative panel 14 First sub-area 15 Second sub-area 16 optical fibers 17 Surface area 18 Front surface 19 lights 20 Long side S1 1st Segment S2 2nd segment S3 3rd segment φ angle E Longitudinal plane M Q transverse median plane L Light propagation direction QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] DE 10 2014 102 496 A1

[0002] EP 1 898 147 A1

[0003] EP 1 895 228 A1

[0004]

Claims

[1] Lighting device for vehicles comprising a planar light guide (1) - two opposite flat sides (2,2') for total internal reflection of light (3,3') coupled into the planar light guide (1), - a light coupling surface (4) for coupling light (3, 3') onto a narrow-sided light coupling side of the planar light guide (1), - a light output surface (8) for coupling out the coupled light (3, 3') at a narrow-sided light output surface, characterized by , that the light output surface (8) of the planar light guide (1) has a recess (10, 10') which is shaped in such a way that an oblique total internal reflection surface (12) is formed, by means of which a part of the coupled light (3, 3') is deflected by an acute angle (φ) in a longitudinal plane (E) of the planar light guide (1). [2] Lighting device according to claim 1, characterized by, that the oblique total reflection surface (12) is flat or slightly curved. [3] Lighting device according to claim 1 or 2, characterized by , that the oblique total reflection surface (12) forms an oblique base of the recess (10, 10') from which at least one wall (11, 11') extending perpendicular to the light output surface (8) extends to the light output surface (8). [4] Lighting device according to any one of claims 1 to 3, characterized by , that the recess (10, 10') is covered and / or concealed by a decorative panel (13). [5] Lighting device according to any one of claims 1 to 4, characterized by , that the recess (10, 10') extends continuously from a first flat side (2) to a second flat side (2') of the planar light guide (1). [6] Lighting device according to any one of claims 1 to 5, characterized by, that the total reflection surface (12) runs in a central region of the planar light guide (1) between the light coupling surface (4) and the light coupling surface (8). [7] Lighting device according to any one of claims 1 to 6, characterized by , that the light output surface (8) has a number of first subsurfaces (14) onto which the light (3) totally reflected exclusively on the opposite flat sides (2, 2') strikes. [8] Lighting device according to any one of claims 1 to 7, characterized by , that the light output surface (8) has a number of second sub-surfaces (15) onto which, on the one hand, a first part of light (3) totally reflected exclusively by total internal reflection at the opposite flat sides (2, 2') of the planar light guide (1) and, on the other hand, a second part of coupled light (3') with additional deflection at the total internal reflection surface (12) strikes. [9] Lighting device according to any one of claims 1 to 8, characterized by , that two recesses (10, 10') each with a total reflection surface (12) are arranged at a distance (a) from each other such that the light (3') deflected at the total reflection surfaces (12) hits different areas of the second partial surface (15) of the light coupling surface (8). [10] Lighting device according to any one of claims 1 to 9, characterized by , that the light output surface (8) of the planar light guide (1) has scattering optical elements. [11] Lighting device according to any one of claims 1 to 10, characterized by , that the light coupling surface (4) has coupling optic elements. [12] Lighting device according to any one of claims 1 to 11, characterized by, that a series of light sources (6) are arranged on the light coupling surface (4) such that a main emission direction of the light sources (6) is perpendicular to the light coupling surface (4). [13] Lighting device according to any one of claims 1 to 11, characterized by , that an elongated light guide (16) is arranged on the light coupling surface (4) of the planar light guide (1), on at least one end face (18) of which a light source (6) is arranged for emitting light (19) into the elongated light guide (16) and that the elongated light guide (16) has coupling elements such that the coupled light (19) is coupled out on a longitudinal side (20) of a lateral surface (17) of the elongated light guide (16) facing the light coupling surface (4) of the planar light guide (1). [14] Lighting device according to any one of claims 1 to 11, characterized by, that the planar light guide (1) is manufactured by injection molding. [15] Lighting device according to any one of claims 1 to 11, characterized by , that the light sources (6) are designed as LED light sources.

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