Lighting device for vehicles

Abstract

Lighting device for vehicles with a light source (5, 6) and a flat light guide (1) associated with it, - comprising several narrow-sided light coupling surfaces (7) on a light coupling side facing the light source (5, 6), each associated with the light source (5, 6), for coupling light emitted by the light source (5, 6) into the flat light guide (1), - comprising a ceiling surface adjoining the narrow-sided light coupling surface (7), - comprising a floor surface (3) adjoining the narrow-sided light coupling surface (7) and running parallel to the ceiling surface (2), - comprising a narrow-sided light coupling surface (8), characterized in that the narrow-sided light coupling surface (8) has a first light coupling section (9) for emitting a first light beam (L2, L3) and a second light coupling section (10) for emitting a second light beam (L1),and that the narrow-sided light coupling surface (7) is shaped such that the second light coupling section (10) is supplied with a higher luminance by means of the second light beam (L1) than the first light coupling section (9).

Description

The invention relates to a lighting device for vehicles having a light source and a flat light guide assigned to the light source, having on a light input side facing the light source a plurality of narrow-side light input surfaces each assigned to the light source for input of light emitted by the light source into the flat light guide, having a ceiling surface adjoining the narrow-side light input surface, having a floor surface adjoining the narrow-side light input surface and running parallel to the ceiling surface, which floor surface has a narrow-side light output surface.EP 2 065 635 B1 discloses a lighting device for vehicles having a light source and a flat light guide, which has an ellipsoidal light coupling element on a light coupling-in side for the concentrated diffusion of light into the flat light guide. On a side opposite the light input side, a light output surface is arranged, on which the input light exits in order to generate a predefined light function. Over the entire narrow-sided light decoupling surface, a homogeneous illumination of the same is produced.DE 10 2014 102 496 A1 discloses a lighting device for vehicles with a planar light guide, in which light is coupled into the light guide via an uneven light coupling surface and is coupled out via a light coupling surface. The light coupling-in surface has a central and an outer coupling-in section, as a result of which the light is directed in a targeted manner into central and outer regions of the light coupling-out surface and homogeneous illumination is achieved.DE 10 2007 019 688 A1 discloses a signal lamp for motor vehicles, which comprises a housing with at least one light source unit and a plurality of rod-shaped light guide elements, wherein the light is coupled into the light guide elements via a common light guide unit. The light guide elements have an inclined surface on the end face facing away from the light source as a light deflection surface, whereby the light is decoupled from the light guide elements in a targeted manner and a concentrated light surface is generated. By grouping and varying lengths of the light guide elements and integrating optical elements and reflectors, different signal light functions can be realized in a space-saving manner and with a styleistically high-quality design.DE 10 2010 005 806 A1 discloses an illumination device having at least one light source arranged on a printed circuit board and at least one planar light guide, wherein the light is coupled into the light guide via a light entry surface arranged in the emission region of the light source and guided to a light exit surface using total reflection. A planar connecting part is formed integrally on the light guide and enables simple and cost-effective fastening of the printed circuit board, wherein the construction causes low light losses and simplifies the assembly.It is an object of the present invention to further develop a lighting device for vehicles containing a flat light guide in such a way that a functional extension is provided in a simple manner, wherein requirements with regard to the appearance of a light decoupling surface can be better fulfilled in particular.To achieve this object, the invention is characterized in conjunction with the preamble of claim 1 in that the narrow-side light decoupling surface has a first light decoupling section for emitting a first light bundle and a second light decoupling section for emitting a second light bundle, and in that the narrow-side light coupling surface is shaped in such a way that the second light decoupling section is acted upon by the second light bundle with a higher luminance than the first light decoupling section.According to the invention, a flat light guide has a light coupling surface in a light coupling region assigned to a light source in each case, such a shape that different sections of a light coupling-out surface on the narrow side are illuminated with light bundles of different luminance. The narrow-side light decoupling surface has a first light decoupling section which is illuminated by a first light bundle. Furthermore, the narrow-side light decoupling surface has a second light decoupling section which is illuminated by a second light bundle, wherein the second light bundle brings about a higher luminance than the first light bundle. The second light bundle serves to generate a predefined signal light function, such as daytime running light or blinking light. The first light beam serves for generating a background illumination or for an ambient illumination. The light decoupling surface of the flat light guide thus has a sudden or divided appearance with different brightnesses. A homogeneous illumination is effected on the one hand in the first light decoupling section and on the other hand in the second light decoupling section, a brightness jump occurring at the edge between the first light decoupling section and the second light decoupling section.According to a preferred embodiment of the invention, the first light decoupling section is formed by a base surface of the narrow-side light decoupling surface, while the second light decoupling section is raised and thus arranged offset in height with respect to the first light decoupling section. The second light decoupling section serving for the signal function is thus arranged so as to be spatially emphasized, while the first light decoupling section serving for background illumination is arranged so as to be spatially set back. This advantageously brings about a three-dimensional appearance of the lighting device.According to a further development of the invention, each light coupling region is assigned at least two light sources which are arranged centered on the narrow-side light coupling surface. The central arrangement of the light sources ensures that homogeneous illumination of the first light decoupling section and of the second light decoupling section is ensured both for a first light function effected by the first light source and for a second light function effected by the second light source. For both signal light functions, a predefined brightness difference is thus effected between the first light decoupling section and the second light decoupling section.According to a further development of the invention, the narrow-sided light coupling surface of the light coupling region has a main lens surface which is respectively assigned to the light source and which is shaped in such a way that a first light portion coupled into the main lens surface impinges directly on the second light coupling-out section. Advantageously, a high luminance can thereby be provided at the second light decoupling section, which is preferably arranged centrally between two opposite longitudinal edges of the light decoupling surface. For this purpose, central light beams are coupled into the flat light guide and are passed on without being totally reflected on a surface thereof.According to a further development of the invention, the main lens surface in the light coupling-in region is formed in such a way that the first light component impinges on the second light decoupling section over a complete horizontal width of the latter. The main lens surface can be designed as a free-form surface, wherein a homogeneous illumination of the second light decoupling section is ensured.According to a further development of the invention, the main lens surface adjoins a spherical surface transversely to the direction of extent of the flat light guide, at which spherical surface a second light component of the light emitted by the light source enters and exits at the first and second light decoupling section after total reflection at a ceiling and floor surface of the flat light guide. This creates uniform illumination, wherein a brightness difference between the first light decoupling section and the second light decoupling section is substantially absent. The second light portion is substantially not bundled by the spherical surface, so that light beams of the second light portion can be guided further toward the light exit side at different angles.According to a further development of the invention, the main lens surface is adjoined in the direction of extent of the flat light guide by a side lens surface which is shaped in such a way that a third light portion coupled in through the side lens surface is totally reflected at a deflection surface of the light coupling region tapering towards the light coupling-in side and is forwarded in the direction of the first light decoupling section and the second light decoupling section. By means of the side lens surface, a focusing of the third light portion running transversely to the direction of extension of the flat light guide is effected, which then impinges on the deflection surface. The side lens surface enables the use of relatively large angles of radiated light beams of the light source running in the extension direction of the flat light guide for the light flux within the surface light guide.According to a further development of the invention, a contour of the tapering deflection surface of the light coupling region specifies a ready-to-illuminate area of the first light decoupling section. Advantageously, by changing the contour of the deflection surface, a light deflection can be adapted to different widths of the first light decoupling section.According to a further development of the invention, the first light decoupling section is provided with scattering elements, so that uniform illumination is ensured.Exemplary embodiments of the invention are explained in more detail below with reference to the drawings.The following are shown: FIG. 1 shows a perspective front view of a lighting device according to the invention according to a first embodiment, FIG. 2 shows a partial rear view of a flat light guide shown in FIG. 1, with two light sources arranged in each case in a light coupling-in region, FIG. 3 is an enlarged view of a narrow-side light coupling surface in the light coupling region, FIG. 4 shows an enlarged partial illustration of the flat light guide on a light decoupling side, FIG. 5 is a vertical section through a light coupling region, FIG. 6 shows a vertical section through the flat light guide in a vertical central plane of the light coupling-in region, FIG. 7 is a perspective rear view of the flat light guide with light rays drawn in, FIG. 8 is a horizontal section through the flat light guide with light rays drawn in; and FIG. 9 is a front perspective view of the flat light guide according to a second embodiment.A lighting device for vehicles may be disposed in a nose or tail portion thereof for generating a signal light function.The lighting device has a flat light guide 1, which has a ceiling surface 2 and a floor surface 3 arranged parallel to the same. The ceiling surface 2 and the floor surface 3 allow the forwarding of light coupled thereto in the main emission direction H by total reflection of light coupled thereto. a plurality of coupling regions 4, preferably parabolic in vertical section, are provided on a light coupling side of the flat light guide 1, each of which is assigned a first light source 5 and a second light source 6. The first light source 5 and the second light source 6 are arranged directly on a narrow-sided light coupling surface 7 of the light coupling region 4. The first light source 5 is arranged at the top in the vertical direction. It is designed as an LED light source emitting white light color and is activated when a daytime running light function is to be generated. The second light source 6 is arranged at the bottom in the vertical direction; it is designed as an LED light source which emits yellow light color and which, when activated, serves to generate a flashing light function.On a light decoupling side of the flat light guide 1, a narrow-side light decoupling surface 8 is provided, which is composed of a first light decoupling section 9 and a second light decoupling section 10. The first light decoupling section 9 is formed by a base surface on the rear side of the flat light guide 1. The second light decoupling section 10 is arranged raised or raised and / or offset in height with respect to the first light decoupling section 9, forming a minimum distance h 1.The ceiling surface 2 and the floor surface 3 as well as a side surface 11 are directly adjacent to the first light decoupling section 9 (base surface). The ceiling surface 2, the bottom surface 3 and the side surface 11 connect the base surface 9 to the coupling-in regions 4 of the flat light guide 1.The first light source 5 and the second light source 6 are each arranged in the coupling regions 4 centered on the narrow-side light coupling surface 7. As can be seen from FIG. 5, the first light source 5 is arranged above a horizontal central plane M of the flat light guide 1 and the second light source 6 is arranged below the central plane M. Since the flat light guide 1 extends in a plane or in the horizontal direction, the flat light guide 1 is formed symmetrically to the central plane M.Alternatively, the flat light guide 1 can also extend in a contour-matched manner to a housing wall or body opening. For example, the flat light conductor 1 can extend in an arc shape or in a stepped manner from the one side surface 11 to the opposite side surface 11.Preferably, the flat light conductor 1 is made in one piece from a transparent material.The narrow-side light coupling surface 7 of the flat light guide 1 has a main lens surface 12, 12' assigned to the first light source 5 and the second light source 6, the spherical surface 13, 13', and the side lens surface 14, 14'. As can be seen from FIG. 3, the main lens surface 12, spherical surface 13 and side lens surface 14 assigned to the first light source 5 are located above the central plane M and the main lens surface 12', spherical surface 13' and side lens surface 14' assigned to the second light source 6 are located below the central plane M. Preferably, the respective main lens surfaces 12, 12', spherical surfaces 13, 13', and side lens surfaces 14, 14' are of identical design.The main lens surface 12, 12' is shaped in such a way that a first light portion L1 coupled into the main lens surface 12, 12' impinges directly on the second light decoupling section 10, see FIG. 6. The first light portion L1 impinges here homogeneously over a complete horizontal width b1 of the second light decoupling section 10.The spherical surface 13, 13' directly adjoins the main lens surface 12, 12' in the vertical direction (transversely to the direction of extension E of the flat light guide 1). The spherical surface 13 assigned to the first light source 5 is thus arranged above the main lens surface 12 and the spherical surface 13' assigned to the second light source 6 is arranged below the main lens surface 12'. A second light portion L2 (drawn in dashed lines in FIG. 6) coupled in through the spherical surface 13, 13' is totally reflected several times on the ceiling surface 2 and the floor surface 3 until it is coupled out at the first light decoupling section 9 and the second light decoupling section 10. It serves for uniform illumination of the first light decoupling section 9 and of the second light decoupling section 10. The spherical surface 13, 13' enables the use of light emitted at a relatively large vertical angle from the first light source 5 or second light source 6.The side lens surface 14, 14' is arranged next to the main lens surface 12, 12' in the horizontal direction (in the extension direction E of the flat light guide 1). It is shaped in such a way that a third light portion L 3 coupled into the side lens surface 14, 14' is totally reflected on a deflection surface 15 of the light coupling region 4 tapering towards the light coupling side in the direction of the first light decoupling section 9 and the second light decoupling section 10, at which it exits. As can be seen from FIG. 7, the main light flux is directed through the main lens surface 12, 12' in the direction of the second light decoupling section 10.In order that the first light decoupling section 9 is illuminated homogeneously over its horizontal illumination width b in 2 fashion, a horizontal contour 16 of the deflection surface 15 can have a corresponding shape or slope. The second light decoupling section 10 is provided with scattering elements 17 which are designed as pincushion optical elements. Alternatively or additionally, the first light decoupling section 9 can also be provided with scattering elements. The scattering elements 17 can consist of scattering translucent material by surface treatment (e.g. surface structuring or surface roughening) or by injection molding on a thin layer. The thin layer can be applied, for example, in the injection molding process to the flat light conductor 1 already injection molded. The scattering elements 17 of the second light decoupling section 10 can also be formed convexly and / or concavely or prismatically.According to the first embodiment, the second light decoupling section 10 is rectangular and is arranged at an inclination to a transverse central plane of the light coupling region 4 intersecting the narrow-side light coupling surface 7 and / or to a transverse plane of the flat light guide 1. On the one hand, the second light decoupling section 10 has a height h1to the first light decoupling section 9, which is smaller than a height h2which defines the distance of the second light decoupling section 10 from the first light decoupling section 9 of an opposite side. The second light decoupling section 10 thus forms the surface of a prism body 18 which projects from the base surface 10 of the flat light guide 1. The prism body 18 has a distance a 1 to longitudinal edges 19 of the base surface 9 and a distance a 2 to a corner edge 20 of the flat light guide 1.According to a second embodiment of the invention according to FIG. 9, oval bodies 21 can protrude from the flat light guide 1 on the light output side, which oval bodies have an oval-shaped second light decoupling section 22. Alternatively, the raised second light decoupling section 22 can also have a circular or other shape.In a first operating state of the lighting device, in which only the first light source 5 is switched on, the daytime running light function is generated as the first light function. If, in another operating state of the lighting device, only the second light source 6 is switched on, a second light function, namely the flashing light function, is generated.A first light beam is emitted by the first light decoupling section 9 for generating a background light function or ambient light function, which is composed of the second light component L 2 and third light component L 3. A second light beam is emitted by the second light decoupling section 10 in order to generate the signal light function, which beam may consist mainly of the first light component L 1 and optionally of the further light components L 2 and / or L 3.Alternatively, the two light sources 5 and 6 can also be switched on simultaneously, so that a specific light function is generated. If necessary, more than two light sources can also be assigned to the same light coupling region 4, so that more than two light functions can be generated.List of reference characters1 Flat light guide 2 Ceiling surface 3 Floor surface 4 Light coupling region 5 1 Light source 6 2 Light source 7 Narrow-side light coupling surface 8 Narrow-side light coupling-out surface 9 1 Light coupling-out portion 10 2 Light coupling-out portion 11 Side surface 12, 12' Main lens surface 13, 13' Spherical surface 14, 14' Side lens surface 15 Deflection surface 16 Horizontal contour 17 Scattering element 18 Prism body 19 Longitudinal edges 20 Corner edges 21 Oval body 22 2 Light coupling-out portion b 1, b 2 Width E Extension direction H Main radiation direction h Distance M Central plane L 1, L 2, L 3 Light component

Claims

Lighting device for vehicles, having a light source (5, 6) and a flat light guide (1) assigned to the latter, - the light input side facing the light source (5, 6) has a plurality of narrow-sided light input surfaces (7) assigned in each case to the light source (5, 6) for input of light emitted by the light source (5, 6) into the flat light guide (1), - the ceiling surface adjoining the narrow-sided light input surface (7), - the floor surface (3) adjoining the narrow-sided light input surface (7) and running parallel to the ceiling surface (2), - the floor surface having a narrow-sided light output surface (8), characterized in that the narrow-sided light output surface (8) has a first light output section (9) for emitting a first light bundle (L2, L3) and a second light decoupling section (10) for emitting a second light bundle (L1), and in that the narrow-side light coupling surface (7) is shaped in such a way that the second light decoupling section (10) is acted upon by the second light bundle (L1) with a higher luminance than the first light decoupling section (9).Lighting device according to claim 1, characterised in that the second light decoupling section (10) of the narrow-side light decoupling surface (8) is arranged raised relative to the first light decoupling section (9).Lighting device according to claim 1 or 2, characterised in that a first light source (5) for generating a first light function and a second light source (6) for generating a second light function are arranged centred in each light coupling region (4) of the flat light guide (1).Lighting device according to one of Claims 1 to 3, characterized in that the narrow-side light coupling surface (7) in the light coupling region (4) has a main lens surface (12, 12') which is assigned in each case to the light source (5, 6) and is shaped in such a way that an coupled-in first light component (L1) impinges directly on the second light decoupling section (10) on the main lens surface (12, 12') and is decoupled as a second light bundle.Illumination device according to one of Claims 1 to 4, characterized in that the main lens surface (12, 12') is shaped in such a way that the first light portion (L1) impinges on the second light decoupling section (10) over a complete horizontal width (b 1) of the latter.Lighting device according to one of Claims 1 to 5, characterized in that, transversely with respect to the direction of extent (E) of the flat light guide (1), the main lens surface (12, 12') is adjoined by a spherical surface (13, 13'), at which a second light component (L2) without refraction enters at the spherical surface (13, 13'), with the result that the second light component (L2) after total reflection occurs at the ceiling surface (2) and the floor surface (3) at the first light decoupling section (9) and the second light decoupling section (10) and is decoupled as a first light bundle.Lighting device according to one of Claims 1 to 6, characterized in that the main lens surface (12, 12') is adjoined in the direction of extent (E) of the flat light conductor (1) by a side lens surface (14, 14'), which is shaped in such a way that a third light portion (L3) coupled in through the side lens surface (14, 14') is totally reflected at a deflection surface (15) of the light coupling region (4) tapering towards the light coupling-in side in the direction of the first light decoupling section (9) and the second light decoupling section (10) and is decoupled as a first light bundle.Lighting device according to claim 7, characterised in that a contour (16) of the tapering deflection surface (15) defines an illumination width (b 2) of the first light decoupling section (9).Lighting device according to one of Claims 1 to 8, characterized in that the first light decoupling section (9) and / or the second light decoupling section (10) is provided with a number of scattering elements (17).Lighting device according to one of Claims 1 to 9, characterized in that the second light decoupling section (10, 22) is contoured in a rectangular or ellipsoidal or circular manner.Lighting device according to one of Claims 1 to 10, characterized in that the narrow-side light coupling-in surface (7) is formed symmetrically with respect to a longitudinal centre plane (M) of the flat light guide (1), and in that the first light source (5) and the second light source (6) are arranged on both sides of the longitudinal centre plane (M).

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