Lighting device for vehicles

A lighting device having a first lighting unit comprising a first light source and a first optics element, disposed upstream thereof in the main beam direction, for generating a first lighting function. The lighting device also has a second light source and a second optics element, disposed upstream thereof in the main beam direction, for generating a second lighting function. The first optics element, disposed in front of the first light source in the main beam direction, is designed as a flat waveguide having a narrow-side light intake surface, having a narrow-side light output surface, and having opposing flat sides connecting the light intake surface and the light output surface. The light intake surface of the flat waveguide is disposed at such a spacing to the first light source that a lateral light beam emitted by the first light source strikes the second optics element in order to illuminate said optics element.

CROSS REFERENCE

This application claims priority to International Application No. PCT/EP2014/059170, filed on May 6, 2014, which itself claims priority to German Application No. 10 2013 104590.1, filed May 6, 2013, both of which are hereby incorporated by reference.

FIELD OF TECHNOLOGY

The invention relates to a lighting device for vehicles having a first lighting unit comprising a first light source and a first optics element, disposed upstream thereof in the main beam direction, for generating a first lighting function, and having a second lighting unit comprising a second a second light source and a second optics element, disposed upstream thereof in the main beam direction, for generating a second lighting function.

BACKGROUND

A lighting device for vehicles is known form DE 102 05 048 A1 having at least two lighting units with different lighting functions. A first lighting unit has a light source as well as an optics element having a curved lateral surface, such that a light bundle is emitted at a relatively large angle to the side, in order to generate a cornering light function. A second lighting unit is provided adjacent to this first lighting unit, having a light source and a reflector as the second optics element, which serves to generate a turn signal light function. The known lighting device enables a space-saving arrangement of numerous lighting units.

In order to generate a daytime running lamp function, flat waveguides are currently used as an optics element disposed upstream of a light source, wherein the flat waveguides have a narrow light intake surface and a narrow light output surface. Opposing flat sides extend between the light intake surface and the light output surface, at which an entering light is conducted toward the light output surface through total internal reflection. The disadvantage with such a daytime running light lighting unit is that the flat waveguides must have a relatively long design due to the narrow light output surface in order to fulfill the legal requirements regarding the minimum lighting area for the lighting function.

SUMMARY OF THE INVENTION

The object of the present invention is thus to further develop a lighting device for vehicles such that the lighting surface of a lighting unit is enlarged in a simple manner, while saving space.

In order to achieve this object, the invention may be characterized in that the first optics element disposed in the main beam direction in front of the first light source is designed as a flat waveguide having a narrow-side light intake surface, having a narrow-side light output surface, and having opposing flat sides connecting the light intake surface and the light output surface, and in that the light intake surface of the flat waveguide is disposed at such a spacing to the first light source that a lateral light beam emitted by the first light source strikes the second optics element in order to illuminate said optics element.

The particular advantage of the invention is that, in a space saving manner, an optics element of an adjacent second lighting unit is used for the illumination of a first lighting unit. A light source allocated to the optics element of the first lighting unit can emit a sub-light beam laterally, such that it does not strike the first optics element, but rather, it strikes a second optics element of the adjacent second lighting unit. If the second lighting unit is in a standby mode, the second optics element is illuminated by laterally emitted sub-light beam (lateral light beam) from the first light source, and can serve to increase the illumination area of the actual first lighting unit. According to the invention, a main light beam enters the first optics element disposed upstream of the first light source and a lateral light beam enters the second optics element allocated to the second lighting unit.

According to a preferred embodiment of the invention, the second optics element is disposed at such a spacing to the second light source of the second lighting unit that the lateral light beam of the first light source strikes a light entry surface of the second optics element. The angle of incidence for the light of the lateral light beam on the light entry surface of the second optics element can be relatively large. It is sufficient when the second optics element also provides illumination, without using light beams for lighting the area in front thereof. The illumination of the second optics element is just great enough that a lighting of the immediate surroundings originates therefrom, which can be detected with light meters, and which fulfills the legal requirements regarding the minimal illumination area for the first lighting function.

According to a further development of the invention, the first optics element has a flat area on a surface facing the second optics element, such that a light path to the second optics element is made available for the lateral light beam. Advantageously, this results in a branching off of a lateral light beam in a simple manner, wherein a main light beam enters the first optics element, and is emitted at the light output surface thereof in accordance with a predefined light distribution.

According to a further development of the invention, an optical separating wall is disposed between the first optics element and the second optics element, such that there is no coupling, or interaction between the first optics element and the second optics element in a region between the light entry surface and the light exit surface.

According to a further development of the invention, the second optics element is designed as a lens, which emits a main light function as the lighting function in interacting with the second light source, such as a low beam function, for example. When the first lighting function is used as a secondary lighting function, this results in a convenient functional linkage, in which the second optics element exhibits a double function. When the second light source is switched on, and the first light source is switched off, it serves to generate the main lighting function. When the second light source is switched off and the first light source is switched on, it serves to generate the secondary lighting function.

According to a further development of the invention, the second optics element has a lateral extension perpendicular to the separating wall, which is at least three times as great as a lateral extension of the flat waveguide. In this manner it is ensured that a sufficiently large illumination area is provided for the first lighting function.

According to a further development of the invention, the first light source and the second light source are disposed on a common plane of extension. By way of example, the two light sources can be disposed on a shared printed circuit board, thus reducing costs.

DETAILED DESCRIPTION OF THE DRAWINGS

A lighting device according to the invention can be used in a front or rear region of a vehicle. In the present exemplary embodiment, the lighting device has a first lighting unit1as well as a second lighting unit2disposed in a housing (not shown). The lighting device is mounted as a headlamp in the front region of the vehicle.

The first lighting unit1serves to generate a secondary lighting function, e.g. a daytime running lights function, and has at least one light emitting diode (LED) as the first light source3. The LED light source3is disposed upstream of a first optics element4in the main beam direction H, which optics element is designed as a flat waveguide. The flat waveguide4has a narrow design in the main beam direction H. It has a narrow-side light intake surface5on a side facing the first light source3, and has a light output surface6on a side facing away from the first light source3. Opposing flat sides7having relatively large dimensions extend between the light intake surface5and the light output surface6, at which light beams L1of a main light beam HL emitted from the first light source3are conducted through total internal reflection toward the light output surface6.

A longitudinal central plane8of the first lighting unit1runs parallel to the flat sides7of the flat waveguide4. The main beam direction H of the first lighting unit1runs in the longitudinal central plane8.

The second lighting unit2is disposed, at a spacing along a norm of the flat sides7, adjacent to the first lighting unit1, having a second light source9and a second optics element disposed in front of the second light source9in the main beam direction H. The second light source9is designed—like the first light source3—as an LED light source. The second optics element10is designed as a lens, preferably a plano-convex lens. The plan-convex lens10is disposed such that it is not rotationally symmetrical to an optical axis11of the second lighting unit2. The lens10has a flat light entry surface12, which is disposed at an axial spacing b to the second light source9, or a printed circuit board13on which the second light source9is mounted. Alternatively, the light entry surface12can also be designed with a convex or concave shape. A convex light exit surface14runs on a side of the lens10facing away from the second light source9, which is struck by light beams L2emitted by the second light source9for generating a main lighting function, e.g. a low beam lighting function, in the main beam direction H, which is subjected to refraction. The light output surface15is designed as a freeform surface, which can, for example, exhibit optics elements.

The lens10has a transverse extension c2, which is at least three times as great as a transverse extension c1of the flat waveguide4.

Preferably numerous LED light sources3are provided as the first light sources3for the first lighting unit1, which extend perpendicular to the plane of the drawing at a predefined spacing on a narrow printed circuit board15. The length of the printed circuit board15corresponds to a length of the flat waveguide4. The length of the flat waveguide4running perpendicular to the plane of the drawing is not sufficient to exceed the dimensions of the light output surface of the predefined minimum illumination area pursuant to the ECE regulation of 25 cm2.

In order to achieve the minimum illumination area for the first lighting unit1when generating a daytime running lights lighting function, the first optics element4has a flat area on a side facing the adjacent second optics element10, such that a lateral light beam SL emitted by the first light source3is emitted, or branched off, respectively, with light beams L1′ toward the second optics element10. Preferably the light beams L1′ strike the light entry surface12of the second optics element10.

A spacing between the light intake surface5of the flat waveguide4and the first light source3, or the printed circuit board15, respectively, is selected such that preferably the lateral light beam SL strikes the second optics element10, through the use of the flat area16, and an illumination thereof toward the main beam direction H is obtained. The portion of the lateral light beam SL to the overall light beam emitted by the first light source3can be small enough that the lens10is illuminated in an ambient manner, without the participation of the lateral light beam SL for generating a light distribution. To an observer, an illumination area appears having dimensions corresponding to the projection of the light exit surface14of the lens10in relation to a plane running perpendicular to the main beam direction H.

In order to generate a daytime running lights lighting function, only the first light source3is switched on, while the second light source9remains off. In this operating state, a strong light intensity of the main light distribution HL is emitted by means of the first optics element4and a weak light intensity of the lateral light distribution SL is emitted by means of the second optics element10in the main beam direction H.

In order to generate the main light distribution, the first light source3is switched off, while the second light source9is switched on. The main light distribution AL is emitted solely via the second optics element10.

In order to prevent an interaction of the two lighting functions “main light” and “secondary light,” a separating wall17is disposed between the first lighting unit1and the second lighting unit2, this wall being opaque in design. The separating wall17extends in a region between the light entry surface12of the second optics element10up to a light output surface6of the first optics element4, preferably beyond the light output surface6.

The first light sources3as well as the second light source9are positioned in a common plane of extension E, which runs perpendicular to the main beam direction H. By way of example, the first light sources3and the second light source9can be disposed on a shared printed circuit board. Alternatively, the light sources3,9can also be disposed in different planes of extension, such that they are offset in the main beam direction (H).

According to an alternative embodiment of the invention, not shown herein, more than two lighting units can also be disposed adjacent to one another, wherein a lateral light beam is branched off from at least one lighting unit, in at least one direction.

In the present exemplary embodiment, the light intake surface5of the first optics element4has a channeling18allocated, respectively, to the first light sources, for an improved introduction of light into the flat waveguides5.

The optics elements4,10are made from a transparent material, preferably a transparent plastic.

LIST OF REFERENCE SYMBOLS