Lighting device for a motor vehicle headlight

Abstract

The invention relates to a lighting device (1a) for a motor vehicle headlight, comprising a first light-guide (2) unit having a retaining bar (2a) and at least two outcoupling bars (2b) arranged at least at a distance from one another and protruding from the retaining bar (2a), a second light-guide unit (3) having a retaining bar (3a) and at least one outcoupling bar (3b) protruding from the retaining bar (3a), a number of light sources (4) for coupling light into the outcoupling bars (2b, 3b) of the light-guide units (2,3), wherein at least one light source (4) is associated with each outcoupling bar (2b, 3b), and comprising at least one lens (5), preferably a projection lens, arranged after the light-guide units (2, 3) for generating a light distribution, wherein each outcoupling bar (2b, 3b) has a light-outcoupling surface (2c, 3c) for emitting light into the at least one lens (5), wherein the first and the second light-guide units (2, 3) are separate components from one another, which are arranged in relation to one another in such a way that a respective outcoupling bar (3b) of the second light-guide unit (3) is arranged between neighbouring outcoupling bars (2b) of the first light-guide unit (2), and wherein an aperture (11) is arranged between the lens (5) and the light-outcoupling surfaces (2c, 3c) of the outcoupling bars (2b, 3b).

Claims

1. A lighting device (1a) for a motor vehicle headlight comprising: a first light-guide unit (2) having a retaining bar (2a) and at least two outcoupling bars (2b) spaced apart from one another and protruding from the retaining bar (2a); a second light-guide unit (3) having a retaining bar (3a) and at least one outcoupling bar (3b) protruding from the retaining bar (3a); a number of light sources (4) for coupling light into the outcoupling bars (2b, 3b) of the first and second light-guide units (2, 3), wherein at least one of the light sources (4) is associated with each of the outcoupling bars (2b, 3b); and at least one lens (5) arranged downstream of the first and second light-guide units (2, 3) for generating a light distribution, wherein each of the outcoupling bars (2b, 3b) has a light-outcoupling surface (2c, 3c) for emitting light into the at least one lens (5), wherein the first and second light-guide units (2, 3) are components separate from one another and arranged such that a respective outcoupling bar (3b) of the second light-guide unit (3) is arranged between neighbouring outcoupling bars (2b) of the first light-guide unit (2), and wherein an aperture (11) is arranged between the at least one lens (5) and the light-outcoupling surfaces (2c, 3c) of the outcoupling bars (2b, 3b) configured to limit the light coupled from the outcoupling bars (2b, 3b) into the at least one lens (5) such that the light distribution emitted by the lighting device (1a) is limited by a single continuous straight bottom edge (UK), wherein the aperture (11) has an opening through which light is guided from the outcoupling bars into the at least one lens, wherein, when installed, an upper side of the opening is limited by a horizontal edge.

2. The lighting device (1a) according to claim 1, wherein the aperture (11) is implemented integrally.

3. The lighting device (1a) according to claim 1, wherein the first light-guide unit (2) has a number of n outcoupling bars protruding from the retaining bar, wherein the second light-guide unit has a number of n1 outcoupling bars protruding from the retaining bar.

4. The lighting device (1a) according to claim 3, wherein n=3, n=4, or n5.

5. The lighting device (1a) according to claim 1, wherein the first light-guide unit (2) has a number of n outcoupling bars protruding from the retaining bar, wherein the second light-guide unit has a number of n outcoupling bars protruding from the retaining bar.

6. The lighting device (1a) according to claim 5, wherein n=3, n=4, or n5.

7. The lighting device (1a) according to claim 1, wherein the first and/or second light-guide units (2, 3) are implemented as transparent solid bodies.

8. The lighting device (1a) according to claim 1, wherein the first and/or second light-guide units (2, 3) are implemented as light-guiding hollow bodies.

9. The lighting device (1a) according to claim 1, wherein at least one LED light source is associated with each outcoupling bar (2b, 3b).

10. The lighting device (1a) according to claim 1, wherein at least some of the light sources associated with the outcoupling bars (2b, 3b) are actuatable individually to generate a dynamic light distribution.

11. The lighting device (1a) according to claim 10, wherein all of the light sources associated with the outcoupling bars (2b, 3b) are actuatable individually to generate the dynamic light distribution.

12. A motor vehicle headlight comprising at least one lighting device (1a) according to claim 1.

13. A motor vehicle comprising at least one lighting device (1a) according to claim 1.

14. The lighting device (1a) according to claim 1, wherein all of the light sources associated with the outcoupling bars (2b, 3b) are actuatable individually to generate a dynamic light distribution.

15. A motor vehicle comprising two motor vehicle headlights, each of which comprises a lighting device (1a) according to claim 1.

16. The lighting device (1a) according to claim 1, wherein the at least one lens (5) is a projection lens.

17. The lighting device (1a) according to claim 1, wherein the single continuous straight bottom edge (UK) is in the form of a horizontal line.

18. The lighting device (1a) according to claim 1, wherein the at least one lens (5) is a projection lens and the single continuous straight bottom edge (UK) is in the form of a horizontal line.

Description

(1) The invention will be discussed below in more detail based on an exemplary and not limiting embodiment illustrated in the figures, where

(2) FIG. 1 shows a schematic view of a lighting device according to the prior art, and FIG. 1a shows a detailed view of FIG. 1;

(3) FIG. 1a shows a detailed view of a beam path through light-guide units of FIG. 1;

(4) FIG. 2 shows a schematic view of multiple light segments generated by the lighting device of FIG. 1;

(5) FIGS. 3 and 4 show an exemplary arrangement of individual components of a lighting device;

(6) FIGS. 5 and 6 show examples of light-guide unit arrangements;

(7) FIG. 7 shows a sectional view of an embodiment according to the invention of a lighting device and FIG. 7a shows a detailed view of FIG. 7;

(8) FIG. 8 shows a view of the light distribution of the lighting device of FIG. 7;

(9) FIG. 9 shows a front view on an aperture of the lighting device.

(10) If not stated otherwise, the same features will be indicated by the same reference numerals throughout the figures.

(11) FIG. 1 shows a schematic view of a lighting device 1 according to the prior art. The lighting device 1 is adapted for use in a motor vehicle headlight and comprises a first light-guide unit 2 and a second light-guide unit 3, the first light-guide unit 2 almost completely covering the second light-guide unit 3 in this perspective view.

(12) The light-guide units 2 and 3 are configured to guide light being coupled into the light-guide unit 2 or 3 via upstream light sources 4 into a downstream lens 5. The light-guide units 2 and 3 are aligned respectively to the optical axis OA of the lens 5 for guiding light into the lens 5. Due to various mounting inaccuracies and/or manufacturing tolerances that will be discussed further below in more detail with reference to FIGS. 3-6, in that instance, the light-guide units 2 and 3 may be offset from one another in a vertical direction such that a bottom edge of the light distribution of the light image generated by the lighting device will be stepped. In this case, the second light-guide unit 3 has an upward offset and the first light-guide unit 2 has a downward offset, whereby an edge ray L3 outcoupled by the second light-guide 3 has an offset to the edge ray L2 outcoupled by the first light-guide unit 2. Here, an edge ray refers to a ray of light located in the outermost edge region of the solid angle illuminated by a light-guide unit 3 and thus setting the limits of the light distribution. If not stated otherwise, all indications of direction refer to the lighting device when mounted. FIG. 1a shows a detailed view of the light-guide units 2 and 3 offset to one another and the exemplary edge rays L2 and L3.

(13) FIG. 2 shows the effects of offsetting the light-guide units 2 and 3 to one another. The first light-guide unit 2 projects individual light segments 6a; the remaining light segments 6b originate from the second light-guide unit 3. Offsetting both light-guide units 2 and 3 to one another will result in offsetting the light image bottom edges LBK-L2 and LBK-L3 to one another. As a result, the light distribution emitted by the lighting device 1 has a bottom edge limiting the light distribution which is stepped, particularly according to a rectangular function.

(14) In order to discuss more clearly the reasons for offsetting the individual light-guide units 2 and 3 to one another, an exemplary structure of a lighting device 1 will be described below with reference to the FIGS. 3 and 4. FIG. 3 shows an exploded view of the lighting device 1, where the light sources 4 are arranged on a carrier element 8. The carrier element may be inserted into a support device 9 that, in turn, is configured to receive the light-guide units 2 and 3. For this purpose, the support device 9 also has depressions 9a limited by guide walls 9b, enabling the light-guide units 2 and 3 to be supported within the depressions 9a. In order to ensure the light-guide units 2 and 3 are being inserted reliably into the depressions 9a despite manufacturing tolerances that, for example, may be due to the manufacturing process of the light-guide units 2 and 3 and the support device 9, the depressions 9a typically have slightly larger dimensions than the corresponding dimensions of the light-guide units 2 and 3. Therefore, the light-guide units 2 and 3 are supported with a certain clearance within the depressions 9a, resulting in possible uncertainties in positioning the light-guide units 2 and 3.

(15) Further, in FIG. 3, the first light-guide unit 2 can be easily recognised as comprising a retaining bar 2a having three outcoupling bars 2b protruding therefrom. The second light-guide unit 3 also comprises a retaining bar 3a having two outcoupling bars 3b protruding therefrom, wherein, in this case, two light sources 4 are associated with each outcoupling bar 2b or 3b. Each of the segments 6a and 6b shown in FIG. 2 is generated by the light sources 4 coupling light into the respective outcoupling bar 2b or 3b by the coupled light exiting the outcoupling bars 2b and 3b through light-outcoupling surfaces 2c and 3c, respectively, and being projected through the downstream lens 5 (see FIG. 1) onto an area in front of the lighting device 1.

(16) FIG. 4 shows the components of FIG. 3 when assembled, where the light-guide units 2 and 3 are secured against slipping out of the depression 9a by a cover not shown in FIG. 3 which is clamped on the support device 9.

(17) FIGS. 5 and 6 show a top view of the light-guide units 2 and 3 and their light-outcoupling surfaces 2c and 3c limited in a vertical direction by a bottom edge (UnterkanteUK) and a top edge (OberkanteOK) indicated by dashed lines. The bottom edge UK being arranged above the top edge OK at the light-outcoupling surfaces is due to the light distribution being inverted by the downstream lens 5. In FIG. 5, the first and the second light-guide units 2 and 3 are arranged in a desired position such that the top and bottom edges OK and UK of the light exit surfaces 2c and 3c are aligned with one another. The vertical distances to the guide walls 9b of the support device 9 are the nominal lengths a1 and a2. By contrast, in FIG. 6, the light-guide units 2 and 3 as shown in FIGS. 1 and 2 are offset to one another, wherein the distances a1 and a2 to the side walls 9b are significantly reduced relative to the distances a1 and a2. As a result, contrary to the arrangement of FIG. 5, the top and bottom edges OK and UK are not aligned with one another anymore but define a rectangular function, as described above with reference to FIG. 2.

(18) FIG. 7 shows a sectional view of an embodiment of a lighting device 1a according to the invention differing from the lighting device of FIGS. 1-4 and 5, 6 by having an aperture 11 arranged between the lens 5 and the light-outcoupling surfaces 2c and 3c of the outcoupling bars 2b, 3b. The aperture 11 is configured to limit the light coupled from the outcoupling bars 2b, 3b into the lens 5 such that the light distribution emitted by the lighting device 1athat is that light distribution generated by the light sources 4 via the light-outcoupling surfaces 2c and 3c through the lens 5is limited downwards by a continuous straight bottom edge UK, preferably in the form of a horizontal line.

(19) In that instance, the aperture 11 has an opening 11a through which light is guided from the outcoupling bars 2b and 3b into the lens 5, wherein, when installed, an upper side of the opening 11a is limited by a horizontal edge (see FIG. 9). In the arrangement shown, the aperture is arranged between the light-outcoupling surfaces 2c and 3c and the lens 5 such that the solid angle illuminated from the outcoupling surfaces towards the lens 5 is restricted upwards, resulting in that the edge ray L3 described above is blocked by the aperture 11 (e.g., through absorption or reflection) and does not reach the downstream lens 5 in this example. Therefore, the area of the light-outcoupling surfaces 2c and 3c that can couple light into the lens 5 may be limited to a common solid angle. Depending on the geometric projecting properties, particularly the field curvature of the lens 5, the aperture 11 may need to be configured in a manner other than stated above in order to achieve a light distribution that is limited downwards by a continuous straight bottom edge, preferably in the form of a horizontal line.

(20) FIG. 7a shows a detailed view of FIG. 7, where the shape of the edge rays L2 and L3 may be recognised particularly well. FIG. 8 shows a view of the light distribution of the lighting device of FIG. 7, particularly of the light segments 6a of the first light-guide unit 2 and the light segments 6b of the second light-guide unit 3. The areas of the light segments 6a and 6b located below the bottom edge UK are blocked out by the aperture 11.

(21) FIG. 9 shows a front view of the aperture 11 of the lighting device 1a covering the outcoupling bars 2b and 3b outside of the opening area 11a. The aperture 11 may be implemented as an integral component of a lens support supporting the lens 5, for example, as an integrally injection-moulded part. The position of the aperture may be generally set freely along the optical axis OA and preferably be selected such that, due to the position of the edge 11b relative to the outcoupling bars 2b and 3b and their respective emission angle, the light distribution emitted by the lens 5 is limited downwards by a single continuous straight bottom edge UK, preferably in the form of a horizontal line.

(22) Upon review of this teaching, those skilled in the art will be able to obtain other embodiments of the invention not shown without involving an inventive step. Therefore, the invention shall not be limited to the embodiment shown. Also, individual aspects of the invention or the embodiment may be selected and combined with one another. The key element are the ideas the invention is based on that may be implemented in a variety of ways by those skilled in the art while still being maintained as such.