Lighting device for vehicles

Abstract

A lighting device for vehicles with a semiconductor-based light source and an optical unit having an imaging device for producing a predetermined light distribution and having an optical element arranged between the semiconductor-based light source and the imaging device. The optical element has a back side facing the semiconductor-based light source and has a front side facing the imaging device. The optical element is formed as a color correction element which has a color correction-free partial surface area through which a firstly emitted partial light beam of the semiconductor-based light source passes and has a color correction-affected partial surface area through which the secondly emitted partial light beam of the semiconductor-based light source passes in a border angle area.

Claims

1. A lighting device for vehicles comprising: a semiconductor-based light source; an optical unit having an imaging device and a color correction element, said imaging device for producing a predetermined light distribution, and said color correction element arranged between the semiconductor-based light source and the imaging device, wherein the color correction element has a back side facing the semiconductor-based light source and has a front side facing the imaging device, wherein the front side of the color correction element consists of a transparent color correction-free partial surface area through which a firstly emitted partial light beam of the semiconductor-based light source passes, and a color correction-affected partial surface area through which a secondly emitted partial light beam of the semiconductor-based light source passes in a border angle area, and wherein the color correction-affected partial surface is less transparent than the color correction-free partial surface.

2. The lighting device according to claim 1, wherein the color correction-affected partial surface area of the color correction element is designed in such a way that the secondly emitted partial light beam emerges with a neutral white light color from the color correction element.

3. The lighting device according to claim 1, wherein the color correction-affected partial surface area of the color correction element is arranged both on the back side as well as on the front side of the color correction element.

4. The lighting device according to claim 1 wherein the color correction-affected partial surface area extends to the back side of the color correction element in an upper section and in a lower section, between which extends a horizontal strip of the color correction-free partial surface area, and that the semiconductor-based light source is arranged horizontally offset to the horizontal strip.

5. The lighting device according to claim 1 wherein on the front side of the color correction element, the color correction-affected partial surface area extends in a lower section and the color correction-free partial surface area extends in an upper section, wherein an upper edge of the color correction-affected partial surface area runs offset vertically downwards to an upper edge of the lower section of the color correction-free partial surface area on the back side.

6. The lighting device according to claim 1 wherein the color correction element is plate-shaped with a depressed retaining bracket for attachment to a carrier of the semiconductor-based light source.

7. The lighting device according to claim 1 wherein the color correction element is arranged near the semiconductor-based light source.

8. The lighting device according to claim 1 wherein the color correction-affected partial surface area of the color correction element is formed by roughening the color correction-affected partial surface area.

9. The lighting device according to claim 1 wherein the color correction-affected partial surface area has a roughness in the μm range.

10. The lighting device according to claim 1 wherein the color correction element consists of a transparent plastic material and in that the color correction element has a wall thickness in the range from 1 mm to 5 mm.

11. A lighting device for vehicles comprising: a semiconductor-based light source; an optical unit having an imaging device and a color correction element, said imaging device for producing a predetermined light distribution, and said color correction element arranged between the semiconductor-based light source and the imaging device, wherein the color correction element has a back side facing the semiconductor-based light source and has a front side facing the imaging device, wherein the color correction element includes a transparent color correction-free partial surface area through which a firstly emitted partial light beam of the semiconductor-based light source passes, and a color correction-affected partial surface area through which a secondly emitted partial light beam of the semiconductor-based light source passes in a border angle area, wherein the color correction-free partial surface and the color correction-affected partial surface each include an outer edge and inner edge, wherein the inner edges of the color correction-free partial surface and the color correction-affected partial surface immediately abut one another, and wherein the color correction-affected partial surface is less transparent than the color correction-free partial surface.

12. A lighting device for vehicles comprising: a semiconductor-based light source; an optical unit having an imaging device and a color correction element, said imaging device for producing a predetermined light distribution, and said color correction element arranged between the semiconductor-based light source and the imaging device, wherein the color correction element has a back side facing the semiconductor-based light source and has a front side facing the imaging device, wherein the front side of the color correction element and the back side of the correction element each include a transparent color correction-free partial surface area through which a firstly emitted partial light beam of the semiconductor-based light source passes, and a color correction-affected partial surface area through which a secondly emitted partial light beam of the semiconductor-based light source passes in a border angle area, and wherein the color correction-affected partial surface is less transparent than the color correction-free partial surface.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Reference is now made more particularly to the drawings, which illustrate the best presently known mode of carrying out the invention and wherein similar reference characters indicate the same parts throughout the views.

(2) FIG. 1 is a vertical section of a lighting device,

(3) FIG. 2 is a vertical section of the lighting device with marked light rays,

(4) FIG. 3 is a front perspective view of a color correction element of the lighting device,

(5) FIG. 4 is a rear perspective view of the color correction element,

(6) FIG. 5 is a rear view of the color correction element and

(7) FIG. 6 is a front view of the color correction element.

DETAILED DESCRIPTION OF THE DRAWINGS

(8) An inventive lighting device 1 for generating a predetermined light distribution, for example, low beam distribution, may be used as a headlight. The lighting device 1 comprises essentially a semiconductor-based light source 2 and an optical unit 3 arranged in the main direction of the beam H before the same.

(9) The optical unit 3 consists firstly of an imaging device 4, by means of which light emitted from light source 2 corresponding to the predetermined light distribution is deflected, for example with a low beam distribution, high beam distribution or similar. The imaging device 4 is formed as a lens having a planar light entrance surface 5 as well as an aspherical light-emitting surface 6. The planar light entry surface 5 is arranged perpendicular to an optical axis 7 of the lens 4 and the light source 2. The aspherical light exit surface 6 is arranged in the main direction of the beam H in front of the planar light entry surface 5.

(10) The semiconductor-based light source 2 is preferably formed as an LED light source that can consist of a 1-chip LED light source or distributed as a matrix on a multi-chip LED light source. The LED light source 2 is arranged on a carrier 8.

(11) For the other, the optical unit 3 has a color correction element 9 that is arranged between the light source 2 and the lens 4. By means of the color correction element 9, an undesirable color fringe is prevented in the light distribution of the lighting device. The color correction element 9 is plate-shaped and is located near the light source 2. The color correction element has both, on the one hand, back side 10 facing the light source 2 as well as front side 11 facing the lens 4, and on the other hand, a color correction-free partial surface area 12 and a color correction-affected area 13.

(12) As is better seen from FIGS. 3 to 6, the color correction-affected partial surface area 13 extends on the back side in an upper section 14 and in a lower section 15, whereby the color correction-free partial surface area 12 extends as a horizontal strip between the sections 14 and 15. As is apparent from FIGS. 1 and 2, the semiconductor-based light

(13) source 2 is arranged displaced horizontally to the horizontal strip 16. The horizontal strip 16 has a width b which is equal to or greater than a vertical dimension of the light source 2.

(14) Further, the color correction element 9 has the color correction-free partial surface area 12 on the front side 11 in an upper section 17 and the color correction-affected partial surface area 13 in a lower section 18. An upper edge of the lower section 18 is arranged vertically downwardly displaced to an upper edge 20 of the lower section 15 arranged on the back side 10. This offset can, for example, amount to 0.5 mm.

(15) The color correction element 9 is manufactured from a transparent, preferably glass-clear and colorless plastic material. The color correction-free partial surface area 12 is thus designed to be transparent and to let the light through with relatively low light loss.

(16) The color correction element 9 may have a wall thickness d in a range from 1 mm to 5 mm, preferably 1 mm to 1.5 mm.

(17) The color correction-affected partial surface area 13 has been manufactured through surface treatment. The relevant sections 14, 15 and 18 are formed by roughening the surface of the color correction element 9. The roughness of these sections may be in a μm range.

(18) The color correction element 9 is thus arranged to the light source 2 so that a relatively large first partial light beam L1 passes through the color correction-free partial surface area 12 via the refraction on the back side 10 and on the front side 11 thereof, without substantially reducing the luminous flux.

(19) A second partial light beam L2 passes through the color correction-affected partial surface area 13, which essentially consists of emitted light beams of the light source 2 in a border angle area. The light beams of the second partial beam L2 are thus emitted at a relatively large opening angle compared to the first partial light beam L1, as can be seen in particular from FIG. 2.

(20) The second partial light beam L2 is already mixed within the color correction element 9 due to the scattering surface structure of the color correction element 9 in the color correction-affected partial surface area 13 so that a color correction occurs in the boundary area of light beams emitted from the light source 2. The second partial light beam thus also exits from the color correction element 9, like the first partial light beam L2, and then itself enters at the planar light input surface 5 of the lens 4.

(21) According to an alternative embodiment not shown, the color correction-affected partial surface area 13 may also be arranged only on the back side 10 or on the front side 11 of the color correction element 9. To achieve the equal mixing of the second partial light beam L2, the roughness here must be larger compared to the embodiment described above.

(22) The color correction element 9 is constructed as plate-shaped and has depressed retaining brackets 21 on opposite sides, each having a bore 22 for fastening the color correction element 9 to the carrier 8 of the LED light source 2. Preferably, the color correction element 9 is connected with the constructed carrier 8 as a printed circuit board by screwing or by riveting.

(23) As can be seen from FIGS. 1 and 2, the color correction element 9 is arranged in a small distance to the LED light source 2. This distance is dependent on the development of heat of the LED light source 2. Preferably, the color correction element 9 is arranged close to the LED light source 2 so that no impairment of the color correction element 9 occurs due to thermal stress.

REFERENCE NUMBER LIST

(24) 1 Lighting device 2 Light source 3 Optical unit 4 Imaging device 5 Light entry surface 6 Light-emitting surface 7 Optical axis 8 Carrier 9 Color correction element 10 Rear side 11 Front side 12 Color correction-free partial surface area 13 Color correction-affected partial surface area 14 Upper section 15 Lower section 16 Horizontal strip 17 Upper section 18 Lower section 19 Upper edge 20 Lower edge L1 First partial light beam L2 Second partial light beam H Main direction of beam d Wall thickness b Width