Headlights for vehicles

Abstract

The invention relates to a headlight for vehicles with at least one light source (1) for emitting light (4), with an optical unit comprising a projection lens (3) for deflecting the light (4) so ​​that a predetermined light distribution with a light / dark boundary is generated in a vehicle foreground, wherein the projection lens (3) has a Fresnel structure (15), wherein the projection lens (3) is designed as an axicon lens (3), wherein a Fresnel structure (15) is provided on an inner side (13) of the axicon lens (3).

Description

[0001] The invention relates to a headlight for vehicles with at least one light source for emitting light, with an optical unit containing a projection lens for deflecting the light, so that a predetermined light distribution with a light / dark boundary is generated in a vehicle foreground, wherein the projection lens has a Fresnel structure.

[0002] From DE 20 2016 100 463 U1, a headlight for vehicles is known which has a laser diode as its light source. To provide white light, which is deflected by means of a reflector according to a predetermined light distribution, a first lens, a second lens, and a phosphor unit are arranged in the main emission direction in front of the laser diode, wherein the phosphor unit converts the light emitted by the second lens into white light. A blue laser beam emitted by the laser diode is refracted in the first lens such that it exhibits a Gaussian pattern. By means of the second lens, the beam exhibiting the Gaussian pattern is converted into a beam with a rectangular beam pattern. For this purpose, the second lens is designed as an axicon lens.

[0003] From DE 10 2022 124 019 A1, a headlight for vehicles is known which has at least one light source and an optical unit for generating a predetermined light distribution, preferably for generating a low-beam distribution with a light / dark boundary. The optical unit can comprise several optical components, for example, a primary optic that pre-shapes the light emitted by the light source, and a secondary optic that shapes the light coming from the primary optic according to the predetermined low-beam distribution. The secondary optic is formed by a projection lens that has a Fresnel structure on one light-exit side. The Fresnel structure has, on the one hand, a plurality of functional edges that deflect the light to generate the predetermined low-beam distribution.On the other hand, the Fresnel structure exhibits numerous interference edges that deflect the light in such a way that they do not contribute to generating the desired low-beam distribution. A disadvantage of the known projection lens is its relatively large volume, resulting in significant material consumption.

[0004] The object of the present invention is therefore to further develop a headlight for vehicles with a projection lens in such a way that an effective collimation effect is achieved in a small volume.

[0005] To solve this problem, the invention has the features of claim 1.

[0006] The particular advantage of the invention lies in the fact that a predetermined collimation effect is achieved with a relatively small volume and minimal material expenditure for the projection lens. This results in a relatively lightweight spotlight. The fundamental concept of the invention is to ensure the refraction of light rays (white light rays) necessary for generating a predetermined light distribution by providing a Fresnel structure on the inner surface of the projection lens, which is designed as an axicon lens. The prevailing misconception among experts that an axicon lens is unsuitable as a projection lens for spotlights has been refuted. Since the axicon lens has a shape comparable to a martini glass with relatively thin walls, the material expenditure for the projection lens can be significantly reduced.

[0007] According to a further development of the invention, the axicon lens has a cladding wall tapering to a point, which has a Fresnel structure on its inner side and preferably a smooth surface on its outer side. The Fresnel structure serves to distribute the light as desired, while the preferably smooth outer surface of the cladding surface serves only to refract the light uniformly. Since the Fresnel structure is located on the inner side of the axicon lens, it is not visible to an observer from the outside. Only the outer side of the axicon lens is visible, so that the optical unit of the headlight has a homogeneous appearance.

[0008] According to a further development of the invention, the axicon lens is designed in a circular cone shape, in particular as a right circular cone, so that the axicon lens can be arranged symmetrically to a horizontal axis, which improves the appearance of the headlight.

[0009] According to a further development of the invention, the opening angle of the axicon lens lies in a range between 100° and 140°. The generatrices of the axicon lens thus run relatively steeply to an optical axis, so that the axicon lens has the shape of a traditional hat of an East Asian rice farmer.

[0010] According to a further development of the invention, the Fresnel structure has a plurality of ring-shaped useful edges that deflect the light for light distribution and a plurality of interference edges that do not deflect the light for light distribution. The angles of attack of the useful edges are arranged such that the light coming from the light source or from a primary optic and entering the axial lens is focused according to the specified requirements to achieve the light distribution, preferably a low-beam distribution.

[0011] According to a further development of the invention, the light source is designed as a number of LED light sources, which preferably emit white light. To align the light, the primary optics can be arranged between the light source and the projection lens.

[0012] An embodiment of the invention is explained in more detail below with reference to the drawings.

[0013] They show: Fig. 1 a schematic side view of a headlight according to the invention with a projection lens, Fig. 2 a rear view of the projection lens and Fig. 3 a section through the axicon lens along the section line III-III in Fig. 2.

[0014] A headlight for vehicles has a number of light sources 1 and an optical unit for generating a predetermined light distribution, in particular a low beam distribution, with a light / dark boundary.

[0015] The at least one light source 1 is designed as an LED light source that emits white light.

[0016] For example, several LED light sources 1 can be arranged in a matrix-like lighting field. The LED light sources 1 are arranged on a common circuit board.

[0017] The optical unit preferably comprises a primary optic 2 and a secondary optic 3. The primary optic 2 parallelizes and / or transforms the light 4 emitted by the at least one light source 1 so that the highest possible proportion of the light 4 emitted by the light source 1 strikes a light entrance side 5 of the secondary optic 3. The primary optic 2 is arranged between the light source 1 and the secondary optic 3.

[0018] In the present embodiment, the secondary optics 3 are formed by only a single projection lens, namely an axicon lens 3. The axicon lens 3 is designed such that it deflects the light 4 entering at the light entry side 5 in such a way that the light 4 exits at a light exit side 6 of the axicon lens 3 in such a way that a predetermined light distribution, for example the low beam distribution, with the light / dark boundary is generated in a vehicle area (not shown) in front of the vehicle.

[0019] The axicon lens 3 is hollow-conical with a mantle wall 7 extending between a tip 8 of the axicon lens 3 and an aperture edge 9 of the axicon lens 3. The aperture edge 9 of the axicon lens 3 lies in a base plane of the axicon lens 3, with the aperture edge 9 having the greatest distance r of the mantle wall 7 to an optical axis 10 of the axicon lens 3 passing through the tip 8 of the axicon lens 3.

[0020] The optical axis 10 of the axicon lens 3 is identical to an optical axis 10 of the primary optics 2 and thus forms the optical axis 10 of the optical unit. In the headlight's installation position in the vehicle, the optical axis 10 runs horizontally.

[0021] In the present embodiment, the axicon lens 3 is circular cone-shaped, in particular as a right circular cone. The opening edge 9 of the cladding wall 7 thus has the same distance r to the optical axis 10 in the circumferential direction.

[0022] The opening angle φ of the axicon lens 3 lies in a range of 100° to 140°, preferably 120°.

[0023] The tip 8 of the axicon lens 3 is located on a front side of the axicon lens 3 in the main emission direction H of the headlight. The aperture rim 9 of the axicon lens 3, or a base area 14 of the axicon lens 3 bounded by the aperture rim 9, is located perpendicular to the optical axis 10 and on a rear side of the axicon lens 3 in the main emission direction H. The aperture rim 9 is located on a side of the axicon lens 3 facing the light source 1.

[0024] An outer surface 11 of the mantle wall 7, facing away from the optical axis 10, preferably has a smooth surface and runs in a straight or linear plane in which the optical axis 10 is located. Opposite generatrix lines 12, 12' of the axicon lens 3 running in this plane have a length l that is less than the diameter d of the base 14 of the axicon lens 3, which is bounded by the aperture edge 9.

[0025] According to an alternative embodiment of the invention, which is not shown, the outer surface 11 of the shell wall 7 can also be provided with scattering optic elements.

[0026] In the present embodiment, the length of the generatrix 12, 12' of the axicon lens 3 corresponds to approximately 2 / 3 of the diameter d of the base 14.

[0027] An inner surface 13 of the mantle wall 7, facing the optical axis 10, is provided with a Fresnel structure 15. The Fresnel structure 15 has a plurality of annular useful flanks 16 that deflect the light 4 for light distribution and a plurality of interference flanks 17 that do not deflect the light 4 for light distribution. The useful flanks 16 and the interference flanks 17 are arranged alternately next to each other, preferably extending continuously from the tip 8 to the aperture edge 9 of the axicon lens 3.

[0028] The functional flanks 16 have an angle of attack α in the range between 0.1° and 5°. The angle of attack α is enclosed by the respective functional flank 16 and a plane E perpendicular to the optical axis 10.

[0029] The angle of attack α of the effective flanks 16 is calculated such that the light 4 entering the axicon lens 3 is refracted in such a way that, after exiting the outer surface 11 of the axicon lens 3, the light is generated in the area in front of the vehicle according to the specified light distribution. For this purpose, the effective flanks 1 have partly the same angle of attack α and partly different angles of attack α.

[0030] According to an alternative embodiment (not shown), the optical unit can consist solely of the secondary optics 3, wherein the secondary optics 3 consists solely of the axicon lens 3. An additional aperture for generating the light / dark boundary of the light distribution is not required if, in particular, the secondary optics 3 are designed such that an edge of the light source 1 is imaged onto the light / dark boundary.

[0031] A stop ring 18 is provided at the opening edge 9 of the axicon lens 3, by means of which the axicon lens 3 can be attached and / or fastened to a support unit (not shown). Fastening can be achieved, for example, by clamping the stop ring 18 from behind. Reference symbol list 1 light source 2 Primary optics 3 Secondary optics / Axicon lens 4 lights 5 Light entry side 6 Light exit side 7. Mantle wall 8 top 9 Opening edge 10 optical axis 11 Outside 12.12' mantle line 13 Inside 14 Base area 15 Fresnel structure 16 usable flanks 17 disturbance flanks 18 Stop ring r distance α Angle of attack Length H Main radiation direction Level E φ Opening angle d diameter

Claims

[1] Headlights for vehicles with at least one light source (1) for emitting light (4), with an optical unit comprising a projection lens (3) for deflecting the light (4) so ​​that a predetermined light distribution with a light / dark boundary is produced in a vehicle foreground, wherein the projection lens (3) has a Fresnel structure (15), characterized by , that the projection lens (3) is designed as an axicon lens (3), wherein the Fresnel structure (15) is provided on an inner side (13) of the axicon lens (3). [2] Headlights according to claim 1, characterized by , that the axicon lens (3) is designed in a hollow cone shape with a mantle wall (7) which has the Fresnel structure (15) on an inner side (13) facing the optical axis (10) of the optical unit and a smooth surface on the outer side (11) facing away from the optical axis (10) of the optical unit. [3] Headlights according to claim 1 or 2, characterized by, that the optical axis (10) of the axicon lens (3) passes through a tip (8) of the axicon lens (3). [4] Headlights according to any one of claims 1 to 3, characterized by , that the tip (8) of the axicon lens (3) is arranged on a front side of the axicon lens (3) in the main emission direction (H) of the headlight. [5] Headlights according to any one of claims 1 to 4, characterized by , that the axicon lens (3) is circular cone-shaped. [6] Headlights according to any one of claims 1 to 5, characterized by , that the axicon lens (3) is formed as a right circular cone. [7] Headlights according to any one of claims 1 to 6, characterized by , that the axicon lens (3) has an opening angle (φ) in the range of 100° to 140°, in particular 120°. [8] Headlights according to any one of claims 1 to 7, characterized by, that a generatrix (12, 12') running in an axial section of the axicon lens (3) has a length (I) that is smaller than a diameter (d) of a base surface (14) of the axicon lens (3), wherein an aperture edge (9) of the axicon lens (3) runs in the base surface (14) of the axicon lens (3). [9] Headlights according to any one of claims 1 to 8, characterized by , that the generatrix (12, 12') of the axicon lens (3) is 2 / 3 of the diameter (d) of the base (14). [10] Headlights according to any one of claims 1 to 9, characterized by , that the Fresnel structure (15) has a plurality of annular useful flanks (16) which deflect the light (4) for light distribution and a plurality of disturbance flanks (17) which do not deflect the light for light distribution, wherein the useful flanks (16) enclose an angle of inclination (α) to a plane (E) perpendicular to the optical axis (10) of the axicon lens (3), which lies in a range between 0.1° and 5°. [11] Headlights according to claim 10, characterized by , that the ring-shaped useful flanks (16) and the ring-shaped disturbance flanks (17) alternately run from the tip (8) to the opening edge (9) of the axicon lens (3). [12] Headlights according to any one of claims 1 to 11, characterized by , that a primary optic (2) is provided between the axicon lens (3) and the light source (1). [13] Headlights according to any one of claims 1 to 12, characterized by , that the light source (1) is designed as an LED light source.

Images