Projection lens for a motor vehicle headlight, as well as headlights with such a projection lens

Abstract

Projection lens (4) for a headlight of a motor vehicle, which is configured to convert an extended light distribution generated by a primary optic (3) of the headlight into a light distribution corresponding to the output light distribution of the headlight, wherein the projection lens (4) comprises a substrate (7) made of a transparent material having an input side (8) for the light emanating from the primary optic (3) of the headlight and an output side (9) opposite the input side (8), wherein a Fresnel structure is arranged on the substrate (7) having a plurality of mutually coaxial annular steps (10), each having a useful flank (11) and a disturbance flank (12), wherein the useful flank (11) is the region of the step (10) which is configured to allow light to pass through it, and wherein the disturbance flank (12) is the region of the step (10) which is not configured to allow light to pass through it.that light passes through it, and wherein at least one of the disturbance edges (12) is curved.

Description

[0001] The present invention relates to a projection lens for a headlight of a motor vehicle according to the preamble of claim 1 and to a headlight according to the preamble of claim 15.

[0002] A projection lens of the aforementioned type is known from DE 11 2013 007 443 B4. The projection lens described therein is designed to convert an extended light distribution generated by a primary optics of the headlight into a light distribution corresponding to the output light distribution of the headlight. The projection lens can comprise at least one substrate made of a transparent material having a Fresnel structure with a plurality of mutually coaxial annular steps.

[0003] Such Fresnel lenses reduce weight and thickness compared to traditional thick lenses typically used in projection modules for headlights. A special feature of Fresnel lenses is that the ring-shaped steps each have a useful flank and an interference flank, with the useful flank being the area of ​​the step designed to allow light to pass through it, and the interference flank being the area of ​​the step not designed to allow light to pass through it. The non-imaging interference flanks arranged between the refractive surfaces can lead to concentrated scattered light and thus sometimes to exceeding the glare limits of projection modules. The interference flanks can also create visible stray light rings, which can disrupt the homogeneity of the produced light image.

[0004] The problem underlying the present invention is to create a projection lens of the type mentioned above that reduces the occurrence of stray light and / or the occurrence of stray light rings and / or the intensity of the stray light that occurs. Furthermore, a headlight of the type mentioned above is to be created.

[0005] This is achieved according to the invention by a projection lens of the type mentioned at the outset having the characterizing features of claim 1 and by a headlight of the type mentioned at the outset having the characterizing features of claim 15. The subclaims relate to preferred embodiments of the invention.

[0006] According to claim 1, at least one of the interference flanks is curved. In particular, several or all of the interference flanks can be curved. A curvature of at least one, preferably several or all, interference flanks leads to a distribution of the luminous flux of the scattered light over a larger solid angle compared to a flat flank. This, on the one hand, can reduce the overall scattered light. On the other hand, the intensity of the scattered light spreading into individual solid angle ranges can be reduced. In particular, the occurrence of scattered light rings is avoided.

[0007] It can be provided that at least one or more or all of the interference edges are concavely curved. Alternatively, it can be provided that at least one or more or all of the interference edges are convexly curved. Alternatively, it can be provided that at least one or more or all of the interference edges are multiply curved, in particular that they are partially concave and partially convex.

[0008] It is possible that the shape of the curvature and / or the radius of curvature of several or all interference flanks are the same.

[0009] Alternatively, it is possible for the shape of the curvature and / or the radius of curvature of at least a first of the interference flanks to be different from the shape of the curvature and / or the radius of curvature of at least a second of the interference flanks. The curvature of each of the interference flanks can have a shape of curvature and / or a radius of curvature that differs from the shape of the curvature and / or the radius of curvature of the other interference flanks. For example, the inclinations of the main planes in which the respective curvature is arranged can also be different for different interference flanks.

[0010] It can be provided that the shape of the curvature and / or the radius of curvature of the interference flanks changes continuously from the inside to the outside at the different annular steps of the Fresnel structure.

[0011] Alternatively, it can be provided that the shape of the curvature and / or the radius of curvature of the interference flanks does not change continuously from the inside to the outside at the different annular steps of the Fresnel structure. For example, the shape of the curvature and / or the radius of curvature of adjacent interference flanks can differ more from each other than the shape of the curvature and / or the radius of curvature of interference flanks that are not adjacent to each other.

[0012] It is possible that the substrate on which the Fresnel structure is arranged is a plate-shaped non-curved substrate.

[0013] Alternatively, the substrate on which the Fresnel structure is arranged can be a curved substrate with a convex side and a concave side opposite the convex side. A curved substrate allows the thickness of the projection lens to be reduced across the board compared to a conventional plano-convex lens, while still maintaining the optical function. This results in a reduction in lens weight and thus in a reduction in processing time and manufacturing costs.

[0014] The Fresnel structure can be arranged on the input side of the substrate. Alternatively, the Fresnel structure can be arranged on the output side of the substrate.

[0015] According to claim 15, it is provided that the projection lens is a projection lens according to the invention.

[0016] The invention is explained in more detail below with reference to the accompanying drawings. In the drawings: Fig. 1 is a merely schematic side view of a headlight according to the invention; Fig. 2 shows a schematic detail of a first embodiment of a projection lens according to the invention; Fig. 3 shows a schematic detail of a second embodiment of a projection lens according to the invention; Fig. 4 shows a schematic detail of a third embodiment of a projection lens according to the invention; Fig. 5 shows a schematic detail of a fourth embodiment of a projection lens according to the invention; Fig. 6 shows a schematic detail of a fifth embodiment of a projection lens according to the invention; Fig. 7 shows a schematic detail of a sixth embodiment of a projection lens according to the invention; Fig. 8 schematic beam paths through the projection lens according to Fig. 7, where, for clarity, the beam paths of a projection lens with flat interference flanks are also indicated.

[0017] In the figures, identical and functionally identical parts are provided with the same reference numerals.

[0018] Fig. Figure 1 shows, merely schematically, an embodiment of a headlight according to the invention. The light 2 emanating from at least one light source 1 of the headlight is shaped by a primary optic 3, shown only schematically, such that an extended light distribution is created behind the primary optic 3. One or more apertures (not shown) can be provided to create the desired shape of the light distribution.

[0019] The headlight further comprises a projection lens 4. This projection lens 4 is in particular the projection lens according to the invention, which is described in more detail below. Fig. 1, this projection lens 4 is shown only schematically. The projection lens 4 is designed such that it converts the extended light distribution generated by the primary optics 3 into a light distribution corresponding to the output light distribution of the headlight. This is shown in Fig. 1 by the beam paths of the light 5 passing through the projection lens 4, which are schematically shown by solid lines.

[0020] In Fig. 1 also shows schematically illustrated beam paths of the scattered light 6 emanating from the projection lens 4, indicated by dashed lines. This scattered light 6 can originate, in particular, from the interference edges of the projection lens 4, which will be described in more detail below.

[0021] In the Fig. 2 to Fig. The projection lens 4 shown in detail in Figure 8 is a plastic lens. The projection lens 4 comprises a substrate 7, which has an input side 8 and an output side 9 opposite the input side 8 for the light emanating from the primary optics 3 (see, for example, Fig. 1 and Fig. 2).

[0022] In the embodiments according to the Fig. 2, Fig. 3, Fig. 6 and Fig. 7, the substrate 7 is formed as a plate-shaped, non-curved substrate 7 made of a transparent material. In the embodiments according to the Fig. 4 and Fig. 5, the substrate 7 is formed as a curved substrate 7 made of a transparent material, which has a convex side 13 and a concave side 14 opposite the convex side 13. The curved substrate 7 has, in particular, the shape of a partially hollow sphere or a part of a hollow ellipsoid of revolution, wherein the convex side 13 corresponds to the outside of the partially hollow sphere or the part of the hollow ellipsoid of revolution, and wherein the concave side 14 corresponds to the inside of the partially hollow sphere or the part of the hollow ellipsoid of revolution.

[0023] The concave side 14 can be arranged on the coupling side 8 and the convex side 13 on the coupling side 9 (see Fig. 4). Alternatively, the convex side 13 can be arranged on the input side 8 and the concave side 14 on the output side 9 (see Fig. 5).

[0024] The projection lens 4 further comprises a Fresnel structure having a plurality of annular steps 10, the axial direction of which coincides in particular with the optical axis, so that the annular steps 10 are coaxial to each other and coaxial to the optical axis 3 of the projection lens 4. The Fresnel structure can be arranged on the coupling side 8 (see Fig. 2, Fig. 4, Fig. 6 and Fig. 7) or on the output side 9 (see Fig. 3 and Fig. 5).

[0025] The annular steps 10 each have a useful flank 11 and a disturbing flank 12 (see for example Fig. 2). The useful edge 11 is the area of ​​stage 10 through which light is arranged, whereas the interference edge 12 is the area of ​​stage 10 through which light is not arranged.

[0026] In the illustrated embodiments, the useful flanks 11 are flat, whereas at least several of the interference flanks 12 are curved. The interference flanks 12 can be concavely curved (see Fig. 7). Alternatively, the interference edges 12 can be convexly curved (see Fig. 6). It is also possible that the interference edges 12 are curved multiple times, in particular they are curved concavely in sections and convexly in sections (see Fig. 2 to Fig. 5).

[0027] The shape of the curvature and / or the radius of curvature of the interference flanks 12 of different annular steps 10 of the illustrated embodiments differ from one another. Alternatively, it is entirely possible for the shape of the curvature and / or the radius of curvature of several or all interference flanks 12 to be the same.

[0028] Furthermore, for example, in the embodiment according to Fig. 6 the inclinations of the main planes 15a, 15b, 15c (see the dotted lines in Fig. 6), in which the respective curvature of the interference edges 12a, 12b, 12c is arranged, is different for different interference edges 12a, 12b, 12c.

[0029] It can be provided that the shape of the curvature and / or the radius of curvature of the interference flanks 12 continuously change from the inside to the outside at the different annular steps 10 of the Fresnel structure. Alternatively, it can also be provided that the shape of the curvature and / or the radius of curvature of the interference flanks 12 do not continuously change from the inside to the outside at the different annular steps 10 of the Fresnel structure.

[0030] Fig.Figure 8 illustrates the effect of curved interference edges 12 on the propagation of the scattered light 6 generated by the interference edges 12. For this purpose, the dashed lines indicate the interference edges 12' according to the prior art, which are flat. Light 2' impinging on these interference edges 12' (see the dashed arrows) is deflected by the interference edges 12' as scattered light 6', all in the same direction.

[0031] In contrast, light 2 incident on different sections 16a, 16b of the curved interference edges 12 (see the solid arrows) is deflected by the interference edges 12 as scattered light 6a, 6b in different directions. As a result, the scattered light 6 is distributed over a larger solid angle, so that the intensity of the scattered light 6 spreading into individual solid angle ranges is reduced. List of reference symbols 1 light source 2, 2' light emanating from the light source 3 Primary optics 4 Projection lens 5 Light passing through projection lens 6, 6a, 6b, 6' Scattered light 7 Substrat 8 Coupling side of the substrate 9 Output side of the substrate 10 ring-shaped step of the Fresnel structure 11 Effective flank of the annular step 12, 12a, 12b, 12c, 12' Interference flank of the annular step 13 convex side of the curved substrate 14 concave side of the curved substrate 15a, 15b, 15c Main plane in which the curvature of the interference flank is arranged 16a, 16b Section of the interference flank QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] DE 11 2013 007 443 B4

[0002]

Claims

[1] A projection lens (4) for a headlight of a motor vehicle, which is designed to convert an extended light distribution generated by a primary optics (3) of the headlight into a light distribution corresponding to the output light distribution of the headlight, wherein the projection lens (4) comprises a substrate (7) made of a transparent material, which has an input side (8) for the light emanating from the primary optics (3) of the headlight and an output side (9) opposite the input side (8), wherein a Fresnel structure is arranged on the substrate (7), which has a plurality of mutually coaxial annular steps (10), each having a useful flank (11) and an interference flank (12), wherein the useful flank (11) is that region of the step (10) which is designed to allow light to pass through it, and wherein the interference flank (12) is that region of the step (10) which is not designed tothat light passes through it, characterized by that at least one of the interference edges (12) is curved. [2] Projection lens (4) according to claim 1, characterized by that several or all of the interference edges (12) are curved. [3] Projection lens (4) according to one of claims 1 or 2, characterized by that at least one or more or all of the interference flanks (12) are concavely curved. [4] Projection lens (4) according to one of claims 1 or 2, characterized by that at least one or more or all of the interference edges (12) are convexly curved. [5] Projection lens (4) according to one of claims 1 or 2, characterized by that at least one or more or all of the interference flanks (12) are multiply curved, in particular are partially concave and partially convex. [6] Projection lens (4) according to one of claims 1 to 5, characterized bythat the shape of the curvature and / or the radius of curvature of several or all interference flanks (12) are the same. [7] Projection lens (4) according to one of claims 1 to 5, characterized by that the shape of the curvature and / or the radius of curvature of at least a first of the interference flanks (12) is different from the shape of the curvature and / or the radius of curvature of at least a second of the interference flanks (12). [8] Projection lens (4) according to claim 7, characterized by that the curvature of each of the interference flanks (12) has a shape of curvature and / or a radius of curvature which differs from the shape of the curvature and / or the radius of curvature of the other interference flanks (12). [9] Projection lens (4) according to one of claims 7 or 8, characterized by that the shape of the curvature and / or the radius of curvature of the interference flanks (12) changes continuously from the inside to the outside at the different annular steps (10) of the Fresnel structure. [10] Projection lens (4) according to one of claims 7 or 8, characterized by that the shape of the curvature and / or the radius of curvature of the interference flanks (12) does not change continuously from the inside to the outside in the different annular steps (10) of the Fresnel structure. [11] Projection lens (4) according to one of claims 1 to 10, characterized by that the substrate (7) on which the Fresnel structure is arranged is a plate-shaped non-curved substrate (7). [12] Projection lens (4) according to one of claims 1 to 10, characterized by that the substrate (7) on which the Fresnel structure is arranged is a curved substrate (7) having a convex side (13) and a concave side (14) opposite the convex side (13). [13] Projection lens (4) according to one of claims 1 to 12, characterized by that the Fresnel structure is arranged on the coupling side (8) of the substrate (7). [14] Projection lens (4) according to one of claims 1 to 12, characterized by that the Fresnel structure is arranged on the output side (9) of the substrate (7). [15] Headlight of a motor vehicle, comprising - at least one light source (1), - a primary optic (3) which is designed to shape the light (2) emanating from the at least one light source (1) in such a way that an extended light distribution is produced, - a projection lens (4) designed to convert the extended light distribution generated by the primary optics (3) into a light distribution corresponding to the output light distribution of the headlight, characterized by that the projection lens (4) is a projection lens (4) according to one of claims 1 to 14.

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