Projection lens for headlight of motor vehicle and headlight having such a projection lens

Abstract

The invention relates to a projection lens (4) for a headlight of a motor vehicle, which projection lens is provided for converting an expanded light distribution generated by a primary optic (3) of the headlight into a light distribution corresponding to an output light distribution of the headlight, the projection lens (4) comprising a substrate (7) made of a transparent material, the invention relates to a headlamp (1) comprising a substrate (7) having a coupling-in side (8) for light emitted from a primary optical element (3) of the headlamp and a coupling-out side (9) opposite the coupling-in side (8), on which substrate (7) a Fresnel structure is arranged, which has a plurality of annular steps (10) which are coaxial to one another and each have a working side (11) and an interference side (12), the working side (11) is a region of the step (10) provided for the passage of light, the interference side (12) is a region of the step (10) not provided for the passage of light, and at least one of the interference sides (12) is curved.

Description

Technical Field

[0001] The 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 . Background Art

[0002] A projection lens of the above-mentioned type is known from DE 11 2013 007 443 B4. The projection lens described therein is provided for converting an extended light distribution generated by a primary optical system of a headlamp into a light distribution corresponding to an output light distribution of the headlamp. The projection lens can include at least one substrate made of a transparent material, which has a Fresnel structure having a plurality of annular steps coaxial with one another.

[0003] Compared to conventional thick lenses, which are usually used for headlight projection modules, such Fresnel lenses have reduced weight and thickness. A feature of the Fresnel lens is that the annular steps each have a working side and a disturbing side, the working side being the region of the step that is provided for light to pass through, and the disturbing side being the region of the step that is not provided for light to pass through. The non-imaging disturbing side, which is arranged between the refractive working side, can lead to concentrated scattered light and thus sometimes to exceeding the glare limit of the projection module. The disturbing side can also generate visible scattered light rings, which can disturb the homogeneity of the generated light image. Summary of the invention

[0004] The object on which the invention is based is to provide a projection lens of the type mentioned at the outset which reduces the occurrence of scattered light and / or the occurrence of scattered light rings and / or the intensity of the scattered light that occurs. In addition, a headlamp of the type mentioned at the outset should be provided.

[0005] This is achieved according to the invention by a projection lens of the type mentioned in the introduction having the characterizing features of claim 1 and by a headlamp of the type mentioned in the introduction having the characterizing features of claim 15. The dependent claims relate to preferred embodiments of the invention.

[0006] According to claim 1, at least one of the interfering side surfaces is configured to be curved. In particular, a plurality of or all of the interfering side surfaces can be configured to be curved. The curvature of at least one, preferably a plurality of or all of the interfering side surfaces distributes the luminous flux of the scattered light in a larger spatial angle than that of the flat side surfaces. Thus, on the one hand, the scattered light can be reduced overall. On the other hand, the intensity of the scattered light propagating in each spatial angle region can be reduced. In particular, the appearance of scattered light rings can be avoided.

[0007] It can be provided that at least one or more or all of the interfering flanks are concavely curved. Alternatively, it can be provided that at least one or more or all of the interfering flanks are convexly curved. Alternatively, it can be provided that at least one or more or all of the interfering flanks are multiply curved, in particular partial sections are concavely curved and partial sections are convexly curved.

[0008] It is possible for the curvature and / or the radius of curvature of several or all interfering side surfaces to be identical.

[0009] Alternatively, there is the possibility that the curvature and / or the radius of curvature of at least one first of the interfering side surfaces are different from the curvature and / or the radius of curvature of at least one second of the interfering side surfaces. Here, the curvature of each interfering side surface can have a curvature and / or a radius of curvature that is different from the curvature and / or the radius of curvature of the other interfering side surfaces. For example, for different interfering side surfaces, the slopes of the main planes in which the corresponding curvatures are arranged can also be different from each other.

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

[0011] Alternatively, it can be provided that the curvature and / or the radius of curvature of the interfering flanks in different annular steps of the Fresnel structure vary discontinuously from the inside to the outside. For example, the curvature and / or the radius of curvature of adjacent interfering flanks can differ to a greater extent than the curvature and / or the radius of curvature of interfering flanks that are not adjacent to each other.

[0012] There is the possibility that the substrate on which the Fresnel structure is arranged is a plate-shaped, non-curved substrate.

[0013] Alternatively, there is the possibility that the substrate on which the Fresnel structure is arranged is a curved substrate having a convex side and a concave side opposite the convex side. By curving the substrate, the thickness of the projection lens can be reduced substantially compared to conventional planar convex lenses, but the optical function is nevertheless maintained. This reduces the lens weight and thus reduces the process time and the manufacturing costs.

[0014] It can be provided that the Fresnel structure is arranged on the coupling-in side of the substrate. Alternatively, it can be provided that the Fresnel structure is arranged on the coupling-out side of the substrate.

[0015] According to claim 15, the projection lens is a projection lens according to the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The present invention is described in detail below with the help of the accompanying drawings. The accompanying drawings are as follows:

[0017] Figure 1 A purely schematic side view of a headlamp according to the invention is shown;

[0018] Figure 2 shows schematic details of a first embodiment of a projection lens according to the invention;

[0019] Figure 3 shows schematic details of a second embodiment of a projection lens according to the invention;

[0020] Figure 4 shows schematic details of a third embodiment of a projection lens according to the invention;

[0021] Figure 5 shows schematic details of a fourth embodiment of a projection lens according to the invention;

[0022] Figure 6 shows schematic details of a fifth embodiment of a projection lens according to the invention;

[0023] Figure 7 shows schematic details of a sixth embodiment of a projection lens according to the invention;

[0024] Figure 8 Shown through the Figure 7 Schematic light path of a projection lens, for the sake of illustration, the light path of a projection lens with a planar interfering side surface is also shown. DETAILED DESCRIPTION

[0025] In the figures, identical and functionally identical parts are provided with the same reference symbols.

[0026] Figure 1 Only one embodiment of the headlamp according to the invention is shown schematically. The light 2 emitted by at least one light source 1 of the headlamp is shaped by a primary optical system 3, which is shown schematically, so that an extended light distribution is generated behind the primary optical system 3. In order to generate the desired light distribution shape, one or more sunshades (not shown) can be provided.

[0027] Furthermore, the headlamp comprises a projection lens 4. The projection lens 4 is in particular a projection lens according to the invention which will be described in more detail below. Figure 1 The projection lens 4 is only schematically shown in FIG. The projection lens 4 is designed so that it transforms the expanded light distribution generated by the primary optical device 3 into a light distribution corresponding to the output light distribution of the headlight. Figure 1 This is represented by the light path of the light 5 which passes through the projection lens 4 and is schematically shown as a solid line.

[0028] In addition, Figure 1 , the beam path of scattered light 6 emitted from the projection lens 4 is schematically shown by dashed lines. The scattered light 6 can be emitted, in particular, from interfering side surfaces of the projection lens 4, which will be described in more detail below.

[0029] exist Figures 2 to 8 The projection lens 4 shown in detail in FIG. 4 is a lens made of plastic. The projection lens 4 comprises a substrate 7 having an incoupling side 8 for the light emitted from the primary optical device 3 and an outcoupling side 9 opposite the incoupling side 8 (see, for example, Figure 1 and Figure 2 ).

[0030] In accordance with Figure 2 , Figure 3 , Figure 6 and Figure 7 In the embodiment of the present invention, the substrate 7 is configured as a plate-shaped non-bent substrate 7 made of a transparent material. Figure 4 and Figure 5 In the embodiment of the present invention, the substrate 7 is configured 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 partial hollow sphere or a partial hollow ellipsoid, wherein the convex side 13 corresponds to the outer side of the partial hollow sphere or the partial hollow ellipsoid and the concave side 14 corresponds to the inner side of the partial hollow sphere or the partial hollow ellipsoid.

[0031] In this case, the concave side 14 can be arranged on the coupling-in side 8 and the convex side 13 can be arranged on the coupling-out side 9 (see Figure 4 Alternatively, the convex side 13 can be arranged on the coupling-in side 8 and the concave side 14 can be arranged on the coupling-out side 9 (see Figure 5 ).

[0032] The projection lens 4 further comprises a Fresnel structure having a plurality of annular steps 10, the axial direction of which in particular coincides with the optical axis, so that the annular steps 10 are coaxial with one another and with the optical axis 3 of the projection lens 4. The Fresnel structure can be arranged on the coupling-in side 8 (see Figure 2 , Figure 4 , Figure 6 and Figure 7 ) or arranged on the outcoupling side 9 (see Figure 3 and Figure 5 ).

[0033] The annular step 10 has a working side surface 11 and an interfering side surface 12 (see for example Figure 2 ). In this case, the working side 11 is a region of the step 10 provided for light to pass through, while the interfering side 12 is a region of the step 10 not provided for light to pass through.

[0034] In the embodiment shown, the working side 11 is configured as a plane, and at least a plurality of the interfering side surfaces 12 are configured as curved. The interfering side surfaces 12 may be concavely curved (see Figure 7 ). Alternatively, the interfering side surface 12 may be convexly curved (see Figure 6 ). It is also possible that the interfering side surface 12 is multiply curved, in particular that some sections are concavely curved and some sections are convexly curved (see Figures 2 to 5 ).

[0035] The curvature and / or curvature radius of the disruptive flanks 12 of the various annular steps 10 of the illustrated embodiment are different from one another. Alternatively, it is entirely possible that the curvature and / or curvature radius of a plurality or all disruptive flanks 12 are the same.

[0036] In addition, for example, according to Figure 6 In the embodiment, for different interfering sides 12a, 12b, 12c, the main planes 15a, 15b, 15c (see Figure 6 The slopes of the dot-dash lines in FIG. 1 are different from each other, and the corresponding curved portions of the interfering side surfaces 12a, 12b, 12c are arranged in the main plane.

[0037] It can be provided that the curvature and / or the radius of curvature of the interfering side surface 12 change continuously from the inside to the outside in different annular steps 10 of the Fresnel structure. Alternatively, it can also be provided that the curvature and / or the radius of curvature of the interfering side surface 12 change discontinuously from the inside to the outside in different annular steps 10 of the Fresnel structure.

[0038] Figure 8 The effect of the curved interference side surface 12 on the propagation of the scattered light 6 generated by the interference side surface 12 is explained. For this purpose, the interference side surface 12', which is designed as a plane according to the prior art, is indicated by dashed lines. The light 2' incident on these interference side surfaces 12' (see dashed arrows) is deflected by the interference side surfaces 12' as scattered light 6' in the same direction.

[0039] In contrast, light 2 incident on different sections 16a, 16b of the curved interfering side surface 12 (see solid arrows) is deflected by the interfering side surface 12 as scattered light 6a, 6b in different directions from each other. As a result, the scattered light 6 is distributed over a larger spatial angle, so that the intensity of the scattered light 6 propagating into each spatial angle region is reduced. Reference numerals list

[0040] 1 Light Source

[0041] 2.2'Light emitted by the light source

[0042] 3 Primary Optics

[0043] 4 Projection lens

[0044] 5Light passing through the projection lens

[0045] 6, 6a, 6b, 6' Scattered light

[0046] 7 base

[0047] 8Incoupling side of substrate

[0048] 9 outcoupling side of substrate

[0049] 10Fresnel structure circular steps

[0050] 11 Working side of the circular step

[0051] 12, 12a, 12b, 12c, 12d' Interference side of the annular step

[0052] 13. Bend the convex side of the base

[0053] 14Bend the concave side of the base

[0054] 15a, 15b, 15c are the main planes in which the curved portion of the interfering side is arranged

[0055] 16a, 16b Interference side sections

Claims

1. A projection lens (4) for a headlight of a motor vehicle, the projection lens being arranged to convert an extended light distribution generated by a primary optical device (3) of the headlight into a light distribution corresponding to an output light distribution of the headlight, the projection lens (4) comprising a substrate (7) made of a transparent material, the substrate having an incoupling side (8) for light emitted from the primary optical device (3) of the headlight and an outcoupling side (9) opposite the incoupling side (8), a Fresnel structure being arranged on the substrate (7), the Fresnel structure having a plurality of mutually coaxial annular steps (10), the annular steps each having a working side (11) and an interfering side (12), the working side (11) being a region of the step (10) arranged for light to pass through, and the interfering side (12) being a region of the step (10) not arranged for light to pass through, characterized in that At least one of the interfering flanks (12) is designed to be curved.

2. The projection lens (4) according to claim 1, characterized in that A plurality of or all of the interfering flanks (12) are designed to be curved.

3. The projection lens (4) according to claim 1 or 2, characterized in that: At least one or more or all of the interfering side surfaces (12) are concavely curved.

4. The projection lens (4) according to claim 1 or 2, characterized in that: At least one or more or all of the interfering side surfaces (12) are convexly curved.

5. The projection lens (4) according to claim 1 or 2, characterized in that: At least one or more or all of the interfering flanks (12) are multiply curved, in particular, some sections are concavely curved and some sections are convexly curved.

6. The projection lens (4) according to any one of claims 1 to 5, characterized in that The curvature shape and / or the radius of curvature of a plurality or all of the interfering side surfaces (12) are the same.

7. The projection lens (4) according to any one of claims 1 to 5, characterized in that The curvature shape and / or the radius of curvature of at least one first interfering side surface of the interfering side surfaces (12) are different from the curvature shape and / or the radius of curvature of at least one second interfering side surface of the interfering side surfaces (12).

8. The projection lens (4) according to claim 7, characterized in that The curved portion of each interfering side surface (12) has a curved shape and / or a curvature radius that is different from the curved shapes and / or curvature radii of other interfering side surfaces (12).

9. The projection lens (4) according to claim 7 or 8, characterized in that In different annular steps (10) of the Fresnel structure, the curvature shape and / or the radius of curvature of the interfering side surface (12) changes continuously from the inside to the outside.

10. The projection lens (4) according to claim 7 or 8, characterized in that In different annular steps (10) of the Fresnel structure, the curvature shape and / or the radius of curvature of the interfering side surface (12) changes discontinuously from inside to outside.

11. The projection lens (4) according to any one of claims 1 to 10, characterized in that The substrate (7) on which the Fresnel structure is arranged is a plate-shaped non-curved substrate (7).

12. The projection lens (4) according to any one of claims 1 to 10, characterized in 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 to the convex side (13).

13. The projection lens (4) according to any one of claims 1 to 12, characterized in that The Fresnel structure is arranged on the coupling-in side (8) of the substrate (7).

14. The projection lens (4) according to any one of claims 1 to 12, characterized in that The Fresnel structure is arranged on the outcoupling side (9) of the substrate (7).

15. A headlamp for a motor vehicle, the headlamp comprising: - at least one light source (1), - a primary optical system (3) which is provided for shaping the light (2) emitted by the at least one light source (1) in such a way that an extended light distribution is produced, - a projection lens (4) which is provided for converting the expanded light distribution generated by the primary optical system (3) into a light distribution corresponding to the output light distribution of the headlight, Characterized in that the projection lens (4) is the projection lens (4) according to any one of Claims 1 to 14.

Images