LIGHT MODULE FOR A MOTOR VEHICLE HEADLIGHT

Description

[0001] The invention relates to a light module for a motor vehicle headlight for generating an overall light distribution.

[0002] A light module of the type mentioned above is known, for example, from DE 10 2018 222 333 A1. The light module comprises an LED array and a two-part lens optic. The LED array forms an active black and white display with high luminance. Each LED corresponds to a pixel of the display and can be controlled separately with different brightness levels. Due to the large number of pixels and the two-dimensional distribution of the pixels, it is possible to generate a variety of light distributions. These light distributions are projected into the environment by a two-part lens optic. The light module can be integrated into a headlight to generate light distributions such as low beam, high beam, partial long-range vision, and cornering light, either alone or together with other light modules. The described light module has the disadvantage that the image generated is highly colorful.This is because the described design cannot correct the chromatic aberration. This problem could be solved by using an achromatic or apochromatic lens. However, this leads to higher costs, greater weight, more space required, and generally lower optical efficiency of the light module due to increased losses due to Fresnel reflection and material absorption. Furthermore, according to the current state of the art, such a light module alone is not sufficient to generate a full high beam distribution in a headlight.

[0003] US 2008 / 055896 discloses a light module with which the brightness and / or color of a light source can be dynamically adjusted. For this purpose, the colors of the light emitted by LEDs, clusters, or groups of LEDs can be varied continuously or incrementally to create virtually any desired pattern of collimated light. The correction of chromatic aberration is not described. Further light modules are known from EP 3608585 A1 and KR 20160077990 A.

[0004] The present invention is based on the object of providing a light module with which the disadvantages described above can be eliminated.

[0005] This object is achieved with a light module according to claim 1.

[0006] According to the invention, starting from the light module of the type mentioned at the outset, it is proposed that the light module comprises a first sub-module for generating a first light distribution and at least one further, second sub-module for generating a second light distribution, wherein the first and second sub-modules each comprise at least one semiconductor light source with a light-emitting surface for emitting light and an optical system with a primary optic for bundling at least a portion of the emitted light and a secondary optic for projecting at least a portion of the bundled light in a light exit direction of the light module, wherein the overall light distribution of the light module comprises the superposition of the first light distribution and the second light distribution,and the semiconductor light source of the first sub-module is arranged at a wavelength-dependent focal point of a first wavelength of the optical system of the first sub-module and the semiconductor light source of the second sub-module is arranged at a wavelength-dependent focal point of a second wavelength of the optical system of the second sub-module, wherein the first wavelength is different from the second wavelength.

[0007] According to the invention, the first sub-module is designed for a first wavelength, and the second sub-module for a second wavelength. The light distributions of the first and second sub-modules each contain a relatively large color error, whereby color error here refers in particular to the deviation of the light color from a specific white point. By superimposing the light distributions of the first and second sub-modules, the color errors cancel each other out in the overall light distribution of the light module.

[0008] Because the first sub-module is designed for the first wavelength, the first sub-module sharply images rays of the first wavelength. Since the optical system includes neither an achromat nor an apochromat, the imaging of rays of other wavelengths, for example the second wavelength, is not optimal. The first light distribution therefore contains a chromatic aberration, particularly in the edge regions. A chromatic aberration is understood to be a deviation in the light color from a white point. For example, the light distribution at a cut-off line, in the area that should appear dark, contains a color fringe created by rays of the second wavelength. In the area of ​​the cut-off line that should appear bright, the proportion of rays of the second wavelength is again somewhat too low, so that rays of the first wavelength increasingly determine the light color here. This effect is also known as chromatic aberration.Chromatic aberration is not corrected by the primary optical system. As already mentioned, this would require an achromat or apochromat, which would require replacing the secondary optics with an achromat or apochromat. This, in turn, would increase the number of lenses in the optical system. This would result in higher costs, a larger required installation space, greater weight, and potentially lower optical efficiency.

[0009] Because the second sub-module is designed for the second wavelength, the second sub-module sharply images rays of the second wavelength. Since the optical system includes neither an achromat nor an apochromat, the imaging of rays of other wavelengths, for example the first wavelength, is not optimal. The second light distribution therefore contains a chromatic aberration, particularly in the edge regions. For example, the light distribution at a light-dark boundary, in the area that is supposed to appear dark, contains a color fringing created by rays of the first wavelength. In the area of ​​the light-dark boundary, which is supposed to appear bright, the proportion of rays of the first wavelength is again somewhat too low, so that rays of the second wavelength increasingly determine the light color here.

[0010] The color errors of the first light distribution of the first sub-module and the second light distribution of the second sub-module are corrected by superimposing the two light distributions.

[0011] By appropriately designing the first and second sub-modules, the color of the overall light distribution can be significantly reduced.

[0012] The overall light distribution generated by the light module does not include a harsh white contrast at the cut-off line. A harsh white contrast is typically undesirable in automotive headlights. Often, additional effort is even made to reduce the contrast at the cut-off line, for example, through microstructuring of lens surfaces or frosting. Such measures are unnecessary with the light module according to the invention.

[0013] Overall, a suitable design of the light module's sub-modules can produce a sufficiently color-neutral overall light distribution while simultaneously avoiding a harsh white contrast at the cut-off point. This eliminates the need for achromatic or apochromatic lenses and additional microstructuring or frosting of the lens surfaces. This advantageously minimizes costs, weight, and installation space. At the same time, with appropriate material selection and design, optical efficiency can be increased, as absorption is reduced by requiring fewer lenses or lens surfaces, and losses due to Fresnel reflection are reduced.

[0014] According to a preferred embodiment, the first light distribution of the first sub-module and the second light distribution of the second sub-module overlap at least partially, in particular largely. It may also prove advantageous if the illumination areas of the first and second sub-modules are identical, so that at least the first and second light distributions completely overlap.

[0015] According to a preferred embodiment, the semiconductor light source of the first sub-module and / or the semiconductor light source of the second sub-module comprises at least one, in particular several, light-emitting diodes (LEDs). The LEDs can be arranged in a matrix-like manner above and / or next to one another, thus forming an LED array. The LEDs of the semiconductor light sources can advantageously be controlled individually, in groups, or all together.

[0016] According to a further preferred embodiment, it is provided that a numerical aperture of the optical system of the first and / or the second sub-module is at least 0.5, in particular at least 0.65.

[0017] Advantageously, the secondary optics of the first sub-module and the secondary optics of the second sub-module can be formed as a single piece. This reduces the number of components and thus the tolerances to be maintained in the positioning of the components, as well as costs. Furthermore, the particularly single-piece, cylindrical shape of the light exit surface can have a beneficial effect on the aesthetic appearance of the light module.

[0018] Advantageously, it can be provided that the secondary optics of the first sub-module and / or the secondary optics of the second sub-module are designed as anamorphic lenses.

[0019] In a further development of this inventive concept, it may prove advantageous if at least one light entry surface of the anamorphic lens is designed as a cylindrical surface section with a horizontal axis of rotation and at least one light exit surface of the anamorphic lens is designed as a cylindrical surface section with a vertical axis of rotation.

[0020] Advantageously, it can be provided that the first sub-module and / or the second sub-module comprises a panel.

[0021] It may prove advantageous for the cover of the first sub-module and the second sub-module to be formed in one piece.

[0022] According to a further preferred embodiment, the light module has a third sub-module for generating a third light distribution with at least one semiconductor light source with a light-emitting surface for emitting light and an optical system with primary optics for bundling at least part of the emitted light and secondary optics for projecting at least part of the bundled light in a light exit direction of the light module, wherein the overall light distribution of the light module comprises the superposition of the third light distribution, wherein the third sub-module is arranged in a wavelength-dependent focal point of a third wavelength of the optical system of the third sub-module, wherein the third wavelength is different from the first and the second wavelength.

[0023] The design options described with reference to the first and / or second sub-module can also be applied to the third sub-module. Furthermore, the light module can comprise additional sub-modules, which are designed in particular for additional wavelengths.

[0024] Advantageously, it can be provided that the first wavelength is approximately 500 nm and / or the second wavelength is approximately 570 nm and / or the third wavelength is approximately 470 nm

[0025] A further embodiment comprises a motor vehicle headlight comprising at least one light module, wherein the light module is designed according to the embodiments described above.

[0026] Advantageous developments and further preferred embodiments of the present invention can be found in the dependent claims as well as the following description of the figures and the associated figures. Fig. 1 shows a light module according to the invention according to a first embodiment in a perspective view; Fig. 2 shows the light module from Figure 1 in a plan view from above; Fig. 3a and 3b each show a spot diagram for a first and a second optical system of the light module from the Figures 1 and 2 ; Fig. 4 shows a light module according to the invention according to a second embodiment in a perspective view; Fig. 5 shows the light module from Fig. 4 in a top view; Fig. 6 the light module from Figures 4 and 5 in a side view; Fig. 7a and 7b different embodiments of a secondary optics of the light module from the Figures 4, 5 and 6 , and Fig. 8 a motor vehicle headlight with a light module according to the invention.

[0027] The Figures 1 and 2show a light module, which is designated in its entirety by the reference numeral 10. The light module 10 is used in a motor vehicle headlight to generate a predeterminable overall light distribution in the light exit direction onto a roadway in front of the vehicle.

[0028] The light module comprises a first sub-module 20a and a second sub-module 20b. The first sub-module 20a comprises a semiconductor light source 22a. The second sub-module 20b comprises a semiconductor light source 22b. According to the illustrated embodiment, the semiconductor light sources 22a, 22b comprise a plurality of light-emitting diodes (LEDs). The LEDs can be arranged in a matrix-like manner, one above the other and / or next to the other, forming an LED array. The LEDs of the semiconductor light sources 22a, 22b can advantageously be controlled individually, in groups, or all together.

[0029] Furthermore, the first sub-module 20a and the second sub-module 20b each comprise an optical system 24a, 24b, each having a primary optic 26a, 26b for bundling at least a portion of the light emitted by the semiconductor light sources 22a, 22b and a secondary optic 28a, 28b for projecting at least a portion of the bundled light as a first and second light distribution in the light exit direction 12 of the light module 10.

[0030] The semiconductor light source 22a of the first sub-module is arranged at a wavelength-dependent focal point 30a of a first wavelength of the optical system 24a of the first sub-module 20a, and the semiconductor light source 22b of the second sub-module 20b is arranged at a wavelength-dependent focal point 30b of a second wavelength of the optical system 24b of the second sub-module 20b. The first wavelength and the second wavelength differ from each other.

[0031] By arranging the semiconductor light source 22a at the focal point 30a of the optical system 24a of the first wavelength and by arranging the semiconductor light source 22b at the focal point 30b of the optical system 24b of the second wavelength, the first sub-module 20a is designed for the first wavelength and the second sub-module is designed for the second wavelength. Design here means that the optical system 24a of the first sub-module 20a images the semiconductor light source 22a for the first wavelength and the optical system 24b of the second sub-module 20b images the semiconductor light source 22b for the second wavelength as sharply as possible.

[0032] The Figures 3a and 3beach show a so-called spot diagram of the first and second sub-modules 20a, 20b for a central object point, ie, for a point located at an intersection point of a plane of the respective semiconductor light source 22a, 22b and an optical axis of the respective optical system 24a, 24b. In the spot diagram, the points of incidence emanating from the central object point are shown in the image plane.

[0033] In Figure 3aThe spot diagram of the first sub-module 20a is shown. Rays of the first wavelength impinge in an area in the center of the diagram, while rays of the second wavelength impinge scattered around the area in the center, approximately within a radius of approximately 0.2 degrees. The points of incidence of the rays of the first wavelength are marked by a cross. The points of incidence of the rays of the second wavelength are marked by a square. Because the first sub-module 20a is designed for the first wavelength, the radius of the area in the center in which the rays of the first wavelength impinge is minimal. Since the optical system 24a comprises neither an achromat nor an apochromat, the imaging of rays of other wavelengths, for example the second wavelength, is not optimal. Light distributions that can be generated with the first sub-module 20a therefore include a chromatic aberration, particularly in the edge regions of the light distributions.Chromatic aberration is understood to be a deviation in the color of light from a white point. For example, a light distribution at a cut-off line, in the area that should appear dark, includes a color fringe created by rays of the second wavelength. In the area of ​​the cut-off line that should appear bright, the proportion of rays of the second wavelength is somewhat too low, so that rays of the first wavelength increasingly determine the color of the light. This effect is also known as chromatic aberration. The chromatic aberration is not corrected by the first optical system 24a. For this, for example, an achromat or an apochromat would be necessary, as already mentioned.This would in turn increase the number of components, in particular lenses, of the optical system 24a, and would thus result in higher costs, a larger required installation space, a greater weight and possibly a lower optical efficiency.

[0034] In Figure 3bThe spot diagram of the second sub-module 20b is shown. Rays of the second wavelength impinge on an area in the center of the diagram, while rays of the first wavelength impinge at scattered points around the area in the center, approximately within a radius of 0.2 degrees. The points of incidence of the rays of the first wavelength are marked by a cross. The points of incidence of the rays of the second wavelength are marked by a square. Because the second sub-module 20b is designed for the second wavelength, the radius of the area in the center in which the rays of the second wavelength impinge is minimal. Since the optical system 24b also does not include an achromat or apochromat, the imaging of rays of other wavelengths, for example the first wavelength, is not optimal.Light distributions that can be generated with the second sub-module 20b therefore contain a chromatic aberration, particularly in the edge regions of the light distributions. For example, a light distribution at a light-dark boundary, in the area that is intended to appear dark, contains a color fringe generated by rays of the first wavelength. In the area of ​​the light-dark boundary that is intended to appear bright, the proportion of rays of the first wavelength is again somewhat too low, so that rays of the second wavelength increasingly determine the light color here. The chromatic aberration is also not corrected by the second optical system 24b.

[0035] The chromatic aberrations of the first light distribution of the first sub-module 20a and the second light distribution of the second sub-module 20b can be corrected by superimposing the two light distributions. Advantageously, the first light distribution of the first sub-module 20a and the second light distribution of the second sub-module 20b overlap at least partially, in particular largely. It may also prove advantageous if the illumination areas of the first and second sub-modules 20a, 20b are identical, so that at least the first and second light distributions completely overlap.

[0036] The first wavelength is, for example, 500 nm and the second wavelength is, for example, 570 nm. In this case, the first light distribution includes a blue color fringe at the light-dark boundary, in the area that should appear dark, and a warm white to yellow light color in the area at the light-dark boundary that should appear bright. The second light distribution includes a yellow color fringe at the light-dark boundary, in the area that should appear dark, and a cool white to blue light color in the area at the light-dark boundary that should appear bright. By superimposing the two light distributions, the yellow and blue color fringes overlap at the light-dark boundary, in the area that should appear dark, and the cool white to blue light colors and the warm white to yellow light colors overlap in the area that should appear bright, so that the overall light distribution includes a white light color.

[0037] By appropriately designing the first and second sub-modules 20a, 20b, the color of the overall light distribution of the light module 10 can be significantly reduced.

[0038] The overall light distribution that can be generated with the light module 10 does not include a harsh white contrast at the light-dark boundary. A harsh white contrast is typically undesirable in motor vehicle headlights. Often, additional effort is even made to reduce the contrast at the light-dark boundary, for example, through so-called microstructuring of lens surfaces or frosting. Such measures are not necessary with the light module 10 according to the invention.

[0039] Overall, a suitable design of the sub-modules 20a, 20b of the light module 10 can produce a sufficiently color-neutral overall light distribution while simultaneously avoiding a harsh white contrast at the cut-off point. This eliminates the need for achromatic or apochromatic lenses and additional microstructuring or frosting of the lens surfaces. This advantageously minimizes costs, weight, and installation space. At the same time, with a suitable choice of materials and design, optical efficiency can be increased, as the smaller number of lenses or lens surfaces required reduces absorption and thus reduces losses due to Fresnel reflection.

[0040] In Figure 2Additionally, beam paths 32a, 32b of the first and second sub-modules 20a, 20b are shown for the respective wavelengths for which the sub-modules 20a, 20b are designed. The beam paths 32a, 32b each originate from a respective center of the respective semiconductor light source 22a, 22b located at the focal point 30a, 30b and are captured and imaged by the optical systems 24a, 24b.

[0041] The side-by-side representation of the beam paths is merely exemplary. Advantageously, the beam paths 32a, 32b overlap to form an overall light distribution of the light module 10.

[0042] The beams emanating from the semiconductor light sources 22a, 22b exhibit a high divergence. Typically, the semiconductor light sources 22a, 22b each radiate into the entire half-space. The more of these beams are captured and imaged by the optical systems 24a, 24b, the larger the so-called numerical aperture of the optical systems 24a, 24b. The numerical aperture is proportional to the sine of the aperture angle. If the semiconductor light sources 22a, 22b are Lambertian emitters, the optical efficiency of the optical systems 24a, 24b is in turn proportional to the square of the numerical aperture. Consequently, the efficiency is proportional to the square of the sine of the aperture angle. Consequently, it is very advantageous for the efficiency of the described light module 10 if the numerical aperture of the optical systems 24a, 24b is as high as possible. Advantageously, the numerical aperture of the optical systems 24a, 24b is at least 0.5, especially 0.65.

[0043] Figures 4, 5 and 6 show various representations of another embodiment of a light module 10.

[0044] According to the illustrated embodiment, the light module 10 comprises a further sub-module 20c. The sub-module 20c is in principle analogous to the already described

[0045] Submodules 20a, 20b are constructed and advantageously designed for a third wavelength. The third wavelength differs from the first and second wavelengths.

[0046] Furthermore, the light module in the Figures 4, 5 and 6 a cover 34. According to the illustrated embodiment, the cover 34 is formed as a single piece for the three sub-modules 20a, 20b, 20c. Alternatively, however, it is also conceivable for each sub-module 20a, 20b, 20c to comprise a separate cover.

[0047] According to the Figures 4, 5 and 6In the embodiment shown, the secondary optics 28a, 28b, 28c of the optical systems 24a, 24b, 24c of the sub-modules 20a, 20b, 20c are designed as a one-piece secondary optics 28. The one-piece secondary optics 28 is further designed as an anamorphic lens. This is shown in Figures 7a and 7b shown.

[0048] Figure 7a shows the anamorphic lens 28 from the light entrance side and Figure 7b from the light exit side. According to the illustrated embodiment, light entry surfaces 36a, 36b, 36c each comprise a cylindrical surface section with a vertical axis of rotation. The light exit surface 38 comprises a cylindrical surface section with a horizontal axis of rotation, in particular oriented perpendicular to the light exit direction 12.

[0049] The light entry surfaces 36a, 36b, 36c are designed so that incoming light rays are bundled in the horizontal plane, cf. Fig. 5 . The light exit surface 38 is advantageously designed so that emerging light rays are bundled in the vertical plane, cf. Fig. 6 .

[0050] The one-piece secondary optics 28 reduces the number of required components and thus the tolerances to be maintained regarding positioning and costs. Furthermore, the particularly one-piece, cylindrical shape of the light exit surface 38 can have a beneficial effect on the aesthetic appearance of the light module 10. Finally, Figure 8a motor vehicle headlight 40. The headlight 40 comprises a housing 42, which is made, for example, of plastic. The housing 42 has a light exit opening 44 in the light exit direction 12, which is closed by a transparent cover plate 46. A light module 10 according to the invention is arranged inside the housing 42. The light module 10 serves to generate any desired resulting driving light distribution of the motor vehicle headlight or a part thereof, e.g., a low beam, high beam, adaptive driving light (city light, country road light, motorway light, partial high beam, marker light), fog light, or the like.

[0051] Together with the light module 10, other light modules for generating any desired driving light distribution or part thereof, or light modules for implementing any desired light function (e.g. indicator light, position light, parking light, daytime running light, parking light, reversing light, brake light or the like) can also be arranged in the housing 42.

Claims

1. A light module (10) for a motor vehicle headlight (40) for generating an overall light distribution, wherein the light module (10) comprises a first sub-module (20a) for generating a first light distribution and at least one further, second sub-module (20b) for generating a second light distribution, wherein the first and the second sub-module (20a, 20b) in each case comprise at least one semiconductor light source (22a, 22b) with a light-emitting surface for emitting light and an optical system (24a, 24b) with a primary optic (26a, 26b) for bundling at least a portion of the emitted light and a secondary optic (28, 28a, 28b) for projecting at least a portion of the bundled light in a light exit direction (12) of the light module (10), wherein the overall light distribution of the light module (10) comprises the superposition of the first light distribution and the second light distribution, and the semiconductor light source (22a) of the first sub-module (20a) in a wavelength-dependent focal point (30a) of a first wavelength of the optical system (24a) of the first sub-module (20a), so that the first sub-module (20a) is designed for the first wavelength and sharply images rays of the first wavelength, and the semiconductor light source (22b) of the second sub-module (20b) is arranged in a wavelength-dependent focal point (30b) of a second wavelength of the optical system (24b) of the second sub-module (20b), so that the second sub-module (20b) is designed for the second wavelength and sharply images rays of the second wavelength, wherein the first wavelength is different from the second wavelength, characterized in that a color error in the first light distribution of the first sub-module (20a) caused by rays of the second wavelength and a color error in the second light distribution caused by rays of the first wavelength are canceled out by the superposition of the first and second light distributions in the overall light distribution of the light module.

2. The light module (10) according to claim 1, characterized in that the first light distribution of the first sub-module (20a) and the second light distribution of the second sub-module (20b) superpose at least partially, in particular largely.

3. The light module (10) according to one of the preceding claims, characterized in that the semiconductor light source (22a) of the first sub-module (20a) and / or the semiconductor light source (22b) of the second sub-module (20b) comprises at least one, in particular multiple, light-emitting diodes.

4. The light module (10) according to one of the preceding claims, characterized in that a numerical aperture of the optical system (24a, 24b) of the first and / or second sub-module (20a, 20b) is at least 0.5, in particular at least 0.65.

5. The light module (10) according to one of the preceding claims, characterized in that the secondary optic (28, 28a) of the first sub-module (20a) and the secondary optic (28, 28b) of the second sub-module (20b) are designed in one piece.

6. The light module (10) according to one of the preceding claims, characterized in that the secondary optic (28, 28a) of the first sub-module (20a) and / or the secondary optic (28, 28b) of the second sub-module (20b) are designed as anamorphic lenses (28).

7. The light module (10) according to claim 6, characterized in that at least one light entry surface (36a, 36b, 36c) of the anamorphic lens (28) is designed as a cylindrical surface portion with a horizontal axis of rotation and at least one light exit surface (38) of the anamorphic lens (28) is designed as a cylindrical surface potion with a vertical axis of rotation.

8. The light module (10) according to one of the preceding claims, characterized in that the first sub-module (20a) and / or the second sub-module (20b) comprises an aperture (34).

9. The light module (10) according to claim 8, characterized in that the aperture (23) of the first sub-module (20a) and the second sub-module (20b) is designed in one piece.

10. The light module (10) according to one of the preceding claims, characterized in that the light module (10) comprises a third sub-module (20c) for generating a third light distribution with at least one semiconductor light source (22c) with a light-emitting surface for emitting light and an optical system (24c) with a primary optic (26c) for bundling at least a portion of the emitted light and a secondary optic (28c) for projecting at least a portion of the bundled light in a light exit direction (12) of the light module (10), wherein the overall light distribution of the light module (10) comprises a superposition of the third light distribution, wherein the semiconductor light source (22c) is arranged in a wavelength-dependent focal point (30c) of a third wavelength of the optical system (24c) of the third sub-module (20c), wherein the third wavelength is different from the first and / or the second wavelength.

11. The light module (10) according to one of the preceding claims, characterized in that the first wavelength is approximately 500 nm and / or the second wavelength is approximately 570 nm and / or the third wavelength is approximately 470 nm.

12. A motor vehicle headlight (40) comprising at least one light module (10), characterized in that the light module (10) is designed according to at least one of the claims 1 to 11.