description

The present invention relates to a low beam headlight or a low beam for motor vehicles.

Essential features of the angular distribution of the light intensity of a low beam for motor vehicles are an approximately symmetrical distribution in the horizontal direction with a half-width of approx. 8 ... 10 ° and an asymmetrical vertical distribution with a half-width of approx. 2 ... 3 ° with a Above, sharp light-dark border with high contrast to avoid dazzling oncoming vehicles.

With right-hand traffic in the direction of travel, the light-dark border forms a horizontal line at a vertical height of approx. - 0.6 °. To the right of the direction of travel, the border is shifted upwards in order to better illuminate traffic signs, for example. Often a horizontal light-dark border is also aimed for on the right. The region in which the border is moved is called the elbow and is located in the central area of ​​the radiation in the direction of travel. The generation of this complex intensity distribution requires large headlight systems with comparatively low transmission.

In conventional low-beam headlights, a screen shaped to match the light-dark boundary is illuminated by a beam-shaped light source (usually LED or halogen lamp) and then projected to infinity onto the roadway using projection optics. In order to achieve the required small divergences, attempts are made to achieve the smallest possible aperture dimensions, which enables a correspondingly small focal length of the projection optics. When reducing the dimensions, however, one is limited by the available luminance of the light sources and the required minimum light intensity of the headlamp.

In order to achieve small dimensions, light sources with high luminance (eg LEDs) are combined with highly efficient beam-shaping optics with free-form reflectors and lenses to achieve high transmission. The resulting systems nevertheless have an extension of well over 10 cm in the direction of light propagation.

An alternative approach using lens arrays was disclosed in [1]: Several individually collimated LEDs are used as the light source, which illuminate a condenser microlens array, followed by a diaphragm array and a projection lens array. The transition from conventional single-aperture optics to multi-aperture optics can greatly reduce the focal length of the projection optics and thus the overall length of the headlight. However, the system's transmission is reduced by the aperture array. Furthermore, the screens are located in the vicinity of an intermediate image plane of the illumination beam path, which causes high energy densities on the absorbing screens and thus a noticeable heat input into the micro-optical system.

Accordingly, there is a desire for a concept for a low beam which makes it possible to achieve short overall lengths, but at the same time to achieve an effective use of energy.

The object of the present invention is therefore to create a low beam or a low beam headlamp which enables short overall lengths to be achieved with a high light energy yield. This object is achieved by the subject matter of the independent claim.

Optics used within the light source arrangement can thus be designed as single-lens optics, ie each lens or optic therein is penetrated by all of the light contributing to the low beam. It is therefore also inexpensive and can not only be provided in a short overall length. In addition, the light source arrangement already takes on one of the beam shaping tasks due to the different divergence in the two

Transversal directions. According to exemplary embodiments of the present application, the divergence in the second transversal direction takes over, for example, the definition of the horizontal opening angle of the low beam. The different divergence preparation by the light source arrangement is then used in the lens arrays in order to effectively use the different divergence in the transverse directions specifically for respective sections of the low beam and to achieve the desired radiation.

According to exemplary embodiments, for example, the two outer lens arrays are designed as cylindrical lens arrays, so that they only take on the task of beam shaping in the first transverse direction, while the section of the low beam illuminated by these lens arrays corresponds to a straight extension of the segment of the light cone of the light source arrangement radiating through them. In particular, the two outer lens arrays can be designed as a honeycomb condenser with cylindrical honeycomb lenses on the inlet side and on the outlet side. The lens arrays thus use the predivergence reduction by the light source arrangement. A mutual offset of an arrangement of the entry-side honeycomb lenses with respect to the exit-side honeycomb lenses in the first transverse direction can be different for the first and third lens arrays with regard to the arrangement of the lens opening and / or lens vertex, so that a change in the light intensity angle distribution of the segment of the light cone radiating through the first lens array in the first transverse direction through the first lens array differs from a change in the light intensity distribution of the segment of the light cone radiating through the third lens array in the first transverse direction through the third lens array. In particular, the two lens arrays can produce light-dark edges in the two outer sections of the low beam in the second transverse direction,

The second or middle lens array, which takes care of the section of the low beam in the middle in the second transverse direction, can likewise be designed as a honeycomb condenser with honeycomb lenses on the inlet side and on the outlet side. Its inter-honeycomb lens distance in the second transverse direction can be greater for the honeycomb lenses on the exit side than for the honeycomb lenses on the entrance side. The magnification can correspond to the higher divergence of the light of the light cone from the light source arrangement along the second transverse direction. This honeycomb condenser can have a diaphragm array buried directly behind the entry-side honeycomb lenses in the middle section to form the elbow, the image of which then defines the elbow just mentioned by the honeycomb lenses on the exit side. A diaphragm-free design is also possible, according to which the elbow is defined by lens edges, e.g. B. the lower lens edges, one or more entry-side honeycomb lenses can be imaged by the corresponding exit-side honeycomb lenses, namely on the elbows just mentioned, in order to define the latter. For this purpose, these imaged edges of the lens openings of the entry-side honeycomb lenses are designed in a correspondingly different manner from an otherwise rectangular basic shape of the lens openings of the entry-side honeycomb lenses. one or more entry-side honeycomb lenses can be imaged by the corresponding exit-side honeycomb lenses, namely on the elbows just mentioned, in order to define the latter. For this purpose, these imaged edges of the lens openings of the entry-side honeycomb lenses are designed in a correspondingly different manner from an otherwise rectangular basic shape of the lens openings of the entry-side honeycomb lenses. one or more entry-side honeycomb lenses can be imaged by the corresponding exit-side honeycomb lenses, namely on the elbows just mentioned, in order to define the latter. For this purpose, these imaged edges of the lens openings of the entry-side honeycomb lenses are designed in a correspondingly different manner from an otherwise rectangular basic shape of the lens openings of the entry-side honeycomb lenses.

It is thus possible to make the low beam just described almost loss-free. In particular, lens openings of the honeycomb lenses of the aforementioned honeycomb condensers can be joined together without gaps. The lens openings of the exit-side honeycomb lenses of the aforementioned honeycomb condensers can have an equidistant pitch in the first transverse direction. Even if the diaphragm array is used in the honeycomb condenser of the second lens array, the loss of light is relatively small. In the case of the diaphragm-free configuration, the lens arrays can even be configured in plastic, for example using injection molding technology.

Preferred exemplary embodiments of the present application are explained in more detail below with reference to the drawings. Show it:

1 shows a spatial representation of the components of a low beam according to an exemplary embodiment of the present application;

2 shows an embodiment of the two outer lens arrays of the low beam according to an exemplary embodiment;

3 shows a plan view with two side sectional views of the middle lens array according to an exemplary embodiment;

FIG. 4 shows a top view and two side sectional views of the central lens array according to a variant in which, in contrast to FIG. 3, there is a diaphragm-free configuration; FIG. and

5 shows a simplified perspective spatial view of the low beam and the light generated by it with the light distribution corresponding to a low beam.

The embodiments described below follow a novel, etendue-preserving approach to generating continuous light intensity distributions by means of irregular honeycomb condensers [2], which largely or even completely dispenses with diaphragms in order to make low beam with a short overall length and increased transmission possible. FIG. 1 shows a first exemplary embodiment of a low beam 100 or a low beam headlight 100 or a device 100 for generating a low beam 102 (cf. FIG. 5).

An LED or an LED cluster (1) is preferably used as the light source, which - in accordance with the aspect ratio of the required output beam - preferably has a greater extent in the horizontal than in the vertical direction. The LED's typically Lambertian radiation is shaped by secondary optics. In this case, a collimation takes place in the vertical direction, whereas the divergence in the horizontal, similar to the required horizontal distribution of the headlight, is only reduced. These secondary optics preferably consist of a radially symmetrical asphere (2) for reducing divergence and a subsequent cylindrical lens collimator (3). If the LED resp.

In Fig. 1, the light source 1, the cylindrical collimator 3 and the aspherical lens 2 located between them thus form a light source arrangement 10 for generating a light cone 12 from light which is less divergent in a first transverse direction y than in a direction perpendicular to the first transverse direction y second transverse direction x. When installing the low beam from FIG. 1 in a motor vehicle, the second transverse direction x corresponds to the horizontal, which will be assumed further below. It should be pointed out, however, that the configuration of the light source arrangement 10 from FIG. 1 is only an example and alternatives also exist. For example, instead of a cylindrical lens collimator 3, an acylindrical collimator or a toroidal collimator could be used. Overall, the light source arrangement can be designed such that the light from the light cone 12 has a divergence that is more than 10 times greater in the horizontal x than in the vertical y. The asymmetrical divergence is used by the lens arrays which the light cone 12 illuminates, as will be described below. For example, the divergence in the horizontal direction can be such that the opening angle of the light cone 12 is between 20 and 50 degrees.

The following micro-optics for beam shaping consists of three horizontally arranged segments 4a-c, namely lens arrays, which, as shown in FIG are.

To achieve the required continuous vertical distribution to the right and left of the direction of travel, according to the present exemplary embodiment, irregular honeycomb condensers, preferably cylindrical lens honeycomb condensers 4a and 4b, each with different vertical heights along the axis y of the projected light-dark boundary 16 are used 5 with different aperture heights or different large lens openings in y, some of which consist of decentered cylinder lens segments. The exit lenslets 6 have a constant aperture height, but can also partly consist of decentered lens segments, as is shown in FIG. Through controlled decentering of the output array to the input array, the height of the light-dark boundary 16 can be set differently for the areas 14a, b to the left and right of the direction of travel. The desired horizontal light intensity distribution right and left to the direction of travel is achieved by the beam shaping of the asphere 2 or the light source arrangement 10.

In other words, the low beam 100 has a first lens array 4a, a second lens array 4c and a third lens array 4b, which are arranged next to one another along the horizontal x in order to be irradiated on the input side by an assigned segment of the light cone 12, into the latter is segmented along the horizontal. On the output side, the lens arrays emit the low beam, as shown in FIG. 5, with a light intensity angle distribution that is different from that of the light cone 12. As shown in FIG. 2, the two outer lens arrays 4a and 4b can be designed as cylindrical lens arrays, so that they allow the respective light segment 12a and 12b of the light cone 12 through which they are shone through in the horizontal direction x without being deflected, which vice versa means that the section or area 14b and 14a of the low beam which is illuminated by the lens arrays 4a and 4b corresponds to a straight extension of the respective light cone segment 12a and 12b along the horizontal axis x, namely with the horizontal divergence of the light cone 12. In particular, the lens arrays 4a and 4b be designed as a honeycomb condenser with inlet-side and outlet-side cylindrical honeycomb lenses 5 and 6. The inlet-side and outlet-side cylindrical honeycomb lenses, also referred to as lenslets, each form a one-dimensional array in the direction y. The lens openings or apertures of the honeycomb lenses 5 and 6 can have a rectangular design and be joined to one another without gaps, as shown in FIG. 2. What the mutual offset of the arrangement with entry-side lenslets or

To determine the light intensity angle distribution in the respectively assigned low beam section 14a and 14b, namely in particular the light-dark boundary 16. For this purpose, this mutual offset is designed differently for the two lens arrays 4a and 4b. The cylindrical lenslets 6 on the exit side can have lens openings of the same size as one another in y and can be arranged with a constant repetition spacing from one another, as shown. The cylindrical honeycomb lenses 6 on the exit side can thus form a regular array. As shown, however, some or some of the cylindrical lenslets 6 on the exit side can be decentered in y

Have lens vertices. For each lens array 4a and 4b there is preferably a paired assignment between input lenslets 5 and output lenslets 6, so that each input lenslet 5 bundles the incident light of the respective segment 12a and 12b into the assigned output lenslet 6 along direction y. The bundling of an input lenslet 5 that is extended in y into an output lenslet 6 that is smaller in y effects an increase in divergence and, in the opposite case, a reduction in divergence in the y direction is achieved. The exit lenslets 6 are located in a focal plane of the entrance lenslets 5. A Köhler illumination is thus achieved.

The central segment (4c) of the micro-optics consists of a tandem array of irregular, rectangular lenslets, which generate the maximum light intensity in the direction of travel and the inclined part of the light-dark boundary or elbow 18, as shown in FIG.

The input array and output array each have a constant but different lenslet size and spacing in the horizontal direction: The horizontal direction of the optical axes of the individual array channels correspond to the horizontal direction of incidence of the light source for the respective array channel. The horizontal distance or pitch of the lenslets 7 of the output array is therefore greater than that of the lenslets 9 of the input array.

The input array has different lenslet sizes in the vertical direction. The apertures of the input lenslets can be relative to the corresponding

Exit lenslets be decentered. In order to enable Köhler illumination in this case as well, the entrance lenslets are then designed as decentered lens segments so that the light source is always imaged in the center of the associated exit lenslet. The output array has rectangular lenslet apertures with constant width and height. In order to achieve the desired far-field distribution, however, lenslets can also be designed here as decentered lens segments.

The border of a diaphragm structure 8 buried under the entrance lenslets 9 is imaged onto the road as a light-dark boundary by the exit lenslets 7. This mode of operation corresponds to a multichannel projector imaging to infinity, whereby reference is made to [3] for further details.

In other words, the second middle lens array 4c can also be designed as a honeycomb condenser with lenslets 9 on the inlet side and lenslets 7 on the outlet side. In the horizontal x, the inter-honeycomb lens spacing of the exit-side lenslets 7 can be greater than for the entry-side lenslets 9, specifically corresponding to the divergence of the light of the incident light cone 12 in this direction x. The honeycomb condenser, which forms the middle lens array 4c, is a two-dimensional honeycomb condenser with a two-dimensional array of honeycomb lenses or lenslets 9 on the entrance side and a corresponding two-dimensional array of honeycomb lenses or lenslets 7 on the exit side. Again, there can be a pair or 1-to-1 assignment between the lenslets 7 and 9: Each pair of the input lenslet 9 and the output lenslet 7 forms a channel, the input lenslet 9 focusing incident light onto the respective output lenslet. This creates a Köhler lighting. The array of exit lenslets 7 can be regular in x and y, ie the exit lenslets can have rectangular lens openings that are joined together without gaps in order to be arranged in columns of the same width and in lines of the same width. The exit-side lenslets 7 could have centered lens vertices, as is shown in FIG. 3, although an alternative also exists, according to which they have decentered lens vertices. The exit-side lenslets 7 are at a focal distance from the entrance-side lenslets 9 and vice versa, the same applies, ie

An alternative implementation of the central segment is also possible without buried diaphragms with irregular input lenslets 9, the contour of which corresponds to the geometry of the elbow - or the diaphragm structures from FIG. 3. Figure 4 shows a corresponding implementation.
1. Low beam headlights with

a light source arrangement (10) for generating a light cone (12) from light which is less divergent in a first transverse direction (y) than in a second transverse direction (x) perpendicular to the first transverse direction;

a first, second and third lens array (4a, 4b, 4c), which are arranged next to one another along the second transverse direction (x), in order to receive on the input side an associated segment of segments (12a, 12b, 12c) arranged next to one another in the second transverse direction of the light cone (12) to be irradiated and to output dipped beam (102) on the output side with a light intensity angle distribution that is different than that of the light cone (12).

2. Low beam headlamp according to claim 1 for installation in a motor vehicle, so that the second transverse direction (x) corresponds to a horizontal.

3. low beam headlamp according to claim 1 or 2, wherein the light source arrangement (10) in the first and second transverse directions (y, x) divergent light source (1) and a collimator (3) for collimating divergent light from the light source (1) with has an increased degree of collimation in the first transverse direction (y) compared to the second transverse direction (x).

4. Low beam headlamp according to claim 3, in which the light source arrangement (10) has an aspherical lens (2) between the light source (1) and the collimator (3) for pre-collimation.

5. low beam headlamp according to claim 3 or 4, wherein the collimator (3) comprises a cylindrical lens collimator or an acylindrical collimator or a toroidal collimator.

6. low beam headlamp according to one of claims 1 to 5, wherein the light source arrangement (10) is designed so that the light of the light cone (12) has a divergence that is more than 10 times greater in the second transverse direction (x) is than in the first transverse direction (y).

7. Low beam headlamp according to one of the preceding claims, in which the second lens array (4c) is arranged between the first and third lens arrays (4a, 4b), and the first and third lens arrays (4a, 4b) are designed as cylindrical lens arrays, so that for each of the first and third lens arrays (4a, 4b) the segment (12a, 12b, 12c) of the light cone (12) which shines through the respective lens array (4a, 4b), on the output side a section (14a, 14b) of the low beam (102 ) which, along the second transverse direction (x), corresponds to a straight extension of the respective segment (12a, 12b).

8. Low beam headlamp according to one of the preceding claims, wherein the second lens array (4c) is arranged between the first and third lens arrays (4a, 4b), and each of the first and third lens arrays (4a, 4b) as

Honeycomb condenser with inlet-side and outlet-side cylindrical honeycomb lenses (5, 6) is formed.

9. Low beam headlamp according to one of the preceding claims, in which the second lens array (4c) is arranged between the first and third lens arrays (4a, 4b), and each of the first and third lens arrays (4a, 4b) as

Honeycomb condenser is formed with a first one-dimensional array of entry-side cylindrical honeycomb lenses (5) extending along the first transverse direction and a second one-dimensional array of exit-side cylindrical honeycomb lenses extending along the first transverse direction.

10. Low beam headlamp according to claim 9, in which a mutual offset of an arrangement of the entry-side cylindrical honeycomb lenses (5) with respect to the exit-side cylindrical honeycomb lenses (6) in the first transverse direction (y) for the first and the third lens array (4a, 4b) with respect to the lens opening and / or the apex of the lens is different, so that a change in the light intensity angle distribution of the segment (12a) of the light cone (12) radiating through the first lens array (4a) in the first transverse direction (y) compared to a change in the light intensity angle distribution that radiating through the third lens array (4b) Segment (12b) of the cone of light (12) in the first transverse direction (y) is different.

1 1. Low beam headlamp according to claim 10, in which the exit-side cylindrical honeycomb lenses (6) for the first and third lens arrays (4a, 4b) have lens openings of the same size as one another in the first transverse direction (y) and are arranged at a constant repeat distance from one another.

12. Low beam headlamp according to one of the preceding claims, in which the second lens array (4c) is arranged between the first and third lens arrays (4a, 4b) and is designed as a honeycomb condenser with entry-side and exit-side honeycomb lenses (7, 9), an inter- The honeycomb lens spacing in the second transverse direction for the honeycomb lenses (7) on the exit side is greater than for the honeycomb lenses (9) on the entrance side.

13. Low beam headlamp according to claim 12, in which the honeycomb condenser of the second lens array (4c) has a diaphragm array (8) buried behind the entry-side honeycomb lenses (9) as seen from the light source arrangement, the image of which through the exit-side honeycomb lenses (7) is light-dark -Edge (18) generated in a central section (14c) of the low beam (102).

14. Low beam headlamp according to claim 12, in which the honeycomb condenser of the second lens array (4c) is designed to be diaphragm-free.

15. Low beam headlamp according to claim 12, in which the honeycomb condenser of the second lens array (4c) is designed to be diaphragm-free and so that an image of lens edges of the entrance-side honeycomb lenses (9) through the exit-side honeycomb lenses (7) in a central section (14c) of the low beam (102) create a light-dark edge (18).

16. Low beam headlamp according to one of claims 1 to 15, wherein

the light intensity distribution of the low beam (102) in a first section (14a), which is illuminated by the segment (12a) of the light cone (12) radiating through the first lens array (4a), in the first transverse direction (y) through the first The lens array (4a) has a first light-dark edge (16) running in the second transverse direction (x),

the light intensity angle distribution of the low beam (102) in a second section (14b), which is illuminated by the segment (12b) of the light cone (12) radiating through the third lens array (4b), in the first transverse direction (y) through the third lens array one in the third light-dark edge (16) running in the second transverse direction and having a different position in the first transverse direction (y) than that of the first light-dark edge (16),

the light intensity angle distribution of the low beam (102) in a third section (14c) which is illuminated by the segment (12c) of the light cone (12) radiating through the second lens array (4c), in the first transverse direction (y) by the second lens array (4c) ) has a second light-dark edge (18) which runs obliquely with respect to the first and second transversal directions (x, y) and which runs from the first to the third light-dark edge.

17. Low beam headlamp according to one of the preceding claims, in which the first, second and third lens arrays are formed monolithically on a common substrate.

18. Motor vehicle with a low beam headlamp according to one of the preceding claims.