DE102018209302A1 - Lighting unit for adaptive lighting - Google Patents

Abstract

The invention relates to a lighting unit (1) with a light source arrangement (2) with a plurality of selectively activatable emission areas (2a-c), each of which is linked to its own spatial direction (5a-c) via an imaging lens system (4), with an entry surface (4aa) of the lens system (4) to avoid back reflections (8) is either asymmetrically concave or convex.

Description

Technical area

The present invention relates to a lighting unit for adaptive lighting, that is to say for the selective emission into different segments or spatial directions of a lighting field.

State of the art

A recent application of adaptive lighting is in the field of street lighting with a motor vehicle headlight, with z. B. ahead or oncoming vehicles to avoid glare from the lighting are excluded. For example, the illumination field is detected by a camera and then those segments or spatial directions in which a corresponding road user was detected are not illuminated. For example, lighting may even be possible in such a way that it is still illuminated but not dazzled (eg by illuminating the legs of a pedestrian). This is intended to illustrate a preferred field of application, but initially does not limit the subject matter in its generality.

A basic principle for the realization of adaptive illumination lies in the conversion between spatial and solid angle resolution, which is achieved with an imaging lens system. The light source arrangement is correspondingly subdivided into a plurality of emission regions which can be selectively, ie selectively, activated (spatial resolution). Such a light source arrangement, the imaging lens system then z. B. such that each emission range is mapped to infinity, which corresponds in principle to a Fourier transform and functionally converts the spatial into a spatial angle distribution. In order to collect as much illumination light as possible, the entrance surface of the lens system is curved in a concave manner, it may extend in a dome fashion over the light source arrangement.

Presentation of the invention

The present invention is based on the technical problem of specifying a particularly advantageous lighting unit.

• - gemäß Anspruch 1 gelöst, bei welcher die konkav gekrümmte Eintrittsfläche des Linsensystems asymmetrisch ist, und zwar bezogen auf eine Mittenachse der Lichtquellenanordnung (siehe unten im Detail), sowie mit einer Beleuchtungseinheit
• - gemäß Anspruch 6 gelöst, bei welcher die Eintrittsfläche des Linsensystems konvex gekrümmt ist.

This is inventively with the lighting unit

• - solved according to claim 1, wherein the concave curved entrance surface of the lens system is asymmetrical, with respect to a center axis of the light source assembly (see below in detail), as well as with a lighting unit
• - Solved according to claim 6, wherein the entrance surface of the lens system is curved convexly.

Both variants are motivated to reduce or avoid contrast-reducing back reflections at the entrance surface of the lens system. On the one hand, the inventors have found that such back-reflections can not always be sufficiently reduced even with an antireflection coating, especially with regard to the high light intensities in motor vehicle applications, especially since a coating is also complicated and expensive or sometimes even impossible to realize. z. B. due to adhesion to certain materials. On the other hand, in particular in the automotive sector, back reflections, as a result of which illumination light enters a spatial direction that is currently not supposed to be supplied with illumination light, may even be relevant to safety, for example when dazzling other road users and thus endangering road traffic.

Specifically, a back reflection considered here results if at least one of the emission regions is activated and its illumination light does not completely enter the lens system, but is reflected back to the light source arrangement proportionately at the entrance surface of the lens system (for example due to Fresnel reflections, typically to a certain extent) of a few percent). This is disadvantageous, in particular, when the back-reflected illumination light strikes another emission region, which is not actually activated at this time, and from this, for example due to scattering processes or absorption / reemission processes (in particular on a phosphor, see below) or else due to reflection processes (For example, on an uncoated chip), through the lens system in the assigned spatial direction (which is not supposed to be supplied).

Both variants according to claims 1 and 6 are based on the same basic idea, namely to design the entry surface so that any return reflexes are as far as possible adjacent to the light source arrangement or at least adjacent to the emission regions. In the case of the concave entrance surface, this is achieved with its asymmetry with respect to the center axis of the light source arrangement. The center axis of the light source arrangement is determined according to the emission regions, namely enforces their common centroid (determined as the geometric centroid of all emission surfaces). The center axis of the light source arrangement further points into the half-space in which the light source arrangement emits; it is located in front of the lens system parallel to a main direction of propagation of the illumination light (which is weighted by averaging when all emission surfaces are activated).

In relation to this central axis, that is to say with the light source arrangement as reference, the entrance surface according to the first variant is asymmetrical. The entrance surface is considered in section and it is asymmetrical to the center axis as a mirror axis. If, in said section plane, that part of the entrance surface which lies on one side of the center axis is mirrored on the other side (axis reflection about the center axis), this reflection is not congruent with the part of the entry surface arranged on the other side (which also vice versa). Thus, the entrance surface is not imaged onto itself in an axis mirroring about the center axis (viewed in said section plane). In particular, the asymmetry with respect to the light source arrangement can be achieved in different ways, for example by an offset and / or by an asymmetrical entrance surface, see the dependent claims. As a result of the asymmetry, the reflexes between the individual emission regions are at least reduced, they reach z. B. largely in addition to the light source arrangement.

According to the second variant, the entry surface is provided with a convex curvature viewed in section (the cutting plane includes the center axis of the light source arrangement). As a result of the convex curvature, the back reflections are scattered to a certain extent, that is fanned out towards the light source arrangement. Accordingly, at least there are fewer reflexes, these can also be located in total next to the light source arrangement. Put simply, according to the first variant (concave entrance surface) with the asymmetry, a back reflection, in particular imaging of the light source arrangement on itself is avoided (a possible image lies next to the light source arrangement), whereas according to the second variant (convex entrance surface) an image of the light source arrangement itself is already is avoided by fanning. However, both variants are based on the same idea.

Preferred embodiments can be found in the dependent claims and the entire disclosure, wherein in the representation of the features is not always distinguished in detail between device and process or use aspects; In any case, implicitly, the disclosure must be read with regard to all categories of claims. It therefore always relates to both the lighting unit and a motor vehicle headlight with such or corresponding uses or a method for designing or manufacturing.

As already mentioned, the lens system is imaging. In general, applications are also conceivable in the motor vehicle sector, in which the emission regions are imaged into the near field, for example for the projection of information onto the road. In this context, the term "near field" is understood in particular to mean the illumination of a surface, for example a vertical surface or spherical shell or free-formed surface, at a distance of up to 200 m. The lens system preferably forms the emission regions at infinity, that is to say the illumination field is subdivided into solid angle segments to which illumination light can optionally be supplied. Although the lens system can generally also consist of a single individual lens (converging lens), it preferably has a plurality of successively arranged individual lenses, compare the exemplary embodiments for illustration.

In any case, the optimization according to the invention relates to the entrance surface of the lens system, that is to say the first refractive surface (of the first single lens), as viewed from the light source arrangement, ie in the direction of irradiation with the illumination light. Reflections on these, the light source assembly facing the entrance surface can be particularly pronounced or critical, which is why an optimization to this effect offers particular advantages. Of course, other light transmission surfaces of the lens system can be optimized accordingly, that back-reflections are reduced. In principle, the relevance of the light passage surfaces decreases with increasing distance from the light source arrangement or the increasing number of intervening light passage surfaces.

Initially, reference was made to the inventive solution principle compared to an antireflection coating. However, these are not necessarily alternatives, and the lens system discussed herein may be provided with an antireflective coating, particularly at the entrance surface. By means of the combination, for example, a particularly high contrast can be achieved, or a simplified antireflex coating, which is thus advantageous in terms of costs, can be provided. Alternatively, however, an uncoated entrance surface is possible. In general, an antireflection coating may, for example, be composed of a plurality of dielectric layers adapted in their refractive indices.

The emission regions of the light source arrangement can be selectively activated, so they can be turned on or off individually according to at least the basic structure of the light source arrangement or activated or not. This can preferably be implemented with a semiconductor component which has a plurality of emission surfaces for emission of a semiconductor radiation (primary radiation), see below in detail. In detail, these emission surfaces can already be predefined by the light source arrangement (by an appropriate wiring) or with a control unit already a certain link. Thus, in the application, each emission range no longer necessarily has to be individually controllable externally, but it can also, depending on the type of use, give functionally summarized groups (eg low beam, high beam or "light finger", etc.).

In a preferred embodiment, which relates to the concave entrance surface, the lens system is arranged offset to the center axis of the light source arrangement. Specifically, an optical axis of the lens system is to be offset from the center axis of the light source arrangement. Because of this offset, the desired asymmetry of the entrance surface with respect to the center axis of the light source arrangement results, even if the entrance surface is considered to be symmetrical in itself (which is possible, but not mandatory).

In general, the "optical axis" of the lens system is the center axis in the direction of transmission. At least one or some of the light passage surfaces of the lens system are preferably at least rotationally, preferably rotationally symmetrically, about the optical axis (with the exception of an optionally asymmetrically designed surface, in particular an asymmetrical entrance surface).

In a preferred embodiment, an offset is provided such that the optical axis of the lens system passes laterally at the light source arrangement. In other words, the optical axis does not penetrate the light source arrangement. The extent of the light source arrangement is in this case measured according to their emission ranges, so it remains, for example, in the case of the semiconductor device, a possible edge region (wiring, etc.), which in turn is not itself designed for light emission out of consideration. Contrary to the emission direction, ie from the perspective of the lens system, looking at the light source arrangement, an envelope is therefore placed around the emission regions and the optical axis is to pass outside of it.

In a preferred embodiment, the lens system is arranged such that its optical axis is parallel to the center axis of the light source arrangement. In the case of the offset so a parallel offset is preferred. Of course, "parallel" refers to accuracy in the context of the technically usual, so it remains, for example, a possible tilting due to a mounting variability out of consideration. In general, the parallel arrangement can, for example, enable a lens system which is still easy to handle in design and assembly. In general, in the case of the offset, in particular parallel offset, the entry surface may also be rotationally symmetrical about the optical axis and nevertheless results in an asymmetry with respect to the center axis of the light source arrangement.

In an alternative preferred embodiment, the entry surface is asymmetrical with respect to the optical axis of the lens system. Specifically, the entrance surface is again viewed in section, wherein the sectional plane includes the center axis of the light source assembly. In this case, the entrance surface is asymmetrical not only with respect to this center axis as a mirror axis, but also with respect to its own optical axis as a mirror axis. In this sectional plane, therefore, the entrance surface is not imaged onto itself upon reflection on the optical axis, cf. the above explanations in detail (in contrast to this, the optical axis is now additionally used as a mirror axis).

According to this variant, the entrance surface is therefore already asymmetric in itself. Consequently, the main asymmetry with respect to the light source arrangement can be achieved even if its center axis coincides with the optical axis of the lens system. This is a first possibility, alternatively, however, the asymmetric entrance surface can also be combined with the offset, whereby the desired deflection of the back reflexes, for example, can be achieved without too great offset or excessive asymmetry (each measure makes a pro-rata contribution ).

In general, the inventive adaptation of the entrance surface, whether asymmetry or convex shape (see below), make a certain compensation by the rest of the lens system necessary. It may, for example, even be necessary to provide additional light passage surfaces for this purpose, that is, for example, an additional single lens. The disadvantage of this (cost, space, if necessary), however, usually weigh less difficult than a loss of contrast, especially as the latter, for example, in the case of automotive applications could also completely prevent implementation (due to the described security issues).

The below-described embodiments may relate to both the asymmetrical concave and the convex entry surface. In addition, in general, the latter can also be asymmetrical, with regard to the light source arrangement (the center axis thereof) or also by itself (with respect to the optical axis of the lens system). Preferably, however, the convex entry surface is symmetrical in itself and in terms of the light source arrangement (no offset).

A preferred embodiment relates to the luminous intensity contrast achieved with the concave or convex entry surface. Specifically, an inactive emission range is considered for this purpose, which (temporarily) does not actively emit, ie is not switched on or active by the light source arrangement. Furthermore, in the sense of a worst-case analysis, it is assumed that all other emission ranges are active, thus potentially maximizing any feedback on the inactive emission range. The contrast is then taken on the basis of the spatial direction with which the inactive emission region is linked, in which thus any scattered light is due, which would or would be due to back reflections in the inactive emission region. Specifically, the contrast then results as the ratio of the light intensity taken in a spatial direction of an active emission region to the light intensity along the spatial direction of the inactive emission region.

This contrast is in the order of naming increasingly preferred at least 100: 1, 150: 1, 200: 1, 250: 1 and 300: 1, respectively. In principle, a maximum of high contrast may be preferred, but for technical or application reasons, upper limits can be, for example, 500: 1, 450: 1 or 400: 1. In contrast formation, the light intensity along the spatial direction of the inactive region is compared with the light intensities along the surrounding spatial directions (ie the adjacent emission regions); Preferably, a corresponding contrast is achieved in relation to all spatial directions or active emission regions.

A further preferred embodiment relates to the position or orientation of the cutting plane in which the asymmetry or convexity exists. This should be based on an installation position of the lens system vertically, so so the avoidance of back-reflections and the contrast improvement is also achieved with respect. The vertical direction. This may be of particular interest in view of the preferred automotive applications because, for example, in the case of partial illumination of another road user (eg the legs of a pedestrian or the part below the windowpanes of a motor vehicle) ultimately "upwards" Back reflexes would be particularly critical. Demensprechend is preferably optimized to the vertical direction. The reference to the installation position of the lens system is based initially on its orientation in the application, for example in the motor vehicle headlight (taking into account its orientation in the vehicle). Furthermore, the imaging properties are also considered.

A preferred embodiment relates to the mean radius of curvature that the entry surface has in said cutting plane. In this case, a mean value formed in the sectional plane over the entry surface (which has a concave or convex curvature) is considered, whereby, of course, a constant radius of curvature is also possible (for example in the case of the offset concave entrance surface or in the case of the convex entry surface). This radius of curvature is set in relation to the geometric extent d of the light source arrangement in the sectional plane of the asymmetry. To put it simply, it is on the one hand advantageous if the radius of curvature does not become too large, that is, the entrance surface does not approach a planar shape, because this would favor the unwanted reflexes on the light source arrangement itself. On the other hand, the radius of curvature should not be too small, not least for reasons of manufacturability etc.

Advantageous lower limits of the mean radius of curvature are in the order of naming increasingly preferred at least 0.5, 0.8, and 1 times the extent d. Upper limits, which in general may also be of interest independently of the lower limits (and vice versa), are increasingly preferred in the order in which they are mentioned at most to the 50, 40, 30, 20, 15, 10, or 5 times the extension d. In general, the extension d is taken purely geometrically on the basis of the emission surfaces, specifically in that section plane in which the entrance surface is asymmetrical with respect to the light source arrangement.

In a preferred embodiment, the entrance surface is rotationally symmetric about the optical axis of the lens system. This has already been discussed above for the concave lens (the corresponding lens system is then preferably offset). Even in the case of the convex shape, a rotational symmetry may be preferred, although in general, for example, a cylindrical lens could also be provided.

In the following, the light source arrangement will be discussed further in detail. In at least one of the emission regions, in a preferred embodiment, a phosphor is arranged which emits a conversion light upon activation (preferably a phosphor can be arranged in several or all emission regions). The conversion light forms the illumination light either by itself (full conversion) or in mixture with proportionately non-converted primary radiation (partial conversion). In the case of such a phosphor-based light source arrangement, the asymmetrically concave or convex entrance surface may be of particular advantage, because conversely back reflections would be particularly critical. As a rule, the phosphor has a scattering effect for any back-reflected conversion light, ie distributes it relatively efficiently into the assigned spatial direction (which is undesirable if the corresponding emission region is actually inactive).

In general, such a phosphor-based light source arrangement for adaptive illumination could, for example, also be provided as a so-called LARP system (Laser Activated Remote Phosphor), for example with a scanning laser beam. Thus, for example, the laser beam could be moved with the aid of a mirror (MEMS mirror) over the surface of a phosphor element and optionally switched on or off per pixel (emission region). Accordingly, illumination light is emitted or not from a respective area (emission area) of the phosphor element. This spatial distribution is converted into a solid angle distribution with the lens system, see above.

On the one hand, such a LARP arrangement can be operated in reflection (irradiation and emission surface are identical), wherein the laser beam can then be coupled to the phosphor element, for example, by the lens system. On the other hand, an operation in transmission is possible, so the Einstrahl- and the radiating surface are thus opposite to each other, namely the phosphor element is irradiated. In this case, an operation in full conversion (all primary radiation is converted into conversion light) or partial conversion is possible, in the latter case, the conversion light in mixture with proportionately non-converted primary radiation forms the illumination light. An example of partial conversion is excitation with blue laser light that is proportionately converted to yellow conversion light (eg, with YAG: Ce as the phosphor), resulting in a mixture of white light.

In a preferred embodiment, the light source arrangement is not provided as a LARP source, but on the basis of a semiconductor device having a plurality of selectively activatable emission surfaces. These are then each assigned to the phosphor, and directly applied thereto (in direct optical contact, not with an air volume in between). At the emission surface (s) a semiconductor radiation is emitted in each case as primary radiation, which is converted completely (full conversion) or preferably proportionately (partial conversion) into the conversion light.

The emission surfaces of the light source arrangement can be formed on a single semiconductor component, but it is also possible for a plurality of components to be combined to form the light source arrangement. Preferably, a respective semiconductor component, even if it is combined with other components, on a plurality of emission surfaces (which are individually controlled, so are operable). Such an integration of multiple emission surfaces in the same semiconductor device may, for example, be advantageous in terms of an overall compact design. The semiconductor component may, for example, be provided based on an InGaN LED. It can be a continuous chip, but it is also possible for several semiconductor component parts to be joined together. In general, the chip or the parts may, for example, also have a hexagonal or trapezoidal basic shape, preferably a rectangle, in particular a square.

In general, the "primary radiation" is preferably blue light, ie it has, for example, a wavelength of at least 380 nm, preferably at least 400 nm or at least 405 nm, with upper limits (independent thereof), for example, at most 480 nm, 475 nm, or 470 nm can be (in the order of naming increasingly preferred). The primary radiation is preferably monochromatic or narrowband. The conversion light, in particular the first conversion light, is preferably yellow light, for example with a dominant wavelength of at least 500 nm or at least 530 nm and (independently thereof), for example at most 650 nm or 600 nm.

The invention also relates to a motor vehicle headlight with a lighting unit disclosed herein, preferably a motor vehicle headlight. The motor vehicle headlight can, for example, a tax and / or Have detection unit or connect to such or connected. As a detection unit can, for. B. a camera or a LiDAR or radar system may be provided, which detects the illumination side of the illumination field (which is accessible to the illumination light in the individual directions). If all emission areas are activated, the entire illumination field is illuminated. If, for example, another road user, such as oncoming traffic or a vehicle driving in front, then dives into the illumination field, this is evaluated by the control unit and the emission areas assigned to the corresponding spatial directions are deactivated, for example switched off (emitting surfaces of the LED) or no longer irradiated (LARP arrangement) ).

The invention also relates to a method for designing a lighting unit disclosed herein, based on a simulation model. In this first, the light source assembly and the lens system are placed relative to each other and the ab initio resulting back reflections are determined. This can be done in particular on the basis of a symmetrical entry surface, ie without offset or asymmetry in itself. In a subsequent step or several iterative steps, the arrangement is then optimized in such a way that fewer or no retroreflections strike the respective other emission regions of the light source arrangement itself.

In this case, those back reflections at the entrance surface of the lens system are considered, which result between the different emission regions, ie from one emission region via the entrance surface to another. These return reflections reduce the contrast and are therefore undesirable. There are various possibilities for implementation in simulation; for example, only one emission area can always be activated and the entire light source arrangement can then be viewed in several successive steps. Likewise, however, a simultaneous emission is conceivable as long as it is resolved which return reflections go back to which emission regions. In principle, back reflections on the originally emitting emission region itself are less critical; they may even be preferred in terms of recycling the radiation. Specifically, an implementation in which each emission region is imaged on itself at the entrance surface may not always be possible or subject to greater optical restrictions.

Preferably, the entrance surface is adapted so that the back reflections between different emission regions are reduced. In general, the back reflections can still lie within the light source arrangement (within an envelope around the emission surfaces). An optimization is to the effect that the return reflections are reduced within the light source arrangement, so then, for example, are largely outside this.

In this optimization, it is assumed that the size of the light source arrangement is given. In particular, the offset (between optical axis and center axis) and / or the curvature of the entrance surface in the section and / or the distance between the light source arrangement and the entrance surface and / or the lens material (refractive index) are optimized as optimization variables. With the offset and the distance so the relative position of the source and lens system is both axially and vertically optimized. In general, as explained above, a plurality of manipulated variables can be adapted at the same time; for example, an asymmetrical entrance surface in combination with an offset is possible. Likewise, it can also be optimized only by one of the sizes.

In any case, the back reflections at the entrance surface are considered, in addition, of course, other light transmission surfaces or other sources of scattered light can be taken into account. However, the influence of the entrance surface on the contrast is so high that it requires consideration or optimization with regard to the desired contrasts.

Other sources of stray light or reflection light can be, for example, holders or enclosures of the lenses, etc. These can be "passivated" in the product, that is to say in the finally produced lighting unit, as areas which are not optically active, e.g. B. obscured or roughened etc.

The back reflections, which are guided with the inventive design of the entrance surface next to the emission regions or the light source arrangement, can then be largely "destroyed" there, so the surface next to the light source arrangement can for example be. Passivated, as well as a beam trap can be provided.

The invention also relates to the use of a presently disclosed lighting unit for lighting, in particular for automotive exterior lighting, preferably for adaptive street lighting. In general, adaptive lighting can also be used in other areas, for example in the Entertainment area (stage or show lighting), in the industrial sector (eg adaptive lighting of a robot or robotic arm, etc.) or in the medical field (surgical field illumination). Advantages always arise when the aim is to illuminate as accurately as possible adaptively, ie with high contrast.

list of figures

In the following, the invention will be explained in more detail with reference to an exemplary embodiment, wherein the individual features in the context of the independent claims in another combination may be essential to the invention and continue to distinguish not in detail between the different claim categories.

• 1 eine nicht erfindungsgemäße Beleuchtungseinheit zur Illustration von Rückreflexen;
• 2 eine erfindungsgemäße Beleuchtungseinheit, bei welcher im Unterschied zu 1 das Linsensystem versetzt ist;
• 3 die Anordnung gemäß 2, wobei ein anderer Emissionsbereich der Lichtquellenanordnung aktiv ist;
• 4 in Ergänzung zu den 2 und 3 die Beleuchtungseinheit im Gesamten, mit dem vollständigen Linsensystem;
• 5 als Alternative zu dem Versatz gemäß den 2 - 4 eine in sich asymmetrische Eintrittsfläche;
• 6 als Alternative zu den Varianten gemäß den 2 - 5 ein Linsensystem mit konvex gekrümmter Eintrittsfläche;
• 7 zu 6 die gesamte Beleuchtungseinheit, mit dem vollständigen Linsensystem.

In detail shows

• 1 a lighting unit not according to the invention for illustrating back reflections;
• 2 a lighting unit according to the invention, in which, in contrast to 1 the lens system is offset;
• 3 the arrangement according to 2 wherein another emission region of the light source device is active;
• 4 in addition to the 2 and 3 the lighting unit in its entirety, with the complete lens system;
• 5 as an alternative to the offset in accordance with 2 - 4 an asymmetrical entrance surface;
• 6 as an alternative to the variants according to the 2 - 5 a lens system with a convexly curved entrance surface;
• 7 to 6 the entire lighting unit, with the complete lens system.

Preferred embodiment of the invention

1 shows a lighting unit 1 with a light source arrangement 2 for the emission of illumination light 3 ,

The lighting unit 2 has several emission areas 2a-c on, which are selectively activated. In the situation according to 1 is only the emission area 2a activated, so only emits this illumination light 3 , The other emission areas 2 B . c can be optionally switched on. In detail, the light source arrangement 2 Semiconductor-based, realized as an LED device, see the introduction to the description in detail.

The light source arrangement 2 is also a lens system 4 assigned, which from the different emission areas 2a-c out emitted illumination light 3 in different directions 5a-c leads. In the case of the situation according to 1 So if the emission area 2a emitted, should only the assigned spatial direction 5a with illumination light 3 be supplied. A preferred field of application is the adaptive street illumination with a motor vehicle headlamp, in which selectively excluded from an illumination field solid angle segments, so are not illuminated, in which find other road users, see the introduction to the description.

In the components and functions described so far, the lighting unit corresponds 1 a construction according to the invention. In contrast to such is the concave entrance surface 4aa of the lens system 4 , specifically the collective lens 4a , but symmetrical with respect to a center axis 6 the light source arrangement 2 , This center axis 6 falls with an optical axis 7 of the lens system 4 together, and the entrance area 4aa is also mirror-symmetrical in itself.

The dotted lines in 1 illustrate the consequence, that is back reflexes 8th of the emission area 2a out emitted illumination light 3 ultimately on the emissions area 2c to meet. This is inactive in the situation shown, the spatial direction 5c So should not illuminating light 3 be supplied. In the emission area 2c However, in concrete terms, the phosphor of the LED, it comes to the scattering of the reflected back light, so this is the result, at least to a certain extent returned to the front. Effective thus also from the emission area 2c Light emitted, although this is inactive, so the spatial direction 5c Illuminating light supplied. The contrast is reduced, and in the case of automotive applications, safety-relevant glare effects can occur.

The 2 - 4 illustrate a first approach of the invention for solving this problem. The entire lens system 4 is relative to the light source assembly 2 offset, so there is an offset 20 between the center axis 6 and the optical axis 7 of the lens system 4 , Here are the center axis 6 and the optical axis 7 parallel to each other. To illustrate the effect is in 2 analogous to the situation according to 1 only the emission range 2a active, and become the resulting reflexes 8th considered (dashed). The reflexes 8th no longer meet another emission area 2 B . c they are even completely outside the light source arrangement 2 , Accordingly, the spatial directions 5b . c that are the emission areas 2 B . c are associated, fed in this way no stray light, which increases the contrast.

3 shows the same figure, in contrast to the emission range 2c is active, so the emission areas 2a . b are inactive. Due to the offset 20 between the axes 6 . 7 meet the reflexes 8th also in this case next to the light source arrangement 2 on, so do not cause stray light. Depending on the application and also required efficiency, the entrance surface 4aa additionally be anti-reflective, but the reflectivity will be in the order of one percent even in the case of an anti-reflection coating, at least at an unfavorable angle of incidence.

4 shows the lighting unit according to the invention 1 whose lens system 4 according to the 2 and 3 offset, in an overall view, it is in particular the other individual lenses 4b-d shown. That from a respective emission area 2a-c out illuminated light 3 As a result, this will result in each case individually (per emission range 2a-c ) collimated and in their own spatial direction 5a-c guided.

5 shows as an alternative to the displacement of the entire lens system 4 a lens 4a , their entrance surface 4aa is asymmetrical in itself. Specifically, the entrance area 4aa regarding the optical axis 7 of the lens system 4 asymmetric. With a reflection on the optical axis 7 becomes the entrance surface 4aa not shown on its own, compare the dashed lines for illustration (this would correspond to a symmetrical reflection of the lower half of the optical axis 7 ).

The effect achieved corresponds to the above description, reflexes 8th of the illumination light 3 Be next to the light source assembly 2 guided.

As an alternative to the concave entrance surface 4aa relating to the light source arrangement 2 is asymmetric, either by offset or in itself, illustrating the 6 and 7 an entrance area 4aa which is convexly curved. As an illustration, again, there is an emission area 2a the light source arrangement 2 active. The reflexes 8th become the light source arrangement due to the convex shape 2 not bundled, but fanned out. As a result, isolated reactions may still be reflexes 8th within the light source assembly 2 However, their density can be at least reduced, compared to 1 helps to improve the contrast.

7 shows to the arrangement according to 6 the entire lighting unit 1 So also the other lenses 4b . c , With the lens system 4 analogous to the above description, one from a respective emission range 2a-c out emitted illumination light collimates in the respective spatial direction 5a-c be guided.

LIST OF REFERENCE NUMBERS

lighting unit 1 Light source arrangement 2 emitting regions 2a-c illumination light 3 lens system 4 Single lens (first) 4a Concave entrance area 4aa Single lenses (further) 4b-d spatial directions 5a-c mid-axis 6 Optical axis 7 retroreflections 8th offset 20

Claims (15)

An illumination unit (1) for adaptive illumination, comprising a light source arrangement (2) with a plurality of emission regions (2a-c) arranged around a common central axis (6) and an imaging lens system (4) associated with the light source arrangement (2), which covers each emission region (2a-c) associated with a respective own spatial direction (5a-c), wherein the emission regions are selectively activated, ie emit their respective illumination light (3) to a respective separate activation in the respective assigned spatial direction, and wherein an entrance surface (4aa ) of the lens system (4) is concavely curved when viewed in a sectional plane containing the center axis (6) of the light source arrangement (2), characterized in that the entrance surface (4aa) is asymmetrical with respect to the light source arrangement (2), namely asymmetrically viewed in the sectional plane around the center axis (6) as a mirror axis. Lighting unit (1) after Claim 1 in which the lens system (4) is arranged offset, so that its optical axis (7) to the center axis (6) of the light source assembly (2) is offset. Lighting unit (1) after Claim 2 in which the lens system (4) is arranged offset in such a way that the optical axis (7) of the lens system (4) passes laterally past the light source arrangement (2). Lighting unit (1) according to one of the preceding claims, in which the lens system (4) is arranged such that its optical axis (7) is parallel to the central axis (6) of the light source arrangement (2). Lighting unit (1) according to one of the preceding claims, in which the entrance surface (4aa) viewed in the sectional plane is also asymmetrical with respect to an optical axis (7) of the lens system (4), namely viewed asymmetrically about the optical axis in the sectional plane ( 7) as a mirror axis. Illumination unit (1) for adaptive illumination, comprising a light source arrangement (2) having a plurality of emission regions arranged around a common center axis (6), and an imaging lens system (4) which is assigned to each light source arrangement (2) and which covers each emission region (2a-c). linked with a respective own spatial direction, wherein the emission regions are selectively activated, ie emit their respective illumination light (3) to a respective separate activation in the respective assigned spatial direction, characterized in that an entrance surface (4aa) of the lens system (4) in one viewed in the center axis (6) of the light source arrangement (2), when viewed in a sectional plane, it is convexly curved, that is to say it protrudes toward the light source arrangement (2). Lighting unit (1) according to one of the preceding claims, in which a luminous intensity contrast which results in the case of an inactive emission area (2a-c) with respect to its spatial direction (5a-c), namely from the remaining spatial directions (5a-c) assuming that their emission regions (2a-c) are activated is at least 100: 1. Lighting unit (1) according to one of the preceding claims, in which, in an installed position of the lens system (4), the sectional plane in which the entrance surface (4aa) is viewed is vertical. Lighting unit (1) according to one of the preceding claims, wherein the light source arrangement (2) has a geometric extension d, which is taken over the entire emission areas (2a-c) in the sectional plane, and the entrance surface (4aa) in the sectional plane considered a Amount taken after taking average curvature radius r, where 0.5-d ≤ r ≤ 50 · d. Lighting unit (1) according to one of the preceding claims, except Claim 5 in which the entrance surface (4aa) of the lens system (4) is rotationally symmetrical about an optical axis (7) of the lens system (4). Lighting unit (1) according to one of the preceding claims, wherein in at least one of the emission regions of the light source assembly (2) a phosphor is arranged, which emits a conversion light upon activation, which at least partially forms the illumination light (3). Lighting unit (1) after Claim 11 in which the emission regions are formed on a semiconductor component which has a plurality of selectively activatable emission surfaces for emission of a primary radiation, wherein at least one of the emission surfaces is assigned a phosphor to at least partially convert the primary radiation into the conversion light. Motor vehicle headlight with a lighting unit (1) according to one of the preceding claims. Method for designing a lighting unit (1) according to one of the preceding claims, wherein in a simulation model - The light source assembly (2) and the lens system are placed relative to each other; - back reflections are determined, which, starting from a respective active emission region (2a-c), at the entry surface (4aa) result in a respective different emission region (2a-c); which backreflections are minimized iteratively by changing the offset between optical axis (7) of the lens system (4) and center axis (6) of the light source assembly (2) and / or the curvature of the entrance surface (4aa) and / or the distance between the light source assembly (2) and the entrance surface (4aa) and / or the lens material. Use of a lighting unit (1) according to one of Claims 1 to 12 for lighting, in particular for automotive exterior lighting, preferably for adaptive street lighting.

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