EP2799762B1 - Light module for a motor vehicle headlamp - Google Patents

Description

description

The present invention relates to a light module of a motor vehicle headlight according to the preamble of claim 1.

Such a light module is assumed to be known here. A light module of a motor vehicle headlight is an assembly which, alone or in conjunction with other light modules of the same headlight or at least one other headlight, generates a rule-compliant light distribution in front of the motor vehicle when used as intended in a motor vehicle.

The light module assumed to be known has several light sources, primary optics and secondary optics, the primary optics being set up to collect light emanating from the light sources and to convert it into an intermediate light distribution which shapes the shape has a closed luminous surface. The secondary optics have a focal length on the object side, and the primary optics and the secondary optics are arranged in such a way that the intermediate light distribution lies at a distance from this focal length in the light path in front of the secondary optics.

Intermediate light distributions of light modules that are intended to produce a light distribution with a light-dark boundary are limited on at least one side by a sharp edge.

The secondary optics is a lens or a reflector and has a focal plane on the object side, which is characterized by the fact that contours lying in it are sharply imaged in an area in front of the light module that lies behind the secondary optics in the direction of propagation of the light.

A light module similar to the subject matter of claim 1 is from EP 2 789 900 known, which forms a state of the art according to Art. 54 (3) EPC. Claim 1 differs from this document in that the light module is set up to generate a low beam light distribution with a light-dark boundary. Other similar light modules are out EP 2 500 628 A2 and WO 2013/031210 A1 known. Recently, semiconductor light sources such as light emitting diodes (LED) have been increasingly used as light sources in motor vehicle headlights. At the beginning of this development, mainly (signal) lights for premium vehicles were operated with light-emitting diodes, in the future the dipped and main beams of mid-range cars will also be optionally generated by LEDs.

As a result of this development, there is a market for low-cost low beam and high beam light modules that use LEDs as light sources.

Today, high-performance LED low beam modules are mostly designed as projection headlights. Two-stage optics first generate a real intermediate image of the light exit surface of the light-emitting diodes used as light sources. So-called arrays of several light-emitting diodes are used in order to generate sufficiently large luminous fluxes. The light exit surface of a single LED that is used in such an array is, for example, square and has an edge length of approximately one millimeter. The individual LEDs are arranged within the array in such a way that their light exit surfaces adjoin one another directly and virtually without any gaps, so that the overall light exit surface of the array appears to be coherent. The disadvantage of these light modules is in particular the high price for the projection lens and the expensive LED arrays.

Reflection systems are much simpler in structure, in which a reflector in simple reflection (1-stage optics) generates a low beam distribution. The light distribution is formed as a superposition of many elementary images of the light source. The image of the light source is understood as the image of the light source through an infinitesimally small reflector zone. In order to superimpose the light source images to form a homogeneous light distribution, the light source itself should also have a uniform luminance. In addition, the light source needs a sharp border, with the image of which the sharp light-dark border of the low beam distribution is generated. As a result, the simple, inexpensive reflective optics require an expensive LED array as a light source.

If, instead of an LED array, which has a quasi-closed light-emitting surface, several individual LEDs arranged at a distance from one another are used (for example: SMD-LEDs, SMD: surface mounted design), the gaps between the LED chips lead and thus in particular between the light exit surfaces too dark stripes in the light distribution. If you try to blur the resulting stripes of the light distribution using scattering optics on the reflector surface to form a homogeneous light distribution, the maximum illuminance is reduced at least in the ratio of the chip width to the sum of the chip width and chip spacing. This means that the average luminance of such a blurred light source compared to an array in which the LED chips are arranged directly next to one another is lower at least in the aforementioned ratio.

Due to the tolerances of the individual chips, also in connection with the color-converting phosphor, the sides of the LED chips are never really on a line, which leads to unclean light-dark boundaries when the array is shown.

Since in reflection systems the cut-off line is not created by imaging a screen, as is the case with projection systems, but is made up of differently oriented light source images, with conventional reflection systems the light center is significantly lower than the cut-off line than with projection systems. This affects the range, since the range decreases as the brightness of the light area just below the light-dark boundary decreases. It is also disadvantageous that reflective systems do not have such high illuminance gradients at the light-dark boundary can be achieved, as they are common in projection systems.

Against this background, the object of the invention is to provide a light module that is as compact as possible, which can be operated with inexpensive SMD LEDs and which does not require an expensive, voluminous projection lens. In addition, the performance of the light module with regard to the illuminance at the edge of a cut-off line of a low beam light distribution and with regard to the steepness of the gradient of the brightness curve across the cut-off line should approach the performance of projection modules.

This object is achieved with the features of claim 1. The present invention differs from the light module assumed to be known in that the primary optics is a one-piece base body made up of converging lens subareas, and that the chip of a light-emitting diode is located between a converging lens subarea that collects light from this light-emitting diode and its focal point on the object side, with the light exit surfaces of the light sources passing through distances lying between them are separated from one another and that the primary optics are set up to distribute light emanating from the light sources in such a way that the distances are not recognizable in the intermediate light distribution.

The several light sources mentioned at the beginning are preferably implemented as an LED array. The secondary optics preferably have several facets, so that several light source-side focal points or a focal line result. It is therefore particularly preferred that the secondary optics have several object-side focal points.

In one embodiment, a faceted reflector is arranged as secondary optics in the light path behind the intermediate light distribution. The reflector is preferably set up to generate a complete low beam distribution from the intermediate light distribution which has an asymmetrical rise.

The reflector can be replaced by a faceted lens with appropriate focal positions. In an alternative embodiment, the secondary optics are implemented as a faceted lens. Due to the more favorable ratio of focal length to aperture (f-number) with lenses compared to reflectors, there is less color aberration in the lens secondary optics.

In this way, the intermediate light distribution represents in a certain way a substitute light source which has the required property of a streak-free appearance and which can be used together with an inexpensive reflection system to generate a rule-compliant light distribution.

A preferred embodiment is characterized in that the primary optics for each light source has its own optically effective partial area, each of which has a light exit surface and these light exit surfaces adjoin one another without a gap, and at least two adjacent light exit surfaces adjoin one another in such a way that at least one side edge of one first of two adjacent light exit surfaces in a line in alignment with a side edge of the second of the two adjacent Light exit surfaces so that the two aligned edges form a common, straight edge.

The primary optics are preferably a one-piece optics array, with each LED being assigned an optically effective partial area as a collecting primary optics and with all primary optics largely directly adjacent to one another with their light exit surfaces. At least two of these optics form a common straight edge with their light exit surfaces.

It is also preferred that each sub-area is a converging lens. In this case, the optics array is preferably constructed from planoconvex lenses and preferably consists of organic or inorganic glass or of silicone rubber (LSR). Organic glasses are, for example, polymethyl methacrylate (PMMA), cycloolefin copolymer (COC), cycloolefin polymer (COP), polycarbonate (PC), polysulfone PSU or polymethacrylmethylimide (PMMI). The lens array preferably has a straight edge at least in sections on one side. For this purpose, the collecting lens array is delimited at least in sections at one edge by a flat side surface, on which part of the incident light is reflected. Alternatively, this edge can also be formed by a diaphragm which is brought into the beam path directly in front of the light exit surface of the lens array.

Instead of metallization, a multilayer coating can be applied to the plastic body. In the multilayer coating, several low and high refractive index layers are alternately combined. A further metal layer can be provided as a radiation barrier under the reflective metal or multilayer layer. This metal layer is deposited, for example, as a thick copper or nickel layer on the plastic body of the reflector array and thus forms protection against the thermal stress caused by the radiation from the LED. This thick metal layer is also able to dissipate heat towards the edge of the reflector.

A heat shield can be provided between the reflector array and the LED, which shades the radiation from the LED onto the rear of the reflector body and thus prevents thermal overloading of the reflector material. The reflector array preferably has at least one straight edge as the edge of a row of light exit surfaces of adjacent reflector subregions.

As a further alternative, it is also preferred that each sub-area is a light guide.

In this case, the primary optics are preferably designed as a light guide array, which consists of light guides widening conically towards the light exit, which preferably have square or rectangular cross-sections in planes on which the main direction of emission of the LED is perpendicular. The light entry surface of the individual light guide subregions is each preferably arranged flat and parallel to the chip surface of the assigned LED. This gets a bigger part of the from the LED outgoing luminous flux coupled into the light guide section than with a convex curvature. In addition, the refraction already results in a certain bundling. Further bundling takes place through reflections on the side walls of the light guide, which is due to the shape that expands towards the light exit. The reflections that take place on the side walls also distinguish light guides from lenses, which are also transparent solids. In the case of lenses, changes in direction of the light only occur through refraction, but not through reflection on the side walls.

It is also preferred that the light exit surface of the individual light guides is convexly curved. This creates a bundling effect when the light emerges. The light guide array preferably consists of one of the materials that was mentioned above as lens material. The light guide array has at least one straight edge, which is composed of edges, adjoining one another in alignment, of individual light exit surfaces of adjacent light guide subregions.

Another preferred embodiment is characterized in that the light module has a screen which is arranged in the beam path of the light directly behind the light exit surface in such a way that it shades part of the intermediate light distribution.

The diaphragm facilitates the generation of a sharp light-dark boundary of the intermediate light distribution, which also has a favorable effect on the sharpness of the rule-compliant light distribution that is ultimately to be generated in advance of the light module. In a preferred embodiment, the panel is attached to the as an insert part or two-component injection-molded part Primary optics are molded on, which has the advantage of low tolerances between the aperture and the primary optics.

It is also preferred that the secondary optics have at least one concave mirror reflector. A concave mirror reflector has the advantages of lower costs and lower weight, in particular in comparison to transparent solid bodies such as lenses or secondary optics operating with total internal reflection.

In order to achieve a good sharpness of the cut-off line and thus a high illuminance gradient, all reflectors are preferably arranged in the beam path in such a way that the beam path at the respective reflectors is always folded at as acute an angle (<90 °) as possible. Due to the acute folding angle of the beam path, the elementary images of the substitute light source hardly change their orientation, so that low-beam light distributions with good homogeneity (no longitudinal stripes in the light distribution), high light focus (just below the low-beam light-light-dark boundary) and sharp light-dark Can create border.

It is also preferred that an optical surface of the secondary optics is divided into a larger sub-area and a smaller sub-area, the larger sub-area being defined by the fact that it has a first object-side focal point and that the two sub-areas have a common image-side focal point at infinity.

As a result, these secondary optics produce an image of the substitute light source in infinity and thus a light distribution in front of the light module, the shape of which is depends on the shape of the intermediate light distribution and thus on the shape of the substitute light source and which, in particular, has a sharp light-dark boundary if such a boundary is also present in the intermediate light distribution.

It is also preferred that the concave mirror reflector has a reflecting surface, the larger part of which has a parabolic shape, an object-side focal point of the parabolic shape lying on the light exit surface of the primary optics.

The object-side focal point of the reflector is preferably on the edge of the substitute light source. To generate a low beam distribution, this is the lower edge of the substitute light source. As described, this edge can also be shaded by a screen to prevent stray light from entering the dark field of the light distribution.

If the secondary optics has several reflector facets, their focal points are preferably also on the edge of the substitute light source. However, depending on the position of the facet, they are preferably positioned at different ends of the light source edge.

It is also preferred that the secondary optics consists of two mirrors that are arranged one behind the other in the beam path in such a way that they fold the beam path of the secondary optics twice at an acute angle and that the secondary optics have an object-side focal point that lies on the light exit surface of the primary optics and the latter Pixel lies at infinity.

By folding at an acute angle, the aforementioned advantages of good sharpness of the cut-off line are achieved because the acute angle means that the orientation of the images of the substitute light source parallel to the cut-off line is largely retained.

The double folding also opens up the possibility of shortening the installation space of the light module and provides a further degree of freedom for the arrangement of the elements of the light module. In particular, particularly compact light modules can thereby be implemented. In addition, it offers structural advantages if the light source radiates forward in the direction of travel and the heat is removed from the light source via a heat sink to the rear: Such a light source can easily be changed from the rear of the headlight. The heat sink on the back of the light module can also be ventilated more easily, which improves the cooling performance. The compact design has the additional advantage that the center of gravity of the light module is in the vicinity of the light exit surface, which facilitates the mechanical pivoting of the light module for headlight range control and / or a cornering light function.

The folding of the beam path is also beneficial because the refractive power in the proposed optical system is divided into primary and secondary optics, so that secondary optics with a low refractive power, i.e. with a long focal length (the focal lengths are 2-3 times larger than with single-stage Systems). This is advantageous because the very long focal lengths in relation to the opening result in an optical system that is insensitive to tolerances. In addition, all chip images have approximately the same size and orientation.

It is also preferred that the first mirror in the direction of propagation of the light in the beam path has a hyperboloid and the second mirror has a paraboloid as a reflection surface, the object-side focal point of the hyperboloid forming the object-side focal point of the secondary optics and the image-side focal point of the hyperboloid coinciding with the focal point of the paraboloid and marks the position of a virtual intermediate image of the intermediate light distribution.

It is also preferred that the secondary optics have several object-side focal points and one or more common image-side focal points or focal lines at infinity.

It is also preferred that the first mirror of the two-stage secondary optics has a hyperboloid or is a plane mirror as a special case of the hyperboloid, and that the second mirror has a faceted paraboloid, the object-side focus of the hyperboloid forming the object-side focus of the secondary optics and the image-side The focal point of the hyperboloid marks the position of a virtual intermediate image of the intermediate light distribution and the downstream parabolic facets are set up to focus on the edge of the virtual image of the intermediate light distribution.

It is also preferred that the first mirror of the two-stage secondary optics has a faceted hyperboloid or, as a special case thereof, a faceted plane mirror and that the second mirror has a paraboloid, the object-side focus of the hyperboloid being the object-side Forms the focal point of the secondary optics and the image-side focal point of the hyperboloid marks the position of a virtual intermediate image of the intermediate light distribution and the parabolic facets downstream in the beam path focus on the edge of the virtual image of the intermediate light distribution.

Another preferred embodiment is characterized in that the two mirrors have several object-side focal points which lie on the edge of the intermediate light distribution and whose image point or their image lines lie at infinity on the light-dark boundary of the light distribution, the two mirror surfaces so are shaped so that all optical paths between the object-side focal point and its respective image points or image lines are of the same length.

In this embodiment, the two mirrors of the two-stage secondary optics are not based on conic sections and do not provide a sharp, undistorted intermediate image of the substitute light source. The optical system, however, has several object-side focal points which lie on the edge of the light exit surface of the primary optics and whose image points or image lines lie at infinity on the light-dark boundary of the light distribution.

An optical system made up of deflection optics 64 and secondary optics 12 does not necessarily have to deliver a sharp virtual intermediate image 66, since aberrations (blurring, distortion, aperture errors) of the intermediate image can be compensated for again by the downstream secondary optics 12.

Further advantages emerge from the description and the attached figures.

It goes without saying that the features mentioned above and those yet to be explained below can be used not only in the respectively specified combination, but also in other combinations or alone, without departing from the scope of the present invention.

Fig. 1

ein Ausführungsbeispiel eines erfindungsgemäßen Lichtmoduls mit einer unterhalb der Sekundäroptik liegenden Ersatzlichtquelle;

Fig. 2

ein Ausführungsbeispiel eines erfindungsgemäßen Lichtmoduls mit einer oberhalb der Sekundäroptik liegenden Ersatzlichtquelle;

Fig. 3

verschiedene Ansichten einer Baugruppe aus Platine, LEDs und einer Primäroptik mit als Reflektoren verwirklichten Teilbereichen eines nicht erfindungsgemäßen Lichtmoduls;

Fig. 4

verschiedene Ansichten einer Baugruppe aus Platine, LEDs und einer Primäroptik mit als Sammellinsen verwirklichten Teilbereichen;

Fig. 5

verschiedene Ansichten einer Baugruppe aus Platine, LEDs und einer Primäroptik mit als Lichtleitern verwirklichten Teilbereichen eines nicht erfindungsgemäßen Lichtmoduls;

Fig. 6

eine perspektivische Darstellung eines Ausführungsbeispiels eines erfindungsgemäßen Lichtmoduls, das einen an einem zusätzlichen Umlenkspiegel gefalteten Strahlengang aufweist;

Fig. 7

den Gegenstand der Fig. 6 mit verschiedenen Ausgestaltungen des Umlenkspiegels, jeweils in einer Seitenansicht;

Fig. 8

Vorderansichten von zwei Ausgestaltungen erfindungsgemäßer Lichtmodule mit Anordnungen der Ersatzlichtquelle gemäß den Alternativen der Fig. 1 und der Fig. 2;

Fig. 9

eine von einem Ausführungsbeispiel eines erfindungsgemäßen Lichtmoduls im Vorfeld des Lichtmoduls erzeugte Abblendlichtverteilung und eine schematische Darstellung von Lichtquellenbildern, aus denen sich die Abblendlichtverteilung zusammensetzt.

Exemplary embodiments of the invention are shown in the drawings and are explained in more detail in the following description. They show, each in schematic form:

Fig. 1

an embodiment of a light module according to the invention with a replacement light source located below the secondary optics;

Fig. 2

an embodiment of a light module according to the invention with a replacement light source located above the secondary optics;

Fig. 3

various views of an assembly made up of circuit board, LEDs and primary optics with partial areas of a light module not according to the invention, implemented as reflectors;

Fig. 4

different views of an assembly of circuit board, LEDs and primary optics with partial areas implemented as converging lenses;

Fig. 5

different views of an assembly of circuit board, LEDs and primary optics with partial areas realized as light guides of a light module not according to the invention;

Fig. 6

a perspective view of an embodiment of an inventive Light module which has a beam path folded on an additional deflecting mirror;

Fig. 7

the subject of Fig. 6 with different configurations of the deflection mirror, each in a side view;

Fig. 8

Front views of two configurations of light modules according to the invention with arrangements of the substitute light source according to the alternatives of FIG Fig. 1 and the Fig. 2 ;

Fig. 9

a low beam distribution generated by an exemplary embodiment of a light module according to the invention in advance of the light module and a schematic representation of light source images from which the low beam distribution is composed.

The same reference symbols in the figures refer to the same or at least comparable elements in terms of their function.

In detail, the Fig. 1 a spatial arrangement of a light source assembly 10 and a secondary optics 12 as an embodiment of a light module 14 according to the invention. There are holding structures that define and fix this arrangement in space, for reasons of clarity and because they are neither for the understanding of the invention nor for the feasibility of the invention are of importance, not shown. The representation of the Fig. 1 is therefore concentrated on the optical elements of the light module. This also applies to the other figures.

The light source assembly 10 and the secondary optics 12 are arranged in such a way that they generate a rule-compliant light distribution 16 on a screen 17 in front of the light module. In the case shown, the light distribution 16 has a light-dark boundary 18 running horizontally in sections.

When the light module 14 is used as intended in a motor vehicle headlight of a motor vehicle that is standing on a level surface, the part 18.1 of the horizontal cut-off line closer to the road runs approximately at the level of the horizon in front of the vehicle or very slightly (usually 0, 57 °) below. The point at which the cut-off line bends upwards is roughly the extension of the vehicle's longitudinal axis. A vertical V running through this point intersects the horizon H at a point on the screen, which is also referred to as HV = (0,0). For details of such a light distribution, see the explanations Figure 9 referenced.

A sagittal plane 20 and a meridional plane 22 can be assigned to the optical system of the light module 14. The sagittal plane 20 lies parallel to the roadway at the level of the horizon H. The meridional plane 22 is defined by the direction of the vertical V and an optical axis of the light module 14, which passes through the HV = (0.0) point.

The light source assembly 10 comprises a heat sink 24 and a circuit board 26 with SMD LEDs 28 arranged thereon and the associated primary optics. The SMD LEDs with the associated primary optics 30 are shown enlarged as detail Z.

Due to their design, the SMD LEDs 28 are arranged in such a way that their light exit surfaces do not adjoin one another without a gap. The light emitted by these SMD LEDs 28 is bundled by the primary optics 30 in such a way that a cohesive, closed intermediate light distribution is established on the seamlessly lined up light exit surfaces of the primary optics 30. This intermediate light distribution, which serves as a substitute light source, is then reproduced by the secondary optics 12 as a low beam distribution 16 on a screen 17 located at a distance in front of the light module 14. The lower edge 32 of the primary optics 30 is imaged as the light-dark boundary of the low beam distribution.

The reflector surface of the secondary optics 12 consists of several reflector facets 12.1, 12.2. 12.3, which are implemented as paraboloids of revolution, for example, at least in areas of their reflection surface. These areas each take up the greater part of the reflection surface of a facet. The different paraboloids for different facets have different focal points 34, 36, all of which are located on the lower edge 32 of the light exit surface of the primary optics 30. The focal points 34, 36 preferably lie at the corners of the primary optics 30. The meridional plane 22 divides the space of the optical system into two half-spaces. If the light source shines from below into the secondary mirror, the mirror facets and their focal points are in the same half-space. The axes of the paraboloids of revolution on which the reflector facets are based point in the direction of the low-beam light-dark boundary 18. In this exemplary embodiment, the light source edge is mapped as the light-dark boundary of the rule-compliant light distribution.

As a representative light beam of the Fig. 1 In the following, a main ray 38 from the beam path of the light module, which runs in the meridional plane 22, is considered.

The main emission directions of the individual LEDs are preferably parallel to one another and in this respect match. The light beam 38 under consideration runs in the main emission direction of the light sources 28 through the lower edge of the light exit surface of the primary optics 30 and propagates in the direction of the reflector surface of the secondary optics 12. The main beam 38 is reflected at the reflector surface at an acute angle (<90 °) and arrives at a point the light-dark boundary 18 of the light distribution 16 is guided in the range H = 0 °, the vertical component of which is usually at V = -0.57 °.

The subject of Figure 2 differs from the subject of Figure 1 in that the light source 10 radiates into the secondary reflector 12 from above. The meridional plane 22 divides the space of the optical system into two half spaces. If the light source shines into the reflector from above, the focal points of the parabolic facets are always on the other side of the meridional plane like the reflector facet itself, which is in comparison to Figure 1 is illustrated by the focal points 34, 36 swapped from right to left in detail Y. Due to the different arrangement of the light source, the sides of the focal points 34, 36 of the respective reflector facets are thus interchanged. Overall shows Figure 2 also an LED low beam module 14 with an asymmetrical cut-off line 18.

The task of the primary optics 30 is within here The invention presented in particular consists in generating a sharply delimited, streak-free and in this respect suitable as a substitute light source intermediate light distribution in a plane that is sharply imaged by the secondary optics 12 in the rule-compliant light distribution 18. For this purpose, the primary optics 30 must in particular generate a closed, coherent luminous surface from the light exit surfaces of the SMD LEDs 28 that are not spaced apart.

For this purpose, the SMD LEDs 28 are arranged in one or more parallel rows. In front of the LED array, an optics array 30 of collecting lenses, reflectors or conical light guides is brought into the beam path so that the light exit surface is illuminated as evenly and homogeneously as possible and the emitted beam has no gaps.

Figure 3 : (not part of the invention) shows an example of a primary optics array 30 of reflectors. The reflector subregions 40 are implemented here as recesses adjoining one another without spacing from a one-piece base body 42. Figure 3b FIG. 11 shows a perspective view of the assembly comprising the printed circuit board 26 and the reflector subregions 40 which cover the associated LEDs. Figure 3a shows a section through this assembly, which runs in the direction of the row arrangement. Figure 3d FIG. 11 shows a section through this assembly, which runs transversely to the array and FIG Figure 3c shows a plan view and a position of said sections.

The reflector subareas have rectangular, in particular square cross-sections. The light exit surfaces of the individual reflectors 40 are lined up without gaps and thus without any gaps and delimit the resulting luminous surface with sharp, straight edges 44. Each SMD LED 28 is assigned a reflector 40. The center points of the reflectors 40 and the center points of the light exit surfaces of the light sources 28 are spaced equally. The row arrangement of the reflectors 40 therefore has the same pitch as the row arrangement of the LEDs 28.

In one embodiment, a heat shield 46 is arranged between the reflector partial areas and the LED, which protects the rear side of the reflector partial areas 40 of the optical array 30 from radiation. Of course, the heat shield 46 is interrupted over the light exit surfaces of the SMD LEDs 28 in order to allow light to exit.

especially the Figures 3a, 3b and 3d clearly show an array of reflectors 40 widening conically towards the light exit with square or rectangular cross-sections, such a cross-section being arranged perpendicular to the optical axis and thus perpendicular to the main emission direction of the LEDs 28. The reflector subregions 40 preferably have the illustrated geometry of truncated pyramids. Like in the Figure 3 is shown, the reflector subregions 40 and the light sources 28 uniquely assigned to them are arranged in one or more rows. In addition, the reflector subregions 40 are identical to one another and their light exit surfaces adjoin one another without a gap so that their light exit surfaces are delimited by at least one straight line 44. Figure 3b shows in particular also a lower edge 44 of the light exit surface of the reflector row arrangement, which is to be depicted as a light-dark boundary. Fig. 4 shows in particular the focal plane 48 of the secondary optics 12, which lies in a plane with the intermediate light distribution, which results as the light exit surface of the reflectors 40.

Fig. 4 shows one of the Fig. 3 comparable item. In contrast to the subject of Figure 3 is in the Fig. 4 the primary optics array 50 constructed according to the invention from converging lenses. The converging lens subareas 50 are implemented here as subareas of a one-piece, transparent base body 52 that adjoin one another without any spacing. The one-piece base body 52 preferably consists of one of the above-mentioned materials.

Figure: 4b FIG. 8 shows a perspective view of the assembly consisting of the printed circuit board 26 and the converging lens subregions 50 and the associated LEDs 28. Figure 4a shows a section through this assembly, which runs in the direction of the row arrangement. Figure 4d FIG. 11 shows a section through this assembly, which runs transversely to the array and FIG Figure: 4c shows a plan view and a position of said sections.

A converging lens sub-area 50 is clearly assigned to each light source 28. Comparisons Figure 4c . The lens array is delimited at least on one edge at least in sections by a flat side surface 54 on which part of the beam path is reflected. This is in the Figure 4d clearly.

Alternatively, this edge 54 can also be formed by a diaphragm 56 which is brought into the beam path immediately in front of the light exit surface of the lens array. This is in the Figures 4e and 4f shown.

Figure 4e shows a primary optics array composed of converging lenses 50 additional screen 56. This covers an edge of the primary optics in order to delimit the light exit surface as sharply as possible. This diaphragm creates a particularly sharp delimitation of the light exit surface in that it shades all light that is scattered past the light exit surface. In this case, the secondary optics focus as directly as possible on the diaphragm edge. If a low beam light distribution with at least partially horizontal light-dark border is to be generated, the diaphragm edge runs along the lower edge of the light exit surface of the primary optics, with the help of which the light-dark transition of the light distribution is then formed by the secondary optics.

The intermediate light distribution is in the lens arrays in the area of the lens body. The focus of the secondary optics is in Fig. 4f at the edge of the diaphragm 54. The embodiment with the lens array is preferred.

The diaphragm can also be used in conjunction with the other configurations of primary optics presented in this application.

Like in the Figure 4 As shown, the converging lens subregions 50 as well as the light sources 28 uniquely assigned to them are arranged in one or more rows. In addition, the converging lens subareas 50 are identical to one another and their light exit surfaces adjoin one another without a gap, so that their light exit surfaces are delimited by at least one straight line 44.

Figure 4g shows an arrangement of a pair of one of several semiconductor light sources 28 in the form of an LED chip and a condensing lens subarea 50 of the base body 52 that collects light from this chip. A division of the base body 52 is denoted by T. The pitch T corresponds to the width of the individual converging lens subareas 50 and the distance between the centers of adjacent LED chips 28. An edge length of the LED chip 28 is designated by B _LED . A virtual LED chip is denoted by 28 '. The edge length of the virtual LED chip 28 'is denoted by B' _LED . An object-side focal point of the converging lens subarea 50 is denoted by F and a main point of the converging lens subarea 50 is denoted by H. The principal point H of a lens is defined as the intersection of a principal plane of the lens with the optical axis. The secondary optics 4 of the light module 1 according to the invention is preferably focused on a main point H of one of the converging lens subareas 50, preferably on the main point H of the converging lens subarea 50 located in the vicinity of an optical axis of the light module. The reference symbol f denotes the focal length of the converging lens subarea 50 and S _F a back focal length of the converging lens subarea 50. A distance between the LED chip 28 and the light entry surface of the converging lens subarea 50 is S ₁ , and a distance between the virtual chip image 28 'and the The light entry surface of the converging lens subarea 50 is denoted by S ₂ .

• 0,1 mm ≤ S₁ ≤ 2 mm
• 1 x B_LED ≤ T ≤ 4 x B_LED

The LED chip 28 lies between the converging lens subarea 50 and its object-side focal point F. The LED chip 28 is enlarged by the converging lens subarea 50 so that the (upright) virtual image 28 'of the chip (in the light exit direction in front of the object-side lens focal point F) for example is the same size as the converging lens portion 50, ie B ' _LED ≈ T. For the The following relationships apply approximately: $$\frac{{\mathrm{S.}}_{\mathrm{F.}}-{\mathrm{S.}}_1}{{\mathrm{S.}}_{\mathrm{F.}}}\approx \frac{{\mathrm{B.}}_{\mathrm{LED}}}{\mathrm{T}}\approx \frac{{\mathrm{B.}}_{\mathrm{LED}}}{\mathrm{B.}{\prime }_{\mathrm{LED}}}$$

• 0.1 mm ≤ S ₁ ≤ 2 mm
• 1 x B _LED ≤ T ≤ 4 x B _LED

The collecting lens subareas 50 of the base body 52 do not serve to generate real intermediate images of the light sources 28, but merely form an illuminated area on the light exit side 25 of the collecting lens subareas 50. The light sources 28 are thus arranged between the light entry areas of the collecting lens subareas 50 and the object-side focal points F of the collecting lens subareas 50 that the edges of the light sources 28 lie on geometric connections from the focal points F to the lens edges. The emission surfaces of the light sources 28 are arranged perpendicular to the optical axes of the converging lens subareas 50. This results in a very uniform illumination of the converging lens subareas 50, and a particularly homogeneous light distribution, the so-called intermediate light distribution, results on the light exit surfaces of the converging lens subareas 50. These intermediate light distributions are mapped by the secondary optics to generate the resulting overall light distribution of the light module on the lane in front of the vehicle. The optical axes of the individual converging lens subareas 50 of the base body 52 all run in one plane, they are preferably parallel to one another. The axis of the secondary optics is on the side that faces the main body 52 facing, parallel to the axis of at least one of the converging lens subareas 50. The LEDs are in particular arranged between their respective converging lens subarea and its paraxial focal point so that a gapless intermediate light distribution is created, which is composed of the virtual images of the light exit surfaces of the individual chips. It should be noted that the light here first emerges from the LED in air and only then strikes the associated converging lens subarea. This differs from the prior art, in which LEDs with transparent potting compounds are used, the potting possibly developing a lens effect.

Fig. 5 (not part of the invention) shows an example of a further embodiment of the primary optics array. In the case of the Fig. 5 The primary optics array consists of light guides 60 with cross-sections widening conically towards the light exit, which are oriented perpendicular to the main direction of propagation of the light in the light guides and thus perpendicular to the respective optical axis and which are rectangular, in particular square. The light exit surfaces 62 of the individual light guides 60 are lined up without gaps and delimit the luminous surface with sharp, straight edges 44, which are lower edges 44 here. One light guide 60 is assigned to each LED 28 in one unambiguous manner.

The light entry surface is preferably flat and is parallel in front of the LED chip. Like the assigned light sources, the light guides 60 are arranged in one or more rows, so that the light exit surfaces are again delimited by at least one straight line 44. The light exit surface is preferably curved in a convex manner. The light guide array is preferably one of the above mentioned materials. The light guide array is preferably manufactured as a one-piece base body which has the light guides as light-guiding partial areas.

For all three configurations of the primary optics array as an array of reflector subareas 40, converging lens subareas 50 and light guide subareas 60, the sum of the light exit areas of the respective subareas forms the closed, coherent intermediate light distribution and substitute light source.

If losses due to absorption and Fresnel reflection are neglected, the substitute light source will have luminance levels similar to that of the chips in the individual LEDs. Such a substitute light source thus also has luminance levels evenly distributed over its entire light exit area and radiation angles similar to individual LEDs. The replacement light source can thus be treated like an LED array in the following.

The light distribution formed in this way now serves as a substitute light source for a downstream secondary optics, which is a converging lens or preferably a reflector with at least partially parabolic reflection surface and which forms a low beam distribution with the aid of this substitute light source.

The alternative light source should be oriented as similarly as possible to the light-dark boundary of the low beam distribution (namely at least in sections horizontally) in order to achieve a good sharpness of the light-dark boundary (high illuminance gradient). For this reason, all reflectors in the beam path are arranged in such a way that the beam path at the respective reflectors is always in is folded as acute as possible (<90 °) and the orientation of the images of the substitute light source parallel to the cut-off line is largely retained.

The secondary optics are preferably a faceted parabolic reflector. The reflector is arranged in the beam path in such a way that the substitute light source shines into the reflector from the front, so that the beam path is deflected at an acute angle. The at least one focal point of the reflector lies on the edge of the substitute light source. To generate a low beam distribution, this is the lower edge of the substitute light source. As described, this edge can also be shaded by a screen to prevent stray light from entering the dark field of the light distribution.

If the secondary optics has several reflector facets, their focal points are again on the edge of the substitute light source, but are preferably positioned at different ends of the light source edge depending on the position of the facet:
If the light source shines into the reflector from below, the respective parabolic facets always have their focal point in the same half-space delimited by the meridional plane. If the light source shines into the reflector from above, the focal points of the parabolic facets are always on the other side of the meridional plane like the reflector facet itself.

This ensures that the images of the substitute light source always connect with the corner closest to the low-beam light-dark border and that no part of the light source images goes into the dark field of the Light distribution protrudes.

The secondary optics do not focus on the chip level of the LEDs but on the lower edge of the light exit surface of the primary optics. The light exit surface can be delimited particularly sharply if a screen is arranged along the edge of the light exit surface which shades all light that is scattered past the light exit surface.

In this case, the secondary optics focus as directly as possible on the diaphragm edge. If a low-beam light distribution with at least partially horizontal light-dark border is to be generated, the diaphragm edge runs along the lower edge of the light exit surface of the primary optics, with the help of which the light-dark transition of the light distribution is then formed by the secondary optics.

The reflector surface of the secondary optics preferably consists of several reflector facets, each of which has surfaces implemented as paraboloids of revolution. The different paraboloids have different focal points, all of which are located on the lower edge of the light exit surface of the primary optics, preferably at its edges (corners), the focal points being in the same hemisphere as the associated facet surfaces.

The axes of the paraboloids of revolution, on which the reflector facets are based, point in the direction of the low-beam light-dark boundary. In this way, the edge of the light source is mapped as a cut-off line for the light distribution.

In one embodiment, the reflector facets are designed as toric surfaces instead of paraboloids of revolution: For this purpose, the curvature of the paraboloid of revolution is increased or decreased in sections parallel to the light-dark boundary (or to sections of the light-dark boundary) through the focal point of the paraboloid that instead of the focal point there is a focal line which runs parallel to the low beam / light / dark border or to sections of the low beam / light / dark border. The scattering can also be achieved by scattering cylinder optics, which are applied to the facet surfaces and whose cylinder axis is perpendicular to the main ray and the low-beam light-dark boundary.

If an asymmetrical low-beam light-dark boundary with an increase is to be generated, this increase is generated via a reflector facet which is as close as possible to the edge of the reflector surface. Details are given below with reference to the Fig. 8 explained.

Figure 6 shows configurations of light modules 14 according to the invention which have a deflecting mirror which additionally folds the beam path. This measure serves to shorten the installation space of the light module and to create a further degree of freedom in order to be able to arrange the elements of the light module as freely as possible.

It offers structural advantages if the light source 10 radiates forwards in the direction of travel (light emission direction) and the heat is removed from the light source via a heat sink 24 to the rear: Such a light source can easily be changed from the rear of the headlight. The Ventilate the heat sink on the back of the light module more easily, which improves the cooling performance. In addition, a compact light module is obtained, the focus of which is in the vicinity of the light exit surface, which facilitates the mechanical pivoting of the light module 14.

The folding of the beam path is also favorable because the refractive power in the proposed optical system is divided into primary and secondary optics, so that secondary optics with low refractive power, i.e. with a long focal length (the focal lengths are 2-3 times larger than with single-stage systems).

The deflection mirror 64 is designed as a hyperboloid, the hyperboloid expressly also intended to include the special case of the plane mirror. The described properties of the secondary optics 12 relate in this case to the optical system 64, 12 made up of deflecting mirror 64 and secondary optics 12, which now focuses with one or more focal points on the lower edge of the substitute light source. The deflection mirror 64 generates at least one virtual intermediate image 66 of the substitute light source 68.

The substitute light source 68 lies in the object-side Petzval surface of the hyperbolic deflecting mirror, while the focal point or points of the secondary optics 12 lie in the image-side Petzval surface of the hyperboloid, i.e. the secondary optics 12 focus on its virtual image 66 instead of on the real substitute light source 68.

Fig.6a shows such a low beam module 14 with a beam path additionally folded by a deflecting mirror 64. The deflecting mirror 64 generates a virtual image 66 of the substitute light source 68. The focal points of the Secondary optics 12 lie as it is in connection with the Figure 1 was explained, preferably on the corners of the primary optics. In the case of the Figure 6a however, the secondary optics does not focus on the real primary optics, but rather on the corners of the virtual image of the primary optics serving as a substitute light source 66.

Fig.6b likewise shows a low beam module 14 with a beam path additionally folded by a deflecting mirror 64. The deflecting mirror 64 generates a virtual image 66 of the substitute light source 68. The focal points of the secondary optics 12 now lie on the lower edge 44 of the virtual image 66 of the substitute light source 68. The deflecting mirror 64 shortens the overall length and thus enables a particularly compact design of the light module 14.

für alle optischen Wege s_i gilt, welche die objektseitigen Brennpunkte 34, 36 der durch den zusätzlichen Umlenkspiegel 64 zweiteiligen Sekundäroptik mit dem gemeinsamen, im Unendlichen liegenden objektseitigen Brennpunkt verbinden. In einer Ausgestaltung weist wenigstens einer der beiden Spiegel eine oder mehrere Facetten auf.The optical system made up of deflection optics 64 and secondary optics 12 is preferably designed so that the condition ${\displaystyle {\sum }_i^n{s}_i\cdot n_i}=\mathrm{constant}$

applies to all optical paths s _i which connect the object-side focal points 34, 36 of the secondary optics, which are two-part by the additional deflecting mirror 64, with the common object-side focal point located at infinity. In one embodiment, at least one of the two mirrors has one or more facets.

erfüllt, muss nicht zwingend ein scharfes virtuelles Zwischenbild 66 liefern, da Aberrationen (Unschärfe, Verzeichnung, Öffnungsfehler) des Zwischenbildes durch die nachgeschaltete Sekundäroptik 12 wieder ausgeglichen werden können.An optical system consisting of deflecting optics 64 and secondary optics 12, which the condition ${\displaystyle {\sum }_i^n{s}_i\cdot n_i}=\mathrm{constant}$

fulfilled, does not necessarily have to deliver a sharp virtual intermediate image 66, since aberrations (blurring, distortion, aperture errors) of the intermediate image can be compensated again by the downstream secondary optics 12.

With regard to the deflection mirror 64, a distinction is made between five configurations. In a first embodiment, the deflecting mirror 64 is a plane mirror. This is in the Fig. 6 shown.

Figure 7a shows a second embodiment with a deflection mirror 64, which is concave and therefore has a collecting effect. The shape is preferably a hyperbola shape. Due to the collecting characteristic, the virtual intermediate image 66 is here an enlarged image of the substitute light source 68. The first hyperbolic focal point 70 lies on the lower edge of the real primary optics of the real substitute light source 68. The second hyperbolic focal point 72 lies on the lower edge of the virtual intermediate image 66 of the substitute light source.

Fig.7b shows a third embodiment with a deflection mirror 64, which is convex and therefore has a dispersing effect. The shape is preferably a hyperbola shape. Because of the diffusing characteristic, the virtual intermediate image 66 is a reduced image of the substitute light source 68. The first hyperbolic focal point 70 lies on the lower edge of the real primary optics of the real substitute light source 68. The second hyperbolic focal point 72 lies on the lower edge of the virtual intermediate image 66 of the substitute light source 68.

The Figure 7 shows embodiments with a hyperboloid as a deflecting mirror 64, which has an object-side focal point 70 and an image-side focal point 72 and with a preferably faceted secondary optics, which has the deflecting mirror and the further mirror 12, and which has several object-side focal points and an image-side focal point at infinity . The Focal points of this secondary optics 12 lie on the lower edge of the virtual image 66 of the substitute light source 68. In contrast to the plane mirror, this image is enlarged or reduced depending on whether the deflecting mirror 64 is a concave or a convex hyperboloid.

In a fourth embodiment, not shown, the light module has a plurality of flat deflecting mirror facets and secondary optics with a single focal point on the object side. The faceted deflecting mirror divides the beam path of the secondary optics and thus creates an optical system with several focal points, similar to a faceted parabolic reflector. The faceted deflecting mirror generates several virtual images of the substitute light source that are shifted relative to one another. The focal points of the two-part secondary optics focus on the edge of the substitute light source as described above.

In a fifth embodiment, likewise not shown, the light module has a faceted hyperboloid as a deflecting mirror with one object-side and several image-side focal points. In this case, the secondary optics should have an object-side and an image-side focus (the latter at infinity). The faceted hyperboloid generates virtual images of the light source that are shifted, enlarged (concave hyperbolic mirror) or reduced (convex hyperbolic mirror), depending on whether the hyperbolic mirror is concave (and thus enlarging) or convex (and thus reducing).

Figure 8 Figure 11 shows front views of embodiments of the Light module as presented to an observer who is in the direction of emission of the light module in front of the light module and who looks into the light module. Both in the case of the Figure 8a as well as in the case of the Figure 8b the reflector serving as secondary optics has a parabolic shape with three facets at least in a region of its reflector surface which is greater than half of its total reflective surface.

Figure 8a shows in particular an embodiment in which the facet 12.1 on the reflector edge on the right in the viewing direction generates the asymmetrical rise 18.2 of the light-dark boundary in the light distribution 16. The facet 12.1 is arranged in particular in such a way that the light source images are tilted in the direction of the rise. As a result, the facet 12.1 generates light source images with an orientation which, in the sum of the light source images, generate the desired increase in the cut-off line. That in the Figure 8a The example shown is suitable for right-hand traffic. The light source shines like the object of the Figure 8a from below into the reflector, the facet 12.1 is not on the same side of the meridional plane as the rise 18.2. The facet edge runs in sections perpendicular to the rise.

Figure 8b shows in particular an embodiment in which the facet 12.3 on the left reflector edge generates the asymmetrical increase in the light-dark boundary in the light distribution. The light source shines like the object of the Figure 8b from above into the reflector, the facet 12.3 lies on the same side of the meridional plane as the rise 18.2 itself. The facet edge runs in sections perpendicular to the rise.

Figure 9b shows a low beam distribution of an embodiment of a light module according to the invention, as it appears on a screen in front of the vehicle. The horizontal line H is level with the horizon. The vertical line V crosses the horizon in the extension of the main radiation direction of the light module. The deviations from the point HV = (0, 0) are given in degrees. Closed curves are lines of constant brightness, with the brightness increasing from line to line from outside to inside. The increase to the right of the HV = (0, 0) point shows that it is a light module for right-hand traffic.

Figure 9a illustrates how the Figure 9b Light distribution shown as an overlay of light source images 74 results. Each light source image is generated from a small part of the reflective surface of the secondary optics. The representation of the Figure 9a is purely schematic in this respect. The light source images are predominantly oriented horizontally or parallel to the cut-off line. The facet that generates the rise, on the other hand, is designed precisely in such a way that it delivers light source images whose edge lies parallel to the desired course of the rise.

The primary optics enlarge the light exit surface by a factor that corresponds roughly to the quotient of the division of the optics array and the side length of an individual chip. This follows from the equally bright substitute light source. The focal length of the secondary optics preferably corresponds to 50 times to 200 times the side length of an individual chip, in particular 80 times to 100 times the stated side length.

Claims (13)

1. Light module (14) of a motor vehicle headlamp, comprising a plurality of light-emitting diodes as light sources (28), a primary optic (30) and a secondary optic (12), the primary optic being designed to collect light emanating from the light sources and to convert it into an intermediate light distribution (68) having the form of a closed luminous surface, and wherein the secondary optic has a focal length on the object side, the primary optic and the secondary optic being arranged in such a way that the intermediate light distribution lies in the light path at the distance of this focal length in front of the secondary optic, the light module being designed to generate a low beam light distribution with a light/dark boundary, characterized in that the primary optics is a one-piece base body constructed from collecting lens sub-regions (50), and in that the chip of a light-emitting diode is located between a collecting lens sub-region (50) collecting light from this light-emitting diode and its object-side focal point (F), wherein light exit surfaces of the light sources (28) are separated from each other by distances between them and that the primary optics is arranged to distribute light emanating from the light sources in such a way that the distances in the intermediate light distribution (68) are not visible, so that a closed luminous surface is created in the intermediate light distribution (68).
2. Light module (14) according to claim 1, characterised in that the primary optics (30) has a separate optically effective partial region for each light source, each of which has a light emission surface, and wherein these light emission surfaces adjoin one another without spacing, and wherein at least two adjacent light emission surfaces thus adjoin one another, in that at least one side edge of a first of two adjacent light emission surfaces lies in line with a side edge of the second of the two adjacent light emission surfaces, so that the two aligned edges form a common straight edge (44).
3. Light module (14) according to claim 2, characterised in that each partial area is a collecting lens (50).
4. Light module (14) according to one of the preceding claims, characterised in that the light module has a diaphragm (56) which is arranged in the beam path of the light immediately behind the light exit surface in such a way that it shades part of the intermediate light distribution.
5. Light module (14) according to one of the preceding claims, characterised in that the secondary optics comprises at least one concave mirror reflector (12).
6. Light module (14) according to claim 5, characterised in that an optical surface of the secondary optics is divided into a larger partial area and a smaller partial area, the larger partial area being defined in that it has a first focal point on the object side and that the two partial areas have a common focal point at infinity on the image side.
7. Light module (14) according to claim 5, characterised in that the concave mirror reflector has a reflecting surface, the larger part of which has a parabolic shape, wherein an object-side focal point of the parabolic shape lies on the light exit surface of the primary optics.
8. Light module (14) according to claim 5, characterized in that the secondary optics consists of two mirrors which are arranged one behind the other in the beam path in such a way that they fold the beam path of the secondary optics twice at an acute angle and that the secondary optics has an object-side focal point which lies on the light exit surface of the primary optics and whose image point lies at infinity.
9. Light module (14) according to claim 8, characterized in that the first mirror (64) in the beam path in the direction of propagation of the light is a hyperboloid and the second mirror is a paraboloid (12), the object-side focus of the hyperboloid forming the object-side focus of the secondary optics and the image-side focus of the hyperboloid coinciding with the focus of the paraboloid and marking the position of a virtual intermediate image of the intermediate light distribution.
10. Light module (14) according to one of the preceding claims, characterized in that the secondary optics has several object side focal points and one or more common image side focal points or focal lines at infinity.
11. Light module (14) according to claim 8 or 9, characterized in that the first mirror (64) of the two-stage secondary optics is a hyperboloid or a plane mirror as a special case of the hyperboloid, and that the second mirror (12) is a faceted paraboloid, wherein the object-side focal point of the hyperboloid forms the object-side focal point of the secondary optics and wherein the image-side focal point of the hyperboloid marks the position of a virtual intermediate image of the intermediate light distribution and wherein the downstream parabolic facets are arranged to focus on the edge of the virtual image of the intermediate light distribution.
12. Light module (14) according to claim 8 or 9, characterized in that the first mirror (64) of the two-stage secondary optics is a faceted hyperboloid or as its special case a faceted plane mirror and that the second mirror (12) is a paraboloid, wherein the object-side focal point of the hyperboloid forms the object-side focal point of the secondary optics and wherein the image-side focal point of the hyperboloid marks the position of a virtual intermediate image of the intermediate light distribution and wherein the parabolic facets arranged downstream in the beam path focus on the edge of the virtual image of the intermediate light distribution.
13. Light module (14) according to claim 8 or 9, characterised in that the two mirrors (64, 12) have several focal points on the object side which lie on the edge of the intermediate light distribution and whose image point or image lines lie on the light-dark boundary of the light distribution at infinity, wherein the two mirror surfaces are shaped in such a way that all optical paths between the focal point on the object side and its respective image points or image lines are of equal length.

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