EP2505910B1 - Motor vehicle headlamp with a semiconductor light source - Google Patents

Description

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

Such a motor vehicle headlight is from the DE 10 2007 007 943 A1 known.

In this case, the main surface mentioned in the preamble is understood to mean an imaginary surface on which the light is refracted as on the real lens. This will be explained below with reference to FIG. 1 explained in more detail.

Such a motor vehicle headlight is known per se. In the meantime, lighting units in vehicle headlamps are increasingly being used, which mostly consist of a plurality of semiconductor light sources by means of projection or reflection optics, low beam or high beam distributions produce. Semiconductor light sources are in particular LEDs, that is light-emitting diodes (LED = light-emitting diode). In this application, arrangements of several LEDs are referred to as a semiconductor light source. For motor vehicle headlamps LEDs are usually used today with a rectangular or square light exit surface with an edge length of 0.5 mm to 2 mm, in particular with an edge length of 1 mm. In contrast to gas discharge lamps, semiconductor light sources still have comparatively low luminous fluxes and luminance, so that the low beam and high beam light distributions in the case of LED headlamps are generally formed from a plurality of light modules.

To represent a low beam function, at least two light distributions are usually combined: a basic light distribution and a low beam spot distribution. In this case, a low-beam spot light module generates the range, ie the areas directly at the cut-off line, while the basic light module illuminates the side illumination and the area immediately in front of the vehicle (vehicle apron). The light distribution of the basic light module has a largely horizontal cut-off and a wide side illumination and a soft vertical outlet close to the vehicle. Thus, the basic light distribution corresponds largely to the light distribution of a fog lamp.

Today, different types of LED basic light modules are known. As a rule, reflection and projection systems are used, wherein the projection systems have at least one light source with at least one primary optics, which generate an intermediate image in the focal plane of at least one projection lens. Mostly the intermediate picture is over an aperture in the Focal plane of the projection lens limited, in order to obtain in this way a particularly sharp cut-off.

Furthermore, reflective basic light modules are known in which the light beam of the LED light source is formed by a freely shaped, usually faceted reflector surface in the desired manner.

The disadvantage is that both reflectors and projectors are relatively large in size. In particular, reflection systems must be made very large in order to obtain good efficiency and acceptable ranges and / or illuminances. In projection systems that provide a 2-step image due to the use of an intermediate image, the resulting large length is often problematic.

Semiconductor light sources are typically half space radiators. Due to the typical radiation characteristics in the half space as well as favored by the sharp boundary of the semiconductor light source (by the just bordered LED chips), would also offer direct imaging (ie without forming an intermediate image single-stage imaging) projection systems in which the light from the semiconductor light source through an astigmatic lens is projected directly onto the road surface: the semiconductor light source lies directly in the focal plane of the astigmatic lens, whereby space and costs for primary optics and intermediate image plane can be saved.

In addition to the lower achievable illuminance is disadvantageous here that after elimination of the primary optics now the projection lens must form the entire light distribution. This results in multiple restrictions and problems.

In particular, the following requirements are to be met: High illuminance levels at the cut-off line should be achieved, and at the same time the illuminance should be smooth and uniform in the direction of the vehicle apron. It should be achieved high efficiency and at the same time a long range and high illuminance. The light exit surface should be kept small.

Against this background, the object of the invention is to provide a motor vehicle headlight, which is characterized by an efficient, compact light module, which can produce low-beam light distributions by imaging a semiconductor light source, in particular a basic light or fog light distribution. In this case, the projection system according to the invention is intended to ensure high illuminance levels directly at the cut-off line and at the same time provide far-reaching light distributions, which evenly spread to lower illuminance levels at lateral and lower edges of the light distribution, so that a homogeneous illumination of the vehicle apron is ensured. For the overall system, the highest possible optical efficiency should be sought.

This object is achieved with a motor vehicle headlight having the features of claim 1.

The inclination of the main surface is preferably 8 ° to 20 °. The strong inclination results in different lens zones with different magnifications. The lens zones closest to the light source produce large images of the light source, far away lens zones produce small pictures. The large images are preferably used for the areas of light distribution in which large dimensions and small illuminance levels are required, for example in the vehicle apron. With closely spaced lens zones, a large amount of luminous flux can be collected, thus achieving good optical efficiency. Small light source images from widely spaced lens zones are well suited for generating coverage directly at the cut-off line - with lower optical efficiency.

It is also preferable that the material thickness of the first projection lens is maximum in a central region of the lens and decreases towards the edges of the first projection lens.

Furthermore, it is preferred that the first projection lens is realized as a concave-convex lens having a concave light entry surface and a convex light exit surface.

A further preferred embodiment is characterized in that the first projection lens has a bi-convex cross-section in a direction parallel to the horizon and a concave-convex cross-section in a vertical direction perpendicular to the horizon.

It is also preferable that the distance of the semiconductor light source from the first projection lens of Focal length of the first projection lens in the direction perpendicular to the horizontal vertical direction corresponds.

It is also preferred that the motor vehicle headlight has a diaphragm arranged directly on the semiconductor light source with a diaphragm edge which sharply delimits a light bundle emanating from the semiconductor light source.

It is further preferred that the semiconductor light source has a plurality of light-emitting semiconductor chips.

A further preferred embodiment is characterized in that the plurality of semiconductor chips can be controlled independently of one another.

drawings

Figur 1

eine Schnittdarstellung eines Ausführungsbeispiels eines erfindungsgemäßen Kraftfahrzeugscheinwerfers zusammen mit einer Lichtverteilung;

Figur 2

eine perspektivische Darstellung einer Anordnung einer Projektionslinse und einer Halbleiterlichtquelle des Scheinwerfers aus der Figur 1;

Figur 3

eine Vorderansicht des Gegenstands der Figur 2 mit verschiedenen Schnittebenen;

Figur 4

einen Vertikalschnitt des Gegenstands der Figur 2;

Figur 5

einen Horizontalschnitt des Gegenstands der Figur 2;

Figur 6

einen Vertikalschnitt einer Anordnung einer Halbleiterlichtquelle und einer Projektionslinse eines Ausführungsbeispiels der Erfindung zusammen mit einer resultierenden Lichtverteilung;

Figur 7

einen Vertikalschnitt einer Anordnung einer Halbleiterlichtquelle und einer Projektionslinse eines nicht erfindungsgemäßen Ausführungsbeispiels zusammen mit einer resultierenden Lichtverteilung;

Figur 8

eine Ausgestaltung des Gegenstands der Figur 7;

Figur 9

einen Vertikalschnitt einer Anordnung einer Halbleiterlichtquelle, einer Projektionslinse und eines Zusatzreflektors, eines nicht erfindungsgemäßen Beispiels;

Figur 10

eine Halbleiterlichtquelle mit einer Zusatzblende;

Figur 11

einen Vertikalschnitt durch Elemente eines nicht erfindungsgemäßen Ausführungsbeispiels eines Kraftfahrzeugscheinwerfers; und

Figur 12

eine Ausgestaltung des Ausführungsbeispiels aus der Figur 11.

Embodiments of the invention are illustrated in the drawings and are explained in more detail in the following description. The same reference numerals designate the same or identical elements, at least in their main function. This show, each in a schematic form, wherein the Fig. 7-9 and 11, 12 do not form part of the invention:

FIG. 1

a sectional view of an embodiment of a motor vehicle headlight according to the invention together with a light distribution;

FIG. 2

a perspective view of an arrangement of a projection lens and a semiconductor light source of the headlamp from the FIG. 1 ;

FIG. 3

a front view of the object of FIG. 2 with different cutting planes;

FIG. 4

a vertical section of the article of FIG. 2 ;

FIG. 5

a horizontal section of the article of FIG. 2 ;

FIG. 6

a vertical section of an arrangement of a semiconductor light source and a projection lens of an embodiment of the invention, together with a resulting light distribution;

FIG. 7

a vertical section of an arrangement of a semiconductor light source and a projection lens of a non-inventive embodiment, together with a resulting light distribution;

FIG. 8

an embodiment of the subject matter of FIG. 7 ;

FIG. 9

a vertical section of an arrangement of a semiconductor light source, a projection lens and an additional reflector, a non-inventive example;

FIG. 10

a semiconductor light source with an additional aperture;

FIG. 11

a vertical section through elements of a non-inventive embodiment of a motor vehicle headlight; and

FIG. 12

an embodiment of the embodiment of the FIG. 11 ,

In detail, the shows FIG. 1a a motor vehicle headlight 10 having at least one semiconductor light source 12 and an optical system 14 influencing a propagation of light of the semiconductor light source 12 within the headlight 10. The optical system 14 has a first projection lens 16 with a main surface 18. The semiconductor light source 12 is in one Focusing the first projection lens 16 is arranged. The headlamp 10 is adapted to the in FIG. 1b to produce shown light distribution 20.

The light distribution 20 is characterized by a bright area 22 and a dark area 24, which is separated from the bright area 22 by a cut-off line 26. The horizontally extending line H represents the position of the horizon in a proper use of the motor vehicle headlight 10 in a motor vehicle. The line V corresponds to a vertical, which is arranged at a right angle to the horizontal H when used as intended. The bright area 22 of the light distribution 20 is just below the horizon H and has a substantially greater extent in the horizontal direction than in the vertical direction. Such a light distribution is typical for low beam and / or basic light beam distribution.

In the embodiment shown in the FIG. 1 is shown, the light distribution 20 is generated by direct imaging of the light exit surface of the semiconductor light source 12, wherein the first projection lens 16 projects an image of the semiconductor light source 12 directly into the far ahead of the motor vehicle headlight 10 apron. In one refinement, the motor vehicle headlight 10 has further semiconductor light sources and optionally further optics 14 which superimpose additional partial light light distributions on the basic light light distribution 20, for example spot light distributions, in order to generate a total light distribution adapted to the respective traffic conditions. An optical axis 28 of the motor vehicle extends between the semiconductor light source 12 and a central point 30 of the cut-off line 26. The central Therefore, point 30 is preferably at the crossing point of the vertical V and the horizontal H or just below it.

The motor vehicle headlight 10 is characterized in that the first projection lens 16 is arranged inclined relative to the optical axis 28 so that points 32 of the main surface 18 of the first projection lens 16 lie in a radial distance r from the optical axis 28 above the optical axis 28 Direction of the optical axis 28 have an axial distance d_32 to the semiconductor light source 12, which differs from a distance d_34 that a lying at the same radial distance r from the optical axis 28 below the optical axis 28 point 34 of the main surface 18 of the first projection lens sixteenth having.

The main surface is a mental construction produced in the following manner. Consider a beam 50, 52 incident on a light entry surface 52 of the first projection lens 16 and the respectively associated beam 56, 58 emerging from the light exit surface 54 of the first projection lens 16. The direction of the exiting beam 56, 58 differs on the entrance and upon the exit from the first projection lens 16, refraction changes direction from the direction of the exiting beam 56, 58. For the conceptual design of the main surface 18, this twofold change in direction is thought to be replaced by a single change of direction occurring within the lens at a point where the incoming beam 50, 52 and the associated exiting beam 56, 58 would intersect if no change in direction took place at the light entry surface 48 and at the light exit surface 54. The set of all possible intersections that are According to the main surface 18 of the first projection lens 16 relative to the optical axis 28 is arranged inclined so that the axial distances d_32 and d_34 of the same radial distance r above and below the optical axis 28 lying points 32 and 34 of the main surface 18 substantially different from each other.

In the embodiment, in the FIG. 1 are shown, at a radial distance r from the optical axis 28 above the optical axis 28 lying points 32 of the main surface 18 a smaller axial distance d_32 to the semiconductor light source 12 than at the same radial distance r from the optical axis 28 below the optical Axis 28 lying points 34 of the main surface 18, which have an axial distance d_34 to the light source 12. In this case, axial distances extend parallel to the optical axis 28 and radial distances extend at right angles to the optical axis 28th

The semiconductor light source 12 consists of one or more semiconductor chips, which can be switched on and off together or separately. In particular, embodiments with five semiconductor chips are presented in this application. However, it should be understood that the number of semiconductor chips may also be less than or greater than five, and that the semiconductor chips need not only be arranged in a single row, as in embodiments discussed herein. Rather, the chips can also be mounted on the circuit carrier 36 in a matrix-like manner in rows and columns or in another, preferably regular arrangement.

The circuit carrier 36 is preferably a rigid or flexible printed circuit board on which the semiconductor chips of the semiconductor light source 12 are attached and through which the semiconductor chips are electrically contacted. In addition, the circuit carrier 36 is adapted to receive the resulting during operation of the semiconductor light source 12 electrical heat loss and forward to a thermally coupled to the circuit carrier 36 heat sink 38, which emits the heat loss to the ambient air.

According to the invention, the mounting of the semiconductor light source 12 in the headlight 10 takes place relative to the first projection lens 16 such that the light exit surface of the semiconductor light source 12 lies in a Petzval surface 40 of the first projection lens 16. The Petzval area 40 is the area of all points that are sharply imaged by the projection lens 16. This means in particular that the semiconductor light source 12 is arranged in a focal point of the first projection lens 16. The structural elements described so far form a light module 42. This light module 42 is alone or together with other light modules of the headlamp 10 in a housing 44. The housing 44 has a in the FIG. 1 to the right light exit opening, which is covered by a transparent cover 46.

FIG. 2 shows a perspective view of a heat sink 38 with mounted circuit substrate 36 and mounted thereon a semiconductor light source 12, which consists of a plurality of horizontally juxtaposed semiconductor chips, together with a first projection lens 16. Die FIG. 2 serves in particular to illustrate the subject matter of FIGS. 3 to 5 ,

The FIG. 3 shows a front view of the subject of FIG. 2 , ie a view of the subject of the FIG. 2 as it results from a viewing direction opposite to the light emission direction. From this line of sight, one sees the light exit surface 54 of the first projection lens 16 in front of the heat sink 38 FIG. 3 shows in particular a preferred embodiment, which is characterized in that the first projection lens 16 in the direction of a horizontal has a greater extent than in the direction of a vertical. The direction of the vertical of the sectional plane IV-IV and the direction of the horizontal of the sectional plane VV corresponds in the FIG. 3 ,

FIG. 4 shows the subject of the FIG. 3 in vertical section IV-IV, and the FIG. 5 shows the subject of the FIG. 3 in horizontal section VV. In particular, the vertical section shows a profile of the first projection lens 16, which is inclined about an axis parallel to the horizon H and perpendicular to the optical axis 28. In the case of a directly imaging projection lens 16, this means that the main surface of the first projection lens 16 above the optical axis 28 is significantly closer to the light source 12 than below the optical axis 28. In the case of a lens mold as shown in FIG FIG. 4 is shown, this also means that the lens edge, in particular the edge of the light source 12 facing lens surface (light entrance surface) 48 above the optical axis 28 is significantly closer to the light source 12 than below the optical axis 28. The profile of the vertical cross section through the In this case, the first projection lens 16 corresponds to the profile of a converging lens, since the material thickness of the first projection lens 16 in the region of the optical axis 28 is greatest and falls toward the edge of the lens.

The FIGS. 4 and 5 show the respective components shown there on the same scale. A comparison of FIGS. 4 and 5 shows therefore in particular that the lens cross sections in the horizontal section of FIG. 5 and the vertical section of the FIG. 4 have different curvatures and thus different focal lengths. The radii of curvature in horizontal section are much larger than the radii of curvature in vertical section. As a result, the first projection lens 16 generates a highly divergent light beam in the horizontal sectional plane, resulting in the FIG. 5 is represented by the wide opening angle 59. In contrast, the smaller radius of curvature in the vertical section means that the light is concentrated much more strongly in the vertical direction. Overall, this results in an astigmatic image, so that the light source 12 is shown as a vertically narrow, horizontal but very wide light distribution 20, as they are qualitatively in the FIG. 1b is shown.

In a vertical section, the first projection lens 16 preferably has a concave light entrance surface 48 and a convex light exit surface 54. In horizontal section, the light entry surface 48 may also deviate from the illustration of FIG FIG. 5 , Be convex, so that there is a biconvex cross-section.

The FIG. 6 shows one of the FIG. 4 comparable vertical section together with individual elements of a resulting light distribution 20. Die FIG. 6 refers in particular to a direct imaging system with a five chips and thus five light emitting surfaces having semiconductor light source 12, which is imaged by a projection lens 16 in a light distribution 20 becomes. The light distribution 20 is thereby, as it also in connection with the FIG. 1b has already been explained, in an HV plane in front of the motor vehicle headlamp, wherein the horizontal axis H with the optical axis 28 and the vertical axis V forms a right-handed coordination system.

To explain the technical effects of the tilted arrangement, are in the FIG. 6 considered three different lens zones LZ1, LZ2 and LZ3. It is understood that this is a purely conceptual construction and that the lens could be divided into other lens zones in any manner. The lens zones can each be regarded as subregions of the main surface 18. A first lens zone LZ1 is arranged above the optical axis 28, while a second lens zone LZ2 is arranged in the region of the optical axis 28 and a third lens zone LZ3 below the optical axis 28.

Due to the tilted arrangement of the projection lens 16, the upper lens zone LZ1 has a first distance S1 from the semiconductor light source 12 which is smaller than a distance S2 of the second lens zone LZ2 from the semiconductor light source 12, this distance S2 being smaller than a distance S3 the third lens zone LZ3 from the semiconductor light source 12. The different distances S1 less than S2 smaller S3 (S1 <S2 <S3) are due to the described inclination of the main surface 18 of the first projection lens 16.

Due to the differing distances S1, S2 and S3, different magnifications result for the different lens zones LZ1, LZ2 and LZ3. The lens zone LZ1, which has the five light exit surfaces Next to the semiconductor light source 12 generates large images B_LZ1 the individual light exit surfaces of the semiconductor light source 12 in the light distribution 20. The lens zone LZ2 further away from the semiconductor light source 12 generates images B_LZ2 of the light exit surfaces semiconductor chips of the semiconductor light source 12, which are smaller than the images B LZ1. The lens zone LZ3 farthest from the semiconductor light source 12 generates the smallest images B_LZ3 of the five light exit surfaces of the semiconductor chips of the semiconductor light source 12.

The large images B_LZ1 are preferably used for the areas of light distribution in which large expansions and small illuminance levels are required, for example in the motor vehicle apron located close to the motor vehicle. With the associated lens zone LZ1 lying comparatively close to the semiconductor light source 12, a large amount of luminous flux can be absorbed and thus good optical efficiency can be achieved.

On the other hand, smaller light source images, for example the light source images B_LZ3 from lens zones LZ3 located farther away from the semiconductor light source 12, are well suited for illumination further ahead of the vehicle, which are just below the cut-off line 26 in the light distribution 20. With these areas, the largest range is reached directly at the cut-off line 26, the larger range is purchased at a comparatively poor efficiency.

In reality, the different lens zones merge into each other, so that their images in The light distribution 20 also overlap continuously from outside to inside or from inside to outside merging into each other. It is true that the largest chip images with the lowest illuminance come from the lens zone which is closest to the semiconductor light source 12, while the smallest chip images with the greatest illuminance come from the lens zone with the greatest distance to the semiconductor light source 12.

According to the invention, the projection lens 16 is positioned relative to the semiconductor light source 12 such that the semiconductor light source 12 lies in the Petzval surface of the vertical cross section of the projection lens 16, in which the optical axis 28 extends. This means that the light-dark boundary 26 is generated by the sharp image of the lower edge of the semiconductor light source 12. However, only individual areas from the vertical sections of the projection lens 16 contribute to the sharp imaging of the lower edge of the light source. The remaining edges of the light distribution 20 appear blurred, since the different lens zones each provide images of very different sizes. Since the horizontal section due to its opposite the vertical section other radius of curvature provides no sharp image, a horizontally wide-blazed light band is generated with low vertical extent, which is substantially less than the horizontal extent. This results qualitatively in the FIG. 1b illustrated form of light distribution 20th

The projection lens 16 has, in one embodiment, at least one lens surface, be it the light entry surface 48 and / or the light exit surface 54, at least partially scattering structures, the For example, realized by a wavy shape of the surface. By means of such scattering microstructures, a slight blurring of the light-dark boundary can be achieved in a targeted manner, which contributes to the homogenization of the light distribution and, moreover, helps to eliminate chromatic aberrations. Vertically arranged cylindrical microlenses scatter horizontally and thus have no decisive influence on the illuminance gradient, that is to say on the maximum range of the headlamp 10.

The FIG. 7 shows an embodiment in which the optical system 14 in addition to the first projection lens 16 has a converging lens 60 which is disposed between the semiconductor light source 12 and the first projection lens 16. A part of the light emitted from the semiconductor light source 12 into the half-space passes through the condenser lens 60. This light is in the FIG. 7 represented by the opening angle 64. The portion 66 of the light emanating from the semiconductor light source 12, which passes through only the first projection lens 16 and does not pass through the condenser lens 60, generates small high-intensity light source images B_66, which are used to form the cut-off line 26.

The additional converging lens 60 directs additional beams from the opening angle 64 onto the first projection lens 16 and thus increases the efficiency of the optical system. In this case, the quotient of the light emitted by the light source 12 in the denominator and of the light impinging in the light distribution 20 in the meter is understood here to be an efficiency or an efficiency of the optical system. The light 68, which is both the additional converging lens 60 and the first projection lens 16 has passed, appears to come from above the semiconductor light source 12. This means that the additional converging lens 60 generates virtual, enlarged images of the semiconductor light source 12, as shown as images B_68 in the light distribution 20 as shown in FIG FIG. 7 are shown. In the FIG. 7 this virtual extension is represented by a virtual image 62 of the semiconductor light source 12 lying above the semiconductor light source 12.

In the embodiment, in the FIG. 7 is shown, the additional converging lens 60 is inclined upward to the semiconductor light source 12, while the first projection lens 16 is inclined upward from the first semiconductor light source 12 away. It is essential in any case that at least one of the two lenses 16, 60 has a defined according to the characterizing features of claim 1 inclination. It is this tendency that is responsible for the different magnifications. On the other hand, whether a larger magnification above the optical axis and a smaller magnification below the optical axis is generated, or whether a smaller magnification above the optical axis and a larger magnification below the optical axis is generated is of secondary importance.

FIG. 8 shows a further embodiment, in which the additional converging lens is realized as a Fresnel lens with Fresnel zones 66. In such a Fresnel lens 60, the light beams are deflected by a plurality of discrete Fresnel lens zones 66. The individual Fresnel lens zones 66 can be degenerated into prism wedges.

The FIG. 9 shows an embodiment in which the optical system 14 in addition to the first projection lens 16 has an additional reflector 68 which is disposed between the semiconductor light source 12 and the first projection lens 16. The additional reflector 68 is set up by its arrangement and its shape to direct light emanating from the semiconductor light source 12 through reflections occurring on at least one optical surface of the additional reflector 68 onto the light entrance surface 48 of the first projection lens 16 such that this light emerges next to the semiconductor light source 12, it appears that the luminous area of the semiconductor light source 12 is virtually widened in the vertical direction and / or in the horizontal direction. In the FIG. 9 this virtual extension is represented by a virtual image 62 of the semiconductor light source 12 lying above the semiconductor light source 12. The additional reflector 68 has, in particular, a reflection surface arranged at an angle to the optical axis 28, so that light of the semiconductor light source 12 falling thereon is directed onto the light entry surface 48 of the first projection lens 16. The reflection surface can optionally be curved, in particular concavely arched.

The additional reflector 68 is preferably arranged on at least one side edge of the semiconductor light source 12 such that a part of the light emitted by the semiconductor light source 12 falls on the additional reflector 68. This generates virtual images of the semiconductor light source 12 in the Petzval plane of the projection lens 16. As a result, the light exit surface of the semiconductor light source 12 is virtually enlarged. The reflected from the reflection surface of the additional reflector 68 rays appear from areas next to the Light exit surfaces of the chips of the semiconductor light source 12 to come and thus extend the images of the light exit surfaces of the chips of the semiconductor light source 12 in the resulting on the roadway light distribution 20 in front of the vehicle to the side or down. As a result, a soft outlet of the light distribution is achieved. A soft spout is understood here to mean a flat intensity gradient. As a result of the additional reflector 68 capturing light which is emitted by the semiconductor light source 12 at an opening angle 64 which lies next to the light entry surface 48 of the first projection lens 16, the additional reflector 68 captures a luminous flux which would otherwise not strike the first projection lens 16 , The additional reflector 68 thus increases the total amount of light occurring on the light entry surface 48 of the first projection lens 16 and thus increases the optical efficiency.
When the auxiliary reflector 68 is placed on the upper edge of the semiconductor light source 12, the light distribution 20 is extended downward in the direction of the vehicle apron, which is closer to the vehicle. If additional reflectors 68 are placed on the side edges of the semiconductor light source 12, the light distribution can then be expanded toward the sides with the aid of the additionally reflected light, thus improving the side illumination. As has already been explained in connection with the additional converging lens 60, here too the part of the light which only passes through the first projection lens 16 generates small light source images with high illuminance, which can be used for the formation of the cut-off line. The part of the light, which is directed by the additional reflector 68 to the projection lens 16, contributes to improved illumination of the great light source imagery, as in the FIG. 7 are denoted by the reference B_68.

The reflection surface of the additional reflector 68 is realized in a preferred embodiment as a metallic coating of a forming and optionally with a painted to smooth roughness structure of the additional reflector 68. Alternatively, a reflective surface of the additional reflector 16 is realized as a white or diffusely reflecting surface. A white and / or diffuse reflective surface can be achieved, for example, by the reflective surface of the auxiliary reflector 68 comprising a layer containing titanium dioxide, zinc oxide, zinc sulfide, calcium carbonate, lead carbonate, barium sulfate or other white pigments.

The additional reflector 68 may also be embodied as a reflector utilizing the effect of internal total reflection at an interface of a transparent solid and consisting, for example, of glass, PMMA (polymethyl methacrylate) or PC (polycarbonate). In this case, the reflection surface is formed by boundary surfaces of one or more deflection prisms, wherein such a deflection prism each having an optically active surface in the form of a refractive light entrance surface, a refractive light exit surface and at least one totally reflecting surface. All optically effective, that is to say the light direction changing surfaces can be convex or concave in this case. The additional reflector may have, at least in part, scattering, for example wavy, structures. This applies both to a reflector in which an intransparent structure is coated with a reflective layer, as well as to designs that have the effect of total internal reflection use. In the case of a transparent solid using internal total reflections, the scattering structures can also be located on refracting light entry and exit surfaces.

FIG. 9b shows an auxiliary reflector 68, which consists of a reflective coated and non-transparent structure. The FIG. 9c shows the alternative of a TIR additional reflector 68 (TIR = Total Internal Reflection). Both the FIG. 9b as well as the FIG. 9c illustrate through the illustrated beam paths beyond the formation of the virtual images 62 of the semiconductor light source 12, which apparently increase the light exit surface of the semiconductor light source 12.

The FIG. 10 shows a heat sink 38 with mounted thereon a circuit substrate 36, on which five LED semiconductor chips are arranged, which constitute a semiconductor light source 12. Instead of five semiconductor chips, the semiconductor light source 12 may also have a larger or smaller number n of semiconductor chips. Preferably, the n semiconductor chips can be switched on and off independently of each other. The object of FIG. 10 is characterized by an aperture 70 arranged directly on the semiconductor light source 12, which sharply delimits a light bundle emanating from LED chips 72 of the semiconductor light source 12. The projection lens 16 images the semiconductor light source 12 with the aperture edge delimiting the light exit surface of the semiconductor light source 12 such that the light-dark boundary 26 results as an image of the diaphragm edge. The image of this diaphragm edge creates a sharp cut-off line 26 in the light distribution 20 of a light module associated with the object of FIG. 10 Is provided. By the Particularly high illuminance or luminance gradient, which can be achieved with such a diaphragm 70, a higher range of the motor vehicle headlight 10 can be achieved.

FIG. 11 FIG. 12 shows an exemplary embodiment that has a light module 42, a diaphragm 74 and a second projection lens 76. The light module 42 corresponds to one of the embodiments described and explained up to here. Such a light module 42 has, in particular, a semiconductor light source 12 and an optical system 14 influencing the propagation direction of light of the semiconductor light source 12, which optical system has a first projection lens 16 with a main surface. The semiconductor light source 12 is disposed at a focal point of the first projection lens 16. The light module 42 is configured to produce a light distribution 20 having a bright area 22 and a dark area 24 separated from the bright area 22 by a horizontal cut-off line 26, and has an optical axis 28 which is a central point 30 of the cut-off line 26 connects to the semiconductor light source 12. The light module 42 is distinguished by the fact that the first projection lens 16 is arranged inclined relative to the optical axis 28 so that points 32 of the main surface 18 of the first projection lens 16 lie in a radial distance r from the optical axis 28 above the optical axis 28 Direction of the optical axis 28 have an axial distance d_32 to the semiconductor light source 12, which differs from an axial distance, the lying at the same radial distance r from the optical axis 28 below the optical axis 28 point 34 of the main surface 18 of the first projection lens sixteenth having.

An embodiment of such a light module 42 is described with reference to FIGS FIG. 1 has been described in detail above. That in the FIG. 11 illustrated embodiment differs from such a light module 42 by a second projection lens 76 in addition to the first projection lens 16 in the light path behind the first projection lens 16 arranged second projection lens 76. In this case, the embodiment shown in the FIG. 11 is configured to focus light emanating from the semiconductor light source 12 with the first projection lens 16 in a region which is at a distance of a focal length f of the second projection lens 76 from the second projection lens 76 between the first projection lens 16 and the second projection lens 76 ,

The embodiment that is in the FIG. 11 is further configured to generate the light distribution projected onto the street as an image of an intermediate image mediated by the second projection lens 76, which image is formed from the light bundled in said area. The intermediate image is doing with one of the reference to the FIGS. 1 to 10 explained embodiments of a light module 42 generates. The intermediate image is additionally delimited by an aperture 74 introduced into the intermediate image plane, that is to say into the Petzval surface of the second projection lens 76, in order to achieve a particularly sharp cut-off line 26. The sharp cut-off line 26 is achieved in this case by the image of the intermediate image delimiting diaphragm edge.

Since the second projection lens 76 causes image reversal, at the areas below the optical axis 28 In the intermediate image plane in regions of the light distribution 20 lying above the optical axis 28, this must be described with reference to FIGS FIGS. 1 to 10 explained projection system rotated 180 ° about the optical axis 28 around to compensate for the image reversal. In other words, with reference to the FIGS. 1 to 10 explained light module 42 must be rotated by 180 ° about the optical axis, so that in the FIG. 1b shown light distribution 20 with a lying below the horizon H bright area 22 results. The with the objects of the FIGS. 1 to 10 generated light distribution is thus different than in the direct imaging systems of FIGS. 1 to 10 not in the distance on the road, but generated in a nearby intermediate image plane. The second projection lens 76 focuses on the light distribution in the intermediate image plane 78 and images it with image reversal onto the road. With the edge of the aperture 74 projecting into the light distribution in the intermediate image plane, the light distribution in the intermediate image plane 78 is limited in order to achieve a sharper cut-off line.

In the FIG. 12 This panel 74 is realized as a mirror panel having a reflective surface 80. The aperture 74 with the reflective surface 80 is arranged so that the subject of the FIG. 11 on the first projection lens 16 side facing the aperture 74 falling light in the subject of FIG. 12 incident on the reflective surface 80 and is additionally directed by this on the light entry surface of the second projection lens 76. The one of the reflective surface 80 having aperture 74 from the Fig. 12 can therefore also be referred to as a mirror or mirror aperture. The second projection lens 76 facing the front edge of the aperture 74th lies in the Petzval area of the second projection lens or follows the course of the Petzval area of the second projection lens 76. Therefore, this mirror leading edge is sharply imaged by the second projection lens 76. Rays that fall on the specularly reflective surface 80, in contrast to the simple aperture 74 of the FIG. 11 not absorbed, but deflected to the projection lens 76 out. In this way, the efficiency is further improved. The reflected rays are directed by the second projection lens 76 into an area below the cut-off line 26, where they amplify the light intensity. The leading edge of the mirror aperture 74 may be contoured to create a contoured cut-off line. In this case, the front mirror contour limits the light distribution in the intermediate image plane 78 so that a sharp cut-off line 26 is created.

For all embodiments shown in this application, the first projection lens 16 and / or the condenser lens 60 and / or the second projection lens 76 and / or the reflector 68 on an optically active surface, be it a light entrance surface and / or a light exit surface of a lens or a reflection surface of the reflector, light in different directions may have scattering structures. It is preferred that the scattering structures give the optically active surface a wavy shape. It is particularly preferred that the scattering structures have a shape of vertically arranged cylinder sections.

Claims (7)

1. Motor vehicle headlamp (10) having at least one semiconductor light source (12) and an optical system (14) which influences a propagation direction of the light within the headlamp (10), characterized in that the optical system (14) has a first projection lens (16) which has a main surface (18) and a light entry surface (48), the semiconductor light source (12) being arranged in a focal point of the first projection lens (16) and the headlamp (10) being adapted to produce a light distribution (20) having a bright region (22) and a dark region (24) separated from the bright region (22) by an at least partially horizontal cut-off (26), and having an optical axis (28) connecting a central point (30) of the cut-off (26) to the semiconductor light source (12), the first projection lens (16) being arranged to be inclined relative to the optical axis (28) such that points (32) of the main surface (18) of the first projection lens (16) lying at a radial distance (r) from the optical axis (28) above the optical axis (28) have, in the direction of the optical axis (28), a smaller axial distance (d_32) from the semiconductor light source (12) than points (34) of the main surface (18) of the first projection lens (16) lying at the same radial distance (y) from the optical axis (28) below the optical axis (28) have, the first projection lens (16) being adapted to direct light of the semiconductor light source (12) incident on the light entry surface (48) directly into the light distribution (20), in that a course of the focal length of the first projection lens (16) in a plane parallel to the horizon deviates from a course of the focal length of the first projection lens in a vertical plane perpendicular to the horizon, and in that the light-emitting surface of the semiconductor light source lies in a Petzval surface of the vertical cross-section of the projection lens (16) in which the optical axis (28) also extends, the Petzval surface (40) being the surface of all points which are sharply imaged by the projection lens (16).
2. Motor vehicle headlamp (10) according to claim 1, characterized in that the material thickness of the first projection lens (16) is maximum in a central region of the first projection lens (16) and decreases towards the edges of the first projection lens (16).
3. Motor vehicle headlamp (10) according to one of the preceding claims, characterized in that the first projection lens (16) is realized as a concave-convex lens with a concave light entry surface (48) and a convex light exit surface (54).
4. Motor vehicle headlamp (10) according to one of the preceding claims, characterized in that the first projection lens (16) has a biconvex cross-section in a direction parallel to the horizon and a concave-convex cross-section in a vertical direction perpendicular to the horizon.
5. Motor vehicle headlamp (10) according to one of the preceding claims, characterized in that the motor vehicle headlamp (10) has a diaphragm (70) which is arranged directly on the semiconductor light source (12) and has a diaphragm edge which sharply delimits a light beam starting from the semiconductor light source (12).
6. Motor vehicle headlamp (10) according to one of the preceding claims, characterized in that the semiconductor light source (12) has several of light-emitting semiconductor chips.
7. Motor vehicle headlamp (10) according to Claim 6, characterized in that the several semiconductor chips can be controlled independently of one another.

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