EP2420728B1 - Projection headlamp with targeted weakened light intensity gradients at the light-dark border - Google Patents

Description

The present invention relates to a projection headlight for a motor vehicle according to the preamble of claim 1. Such a motor vehicle headlight is known from JP 63 157 102 U known.

A projection headlamp generally comprises at least one light source, an optical element collecting light of the light source, a diaphragm with a diaphragm edge, and imaging optics. The optical element is set up and arranged to direct collected light onto the diaphragm edge, so that a first light distribution bounded by the diaphragm edge adjusts at the diaphragm edge, which is imaged by the imaging optical system as a second light distribution in an advance field of the headlight. The aperture edge in the second light distribution as a light-dark boundary between a shown comparatively lighter and a comparatively darker area.

The light intensity gradient occurring when crossing the cut-off line is an important parameter in the design and construction of automotive headlamps. A high value of the light intensity gradient is perceived as a high-contrast and thus sharp cut-off line. On the one hand there are legal minimum requirements for the sharpness of the cut-off line, which must be complied with. On the other hand, a blurred chiaroscuro limit is more pleasant for the driver. A less contrasty transition is less restless than a high-contrast transition, especially in the case of rapid vertical movements of the cut-off line, as they occur on bumpy roads. The less contrasting transition is therefore less tiring.

The object of the invention is a further improvement of visual comfort and driving safety.

This object is achieved with the features of claim 1. The projection headlamp according to the invention is also distinguished by the fact that the diaphragm has projections and / or half-open incisions in the diaphragm edge and / or that the diaphragm has a closed edge limited first recesses in the diaphragm, which are arranged at a distance from the diaphragm edge, the is less than one fifth of the width of the aperture.

Normally, the aperture edge is sharply imaged as a light-dark boundary in the second light distribution in the run-up to the headlamp. For this purpose, the diaphragm edge is usually arranged so that it is close to the focal point of the imaging optics. In addition, the aperture edge separates sharply between a shadowed from the aperture and a not shaded by the aperture and thus illuminated area in the second light distribution.

By the invention, this sharp separation is attenuated and thus blurred. Each projection shadows light that would contribute to illuminating the bright area below the cut-off line in a conventional aperture. Each incision and recess, on the other hand, allows light to pass which would be shaded in a conventional aperture. In other words, in comparison with a conventional aperture, the intensity in the inherently bright area in the middle reduced and increased in average per se dark area.

At the same time the projections protrude beyond a middle course of the diaphragm edge, while the recesses and recesses remain behind this central course. With regard to their position at the focal point of the imaging optics, the position of the projections, cuts and recesses inevitably deviates from the position of the middle course of the diaphragm edge.

Assuming that the mean profile of the diaphragm edge is sharply imaged because of its proximity to the focal point of the imaging optics, it follows from the different position of the projections, notches and recesses that they are less sharply imaged. As a result, this results in a second light distribution in advance of the headlamp, which is characterized by a less sharp and thus less contrasting bright-dark border, without the causative details of the aperture shape, so the projections and / or cuts and / or recesses sharply displayed become what would be undesirable.

By virtue of the fact that an amplitude of the incisions and / or projections and / or an area and / or a number and / or a distance of first recesses increases with increasing distance from the optical axis, a light-dark boundary is produced in the second light distribution, which becomes comparatively sharp in a central area and comparatively blurred in peripheral areas. As a result, for example, vertical movements of the cut-off line, as occur, for example, on wavy roads, are more evident in the central area than in the peripheral areas. This results in the driver intuitively concentrating more on the central area, which is desirable for reasons of driving safety.

The same advantages are achieved alternatively or additionally by an embodiment of a headlamp according to the invention, in which the diaphragm edge has a central region lying close to the optical axis, in which the diaphragm neither protrusions, nor semi-open cuts in the diaphragm edge, still having a closed edge limited first recesses in the aperture.

The desired reduction in the sharpness of the cut-off line is achieved in the invention by designing the aperture. In comparison to the imaging optics, the diaphragm is a comparatively easy to design and to be manufactured part, which in total allows a predictable, targeted adjustment of the sharpness of the cut-off line with a reduced effort.

A preferred embodiment is characterized in that the imaging optics have a lens which is not rotationally symmetrical with respect to the optical axis or an astigmatic one which is not rotationally symmetrical with respect to the optical axis Lens system is. Astigmatism is an aberration in which points are not depicted as points, but generally as elliptical surfaces. Such an aberration already results to a comparatively small extent in the case of beam bundles which impinge on a rotationally symmetrical lens from a point located outside the optical axis. Non-rotationally symmetric lenses generally have a more pronounced astigmatism. The thus increased blurring of the image contributes in this embodiment to the fact that the holey or jagged or wave-shaped modulated diaphragm edge is not sharply displayed, which would be undesirable.

It is also preferred that the imaging optics have a different focal length on the optical axis in a plane or direction running along the diaphragm edge than in a plane or direction running transversely to the diaphragm edge. This results in the possibility of imaging the light distribution between the diaphragm edge and the imaging optics in the two directions with different degrees of sharpness. This contributes to the fact that projections, cuts and recesses, which has the aperture in the vicinity of the diaphragm edge, are not resolved when mapping the first light distribution in the second light distribution.

A further preferred embodiment is characterized in that the diaphragm edge is closer to one of the two focal points of the imaging optics lying on the optical axis than to the other of the two focal points of the imaging optics lying on the optical axis. In other words, the diaphragm edge is not equidistant from the two focal points, but closer to one of the two focal points. The aperture can basically be arranged in a horizontal position or a vertical position or in an intermediate position between these two layers in the headlight. Depending on the position of the diaphragm, it may be more favorable for the desired fuzzy dissolution of the projections and recesses and recesses to arrange the diaphragm closer to one of the two foci than to the other of the two foci.

It is also preferred that the diaphragm edge is arranged closer to the focal point farther away from the imaging optics in the direction of the optical axis than at the focal point which is less distant from the imaging optics. This embodiment has the advantage that it contributes to the fact that the projections, cuts and recesses in the aperture in the second light distribution are not resolved, and therefore not visible or at least not clearly visible in particular in a more horizontally than vertically arranged in the headlight aperture to step.

It is also preferred that the diaphragm lies in a plane which includes an angle of less than 20 °, in particular an angle of less than 10 °, in particular an angle of 0 ° with a plane defined by the diaphragm edge and the optical axis, and that the aperture has a reflective surface. As a result of this position and reflective design, the light initially shaded by the diaphragm can be reflected onto the light entry surface of the imaging optics and be refracted by the latter into the bright region of the second light distribution. This improves the efficiency which can be defined as the quotient of the light emitted by the light source in the denominator and the light forming the second light distribution in the counter.

A further preferred embodiment is characterized in that the diaphragm in its plane has bulges and / or depressions and / or further recesses which are farther away from the diaphragm edge than the first recesses. These structures are preferably used to modify the light distribution defined by the basic shape of the diaphragm, for example to obtain prescribed light intensity values at certain measurement points within the intrinsically dark region of the light distribution. These measuring points located above the cut-off line serve, for example, to ensure certain illuminance levels of traffic signs (so-called overhead values).

A further preferred embodiment provides that the imaging optics has light-scattering structures in the form of local bulges and / or depressions on its light entry surface and / or on its light exit surface.

This embodiment opens up further degrees of freedom in the design of the headlamps, since it permits a division of the modifications of the projection system to the diaphragm and the imaging optics required for a desired reduction in the sharpness of the cut-off line. The division reduces the amount of modification required with respect to each of the components. In the case of the lens, scattered structures that are distributed periodically or statistically over the lens surface may then be sufficient, which avoids time-consuming and expensive production of individually calculated scattering structures. At the same time, the lens reduces the sharpness of the image of the area of the diaphragm in the vicinity of the diaphragm edge which is structured in accordance with the invention. This contributes to the desired effect that the cuts, projections and recesses of the aperture in the second light distribution are not or only weaker than usual resolved.

Further advantages will be apparent from the dependent claims, the description and the attached figures.

It is understood that the features mentioned above and those yet to be explained below can be used not only in the respectively indicated combination but also in other combinations or in isolation, without to leave the scope of the present invention.

drawings

Fig. 1

einen Projektionsscheinwerfer als technisches Umfeld der Erfindung;

Fig. 2

eine aus dem Stand der Technik bekannte Blende;

Fig. 3

Ausführungsbeispiele von Blenden erfindungsgemäßer Scheinwerfer;

Fig. 4

ein Beispiel einer Lichtverteilung, die eine Hell-Dunkel-Grenze aufweist;

Fig. 5

Verläufe von Beleuchtungsintensitäten beim Überqueren der Hell-Dunkel-Grenze einer Lichtverteilung in qualitativer Form;

Fig. 6

eine nicht rotationssymmetrische, astigmatische Linse in zwei Schnittebenen mit zugehörigen Strahlengängen;

Fig. 7

eine Anordnung von Elementen eines erfindungsgemäßen Projektionscheinwerfers mit einer vertikal angeordneten Blende;

Fig. 8

eine Anordnung von Elementen eines erfindungsgemäßen Projektionsscheinwerfers mit einer horizontal angeordneten Blende; und

Fig. 9

eine weitere Ausgestaltung einer Blende eines erfindungsgemäßen Scheinwerfers.

Embodiments of the invention are illustrated in the drawings and are explained in more detail in the following description. Show, in schematic form:

Fig. 1

a projection headlamp as a technical environment of the invention;

Fig. 2

a known from the prior art aperture;

Fig. 3

Embodiments of panels according to the invention headlights;

Fig. 4

an example of a light distribution having a light-dark boundary;

Fig. 5

Trajectories of illumination intensities when crossing the cut-off line of a light distribution in qualitative form;

Fig. 6

a non-rotationally symmetric, astigmatic lens in two sectional planes with associated beam paths;

Fig. 7

an arrangement of elements of a projection headlamp according to the invention with a vertically arranged aperture;

Fig. 8

an arrangement of elements of a projection headlamp according to the invention with a horizontally arranged aperture; and

Fig. 9

a further embodiment of a diaphragm of a headlight according to the invention.

Identical reference numbers refer in the various figures to identical or at least functionally identical elements.

In detail, the shows FIG. 1 a projection headlight 10 for a motor vehicle with a light source 12, a light 15 of the light source 12 collecting optical element 14, a diaphragm 16 having a diaphragm edge 18, and an imaging optics 22. The said elements 12, 14, 16 and 22 are along a optical axis 31 of the headlamp 10 arranged so that the optical element 14 from the light source 12 originating light bundles 15 and directed to the diaphragm edge 18, so that adjusts a limited by the diaphragm edge 18 first light distribution at the diaphragm edge 18.

The imaging optics 22 is arranged and arranged so that it images the first light distribution as a second light distribution 24 in an apron of the headlamp 10, wherein the aperture edge 18 in the second light distribution 24 as a light-dark boundary 26 between a comparatively brighter area 28 and a comparatively darker area 30 of the second light distribution 24 is imaged.

The image is made in such a way that the aperture 16 is displayed upside down and reversed in the front of the motor vehicle. The brighter region 28 therefore lies below the horizon in the case of a projection headlamp 10, which is intended to fulfill a dimming function. The fact that the darker area 30 is above the horizon, dazzling oncoming traffic is avoided or at least reduced. The diaphragm edge 18 is generally asymmetrical and has, for example, a section sloping from the optical axis 31 to the side at an angle of 15 °, which is imaged as a rising edge in the second light distribution 24. As a result, it is known that the side of the vehicle not facing the oncoming traffic can be illuminated far more extensively. at Alternative embodiments are provided angles of 0 ° or 45 ° or 90 °.

The light source 12 is in a first embodiment, an incandescent lamp or a gas discharge lamp. In this embodiment, the light collecting optical element 14 is preferably a polyellipsoid reflector having an ellipsoidal basic shape. The light source 12 is preferably arranged in the one focal point of the ellipsoidal reflector. In the other focal point of the ellipsoidal reflector, the diaphragm edge 18 is arranged. The isotropically radiated light from the light source 12 is directed by the reflector 14 in the second focal point, so that there is a highly concentrated first light distribution, which is bounded by the diaphragm edge 18.

In an alternative embodiment, the light source 12 is a semiconductor light source or an array of semiconductor light sources. Semiconductor light sources, in particular light-emitting diodes, are generally half-space radiators and thus differ from incandescent lamps and gas-discharge lamps, which can be considered approximately as isotropically emitting light sources 12. For this reason, another light-collecting element 14 is used as the light source 12 for the semiconductor light source design.

In contrast to a polyellipsoid reflector, which surrounds the light source 12 more or less, in the case of semiconductor light sources as light sources 12, only a half-side closed reflector 14 is required, which should also have an ellipsoidal basic shape. Transferred to the representation of FIG. 1 This means that the lower half of the reflector 14 shown there could be omitted.

As an alternative to such a half-shell reflector as a light-collecting optical element could be used for a semiconductor light source or as an array of semiconductor light sources realized light source 12 and a head optics of light-conducting material which receives the light 15 of the light sources 12 and by refraction and by in the interior of the light conducting internal material internal total reflections and focuses on the diaphragm edge 18.

In one embodiment, the imaging optics 22 is a converging lens, which is arranged such that its reflector-side focal point lies in the region of the first light distribution at the diaphragm edge 18. The diaphragm edge 18 is then imaged as a sharp cut-off line 26 in the second light distribution 24 in the apron of the motor vehicle.

FIG. 2 shows a known from the prior art aperture 16, which, as shown in the FIG. 1 is shown, is arranged transversely to the optical axis 31 in the headlight 10 and has a substantially smooth aperture edge 18. The diaphragm edge 18 may have a curvature, as in the FIG. 2 is shown, in conjunction with the imaging optics 22 to achieve a desired contour of the cut-off line 26 in the second light distribution 24 in front of the motor vehicle. In the prior art, this smooth course is depicted as a sharp cut-off line 26.

The FIG. 3 shows various embodiments of apertures 32 inventive headlights 10. In detail, the FIG. 3a a diaphragm 32, the diaphragm edge 34 has half-open incisions 38 and projections 40. Measured on a central diaphragm profile 36, the projections 40 extend into a region which, in a conventional diaphragm, as shown in the FIG. 2 is shown, completely translucent would be. The projections 40 shadow in a region which is close to the central curve 36 of the diaphragm edge 34, light, which would not be shaded in the known aperture 16. In contrast, the semi-open incisions 38 allow light through the aperture 32, which would be completely shadowed in the conventional aperture 16.

This causes the aperture 32, as in the FIG. 3a is shown, the light intensity in the first light distribution, which adjusts itself to the diaphragm edge 34, reduced above the central course 36 and increased below the central curve 36.

Similarly, it is the subject of FIG. 3b , The object of FIG. 3b differs from the subject of FIG. 3a in that the projections 40 and cuts 38 in the subject matter of FIG. 3b give a rather wavy, round edge, while at the subject of the FIG. 3a have a more straight, pointed, jagged course.

The further embodiment, which in the Figure 3c is shown, characterized by first recesses 50, which are provided just below the diaphragm edge 34 in the aperture 32. By means of these recesses 50, light which would be shaded by the diaphragm material in the conventional diaphragm 16 passes through the diaphragm and thus influences the first light distribution which occurs at the diaphragm 32.

All three embodiments of the aperture 32, as shown in the FIGS. 3a-c are represented, characterized in that the diaphragm edge 34 has a central, lying close to the optical axis 31 region 42 in which the aperture 32 neither projections 40, nor half-open incisions 38 in the diaphragm edge 34, nor bounded by a closed edge having first recesses 50 in the aperture 32. Therefore, in this middle region 42, the diaphragms 32 do not differ from the conventional diaphragms 16. In this middle region, therefore, the light-dark boundary produced by the diaphragms 32 in cooperation with the other components of the projection headlamp 10 does not differ from the bright one Dark border, as produced in a projection headlamp with a conventional aperture 16.

Differences in the light distributions arise, however, in the right and left edge regions of the diaphragm edges, in which the diaphragm edge 34, for example, in the FIG. 3a illustrated serrated profile 46 or in the FIG. 3b has waveform shown 48 or in which first recesses 50 in the aperture 34 affect the first light distribution. This will be explained below with reference to FIGS. 4 and 5 explained in more detail. The FIG. 4 shows in its right half a half of a second light distribution 24, as it is generated by means of a conventional diaphragm 16 and having a well-marked both in the central region 42 and in the right edge region bright-dark boundary 26.

In her left half shows the FIG. 4 for comparison, a light distribution 24, as produced by the same projection headlight under the same conditions with a diaphragm 32, as shown in the FIGS. 3a . b and c is shown. In this case, the otherwise sharp light-dark boundary 26 in the left edge area blurred, which is indicated by a split of the light-dark boundary 26 in three light-dark boundaries 26, 26 'and 26 ".Each of the three lines 26, 26' and 26 "corresponds to a constant illuminance. This means that the transition from light to dark, which occurs in the right half of the light distribution 24 sharply above the cut-off line 26, takes place in the left half of the light distribution 24 over an area which is blurred over several degrees of angle.

It should be understood that the illustration of blurring the cut-off by three isolux lines 26, 26 ', and 26 "is merely illustrative and, in reality, any number of further isolux lines are given with a finer subdivision of illuminance values could draw.

FIG. 5 illustrates the same relationship in that there is the intensity over the degree of blending of the light spots from a central axis, for example, the optical axis 31 is shown. In this case, the course of intensity shown in solid lines belongs to a conventional diaphragm 16 and to a light distribution 24, as in the right part of FIG FIG. 4 is shown. This course is characterized by a sharp cut-off line 26, located in the FIG. 5 represented by a very steep curve 54 in the region of the horizon angle of 0 °. In contrast to this very steep course, the dashed curve 54 at the angle 0 ° and in a narrow angle environment around this angle of 0 ° around a lower slope. This means that the correspondingly less steep course of the cut-off line is correspondingly less contrasted and correspondingly more blurred.

The dashed curve 56 results in a projection headlight 10 by diaphragms, of which embodiments in the FIGS. 3a . b and c and which are characterized in that they affect the first light distribution at the diaphragm edge 34 in the right and left edge zones of the diaphragm 32 outside the central region 42 so that they allow more light in the otherwise shadowed area and less light in the otherwise get illuminated area.

In the FIG. 5 This is shown by the fact that the curve 54 belonging to the diaphragms 32 of a headlight according to the invention runs just below the horizon, that is to say at values of slightly less than 0 °, below the curve 56, while the curve 54 lies above the horizon Values of slightly more than 0 ° above the curve 56 runs.

That in the FIG. 4 from the center to the outer edges of the light distribution 24 becoming stronger blurring, which in the FIG. 4 is expressed by the increasing distance from inside to outside of the isolux lines 26 ', 26 and 26 ", resulting in that an amplitude of the incisions 38 and / or projections 40 and / or an area and / or a number and / or a distance of the first recesses 50 from a central course 36 of the diaphragm edge 34 increases with increasing distance from the optical axis 31.

The deliberate broadening and blurring of the cut-off line additionally requires that in connection with the FIG. 3 explained structuring of the diaphragm 32 in the region of the diaphragm edge 34 by cuts 38 and / or projections 40 and / or recesses 50 in the production the second light distribution 24 is not resolved. In other words, said structuring should not be visible in the second light distribution 24. This desired effect is favored by an astigmatism of the imaging optics 22. By astigmatism, dots are generally not depicted as dots, but as ellipses and thus out of focus.

In order to suitably dimension this desired blurring, an embodiment provides that the imaging optics 22 is a lens 58 which is not rotationally symmetrical with respect to the optical axis 31 or an astigmatic lens system which is not rotationally symmetrical with respect to the optical axis. Such an embodiment is schematically in the FIG. 6 shown. The FIG. 6a shows a first section 60 through such a non-rotationally symmetrical lens 58, which was guided along the optical axis 31 and transversely to a diaphragm edge 34. If the diaphragm edge 34 is to be imaged in the second light distribution 24 as a substantially horizontal light-dark boundary, the section 60 is a vertical section.

The FIG. 6b shows a second section 62 through the non-rotationally symmetrical lens 58, which is guided along the optical axis 31 and along a diaphragm edge 34. If the diaphragm edge 34 is to be imaged in the second light distribution 24 as a substantially horizontally running cut-off line, the section 62 is a horizontal section. The focal length of a lens is known to be longer, the lower its curvature.

At the subject of FIG. 6 the lens 58 has in its vertical section 60 a lower curvature of its light entry surface and light exit surface, and thus in particular a comparatively large focal length fv.

The focal length fv is in the FIG. 6a the distance of the focal point 66 from a median plane of the lens 58. The light rays 68 are correspondingly extending in the vertical sectional plane light rays.

In the horizontal section 62, the lens 58 has a greater curvature and thus shorter focal length fh. The focal point 64 lying in the horizontal sectional plane is therefore closer to the lens 58 than the focal point 66, which lies in the vertical sectional plane. The light rays 70 represent light rays lying in the horizontal sectional plane.

The FIG. 7 shows an arrangement of elements of a projection headlamp according to the invention with a vertically arranged aperture 32, as in connection with the FIG. 3 has been explained, and with a non-rotationally symmetrical lens 58, as in connection with the FIG. 6 has been explained.

The lens 58 is thicker at its upper edge than at its lateral edge and therefore has a greater focal length in its vertical section than in its horizontal section. The diaphragm edge 34 is preferably arranged closer to one of the two focal points 64, 66 than to the respective other of the two focal points 66, 64 of the lens 58 serving as imaging optics 22. In one particularly preferred embodiment, the diaphragm edge 34 is in the direction of the optical axis 31 closer to the farther from the imaging optics 22, respectively the lens 58, removed focal point 66, as disposed on the less far from the imaging optics 22, respectively the lens 58, the removed focal point 64th

The diaphragm edge 34 is therefore in this embodiment in vertical focal point 66 of the astigmatic lens 58. The horizontal focus 64 lies between the diaphragm edge 34 and the lens 58. This has the effect that the diaphragm edge is sharply focused vertically but not sharply horizontally. If the horizontal focal point 64 is far enough away from the vertical focal point 66, which is favored by the asymmetrically designed lens 58 with respect to its rotational symmetry, the serrated or wavy or first recesses 50 having shape of the aperture 32, respectively the diaphragm edge 34, no longer resolved. The cuts 38, projections 40 and recesses 50 are rather blurred horizontally, which is desirable here.

With respect to the light source 12 and the light of the light source 12 collecting optical elements shows the FIG. 7 an embodiment with an arrangement of two semiconductor light sources 72, 74, in particular light-emitting diodes, as a light source 12 and an array of internally totally reflecting auxiliary optics 80, 82 as light-collecting elements. The attachment optics 80, 82 consist for example of PMMA (polymethyl methacrylate) or PC (polycarbonate) as a light-conducting material. Due to the high refractive index of these materials compared to air, the opening angle of the outgoing light beam from each semiconductor light source decreases when entering the respectively assigned intent optics of, for example, 90 ° to about 40 °. This angle relates in each case to the deviation of a marginal ray of the propagation cone from a central axis of the propagation cone.

This effect justifies the light collecting effect of the attachment optics. By a design of the side surfaces as totally reflecting reflecting surfaces, a highly efficient focusing of the light takes place, since the internal Total reflection in contrast to reflections on reflective metal surfaces is virtually lossless.

The totally reflecting side surfaces and the surfaces of the auxiliary optics 80, 82 which serve as the light exit surface and face the diaphragm 34 are preferably configured by their geometry to focus the light emanating from the semiconductor light sources 72, 74 and to direct them to the diaphragm edge 34, so that at the Aperture edge 34 sets a limited by the diaphragm edge 34 first light distribution.

This is then imaged by the lens 58 as imaging optics 22 in the form of a second light distribution 24 in an apron of the headlamp 10, wherein the diaphragm edge 34 in the second light distribution 24 as a light-dark boundary 26 between a comparatively brighter area and a comparatively darker area is shown.

The FIG. 8 shows a particularly preferred embodiment of an arrangement of elements of a projection headlamp according to the invention. Similar to the subject of the FIG. 7 also indicates the subject of the FIG. 8 Semiconductor light sources 72, 74, 76, 78 as a light source 12 and associated attachment optics 80, 82, 84 and 86 as light collecting, focusing and directing elements. The unequal number of semiconductor light sources and attachment optics in the objects of FIGS. 7 and 8 is insignificant. However, a significant difference is the arrangement of the aperture 32nd

While the aperture 32 at the subject of FIG. 7 is arranged at right angles to the optical axis and in particular vertical to the optical axis, shows the FIG. 8 a parallel with respect to the optical axis 31, that is horizontal arrangement of the aperture 32. The FIG. 8 shows thus in particular an embodiment in which the diaphragm 32 lies in a plane which includes an angle of less than 20 ° with a plane defined by the diaphragm edge 34 and the optical axis 31, in particular an angle of less than 10 °, in particular one Angle of 0 °.

For the widening of the cut-off line with the present invention and reduction of the light intensity gradient above the cut-off in the edge regions of the second light distribution 24 in front of the vehicle, the angular position of the diaphragm 32 is of subordinate importance. A need for adjustment to the situation results under certain circumstances in that the diaphragm edge 34 should each have a similar curvature as the light entrance surface of the imaging optics 22 facing it, or the lens 58 serving as the imaging optics 22 FIG. 8 Such a curvature is recognizable. At the subject of FIG. 7 such a curvature would be feasible by moving the vertical outer edges of the aperture 32 somewhat towards the lens 58, while the central region of the diaphragm edge 34 should remain in the focal point 66 of the vertical section through the lens 58.

Compared to the vertical arrangement of the aperture 32 in the FIG. 7 lies the real advantage of the arrangement of the aperture 32, as shown in the FIG. 8 is shown in an increase in efficiency. In this case, an efficiency is understood here as the proportion of the amount of light emitted by the light source 12, which is imaged in the light distribution 24 in front of the motor vehicle. This amount of light remains with the object of FIG. 7 necessarily behind an optimal value, because the vertically arranged Aperture shading a certain portion of the first light distribution, which adjusts to the diaphragm edge 34, effectively shaded.

At the subject of FIG. 8 Although such shading also takes place in the sense that the horizontal diaphragm 32 prevents the light impinging on it from entering the intended dark region 30 of the light distribution 24. However, the horizontal diaphragm 32 also offers the possibility of reflecting the reflected light onto the light entrance side of the lens 58 facing the diaphragm 32, wherein the lens 58 is preferably designed such that it diffracts this light into the bright region 28 of the second light source Light distribution 24 directed in front of the motor vehicle.

This is the subject of the FIG. 8 less light lost than at the subject of the FIG. 7 , This efficiency advantage of FIG. 8 can still be increased by the fact that the light exit surfaces of the attachment optics 80, 82, 84, 86 facing surface of the aperture 32 is designed to be reflective. This is preferably achieved by a metallic reflective coating, as known from reflector fabrication for decades. The more efficient use of light makes the embodiment with the horizontally arranged aperture 32 particularly suitable for use in conjunction with semiconductor light sources as the light source 12. This is because semiconductor light sources, at least if limited in number, do not readily provide so much luminous flux as can be expected from gas discharge lamps and / or halogen lamps.

Another advantage of the horizontal aperture 32 is that with a horizontal installation of the aperture 32 of the lower part of the projection module for more Functions can be used. Thus, it is particularly advantageous to use the upper part as auxiliary low beam and the lower part as additional high beam. The aperture described acts both in the dipped beam and in the high beam range. As a result, the structurally visible dividing line between additional low beam and additional high beam is additionally blurred.

A preferred embodiment is characterized in that the aperture is movable. The aperture is moved along the aperture or folded. In one embodiment, as in the Fig. 7 is shown, there is a shift of the aperture down. In one embodiment, as in the Fig. 8 is shown, there is a shift of the panel to the rear. In one embodiment with a foldable panel, it is pivoted about an axis which is largely perpendicular, in particular perpendicular, to the direction of travel and largely parallel, in particular parallel to the roadway. Extensive means here except for deviations of less than 5 °. The folding movement takes place at the vertical aperture Fig. 7 preferably with a movement of the diaphragm edge forward and in the horizontal aperture of the Fig. 8 preferably with a movement of the diaphragm edge down. In a preferred embodiment, the movement of the diaphragm between two end positions is performed. In the end position shifted downwards or to the rear, or in the end position folded forwards or downwards, the projection headlamp supports the high beam function. It is also preferable that the diaphragm can also be moved in each case in one or more intermediate positions, which lie between said end positions.

Another embodiment is characterized in that the lens 58 further optical functions such as a Color correction or a further reduction in contrast in the area of the cut-off by microstructures or light-scattering structures on one or more surfaces of the lens 58 is met. To illustrate this shows the FIG. 6 a lens 58 as an embodiment of an imaging optics 22, which has light-scattering structures 92 in the form of local bulges and / or depressions on its light exit surface 90.

FIG. 9 shows a further embodiment, which is realized both in vertical and horizontally arranged aperture 32. This embodiment is characterized in that the diaphragm 32 has in its plane bulges and / or depressions and / or further recesses 88, which are farther away from the diaphragm edge 34 than the first recesses 50 which are used to broaden the cut-off line serve in their peripheral areas. Through these recesses, depressions or bulges, the shading effect of the diaphragm 32 is purposefully locally modified to give certain proportions of light a certain direction, so that, for example, traffic signs, which are normally in the dark area 30 of the second light distribution 24, with a small, but permissible and prescribed light intensity are irradiated, which does not lead to dazzling oncoming traffic. The recesses contain optical elements in a further embodiment.

Claims (10)

1. A projection headlamp (10) for a motor vehicle, having at least one light source (12), an optical element (14) that collects light (15) from the light source (12), and a screen (32) which has a screen edge (34), and having an optical projection element (22), in which the optical element (14) focuses collected light (15) and aims it at the screen edge (34), so that at the screen edge (34), a first light distribution defined by the screen edge (34) is established, which is projected by the optical projection element (22) as a second light distribution (24) into an area ahead of the headlamp (10), and the screen edge (34) in the second light distribution (24) is projected as a light-dark border (26) between a comparatively lighter region (28) and a comparatively darker region (30) of the second light distribution (24), and the screen (32) has protrusions (40) and/or semi-open notches (38) in the screen edge (34), and/or the screen (32) has first recesses (50) in the screen (32), which are defined by a closed edge and are disposed at a distance from the screen edge (34) that is shorter than one-fifth of the width (52) of the screen (32), characterized in that an amplitude of the notches (38) and/or protrusions (40) and/or an area of first recesses (50) and/or a number of first recesses (50), from a middle course (36) of the screen edge (34), increases with increasing distance from the optical axis (31).
2. The headlamp (10) according to claim 1, characterized in that the optical projection element (22) is a lens (58) that is not rotationally symmetrical relative to the optical axis (31), or an astigmatic lens system that is not rotationally symmetrical relative to the optical axis (31).
3. The headlamp (10) according to claim 2, characterized in that the optical projection element (22) on the optical axis (31) has a focal length in a plane extending along the screen edge (34) that is different from that in a direction extending transversely to the screen edge.
4. The headlamp (10) according to claim 3, characterized in that the screen edge (34) is located closer to one (66) of the focal points (64, 66) of the optical projection element (22) that are located on the optical axis (31) than to another (64) of the focal points of the optical projection element that are located on the optical axis (31).
5. The headlamp (10) according to claim 4, characterized in that the screen edge (34), in the direction of the optical axis (31), is disposed closer to the focal point (66) that is farther away from the optical projection element (22) than to the focal point (64) that is not as far away from the optical projection element (22).
6. The headlamp (10) according to one of the foregoing claims, characterized in that the screen (32) is located in a plane which, with a plane defined by the screen edge (34) and the optical axis (31), forms an angle of less than 20°, in particular an angle of less than 10° and in particular an angle of 0°, and that the screen (32) has a reflective surface.
7. The headlamp (10) according to one of the foregoing claims, characterized in that the screen (32), in its plane, has convexities and/or indentations and/or further recesses (88), which are located farther away from the screen edge (34) than the first recesses (50) are.
8. The headlamp (10) according to one of the foregoing claims, characterized in that the screen edge (34) has a middle region (42), located near the optical axis (31), in which the screen (32) has neither protrusions (40),nor semi-open notches (38) in the screen edge (34), nor first recesses (50) in the screen that are defined by a closed edge.
9. The headlamp (10) according to one of the foregoing claims, characterized in that the optical projection element (22), on its light entry face and/or on its light exit face (90), has light-scattering structures (92), in the form of local convexities and/or indentations.
10. The headlamp (10) according to one of the foregoing claims, characterized in that the screen (32) is movable.

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