EP2730836B1 - Light module for a headlight of a motor vehicle - Google Patents

Description

The invention relates to a light module for a headlight of a motor vehicle according to the preamble of claim 1. Such a light module is both from the JP 2004 172 104 as well as from the JP 2009 193 810 known.
It should be noted that in the following text all designations which relate to an orientation in space, such as above, below, horizontally, vertically, etc., refer to an orientation of the light module in the room, which in an intended use of the light module in an in a motor vehicle built-in headlights of a motor vehicle on a flat road or floor space results.

So-called projection light modules are known from the prior art, in which one or more primary optics depict one or more light sources on a focal surface. This results in the focal surface of a first light distribution, which is imaged by a secondary optics in a second, lying in the run-up of the motor vehicle light distribution. The light-dark border is created by the edge of an aperture. If the edge lies in the focal surface of the secondary optics, it is imaged by this as a sharp cut-off in the second light distribution. Because the secondary optics images the first light distribution generated in the focal plane upside down and laterally reversed, light that passes through the focal surface above an optical axis of the secondary optics is imaged below the optical axis. Conversely, light passing through the focal plane below the optical axis is imaged above the optical axis. This gives the second light distribution a brighter area below the cut-off line that illuminates the lane, and a darker area above the cut-off line, which avoids dazzling oncoming traffic. Thus, the second light distribution is a rule-compliant low beam light distribution.

Also known are so-called direct imaging systems in which an imaging optical system images a light source directly through a clear cover of the headlight in the apron of the motor vehicle.

From the EP 1 193 440 A1 is a reflective aperture known. The diaphragm is designed as a horizontal surface in the light module, which has a reflective surface. Light, which would normally be shaded by a vertical aperture, strikes the reflective surface and reflects upwards. The reflected light passes through the focal plane above an optical axis and is therefore imaged by the secondary optics into the brighter area below the cut-off line. The light reflected from the aperture surface increases the efficiency of the light module.

The legislator stipulates that a certain area, which lies in the darker area of the low-beam distribution and thus above the cut-off line, should be illuminated with a certain minimum illuminance. This area, also called overhead area, serves, for example, to illuminate traffic signs arranged above the roadway. A conformal overhead light distribution must be such that it has sufficient light intensity in a limited angular range above the cut-off line, while avoiding dazzling oncoming traffic.

From the DE 10 2008 015 510 It is known to generate an overhead light distribution by allowing a partially mirrored aperture to pass light through a non-mirrored portion of the aperture. The light then passes below the optical axis through the focal plane of the imaging optics and is therefore deflected by the latter into a region above the cut-off line of the low-beam light distribution in order to produce an overhead light distribution. Alternatively, translucent recesses may also be incorporated into a fully-mirrored diaphragm to produce the overhead light distribution.

Many projection light modules are designed for vertically very narrow light distributions or, for reasons of efficiency, have a first light distribution, which is formed mainly by beams which originate directly from the light source and have few or no reflected components.

In these systems, it is often not possible to find a beam that follows an overhead light path and that is imaged as it passes through a lichtduchlässigen part of the aperture of the secondary optics so that the legal requirement on the overhead light distribution are met.

Furthermore, one also finds bundles of rays which, although they follow an overhead light beam path, however lead to glare of oncoming traffic or exceeding the maximum permissible illuminance for the overhead lighting.

Against this background, the object of the invention is to specify a light module of the type mentioned above, with which a rule-conforming overhead light distribution can be represented.

This object is achieved with the features of claim 1. In this case, the invention differs from the prior art known at the outset as known per se in that the diaphragm edge is a front edge of a substantially horizontal diaphragm having a reflecting surface which has a recess which extends through a recess located between the recess and the diaphragm edge Partial face of the diaphragm is separated from the diaphragm edge and the lying in transverse to the optical axis of the light module directions through the first reflection surface and the second reflection surface is limited.

By lying between the diaphragm edge and the recess part surface of the diaphragm, there is the effect that the recess does not block out any light from an area lying directly on the diaphragm edge, which is a undesirable reduction of the range of the low beam avoids.

By already mentioned in the preamble of claim 1 first of the two deflections, the overhead light of the remaining light, which generates the low-beam light distribution, separated. The second deflection allows an individual influencing of the separated light with the aim of generating a rule-compliant overhead lighting.

The embodiments described below relate to projection light systems, in which a primary optics initially generates a light module-internal first light distribution, which is projected by an imaging optical system in the apron of the headlight. However, the invention can also be easily transferred to direct imaging systems in which e.g. a light exit surface of a semiconductor light source is projected by projection.

A preferred embodiment is characterized in that the light module has at least a primary optic, an imaging optic and a diaphragm, the primary optics collecting light emitted by the light source and producing therefrom a first light distribution which lies in a focal plane of the imaging optic, the imaging optics thereto is configured to image the first light distribution in a lying in a run of the light module second light distribution, and wherein the aperture has the optically effective edge and wherein the edge lies in the focal surface and limits the first light distribution and thus as a light-dark boundary in the second light distribution is imaged, and wherein the aperture has a recess which through the first Reflection surface and the second reflection surface is limited, wherein designed as a first reflection surface boundary surface of the recess of the light source and the second reflection surface, so that it deflects light incident thereon from the light source to the second reflection surface and wherein the configured as a second reflection surface boundary surface of the recess the first reflection surface and the secondary optics faces and directs incident light from the first reflection surface forth on the secondary optics.

By these features, the above-mentioned disadvantages of failure to meet the requirements for the overhead illumination intensity in a diaphragm with a recess provided for generating the overhead lighting are avoided. This is achieved by the double deflection, which allows a targeted directional influence of the light used to generate the overhead light. It is also preferred that the diaphragm is a one-piece cohesively connected plastic injection-molded part, which is demoldable without undercut. This is a particularly cost effective alternative.

It is also preferred that the panel has a sheet metal part forming the front panel edge, which is encapsulated in plastic or connected to a plastic part, wherein the opening is arranged in the plastic part. This is a thermally comparatively high loadable alternative for applications with strong sunlight.

Furthermore, it is preferred that the diaphragm is made of metal. This is also a thermally highly resilient design. In this case it is not necessarily it is necessary to mirror or coat the reflective surfaces, but it is sufficient to mold more or less polished tool surfaces. This saves the cost of additional operations such as coating or polishing the reflective surfaces.

It is also preferred that the aperture has a recess formed by punching or cutting, wherein the recess results as a result of a continuous separation of the diaphragm material on three sides of the recess and over a fourth side of the recess downwardly deflecting the resulting tongue a surface of the bent tongue forms the second reflecting surface. Thus, the invention can be implemented easily and inexpensively.

It is also preferred that the first reflection surface and / or the second reflection surface in their vertical extension is in each case a flat surface. This embodiment has the advantage that the shape (divergence) of the reflected beam is not changed. Instead, only the direction of the light and / or its distance to the optical axis is changed. For example, reflecting surfaces arranged perpendicularly to the optical axis ensure a parallel displacement of the reflected light. The parallel shifted light occurs as a result of the parallel displacement and the greater distance from the optical axis to more curved areas of the imaging optics and experiences there correspondingly a greater deflection. By tilting from a reflection surface or from both reflection surfaces, the light can be targeted to areas of the secondary optics, which cause a change in direction required for the desired overhead lighting.

A further advantageous embodiment provides that the first reflection surface and / or the second reflection surface is convexly curved in its vertical extension. The convex curvature of the reflection surfaces causes a bundle of rays to expand vertically during the reflection. This results in a vertically wide first light distribution in the focal surface, which is imaged by the secondary optics in a vertically wide second light distribution. In this way it becomes possible to illuminate a larger angular range in the vertical direction with the aid of the convex reflection surfaces than with flat reflection surfaces. However, because the irradiated amount of light is distributed over a larger area, the illuminance of this area decreases.

In addition, it is proposed that the first reflection surface and / or the second reflection surface is concavely curved in its vertical extent. The concave curvature of the reflection surfaces leads to a bundle of rays being vertically focused during the reflection. This results in a vertically narrow first light distribution in the focal surface, which is imaged by the secondary optics in a vertically narrow second light distribution. In this way, a narrower in the vertical direction angle range is illuminated than with flat reflecting surfaces. However, because the amount of light irradiated is distributed to a smaller area, the illuminance of this area increases.

It is also favorable that the first reflection surface and / or the second reflection surface are convexly curved in their horizontal extension. The convex curvature of the Reflection surfaces cause a bundle of rays to expand horizontally during reflection. This results in a horizontally wide first light distribution in the focal surface, which is imaged by the secondary optics in a horizontally wide second light distribution. In this way it becomes possible to illuminate a larger angular range in a horizontal direction with the aid of the convex reflection surfaces than with flat reflection surfaces. However, because the irradiated amount of light is distributed over a larger area, the illuminance of this area decreases.

Furthermore, it is proposed that the first reflection surface and / or the second reflection surface are concavely curved in their horizontal extent. The concave curvature of the reflection surfaces causes a bundle of rays to be horizontally focused during the reflection. This results in a horizontally narrow first light distribution in the focal plane, which is imaged by the secondary optics in a horizontally narrow second light distribution. In this way, an angle range smaller in the horizontal direction is illuminated than with flat reflecting surfaces. However, because the amount of light irradiated is distributed to a smaller area, the illuminance of this area increases.

Of course, all possible combinations of the four embodiments of the reflecting surfaces described above are conceivable, if they serve the representation of the rule-conforming overhead light distribution. With its embodiments, the invention permits in each case an adjustment of the intensity and the position of the overhead light distribution by a specific definition of the Geometry of the two reflection surfaces, because this geometry determines the direction and divergence (opening angle) of each reflected light beam.

It is also preferred that the first reflection surface and / or the second reflection surface are tilted against the focal surface. Preferably, one or both reflection surfaces are inclined relative to the focal surface so that the light reflected twice at them passes through the focal surface at the same location as the light passing directly through the recess. Because the light reflected twice at the inclined reflection surfaces passes through the imaging optics at a location closer to the optical axis, imaging optics with a smaller vertical extent can be used, as long as the other beam paths allow. Smaller imaging optics, are cheaper to produce and lead to a reduction in the sizes of the light modules. In addition, they contribute to a reduction in fuel consumption due to their lower weight.

In a largely parallel arrangement of the two reflection surfaces to each other or to the focal surface results in a reversal of the light direction between the surfaces. It is also conceivable to increase the inclination of the two reflection surfaces against the focal surface and to change the arrangement of the reflection surfaces so that the reversal of the light direction is eliminated. The inclination of the reflection surfaces against the focal surface or against each other, as well as a shift of the reflection surfaces against each other or with respect to the focal surface can be carried out in the vertical and / or horizontal plane. This can cause structural restrictions in the Beam path and / or be compensated in the imaging optics.

In particular, the two reflection surfaces can also be arranged independently of a recess in the diaphragm. Under certain circumstances, it is advantageous if the imaging optics has a special zone, similar to a progressive or two-strength spectacles, by which the light reflected at the two reflection surfaces light is deflected into a rule-compliant overhead area.

On the other hand, it is also conceivable to use a recess in the diaphragm according to the prior art and to realize the two required for the generation of the overhead light reflecting surfaces as separate from the diaphragm structures.

An embodiment with reflection surfaces that are separate from the diaphragm can also be combined with a diaphragm that has no recess.

All of the above-mentioned variants of the arrangement and shape of the reflection surfaces can also be used to guide part of the light to generate the rule-conforming overhead light distribution past the imaging optics.

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

Figur 1

eine Schnittdarstellung eines bekannten Scheinwerfers mit einem Projektionslichtmodul als technisches Umfeld der Erfindung;

Figur 2

schematische Darstellungen einer ersten bevorzugten Ausführungsform der Erfindung;

Figur 3

eine Seitenansicht eines Schnittes durch den Gegenstand der Fig. 2 zur Erläuterung der Funktionsweise;

Figur 4

eine Schnittdarstellung einer Blende, die eine Ausgestaltung der Erfindung darstellt;

Figur 5

eine Schnittdarstellung einer Blende einer weiteren Ausgestaltung;

Figur 6

eine Schnittdarstellung wesentlicher Elemente einer weiteren Ausgestaltung;

Figur 7

Messwerte einer Abblendlichtverteilung und einer Overheadlichtverteilung, die mit einer Blende erzeugt wurden, die dem Stand der Technik entspricht; und

Figur 8

Messwerte einer Abblendlichtverteilung und einer erfindungsgemäß erzeugten Overheadlichtverteilung.

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

FIG. 1

a sectional view of a known headlamp with a projection light module as a technical environment of the invention;

FIG. 2

schematic representations of a first preferred embodiment of the invention;

FIG. 3

a side view of a section through the subject of Fig. 2 to explain the operation;

FIG. 4

a sectional view of a diaphragm, which represents an embodiment of the invention;

FIG. 5

a sectional view of a panel of another embodiment;

FIG. 6

a sectional view of essential elements of another embodiment;

FIG. 7

Measured values of a low beam distribution and an overhead light distribution generated with a diaphragm that corresponds to the prior art; and

FIG. 8

Measured values of a low-beam light distribution and an overhead light distribution generated according to the invention.

There are for functionally equivalent elements and sizes in all figures used in different embodiments, the same reference numerals.

FIG. 1 shows a schematic representation of a light module 10 for a motor vehicle headlight 1, with a light source 12, a light 14 of the light source 12 collecting element 16, also called primary optics, a diaphragm 18 having a diaphragm edge 20, and an imaging optics 22, which also as Secondary optics is called. Said elements 12, 16, 18 and 22 are arranged along an optical axis 24 of the light module 10 so that the element 16 bundles light 14 originating from the light source 12 and directs it to the diaphragm edge 20, so that at the diaphragm edge 20 one of the diaphragm edge 20 limited first light distribution 23 sets. The light source is arranged for this purpose in a first focal point of the primary optics. The diaphragm edge is arranged in a second focus of the primary optics, so that the primary optics of the light source outgoing light bundles in the second focal point at the diaphragm edge. The light module 10 is arranged in a housing 2, which has a light exit opening, which is covered by a transparent cover 3. The iris can be straight or curved.

The imaging optics 22 is arranged and arranged so that it images the first light distribution 23 as a second light distribution 26 in a front of the light module 10, wherein the diaphragm edge 20 in the second light distribution 26 as a light-dark boundary 28 between a comparatively brighter area 30th and a comparatively darker region 32 of the second light distribution 26 is imaged.

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 20. The diaphragm edge 20 is then imaged as a sharp cut-off line 28 in the second light distribution 26 in the apron of the motor vehicle.

The image is made in such a way that the aperture 18 is displayed upside down and reversed in the front of the motor vehicle. The brighter region 30 therefore lies below the horizon in the case of a projection headlamp 10, which is to fulfill a dimming function. The fact that the darker area 32 is above the horizon, dazzling oncoming traffic is avoided or at least reduced. The thus generated second light distribution 26 thus represents the rule-compliant low beam distribution.

In general, the diaphragm edge 20 is designed asymmetrically and has, for example, from the optical axis 24 to the side by an angle of 15 ° sloping, section, which is displayed as a rising edge in the second light distribution 26. As a result, as is well known, the side of the road not facing oncoming traffic can be illuminated far more extensively. This asymmetry occurs in a plane perpendicular to the plane of the drawing and the optical axis and is therefore in the Fig. 1 not visible.

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 16 is preferably a polyellipsoid reflector, which is an ellipsoidal Basic form possesses. 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 20 is arranged. The light isotropically radiated by the light source 12 is directed by the reflector 16 into the second focal point, so that there arises a highly focused first light distribution which is delimited by the diaphragm edge 20.

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 16 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 16 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 16 shown there could be omitted.

As an alternative to such a half-shell reflector as a light-collecting optical element 16, a head optics made of light-conducting material could also be used for a light source 12 realized as a semiconductor light source or as an arrangement of semiconductor light sources. which absorbs the light 14 of the light source 12 and, by refraction at the light entrance surface and the light exit surface and by taking place inside the light-conducting material material internal total reflections at lateral interfaces and focuses on the diaphragm edge 20. Such an embodiment is in the Fig. 2 to 6 displayed.

It should also be noted that the invention described below is also conceivable for so-called direct-imaging headlamp systems in which light-reflecting and / or light-refracting optics as light-collecting elements 16, the light 14 of the light source 12 directly through a clear cover of the headlamp in the apron of the motor vehicle to steer. The first light distribution in this case is, for example, an optically effective light exit surface of an arrangement of light-emitting diodes (LEDs). In the automotive field, e.g. LEDs with rectangular or square light exit surfaces of 0.3 up to 2 mm edge length used, from which larger light exit surfaces can be composed mosaic-like. It is also essential in such embodiments that the light 14 of the light source 12 passes through a focal plane of the imaging optics 22. In such an embodiment, the edge may be an edge of the light exit surface or an edge of an additional diaphragm which is arranged in the immediate vicinity of the light exit surface.

Fig. 2a shows a side view of an arrangement of light source 12 with primary optics 16, aperture 18 and imaging optics 22. The aperture 18 is in the invention in contrast to the subject of Fig. 1 a substantially horizontal, in particular a horizontal lying Aperture having a specular surface which is illuminated with light from the light source 12. The light source 12 is here a semiconductor light source, in particular a light emitting diode or an arrangement of a plurality of light emitting diodes. However, the invention can also be realized using other light sources. The light-collecting primary optics 16 here is a front optics made of a transparent material such as glass. Such an attachment optics has at least one light entry surface facing the light source, a light exit surface facing the screen and at least one lateral boundary surface lying between the light entry surface and the light exit surface and connecting these two surfaces. The lateral boundary surface is preferably configured to direct incident light from the light entry surface to the light exit surface through total internal reflection. The bundling effect of such an optical attachment results from the total reflections mentioned as well as from the refraction of light at the light entry surface and the light exit surface. The attachment optics are designed to collect the light emitted by the light source and to direct it to the aperture, as described above in connection with the Fig. 1 has been described. Therefore, the light-collecting primary optics may also be a concave mirror reflector. Alternatively, the light-collecting primary optics may also be a condensing lens.

The front edge 20 of the diaphragm lies in a light source-side focal surface 40 of the imaging optics 22, and the reflective surface extends from the diaphragm edge towards the rear towards the light source. Light 23 passing through the focal plane of the imaging optics without prior reflection at the specular surface above the optical axis 24 is transmitted through the optical system Imaging optics shown below the horizon. Light 25, which would pass through the focal plane 40 at a non-existent aperture below the optical axis, would then be imaged above the optical axis. The reflecting aperture also images this light below the horizon, which results from the downward sloping course of the associated light bundle 25, which emerges from the imaging optics (to the left). This requirement also determines the allowed degree of deviation from a horizontal position. In any case, the diaphragm is arranged so that light reflected at its reflecting surface located outside the recess is directed onto the imaging optics such that it deflects it into the bright region below the cut-off line. Together, these two light beams provide a light distribution with cut-off and improved efficiency over non-reflecting diaphragms. This is known so far. It is new that boundary surfaces of an overhead light from the luminous flux of the light source 12 blanking recess in the diaphragm are used for generating and / or influencing the overhead light. In this case, the invention has the particular advantage that it branches off this light from the luminous flux of the light source so that the light intensity at the cut-off line is not affected. How the boundary surfaces are used for generating and / or influencing the overhead light will be described in detail below with reference to FIGS Fig. 3 explained. First, however, the Fig. 2b explained.

The FIG. 2b shows the arrangement of the light source 12, the primary optics 16, the diaphragm 18 and the imaging optics 22 from the Fig. 2a in isometric view. The diaphragm 18 has a recess 34. The recess 34 is in a preferred embodiment rectangular. The recess is separated from the diaphragm edge by a partial surface of the diaphragm located between it and the diaphragm edge 20. The distance of the recess from the diaphragm edge is preferably at least twice, preferably more than three times the thickness of the diaphragm. This has the technical effect that the recess does not block out any light from an area of the specular diaphragm surface located directly on the diaphragm edge. This area influences the intensity of the light directly at the cut-off line. Intensity losses would reduce the range of the dipped beam at this point. This undesirable effect is avoided by the aforementioned embodiments. In the illustrated embodiment, the recess 34 is limited in transverse to the optical axis 24 directions by two surfaces, which are preferably designed as reflection surfaces 36, 38. A designed as a first reflection surface 36 boundary surface of the recess of the light source 12 and the second reflection surface 38 faces. It is correspondingly illuminated by the light source 12 and deflects incident light to the second reflection surface 38. The designed as a second reflection surface 38 boundary surface of the recess facing the first reflection surface and the secondary optics 22. The first reflection surface 36 and the second reflection surface 38 are preferably designed to be reflective.

In principle, there is the possibility in the development of primary optics to direct a certain proportion of the light, for example with a facet in the exit optics of the primary optics, to the opening. Alternatively, however, the light that simply falls on the panel is used. The size of the open area in the aperture provides an important parameter for controlling the luminous flux. In this case, a single large opening or a plurality of small individual openings can be selected with corresponding surfaces. The plurality of surfaces are arranged substantially side by side. Depending on the optical conditions may be an arrangement of several individual openings, each with the same distance from the diaphragm edge. When using a plurality of LED modules each consisting of a light source 12 and a lens attachment (primary optics 16 different modules can each be assigned an opening.

In a preferred embodiment, the diaphragm 18 is a one-piece cohesively connected plastic injection molded part which is demoldable without undercut. In an alternative embodiment, the diaphragm 18 is a metal part. The recess 34 is produced in this case, for example, by punching or cutting, wherein the diaphragm material is cut on three sides of the recess 34 and bent over a fourth side down. The severing and bending preferably takes place such that a surface of the bent material becomes the second reflection surface 38.

In this embodiment, the recess results as a result of the continuous separation of the diaphragm material on three sides of the recess and on the fourth side of the recess downward bend of the resulting tongue, wherein a surface of the bent tongue forms the second reflection surface.

In a further embodiment, a part made of sheet metal forms the front panel edge. This sheet metal part is with Plastic encapsulated or connected to a plastic part, for example by clips. The opening 34 is preferably arranged in the plastic part. This ensures that the aperture, for example, is not damaged by sunlight, which is bundled by the secondary optics on the diaphragm edge. As a result, the diaphragm edge is subject to particularly high thermal loads compared to the rest of the diaphragm. Metal keeps these loads better than plastic.

FIG. 3 shows a schematic representation of the influence of the recess 34 and the first reflection surface 36 and the second reflection surface 38 on the propagating light.
The in the Fig. 3 illustrated arrangement of the light source 12 with the primary optics 16, the diaphragm 20 and the imaging optics 22 corresponds to the arrangement of these components from the Fig. 2 , In contrast to Fig. 2 show the Fig. 3 incident beam paths of light that passes through the recess 34. The diaphragm 18 is arranged in particular such that the diaphragm edge 20 lies in the light source-side focal surface 40 of the imaging optical unit 22.

A first beam 42 of the light 14 of the light source 12 enters the recess 34 and strikes the first reflection surface 36. From this first reflection surface 36, the first beam 42 is reflected by a first reflection in the direction of the second reflection surface 38. There, ie at the second reflection surface 38, the beam 42 is reflected a second time and forms a beam 44. The propagating in this beam 44 light passes through the light source side focal surface 40 of the imaging optics 22 below the optical axis 24 and is by the imaging optics 22 in the second light distribution 26 is deflected above the cut-off line 28, wherein it forms after the exit from the imaging optics 22 a forward and upward directed overhead light beam 46.

Thus, the light propagating in the first beam 42 is directed into an overhead light bundle 46, in which light 14 is transferred to a less brightly-lit region 32 of the low-beam light distribution 26, beyond the light-dark boundary 28, in which region 32 a rule-compliant dipped beam must reach locally predetermined overhead brightness values.

In the embodiment, in the Fig. 2a and 3 is shown, the first reflection surface 36 and the second reflection surface 38 are flat and parallel to each other. As a result, the shape of the first beam 42 is maintained. So it is neither expanded nor bundled. Its divergence remains with the twofold redirection. The doubly-reflected beam 44 is compared to a direct beam 47, which passes through the recess 34 without being deflected at the first reflection surface, down, ie away from the optical axis 24, offset. The doubly-reflected beam 44 is displaced parallel downwards and thus away from the optical axis 24 by the longer path compared to the direct beam 47 and passes through the focal surface 40 deeper. As a result, it is refracted upwards by the imaging optics 22 and ultimately deflected higher than the light propagating in the beam path 47 above the cut-off line 28 into the apron of the motor vehicle. There it contributes to the formation of a rule-compliant overhead lighting.

Fig. 4 shows a longitudinal section along the optical axis through a diaphragm 18, which has a first reflection surface 36 and a second reflection surface 38. The first reflection surface 36 and the second reflection surface 38 are formed in this embodiment in the vertical direction in each case convexly curved. Here, too, the diaphragm edge 20 lies in a light source-side focal surface of the imaging optics 22. The incident first radiation beam 42 strikes the convex first reflection surface 36 and is reflected by this to the second reflection surface 38 and thereby widened in the vertical direction. The second reflection surface 38 is also convex. The light reflected in the second reflection on the second reflection surface 38 is therefore again widened in the vertical direction. This results in the focal surface 40, a first light distribution having a greater vertical extent compared to the first light distribution generated with the flat reflecting surfaces 36 and 38. This expanded first light distribution is imaged by the imaging optics 22 in the second light distribution. The vertical extent of the resulting overhead light component at the second light distribution is greater than the vertical extent of the overhead light component at the second light distribution, which results for the case with planar reflection surface 36 and 38. At comparable luminous flux levels of each incident on the first reflection surface 36 light beam 42, the expansion of the overhead light component with a reduction in illuminance within the overhead light component in the second light distribution 26 is accompanied, since the same luminous flux at convex reflection surfaces 36, 38 on a larger solid angle is distributed.

Fig. 5 shows a longitudinal axis extending along the optical axis Vertical section through a diaphragm 18, which has a first reflection surface 36 and a second reflection surface 38. The first reflection surface 36 and the second reflection surface 38 are each concavely curved in the vertical direction in this embodiment. Here, too, the diaphragm edge 20 lies in a light source-side focal surface of the imaging optics 22. The incident first beam 42 strikes the concave first reflection surface 36 and is reflected by this to the second reflection surface 38 and thereby focused in the vertical direction. The second reflection surface 38 is also concave in shape. The light reflected in the second reflection on the second reflection surface 38 is therefore bundled again in the vertical direction. This results in the focal surface 40, a first light distribution, which has a smaller vertical extent compared to the first light distribution generated with the flat reflecting surfaces 36 and 38 and therefore is narrower. This narrower first light distribution is imaged by the imaging optics 22 into the second light distribution. The vertical extent of the resulting overhead light component at the second light distribution is smaller than the vertical extent of the overhead light component at the second light distribution, which results for the case with flat reflecting surface 36 and 38. At comparable luminous flux levels of each incident on the first reflective surface 36 light bundle 42, the bundling of the overhead light component is accompanied by an increase in illuminance within the overhead light component in the second light distribution 26, since the same luminous flux in convex reflection surfaces 36, 38 on a smaller solid angle is distributed.

The above description of FIGS. 4 and 5 applies to the shape of the first reflection surface 36 and the second reflection surface 38 in the plane of the drawing. Changes in the curvature of the reflection surfaces in this plane in each case influence the vertical light distribution.

Further embodiments are characterized in that the reflection surfaces 36, 38 alternatively or additionally in a plane perpendicular to the plane of the drawing and the optical axis level are curved flat or convex or concave. Different curvatures in such a plane are formed in different horizontal light distributions. A curvature plane of the first reflection surface 36 and the second reflection surface 38 is in each case identical to a plane in which the reflected radiation beam 44 is widened or focused. Here, by a plane of curvature is meant an imaginary plane which intersects the reflection surface and in which the resulting cutting curve has a curvature. If a reflection surface, for example, convexly curved in its horizontal extension, the beam reflected on it is widened in the horizontal. If the reflection surface is concavely curved, for example in its horizontal extension, the beam reflected on it is focused in the horizontal. For concave or convex curved surfaces in their vertical extent, it holds true that the bundle of rays reflected on them is focused or widened in the vertical direction.

Consequently, reflecting surfaces which are curved in their horizontal and vertical extension convexly or concavely expand or focus the beam reflected thereon in both the horizontal and in the vertical direction. A widening or focusing of the overhead light distribution is consequently achieved by convex or concave reflection surfaces 36 and 38.

The plane in which the reflection surfaces are curved determines the direction in which the expansion or focusing takes place. Reflective surfaces 36, 38 curved around the vertical produce an expansion or focusing of the overhead light distribution in the horizontal. In contrast, when the reflection surfaces 36 and or 38 are curved around the horizontal, the overhead light distribution is widened or focused in the vertical direction.

The Fig. 6 shows a schematic representation of the light source 12 arranged thereon with primary optics 16, and the diaphragm 18 with the recess 34, and the secondary optics 22. The diaphragm edge 20 is also here in the light source side focal surface 40 of the imaging optics 22. In contrast to the subject of FIG. 3 the second reflection surface 38 is arranged tilted relative to the first reflection surface 36. In the illustrated embodiment, the first reflective surface 36 is parallel to the focal surface 40, while the second reflective surface 38 is not parallel to the focal surface 40. In the illustrated embodiment, the lower end of the second reflection surface 38 in the figure is closer to the focal surface 40 than the upper end of the second reflection surface 38 closer to the horizontal mirror surface of the diaphragm.

At the obliquely forwardly inclined downwards second reflection surface 38 is there incident beam 42 after the at the first reflection surface 36 reflected the first reflection a second time and occurs at the same point 48 through the focal surface 40 as the uninfluenced beam 44 that the recess 34 passes directly and without being reflected there. Due to the two-fold reflection on the surfaces 36 and 38 and the inclination of the second reflection surface 38, the dual-reflected beam 47 with a smaller distance from the optical axis 24 passes through the imaging optics 22 as the beam 44. Thus, the vertical width of the second light distribution 26 with respect to Use of aperture 20 with recesses 34 without reflective surfaces 36 and 38 not changed. This shows that by tilting the reflective surfaces 36 and / or 38, it is possible to use imaging optics 22 of lesser vertical extent to obtain a second light distribution 26 having a width such as recesses 34 without first reflective surfaces 36 and second reflective surfaces 38 would come.
In the FIG. 6 only the tilt of the second reflection surface 38 is shown about a first axis which is perpendicular to the optical axis 24 and points in the plane of the drawing. It is also conceivable tilting of the reflection surface about a second axis, which is neither parallel nor antiparallel to the first axis and the optical axis.
The above FIGS. 3 to 6 show embodiments in which the first reflection surface 36 and the second reflection surface 38 are each inclined in pairs planar, concave, convex or relative to the focal surface 40. Of course, as well as any combinations of the arrangements described above or formations of the reflective surfaces 36 or 38 conceivable that serve to produce a rule-conforming overhead light distribution.
From the drawings, in particular from the Fig. 3 and the Fig. 6 It can be seen that the overhead light 46 consists of a direct and a reflected portion. However, this also means that the two partial light bundles must have similar opening angles and leave the opening in approximately the same direction. The fulfillment of these conditions is required so that the two light beams can overlap to a light distribution. In a preferred embodiment, the two mirror surfaces are configured in such a way that the reflected light bundle fulfills the conditions for the superposition of the two bundles.
The FIGS. 7 and 8 show experimentally determined second light distributions 26 for a diaphragm 18, which has a recess 34. It concerns the Fig. 7 a diaphragm 18, as known from the prior art, and the Fig. 8 relates to an embodiment with a diaphragm 18, which has a recess 34, a first reflection surface 36 and a second reflection surface 38, wherein the first reflection surface 36 and the second reflection surface 38 are arranged substantially parallel to the light source side focal surface 40 of the imaging optics 22. In other words: Fig. 7 shows a light distribution, which has with a known light module with a mirror aperture with single recess, while the Fig. 8 shows a shifted by double reflection and deformed light distribution, as was generated with an embodiment of a light module according to the invention, which only by the execution of the mirror aperture with the two additionally distinguishes reflective surfaces 36 and 38 from the known light module.

In both FIGS. 7 and 8 are on the abscissa each indicate the horizontal angle of the light distribution 26. The ordinate axes represent the vertical angles. The H = 0 line marks the position of the horizon in front of the vehicle. The V = 0 line marks a straight ahead direction. The HV intersection lies in an extension of the optical axis 24 in front of the headlight. Measurement points 50 lying above the horizon, at which the overhead light distribution must assume legally prescribed illumination intensities, are in the FIGS. 7 and 8 marked by crosses. In both FIGS. 7 and 8 the cut-off point 28 is clearly visible, which according to the legal requirements must be about 1 ° below the horizontal (0 ° line in the diagram). Below the light-dark boundary 28 is the brighter area 30, which corresponds to the so-called low-beam light distribution 26. An overhead light distribution 52 is above the horizontal. The closed curves are each Isolux lines, ie lines of the same illuminance, whereby the illuminance increases from line to line from outside to inside.

Out FIG. 7 It will be seen that the aperture 18 with the recess 34 without additional reflecting surfaces 36 and 38 is not sufficient to meet the legal requirements. This is reflected in the fact that in the upper measuring points 50 the legally required illuminance levels are not reached, or in that the total overhead light distribution 52 is too close to the cut-off line 28. Such overhead lighting serves its purpose of illuminating Road signs arranged above the road are not sufficient.

In contrast, the shows FIG. 8 , whose light distribution has been generated with an embodiment of the invention, an overhead light distribution 52 with sufficient illuminance levels in the legally prescribed measuring points 50th

Claims (13)

1. Lighting module (10) for a motor vehicle's headlamp, comprising a light source (12), which emits light (14), and comprising at least one optical element (22), which carries a part of the light (14) over into a bright area of a low beam light distribution (26) produced in a field in front of the headlamp, and bordered by a bright dark boundary (28), which is produced as an image of an edge (20) of a screen that spatially limits the current of the light generated by the light source, wherein a further part of the light (14) is deflected at a first reflection surface (36) into an overhead optical path (46) and is carried over as overhead light into a less brightly illuminated area (32) of the low beam light distribution (26) lying beyond the bright dark boundary, in which a rule conforming low beam light locally has to achieve predetermined brightness values, wherein, in the overhead-optical path (46) at least one second deflection of the overhead light is effected at a second reflection surface (38), characterized in that the edge (20) of the screen is a leading edge of a screen (18) lying essentially horizontal and having a specular surface which comprises an opening (34), which is separated from the edge (20) of the screen by a partial area of the screen which lies between the opening and the edge of the screen and wherein the opening (34) is, in a direction transverse to the lighting module's optical axis, bordered by the first reflection surface (36) and the second reflection surface (38).
2. Lighting module (10) according to preceding claim 1, characterized in that the lighting module comprises at least a primary optical element (16), an imaging optical element (22) and the screen (18), wherein the primary optical element collects light (14) emitted by the light source (12) and forms a first light distribution out of it, which lies in a focal area (40) of the imaging optical element (22), wherein the imaging optical element (22) is adapted to image the first light distribution into a second light distribution (26) lying in a field in front of the lighting module (11), and wherein the edge (20) of the screen lies in the focal area (40) and borders the first light distribution and is thereby imaged as bright dark boundary (28) in the second light distribution (26), and wherein the first reflection surface (36) faces the light source (12) and the second reflection surface (38), such that the first reflection surface (36) deflects light incident from the light source (12) to the second reflection surface (38) and wherein the second reflection surface (38) faces the first reflection surface and the secondary optical element (22) and directs light incident from the first reflection surface on the secondary optical element.
3. Lighting module (10) according to claim 2, characterized in that the screen (18) is a single piece material-sticking together injection molded plastic part which can be removed from the mold without undercut.
4. Lighting module (10) according to claim 2, characterized in that the screen (18) comprises a sheet metal part which constitutes the leading edge of the screen and which is molded with plastic or connected with a plastic part, wherein the opening (34) is arranged in the plastic part.
5. Lighting module (10) according to claim 2, characterized in that the screen (18) is made from metal.
6. Lighting module (10) according to claim 5, characterized in that the screen (18) comprises an opening (34) made by punching or cutting, wherein the screen's material is cut through at three sides of the opening (34), wherein the opening (34) results from a continuous cut through the screen's material at three sides of the opening (34) and a bend of the resulting tongue over a fourth side of the opening, wherein a surface of the bent tongue constitutes the second reflection surface (38).
7. Lighting module (10) according to any of the preceding claims, characterized in that the first reflection surface (36) and/or the second reflection surface (38) is, in its vertical extent, a plane surface, respectively.
8. Lighting module (10) according to any of the claims 1 to 6, characterized in that the first reflection surface (36) and/or the second reflection surface (38) is, in its vertical extent, convexly curved.
9. Lighting module (10) according to any of claims 1 to 4, characterized in that the first reflection surface (36) and/or the second reflection surface (38) are, in its vertical extent, concavely curved.
10. Lighting module (10) according to any of the preceding claims, characterized in that the first reflection surface (36) and/or the second reflection surface (38) is, in its respective horizontal extent, a plane surface.
11. Lighting module (10) according to any of claims 1 to 9, characterized in that the first reflection surface (36) and/or the second reflection surface (38) is, in its horizontal extent, convexly curved.
12. Lighting module (10) according to any of claims 1 to 9, characterized in that the first reflection surface (36) and/or the second reflection surface (38) are, in their horizontal extent, concavely curved.
13. Lighting module (10) according to any of claims 1 to 9, characterized in that the first reflection surface and/or the second reflection surface is tilted in relation to the focal area (40).

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