EP3870894B1 - Light unit for a motor vehicle headlamp - Google Patents

Description

The invention relates to a lighting unit for a lighting device of a motor vehicle, in particular for a motor vehicle headlight, comprising: at least one low beam module for generating a low beam light distribution largely below a horizontal light-dark boundary depicted essentially in front of the motor vehicle, at least one high beam module for generating a high beam - Light distribution largely above the cut-off line, imaging optics downstream of the low-beam module and the high-beam module in the optical beam direction to generate an overall light distribution of the light modules with an optical axis and a focal surface oriented essentially normal to the optical axis, and a screen that has a screen edge has and extends to generate the horizontal light-dark boundary in a light image generated by the lighting unit substantially to the focal surface of the imaging optics.

Lighting devices and light modules for motor vehicles, which are set up to generate different light distributions and light-dark boundaries by means of appropriate control and to project them onto the road, are well known. According to a well-known principle, these different light distributions and light-dark boundaries are suppressed by means of a beam shield, with which a part of the emitted light beams is blanked out in a targeted manner. By means of the aperture, among other things, a sharp cut-off between light and dark can be obtained in a light image generated by the low-beam function, so that blinding of preceding or oncoming road users is largely avoided.

Luminous units according to the structure mentioned at the outset are well known. The low beam module, which is arranged on top in the motor vehicle when installed, and the high beam module, which is arranged on the underside in the motor vehicle when installed, interact via the common screen body and the common imaging optics, so that the imaging optics images the intermediate light images of both the low beam module and the high beam module and the screen images the beam paths of both modules affected. Lighting units of this type generally have the disadvantage in common that they do not intentionally mix or overlap the light beams of the light beams attached on the top allow the low beam module and the high beam module mounted on the underside. Because beam shields cannot be made infinitely thin and this unavoidable material thickness at the shield edge of the shield is reflected in the light image generated by the downstream imaging optics, the superimposition of the two partial light distributions (i.e. low beam and high beam) to form an overall light distribution (high beam function) creates a for the Driver visible dark gap in the area of the light-dark boundary. This disturbing inhomogeneity in the light image projected onto the road makes it difficult for the vehicle driver to recognize the surroundings, which increases the risk of an accident. In the prior art, for example in the DE 602004002043 T2 , the FR2962786A1 or the AT514161A1 To solve this known problem, the arrangement of optical elements in the area of the focal plane of the projection lens is proposed for the targeted mixing or overlapping of the light distribution generated above and below the aperture and for influencing the light-dark boundary. From the WO 2015014706 A1 another solution is known, in which a visor body made of transparent material is provided with a mirror layer, whereby the overlapping between low beam and high beam is improved by the transparent visor edge, but due to the transmission of the light at the visor edge, interfering scattered light in the area above the HH line is generated. The documents DE 10 2010 046 021 A1 and DE 10 2009 008 631 A1 disclose further lighting units for motor vehicle headlights.

Another disadvantage of known beam stops is that they can evaporate or burn out in the front area due to the magnifying glass effect. The critical area is here in that edge area of the beam diaphragm, which is in particular in the center and is formed along the focal curve of the imaging optics (e.g. projection lens).

It is an object of the invention to provide a light module of the type mentioned at the outset, comprising, among other things, a low beam module, a high beam module, a beam diaphragm designed to generate a horizontal light-dark boundary, and imaging optics, in which the above-described dark gap in the light image between the high beam and low beam is closed, the generation of disturbing scattered light in the area above the light-dark line is largely avoided, and the above-mentioned problem with regard to the burning glass effect in the critical area of the aperture edges is solved.

This object is achieved with a lighting unit for a lighting device of a motor vehicle, in particular for a motor vehicle headlight, of the type mentioned at the outset in that the screen has a substantially flat, opaque screen area and, on the screen edge in the area of the focal surface, a light-transmissive screen area with a geometric structure made of a transparent material, wherein the geometric structure comprises at least one prismatic body with an essentially triangular cross-sectional area, the at least one prismatic body extends longitudinally and the longitudinal extent runs essentially transversely to the optical axis, the at least one prismatic body has a first, a second and a third prismatic surface , wherein the first prism surface is substantially aligned with the planar opaque panel area, the second prism surface faces the opaque panel area and with the first prism surface encloses an interior angle α1 ≥ θ, and the third prism surface faces away from the opaque diaphragm area and encloses an interior angle α2 ≥ θ with the first prism surface, where θ is the critical angle of total internal reflection of the transparent material, the interior angles α1 and α2 being the same or different and with the proviso that the interior angle α1 and the interior angle α2 are not 45°.

With the screen according to the invention, the light beams generated by the low beam module are totally reflected by the prism structure on the screen edge in the area of the apron, so that the generation of disturbing scattered light in the area above the HH line is prevented, whereas those light beams generated by the high beam module pass through the prism structure in a transmissive manner and are deflected at this prism structure in such a way that the dark gap between the low beam and the high beam in the light image is closed when the high beam function is switched on (see also 7 , in which the beam paths are shown schematically, as well as a description of this).

In addition, the problem related to the burning glass effect is solved, since thanks to the transparent aperture area, which includes the geometric prism structure, the light rays, eg sunlight, are no longer absorbed, but penetrate the material and diverge. Another advantage is that the light beams that are totally reflected by the prism structure and that are generated by the low-beam module are refracted, resulting in a softer transition or a desired gradient generated at the light-dark boundary. This means that no further measures, such as a microstructure on the imaging optics, need to be taken in order to produce a desired gradient to soften the light-dark boundary.

The invention thus solves several current lighting problems of lighting units that have a low-beam module, a high-beam module and a beam shield for generating a horizontal light-dark boundary.

The diaphragm, which has an essentially flat appearance, can lie essentially horizontally in the optical axis or be slightly inclined relative to the optical axis, in a manner known per se. In certain variants, the screen can also have a kink along a horizontal line, so that the screen body does not have a continuous flat boundary surface. In addition, it is also possible to implement an increase in asymmetry in the light distribution, in that the at least one prismatic body and, if applicable, the screen body have two areas that are offset in height relative to one another, with one area being to the left and the other area to the right of the optical axis, and the Both areas are connected by an oblique transition area through which the optical axis runs (see Fig.10 and description of it).

The geometric structure may comprise a single large prism or two or more smaller prisms, the large prism or the two or more smaller prisms having to comply with the technical characteristics in terms of arrangement and internal angles defined above or in claim 1 (see also 9 and description of it). It was found that geometric structures other than the prism structure defined herein, for example a wedge shape with an internal angle α1 or an internal angle α2 of 45°, do not bring the desired advantages and, for example, total reflection also for the high beam or an undesired transmission of the low beams bring yourself

If several dirt prisms are lined up, they can have the same height. Alternatively, the heights of the lined-up prisms can increase steadily, which has the advantage that a smaller triangular prism that is closer to the focal point shades proportionately fewer high-beam light rays that are emitted by the first prism surfaces triangular prisms enter the transparent geometric structure of the aperture. For example, fewer high-beam rays are totally reflected at a second prism face of a smaller height prism closer to the focal point than enter via a first prism face of a triangular prism of greater height. The increase in the heights of the triangular prisms advantageously follows a parabolic curve.

Imaging optics for headlights are well known per se to those skilled in the art. The imaging optics can be constructed in a manner known per se and can comprise, for example, a projection lens or a multi-stage lens system; furthermore, lens-reflector combinations are also possible.

In certain variants, the geometric structure comprises at least two prismatic bodies arranged one behind the other in the optical beam direction, the first prismatic surfaces of which adjoin one another longitudinally and are aligned with one another.

The geometric structure is preferably formed from exactly two prismatic bodies arranged one behind the other in the optical beam direction, the first prismatic surfaces of which adjoin one another longitudinally and are aligned with one another; Due to the necessary geometric dimensions with regard to the prism surface and the basic thickness of the diaphragm, a geometric structure with exactly two prismatic bodies arranged in the optical direction of the beam has proven to be particularly advantageous because, on the one hand, the above-mentioned technical problems to be solved due to the distance of the geometric structure to the focal surface or .to the focal point of the imaging optics can be optimally solved, and this variant is also technically easy to implement. Undesirable color effects and the formation of a blurred light-dark boundary, which can occur with a larger number of prism bodies, e.g. with more than three prisms, due to the greater distance between the prism structures and the focal surface/focal point, are avoided with this preferred variant.

In certain variants, the at least one prism body has two areas that merge into one another in the longitudinal direction, which are offset in height from one another and are connected to one another via a preferably inclined transition area through which the optical axis runs. This makes it possible to achieve an increase in asymmetry in the light distribution (see Fig.10 and description of it).

In certain variants, the opaque panel area can at least partially have a reflective surface.

In certain design variants, the screen is made in one piece from the light-transmitting material and the opaque screen area is vaporized in a manner known per se, e.g. vaporized with a metal such as aluminum, or is mirrored.

In other variants, the opaque panel area is made of an opaque material (e.g. metal or opaque plastic) and the translucent panel area, which encompasses the geometric structure, is an insert made of the translucent material (e.g. glass or translucent/transparent plastic), or the panel is made of a a multi-component injection molding process using transparent and opaque plastic materials, e.g. by a two-component injection molding process using an opaque and a transparent plastic material.

The transparent material is preferably plastic or glass.

In certain variants, the second and/or third prismatic surface is designed to be essentially planar.

In specific variants, the second and/or third prism surface is curved, preferably the third prism surface is curved inwards. These variants have the advantage that the gradient of the light-dark boundary can also be positively influenced, so that a smooth transition of the light-dark boundary can be realized (see also 11 and 12 as well as a description of this). In certain sub-variants, the cross-sectional area of the at least one prismatic body remains the same in the longitudinal extent. In other sub-variants it can be provided that the cross-sectional area of the at least one prism body increases in the longitudinal extension; in this way, the gradient of the light-dark boundary towards the edge areas of the light distribution is further softened, so that the roadsides can be illuminated in a particularly pleasant manner for the motor vehicle driver.

In advantageous variants, the at least one low-beam module and the at least one high-beam module each comprise at least one light source, with each light source being assigned a collimator in the optical beam direction and the collimator being set up to reduce the beam angle of the light beams generated by the light source and thereby increase the beam characteristics design. In these variants, the lighting unit can be a collimator module, for example, which comprises the at least one low-beam module and the at least one high-beam module, and wherein the low-beam and high-beam modules are assigned a plurality of light sources and a collimator is connected downstream of each light source in the optical beam direction. The aperture is located downstream of the collimator module in the optical beam direction. A projection lens or a multi-stage lens system can be provided as imaging optics. The collimator can be designed, for example, as a TIR collimator lens (TIR—Total Internal Reflection). Such TIR collimator lenses are well known to a person skilled in the art (e.g. TIR lens Bern from Auer Lighting GmbH, DE); these are optically transparent bodies made of a transparent material with a refractive index greater than that of air, e.g. glass or plastic; In doing so, essentially all of the light refracted on the light coupling-out surface of the TIR collimator lens spreads further through the air, preferably in a predetermined direction with a reduction in divergence compared to the light propagation in front of the light coupling-in surface. It is also conceivable that the collimator is designed as a reflector, i.e. as a surface that reflects light (mainly visible) and deflects light rays propagating through the air in a preferably predetermined direction. However, the components of the low-beam module and/or high-beam module that shape the light distribution can also be designed in the form of polyellipsoid reflector arrangements based on the projection headlight type, as is well known to those skilled in the art.

In advantageous variants of the invention, the screen has at least one light window, with at least one light path running outwards from the low beam and/or high beam modules through the at least one light window and through the imaging optics. This development makes it possible to additionally mix the light beams that are generated by the low beam module and the high beam module in a targeted manner and to additionally minimize inhomogeneities in the light image of a high beam function. In addition, a targeted emission of light beams in areas of the light image is possible, which is usually used to illuminate traffic signs of particular meaning (so-called "sign light"). In certain sub-variants, it can be provided that the at least one light path runs outwards through the at least one light window exclusively from the low beam module through the at least one light window and through the imaging optics. In certain sub-variants, the at least one light window can be arranged in the opaque screen area of the screen and delimited by it, with the light window being designed as a recess in the opaque screen area of the screen or consisting of a light-transmitting material.

A further subject of the invention is a motor vehicle headlight which comprises at least one lighting unit according to the invention. The motor vehicle headlight is a headlight. The motor vehicle headlight according to the invention is expediently constructed according to headlight construction principles which are known per se and comprises a housing with a light exit opening which is covered by a lens or a cover plate. Modern motor vehicle headlights often have a number of light modules which, taken individually or in combination, can take on individual light functions. These light modules are often arranged in close proximity to one another in the headlight housing. In addition to a lighting unit according to the invention, which has a low beam module and a high beam module, the motor vehicle headlight according to the invention can therefore also include other light modules, e.g such as the light distribution of a daytime running light, a turn signal light, etc.

Another object of the invention is a motor vehicle comprising at least one lighting unit according to the invention and/or a motor vehicle headlight according to the invention. The term "motor vehicle" (motor vehicle) as used herein refers to single or multi-track motorized land vehicles such as motorcycles, cars, trucks and the like.

• Fig. 1 zeigt eine schematische Darstellung einer Leuchteinheit gemäß der Erfindung in perspektivischer Ansicht,
• Fig. 2 zeigt die Leuchteinheit aus Fig. 1 in Seitenansicht,
• Fig. 3 zeigt die Blende der in Fig. 1 und 2 dargestellten Leuchteinheit in perspektivischer Ansicht,
• Fig. 4 zeigt eine Draufsicht auf die Blende der in Fig. 1 und 2 dargestellten Leuchteinheit,
• Fig. 5 zeigt einen Schnitt durch die Blende der in Fig. 1 und 2 dargestellten Leuchteinheit entlang der optischen Achse,
• Fig. 6 zeigt die geometrische Prismenstruktur der Blende der in Fig. 1 und 2 dargestellten Leuchteinheit,
• Fig. 7 veranschaulicht den Strahlengang der Lichtstrahlen, die vom Abblendlichtmodul bzw. vom Fernlichtmodul emittiert werden, durch einen dreieckigen Prismenkörper einer erfindungsgemäß eingesetzten Blende,
• Fig. 8 zeigt eine Detailansicht eines Schnitts durch die Blende in Fig. 1 und Fig. 2 und veranschaulicht den Strahlengang der Lichtstrahlen, die vom Abblendlichtmodul emittiert werden, durch ein in der erfindungsgemäß eingesetzten Blende angeordnetes Lichtfenster ("sign light"),
• Fig. 8a zeigt eine vergrößerte Ansicht der Fig. 8, wobei in Fig. 8a zusätzlich der Strahlengang der Lichtstrahlen, die vom Fernlichtmodul emittiert werden, dargestellt ist,
• Fig. 9 veranschaulicht die Anordnung eines großen Dreiecksprismas bzw. mehrerer kleiner Dreiecksprismen einer erfindungsgemäß eingesetzten Blende in Bezug auf den Brennpunkt der Abbildungsoptik,
• Fig. 10 zeigt eine abgewandelte Variante einer Blende für eine erfindungsgemäße Leuchteinheit,
• Fig.11 veranschaulicht eine Gradientengestaltung zur Aufweichung der Hell-Dunkel-Grenze bei einer Abblendlichtverteilung mit Hilfe einer erfindungsgemäß eingesetzten Blende, die einen Prismenkörper mit gekrümmten Prismenflächen aufweist, und
• Fig. 12 zeigt eine beispielhafte Lichtverteilung mit Hell-Dunkel-Grenze in einem zweidimensionalen Winkelraum anhand der Linien H-H und V-V bei einer Gradientengestaltung gemäß Fig. 11.

The invention and other advantages are described in more detail below with the aid of non-limiting examples and the accompanying drawings, in which the drawings show:

• 1 shows a schematic representation of a lighting unit according to the invention in a perspective view,
• 2 shows the light unit off 1 in side view,
• 3 shows the aperture of the in Figures 1 and 2 illustrated lighting unit in a perspective view,
• 4 shows a plan view of the panel in Figures 1 and 2 illustrated lighting unit,
• figure 5 shows a section through the aperture of the in Figures 1 and 2 illustrated lighting unit along the optical axis,
• 6 shows the geometric prismatic structure of the aperture of in Figures 1 and 2 illustrated lighting unit,
• 7 illustrates the beam path of the light rays that are emitted by the low beam module or the high beam module, through a triangular prismatic body of a screen used according to the invention,
• 8 shows a detailed view of a section through the aperture in 1 and 2 and illustrates the optical path of the light rays emitted by the low beam module through a light window ("sign light") arranged in the screen used according to the invention,
• Figure 8a shows an enlarged view of the 8 , where in Figure 8a the optical path of the light beams emitted by the high-beam module is also shown,
• 9 illustrates the arrangement of a large triangular prism or several small triangular prisms of an aperture used according to the invention in relation to the focal point of the imaging optics,
• 10 shows a modified variant of a screen for a lighting unit according to the invention,
• Fig.11 illustrates a gradient design for softening the light-dark boundary in a low beam distribution with the aid of a screen used according to the invention, which has a prism body with curved prism surfaces, and
• 12 shows an exemplary light distribution with a light-dark boundary in a two-dimensional angle space based on the lines HH and VV in a gradient configuration according to FIG 11 .

It should be understood that the embodiments described herein are for illustration only and are not to be construed as limiting the invention; on the contrary, all configurations that can be found by a person skilled in the art on the basis of the description fall within the scope of protection of the invention, the scope of protection being defined by the claims.

In the figures, the same reference numbers are used for the same or comparable elements for the purpose of simpler explanation and representation. Furthermore, the reference signs used in the claims are only intended to facilitate the legibility of the claims and the understanding of the invention and in no way have any character affecting the protective scope of the invention.

1 shows a schematic representation of an embodiment variant of a lighting unit 100 according to the invention in a perspective view. 2 shows the lighting unit 100 from 1 in side view. The lighting unit 100 is provided for installation in a lighting device of a motor vehicle, in particular for a motor vehicle headlight (front headlight). Lighting unit 100 comprises a low-beam module 101, a high-beam module 102 and imaging optics in the form of a projection lens 103 with an optical axis 104 and one essentially normal to the optical axis 104, which are connected downstream of the low-beam module 101 and the high-beam module 102 to generate an overall light distribution of the light module in the optical beam direction oriented focal surface 116, also known as the Petzval surface. The low-beam module 101 is set up to generate a low-beam light distribution for the most part below a horizontal light-dark boundary that is imaged essentially in front of the motor vehicle. The high-beam module 102 is set up to generate a high-beam light distribution largely above the cut-off line. Furthermore, the lighting unit includes 100 an essentially horizontal diaphragm 105, which has a diaphragm edge 106 and extends to generate the horizontal light-dark boundary in a light image generated by the lighting unit 100 essentially up to the focal surface 116 of the downstream projection lens 103. The aperture edge 106 reaches up to the focal surface 116 or up to the focal point F of the projection lens 103 .

In the example shown, the low beam module 101 and the high beam module 102 together form a collimator module that is constructed according to generally known principles and does not need to be explained in more detail at this point (see also the description of collimators, eg TIR collimator lenses, above). The low-beam module 101 and the high-beam module 102 each comprise a plurality of light sources, not shown in detail, for example embodied as LEDs, each light source being assigned a collimator, also not shown in detail, in the optical beam direction. Each collimator is designed to reduce the divergence of the light rays generated by the light source. The collimator module includes other optical components such as lenses or reflectors. However, the low-beam module 101 and the high-beam module 102 can also be constructed according to other construction principles and are not limited to the 1 and 2 collimator structure shown schematically limited. Alternatively, the low-beam module and/or the high-beam module can have reflectors based on the classic PES (poly-ellipsoid system) headlight type that is well known in the art.

The features of the lighting unit 100 according to the invention can be found in the panel 105, which is described in more detail in the following figures.

3 shows the aperture 105 of the Figures 1 and 2 illustrated lighting unit 100 in a perspective view, 4 shows a plan view of the panel 105 and figure 5 shows a section through aperture 105. 6 shows the geometric prismatic structure of the aperture of in Figures 1 and 2 illustrated lighting unit in detail. The panel 105 has an essentially flat, opaque panel area 107 and on the panel edge 106 in the area of the focal surface 116 a light-transmitting panel area 108 with a geometric structure 109 made of a light-transmitting material. It goes without saying that the opaque screen area 107 can have a reflective surface, at least in part.

In the example shown, the opaque screen area 107 is made of metal and the light-permeable screen area 108 comprising the geometric structure 109 is an insert made of the light-permeable material. However, it is also possible to manufacture the screen 105 in one piece from the light-transmitting material and the opaque screen area 107 is vapour-deposited in a manner known per se, e.g. with a metal such as aluminum, with the light-transmissive screen area 108 being recessed and therefore not being vapor-coated. In the example shown, the translucent material is plastic. Instead of plastic, glass can also be chosen as the opaque material.

The geometric structure 109 of the exemplary aperture 105 comprises two prism bodies 110, each with a substantially triangular cross-sectional area. Each prismatic body 110 extends longitudinally and the longitudinal extent runs essentially transversely to the optical axis 104. Each prismatic body has a first, a second and a third prismatic surface, with the first prismatic surface 111 being essentially aligned with the flat, opaque screen area 107, and the second prismatic surface 112 faces the opaque diaphragm area 107 and encloses an interior angle α1 ≥ θ with the first prism surface 111, and the third prism surface 113 faces away from the opaque diaphragm area 107 and encloses an interior angle α2 ≥ θ with the first prism surface 111, where θ is the critical angle of total internal reflection of the light-transmitting material, the interior angles α1 and α2 are the same or different, and provided that the interior angle α1 and the interior angle α2 are not 45°, respectively.

7 illustrates the beam path of the light beams emitted by the low beam module or the high beam module, through one of the two prism bodies 110 of the screen 105 used according to the invention. The light beams 114 generated by the low beam module 101 enter the prism body 110 through the second prism surface 112 and are first prismatic surface 111 is totally reflected and exits through the third prismatic surface 113, so that the generation of interfering scattered light in the area above the HH line is suppressed. The light beams 117 generated by the high beam module 102 enter through the first prism surface 111, are transmitted through the prism body and are slightly deflected when exiting through the third prism surface 113, so that the gap between the low beam and the high beam in the light image of the high beam function (ie low beam and high beam are switched on) is closed.

A further development of the invention is also shown in the screen 105 . The diaphragm 105 has a light window 115 which is arranged in the opaque diaphragm area 107 of the diaphragm 105 and is delimited by this. The light window 115 is created by closing a window-shaped recess in the opaque panel area 107 with an insert plate made of transparent plastic. The light path from the low and/or high beam modules may be through the light window 115 and out through the projection lens. This development makes it possible to additionally mix the light beams that are generated by the low beam module and the high beam module in a targeted manner and to additionally minimize inhomogeneities in the light image of a high beam function. In addition, it is possible to emit light rays in a targeted manner in areas of the light image which are usually of particular importance for illuminating traffic signs (so-called “sign light”). For example, it can be provided that the light path through the light window 115 runs exclusively from the low beam module 101 through the light window 115 and through the imaging optics 101 to the outside. this is in 8 shown, which is a detailed view of a section through the aperture in 1 and 2 represents and the beam path of the light beams 114, which are emitted by the low beam module 101, through the aperture 105 arranged in the light window 115 ("sign light") illustrates. Figure 8a shows an enlarged view of the 8 , wherein the optical path of the light beams 117, which are emitted by the high-beam module 102, is also shown. The light beams 117 from the high-beam module are totally reflected at the lower boundary surface 118 of the light window 115, which is inclined relative to the optical axis 104 (in Figure 8a the totally reflected light rays are marked with 117*). Thus, the light rays 117 to the perpendicular n on the boundary surface 118 have an angle of incidence greater than the angle of total reflection. This prevents light from the high beam module from contributing to the front of the low beam distribution and thus compliance with legal requirements is made possible {USA FMVSS-108 TableXVIII UB2: measuring point [4D,V]with a light intensity specification of <12000 cd Maximum Photometric Intensity} . The necessary inclination can also be achieved by a prismatic design of this lower boundary surface 118 .

9 illustrates two exemplary alternative variants for triangular prisms of an aperture used according to the invention, namely on the one hand the arrangement of a single large triangular prism 210 with a height H and, alternatively, on the other hand the arrangement of several (five in total) small triangular prisms 310. The triangular prisms 210 or 310 are each arranged in the translucent area on the diaphragm edge of a diaphragm used according to the invention and in relation to the focal surface or focal point F of the imaging optics (e.g. a projection lens 103 1 and 2 ) positioned in the lighting unit according to the invention. Referring to the description of the prism bodies 110 above, the triangular prisms 210 or 310 each comprise a first prism surface 211 or 311, a second prism surface 212 or 312 and a third prism surface 213 or 313. As in 9 is clearly visible, the respective first prism surface 211 or 311 of the triangular prisms 210 or 310 runs essentially parallel to the optical axis 204. As shown in FIG 9 is clearly visible, the second prism faces 312 of the five small triangular prisms 310 are parallel to the second prism face 212 of the large triangular prism 210; the third prism faces 313 of the small triangular prisms 310 lie parallel to the third prism face 213 of the large triangular prism 210. The diaphragm edge 206 or 306 is defined by the prism edge formed from prism faces 211 and 213 or 311 and 313 (in the case of the small triangular prisms 310 by the outermost , the imaging optics nearest prism 310). In 9 the diaphragm edge 206 or 306 extends exactly up to the focal point F of the imaging optics/projection lens.

In the 9 The small dirt prisms 310 shown all have the same height H'. However, one skilled in the art will appreciate that the heights of the arrayed prisms can steadily increase. This has the advantage that a smaller triangular prism that is closer to the focal point shades proportionately fewer high beams that enter the transparent geometric structure of the diaphragm through the first prism surfaces of the triangular prisms. For example, fewer high-beam rays are totally reflected at a second prism face of a smaller height prism closer to the focal point than enter via a first prism face of a triangular prism of greater height. The increase in the heights of the triangular prisms advantageously follows a parabolic curve.

10 shows a modified variant of a screen 405 for a lighting unit according to the invention. The panel 405 is constructed essentially like the panel 105 described above. The panel 405 has an essentially flat, opaque panel area 407 and, on the panel edge 406 in the area of the focal surface, a transparent panel area 408 with a geometric structure 409 comprising two prismatic bodies 410 made of a transparent material. The prism body 410 have in the longitudinal direction, two regions 410a and 410b that merge into one another, which are offset in height from one another and are connected to one another via an inclined transition region 410c, through which the optical axis 404 runs. Likewise, the opaque area 407 also comprises two areas 407a and 407b which merge into one another and are offset in height relative to one another and are connected to one another via an inclined transition area 407c through which the optical axis 404 runs. This makes it possible to realize an increase in asymmetry in the light distribution. As with prism bodies 110, 210, and 310 described above, prism bodies 410 include first, second, and third prism faces (in 10 not provided with reference numbers for reasons of space), the second prism surface faces the opaque diaphragm area 407 and encloses an interior angle α1 ≥ θ with the first prism surface, and the third prism surface faces away from the opaque diaphragm area 407 and encloses an interior angle with the first prism surface α2 ≥ θ, where θ is the critical angle of total reflection of the light-transmitting material, the interior angles α1 and α2 are the same or different, and provided that the interior angle α1 and the interior angle α2 are not 45°, respectively. Like the screen 105, the screen 405 can of course also be provided with a light window 115 for generating a "sign light" function.

11 illustrates a gradient design for softening the light-dark boundary in a low beam distribution with the aid of a screen used according to the invention, which has a prismatic body with curved prismatic surfaces. 12 shows an exemplary light distribution with a light-dark boundary in a two-dimensional angle space based on the lines HH and VV in a gradient configuration according to FIG 11 . One advantage of the invention is that the light beams that are totally reflected on the prism structure and are emitted by the low beam module are refracted in slightly different directions, so that a softer transition or a legally compliant gradient value of the light-dark boundary is generated, with the light-dark boundary is primarily determined by the aperture edge 506 . A vehicle driver then perceives the light distribution without an irritating boundary line between the illuminated and dark road surface. This means that no further measures, such as a microstructure on the imaging optics, need to be taken in order to bring about a desired softening of the light-dark boundary. In the 11 an advantageous development of the invention is shown. In this development, a third prism surface 513 is a prism body 510 is curved inward, the cross-sectional area being constant in the longitudinal extension. As described above, the prismatic body 510 is a component of a screen used according to the invention, which is not shown in detail here, however. The use of a curved third prism surface 513 (and/or a curved second prism surface 512 ) has the advantage that the gradient of the light-dark boundary can be set in a particularly targeted manner and positively influenced, so that the light-dark boundary is split and is shown more broadly. For an observer or the vehicle driver, this results in a particularly soft transition of the light-dark boundary in the light image. The light path of the light beams 516 emitted by the low beam module from the curved third prism surface 513 to the passage through a projection lens 503 is in 11 illustrated by arrows. An exemplary bundle of parallel rays 516 experiences a diverging total reflection bundle of rays 516′ due to different surface normals on the curved third prism surface 513. The divergence δ is further increased by the projection lens 503 due to the different refraction of the light distribution beam 516". The first prism surface 511 leaves the prism body 510 via the curved third prism surface 513. Light is refracted at the two prism surfaces 512 and 513 according to Snell's law of refraction 12 it can be seen that the light-dark boundary HDG, which runs slightly below and parallel to the HH line, is widened wider, causing the gradient to decrease.

The invention can be modified in any manner known to those skilled in the art and is not limited to the embodiments shown. Individual aspects of the invention can also be taken up and largely combined with one another. Essential are the ideas on which the invention is based, which, in view of this teaching, can be carried out in a variety of ways by a person skilled in the art and are nevertheless maintained as such, the subject matter of the invention being defined by the appended claims.

Claims (15)

1. A lamp unit (100) for a motor-vehicle headlamp, comprising:

   at least one dipped-beam module (101) for generating a dipped-beam light distribution, for the most part below a horizontal cut-off line imaged substantially in front of the motor vehicle,

   at least one main-beam module (102) for generating a main-beam light distribution, for the most part above the cut-off line,

   an imaging optical element (103, 503) connected downstream of the dipped-beam module (101) and the main-beam module (102) in the optical beam direction for generating a total light distribution of the light modules, having an optical axis (104, 204, 404, 504) and a focal surface (116) orientated substantially normal to the optical axis (104, 204, 404, 504), and

   a diaphragm (105, 405), which has a diaphragm edge (106, 206, 306, 506) and extends essentially up to the focal surface (116) of the imaging optical element (103, 503) for generating the horizontal cut-off line in a light image generated by the lamp unit (100),

   characterized in that

   the diaphragm (105, 405) has a substantially flat opaque diaphragm region (107, 407) and has a transparent diaphragm region (108, 408) with a geometric structure (109, 409) made from a transparent material at the diaphragm edge (106, 206, 306, 506) in the region of the focal surface (116), wherein the geometric structure (109, 409) comprises at least one prism body (110, 210, 310, 410, 510) with a substantially triangular cross-sectional area, the at least one prism body (110, 210, 310, 410, 510) is elongated and the longitudinal extent runs substantially transversely to the optical axis (104, 204, 404, 504), the at least one prism body (110, 210, 310, 410, 510) has a first, a second and a third prism surface, wherein the first prism surface (111, 211, 311, 511) is substantially flush with the flat opaque diaphragm region (107, 407), the second prism surface (112, 212, 312, 512) faces the opaque diaphragm region (107, 407) and encloses an internal angle α1 ≥ θ with the first prism surface (111, 211, 311), and the third prism surface (113, 213, 313, 513) faces away from the opaque diaphragm region (107, 407) and encloses an internal angle a2 ≥ θ with the first prism surface (111, 211, 311), wherein θ is the critical angle of total internal reflection of the transparent material, the internal angles a1 and a2 are the same or different, and with the proviso that the internal angle a1 or the internal angle a2 is not 45°.
2. The lamp unit according to Claim 1, characterized in that the geometric structure (109, 409) comprises at least two prism bodies (110, 310, 410) arranged one behind the other in the optical beam direction, the first prism surfaces (111, 311) of which adjoin one another longitudinally and are flush with one another.
3. The lamp unit according to Claim 2, characterized in that the geometric structure (109, 409) comprises at least two prism bodies (110, 410) arranged one behind the other in the optical beam direction, the first prism surfaces (111) of which adjoin one another longitudinally and are flush with one another.
4. The lamp unit according to one of Claims 1 to 3, characterized in that the at least one prism body (410) has two regions (410a, 410b) transitioning into one another in the longitudinal direction, which regions are offset with respect to one another in terms of height, and are connected to one another by means of a, preferably oblique, transition region (410c), through which the optical axis (404) runs.
5. The lamp unit according to one of Claims 1 to 4, characterized in that the diaphragm is manufactured in one piece from the transparent material and the opaque diaphragm region is vapour coated, particularly metal vapour coated or mirror coated.
6. The lamp unit according to one of Claims 1 to 4, characterized in that the opaque diaphragm region is manufactured from an opaque material and the transparent diaphragm region comprising the geometric structure is an insert made from the transparent material, or the diaphragm is produced by means of a multi-component injection moulding method using transparent and opaque plastic materials.
7. The lamp unit according to one of Claims 1 to 6, characterized in that the transparent material is plastic or glass.
8. The lamp unit according to one of Claims 1 to 7, characterized in that the second and/or third prism surface (112, 113, 212, 213, 312, 313) is substantially planar.
9. The lamp unit according to one of Claims 1 to 7, characterized in that the second and/or third prism surface (512, 513) is curved, preferably the third prism surface (513) is curved inwardly.
10. The lamp unit according to one of Claims 1 to 8, characterized in that the at least one dipped-beam module (101) and the at least one main-beam module (102) comprise at least one light source in each case, wherein a collimator is assigned to each light source in the optical beam direction and the collimator is set up to reduce the size of the beam angle of the light beams generated by the light source.
11. The lamp unit according to one of Claims 1 to 10, characterized in that the diaphragm (101) has at least one light window (115), wherein at least one light path runs from the dipped-beam and/or main-beam modules (101, 102) through the at least one light window (115) and through the imaging optical element (103) to the outside.
12. The lamp unit according to Claim 11, characterized in that the at least one light path runs through the at least one light window (115) exclusively from the dipped-beam module (101) through the at least one light window (115) and through the imaging optical element (103) to the outside.
13. The lamp unit according to Claim 11 or 12, characterized in that the at least one light window (115) may be arranged in the opaque diaphragm region (107) of the diaphragm (105) and delimited by the same, wherein the light window (107) is constructed as a recess in the opaque diaphragm region of the diaphragm or consists of a transparent material.
14. A motor-vehicle headlamp having at least one lamp unit (100) according to one of Claims 1 to 13.
15. A motor-vehicle comprising at least one lamp unit (100) according to one of Claims 1 to 13 and/or a motor-vehicle headlamp according to Claim 14.

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