EP3643962A1 - Light unit for a motor vehicle headlamp - Google Patents

Abstract

The invention relates to a lighting unit (100) for a motor vehicle lighting device, comprising: a low beam module (101), a high beam module (102), an imaging optics (103, 503) downstream of the low beam module (101) and the high beam module (102) with an optical axis (104 , 204, 404, 504) and a focal surface (116) oriented normal to the optical axis (104, 204, 404, 504), and an aperture (105, 405) which has an aperture edge (106, 206, 306) and is for generating the horizontal light-dark boundary in a light image generated by the lighting unit (100) extends essentially to the focal surface (116) of the imaging optics (103, 503), the diaphragm (105, 405) having an opaque diaphragm area (107, 407) and on the diaphragm edge (106, 206, 306) in the area of the focal surface (116) has a translucent diaphragm area (108, (408) with a geometric structure (109, 409) made of a translucent material, the geometrical Structure (109, 409) comprises at least one prism body (110, 210, 310, 410, 510) with a triangular cross-sectional area, which is elongated and the longitudinal extension extends transversely to the optical axis (104, 204, 404), which has at least one prism body ( 110, 210, 310, 410, 510) has a first, a second and a third prism surface, the second prism surface (112, 212, 312, 512) with the first prism surface (111, 211, 311) includes an inside angle α1 ≥ θ , and the third prism surface (113, 213, 313, 513) with the first prism surface (111, 211, 311) includes an inside angle α2 ≥ θ, where θ is the critical angle of the total reflection of the transparent material, the inside angles α1 and α2 are the same or different , and with the proviso that the inner angle α1 or the inner angle α2 is not 45 °.

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 light module for producing a low-beam light distribution, for the most part below a horizontal cut-off line essentially mapped in front of the motor vehicle, at least one high-beam light module for generating high-beam light -Light distribution mostly above the cut-off line, an imaging optics downstream of the low beam module and the high beam module in the optical beam direction for generating 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 diaphragm that has a diaphragm edge has and extends to generate the horizontal light-dark boundary in a light image generated by the lighting unit essentially to the focal surface of the imaging optics.

Lighting devices and light modules for motor vehicles, which are set up to generate various light distributions and light-dark boundaries by means of appropriate control and to project them onto the road, are well known. These different light distributions and light-dark limits are determined according to a well-known principle by means of a beam diaphragm, with which part of the light beams emitted are selectively hidden. The aperture can be used, inter alia, to obtain a sharp cut-off in a light image generated by the low beam function, so that glare from road users traveling ahead or oncoming is largely avoided.

Luminous units according to the structure mentioned at the outset are well known. The low beam module arranged on the top side in the motor vehicle in the installed state and the high beam module arranged on the bottom side in the motor vehicle in the installed state work together via the common diaphragm body and the common imaging optics, so that the imaging optics depict the intermediate light images of both the low beam module and the high beam module and the diaphragm the beam paths of both Modules influenced. Luminaire units of this type generally have the disadvantage in common that they do not deliberately mix or overlap the light beams of the upper side Allow the low beam module and the high beam module on the underside. Because radiation diaphragms cannot be designed to be infinitely thin and this inevitable material thickness at the diaphragm edge of the diaphragm is imaged by the downstream imaging optics in the generated light image, the overlapping of the two partial light distributions (i.e. low beam and high beam) results in an overall light distribution (high beam function) for the Vehicle driver visible dark gap in the area of the cut-off. This disruptive inhomogeneity in the light image projected onto the road makes it difficult for the driver to recognize the surroundings, which increases the risk of accidents. In the prior art, for example in the DE 602004002043 T2 , the FR 2962786 A1 or the AT 514161 A1 To solve this known problem, the arrangement of optical elements in the region of the focal plane of the projection lens is proposed for deliberately mixing or overlapping the light distribution generated above and below the diaphragm and for influencing the light-dark boundary. From the WO 2015014706 A1 Another solution is known in which a diaphragm body made of transparent material is provided with a mirror layer, although the transparency of the diaphragm edge improves the overlap between low beam and high beam, but due to the transmission of the light at the diaphragm edge, disturbing scattered light in the area above the HH Line is generated.

Another disadvantage of known radiation diaphragms is that they can evaporate or burn out in the front area due to the burning glass effect. The critical area is located in that, in particular in the middle, edge area of the radiation diaphragm, which is shaped along the focal curve of the imaging optics (e.g. projection lens).

It is an object of the invention to provide a light module according to the type mentioned at the outset, including, inter alia, a low beam module, a high beam module, a beam diaphragm set up to produce a horizontal light dark boundary, and an imaging optics in which the dark gap in the light image between the high beam and the beam described above Low beam is closed, the generation of disturbing stray 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 diaphragm edge 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 diaphragm has a substantially flat, opaque diaphragm area and on the diaphragm edge in the area of the focal surface a translucent diaphragm area with a geometric structure made from one has translucent material, wherein the geometric structure comprises at least one prism body with a substantially triangular cross-sectional area, the at least one prism body is elongated and the longitudinal extension is substantially transverse to the optical axis, the at least one prism body has a first, a second and a third prism surface , wherein the first prism surface is substantially aligned with the flat opaque area, the second prism area towards the opaque area and includes an inner angle α1 ≥ θ with the first prism surface, and the third prism surface faces away from the opaque aperture area and includes an inner angle α2 ≥ θ with the first prism surface, where θ is the critical angle of the total reflection of the translucent material, the inner angles α1 and α2 are the same or different, and with the proviso that the inside angle α1 and the inside angle α2 is not 45 °.

In the diaphragm according to the invention, the light beams generated by the low beam module are totally reflected by the prism structure on the diaphragm 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 and are deflected on this prism structure in such a way that the dark gap between the low beam and the high beam in the photograph is closed when the high beam function is switched on (see also Fig. 7 , in which the beam paths are shown schematically, as well as a description of this).

In addition, the problem with regard to the burning glass effect is solved because, thanks to the transparent diaphragm area, which comprises the geometric prism structure, the light rays, for example sunlight, are no longer absorbed, but penetrate the material and diverge. Another advantage is that the light rays totally reflected on the prism structure, which are generated by the low beam module, are refracted, so that a softer transition or a desired gradient is generated at the cut-off line. Thus, no further measures, for example a microstructure on the imaging optics, need to be taken in order to generate a desired gradient in order to soften the light-dark boundary.

The invention thus solves several current lighting problems of lighting units which have a low beam module, a high beam module and a beam diaphragm for generating a horizontal cut-off line.

The diaphragm, which has an essentially flat appearance, can lie essentially horizontally in the optical axis in a manner known per se or can be slightly inclined with respect to the optical axis. 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 prism body and, if appropriate, the diaphragm body have two regions offset in height from one another, one region being on the left and the other region on 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).

The geometric structure can comprise a single large prism or two or more smaller prisms, the large or the two or more smaller prisms having to fulfill the technical features defined above or in claim 1 with regard to the arrangement and the internal angles (see also Fig. 9 and description). It was found that geometrical structures other than the prism structure defined here, for example a wedge shape with an inside angle α1 or an inside angle α2 of 45 °, do not bring about the desired advantages and, for example, total reflection also for the high beam or an undesired transmission of the low beam bring oneself.

If several dirt prisms are lined up, they can have the same height. Alternatively, the heights of the prisms strung together can increase steadily, which has the advantage that a smaller triangular prism, which is closer to the focal point, shadows proportionately fewer high beam rays which are caused by first prism surfaces of the Triangular prisms enter the transparent geometric structure of the panel. For example, fewer high-beam beams are totally reflected on a second prism surface of a prism that is closer to the focal point and has a lower height, and they enter via a first prism surface of a triangular prism that has a higher height. The increase in the heights of the triangular prisms advantageously follows a parabolic curve.

Imaging optics for headlights are well known 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; lens-reflector combinations are also possible.

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

The geometric structure is preferably formed from exactly two prism bodies arranged one behind the other in the optical beam direction, the first prism surfaces of which adjoin one another longitudinally and are in alignment 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 prism bodies arranged in the optical beam direction has proven to be particularly advantageous, because on the one hand the technical tasks to be solved due to the distance of the geometric structure from the focal surface or can be optimally resolved at the focal point of the imaging optics, and this variant can also be technically easily implemented. Undesirable color effects and the formation of a blurred light-dark boundary, which may be the case with a higher number of prism bodies, e.g. in the case of more than three prisms due to the greater distance between the prism structures and the focal surface / focal point, this preferred variant avoids this.

In certain variants, the at least one prism body has two mutually merging regions in the longitudinal direction, which are offset in height and are connected to one another via a preferably oblique transition region through which the optical axis runs. This makes it possible to achieve an asymmetry in the light distribution (see Fig. 10 and description).

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

In certain versions, the screen is made in one piece from the translucent material and the opaque area is vapor-coated in a manner known per se, e.g. steamed with a metal such as aluminum, or 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 includes the geometric structure, is an insert made of the translucent material (e.g. glass or translucent / transparent plastic), or the panel is by means of a multi-component injection molding process using translucent and opaque plastic materials, for example by means of a two-component injection molding process using an opaque and a permeable plastic material.

The transparent material is preferably plastic or glass.

In certain variants, the second and / or third prism surface is 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 be influenced positively, so that a soft transition of the light-dark boundary can be achieved (see also 11 and 12 and description of this). With certain sub-variants, the cross-sectional area of the at least one prism body is constant in the longitudinal extent. In the case of other sub-variants, it can be provided that the cross-sectional area of the at least one prism body increases in the longitudinal extent; In this way, the gradient of the light-dark boundary towards the edge regions of the light distribution is further softened, so that the illumination of the road edges can be made particularly pleasant for the driver of the motor vehicle.

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, a collimator being assigned to each light source in the optical beam direction and the collimator being set up to reduce the radiation angle of the light beams generated by the light source and thereby to increase the radiation characteristic shape. In these variants, the lighting unit can be, for example, a collimator module, 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 connected 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 which are made of a transparent material whose refractive index is greater than the refractive index of the air, e.g. made of glass or plastic; the essentially all of the light refracted at the light coupling-out surface of the TIR collimator lens continues to spread through the air, preferably in a predetermined direction while reducing the 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 (above all visible) light reflecting surface, which deflects light rays propagating in air in a preferably predetermined direction. The light distribution-shaping components of the low beam module and / or high beam module can, however, also be designed in the form of polyellipsoid reflector arrangements of the projection headlight type, as is well known to the person skilled in the art.

In advantageous variants of the invention, the diaphragm has at least one light window, at least one light path from the low beam and / or high beam modules running through the at least one light window and through the imaging optics to the outside. This further 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 rays in areas of the light image is possible, which is usually of particular importance for illuminating traffic signs Are meaning (so-called "sign light"). In certain sub-variants, it can be provided that the at least one light path through the at least one light window runs exclusively from the low beam module through the at least one light window and through the imaging optics to the outside. In certain sub-variants, the at least one light window can be arranged in and delimited by the opaque diaphragm area of the diaphragm, the light window being designed as a recess in the opaque diaphragm area of the diaphragm or consisting of a translucent material.

Another object 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 front headlight. The motor vehicle headlamp according to the invention is expediently constructed according to known headlamp construction principles and comprises a housing with a light exit opening which is covered by a diffusing screen or a cover disk. Modern motor vehicle headlights often have a plurality of light modules which, taken on their own or in combination, can take over individual light functions. These light modules are often arranged in close proximity to one another in the headlight housing. The motor vehicle headlight according to the invention can therefore, in addition to a lighting unit according to the invention, which has a low beam module and a high beam module, therefore also comprise further light modules, e.g. a daytime running light unit, a flashing light unit etc. Accordingly, in addition to the low beam or high beam distribution, further light distributions can be generated by the further light modules, such as the light distribution of a daytime running light, a flashing 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" as used herein refers to single or multi-lane motorized land based vehicles such as motorcycles, automobiles, 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 further advantages are described in more detail below with the aid of non-restrictive examples and accompanying drawings, the drawings showing:

• Fig. 1 shows a schematic representation of a lighting unit according to the invention in perspective view,
• Fig. 2 shows the light unit Fig. 1 in side view,
• Fig. 3 shows the aperture of the in 1 and 2 illustrated lighting unit in perspective view,
• Fig. 4 shows a top view of the aperture of the in 1 and 2 illustrated lighting unit,
• Fig. 5 shows a section through the aperture of the in 1 and 2 light unit shown along the optical axis,
• Fig. 6 shows the geometric prism structure of the aperture of the in 1 and 2 illustrated lighting unit,
• Fig. 7 illustrates the beam path of the light beams, which are emitted by the low beam module or by the high beam module, through a triangular prism body of a diaphragm used according to the invention,
• Fig. 8 shows a detailed view of a section through the aperture in 1 and 2 and illustrates the beam path of the light beams which are emitted by the low beam module through a light window arranged in the diaphragm used according to the invention ("sign light"),
• Fig. 8a shows an enlarged view of the Fig. 8 , where in Fig. 8a the beam path of the light beams emitted by the high-beam module is also shown,
• Fig. 9 illustrates the arrangement of a large triangular prism or a plurality of small triangular prisms of an aperture used according to the invention with respect to the focal point of the imaging optics,
• Fig. 10 shows a modified variant of a panel 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 an aperture used according to the invention, which has a prism body with curved prism surfaces, and
• Fig. 12 shows an exemplary light distribution with light-dark boundary in a two-dimensional angular space using the lines HH and VV in a gradient design according to Fig. 11 .

It is understood that the embodiments described here are only for illustration and are not to be interpreted as restricting the invention; rather, the scope of the invention includes all configurations which the person skilled in the art can find from the description, the scope of protection being defined by the claims.

In the figures, the same reference numerals are used for the same or comparable elements for the purpose of easier explanation and illustration. The reference symbols 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 a character which would impair the scope of the invention.

Fig. 1 shows a schematic representation of an embodiment variant of a lighting unit 100 according to the invention in a perspective view. Fig. 2 shows the lighting unit 100 Fig. 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). The lighting unit 100 comprises a low-beam light module 101, a high-beam light module 102 and an imaging optics downstream of the low-beam light module 101 and of the high-beam module 102 in order to produce an overall light distribution of the light module in the optical beam direction in the form of a projection lens 103 with an optical axis 104 and an essentially normal to the optical axis 104 oriented focal surface 116, also known as the Petzval surface. The low-beam light module 101 is configured to generate a low-beam light distribution for the most part below a horizontal cut-off line essentially shown in front of the motor vehicle. The high beam module 102 is configured to generate a high beam light distribution for the most part above the cut-off line. The lighting unit also includes 100 an essentially horizontally lying 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 diaphragm edge 106 extends to the focal surface 116 or to the focal point F of the projection lens 103.

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

Fig. 3 shows the aperture 105 of the in 1 and 2 illustrated lighting unit 100 in perspective view, Fig. 4 shows a top view of the aperture 105 and Fig. 5 shows a section through aperture 105. Fig. 6 shows the geometric prism structure of the aperture of the in 1 and 2 illustrated lighting unit in detail. The diaphragm 105 has a substantially flat opaque diaphragm area 107 and on the diaphragm edge 106 in the area of the focal surface 116 a translucent diaphragm area 108 with a geometric structure 109 made of a translucent material. It goes without saying that the opaque diaphragm area 107 can at least partially have a reflective surface.

In the example shown, the opaque diaphragm area 107 is made of metal and the translucent diaphragm area 108 comprising the geometric structure 109 is an insert made of the translucent material. However, it is also possible to manufacture the diaphragm 105 in one piece from the translucent material and the opaque diaphragm area 107 is vapor-coated in a manner known per se, e.g. sputtered with a metal such as aluminum, the translucent aperture area 108 being left out and therefore not sputtered. 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 diaphragm 105 comprises two prism bodies 110, each with an essentially triangular cross-sectional area. Each prism body 110 is elongated and the longitudinal extent extends essentially transversely to the optical axis 104. Each prism body has a first, a second and a third prism surface, the first prism surface 111 being essentially flush with the flat opaque area 107, the second prism surface 112 faces the opaque aperture region 107 and includes an inner angle α1 ≥ θ with the first prism surface 111, and the third prism surface 113 faces away from the opaque aperture region 107 and includes an interior angle α2 ≥ θ with the first prism surface 111, where θ is the critical angle of the total reflection of the translucent material, the interior angles α1 and α2 are the same or different, and with the proviso that the interior angle α1 and the interior angle α2 is not 45 °.

Fig. 7 illustrates the beam path of the light beams, which are emitted by the low beam module or by the high beam module, through one of the two prism bodies 110 of the diaphragm 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 become on the first prism surface 111 totally reflected and emerge through the third prism surface 113, so that the generation of disturbing scattered light in the area above the HH line is prevented. The light beams 117, which are 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 photograph of the high beam function (ie low beam and high beam is switched on) is closed.

A further development of the invention is also shown in the panel 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 the latter. The light window 115 is created in that a window-shaped recess in the opaque panel area 107 is closed with an insert made of transparent plastic. The light path from the low beam and / or high beam modules can run out through the light window 115 and through the projection lens. This further 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 rays in areas of the light image is possible, 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 Fig. 8 shown, which is a detailed view of a section through the aperture in 1 and 2 and illustrates the beam path of the light beams 114, which are emitted by the low-beam light module 101, through the light window 115 (“sign light”) arranged in the diaphragm 105. Fig. 8a shows an enlarged view of the Fig. 8 , in addition, the beam path of the light beams 117, which are emitted by the high beam module 102, is shown. The light beams 117 from the high beam module are totally reflected at the lower boundary surface 118 of the light window 115 inclined to the optical axis 104 (in Fig. 8a the totally reflected light rays are marked with 117 *). Thus, the light rays 117 to the plumb line n at the interface 118 have an angle of incidence greater than the angle of the total reflection. This prevents light from the high beam module from contributing to the apron in the low beam distribution and thus compliance with legal requirements is made possible. {USA FMVSS-108 TableXVIII UB2: measuring point [4D, V] with a specification for the light intensity <12000 cd Maximum Photometric Intensity} . The necessary inclination can also be achieved by a prismatic design of this lower interface 118.

Fig. 9 illustrates two exemplary alternative variants for triangular prisms of a diaphragm 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 and 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 the focal point F of the imaging optics (for example 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 and 310 each include a first prism surface 211 and 311, a second prism surface 212 and 312 and a third prism surface 213 and 313, respectively Fig. 9 is clearly visible, the first prism surface 211 and 311 of the triangular prisms 210 and 310 runs essentially parallel to the optical axis 204 Fig. 9 As can be clearly seen, the second prism surfaces 312 of the five small triangular prisms 310 lie parallel to the second prism surface 212 of the large triangular prism 210; the third prism surfaces 313 of the small triangular prisms 310 lie parallel to the third prism surface 213 of the large triangular prism 210. The diaphragm edge 206 or 306 is defined by the prism edge formed from prism surfaces 211 and 213 or 311 and 313 (for the small triangular prisms 310 by the outermost one , prism 310 closest to the imaging optics). In Fig. 9 the aperture edge 206 or 306 extends exactly to the focal point F of the imaging optics / projection lens.

In the Fig. 9 Small dirt prisms 310 shown all have the same height H '. However, a person skilled in the art will understand that the heights of the prisms lined up can increase steadily. This has the advantage that a smaller triangular prism, which is closer to the focal point, shadows proportionately fewer high-beam beams which enter the transparent geometric structure of the diaphragm through first prismatic surfaces of the triangular prisms. For example, fewer high-beam beams are totally reflected on a second prism surface of a prism that is closer to the focal point and has a lower height, and they enter via a first prism surface of a triangular prism that has a higher height. The increase in the heights of the triangular prisms advantageously follows a parabolic curve.

Fig. 10 shows a modified variant of an aperture 405 for a lighting unit according to the invention. The aperture 405 is constructed essentially like the aperture 105 described above. The diaphragm 405 has a substantially flat opaque diaphragm area 407 and on the diaphragm edge 406 in the area of the focal surface a translucent diaphragm area 408 with a geometric structure 409 comprising two prismatic bodies 410 made of a translucent material. The prism body 410 have in the longitudinal direction there are two merging areas 410a and 410b which are offset in height from one another and are connected to one another via an oblique transition area 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, are connected to one another via an inclined transition area 407c through which the optical axis 404 runs. This makes it possible to achieve an increase in asymmetry in the light distribution. As with the prism bodies 110, 210 and 310 described above, the prism bodies 410 comprise a first, a second and a third prism surface (in Fig. 10 not provided with reference numerals for reasons of space), the second prism surface faces the opaque aperture region 407 and includes an inner angle α1 θ with the first prism surface, and the third prism surface faces away from the opaque aperture region 407 and closes an interior angle with the first prism surface α2 ≥ θ, where θ is the critical angle of the total reflection of the translucent material, the interior angles α1 and α2 are the same or different, and with the proviso that the interior angle α1 and the interior angle α2 is not 45 °. Like the diaphragm 105, the diaphragm 405 can of course also be provided with a light window 115 for generating a “sign light” function.

Fig. 11 illustrates a gradient design for softening the light-dark boundary in a low beam distribution with the aid of an aperture used according to the invention, which has a prism body with curved prism surfaces. Fig. 12 shows an exemplary light distribution with light-dark boundary in a two-dimensional angular space using the lines HH and VV in a gradient design according to Fig. 11 . An advantage of the invention is that the light rays totally reflected on the prism structure, which are emitted by the low beam module, are refracted in slightly different directions, so that a softer transition or a lawful gradient value of the cut-off line is generated, whereby the cut-off 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. Thus, no further measures, for example a microstructure on the imaging optics, have to be taken in order to bring about a desired softening of the light-dark boundary. In the Fig. 11 an advantageous development of the invention is shown. In this development, a third prism surface 513 is a prism body 510 curved inwards, the cross-sectional area being constant in the longitudinal extent. The prism body 510 is, as described above, a component of a diaphragm used according to the invention, which is not shown 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 influenced positively, so that the light-dark boundary is split and is shown wider. For a viewer or the vehicle driver, this results in a particularly smooth transition of the cut-off line in the photograph. 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 shown in FIG Fig. 11 illustrated with arrows. An exemplary parallel beam 516 experiences a diverging total reflection beam 516 'due to different surface normals on the curved third prism surface 513. The divergence δ is further increased by the projection lens 503 owing to the different refraction of the light distribution beam 516 ". The same applies analogously to light beams that enter the prism body 510 via a generally curved second prism surface 512 and after total reflection on the generally planar one first prism surface 511 leave 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 Fig. 12 it can be seen that the cut-off line HDG, which runs slightly below and parallel to the HH line, is widened, as a result of which the gradient decreases.

The invention can be modified in any manner known to the person skilled in the art and is not restricted to the embodiments shown. Individual aspects of the invention can also be taken up and largely combined with one another. What is 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 nevertheless remain as such.

Claims (15)

Lighting unit (100) for a lighting device of a motor vehicle, in particular for a motor vehicle headlight, comprising: at least one low-beam light module (101) for generating a low-beam light distribution for the most part below a horizontal cut-off line that is essentially shown in front of the motor vehicle, at least one high beam module (102) for generating a high beam light distribution mostly above the cut-off line, imaging optics (103, 503) connected downstream of the low beam module (101) and the high beam module (102) in the optical beam direction to produce an overall light distribution of the light modules, with an optical axis (104, 204, 404, 504) and one that is essentially normal to the optical axis ( 104, 204, 404, 504) oriented focal surface (116), and a diaphragm (105, 405), which has a diaphragm edge (106, 206, 306, 506) and, in order 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 imaging optics (103 , 503) extends, characterized in that the diaphragm (105, 405) has a substantially flat opaque diaphragm area (107, 407) and on the diaphragm edge (106, 206, 306, 506) in the area of the focal surface (116) a translucent diaphragm area (108, 408) with a geometric structure (109, 409) made of a translucent material, the geometric structure (109, 409) comprising 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 is essentially transverse to the optical axis (104, 204, 404, 504), the at least one prism body (110, 210, 310, 410, 510) a first, a second and has a third prism surface, the first Prism surface (111, 211, 311, 511) essentially flush with the flat opaque diaphragm area (107, 407), the second prism surface (112, 212, 312, 512) faces the opaque diaphragm area (107, 407) and with the first prism area ( 111, 211, 311) includes an inside angle α1 ≥ θ, and the third prism surface (113, 213, 313, 513) faces away from the opaque diaphragm area (107, 407) and one with the first prism surface (111, 211, 311) Includes interior angle α2 ≥ θ, where θ is the critical angle of the total reflection of the translucent material, the interior angles α1 and α2 are the same or different, and with the proviso that the interior angle α1 and the interior angle α2 is not 45 °. Luminous 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 and are aligned with one another. Luminous unit according to claim 2, characterized in that the geometric structure (109, 409) is formed from exactly 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 lengthways and are flush with one another. Luminous unit according to one of Claims 1 to 3, characterized in that the at least one prism body (410) has two regions (410a, 410b) which merge into one another in the longitudinal direction and are offset in height and via a preferably oblique transition region (410c ) through which the optical axis (404) runs are interconnected. Lighting unit according to one of claims 1 to 4, characterized in that the panel is made in one piece from the translucent material and the opaque panel area is vapor-coated, in particular metal-coated, or is mirrored. Luminous unit according to one of claims 1 to 4, characterized in that the opaque diaphragm area is made of an opaque material and the translucent diaphragm area comprising the geometric structure Insert is made of the translucent material, or the panel is made by a multi-component injection molding process using translucent and opaque plastic materials. Lighting unit according to one of claims 1 to 6, characterized in that the translucent material is plastic or glass. Lighting 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. Lighting 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 inwards. Lighting unit according to one of claims 1 to 8, characterized in that the at least one low beam module (101) and the at least one high beam module (102) each comprise at least one light source, a collimator being assigned to each light source in the optical beam direction and the collimator being set up for this purpose to reduce the angle of radiation of the light rays generated by the light source. Lighting unit according to one of claims 1 to 10, characterized in that the diaphragm (101) has at least one light window (115), at least one light path from the low-beam and / or high-beam modules (101, 102) through the at least one light window (115) and runs outwards through the imaging optics (103). Lighting unit according to claim 11, characterized in that the at least one light path through the at least one light window (115) extends exclusively from the low beam module (101) through the at least one light window (115) and through the imaging optics (103). Lighting unit according to claim 11 or 12, characterized in that the at least one light window (115) is arranged in the opaque diaphragm area (107) of the diaphragm (105) and is delimited by the latter, the light window (107) being a recess in the opaque area of the diaphragm is formed or consists of a translucent material. Motor vehicle headlight with at least one light unit (100) according to one of claims 1 to 13. Motor vehicle comprising at least one lighting unit (100) according to one of Claims 1 to 13 and / or a motor vehicle headlight according to Claim 14.

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