EP2578929B1 - Arrangement of overhead elements on a projection lens of a motor vehicle headlamp - Google Patents

Description

The present invention relates to a method according to the preamble of claim 1 and a headlight according to the independent device claim.

Such a method and such a headlight are from the DE 20 2005 004 080 U1 known.

The 10 2009 020 593 A1 shows, in particular, a motor vehicle projection headlight, which is set up to project an edge, which limits a luminous flux of a light source of the headlight, as a light-dark boundary of a light distribution generated in advance by the headlight, and which has a projection lens with geometric overhead elements which are implemented as local deformations of an interface of the projection lens and which are set up to emit light above the light-dark boundary direct overhead area of the light distribution. By instructing to discretely distribute more than a hundred such overhead elements over the interface of the projection lens, this document implicitly also shows a method according to the preamble of claim 1.

The light-dark boundary of a low beam distribution delimits a lower, brightly illuminated area of the light distribution from an upper, darker area. As is known, the upper area is dimly illuminated in order to reduce glare to other road users, in particular oncoming traffic.

In the ECE legal area, certain location-dependent illuminance levels are required for motor vehicle headlights. These are formulated separately for low and high beam using numerous measuring points. The present invention relates in particular to the measurement points prescribed for a low beam. A representation of measuring points for the illuminance can for example Automotive paperback, 24th edition, April 2002, ISBN 3-528-13876-9, page 816 be removed.

In addition to predefined illuminance levels of the light striking the street, that is to say the light area of the light distribution below the light-dark boundary, special requirements for illuminance levels above the light-dark limit must also be met. This area of light distribution above the light-dark boundary is also referred to as the overhead or signlight area (derived from the visibility of the traffic signs).

The legal measuring points in this area extend up to 4 ° above the horizon and are indicated by Characterized minimum or maximum values as well as so-called total values for the illuminance that is set in each of the measuring points.

Due to the system, projection systems with low beam function have very little light above the cut-off line, since this overhead area is effectively shadowed by the aperture used in projection systems. It is this diaphragm, the edge of which is projected as a light-dark boundary into the light distribution in front of the headlight, in particular in front of the vehicle.

Because of the effective shading, special measures are necessary to adequately illuminate these measuring points with suitable amounts of light. At the same time, attention must be paid to compliance with the prescribed maximum values near the cut-off line. These maximum values are also referred to as so-called glare values.

In known devices, this is achieved in that local deformations are arranged on the front (light exit) or rear (light entry) interface of the projection lens, which deflect light into the Signlight measuring points due to their additional prismatic, that is, light-refractive, effect. This is for example from the DE 10 2004 024 107 A1 known, which in this context has a horizontally extending in the middle of the lens interface cylinder portion. From the DE 103 094 34 a projection lens with a local depression serving this purpose is known in the lower region of the lens. This device is similar to the subject of US 7 040 789 B2 , which uses a kind of ribs, which are arranged all around the lens edge. Snake-like elements are also known on the Front surface of the projection lens as in the US 7 025 483 B2 to be discribed.

A local deformation of the lower lens area of the projection lens with an additional, horizontally scattering superstructure is also from the utility model DE 20 2005 004 080 known.

It is also known to provide the lens rear surface with prismatic deflecting elements for generating light for a secondary lighting area, such as the DE 10 2004 024 107 A1 can be seen. The one already mentioned at the beginning DE 10 2009 020 593 uses many small prismatic elements regularly distributed on the projection lens to deflect light into an overhead area

Geometric surface modifications are also known, but they are not primarily aimed at illuminating overhead measurement points: These include, for example, lenses with horizontal and oblique wave structures. This is known both for the European ECE legal area and for the American SAE legal area. As an example, refer to the DE 40 31 352 A1 referred. Lenses with cylindrical elements are described in utility model G 90 00 395.

In addition, the use of additional reflective components in the projection system is possible, such as the use of reflective diaphragms arranged transversely to the direction of light. An example of a reflective additional component which is arranged directly behind the projection lens is the US 5,307,247 refer to.

Other solutions are also conceivable, such as openings in the dipped beam. Such openings can also be combined with additional, reflective components. An opening in the panel is, for example, in the KR 10 2009 0064 724 A and in the KR 10 2010 0069 471 A described.

Any deformation of a light entry interface or a light exit interface of the projection lens, which is used to generate overhead light, is clearly perceptible, since the generation of overhead light requires relatively large deflection angles of at least several degrees. There can therefore be no macroscopic, "invisible" solution on the projection lens.

This is important in view of the fact that design is increasingly becoming the focus of current headlights. This means that the acceptance of previously known overhead solutions on projection lenses is decreasing on the side of headlamp customers. The appearance of headlamps is being assessed more and more critically by customers, so that the appearance and, in part, also the function of the headlamps are subject to increasingly higher demands.

The appearance of the projection lens when it is switched on also plays an increasing role, so that solutions in which parts of the lens are illuminated in a precise, selective manner are not desired.

Accordingly, many previous solutions can no longer be used because they are no longer accepted by customers.

Legislation is currently expected to tighten the regulations for overhead values, some of which cannot be met with previous solutions. On the one hand, higher amounts of light are prescribed at individual measuring points in the overhead area. On the other hand, there is a parallel requirement to keep the glare values within the previously permitted limits. In addition, new measuring points to be illuminated have been introduced. Previous solutions lead to an increase in the glare values beyond the permitted limits if the overhead light level increases, so that such headlights may no longer be permitted.

Furthermore, previous solutions sometimes result in side effects in the light distribution: Since light has to be taken from the normal low beam distribution for the overhead portion, this can lead to inhomogeneities within the light distribution on the street, which are perceived as holes, i.e. as clearly visible dark spots will.

Previous solutions for overhead light also have the disadvantage that they are usually only compatible with a specific projection system. If these solutions are used in another projection system, the targets regarding measured values to be achieved, neutrality with regard to the performance and homogeneity of the light distribution are generally not achieved. The overhead solution then does not fit.

The process aspects of the invention proposed here are distinguished by the characterizing features of claim 1.

As a result, the method aspects of the invention provide a modular principle that gradually leads to an overhead solution that can be individually adapted to each projection system.

Suitable positions for the geometric elements are found first. The size and design of the geometric elements for generating overhead light can then be easily dimensioned precisely by means of lighting simulation and analysis. In this way, compliance with the required measurement values, maintaining the performance of the system and the homogeneity of the light distribution can be simultaneously optimized and achieved for each projection system.

For the purpose of generating light in the overhead area of the low beam of projection systems, exactly adaptable, geometric elements on the surface of the projection lens are proposed for this purpose, which due to their small size have an aesthetically pleasing and desired appearance.
In its device aspects, the invention is characterized by the characterizing features of claim 8.

Due to the two symmetrically arranged partial areas and the one centrally arranged partial area, an inconspicuous, wanted and in particular aesthetically appealing appearance of the entire lens is achieved due to its symmetry, so that the lens can be regarded as a design element. The consciously chosen appearance of the overhead geometries avoids the subjective impression of a defective lens, especially due to its symmetry.

Further advantages result from the dependent claims, the description and the attached figures.

It goes without saying that the features mentioned above and those yet to be explained below can be used not only in the combination indicated in each case, but also in other combinations or on their own without departing from the scope of the present invention.

drawings

Fig. 1

eine Schnittdarstellung eines Kraftfahrzeugscheinwerfers als technisches Umfeld der Erfindung;

Fig. 2

einen Querschnitt durch eine Ausgestaltung eines Overhead-Elements aus der Fig. 1;

Fig. 3

eine Draufsicht auf eine mit Overhead-Elementen ausgestattete Projektionslinse; und

Fig. 4

eine Lichtverteilung mit Overheadlicht, das mit einem nach dem erfindungsgemäßen Verfahren erzeugten Scheinwerfer erzeugt worden ist.

Exemplary embodiments of the invention are shown in the drawings and are explained in more detail in the description below. The same reference numerals in the different figures denote the same elements. In each case in schematic form:

Fig. 1

a sectional view of a motor vehicle headlight as a technical environment of the invention;

Fig. 2

a cross section through an embodiment of an overhead element from the Fig. 1 ;

Fig. 3

a plan view of a projection lens equipped with overhead elements; and

Fig. 4

a light distribution with overhead light, which has been generated with a headlight generated according to the inventive method.

Fig. 1 shows in detail a schematic representation of an embodiment of a headlight 10 in a longitudinal section. The headlight 10 has a housing 12 with a light exit opening, which from a transparent cover 14 is covered. A projection module 16 is arranged in the housing 12. The projection module 16 has a light source 18 and a reflector 20, which reflects at least part of the light emanating from the light source 18 and bundles it into a focal region. The reflector 20 preferably has the shape of an ellipsoid of revolution or an ellipsoid-like free form deviating therefrom. The light source 18 is arranged in a first focal point F _{1 of} the reflector 20. A diaphragm arrangement 22 shields at least part of the luminous flux emanating from the reflector 20. The aperture 22 is shown in the Fig. 1 arranged in a plane that runs perpendicular to an optical axis 24 and through the second focal point F _{2 of} the reflector 20. The aperture 22 can also be arranged lying parallel to the optical axis 24 and have a light reflecting surface. In addition to the vertical extension, the diaphragm can also have a certain extent parallel to the optical axis, so that it is to a certain extent a thick diaphragm. In any case, however, the diaphragm edge lying in the region of the second focal point F2 or a diaphragm edge lying in the region of a second focal plane is projected as a light-dark boundary into the apron of the headlight 10.

The projection takes place through a projection lens 26. In the exemplary embodiment shown, the projection lens 26 is attached to a front edge of the reflector 20 by means of a lens holder (not shown) which engages a collar 28. The lens 26 is made of any light-permeable material, for example a temperature-resistant plastic or glass, and has a substantially flat light entry interface 30 on the side facing the light source 18 and a convex light exit interface on its opposite side 32 on. Of course, the interface 30 can also be concave or convex.

The light module 16 is used to generate a light distribution with a cut-off line, preferably a low beam distribution or a fog light distribution. The light-dark boundary results as a projection of the edge of the diaphragm arrangement 22 located in the region of the second focal point F2 of the reflector 20 in the light distribution generated by the light module 6 on the road. The direction x is essentially parallel to the direction of the optical axis 24, which corresponds to the main emission direction of the luminous flux, and, when the headlight 10 is installed, parallel to the longitudinal axis of the vehicle. The z direction is parallel to the vertical axis of the vehicle and points upwards. The y direction is accordingly perpendicular to the plane of the drawing and points into it. In the lower half of the projection lens 26, the light exit interface 32 has a partial region 58 of the interface with a grouping of up to twenty individual overhead elements 34, which are implemented in the form of local deformations of the interface, here in the form of projections . Another grouping of such or similar overhead elements is the subject of Fig. 1 also arranged laterally approximately at the level of the optical axis 24 in a partial region 54 of the interface 32.

Figure 2 shows a cross section through a single overhead element 34 of the lower grouping in the partial area 58 according to Figure 1 as he is with one in the drawing plane of the Fig. 1 performed cut results qualitatively. The cross section of the individual overhead element 34 is divided into a first section 42, which lies between points 38 and 40, and a second section 46 between points 40 and 44. Below the vertical extension or length of the individual overhead element is the distance between points 38 and 44 in the Fig. 2 Roger that. In a preferred embodiment, the curvature of the first section 42 corresponds to the curvature of a cylinder jacket. The surface of the individual overhead element 34 belonging to the section 42 corresponds to part of an outer surface of an imaginary cylinder, the axis of which, when the headlight 10 is installed in the vehicle, lies parallel to the base area of the vehicle within the lens 26.

Alternatively, the contour of section 42 can also be generated as a spline function or as a comparable mathematical function or as a combination of such functions. A continuously differentiable course of the edge curve resulting from the cut with a curvature that is variable in the z direction is preferred.

The first section 42 produces the desired deflection effect. Section 46 only serves to implement a continuously differentiable and thus edgeless transition between the first section 42 of the individual overhead element 34 and the remaining interface 32 of the lens 26.

Individual overhead elements 34 are grouped into sub-areas 54, 56, 58 of the interface by side-by-side arrangement and / or by stacking one above the other. Because of their spatial limitations, each such grouping can itself be regarded as an overhead element. The desired deflecting effect is obtained by comparing the light bundle 48 which passes through the interface of the lens 26 in the region of the overhead element 34 with the light bundles 50, 52 pass through areas of the interface 32 adjacent to the overhead element 34, clearly. In comparison to the light beams 50 and 52, a part 48 ′ of the light beam 48 experiences a deflection in the z direction when it passes through the interface 32. This deflection deflects the light bundle 48 'beyond the light-dark boundary, while the part 48 "of the light bundle 48 is deflected into the low-beam light distribution. The light bundles 50, 52 illuminate the area below the light-dark boundary.

According to the division of the areas of the overhead elements 34 and the remaining light exit interface of the lens 26, preferably less than one percent to less than five percent of the light passing through the lens 26 is scattered into the overhead region, while the remaining ones are scattered more than ninety-five to more than ninety-nine percent are used to illuminate the area below the cut-off line.

In a preferred embodiment, a maximum deflection of a light beam 48 'deflected by an overhead element 34 is at least five degrees with respect to an adjacent light beam 50, 52 which is not deflected by the overhead element 34.

So far, the invention has been explained using the example of a light exit interface of a projection lens 26. As an alternative or in addition, the locally selectively deflecting effect can also be generated by an appropriate configuration of the light entry interface 30 of the lens 26. In the case of vehicle headlights, the light module 16 of which cannot be swiveled, the distracting effect may also be achieved by distributing overhead elements on the light entry interface the cover plate can be realized.

The following describes how successive individual steps, and thus, so to speak, according to a modular principle, are used to position and design adaptable geometric overhead elements 34 on the surface, for example on the light exit interface 32 of a projection lens 26, in order to provide precisely defined light in the overhead area produce. In principle, this method can be applied to any projection system.

In a first step, a new analysis method is used to define subareas on the interface of the projection lens 26 which are suitable for the positioning of overhead elements. These subareas should have dimensions that are as small as possible and thus attract little attention aesthetically. They should preferably be arranged below in the z direction and / or outside in the y direction.

To define the subareas, an interface of the projection lens 26, for example the light exit interface 32, is mathematically broken down into small segments. These segments are specifically examined for their suitability for the positioning of overhead elements 34. In this sense, suitability arises in particular from the fact that such segments illuminate the surroundings of the light-dark boundary. At the end of the analysis, exact statements are made for the ideal positioning of the geometric elements. This procedure prevents undesirable side effects on the homogeneity of the light distribution or the performance of the projection system.

Fig. 3 shows a top view of a light exit interface 32 of a projection lens 26 with a preferred arrangement of partial areas 54, 56 and 58. Two symmetrically arranged partial areas 54 and 56 and a central area 58 arranged below are preferably defined. This arrangement results in an inconspicuous, wanted and aesthetically appealing appearance of the entire lens 26, so that here there is a further degree of design freedom, or so that the lens 26 can be regarded as a design element. The deliberately chosen appearance of the symmetrical arrangement of the partial areas 54 and 56 also avoids, in particular, an impression of a defective lens, as can be awakened, for example, in the case of an overhead element running across the lens in the form of a cylinder part volume.

The subareas are in particular arranged in such a way that effects on the low beam distribution below the light / dark boundary, from which the overhead light is ultimately extracted, are minimal. The homogeneity of the light distribution remains largely unaffected.

In the first step, partial areas 54, 56, 58 are thus defined on the interface of the projection lens, but these do not necessarily have to be arranged as it is in FIG Fig. 3 is shown. It is essential that the partial areas 54, 56, 58 are suitable for an arrangement of overhead elements 34, the suitability resulting from the fact that the partial areas 54, 56, 58 have dimensions that are as small as possible and that a luminous flux that passes through these partial areas 54, 56, 58 passes through, can be deflected without disturbing effects on the rest of the light distribution in the overhead area of the light distribution above the light-dark boundary.

According to the invention, the subregions, for example the subregions 54, 56, 58 shown, are those regions on the projection lens 26 which are traversed by light which would be used to generate the light-dark boundary if there are no overhead elements 34, that is to say that Illumination of the bright area at or just below the cut-off would contribute.
For the definition of the areas, the interface, for example the light exit interface 32 of the projection lens 26, is broken down mathematically into small segments. These segments are then specifically examined for their suitability for the positioning of overhead elements.

According to the invention, three sub-areas 54, 56, 58 are defined, two sub-areas 54, 56 of the three sub-areas being arranged symmetrically to an imaginary plane containing the optical axis 24 of the headlight 10 and perpendicular to the horizon and thus oriented vertically when the headlight is oriented in this way that it generates a light distribution with a rule-compliant, at least partially parallel light-dark boundary. In the Fig. 3 this is the xz level. With such an alignment, the third region 58 is arranged in a lower half of the interface 32 such that it is divided into two equal halves by the vertically oriented imaginary plane 39, so that there is also a symmetry of the arrangement with respect to the plane 39 mentioned . With regard to the lower partial area 58, the individual overhead elements 34, which are grouped together in such a partial area, can also be arranged rotated relative to one another.

In the case of deflecting surfaces based on cylindrical surfaces, this means that the axes of the cylinders belonging to various individual grouped overheasd elements are not aligned parallel to one another, as is shown in FIG Fig. 3 to the right of the projection lens 26 is shown enlarged for a partial area 58. The distraction is done by such a grouping with both lateral and vertical directional components.

The two partial regions 54, 56 arranged symmetrically to one another with respect to a symmetry plane lying centrally between them and parallel to the xz plane preferably have a width of 4 to 5 mm with a length of approximately 10 mm. The lower middle region is preferably approximately 6 mm long and approximately 2.5 mm high. This applies to a lens 26 with a diameter of approximately 60 to 75 mm. With these values, the area occupied by overhead elements 34 is only about 3% of the light exit area 32 of the projection lens 26 projected into the plane. This is significantly less than with the uniform distribution according to FIG DE 10 2009 020 593 A1 . It is therefore preferred and at the same time an advantage of the invention that overhead lighting which meets the legal requirements can be achieved with such a small proportion of the overhead element areas on the surface of the lens. In preferred configurations, this area share is less than 5%. It generally applies to the partial areas that their width is preferably between two mm and ten mm, and their length is preferably between one and twenty mm.

It is also preferred that the two partial regions 54, 56 arranged laterally symmetrically to one another are rotated about an axis of rotation that is parallel to the optical axis and runs through the respective partial region 54 or 56 in such a way that they illuminate light in the Claim 5 described alignment of the headlamp not only deflect upwards, but also to the side. The optical axis runs in the Fig. 3 parallel to the x direction. The subregions 54 and 56 are thus preferably with overhead elements, for example with overhead elements 34 which are shown in FIG Fig. 2 illustrated type proves that these overhead elements deflect light passing through them so that this light has propagation direction components 60, 62, respectively. These propagation direction components are distinguished by the fact that they not only have an upward component (in the z direction), but also that they have directional components that point laterally, ie in the positive and / or negative y direction. The width of the overhead lighting in the y direction required for conformity with the rules is thereby achieved, so that all prescribed measuring points are illuminated.

In these partial areas 54, 56, 58 defined in the first step, individual overhead elements 34 and / or groups of individual overhead elements are arranged in the second step. Each group preferably contains a number of individual overhead elements, which is between 1 and 20. The overhead elements 34 preferably have a geometry which, due to their far-reaching adaptability, enables a defined generation of overhead light. At the same time, the maximum values (glare values) to be observed are taken into account through targeted light control, so that the legal requirements can be safely met.

A targeted adaptation of the geometry of the overhead elements is possible better than before due to the large number of degrees of freedom in the geometric design. The overhead elements are at least C1 continuous, i.e. at least once continuously differentiable and therefore without Step or kink in the interface, so integrated into the surface of the projection lens 26. In series production, this leads to an improved tool life.

The dimensioning of the geometric elements to be used in the partial areas defined in the first step, be it the partial areas 54, 56, 58 or other partial areas defined in the first step, takes place by means of simulation and subsequent analysis. Due to the precisely defined geometry of the overhead elements 34, their effect can be predicted with good accuracy. This makes it easy to adapt the elements 34 to precise targets. This saves a considerable amount of time when determining the size, number and alignment of the overhead elements.

Smaller surface sections 42 of the front surface of the projection lens 26 are specifically tilted in the vertical direction relative to their previous orientation. In other words, a z component of a surface normal of the surface section or surface area is enlarged. The light that passes through these surface sections or surface areas experiences a significant increase compared to its previous direction, i.e. an increase in the z component of its direction of propagation, and then illuminates the overhead area of the light distribution as a desired consequence. This light is taken from the low beam distribution that occurs without such a tilt.

The vertical deflection angle is varied within the tilted surface sections to cover the entire overhead measurement range. This creates a flat and homogeneous, albeit comparatively weak Illuminated area in which all overhead measurement points are located. The maximum light deflection achieved by the overhead elements is at least 4 °, but can also be up to 10 °.

The surface sections 42 tilted against the surface 32 of the projection lens 26 are generally realized by cylinder sections. However, they can also be limited by comparable or different mathematical functions or, for example, spline surfaces or a combination of them. The tilted individual surfaces are integrated into the surface of the projection lens by clever rounding, which lies between points 40 and 44. Various rounding surfaces or free-form surfaces defined by mathematical functions can be used. Areas defined by spline functions can also be used; other defined areas are also possible.

The rounding is realized in particular in that an at least once continuously differentiable transition is generated between the base surface 32 of the projection lens 26 and the light-deflecting surface sections or the overhead elements. This soft integration into the projection lens 26 improves the service life of the lens tool, since there are no sharp edges that could be worn out. The basic appearance and the functional principle of the overhead elements is described in the Figure 2 shown.

The arrangement and grouping of the overhead elements is not limited to an arrangement in a pattern of three sub-areas. Depending on the lighting design of the projection system, different positioning, number and size of the above described overhead elements 34 suitable to generate a sufficient amount of overhead light, without having to put up with a disturbing influence on the rest of the light distribution.

For design reasons, the in the Fig. 3 Arrangement of three sub-areas with the described symmetry, represented qualitatively, represents the configuration according to the invention.

In each of these areas Fig. 3 at least one single overhead element 34 is placed. Instead of occupying only one single overhead element 34, occupying each sub-area with only up to ten individual overhead elements 34 is preferred, the number of individual overhead elements in the sub-areas arranged symmetrically to one another preferably being the same. As already explained, it is preferred that two groups are placed in the two lateral areas of the projection lens (based on the vertical axis) and the third group in the central area, preferably further below.

An improved functionality of the overhead elements is achieved by the following measures: The two lateral areas with overhead elements can additionally be rotated about their center, the axis of rotation running parallel to the optical axis of the projection system. The angle of rotation can be optimally adjusted. The light passing through is not only deflected upwards, but also deliberately deflected to the side. By this measure, the lighting of With regard to the permissible illuminance, measurement points limited to a higher limit (glare values) are significantly reduced. At the same time, the overhead measuring points on the side are illuminated more intensely, so that the efficiency of the overhead elements increases.

Due to the compactness of the overhead elements within their subareas, they can be arranged on the surface of the projection lens in such a way that the required light can be removed without disruptive effects on the rest of the light distribution. Areas that only have a slight mixing of the light or are relevant for the performance of the projection system can be left out: In this way, for example, inhomogeneities or darkening in the area directly in front of the vehicle and in the side areas of the light distribution are prevented.

The group of overhead elements 34, which is integrated centrally and preferably below in the partial area 58 of the front surface of the lens, is of particular importance Fig. 3 this is the group of individual overhead elements 34 arranged in the partial area 58. These support the elements 34 arranged laterally in the partial areas 54 and 56 by making an additional contribution to the required overhead light.

At the same time, their preferred lateral scattering enables the light to be homogenized in the overhead region; the averaging effect which arises along the y direction is used. This generates a very even overhead light.

They also reduce the occurrence of inhomogeneities in the light distribution because this occurs in the overhead area required light is taken from another, uncritical point on the lens surface.

The aesthetically improved appearance of the overhead elements due to the less conspicuousness is achieved by using very compact structures with spatially small dimensions instead of an overhead element which extends far beyond the projection lens or numerous discrete individual elements.

By dividing the deflecting surfaces into individual elements 34, which are arranged one above the other or next to one another, a very small height of the individual elements is achieved in the direction of their surface normals. This height is preferably in the range from 0.02 to 0.2 mm. In individual cases, the use of only one element per group may be sufficient; the division is not necessary here. This configuration is preferred if only a correspondingly small area is required for the overhead elements.

The grouping of several, similar overhead elements 34 in a delimited partial area, for example an overhead area 54, 56 or 58, and the symmetrical arrangement of the partial areas lead to a desired appearance, so that the elements are not to be confused with surface defects on the lens are. The desired appearance is enhanced by the arrangement of the two lateral overhead areas 54, 56, which runs symmetrically to the vertical axis, and the central additional area 58, which also contains a grouping of individual overhead elements 34.

An overall resulting light distribution with an overhead component generated according to the invention is shown in FIG Fig. 4 shown. H denotes a horizontal and V a vertical. The crossing point H = V = 0 represents the center of the light distribution. The H direction thus corresponds to the y direction also used here and the V direction corresponds to the z direction. The numbers are given in degrees. The closed curves are lines of the same illuminance, the illuminance decreasing from the inside to the outside.

The overhead measurement points M1-M6 to be illuminated with a minimum amount of light are safely in the sufficiently illuminated overhead area. At the same time, the light level below the measuring points M4, M5, M6 does not rise any further, so that the maximum values (glare values) permitted there are reliably maintained.

The essence of the invention presented here relates to the described method for arranging and designing lens structures for generating overhead values. The invention is not limited to the generation of a special overhead light distribution.

The method is intended to determine the position, the dimensions and the number of overhead elements. The light source 18 itself and the reflector 20 and the diaphragm 22 of the low-beam light distribution must be taken into account. Halogen and gas discharge lamps and semiconductor light sources come into question as light sources. Preferred positions of the overhead structures are areas on the lens which are traversed by light which serves to generate the light-dark boundary.

The surface structures according to the invention can be made using the known lens structures (wave structures, grain patterns, rhombuses) DE102008023551 ), especially those combined to influence the light-dark boundary. When using different structures on a lens surface, the structures for generating the overhead values are not superimposed on the other structures. Instead, the overhead structures described here are retained and the other structures are trimmed accordingly.

In the method described here for arranging and designing lens structures for generating overhead values, the lens front surface is computationally divided into small, individual segments of a suitable size in a first step. In one embodiment, these segments are each 5 x 5 mm in size.

Then, in a second step, a separate simulation is carried out for each segment of the surface of the projection lens. Only the light that passes through the currently examined segment of the projection lens is considered. The result is the associated light distribution for each segment. It is thus known in each case at which location of the light distribution how much light arrives from the relevant segment.

On this basis, it is determined in a third step for each segment whether this segment is suitable for integrating overhead elements. In this way, in this third step, all lens areas are divided into areas that can be used for overhead lighting and areas that cannot be used. Usable areas are areas that bring light to or near the cut-off line. Areas that cannot be used illuminate this In front of the vehicle or illuminate the side area of the light distribution or are essential for the performance of the projection system. In this sense, if you arranged non-usable areas of overhead elements, the homogeneity of the light distribution and the performance of the projection system would be impaired.

With the result of this analysis, the optimal positioning of the overhead elements on the projection lens is known. The fourth step now follows, in which the geometry and the properties of the overhead elements are defined. The definition of the geometry of the overhead individual elements and the grouping of such overhead elements is preferably carried out according to the following aspects:
The height of the area to be illuminated, ie the distance from the lower edge to the upper edge of the overhead light strip, is set via the radius of the cylinder on which it is based. The smaller the radius is chosen, the more the resulting overhead light is expanded vertically. The optimal vertical positioning of the overhead area is achieved by vertical displacement of the cylinder axis of the overhead individual elements. The entire light band can be precisely adjusted in its vertical position. Overall, it can be moved up or down to optimally illuminate the specified measuring points. A vertical shift is understood to mean a shift parallel to the vertical axis of the vehicle. In the figures, this is the z direction. The amount of light required for the overhead light can easily be precisely targeted by varying the number of individual overheand elements and by extending the individual elements laterally dimension. The larger the area of the overhead elements, the more overhead light is generated. The additional relief of the glare values is achieved by suitable positioning of the overhead individual elements and additionally by rotating the overhead elements. The individual overhead elements are positioned such that they are only arranged in non-critical areas of the projection lens. These are the appropriate areas mentioned above. A lateral deflection is additionally generated by the rotation on the surface of the projection lens 32, whereas when several individual overhead elements 34 are aligned one above the other in a vertical row, so to speak, the light is deflected only in the vertical direction. To increase the distracting area in the Figure 2 is shown, several such individual overhead elements 34 are preferably arranged in a row next to one another or one above the other. These individual overhead elements are preferably combined in groups, as is the case, for. B. from the top view of a projection lens 26 according to Figure 3 can be seen. The grouping in the partial area 58 shows a side-by-side arrangement in which several individual overhead elements 34 are arranged side by side in the y-direction. The two other groups, which lie in the partial areas 54 and 56, each show groups of overhead elements 34, which have been rotated somewhat out of the z direction.

Claims (13)

1. Method for arranging and dimensioning geometric overhead elements (34), which are implemented as local deformations of an interface (32) of a projection lens (26) of a motor vehicle projection headlamp (10), which is designed to project an edge, which delimits a luminous output from a light source of the headlamp, as the light-dark cut-off of a light distribution produced by the headlamp in front thereof, the overhead elements (34) being designed so as to direct light into an overhead region of the light distribution, which region is above the light-dark cut-off, characterized in that, in a first step, three subregions (54, 56, 58) of the interface (32) are defined which are those regions on the projection lens (26) through which light passes, which light would serve to produce the light-dark cut-off, in the event of there being no overhead elements (34), such that said light would contribute to the illumination of the light region on the light-dark cut-off, two of the three subregions being arranged so as to be symmetrical with respect to a plane, which contains the optical axis of the headlamp and is perpendicular with respect to the horizon and is thus a vertically oriented imaginary plane, if the headlamp is oriented in such a way that it produces a light distribution having a light-dark cut-off that conforms to the rules and is at least partially parallel to the horizon, and such that, in such an orientation, the third region is arranged in a lower half of the interface such that it is divided into two equal halves by the vertically oriented imaginary plane, in that, in a second step, overhead elements (34) are defined which are arranged in the subregions defined in the first step, in that an overhead illumination resulting from the simulated overhead elements is simulated, the simulation of the defined overhead elements being used in order to iteratively modify a number and/or shape of the defined overhead elements such that the simulated overhead illumination satisfies predefined conditions.
2. Method according to claim 1, characterized in that, in the first step, subregions are defined on the interface of the projection lens which are suitable for positioning overhead elements, the suitability resulting from the fact that the subregions have the smallest possible dimensions and that a luminous output, which passes through these subregions, can be deflected without disturbing effects on the rest of the light distribution into the overhead region of the light distribution, which region is above the light-dark cut-off.
3. Method according to either of the preceding claims, characterized in that, in the first step, the interface of the projection lens is split into small segments, and in that these segments are specifically examined for their suitability for the positioning of overhead elements.
4. Method according to claim 1, characterized in that the two laterally symmetrically arranged subregions are rotated about a rotational axis, which is parallel to the optical axis and passes through the relevant subregion, such that, in the described orientation of the headlamp, said subregions deflect light not only upward, but also to the side.
5. Method according to any of the preceding claims, characterized in that, for the defined overhead elements, those geometries are used which are distinguished by extensive adaptability and of which the effect on the light distribution can be simulated with a high level of accuracy.
6. Method according to claim 5, characterized in that the overhead elements are defined such that the interface between the overhead elements and the air continuously differentiably transitions into the adjacent interface of the projection lens which does not belong to the overhead element.
7. Method according to claim 4, characterized in that the overhead elements to be arranged in the subregions are defined with respect to their size, number, geometric design and orientation within the subregions.
8. Motor vehicle projection headlamp, which is designed to project an edge, which delimits a luminous output from a light source of the headlamp, as the light-dark cut-off of a light distribution produced by the headlamp in front thereof, and which headlamp comprises a projection lens having geometric overhead elements which are implemented as local deformations of an interface of the projection lens and are designed so as to direct light into an overhead region of the light distribution, which region is above the light-dark cut-off, characterized in that the overhead elements are arranged on three subregions of the interface so as to be restricted, which subregions are those regions on the projection lens (26) through which light passes, which light would serve to produce the light-dark cut-off, in the event of there being no overhead elements (34), such that said light would contribute to the illumination of the light region on the light-dark cut-off, two of the three subregions being arranged so as to be symmetrical with respect to a plane, which contains the optical axis of the headlamp and is perpendicular with respect to the horizon and is thus a vertically oriented imaginary plane, if the headlamp is oriented in such a way that it produces a light distribution having a light-dark cut-off that conforms to the rules and is at least partially parallel to the horizon, and such that, in such an orientation, the third region is arranged in a lower half of the interface such that it is divided into two equal halves by the vertically oriented imaginary plane.
9. Headlamp according to claim 8, characterized in that the two laterally symmetrically arranged subregions are arranged so as to be rotated about a rotational axis, which is parallel to the optical axis and passes through the relevant subregion, such that, in the described orientation of the headlamp, said subregions deflect light not only upward, but also to the side.
10. Headlamp according to claim 9, characterized in that the interface between the overhead elements and the air continuously differentiably transitions into the adjacent surface of the interface of the projection lens which does not belong to the overhead element.
11. Headlamp according to any of claims 8 to 10, characterized in that each subregion comprises one to ten overhead elements.
12. Headlamp according to claim 11, characterized in that the overhead elements protrude out or protrude in by 0.02 to 0.2 mm from the interface of the projection lens surrounding said elements.
13. Headlamp according to any of claims 8 to 12, characterized in that, in addition to the overhead elements, the interface comprises surface structures which are not used for producing an overhead illumination and are arranged outside of the subregions of the interface which have the overhead elements.

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