EP3329179B1 - Light device for a vehicle headlamp - Google Patents

Description

The invention relates to a lighting device for a headlight, in particular a motor vehicle headlight, comprising a plurality of light sources, a light guide with a plurality of light guide elements and a downstream imaging optical element, each light guide each having a light input surface and a respective light exit surface, wherein the light guide in at least one row are arranged, wherein the light-guiding elements are arranged in at least one row, and the light-guiding elements of at least one row are formed as high-beam light-guiding elements and form a high beam row, each high-beam Lichtleitelement each comprises a lower Lichtleitfläche.

Such lighting units, which are also referred to as pixel light modules, are common in the automotive industry and serve, for example, the imaging of glare-free high beam by the light is usually emitted by a plurality of artificial light sources and by a corresponding plurality of juxtaposed light guides (attachment optics / Primary optics) is focused in the emission direction. The light guides have a relatively small cross-section and therefore emit the light of the individual light sources each associated with very concentrated in the emission direction. Pixel light emitters are very flexible in terms of light distribution because for each pixel, i. For every light guide, the illuminance can be controlled individually and any light distribution can be realized.

On the one hand, the concentrated radiation of the light guides is desired, for example, to comply with legal requirements regarding the light-dark line of a motor vehicle headlight or implement adaptive flexible Ausblendszenarien, on the other hand, this creates disturbing inhomogeneities in areas of the light image in which a uniform, concentrated and directed illumination desired is, as for example in the high beam distribution.

This problem could be improved by reducing the height of the high beam distribution, which is in contradiction to customer requirements. There is therefore a need for improved measures for homogenizing the high beam distribution.

Various measures or methods are known from the prior art, which are based on the one hand on the defocusing and on the other hand on the light scattering, for example by means of light-scattering structures.

The US 8,011,803 B2 relates to a fog lamp, the collimating attachment optics with attached wavy deflection, which is inclined to the main emission of the LED includes. As a result, on the one hand, the light is deflected but also scattered, so that the homogeneity is improved.

The DE 2009 053 581 B3 refers to the primary optics of a matrix / pixel module. The frontal exit surface of the optic is provided with a wavy padding structure.

The DE 10 2008 005 488 A1 discloses a fine structure surface for the optical unit having a plurality of structural elements with which the light spots are widened in the horizontal direction. If the light spots overlap, the edges blur, resulting in a more homogeneous overall light distribution.

The DE 10 2010 027 322 A1 describes refractive micro-optic components at the light exit surface of a primary optic.

The EP 2 587 125 A2 discloses microstructures on the light exit surface of the primary optics of a pixel headlamp.

The US 5,727,108 discloses prismatic boundary surfaces for compound parabolic concentrator (CPC) alignment optics.

The US 2015/0131324 A1 discloses a lighting device for a headlamp, with light-guiding elements, which are arranged in a row and form a high beam row.

It is an object of the invention to provide a lighting device for headlights, on the one hand allows a more homogeneous high beam distribution and on the other hand, a concentrated and directed illumination of a high beam area.

This object is achieved with a lighting device for headlamps of the type mentioned, which is inventively characterized in that the lower Lichtleitfläche at least in the region in which the light beams are reflected, at least partially structures, wherein the structures in that region of the lower light guide surface, which is adjacent to the light exit surface and in which the light is reflected, are formed, and that the structures are groove-shaped , wherein the grooves are oriented transversely to an optical axis of the lighting device and have a width of 0.2-0.4 mm and a height of 0.015-0.03 mm.

The invention is a technically simple and cost-effective measure to locally influence the light distribution in the respective high-beam light guide elements and thus to realize a more homogeneous high beam distribution. By arranging the groove-shaped structures only in the vicinity of the light exit surface of the respective high-beam light guide elements of the high beam row, specifically, the superposition of the once-reflected light beams to the directly emitted light can be improved.

The basic structure of light-guiding elements and attachment optics for pixel light lighting devices for headlights is known per se. The light-guiding elements are made, for example, of plastic, glass or any other suitable materials for light transmission. Preferably, the light guide elements are made of a silicone material. The light-guiding elements are typically embodied as solid bodies and preferably consist of a single continuous optical medium, wherein the light conduction takes place within this medium. The light-guiding elements typically have a substantially square or rectangular cross section and usually expand in the light emission direction in a manner known per se. In an alternative embodiment, the light-guiding elements can be realized as open collimators.

The light emitted by the light source and light coupled into the light guide is expediently totally reflected by the lower light guide surface.

Advantageously, the grooves formed on the lower light guiding surface have a periodic geometry.

In a variant, it is provided that, starting from the light exit surface, 6-15 grooves are formed on the lower light guide surface.

Experience has shown that the structure of a lighting device for pixel light is particularly efficient when the light-guiding elements are arranged in exactly three rows arranged one above the other, which together form a high beam distribution. In such an arrangement, the upper row may be formed as a leading row, the middle row as an asymmetrical row and the lower row as a high beam row, the high beam row being provided by high beam light guiding elements having structures as described herein. Conveniently, the bottom row is the high beam row.

In another embodiment, all the light-guiding elements can be designed as high-beam light-guiding elements which are arranged in exactly one row. Such lighting devices are also referred to as pixel high beam modules.

The light-conducting elements of the rows are preferably arranged as close as possible to each other, whereby inhomogeneities in the photograph can be further reduced. In one development of the invention, the light exit surfaces of the individual light guide elements can therefore be part of a common light exit surface, with the individual light exit surfaces adjoining one another. The common light exit surface is typically a curved surface, usually following the Petzval surface of the imaging optics (e.g., an imaging lens). For certain applications, however, deliberate deviations in the curvature can also be used in order to use aberrations for light homogenization in the edge region.

Another object of the invention relates to a headlamp, in particular a motor vehicle headlamp, which comprises a lighting device according to the invention as disclosed herein. Headlights of this type are also referred to as pixel light.

• Fig. 1 eine perspektivische Darstellung des Grundaufbaus einer Leuchteinrichtung gemäß der Erfindung,
• Fig. 2 eine Darstellung der Gesamtlichtverteilung, die mit der Leuchteinrichtung aus Fig. 1 erhalten wird,
• Fig. 3 eine Detailansicht auf die Vorsatzoptik aus Fig. 1 in Lichtausbreitungsrichtung,
• Fig. 4 eine Seitenansicht eines Fernlicht-Lichtleitelements gemäß dem Stand der Technik,
• Fig. 5 eine Lichtstärkenverteilung (Lichtstärke-Simulation) eines Fernlicht-Lichtleitelements aus Fig. 4.
• Fig. 6 eine Intensitätsverlaufskurve der Lichtstärkenverteilung aus Fig. 5,
• Fig. 7 eine Seitenansicht eines Fernlicht-Lichtleitelements gemäß der Erfindung,
• Fig. 8 eine Darstellung der Lichtstärkenverteilung des Fernlicht-Lichtleitelements aus Fig. 7,
• Fig. 9 eine Intensitätsverlaufskurve der Lichtstärkenverteilung aus Fig. 8,
• Fig. 10 einen Vertikalschnitt durch ein Fernlicht-Lichtleitelement gemäß der Erfindung, und
• Fig. 11 ein Detail aus Fig. 10.

The invention and its advantages are described in more detail below by way of non-limiting examples, which are illustrated in the accompanying drawings. The drawings show in:

• Fig. 1 a perspective view of the basic structure of a lighting device according to the invention,
• Fig. 2 a representation of the total light distribution, with the lighting device off Fig. 1 is obtained
• Fig. 3 a detailed view of the attachment optics Fig. 1 in the direction of light propagation,
• Fig. 4 a side view of a high-beam light guide according to the prior art,
• Fig. 5 a light intensity distribution (light intensity simulation) of a high-beam light-guiding element Fig. 4 ,
• Fig. 6 an intensity curve of the luminous intensity distribution Fig. 5 .
• Fig. 7 a side view of a high-beam light-conducting element according to the invention,
• Fig. 8 a representation of the light intensity distribution of the high-beam light-guiding element Fig. 7 .
• Fig. 9 an intensity curve of the luminous intensity distribution Fig. 8 .
• Fig. 10 a vertical section through a high-beam light-conducting element according to the invention, and
• Fig. 11 a detail from Fig. 10 ,

Fig. 1 shows a perspective view of the basic structure of a lighting device 1 according to the invention. The lighting device 1 comprises a plurality of in Fig. 1 not shown LED light sources 100 (see, however Fig. 7 ) and a mounted in Lichtabstrahlrichtung attachment optics 10 (= primary optics) and a downstream imaging optics 200 (shown as a single lens 200). The attachment optics 10 comprises light guide elements 11, 12, 13, which are arranged in three rows and the radiating side to a common end plate 26 extend. The end plate 26 is the emission side limited by a light exit surface 23 ', wherein the light exit surfaces 23 of the individual light guide elements (see Fig. 7 ) are each part of the common light exit surface 23 ', wherein individual light exit surfaces 23 adjoin one another. The common light exit surface 23 'is typically a curved surface, usually following the Petzval surface of the imaging lens 200. For certain applications, deliberate deviations in the curvature of the common light exit surface 23 'can also be used in order to use aberrations for light homogenization in the edge region. Each light-guiding element 11, 12, 13 is a per se known per se LED light source 100 (see FIG. Fig. 7 ). For each light guide element 11, 12, 13, the illuminance can be controlled individually, which is why arbitrary light distributions can be realized. At the in Fig. 1 shown attachment optics 10, the upper row is formed as a front row row consisting of a plurality of apron light-guiding elements 13. The middle row is formed as asymmetry series consisting of a plurality of asymmetry light guide elements 12 and the lower row is formed as a high beam row consisting of a plurality of high beam light-guiding elements 11. The three rows together form a high beam distribution in the activated state. The high-beam light guide elements 11 are on their lower light guide surface 24 (see Fig. 7 ) are provided with a groove structure 25, wherein the grooves 25 are oriented transversely to an optical axis 16 of the lighting device 1. Fig. 3 shows a detailed view of the attachment optics 10 Fig. 1 in the light propagation direction.

The light-guiding elements 11, 12, 13 can be made, for example, of silicone, plastic, glass or any other suitable materials for light conduction. The light-guiding elements 11, 12, 13 are designed as solid bodies and consist of a single continuous optical medium, wherein the light conduit takes place within this medium. The light-guiding elements 11, 12, 13 have a substantially square or rectangular cross-section and expand in the light emission direction, where they finally as described above radiation side to the common end plate 26, the emission side by a light exit plane 23 '(see. Fig. 3 ) is limited.

Fig. 2 shows a representation of the total light distribution (= pixel light distribution) with a view through the imaging lens on a measuring screen, with the lighting device 1 off Fig. 1 can be won. It is about a horizontal axis U and a vertical Axis V matrix-shaped and arranged in three rows fields recognizable, the upper row, which includes a plurality of high beam strips, for illumination of the high beam area, the middle row for illumination in the asymmetry area (forming a cut-off) and the lower row for illumination the apron of a pixel light spotlight is used. Overall, the light distribution forms a high beam distribution. Adjacent fields touch or overlap each other, making the light image appear substantially homogeneous to a viewer.

Fig. 4 shows a side view of a high-beam light guide element 11 'according to the prior art. The high-beam light-conducting element 11 'is a solid body having a light coupling surface 21, via which the light emitted by the LED light source is coupled into the light-conducting element 11'. The light is conducted forward along the high-beam light-conducting element 11 'to a light exit surface 23. Fig. 4 also shows exemplary beam paths emanating from the light incoupling surface 21, wherein the beams 50 represent the direct light exit and the beams 51, which are reflected at a lower light guide surface 24, represent the indirect light exit. Also visible is the upper light guide surface 22, whereas the side of the solid body limiting light guide surfaces are not provided with reference numerals for reasons of representability. The light rays are totally reflected at the light guide surfaces. Like from the Fig. 4 As can be seen, the lower light guide surface 24 of a prior art high-beam light guide element 11 'is formed along its entire length as a smooth reflection surface (optimized for the use of total reflection).

Fig. 5 shows by way of example a luminous intensity distribution 30 (photometric ray tracing simulation with a luminous intensity sensor, wherein a grayscale image is obtained in accordance with the luminous intensity) of a high-beam light-conducting element 11 ' Fig. 4 , In the lower part of the high beam segment, an intensity maximum 31 can be detected; In the upper area of the high beam segment, on the other hand, there is first an intensity drop 32, which leads to a clearly visible inhomogeneity due to a rise 33 of the intensity. Fig. 6 shows an intensity curve of the luminous intensity distribution Fig. 5 in which the counter-rise 33 is clearly visible. The cause of the inhomogeneity lies in particular in the transition and the insufficient overlap between the directly emitted light 50 and the light 51 reflected at the lower light guide surface 24.

Fig. 7 shows a side view of a high beam light guide element 11 according to the invention. The high-beam light guide 11 according to the invention differs from that of the prior art (high-beam light guide 11 ', see Fig. 4 ) in that groove-shaped structures 25 are formed on the lower light guide surface 24 in the region in which the beams 52 are reflected. The remaining structure of the high-beam light-guiding element 11 corresponds to that of the Fig. 4 and reference is made to the description above. Fig. 7 also shows exemplary beam paths emanating from the light incoupling surface 21, wherein the beams 50 represent the direct light exit and the beams 52, which are reflected at the groove structure 25 of the light guide surface 24, represent the indirect light exit. The groove structure 25 scatters and shapes the light 52 precisely in that region which lies in the transition between the directly emitted light 50 and the light 52 reflected at the groove structure 25 of the lower light guide surface 24. By the groove structure 25, the light distribution can be influenced and as a result there is an improvement in the light homogeneity.

Fig. 8 shows by way of example a luminous intensity distribution 30 '(photometric ray tracing simulation with a luminous intensity sensor, a grayscale image being obtained in accordance with the luminous intensity) of a high-beam light-conducting element 11 according to the invention Fig. 7 , In the lower part of the high beam segment, the intensity maximum 31 can be detected; In the upper part of the high beam segment, a continuous drop in intensity is generally recognizable and the light image is much more homogeneous compared to the prior art. Fig. 9 shows an intensity curve of the luminous intensity distribution Fig. 8 from which the continuous intensity drop and the improved homogeneity (in Fig. 7 marked with the reference numeral 34) is clearly visible in the transition between the directly emitted light 50 and the light reflected at the groove structure 25 light 52. With the help of the groove structure, the outlet can be upwards (see. Fig. 2 ) be better designed and optimized.

Fig. 10 shows a vertical section through a high-beam light-conducting element 11 according to the invention. As can be seen therein, the grooves 25 extend transversely to the optical axis (or light propagation direction) and are formed along a (imaginary) carrier curve TK on the lower light guide surface 24. In the example shown, a total of 9 grooves are formed starting from the light exit surface 23. For example, the grooves 25 have a width of 0.3 mm and a height of 0.015-0.03 mm.

Fig. 11 shows a detail Fig. 10 (in Fig. 10 indicated by a dashed circle). An optimized embodiment can be obtained as follows: The carrier curve TK is the boundary of a light-guiding element. On this curved (imaginary) curve TK points P (Pi, Pi + 1, Pi + 2) are plotted, which have a constant distance S from each other. This distance (or wavelength) is for a special high-beam light guide, for example, S = 0.30 mm. Neighboring Points Pi and Pi + 1 determine a path into whose halving point Hi a normal is established. Above the point, a vertex Si is established at a distance = amplitude of hi. The three points Pi, Si, Pi + 1 are the nodes of a spline curve. The magnitude of the amplitude is iteratively varied, with the respective geometry a photometric simulation is carried out according to a conventional manner. By comparing the obtained light images (or the gradient curve), the best amplitude is determined. This process must be repeated for each groove, since the distance from the light source (LED light source 100) determines the angle of incidence on the support curve and thus the location of the inhomogeneity. The boundary surface of the groove itself is an extension surface of the determined spline curve, wherein the extension direction is normal to the vertical center plane of the light guide, and wherein each groove has its own amplitude.

The examples shown are only a few among many and not to be construed as limiting.

Claims (9)

1. A lighting device (1) for a headlamp, in particular a motor-vehicle headlamp, comprising a plurality of light sources (100), a light-guiding device (10) with a plurality of light-guiding elements (11, 12, 13), and a downstream imaging optical element (200), wherein each light-guiding element (11, 12, 13) has a light infeed face and a light exit face, wherein the light-guiding elements (11, 12, 13) are arranged in at least one row and the light-guiding elements of at least one row are configured as main beam light-guiding elements (11) and form a main beam row, wherein each main beam light-guiding element (11) comprises a lower light-guiding face (24),
   characterised in that
   the lower light-guiding face (24) has, at least in the region in which the light beams (52) are reflected, structures (25) at least in regions, wherein the structures (25) are formed in the region of the lower light-guiding face (24) which borders the light exit face (23) and in which the light is reflected, and in that the structures are rib-like, wherein the ribs (25) are oriented transversely to an optical axis (16) of the lighting device and have a width of 0.2 to 0.4 mm and a height of 0.015 to 0.03 mm.
2. The lighting device according to claim 1, characterised in that the lower light-guiding face (24) totally reflects the coupled-in light beams.
3. The lighting device according to claim 1 or 2, characterised in that the ribs have a periodic geometry.
4. The lighting device according to any one of claims 1 to 3, characterised in that, starting from the light exit face, 6 to 15 ribs (25) are formed on the lower light-guiding face (24).
5. The lighting device according to any one of claims 1 to 4, characterised in that the light-guiding elements (11,12,13) are arranged in exactly three rows arranged one above the other, which together form a main beam distribution.
6. The lighting device according to claim 5, characterised in that the lowermost row (11) is the main beam row.
7. The lighting device according to any one of claims 1 to 4, characterised in that all light-guiding elements are formed as main beam light-guiding elements arranged in exactly one row.
8. The lighting device according to any one of claims 1 to 7, characterised in that the light exit faces (23) of the light-guiding elements (11, 12, 13) are part of a joint light exit face (23'), wherein individual light exit faces (23) border one another.
9. A motor-vehicle headlamp comprising a lighting device (1) according to any one of claims 1 to 8.

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