DE102008047728B4 - Headlights for automobiles - Google Patents

Abstract

Headlights for motor vehicles with a plurality of LED lighting elements (5, 5 '), which are arranged in an LED field (11) grouped at a distance from one another, and with one in the light emission direction (2) in front of the LED field (11) arranged optical unit (3) for generating a predetermined light distribution, that the optical unit (3) has a segmented lens (3 ', 3' '), the at least two lens segments (S1, S1'; S2, S2 '; S3, S3') in such a way that the light images (b1, b2, b3,) imaged by the lens segments (S1, S1 '; S2, S2'; S3, S3 ') of the LED lighting elements (5, 5') are superimposed and / or are shifted relative to each other that from the light images (b1, b2, b3) of the lens segments (S1, S1 '; S2, S2'; S3, S3 ') resulting light images (B1, B2, B3, B4, B5, BN) are formed which are arranged directly next to one another or overlapping on a measuring screen (12), characterized in that the lens segments (S1, S1 '; S2, S2'; S3, S3 ') are configured in this way are iert that a predetermined color mixture occurs at an edge (10) of the light band (6).

Description

The invention relates to a headlight according to the preamble of claim 1.

From the DE 101 29 743 C2 a headlight for motor vehicles is known which has an array of LED lighting elements as a light source. An optical unit is arranged in front of the LED field in the direction of light emission and consists of a converging lens and a diffuser arranged in front of the converging lens in the direction of light emission. The converging lens bundles the light emitted by each LED light element. In 1 shows how the light emitted by a number of LED lighting elements is imaged by means of a converging lens. A “string of pearls” of photographs is created on a measuring screen A ₁ , A ₂ , A ₃ ... A _N (Luminous element images), with between adjacent light images of length L ₁ a gap K arises. This leads to inhomogeneities in the light distribution or to a blurred light-dark boundary of a light distribution. After DE 101 29 743 C2 For example, the diffuser is designed as a microlens, by means of which the light coming from the converging lens is scattered in such a way that the light images of the individual LED lighting elements overlap. The disadvantage of the known headlight is that the measures for homogenizing the light distribution are relatively expensive and, in particular, a sharp cut-off line cannot be achieved.

From the DE 10 2007 040 760 A1 a headlight for motor vehicles having a plurality of LED lighting elements and a segmented lens is known, lens segments of the lens being arranged at a distance from one another. A recess is provided between the lens segments in order to reduce the weight.

From the DE 103 15 133 A1 there is known a headlight for motor vehicles having a plurality of LED lighting elements and a lens. The lens serves as the primary optics and has a plurality of lens elements that allow the light to be focused. A secondary lens, which is not segmented, is located in front of the primary optics.

The object of the present invention is therefore to develop a headlight for motor vehicles in such a way that inhomogeneities in a light distribution are reduced with little effort and a relatively high degree of selectivity is ensured when imaging LED lighting elements.

To solve this problem, the invention has the features of claim 1.

The particular advantage of the invention is that a segmented lens avoids undesirable inhomogeneities in a light distribution that arise due to the imaging of LED lighting elements in spaced apart light images, with a relatively high degree of selectivity of the LED lighting element imaging being ensured. In this way, the effectiveness in generating, for example, a dynamic light distribution depending on the traffic situation can be increased. For example, a glare-free high beam function can be generated in this way, with glare being reduced by switching off various LED light elements depending on the current position of another road user in front of the vehicle. The basic concept of the invention is to form a lens by at least two lens segments which each image the LED lighting elements differently in such a way that light images of a predetermined size resulting from the LED lighting elements are generated. If an LED field formed from a row of LED lighting elements is provided, a continuous, homogenized lighting strip is thus obtained. The light images of the individual LED lighting elements lie directly next to one another or can overlap or overlap. According to the invention, the lens segments are configured in such a way that a predetermined color mixture occurs at an edge of the light band. For example, the middle lens segment can have a convex-like contour and the adjacent outer lens segments have a divergent contour on a light coupling-out side. In this way, color effects at the edge of the light band can be reduced or homogenized.

According to a preferred embodiment of the invention, the lens segments are arranged directly next to one another transversely to an optical axis (main axis) of the lens. The lens segments each have different optical axes, the distance between the optical axes of the respective lens segments being provided as a function of a clear distance between adjacent LED lighting elements such that a homogeneous band of light is generated. The light band is composed of the resulting light images, which preferably have a constant length. The resulting photos themselves are composed of the photos of the individual lens segments.

According to a further development of the invention, the segmented lens has three lens segments, so that the resulting light image is composed of three light images each imaged by the three lens segments. The segmented lens is advantageously of compact design and enables a desired homogeneous formation of a light band.

According to a development of the invention, the segmented lens can also consist of three pairs of There are lens segments, wherein the pairs of lens segments can each be designed the same. A relatively wide, homogeneous band of light can advantageously be generated in this way.

Further advantages of the invention emerge from the further subclaims.

Exemplary embodiments of the invention are explained in more detail below with reference to the drawings.

• 1 eine Darstellung eines Lichtbandes auf einem Messschirm, wobei eine Reihe von LED-Leuchtelementen mittels einer Sammellinse nach dem Stand der Technik abgebildet worden ist,
• 2 einen Horizontalschnitt durch einen Scheinwerfer nach einer ersten Ausführungsform, wobei ein Lichtbild eines mittleren LED-Leuchtelementes auf einem Messschirm exemplarisch dargestellt ist,
• 3 eine schematische Vorderansicht eines LED-Feldes mit einer Reihe von LED-Leuchtelementen und Darstellung der relativen Anordnung einer segmentierten Linse nach einer ersten Ausführungsform zu denselben,
• 4 eine schematische Darstellung von durch die erfindungsgemäße segmentierte Linse abgebildeten resultierenden Lichtbildern der Reihe von LED-Leuchtelementen auf einem Messschirm gemäß 3,
• 5 eine schematische Darstellung von durch die erfindungsgemäße segmentierte Linse abgebildeten resultierenden Lichtbildern der Reihe von LED-Leuchtelementen auf einem Messschirm gemäß 3, wobei eine Lücke zur Bildung eines Entblendungsbereiches infolge des ausgeschalteten Zustands eines der LED-Leuchtelemente vorgesehen ist,
• 6 eine schematische Darstellung von durch die erfindungsgemäße segmentierte Linse abgebildeten resultierenden Lichtbildern der Reihe von LED-Leuchtelementen auf einem Messschirm gemäß 3, wobei dem LED-Feld eine segmentierte Linse nach einer zweiten Ausführungsform zugeordnet ist und
• 7 ein schematischer Vertikalschnitt durch einen als einen nach dem Projektionsprinzip arbeitenden Scheinwerfer nach einer zweiten Ausführungsform, wobei die Optikeinheit eine segmentierte Linse mit zwei Linsensegmenten aufweist.

Show it:

• 1 a representation of a light band on a measuring screen, wherein a row of LED light elements has been mapped by means of a collecting lens according to the prior art,
• 2 a horizontal section through a headlight according to a first embodiment, with a light image of a central LED light element shown on a measuring screen as an example,
• 3 a schematic front view of an LED field with a row of LED lighting elements and representation of the relative arrangement of a segmented lens according to a first embodiment to the same,
• 4th a schematic representation of the resulting light images of the row of LED lighting elements imaged by the segmented lens according to the invention on a measuring screen according to FIG 3 ,
• 5 a schematic representation of the resulting light images of the row of LED lighting elements imaged by the segmented lens according to the invention on a measuring screen according to FIG 3 with a gap being provided to form a glare-free area due to one of the LED lighting elements being switched off,
• 6 a schematic representation of the resulting light images of the row of LED lighting elements imaged by the segmented lens according to the invention on a measuring screen according to FIG 3 , wherein the LED field is assigned a segmented lens according to a second embodiment and
• 7th a schematic vertical section through a headlight operating according to the projection principle according to a second embodiment, the optical unit having a segmented lens with two lens segments.

A headlight for motor vehicles can be used, for example, to generate a low beam distribution or a high beam distribution. For example, the headlight can be used to generate a dynamic high beam distribution, with individual LED lighting elements being switched off or on depending on the traffic situation, that is, on the current position of another road user in front of the vehicle carrying the headlight. An unwanted dazzling of the other road user can be avoided due to a "sharp" gap in a light band.

The headlight essentially consists of a light source 1 and one in the direction of light emission 2 in front of the light source 1 arranged optical unit 3 to generate a given light distribution.

The light source 1 is according to a first embodiment of the invention according to the 2 to 5 from an LED field with a row 4th of LED lighting elements 5 educated. The series 4th of LED lighting elements 5 preferably extends in a horizontal direction. Adjacent LED lighting elements 5 show a clear distance d to each other. The LED lighting elements 5 are each designed as LED chips, the chip having one or more LEDs.

The optical unit 3 ' is designed as a segmented lens (optical element). According to the first embodiment of the invention according to the 2 to 5 exhibits the segmented lens 3 ' three lens segments S1 , S2 , S3 which are integrally connected to each other. The segmented lens 3 ' is designed as a plano-convex lens. According to an alternative embodiment, not shown, the segmented lens can also be designed as a biconvex segmented lens.

The segmented lens 3 ' is to a middle LED light element 5 ' of the LED field 4th aligned, with a transverse median plane Q the segmented lens 3 ' at the same time a transverse central axis Q of the middle LED light element 5 ' forms.

In 2 is an example of a resulting light image (luminous element image) B ₄ of the middle LED light element 5 ' shown that such a length L ₂ has the adjacent resulting light images B ₁ , B ₂ , B ₃ , B ₄ ... B _N of the neighboring LED lighting elements 5 on a measuring screen 12th are arranged directly adjacent to one another in the horizontal direction, see 4th . This results in a homogeneous light strip 6 , the result of a sequence of the resulting photographs B ₁ , B ₂ , B ₃ , B ₄ ... B _N is formed. The light strip 6 extends in the horizontal direction and enables a sharp image of a cut-off line.

The photographs B ₁ , B ₂ , B ₃ , B ₄ ... B _N form resulting light images, each passing through the lens segments S1 , S2 , S3 the photographs shown b ₁ , b ₂ , b ₃ (Partial light images) of the same LED lighting element 5 , 5 ' be generated. As in 2 using the LED light element as an example 5 ' is shown, the result is the photograph B ₄ of the LED lighting element 5 ' from superimposition of the through the first outer lens segment S1 pictured first photo b ₁ , des through the middle second lens segment S2 pictured second photo b ₂ and the third light image formed by means of the outer third lens segment S ₃ b ₃ . The partial light images b ₁ , b ₂ , b ₃ have a different length in the horizontal direction, with adjacent light images b ₁ , b ₂ , b ₃ lie directly next to each other. This results in a homogeneous light image B ₄ .

How out 2 can be seen, point the lens segments S1 , S2 , S3 different optical axes O ₁ , O ₂ , O ₃ on. The optical axis O ₁ of the first lens segment S1 is at a distance e ₁ to the optical axis O ₂ of the middle lens segment S2 arranged. The optical axis O ₃ of the outer lens segment S3 is at a distance e ₂ to the optical axis O ₂ of the middle lens segment S2 arranged. For example, the distances e ₁ , e ₂ the outer lens segments S1 , S2 to the middle lens segment S2 be formed the same. In this case, the segmented lens is symmetrical about the transverse center plane Q arranged. Preferably the optical axes are O ₁ , O ₂ , O ₃ of the lens segments S1 , S2 , S3 arranged parallel offset to one another.

The distance e ₁ , e ₂ the optical axes O ₁ , O ₂ , O ₃ to each other is chosen in such a way that an otherwise occurring gap K between two adjacent photographs A ₁ , A ₂ , A ₃ , ... A _N be avoided, the resulting photographs B ₁ , B ₂ , B ₃ , B ₄ , ... B _N one around the gap K increased length L ₂ compared to length L ₁ the photographs A ₁ , A ₂ , A ₃ , ... A _N state of the art.

In the present exemplary embodiment, there are adjacent edges 7th , 7 ' the partial light images b ₁ , b ₂ , b ₃ directly to each other. According to an alternative embodiment, not shown, the lens segments S1 , S2 , S3 also be designed so that edge areas of the partial light images b ₁ , b ₂ , b ₃ overlap.

When using the headlight for a dynamic high beam, individual LED lighting elements 5 , 5 ' can be switched on or off. How out 5 can be seen, enables the LED light element to be switched off 5 ' a gap 8th in the light distribution, with edges 9 of the divided light band 6 have a relatively high illuminance gradient, which means that a “sharp” glare reduction for the other road user is made possible.

In the present embodiment, the middle lens segment S2 a convex-like contour on one side of the light decoupling, while the outer lens segments S1 , S3 have a divergent contour on the light coupling-out side. This allows color effects on the outer edge 10 of the light strip 6 control or homogenize. For example, the margins 10 due to the different imaging of red or blue spectral components through the lens segments S1 , S3 on the one hand and S2 on the other hand, neutralized to "white" light or changed to a certain color.

According to a second embodiment of the invention 6 can the LED box 11 from a plurality of rows 4th with LED light elements 5 be arranged. The result is a matrix-like or grid-like structure of the LED field 11 . The LED field 11 is as an optical unit 3 a segmented lens 3 '' upstream, which consists of three pairs of lens segments S1 , S1 ', S2 'S2', S3, S3 '. The pairs of lens segments, namely lens segment S1 and S1 'resp. S2 and S2 'resp. S3 and S3 'are identical. The segmented lens 3 '' thus consists of two segmented lenses arranged next to one another 3 ' , with the two segmented lenses 3 ' are integrally connected to each other. The design of six lens segments can be advantageous S1 , S1 ', S2 , S2 ', S3 , S3 'a plurality of light strips arranged next to one another 10 be generated.

The segmented lens 3 , 3 ' , 3 '' can be formed from a glass material or from a plastic material.

According to a further embodiment of the invention according to the 7th the headlight can be designed as a projection headlight working according to the projection principle, the optical unit having an upper reflector 24 , one in the vertical direction under the upper reflector 24 arranged lower reflector 24 ' , one of the reflectors 24 , 24 ' upstream facing edge 22nd as well as one of the blending edge 22nd upstream segmented lens 26th having. The segmented lens 26th has an upper lens segment 27 and a lower lens segment integrally connected therewith 27 ' on, which are each formed plano-convex.

The lower lens segment 27 ' is designed such that an optical axis 28 is formed, which is the blending edge 22nd cuts. The upper lens segment 27 is designed such that an optical axis 29 is formed, which is offset in the vertical direction downwards to the optical axis 28 of the lower lens segment 27 ' is preferably shifted in parallel. This optical axis 29 cuts the lower reflector 24 ' .

How out 7th can be seen, the upper lens segment extends 27 in one area of the lens 26th , the one above the central optical axis 28 is arranged.

The top reflector 24 associated upper LED field 21st with the LED lighting elements 25th is opposite to the opposite lower LED field 21 ' with the lower LED light elements 25 ' of the LED field 21 ' arranged oriented, with the LED lighting elements 25th , 25 ' each perpendicular to the optical axes 28 , 29 the lens 26th are arranged oriented. The upper LED field is used to generate a low beam distribution 21st switched on while the lower LED field 21 ' is turned off. The upper LED field is used to generate a high beam distribution 21st and the lower LED field 21 ' switched on, due to the segmented design of the lens 26th the glare edge shown in the low beam position of the headlight as a light-dark border 22nd is "pushed" downwards so that a homogeneous light illumination is guaranteed.

The upper lens segment is used in both the low beam and high beam function of the headlight 27 as well as the lower lens segment 27 ' by means of the upper reflector 24 reflected rays 30th and from by means of the lower reflector 24 ' reflected rays 30 ' detected.

List of reference symbols

1

Light source

2

Direction of light emission

3, 3 ', 3' '

Optical unit

4th

line

5, 5 '

LED light elements

6th

Light strip

7, 7 '

edge

8th

gap

9

edge

10

edge

11

LED field

12

Measuring screen

21, 21 '

LED field

22nd

Blending edge

24, 24 '

upper reflector

25, 25 '

LED light elements

26th

lens

30, 30 '

Rays

d

clear distance

S1, S2, S3, 27,

Lens segments

27 'Q

Transverse median plane

L ₁ , L ₂

length

A ₁ , A ₂ , A ₃ , ... A _N

Photographs

B ₁ , B ₂ , B ₃ , ... B _N

Photographs

b ₁ , b ₂ , b ₃

Partial light images

O ₁ , O ₂ , O ₃ , 28, 29

optical axis

e ₁ , e ₂

distance

K

gap

Claims (6)

Headlights for motor vehicles with a plurality of LED lighting elements (5, 5 '), which are arranged in an LED field (11) grouped at a distance from one another, and with one in the light emission direction (2) in front of the LED field (11) arranged optical unit (3) for generating a predetermined light distribution, that the optical unit (3) has a segmented lens (3 ', 3''), the at least two lens segments (S1, S1'; S2, S2 '; S3, S3') in such a way that the light images (b ₁ , b ₂ , b ₃ ,) of the LED lighting elements (5, 5 ') imaged by the lens segments (S1, S1'; S2, S2 '; S3, S3') are superimposed and / or are shifted relative to one another that from the light images (b ₁ , b ₂ , b ₃ ) of the lens segments (S1, S1 '; S2, S2'; S3, S3 ') resulting light images (B ₁ , B ₂ , B ₃ , B ₄ , B ₅ , B _N ) are formed which are arranged lying directly next to one another or overlapping on a measuring screen (12), characterized in that the lens segments (S1, S1 '; S2, S2'; S3, S3 ') are configured in such a way that a predetermined color mixture occurs at an edge (10) of the light band (6). Headlights after Claim 1 , characterized in that the lens segments (S1, S1 '; S2, S2'; S3, S3 ') transversely to an optical axis (O ₁ , O ₂ , O ₃ ) of the segmented lens (3, 3', 3 '' ) are arranged directly next to one another and that the lens segments (S1, S1 '; S2, S2'; S3, S3 ') of the segmented lens (3, 3', 3 '') each have a different optical axis (O ₁ , O ₂ , O ₃ ), which are arranged offset from one another at a distance (e ₁ , e ₂ ) from one another as a function of a clear distance (d) between adjacent LED lighting elements (5, 5 '). Headlights after Claim 1 or 2 , characterized in that the lens segments (S1, S1 '; S2, S2 '; S3, S3 ') are matched to one another in such a way that the light images (b ₁ , b ₂ , b ₃ ) of the same light images (B ₁ , B ₂ , B ₃ , B ₄ , B ₅ , B _N ) of a length (L ₂ ) are superimposed, with adjacent edges (7, 7 ') of the light images (B ₁ , B ₂ , B ₃ , B ₄ , B ₅ , B _N ) lying directly next to one another, and that the resulting light images (B ₁ , B ₂ , B ₃ , B ₄ , B ₅ , B _N ) form a homogeneous light band (10). Headlights after one of the Claims 1 to 3 , characterized in that the segmented lens (3 ') has at least three lens segments (S1, S1'; S2, S2 '; S3, S3'), so that the resulting light image (B ₁ , B ₂ , B ₃ , B ₄ , B ₅ , B _N ) from three light images (B ₁ , B ₂ , B ₃ , B ₄ , B ₅ , B) each imaged by the three lens segments (S1, S1 '; S2, S2'; S3, S3 ') _N ) composed. Headlights after Claim 4 , characterized in that the three lens segments (S1, S1 '; S2, S2'; S3, S3 ') extend in the direction of a row (4) of LED lighting elements (5, 5') and that the spacings (e ₁ , e ₂ ) of the outer lens segments (S1, S3) are of the same design as the central lens segment (S2), the segmented lens (3, 3 ', 3 ") being arranged symmetrically to a transverse central plane (Q). Headlights after one of the Claims 1 to 5 , characterized in that the LED field (11) consists of at least two rows (4) of LED lighting elements (5, 5 '), whereby adjacent LED lighting elements (5) are arranged at the same distance (d) from one another, and that the segmented lens (3 ") consists of three pairs of lens segments (S1, S1 '; S2, S2'; S3, S3 '), the lens segments (S1, S1'; S2, S2 '; S3, S3 ') are designed identically and are arranged side by side.

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