Patent Description:
A headlamp of the aforementioned type is known from <CIT>. The headlamp comprises of a plurality of light sources, a light guide unit having a plurality of light guides and a downstream projection lens having a focal plane, wherein each light guide respectively has a light coupling-out surface, wherein the light coupling-out surfaces of at least two adjacent light guides are offset with respect to one another in relation to the focal plane, and/or at least two mutually adjacent light guides in each case make contact with one another along an extent in a contact region, wherein the respective extents deviate from one another, measured in relation to the focal plane.

Another headlamp is known from <CIT>. The headlamp described therein comprises a plurality of first light-emitting diodes (LED) for a high beam and a plurality of second light-emitting diodes for a low beam. The light-emitting diodes can be individually controlled to adapt the generated light distribution to the traffic situation, for example to avoid dazzling an oncoming vehicle. The headlamp also comprises a first light guide for the light emitted by the first light-emitting diodes and a second light guide for the light emitted by the second light-emitting diodes. A light guide element is assigned to each of the light sources, which extends from the light source to the light guide and is comprised by the respective light guide.

A disadvantage of such a headlamp is the small spread of the light distribution produced by the headlamp, in particular the small spread of the low beam light distribution produced by the headlamp, which is in particular approximately ± <NUM>°. In order to increase the spread in the concept described in <CIT>, additional light guide elements would have to be provided, which would lead to higher costs of the headlamp.

The problem underlying the present invention is the creation of a headlamp of the type mentioned above in which an increase in the spread of the light distribution produced by the headlamp, in particular the low beam, is possible at low cost.

This is achieved, in accordance with the invention, by means of a headlamp of the aforementioned kind with the characterizing features of claim <NUM>. The subclaims concern preferred forms of the invention.

Claim <NUM> provides that the first light exit surface and/or the second light exit surface have a structuring, wherein in a region which is arranged centrally in the direction in which the light entry surfaces are arranged side by side, the structuring of the first light exit surface and/or the second light exit surface is not provided. By means of a structuring, the emerging light can be homogenized, which in particular avoids undesirable local intensity maxima on components arranged behind the light exit surfaces. By omitting the structuring in the central region, higher light intensities can be achieved.

At least a first one of the light entry surfaces has a greater width in the direction in which the light entry surfaces are arranged side by side than at least a second one of the light entry surfaces. By such a design, an increase in the spread of the light distribution produced by the headlamp can be achieved. For example, low beam light distributions with a spread of up to more than ± <NUM>° can be obtained with an appropriately designed headlamp. Furthermore, the wider light entry surfaces make the light distribution less sensitive to tolerances in relation to the positioning of the light sources.

It may be provided that at least a first one of the light entry surfaces in the direction in which the light entry surfaces are arranged side by side has such a large width that two of the light sources can be arranged side by side in front of this light entry surface. In this way the light of two light sources can be coupled into these light entry surfaces.

It is possible that the at least one first of the light entry surfaces is arranged further outwardly in the direction in which the light entry surfaces are arranged side by side than the at least one second of the light entry surfaces. In particular, the width of the light entry surfaces increases at least partially from a central region outwards in the direction in which the light entry surfaces are arranged side by side. In this way, two light sources can be selectively positioned in an outer area in front of the light entry surfaces so that a higher illuminance can be achieved in the edge areas of the light distribution.

It may be provided that the at least one first of the light entry surfaces and the at least one second of the light entry surfaces are light entry surfaces of the second light guide. In this way, the low beam light distribution is specifically influenced.

It is possible that each of the light guides has light guide elements which project from the light guides, the ends of the light guide elements facing away from the light guides forming the light entry surfaces. Furthermore, it is possible that a first light guide element, the end of which forms the at least one first of the light entry surfaces, has a greater width over its longitudinal extension in the direction in which the light entry surfaces are arranged side by side than a second light guide element, the end of which forms the at least one second of the light entry surfaces. Due to the greater width over the longitudinal extension of the light guide elements, the light moving through this wide light guide element is distributed over a greater angular range.

It may be provided that the first and/or the second light sources are designed as light-emitting diodes, which are arranged in particular on a common circuit board. By arranging them on a common circuit board, it is relatively easy to influence the light distribution produced by the headlamp, in particular without changing the optical system. This can be achieved by providing differently equipped circuit boards which differ, for example, in the arrangement and/or the number of light-emitting diodes. By replacing one board with another, the light distribution produced by the headlamp can be changed. For example, the spread of the light distribution can be easily changed without changing the optics.

It is possible that the first and/or the second light sources can be controlled individually or in individual groups. In this way, the light distribution produced by the headlamp can be adapted to the traffic situation, e.g. to avoid dazzling an oncoming vehicle.

It may be provided that in a region which is arranged centrally in the direction in which the light entry surfaces are arranged side by side, the structuring of the first light exit surface and/or the second light exit surface is not provided. By omitting the structuring in the central region, higher light intensities can be achieved.

It is possible that the light guides each have a collimating lens which are integrated in particular in the light exit surfaces. By integrating one collimating lens each into the light guides, the efficiency of the headlamp can be increased.

It may be provided that the headlamp comprises an, in particular monolithic, optical component which comprises both the first and the second light guide, in particular with the optical component serving as a primary optics. This design makes it easier to assemble the headlamp, in particular because components can be integrated into one another.

It is possible that the optical component has a light exit surface which is formed by the light exit surfaces of the first and second light guides, in particular wherein the light exit surfaces of the first and second light guides are adjacent to and/or merge into one another. The optical component thus contributes both to the generation of the high beam and to the generation of the low beam.

By structuring the secondary optics, any artifacts generated by the structuring of the primary optics can be minimized.

The invention is explained in more detail below on the basis of the attached drawings.

In the figures, identical and functionally identical parts are marked with identical reference symbols.

The illustrated version of a headlamp according to the invention comprises an unshown circuit board on which a plurality of light sources in the form of light-emitting diodes (LEDs) are arranged. In this case, both several first light sources designed as light-emitting diodes for a high beam and several second light sources designed as light-emitting diodes for a low beam are arranged on the board.

It is possible to use other light sources instead of the light-emitting diodes. For example, semiconductor lasers could also be used as light sources.

The light sources can be controlled separately to switch between low beam and high beam. It is also possible to implement other functions of an adaptive front lighting system by varying the power supply to the light sources, such as city lights, country lights or motorway lights. It is also possible to control the first and/or second light sources individually or in groups. In this way, the light distribution generated by the headlamp can be adapted to the traffic situation, e.g. to avoid dazzling an oncoming vehicle.

The illustrated design of a headlamp according to the invention further comprises an optical component <NUM> serving as a primary optics, in particular a monolithic optical component <NUM>, and a secondary optics <NUM>. During operation of the headlamp, the light emitted by the light sources passes first through the primary optics and then through the secondary optics <NUM>.

The optical component <NUM>, which serves as primary optics, comprises a first light guide <NUM> for the high beam and a second light guide <NUM> for the low beam (see, for example, <FIG>). The light guides <NUM>, <NUM> each have several light entry surfaces <NUM>, <NUM> on their lower side in <FIG> (see also <FIG>), into which the light of the light-emitting diodes is coupled when the headlamp is in operation. On the upper side shown in <FIG> the light guides <NUM>, <NUM> each have a light exit surface <NUM>, <NUM> through which the light emerges.

The light guides <NUM>, <NUM> each have a plurality of light guide elements <NUM>, <NUM>, which protrude from the light guides <NUM>, <NUM>. The ends of the light guide elements <NUM>, <NUM> facing away from the light guides <NUM>, <NUM> form the light entry surfaces <NUM>, <NUM>. The light guide elements <NUM>, <NUM> are essentially finger-shaped or trunk-shaped.

<FIG>, <FIG>, <FIG> and <FIG> illustrates that each of the light exit surfaces <NUM>, <NUM> is curved so that two collimating lenses <NUM>, <NUM> are formed on the optical component <NUM> serving as primary optics, each of which is assigned to one of the light guides <NUM>, <NUM>. The efficiency of the headlamp can be increased by integrating one collimating lens <NUM>, <NUM> each into the light guides <NUM>, <NUM>.

The illustrated version of the secondary optics <NUM> also features a collimating lens <NUM>, which is designed as a biconvex lens (see <FIG>). It is also possible to design the collimating lens <NUM> differently, for example as a plano-convex lens. The cutting width of the collimating lens <NUM> of the secondary optics <NUM> is adapted to the cutting widths of the collimating lenses <NUM>, <NUM> of the primary optics.

The illustrated design of a headlamp according to the invention further comprises an unshown housing in or on which the optical component <NUM> serving as primary optics with the circuit board, the secondary optics <NUM> and a likewise unshown heat sink for the light emitting diodes arranged on the circuit board can be mounted.

<FIG> illustrates that the light exit surface <NUM> of the second light guide <NUM> has a structuring <NUM>. It is certainly possible to also provide the light exit surface <NUM> of the first light guide <NUM> at least partially with this or a comparable structuring <NUM>. The structuring <NUM> can be designed as a prism array, for example. The structuring <NUM> homogenizes the light emerging from the light exit surface <NUM> at least to such an extent that no undesired intensity maxima occur on the secondary optics <NUM> and/or an unshown cover glass.

The structuring <NUM> is recessed in a middle area <NUM>. The light can pass through this recessed area <NUM> relatively unhindered, so that higher light intensities can be achieved.

It is certainly possible to provide a structuring on the collimating lens <NUM> of the secondary optics.

<FIG>, <FIG> illustrate that eleven light entry surfaces <NUM> of the first light guide <NUM> and ten light entry surfaces <NUM> of the second light guide <NUM> are provided, each formed by the distal end of a light guide element <NUM>, <NUM>. If a light source, for example in the form of a light-emitting diode, is arranged in front of each of the light entry surfaces <NUM>, <NUM>, eleven light sources for the high beam and ten light sources for the low beam would be provided.

However, it is quite possible to provide more or less light entry surfaces <NUM>, <NUM> or more or less light guide elements <NUM>, <NUM> on both the first light guide <NUM> and the second light guide <NUM>.

<FIG> and <FIG> illustrate that the light entry surfaces <NUM> of the first light guide <NUM> in the direction in which the light entry surfaces <NUM> are arranged next to each other have the same width. In contrast, the light entry surfaces <NUM> of the second light guide <NUM> in the direction in which the light entry surfaces <NUM> are arranged next to each other have at least partially different widths (see <FIG> and <FIG>).

The width of the light entry surfaces <NUM> and the width of the light guide elements <NUM> essentially increases at least partially from a central area to the outside. Thus a first light entry surface 6a, which is visible at the left outer edge in <FIG>, is considerably wider than a second light entry surface 6b, which is arranged closer to the centre of the light guide <NUM>. Accordingly, the light guide element 10a assigned to the first light entry surface 6a is also significantly wider over its longitudinal extension than the light guide element 10b assigned to the second light entry surface 6b.

Claim 1:
Headlamp for a motor vehicle, comprising
- a plurality of first light sources for a high beam, emitting light during operation of the headlamp,
- a plurality of second light sources for a low beam, emitting light during operation of the headlamp,
a first light guide (<NUM>) having a plurality of light entry surfaces (<NUM>) arranged side by side for the light emitted from the first light sources and a first light exit surface (<NUM>),
- a second light guide (<NUM>) having a plurality of light entry surfaces (<NUM>, 6a, 6b) arranged side by side for the light emitted from the second light sources and a second light exit surface (<NUM>), wherein at least a first one of the light entry surfaces (6a) has a greater width in the direction in which the light entry surfaces (<NUM>, <NUM>) are arranged side by side than at least a second one of the light entry surfaces (6b),
characterized in that the first light exit surface (<NUM>) and/or the second light exit surface (<NUM>) have a structuring (<NUM>), wherein in a region (<NUM>) which is arranged centrally in the direction in which the light entry surfaces (<NUM>, <NUM>) are arranged side by side, the structuring (<NUM>) of the first light exit surface (<NUM>) and/or the second light exit surface (<NUM>) is not provided.