EP3379142A1 - Light module for a vehicle headlamp and motor vehicle headlamp with such a light module - Google Patents

Abstract

The invention relates to a light module (6) for a motor vehicle headlight, which has a light emission unit (10) with a plurality of matrix-like point light sources (10a-10e) and projection optics (12) with at least one projection lens (14, 16) Luminous emission unit (10) emits emitted light as the resulting light distribution of the light module (6) on a roadway (18) in front of the motor vehicle. In order to improve the imaging properties of the projection optics (12), a lens (20) with a concavely curved exit surface (20b) is arranged between the light emission unit (10) and the projection optics (12) Beam angle emitted and incident on the exit surface (20b) of the lens (20) light beams (22a, 22b) by means of total reflection deflects towards the edge, so that they no longer pass through the projection optics (12).

Description

The present invention relates to a light module for a motor vehicle headlight with the features of the preamble of claim 1. Furthermore, the invention relates to a pig headlight with such a light module according to the preamble of claim 11.

Recently, semiconductor light sources (eg, LEDs) comprising one or more LED chips have been increasingly used in automotive headlamp light modules. Such LED light modules usually comprise at least one bundling optical unit in the form of a front lens made of a solid transparent material, in particular plastic or glass. The light emitted by the semiconductor light source or sources is coupled via one or more light entry surfaces in the optical attachment, is at least partially deflected by means of total reflection at interfaces of the optical attachment and finally coupled via one or more light exit surfaces of the attachment optics. The bundling of the light takes place by refraction at the light entrance and / or light exit as well as by the deflection by total reflection.

As a light source of LED light modules a plurality of matrix-like juxtaposed and / or stacked LED chips can be used, which can be controlled separately or in groups separately. In this way, a plurality of partial light bundles can be generated, which complement or overlap the resulting light bundle of the light module for generating the predetermined light distribution. As a result, selected areas of the light distribution, for example in the area of oncoming or preceding vehicles, can be selectively masked out. In this case, a better illumination of the area in front of the motor vehicle can be achieved, since it is more often possible to drive with high beam, whereby dazzling of other road users is prevented since areas in which they are located are deliberately masked out. Such light modules are referred to as multi-beam LED modules or as matrix LED modules. Currently in use multi-beam LED modules include semiconductor light sources, each having 84 matrix-like LED chips. The light distribution of the light module is thus composed of 84 areas that can be hidden or illuminated individually or in groups. Such a light distribution is also referred to as adaptive driving beam (ADB), glare-free high beam or partial high beam. In the example mentioned, a light pixel corresponds to the light distribution at a distance of 100 m in front of the motor vehicle of an area of 1.8 × 2.4 m. To capture the position of other road users in the environment of a Motor vehicle, the motor vehicle has suitable sensors, eg. In the form of a camera, and suitable processing logic that determines the position of the other road users from the sensor signals and generates suitable drive signals for the light modules or their LED chips.

A matrix LED module is the basic structure ago, for example, from the DE 100 09 782 A1 known. It shows how such a matrix LED module can be used in combination with a projection lens to generate a variable light distribution. If a matrix LED module is integrated into a headlight of a motor vehicle, the light distribution can be adapted dynamically to the traffic conditions (eg oncoming or preceding vehicle) with the aim of optimal light distribution for the driver of the motor vehicle and at the same time dazzling other road users to avoid.

Recent developments in the field of multi-beam LED modules include so-called pAFS (micro-structured adaptive front-lighting system) light modules, in which a matrix with currently up to 1,024 individually controllable LEDs is used. In particular, a multiplicity of white LEDs (eg blue LEDs with integrated converter) are arranged in a particularly densely packed manner on an LED chip, so that they can produce an almost completely seamless switchable light surface which can be used for a multiplicity of punctiform light sources (so-called pixels, eg per LED one pixel). Each LED emits light with a lambertian radiation distribution in the half space perpendicular to the light exit surface of the LED. In the headlight, a projection optic forms the light surface as a light distribution on the road ahead of Motor vehicle off. When using, for example, four of these LED chips in a light module, the resulting light distribution of a single light module thus includes, for example, 4,096 subareas (so-called light pixels) which can be blanked out individually or in groups. When using two headlamps in a motor vehicle, the light distribution is thus divided into 8,192 light pixels. This finer subdivision of the light distribution makes it possible to bring the illuminated areas of the light distribution closer to the position where other road users were detected, and thus to achieve improved illumination in front of the motor vehicle, but without dazzling other road users.

Another recent development in the field of multi-beam LED modules allows an even finer subdivision of the resulting light distribution. These are so-called DLP (digital light processing) light modules, in which the light from an LED (eg high current LED) is directed to a micromirror array, which includes a plurality (for example, more than 1 million) tiny micromirrors , which can be individually controlled and tilted with a frequency of up to 5,000 Hz. For deflecting the light emitted by the LED, a concave mirror can be used. A pixel of the light distribution corresponds to a surface of only 4.0 x 2.5 cm at a distance of 100 m in front of the motor vehicle. The state of the individual mirrors determines the path of the light. If one of the micromirrors is in its initial position, it reflects the light incident on it completely via projection optics, which are designed, for example, as a projection lens, onto the road ahead of the motor vehicle. When the micromirror is completely tilted (by about 10 °), the reflected light no longer lands on the road, but, for example, in a light trap, so that the corresponding light pixel is deactivated and there is an unlit spot in the light distribution. In the intermediate stages and depending on the switching frequency of the micromirrors, gray levels (with lower brightness) can be generated at the respective light pixels. Headlamps with a DLP module are also referred to as HD (high definition) headlights.

In the mentioned types of light modules, the light distribution must be generated as accurately as possible in front of the motor vehicle. This applies in particular when the light modules produce a dimmed light distribution with a light-dark boundary between the illuminated near area of the light distribution and the non-illuminated far area or a partial high beam with horizontal and vertical light-dark boundaries between the illuminated areas (light pixels) of the light distribution and the non-illuminated areas should. The finer the subdivision of the light distribution into light pixels, the more important is a highly accurate positioning of the light distribution or of the individual light pixels in front of the motor vehicle in order to prevent dazzling of other road users.

Since projection optics can focus only light with an upward limited opening angle (eg maximum +/- 20 °), it is advantageous to limit the emission range of the light emission unit. Light that falls on the projection optics at too great an angle is poorly or blurred due to optical aberrations, which generally increase with the angle of incidence oblique to the optical axis. In addition, light that can enter at large angles of incidence Projection optics fall, lead to stray light, which further reduces the contrast of the image. Thus, the accuracies of the light distribution required with pAFS modules and DLP modules can not be achieved.

Based on the described prior art, the present invention has the object to provide a compact, optical projection system for matrix LEDs available, which prevents light incident at too large angles of incidence in the projection optics.

To solve this problem, a light module is proposed with the features of claim 1. In particular, a light module for a headlamp of a motor vehicle is proposed, wherein the light module has a light emission unit with a plurality of point-like light sources arranged in a matrix, each emitting light with a Lambertian radiation characteristic, and projection optics having at least one projection lens which illuminate the light emitted by the light emission unit as the resulting light distribution of the light module on a roadway in front of the motor vehicle. Furthermore, the light module comprises in a beam path between the light emission unit and the projection optics a lens which has a concave curved exit surface on the side remote from the light emission unit. The exit surface deflects light emitted by the light emission unit with a large emission angle and impinging on the tread surface of the lens by means of total reflection toward the edge, so that it no longer passes through the projection optics.

According to the present invention, therefore, a lens in a main radiation direction of the light emission unit arranged in front of this, so that the light emitted by the light emission unit light hits the lens. The lens has an entrance side directed toward the light emission unit and an outlet side facing away from the light emission unit. The exit side has a concave curvature. This causes the light emitted by the light emission unit at large angles (eg> 30 °) relative to the optical axis and incident on the exit surface to be totally reflected and dissipated laterally. This prevents it from reaching the projection optics and being imaged by them. As a result, the imaging properties of the projection system can be improved, in particular the contrast and the sharpness of the image can be increased.

The use of a lens for filtering out light emitted by the light emitting unit at a large angle of radiation from the beam used to generate the light distribution has over the use of a diaphragm, such as WO 2013/020 156 A1 is known, significant benefits. The effective area or edge of a panel always has a fixed position with respect to the light-emitting unit. In the case of the lens used according to the invention, on the other hand, due to the curvature of the totally reflecting exit surface, there is a shift in the surface areas of the exit surface which are effectively used for the total reflection, depending on which position in the light emission unit the respective punctiform light source is arranged. Area sections used for punctiform light sources arranged at the outer edge of the light emission unit are located higher on the exit surface (and thus have a greater curvature) than the area of the exit surface (with less curvature) used for punctiform light sources located at the center of the light emitting unit. This would be something like an aperture for the light rays of punctiform light sources arranged at the outer edge of the light emitting unit, which is located slightly further outside than a diaphragm for the light rays of punctiform light sources arranged in the center of the light emission unit. Since the individual point-shaped light sources preferably emit light forward in a main emission direction, the use of a lens increases the efficiency of the light module over the use of a diaphragm, since less light is lost (filtered out) when using a lens with the point-shaped light sources arranged at the outer edge of the light source , is deflected towards the edge) than when using a shutter.

According to an advantageous development of the invention, it is proposed that the light reflected toward the edge strike an outer edge of the optical system which has light-absorbing properties. As a result, scattered light, which could be caused by the light deflected from the exit surface to the edge, can be prevented, since the deflected light can no longer pass uncontrolled back to the projection optics and on into the resulting light distribution. Advantageously, a light-absorbing layer is applied to the outer edge of the optic.

According to a preferred embodiment of the invention, it is proposed that the point-like light sources arranged in the form of a matrix are used as semiconductor light sources, in particular as light-emitting diodes (LEDs) or semiconductor lasers are formed. Such a light module is also referred to as a multi-beam LED module or as a matrix LED module. Advantageously, the light module has over 1,000 individually controllable semiconductor light sources. Such a light module is preferably a pAFS (micro-structured adaptive front-lighting system) light module, in which a small LED chip with a plurality (currently up to 1024) individually controllable LEDs is used.

As light beams which are emitted in a 'large beam angle' in the context of the present invention by the light emitting unit, such light rays are called, which are due to optical aberrations on the projection optics poor, especially blurred, imaged on the road and / or lead to stray light which reduces the contrast of the picture. As a rule, projection optics can focus only on light with an opening angle limited to approx. +/- 20 °. Light beams with opening angles greater than +/- 20 °, in particular greater than +/- 30 °, are thus prevented from hitting the projection optics.

The entrance surface of the lens facing the light emitting unit may be arbitrarily (e.g., curved). However, the light emission unit facing the entrance surface of the lens is preferably formed flat. It is also conceivable for an antireflection coating to be applied to the entrance surface of the lens facing the light source in order to prevent backscattering of the light emission unit.

The projection optics of the light module preferably comprises several in the beam path arranged one behind the other Projection lenses.

The object underlying the present invention is further achieved by a motor vehicle headlight having the features of claim 14. This has a light module according to the invention.

Figur 1

einen erfindungsgemäßen Kraftfahrzeugscheinwerfer gemäß einer bevorzugten Ausführungsform;

Figur 2

ein erfindungsgemäßes Lichtmodul gemäß einer bevorzugten Ausführungsform mit beispielhaft eingezeichneten Lichtstrahlen; und

Figur 3

das Lichtmodul aus Figur 2 mit anderen beispielhaft eingezeichneten Lichtstrahlen.

Further features and advantages of the present invention will be explained in more detail with reference to FIGS. Show it:

FIG. 1

a motor vehicle headlamp according to the invention according to a preferred embodiment;

FIG. 2

an inventive light module according to a preferred embodiment with exemplified light beams; and

FIG. 3

the light module off FIG. 2 with other exemplified light beams.

The present invention relates to a light module and a motor vehicle headlight with such a light module. Such a headlight 1 is exemplary in FIG. 1 shown and serves to generate a predetermined light distribution. The light distribution can be any headlight function, for example dipped beam, high beam, fog light or any adaptive light distribution (eg partial high beam). It is also conceivable that the light distribution generated by the headlight 1 is an indication (eg symbol) for the information of a driver of the motor vehicle or of persons in the vicinity of the motor vehicle about certain ambient and / or vehicle situations, which is displayed on the road in front of the vehicle. The reference may, for example, a road sign (to warn the driver of certain dangerous situations), a stylized pedestrian (to warn the driver of pedestrians on the roadside), a crosswalk (to inform pedestrians that the vehicle stops and the road can be crossed) , an ice crystal (to warn the driver against slippery roads), or a turn-off (eg arrow) of a navigation system.

The headlight 1 comprises a housing 2, which preferably consists of an opaque material, in particular plastic. In a light exit direction 3, the housing 2 has a light exit opening 4, which is closed by a cover 5. The cover 5 is preferably made of a transparent material, for example. Glass or plastic. The cover 5 is formed without optically active elements. At a merely schematically drawn position 6, a light module 6 is arranged in the interior of the housing 2, which is described below with reference to FIG FIGS. 2 and 3 is explained in more detail. The light module 6 serves to generate the light distribution of the headlight 1 or a part of the light distribution. The headlight 1 is preferably arranged at any desired location on the outside in the front region of the motor vehicle.

A first preferred embodiment of the light module 6 is exemplary and schematically in FIG FIG. 2 shown. The light module 6 comprises a light emission unit 10 with a plurality of point-like light sources 10a-10e arranged in the form of a matrix, which each emit light with a Lambert radiation pattern, and a projection optics 12 with at least one projection lens 3, 4. In the example shown here, the projection optics 12 comprises two lenses 14, 16 arranged in the beam path one behind the other. The projection optics 12 images the light emitted by the light emission unit 10 as the resulting light distribution of the light module 6 on a roadway 18 in front of the motor vehicle. The roadway 18 is symbolized here by way of example by a standing in front of the vehicle at a distance measuring screen.

The light module 6 has, in the beam path between the light emission unit 10 and the projection optics 12, a lens 20 with a concavely curved exit surface 20b on the side of the lens 20 remote from the light emission unit 10. The exit surface 20b deflects light rays emitted by the light emission unit 10 with a large emission angle and impinging on the exit surface 20b of the lens 20 (eg rays 22a and rays 22b directed towards the edge of the lens 20) by means of total reflection towards the edge, so that it no longer passes through the projection optics 12 passes. Only the light emitted by the light emitting unit 10 with a relatively small emission angle (e.g., rays 22c) is transmitted through the lens 20 and imaged on the lane 18 by the projection optics 12.

As light beams which are emitted by the light emission unit 10 in a 'large radiation angle' in the sense of the present invention, such light beams 22a, 22b are referred to which (without the lens 20) due to optical aberrations on the projection optics 12 bad, in particular blurred the roadway 18 are displayed and / or lead to stray light, which reduces the contrast of the image on the roadway 18. Projection optics 12 can usually only Sharp light with an opening angle limited to approx. +/- 20 °. Light beams with aperture angles greater than +/- 20 °, in particular greater than +/- 30 °, are thus prevented in the invention from hitting the projection optics 12.

The light emitting unit 10 may be formed differently. According to a first possibility, the individual point-shaped light sources 10a-10e of the light emission unit 10 each comprise a semiconductor light source, in particular a light-emitting diode (LED). The LEDs can be selectively controlled individually or in groups in order to switch the semiconductor light sources on or off or to dim them. The light module 6 has, for example, over 1,000 individually controllable LEDs. These are preferably mounted on a common circuit board (not shown) and contacted via this electrically. In particular, the light module 6 can be designed as a so-called pAFS (micro-structured adaptive front-lighting system) light module. According to another possibility, the light-emitting unit 10 has a semiconductor light source and a micromirror array comprising a plurality of micromirrors which can be individually controlled and tilted, each of the micromirrors forming one of the point-shaped light sources of the light-emitting unit 10. The micromirror array comprises, for example, at least 1 million micromirrors which can be tilted at a frequency of up to 5,000 Hz.

In order to prevent stray light, the edge of the lens 20 has optically absorbing properties. In particular, on the edge of the lens 20, an absorbent layer 24 (see. FIG. 3 ) be applied. The absorbing layer 24 consists, for example, of black color. One of the Light emitting unit 10 facing entrance surface 20a of the lens 20 is preferably flat. An antireflection coating may be applied to the entrance surface 20a in order to prevent backscattering of the light emission unit 10. The control of the individual pixels of the light emitting unit 10 and thus also the resulting light distribution of the light module 6 is controlled by a control electronics, not shown here, as for example. From the DE 10 2009 054 227 A1 is known. The control electronics receives from a suitable sensor, for example from a camera, information about the traffic situation (eg on vehicles in front or oncoming traffic) and generated in response to corresponding control signals for the point-shaped light sources 10a-10e. In this way, as a light distribution, for example, a glare-free high beam can be generated.

In the FIGS. 2 and 3 is an external point light source 10a of the light emitting unit 10 (see. FIG. 2 ) and a corresponding exemplary beam path and a further inside (eg a central) point light source 10c (see. FIG. 3 ) and a corresponding exemplary beam path. Based on FIG. 2 It can be clearly seen that the light emitted at large angles is totally reflected at the exit surface 20b. The radiation angles above which total reflection occurs are not symmetrical as in FIG. 3 , The rays 22b directed toward the edge of the lens 20 are totally reflected at smaller angles than the rays 22a facing towards the center, since the curvature of the lens 20 and the exit surface 20b increases towards the edge. This is advantageous for the imaging quality of the projection system shown, since marginal rays 22b in Generally less well mapped.

If the lens 20 and the projection lenses 14, 16 consist of materials with different dispersion (Abbe number), the arrangement can be used at the same time for the compensation of achromatic errors. Achromatic systems generally consist of a combination of concave and convex lenses.

Claims (13)

Light module (6) for a headlight of a motor vehicle, wherein the light module (6) comprises a light emission unit (10) with a plurality of point-like light sources (10a-10e) arranged in a matrix, each emitting light with a Lambert radiation pattern, and projection optics (12) with at least one projection lens (14, 16), which images the light emitted by the light emission unit (10) as a resulting light distribution of the light module (6) on a roadway (18) in front of the motor vehicle, characterized in that in a beam path between the light emission unit (10) and the projection optics (12) a lens (20) having a on the side facing away from the light emitting unit (10) side concave exit surface (20 b) is arranged, wherein the exit surface (20 b) from the light emission unit (10) with a large Abstrahlwinkel emitted and incident on the exit surface (20b) of the lens (20) light rays n (22a, 22b) deflects towards the edge by means of total reflection, so that it is no longer deflected by the projection optics (12). pass. Light module (6) according to claim 1, characterized in that the rays of light (22a, 22b) reflected toward the edge strike an outer edge of the optical system (20) which has light-absorbing properties. Light module (6) according to claim 2, characterized in that on the outer edge of the optical system (12) a light-absorbing layer (24) is applied. Light module (6) according to one of claims 1 to 3, characterized in that the punctiform light sources (10a-10e) of the light emitting unit (10) semiconductor light sources, in particular light-emitting diodes comprise. Light module (6) according to claim 4, characterized in that the light module (6) has over 1,000 individually controllable semiconductor light sources. Light module (6) according to claim 4 or 5, characterized in that the light module (6) is designed as a pAFS (micro-structured adaptive front-lighting system) light module (6). Light module (6) according to one of claims 1 to 3, characterized in that the light emitting unit (10) comprises a semiconductor light source and a micromirror array comprising a plurality of micromirrors, the can be individually controlled and tilted, wherein each of the micromirrors forms one of the point-shaped light sources (10a-10e) of the light emission unit (10). Light module (6) according to claim 7, characterized in that the micromirror array comprises at least 10 ⁶ micromirrors, which can be tilted at a frequency of up to 5,000 Hz. Light module (6) according to one of claims 1 to 8, characterized in that the exit surface (20b) of the lens (20) from the light emission unit (10) with a radiation angle> 20 °, preferably> 30 °, emitted and on the exit surface (20). 20b) of the lens (20) incident light beams (22a, 22b) deflects by total reflection towards the edge. Light module (6) according to one of claims 1 to 9, characterized in that one of the light emitting unit (10) facing the entrance surface (20a) of the lens (20) is flat. Light module (6) according to one of claims 1 to 10, characterized in that on one of the light emitting unit (10) facing the entrance surface (20a) of the lens (20) an antireflection coating is applied. Light module (6) according to one of claims 1 to 11, characterized in that the projection optical system (12) comprises a plurality of projection lenses (14, 16) arranged one behind the other in the beam path . Headlamp (1) of a motor vehicle, the headlamp (1) comprising a housing (2) with a light exit opening (4) closed by a transparent cover (5) and with a light module (6) arranged in the housing (2) Light distribution through the cover (5) on a roadway (18) in front of the motor vehicle images, wherein the light module (6) a Lichtaussendung unit (10) with a plurality of matrix-like point-shaped light sources (10a-10e), each with a lambert'schen light Emit radiation characteristic, and a projection optical system (12) having at least one projection lens (14, 16) which images the light emitted by the light emitting unit (10) emitted light as resulting light distribution of the light module (6) on a roadway (18) in front of the motor vehicle, characterized in that the light module (6) is designed according to one of Claims 1 to 12.

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