EP3052853A1

EP3052853A1 - Illumination device for a motor vehicle and motor vehicle

Info

Publication number: EP3052853A1
Application number: EP14780762.2A
Authority: EP
Inventors: Carsten Gut; Jürgen Wilhelmy
Original assignee: Audi AG
Current assignee: Audi AG
Priority date: 2013-10-02
Filing date: 2014-10-01
Publication date: 2016-08-10
Anticipated expiration: 2034-10-01
Also published as: EP3052853B1; DE102013016423A1; WO2015049048A1

Abstract

The invention relates to an illumination device (1, 1') for a motor vehicle (17), comprising a laser light source (2), a radiation converter (6) containing a fluorescent material, in particular phosphorus, and a reflector (5), wherein laser light transmitted from the laser light source (2) is converted in the radiation converter (6) into secondary light which is in particular white and has a greater bandwidth by comparison with the laser light, and is spread. Said secondary light is redirected by the reflector (5) into a transmission direction of the illumination device (1, 1'), wherein in an impact region (8) of the reflector (5), which in the absence of the radiation converter (6) is exposed to the laser light, a protective means is provided for reduction of the light intensity of laser light transmitted from the illumination device (1, 1') in the absence of or damage to the radiation converter (6).

Description

Beieuchtungseinrichtung for a motor vehicle and motor vehicle

The invention relates to a lighting device for a motor vehicle, comprising a laser light source, a radiation material containing a fluorescent material, in particular phosphorus, and a reflector, wherein emitted from the laser light source laser light in the radiation converter in compared to the laser light broadbandigeres, in particular white secondary light converted and fanned is, which secondary light is deflected by the reflector in a direction of emission of the illumination device. In addition, the invention relates to a motor vehicle.

Today's motor vehicles have a multiplicity of illumination devices, in particular signal lights and / or headlights arranged outside the motor vehicle. Headlamps in particular pose a challenge. Headlamps have been proposed that produce the necessary light through LEDs. Although this can realize a much more efficient generation of light, but the headlights, especially due to the cooling facilities, heavier.

In a further improvement approach, lighting devices for motor vehicles have been proposed, whose light source is a laser light source, in particular comprising at least one laser diode. For example, the light from at least one laser diode can be directed through a light guide onto a reflector which reflects it in a direction of emission. However, there is the problem that on the one hand laser light sources generate light of a certain wavelength, on the other hand extremely focused light. While it is fundamentally conceivable to combine the light of several laser diodes of different colors, it has also been proposed to use the laser light with the use of a radiation converter (also known as

CONFIRMATION COPY Naming light conversion body) into white light. In particular, radiation converters with phosphorus are known, for example as a phosphor coating, since phosphorus has fluorescent properties and can thus generate broadband secondary light, in particular white secondary light, from laser light of a suitable wavelength. If, for example, blue light is generated in a laser light source and irradiated onto a radiation converter made of yellow phosphor, the radiation converter converts the light into white light. The radiation converter, in particular phosphorus, further has the property that a beam divergence occurs, that is, the secondary light is generated fanned out. This beam divergence ensures that any unwanted effect of the focused laser light on people is lifted. A radiation converter may for example consist of a ceramic, is sintered in the phosphor.

However, if the radiation converter is removed or damaged, besides the conversion of the laser light into the secondary light, the fanning effect and laser light can be eliminated, which is undesirable.

The invention is therefore based on the object to improve a lighting device with regard to damage cases of a radiation converter.

To solve this problem is provided according to the invention in a lighting device of the type mentioned that a protection means for reducing the light intensity emitted by the illumination device laser light in case of elimination or damage of the radiation converter in an impact area of the reflector, which is exposed to the laser converter in the absence of the Strahlungskonverters is provided.

Accordingly, suitable mechanical and / or optical measures are proposed in order to avoid as much as possible the leakage of high-intensity, possibly interfering effects triggering laser light in case of elimination or damage of the radiation converter, so that unwanted Light effects due to stray laser radiation are avoided as far as possible. For example, in this way distractions are avoided by intensively illuminated areas in the illumination area and the like.

The radiation converter, which preferably consists of or comprises phosphorus, in particular of yellow phosphorus when using blue laser light, basically ensures conversion and fanning out of the laser light, so that secondary light is produced. The beam divergence produced by the radiation converter at least partially disappears when the radiation converter is damaged or at least partially removed, for example falling off. Then, the laser light having a preferred direction has a non-reversed effect on the impact area of the reflector, which is determined, in particular, by the divergence angle of the exiting laser light. If an optical fiber is used, from which the laser light emerges, for example at one end of the optical fiber, the divergence angle of the exiting laser light (laser beam) is determined by the numerical aperture of the optical fiber. Consequently, in these and other cases, it can be easily determined where the reflector would be affected by the converted laser light when the radiation converter is eliminated, so that the impact area results. It is now proposed to design this impact area of the reflector such that, at least in the event of a fault, ie when the radiation converter is omitted or damaged, no such reflection occurs that the laser light is deflected as a beam in the direction of emission of the illumination device, that is, the light intensity from out of the illumination device emitted laser light is reduced, preferably zero, so that in case of failure no laser light can escape from the illumination device and can cause disturbing effects. A reduction of the light intensity should be such that disturbing and / or unwanted effects are avoided by the laser light.

Specifically, the illumination device can be configured overall so that an exit surface of the laser light source, in particular an end of a light guide of the laser light source, directly with the radiation converter connected and directed to the reflector and / or that the radiation converter has a Lambertian radiation characteristic. The radiation converter can therefore directly connect to an exit surface of the laser light source, which can also be defined by a focus region of at least one laser diode as a laser light source or at several laser diodes on a beam combiner ("beam combiner") may be formed, so that preferably the exit direction of the laser light source in the direction of The secondary light is thus radiated in the direction of the reflector, where the desired light distribution of the illumination device is formed, whereby the radiation converter, in particular the phosphor body, can have a lambert radiation characteristic in the converting, error-free state, which corresponds to the aforementioned fanning out.

For the specific embodiment of the protective means, several possibilities are conceivable according to the invention, after the protective agent can in particular have an absorbing and / or diverging effect. Thus, in a first embodiment of the present invention, it is provided that the protective means is a diverging element formed from the reflector and / or applied to the reflector. A divergent element ensures that a laser light incident as a beam in the impingement region is fanned out in such a way that the light intensity is distributed over a larger angular range and thus disturbing and / or unwanted optical effects are avoided. In this case, it is preferred if the divergent element is formed from the reflector itself, in particular by a suitable shaping, for example by providing a curvature in the area of impact. However, it is also conceivable to apply an additional divergence body as divergent element to the reflector at least in the impact area, for example a diverging coating.

Specifically, the diverging element in the impingement region may have a convex or concave, in particular round shape. An example is a part-ball-like element with a fixed radius of curvature; however, this can vary. In this case, the radius of curvature, for example, of be made dependent on the expected maximum intensity of the laser beam at the corresponding location, so that a sufficiently divergent reflection property is given. Generally speaking, it can thus be provided that the diverging element is formed in the impact area as a function of the beam geometry of the laser light. If necessary, the beam geometry also includes the location-dependent beam intensity. This beam geometry can be determined from the special properties of the optical elements used, for example, the already mentioned divergence angle of the exiting laser beam.

The advantage of reflecting, diverging elements is generally that the laser light is then not (only) absorbed, but distributed, so that little or little additional cooling is necessary. However, laser light is emitted in most cases, albeit considerably attenuated. With a suitable design of the diverging element, however, this can also be used to advantage by ultimately a kind of "emergency operation" of the lighting device is realized, for example, a glow in the color of the laser light with weaker brightness or the like.

In an alternative or using a plurality of protective means additional embodiment for using a diverging element may be suitably provided that the protective means is a jet trap. Beam traps ("beam dumps") are already known in principle in the prior art, in particular for laser light.) Beam traps are optical elements which serve to absorb a light beam, in this case the beam of laser light Also, black-colored aluminum cones in housings that may have, for example, a ribbed inner wall that is colored black have been proposed, however, depending on the present performance, flat surfaces and the like are also considered Jet traps become known. In a concrete embodiment, the jet trap may be an absorption body arranged behind the reflector which is perforated in the impact area. The reflector can be broken in the impact area, so that behind it, for example, a cavity, as described, can follow, in which the laser light is trapped and absorbed. However, it is also possible and preferred for the absorption body to be at least part of a heat sink, in particular a black-colored aluminum heat sink for the lighting device. If an already existing heat sink is used, ultimately, the dissipation of the heat resulting from the absorption of the laser light is also taken care of, so that in the end heat sinks, in particular the heat sinks assigned to the lighting device itself, can be used multiple times. If the heat sink is in any case provided with a ribbed surface, a jet trap can easily be produced, for example, by blackening.

It can additionally or alternatively be provided that the reflector is provided in the impact area with a coating which reflects up to a limit temperature being exceeded. In this way, the reflector can be used normally with the usual radiation characteristic until too high a heating occurs due to the unconverted laser radiation and the coating changes its properties, that is to say it can no longer be used as a reflective surface. There are several possibilities to change the properties. For example, it is conceivable that the coating or layer becomes permeable at least for the laser light when the limit temperature is exceeded, in particular when the jet trap is arranged behind it. A permeability can ultimately also be generated by omission, ie destruction, of the coating; in other words, this means that destruction of the reflector surface can take place in the impact area, which is particularly expedient if the beam trap is located behind it. However, the coating may optionally also act as a jet trap after the limit temperature has been exceeded, but this is less preferred, in particular due to the cooling requirement that arises, even if heat-dissipating materials or even cooling bodies of cooling fluid are applied to the corresponding coating. directions themselves can be coupled. If the coating is fundamentally reflective, then the normal optical properties of the reflector can be further realized for normal operation, so that no corrective measures are required. Only in the event of an error occurs the laser light as much as possible absorbing effect.

The general advantage of beam traps is that the laser light is absorbed as much as possible, thus any light effects can be avoided in an error case and thus a defect is easy to recognize, on the other hand disturbing light effects, such as unwanted light distribution, even at lower light intensities largely can be avoided.

In a generally advantageous embodiment of the illumination device according to the invention, the reflector may be shaped to correct aberrations resulting from the protection means. By using the protective means so aberrations can occur in the reflector, which can be taken into account in the design of the reflector in order nevertheless to obtain as precisely as possible the desired light distribution of the illumination device. To determine suitable shapes of reflectors and the like, conventional optical simulation and planning programs can be used.

In a particularly advantageous embodiment of the present invention can be provided that in the impact area and / or as part of the protection means, a measuring device, in particular a photodetector, is arranged, wherein the operation of the laser light source controlling control device for evaluating the measurement data of the measuring device and for deactivating the Laser light source is formed upon detection of a threshold value exceeding a particular amount of laser light. This means that a measuring device, in particular a photodetector, can be introduced in the impact area, preferably when using a beam trap. Such a measuring device can measure the incoming absolute or relative radiation, thus providing measurement data that after a suitable evaluation of a statement about whether laser light is present in the impact area, so that can be inferred from a certain amount of laser light to an error case and a shutdown of the laser light source can be made. It can be provided that the control device is designed to determine a spectrum and / or an intensity of the incident light on the measuring device. Laser light that strikes the impact area and thus the measuring device directly, that is to say converted, has two consequences: on the one hand, the spectrum of the incident light changes, for example, if it is shifted more or even completely toward the wavelength emitted by the laser light source or even only from this is formed. On the other hand, if the fanning effect of the radiation converter is omitted, a higher light intensity is given, which of course can be measured as well. For example, if the spectrum deviates too much from the spectrum desired by the radiation converter and / or the intensity exceeds a limit value for the intensity, deactivation of the laser light source can take place.

In addition to the illumination device, the invention also relates to a motor vehicle which comprises at least one illumination device of the type according to the invention. In this case, the illumination device is preferably a headlight, in particular a headlight. All embodiments of the illumination device according to the invention can be analogously transferred to the motor vehicle according to the invention, so that here too the advantages of the invention can be obtained.

Further advantages and details of the present invention will become apparent from the embodiments described below and with reference to the drawing. Showing:

1 shows a lighting device according to the invention in a first embodiment in error-free operation,

Fig. 2, the illumination device of FIG. 1 in the absence of

Radiation converter, Fig. 3 shows a lighting device according to the invention a second

Embodiment in normal operation,

Fig. 4, the illumination device of FIG. 3 in the absence of

Radiation converter,

5 shows a lighting device according to the invention in a third embodiment with error-free operation,

Fig. 6, the illumination device of FIG. 5 in the absence of

Radiation converter,

Fig. 7 shows a coating on a reflector, and

8 shows a motor vehicle according to the invention

1 shows a schematic diagram of a lighting device 1 in normal operation. A laser light source 2 comprises at least one laser diode 3, in particular also a plurality of laser diodes 3, whose light can be brought together by a beam combiner not shown here. The laser light is not irradiated directly to the reflector 5 in normal operation, but placed between the laser diode 3 and the reflector 5, in particular directly on an exit surface of the laser light source 2, a phosphor comprehensive radiation converter 6 is arranged, which converts the laser light into white secondary light and this fan-out, as indicated by the arrows 7. In this case, the radiation converter 6 has a lambert radiation characteristic, so that the reflector 5 can be illuminated relatively uniformly.

If the radiation converter 6 were omitted, the laser light from the laser light source 2 would impinge directly on the reflector 5, namely in a previously ascertainable, for example, calculable, impact area 8. This results in the present case from the divergence angle of the end of the of the optical fiber 4 emerging laser beam, which is determined by the numerical aperture of the optical fiber 4. In the impact area 8, the reflector 5 is now obviously modified, in which a divergent element 9 is provided as protection means, which may be formed from the reflector 5 itself, for example by bulging the reflector, or may be applied to the reflector 5. In this case, a partial omission of the radiation converter 6 is conceivable, in which case a part of the laser light impinges directly on the diverging element 9.

As can be seen in more detail from FIG. 2, which shows a schematic diagram of the illumination device 1 without radiation converter 6, ie in the event of a fault, the diverging element 9, which is otherwise concave here, ensures a fanning out of the laser light by disturbing optical effects avoid. Obviously, due to the positioning of the diverging element 9 in the impingement region 8, the laser light impinges on the diverging element 9 as beam 10, where it is deflected in different directions due to the curved surface of the divergent element 9, that is fanned out, arrows 11. The laser light thus emerges not with full intensity from the lighting device 1, where it could, for example, hit people or could produce disturbing light distributions, but is deflected in various directions and thus "distributed." It should be noted at this point that the reflector 5 is configured is that aberrations resulting from the divergent element 9 are corrected in normal operation, thus the desired light distribution is obtained.

The diverging element 9 is also designed to be thermally stable, after it can come by the laser beam 10 to greater heat.

3 and 4 show a comparison with FIGS. 1 and 2 modified second embodiment of a lighting device 1 ', in which the main difference, the laser light source 2 identifies a light guide 4, the laser light of at least one laser diode 3 in the region of the reflector 5 leads , The radiation converter 6 is directly on the exit surface of the Optical fiber 4 is arranged. Through the light guide 4, an annular or elliptical distribution of the laser light is formed.

If therefore the radiation converter 6 falls away according to FIG. 4, then the laser light of this beam geometry impinges on the divergent element 9, which is modified with respect to FIGS. 1 and 2 as a function of this beam geometry, ie in its concrete form, in particular the radius of curvature Beam geometry is designed accordingly. For example, in the case of an annular distribution of the laser light, a spherical shape of fixed radius can be expedient as divergent element 9.

Fig. 5 shows a third embodiment of a lighting device 1 ", wherein the same parts are provided with the same reference numerals for simplicity. Fig. 5 again shows the normal operation, Fig. 6 shows the error operation in case of loss or damage of the radiation converter 6. Although there again Of course, the design of the protective means can also be used with other laser light sources 2, for example those of FIGS. 1 and 2.

Visible in the third embodiment, the reflector 5 in the impact area 8 is broken, wherein behind the aperture arranged as an absorption body beam trap 12 is arranged, which in the present case forms part of an already provided for the illumination device heat sink 13. The heat sink 13 is made of aluminum and is at least in the area of the jet trap 12 ribbed and blackened. The beam trap 12, as shown schematically in FIG. 6, absorbs most of the directly incident laser light or even the entire laser light.

It should be noted at this point that, of course, other known in the art basically jet traps can be used.

Within the beam trap 12 is present also a measuring device 14 for incident light, here a photodetector, is provided. The trade fair Device 14 receives measurement data relating to the incident light, which are evaluated by a control device 15 connected to the measuring device 14. The control device 15 determines the presence of a defect, in particular the elimination or damage of the radiation converter 6, by checking whether at least a certain amount of laser light, thus unconverted light, arrives on the measuring device 14. To assess this, on the one hand, the spectrum of the incident light can be considered, after it is shifted towards the wavelength of the laser diode 3 used. On the other hand, the intensity of the light can also be considered. Suitable threshold values are used, which, if they are exceeded or undershot, establish a defect in the sense of FIG. 6. If such a defect occurs, the control device 5 deactivates the laser light source 2.

It should be noted that such a measuring device 14, which supplies data to a control device 15, which are evaluated there, of course, in principle, also in the first embodiment of FIG. 1 and FIG. 2 or the second embodiment of FIG. 3 and FIG can be.

In the third exemplary embodiment according to FIGS. 5 and 6, too, the reflector 5 is shaped in such a way that aberrations resulting from the aperture are corrected.

FIG. 7 shows, as a detail sketch, a further variant of a jet trap which can be provided directly on the reflector 5. For this purpose, a coating 16 is provided in the impact area 8, which is basically reflective, but assumes the properties of a jet trap when a limit temperature is exceeded. In this case, the reflector 5 still acts as designed reflective in normal operation, so that aberrations are avoided, however, occurs in case of failure, a jet trap effect.

In a further embodiment, the coating 16 as a layer can also cover an opening of the reflector 5 and, in the event of an overshoot, ten of the limit temperature are destroyed, the actual beam trap is arranged as in the embodiment of Fig. 5 and Fig. 6 behind the coating.

Alternatively, by the way, as divergent element 9 a diverging coating of the reflector 5 is conceivable.

Finally, Fig. 8 shows a schematic diagram of a motor vehicle 17 according to the invention which has two lighting devices 1, 1 'and 1 "as front headlights, nevertheless it should be pointed out that other lighting devices of a motor vehicle according to the present invention can also be configured.

Claims

P A T E N T A N S P R E C H E

Lighting device (1, 1 ') for a motor vehicle (17), comprising a laser light source (2), a radiation converter (6) containing a fluorescent material, in particular phosphorus, and a reflector (5), laser light emitted by the laser light source (2) in the radiation converter (6) is converted and fanned out in broadband, in particular white secondary light compared to the laser light, which secondary light is deflected by the reflector (5) in an emission direction of the illumination device (1, 1 '),

characterized,

a protection means for reducing the light intensity of laser light emitted from the illumination device (1, 1 ') in the event of omission or damage of the radiation converter in an impact area (8) of the reflector (5) which is exposed to the laser light when the radiation converter (6) is omitted (6) is provided.

Lighting device according to claim 1,

characterized,

an exit surface of the laser light source (2) is connected directly to the radiation converter (6) and directed onto the reflector (5) and / or that the radiation converter (6) has a Lambert radiation characteristic.

Lighting device according to claim 1 or 2,

characterized,

the protective means is a diverging element (9) formed from the reflector (5) and / or applied to the reflector (5).

4. Lighting device according to claim 3,

characterized, the divergent element (9) has a convex or concave, in particular round shape, in the impact area (8) and / or is shaped as a function of the beam geometry of the laser light.

5. Lighting device according to claim 1 or 2,

characterized,

the protection means is a jet trap (12).

6. Lighting device according to claim 5,

characterized,

in that the jet trap (12) is an absorption body arranged behind the reflector (5) which has been broken through in the impact area (8).

7. Lighting device according to claim 6,

characterized,

in that the absorption body is at least part of a heat sink (13), in particular a black-colored aluminum heat sink (13) for the illumination device (1, 1 ').

8. Lighting device according to one of claims 5 to 7,

characterized,

in that the reflector (5) is provided in the impingement region with a coating (16) which reflects up to a limit temperature being exceeded.

9. Lighting device according to claim 8,

characterized,

if the limit temperature is exceeded, in particular in the case of the jet trap (12) arranged behind it, the coating (16) becomes permeable at least to the laser light and / or acts as a beam trap (12) itself.

10. Lighting device according to one of the preceding claims, characterized in that in that the reflector (5) is shaped to correct aberrations caused by the protective means.

11. Lighting device according to one of the preceding claims, characterized in that

a measuring device (14), in particular a photodetector, is arranged in the impingement region (8) and / or as part of the protective device, a control device (15) controlling the operation of the laser light source (2) for evaluating the measurement data of the measuring device (14) and for deactivating the laser light source (2) upon detection of an amount of laser light which in particular exceeds a threshold value.

12. Lighting device according to claim 11,

characterized,

in that the control device (15) is designed to determine a spectrum and / or an intensity of the light striking the measuring device (14).

13. motor vehicle (17) comprising at least one illumination device (1, 1 ') according to one of the preceding claims.