EP3056802A1 - Lighting device for a headlight of a motor vehicle and method for operation of a lighting device - Google Patents

Abstract

The invention relates to a lighting device (3) for a headlight (2) of a motor vehicle (1), having a light source (4) for emitting a primary radiation (5) having a first wavelength distribution, with a converter element (8) for converting the primary radiation (5) into a secondary radiation (9), which has a second wavelength distribution, and with a deflection device (10) which has a reflector element (12) for reflecting the secondary radiation (9), wherein the deflection device (10) comprises a microlens array (13) with a plurality of microlenses (16), wherein at least one of the microlenses (16) is adapted to scatter the primary radiation (5) in the event of failure of the converter element (8).

Description

The present invention relates to a lighting device for a headlamp of a motor vehicle, having a light source for emitting a primary radiation having a first wavelength distribution, with a converter element for converting the primary radiation into a secondary radiation having a second wavelength distribution, and with a deflector, which Reflector element for reflecting the secondary radiation. The invention also relates to a headlamp with such a lighting device. Furthermore, the present invention relates to a motor vehicle with such a headlight. Finally, the present invention relates to a method for operating a lighting device for a headlight of a motor vehicle.

The interest is directed in the present case in particular to lighting devices for headlights of a motor vehicle. Lighting devices are known from the prior art, which have a light source for emitting a primary radiation. This light source may include, for example, a laser or laser diodes, with which as the primary radiation light in the blue wavelength range is emitted. This primary radiation can be converted by means of a converter element into a secondary radiation which has a second wavelength distribution. As the secondary radiation, for example, white light can be provided. In addition, such lighting devices may have a reflector element or a reflector for reflecting the secondary radiation. Thus, a corresponding light distribution can be provided in front of the motor vehicle.

Since in a defect or failure of the converter element, the primary radiation of the laser can usually pose a threat to living beings, different security concepts have been developed. One Safety concept provides, for example, a so-called radiation trap, which is integrated in the deflection device or the reflector element. In the case of a defect of the converter element, it is no longer the converted, diffuse secondary radiation that strikes the reflector element, but the short-wave primary radiation of the laser. Since this primary radiation is usually strongly bundled, the radiation trap can be positioned so that it makes the laser radiation or primary radiation harmless in its point of impact. Thus, the primary radiation can be completely absorbed in the event of a defect of the converter element with the radiation trap.

In normal operation of the lighting device, however, there is the disadvantage that the secondary radiation is not reflected in the region of the radiation trap and thus does not contribute to the light distribution of the headlight. This can permanently result in a loss of radiation intensity, which is provided by the headlight.

This describes the AT 512 588 A1 a light source module for a vehicle headlamp, wherein the light source module has at least one laser light source and at least one illuminating element which can be excited by illumination with laser light for the purpose of emitting visible light. In this case, the laser light source and the luminous element are arranged spaced apart on a carrier element. The support member may be at least partially made of a transparent material. Furthermore, the carrier element may have irregularities or microstructures executed on its surface with which the irradiated laser light or the light originating from the luminous element can be deflected and thereby made visible.

Furthermore, the describes DE 10 2011 085 378 A1 a lighting device for a motor vehicle. The illumination device comprises one or more illumination units, wherein a respective illumination unit generates a punctiform light source during operation by means of laser light. Furthermore, an optical device is provided, which is configured and arranged in relation to the illumination unit such that a predetermined light distribution is generated from the light of the point-like light source after passing through the optical device. The illumination unit may, for example, comprise a laser diode with which light in the blue wavelength range can be emitted.

In addition, the describes DE 10 2012 005 660 A1 an illumination device for generating light. The illumination device comprises an excitation light source for emitting blue or ultraviolet excitation light, a conversion medium for converting the excitation light into more boring light such that light reflected from the conversion medium appears white. Furthermore, the illumination device can have a mirror or a mirrored surface through which a part of the secondary radiation can be directed back to the conversion medium. Preferably, this mirror is arranged such that a part of the reflected blue radiation can fall back to a luminous spot of the conversion medium in order to be converted there into longer-wavelength, yellow light.

It is an object of the present invention to provide a lighting device for a headlamp of the type mentioned, which can be operated safely and efficiently.

This object is achieved by a lighting device, by a headlight, by a motor vehicle and by a method with the features according to the respective independent claims. Advantageous developments of the invention are the subject of the dependent claims.

An illumination device according to the invention for a headlight of a motor vehicle comprises a light source for emitting a primary radiation which has a first wavelength distribution. Furthermore, the lighting device comprises a converter element for converting the primary radiation into a secondary radiation which has a second wavelength distribution. In addition, the lighting device comprises a deflection device, which has a reflector element for reflecting the secondary radiation. In addition, the deflection device has a microlens array with a plurality of microlenses, wherein at least one of the microlenses is designed to scatter the primary radiation in the event of failure of the converter element.

The lighting device can be used in a headlight of a motor vehicle. The light source of the lighting device may, for example, comprise at least one laser or one laser diode. With the light source, the primary radiation can be emitted in the form of light in the blue wavelength range. With the converter element, the Primary radiation in a secondary radiation, which preferably has a higher wavelength than the primary radiation, are converted. The converter element may be a fluorescent converter element. The converter element may for example be formed at least partially from yttrium-aluminum-garnet doped with cerium. The converter element may also be referred to by the term "phosphor". The secondary radiation strikes a deflection device, which has a reflector element. This reflector element can be formed for example by a corresponding reflective coating. With the reflector element, the secondary radiation can be reflected, so that a light distribution can be provided.

Furthermore, the deflection device comprises a microlens array which has a plurality of microlenses. The microlenses can have dimensions in the range of micrometers or millimeters. The microlenses can be manufactured by a microtechnical manufacturing process. The microlenses may be arranged in the microlens array in a line-shaped, column-shaped or matrix-like manner. The microlenses are now used to scatter the primary radiation. In other words, instead of a radiation trap, a microlens array is now used with which the primary radiation can be dispersed in the event of a defect of the converter element. A defect of the converter element is present, for example, if the converter element has an impurity, a breakage point or the like. The failure of the converter element describes in particular the state in which the converter element does not convert the primary radiation into the secondary radiation. Thus, the normally dangerous for living beings primary radiation, which is present in particular as a concentrated laser beam, can be expanded or diverged. By scattering the primary radiation, the radiation intensity can be reduced. Thus, in the event of an error, it can be achieved that the primary radiation does not pose a threat to living beings and in particular to their eyes.

Preferably, the primary radiation impinging on the converter element runs along an imaginary line, the microlens array being arranged in a region of an intersection of the imaginary line and the deflection device. The microlens array is applied, for example, on the surface of the deflection device facing the converter element. The microlens array can be applied in such a way that the primary radiation which passes through the converter element without conversion strikes the microlens array meets. In this case, the positioning and / or the spatial extent of the microlens array can be determined such that a deflection of the primary radiation at a predetermined angle by the defective converter element is taken into account. Thus, the primary radiation can be reliably dissipated at a defect of the converter element.

In one embodiment, the respective microlenses are at least partially reflective. The respective microlenses may have a reflective surface at least in some areas. The microlenses may, for example, have a coating of a reflective material, in particular a metal. Thus, it can be reliably achieved that the primary radiation is dissipated in the event of a defect of the converter element.

In a further embodiment, the microlenses are arranged relative to one another such that in each case a gap is arranged between two adjacent microlenses, wherein an absorber element for absorbing the primary radiation is arranged in the intermediate space. In other words, the microlenses in the microlens array are arranged at a distance from one another. Between the microlenses is an absorber element, with which the primary radiation can be absorbed. Thus, the part of the primary radiation which does not directly strike the microlenses and is scattered by them, can be absorbed accordingly. Thus, a threat to living beings can be prevented by the primary radiation.

Furthermore, it is advantageous if the microlenses are each concave on a side facing the converter element. The microlenses can be designed as scattering lenses, with which the primary radiation, which is present in particular as a concentrated laser beam, can be widened. Thus, the radiation energy of the primary radiation can be reduced. In particular, the radiation energy can be reduced in a predetermined area in front of the headlight, for example at a distance of 2 meters in front of the headlight. Thus, existing safety standards can be reliably met.

In one embodiment, the microlenses each have a radius in a range between 0.1 millimeter and 1 millimeter. In particular, the microlenses each have a radius of 0.5 millimeters. The complete Microlens array, for example, have a diameter in the range between 10 and 20 millimeters. Thus, the microlens array has a plurality of individual microlenses. It can thus be achieved that the concentrated primary radiation which impinges on the respective microlenses can be reliably dispersed.

An inventive headlight for a motor vehicle comprises a lighting device according to the invention. The headlight can be designed in particular as a headlight.

A motor vehicle according to the invention comprises at least one headlight according to the invention. Each headlight of the motor vehicle preferably comprises a lighting device according to the invention. With the headlamps, for example, a low beam, a high beam, a daytime running light, a city light, a highway light or the like can be provided. The motor vehicle is designed in particular as a passenger car.

An inventive method is used to operate a lighting device for a motor vehicle. In this case, a primary radiation having a first wavelength distribution is emitted by means of a light source. The primary radiation is converted by means of a converter element into a secondary radiation having a second wavelength distribution. Furthermore, the secondary radiation is reflected by means of a reflector element of a deflection device. In addition, the deflection device has a microlens array with a plurality of microlenses, wherein the primary radiation is scattered by means of at least one of the microlenses in the event of failure of the converter element.

The preferred embodiments presented with reference to the lighting device according to the invention and their advantages apply correspondingly to the headlight according to the invention, the motor vehicle according to the invention and the method according to the invention.

Further features of the invention will become apparent from the claims, the figures and the description of the figures. The features and feature combinations mentioned above in the description, as well as the features and feature combinations mentioned below in the description of the figures and / or shown alone in the figures, are not only given in the respectively indicated Combination, but also in other combinations or alone, without departing from the scope of the invention.

The invention will now be described with reference to preferred embodiments and with reference to the accompanying drawings.

Fig. 1

in schematischer Darstellung ein Kraftfahrzeug gemäß einer Ausführungsform der vorliegenden Erfindung, welches zwei Scheinwerfer aufweist;

Fig. 2

eine Beleuchtungsvorrichtung für die Scheinwerfer in einer geschnittenen Seitenansicht;

Fig. 3

die Beleuchtungsvorrichtung gemäß Fig. 2 in einer Perspektivansicht, wobei ein Konverterelement der Beleuchtungsvorrichtung einen Defekt aufweist; und

Fig. 4

die Beleuchtungsvorrichtung gemäß Fig. 3 in einer weiteren Perspektivansicht.

Showing:

Fig. 1

a schematic representation of a motor vehicle according to an embodiment of the present invention, which has two headlights;

Fig. 2

a lighting device for the headlights in a sectional side view;

Fig. 3

the lighting device according to Fig. 2 in a perspective view, wherein a converter element of the lighting device has a defect; and

Fig. 4

the lighting device according to Fig. 3 in another perspective view.

In the figures, identical or functionally identical elements are provided with the same reference numerals.

Fig. 1 shows a motor vehicle 1 according to an embodiment of the present invention in a plan view. The motor vehicle 1 is formed in the present embodiment as a passenger car. The motor vehicle 1 comprises two headlights 2, which are designed as front headlights. The headlights 2 each comprise a lighting device 3.

Fig. 2 shows an embodiment of the lighting device 3 in a sectional side view. The illumination device 3 comprises a light source 4 which comprises, for example, at least one laser or one laser diode. With the light source 4, a primary radiation 5 can be emitted with a first wavelength distribution. In particular, 4 light in the blue wavelength range can be emitted with the light source. The primary radiation 5 is optionally provided by the light source 4 via an integrator 6 directed to a deflecting mirror 7. The deflecting mirror 7 deflects the primary radiation 5 to a converter element 8. The converter element 8 serves to convert the primary radiation 5 into a secondary radiation 9. The secondary radiation 9 has a second wavelength distribution. In particular, the secondary radiation 9 is light in the white wavelength range. In the present exemplary embodiment, the light source 4, the integrator 6, the deflection mirror 7 and the converter element 8 are arranged in a housing 14.

The secondary radiation 9 is also scattered by the converter element 8. This is shown here by the individual light beams. The secondary radiation 9 strikes a deflection device 10. The deflection device 10 has, on a side 11 facing the converter element 8, a reflector element 12 which serves to deflect the secondary radiation 9. The reflector element 12 can be provided for example by a metallic coating. In addition, the deflecting device 10 comprises a microlens array 13 shown here only schematically. The microlens array 13 further serves to reflect or deflect the secondary radiation 9, wherein in the present case an ideal deflection or reflection of the secondary radiation 9 through the microlens array 13 is shown. In addition, the light rays of the secondary radiation 9 impinging on the microlens array 13 are scattered by the microlens array 13.

Fig. 3 shows the lighting device 3 in a perspective view. In the present case, the converter element 8 has a defect. As a result, the primary radiation 5 is not converted by the converter element 8 into the secondary radiation 9. Thus, the primary radiation 5 strikes the microlens array 13 as a concentrated laser beam directly. The microlens array 13 is a plurality of microlenses 16. The arrangement of the microlenses 16 in the microlens array is particularly in Fig. 4 which shows a further perspective view of the lighting device 3. The microlenses 16 are arranged in a matrix-like manner in rows and columns in the microlens array 13. The individual microlenses 16 may, for example, have a radius of 0.5 millimeters. The microlenses 16 may be made of a glass or of a plastic. In addition, the microlenses 16 may have a reflective coating. With the respective microlenses 16, the primary radiation 5, which strikes the microlens array 13, can be scattered. This is illustrated by the light beam 15 in the present case. Thus, the dangerous primary radiation 5 or laser radiation can be scattered. Thus, the intensity of the primary radiation can be reduced and thus endangerment of living beings can be prevented.

Claims (9)

Lighting device (3) for a headlight (2) of a motor vehicle (1), comprising a light source (4) for emitting a primary radiation (5) having a first wavelength distribution, with a converter element (8) for converting the primary radiation (5) into a secondary radiation (9) which has a second wavelength distribution, and a deflection device (10) which has a reflector element (12) for reflecting the secondary radiation (9),
characterized in that
the deflection device (10) has a microlens array (13) with a plurality of microlenses (16), wherein at least one of the microlenses (16) is designed to scatter the primary radiation (5) in the event of failure of the converter element (8). Lighting device (3) according to claim 1,
characterized in that
the primary radiation (5) impinging on the converter element (8) runs along an imaginary line, wherein the microlens array (13) is arranged in a region of an intersection of the imaginary line and the deflection device (10). Lighting device (3) according to claim 1 or 2,
characterized in that
the respective microlenses (16) are designed to be reflective at least in regions. Lighting device (3) according to one of the preceding claims,
characterized in that
the microlenses (16) are arranged relative to one another in such a way that in each case a gap is arranged between two adjacent microlenses (16), wherein an absorber element for absorbing the primary radiation (5) is arranged in the intermediate space. Lighting device (3) according to one of the preceding claims,
characterized in that
the microlenses (16) each at one of the converter element (8) facing Side are concave. Lighting device (3) according to one of the preceding claims,
characterized in that
the microlenses (16) each have a radius in a range between 0.1 mm and 1 mm. Headlight (2) for a motor vehicle (1) with a lighting device (3) according to one of the preceding claims. Motor vehicle (1) with at least one headlight (2) according to claim 7. Method for operating a lighting device (3) for a motor vehicle (1), in which by means of a light source (4) a primary radiation (5) having a first wavelength distribution is emitted, by means of a converter element (8) the primary radiation (5) in a secondary radiation (9), which has a second wavelength distribution, is converted and the secondary radiation (9) is reflected by means of a reflector element (12) of a deflection device (10),
characterized in that
the deflection device (10) has a microlens array (13) with a plurality of microlenses (16), wherein the primary radiation (5) is scattered by means of at least one of the microlenses (16) in the event of failure of the converter element (8).

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