EP3056801B1 - Lighting device for a headlight of a motor vehicle and method for operation of a lighting device - Google Patents

Description

The present invention relates to a lighting device for a headlamp of a motor vehicle, comprising a light source for emitting a primary radiation, which has a first wavelength distribution, with a converter element for converting the primary radiation into a secondary radiation, which has a second wavelength distribution, and with a deflection, 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. By way of example, this light source can comprise at least one laser or laser diodes, with which light in the blue wavelength range is emitted as the primary radiation. 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 harmless the laser radiation or primary radiation in their point of impact. Thus, the primary radiation can be completely absorbed in 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 DE 10 2012 109 088 A1 a fiber optic conversion module as part of a lighting device. The conversion module comprises an optical fiber, which is provided at a light entry end for coupling to an excitation light source with a plug which is arranged at a light exit end for emitting excitation light at a light spot. Furthermore, a converter is provided which serves to compress short-wavelength excitation light into medium-long-wave useful light. Furthermore, the conversion module has a light emission window for useful light, which is provided with a light trap for excitation light reflected at the converter.

In addition, the describes DE 10 2012 112 994 A1 a headlamp device having a laser light source for emission of collimated primary radiation, a conversion element for at least partially converting the collimated primary radiation into secondary radiation and a deflection device which is provided for directing the collimated primary radiation coming from the laser light source during operation to the conversion element and as a scanning beam over partial regions to lead the conversion element.

In addition, the describes DE 10 2012 220 472 A1 a lighting device for a motor vehicle, which has a laser light source for the emission of a primary light beam. Furthermore, the illumination device comprises a photoluminescent element, which is arranged such that the primary light beam which can be emitted by the laser light impinges on the photoluminescent element, and which is embodied such that a secondary light distribution can be emitted by the incident primary light beam by utilizing photoluminescence. Further, a Abstrahlhemmungsmittel be arranged in the beam path between the photoluminescent element and a Abstrahloptikeinrichtung. This radiation-inhibiting element can have a deflecting prism or a facet element which is embodied such that a light beam incident on the deflecting prism or facet element is deflected in such a way that it does not contribute to the emission light distribution. In particular, a design is conceivable such that an incident light beam is deflected in an absorber or a light trap, preferably in the interior of the lighting device.

In addition, the generic describes EP 2 461 092 A2 a vehicular lamp comprising a laser diode and a phosphor for converting the blue light of the laser diode into white light. Further, the vehicle lamp has a reflector with a reflection surface, which reflects the white light. The reflective surface may have an optical structure that disperses the blue light, reflects the blue light back to the phosphor, or lets the blue light pass through the reflective surface to an area behind it.
It is an object of the present invention to provide a lighting device for a headlight 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. Moreover, the deflection device has a refraction element which is designed to output the primary radiation impinging on the refraction element with a first angle of reflection and to output the secondary radiation impinging on the refraction element at a second angle of departure different from the angle of emergence.

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 can be converted into a secondary radiation, which preferably has a higher wavelength than the primary radiation. 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.

The deflection device furthermore comprises at least one refraction element which is designed to output the primary radiation impinging on the refraction element at a first failure angle in the event of a failure of the converter element. Furthermore, the refraction element is designed to output the secondary radiation impinging on the refraction element at a second failure angle different from the first departure angle. In other words, instead of a radiation trap now at least one refractive element is used, with which both the primary radiation and the secondary radiation can be deflected. In this case, the primary radiation usually hits the at least one refraction element only in the case of a failure or 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 with the converter element, a conversion of the primary radiation into the secondary radiation no longer occurs. In the present case, the primary radiation and the secondary radiation are output at different failure angles with the at least one refractive element. Thus, it can be prevented, in particular, that the primary radiation, which is normally dangerous for living beings and is present in particular as a concentrated laser beam, can endanger living beings. 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. According to the invention, the refractive element has an optical body which is designed to break the primary radiation coupled into the optical body at a first angle of incidence and the secondary radiation coupled into the optical body at a second angle of incidence. The optical body of the refractive element may be made of a glass or a plastic, for example. With the optical body, both the primary radiation and the secondary radiation can be refracted. In this case, the primary radiation, which represents, for example, light in the blue wavelength range, refracted differently than the secondary radiation, which represents, for example, light in the yellow or white wavelength range. Thus can be achieved in a simple manner that the primary radiation and the secondary radiation are harmful broken or distracted.
In addition, the refractive element has a reflector layer for reflecting the primary radiation and / or secondary radiation coupled into the optical body. The primary radiation and the secondary radiation impinging on the refracting element are refracted by the optical body at a respective incident angle. Subsequently, the primary radiation and the secondary radiation are reflected by the reflector layer and coupled out of the optical body at different angles of reflection. Thus, it can be achieved in a simple manner that the primary radiation and the secondary radiation are reflected at different angles of reflection of the refractive element.

Preferably, the illumination device has an absorber element for absorbing the primary radiation, which is arranged such that the primary radiation output by the refraction element strikes the absorber element. In other words, the primary radiation at a Failure of the converter element so deflected with the at least one refractive element that this impinges on an absorber element. With the absorber element then the dangerous primary radiation can be absorbed. This can prevent that the dangerous primary radiation or the blue laser light from the illumination device comes to the outside and thus endanger living things. Thus, the lighting device can be operated safely.

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

In a further embodiment, the refraction element has a shape of a prism. The refractive element can be produced, for example, by a microtechnical production method. The refractive element may have a base in the form of a polygon, which is arranged parallel to the deflecting device. The dimensions of this base may include expansion in the range between 0.1 and 1 millimeter, especially 0.5 millimeter.

Preferably, the deflection device has a plurality of refractive elements, which are arranged side by side. In other words, the individual refractive elements are arranged so that they have no gap to each other. Thus, it can be reliably achieved that the primary radiation which strikes the respective refractive elements is reliably deflected. Alternatively, it may be provided that the respective refractive elements are arranged at a distance from one another, wherein an absorber element for absorbing the primary radiation is arranged in the intermediate space between two adjacent refraction elements. 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, by means of a refraction element of the deflection device, the primary radiation impinging on the refraction element in the event of a failure of the converter element is output at a first failure angle and the secondary radiation impinging on the refraction element is output at a second failure angle different from the first departure angle. Furthermore, by means of an optical body of the refractive element, the primary radiation coupled into the optical body is refracted at a first angle of incidence and the secondary radiation coupled into the optical body is refracted at a second angle of incidence. Furthermore, the primary radiation and / or secondary radiation coupled into the optical body is reflected by means of a reflector layer of the refractive 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 above in the description mentioned features and feature combinations, as well as the features mentioned below in the figure description and / or alone in the figures and feature combinations can be used not only in the 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

ein Brechungselement der Beleuchtungsvorrichtung in einer geschnittenen Seitenansicht; und

Fig. 4

das Brechungselement gemäß Fig. 3 in einer 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

a refractive element of the lighting device in a sectional side view; and

Fig. 4

the refraction element according to Fig. 3 in a perspective view.

In the figures, identical and 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. In particular, with the light source 4 light in the blue wavelength range to be sent out. The primary radiation 5 may, for example, have a wavelength of 450 nanometers. The primary radiation 5 is optionally conducted by the light source via an integrator 6 to a deflection 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. The secondary radiation 9 can have a wavelength in the range between 500 and 780 nanometers. In particular, the secondary radiation is light in the white or yellow 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. In the present case, this is represented by the individual light beams (dashed lines). The secondary radiation 9 strikes a deflection device 10. The deflection device 10 has, on a side 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 deflection device 10 comprises a refraction element 13, which is shown here only schematically. The deflection device 10 can also have a plurality of refraction elements 13. With the at least one refractive element 13, both the primary radiation 5 and the secondary radiation 9 can be reflected or refracted.

In case of failure or defect of the converter element 8, the primary radiation 5 is not converted by the converter element 8 into the secondary radiation 9. In this case, the primary radiation 5 is deflected or refracted by the at least one refraction element 13 such that it strikes an absorber element 15. From the absorber element 15, the primary radiation 4 can be absorbed. In this way it can be prevented that the primary radiation 4 or the dangerous blue laser light emerges from the lighting device 3 and thus can lead to damage to living beings. In contrast, the converted secondary radiation 9 is directed by the at least one refractive element 13 such that it penetrates out of the illumination device 3 to the outside and thus provides a light distribution for the headlight 2.

Fig. 3 shows a refractive element 13 in a sectional side view. The refractive element 13 has an optical body 16, which may be made of a glass or a plastic, for example. It can be seen that the primary radiation 5 and the secondary radiation 9 impinge upon the optical body 16 at an angle of incidence α. The optical body 16 breaks the primary radiation 5 at a first angle of incidence β1 and the secondary radiation 9 at a second angle of incidence β2. Both the primary radiation 5 and the secondary radiation 9 are reflected by a reflector layer 17. The reflector layer 17 may be formed, for example, by the reflector element 12. Of the reflector layer 17, the primary radiation 5 and the secondary radiation 9 are reflected at the angles β1 and β2. Upon the exit of the primary radiation 5 from the optical body 16, the primary radiation 5 is refracted at a first angle of reflection γ1. The secondary radiation 9 is refracted at the exit from the optical body 16 at a second angle of reflection γ2. If the reflector layer 17 is arranged in perpendicular to a beam path of the primary radiation 5 and the secondary radiation 9, the first angle of emergence γ1 and the second angle of emergence γ2 are equal. If the reflector layer 17 is not arranged perpendicular to the beam path of the primary radiation 5 and the secondary radiation 9, the first angle of deflection γ1 and the second angle of departure γ2 differ. The different angles of incidence β1, β2 and the different angles of incidence γ1 and γ2 arise as a result of the different wavelengths of the primary radiation 5 and the secondary radiation 9.

Fig. 4 shows the refracting element 13 in a perspective view. It can be seen here that the refraction element 13 has the shape of a prism. A base of the refracting element 13 has the shape of a quadrilateral. The spatial dimensions of the body can be in the range between 0.1 and 1 millimeter. Due to the prismatic configuration of the refractive element 13 can be made possible in a particularly simple manner that several of the refractive elements 13 can be arranged side by side in a plurality of rows and columns.

Claims (8)

1. Lighting device (3) for a headlamp (2) of a motor vehicle (1), with a light source (4) for emitting a primary beam (5) which comprises a first wavelength distribution, with a converter element (8) for converting the primary beam (5) into a secondary beam (9) which comprises a second wavelength distribution and with a deflection device (10) which comprises a reflector element (12) for reflecting the secondary beam (9), wherein the deflection device (10) comprises a refractive element (13) which is designed to emit the primary beam (5) impinging upon the refractive element (13) at a first angle of reflection (γ1) in the case of a fault of the converter element (8) and to emit the secondary beam (9) impinging upon the refractive element (13) at a second angle of reflection (γ2) different from the first angle of reflection (γ1),
   characterised in that
   the refractive element (13) comprises an optical body (16) which is designed to refract the primary beam (5) coupled into the optical body (16) at a first angle of incidence (β1) and to refract the secondary beam (9) coupled into the optical body (16) at a second angle of incidence (β2) and comprises a reflector layer (17) to reflect the primary beam (5) and/or secondary beam (9) coupled into the optical body (16).
2. Lighting device (3) according to claim 1,
   characterised in that
   the lighting device (3) comprises an absorber element (15) for absorbing the primary beam (5) which is arranged such that the primary beam (5) emitted by the refractive element (13) impinges upon the absorber element (15).
3. Lighting device (3) according to claim 1 or 2,
   characterised in that
   the primary beam (5) impinging upon the converter element (8) runs along an imaginary line wherein the refractive element (13) is arranged in a region of an intersection point of the imaginary line and the deflection device (10).
4. Lighting device (3) according to any one of the preceding claims,
   characterised in that
   the refractive element (13) has a prism shape.
5. Lighting device (3) according to any one of the preceding claims,
   characterised in that
   the deflection device (10) comprises a plurality of refractive elements (13) which are arranged next to each other.
6. Headlamp (2) for a motor vehicle (1) with a lighting device (3) according to any one of the preceding claims.
7. Motor vehicle (1) with at least one headlamp (2) according to claim 6.
8. Method for operating a lighting device (3) for a headlamp (2) of a motor vehicle (1), in which a primary beam (5) is emitted by means of a light source (4), said primary beam comprises a first wavelength distribution, the primary beam (5) is converted by means of a converter element (8) into a secondary beam (9) which comprises a second wavelength distribution and the secondary beam (9) is reflected by means of a reflector element (12) of a deflection device (10),
   wherein the primary beam (5) impinging upon the refractive element (13) in the case of a fault of the converter element (8) is emitted by means of a refractive element (13) of the deflection device (10) at a first angle of reflection (γ1) and the secondary beam (9) impinging upon the refractive element (13) is emitted at a second angle of reflection (γ2) different from the first angle of reflection (γ1),
   characterised in that
   the primary beam (5) coupled into the optical body (16) is refracted by means of an optical body (16) of the refractive element (13) at a first angle of incidence (β1) and the secondary beam (9) coupled into the optical body (16) is refracted at a second angle of incidence (β2) and the primary beam (5) and/or secondary beam (9) coupled into the optical body (16) is reflected by means of a reflector layer (17) of the refractive element (13).

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