EP3371509B1 - Light module - Google Patents

Description

The invention relates to a light module for a motor vehicle headlight according to the preamble of claim 1.

In the field of motor vehicle lighting, especially in motor vehicle headlights, the use of powerful light sources with the highest possible luminance is desirable. As a result, bright lighting devices can be implemented with a small installation space. The light distribution emitted must have certain properties that are usually prescribed by law. White light is generally desired for the front lights of a motor vehicle.

With laser light sources, for example semiconductor laser diodes, high radiation outputs can be achieved. However, in principle, laser light sources usually emit almost monochromatic, coherent and strongly collimated laser light, which in this form cannot be used directly as the emitted light of the lighting device.

Laser light sources are therefore mostly used in vehicle lighting with a wavelength converter. The monochromatic, coherent laser light is converted into diffuse and largely incoherent white light. From the DE 10 2012 220 481 A1 and the US 8,400,011 B2 For example, light modules with a laser light source and a photoluminescence converter are known. The photoluminescence converter has a photoluminescent dye that emits light with different wavelengths when excited to photoluminescence by means of laser light. The secondary light distribution achieved in this way includes the converted light and possibly also scattered portions of the incident light, and can therefore be used for the purposes of vehicle lighting.

The wavelength converter is of relevance to safety, since unconverted laser light is potentially dangerous with the typically high radiation power of laser light sources.

If the wavelength converter is damaged, there may be a risk of strongly collimated laser beams emerging from the lighting device. In order to detect damage to the converter and to switch off the laser if necessary, the DE 10 2012 220 481 A1 and the US 8,400,011 B2 a detection device for detecting the radiation intensity is provided. Disadvantages of these safety devices are that they require additional optical and electronic components in order to detect the radiation intensity. In addition, a control device is required in order to switch off the laser light source if the detected intensity exceeds a safety limit value.

From the DE 10 2012 220 472 A1 a safety device is known in which a screen is arranged on an emitting device or in the beam path between the photoluminescent element and the emitting optics. This diaphragm must be precisely adjusted in relation to the photoluminescent element and the laser light source. In addition, it must be structurally ensured that the diaphragm does not inadvertently change its position.

Out EP 2 781 823 A2 a light module for a motor vehicle headlight is known with a laser light source, a wavelength converter, a radiation optics device and a support component for holding the wavelength converter. However, a light guide is provided by means of which the laser light is coupled directly into the wavelength converter. Therefore, a primary light bundle in the actual sense, with respect to which the wavelength converter is arranged, is not provided.

Out US 2012/0292636 A1 a light module with a laser light source, a wavelength converter and an optical emission device is also known, embodiments with and without a light guide being disclosed. In two figures, the wavelength converter is followed by a UV mirror which is intended to reflect non-wavelength-converted light back onto the wavelength converter. A design or alignment of the mirror in relation to a primary light beam is not apparent.

Another light module with a laser light source, a wavelength converter and a radiation optical device is in the WO 2015/154983 A1 described. Here, a wavelength converter is provided with a hole through which a direct light component of the primary light beam is radiated.

The present invention is based on the object of avoiding the risk of laser light emerging from a motor vehicle lighting device in a reliable and robust manner.

This object is achieved by a light module with the features of claim 1. In the present context, a light module is understood to be the actual light-emitting structural unit of a motor vehicle lighting device. However, the object is also achieved by a motor vehicle lighting device with the features of the light module described.

The light module comprises a laser light source for emitting a primary light bundle in a primary solid angle area around a primary emission direction starting from the laser light source. Furthermore, a wavelength converter is provided, which is arranged in such a way that the primary light bundle that can be emitted with the laser light source strikes the wavelength converter. The wavelength converter is designed in such a way that a secondary light distribution with in particular polychromatic or white light can be emitted by the incident primary light bundle, in that at least a portion of the primary light bundle is converted from laser light, e.g. using photoluminescence, into light with a different wavelength.

The secondary light distribution is emitted in particular in a secondary solid angle range. The emission of the secondary light distribution from the wavelength converter occurs in particular diffuse and largely undirected. As a rule, the wavelength converter has the emission characteristics of a Lambert radiator after excitation by the primary light beam. In this respect, the secondary solid angle range is significantly larger than the primary solid angle range.

The light module further comprises an emission optics device (e.g. projection lens, deflecting reflector) for converting the secondary light distribution into an emission light distribution of the light module. The emitted light distribution is concentrated e.g. around a main emission direction which, when installed in a motor vehicle, points e.g. in the direction of travel.

The light module also includes a support component for holding the wavelength converter. The carrier component has a safety bracket which, viewed from the wavelength converter, covers the primary solid angle area around the primary emission direction.

In trouble-free normal operation, the following beam path results in the light module: Starting from the laser light source acting as the primary light source, a primary light bundle (laser light) runs essentially in the primary solid angle range around the primary emission direction. The primary light beam emitted by the laser light source normally hits the wavelength converter. The wavelength converter converts the coherent primary light bundle into a usable secondary light distribution from diffuse, largely incoherent white light. The light beams of the secondary light distribution impinge on the emitting optics device and are directed by this in the, preferably essentially around one main emission direction of the light module concentrated, radiated light distribution reshaped (ie deflected and / or reflected and / or projected). For the radiation optics device, the wavelength converter therefore acts as the actual light source, the secondary light distribution of which essentially no longer exhibits the hazard potential of laser light. In normal operation, the wavelength converter thus ensures that the potentially dangerous laser light does not reach the emitted light distribution directly.

If the wavelength converter is not arranged in the beam path of the primary light bundle (e.g. broken) due to mechanical influences, an accident or a construction fault, the laser light of the primary light bundle is suppressed by the safety bar on the carrier component of the wavelength converter. The safety bar is thus arranged on the carrier component in such a way that it is prevented that, in spite of the no longer effective wavelength converter, potentially dangerous laser light emerges from the light module. The safety bar also ensures that the wavelength converter is arranged on the carrier component so that it is protected from mechanical influences.

When using laser light sources, because of the typically strongly collimated light bundles with a small beam diameter, precise alignment of the laser light source on the wavelength converter and a reliable and safe arrangement of the wavelength converter must be ensured. This can be ensured with the carrier component for holding the wavelength converter and, if necessary, its method of fastening in the light module.

By arranging the safety bar on the carrier component of the wavelength converter, the safety bar is also in a robust, safe and precisely aligned position with the laser light source. In the embodiment according to the invention, each laser beam can thus be terminated by the safety bracket in the interior of the light module. In the event of a fault, a hazard from emitted laser beams is avoided in a way that is easy to implement. This protective device has a high level of functional reliability, since in particular moving mechanical components or electronic controls are not required.

The radiation optics device can be designed as a reflector, e.g. a parabolic reflector, or as a reflector arrangement. It is also possible for the radiation optics device to be designed as a projection device, e.g. comprising a projection lens. The radiation optics device can also consist of several optical elements, e.g. primary optics and secondary optics.

In normal, trouble-free operation, the influence of the safety bar on the light beam distribution is negligibly small. This is due to the fact that the size of the safety bar is preferably such that the light is only blocked in the event that it hits the safety bar directly (without a wavelength converter). With typical laser light sources, the half-value angle of the laser light can be approximately 2 ° -8 °. The safety bar has, for example, a longitudinal extension of 10mm to 20mm and a transverse extension of 1mm to 8mm and, in the case mentioned, can for example block 90% of the laser beam. If the wavelength converter is effective, the Radiated light distribution essentially fed by the secondary light distribution emitted by the wavelength converter. The largely incoherent white light of the secondary light distribution is less collimated and more diffuse. The power of the secondary light distribution is therefore distributed more homogeneously in space in the secondary spatial angle range. The secondary solid angle range is significantly larger than the primary solid angle range. A suppression of light beams by the safety bar in the comparatively small primary solid angle range around the primary emission direction therefore does not lead to a noticeable loss of power or interference with the emission of light distribution during normal operation. In order to minimize power losses, the safety bar is in particular not designed to be larger than necessary to block the primary beam. The safety bar is in particular dimensioned such that only light is blocked which strikes the safety bar running around the primary emission direction in the primary solid angle range.

The safety bracket is preferably firmly connected to the carrier component, in particular connected in one piece. As a result, the safety bar is mechanically robust and integrated into the carrier component with a fixed adjustment. In particular, this ensures that the safety bar is precisely aligned relative to the wavelength converter.

The safety bracket is preferably arranged in the beam path of the primary light bundle between the wavelength converter and the radiation optics device. As a result, the primary light bundle is suppressed by the safety bar before it hits the emitting optics device and prevents potentially dangerous laser light from the emitting optics device in the direction of the Beam light distribution is deflected. In particular, the safety bar protrudes over a mounting plane of the wavelength converter in which the wavelength converter is arranged.

In a preferred embodiment, the safety bar extends in its further course at a distance from the mounting plane and extends along the mounting plane, in particular essentially parallel to the mounting plane. The distance between the section of the safety bar running along the mounting plane and the mounting plane can be approx. 1-10 mm, for example. It is conceivable that, starting from the mounting plane, the safety bar initially has an inclined course. After the inclined course, the safety bar can merge into a section with a parallel course to the holding plane. It is also conceivable that the safety bar has an angled course along its extension. In particular, the safety bar is designed like a finger and extends bent over the mounting level. Due to the angled design, the safety bar affects the smallest possible area of the secondary light distribution when the wavelength converter is intact.

The safety bar preferably comprises an absorption area on the side facing the laser light source, which is designed in such a way that incident laser light can be at least partially absorbed. This can take place in that the absorption area comprises a surface designed to absorb laser light.

It proves to be advantageous if the absorption area on the side facing the laser light source is only in the Area is formed which covers the primary solid angle area.

According to one embodiment of the invention, the safety bar comprises a scattering area with a surface made of a scattering material, so that an incident light bundle is in particular scattered to the side or diffusely in such a way that it is not detected by the emitting optics device. A bundle of light hitting the scattering surface does not contribute to the distribution of the emitted light.

An embodiment is also conceivable according to which the safety bar comprises a reflection area with a reflection surface which is arranged in such a way that a light beam incident along the primary emission direction can be deflected in such a way that it does not contribute to the emission of light distribution. A light bundle impinging on the reflection surface is deflected in particular in such a way that it is not detected by the emitting optics device. For example, the reflection surface can be oriented obliquely to the primary emission direction.

An advantageous embodiment results from the fact that the safety bar includes a back-reflection area with a reflective surface, so that a light bundle running along the primary emission direction and incident on the reflective surface is directed back to the wavelength converter. The light bundle can then be scattered by the wavelength converter and thus at least partially contribute to the radiation light distribution. The back-reflection area can be designed and oriented, for example, in such a way that back-reflected light hits you in comparison to the original Beam direction strikes remote or marginal area of the wavelength converter. In the case of a wavelength converter that is damaged in certain areas, the radiation can thereby be directed to areas that are still undamaged, thereby increasing operational reliability.

For the further configuration of the light module, a detection element designed to detect laser radiation is provided. The safety bar preferably includes a deflection area with an at least partially reflective surface, so that a light bundle incident along the primary emission direction can be at least partially deflected onto the detection element. The detection element is set up in particular to detect an increase in intensity of the detected light. If the radiation intensity exceeds a specified threshold value, e.g. the laser light source can be switched off by control electronics.

It is conceivable that a detection element is arranged on the safety bar itself. This can be a temperature sensor, for example. In particular, the safety bar has an absorption area with an absorbent surface. The safety bar heats up through the absorption of unconverted laser radiation. If, in the case of a damaged wavelength converter, more unconverted laser radiation hits the safety bar, it will heat up more. The temperature rise is recorded by a temperature sensor. If the temperature exceeds a specified value, the laser light source can be switched off by control electronics, for example. It is also conceivable to attach an indication element to the bracket that changes its color, in particular permanently, when heated above a threshold value. Look at the discoloration of it Indication element, defects or damage to the wavelength converter can be diagnosed even when the light module is switched off.

For vehicle lighting devices, the light emitted distribution should often have characteristic properties, some of which are regulated by law. In particular, a shielded light distribution has a light-dark boundary which separates an illuminated area (below) from a dark area (above). According to one aspect of the invention, the safety bar can help to achieve the desired light distribution. For this purpose, the safety bar can, for example, have a diaphragm edge which shades an area of the secondary light distribution and which is arranged in relation to the radiation optics device in such a way that the secondary light distribution shaded by the diaphragm edge is transformed into an emitted light distribution with a light-dark border.

Further details and advantageous embodiments of the invention can be found in the following description, on the basis of which the embodiments of the invention shown in the figures are described and explained in more detail.

• Fig.1 eine skizzierte Darstellung eines erfindungsgemäßen Lichtmoduls im Normalbetrieb;
• Fig. 2 eine Detailansicht aus Fig. 1;
• Fig. 3a eine Detailansicht eines erfindungsgemäßen Lichtmoduls in einer weiteren Ausführungsform im Normalbetrieb;
• Fig. 3b eine Detailansicht eines erfindungsgemäßen Lichtmoduls aus Fig. 3a im gestörten Betrieb;
• Fig. 4 eine Detailansicht eines erfindungsgemäßen Lichtmoduls in einer weiteren Ausführungsform; und
• Fig. 5 eine Detailansicht eines erfindungsgemäßen Lichtmoduls in einer anderen Ausführungsform.

Show it:

• Fig.1 a sketched representation of a light module according to the invention in normal operation;
• Fig. 2 a detailed view Fig. 1 ;
• Fig. 3a a detailed view of an inventive Light module in a further embodiment in normal operation;
• Figure 3b a detailed view of a light module according to the invention Fig. 3a in disturbed operation;
• Fig. 4 a detailed view of a light module according to the invention in a further embodiment; and
• Fig. 5 a detailed view of a light module according to the invention in another embodiment.

In the figures and in the following description, the same or corresponding components and features are provided with the same reference symbols.

The Figure 1 shows a light module 10 for a motor vehicle headlight with a laser light source 12 in side view. This emits a primary light bundle 14 which runs concentrated around a primary emission direction 16 in a small primary solid angle range. In the in Figure 1 The normal operation shown, the primary light bundle 14 hits an optional intermediate optics 18, which directs the primary light bundle 14 onto a wavelength converter 20. The wavelength converter 20 is held by a carrier component 22 and arranged in the beam path of the primary light bundle 14 of the laser light source 12. The incident primary light bundle 14 stimulates the wavelength converter 20 to emit a secondary light distribution 24, which preferably has incoherent, polychromatic or white light. Therefore, the secondary light distribution no longer has the potentially dangerous properties of laser light.

The secondary light distribution 24 fills you up compared to the primary solid angle range from larger secondary solid angle range. An emission optics device embodied as a reflector 26 in the example shown serves to convert or deflect the light bundles of the secondary light distribution 24 into an emission light distribution 28 which is essentially concentrated around a main emission direction 30 of the light module 10.

The light module 10 comprises a safety bracket 32 which is arranged on the support component 22 of the wavelength converter 20 and protrudes over a mounting plane for the wavelength converter 20 in which the wavelength converter 20 or a light-emitting surface of the wavelength converter 20 is arranged.

Fig. 2 shows an embodiment of a light module 10 in a plan view of the carrier component 22 with the wavelength converter 20 and the safety bracket 32 fastened to the carrier component. The safety bracket 32 protrudes over the mounting plane of the wavelength converter 20. In particular, the wavelength converter 20 is positioned in a central section of the carrier component 22. The safety bracket 32 attaches, for example, to an edge section of the carrier component 22 and, starting from the edge section, protrudes over the central area of the carrier component 22. In this respect, the safety bracket 32 covers part of the surface of the wavelength converter 20 Secondary light distribution 22 on the safety bar 32. The safety bar 32 is dimensioned and arranged in such a way that the primary solid angle area is covered, in which the bundles of light run from the Laser light source 12 run around primary emission direction 16. In the ideal case, only those light bundles hit the safety bar 32 which, starting from the laser light source 12, extend in a primary solid angle range around the primary emission direction 16, so that a transformation into the emission light distribution 28 is suppressed for such light bundles. The emitted light distribution 28 is essentially generated by the secondary light distribution 24. A suppression of light beams in the comparatively small primary solid angle range around the primary emission direction 16 therefore does not lead to a noticeable loss of power or disturbances in the emission light distribution 28 during normal operation.

On the side facing the wavelength converter 20, the safety bar 32 can comprise an absorption region 34 for absorbing laser radiation. The safety bar 32 is heated by the absorption of the laser radiation. If the wavelength converter 20 is damaged, a larger proportion of laser light strikes the safety bar 32. The latter heats up more. For example, a temperature sensor 36 attached to the safety bar 32 can detect the heating.

The Figures 3a and 3b show a schematic representation of the safety bar 32 of a light module 10 in a further embodiment in trouble-free operation ( Fig. 3a ) and for an incident ( Figure 3b ). The safety bar 32 comprises a reflection area 38 with a reflection surface 40 oriented obliquely to the primary emission direction 16. In normal operation ( Fig. 3a ), ie with an intact wavelength converter 20, in the ideal case the entire primary light bundle 14 is recorded and the secondary light distribution 24 is generated. The secondary light distribution 24 shines in the Secondary solid angle range from and only that part of the secondary light distribution 24 which runs in the primary emission direction 16 is deflected by the safety bracket 32. The remaining light bundles of the secondary light distribution 24 are not reflected by the safety bar 32 and strike the reflector 26.

Is the wavelength converter 20 damaged ( Figure 3b ), the potentially dangerous laser light bundle, emanating from the laser light source 12 and the intermediate optics 18, hits the safety bracket 32. By the reflective surface 40 of the safety bracket 32, the incident light beams are directed into an area facing away from the main emission direction 30 of the light module 10 and the reflector 26 and thus carry them does not contribute to the radiation light distribution 28 of the light module 10.

The Figures 4 and 5 show further embodiments of a light module 10, the radiation optics not being shown in each case. A detection element 44 for detecting and monitoring the radiation intensity of laser light and for emitting a detector signal is arranged on a circuit board 42. In Figure 4 the safety bar 32 has a scattering area 46 with a scattering surface 48. At least part of the light bundle impinging on the safety bracket 32 is directed by the scattering surface 48 onto a light guide 50 and guided in the light guide 50 onto the detection element 44. The light guide 50 is preferably designed in such a way that only unconverted laser beams are guided. This can be achieved in particular by coating the light guide 50 or by installing an additional optical filter. Light bundle of Secondary light distributions 24 which strike the light guide 50 are then absorbed and / or reflected and preferably do not reach the detection element 44.

The detection element 44 detects the radiation intensity of the incident light bundle. In the event of a defect in the wavelength converter 20, the unconverted laser light beam strikes the safety bracket 32 and thus also the detection element 44. The detection element 44 then detects a (sudden) increase in the radiation intensity and sends a detection signal to the control electronics of the laser light source if the radiation intensity exceeds a limit value 12. In order to avoid further damage to the light module 10, the laser light source 12 can be deactivated based on the detection signal in the event of a fault.

The Figure 5 shows an embodiment in which at least a part of the light beam impinging on the safety bracket 32 is guided through a transmission opening 52 in the carrier component 22 onto the detection element 44. An optical element 54, in particular a lens, a diffractive element, a color filter or a prism, is advantageously provided in the transmission opening 52 in order to adapt the light bundles entering through the transmission opening 52 to the detection element 44.

Claims (11)

1. Light module (10) for a motor vehicle headlight, comprising:

   • at least one laser light source (12) for emitting a primary light beam (14);

   • a wavelength converter (20) for converting the primary light beam (4) into a secondary light distribution (24);

   • an emission optics device (26) for converting the secondary light distribution (24) into an emission light distribution (28) of the light module (10);

   • a carrier component (22) being provided for holding the wavelength converter (20),

   characterized in that
   the laser light source (12) is designed such that the primary light beam (14) is emitted in a primary solid angle range about a primary emission direction (16),
   and in that the wavelength converter (20) is designed such that the primary light beam (14) strikes the wavelength converter (20) in the primary solid angle range about the primary emission direction (16),
   and in that the carrier component (22) has a safety guard (32) which, starting from the wavelength converter (20), covers the primary solid angle range about the primary emission direction (16) and is arranged on the carrier component (22) such that it prevents potentially dangerous laser light of the primary light beam (14) from exiting the light module (10) .
2. Light module (10) according to claim 1, characterized in that the safety guard (32) is rigidly connected to the carrier component (22), the safety guard (32) protruding over a mounting plane for the wavelength converter (20).
3. Light module (10) according to the preceding claim, characterized in that the safety guard (32) extends, in its further extension, at a distance from the mounting plane and along the mounting plane.
4. Light module (10) according to any of the preceding claims, characterized in that the safety guard (32) has an absorption region (34) which is designed such that incident laser light is absorbed.
5. Light module (10) according to any of the preceding claims, characterized in that the absorption region (34) only completely covers the primary solid angle range.
6. Light module (10) according to any of the preceding claims, characterized in that the safety guard (32) comprises a scatter region (46) having a scattering surface (48) such that an incident light beam is scattered to the side or diffusely.
7. Light module (10) according to any of the preceding claims, characterized in that the safety guard (32) comprises a reflection region (38) having a reflection surface (40) which is arranged such that a light beam incident in the primary emission direction (16) can be deflected such that it does not contribute to the emission light distribution (28).
8. Light module (10) according to any of the preceding claims, characterized in that the safety guard (32) comprises a back-reflection region (38) having a reflective surface (40) such that a light beam incident in the primary emission direction (16) is deflected back to the wavelength converter (20).
9. Light module (10) according to any of the preceding claims, characterized in that the safety guard (32) comprises a deflection region having a reflective surface such that a light beam incident in the primary emission direction (16) can be deflected onto a detection element (44) designed for detecting laser radiation.
10. Light module (10) according to any of the preceding claims, characterized in that a detection element (36), in particular for detecting temperature, and/or an indication element, in particular for indicating temperature, is arranged on the safety guard (32).
11. Light module (10) according to any of the preceding claims, characterized in that the safety guard (32) has at least one screen edge which shades a region of the secondary light distribution and which is arranged in relation to the emission optics device (26) such that the secondary light distribution (24) shaded by the screen edge is transformed into an emission light distribution having a light-dark boundary.

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