DE102015104499A1 - Lighting device for vehicles - Google Patents

Abstract

Lighting device for vehicles with a semiconductor-based light source (1) for emitting an electromagnetic primary radiation and with a in the main emission in front of the semiconductor-based light source (1) arranged Lumineszenzkonversionselement (2), wherein the Lumineszenzkonversionselement (2) a phosphor for converting at least a portion of the primary radiation in a Secondary radiation having a different wavelength than the primary radiation comprises, wherein one of the frequency converter (2) emitted light radiation in an optical system (3, 6) is coupled, wherein at least one light sensor (4) for analyzing parts of the optics (3 , 6) coupled-in light radiation is provided.

Description

The invention relates to a lighting device for vehicles with a semiconductor-based light source, in particular a laser for emitting an electromagnetic primary radiation and arranged in the main emission before the semiconductor-based light source luminescence conversion element, in particular a light input surface for coupling the primary radiation has, which is a phosphor for converting the entire or a portion of the primary radiation in a secondary radiation having a different wavelength than the primary radiation, and in particular a light outcoupling surface for coupling the primary radiation and the secondary radiation and wherein a light emitted from the frequency converter light radiation is coupled into an optical system.

STATE OF THE ART

In various applications of the lighting industry, new light sources are used to optimize installation space, efficiency, service life and many other criteria. The latest innovations are currently heavily involved with LASER diodes as a new semiconductor light source. These are characterized by a long life, small space, the property as a point light source and high performance characteristics by an emission of monochromatic radiation. Especially in the generation of broadband light (white) is a radiation of high-energy radiation (short wave) with low half-width of the wavelengths of advantage.

About the principle of frequency conversion is e.g. With today's phosphors of different types (powder, ceramic, potting, etc.) a change in the spectrum and thus the electromagnetic energy per spectral component made. The current classification of such a light source is equivalent to LEDs.

In particular, the mechanical stresses in the automotive sector, however, it can damage the phosphor come (breakage, chipping, waste, etc.). In the case of damage, coherent LASER radiation can also escape, which in turn is subject to laser protection and thus laser protection classes.

In the WO 2014/072227 A1 a lighting device for motor vehicles is described. A laser light source is used to emit a laser light beam in a photoluminescent element. By the incident light in the photoluminescent element, a secondary light is generated in a specific light distribution. An abstraction device converts the secondary light into a radiation distribution. Light bundles extending in a primary space angle area around the primary radiation direction are suppressed by an emission inhibitor. This is intended to prevent unconverted laser light emerging from the illumination device when the photoluminescent element is damaged.

Especially in the automotive lighting industry, light sources are used which have to produce high light intensities at small dimensions. In order to optimize the optical imaging properties, the property of the "point light source" is favored. In the course of this, semiconductor elements (LED) are often connected in front of a frequency-converting element.

Currently, the use of ceramics for radiation conversion is being investigated (grenades, for example, Y3Al5O12: Ce3 + compounds). Particle physics, the energy-rich, short-wave beam is absorbed by the crystal lattice as it penetrates the phosphor, transformed into lower-energy states within the atomic energy levels and isotropically emitted by the crystal lattice in the form of short-wave radiation. The emitted radiation is broadband nature and is perceived by humans in superposition with the unabsorbed high-energy radiation as white light.

Because the phosphor is a crystalline structure, consideration is given to the possibility of damage, breakage, etc. At present, there are various possibilities for predicting a change in the radiation properties in individual modules and thus for determining whether there is a risk due to laser radiation. Common methods are the determination of the reflective component of radiation components in / from a light guide (OSRAM) or the detection of emerging radiation components from the total light distribution of the light source by partial measurement in the light cone, reflective measurement of a proportion of the light cone, etc.

Such techniques are feasible, but not usable for all lighting systems (reflection, projection) and sometimes have a high Justageanforderung to the sensor and the light source, or Einkoppelstelle on. With regard to the use of "aperture structures" in a reflective solution, there are also changes in the reflector, which can affect the imaging accuracy. In addition, it must be ensured that all error cases are detectable, which is currently not the case.

At present, there is no universal technical solution for laser-based Headlamp systems of various types that support laser safety and switch off the lighting system in the event of danger.

DISCLOSURE OF THE INVENTION

Object of the present invention is to develop a lighting device for vehicles with a semiconductor-based light source such that reliable light can be emitted via a relatively small Lichtauskoppelflächen at high luminance with high conversion efficiency.

To achieve this object, the invention in conjunction with the preamble of claim 1, characterized in that at least one light sensor is provided for analyzing parts of the light radiation coupled into the optics. The light sensor is preferably set up to analyze the detected light beams with respect to a hazard to the human eye.

The advantage of the invention is that in addition now an overall concept for the eye safety of the entire lighting device is provided. The proposed light manufacturer's eye safety concept has the advantage that it does not require any sensors used by the lamp manufacturer and immediately detects an eye hazard of the output light distribution without having sensors for detecting each individual cause of the fault. It can also detect errors whose cause can not be detected directly by a sensor, e.g. a break in the crystal structure of the converter. Furthermore, the concept offers the advantage of being applicable to any optical concepts. In particular, it can be used to detect the eye hazard for all light sources (for example lasers) whose spectrum can change from a non-eye-endangering to an eye-endangering state.

From the radiation detected by the light sensor can now make a statement about whether the laser module (laser and converting unit) is still working as desired, or has a defect and thus does not meet the safety criteria for approval. It is both a modification of the imaging system and the non-imaging system (light guide) possible.

At present, individual materials are increasingly used for the manufacture of the optics (for example glass, thermoplastics such as PMMA & PC, elastomers or silicones). Each of these materials has a certain index of refraction that can be used in conjunction with invention content to direct emitted light from the light source to total internal reflection (TIR) to an analysis sensor.

The optics may be a reflector and / or a refractor. A reflector used preferably has an opening in extension of the radiation direction of the primary radiation. If the luminescence conversion element is defective, a large proportion of primary radiation can radiate through the luminescence conversion element without being converted, which represents a particularly high eye hazard. However, the unconverted primary radiation is not reflected by the reflector to the outside, but introduced into the opening. Here this primary radiation can be made harmless. In addition, the light sensor (possibly with the interposition of a deflecting element) can be arranged behind the opening.

Preferably, at least one optical deflecting element is provided, which deflects at least parts of the optical radiation extending in the optical device in the direction of the, in particular outside, the optics mounted light sensor.

EMBODIMENTS OF THE INVENTION

Embodiments of the invention are explained below with reference to the drawings. Show it:

1 a lighting device according to the invention in a first embodiment,

2 a lighting device according to the invention in a second embodiment,

3 a lighting device according to the invention in a third embodiment,

4 a lighting device according to the invention in a fourth embodiment,

5 a lighting device according to the invention in a fifth embodiment,

6 a lighting device according to the invention in a sixth embodiment,

7 a lighting device according to the invention in a seventh embodiment.

The lighting devices according to the invention according to the 1 to 7 each comprise as a light source a short-wave semiconductor laser 1 and a downstream converter 2 , which converts the shortwave laser radiation into white light. Further, a light-shaping element in the 1 to 6 a reflector 3 or in 7 a dispersed refracting element 8th , and at least one light sensor 4 provided that evaluates the converted light in terms of its eye sensitivity and above a certain threshold one Safety mechanism, in the simplest case shutdown, activated.

The light sensor 4 may be a photo element which integrates over the entire sensitivity range of the eye, integrated over the blue peak of the laser radiation and / or integrated over the yellow range of the converted white light. Any combination in which threshold values for calculated sensor output variables are defined is also conceivable.

The light sensor 4 can be arranged in the illumination device such that this scattered light is detected and analyzed, which runs outside the actual beam path (see 1 and 2 and 7 ).

The light sensor 4 can be arranged in the illumination device such that this scattered light is detected and analyzed, which extends outside the actual beam path and in particular from any lens 7 is reflected (Fresnel reflection) (see 3 ).

The light sensor 4 can be so behind an opening 9 in the reflector 3 be arranged that detects this directly emitted from the laser diode light and evaluated (see 4 ).

The light sensor 4 can be arranged such that this of a deflecting element 5 which is behind an opening 9 in the reflector 3 is arranged, deflected indirect light detected and evaluated (see 5 ).

The light sensor 4a may be arranged such that this spectral components, in which the light previously by a disperse element 8th was dissected, recorded and evaluated. Preferably, at least one additional spectral component is thereby produced by at least one additional sensor 4b recorded and evaluated (see 6 ).

The light sensor 4 may be arranged such that it consists of a light-guiding / -forming refractive element 6 leaking light is detected and evaluated (see 7 ); Preferably, such light is detected, which does not exit at a defined light exit surface of the lamp, which is therefore not intended for the defined illumination of the road.

Any combination of the presented variants is conceivable. An advantage of in the 4 . 5 and 6 variants shown is that in the case of converter damage, eg by breakage or saturation, the shortwave light emitted by the laser (primary radiation), which is classified as particularly dangerous to the eye, in fact absorbed in a kind of light trap and thus to the eye before the activation of the safety mechanism is made harmless. That's the opening 9 of the reflector 3 arranged in extension of the unconverted laser beam.

LIST OF REFERENCE NUMBERS

1

laser

2

frequency converter

3

reflector

4

light sensor

5

deflecting

6

refractive element

7

lens

8th

dispersive element

9

opening

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• WO 2014/072227 A1 [0005]

Claims (9)

Lighting device for vehicles with a semiconductor-based light source ( 1 ) for emitting an electromagnetic primary radiation and with a main emission direction in front of the semiconductor-based light source ( 1 ) arranged luminescence conversion element ( 2 ), wherein the luminescence conversion element ( 2 ) comprises a phosphor for converting at least a portion of the primary radiation into a secondary radiation having a different wavelength than the primary radiation, one of the frequency converter ( 2 ) emitted light radiation in an optic ( 3 . 6 ) is coupled, characterized in that at least one light sensor ( 4 ) for the analysis of parts of the optics ( 3 . 6 ) coupled light radiation is provided. Lighting device according to the preceding claim, characterized in that the optics by a reflector ( 3 ) is formed. Lighting device according to the preceding claim, characterized in that the reflector ( 3 ) in the extension of the radiation direction of the primary radiation an opening ( 9 ), so that unconverted primary radiation is not transmitted through the reflector ( 3 ) is reflected to the outside. Lighting device according to the preceding claim, characterized in that behind the opening ( 9 ) the light sensor ( 4 ) is arranged. Lighting device according to claim 1, characterized in that the optics by a refractive element ( 6 ) is formed. Lighting device according to one of the preceding claims, characterized in that the light sensor ( 4 ) is arranged to analyze the detected light beams with respect to a malfunction, in particular a hazard to the human eye. Lighting device according to one of the preceding claims, characterized by at least one optical element ( 5 . 6 . 7 . 8th ), which at least parts of the optics ( 3 . 6 ) extending light radiation in the direction of, in particular outside the optics ( 3 . 6 ), light sensor ( 4 ) redirects. Method for monitoring a lighting device according to one of the preceding claims, wherein the light emitted by the at least one light sensor ( 4 ) detected light radiation on a malfunction, in particular their threat to the human eye, is examined out and if necessary, a safety shutdown of the laser ( 1 ) is carried out.  Monitoring unit for a lighting device according to one of claims 1 to 7 or for carrying out the method according to claim 8.

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