DE102015104506A1 - Lighting device for vehicles - Google Patents

Abstract

Illumination device (1) for vehicles with a semiconductor-based light source (2) for emitting an electromagnetic primary radiation and with a luminescence conversion element (3) arranged in the main emission direction in front of the semiconductor-based light source (2), wherein the luminescence conversion element (4) comprises a phosphor for converting at least part of the Primary radiation into a secondary radiation, which has a different wavelength than the primary radiation comprises, wherein one of the frequency converter (3) emitted light radiation is coupled into an optical system (5), wherein at least one light sensor (7) for analyzing the optics (5) coupled light radiation (4) 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 a part 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 the luminescence conversion element is associated with a heat sink for cooling.

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. This is characterized by a long life, small space, the property as a point light source and high performance 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 eg Y3Al5O12: Ce3 + compounds). Particle physics, the energy-rich, short-wave radiation 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 reflected portion of radiation components in / from a light guide or the detection of emerging radiation components from the total light distribution of the light source by partial measurement in the light cone, measurement of a reflected portion of the cone of light, 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 reflection-based 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 the light radiation coupled into the optics. The detected light radiation can now be evaluated by an evaluation unit with regard to possible damage to the lighting device. In particular, the frequency spectrum contained in the light radiation is recorded and analyzed.

The invention makes use of the fact that in a system with optically imaging units (primary, secondary optics, etc.) the "collected" luminous flux of the light source is passed through the optics and subsequently imaged. So far, symmetrical optics are often used. Following the trend in terms of design, efficiency, new materials and production processes as well as the weight advantage due to material savings, cropped optics can be used. In this case, the optically, for the illustration not relevant surfaces can be removed. Often, this also partially in the optical system existing radiation components (scattered radiation, internal reflections, not mainly relevant radiation components, etc.) away; However, these are relevant for an analysis of the radiation in the optical imaging system of the light source and can be used for the analysis.

For the invention described herein, a modification of the imaging system is to be used in order to make a statement about the emitted and directed radiation, whether the laser module (laser and converting unit) is still working as desired, or has a defect and thus the security features not approved. It is both a modification of the imaging system and the non-imaging system (light guide) possible.

At present, individual materials are increasingly being used for the production of the optics (eg 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.

Preferably, the illumination device comprises an arrangement with a multiplicity of light sensors for detecting light radiation extending at different positions of the optics. Alternatively, a light sensor can be mounted in the optics or directly on the optics, which can detect parts of the light radiation extending in the optics.

Preferably, at least one optical decoupling element is provided, which is arranged at least partially in the optics and deflects at least parts of the optic light radiation extending in the direction of a, in particular outside, the optics mounted light sensor.

Thus, in some regions of optics, preferably those which are not necessary for imaging of structures (eg, see the areas described above), individual defined geometric structures may be introduced, e.g. B. holes, in which then a z. B. a light-conducting optical unit is introduced, which is characterized by a higher refractive index than the surrounding lens material and optionally by a (eg., 45 °) angle entry surface for the emitted light, the light source is facing.

In a further preferred embodiment, reflector structures, in particular prism structures, can also be introduced into the lens in a production method, which reflect a radiation component incident on them onto the positioned analysis unit.

In a further preferred embodiment, individual portions of the detection material (eg, materials silicon, which correspond to the spectrum of the short-wave peak of the frequency-converted radiation) can be introduced into the optics, especially in the case of silicon, in order in particular to enable immediate analysis of the radiation ,

The present invention thus enables the analysis of "white" radiation according to the automotive requirements for headlamps directly on the lighting device. Thus, no complex setups are needed for capturing the radiation components from the emissive and optical components of the overall system, resulting in a simplification of the design. Furthermore, there are the following advantages, the space optimization, the reduction of complexity compared to other solutions, the possibility of individual monitoring of the laser elements in multi-laser diode assemblies and the security elements and the use of surfaces and sensor elements already in Headlights are installed. A real-time shutdown becomes possible.

EMBODIMENT 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,

The subfigures a) each show the lighting devices in cross section, the subfigures b) each show the lighting devices in longitudinal section.

The lighting device according to the invention 1 according to figure comprises as a light source a short-wave semiconductor laser 2 which is behind a luminescence conversion element 3 with a frequency-converting layer, such as a phosphorus ceramic sitting. Through this unit of semiconductor laser and luminescence conversion element 3 becomes light 4 in a decoupling element 6 ' , in this case a TIR (total internal reflection) optics 6 ' coupled, which has a certain refractive index n1. By the given form ( 1a ) is formed at the same time a typical for the vehicle low beam light-dark boundary, which can also be projected by a secondary optics in the apron of the vehicle. It is an arrangement 9 with a plurality of radiation detector units 7 ' However, with regard to safety and the effect chains the radiation detector unit as close as possible to the light source 2 should be positioned. Which in this case in the TIR primary optics 5 coupled radiation 4 has at commissioning a specific pattern (spectrum) which can be accurately described by a ratio of shortwave and longwave radiation. This radiation is due to the internal reflection on the lateral surface of the optics 5 totally reflected and reaches the optical output, as well as in the "decoupling trap" with the light guide 6 ' , which in the optics 4 is introduced via a channel or the like, has a higher refractive index n2> n1 and has a special coupling surface inclination. Via a prism angle of the light guide 6 is the total reflection of a part of the emitted radiation 4 to the radiation detector unit 7 ' passed and detected there. Again, the radiation 4 totally reflected on the optical interfaces to the environment and on the sensor 7 ' radiated. This unit 7 ' compares the received radiation components or the components of the short-wave radiation with a reference value. Should a positioning error of the semiconductor laser 2 to the phosphor, a Phosphorriss, a leaking of the phosphor or other damage occur, the actual signal of a stored in the evaluation unit target signal will differ and a safety circuit can disable the laser.

In the embodiment according to 2 is dispensed with working on the TIR principle decoupling element. Special production methods can be used to create optical elements 6 '' in the optics 5 be introduced so that a radiation reflection takes place such that a partial radiation on a sensor element 7 is decoupled. This reduces the space and the disturbance of the beam path from the light source 2 to the exit of the primary optics 4 , Incidentally, the design of the 2 with the one after 1 match.

In the embodiment according to 3 become decoupling structures 6 ''' in the interface between the material of the optics 5 and the environment introduced (eg radiation decoupling prisms), the radiation 4 on the light sensor 7 to steer. Incidentally, the design of the 3 with the one after 1 match.

In the embodiment according to 4 is dispensed with an optical radiation deflection and decoupling. There are individual tracks of radiation-sensitive material 7 '' (Silicon, eg a-SiC: H pin structures) as light sensors on the primary optics 5 applied or in the material of primary optics 5 introduced an immediate signal for the evaluation unit 8th to obtain. This minimizes shading by optical elements in the primary optics 5 as well as the number of optical parts and components as well as possibly the effort for the production process. A network / matrix structure can be used. Incidentally, the design of the 4 with the one after 1 match.

LIST OF REFERENCE NUMBERS

1

lighting device

2

laser

3

frequency converter

4

light radiation

5

optics

6

outcoupling

7

light sensor

8th

evaluation

9

Arrangement of light sensors

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 (10)

Lighting device ( 1 ) for vehicles with a semiconductor-based light source ( 2 ) for emitting an electromagnetic primary radiation and with a main emission direction in front of the semiconductor-based light source ( 2 ) arranged luminescence conversion element ( 3 ), wherein the luminescence conversion element ( 4 ) 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 ( 3 ) emitted light radiation in an optic ( 5 ) is coupled, characterized in that at least one light sensor ( 7 ) for the analysis of the optics ( 5 ) coupled light radiation ( 4 ) is provided. Lighting device ( 1 ) according to the preceding claim, characterized in that the optic is a TIR optic or a mirrored optic body. Lighting device ( 1 ) according to one of the preceding claims, characterized by an evaluation unit ( 8th ) for the evaluation of the at least one light sensor ( 7 ) detected light radiation ( 4 ) with regard to possible damage to the lighting device ( 1 ). Lighting device ( 1 ) according to one of the preceding claims, characterized in that the light sensor ( 7 ), which is in the light radiation ( 4 ) recorded frequency spectrum and provide an evaluation. Lighting device ( 1 ) according to one of the preceding claims, characterized by an arrangement ( 9 ) a plurality of light sensors ( 7 ) for detecting at different positions of the optics extending light radiation ( 4 ). Lighting device ( 1 ) according to one of the preceding claims, characterized by at least one optical outcoupling element ( 6 ), which at least partially in the optics ( 5 ) and at least parts of the optics ( 5 ) extending light radiation ( 4 ) in the direction of one, especially outside, the optics ( 5 ) mounted light sensor ( 7 ' ) redirects. Lighting device ( 1 ) according to one of the preceding claims, characterized in that in optics ( 5 ) or directly on the optics ( 5 ) a light sensor ( 7 '' ), the parts of the optics ( 5 ) extending light radiation ( 4 ). Method for monitoring a lighting device according to one of the preceding claims, wherein the light emitted by the at least one light sensor ( 7 ) detected light radiation ( 4 ) with regard to possible damage to parts of the lighting device ( 1 ), in particular parts of the light source ( 2 ) and / or the luminescence conversion element ( 4 ) and, if necessary, a safety shutdown of the light source ( 2 ) is carried out. A method according to claim 8, characterized in that in the detected light radiation ( 4 ) evaluated frequency spectrum is evaluated. Monitoring unit for a lighting device ( 1 ) according to one of claims 1 to 7 or for carrying out the method according to one of claims 8 or 9.

Images