WO2015154926A1

WO2015154926A1 - Headlight module

Info

Publication number: WO2015154926A1
Application number: PCT/EP2015/054824
Authority: WO
Inventors: Andreas Petersen; Stefan Leidich
Original assignee: Robert Bosch Gmbh
Priority date: 2014-04-09
Filing date: 2015-03-09
Publication date: 2015-10-15
Also published as: DE102014206822A1; EP3129702A1; CN106461178A

Abstract

Disclosed is a headlight module (10) comprising a luminophore (20) which can be excited using electromagnetic radiation so as to emit light, a radiation source (12) for exciting the at least one luminophore (20), and a supporting device (18) for the luminophore (20). Said headlight module is characterized in that a surface (19) of the supporting device (18) has a structure comprising depressions (17) and in that the luminophore (20) is placed in the depressions (17) on the surface (19) of the supporting device (18). The invention allows for higher spatial resolution of the light emitted by a headlight as well as for an increased light yield.

Description

Description title

Headlamp module The invention is based on a headlamp module according to the preamble of the independent patent claim.

PRIOR ART Headlights in the field of motor vehicle technology enable the choice between a plurality of fixedly defined light distributions, such as low beam, high beam and fog light, for example. Increasingly, so-called adaptive headlamp systems are spreading, which expand the selection of light distributions and allow, for example, dynamic cornering light, highway, city and bad weather light. The selection of the light distributions can be made by the motor vehicle system depending on the situation.

A further development in the field of vehicle lighting represent so-called active headlamps. These are not limited to predefined light distributions, but allow, similar to a projector, any

Light distribution in the space in front of the vehicle. With such a system it is for example possible to hide oncoming and preceding vehicles within the own high beam, also referred to as so-called glare-free high beam, or to highlight possible sources of danger by direct lighting for the driver.

Such active headlamps can be realized essentially in two principal ways. In subtractive systems, the entire generated luminous flux is transmitted through a matrix of optically active elements, for example LCD, LCoS, DMD, conducted. Bright areas are created by allowing the luminous flux to pass through. For dark areas, the luminous flux is absorbed by means of the optically active elements, for example LCD or LCoS, or deflected, for example by means of DMD, in the direction of an absorber. In subtractive systems, the generation of light and its variable distribution in space take place in different components. For this reason, the power density of the light source does not limit the resolution of the system. Small-sized systems with relatively high resolutions can therefore be achieved. Due to the principle, the optical losses are higher in a subtractive system than in an additive system.

Additive systems illuminate the scene via matrix arrangements of light sources, for example LEDs, in which the individual light sources can be switched on and off as required. In an ideal additive system, therefore, the entire amount of light generated is always used. The necessary cooling of the light source matrix in such a system typically limits the size, the maximum brightness and / or the achievable resolution.

One way to spatially separate light generation and distribution in an additive active headlight system is to use a stimulable phosphor with electromagnetic radiation, for example, laser radiation. The phosphor is scanned here with the stimulating radiation and then imaged using projection optics. The principle is shown for example in DE 10 2010 028 949 AI.

Advantages of the invention

The headlight module according to the invention with the features of the independent claim offers the advantage of increased spatial resolution of the light emitted by him, improved contrast and increased light output. To achieve a comparable brightness at the desired lighting destination is thus compared to the solution according to the prior art, a smaller Energy supply required. In addition, the system generates less waste heat, so that the cost of cooling the system can be reduced.

This is achieved with a headlamp module comprising a phosphor excitable for emitting light by electromagnetic radiation, a radiation source for exciting the at least one phosphor, and a phosphor support, wherein a surface of the support means has a dimpled structure and wherein the phosphor is disposed in the recesses of the surface of the carrier device. The recesses serve as reflectors, and focus the light emitted by the phosphor.

The headlight module according to the invention can advantageously be used in the field of motor vehicle technology, in particular as part of an active driving light, as described in the section of the prior art, that is to say in a vehicle headlight. Further advantageous uses are, for example, spotlights for stage lighting, workplace lighting, living room lighting and others.

Advantageously, the recesses of the phosphor carrier device each have a reflective surface on which the phosphor is applied. This reduces absorption of parts of the light generated by the phosphor by the carrier device and thus increases the luminous efficacy and reduces the waste heat of the system, which otherwise might have to be dissipated by separate cooling measures. Advantageously, the reflective surface of the depressions can be formed by a reflective layer introduced into the depression. Alternatively, a polish for producing a reflective surface of the wells would be conceivable.

Advantageously, the recesses containing the phosphor on the surface of the carrier device have an ellipsoidal shape. This form is particularly suitable for the bundling of the diffused by the phosphor, so undirected light. Drawings Exemplary embodiments of the invention are illustrated in the figures and will be explained in more detail below. Show it

Figure 1 is a schematic representation of the understanding of the invention essential part of a headlamp module according to the prior art and

Figure 2 is a schematic representation of the invention essential part of the headlamp module according to the invention. Description of the embodiments

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows, in a schematic representation, the part of a headlamp module 10 according to the prior art which is essential for understanding the invention and as described in detail in DE 10 2010 028 949 A1, for example.

This headlamp module 10 comprises a radiation source 12 which is designed to emit electromagnetic radiation, in the present case laser light, in this case blue laser light. For example, the radiation source 12 may be a laser diode. The radiation source 12 gives the

Radiation, here the laser light directed and focused, so in the form of a laser beam. The radiation of the radiation source 12 strikes a beam steering device 14 which comprises a mirror, preferably a micromirror device. As indicated by the two double arrows, the micromirror is designed as a micromirror pivotable in two spatial axes in response to electrical activation. Thus, the incident laser light beam can be deflected in a desired direction depending on the electrical control of the micromirror. Instead of a single micromirror which can be swiveled in two spatial axes, two can also be used Micromirror can be used, which are pivotable in one spatial direction. If no vertical resolution is needed, a single-axis mirror would also be possible.

The radiation of the radiation source 12 deflected by the beam steering device 14 impinges on a phosphor 20 which can be excited by means of electromagnetic radiation, here for example blue laser light and which is arranged on a carrier device 18. The support device 18 is preferably made of highly thermally conductive material, such as a suitable ceramic, such as ceramic, for example polycrystalline alumina ceramic (PCA) or sapphire. The beam steering device 14 allows the deflection of the radiation beam generated by the radiation source 12 to an arbitrary point of the surface of the phosphor 20. The control of the beam steering device 14 not shown separately in the figure is designed to deflect the radiation emitted by the radiation source 12 such that temporally successively different areas of the phosphor 20 are excited.

Similar to the line by line image construction in a picture tube of a television in which the human eye perceives a planar image by a suitable temporal and spatial control pattern, the driving pattern of the beam steering device 14 is carried out according to the invention, so that from an interaction of temporal resolution of the human eye and reaction times of the Luminescent 20 the human eye perceives a steady lighting of the headlamp module without flicker or the like.

As a result of the excitation by means of the electromagnetic radiation 13, the phosphor emits light 21. The light output is not bundled in the solution according to the prior art, but diffuse. By suitable deflection schemes, the desired light distributions of the headlight module and the headlight module having headlight, for example, a motor vehicle. With regard to the construction and the mode of operation of the headlight module described and of a suitable phosphor, reference is made to DE 10 2010 028 949 A1, the disclosure content of which is hereby included in the present patent application.

In Figure 2, the invention essential part of a headlamp module 10 according to the invention is shown in a schematic representation. In contrast to the headlight module 10 according to FIG. 1, the carrier device 18 of the headlight module 10 according to the invention has a structured surface 19 which comprises depressions 17. The structure may advantageously be a microstructure.

The exact shape of the individual microreflectors can be determined, for example, by means of optical simulation. It should be such that it collimates the emitted light. The microreflectors are particularly suitable for a front-side excitation, as shown in FIG. Instead of microreflectors and micro-optics can be used, which are suitable for a back excitation, as described in DE 10 2010 028 949 AI.

The microstructures should be larger than the wavelength of the laser light used (450 nm) and less than 1 mm. Ideally, the structure sizes should be between 1 μηι and 100 μηι. In principle, all possibilities of surface microstructuring are available for the production of the microstructure. Most promising, however, are embossing methods such as. Micro and nanoimprint process. Also ablation methods, such as laser ablation, followed by chemical or physical smoothing in question.

In the recesses 17 of the surface 19 of the support device 18 of the electromagnetically excitable phosphor 20 is introduced. The phosphor 20 is preferably located exclusively within the depressions 17. The phosphor 20 is excited by the excitation source 12, here the laser 12 diffuse, so undirected light from. The part of the light that is emitted in the direction of the bottom 171 or the walls 172 of the recesses 17 is at least partially reflected by the bottom 171 or the walls 172. To reduce absorption of parts of the light emitted in the direction of the bottom or walls of the depressions 17 and thus to increase the reflectance, the depressions 17 have a reflective coating 15. This can be done by polishing the wells. Alternatively, preferably, a reflective layer 15 may be incorporated. The reflective layer can be made, for example, of metallic material with high reflectivity, such as, for example, silver (Ag) or aluminum (Al) or dielectric layers or layer stacks of materials which have no or very little absorption at the laser wavelength, such as, for example, silicon nitride (SiN), Silica (SiO 2), titanium dioxide (TiO 2).

For introducing or producing the reflective layer, known methods, such as vapor deposition, for example thermal evaporation, electron beam or ion beam evaporation, physical vapor deposition (PVD) methods, such as sputtering or pulsed laser deposition (PLD), deposition from the gas phase, for example Chemical Vapor deposition (CVD), plasma enhanced CVD (PECVD) or electrochemical deposition from solution.

The phosphor consists of an optically active phosphor powder which is embedded in a suitable matrix material. The matrix material should be optically transparent in the relevant wavelength range, have a suitable refractive index and have sufficient thermal conductivity to dissipate the waste heat. Typical matrix materials are plastics such as polymers and polycarbonates, glass, silicone, or the like.

The mixture of phosphor powder and matrix material can be in the form of a liquid, a gel or a paste before the final curing and applied in this form to the structured carrier substrate.

From the recesses 17 passes through the walls 172 and the bottom 171 and reflected directly from the phosphor 20 from the recess 17 out radiated light 21 off. This has a lower divergence compared to the prior art. By suitable shaping of the depressions, the light emerging from the depressions 17 can be further bundled. For this purpose, the depressions 17 preferably have an ellipsoidal cross-section. This cross-section has proven advantageous for the bundling of diffused light. Alternatively, the shape of a micro free-form reflector can be used. A free-form reflector is a reflector whose shape does not correspond to a mathematically definable figure. Macroscopic free-form reflectors are known per se and are used in many motor vehicles as the main optics in clear glass headlights.

For further construction and operation of the headlight module according to the invention, reference is made to the description in connection with Figure 1 and the disclosure of DE 10 2010 028 949 AI.

Claims

claims

1. Headlight module (10) with

a phosphor (20) which can be excited by means of electromagnetic radiation for emitting light,

a radiation source (12) for exciting the at least one phosphor

(20)

a carrier device (18) for the phosphor (20)

characterized,

in that a surface (19) of the carrier device (18) has a structure with depressions (17) and that the phosphor (20) is arranged in the depressions (17) of the surface (19) of the carrier device (18).

2. headlamp module according to claim 1, characterized in that the recesses (17) each have a reflective surface to which the phosphor (20) is applied.

3. Headlamp module according to claim 2, characterized in that the reflective surface of the recesses (17) is formed by an introduced into the recess reflective layer (15).

4. Headlamp module according to one of the preceding claims, characterized in that the recesses (17) have an ellipsoidal shape.