WO2016154647A1

WO2016154647A1 - Lighting device

Info

Publication number: WO2016154647A1
Application number: PCT/AT2016/050057
Authority: WO
Inventors: Andreas Luger
Original assignee: Zkw Group Gmbh
Priority date: 2015-04-02
Filing date: 2016-03-14
Publication date: 2016-10-06
Also published as: CN207049823U; DE202016008100U1; AT517019B1; AT517019A1

Abstract

The invention relates to a lighting device (1) for a motor vehicle, comprising a luminous element module (10) with at least one light emission source (200), at least one light guiding element (300), and at least one luminous element (400). The light guiding element (300) is designed to guide (110) light (100) supplied by the at least one light emission source (200) through at least one light in-coupling surface (310) of the light guiding element (300) to a light out-coupling surface (340) of the light guiding element (300), and the light out-coupling surface (340) of the light guiding element (300) is designed to direct light (120) emitted from the light out-coupling surface (340) in the emission direction (120) onto at least one light entry surface (410) of the luminous element (400), wherein the emitted light (120) reaches (130) the luminous element (400) through the light entry surface (410) of the luminous element (400) and exits (140) the luminous element at at least one light exit surface (420) of the luminous element (400). At least one light in-coupling surface (310) and/or light out-coupling surface (340) of the at least one light guiding element (300) and/or at least one light entry surface (410) and/or light exit surface (420) of the at least one luminous element (400) has or have a structured reflection-blocking boundary surface (500).

Description

ILLUMINATION DEVICE

The invention relates to a lighting device for a motor vehicle, which lighting device comprises a luminous element module having at least one light emission source, with at least one light guide element and at least one luminous element, the light guide element being adapted to transmit light fed by the at least one light emission source through at least one light coupling surface of the light guide element to direct a light outcoupling surface of the light guide, and the light outcoupling surface of the light guide is adapted to direct light emitted from the light output surface in the emission on at least one light entrance surface of the filament, the radiated light passes through the light entrance surface of the filament into the filament and at least one Light exit surface of the filament emerges again from this.

The advent of LED technology for lighting devices for motor vehicles has meant that in particular the headlights and the taillights in motor vehicles have developed in recent years into veritable design elements. For particularly flexible representation of different lighting designs are so-called glow bar concepts are particularly well. Through the use of light-conducting elements, which are usually designed rod-shaped in the form of light rods, lighting devices can be realized with a variety of homogeneous luminous geometries. For example, luminous strips or luminous rings can be realized in the context of lighting devices with such luminous rod concepts. By using a luminous body module, in which a three-dimensional luminous body is arranged upstream of the optical waveguide, it is even possible to produce three-dimensional SD lighting effects. However, conventional light guides or glow sticks have the great disadvantage that they are very inefficient. In a conventional light rod concept, the light is usually fed into the light guide on the front side. The alignment of the light beams to the front then takes place via calculated prisms, which are arranged on the light-guiding element. Due to the different refractive indices, the light conduction at the interfaces between the optical material of the light guide element and the surrounding air between the light guide element and the preceding luminous body leads to undesired reflections at the entry and exit surfaces of the light guide element and the luminous element, thereby increasing the overall efficiency and luminous efficiency decreases adversely and the achievable light intensity of such filament modules is low. Different designs of vehicle headlamps with light guides are known from the prior art. For example, document US 2014/0056021 A shows a vehicle headlight with a laser light source, the laser light being conducted via a light guide onto a phosphorus conversion layer. The light guide can be provided at its light entry surface with an anti-reflection coating.

Furthermore, the document EP 2 518 838 A2 shows a vehicle headlight with a light guide, which is provided with an antireflection coating on its input and / or output surfaces. The antireflection coating may also have a moth-eye structure. Similar to the embodiment shown in document US 2014/0056021 A, a deflection mirror with a phosphor coating is also irradiated in the case of the vehicle headlight disclosed in document EP 2 518 838 A2.

The present invention therefore has as its object to avoid the known from the prior art disadvantages for a lighting device of the type mentioned, and to provide a device with a significantly higher transmission or higher overall efficiency. At the same time the light intensity of the lamp module is to be increased.

This object is achieved in a lighting device according to the preamble of claim 1 with the features of the characterizing part of claim 1. The subclaims relate to particularly advantageous further embodiments of the invention.

In a lighting device according to the invention for a motor vehicle, which lighting device comprises a luminous element module having at least one light emission source, with at least one light guide element and at least one luminous element, wherein the light guide is adapted to light fed by the at least one light emitting source through at least one light input surface of the light guide element To direct light output surface of the light guide, as well as the light outcoupling surface of the light guide is adapted to direct light emitted from the light output surface in the emission on at least one light entrance surface of the filament, the radiated light passes through the light entrance surface of the filament into the filament and at least one light exit surface the luminous body again emerges from this, has or have at least one light coupling surface and / or r light output surface of the at least one light guide and / or at least one light entrance surface and / or light exit surface of the at least one luminous body on a reflection-inhibiting structure interface. The use of reflection-inhibiting structure boundary surfaces at the boundary surfaces of the light-guiding element and / or the luminous element achieves at least partial antireflection of the corresponding boundary surfaces and thus a reduction in Fresnel losses at the interfaces, the reflection-inhibiting structured boundary surfaces having a significantly higher transmission than the corresponding ones untreated surfaces. Thus, the overall efficiency of the lighting device is significantly increased and increases the potential applications of such lighting devices with lighting modules. Due to the different refractive indices, reflections occur at the entrance and exit surfaces of the light-guiding element or the luminous element. The reflectance is primarily dependent on the refractive index difference of the two materials meeting at the interfaces of air with a refractive index of about n = l and the corresponding material of the light guide or the filament, such as glass or plastic. As a plastic, for example, polycarbonate - PC for short - with a refractive index of about n = l, 58 are used. For each non-reflective interface (air / plastic or plastic / air), an increase in efficiency or an increase in light intensity of approx. 5% can be achieved. In the case of an antireflection coating of a conventional light-guiding element in that the light-incoupling surface and the light-outcoupling surface of the light-guiding element are each provided with an antireflective structure interface, an increase in efficiency of approximately 10% is possible. In the case of a luminous rod concept with an upstream luminous body, the overall efficiency can even be increased by about 15 to 21.5%, even if the light entry surface and the light exit surface of the filament each have a reflection-inhibiting structural interface.

In the context of the invention, the at least one reflection-inhibiting structure interface can also have macrostructures. It is thus possible, for example, for the reflection-inhibiting structure boundary surface on the light-guiding element and / or on the luminous body to consist of a plurality of respectively structured partial surfaces, wherein the partial surfaces are arranged, for example, in a stepped manner relative to one another. Each of the partial surfaces is equipped with an antireflective structure interface.

In an illumination device according to the invention, the reflection-inhibiting structure interface expediently has a periodic moth-eye structure at least in sections. It is known from nature that the eyes of some nocturnal insects do not reflect. This so-called "moth eye effect" is not due to reflection-inhibiting coatings, but to nano-structured ocular surfaces of such insects, in which tiny columns are arranged equidistantly on the ocular surface and form an antireflective structure through which a gradual change in refractive index is caused. The individual compound eyes look like hexagonal surface lattices. The structure depth of the minute columns or gratings is for example about 200 nm, with distances between the columns being for example about 230 nm.

Likewise, within the scope of the invention, reflection-inhibiting structural boundary surfaces are used which, at least in sections, have a periodic moth-eye structure. Advantageously, such a periodic moth-eye structure offers a low angle of incidence dependence and permits antireflection of the corresponding surfaces over a broad spectral range, from the near UV wavelength spectrum to the visible light spectrum (VIS) and into infrared light (IR). By introducing this special moth-eye structure on the interface of an optically transparent medium, a refractive index gradient is obtained which increases continuously towards the substrate.

Surfaces with moth-eye structures are also referred to as periodic surface profiles, which can be described as optical gratings. An optical grating is understood to mean all locally periodic structures which act on the phase or the amplitude of the light radiation. The structure period, the structure shape and the material properties determine the lattice properties. The optical effect of such moth-eye structures is based on the diffraction of the incident light at the surface grid. This effect occurs when the period of the surface is smaller than that of the incident light. The diffraction is stronger, the smaller the ratio of grating period to light wavelength. The structured interface of the optically denser medium thus behaves like a Fresnel reflection-less plane surface. The effect of increasing the efficiency arises from the gradual change in the refractive index, so that the refractive index of the lens material continuously approaches the refractive index of air. As a result, the Fresnel losses decrease as they pass through the material interface. The regular arrangement of these structural elements leads to a strong angular dependence of the reflection.

In a further advantageous embodiment of the invention, in an illumination device, the reflection-inhibiting structure interface has, at least in sections, a stochastic moth-eye structure. In this simplified form of manufacture, moth-eye structures can also be made by subjecting the ratio of periodic surface profiles or optical gratings to irregular variations. Stochastic structures are further advantageous in terms of the angular dependence of the reflection, which is reduced compared to regularly arranged structural elements. Suitably, in a lighting device, the stochastic moth-eye structure of the reflection-inhibiting structure interface is produced by targeted treatment of a polymeric material with an ion plasma. By way of example, the surfaces to be structured are bombarded with an ion plasma, but interferences in the material to be structured likewise influence the shape of the stochastic moth-eye structure.

Appropriately, in an illumination device according to the invention, the reflection-inhibiting structure interface by microstructured valleys and mountains of a limit curve can be approximated, with adjacent valleys and mountains are spaced apart on the micrometer scale. In principle, the smaller the structure of the reflection-inhibiting structure interface, the higher the transmissions with substrates structured in this way in comparison with correspondingly untreated surfaces can be achieved.

In a lighting device according to the invention, the reflection-inhibiting structure boundary surface can be specified or described in an approximately advantageous manner by nanostructured valleys and mountains of a limit curve, wherein adjacent valleys and mountains are spaced apart on the nanometer scale. In this version with nanostructured reflection-inhibiting structural interfaces, a particularly good anti-reflection of the surfaces and thus a particularly high light intensity is achieved.

In a further advantageous embodiment of the invention, the light-guiding element and / or the luminous element is or are made of plastic in an illumination device, and the reflection-inhibiting structure boundary surfaces are introduced directly into a plastic tool. The anti-reflection takes place via a moth eye structure, which is introduced directly into the plastic tool. Advantageously, no additional manufacturing costs are incurred in the subsequent production of the plastic parts themselves.

In an illumination device according to the invention, the reflection-inhibiting structural boundary surfaces in the plastic are advantageous in the form of model impressions of a plastic tool.

In an illumination device according to the invention, the light-guiding element is expediently equipped with deflecting prisms in the region of its light output surface, wherein the Deflection prisms are set up to redirect light diverted in the light guide element substantially in the same emission direction from the light outcoupling surface.

In one development of the invention, the light outcoupling surface of the light-guiding element is arranged at least in sections parallel to the light-entry surface of the luminous element in an illumination device. In this arrangement, the efficiency of the lighting device is further increased because light emitted from the light outcoupling surface of the light guide element strikes the light entrance surface of the light body parallel to the light outcoupling surface of the light guide element, thereby entering the interior of the light body substantially directly and without reflection.

In a further advantageous embodiment of the invention, in the case of an illumination device, the light-guiding element is a luminescent rod with a 3D carrier curve, the luminescent rod preferably having a circular or oval cross-section. For example, the luminescent rod has a tubular shape that is shaped along a three-dimensional 3D carrier curve. In the event that the luminous rod has a substantially cylindrical shape, corresponds in this case, the 3D carrier curve of a longitudinal axis of the cylindrical luminous rod.

In an illumination device according to the invention, the at least one light entry surface and the at least one light exit surface of the luminous body are expediently arranged substantially parallel to one another.

The field of application of the invention is intended primarily for the motor vehicle headlight area. However, it is provided within the scope of the invention and conceivable to use lighting devices according to the invention also in other areas, such as in the tail light area or for lighting in the interior of the vehicle. The invention can thus be used in the entire motor vehicle sector for different lighting tasks both in cars, trucks, and motorcycles.

From the prior art, different manufacturing methods for provided with a moth eye structure plastic surfaces are known. For example, the negative form of the moth eye structure is applied to a mold insert of a tool. Subsequently, the anti-reflective optical components, without further steps, can be produced directly in an injection molding process. The moth-eye structure is formed directly on the surface of the corresponding optical elements. The advantage of the technology lies in the fact that the optical components in comparison to coating methods with interference layers can be produced inexpensively and in large quantities as soon as the mold inserts are available.

The main challenge lies primarily in creating the corresponding mold inserts. There are several ways in which the moth's eye structure can be applied to such mold inserts. One possibility is, for example, the so-called modified PVD process. In this process, wear resistant and high-temperature resistant ceramic hard coatings consisting of titanium aluminum nitride (TiAlN) and titanium oxide (TiOx) are applied to injection molds or dies, which in turn are made from a common tool material. For example, made of steel or steel alloys, applied. By means of a targeted crystal growth and a suitable choice of the deposition parameters, the desired surface topography is generated. Characteristic are the self-organizing columnar surface structures whose individual columns are characterized by pyramidal tips. However, it should be noted that the structures grow statistically distributed due to the process and are therefore arranged stochastically and not periodically on the tool surface or can be. The big advantage of the modified PVD process is that practically any contour or size can be anti-reflective. Furthermore, wear-resistant, high-temperature-resistant hard coatings are used, which have a very long service life. With the tools created in this way, direct-coated optical elements, for example, of polymethyl methacrylate (PMMA), polycarbonate (PC) or other comparable plastics can be injected directly.

Another possibility for generating surface structures in the nanometer range is the so-called holographic exposure of photoresist plates (photoresist plates) with special etching techniques. Exposure and the associated periodic structuring can be achieved by high-performance lasers. These are two coherent laser beams that are brought into interference, producing a periodic sinusoidal intensity modulation. With this pattern, the photosensitive material is exposed. By electroplating the structuring of the photoresist plates is transferred to a nickel-shim structural element. This then represents the so-called master for the injection molding and hot stamping processes. Total reflectivities of one percent can be achieved with this method. However, only flat surfaces having a size of at most 0.5 m ² can be produced by this method. Moreover, it is also possible by means of an anodic process to apply nanoscale surface structures in the nanometer size range from 30 nm to 200 nm on aluminum inserts. The aforementioned methods can be used individually or be used together in the context of the invention for the preparation of the reflection-inhibiting structure interfaces.

In one development of the invention, a vehicle headlight with one or more lighting devices according to the invention can also be specified.

Furthermore, within the scope of the invention, a motor vehicle with at least one vehicle headlight, preferably exactly two vehicle headlights, can be specified, wherein the at least one vehicle headlight is equipped with one or more lighting devices according to the invention.

Further details, features and advantages of the invention will become apparent from the following explanation of exemplary embodiments schematically illustrated in the drawings. In the drawings show:

1 is a plan view of a possible embodiment of a lighting device according to the invention with a light-guiding element and a luminous element, wherein structural boundary surfaces with a moth-eye structure are shown in hatching;

2 is an isometric oblique view from the front of a feed region into a light guide element, wherein a structure interface with a moth eye structure at a light coupling surface at the entrance to the light guide is shown in hatching;

3 shows an isometric oblique view from the side of a light guide in the form of a light stick and a corresponding luminous body.

4 shows a schematic diagram of a surface section with a moth-like structure structure interface and a boundary curve of the structure interface corresponding to the actual surface.

1 illustrates a lighting device 1 according to the invention for a motor vehicle with a lighting module 10 with a plurality of light emission sources 200, which are embodied here as LEDs 200 and mounted on a light emission source support 210. For this purpose, a light-emitting region 220 is arranged on the carrier 210 in such a way that light 100 emitted by it is fed into a light-incoupling surface 310 or light-entry surface 310 of a light-conducting element 300. The emitted light beams 100, which at the same time illustrate the light 100 fed into the light guide element 300, are shown in FIG. 1 as dashed arrows. After passing through the light incoupling surface 310, the fed light 100 in the interior of the light guide element 300 passes through a feed region 320 to inner walls of the light guide element 300, at which the light is known to be totally reflected or redirected 110. After overcoming one corresponding Lichtleitstrecke within the light guide 300, the redirected light 110 reaches a portion of the light guide 300, which is provided with a plurality of deflection prisms 330. At the deflecting prisms 330, the redirected light beams 110 are again deflected and pass through a light outcoupling surface 340 of the light-guiding element 300 into an air gap 600 between the light-guiding element 300 and a luminous element 400. The light-outcoupling surface 340 of the light-guiding element 300 is substantially deflected in each case in an emission direction 120 for this purpose is coupled to at least one light entry surface 410 of the luminous element 400 in the emission direction 120 of the emitted light 120. In other words, the light outcoupling surface 340 of the light-guiding element 300 is arranged or formed in such a way that the light 120 emitted by it strikes at least one light-entry surface 410 of the luminous element 400 in the emission direction 120. The emitted light 120 passes through the light entrance surface 410 of the luminous element 400 into the luminous element 400, is distributed as light absorbed by the luminous element 400 within the luminous element 400 and reemerges at a light exit surface 420 of the luminous element 400 as emitted light 140 therefrom out. The emitted light 140 is thus emitted to the surroundings 600 of the luminous element 400, the light coupling surface 310 and the light outcoupling surface 340 of the light-guiding element 300 and the light entry surface 410 and the light exit surface 420 of the luminous element 400 here each have an antireflective structure boundary surface 500 with a moth-eye structure. The reflection-inhibiting structure boundary surfaces 500 are shown in hatching in FIG. 1.

2 shows in detail a feed region 320 in a light guide element 300, wherein a structure boundary surface 500 with a moth eye structure at a light coupling surface 310 at the entrance to the light guide element 300 is shown in hatching. In the foreground of the image, a light emission source carrier 210 having a plurality of light emission sources 200, which are arranged on a rear side of the carrier 210 facing the light coupling surface 310, is shown.

FIG. 3 shows, in an isometric oblique view from the side, a light-conducting element 300 in the form of a glow stick 350. The glow stick 350 here has a substantially circular cross-section and extends approximately tubularly along a 3D carrier curve 360 of the lightstick 350. At a sectoral longitudinal section of FIG 3D carrier curve 360 of the light bar 350 deflection prisms 330 are provided. An associated three-dimensional luminous body 400 is arranged substantially diametrically opposite to the deflecting prisms 330 spaced from the luminous rod 350 has for this purpose a light entrance surface 410, which is substantially parallel to the 3D carrier curve 360 of the luminous rod 350. On the outside of the luminous element 400 opposite the light entry surface 410, a light exit surface 420 is provided, which is approximately parallel to the light entry surface 410. Either the light entry surface 410, as well as the light exit surface 420 are here equipped with a reflection-inhibiting structure interface 500 with a moth-eye structure. A cover surface 430 of the three-dimensional luminous element 400 is equipped here without an antireflective structure interface 500.

4 shows, in a simplified schematic diagram, a surface section with a structure boundary surface 500 with moth-eye structure and a boundary curve 510 of the structure interface 500 corresponding to the actual contour of the reflection-inhibiting material. The actual material contour of the structure interface 500 is indicated here by dashed lines. The course of the limit curve 510 shown here, which is adapted to the actual material contour, is described approximately by a periodic sequence of valleys 520 as well as of adjacent mountains 530 or can be specified by such a periodic sequence.

LIST OF POSITION NAMES Lighting device

Illuminant module

(in light guide element) fed light (arrow direction)

(in the light guide element) redirected light (arrow direction)

(Light emitted by the light-guiding element) or emission direction (arrow direction) (light absorbed by the luminous element)

(light emitted from the luminous body)

Light emission source, e.g. LEDs

Light emission source carrier

Light emitting area

light guide

Light input surface or light entry surface of the light guide; Interface feed region of the light guide

deflecting prism

Lichtauskoppelfläche or light exit surface of the light guide; Interface glow stick

3D carrier curve of the light stick

3D lamp

Light entry surface in 3D-illuminant; interface

Light exit surface made of 3D luminaire; interface

(upper) top surface of the 3D-illuminant

Structure interface with moth-eye structure; interface

Limit curve of the structure interface

Valleys of the limit curve of the structural interface

Mountains of limit curve of the structural interface

ambient air

Claims

1. Lighting device (1) for a motor vehicle, which lighting device (1) comprises a luminous element module (10) with at least one light emission source (200), with at least one light guide element (300) and at least one luminous element (400), wherein the light guide element ( 300) is adapted to guide light (100) fed from the at least one light emission source (200) through at least one light coupling surface (310) of the light guide element (300) to a light coupling surface (340) of the light guide element (110), as well the light outcoupling surface (340) of the light-guiding element (300) is configured to direct light (120) emitted by the light outcoupling surface (340) in the emission direction (120) to at least one light entry surface (410) of the luminous body (400), the emitted light ( 120) passes through the light entry surface (410) of the luminous body (400) into the luminous body (400) (130) and at least one Lichta exit surface (420) of the luminous element (400) again from this exit (140), characterized in that at least one light input surface (310) and / or light output surface (340) of the at least one light guide element (300) and / or at least one light entry surface (410) and / or light exit surface (420) of the at least one luminous body (400) has or have a reflection-inhibiting structure interface (500).

2. Lighting device (1) according to claim 1, characterized in that the reflection-inhibiting structure interface (500) at least in sections, a periodic moth eye structure (510, 520, 530).

3. Lighting device (1) according to claim 1 or 2, characterized in that the reflection-inhibiting structure interface (500) at least in sections, a stochastic moth eye structure (510).

4. Lighting device (1) according to one of claims 1 to 3, characterized in that the reflection-inhibiting structure interface (500) by microstructured valleys (520) and mountains (530) of a limit curve (510) is approximately specified, with adjacent valleys (520) and mountains (530) are spaced apart on a micrometer scale.

5. Lighting device (1) according to one of claims 1 to 3, characterized in that the reflection-inhibiting structure interface (500) by nanostructured valleys (520) and mountains (530) of a limit curve (510) approximately is assignable with adjacent valleys (520) and mountains (530) spaced from each other on the nanometer scale.

6. Lighting device (1) according to one of claims 1 to 5, characterized in that the light-guiding element (300) and / or the luminous body (400) is made of plastic and the reflection-inhibiting structure boundary surfaces (500) introduced directly into a plastic tool are.

7. Lighting device (1) according to claim 6, characterized in that the reflection-inhibiting structure boundary surfaces (500) in the plastic are model impressions of a plastic tool.

8. Lighting device (1) according to any one of claims 3 to 6, characterized in that the stochastic moth-eye structure (510) of the reflection-inhibiting structure interface (500) is produced by targeted treatment of a polymeric material with an ion plasma.

9. lighting device (1) according to one of claims 1 to 8, characterized in that the light-guiding element (300) in the region of its Lichtauskoppelfläche (340) with deflection prisms (330) is provided, wherein the deflection prisms (330) are adapted to, in the light guide (300) diverting redirected light (110) substantially in the same emission direction (120) from the light outcoupling surface (340).

10. Lighting device (1) according to one of claims 1 to 9, characterized in that the light outcoupling surface (340) of the light-guiding element (300) is arranged at least in sections parallel to the light entry surface (410) of the luminous body (400).

11. Lighting device (1) according to one of claims 1 to 10, characterized in that the light-guiding element (300) is a luminescent rod (350) with an SD support curve (360), wherein the luminescent rod (350) preferably has a circular or oval cross-section having.

12. Lighting device (1) according to one of claims 1 to 11, characterized in that the at least one light entry surface (410) and the at least one light exit surface (420) of the luminous body (400) are arranged substantially parallel to each other.

13. A vehicle headlight with one or more lighting devices (1) according to one of claims 1 to 12.

14. Motor vehicle with at least one vehicle headlight, preferably exactly two vehicle headlights, according to claim 13.