DE102010042619A1 - Lighting device for surface light emission - Google Patents

Abstract

The invention relates to a lighting device (1) with a flat light emission characteristic, comprising a flat light guide (2) with at least one light input surface and with at least one light output surface (3) and a light source (7) emitting with a first spectral characteristic, the light source (7) is arranged in relation to the light guide (2) in such a way that light emitted from the light source (7) can be coupled into the light guide (2) via the light coupling surface. The light guide has a light conversion substance which can be excited by the light from the first light source to emit secondary radiation (2).

Description

The present invention relates to a lighting device with light guide for surface light emission.

From the US 20080151554A1 a device of this type is known, which has a light-conducting body with coupling-out points for coupling the radiation from the light-conducting body, wherein the coupling-out points are applied to a voltage applied to the surface of the light guide film. The decoupling sites may further include dyes to achieve a desired color spectrum of the emitted light.

Furthermore, in the published patent application DE 10336352 A1 a light guide and a method for producing scattered light structures on flat optical fibers described. In the scattered light structures, which are applied directly to the light guide in a non-impact method, light for visualization of the scattered light structures can be coupled.

It is an object of the present invention to provide a simple to manufacture light emitting device for surface light emission with high efficiency and increased reliability and with the possibility of color mixing.

This object is achieved by a light guide according to claim 1.

Advantageous embodiments of a lighting device are the subject of the dependent claims.

According to one of the first variant of the invention, a light emitting device for surface light emission on a planar light guide with light conversion material and at least one light output surface and a light emitted with a first spectral characteristic light source, wherein the light source is arranged with respect to the light guide such that the from Light emitted light can enter the light guide and can stimulate the light conversion material to emission of secondary radiation. In this case, the light emerging from the optical waveguide through the decoupling surface exhibits a different spectral characteristic compared to the light coupled into the optical waveguide and can be perceived as substantially planar illumination.

A flat light emission or areal light emission characteristic is present in particular when the light emission surface is large in relation to the surface of the light sources, in particular more than 10 times larger.

The resulting light emerging from the light guide can be influenced by the appropriate choice of the light source, the conversion substance and the geometric arrangement such that a desired spatial-spectral light distribution is achieved.

According to a preferred embodiment of the invention, an LED is used as the light source. Due to their compactness and high efficiency, LEDs are particularly well suited for compact or flat constructions with low height.

In one embodiment of the invention, the light source is a blue or white light emitting LED, in particular based on a III-V semiconductor. These LEDs are characterized by high efficiency and by the short-wave radiation they are able to excite various luminescent substances. In this way, the conversion substance of the light guide can be easily brought to excitation and subsequent emission of the secondary radiation.

In an advantageous embodiment of the invention, a UV LED is used as the light source. This has the advantage that the primary radiation is imperceptible to the human eye, whereby a particularly homogeneous illumination in the visible spectrum can be achieved.

In an advantageous embodiment of the invention, the light conversion substance is spatially distributed within the light guide. On the one hand results in a spatial illumination of the light guide and on the other hand, the light conversion material is better protected against external mechanical and / or chemical influences.

In a further embodiment of the lighting device according to the invention, the light conversion substance is applied flat on the light output surface. Thereby, the distance between the light conversion material and the light source can be increased, which can lead to a reduction of the possible caused by the light source degradation of the light conversion material and thus to an increase in the life of the lighting device. Due to the flat application of the light conversion substance on the outer surface also the characteristics of the lighting device can be subsequently influenced. This can be done particularly advantageously by means of screen printing, since this represents a simple and cost-effective method in which areas can also be selectively coated or released.

Furthermore, a lighting device in which the optical waveguide has a decoupling structure on the light output surface is preferred. This allows the Homogeneity of the lighting and the efficiency of the light extraction can be increased. The decoupling structure can be advantageously applied by screen printing.

In particular, a lighting device in which the optical waveguide has embedded scattering centers is preferred. As a result, the homogeneity of the lighting can be further increased and the spatial lighting can be favorably influenced.

In an advantageous embodiment, the color location of the light emitted by the light conversion material in the CIE color diagram is within a quadrilateral defined by the coordinates (0.42, 0.42), (0.512, 0.487), (0.416, 0.583), and (0.36 0.48) in particular by the coordinates (0.425, 0.44), (0.512, 0.487), (0.416, 0.583) and (0.38, 0.48) is spanned. In combination with a blue LED, this results in an advantageous spectrum expansion of the light emerging from the light guide, so that it can be perceived as a substantially white light.

In a particularly advantageous embodiment, the lighting device has a further light source emitting in the red spectral range. As a result, for example, the color temperature and the color rendering index of the resulting white light can be favorably influenced. With the increase of the red portion in the white light, the color temperature of the white light is generally lowered, which is often perceived by the human eye as pleasant. In addition, this affects the color rendering in such a way that the corresponding red color can appear better in the objects illuminated with this light.

It may also be advantageous if the conversion substance is arranged so that the light of at least two LEDs of the same type, in particular blue LEDs, is converted in different proportions. In particular, the light of at least one of these LEDs can be almost not converted. This makes it possible to increase the proportion of light in the unconverted light, that is, to set a colder light color, for example, by means of an increased blue component. The slight differences between individual LEDs of the same type, which are attempted to be reduced by so-called binning, have a smaller effect in such an embodiment.

With suitable electrical control / regulation of the LEDs, it is thus possible to set both brightness and color temperature and the color rendering index of the light emitted by the lighting device.

In a preferred embodiment, the side surface of the light guide is designed as a light coupling surface, which allows a particularly low overall height of the lighting device. Alternatively or additionally, the lower surface of the light guide opposite the light output surface may be formed as a light input surface. This arrangement is particularly advantageous if you want to achieve higher luminance in large-area lighting devices.

In a further embodiment, the light guide has at least one recess for receiving the light source on the light coupling surface. As a result, it is possible to achieve a reduction in the light scattered in the space outside the light guide and an improved light coupling into the light guide.

Alternatively or additionally, the lighting device may have at least one light source embedded in the light guide, which may be particularly advantageous for the coupling of the light emitted from the light source into the light guide. As a result, an air gap in the optical interface between the light source and the light guide is avoided, which can lead to improved light coupling into the light guide.

In particular, it is advantageous if the light source is embedded in the light guide by means of an embedding compound. As a result, the coupling of the light emitted from the light source into the light guide is further improved. Particularly advantageous is the refractive index of the investment chosen so that total reflection is avoided at the interfaces of light source and investment material and investment and light guide. For this purpose, the refractive indices n _{E of} the embedding compound, n _{Q of} the light source and n _{L of} the optical waveguide are selected such that n _Q ≦ n _E ≦ n _L. It may also be advantageous if the investment contains at least one conversion substance.

Advantageously, the lighting device has a conversion zone with an increased concentration of the light conversion substance. This zone with increased concentration of the light conversion substance can lead to an increased selective light conversion of the light emitted from this LED in the vicinity of an LED, whereby the luminous properties of the lighting device can additionally be advantageously influenced. For example, when using multiple LEDs as light sources, such zones with increased phosphor concentration may be provided near LEDs with shorter emission wavelengths, which may result in increased selective light conversion of the light emitted from these LEDs, while that from the LEDs with longer emission wavelengths (eg In the case of a red LED) emitted light can propagate largely unhindered in the light guide.

It may also be advantageously provided a preferably linear concentration gradient of the conversion substance as a function of the distance from the light source to be converted, so that in the vicinity of the light source, a higher proportion of the light emanating from the source is converted than at some distance. As a result, the radiation behavior of the lighting device can be advantageously influenced. Particularly advantageous is an embodiment in which the concentration of the scattering centers in dependence on the distance from the light sources, in particular from the light sources whose light is at least partially converted by means of the conversion substance, increases. Particularly in the case of conversion substance, which is present in the form of conversion particles and thus likewise causes light scattering, a particularly homogeneous light distribution is achieved.

In a further embodiment of the invention, the lighting device additionally has at least one optical element which is provided for influencing the emission characteristic of the lighting device. As an optical element, for example, an at least partially embedded in the optical fiber optical element can be provided. Furthermore, the optical element may be formed as an at least partially transparent, as a light-transmissive or as an opaque optical element and / or have light-diffractive and / or refractive properties. With suitable positioning or dimensioning of the optical element with respect to the LED, a glare of the LED or a further homogenization of the radiation can be achieved.

The invention will be described below with reference to the drawings.

1 shows a schematic cross section through a first embodiment of a lighting device according to the invention,

2 shows a schematic cross section through a second embodiment of a lighting device according to the invention with additional coupling-out structures,

3 shows a schematic cross section through a third embodiment of a lighting device according to the invention,

4 shows a schematic cross section through a fourth embodiment of a lighting device according to the invention,

5 shows a schematic cross section through a fifth embodiment of a lighting device according to the invention,

6 shows a schematic cross section through a sixth embodiment of a lighting device according to the invention,

7 shows a schematic cross section through a seventh embodiment of a lighting device according to the invention,

8th shows a schematic cross section through an eighth embodiment of a lighting device according to the invention,

9 shows a schematic cross section through a ninth embodiment of a lighting device according to the invention with side light coupling,

10 shows a schematic cross section in the plane of the light guide by the embodiment of the invention having the lighting device according to 9 ,

11 shows an embodiment of the invention with coupling-out structures 9 gem. 2 in plan view.

12 shows a schematic cross section through a further embodiment of a lighting device according to the invention,

13 shows a schematic sectional view of the concentration distribution of scattering centers and conversion substance for a further embodiment of the invention,

14 shows a cross section through a further lighting device according to the invention, which analogous to that in 7 illustrated example is formed in the form of a planar light guide.

1 shows a cross section through a lighting device according to the invention 1 , in the form of a planar light guide 2 is formed and the an upper surface 3 , a side surface 4 and a lower surface 5 having. The planar light guide 2 is with its bottom surface 5 on a base plate 8th appropriate. Furthermore, the light guide 2 on the lower surface 5 recesses 6 for receiving LEDs 7 on where the on the base plate 8th attached LEDs 7 protrude.

The light guide 2 expediently contains a permeable to the optical radiation material. In particular, the light guide contains 2 Glass or a plastic material such as polymethyl methacrylate (PMMA) or polycarbonate (PC). Optionally, the optical fiber may consist essentially of one of these materials.

The light guide 2 has in its interior a light conversion substance, which with that from the LEDs 7 emitted light can interact. In this example, the conversion substance in the form of small particles is largely uniform in the total volume of the light guide 2 distributed. This interaction can lead to scattering, to absorption as well as to a secondary emission, so that spatially distributed illumination of the light guide can occur. The light inside the light guide can pass over the top surface 3 from the light guide 2 escape.

As the light conversion material, one or more suitable luminescent materials may be used, especially orthosilicates (such as Sr 2 SiO 4 (Eu 2+)), garnets (such as yttrium aluminum garnet activated with CeY 3 (Al, Si) 5 O 12 (Ce 3+) ), Nitrides (such as Ba2Si5N8 (Eu2 +)) or oxynitrides (such as SrSi2O2N2 (Eu2 +)).

The base plate 8th can on the side facing the optical fiber housed or unhoused LED and driver circuits for operating the LED have. Furthermore, the base plate may be formed as a printed circuit board (PCB) or metal core PCB (MCPCB), which is responsible for the heat dissipation from the LED 7 or may be particularly advantageous from the driver circuit. Optionally, an adhesion layer between the base plate 8th and the light guide 2 be provided. The base plate 8th may comprise a base body made of a translucent material to illuminate through the base plate 8th through. Optionally, the base plate may have a side or bottom mirroring and / or a highly reflective layer on the side facing the light guide.

2 shows a lighting device like 1 , but with additional coupling-out structures 9 on the upper surface 3 are attached. Also in this example, the light guide 2 in its interior a light conversion substance, which in the form of small particles largely uniformly in the total volume of the light guide 2 is distributed.

The coupling-out structures 9 can be considered as unevenness of the top surface of the light guide 3 be formed in the form of notches or dimples or elevations. Alternatively or additionally, the coupling-out structures 9 from the outside to the light guide 2 be applied, for example by screen printing. The coupling-out structures can lead to improved light extraction by suppression of the total internal reflection at the light output surface. 3 shows a lighting device 1 as 1 , but with additional optical elements 10 that are inside the light guide 2 are embedded.

As an optical element 10 For example, an opaque or wholly or partially translucent shutter sized and positioned with respect to the LED may be used such that non-uniform, such as blotching, of the lighting device 1 , due to the spatially discrete distribution of the LEDs 7 , can be avoided or reduced.

Alternatively, the optical element 10 in the form of a lens, preferably in the form of a scattering lens, be formed.

The lateral dimension D of the optical element 10 is preferably larger than the lateral dimension d of the recess 6 and less than half the distance L between two adjacent LEDs 7 , d <D <L, in particular (d + h) <D <L / 2, where h is the depth of the recess 6 represents.

4 shows the lighting device 1 with the coupling-out structures 9 according to 2 , as well as with optical elements 10 according to 3 , The size or the area density of the coupling-out structures 9 can be selected and adapted to the arrangement of the LED 7 and the optical elements 10 be adapted so that a particularly uniform luminance distribution is achieved on the light output surface of the lighting device. In this case, the area density of the coupling-out structures can have a spatial correlation with the LED arrangement. For example, the density of the coupling-out structures near an LED may decrease and increase away from the LED. Thus, for example, in the areas between the LEDs 7 the luminous intensity of the light guide 2 increase.

5 shows a lighting device 1 according to 1 with additional in the light guide 2 embedded scattering centers 11 ,

The scattering centers 11 may be in the form of scattering particles and / or bubbles, wherein the size of the particles or bubbles and their spatial distribution can be chosen differently from case to case.

The size of the particles or bubbles may be less than or equal to 1 mm in the range. Alternatively and / or additionally, nano-particles can be used as scattering centers. The size of nano-particles is preferably less than 100 nm. As a result, the wavelength dependency of the light scattering (for example by Rayleigh scattering) can advantageously be exploited. Because the short-wave blue or UV radiation undergoes a stronger scattering than the radiation with longer wavelengths, in particular the secondary radiation emitted by the light conversion substance or the long-wave radiation emitted from a red LED. This will be the short-wave blue or UV radiation in the interior of the light guide scattered stronger, thus this radiation can better contribute to the uniform excitation of the conversion substance.

Advantageously, the scattering centers are distributed differently depending on the LED arrangement. The density of the scattering centers may range between 400 and 40,000 particles per cubic centimeter, more preferably between 500 and 5000 particles per cubic centimeter.

6 shows an embodiment of the lighting device according to the invention 1 with the upper layer 12 , The upper layer 12 may be in the form of a thermomechanically coated translucent sheet. Advantageously, the upper layer 12 a smooth surface on. The upper layer 12 Can be used as a protective layer to protect the top surface 3 of the light guide 2 be formed before external influences. Alternatively or additionally, the upper layer 12 be formed as a nano- or microstructures having optical film to direct the exiting light in a desired manner. Thus, these nano- or microstructures in the form of linear asymmetric prisms can serve for anisotropic radiation, which can be advantageous in concrete applications, for example as a glare control measure. Generally, the layer 12 be constructed of individual layer components, so for example a microstructured optical film and a protective layer.

7 shows an embodiment of the lighting device according to the invention 1 with a conversion layer 13 , The conversion layer 13 has light conversion material and is used for conversion of the LED 7 emitted light. The conversion layer 13 is located inside the light guide. It can be a part of the light guide 2 be or be formed as a separate layer within a sandwich structure. Alternatively or additionally, the conversion layer 13 on the upper surface 3 of the light guide 2 lie and thus an outer surface of the lighting device 1 form.

The solid conversion layer 13 , like in the 7 shown, is particularly advantageous when using UV LEDs as the light source 7 be used and leakage of harmful UV radiation should be avoided. The conversion layer can also be applied by means of screen printing, for example.

8th shows a cross section through a lighting device according to the invention 1 in which the light conversion substance is in conversion zones 14 is localized. In this embodiment, the conversion zones are 14 only near certain LEDs 7a arranged. Advantageously, the conversion zones are located 17 near shortwave radiation emitting LEDs 7a while the light of longer wavelength (red) LEDs 7b directly - ie unhindered - in the light guide 2 can get. As a result, a particularly efficient mixed light source can be realized.

9 shows a cross section through a lighting device according to the invention 1 with lateral light coupling. The lighting device 1 points to the opposite sides of the light guide 2 two side plates 15 with LEDs 7 on.

The side plates 15 may have on the sides facing the light guide housed or unhoused LED and driver circuits for operating the LED. Further, the side plates may be formed as Printed Cicuit Board (PCB) or Metal Core PCB (MCPCB), which is for the heat dissipation of the LED 7 or may be particularly advantageous from a driver circuit. Optionally, an adhesion layer between the side plate 15 and the light guide 2 be provided.

The on the side plates 15 arranged LEDs 7 protrude into the recesses 6 in the light guide 2 into it.

In this embodiment, both the upper surface 3 of the light guide 2 as well as the lower surface 5 of the light guide 2 serve as Lichtauskoppelflächen.

10 shows a cross section in plan view through the lighting device 1 gem. 9 , Dashed are schematic equi-concentration lines 16 the scattering centers shown. Scattering particles, which serve here as scattering centers, are in the 10 Not shown. Äquikonzentrationslinien 16 indicate areas of equal concentration of the scattering centers and thus illustrate a deviation from a homogeneous distribution of the scattering centers.

As scattering centers also bubbles or local refractive index fluctuations, caused by local structural modification of the optical fiber material serve. Such refractive index fluctuations can be caused, for example, by local heating of the light guide by means of a focused laser beam.

This inhomogeneity in the spatial distribution of scattering centers has a correlation with or a dependence on the LED arrangement, wherein this dependence in the edge regions of the light guide 2 is more pronounced and away from the edge regions toward the central region of the light guide 2 decreases. In particular, up to a distance L '<L from the side surface of the light guide, this correlation can be seen.

11 shows an embodiment of the invention with coupling-out structures 9 gem. 2 in plan view.

The coupling-out structures 9 in this example are not uniform on the entire surface of the light guide 2 but have a correlation with the spatial arrangement of LEDs 7 on. So are in the edge areas of the light guide 2 , especially near LEDs 7 , Areas without decoupling structures recognizable. Compared to the middle area of the light guide 2 These areas can be less dense or weaker decoupling structures 9 exhibit. With increasing distance from the side wall 4 towards the center of the light guide 2 the coupling-out structures become more homogeneous in their distribution. In this case, the surface density of the coupling-out structures 9 increase.

12 shows a cross section through a lighting device according to the invention 1 , in analogy to 8th the light conversion substance in conversion zones 14 is localized. Also in this embodiment, the conversion zones 14 only in the vicinity of certain (ie surrounded by conversion) LEDS 7a arranged. Advantageously, the conversion zones are located 17 near shortwave radiation emitting LEDs 7c while the light of longer wavelength (red) LEDs 7b directly - ie unhindered - in the light guide 2 can get. In addition, some of the shortwave radiation emitting LEDs 7d not surrounded by conversion substance, so that unimpeded radiation can take place. The shortwave radiation emitting LEDs 7c are all of the same type, regardless of whether they are LEDs surrounded by conversion material 7a or LEDs not surrounded by conversion substance 7d are. In what number or in what ratio the different LEDs are used, depends on the desired color temperature. Are the different LEDs 7a . 7b . 7d can be controlled separately from each other, the color and / or the color temperature of the lighting device can be adjusted particularly well.

13 shows in a schematic sectional view of the concentration distribution c _S of scattering centers and c _K of conversion substance over the path s for a further embodiment of the invention. In the region of an LED, whose light is at least partially converted, the concentration c _K of conversion substance, which also acts as a light scattering, has its maximum and decreases to a minimum, which lies between two LEDs, linearly. Conversely, the concentration of scattering centers in the area of the LED has its minimum and reaches the maximum in between. As a result, a particularly effective decoupling of light is achieved, since the scattering effect of the conversion substance is exploited, thus saving scattering centers and / or light losses can be avoided. Of the linear courses of the concentrations c _S and c _{K shown,} it is of course possible to deviate for both one and both components as a function of the light distribution requirements. In particular, the maxima and / or minima of the concentrations c _S and c _k can also be chosen to be different. The position of the minima and / or maxima does not necessarily have to be chosen exactly between the LED or with the LED.

14 shows a cross section through a further lighting device according to the invention 1 analogous to that in 7 illustrated example in the form of a planar light guide 2 is formed and the an upper surface 3 , a side surface 4 and a lower surface 5 having. The planar light guide 2 points to the bottom surface 5 recesses 6 for receiving LEDs 7 on. In contrast to the previous embodiments, here are the LEDs 7 but directly in the light guide 8th by means of an embedding compound 18 embedded. As a result, the coupling of the light emitted from the light source into the light guide 2 further improved and it can be on the base plate 8th be waived. The refractive index n _{E of} the investment 18 is chosen so that total reflection at the interfaces of LED 7 and investment material 18 as well as investment material 18 and light guides 2 is avoided, ie the refractive indices n _{E of} the investment 18 , n _{Q of} the LED and n _{L of} the optical fiber 2 are chosen such that: n _Q ≤ n _E ≤ n _L.

The light guide 2 expediently contains a permeable to the optical radiation material. In particular, the light guide contains 2 Glass or a plastic material such as polymethyl methacrylate (PMMA) or polycarbonate (PC). Optionally, the optical fiber may consist essentially of one of these materials. Due to the lack of base plate for heat dissipation is here in particular a thermally highly conductive material, ie with a thermal conductivity of more than 1 W / mK, in particular more than 20 W / mK, for example based on quartz glass or Al ₂ O ₃ , provided. Also the investment 18 should have good thermal conductivity.

The conversion layer 13 has light conversion material and is used for conversion of the LED 7 emitted light. The conversion layer 13 is located inside the light guide. It can be a part of the light guide 2 be or be formed as a separate layer within a sandwich structure. Alternatively or additionally, the conversion layer 13 on the upper surface 3 of the light guide 2 lie and thus an outer surface of the lighting device 1 form. Also the investment 18 may contain a conversion substance. Again, the conversion layer can 13 be applied by screen printing, as generally in the context of the invention, both conversion and scattering layers can be advantageously applied by means of this method.

The invention is not limited by the description with reference to the embodiments. Rather, the invention encompasses any novel feature as well as any combination of features, including in particular any combination of features in the claims, even if that feature or combination itself is not explicitly stated in the claims or embodiments.

LIST OF REFERENCE NUMBERS

1

lighting device

2

optical fiber

3

Upper surface of the light guide

4

Side surface of the light guide

5

Lower surface of the light guide

6

recess

7

LED

7a

surrounded by conversion material LED

7b

longer wavelength LED

7c

shortwave radiation emitting LED

7d

LED not surrounded by conversion substance

8th

baseplate

9

Auskoppelstuktur

10

Optical elements

11

scattering centers

12

Upper layer

13

conversion layer

14

conversion zone

15

side plate

16

Äquikonzentrationslinien

17

Red LED

18

investment

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

• US 20080151554 A1 [0002]
• DE 10336352 A1 [0003]

Claims (15)

Lighting device ( 1 ) having a two-dimensional light emission characteristic, comprising a planar light guide ( 2 ) having at least one light input surface and at least one light output surface ( 3 ) as well as a light source emitting with a first spectral characteristic ( 7 ), the light source ( 7 ) with respect to the light guide ( 2 ) is arranged such that from the light source ( 7 ) emitted light in the light guide ( 2 ) via the light incoupling surface, characterized in that the optical waveguide has a light conversion substance which can be excited by the light of the first light source to emit a secondary radiation ( 2 ). Lighting device ( 1 ) according to claim 1, characterized in that the light source ( 7 ) as an LED light source ( 7 ) is trained. Lighting device ( 1 ) according to claim 2, characterized in that the light source ( 7 ) as a blue, white or UV emitting LED light source ( 7 ) is trained. Lighting device ( 1 ) according to claims 1 or 2, characterized in that the light conversion substance on the light output surface ( 3 ) of the light guide ( 2 ) is applied and / or spatially distributed in the interior. Lighting device ( 1 ) according to one of the preceding claims, characterized in that the light guide ( 2 ) a decoupling structure ( 9 ) on the light output surface ( 8th ) having. Lighting device ( 1 ) according to one of the preceding claims, characterized in that the light guide ( 2 ) has embedded scattering centers. Lighting device ( 1 ) according to one of the preceding claims, characterized in that the color location of the light emitted by the light conversion substance in the CIS color diagram lies within a quadrilateral represented by the coordinates (0.42, 0.42), (0.512, 0.487), (0.416; 0.583) and (0.36; 0.48). Lighting device ( 1 ) according to one of the preceding claims, characterized in that the lighting device ( 1 ) another, in the red spectral range emitting light source ( 17 ) having. Lighting device ( 1 ) according to one of the preceding claims, characterized in that the side surface ( 4 ) and / or the light outcoupling surface opposite lower surface ( 5 ) of the light guide ( 2 ) serve as light input surface. Lighting device ( 1 ) according to one of the preceding claims, characterized in that the light guide ( 2 ) at least one recess ( 6 ) on the light input surface ( 6 ) for receiving one of the light sources ( 7 . 17 ) having. Lighting device ( 1 ) according to one of the preceding claims, characterized in that the light source ( 7 ) in the optical fiber ( 2 ) is embedded. Lighting device ( 1 ) according to one of the preceding claims, characterized in that the light guide ( 2 ) a conversion zone ( 13 ) having increased concentration of the light conversion substance. Lighting device ( 1 ) according to one of the preceding claims, characterized in that the conversion zone ( 13 ) is located near a blue LED or a UV LED. Lighting device ( 1 ) according to one of the preceding claims, characterized in that the equi-concentration lines of the scattering particles ( 11 ) and / or the coupling-out structures ( 9 ) a spatial correlation with the arrangement of the LED ( 7 ) exhibit. Lighting device ( 1 ) according to one of the preceding claims, characterized in that at least one optical element ( 10 ) is provided for influencing the emission characteristic.

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