DE102004046256A1 - Surface lighting system for rearward lighting of liquid crystal display, has light conductors for emitting electromagnetic radiation at its front side, and radiation sources positioned such that their optical axes cut each other - Google Patents

Abstract

The system has light conductors (1) for emitting an electromagnetic radiation at its front side, where the conductors have front and rear sides (6, 4). The rear sides are inclined against a lateral injecting surface through which the electromagnetic radiation is irradiated between the front and rear sides. Radiation sources (2) e.g. LEDs, emit the radiation, and are positioned in such a way that their optical axes cut each other.

Description

The The invention relates to a surface lighting system.

For surface lighting systems there are many Applications. You can for example, as bulbs in lamps or design arrangements serve. In particular, surface lighting systems can be used used for backlighting displays such as liquid crystal displays (LCD displays) become.

to Backlighting of displays are usually lighting systems used, which include a continuous light guide, in the side a rod-shaped Light source with an isotropic radiation characteristic, such as e.g. a fluorescent tube, couples. These systems have the disadvantage that the dimensions the light-emitting surface can not be increased arbitrarily can, as otherwise lateral inhomogeneities in the radiation characteristic may occur.

From the pamphlets US 6,646,367 B2 and US 6,241,358 B1 Surface illumination systems are known, which are cascade-shaped of several optical fibers modular, in each of the side light rod-shaped primary light sources with an isotropic radiation characteristic, such as cold cathode lamps, coupled.

Such surface illumination systems often each have high light intensities in the region of the coupling-in region 31 and at the joints between the light guides 1 on, while that of the coupling area 31 remote area of the light guide 1 appears dark, as in 1a shown. In order to achieve a homogeneous radiation characteristic in such surface luminous systems, was in the publications US 6,241,358 B1 and US 6,464,367 B2 proposed a number of measures, such as the arrangement of reflectors 42 on the back side 4 the light guide 1 and the primary light sources 2 around.

task The present invention is a surface lighting system with possible indicate homogenous radiation characteristic, in particular technically is easy to implement and its lighting surface also on technically simple Way can be scaled.

These Task is by a surface lighting system solved according to claim 1.

advantageous embodiments of the surface luminous system are in the subclaims 2 to 19 indicated.

• – mindestens einen Lichtleiter mit einer der Strahlung emittierenden Vorderseite des Oberflächenleuchtsystemszugewandten Lichtleiter-Vorderseite, einer von der Strahlung emittierenden Vorderseite abgewandten Lichtleiter-Rückseite und einer seitlichen Einkoppelfläche, durch die im Betrieb des Oberflächenleuchtsystems elektromagnetische Strahlung zwischen die Lichtleiter-Vorderseite und die Lichtleiter-Rückseite eingestrahlt wird, wobei die Lichtleiter-Rückseite der Einkoppelfläche entgegengeneigt ist,
• – mindestens eine primäre Strahlungsquelle mit definiertem begrenztem Abstrahlwinkel, die geeignet ist, die in den Lichtleiter einzukoppelnde elektromagnetische Strahlung zu emittieren, und
• – mindestens ein streuendes und/oder reflektierendes Element an der Lichtleiter-Rückseite.

An inventive surface luminous system with an electromagnetic radiation emitting front comprises in particular:

• - At least one light guide with a radiation emitting front of the surface illumination system facing the light guide front side facing away from the radiation front side light guide back side and a side coupling surface, irradiated by the operation of the surface lighting system electromagnetic radiation between the optical fiber front side and the optical fiber back is, with the optical fiber rear side of the coupling surface is inclined,
• - At least one primary radiation source with a defined limited radiation angle, which is adapted to emit the electromagnetic radiation to be coupled into the optical waveguide, and
• - At least one scattering and / or reflective element on the light guide back.

The Surface lighting system emits preferentially electromagnetic radiation with wavelengths in the visible area, especially white light. Also emitting the primary Radiation sources prefer electromagnetic radiation with wavelengths in the visible area, especially white light.

When Optical fiber is hereinafter referred to a device that to contributes the electromagnetic radiation of the primary radiation source so too derive that these are largely homogeneous from the front of the Surface lighting system is emitted. As a light guide according to the invention, for example a conventional one Light guide made of an at least partially radiation-transparent material, such as glass or plastic serve. For light distribution can generally any surface the light guide be provided with optically active structures, which may have refractive and / or diffractive character.

Farther For example, the light guide can also comprise a hollow body. its surfaces are structured to light pipe. Under a light guide is still in the broadest sense, also to understand any arrangement of surfaces intended for serve targeted conduction of electromagnetic radiation.

Each optical fiber is powered by a certain number of primary radiation sources with radiation, which is irradiated laterally via the coupling surface in the optical fiber. A light guide, the primary radiation sources whose radiation is coupled laterally into the light guide and one or more scattering and / or reflective elements on the back of the light guide together form a light tile. The surface lighting system may include a light tile or be composed of a plurality of light tiles, which may also have different sizes and geometries, to form a light tile composite. So it is advantageously possible to easily realize surface lighting systems with a variety of sizes and geometries.

Around with primary Radiation sources with defined limited beam angle a luminous tile with Homogeneous radiation characteristics are reflected and / or scattering elements on the optical fiber back arranged and the light guide back shaped so that it is opposite to the coupling surface. The Interaction of these parts for the targeted guidance of the radiation inside a light tile is described below.

The Radiation of the primary Radiation sources is laterally over the coupling surfaces irradiated in the light guide in the form of a limited cone. In this case, the radiation source occupies only a small part of the coupling surface. The light guide is shaped so that its backside the rays of the radiation cone is leaning against, leaving the rays on the back of the light guide, after having some way within the light guide along the light-emitting front covered to have. The stronger the fiber optic back across from the front is inclined, the shorter is the path, the rays in the light guide on average, before they hit the back. Alternatively, by vertical tilting of the primary radiation sources against the front of the surface lighting system, the location can be varied, at the rays on the back of the light guide impinge around the rays from the back of the light guide to the radiation emitting face of the surface luminous system Steer is an element with reflective properties the fiber optic back arranged. Thus also in the area radiation from the front of the Surface lighting system is emitted, the rays due to the defined limited Pass through the radiation angle undisturbed, has the optical element on the back also prefers such scattering properties that in this Area of the light guide radiation is deflected back.

By the use of primary Radiation sources with defined limited radiation angle, it is advantageous in a technically simple way, the course of the radiation within the light tiles as far as possible predict. The scattering and / or reflective elements on the back side the light guide and the slope of the light guide back are chosen that the coupled into a light guide light over the Length of one Light tile largely complete is homogeneously emitted by, so to speak, the light "evenly consumed." On this Way is also usually the largest part of the coupled radiation from the front of the surface lighting system radiated.

at a preferred embodiment is the primary one Radiation source substantially punctiform.

"Essentially punctiform "or" punctiform "means in the frame the invention that the extent of the radiation source with respect to the corresponding Extension of the light guide is that further reduction the dimensions of the radiation source no significant impact on the radiation characteristics of the surface lighting system has. In doubt means "im essential punctiform "or" punctiform "in particular that the largest sectional area of the Light guide, which passes through the radiation cone in the light guide at least half so big preferably ten times bigger, particularly preferably one hundred times as large as the radiation-emitting area the radiation source. As a rule, radiation-emitting semiconductor chips, like light emitting diodes (LEDs) or laser diodes in connection with typical ones Dimensions of a light guide for a surface luminous system, which serves for the backlighting of a display, for example, as punctiform.

The Use punctiform Radiation sources offers the advantage that the optically active elements, the course of the injected into the light guide radiation direct, easy to determine.

In a preferred embodiment of the surface luminous system according to the invention be considered primary Radiation sources light emitting diodes used.

LEDs are components that emit electromagnetic radiation that in an active photon emitting region of a semiconductor chip is produced. Such components are known to the person skilled in the art and are therefore not closer at this point described.

in the Compared to conventional used radiation sources, LEDs are defined by a defined limited beam angle. They also offer a number of benefits such as long life and low energy consumption.

At the front of the light guide is in front a decoupling element is preferably arranged, which decouples the radiation emitted by the front side of the surface illumination system according to a desired characteristic. The decoupling element is preferably permeable to the radiation emitted by the front side of the surface illumination system.

at a preferred embodiment the decoupling element is provided, the radiation in the direction of surface normal the front of the surface lighting system to steer. The radiation is thus substantially perpendicular to the front of the Surface lighting system so that the radiation intensity perceived by an observer or can be measured by a detector dependent on at which position in front of the front of the surface lighting system he is located. The radiation intensity is maximum at one position frontal in front of the surface lighting system. A surface lighting system with this emission characteristic is particularly suitable for backlighting of displays.

at a further preferred embodiment is the decoupling element provided from the front of the Surface luminous system emitted Radiation from each point of the front isotropic in all spatial directions the half-plane bounded by the light-emitting front becomes. The radiation intensity such a surface luminous system, which an observer perceives or measures a detector in front of the surface illumination system is largely independent of its position. One Surface lighting system with such a radiation characteristic is particularly suitable as lighting in design arrangements or luminaires.

Prefers the Auskoppelelement structuring the front of the Include light guide. The decoupling element can be a direct structuring be the light guide front. Furthermore, it can be a direct Structuring the fiber optic front and additional comprise separate elements, such as an optically active film, which is arranged on the front side of the light guide. Such Foil may be, for example, a radiation-transparent film, the prismatic structures on the surface has (prism sheet). The prism-shaped structuring directs on the back incident light in the direction of the surface normal of the radiation emitting front and homogenized so the radiation characteristics the lighting device.

The scattering and / or reflective elements on the light guide back are preferably made of diffuse reflective films. Such slides have the advantage that they are inexpensive, light weight have and can be easily processed.

at a further preferred embodiment of the surface luminous system can that scattering and or reflective element on the light guide back also a direct structuring of the optical fiber back include. The scattering and / or reflective element can be a direct structuring of the light guide back. It can also a direct structuring of the optical fiber backside and additionally separate comprise optically active element. So can the fiber optic back for example, be roughened so that it scatters radiation and at the same time an additional Have reflector that reflects the radiation.

Suitable as scattering and / or reflective structures on the back the light guide is for example a staircase structure. Such a stair structure acts as a directional scattering optics, the radiation towards the front of the light guide directs. Structuring, as directional scattering optics are structurings that are spatial in nature Preferred direction and include elements that incident Scatter radiation.

Prefers is located at the coupling surface of the light guide an optically effective coupling element, the electromagnetic radiation of the primary light source accordingly a desired one Characteristic coupled into the light guide. The coupling element may in a preferred embodiment of the surface luminous system comprise a direct structuring of the coupling surface. It can, for example a direct structuring of the coupling surface, a lens, a lens system, a be diffractive optical element or a combination thereof.

at a preferred embodiment the coupling element is provided, the radiation of the primary radiation sources align parallel to the front of the surface lighting system. The course of parallel rays in light guides and their behavior at the interfaces The light guide can be calculated very easily. This offers the Advantage that the system in terms of a planned radiation characteristic can be optimized more easily.

In general, each surface of the light guide can be provided with optically active structures for targeted light distribution, which may have a refractive and / or diffractive character. In particular, the scattering and / or reflective element at the back of the light guide, the outcoupling element at the light guide front side and the coupling element at the coupling surface must each kei ne separate elements, but can be integrated by appropriate structuring of the respective surface in the light guide. Furthermore, they can also be formed by a combination of a direct structuring of the respective surface with one or more separate elements.

On the surfaces or in the interior of the optical waveguide may also be preferred wavelength conversion material are located. Wavelength conversion materials are substances that are the wavelength of transforming incident light into another. They are for example described in the document WO 98/12757 A1, the disclosure of which insofar hereby by reference is recorded.

Wavelength conversion materials are applied to blue LEDs, for example, to a part the blue primary radiation to turn into yellow light that deals with the remaining blue light mixes and so a white Color impression leaves the viewer. Likewise, wavelength conversion materials be applied to LEDs, the light in the ultraviolet range emit so white or to create mixed-color light.

is wavelength conversion material on the front or inside the light guide, it is not more necessary, the LEDs individually with wavelength conversion material to coat, to light the desired To get color. This offers some advantages from production engineering View.

at Use of wavelength conversion material, that electromagnetic radiation of the ultraviolet range (UV radiation) at least partially In particular, LEDs can be converted into visible light primary Radiation sources are used, the electromagnetic radiation with wavelength emit in the ultraviolet range. For example, hereby Wavelength conversion material be used that part of the UV radiation of the primary radiation sources in yellow light and another part in blue light a surface lighting system to receive, which emits light in operation, the a white color impression leaves the viewer behind.

Next Wavelength conversion materials can be the Fiber optics inside also other optically effective elements like For example, scattering particles or holograms contain, with which also the radiation characteristic of the surface luminous system positively influence.

Prefers are the neighboring areas of the Fiber optic interconnected so that no air gaps between insist on them. This can prevent that eventually existing residual radiation at the end of a light tile due to Refractive index difference between optical fiber material and air increasingly reflected back to the coupling region.

The Light guides can For example, be associated with adhesives or a potting compound. In principle, all joining materials are similar have optical properties such as the optical fiber material.

Prefers includes a surface lighting system at least two primary Radiation sources, which are arranged so that the optical Axes of at least two primary Cut radiation sources. This allows a more homogeneous illumination the light guide and thus a more homogeneous radiation characteristic of the surface luminous system be achieved.

Further advantages and advantageous embodiments of the surface lighting system will become apparent from the following in connection with the 1a . 1b . 2a to 2d . 3a . 3b . 4a to 4c . 5a . 5b . 6a and 6b closer explained embodiments.

It demonstrate:

1a , a diagram of the local brightness distribution I (x) of a not belonging to the invention surface luminous system of two light guides, laterally coupled in each case an isotropic radiation source, wherein a sectional view of the surface luminous system is shown schematically below the x-axis of the diagram

1b , a diagram of the local brightness distribution I (x) of a surface illumination system consisting of two light guides into which radiation sources with a defined limited radiation angle are coupled laterally, wherein a sectional representation of the surface illumination system is shown schematically below the x-axis of the diagram,

2a FIG. 4 is a schematic sectional view of a surface illumination system according to a first embodiment and the rays running inside and at the interfaces of the light tiles. FIG.

2 B , a schematic sectional view of a light tile and course of the rays in the interior and at the interfaces of the light tile,

2c , A schematic sectional view of a not belonging to the invention surface luminous system without optical elements on the Front sides, without reflectors on the backs of the light guides and without gluing of the light guide edges and the rays running inside and at the interfaces of the light tiles,

2d , A schematic sectional view of a surface lighting system analogous to that of 2a , but without gluing the fiber edges and showing the light path inside and at the interfaces of the light guides,

3a , a schematic sectional view of a light tile, according to an embodiment of the invention,

3b , a further schematic sectional view of a light tile according to a further exemplary embodiment of the invention,

4a FIG. 4 is a further schematic sectional view of a light tile, according to a further exemplary embodiment of the invention, FIG.

4b 5 is a further schematic sectional view of a light tile according to a further exemplary embodiment of the invention, and a schematic representation of the light profile in the interior and at the interfaces of the light guide,

4c , An enlarged view of the coupling region of the light tile 4b and representation of the light path within the coupling region,

5a , a schematic sectional view of a lighting system according to another embodiment,

5b , schematic perspective plan view of a surface lighting system according to 5a with a lens bar in front of the light tile, and

6a and 6b , schematic plan views of a light tile according to another embodiment of the invention.

In the embodiments and figures are the same or equivalent components respectively provided with the same reference numerals. The illustrated elements the figures are basically not as true to scale to watch. Rather, you can for a better understanding partially exaggerated shown big be.

In contrast to the prior art (see 1a ) arises in the present invention due to the use of primary radiation sources 2 with defined limited radiation angle the problem that without further action high radiation intensities usually at the end 5 of the light guide 1 occur, the coupling surface 3 opposite (cf. 1b ).

As primary radiation source 2 for example, LEDs are used with a defined limited radiation angle. Due to their dimensions, LEDs are usually punctiform radiation sources 2 , For example, an LED may have a height of 0.6 mm, a width of 0.8 mm, and a length of 1.7 mm. A suitable light guide usually has at least a height that is twice as high as the height of the LED. It should be noted at this point that other components than primary radiation sources 2 can be used for the surface lighting system, which are characterized by a defined limited radiation angle, such as laser diodes, which are usually punctiform radiation sources.

The surface lighting system according to 2a includes several optical fibers 1 with lateral coupling surface 3 into which the primary radiation sources 2 inject. The primary sources of radiation 2 and the light guides 1 are each on individual carriers 9 mounted and form a light tile. These light tiles are on another support 10 arranged in such a light tile composite that front pages 6 essentially the radiation emitting front side 60 of the surface luminous system. Every light guide 1 indicates on its back 4 a scattering and / or reflective element 41 on, such as a foil that diffusely reflects. Such a film may contain, for example, the plastic POCAN. On the front side 60 the Oberflä chenleuchtsystems are one or more optically active films, such as a prism sheet 63 , The edges 7 the light guide 1 are connected so that there are no air gaps between them. This can be z. B. can be achieved by gluing. Alternatively, the light guides 1 for example, be shed.

Like the schematic representation of the rays in 2 B shows, the radiation of the point-shaped primary radiation source 2 due to the defined limited emission angle α in the form of a cone in the light guide 1 coupled. The rays lay inside the light guide 1 some way along the radiation-emitting front 60 of the surface illumination system and, depending on the position within the radiation cone, sooner or later hit the back of the light guide 4 , the coupling surface 3 is inclined towards. The diffuse reflector 41 on the fiber optic back 4 prevents radiation from passing through the back of the light guide 4 On the other hand, due to its diffuse character, it can scatter radiation back towards the coupling region 31 , As a result, light is also in the range of Einkoppelbe Reich 31 from the front 60 of the surface lighting system that would otherwise appear dark.

The optical films on the front 60 of the surface luminous system serve as decoupling elements 62 and also have the task of producing a homogeneous radiation characteristic. In particular, a prism sheet 63 directs the rays at the interface surface light system / air in the direction of the normal of the front 60 of the surface luminous system.

By gluing the fiber optic edges 7 be larger refractive index differences within the areas that the radiation to the front 60 of the surface luminous system must be avoided. This further contributes to a homogeneous radiation characteristic of the surface luminous system.

To illustrate the effect of the diffuse reflectors 41 on the fiber optic backs 4 , the prism sheet 63 on the front of the fiber optic network and the gluing of the fiber optic edges 7 is in 2 B the course of the rays within a surface luminous system shown schematically, these elements compared to the surface luminous system in 2a absence.

Due to the lack of diffuse reflector 41 on the fiber optic back 4 Radiation can escape at these points, which generally reduces the brightness of the surface lighting system. Furthermore, the surface lighting system appears in the vicinity of the coupling areas 31 dark, because no radiation from the diffuse reflector 41 from the fiber optic back 4 again in the direction of coupling area 31 is scattered back.

The absence of the prism sheet 63 on the front of the fiber optic composite, causes the rays to be oblique from the front 60 of the surface luminous system are radiated. This generally reduces the brightness perceived by an observer who is positioned frontally in front of the surface illumination system.

Exist between the fiber optic edges 7 air-filled gaps are due to the refractive index difference between the material of the optical fiber 1 and air rays multiply reflected at this boundary and subsequently from the front 60 in the field of optical fiber edges 7 radiated. As a rule, this leads to bright stripes in the area of the optical fiber edges 7 ,

In 2c is unlike the 2a the bonding of the optical fiber edges 7 , The schematic representation of the beam path therefore shows in this area an increased exit of rays at the front 60 of the surface luminous system.

By a direct structuring of the surfaces 3 . 4 . 6 of the light guide 1 can optically active elements, such as the coupling element 32 , the decoupling element 62 and the diffusing and / or reflecting element 41 also directly into the light guide 1 to get integrated. So is the light guide 1 of the embodiment according to 3a on the coupling surface 3 , on the fiber optic back 4 and on the fiber optic front 6 provided with structuring. The structuring on the coupling surface 3 serves the targeted coupling of radiation into the light guide 1 , the structuring on the back 4 has scattering properties and can be produced for example by roughening the surface and the front 6 is with a coupling optics 62 structured. In addition, at the back of the light guide 4 a reflector 42 arranged.

The fiber optic back 4 can also with directional scattering optics 43 such as a staircase structure 44 be provided (cf. 3b ). The staircase structure can have, for example, dimensions of a few millimeters to a few micrometers. At a slope of the light guide back 4 of 45 ° to the front emitting radiation 6 of the light guide 1 will be on the back 4 of the light guide 1 falling radiation substantially perpendicular to the radiation emitting front 60 directed the surface luminous system.

With a suitable choice of structuring may possibly on an additional reflector 42 be waived.

The volume of the light guide 1 can be essentially formed by a matrix mass, which is responsible for the radiation of the primary radiation sources 2 is largely transparent, such as many plastics or glass. Into the matrix mass can be optical elements 12 Like holograms or scattering particles embedded, which also has the radiation distribution within the light guide 1 targeted influence.

The light guides 1 may continue to be in the interior or on the surfaces of wavelength conversion material 11 wear, so that the radiation of the primary radiation sources 2 is at least partially converted into radiation of a different wavelength. In this way, the color impression of the light emitted by the surface lighting system can be varied.

The shape of the fiber optic backs 4 influences the beam path within the light guide 1 and thus the overall radiation characteristics of the surface illumination system substantially, since it depends on which path the rays within the light guide 1 along the front 60 put back and where they on the light guide back 4 incident.

Furthermore, the shape of the light guide surface is also 8th that the coupling surface 3 with the front 6 connects, decisive for the course of the rays within the light guide 1 and thus for the radiation characteristic of the surface luminous system.

To optimize the radiation characteristics of the surface lighting system, therefore, the choice of suitable geometries of the optical fiber back 4 and the interface 8th of the light guide 1 between coupling surface 3 and front side 6 essential, as the embodiment according to 4a shows where these surfaces 4 . 8th , each can be in the dashed area. The fiber optic back 4 and the interface 8th between coupling surface 3 and fiber optic front 6 may also be concave or convex. The exact shape of these optical fiber surfaces depends on several parameters, such as the aperture angle α and the area of the primary radiation sources, as well as the optical fiber material. If such parameters are known, the shape of the light guide surfaces can usually be calculated.

For aligning the rays within the light guide 1 in the direction of the radiation emitting front side 60 of the surface lighting system may be the optical fiber back 4 also a stair structure 44 include, as in the embodiment according to the 4b and 4c ,

In the embodiment according to the 5a and 5b becomes the light-emitting front 60 the surface lighting system essentially by a cover 61 formed, under the, preferably curved, reflectors 42 are arranged, which is the function of the light guide back 4 and the scattering and / or reflective elements 41 at the light guide back 4 meet according to the embodiments described above. Side of the reflectors 42 there is a "virtual" coupling surface 3 over which the primary radiation sources 2 in the coupling area 31 couple in the light tile. For parallelization of the beams in this embodiment is a coupling elements 32 such as B. a lens or a lens system between the coupling surface 3 and the primary radiation source 2 arranged. The reflectors 42 are shaped so that the parallel rays of them are substantially perpendicular to the light-emitting front 60 of the surface luminous system.

The primary sources of radiation 2 can also be in rows in front of the coupling surface 3 of the light guide 1 be arranged, being between the primary radiation sources 2 and the coupling surface 3 a lens bar as a coupling element 32 is positioned.

Another embodiment of the surface lighting system is shown in FIGS 6a and 6b shown. Here are the Einkoppelbereiche 31 the light guide 1 shaped so that the primary radiation sources 2 within a plane parallel to the front 60 of the surface lighting system obliquely to each other in the light guide 1 couple, so that the optical axes of the primary radiation sources 2 to cut. In particular, the primary radiation sources 2 be positioned in this embodiment, that the radiation cone of different primary radiation sources 2 overlap in as large a range as possible.

The primary sources of radiation 2 are for example on a flexible circuit board 13 mounted, which can be bent and thus easy mounting of the primary light sources at the obliquely shaped coupling areas 31 allows.

Of the completeness It should be noted, of course, that the invention does not apply, of course the embodiments limited is, but that all embodiments fall within the scope of the invention, whose generally Part explained fundamental Principle is based. At the same time it should be noted that the different elements of the different embodiments can be combined with each other.

Claims (19)

Surface lighting system, with an electromagnetic radiation emitting front side ( 60 ), which includes: - at least one optical fiber ( 1 ) with a radiation emitting front side ( 60 ) of the surface illumination system facing the light guide front side ( 6 ), a front emitting radiation ( 60 ) facing away from the light guide back ( 4 ) and a lateral coupling surface ( 3 ), by which during operation of the surface lighting system electromagnetic radiation between the optical fiber front side ( 6 ) and the optical fiber back ( 4 ) is irradiated, wherein the optical fiber back ( 4 ) of the coupling surface ( 3 ), - at least one primary radiation source ( 2 ) with a defined limited angle of radiation, which is suitable in the light guide ( 1 ) to emit electromagnetic radiation to be coupled in, and - at least one scattering and / or reflecting of the element ( 41 ) at the back of the light guide ( 4 ). Surface lighting system according to claim 1, wherein the primary radiation source substantially punctual is. Surface luminous system according to one of the preceding claims, in which the primary radiation source ( 2 ) comprises at least one LED. Surface luminous system according to one of the above claims, with at least one decoupling element ( 62 ) on the front side ( 6 ) of the light guide ( 1 ), which is the one from the front ( 6 ) of the surface luminous system emits radiation corresponding to a desired characteristic. Surface luminous system according to Claim 4, in which the decoupling element ( 62 ), from the front ( 60 ) of the surface illumination system emitted in the direction of the surface normal of the front ( 60 ) of the surface lighting system. Surface luminous system according to Claim 4, in which the decoupling element ( 62 ) provided by the front ( 60 ) of the surface luminous system emitted radiation from each point of the front ( 60 ) isotropic in all spatial directions of the half-plane, which differs from the light-emitting front ( 60 ) is limited, decouple. Surface lighting system according to one of claims 4 to 6, wherein the decoupling element ( 62 ) a structuring of the front side ( 6 ) of the light guide ( 1 ). Surface lighting system according to one of claims 4 to 7, wherein the decoupling element ( 62 ) a radiation-transparent film ( 63 ) having prismatic structures on the surface. Surface lighting system according to one of the preceding claims, in which the scattering and / or reflecting element ( 41 ) on the back side ( 4 ) of the light guide ( 1 ) comprises a diffusely reflecting film. Surface lighting system according to one of the preceding claims, in which the scattering and / or reflecting element ( 41 ) a structuring ( 14 ) the back ( 4 ) of the light conductor ( 1 ) which scatters and / or reflects incident radiation. Surface luminous system according to Claim 9, in which the structuring comprises a staircase structure ( 44 ). Surface luminous system according to one of the above claims, having an optically active coupling element ( 32 ) at the coupling surface ( 3 ) of the light guide ( 1 ), the electromagnetic radiation corresponding to a desired characteristic in the light guide ( 1 ). Surface lighting system according to claim 12, wherein the coupling element ( 32 ) a structuring of the coupling surface ( 3 ) of the light guide ( 1 ). Surface lighting system according to one of claims 12 or 13, wherein the coupling element ( 32 ), the radiation of the primary radiation source ( 2 ) parallel to the front ( 60 ) of the surface lighting system. Surface lighting system according to one of the preceding claims, in which at least parts of the surface of the light guide ( 1 ) Wavelength conversion material ( 11 ). Surface lighting system according to one of the preceding claims, in which the interior of the light guide ( 1 ) optically active elements ( 12 ). Surface luminescent system according to Claim 16, in which the optically active elements ( 12 ) Scattering particles, holograms and / or wavelength-converting phosphor particles ( 11 ) are. Surface luminous system according to one of the above claims, comprising at least two light guides ( 1 ), with each other at the edges ( 7 ) are connected so that there are no air gaps between them. Surface luminous system according to one of the preceding claims, comprising at least two primary radiation sources ( 2 ) positioned so that their optical axes intersect.