Abstract:
The invention relates to an arrangement for light emission, comprising at least one LED illuminant in a long arrangement, a carrier element carrying the LED illuminant, and a light emitting element that can be connected to the carrier element. The light emitting element comprises a first region ( 41 ) wherein traversing light is extensively scattered. It also comprises a second region ( 40 ) wherein traversing light is scattered significantly less than in the first region.

Description:
The subject matter of the application is an arrangement for light-emission having LED illuminants in an elongate arrangement, a carrier element which carries the LED illuminants, and a light-radiating element which can be connected to the carrier element. Further subject matter of the application is a luminaire. 
     BACKGROUND OF THE INVENTION 
     The optical capacity of LED light sources has undergone a development, making their use appear of interest for general lighting purposes. LED light sources are distinguished by their efficiency and, whilst provided the operating conditions are observed, by particular reliability. Their light-radiation characteristic as well as the operating conditions to be observed do, however, basically differ from conventional illuminants, such as, for example, incandescent bulbs, fluorescent tubes or gas-discharge lamps, so that it appears that existing luminaire constructions can only be retrofitted at considerable expense. LED light sources in this connection radiate very directed, punctiform light. This opens up additional areas of application when compared with conventional illuminants. 
     SUMMARY OF THE INVENTION 
     An object of the present invention is to provide an arrangement for light-emission which optimizes the outlay on retrofitting existing luminaire constructions and at the same time renders possible great flexibility of illumination. 
     This object is achieved with the features of claim  1 . Further developments of the invention constitute subject matter of the dependent claims. 
     Basing considerations on the thought that the light-radiation characteristic and the position of installation of LEDs and conventional light sources differ for reasons of observance of the operating conditions for the respective illuminants, an arrangement is proposed for light-emission that has LED illuminants in an elongate arrangement, a carrier element which carries the LED illuminants, and a light-radiating element which can be connected to the carrier element. The light-radiating element has a first region in which traversing light is scattered to a large extent. Furthermore, it has a second region in which traversing light is scattered to a significantly smaller extent than in the first region. Usability of the light of the LED illuminant that was not originally scattered and light that is scattered is thus rendered possible in lamp constructions that are largely conventional. 
     The differing extent of scattering in the two regions is preferably achieved by means of differing materials of differing optical properties. Alternatively, use of a single material of differing thickness in the two regions is also possible. 
     In addition, the use of a common material with a differingly high quantity of scattering particles incorporated therein is also possible as an option. 
     For further improvement of the flexibility of the illumination, in addition prism-shaped elevations and/or depressions can be applied to the outside of the light-radiating element in order to guide the light that is not scattered. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention is described by way of example in the following with reference to the drawings in which an advantageous exemplary embodiment of the invention is presented and in which: 
         FIG. 1  shows an exemplary embodiment of the luminaire in accordance with the invention; 
         FIG. 2  shows a first exemplary embodiment of the arrangement in accordance with the invention in a detailed view; 
         FIG. 3  shows a second exemplary embodiment of the arrangement in accordance with the invention in a detailed view; 
         FIG. 4  shows a third exemplary embodiment of the arrangement in accordance with the invention in a detailed view; and 
         FIG. 5  shows a fourth exemplary embodiment of the arrangement in accordance with the invention in a detailed view. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     In the first instance, the general structure of the luminaire in accordance with the invention is explained with reference to  FIG. 1 . Subsequently, the precise technical structure and the mode of functioning of the arrangement in accordance with the invention, in particular of the light-radiating element contained therein, are pointed out with reference to  FIG. 2-FIG .  5 . Identical elements have in part not been repeatedly presented and described in figures that are similar. 
       FIG. 1  shows an exemplary embodiment of a luminaire  10  in accordance with the invention in a sectional representation. The luminaire  10  in accordance with the invention in this case contains a housing  20 , a reflector  30 , an arrangement for light-emission  100  and a cover  33 . With its closed side, the upper side in the drawing, the housing  20  can in this case be secured to a surface, for example a ceiling. The light-emission is effected through the arrangement for light-emission  100  in the opposite direction through the cover  33 . The reflector  30  then reflects a portion of the luminous power emitted by the arrangement for light-emission  100 . 
     The reflector  30  is in this case set up with a curved form, in particular a parabolic form. Uniform illumination of a region that is controllable in a targeted manner is thus achieved. The reflector  30  in this case ends so as to be flush with the housing  20  of the luminaire  10 . The reflector  30  is provided with a focal point in the sectional representation. In three-dimensional reality, this is not a focal point, but a focal line. The focal point largely corresponds, at least in sections, with the outer surface of the light-radiating element  130 . Optimum distribution of the light that is radiated by the light-radiating element  130  through the reflector  30  is thus achieved. 
     The arrangement for light-emission  100  contains a carrier element  120 , an LED illuminant  110  and a light-radiating element  130 . The carrier element  120  is in this case connected to the housing  20  of the luminaire  10 . The carrier element  120  carries, furthermore, the LED illuminant  110 . Alternatively, a plurality of LED illuminants  110  can also be secured to the carrier element  120 . The LED illuminant  110  is preferably reversibly connected to the carrier element  120  and can be connected or separated without the use of a tool. The LED illuminant  110  is arranged in such a way that the light-radiation is effected in the direction of the open side of the housing  20  that is provided with the cover  33 . Arranged between the LED illuminant  110  and the cover  33  there is, furthermore, the light-radiating element  130 . In this case, it is connected to the carrier element  120  and held by it. Advantageously, this connection is reversible and can be effected and released without the use of a tool. Instead of being connected merely to the housing  20 , the carrier element  120  can complete the surface of the housing  20  that is interrupted by an opening. It is thus possible to make savings in terms of material for the housing. 
     The light-radiating element  130  in this connection is a profiled body with a substantially trapezoidal or substantially rounded cross section. It is aligned in this case along the elongate LED illuminant  110 . The light-radiating element  130  then extends over the whole length of the LED illuminant  110 . 
     The aim of the present invention is the targeted control of the light-radiation characteristic of the LED illuminant  110 . For this, the light-radiating element  130  is provided with various regions of differing light-radiation characteristics. Thus, for example, a very diffuse light-radiation characteristic is achieved directly downwards, that is, in the direct direction of radiation of the LED illuminants  110  by virtue of the fact that the light-radiating element  130  has a large scattering effect in this region. In the lateral direction, that is, in the vicinity of the edge of the luminaire  10 , on the other hand, a directional light-radiation characteristic is to be achieved. For this, the light-radiating element  130  is formed in this region so that it is largely transparent and only scatters the traversing light a little. This is dealt with in greater detail with reference to  FIGS. 2-5 . 
     For further scattering of the light-radiation characteristic of the luminaire  10 , the cover  33  is divided into a plurality of sections  31 ,  32 . Located in the vicinity of the light-radiating element  130  is the first section  32  of the cover  33 . This first section is provided with a first light-radiation characteristic. Located in the region close to the edge of the luminaire  10 , that is, remote from the light-radiating element  130 , is the second section  31  of the cover  33 . Here, the cover  33  is provided with a second light-radiation characteristic. Thus further fine adjustment of the light quality can be effected in the various regions that are to be illuminated. For example, diffuse, very uniform illumination is possible in the region of the light-radiating element  130  directly in the direction of the light-exit opening of the luminaire  10 , whilst in the lateral region, that is, to the side of the direct direction of radiation, illumination that is less diffuse are achieved with at the same time a higher degree of efficiency on account of lower losses as a result of scattering. 
     The reflector  30  is likewise connected to the carrier element  120 . In the case of a conventional luminaire, one or more fluorescent tubes would be located at the focal point of the reflector  30 . These would be arranged perpendicularly with respect to the sectional plane of the drawings. The light-radiating element  130  is formed here in such a way that its outer form largely corresponds to the contour of the fluorescent tube or fluorescent tubes in a conventional luminaire. 
     The reflector  30  projects into the region of the light-radiating element  130 . In other words, the reflector  30  and the light-radiating element  130  overlap in part. The reflector  30  has a first light-radiation characteristic outside the light-radiating element  130 . In the region inside the light-radiating element  130 , the reflector has a second light-radiation characteristic. As a result, the whole light-radiation characteristic of the luminaire  10  can be adjusted further. 
     Advantageously, moreover, the surface of the carrier element  120  that is directed in the direction of the light-radiation is provided with a coating of high reflectivity. A further increase in the degree of efficiency of the luminaire can thus be attained. 
       FIG. 2  shows a first exemplary embodiment of the light-radiating element  130  from  FIG. 1 . Here as well, the light-radiating element is shown in a cross-sectional representation. The substantially trapezoidal cross section is clearly recognizable. The light-radiating element  130  is provided with holding strips  45  and securing strips  44  in the upper region in order to secure it to the carrier element  120  from  FIG. 1 . 
     The light-radiating element shown here consists of two different materials  42 ,  43 . In a first region  41 , which is located directly underneath the LED illuminant and thus in the main direction of radiation, the light-radiating element consists mainly of a first material  42 . This first material  42  has a very strong scattering effect. In other words, traversing light undergoes strong scattering. In a second region  40  at the edge of the light-radiating element, that is, to the side with respect to the main direction of radiation of the LED illuminants, the light-radiating element predominantly consists of a second material  43 . This second material  43  is largely transparent or has at least significantly fewer scattering properties than the first material  42 . 
     In the exemplary embodiment shown here, there is a smooth transition between the first material  42  and the second material  43 . This is achieved here by means of a reduction in the material cross section of the first material  42 , starting from the first region  41  through to the second region  40 , and a simultaneous increase in the material cross section of the second material  43 . As a result of the decrease in the cross section of the strongly scattering first material  42 , the scattering effect becomes less, the further away from the first region  41  a light beam penetrates the radiating element. Alternatively, however, there can also be an abrupt transition from the first material  42  to the second material  43 . 
     A second exemplary embodiment of the light-radiating element  130  from  FIG. 1  is shown in  FIG. 3 . The light-radiating element shown here consists merely of a single material  52 . This material  52  has scattering properties. The greater the thickness of the material  52  is, the stronger the scattering properties are. In a first region  51 , the light-radiating element has a very great thickness. In a second region  50 , the light-radiating element has a very small thickness. Thus, just as in  FIG. 2 , a situation is reached where in the first region  51  a strong scattering effect occurs, whilst in the second region  50  merely a small scattering effect is attained. 
     In the two exemplary embodiments shown in  FIG. 2  and  FIG. 3 , the light-radiating element has sharp edges. However, this is only an exemplary configuration. Rounded edges are likewise conceivable and additionally ensure that the illumination is more uniform. 
       FIG. 4  shows a third exemplary embodiment of the arrangement in accordance with the invention for light-emission in a detailed view. Here as well, merely the light-radiating element  130  from  FIG. 1  is shown. This light-radiating element is also provided with a first region  61  and a second region  60 . Just like the light-radiating element shown in  FIG. 3 , it consists merely of a single material  62  which has a scattering effect that is dependent upon its material thickness. The light-radiating element shown here differs from the light-radiating element shown in  FIG. 3  merely as a result of its form in the cross-sectional representation. Thus, the light-radiating element shown here has a rounded form, in particular a circular-arc-shaped form, in the cross-sectional representation. Illumination that is even more uniform can be achieved by means of this shaping. 
     A fourth exemplary embodiment of the arrangement in accordance with the invention for light-emission is shown in a detailed view in  FIG. 5 . Here as well merely the light-radiating element  130  from  FIG. 1  is shown. Just as in  FIG. 4 , the light-radiating element shown here has a rounded form in the cross-sectional representation. 
     This light-radiating element also consists merely of a single material  72 . It has largely a uniform wall thickness. This light-radiating element is also provided with a first region  71  and a second region  70 . In the first region  71 , a high number of scattering particles  74  is incorporated in the material  72 . Thus a high scattering effect on traversing light is achieved in the first region  71 . At the same time, in the second region  70  a very small scattering effect on traversing light is achieved, since there merely a very small number of scattering particles  74  is introduced into the material  72 . 
     In the exemplary embodiment shown here, furthermore, prism-shaped elevations  73  are applied on the outside of the light-radiating element in the second region  70 . As a result of their precise shaping, further guidance of the traversing light is effected in desired directions. Instead of prism-shaped elevations  73 , prism-shaped depressions can also be used. A combination of elevations  73  and depressions is also possible. The prism-shaped elevations  73  and/or depressions give rise to further improvement in the controllability of the light-radiation characteristic. 
     The invention is not limited to the exemplary embodiment shown. Profiles of the light-radiating element that deviate therefrom are also conceivable. Use without a reflector is within the inventive idea too. A combination of the materials and light-radiation characteristics put forward here is also possible. All of the features described above or features shown in the figures can be combined with each other advantageously in any way within the scope of the invention.