Patent Publication Number: US-2012026737-A1

Title: Outdoor lighting unit

Description:
The invention relates to an outdoor lighting unit for lighting streets, sidewalks, outdoor industrial installation and the like (e.g. also railroad installations, aircraft runways, parking areas, houses, camping sites, sports fields, etc.). 
     It is known for such outdoor lighting units to provide an LED light source which has a plurality of light emitting diodes and which is characterized by high reliability and a long service life. It is, however, important not to exceed a predefined operating temperature on the use of an LED light source. It is furthermore important to protect the LED light source against contamination and weather influences. These measures should be achieved with a small manufacturing effort. Furthermore, the outdoor lighting unit should be able to be easily adapted to different applications or customer wishes. 
     It is an object of the invention to provide an outdoor lighting unit which ensures an effective cooling of the LED light source and protection against environmental influences with a simple manufacture. 
     This object is satisfied by an outdoor lighting unit having the features of claim  1 . This lighting unit has an LED light source with a plurality of light emitting diodes in a two-dimensional arrangement, i.e. an areal arrangement. The lighting unit furthermore has a housing which includes a single-part, solid housing element. This housing element has at its lower side (with respect to the position of use of the lighting unit) at least one planar installation section at which a rear side of the LED light source is fastened areally and in a thermally conductive connection. The housing element furthermore has at the lower side a peripheral marginal section which projects downwardly with respect to the plane of said installation section (again with respect to the position of use of the lighting unit). At its upper side, the housing element has an exposed cooling section which is convexly curved and has a plurality of cooling passages which extend along the convex curvature. The housing element additionally includes a holding section by means of which the lighting unit can be fastened in a self-supporting manner to a mast, for example. 
     Since the housing element is made in one piece with said different sections and in a solid manner, the housing element not only serves for the reception of the LED light source. The housing element rather also forms an effective heat sink for the LED light source with a high heat capacity and good thermal conductivity from the installation section for the LED light source to all said further sections of the housing element. Due to the areal arrangement of the LED light source at the installation section of the housing element, an efficient transfer of the waste heat of the LED light source to the housing element is ensured, with a direct areal contact, an indirect areal contact e.g. via a thermally conductive paste) or a slight air gap being able to be provided. Due to the one-part design, a simple manufacture of the housing element and a simple installation of the lighting unit are also possible. 
     An installation volume in which the LED light source can be arranged, in particular together with a reflector device, is formed by the peripheral wall section of the housing element at its lower side. The downwardly projecting arrangement of the wall section (again with respect to the position of use of the lighting unit) corresponds to a bell-like enclosing of the LED light source, whereby particularly good protection against environmental influences is ensured. 
     Whereas the total housing element acts as a heat sink for the waste heat of the LED light source due to its solid design, the upper side of the housing element (that is the substantially upwardly facing outer side in the position of use of the lighting unit) serves as a cooling section in order effectively to output the heat taken up by the LED light source to the environment. This cooling section is exposed, i.e. it is directly exposed to the environment of the lighting unit. An air flow can be used particularly effectively for cooling purposes due to the convex curvature of the cooling section and due to the formation of a plurality of cooling passages. Environmental air which is heated by the housing element and flows upwardly is namely guided along the cooling passages, whereby an increase of the throughflow speed (passage effect) and an increase of the surface covered by the air flow result. Furthermore, a cooling of the housing element and self-cleaning effects are possible by precipitation which impacts on the housing element from above and flows off downwardly along the cooling passages (rain, melted snow or melted ice). 
     Due to the integral formation of a holding section at said housing element (for example a joint section or a fastening flange) not only a particularly simple structure of the lighting unit with few components results, but also a good thermal transfer to the holding device which can thus serve as an additional heat sink, in particular for adjacently arranged electronic or electrical components of the lighting unit with a particularly high thermal output (e.g. power pack, control unit). 
     Advantageous embodiments are described in the following and are named in the dependent claims. 
     In accordance with an advantageous embodiment, the housing element extends, starting from said holding section, along a lengthways direction, with the cooling passages of the cooling section extending substantially perpendicular to this lengthways direction. The lighting unit, which is anyway characterized by a high stability due to the one-part design of the explained housing element, can hereby withstand particularly high wind loads. If the wind namely does not engage at the relatively narrow front side or rear side, but rather at one of the lengthways sides of the housing element, the reduced air resistance makes itself advantageously noticeable due to the cooling passages extending in the transverse direction. This is in particular of importance when the lighting unit is used for lighting streets since the lighting unit is typically arranged freestanding in this case and is only supported by a mast as a holding device so that the lighting unit is exposed to the air flows without protection. 
     A particularly inexpensive manufacture of the housing element results when it is formed as a casting, for example from a light metal. 
     The housing element is preferably made from an aluminum alloy resistant to sea water, and indeed without any special surface treatment at the upper side, that is at said cooling section. An AlMg alloy or AlMgMn alloy can be used for this purpose, for example (in particular AlMg2Mn0.8 or AlMg4.5Mn). If no natural oxide layer forms at the housing element and also no anodic oxidation (anodization) is carried out, a better self-cleaning effect namely results at the upper side of the housing element, whereby a better thermal output to the environment is ensured in the long term. If, furthermore, no additional layers are applied to the upper side (e.g. 
     lacquer), a thermal insulation by outermost layers is avoided, which likewise contributes to a good thermal transfer to the environment. If this additional effect is not required for a desired application, a housing element can, however, also be used made from an aluminum alloy resistant to sea water and having an additional surface protection (e.g. lacquer, coating). 
     To achieve a particularly effective overflow of the cooling section of the housing element at the upper side, said cooling passages preferably have a width at half their depth which is at least 2.5 times as large (e.g. approx. 3 times as large) as the width of ribs which are formed between the cooling passages at the cooling section. 
     It is preferred in this respect if said cooling passages have a width of at least 10 mm, in particular a width of at least 15 mm, at half their depth. It is furthermore preferred if the cooling passages have a depth of at least 15 mm. 
     A desired self-cleaning effect at the upper side of the housing element is amplified by the aforesaid proportions and widths since, for example, rainwater can penetrate easily into the cooling passages without disturbing surface tension effects, can wet them, flow out of the cooling passages and in so doing can also take along contaminants. 
     The cooling passages preferably converge toward the base, with the base of the cooling passages being concavely curved in cross-section, for example with a radius of curvature of approximately 5 mm. Air turbulence can hereby arise at the base of the cooling passages which has an advantageous effect on the thermal transfer from the cooling section of the housing element to the environment. 
     In addition to said housing element, the housing of the lighting unit can have a cover device which can be fastened to the lower side of the wall section of the housing element and which is transparent at least in the region of the LED light source. Such a cover device serves for the protection from environmental influences. 
     Said cover device can be thermally conductively connected to the peripheral wall section of the housing element so that the cover device also forms a heat sink for the waste heat of the LED light source. 
     The spacing between the light emitting diodes of the LED light source and the cover device preferably amounts to at least 10 mm, in particular to at least 15 mm. It is hereby ensured that sufficient air circulation can form within the housing in order also to lead off waste heat of the light emitting diode convectively and to transfer it to different housing regions and thus to provide a uniform heat distribution. 
     Said cover device can be pivotably connected to the housing element to allow a simple access to the inner housing space (for example, for servicing purposes). 
     As regards said LED light source, it preferably has an electric insulation layer at the rear side to allow an areal, mechanical connection to the installation section of the typically metallic housing element. 
     The LED light source can be screwed, riveted or adhesively bonded to the installation section of the housing element, in particular using a thermally conductive adhesive. 
     The housing element can have at least two separate installation sections for a respective module of the LED light source at its lower side, with the installation sections extending along different planes (i.e. at different heights) or being arranged inclined with respect to one another (i.e. at an angle different from 180°. 
     In accordance with a particularly advantageous embodiment, the LED light source selectively has one or more modules which have an anisotropic radiation angle characteristic, i.e. a different radiation flow is transmitted in different spatial angle ranges (X/Y characteristic). In this embodiment, the installation section of the housing element is formed to selectively receive a single module (having a predefined radiation angle characteristic), or a plurality of modules (having a respective predefined radiation angle characteristic) in a lengthways arrangement, or a plurality of modules of the LED light source in a transverse arrangement. In other words, the plurality of modules can selectively be arranged next to one another in a lengthways direction or next to one another in a transverse direction. The lighting unit can hereby be adapted in a simple manner to different applications or customer wishes (variable configuration of the installation section of the housing element in accordance with a “modular principle”). 
     Said modules of the LED light source can have a substantially square outline, for example, to allow a simple arrangement or a multiple arrangement in different directions. It is, however, generally also possible that said modules, for example, have a rectangular, a round or a hexagonal shape. 
     It is furthermore preferred if not only one variation is possible with respect to different arrangements in different directions. Alternatively or additionally, a variation of the alignment can also be provided, i.e. a module of the light source having a specific X/Y characteristic can selectively also be fastened to the installation section of the housing element in an alignment rotated by 90°. The lighting unit can also hereby be easily adapted to different applications or customer wishes—with an otherwise unchanged structure. In this respect, any desired intermediate positions are also possible (i.e. different angles to 90°, in particular when said modules of the LED light source are round or hexagonal. 
     It is particularly preferred if the installation section of the housing element has a “+” shape, i.e. if the installation section is substantially cruciform. In this case, a plurality of modules of the LED light source can selectively be fastened to the installation section next to one another in a lengthways arrangement or in a transverse arrangement. 
     The surface of the installation section of the housing element in accordance with a further embodiment has a lower roughness than the surface of the cooling section. Whereas an increased roughness at the surface of the cooling section can contribute to an improved thermal transfer from the housing element to the environment, a relatively small roughness of the surface of the installation section effects a better thermal transition from the LED light source to the installation section of the housing element areally connected hereto. 
     The LED light source preferably includes a carrier device to which the plurality of light emitting diodes are electrically conductively and thermally conductively fastened, with a rear side of this carrier device being arranged areally and in a thermally conductive connection at the installation section of the housing element. Said carrier device is preferably made areally thermally conductive at least along a layer to distribute the heat generated by the light emitting diodes areally along the carrier device and also to transfer it areally from the carrier device to the installation section of the housing element. Unwanted, so-called “hot-spots” which could have a negative effect on the operating behavior of the light emitting diodes are hereby effectively avoided. 
     Said peripheral wall section at the lower side of the housing element can surround an installation volume in which the LED light source is arranged together with an associated reflector device. 
     In accordance with a particularly advantageous embodiment, the LED light source has a plurality of reflector elements which are arranged between the plurality of light emitting diodes and which are thermally conductively connected to the light emitting diodes. The reflector elements are in this respect located at the side remote from the installation section of the housing element, i.e. in the position of use of the lighting unit the reflector elements face downward. The reflector elements primarily serve as reflector elements to distribute the light output by the light emitting diodes in accordance with a desired radiation angle characteristic. In addition, the reflector elements provide an improved heat distribution and act as a further cooling device in that they take up a portion of the waste heat of the light emitting diodes and output it to the inner space of the housing. 
     The spacing between a cover device of the housing or of the already named cover device at the lower side, on the one hand, and said reflector elements, on the other hand, preferably amounts to at least 5 mm. Sufficient air circulation in the inner space of the housing is hereby ensured to distribute the waste heat taken up by the reflector elements. The LED light source is thus also cooled by air circulation (i.e. convectively) and not only be thermal conductivity at the rear side over the installation section of the housing element. 
     It is furthermore preferred if each of said reflector elements has a flank which is inclined with respect to a surface normal to the plane of the two-dimensional arrangement of the light emitting diodes and which is arranged in a straight line parallel to this arrangement plane in a longitudinal section. It has been found that a radiation angle characteristic particularly suitable for outdoor lighting units can hereby be realized, with the characteristic being settable by selection of the inclination angle. 
     The reflector elements can in particular be arranged in web-shape and have a substantially trapezoidal or triangular transverse section, with the aforesaid flanks also being able to be concavely curved in cross-section. The reflector elements hereby have a particularly simple structure to simultaneously satisfy a cooling function and to effect a desired radiation angle characteristic which is selected, for example, in dependence on the installation height of the outdoor lighting unit. 
     Said reflector elements are preferably formed separately from one another and also separately from said carrier device of the LED light source. A modular design with a settable radiation angle characteristic hereby also results with respect to the LED light source. 
     In accordance with a further embodiment, the outdoor lighting unit has at least one electronic or electrical component separate from the LED light source, for example a transformer and/or a control unit which is thermally conductively connected to an associated fastening section of the housing element. This connection can be realized, for example, via an areal contact or via fastening spigots (so-called domes). The heat generated by said component is hereby output along the housing element both to the installation section for the LED light source and to the cooling section. It can hereby be achieved that the heat generated by said component is utilized to bring the LED light source quickly to the desired operating temperature after its switching on, with an overheating being avoided in that the heat Oust like the waste heat of the LED light source) is ultimately also transferred to the cooling section of the housing element. 
     In accordance with an advantageous further development of this embodiment, said fastening section is arranged at the lower side of the housing element between the installation section (for the LED light source) on the one hand and the explained holding section (for the fastening of the lighting unit to a holding device) on the other hand so that the heat generated by the component is also effectively transferred to the associated holding device. In other words, said electronic or electrical component, which generates a particularly high thermal output, is arranged adjacent to the holding section of the housing element so that the waste heat can be effectively output to the associated holding device. 
     It is preferred if in the region of said fastening section (for the electrical or electronic component) the housing element is higher relative to the installation section for the LED light source and/or has a larger material thickness. A higher mechanical stability can hereby be achieved in the region of said fastening section, in particular if it is arranged between said installation section and the holding section of the housing element, and the higher material use can also result in a better thermal distribution. 
    
    
     
       The invention will be explained in the following only by way of example with reference to the drawings. The direction indications named in the following relate to the position of use of the explained outdoor lighting unit. 
         FIG. 1  shows an outdoor lighting unit in a perspective view obliquely from above; 
         FIG. 2  shows the lighting unit in a perspective view obliquely from below (with two modules of the light source in a transverse arrangement); 
         FIG. 3  shows a lower view of the lighting unit (with two modules of the light source in a lengthways arrangement); 
         FIG. 4  shows the lighting unit in a perspective view from below (with a single module of the light source).; 
         FIG. 5  shows a perspective view of the lower side of the housing element of the lighting unit in accordance with  FIGS. 1 to 4 ; 
         FIG. 6  shows a lower view of the housing element 
         FIG. 7  shows a cross-sectional view along the plane VII-VII of  FIG. 6 ; 
         FIG. 8  shows a perspective view of a module of the light source of the lighting unit of  FIGS. 1 to 4 . 
     
    
    
     The outdoor lighting unit (in the following: lighting unit) shown in  FIGS. 1 to 4  serves for the lighting of streets, sidewalks, outdoor industrial installations and the like. The lighting unit has an LED light source  11  and a housing  13 . The housing  13  includes a single one-part housing element  15  which is made solid, i.e. substantially without hollow spaces (apart from openings for a mechanical or electric connection). The housing element  15  is formed as a casting made from an aluminum alloy resistant to sea water and thus resistant to weather without any additional surface treatment at the upper side, for example from AlMg4.5Mn. The housing  13  furthermore includes a cover device  17  in the form of a plate which is pivotably connected to the housing element  15  by means of two hinges  19  and which is made transparent in the region of the LED light source  11 . The cover device  17  is fixable by means of fixing devices, not designated in any more detail, in the position shown closed in  FIGS. 2 to 4 . 
     The LED light source  11  has a plurality of light emitting diodes  21  in a two-dimensional arrangement, namely in an arrangement of a plurality of rows  23 . The LED light source  11  furthermore includes a plurality of web-shaped reflector elements  25 , with each reflector element  25  being arranged between two rows  23  of light emitting diodes  21  or adjacent to an outermost row  23  of light emitting diodes  21  (cf. in particular  FIG. 3 ). The light emitting diodes  21  are electrically conductively and thermally conductively fastened to a planar carrier device  27 . The reflector elements  25  are also thermally conductively fastened to the carrier device  27 . The LED light source  11  can include a plurality of modules  29 , with each module  29  having its own carrier device  27  with light emitting diodes  21  and reflector elements  25  arranged thereon. Two such modules  29  are shown in  FIGS. 2 and 3 . A single module  29  is shown in  FIG. 4 . 
     The housing element  15  includes a plurality of sections which are made integrally at the housing element  15  and which satisfy different functions. A planar, substantially “+” shaped installation section  31  is provided at the lower side of the housing element  15 , and the rear side of the carrier device  27  of the LED light source  11  is fastened (for example, screwed, riveted or adhesively bonded) thereto areally and in a thermally conductive connection. The housing element  15  furthermore includes a peripheral wall section  33  at the lower side which projects downwardly from the plane of extent of said installation section  31 , i.e. the wall section  33  protrudes downwardly with respect to the plane of the installation section  31 . The wall section  31  hereby surrounds an installation volume  35  of the housing element  15  in which the LED light source  11  including the reflector elements  25  is arranged. 
     The housing element  15  additionally includes at the upper side an exposed cooling section  37  which is convexly curved (for example with respect to the plane of extent of the installation section  31 ) and has a plurality of cooling passages  39  which extend along the convex curvature. The housing element  15  furthermore has a holding section  41  which cooperates with a joint element  43  of an associated holding device  45  (e.g. mast) so that the lighting unit can be fastened to the holding device  45  in a self-supporting manner. Starting from the holding section  41 , the housing element  15  extends along a lengthways direction X. Said cooling passages  39  extend substantially perpendicular to this lengthways direction X, i.e. along a transverse direction Y. 
     The housing element  15  furthermore has a fastening section  17  (cf.  FIGS. 5 and 6 ) at the lower side. An electrical component  49  (e.g. a power pack) is fastened thereto in a thermally conductive manner (cf.  FIGS. 2 to 4 ). 
     A particular advantage of the outdoor lighting unit shown comprises the one-part solid formation of the housing element  15  with the sections  31 ,  33 ,  37 ,  41  and  47 . The total and single housing element  15  with an optimized thermal transition can namely hereby serve as a heat sink for the LED light source  11 . Since the cover device  17  contacts the lower side of the peripheral wall section  33  and is thus thermally conductively connected to the wall section  33 , the cover device  17  can serve as an additional heat sink for the waste heat of the LED light source  11 . Heat can also be output to the associated holding device  45  via the holding section  41 . 
     Due to the downwardly projecting peripheral wall section  33 , the housing element  15  furthermore has a bell shape, with the LED light source  11  being provided in an elevated arrangement with respect to the lower side of the wall section  33  so that the LED light source  11  is particularly effectively protected against environmental influences. The plate-shaped cover crevice  17  contacting the lower side of the peripheral wall section  33  provides effective protection for the inner space of the housing element  15  against environmental influences with a simple structure. 
     Advantageous details of the lighting unit shown will be explained in the following. 
     Not only an increase in the surface is achieved by the formation of the cooling passages  39  at the convexly curved cooling section  37 , but the heating of the environmental air at the upper side of the housing element  15  rather effects a rising of the heated air, with cooler air being able to flow on constantly along the cooling passages  39  also extending in the vertical direction. Substantially the total surface of the cooling section  37  at the upper side is hereby utilized for an effective thermal transfer to the environmental air. It is important in this respect that the width of the cooling passages  39  (with respect to half of its depth) is at least  2 . 5  times as large as the width of ribs  51  (with respect to half the height of the ribs) which are formed at the cooling section  37  between the cooling passages  39 . 
     The formation of cooling passages  39  with such width relationships is also of particular advantage with respect to the stability toward wind loads which engage along the lengthways sides of the housing  13 . An only small air resistance is namely produced along the transverse direction Y (despite the lengthways shape of the housing  13 ) by the wide cooling passages  39 . 
     The wide cooling passages  39  furthermore contribute to the fact that precipitation can flow off effectively from the upper side of the housing  13  while forming a self-cleaning effect. 
     As regards the cooling of the LED light source  11 , it is also of special advantage that the reflector elements  25  are thermally conductively connected to the light emitting diodes  21  (directly or via the carrier device  27 ). The reflector elements  25  thus serve as an additional cooling device. 
     It is also of advantage in this connection that the inner space of the housing  13  has a large clearance. In other words, a sufficient spacing between the light emitting diodes  21  or the reflector elements  25 , on the one hand, and the upper side of the cover device  17 , on the other hand, is provided to allow the formation of air circulation in the inner space of the housing  13 . For example, the spacing between the lower side (i.e. the tip) of the reflector elements  25  and of the cover device  17  can amount to at least 5 mm. An effective air overflow of the light emitting diodes  21  is hereby made possible for the purpose of convective cooling. 
     Due to the arrangement of the fastening section  47  between the assembly section  31  for the LED light source  11 , on the one hand, and the holding section  41 , on the other hand, the waste heat generated by the electrical component  49  can be used so that the LED light source  11  fast reaches its predefined thermal operating point after its switching on. 
     There is a particular advantage with respect to the cooperation of the modules  29  of the LED light source  11  with the associated installation section  31  of the housing element  15 . The substantially square modules  29  namely have an anisotropic radiation angle characteristic due to the web-shaped reflector element  25 , i.e. much more light is radiated along a first direction than along a second direction perpendicular hereto. The modules  29  can, on the one hand, be fastened in different angular positions to the installation section  31  (i.e. the reflector elements  25  extend parallel or perpendicular to the lengthways direction X). On the other hand, selectively a single module  29  or a plurality of modules  29  in a lengthways arrangement or in a transverse arrangement can be fastened at the “+” shaped installation section  31  (i.e. next to one another along the lengthways direction X or next to one another along the transverse direction Y). By varying these parameters (angular position, direction of arrangement), the radiation angle characteristic of the lighting unit can thus be adapted in a simple manner to different applications or customer wishes while maintaining the same base structure and while using the same components. 
     Finally, the exact design of an LED light source  11  will be explained in more detail with reference to  FIG. 8 .  FIG. 8  shows that the light emitting diodes  21  are fastened (for example soldered on, bonded or conductively adhered) to the carrier device  27  in accordance with a two-dimensional pattern. The light emitting diodes  21  are in this respect arranged in a plurality of rows  23 , with a respective web-shaped reflector element  25  being fastened (e.g. screwed) between two adjacent rows  23  at the carrier device  27 . Each reflector element  25  thus acts as a reflector for a plurality of light emitting diodes  21 . The light emitting diodes  21  typically transmit visible light at a nominal radiation angle of approximately 120° with a substantially white emission spectrum. They are light emitting diodes  21  with high brightness to be able to illuminate large areas. 
     The carrier device  27  is a circuit board or another type of carrier plate having a plurality of metallic conductor tracks  61  and a plurality of connector surfaces (i.e. solder surfaces)  63 . The carrier device  27  is made areally thermally conductive to distribute the heat generated by the light emitting diodes  21  areally along the carrier device  27  and to transfer it areally from the carrier device  27  to the installation section  31  of the housing element  15  ( FIGS. 1 to 7 ). For this purpose, the conductor tracks  61  form, together with the connector surfaces  63 , a regionally interrupted thermally conductive layer  62  at the front side of the carrier device  27 . Additional thermally conductive layers (in particular full-area, i.e. uninterrupted, thermally conductive layers) can also be provided within the carrier device  27 . The metallic conductor tracks  61  are for the larger part covered by a thin insulation layer  64  at the front side. The insulation layer  64  effects an electric insulation and simultaneously allows an effective thermal coupling of the reflector elements  25  via said thermally conductive layer  62  (i.e. via the conductor tracks  61 ) with the rear side of the light emitting diodes  21  so that the reflector elements  25  serve as a cooling device for the light emitting diodes  21 . For this purpose, the light emitting diodes are partly seated on the conductor tracks  61  and the reflector elements  25  overlap (via said insulations layer  64 ) with lateral regions of the conductor paths  61 . At the rear side, the carrier device  27  of the LED light source  11  has an electric insulating layer  65  to effect a reliable electric insulation from the installation section  31  of the housing element  15 . 
     The reflector elements  25  have a trapezoidal cross-section, with the reflector elements  25  converging as the distance from the carrier device  27  increases, i.e. along a surface normal of the carrier device  27 . Each reflector element  25  has a respective flank  67  along its two lengthways sides which forms the actual reflector surface. These flanks  67  are inclined by a predefined angle of inclination with respect to the surface normal of the carrier device  27 . It can be seen from  FIG. 8  that the flanks  67  are made in a straight line in a lengthways section parallel to the plane of extent of the carrier device  27 . 
     Since the reflector elements  25  are formed separately from the carrier device  27 , the LED light source  11  has a modular structure. It is hereby possible selectively to configure a respective LED light source  11  with one of a plurality of different sets of reflector elements  25  which in particular differ with respect to said angle of inclination of the flanks  67 . An adaptation of the outdoor lighting unit to different applications or customer wishes can hereby additionally take place. 
     It is also of special advantage in this respect that no further optical elements are absolutely necessary due to the use of the web-shaped reflector elements  25 . The LED light source  11  can in particular be formed without separate lenses. A simple transparent cover (cover device  17 ) is sufficient as protection against contamination. 
     REFERENCE NUMERAL LIST  
     
         
           11  LED light source 
           13  housing 
           15  housing element 
           17  cover device 
           19  hinge 
           21  light emitting diode 
           23  row 
           25  reflector element 
           27  carrier device 
           29  module 
           31  assembly section 
           33  wall section 
           35  installation volume 
           37  cooling section 
           39  cooling passage 
           41  holding section 
           43  joint element 
           45  holding device 
           47  fastening section 
           49  electrical component 
           51  rib 
           61  conductor track 
           62  thermally conductive layer 
           63  connector surface 
           64  insulating layer 
           65  insulating layer 
           67  flank 
         X lengthways direction 
         Y transverse direction