Abstract:
Set of a plurality of LED emitters, wherein the LED emitters in the set generate a different luminous efficacy, and have a standard housing.

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates generally to lighting which uses LEDs as light-generating elements. 
     SUMMARY OF THE INVENTION 
     In this case, the object of the present invention is to specify particularly advantageous configurations. An advantageous configuration is in this case firstly to be understood to mean that a large number of identical parts can also be used for LED emitters with different luminous efficacy (lumens) on the production side. Alternatively or in addition, an advantageous configuration can also be understood to mean that the luminous efficacy emitted by the LED emitter is conducted very efficiently from the emitter. 
     This object is achieved by the features of the independent claims. The dependent claims advantageously develop the central concept of the invention. 
     The invention provides a set of a plurality of LED emitters, wherein
     the LED emitters in the set generate a different luminous efficacy,   the LED emitters have a standard housing.   

     Each emitter can have an LED module with a plurality of LED chips, wherein the mid-distance between the LED chips of an LED module and also the mid-distance between LED chips of LED modules of different emitters is preferably constant. In this case, the mid-distance is the distance between the axes of symmetry of two mirror-symmetrical or rotationally symmetrical LED chips. 
     The mid-distance can be between 1.5 mm and 4 mm, preferably 2.5 to 4 mm. 
     The mid-distance between the LED chips which has been selected so as to be relatively small is used for improved luminous efficacy. By virtue of said small mid-distance between the LED chips on the LED module, homogenous white light is emitted by the LED modules or LED emitters, while the heat dissipation of the LED module remains optimized. The use of metal-core printed circuit boards as mounts for the LED module is in this case particularly advantageous. 
     The LED chips can be covered with a dispensed casting compound, such as a so-called dome-shaped globe top or another cover, for example, wherein the globe tops of adjacent LED chips preferably do not run with one another. 
     Globe tops which run with one another are also conceivable. In this exemplary embodiment, a plurality of LEDs are positioned beneath a common globe top. 
     Furthermore, the invention relates to an LED emitter, having:
     a plurality of LED chips spaced uniformly apart from one another on a common mount, wherein the LED chips are covered by a casting compound, and the LED chips form a light field,   a reflector, which is positioned directly on the mount, extends away from the mount and surrounds the light field narrowly on its side positioned on the mount   

     The light area can make up at least 30%, preferably at least 50%, even more preferably 55%, of the cross-sectional area of that side of the reflector which is positioned on the mount. 
     The lateral surface of the reflector can have a parabolic or a linear profile. 
     The surface of the reflector can be faceted and/or patterned. 
     The total area of the covered LED chips can make up at least 20%, preferably at least 25%, even more preferably at least 35%, of that side of the reflector which is positioned on the mount. 
     The LED emitter can be in the form of a so-called ceiling-mounted emitter for installation in suspended ceilings. 
     The LED emitter can have a housing with a light exit opening, which is covered by a diffuser (and/or phosphor disk) or is open. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Further advantages, features and properties of the invention will now be explained in more detail with reference to the description of an exemplary embodiment and the figures of the attached drawings. 
         FIGS. 1 ,  2  and  3  show LED modules for LED emitters of different luminous efficacy, and 
         FIG. 4  shows an exploded view of an LED emitter with one of the LED modules shown in  FIGS. 1 to 3 , and 
         FIG. 5  shows a facet reflector which can be used in the context of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The invention relates in particular to a group of identical LED emitters, wherein the group has LED emitters with different luminous efficacy (lumens). Emitters with at least two different luminous efficacies in this case have a different number of LED chips, but mounts (printed circuit boards) with identical dimensions, which ensures an increase in the number of identical parts even for LED emitters with different luminous efficacies. 
     In this case,  FIG. 1  shows an LED module, i.e. a large number of LED chips  1  on a printed circuit board mount  2 . This LED module  3  in  FIG. 1  can be provided for a luminous efficacy of 2000 lumens, for example. 
       FIG. 2  now shows a further LED module, which can be dimensioned, for example, for a luminous efficacy (when installed in an LED emitter) of 3000 lumens and correspondingly has more LED chips. 
     This LED module  4  has the same printed circuit board  5  as the LED module  6  illustrated in  FIG. 3  for a luminous efficacy of 4000 lumens, for example, which LED module  6  therefore has an identical printed circuit board as regards dimensions and fitting holes  8 . 
     Further standardization can be provided in that the distance between the light spots, i.e. the mid-points of the LED chips  1 , is identical for all of the LED modules  3 ,  5 ,  6  in  FIGS. 1 ,  2  and  3 . The distance between the mid-points is in this case the distance between the axes of symmetry of two mirror-symmetrical or rotationally symmetrical LED chips. 
     The distance between the light spots (mid-point distance) can be, for example, between 2 and 4 mm, preferably between 3.2 and 3.8 mm. As has been mentioned, this distance between the light spots can be selected to be identical for the LED modules of different powers, which in turn can result in standardization possibilities (use of identical parts) as regards the downstream optics (reflector, diffuser, phosphor disk), which will be explained below with reference to  FIG. 4 . 
     As can be seen from  FIG. 4 , the LED module shown in  FIGS. 1 ,  2  and  3 , now denoted by the reference symbol  10 , is installed in an LED emitter, which can be used as a downlight or spotlight, for example. This emitter, denoted overall by  11  in  FIG. 4 , has a bottom-side housing with a heat sink  32 , for example, on which the LED module  10  is fitted in thermal contact. 
     Preferably, at least essential parts of the bottom housing part  32  are manufactured from a material with high thermal conductivity, in particular from metal. 
     Preferably, a reflector  12  is positioned in direct contact on the printed circuit board of the LED module  10 , said reflector preferably being configured in such a way that that side  13  of the reflector which is open towards the LEDs has a smaller cross-sectional area than the exit side  14  of the reflector  12  which faces away from the LEDs. There is therefore a reflector which extends in the light emission direction. 
     The reflector is preferably rotationally symmetrical. 
     The contours (generatrices) of the reflector  12  can in this case be linear, with the result that a truncated cone shape is produced. Alternatively, however, other profiles are also conceivable, in particular bent profiles such as parabolic profiles, for example, for the contour of the lateral surface  15  of the reflector  12 . 
     Finally, an upper part  20  and a covering disk  21  with a central, preferably circular opening  22  is positioned on the bottom part  12  of the housing. 
     Optionally, a diffuser (not shown) can be inserted into the circular exit opening  22 , it being possible for said diffuser to optionally also perform further optical functions, in addition to the diffuser effect thereof. For example, a color conversion medium for changing the wavelength (for example in the form of a phosphor disk) can also be inserted into the diffuser, if used. 
     The phosphor disk can also be used without diffuse particles in the LED emitter. The use of phosphor disks and/or diffusers with patterned surfaces is also conceivable. 
     Overall, it is preferred, however, that a color conversion medium (for example inorganic or organic phosphors)  30  is applied in the form of a so-called globe top or in another way to the respective LED chip in direct contact therewith so as to generate white light. 
     As has been mentioned, the housing shown in  FIG. 4  and the reflector are used in the form of identical parts for LED modules likewise with different dimensions and in any case different luminous efficacies (lumens). 
     The use of a phosphor disk in combination with a white reflector (which forms a highly reflective surface) is particularly preferred when the LED module  10  has LEDs of different spectrums, for example monochromatic LEDs, in particular red LEDs, in combination with a preferably phosphor-converted for example blue or UV LED (which emits white light, for example) or with a further monochromatic, for example blue or green LED. The phosphor-converted LEDs can emit green, white or red light, for example. 
     The reflector  12  having a highly reflective surface (for example white surface) ensures effective light mixing, with the result that the space delimited by the reflector  12  can also be referred to as a light mixing chamber within the LED emitter. Homogenous white light is generated from the monochromatic or from the monochromatic and phosphor-converted light-emitting diodes with the aid of the light mixing chamber. 
     An additional reflector (not shown), which can be positioned on the LED emitter  11 , is also conceivable. A multi-stage optics system with targeted light direction can be realized by means of this additional reflector. 
     The reflector  12  can be manufactured from a coated polymer, a metal such as aluminum etc. 
     The reflector consisting of metal in conjunction with a diffuser is preferred for the exemplary embodiments in which phosphor-converted LEDs are primarily used. By using a metal reflector, the light direction can be controlled as desired without the use of a multi-stage optics system. 
     Conventional metal reflectors can be incorporated in the LED emitters. They provide further standardization possibilities. 
     The reflector can be faceted, as is shown in the example in  FIG. 5 . 
     The LED emitter  11  illustrated in  FIG. 4  is used in particular as a replacement for existing emitters with conventional light-emitting means, which therefore use a halogen or xenon lamp as light-emitting means. This configuration is generally referred to as a “retrofit”. 
     In accordance with a further embodiment, the diameter of the reflector  12  is matched to the outer contour of the light field formed by the LEDs on the module  10 . In the case of a relatively small light field, such as in  FIG. 1 , for example, therefore, a smaller reflector can be selected than in the case of a relatively large light field as illustrated in  FIGS. 2 and 3 . 
     In this case, the invention is based on the principle that that opening side  13  of the reflector  12  which faces the LEDs surrounds the active light field (outer contour of the LEDs on the LED module  10 ) as narrowly as possible, which increases the efficiency (light output per electrical power, in watts) of the depicted LED emitter  11 . Since the distance between the light spots is selected to be as small as possible, as mentioned already at the outset, the area of the entry side  13  of the extending reflector  12  can therefore also be kept as small as possible. 
     As can already be seen schematically in  FIG. 4 , the extending reflector  12  according to the invention is positioned directly on the printed circuit board of the LED module  10  and is not spaced apart therefrom, which further increases the luminous efficacy. 
     A further concept of the present invention consists in that the active light field is formed by discrete light spots (LED chips spaced apart from one another with separate coating in the form of globe tops), but the “fill level” of the light field, i.e. the total area of the globe tops in comparison to the area formed by the outer contour of the light field, is as high as possible. 
     Preferably, the fill level of the light field, i.e. the proportion of the area of the outer contour of the light field made up by the globe top area, is at least 15%, preferably 20%, even more preferably 35%. 
     A further important parameter according to the invention is the ratio of the area of the outer contour of the light field to the area of the entry side  13  of the reflector  12 . According to the invention, the area of the outer contour of the light field is at least 30%, preferably 50%, even more preferably 55%, of the area of the entry side  13  of the extending reflector  12 . 
     As can be seen schematically in  FIG. 4 , the outer side of the upper part  20  of the housing of the LED emitter  11 , said upper part being manufactured from polymer (with a high thermal conductivity), for example, can be profiled so as to form cooling ribs  25 . 
     These cooling ribs can extend beyond the cover part  21  as well (see reference symbol  26 ).