Patent Publication Number: US-9845934-B2

Title: Lighting arrangement, in particular for escape route lighting

Description:
The present invention relates to a lighting arrangement which above all is suitable for illuminating regions along a straight line. In particular, the invention relates to so-called escape route lighting. 
     Arrangements for escape route lighting are absolutely essential in relatively large building complexes in order to make it possible for people to leave the building in a safe and reliable manner. In contrast with so-called escape sign luminaires, whose task consists in indicating an evacuation or escape route, the task of escape route lighting consists in illuminating or lighting up the escape route itself in a sufficient way. Even in the event of failure of the usual lighting of the building the identification of obstacles and the like in the region of the escape or evacuation route is to be rendered possible by this means so that also relatively large crowds of people can leave the building or rescue forces can get into the building quickly and efficiently. 
     Hitherto, usually luminaires that have a so-called simple symmetrical radiation characteristic have been used for escape route lighting. Such a radiation characteristic by way of which the light of the light source(s) is substantially radiated in two directions that are opposed to each other guarantees uniform illumination of the evacuation route on both sides of the luminaire along a straight line. Such luminaires are, for example, mounted at regular intervals along the ceiling of a corridor constituting the evacuation route. A lateral arrangement, for example on walls or the like, is also known, with the light-radiation characteristic then being correspondingly adapted. Basically, however, in such cases it is provided that the light is delivered in two opposite directions so that lighting of an elongate region is attained on both sides of the luminaire. 
     Light-delivery deviating from this simple symmetrical radiation characteristic would, however, be advantageous for different mounting situations of such luminaires and special courses of the evacuation or escape route. For example, in situations in which the luminaires for escape route lighting are arranged at intersections, branches or bends and/or corners it would be desirable to adapt the light-delivery of the luminaires in a corresponding manner. One-sided illumination of an escape route can also be advantageous, for example, if the means for escape route lighting are integrated into an escape sign luminaire which is mounted above an emergency exit. In this case, one-sided escape route lighting is significantly more efficient, since in the case of symmetrical radiation a portion of the light would be solely directed towards the wall. Furthermore, one-sided light-delivery is also often advantageous in road tunnels since as a result, for example, a situation can be avoided where people who are escaping are dazzled. 
     The underlying set object of the present invention is therefore to offer a possibility of being able to adapt the light-delivery in a simple way in lighting arrangements that are provided in particular for escape route lighting. The outlay for adapting the light-radiation characteristic is to be kept as low as possible in this connection and preferably is not to necessitate the use of specially adapted optical elements. 
     The afore-mentioned object is achieved by means of a lighting arrangement. 
     The solution in accordance with the invention is based on the idea of using one or more light sources that are arranged so as to lie as close together as possible in order to realize the lighting. Associated with the light source or sources there is in each case an optical element which substantially asymmetrically radiates the light that is emitted from the associated light source. Owing to the fact that this optical element is mounted so that it can be positioned in different ways, in particular rotatably, adaptation of the light-radiation characteristic of the lighting arrangement can be effected in a simple way and in particular without the use of novel or additional components. 
     In accordance with the invention, consequently a lighting arrangement, in particular for escape route lighting, is proposed that has a light source as well as an optical element associated with the light source. The optical element is in this case designed to radiate asymmetrically the light that is emitted from the associated light source, with it being possible for it to be positioned in different ways in accordance with the invention. The light source is in this case preferably formed by a substantially punctiform light source, in particular by means of an LED. 
     As already mentioned, preferably a plurality of light sources is provided, arranged at a short distance next to one another and aligned parallel to each other. The optical elements that are associated with the light sources are then in particular of identical construction. The mounting or support of the optical element or elements is then preferably such that they can be positioned in different rotational positions with reference to a longitudinal axis that is defined by the respective light source. Owing to the fact that the optical element or elements is or are, so to speak, rotatably mounted, the direction of the delivered light can be adapted in a simple way, that is, individually for each individual light source. In the event that at least two light sources are used, it is thus possible in a simple way to change from a simple symmetrical radiation characteristic, as it was used hitherto in escape route luminaires in accordance with the embodiments above, to another radiation characteristic which is significantly better suited, for example, for illuminating branches, bends, intersections and the like. It would also be possible to align the optical elements in a similar way so that the light is delivered merely in a single direction. In this connection, means are preferably provided by way of which preferred positions for the optical element or elements are defined. In particular these can be latching elements which are arranged, on the one hand, on the optical element and, on the other hand, on a carrier for the optical element. 
     The optical element itself or optical elements themselves is or are preferably formed in each case by means of a lens. In the case of the use of a punctiform light source, in this connection the lens can have a cavity facing the light source. The arrangement of the lens is then effected in such a way that the light source projects a short way into this cavity, with the lateral and base surface of the cavity then forming the light-entry surface for the lens. It has been shown that with such a configuration the light that is delivered from the light source, for example from an LED, can be utilized in an effective way. The light-exit region of the lens in turn is configured in such a way that the asymmetrical light-delivery that is striven for is attained. It would be possible in this connection in particular to utilize a so-called Fresnel structure, which leads to a reduction in the overall height. 
     In accordance with an advantageous further development of the invention it can also further be provided that an additional light-influencing element is used that can be mounted on the lens in a rotatable manner, for example. This can be a transparent lens, plastics rings or reflectors, or semi-mirrors, partly coated with aluminium or similar by vapour deposition. With the aid of this additional element the light-delivery could then further be adapted to the special requirements. In this case, the lens or the first optical element need not then necessarily deliver light asymmetrically, but could also bring about symmetrical light-delivery. The additional element can thus be utilized, for example, to change between symmetrical and asymmetrical light-delivery or vice versa. 
     In accordance with this aspect, lighting arrangement, in particular for escape route lighting, is thus also proposed that has at least one light source as well as an optical element associated with the light source, wherein the optical element can be positioned in different ways, and associated with the optical element there is an additional light-influencing element which can be set in particular onto the optical element and preferably can be mounted thereon in a rotatable manner. 
     A particularly preferred example of application of the lighting arrangement in accordance with the invention consists, as already explained, in utilizing it to illuminate escape routes. In this connection, in particular it can be provided that the lighting arrangement is integrated in a luminaire as an extension, wherein the carrier for the optical element or elements is then formed by a housing portion of the luminaire. In particular, it would be possible in this case for the luminaire to be an escape sign luminaire, wherein then in this way a particularly simple and elegant indication, on the one hand, and illumination of an escape route, on the other hand, are rendered possible. The concept in accordance with the invention, however, is not limited to the illumination of escape routes, but can basically be used whenever the light-radiation characteristic of a lighting arrangement is to be adapted in a simple way. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
       The invention will be explained in greater detail in the following with reference to the enclosed drawing, in which: 
         FIG. 1  shows the view of an escape sign luminaire in which the lighting arrangement in accordance with the invention has been integrated in order to illuminate an escape route; 
         FIG. 2  shows the arrangement of the optical element for asymmetrical light-delivery in the case of the luminaire of  FIG. 1  in a sectional representation; 
         FIGS. 3 and 4  show views of the lens that is used in the case of the lighting arrangement in accordance with the invention; 
         FIGS. 5 a  and 5 b    show two alternative arrangements of the optical elements in the case of the escape sign luminaire shown in  FIG. 1 ; and 
         FIGS. 6 a  and 6 b    show the light-distribution curves that result with the arrangements of the lenses according to  FIGS. 5 a    and  5   b.    
     
    
    
       FIG. 1  shows, as a preferred example of application and exemplary embodiment, a so-called escape sign luminaire, provided with reference numeral  100 , that is used to present an evacuation route. In a known way, this luminaire  100  has a circumferential frame  101 , which is used to support one or two transparent panes  102  for light-delivery. The frame  101  and the panes  102  form a housing of the luminaire  100  in whose interior space light sources are arranged. The light is then delivered by way of the transparent panes  102 , with the panes  102  containing a pictogram by way of which, for example, the direction of the evacuation route is indicated. Such escape sign luminaires are already sufficiently well known and are arranged at relevant positions within a building or the like in order to indicate evacuation routes. The light-delivery can then be effected on one side or two sides, depending on whether the luminaire is arranged in the centre of a room or corridor or on the wall above an emergency exit. 
     The special feature of the escape sign luminaire  100  shown in  FIG. 1  consists in the fact that in addition it also has means for illuminating the escape route. In the present case, these means are integrated into the luminaire  100 , although they could of course also be used independently of such an escape sign luminaire  100 . Integration affords in a particularly simple and elegant way the possibility of not only indicating an escape route, but also of lighting it. 
     The means in accordance with the invention of illuminating the escape route consist, in the exemplary embodiment shown, of two light sources and also of optical elements respectively associated with the light sources. The light sources are preferably formed by LEDs  10 , which are arranged within the luminaire  100  and are supplied with current by suitable means that are not described further. Associated with each LED  10  there is an optical element in the form of a lens  15  by way of which the light emitted from the LED  10  is delivered. The lenses  15  in this connection are arranged on the frame  101  of the escape sign luminaire  100  and engage in particular into corresponding openings  105  of the frame  101 . 
     The more precise configuration of the lenses  15  can also be inferred in particular from  FIGS. 3 and 4 . An object of these lenses  15  is to receive the LED light in an efficient way and to radiate it in a desired direction. For this purpose, the lenses  15 , which are of identical construction, in the first instance each have a conical region  16  facing the LED  10 . This conical region  16  is provided with a cavity  17  into which the LED  10  easily projects in the final assembly state (see  FIG. 2 ). As a result of this arrangement it is guaranteed that the light that is emitted from the LED  10  is almost completely delivered by way of the lens  15  and can thus be influenced in a desired way. The lateral surface and base surface of the cavity  17  consequently form a light-entry surface for the lens  15 , wherein the base surface is preferably formed so as to be slightly curved, this having the advantage that the light falls substantially in parallel onto the light-exit region  18  of the lens  15  and consequently can be influenced in an effective manner. 
     This light-exit region  18  of the lens  15  is configured in such a way that asymmetrical light-delivery is attained; the light is thus deflected and delivered in a targeted manner in a specific direction. In the exemplary embodiment shown, the light-exit region  18  of the lens  15  is provided with a so-called Fresnel structure for this. It thus has a plurality of fins  19  which are arranged next to one another in parallel and are formed in a wedge-shaped manner and by way of whose flanks the light is influenced in such a way that the asymmetrical light-radiation that is striven for is attained. To be exact, in the present case the light is reflected totally at the inclined flanks of the fins  19  in such a way that light-delivery as indicated in  FIG. 2  results. 
     The use of this Fresnel structure has the advantage that the overall height of the lens  15  can be reduced. The light-exit side of the lens  15  could, however, also be shaped in another way in order to attain the asymmetrical light-radiation that is striven for. A wedge-like configuration or a cylindrical structural form which is cut across an oblique surface would also be possible, for example. 
     The support of the lens  15  in the assembly opening  105  of the frame  101  is effected with the aid of four snap-action arms  20  which are arranged so that they are distributed over the periphery of the conical region  16  of the lens  15 . These snap-action arms  20  have a certain flexibility so that they can yield easily when the lens  15  is pushed in from the underside. If the lens  15  is inserted sufficiently deeply, the arms  20  snap outwards and engage with corresponding latching lugs  21  behind corresponding projections that can be formed on the frame  101  or—as shown—on the lateral panes  102  of the escape sign luminaire  100 . 
     The possibility then exists in accordance with the invention, for each of the two lenses  15 , to position the lens  15  in various rotational positions in relation to a longitudinal axis I (see  FIG. 4 ), which is defined by the alignment of the associated LED  10 . As a result of the rotationally symmetrical configuration of the region  16  of the lens  15  that faces the LED  10  and also the arrangement of the latching arms  20  the lens  15  can then be turned freely with respect to this axis I so that in principle any position would be possible. Specific preferred positions are, however, preferably defined in which the lens  15  is additionally latched with the housing of the luminaire  100 . In the example shown, additional knobs  22  are provided for this on the lens  15  which, when one of these preferred positions is reached, engage into corresponding depressions—not shown—that are formed on the frame  102 . In accordance with the arrangement of the knobs  22  shown, there are therefore four preferred positions, which are respectively rotated by 90° with respect to each other. In other words, the lens  15  can be secured to the frame  101  of the luminaire  100  whilst being aligned in four different directions. 
     Other possibilities of defining corresponding preferred positions for the lenses would also be possible. Thus, for example, the assembly opening in the frame  101  could be formed not so that it is circular, but as a polygon, wherein then as a result of corresponding configuration of, for example, the latching arms  20  insertion of the lens  15  is only rendered possible in specific positions. Furthermore, it would also be possible for no preferred positions at all to be defined, but instead for the lens  15  to be able to be turned freely, except that because of corresponding jamming between the lens and the housing frame  101  the lens  15  is guaranteed to remain in the set position. It is, however, fundamentally important that the possibility exists of setting the radiation direction of the light freely by corresponding selection of the position of the lens  15 . 
     The possibility therefore now exists, for example, of aligning the two lenses  15 , as shown in  FIGS. 5 a  and 5 b   . Whilst in the case of the variant in accordance with  FIG. 5 a    the lenses  15  are diametrically opposed, that is, they are oriented so as to be turned by 180° with respect to each other, the lenses in  FIG. 5 b    are aligned in the same way. In the case of the arrangement in accordance with  FIG. 5 a   , a light-radiation characteristic, as it is shown in  FIG. 6 a   , then results overall for the lighting arrangement. Symmetrical light-delivery extending in two directions is thus attained. This corresponds to the light-delivery as was hitherto used in most cases in escape route lighting. Such a light-radiation characteristic would thus be suitable in particular in such cases in which the escape sign luminaire  100  is located substantially in the centre (viewed in the longitudinal direction) of an escape route that is to be illuminated. A section of the escape route is then illuminated with the aid of the lighting arrangement in accordance with the invention on both sides of the luminaire  100 . 
     In the position in accordance with  FIG. 5 b   , on the other hand, the light is delivered through both lenses  15  in the same direction, and the asymmetrical light-radiation characteristic that is shown in  FIG. 6 b    results. This is suitable in particular in such cases in which the escape sign luminaire  100  is located above an emergency exit, and the region of the escape route towards the emergency exit is to be illuminated. 
     It is obvious, furthermore, that the lighting arrangement in accordance with the invention in particular is also very well suited for illuminating bends or corners of an escape route. In this case, the lenses would have to be aligned in such a way that the light-delivery follows in two beams turned by 90°. Furthermore, it would also be possible for more than two light sources with associated lenses to be used in order to be able to illuminate, for example, branches, intersections or the like. In all cases, however, the use of specially configured optical elements is not necessary; instead the adaptation of the light-radiation characteristic can be effected solely by corresponding setting of the lenses. This means that the light-radiation characteristic can be adapted to special wishes very simply and effectively and, in particular, however, also cost-effectively. 
     Furthermore, it would also basically be possible within the scope of the present invention for merely one single light source with associated adjustable optics to be used. Admittedly in this case merely illumination along a straight line or a line is possible, that is, bends or corners of an evacuation route cannot be illuminated so well, yet the possibility still exists of changing the alignment of this straight line or line. For example, this would be helpful if a tunnel that is not straight, but follows a bend or curved track is to be illuminated. 
     A possible further development of the invention can also consist in using a further or additional element that influences the light and is arranged downstream of the optical element in the light path. This additional light-influencing element could, for example, be mounted in a rotatable manner onto the lens—which is preferably still arranged on the housing so that it can be positioned in a rotatable manner or in different positions, as described above. These elements can then be transparent lenses, plastics rings or reflectors, partly coated with aluminium or similar by vapour deposition, or semi-mirrors, that is, elements which are partly permeable to light and partly mirror-coated. With the aid of these additional elements, the light-delivery could then be further adapted to the special requirements. Thus, for example, the direction of the lighting could be fixed by means of the first lens, and the width and/or horizontal inclination of the light beam could be set with the aid of the additional light-influencing element. 
     This further development just described is of course also possible both in the case of the use of a single light source and in the case of the employment of a plurality of light sources. Furthermore, in this case the lens, that is, the first optical element, need not necessarily deliver light asymmetrically, but could also bring about symmetrical light-delivery. In this case, the additional element could be utilized, for example, to change between symmetrical and asymmetrical light-delivery or vice versa. 
     Finally, it is also to be pointed out that the concept in accordance with the invention is not limited to the illumination of escape routes, but could also be used in other cases in which adaptation of the light-distribution characteristic is desired. In particular, use as a so-called wallwasher with which wall regions are illuminated would also be possible. In this connection, adaptation of the light-radiation can then be effected in a simple way, depending on whether the lighting arrangement is located on the longitudinal side or in a corner region of a room.