Patent Publication Number: US-8113685-B2

Title: Lighting device comprising at least one lamp and at least one OLED

Description:
FIELD OF THE INVENTION 
     The present invention relates to a lighting device comprising at least one lamp and at least one OLED. 
     BACKGROUND OF THE INVENTION 
     Lighting devices or lamp systems comprising different light sources are known in the art. For instance, U.S. Pat. No. 6,688,753 describes a lighting device comprising a first lighting element, preferably a compact fluorescent discharge vessel, and a second lighting element preferably comprising a plurality of LEDs. During operation, the first lighting element has a comparatively high light output. In operation, the second lighting element has a light output which is relatively low in comparison with that of the first lighting element. The first or the second lighting element, or both can be switched on. The lighting device allows remote-controlled switching between orientation light (night lamp) and normal light, using a toggle function in the lighting device. 
     US 2005/0265023 also describes a hybrid system for illumination, comprising a gas discharge lamp with a color point in the green-blue, a LED with a color point in the yellow-red, and an optical component for additive mixing of the light from the gas discharge lamp and the LED. A blue and green emitting fluorescent lamp is particularly suitable as a gas discharge lamp, and a red-yellow emitting AlGaInP LED or a red-emitting AlGaAs LED as a LED. Through additive mixing of the light from these high-efficiency light sources, US 2005/0265023 provides a highly efficient light source affording good color rendering, which contains the three primary colors and is particularly suited to the highly efficient generation of white light. 
     OBJECT AND SUMMARY OF THE INVENTION 
     These prior-art lamps have one or more drawbacks of being unable to provide a lamp with two (separate) beams, for instance, one for illuminating objects and the other having a luminance function, or they have a complicated or voluminous construction. 
     It is an object of the invention to provide an alternative lighting device, which preferably further obviates one or more of the above-mentioned drawbacks. In a specific embodiment, it is an object of the invention to provide a lighting device in which the at least one lamp and the at least one OLED provide beams of light which may leave the device at different angles. 
     In accordance with a first aspect of the invention, a lighting device comprises (a) at least one lamp which is arranged to generate light and (b) at least one OLED which is arranged to generate light, wherein the at least one OLED is arranged to transmit at least part of the light generated by the at least one lamp. 
     In a specific embodiment, a lighting device according to the invention further comprises a beam manipulator which is arranged to manipulate at least part of the light of the at least one lamp and illuminate at least part of the at least one OLED with manipulated light. The OLED transmits at least part of the (manipulated) light generated by the lamp. 
     In yet another specific embodiment, the invention provides a lighting device wherein the lamp and the beam manipulator are arranged to manipulate the light of the at least one lamp into a beam, and the at least one OLED is arranged to provide light substantially outside the beam of the (manipulated) lamp light. 
     In a specific embodiment, the invention provides a lighting device wherein the at least one lamp is arranged to generate light into a first beam and the at least one OLED is arranged to generate light into a second beam, wherein, relative to a normal to the at least one OLED, the first beam has a cut-off angle β 1  and the second beam has a cut-off angle γ 2  and optionally a cut-off angle γ 1 , and wherein γ 2 &gt;γ 1  and preferably γ 2 ≧β 1 . 
     The lighting device of the invention may advantageously allow the option of providing two types of light, “normal” of the lamp, which can be used, for instance, for illumination purposes, and OLED light of the OLED, which can be used for lumination purposes. 
     Furthermore, embodiments of the lighting device according to the invention may fulfill (at the same time) the functions of, for instance, an illuminance system for e.g. general shop-lighting, and a luminance system for e.g. indication lighting. For instance, in a shop, the lighting device may provide general lighting by the lamp and lumination light, depending on the types of goods presented in a specific part of the shop. The two types of light generated by the lighting device according to the invention may also be used to give color effects. Furthermore, the lighting device of the invention may also provide the functions of orientation light (night light) or escape indication (OLED) and illumination (lamp). These multiple functions may be executed at the same time or consecutively. Other embodiments enable the lighting device to provide light having a “corona” effect. 
     The lighting device according to the invention has the further advantage that relatively small devices may be constructed and, as mentioned above, more functions can be combined in one lighting device. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Embodiments of the invention will now be described, by way of example only, with reference to the accompanying schematic drawings in which corresponding reference symbols indicate corresponding parts. 
         FIG. 1  is a schematic side view of an embodiment of the lighting device of the invention, such as a downlight or TL luminaire; 
         FIGS. 2   a - 2   d  schematically depict in more detail the OLED and a window pane comprising the OLED, respectively, for use in the lighting device of the invention; 
         FIGS. 3   a - 3   h  schematically depict embodiments of the OLED and ray-tracing figures; 
         FIG. 4  is a schematic side view of another embodiment of the lighting device of the invention; 
         FIG. 5  is a schematic side view of yet another embodiment of the lighting device of the invention; 
         FIG. 6  is a schematic top view of another embodiment of the lighting device of the invention; 
         FIG. 7  is a schematic side view of yet another embodiment of the lighting device of the invention; 
         FIGS. 8   a - d  schematically depict specific light distributions that can be achieved with the lighting device of the invention; and 
         FIG. 9  is a schematic side view of yet another embodiment of the lighting device of the invention. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     Referring to  FIGS. 1 ,  4  to  7 , and  9 , the present invention provides a lighting device  1  comprising:
     (a) at least one lamp  10  (also indicated as source  10 ) which is arranged to generate light  11 ; and   (b) at least one OLED  20  (also indicated as source  20 ) which is arranged to generate light  21 , wherein the at least one OLED  20  is arranged to transmit at least part of the light  11  generated by the at least one lamp  10 . As can be seen in the Figure(s), the at least one lamp  10  is arranged to illuminate (or irradiate) at least part of the at least one OLED  20 , which (during operation of the device  1 ) transmits at least part of the light  11  generated by the at least one lamp  10 .   

     The light generated by device  1 , i.e. the light generated by both sources  10  and  20 , is denoted by reference numeral  32 . The light generated by the two sources  10 ,  20  may be separated substantially angularly, as is especially indicated in  FIGS. 2 to 5 , but may also substantially overlap, as is indicated, for instance, in  FIG. 6 . Hence, in embodiments, light  32  generated by lighting device  1  may comprise two or more beams which may be angularly separated. The term “angularly separated” refers to the situation in which an observer can distinguish different beams dependent upon the viewing angle. 
     The individual light sources  10 ,  20  of the lighting device  1  will first be described in general below, and embodiments of the lighting device  1  will then be described in more detail. 
     The Light Sources (Lamp  10  and OLED  20 ) 
     The at least one lamp  10  may comprise one or more lamps selected from the group of filament lamps, fluorescent lamps (especially tubular luminescent (TL) lamps and compact fluorescent lamps (CFL)), halogen lamps, low-pressure gas discharge lamps, high-pressure gas discharge lamps, LEDs, and optionally also OLEDs. The at least one lamp  10  is preferably suitable for illumination purposes, ranging from low-flux applications for consumer use, typically at more than about 50 Lm (lumen), via about 3000 Lm application in office lighting to high-flux applications as used in industry and stadium lighting, where the flux per lighting device can exceed about 5000 or even 10,000 Lm. Hence, the at least one lamp is able to provide a luminous flux (further indicated as flux) of light selected from the range of about 25 to 20,000 Lm. In an embodiment, the at least one lamp  10  has a variable flux. Lamp  10  preferably comprises one or more lamps selected from the group of low-pressure gas discharge lamps (CFL, TL) and LEDs. Herein, the term “LED” or “LEDs” (light-emitting diode or diodes) does not include an OLED or OLEDs (organic light-emitting diode or diodes). The lamps  10  described herein may be lamps known to the person skilled in the art. 
     The term “at least one lamp” includes embodiments wherein more than one lamp is used, i.e. a plurality of lamps, for instance, a number of LEDs, such as two or more LEDs or a system of two fluorescent lamps with different color temperatures (as described in, for instance, US2005/0225986 or WO2003048634). Herein, the notation “lamp” also indicates “at least one lamp”. Hence, the terms “at least one lamp” or “lamp” refer to one or more lamps. 
     The at least one OLED  20  may comprise one or more OLEDs. Herein, the notation “OLED” also indicates “at least one OLED”. Hence, the terms “at least one OLED” or “OLED” refer to one or more OLEDs, i.e. a plurality of OLEDs. 
     OLED performance has improved with time and is expected to improve even further in the future to a level at which they can even be applied in illuminance lighting devices. Nowadays, OLEDs can already be applied in luminance applications. In comparison with other light sources, OLEDs have unique features such as flatness, flexibility, and transparency when they are off and in operation. Generally, the performance of most commercially available OLEDs does not yet meet the illuminance standard. This may still stand in the way of applying OLEDs (now commercially available) on the general lighting market, but this may be different in the near future. They are, however, perfectly suited for luminance effects. 
     OLEDs are known in the art. However, for the sake of understanding, an embodiment of such OLEDs will herein be described schematically. Two types of OLEDs can be distinguished:
         OLEDs in which the active layer is a polymer (PolyLeds); and   OLEDs in which the active layer is a Small molecule (SmOLEDs).
 
The OLED device consists of an active layer, a cathode, an anode and a substrate. The active organic layers consist of a hole transport layer (for instance, about 100 nm) and the light-emitting polymer (for instance, about 80 nm) for the polymer-based organic LED. The small-molecule version of an organic LED consists of some more layers: hole injecting, emitting, hole blocking and electron transport layer. The emitting OLED layer is a hydrocarbon-based structure, for instance, manufactured by well-known suppliers, such as Kodak, Mitsubishi and Konica Minolta. The OLED active layer is mounted on a substrate which may be sputtered with, for instance, indium tin oxide (ITO), thereby forming an ITO layer of about 150 nm to function as a hole-injecting electrode. The cathode applied on top of the organic layers may ensure that electron injection is of the order of 100 nm. When the substrate and both the cathode and anode material are chosen from the transparent conductor oxide group of materials, e.g. an ITO type of material, a transparent device can be constructed. Overall, the complete stack in both organic LEDs does not generally exceed about 200 nm. The devices can be encapsulated by means of thin-film encapsulation which, in total, may form an additional layer of about 10 μm (about 0.6 μm of actual barrier and several μms of additional protective coating). The thickness of a device is therefore mainly determined by the substrate thickness. In the case of glass encapsulation, the minimum thickness used is about 0.4 mm which is roughly four times the thickness of 80 gram/m 2  paper often used in printed matter. Nowadays, the area can be extended to page-like dimensions. The performance of state-of-the-art emitting polymers is improving rapidly. The brightness level of the OLED can be adjusted by changing the current/voltage settings of the power source, as OLEDs are current-driven. All this is known in the art.
       

     White emitting OLEDs are known to have a brightness of about 50 Cd/m 2 : 3 V, 3 mA/cm 2  (1.5 lum), efficiencies of 12 Cd/A have been reported for small-molecule devices. 
     The at least one OLED  20  preferably generates light with a saturated color (i.e. a purity of at least 70%). This is useful for indication. Alternatively, also a stack of OLEDs with different colors can be used, which may result in a tunable indication color of the luminaire (see also below). 
       FIG. 2   a  schematically depicts an OLED  20  with an organic layer  22  sandwiched between a first layer  23  and a second layer  24 , which layers comprise the above-mentioned substrate or substrates and/or electrodes, etc., as known in the art. The details of the substrate or substrates and anode or anodes/cathode or cathodes, etc. are not further described or depicted, see also above. This is known in the art, see e.g. M. Fujita et al., Electronics Letters, 27 Nov. 2003, vol. 39 (24) or N. K. Patel et al., IEEE Journal on selected topics in quantum electronics, vol. 8 (2), March/April 2002, pages 346-361. The thickness d 20  of the OLED  20 , including a substrate, is generally in the range of about 0.3 to 20 mm. 
     In general, prior-art OLED devices further comprise specific structures at one or more of the interfaces of organic layer/ITO layer-substrate and substrate-air. These structures are necessary to couple the light generated in the organic layer  22  (efficiently) out of the OLED  20 , see e.g. also Patel et al., who describe structures such as surface roughness, silica microspheres, microlenses, etc. Other structures for improving outcoupling of the light are also possible. When these structures are present at both sides of the organic layer  22 , and transparent electrodes/substrates are used, light is emitted in both directions relative to the organic layer (in  FIG. 2   a , OLED light would escape from faces  20   a  and  20   b ); when such structures are only arranged at one side (i.e. at face  20   a  or face  20   b ), and, for instance, a reflective layer is present at the other side, light generated in the organic layer is substantially emitted in one direction (in  FIG. 2   b , OLED light would escape from faces  20   a  or  20   b ). In a preferred embodiment, these structures are absent, at least at the above-mentioned interfaces, see also below. Hence, in an embodiment, no structures are provided to enhance the output coupling from OLED light from face  20   a  and/or face  20   b . Faces  20   a  and  20   b  are external surfaces of the OLED (i.e. of first layer  23  and second layer  24 , respectively) which are arranged in parallel with the organic layer  22 , as known in the art. 
     The OLEDs used herein are transparent. Transparent OLEDs have only substantially transparent components (substrate, cathode and anode) and, when turned off, are preferably at least 50% transparent, preferably at least about 70%, more preferably at least up to about 85% or more. When the transparent OLED is turned on, it allows light to pass in both directions. The OLEDs used in the invention are preferably at least 50% transparent to the visible light  11  generated by the at least one lamp  10 , especially when (one or more of the) at least one OLED is switched on (is in operation), and preferably at least about 70%, more preferably at least 85% transparent. Here, the phrase “at least 50% transparent” means that the transmission throughout the visible wavelength range (i.e. within the range of 380-780 nm) of the light  11  generated by the at least one lamp  10  will be transmitted for at least 50% by the at least one OLED  20  when the OLED  20  is in operation and when assuming perpendicular irradiation with such light  11 . 
     OLEDs may be foldable, which is of special relevance for application on curved surfaces, as depicted in  FIG. 6  (see also below) or bent surfaces. Foldable OLEDs have substrates, cathodes, anodes, etc. made of flexible metallic foils or plastics. Foldable OLEDs are known in the art. 
     The term “light” herein especially refers to visible radiation (VIS), i.e. radiation in the range of about 380-780 nm. In an embodiment, the light generated by the one or more lamps  10  or by the one or more OLEDs  20  comprises white radiation (i.e. white light), although in another embodiment one or more of these light sources  10 ,  20  may also produce colored light. Commercially available lamps  10  and transmissive OLEDs  20  emitting (white) light may be used. When the at least one lamp  10  comprises more than one lamp, such as a plurality of LEDs, or when the at least one OLED  20  comprises more than one OLED, the respective lamps or respective OLEDs may generate radiation of different colors. For instance, a set of blue, green and red LEDs may be used as lamp  10 . When such multiple sources with multiple colors (of the generated light) are used as lamp  10 , these sources are preferably arranged to be able to generate white light (by color mixing). 
     The Lighting Device  1   
     As mentioned above, the at least one OLED  20  is arranged to transmit at least part of the light  11  generated by the at least one lamp  10 . In the device  1 , the at least one lamp  10  is arranged to illuminate at least part of the at least one OLED  20 . Due to the fact that the OLED  20  is transmissive, at least part of the light  11  generated by the at least one lamp  10  is transmitted by the at least one OLED  20 . Such a configuration, as schematically depicted in, for instance, the embodiments of  FIGS. 1 and 4  to  7 , allows a relatively compact arrangement of the two sources  10 ,  20 . 
     The embodiment of the lighting device  1  in  FIGS. 1 ,  4 ,  5  and  7  further comprises a housing  50 . The housing  50  has at least one opening  52  (or window), through which light  11  of the at least one lamp  10  can escape from the interior of the housing. In a further embodiment, the lighting device  1  has only one opening  52 , arranged to allow light  11  to escape from the lighting device  1 , i.e. housing  50  has only one opening  52 . The lamp  10  is circumferentially arranged in housing  50 . The embodiments schematically depicted in  FIGS. 1 ,  4 ,  5  and  7  especially refer to side views of downlight lighting devices or TL office lighting devices. The term “downlight” is known to the person skilled in the art and generally refers to a luminaire in which most of the light is directed downwards, in particular to a floor or the ground. The lighting device  1  may also be termed luminaire. 
     The opening  52  may comprise the at least one OLED  20 . For instance, the one or more OLEDs  20  may be arranged within opening  52  or at one side of this opening  52 . In  FIG. 1 , the at least one OLED  20  is arranged substantially at one side of the opening  52 , but as will be clear to the person skilled in the art, the shape of housing  50  and opening  52  may have any geometry, and concomitantly, the arrangement of the at least one OLED  20  in the lighting device  1  may be chosen by the person and/or designer skilled in the art, on condition that at least part of the light  11  of the at least one lamp  10  irradiates the at least one OLED  20  (which transmits at least part of this light  11 ). The at least one OLED  20  may be integrated within, in front of or behind opening  52  in any way known to the person skilled in the art. Hence, the at least one OLED  20  will at least partly be arranged as a kind of window pane (denoted by reference numeral  40 ), through which at least part of the light  11  of lamp  10  will be transmitted. This window pane  40  may be the (at least one) OLED  20 , or it may be a transmissive material wherein and/or whereon the at least one OLED  20  is arranged (see also below). In either case, when the OLED is in operation, the transmission of the window pane  40  for the visible light  11  of the at least one lamp  10  is at least 50%, preferably at least 70%, more preferably at least 85%, assuming perpendicular irradiation (see also above). 
     The lighting device  1  according to the invention may further comprise one or more beam manipulators  30  arranged to manipulate at least part of the light  11  of the at least one lamp  10  and illuminate at least part of the at least one OLED  20  with manipulated light. The beam manipulator  30  may comprise one or more devices selected from the group of reflectors and collimators. Due to the geometry of the lighting device  1  (especially housing  50  and the arrangement of the at least one lamp  10  relative to housing  50 ) and/or the beam manipulator  30 , light  11  leaves the device  1  as beam  18 . 
     The housing  50  preferably further comprises an at least partly reflective wall  51 , also indicated as reflector or reflectors  51 , as beam manipulator  30 . Reflective elements or reflective coatings or layers are known to the person skilled in the art. At least part of the internal wall of housing  50  is preferably reflective. More preferably, substantially the whole internal wall of the housing  50  that receives light  11  from the at least one lamp  10  comprises reflective wall  51 . In this way, light  11  of the at least one lamp  10  is substantially collimated on opening  52  (i.e. on at least part of the at least one OLED  20 ). Hence, in these Figures, beam manipulator  30  comprises a reflective layer, coating or element, which at least partially encloses the at least one lamp  10  and is arranged to manipulate at least part of the light  11  of the at least one lamp  10  (into a beam  18 ). 
     The beam manipulator  30  may also comprise a collimator. For instance, lamp  10  may comprise one or more LEDs having one or more collimators to collimate the light of the one or more LEDs. Each LED may have one collimator, respectively, but a plurality of LEDs may also have one collimator. LEDs with collimators or sets of LEDs with collimators are known in the art. 
     Hence, in a specific embodiment, the invention provides a lighting device  1  further comprising (at least one) beam manipulator  30  which is arranged to manipulate at least part of the light  11  of the at least one lamp  10  and illuminate at least part of the at least one OLED  20  with the manipulated light  11 . The transparent OLED or OLEDs transmit at least part of the light  11  collimated by beam manipulator or manipulators  30  and illuminated by this (collimated) light. In these embodiments, the at least one OLED  20  is arranged within, in front of or behind opening  52 , such that the manipulated light  11  of the at least one lamp  10  illuminates the at least one OLED  20  and through which at least part of the manipulated light  11  is transmitted. In an embodiment, preferably at least 40%, more preferably at least 70%, more preferably at least 90% of total flux of the light  11  of the at least one lamp  10  illuminates the at least one OLED  20  (see further also below). As will be clear to the person skilled in the art, one or more of the geometries of the housing  50 , including the opening  52 , the arrangement of the at least one lamp  10  relative to housing  50  and the optional presence of one or more beam manipulators  30 , direct at least part of the total flux (preferably at least 40%) of the light  11  of the at least one lamp  10  towards the at least one OLED  20  (comprised in opening  52 ), and beam  18  is generated. 
     In  FIGS. 1 ,  4 ,  5  and  7 , the opening  52  comprises window pane  40 , which is at least partially transparent to light  11  of lamp  10 . The window pane  40  may consist of one or more OLEDs  20 , i.e. window pane  40  is the at least one transparent OLED as described herein, or window pane  40  may comprise one or more transparent OLEDs, for instance, arranged in or on a glass plate (see below). Hence, the term “window pane” refers to a transparent device such as a plate, which is arranged within, in front of or behind opening  52  and comprises the one or more OLEDs  20 . The window pane  40  is preferably flat, although in an embodiment also a curved window pane  40  may be applied. The preferred embodiments herein depicted schematically ( FIGS. 1 ,  4 ,  5 , and  7 ) comprise substantially flat window panes  40 . Hence, in a specific embodiment, the at least one lamp  10  is arranged in a beam manipulator  30  which is arranged at least partially circumferentially and further comprises window pane  40  which comprises the at least one OLED  20 . The window pane  40  is arranged to transmit at least part of the light  11  from lamp  10 . 
     Window pane  40  may be, for instance, a glass plate or a transparent plastic or any other substantially transparent material, on or in which the at least one OLED  20  is arranged. For instance, especially when the OLED  20  is not foldable, for instance, in cases where the substrate is made of glass, window pane  40  may be the one or more OLEDs  20 . 
     However, in another embodiment, as schematically depicted in  FIG. 2   d , the one or more OLEDs may also be comprised in a sheet, for instance, glass (the OLED or OLEDs  20 ), or may be sandwiched between glass plates or transparent plastic. 
     The window pane  40  has a thickness d 40  which is in the range of d 20  (when the window consists of one or more OLEDs) to about 20 mm (when the window comprises a transparent plate wherein and/or whereon the OLED or OLEDs are arranged), such as about 0.3-20 mm, although a larger thickness is also possible. When more OLEDs of different colors are used in one luminaire, they can be arranged on top of or next to each other. 
     Transparent materials which can be used to incorporate the OLED (for instance, in a sandwich structure), and/or on which the OLED may be applied, may be selected from, for instance, the group of glass, polymethyl acrylate (PMA), polymethyl methacrylate (PMMA) (Plexiglas or Perspex), cellulose acetate butyrate (CAB), polycarbonate, polyvinyl chloride (PVC), polyethylene terephthalate (PET), and glycol modified polyethylene terephthalate (PETG), which materials may be provided as transparent sheets. In another embodiment, the sheet material comprises an acrylate, for instance, PMA or PMMA, especially PMMA. Such materials are also known in the art as transparent plastics. In yet another embodiment, the sheet comprises transparent plastics commercially known as PERSPEX™ or PRISMEX™. Other substantially transparent materials known to the person skilled in the art may also be used. Combinations of two (or more) materials may be used. 
     The embodiments as schematically depicted in  FIGS. 1 ,  4 ,  5  and  7  may have the specific advantage that a lighting device  1  can be provided which is arranged to provide two beams, one beam substantially comprising light  21  generated by the one or more OLEDs  20 , and one beam substantially comprising light  11  generated by the one or more lamps  10 . The OLED  20  is a Lambertian radiator, emitting light to all directions. This means that, especially with the current OLED performance, in the beam of the traditional lamp, the OLED  20  may have a relatively low flux in comparison with the flux of a “traditional” lamp, and may even not be perceivable by an observer. Outside the beam of the traditional lamp, the OLED light will become visible and luminance indication lighting, etc. can be obtained. 
     In the embodiments schematically depicted in  FIGS. 1 ,  4 ,  5  and  7 , a lighting device  1  is provided, wherein the lamp  10  and the optional beam manipulator  30  are arranged to manipulate light  11  into a beam  18  and the at least one OLED  20  may be arranged to provide light  21  substantially outside the beam  18 . The term “substantially outside the beam  18 ” herein refers to the situation in which the cut-off angles (see also below) at which these beams  18  and  28  leave lighting device  1  substantially do not coincide. In this way, a lighting device  1  may be provided wherein the at least one lamp  10  and the at least one OLED  20  provide beams of light  18 ,  28  which are separated substantially angularly and thus leave the device  1  at different angles. For instance, this may be due to the fact that beam  18  substantially leaves the lighting device  1  at one or more positions spatially separated from positions where beam  28  substantially leaves the lighting device  1 . Alternatively, or in combination with the above, this may also be due to the fact that beam  18  substantially leaves the lighting device  1  at angles different from angles at which beam  28  substantially leaves the lighting device  1 . 
     This is further elucidated with reference to  FIGS. 2   a  to  3   h .  FIGS. 2   a  to  3   h  schematically illustrate how this can be achieved in embodiments of the invention. The result is shown in  FIGS. 3   b  to  d ,  3   f  to  h , and in the schematic  FIGS. 2   c ,  4  and  5 . As mentioned above, the OLED  20  has a first face  20   a  and a second face  20   b , which are substantially parallel to the organic layer  22 . As mentioned above, prior-art OLEDs generally have structures to promote coupling of light (from the organic layer) out of the device, i.e. from first face  20   a , or second face  20   b , or from both faces  20   a  and  20   b , for instance, in the direction perpendicular to faces  20   a  and/or  20   b . Furthermore, the device  20  has edges  20   c,  substantially perpendicular to faces  20   a  and  20   b . Edges  20   c  may refer to one or more edges  20   c . Edges  20   c  are the edges of the device  20  which are arranged substantially perpendicularly to the organic layer; edges  20   a  and  20   b  are the external faces of the first and the second layer, respectively, which are substantially parallel to the organic layer  22  in OLED  20 ; i.e. the front and back face, respectively, of the OLED  20 . 
     However, in the invention, also due to the preferred absence of structures for improving outcoupling of light at one or more of the interfaces  22 - 24 ,  22 - 23 ,  24 -outside or  23 -outside, light  21  will leave the OLED  20  at all surfaces  20   a ,  20   b  and  20   c , but preferentially at the side surfaces or edges  20   c . This is indicated in  FIGS. 3   a ,  3   b  and  3   c . A commercially available optical ray-tracing program is used to simulate the OLEDs  20  output. 
     First, an OLED  20  having rectangular edges  20   c  ( FIG. 3   a ) is simulated (rectangular with respect to substantially parallel first and second faces  20   a  and  20   c ). In this case, the luminance on edges is three times higher than from the top surface  20   b  of OLEDs ( FIG. 3   b ). The edge luminous intensity distribution is shown in  FIGS. 3   c  and  3   d . The A-direction is parallel to the y-axis, the B-direction is parallel to the x-axis and the C-direction is parallel to the z-axis (see also  FIG. 4 ). This means that light  21  (essentially) comes from the edges  20   c , and assuming an arrangement parallel to floor and ceiling, illuminates in two directions: in the direction of the ceiling and of the floor. Likewise, this will apply to window panes  40  including the one or more OLEDs  20 . Then, OLED light  21  will leave the pane  40  at all surfaces  40   a ,  40   b  and  40   c , but preferentially at the side surfaces or edges  40   c . Edges  40   c  are the edges of the window pane  40  which are arranged substantially perpendicularly to the organic layer; edges  40   a  and  40   b  are the external faces of the pane  40 , respectively, which are substantially parallel to the organic layer  22  in OLED  20 ; i.e. the front and back face, respectively, of the OLED  20 . 
     In a preferred embodiment, however, OLEDs  20  having one or more tilted edges  20   c  are applied, as is schematically depicted in  FIGS. 2   c  and  3   d . This also includes window panes  40  having one or more tilted edges  40   c , as is schematically depicted in  FIG. 2   d .  FIG. 2   d  schematically depicts a window pane  40  comprising a plurality of OLEDs, which are integrated in a transparent material. The front and back faces  40   a  and  40   b  are essentially parallel to the organic layer or layers  20  of the OLED or OLEDs. The edge or edges  40   c  of window pane  40  may be tilted at an angle α. This means that window panes  40 , in and/or on which one or more OLEDs  20  are provided, may include tilted edges  40   c . Ray-tracing results of OLEDs having tilted edges  20   c  are shown in  FIGS. 3   f ,  3   g  and  3   h  (edge luminous intensity distributions). In this case, the light substantially comes from OLEDs  20  and substantially illuminates either the ceiling or the floor at a certain angle. In this case, the luminance on edges  20   c  or  40   c  may be at least about three times higher than from the top surface  20   b  of OLEDs  20 , but may even be higher. In  FIGS. 3   f  and  3   h , an OLED  20  is used with edges  20   c  having an angle α of about 45°; in  FIG. 3   g , α is slightly larger than 0°. 
     Hence, in a specific embodiment, a lighting device  1  is provided, which comprises at least one OLED  20  or a window pane  40  comprising at least one OLED  20 , wherein the at least one OLED or the window pane  40  comprising the at least one OLED  20  is arranged to emit light  21  substantially at edge  20   c  or  40   c , respectively. The term “substantially” herein refers to the situation in which at least 50% of the total flux of light  21  leaving the OLED  20  (or the window pane  40 ) leaves from the total external surface of these edges. Edges  20   c  and  40   c  relate to edges of the OLED or the window, which are perpendicular to the plane of the organic layer  22 , respectively, or optionally tilted. Alternatively or additionally, the edges have an end surface  20   f ,  40   f  which has a concave, convex or undulated shape along a normal  18   a  normal to the OLED  20 , as is shown in  FIG. 9 . In this way, a desired designed beam shape is obtained, which is suitable for special decorative illumination or illuminative effects. In  FIGS. 2   c  and  2   d , angle α reflects the tilt of the edges  20   c  and  40   c . In  FIG. 2   a , this angle α is 0°; α is preferably larger than 0° and smaller than 90° (1), or larger than 90° and smaller than 180° (2). Assuming a configuration in which the organic layer or layers  22  are substantially parallel to a ceiling (or floor), the former configuration (1) is advantageous for preferentially illuminating objects arranged below the device  1 , such as, for instance, a floor, and the latter configuration (2) is advantageous for preferentially illuminating objects arranged above the device  1 , such as, for instance, a ceiling. In this way, a device  1  is provided in which the beam  18  of light  11  generated by the at least one lamp  10  and the beam  28  of light  21  generated by the at least one OLED  20  may leave the device  1  in an angularly separated way. As can be seen in  FIGS. 3   b ,  3   c  and  3   d , on the one hand, and  FIGS. 3   f ,  3   g  and  3   h , on the other hand, the use of a tilted edge  20   c  or  40   c  leads to an increase and/or a redistribution of the light that escapes from edge  20   c  or  40   c . For instance, the relative symmetric distribution of light in an upward and downward direction in  FIG. 3   b  (tilt α=0) is changed in a distribution of  FIG. 3   f  with relatively more light directed downwards when using tilted edges. 
     For the sake of understanding, further reference is made below to window pane  40  only, which, as described above, may consist of one or more OLEDs  20  (see also above), or may comprise the one or more OLEDs  20 . 
     Hence, in an embodiment, the window pane  40  has at least one edge  40   c  which is tilted at angle α (tilt angle) relative to a normal to the at least one OLED  20 , wherein 0°&lt;α&lt;90° or 90°&lt;α&lt;180°. This normal is substantially parallel to a normal to front and bottom faces  40   a  and  40   b  (or  20   a  and  20   b ), respectively. In  FIGS. 2   b  and  2   d , both drawn edges (edges  20   c  in  FIG. 2   b  and edges  40   c  in  FIG. 2   d , respectively) have a tilt angle α. The tilt angle α may differ for each edge  40   c . The window pane may be circular and have one edge  40   c , or may have different shapes such as triangular, square, rectangular, etc. One or more of the edges may have the same tilt angle α. However, α may also vary along the edge or edges  40   c . In systems with an even number of edges  40   c  (≧2), wherein at least two edges  40   c  are arranged opposite each other, these opposite edges ( 20   c ) may be tilted independently at angle α. The term “independently” herein refers to the arrangement in which the tilt angle α may be the same for the opposite edges  40   c , but may of course also not be the same. Tilt angle α may vary over the edge or edges  40   c . This means that when there is more than one edge  40   c,  different edges  40   c  may have different tilt angles α, and/or one (circular) or more (triangular, square, rectangular, etc.) edges have a changing tilt angle α. Assuming rectangular or square panes  40 , two opposite edges  40   c  are preferably tilted independently at tilt angle α, both preferably having the same tilt angle α. 
       FIG. 4  shows a specific embodiment of a lighting device  1  in which beam  18  has a normal  18   a  to window pane  40  and beam  18  is substantially confined to a beam at an angle β 1  relative to the normal  18   a  to window pane  40 , and in which the at least one OLED  20  is arranged to generate light  21  into a beam  28 , the OLED beam  28  being substantially confined to a beam having a smallest angle γ 1  with respect to a normal  18   a  to window pane  40  and a largest angle γ 2  with respect to a normal  18   a  to window pane  40 . In fact, normal  18   a  is a normal to OLED  20  (or a normal to organic layer  22 ). Hence, γ 2 &gt;γ 1 ; γ 2 &gt;0°; preferably γ 2 ≧β 1  (in  FIG. 4 , γ 2  is larger than β 1 ); γ 1 &gt;0°; β 1 &gt;0°. 
     Here, a substantially flat window pane  40  is shown, but in other embodiments, the window pane  40  comprising the one or more OLEDs  20  may also be curved. As will be clear to the person skilled in the art, window pane  40  may also comprise a plurality of window panes, one or more of which comprise one or more OLEDs  20 . 
       FIG. 4  assumes a symmetric light distribution relative to the normal  18   a,  wherein angles β 1 =β 1 ′, γ 1 =γ 1 ′ and γ 2 =γ 2 ′. Herein, γ 2 &gt;γ 1 . Unless otherwise indicated, a substantially symmetric light distribution is assumed (mirror symmetry; see also  FIGS. 8   a,    8   b  and  8   d ). Furthermore,  FIG. 4  assumes a horizontal arrangement of lighting device  1 , i.e. window pane  40  is substantially parallel to the floor and ceiling. As will be clear to the person skilled in the art, the invention is not limited to such an arrangement. When, in  FIG. 4 , the observer would be positioned at  18 ′ and then move to the left or the right, he would experience substantially similar light distributions, see also  FIGS. 3   b ,  3   c ,  3   d ,  3   f ,  3   g  and  3   h;  likewise, the observer moving to the back or standing up might again experience substantially similar light distributions. Hence, when referring to β 1 , γ 1  and γ 2 , reference is also made to β 1 ′, γ 1 ′ and γ 2 ′, respectively, below, unless otherwise indicated. Note that these angles refer to a two-dimensional description of beams  18  and  28 , i.e. in the plane of X (or B) and Z (or C). As is known to the person skilled in the art, the light distribution in the plane of Y (or A) and Z (or C) may differ from the former (see also below in the description of  FIGS. 8   a  to  d ). 
     Furthermore,  FIG. 4  schematically depicts an embodiment in which lighting device  1  is arranged as, for instance, a TL lamp in a luminaire. As can be seen in  FIG. 4  (but also  FIGS. 5 and 7 ) most of the light  32  is directed downwards. Hence, angle  18 ′ is a right angle, which, in this substantially horizontal arrangement, can also be indicated as “nadir”. 
     In the schematic  FIG. 4 , which depicts one of the possible embodiments of the invention, two distinct lighting areas can be observed, one area  180 , which is substantially illuminated by beam  18  confined by angle β 1  (here β 1 =β 1 ′), and another area  280 , wherein lumination from the at least one OLED  20  is received in the form of beam  28  confined by angle γ 2  (here γ 2 =γ 2 ′). As will be clear to the person skilled in the art and, for instance, also from  FIGS. 3   b ,  3   c ,  3   d ,  3   f ,  3   g  and  3   h , the at least one OLED  20  may also irradiate at angles smaller than γ 1  (and γ 1 ′) in case γ 1 ≠0°. However, especially in the case in which α is smaller than 90° and larger than 0°, the flux between angles γ 1  (wherein γ 1 ≠0°) and γ 2  may be even more enhanced relative to the areas confined to γ 1  (see  FIG. 3   h ). 
     The angles γ 2  and β 1 , and in an embodiment also angle γ 1  especially refer to cut-off angles. The term cut-off angle is known to the person skilled in the art and refers to the angle formed by a line drawn from the direction of the direct light (i.e. beams  18  and  28 , respectively) at the light source with respect to a vertical (here the dash-dotted line to  18 ′), beyond which no direct light is emitted. The phrase “beyond which no direct light is emitted” is to be understood in the sense of European Standard EN I 12464-I (-SC/02168, revised Dec. 11, 2002), wherein the limit is set at a luminance of ≦1000 cd/m 2 . Hence, γ 2  and γ 1 , or γ 2  alone when γ 1 =0°, define beam  28  in a preferred embodiment, wherein, at angles smaller than γ 2  (and larger than γ 1  in case γ 1 ≠0°), the at least one OLED  20  of lighting device  1  provides a luminance of more than 1000 cd/m 2 , and at angles equal to or larger than γ 2  and equal to or smaller than γ 1  (if γ 1 ≠0°), the at least one OLED  20  of lighting device  1  provides a luminance of ≦1000 cd/m 2 . Likewise, β 1  defines beam  18  in a preferred embodiment, wherein, at angles smaller than β 1 , the at least one lamp  10  of lighting device  1  provides a luminance of more than 1000 cd/m 2  and at angles equal to or larger than β 1 , the at least one lamp  10  of lighting device  1  provides a luminance of ≦1000 cd/m 2 . Hence, when the lighting device  1  in this embodiment is in operation and an observer views the device  1  at a viewing angle equal to or larger than γ 2 , a luminance of the at least one OLED  20  and the at least one lamp  10  will be ≦1000 cd/m 2 . When the viewing angle is reduced and becomes smaller than γ 2 , but larger than γ 1  (if y≠0°), an OLED luminance of more than 1000 cd/m 2  will be observed. At angles smaller than β 1 , a lamp  10  luminance of more than 1000 cd/m 2  will be received. 
     Hence, in an embodiment of the lighting device, the at least one lamp  10  is arranged to generate light  21  into first beam  18 , and the at least one OLED  20  is arranged to generate light  21  into second beam  28 , wherein, relative to the normal to the at least one OLED  20 , the first beam  18  has a cut-off angle β 1  and the second beam has a cut-off angle γ 2  and optionally a cut-off angle γ 1 , and γ 2 &gt;γ 1 , preferably γ 2 ≧β 1 . At angles≧β 1 , the luminance of the lighting device  1  due to the first beam  18  and, at angles≧γ 2 , the luminance of the lighting device  1  due to the second beam  28  are preferably independently ≦1000 cd/m 2 . At angles&lt;β 1 , the luminance of the lighting device  1  due to the first beam  18  and, at angles&lt;γ 2  (and larger than if y≠0°), the luminance of the lighting device  1  due to the second beam  28  are independently &gt;1000 cd/m 2 . When γ 1 ≈0°, beam  28  has only one cut-off angle. 
     In a preferred embodiment, γ 2 &gt;β 1  (i.e. β 1 &lt;γ 2 ; β 1 &gt;0°). In this way, a lighting device  1  can be provided, wherein the “core” beam  18  can be used, for instance, for illumination, and the light in beam  28  provides a lumination effect: a light effect may be created around the beam  18  of the at least one lamp  10 , “similar” to a halo. 
     Especially in view of office applications, β 1  is preferably chosen to be 0&lt;β 1 ≦65° so as to circumvent glare; in another embodiment, 0&lt;β 1 ≦55°, and in yet another embodiment, 0&lt;β 1 ≦30°. Assuming a lighting device  10  used as ceiling lighting in a general lighting application, when β 1 ≦65°, and preferably ≦30°, glare is minimized. Since the OLED light  21  in beam  28  is generally weaker, glare by the OLED light  21  may be substantially absent. In an embodiment, γ 1 ≧30°, preferably γ 2 ≦65°. Preferably, γ 2 ≧β 1 , more preferably γ 2 &gt;β 1 . In yet a further embodiment, 0&lt;β 1 ≦10°; such a configuration can be used as “accent lighting”, with the at least one lamp  10  providing a beam of light  18  at a relatively narrow angle β 1 . 
     In another preferred embodiment, γ 1 ≧β 1 . Especially when γ 1 ≦β 1 , or even more preferably when γ 1 &gt;β 1 , the at least one OLED  20  is arranged to provide the second beam of light  28  substantially outside the first beam of light  18 , as is indicated in  FIG. 4 . The phrase “second beam of light  28  substantially outside the first beam of light  18 ” will be clear to the person skilled in the art. It especially refers to a distribution of the light wherein the at least one OLED  20  substantially provides beam  28  in an area outside area  180 . Such a configuration provides a device  10  with light  32  from the at least one lamp  10  and the at least one OLED  20 , while outside the beam  18  of the lamp  10 , the OLED light  21  will become visible (as “beam”  28 ) and luminance indication lighting can be obtained. In one embodiment, the angular distribution at which the OLED light  28  is dominant and thus visible is typical of shoppers looking for indication signs. By shaping the geometry of the OLED  20  (as defined above with respect to the tilted edges  20   c  and  40   c , respectively), the angular flux distribution of the OLED light can even be tuned further to enhance the effect, as shown above. Hence, an embodiment of the invention provides a lighting device  1  wherein a difference between the angular flux distribution of the lamp  10  (which may be a traditional light source) and the OLED  20  can be achieved relatively easily, without relatively bulky or complicated optics. However, for any configuration in which γ 2 &gt;β 1 , a lighting effect is created wherein the OLED light  28  is angularly separated from the lamp light  18  and is seen outside this beam  18 . 
     In other embodiments, γ 1 ≦β 1 , and especially when also γ 1 =0°, beams  18  and  28  at least partially overlap. Such embodiments may be used to provide, for instance, a color variation, when, for instance, the at least one OLED  20  is able to provide colored light. When, furthermore, also γ 2 &gt;β 1 , the above-described combination of illumination by beam  18  and rumination from beam  28  can also be achieved. 
     In another embodiment, γ 2 =β 1 . When γ 1 =0° and γ 2 =β 1 , the beams  18  and  28  essentially overlap, i.e. beams  18  and  28  have substantially the same cut-off angles. When γ 1 ≠0° (i.e. γ 1 &gt;0°) and γ 2 =β 1 , the beams  18  and  28  overlap, but the intensity of beam  28  has a relative minimum at a normal  18   a  to window pane  40 , see e.g. also  FIG. 3   h , which may show the luminous intensity of lighting device  1  with such an arrangement. Also these embodiments may be used to provide a color variation. 
     In again another embodiment, 2°&lt;γ 2 ≦65°, 0°&lt;β 1 ≦30°, and γ 2 &gt;β 1 . Such an embodiment may be used for rumination (OLED light  21 ) with the lamp  10  as “accent light”, especially when 0°&lt;β 1 ≦10°. 
     In another specific embodiment, γ 2 &lt;β 1 . In this way, OLED light  21  of the at least one OLED  20  as beam  28  may be found within beam  18  of the at least one lamp  10 . This may provide a “corona” effect of light  32 . For instance, when the OLED  20  provides red light and the lamp  10  provides white light, a red-light red spot may be observed within beam  18 . 
     As schematically shown in an alternative embodiment of the lighting device  1  in  FIG. 9 , the lighting device  1  has a concave surface  20   f  of the OLED  20  and a concave surface  40   f  of the window pane  40 , respectively. This results in a narrow beam  28  in a direction almost perpendicular to the normal  18   a , wherein γ 1  is about 80° and γ 2  is about 100° and γ 1 =γ 1 ′ and γ 2 =γ 2 ′. 
     In yet another embodiment, as schematically depicted in  FIG. 7 , lamp  1  comprises two openings which are arranged to pass light  11  from the at least one lamp  10  through these openings in preferably different directions. In  FIG. 7 , lamp  1  comprises a first opening  52 ( 1 ) and a second opening  52 ( 2 ), which, in this embodiment, are opposite to each other, with respect to the at least one lamp  10 . In this embodiment, the one or more beam manipulators  30  are preferably arranged to manipulate light  11  into two directions, i.e. in the direction of opening  52 ( 1 ) and opening  52 ( 2 ) in the beam manipulator  30  (here, the openings in housing  50 ). Hence, in another preferred embodiment, the invention provides a lighting device  1  which further comprises a first opening  52 ( 1 ) and a second opening  52 ( 2 ), wherein the at least one lamp  10  is arranged to provide at least 20%, more preferably at least 30% of the total flux of light  11  generated by the at least one lamp  10  in the direction of the first opening  52 ( 1 ), and to provide at least 20%, more preferably at least 30% of the total flux of light  11  in the direction of the second opening  52 ( 2 ). The fluxes through openings  52 ( 1 ) and  52 ( 2 ) may have ratios of, for instance, 100:0 (no opening, as discussed above), 80:20, 60:40, 70:30 and 20:80. The percentages of the fluxes add up to 100%. The first opening  52 ( 1 ) is the opening which is indicated as opening  52  in  FIGS. 4 ,  5  and  6 . It is this opening which comprises the at least one OLED  20 . As will be clear to the person skilled in the art, also the second opening  52 ( 2 ) may comprise at least one OLED. 
     In the embodiment schematically depicted in  FIG. 7 , at least part of the light  11  escapes from the lighting device  1  via the second opening  52 ( 2 ). The beam manipulator  30  may be arranged to reflect at least part of the total flux of the light  11  of the at least one lamp  10  downwards and to reflect at least part of the total flux of the light  11  of the at least one lamp  10  in another direction, typically upwards. This up/down light distribution may be used in suspended luminaries for lighting both the room below and the ceiling above. In this specific embodiment, the transparent OLED  20  can be located in the beam reflecting to the floor, in the beam directed to the ceiling, or in both. In these embodiments, the transparent OLEDs  20  thus only transmit part of the total flux of the one lamp  10 . The invention is not limited to suspended lighting devices  1 . 
     Hence, as will be clear to the person skilled in the art, one or more of the geometries of the housing  50 , including the one or more openings  52 , the arrangement of the at least one lamp  10  relative to the housing  50  and the optional presence of one or more beam manipulators  30  (and the arrangement of the lamp relative to the optional one or more beam manipulators  30 ), direct at least part of the total flux of the light  11  towards the at least one OLED  20  (comprised in opening  52 ( 1 )), and beam  18  is generated, while at least part of the total flux of light  11  escapes from the lighting device  1  via second opening  52 ( 2 ). 
     As will be clear to the person skilled in the art, the openings  52 ( 1 ) and  52 ( 2 ) are interchangeable, for instance, instead of opening  52 ( 1 ), opening  52 ( 2 ) may comprise the at least one OLED  20 . The preferred embodiments described hereinbefore with conditions for β 1 , γ 1  and γ 2  refer to the one or more openings or windows  52  of lighting devices which are to be arranged to provide beam  18  substantially in the direction below the lighting device  1  when in use, especially in its prescribed use, such as opening  52 ( 1 ) in  FIG. 7  and opening  1  in  FIGS. 4 and 5 . 
     In yet another embodiment, the lighting device  1  according to the invention provides an asymmetric beam of the at least one lamp  10 , for instance, for illuminating a wall (wall-washing application), and the OLED is used for guidance. Here, β 1 ≠β 1 ′, and either β 1 &gt;β 1 ′ or β 1 &lt;β 1 ′. For instance, β 1  may be about 0° and β 1 ′ may be about 80°. As will be clear to the person skilled in the art, this is equivalent to an embodiment wherein β 1 ′ may be about 0° and β 1  may be about 80°. One of β 1  and β 1 ′ is preferably &lt;10° and the other one of β 1  and β 1 ′&gt;10°, preferably &gt;45°, more preferably between about 60° and 90°, and preferably less than about 85°. Whereas the light distribution of beam  18  may be asymmetric, the light distribution of beam  28  may still be symmetric, but also asymmetric. When, for instance, the tilt angle α varies over edge or edges  40   c  (i.e. changing a for one or more edges and/or different tilt angles α for two or more edges), an asymmetric beam  28  may be generated by the OLED  20  in operation. In a preferred embodiment, both γ 2  and γ 2 ′ preferably define beam  28 , wherein (i.e. at angles smaller than γ 2  and γ 2 ′) the at least one OLED  20  of lighting device  1  provides a luminance of more than 1000 cd/m 2 , and at angles equal to or larger than γ 2  and γ 2 ′, the at least one OLED  20  of lighting device  1  provides a luminance of ≦1000 cd/m 2 . Preferably, γ 2  and γ 2 ′ are both independently smaller than about 65°. 
     Hence, in a specific embodiment, at least the first beam  18  has an asymmetric light distribution. In yet another embodiment, at least the second beam  28  has an asymmetric light distribution. 
     The lighting device  1  of the invention can be applied in any environment where general lighting and indication light may be needed, such as in shops, hospitals, clinics, offices, corridors, tunnels, indoor escape routes, gangways (in e.g. planes or coaches), elevators, escalators, hospitality areas such as pubs, restaurants, hotels, etc. 
     In a specific embodiment, such as, for instance, in shops, especially in high-ceiling shops, luminance lighting can be used to indicate areas with a certain shopping content, such as e.g. red for meat, green for vegetables, blue for fish. Nowadays, this requires installation of two lamp systems, namely, an illuminance system for general “shop” lighting and a luminance system for indication lighting. This problem can be solved by the device  1  of the invention. Hence, an embodiment of a hybrid OLED-lamp system as described herein as lighting device  1  combines the function of general lighting (by the traditional lamp or lamps/LED or LEDs)  10  and indication lighting by the OLED or OLEDs  20 . Since the OLED or OLEDs  20  are substantially transparent, the two light sources  10 ,  20  are preferably placed over each other so as to minimize volume. For such applications, the at least one OLED  20  is arranged to generate colored light  21 . 
     Examples of characteristic luminous intensity curves that may be achieved with lamps of the invention are schematically depicted in  FIGS. 8   a  to  8   d . In these Figures, the broken lines reflect the luminous intensity of the light in the y-direction, whereas the solid lines reflect the luminous intensity of the light in the x direction (see also  FIG. 4 ). These Figures may especially relate to the light in beam  18 ; the light of the at least one OLED  20  in beam  28  may be distributed in the same but preferably different way, as described above.  FIG. 8   a  typically depicts a fluorescent tube application (TL). When, in  FIG. 4 , lighting device  1  is a fluorescent tube, the observer moving along the x-direction will experience another light distribution than when moving along the y-direction.  FIG. 8   b  schematically depicts a downlight application in which both distributions are substantially equal. In the latter case, the luminous intensity distribution may be similar in both directions.  FIG. 8   c  schematically depicts a wall-washing application. Here, the light distribution is asymmetric, at least in one direction of the beam. In the invention, this may be especially beam  18 .  FIG. 8   d  finally depicts an application in which light also escapes from the top of lighting device  1 . 
     The term “luminance” is known in the art and refers to a measure of the brightness of a surface. The terms “illuminance” and “illumination” are also known in the art and refer to the amount of light incident on a surface. 
     As mentioned above, the term “at least one lamp  10 ” may also include a plurality of lamps. An embodiment thereof is schematically shown in  FIG. 5 . In this Figure, two lamps are applied as “lamp”  10 . Such luminaires are often used in office lighting. Likewise, a plurality of LEDs may be used. 
     The lighting device  1  as schematically depicted in  FIGS. 1 ,  4 ,  5  and  7  may have further features which are not shown, such as louvers for (further) manipulation of beam  18  and/or beam  28 . In addition or next to louvers, the lighting device  1  may comprise elements arranged to substantially block OLED light  28  in at least one direction. Since OLED light essentially escapes in two directions from edge  20   c  or  40   c , respectively, one of these directions may be blocked. With particular reference to  FIGS. 3   b / 3   c  and  3   f / 3   g , it may be interesting to block at least part of the light that is emitted upwards. Likewise, the lighting device  1  may also comprises elements for blocking at least part of the light  11  of the at least one lamp, such as a reflector as is sometimes used in spot lights. 
     In yet another embodiment, which is schematically depicted in  FIG. 6 , the at least one OLED  20  can be arranged on a tubular fluorescent tube (TL) or fluorescent lamp, herein denoted by reference numeral  10 . The OLED or OLEDs  20  may be wrapped, folded, coated or attached to the outer surface of the lamp  10 . Such a lighting device  1  has, inter alia, the advantage that the light  32  emitted by the device  1  can be modulated by selecting the intensity and/or color of the OLED. For instance, the at least one OLED  20  may modify the white light  11  of a fluorescent lamp to colored light. Such a lighting device may also be a kind of multi-purpose lighting device  1 , which combines the functionalities of providing light  11  for illumination and light  21  for rumination, depending on the desired application. 
     The lighting device may further comprise a controller (not shown) for controlling the light intensity and optionally the color of one or more light sources  10 ,  20 . This may include controlling the intensity or color of individual light sources of a plurality of light sources, which form the at least one lamp  10 , and/or the intensity or color of individual OLEDs of a plurality of OLEDs which form the at least one OLED  20 . The controller may be an “only hardware” system with, for instance, switches such as touch controls, slide switches, etc. for controlling the intensity of light sources  10 ,  20  or selecting the desired color, depending on the application of lighting device  1 , the user&#39;s mood, etc. Furthermore, the intensity and/or color of light source  10 ,  20  may depend on external parameters such as time, temperature, light intensity of external sources (such as the sun), which may be measured by sensors (not shown). The controller may be operated via a remote control. The controller may control the intensity of one or more light sources  10 ,  20  via means known in the art to control such light sources, such as ballasts. 
     In yet another embodiment, the controller may comprise a memory, with executable instructions, and an input-output unit, configured to:
     (i) receive one or more input signals from one or more elements selected from the group of:   

     (1) one or more sensors; and 
     (2) a user input device; and
     (ii) send one or more output signals to control the intensity and/or color of one or more light sources  10 ,  20 ; and a processor designed to process the one or more input signals into one or more output signals based on the executable instructions.   

     The controller may provide one or more functions of, inter alia, switching on and off one or more first light sources  10  and second light sources  20 ; determining the intensity of light  11 ; determining the intensity of light  21 ; determining the intensity of light  32 ; determining the color of light  11 ; determining the color of light  21 ; determining the color of light  32 ; determining whether or not one or more colors or intensities of light of one or more of light  11 , light  21  and light  32  depend on one or more external parameters such as time, temperature, light intensity of external sources, etc. 
     It should be noted that the terms “top” and “bottom”, and “left” and “right” are interchangeable. 
     The embodiments described hereinbefore illustrate rather than limit the invention, and those skilled in the art will be able to design many alternative embodiments without departing from the scope of the appended claims. In the claims, any reference signs placed between parentheses shall not be construed as limiting the claim. Use of the verb “comprise” and its conjugations does not exclude the presence of elements or steps other than those stated in a claim. The article “a” or “an” preceding an element does not exclude the presence of a plurality of such elements. The invention may be implemented by means of hardware comprising several distinct elements, and by means of a suitably programmed computer. In the device claim enumerating several means, several of these means may be embodied by one and the same item of hardware. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage.