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

The invention provides a lighting device comprising at least one lamp and at least one OLED which are 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. The lighting device of the invention may advantageously provide the option of providing two types of light, namely, “normal” of the lamp, which can be used for e.g. illumination purposes, and OLED light of the OLED, which can be used for lumination purposes.

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 β1and the second beam has a cut-off angle γ2and optionally a cut-off angle γ1, and wherein γ2>γ1and preferably γ2≧β1.

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.

DESCRIPTION OF EMBODIMENTS

Referring toFIGS. 1,4to7, and9, the present invention provides a lighting device1comprising:(a) at least one lamp10(also indicated as source10) which is arranged to generate light11; and(b) at least one OLED20(also indicated as source20) which is arranged to generate light21, wherein the at least one OLED20is arranged to transmit at least part of the light11generated by the at least one lamp10. As can be seen in the Figure(s), the at least one lamp10is arranged to illuminate (or irradiate) at least part of the at least one OLED20, which (during operation of the device1) transmits at least part of the light11generated by the at least one lamp10.

The light generated by device1, i.e. the light generated by both sources10and20, is denoted by reference numeral32. The light generated by the two sources10,20may be separated substantially angularly, as is especially indicated inFIGS. 2 to 5, but may also substantially overlap, as is indicated, for instance, inFIG. 6. Hence, in embodiments, light32generated by lighting device1may 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 sources10,20of the lighting device1will first be described in general below, and embodiments of the lighting device1will then be described in more detail.

The Light Sources (Lamp10and OLED20)

The at least one lamp10may 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 lamp10is 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 lamp10has a variable flux. Lamp10preferably 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 lamps10described 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 OLED20may 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); andOLEDs 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/m2paper 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/m2: 3 V, 3 mA/cm2(1.5 lum), efficiencies of 12 Cd/A have been reported for small-molecule devices.

The at least one OLED20preferably 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. 2aschematically depicts an OLED20with an organic layer22sandwiched between a first layer23and a second layer24, 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 d20of the OLED20, 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 layer22(efficiently) out of the OLED20, 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 layer22, and transparent electrodes/substrates are used, light is emitted in both directions relative to the organic layer (inFIG. 2a, OLED light would escape from faces20aand20b); when such structures are only arranged at one side (i.e. at face20aor face20b), and, for instance, a reflective layer is present at the other side, light generated in the organic layer is substantially emitted in one direction (inFIG. 2b, OLED light would escape from faces20aor20b). 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 face20aand/or face20b. Faces20aand20bare external surfaces of the OLED (i.e. of first layer23and second layer24, respectively) which are arranged in parallel with the organic layer22, 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 light11generated by the at least one lamp10, 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 light11generated by the at least one lamp10will be transmitted for at least 50% by the at least one OLED20when the OLED20is in operation and when assuming perpendicular irradiation with such light11.

OLEDs may be foldable, which is of special relevance for application on curved surfaces, as depicted inFIG. 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 lamps10or by the one or more OLEDs20comprises white radiation (i.e. white light), although in another embodiment one or more of these light sources10,20may also produce colored light. Commercially available lamps10and transmissive OLEDs20emitting (white) light may be used. When the at least one lamp10comprises more than one lamp, such as a plurality of LEDs, or when the at least one OLED20comprises 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 lamp10. When such multiple sources with multiple colors (of the generated light) are used as lamp10, these sources are preferably arranged to be able to generate white light (by color mixing).

The Lighting Device1

As mentioned above, the at least one OLED20is arranged to transmit at least part of the light11generated by the at least one lamp10. In the device1, the at least one lamp10is arranged to illuminate at least part of the at least one OLED20. Due to the fact that the OLED20is transmissive, at least part of the light11generated by the at least one lamp10is transmitted by the at least one OLED20. Such a configuration, as schematically depicted in, for instance, the embodiments ofFIGS. 1 and 4to7, allows a relatively compact arrangement of the two sources10,20.

The embodiment of the lighting device1inFIGS. 1,4,5and7further comprises a housing50. The housing50has at least one opening52(or window), through which light11of the at least one lamp10can escape from the interior of the housing. In a further embodiment, the lighting device1has only one opening52, arranged to allow light11to escape from the lighting device1, i.e. housing50has only one opening52. The lamp10is circumferentially arranged in housing50. The embodiments schematically depicted inFIGS. 1,4,5and7especially 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 device1may also be termed luminaire.

The opening52may comprise the at least one OLED20. For instance, the one or more OLEDs20may be arranged within opening52or at one side of this opening52. InFIG. 1, the at least one OLED20is arranged substantially at one side of the opening52, but as will be clear to the person skilled in the art, the shape of housing50and opening52may have any geometry, and concomitantly, the arrangement of the at least one OLED20in the lighting device1may be chosen by the person and/or designer skilled in the art, on condition that at least part of the light11of the at least one lamp10irradiates the at least one OLED20(which transmits at least part of this light11). The at least one OLED20may be integrated within, in front of or behind opening52in any way known to the person skilled in the art. Hence, the at least one OLED20will at least partly be arranged as a kind of window pane (denoted by reference numeral40), through which at least part of the light11of lamp10will be transmitted. This window pane40may be the (at least one) OLED20, or it may be a transmissive material wherein and/or whereon the at least one OLED20is arranged (see also below). In either case, when the OLED is in operation, the transmission of the window pane40for the visible light11of the at least one lamp10is at least 50%, preferably at least 70%, more preferably at least 85%, assuming perpendicular irradiation (see also above).

The lighting device1according to the invention may further comprise one or more beam manipulators30arranged to manipulate at least part of the light11of the at least one lamp10and illuminate at least part of the at least one OLED20with manipulated light. The beam manipulator30may comprise one or more devices selected from the group of reflectors and collimators. Due to the geometry of the lighting device1(especially housing50and the arrangement of the at least one lamp10relative to housing50) and/or the beam manipulator30, light11leaves the device1as beam18.

The housing50preferably further comprises an at least partly reflective wall51, also indicated as reflector or reflectors51, as beam manipulator30. Reflective elements or reflective coatings or layers are known to the person skilled in the art. At least part of the internal wall of housing50is preferably reflective. More preferably, substantially the whole internal wall of the housing50that receives light11from the at least one lamp10comprises reflective wall51. In this way, light11of the at least one lamp10is substantially collimated on opening52(i.e. on at least part of the at least one OLED20). Hence, in these Figures, beam manipulator30comprises a reflective layer, coating or element, which at least partially encloses the at least one lamp10and is arranged to manipulate at least part of the light11of the at least one lamp10(into a beam18).

The beam manipulator30may also comprise a collimator. For instance, lamp10may 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 device1further comprising (at least one) beam manipulator30which is arranged to manipulate at least part of the light11of the at least one lamp10and illuminate at least part of the at least one OLED20with the manipulated light11. The transparent OLED or OLEDs transmit at least part of the light11collimated by beam manipulator or manipulators30and illuminated by this (collimated) light. In these embodiments, the at least one OLED20is arranged within, in front of or behind opening52, such that the manipulated light11of the at least one lamp10illuminates the at least one OLED20and through which at least part of the manipulated light11is transmitted. In an embodiment, preferably at least 40%, more preferably at least 70%, more preferably at least 90% of total flux of the light11of the at least one lamp10illuminates the at least one OLED20(see further also below). As will be clear to the person skilled in the art, one or more of the geometries of the housing50, including the opening52, the arrangement of the at least one lamp10relative to housing50and the optional presence of one or more beam manipulators30, direct at least part of the total flux (preferably at least 40%) of the light11of the at least one lamp10towards the at least one OLED20(comprised in opening52), and beam18is generated.

InFIGS. 1,4,5and7, the opening52comprises window pane40, which is at least partially transparent to light11of lamp10. The window pane40may consist of one or more OLEDs20, i.e. window pane40is the at least one transparent OLED as described herein, or window pane40may 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 opening52and comprises the one or more OLEDs20. The window pane40is preferably flat, although in an embodiment also a curved window pane40may be applied. The preferred embodiments herein depicted schematically (FIGS. 1,4,5, and7) comprise substantially flat window panes40. Hence, in a specific embodiment, the at least one lamp10is arranged in a beam manipulator30which is arranged at least partially circumferentially and further comprises window pane40which comprises the at least one OLED20. The window pane40is arranged to transmit at least part of the light11from lamp10.

Window pane40may be, for instance, a glass plate or a transparent plastic or any other substantially transparent material, on or in which the at least one OLED20is arranged. For instance, especially when the OLED20is not foldable, for instance, in cases where the substrate is made of glass, window pane40may be the one or more OLEDs20.

However, in another embodiment, as schematically depicted inFIG. 2d, the one or more OLEDs may also be comprised in a sheet, for instance, glass (the OLED or OLEDs20), or may be sandwiched between glass plates or transparent plastic.

The window pane40has a thickness d40which is in the range of d20(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 inFIGS. 1,4,5and7may have the specific advantage that a lighting device1can be provided which is arranged to provide two beams, one beam substantially comprising light21generated by the one or more OLEDs20, and one beam substantially comprising light11generated by the one or more lamps10. The OLED20is 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 OLED20may 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 inFIGS. 1,4,5and7, a lighting device1is provided, wherein the lamp10and the optional beam manipulator30are arranged to manipulate light11into a beam18and the at least one OLED20may be arranged to provide light21substantially outside the beam18. The term “substantially outside the beam18” herein refers to the situation in which the cut-off angles (see also below) at which these beams18and28leave lighting device1substantially do not coincide. In this way, a lighting device1may be provided wherein the at least one lamp10and the at least one OLED20provide beams of light18,28which are separated substantially angularly and thus leave the device1at different angles. For instance, this may be due to the fact that beam18substantially leaves the lighting device1at one or more positions spatially separated from positions where beam28substantially leaves the lighting device1. Alternatively, or in combination with the above, this may also be due to the fact that beam18substantially leaves the lighting device1at angles different from angles at which beam28substantially leaves the lighting device1.

This is further elucidated with reference toFIGS. 2ato3h.FIGS. 2ato3hschematically illustrate how this can be achieved in embodiments of the invention. The result is shown inFIGS. 3btod,3ftoh, and in the schematicFIGS. 2c,4and5. As mentioned above, the OLED20has a first face20aand a second face20b, which are substantially parallel to the organic layer22. 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 face20a, or second face20b, or from both faces20aand20b, for instance, in the direction perpendicular to faces20aand/or20b. Furthermore, the device20has edges20c,substantially perpendicular to faces20aand20b. Edges20cmay refer to one or more edges20c. Edges20care the edges of the device20which are arranged substantially perpendicularly to the organic layer; edges20aand20bare the external faces of the first and the second layer, respectively, which are substantially parallel to the organic layer22in OLED20; i.e. the front and back face, respectively, of the OLED20.

However, in the invention, also due to the preferred absence of structures for improving outcoupling of light at one or more of the interfaces22-24,22-23,24-outside or23-outside, light21will leave the OLED20at all surfaces20a,20band20c, but preferentially at the side surfaces or edges20c. This is indicated inFIGS. 3a,3band3c. A commercially available optical ray-tracing program is used to simulate the OLEDs20output.

First, an OLED20having rectangular edges20c(FIG. 3a) is simulated (rectangular with respect to substantially parallel first and second faces20aand20c). In this case, the luminance on edges is three times higher than from the top surface20bof OLEDs (FIG. 3b). The edge luminous intensity distribution is shown inFIGS. 3cand3d. 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 alsoFIG. 4). This means that light21(essentially) comes from the edges20c, 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 panes40including the one or more OLEDs20. Then, OLED light21will leave the pane40at all surfaces40a,40band40c, but preferentially at the side surfaces or edges40c. Edges40care the edges of the window pane40which are arranged substantially perpendicularly to the organic layer; edges40aand40bare the external faces of the pane40, respectively, which are substantially parallel to the organic layer22in OLED20; i.e. the front and back face, respectively, of the OLED20.

In a preferred embodiment, however, OLEDs20having one or more tilted edges20care applied, as is schematically depicted inFIGS. 2cand3d. This also includes window panes40having one or more tilted edges40c, as is schematically depicted inFIG. 2d.FIG. 2dschematically depicts a window pane40comprising a plurality of OLEDs, which are integrated in a transparent material. The front and back faces40aand40bare essentially parallel to the organic layer or layers20of the OLED or OLEDs. The edge or edges40cof window pane40may be tilted at an angle α. This means that window panes40, in and/or on which one or more OLEDs20are provided, may include tilted edges40c. Ray-tracing results of OLEDs having tilted edges20care shown inFIGS. 3f,3gand3h(edge luminous intensity distributions). In this case, the light substantially comes from OLEDs20and substantially illuminates either the ceiling or the floor at a certain angle. In this case, the luminance on edges20cor40cmay be at least about three times higher than from the top surface20bof OLEDs20, but may even be higher. InFIGS. 3fand3h, an OLED20is used with edges20chaving an angle α of about 45°; inFIG. 3g, α is slightly larger than 0°.

Hence, in a specific embodiment, a lighting device1is provided, which comprises at least one OLED20or a window pane40comprising at least one OLED20, wherein the at least one OLED or the window pane40comprising the at least one OLED20is arranged to emit light21substantially at edge20cor40c, respectively. The term “substantially” herein refers to the situation in which at least 50% of the total flux of light21leaving the OLED20(or the window pane40) leaves from the total external surface of these edges. Edges20cand40crelate to edges of the OLED or the window, which are perpendicular to the plane of the organic layer22, respectively, or optionally tilted. Alternatively or additionally, the edges have an end surface20f,40fwhich has a concave, convex or undulated shape along a normal18anormal to the OLED20, as is shown inFIG. 9. In this way, a desired designed beam shape is obtained, which is suitable for special decorative illumination or illuminative effects. InFIGS. 2cand2d, angle α reflects the tilt of the edges20cand40c. InFIG. 2a, 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 layers22are substantially parallel to a ceiling (or floor), the former configuration (1) is advantageous for preferentially illuminating objects arranged below the device1, such as, for instance, a floor, and the latter configuration (2) is advantageous for preferentially illuminating objects arranged above the device1, such as, for instance, a ceiling. In this way, a device1is provided in which the beam18of light11generated by the at least one lamp10and the beam28of light21generated by the at least one OLED20may leave the device1in an angularly separated way. As can be seen inFIGS. 3b,3cand3d, on the one hand, andFIGS. 3f,3gand3h, on the other hand, the use of a tilted edge20cor40cleads to an increase and/or a redistribution of the light that escapes from edge20cor40c. For instance, the relative symmetric distribution of light in an upward and downward direction inFIG. 3b(tilt α=0) is changed in a distribution ofFIG. 3fwith relatively more light directed downwards when using tilted edges.

For the sake of understanding, further reference is made below to window pane40only, which, as described above, may consist of one or more OLEDs20(see also above), or may comprise the one or more OLEDs20.

Hence, in an embodiment, the window pane40has at least one edge40cwhich is tilted at angle α (tilt angle) relative to a normal to the at least one OLED20, wherein 0°<α<90° or 90°<α<180°. This normal is substantially parallel to a normal to front and bottom faces40aand40b(or20aand20b), respectively. InFIGS. 2band2d, both drawn edges (edges20cinFIG. 2band edges40cinFIG. 2d, respectively) have a tilt angle α. The tilt angle α may differ for each edge40c. The window pane may be circular and have one edge40c, 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 edges40c. In systems with an even number of edges40c(≧2), wherein at least two edges40care arranged opposite each other, these opposite edges (20c) 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 edges40c, but may of course also not be the same. Tilt angle α may vary over the edge or edges40c. This means that when there is more than one edge40c,different edges40cmay 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 panes40, two opposite edges40care preferably tilted independently at tilt angle α, both preferably having the same tilt angle α.

FIG. 4shows a specific embodiment of a lighting device1in which beam18has a normal18ato window pane40and beam18is substantially confined to a beam at an angle β1relative to the normal18ato window pane40, and in which the at least one OLED20is arranged to generate light21into a beam28, the OLED beam28being substantially confined to a beam having a smallest angle γ1with respect to a normal18ato window pane40and a largest angle γ2with respect to a normal18ato window pane40. In fact, normal18ais a normal to OLED20(or a normal to organic layer22). Hence, γ2>γ1; γ2>0°; preferably γ2≧β1(inFIG. 4, γ2is larger than β1); γ1>0°; β1>0°.

Here, a substantially flat window pane40is shown, but in other embodiments, the window pane40comprising the one or more OLEDs20may also be curved. As will be clear to the person skilled in the art, window pane40may also comprise a plurality of window panes, one or more of which comprise one or more OLEDs20.

FIG. 4assumes a symmetric light distribution relative to the normal18a,wherein angles β1=β1′, γ1=γ1′ and γ2=γ2′. Herein, γ2>γ1. Unless otherwise indicated, a substantially symmetric light distribution is assumed (mirror symmetry; see alsoFIGS. 8a,8band8d). Furthermore,FIG. 4assumes a horizontal arrangement of lighting device1, i.e. window pane40is 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, inFIG. 4, the observer would be positioned at18′ and then move to the left or the right, he would experience substantially similar light distributions, see alsoFIGS. 3b,3c,3d,3f,3gand3h;likewise, the observer moving to the back or standing up might again experience substantially similar light distributions. Hence, when referring to β1, γ1and γ2, reference is also made to β1′, γ1′ and γ2′, respectively, below, unless otherwise indicated. Note that these angles refer to a two-dimensional description of beams18and28, 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 ofFIGS. 8atod).

Furthermore,FIG. 4schematically depicts an embodiment in which lighting device1is arranged as, for instance, a TL lamp in a luminaire. As can be seen inFIG. 4(but alsoFIGS. 5 and 7) most of the light32is directed downwards. Hence, angle18′ is a right angle, which, in this substantially horizontal arrangement, can also be indicated as “nadir”.

In the schematicFIG. 4, which depicts one of the possible embodiments of the invention, two distinct lighting areas can be observed, one area180, which is substantially illuminated by beam18confined by angle β1(here β1=β1′), and another area280, wherein lumination from the at least one OLED20is received in the form of beam28confined by angle γ2(here γ2=γ2′). As will be clear to the person skilled in the art and, for instance, also fromFIGS. 3b,3c,3d,3f,3gand3h, the at least one OLED20may also irradiate at angles smaller than γ1(and γ1′) in case γ1≠0°. However, especially in the case in which α is smaller than 90° and larger than 0°, the flux between angles γ1(wherein γ1≠0°) and γ2may be even more enhanced relative to the areas confined to γ1(seeFIG. 3h).

The angles γ2and β1, and in an embodiment also angle γ1especially 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. beams18and28, respectively) at the light source with respect to a vertical (here the dash-dotted line to18′), 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/m2. Hence, γ2and γ1, or γ2alone when γ1=0°, define beam28in a preferred embodiment, wherein, at angles smaller than γ2(and larger than γ1in case γ1≠0°), the at least one OLED20of lighting device1provides a luminance of more than 1000 cd/m2, and at angles equal to or larger than γ2and equal to or smaller than γ1(if γ1≠0°), the at least one OLED20of lighting device1provides a luminance of ≦1000 cd/m2. Likewise, β1defines beam18in a preferred embodiment, wherein, at angles smaller than β1, the at least one lamp10of lighting device1provides a luminance of more than 1000 cd/m2and at angles equal to or larger than β1, the at least one lamp10of lighting device1provides a luminance of ≦1000 cd/m2. Hence, when the lighting device1in this embodiment is in operation and an observer views the device1at a viewing angle equal to or larger than γ2, a luminance of the at least one OLED20and the at least one lamp10will be ≦1000 cd/m2. When the viewing angle is reduced and becomes smaller than γ2, but larger than γ1(if y≠0°), an OLED luminance of more than 1000 cd/m2will be observed. At angles smaller than β1, a lamp10luminance of more than 1000 cd/m2will be received.

Hence, in an embodiment of the lighting device, the at least one lamp10is arranged to generate light21into first beam18, and the at least one OLED20is arranged to generate light21into second beam28, wherein, relative to the normal to the at least one OLED20, the first beam18has a cut-off angle β1and the second beam has a cut-off angle γ2and optionally a cut-off angle γ1, and γ2>γ1, preferably γ2≧β1. At angles≧β1, the luminance of the lighting device1due to the first beam18and, at angles≧γ2, the luminance of the lighting device1due to the second beam28are preferably independently ≦1000 cd/m2. At angles<β1, the luminance of the lighting device1due to the first beam18and, at angles<γ2(and larger than if y≠0°), the luminance of the lighting device1due to the second beam28are independently >1000 cd/m2. When γ1≈0°, beam28has only one cut-off angle.

In a preferred embodiment, γ2>β1(i.e. β1<γ2; β1>0°). In this way, a lighting device1can be provided, wherein the “core” beam18can be used, for instance, for illumination, and the light in beam28provides a lumination effect: a light effect may be created around the beam18of the at least one lamp10, “similar” to a halo.

Especially in view of office applications, β1is preferably chosen to be 0<β1≦65° so as to circumvent glare; in another embodiment, 0<β1≦55°, and in yet another embodiment, 0<β1≦30°. Assuming a lighting device10used as ceiling lighting in a general lighting application, when β1≦65°, and preferably ≦30°, glare is minimized. Since the OLED light21in beam28is generally weaker, glare by the OLED light21may be substantially absent. In an embodiment, γ1≧30°, preferably γ2≦65°. Preferably, γ2≧β1, more preferably γ2>β1. In yet a further embodiment, 0<β1≦10°; such a configuration can be used as “accent lighting”, with the at least one lamp10providing a beam of light18at a relatively narrow angle β1.

In another preferred embodiment, γ1≧β1. Especially when γ1≦β1, or even more preferably when γ1>β1, the at least one OLED20is arranged to provide the second beam of light28substantially outside the first beam of light18, as is indicated inFIG. 4. The phrase “second beam of light28substantially outside the first beam of light18” will be clear to the person skilled in the art. It especially refers to a distribution of the light wherein the at least one OLED20substantially provides beam28in an area outside area180. Such a configuration provides a device10with light32from the at least one lamp10and the at least one OLED20, while outside the beam18of the lamp10, the OLED light21will become visible (as “beam”28) and luminance indication lighting can be obtained. In one embodiment, the angular distribution at which the OLED light28is dominant and thus visible is typical of shoppers looking for indication signs. By shaping the geometry of the OLED20(as defined above with respect to the tilted edges20cand40c, 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 device1wherein a difference between the angular flux distribution of the lamp10(which may be a traditional light source) and the OLED20can be achieved relatively easily, without relatively bulky or complicated optics. However, for any configuration in which γ2>β1, a lighting effect is created wherein the OLED light28is angularly separated from the lamp light18and is seen outside this beam18.

In other embodiments, γ1≦β1, and especially when also γ1=0°, beams18and28at least partially overlap. Such embodiments may be used to provide, for instance, a color variation, when, for instance, the at least one OLED20is able to provide colored light. When, furthermore, also γ2>β1, the above-described combination of illumination by beam18and rumination from beam28can also be achieved.

In another embodiment, γ2=β1. When γ1=0° and γ2=β1, the beams18and28essentially overlap, i.e. beams18and28have substantially the same cut-off angles. When γ1≠0° (i.e. γ1>0°) and γ2=β1, the beams18and28overlap, but the intensity of beam28has a relative minimum at a normal18ato window pane40, see e.g. alsoFIG. 3h, which may show the luminous intensity of lighting device1with such an arrangement. Also these embodiments may be used to provide a color variation.

In again another embodiment, 2°<γ2≦65°, 0°<β1≦30°, and γ2>β1. Such an embodiment may be used for rumination (OLED light21) with the lamp10as “accent light”, especially when 0°<β1≦10°.

In another specific embodiment, γ2<β1. In this way, OLED light21of the at least one OLED20as beam28may be found within beam18of the at least one lamp10. This may provide a “corona” effect of light32. For instance, when the OLED20provides red light and the lamp10provides white light, a red-light red spot may be observed within beam18.

As schematically shown in an alternative embodiment of the lighting device1inFIG. 9, the lighting device1has a concave surface20fof the OLED20and a concave surface40fof the window pane40, respectively. This results in a narrow beam28in a direction almost perpendicular to the normal18a, wherein γ1is about 80° and γ2is about 100° and γ1=γ1′ and γ2=γ2′.

In yet another embodiment, as schematically depicted inFIG. 7, lamp1comprises two openings which are arranged to pass light11from the at least one lamp10through these openings in preferably different directions. InFIG. 7, lamp1comprises a first opening52(1) and a second opening52(2), which, in this embodiment, are opposite to each other, with respect to the at least one lamp10. In this embodiment, the one or more beam manipulators30are preferably arranged to manipulate light11into two directions, i.e. in the direction of opening52(1) and opening52(2) in the beam manipulator30(here, the openings in housing50). Hence, in another preferred embodiment, the invention provides a lighting device1which further comprises a first opening52(1) and a second opening52(2), wherein the at least one lamp10is arranged to provide at least 20%, more preferably at least 30% of the total flux of light11generated by the at least one lamp10in the direction of the first opening52(1), and to provide at least 20%, more preferably at least 30% of the total flux of light11in the direction of the second opening52(2). The fluxes through openings52(1) and52(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 opening52(1) is the opening which is indicated as opening52inFIGS. 4,5and6. It is this opening which comprises the at least one OLED20. As will be clear to the person skilled in the art, also the second opening52(2) may comprise at least one OLED.

In the embodiment schematically depicted inFIG. 7, at least part of the light11escapes from the lighting device1via the second opening52(2). The beam manipulator30may be arranged to reflect at least part of the total flux of the light11of the at least one lamp10downwards and to reflect at least part of the total flux of the light11of the at least one lamp10in 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 OLED20can be located in the beam reflecting to the floor, in the beam directed to the ceiling, or in both. In these embodiments, the transparent OLEDs20thus only transmit part of the total flux of the one lamp10. The invention is not limited to suspended lighting devices1.

Hence, as will be clear to the person skilled in the art, one or more of the geometries of the housing50, including the one or more openings52, the arrangement of the at least one lamp10relative to the housing50and the optional presence of one or more beam manipulators30(and the arrangement of the lamp relative to the optional one or more beam manipulators30), direct at least part of the total flux of the light11towards the at least one OLED20(comprised in opening52(1)), and beam18is generated, while at least part of the total flux of light11escapes from the lighting device1via second opening52(2).

As will be clear to the person skilled in the art, the openings52(1) and52(2) are interchangeable, for instance, instead of opening52(1), opening52(2) may comprise the at least one OLED20. The preferred embodiments described hereinbefore with conditions for β1, γ1and γ2refer to the one or more openings or windows52of lighting devices which are to be arranged to provide beam18substantially in the direction below the lighting device1when in use, especially in its prescribed use, such as opening52(1) inFIG. 7and opening1inFIGS. 4 and 5.

In yet another embodiment, the lighting device1according to the invention provides an asymmetric beam of the at least one lamp10, for instance, for illuminating a wall (wall-washing application), and the OLED is used for guidance. Here, β1≠β1′, and either β1>β1′ or β1<β1′. For instance, β1may be about 0° and β1′ may be about 80°. As will be clear to the person skilled in the art, this is equivalent to an embodiment wherein β1′ may be about 0° and β1may be about 80°. One of β1and β1′ is preferably <10° and the other one of β1and β1′>10°, preferably >45°, more preferably between about 60° and 90°, and preferably less than about 85°. Whereas the light distribution of beam18may be asymmetric, the light distribution of beam28may still be symmetric, but also asymmetric. When, for instance, the tilt angle α varies over edge or edges40c(i.e. changing a for one or more edges and/or different tilt angles α for two or more edges), an asymmetric beam28may be generated by the OLED20in operation. In a preferred embodiment, both γ2and γ2′ preferably define beam28, wherein (i.e. at angles smaller than γ2and γ2′) the at least one OLED20of lighting device1provides a luminance of more than 1000 cd/m2, and at angles equal to or larger than γ2and γ2′, the at least one OLED20of lighting device1provides a luminance of ≦1000 cd/m2. Preferably, γ2and γ2′ are both independently smaller than about 65°.

Hence, in a specific embodiment, at least the first beam18has an asymmetric light distribution. In yet another embodiment, at least the second beam28has an asymmetric light distribution.

The lighting device1of 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 device1of the invention. Hence, an embodiment of a hybrid OLED-lamp system as described herein as lighting device1combines the function of general lighting (by the traditional lamp or lamps/LED or LEDs)10and indication lighting by the OLED or OLEDs20. Since the OLED or OLEDs20are substantially transparent, the two light sources10,20are preferably placed over each other so as to minimize volume. For such applications, the at least one OLED20is arranged to generate colored light21.

Examples of characteristic luminous intensity curves that may be achieved with lamps of the invention are schematically depicted inFIGS. 8ato8d. 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 alsoFIG. 4). These Figures may especially relate to the light in beam18; the light of the at least one OLED20in beam28may be distributed in the same but preferably different way, as described above.FIG. 8atypically depicts a fluorescent tube application (TL). When, inFIG. 4, lighting device1is a fluorescent tube, the observer moving along the x-direction will experience another light distribution than when moving along the y-direction.FIG. 8bschematically 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. 8cschematically 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 beam18.FIG. 8dfinally depicts an application in which light also escapes from the top of lighting device1.

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 lamp10” may also include a plurality of lamps. An embodiment thereof is schematically shown inFIG. 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 device1as schematically depicted inFIGS. 1,4,5and7may have further features which are not shown, such as louvers for (further) manipulation of beam18and/or beam28. In addition or next to louvers, the lighting device1may comprise elements arranged to substantially block OLED light28in at least one direction. Since OLED light essentially escapes in two directions from edge20cor40c, respectively, one of these directions may be blocked. With particular reference toFIGS. 3b/3cand3f/3g, it may be interesting to block at least part of the light that is emitted upwards. Likewise, the lighting device1may also comprises elements for blocking at least part of the light11of the at least one lamp, such as a reflector as is sometimes used in spot lights.

In yet another embodiment, which is schematically depicted inFIG. 6, the at least one OLED20can be arranged on a tubular fluorescent tube (TL) or fluorescent lamp, herein denoted by reference numeral10. The OLED or OLEDs20may be wrapped, folded, coated or attached to the outer surface of the lamp10. Such a lighting device1has, inter alia, the advantage that the light32emitted by the device1can be modulated by selecting the intensity and/or color of the OLED. For instance, the at least one OLED20may modify the white light11of a fluorescent lamp to colored light. Such a lighting device may also be a kind of multi-purpose lighting device1, which combines the functionalities of providing light11for illumination and light21for 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 sources10,20. This may include controlling the intensity or color of individual light sources of a plurality of light sources, which form the at least one lamp10, and/or the intensity or color of individual OLEDs of a plurality of OLEDs which form the at least one OLED20. 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 sources10,20or selecting the desired color, depending on the application of lighting device1, the user's mood, etc. Furthermore, the intensity and/or color of light source10,20may 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 sources10,20via 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 sources10,20; 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 sources10and second light sources20; determining the intensity of light11; determining the intensity of light21; determining the intensity of light32; determining the color of light11; determining the color of light21; determining the color of light32; determining whether or not one or more colors or intensities of light of one or more of light11, light21and light32depend 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.