FIELD OF THE INVENTION

The invention relates to a lighting device and to a method for producing such lighting device. The invention also relates to a luminaire comprising such lighting device.

BACKGROUND OF THE INVENTION

The use of transmissive resins is known in the art. US2010/0031544, for instance describes a cover plate for a lighting fixture and a lighting fixture having the same, which achieves superior light diffusivity and light uniformity as well as superior light transmission in comparison with the prior art, thereby improving a luminance characteristic. The cover plate is arranged at an exterior of a light source of the light fixture so as to exit lighting emitted from the light source outward. The cover plate is made of light transmissive resin material having 5-35% of bubbles for light scattering, which have a diameter within a range of 60 pm ~ 700 pm, and exits light emitted from the light source while diffusing the light to the whole area of the cover plate.

SUMMARY OF THE INVENTION

There is a desire to make stable and relatively simple lighting devices. Such devices may have a longer lifetime as there may be less failures.

Hence, it is an aspect of the invention to provide an alternative lighting device and/or process for producing such lighting device, which preferably further at least partly obviate(s) one or more of above-described drawbacks. The present invention may have as object to overcome or ameliorate at least one of the disadvantages of the prior art, or to provide a useful alternative.

Amongst others, the invention proposes a novel method to make a housing and optics of a luminaire. Herein, foaming is proposed to form a diffuse housing that may serve both the structural and optical purpose. Such build up may in embodiments also enable a rimless design and herewith the full light surface could be luminous. There may in embodiments no optical interruptions because the foam may act as a structural part. Hence, in an aspect the invention provides a lighting device comprising one or more light sources, especially an array of light sources, even more especially a 2D array of light sources. Yet even more especially, the lighting device comprises a 2D array of solid state light sources. Especially, the (solid state) light sources are configured to generate light source light, especially visible light source light. Further, the lighting device comprises electrical wiring electrically coupled to the (solid state) light sources. Further, especially the lighting device comprises a foam layer, enclosing the one or more (solid state) light sources. Especially, the foam layer encloses at least part of a plurality of the (solid state) light sources. Especially, the foam layer comprises a foam material that is transmissive for at least part of the light source light. In embodiments, the foam layer (“foam” or “foam layer”) has a first foam layer face and a second foam layer face. Especially, during operation of the lighting device at least part of the light source light emanates from at least one of the first foam layer face and the second foam layer face. Hence, in specific embodiments the invention provides a lighting device comprising (i) a one or more light sources, especially a 2D array of (solid state) light sources, wherein the (solid state) light sources are configured to generate light source light, (ii) electrical wiring electrically coupled to the (solid state) light sources, and (iii) a foam layer, enclosing at least part of a plurality of the (solid state) light sources, wherein the foam layer comprises a foam material that is transmissive for at least part of the light source light, wherein the foam layer has a first foam layer face and a second foam layer face, wherein during operation of the lighting device at least part of the light source light emanates from at least one of the first foam layer face and the second foam layer face, wherein the foam layer is a self-supporting layer.

The present invention may allow a material complexity reduction: using foam, lower amounts of material can be used, while essentially maintaining the mechanical strength. Further, the present invention may also reduce product complexity. Here, a component count reduction may be achieved as the housing and the optics, may be two different parts because of the different properties needed, which may in the present invention in embodiments be integrated into a single element. Hence, less assembly steps may be needed. In embodiments, the use of a chemical-setting material may further improve the stability of the foam. Hence, in embodiments the foam may comprise a chemical setting material and/or may be based on a polymer foam production process wherein a chemical setting material is applied. The process may enable relatively low pressure molding, whereas high pressure molding could damage components like a driver, LEDs etc. As indicated above, the lighting device comprises one or more light sources, especially a plurality of light sources. The term “light source” may refer to a semiconductor light-emitting device, such as a light emitting diode (LEDs), a resonant cavity light emitting diode (RCLED), a vertical cavity laser diode (VCSELs), an edge emitting laser, etc.. The term “light source” may also refer to an organic light-emitting diode, such as a passive- matrix (PMOLED) or an active-matrix (AMOLED). In a specific embodiment, the light source comprises a solid state light source (such as a LED or laser diode). In an embodiment, the light source comprises a LED (light emitting diode). The term LED may also refer to a plurality of LEDs. Further, the term “light source” may in embodiments also refer to a so- called chips-on-board (COB) light source. The term “COB” especially refers to LED chips in the form of a semiconductor chip that is neither encased nor connected but directly mounted onto a substrate, such as a PCB. Hence, a plurality of semiconductor light sources may be configured on the same substrate. In embodiments, a COB is a multi LED chip configured together as a single lighting module. The term “light source” may also relate to a plurality of (essentially identical (or different)) light sources, such as 2-2000 solid state light sources. In embodiments, the light source may comprise one or more micro-optical elements (array of micro lenses) downstream of a single solid state light source, such as a LED, or downstream of a plurality of solid state light sources (i.e. e.g. shared by multiple LEDs). In embodiments, the light source may comprise a LED with on-chip optics. In embodiments, the light source comprises a pixelated single LEDs (with or without optics) (offering in embodiments on-chip beam steering).

Herein, the term “light source” especially refers to “solid state light source”. Especially, the lighting device comprises a plurality of solid state light sources.

The phrases “different light sources” or “a plurality of different light sources”, and similar phrases, may in embodiments refer to a plurality of solid state light sources selected from at least two different bins. Likewise, the phrases “identical light sources” or “a plurality of same light sources”, and similar phrases, may in embodiments refer to a plurality of solid state light sources selected from the same bin.

The terms “light source” or “solid state light source” may also refer to a package comprising a light source and optics, or especially a package comprising a solid state light source and optics, respectively. The optics may in specific embodiments comprise a lens, though alternatively or additionally, other optics may also be possible. In embodiments, the solid state light source(s) may be top emitters. Alternatively or additionally, in embodiments the solid state light source(s) may be side emitters.

In specific embodiments, a plurality of the light sources, especially essentially all, may be configured to generate light source in a direction of one of the first foam layer face and the second foam layer face. In alternative embodiments, a subset of the total number of the light sources may be configured to generate light source in a direction of first foam layer face and another subset of the total number of the light sources may be configured to generate light source in a direction of the second foam layer face. In the former embodiments, the lighting device light may essentially emanate from one side of the lighting device, whereas in the latter embodiment the lighting device light may emanate from two sides of the lighting device. The term “lighting device light” especially refers to the light composed of the light source light of the light sources of the (array) of the lighting device (and which emanates from the lighting device during operation).

The one or more light sources are configured to generate light source light. Especially, the light source light comprises visible light source light. In specific embodiments, the light source essentially consist of visible light source light. When there is more than one light source, one or more light sources may provide essentially the same radiation (i.e. radiation with same spectral power distribution). In yet other embodiments, when there are a plurality of light sources, there may be two or more light sources configured to generate light source light having different spectral power distributions. Further, when there are a plurality of light sources, at least one, especially at least 50%, may be configured to generate visible light. Optionally, one or more light sources may be configured to generate UV radiation or IR radiation.

Hence, in embodiments one or more of the light sources may be configured to generate UV light. Such UV light may have one or more wavelengths in the 100-380 nm wavelength region, such as in the 250-380 nm wavelength regions. IR radiation may have one or more wavelengths in the 800-10.000 nm wavelength region, such as one or more wavelengths in the IR-A (800-1400 nm) and/or in the IR-B (1400-3000 nm) and/or in the IR- C (3000- 10000 nm). Especially, IR radiation may have one or more wavelengths in the 800- 3000 nm wavelength region. IR radiation may e.g. be used for LiFi applications. The terms “Li-Fi” or LiFi (“light fidelity”) refers to a wireless communication technology, which utilizes light to transmit data and position between devices. Foams, like PU foams, may also be transmissive for UV and/or IR radiation. Would transmission be too low, a physical opening or channel may be created through which the UV and/or IR can propagate through the foam without having to be transmitted through the foam material (itself).

Especially, one or more, even more especially at least 50% of a plurality of the light sources, such as in embodiments essentially all, may be configured to generate visible light. The terms “visible”, “visible light” or “visible emission” and similar terms refer to light having one or more wavelengths in the range of about 380-780 nm.

In specific embodiments, the lighting device is configured to generate white (especially in at least one operational mode or mode of operation). The term “white light” herein, is known to the person skilled in the art. It especially relates to light having a correlated color temperature (CCT) between about 1800 K and 20000 K, such as between 2000 and 20000 K, especially 2700-20000 K, for general lighting especially in the range of about 2700 K and 6500 K. In yet other embodiments, the CCT is selected from the range of 1800-6500 K. In embodiments, for backlighting purposes the correlated color temperature (CCT) may especially be in the range of about 7000 K and 20000 K. Yet further, in embodiments the correlated color temperature (CCT) is especially within about 15 SDCM (standard deviation of color matching) from the BBL (black body locus), especially within about 10 SDCM from the BBL, even more especially within about 5 SDCM from the BBL.

When two or more light sources are configured to generate visible light, in specific embodiments the spectral distribution of the lighting device light may be controllable. Hence, two or more light sources are configured to generate visible light e.g. one or more of the color point and color rendering index may be controlled. Hence, in yet further specific embodiments the lighting device may be functionally coupled to or may comprise a control system.

For instance, in embodiments a first subset of light sources maybe configured to generate light source light with a first spectral power distribution and a second subset of the light sources may be configured to generate light source light with a second spectral power distribution different from the first. More subsets may also be available. In this way, e.g. light sources may be provided with two or more different correlated color temperatures. In this way, e.g. RGB light sources may be applied, or RGBY light sources may be applied, etc.. When light sources have different spectral power distributions, the color points may e.g. differ with at least 0.005 for u’ and/or with least 0.005 for v’(CIE 1976 UCS (uniform chromaticity scale) diagram). For instance, in embodiments solid state light sources from different bins may be applied. The foam layer may also provide color mixing of the light source light of the different light sources. Hence, the foam layer may have a color mixing and/or homogenizing function(s).

The term “controlling” and similar terms especially refer at least to determining the behavior or supervising the running of an element. Hence, herein “controlling” and similar terms may e.g. refer to imposing behavior to the element (determining the behavior or supervising the running of an element), etc., such as e.g. measuring, displaying, actuating, opening, shifting, changing temperature, etc.. Beyond that, the term “controlling” and similar terms may additionally include monitoring. Hence, the term “controlling” and similar terms may include imposing behavior on an element and also imposing behavior on an element and monitoring the element. The controlling of the element can be done with a control system, which may also be indicated as “controller”. The control system and the element may thus at least temporarily, or permanently, functionally be coupled. The element may comprise the control system. In embodiments, the control system and element may not be physically coupled. Control can be done via wired and/or wireless control. The term “control system” may also refer to a plurality of different control systems, which especially are functionally coupled, and of which e.g. one control system may be a master control system and one or more others may be slave control systems. A control system may comprise or may be functionally coupled to a user interface.

The control system may also be configured to receive and execute instructions form a remote control. In embodiments, the control system may be controlled via an App on a device, such as a portable device, like a Smartphone or I-phone, a tablet, etc.. The device is thus not necessarily coupled to the lighting system, but may be (temporarily) functionally coupled to the lighting system.

Hence, in embodiments the control system may (also) be configured to be controlled by an App on a remote device. In such embodiments the control system of the lighting system may be a slave control system or control in a slave mode. For instance, the lighting system may be identifiable with a code, especially a unique code for the respective lighting system. The control system of the lighting system may be configured to be controlled by an external control system which has access to the lighting system on the basis of knowledge (input by a user interface of with an optical sensor (e.g. QR code reader) of the (unique) code. The lighting system may also comprise means for communicating with other systems or devices, such as on the basis of Bluetooth, WIFI, ZigBee, BLE or WiMAX, or another wireless technology. The system, or apparatus, or device may execute an action in a “mode” or “operation mode” or “mode of operation”. Likewise, in a method an action or stage, or step may be executed in a “mode” or “operation mode” or “mode of operation”. The term “mode” may also be indicated as “controlling mode”. This does not exclude that the system, or apparatus, or device may also be adapted for providing another controlling mode, or a plurality of other controlling modes. Likewise, this may not exclude that before executing the mode and/or after executing the mode one or more other modes may be executed.

However, in embodiments a control system may be available, that is adapted to provide at least the controlling mode. Would other modes be available, the choice of such modes may especially be executed via a user interface, though other options, like executing a mode in dependence of a sensor signal or a (time) scheme, may also be possible. The operation mode may in embodiments also refer to a system, or apparatus, or device, that can only operate in a single operation mode (i.e. “on”, without further tunability).

Hence, in embodiments, the control system may control in dependence of one or more of an input signal of a user interface, a sensor signal (of a sensor), and a timer. The term “timer” may refer to a clock and/or a predetermined time scheme.

In embodiments, the plurality of (solid state) light sources is configured in a ID array. In yet other embodiments, the plurality of (solid state) light sources may be configured in a 2D array. The (ID or especially 2D) array can be a regularly arranged array (with e.g. a single pitch) or a non-regular array, like a random arrangement or a pseudo random arrangement.

The lighting device further comprises (ii) electrical wiring electrically coupled to the solid state light sources. The term “electrically coupled” may especially refer to “electrically conductively coupled”. Hence, via the wiring the light source(s) may be functionally coupled to electronics and/or an electrical power source. The electrical wiring may include one or more isolated electrical conductors. Alternatively or additionally the electrical wiring may include one or more electrically conductive tracks comprised by a substrate, such as an integrated circuit, or a substrate comprising an integrated circuit. In specific embodiments, the integrated circuit may be flexible, e.g. for providing a flexible lighting device. In other embodiments, the integrated circuit may be rigid.

In embodiments, the electrical wiring may be comprised by a printed circuit board (PCB). As known in the art, a printed circuit board may mechanically support and electrically connect electronic components or electrical components using conductive tracks, pads and other features etched from one or more sheet layers of copper laminated onto and/or between sheet layers of a non-conductive substrate (shortly indicated as “track” or “conductive track”). Hence, in embodiments a PCB may comprise an insulating layer arranged between a substrate and a conductive layer. An (electronic) component, such as a solid stage light source, may generally be soldered onto the PCB to both electrically connect and mechanically fasten it to the PCB. For instance, a basic PCB may consist of a flat sheet of insulating material and a layer of copper foil, laminated to the substrate. Chemical etching divides the copper into separate conducting lines called tracks or circuit traces, pads for connections, vias to pass connections between layers of copper, and features such as solid conductive areas for EM shielding or other purposes. The tracks function as wires fixed in place, and are insulated from each other by air and the board substrate material. The surface of a PCB may have a coating that protects the copper from corrosion and reduces the chances of solder shorts between traces or undesired electrical contact with stray bare wires. For its function in helping to prevent solder shorts, the coating is called solder resist. In specific embodiments, the board may comprise a printed circuit board. Especially, the board may comprise one or more of a CEM-1 PCE, a CEM-3 PCE, a FR-1 PCE, a FR-2 PCB, a FR-3 PCB, a FR-4 PCB, and aluminum metal core PCB, especially one or more of a CEM-1 PCB, a CEM-3 PCB, a FR-1 PCB, and a FR4 PCB and an aluminum metal core PCB, more especially one or more of a CEM-1 PCB, a CEM-3 PCB, a FR-1 PCB. In embodiments, the support may comprise a printed circuit board.

In embodiments, the support may be polymeric layer configured to support the light source(s) and the wiring. Hence, in embodiments the electrical wiring may be comprised by a support (in embodiments not being a PCB). In embodiments, the support may comprise one or more of PET, PC and polyimide. In embodiments, the support may be transmissive for the light source light, as may e.g. be the case for polyimide, or PET or PC. In such embodiments, the lighting device may provide device light in two essentially opposite directions. In specific embodiments, the support may be a second foam (see further below about foams).

In embodiments, the wiring may include a wire grid. The wire grid may be comprised by a support.

The lighting device may further comprise electronics, like e.g. a driver, ballast, etc... This is not further elucidated herein.

The lighting device further comprises a foam layer. The foam layer comprises a foam material. Physical foams refer to foams that are generated under high pressures.

Foams may also be made under ambient pressures (though elevated pressures are not necessarily excluded). Herein, the foams are especially obtainable (or especially obtained) via a low-pressure foaming process (see also below).

Foams may especially be produced while using foaming agents or blowing agents, which induce generation of gas. Due to the foaming agent, bubbles may be generated, whereby the foam is created.

The foam material is especially transmissive for at least part of the light source light. Hence, the foam material may essentially be colorless. In this way, light source light may enter the foam, propagate through the foam, but also exit again from the foam. The presence of bubbles leads to a scattering of the light source light. Hence, in this way the foam layer can be used as scattering element. Further, the foam layer can provide strength to the device and/or even have the function of a support. Even more, in this way the foam allows generating lighting devices essentially without, i.e. free from, additional edge elements, as the foam may essentially provide the edge of the device. This may allow a rimless configuration of (adjacent) lighting devices.

Further, the foam may protect the light sources. In specific embodiments, the foam layer may also be flexible, which may allow a flexible lighting device in embodiments. In yet other embodiments, the foam layer may be (mechanically) rigid.

Suitable foam materials may be polyurethanes (PU). PU can be light transmissive, even light transparent. Other suitable foam materials may be selected from the group consisting of ethylene-vinyl acetate (EVA) foam, the copolymers of ethylene and vinyl acetate (also referred to as polyethylene-vinyl acetate (PEVA)), low-density polyethylene (LDPE) foam, first grade of polyethylene (PE), nitrile rubber (NBR) foam, the copolymers of acrylonitrile (ACN) and butadiene, polychloroprene foam or neoprene, polyimide foam, polypropylene (PP) foam, including expanded polypropylene (EPP) and polypropylene paper (PPP), polystyrene (PS) foam, including expanded polystyrene (EPS), extruded polystyrene foam (XPS), polyethylene foam, polyvinyl chloride (PVC) foam, silicone foam, etc... Alternatively or additionally, a polycarbonate (PC) foam may be applied. Essentially any polymeric material may be used that is transmissive for visible radiation and that can be made as foam during polymerization.

Hence, the foam layer is especially a polymeric foam layer. The foam material is thus especially a polymeric material (like comprising organic polymers (such as mentioned above) and/or inorganic-organic polymers (like e.g. siloxane polymers). Hence, the term “foam material” may in specific embodiments also refer to a combination of different foam materials. The term “foam layer” may also refer to multi-layer of identical or different types of foams.

In embodiments, the polymeric material may especially be based on the use of a chemical setting agent and/or on the basis of the use of a foaming agent, such as an aerosol, etc.. Hence, in specific embodiments the foam layer and foam material, and similar terms, may herein also be indicated as “chemical foam layer” or “chemical foam material”, respectively.

In specific embodiments, the foam material comprises one or more of a polyurethane foam. PU foams can be relatively stable toward UV radiation and may have a relatively high transmission for visible light. Further, as indicated above, the foam material may also comprise a combination of different foam materials.

The transmission or light permeability can be determined by providing light at a specific wavelength with a first intensity to the material and relating the intensity of the light at that wavelength measured after transmission through the material, to the first intensity of the light provided at that specific wavelength to the material (see also E-208 and E-406 of the CRC Handbook of Chemistry and Physics, 69th edition, 1088-1989).

In specific embodiments, a material may be considered transmissive when the transmission of the radiation at a wavelength or in a wavelength range, especially at a wavelength or in a wavelength range of radiation generated by a source of radiation as herein described, through a 1 mm thick layer of the material, especially even through a 5 mm thick layer of the material, under perpendicular irradiation with said radiation is at least about 20%, such as at least 40%, like at least 60%, such as especially at least 80%, such as at least about 85%, such as even at least about 90%.

As indicated above, in embodiments the foam may at least partly enclose one or more of the one or more light sources. Hence, when there are a plurality of light sources, at least part of the plurality of light sources may be at least partly be enclosed by the foam. Such light sources may be in physical contact with the foam material. At least part of the external surface of such light source may be in contact with the foam material, such as at least about 20%, like in embodiments at least about 50%.

Hence, the foam may enclose a plurality of the solid state light sources. In specific embodiments, the foam at least partly encloses all light sources. As indicated above, this may provide protection and/or may simplify the structure of the lighting device and/or may enhance the robustness of the device, etc.. Hence, in embodiments one or more of the one or more light sources, especially all light sources of the plurality of light sources may be at least partly embedded in the foam. Therefore, at least part of the foam material is configured downstream of the light source(s).

The terms “upstream” and “downstream” relate to an arrangement of items or features relative to the propagation of the light from a light generating means (here the especially the light source), wherein relative to a first position within a beam of light from the light generating means, a second position in the beam of light closer to the light generating means is “upstream”, and a third position within the beam of light further away from the light generating means is “downstream”.

The foam layer has a first foam layer face and a second foam layer face. Especially, these two faces define the thickness of the foam layer. In specific embodiments, the thickness is essentially constant over the entire foam layer. In yet other embodiments, there may be different thicknesses. In specific embodiments, the first foam layer face and the second foam layer face define a first height (HI) selected from the range of 0.5-50 mm. Hence, in embodiments the thickness of the foam layer may vary within this range. In yet other embodiments, the thickness is essentially even over the foam layer (and selected from this range). Even when the foam layer may be curved, in embodiments the thickness may essentially be even over the foam layer (and selected from this range).

Especially, in embodiments the foam layer has a length and a width (or optionally a diameter, i.e. the length and width are identical and the foam layer has a circular cross-section), which are each individually at least n times larger than first height. In embodiments, n is 2, such as especially 5, like more especially 10, like even more especially 20. Further, n may be at maximum e.g. about 1000, such as at maximum about 500, like at maximum about 200. Hence, the layer (and especially also the device) may have a plate-like shape and/or may especially have an essentially 2D shape. Hence, in embodiments the foam layer may have one or more aspect ratios of at least 2, such as especially at least 5, like more especially at least 10, like even more especially at least 20, or even much larger, such as at least 100. In specific embodiments, the one or more aspect ratios may be at maximum about 1000, such as at maximum about 500, like at maximum about 200.

The foam layer may have essentially any shape. The foam layer may be planar. However, the foam layer may also be ID curved or 2D curved. The foam layer may be planar and have a square, round, hexagonal, elliptical, etc. cross-section. The foam layer may be free-shaped. Hence, the ID array of light sources or 2D array of light sources is not necessarily a planar array of light sources. As indicated above, the thickness or height of the foam layer may in embodiments be essentially even. Hence, especially the light source(s) are configured at one side of the foam layer. In specific embodiments at least part of the light source light escapes from another side of the foam. Hence, during operation of the lighting device at least part of the (visible) light source light emanates from at least one of the first foam layer face and the second foam layer face. The lighting device may further comprise one or more reflectors in order to promote predominant outcoupling via one of the first foam layer face and the second foam layer face. Such reflector(s) may be configured at an edge. Alternatively or additionally, such reflector may be configured (at least) between adjacent light sources (see further also below). For instance, in embodiments the first foam layer face may be provided with a reflective layer, such as a reflective coating. Herein, the term “reflective” especially refers to reflective for visible light source light. In specific embodiments, over the wavelength range of the visible light source light, the reflectivity may be in average at least 20%, such as at least 30%, especially at least 50%, such as at least 70%, like at least 80%, under perpendicular radiation (with the (solid state) light source light.

In alternative embodiments, the light source light may escape from the first foam layer face and the second foam layer face. Further, in specific embodiments the light sources may essentially entirely be embedded in the foam layer. This may facilitate escape from light source light in two (opposite) directions.

In embodiments, the support may be a foam layer (herein also indicated as “second foam layer”) to which the herein described foam layer is provided, in this way a lighting device may be provided which may be essentially based on light sources essentially fully embedded in a foam.

As indicated below, the wiring may be comprised by an integrated circuit, such as copper tracks on a substrate, or the wiring may comprise electrically conducting cables, or the wiring may comprise a wire grid. Amongst others, in such embodiments at least part of the electrical wiring is in physical contact with the foam layer or is partly embedded in the foam layer. Especially, when the foam is applied to a substrate on which the wiring is available, the wiring is in physical contact with the foam layer or is partly embedded in the foam layer.

Hence, in specific embodiments the foam layer (and the foam material) is electrically insulating. Herein, a conductive material may especially comprise a conductivity (at room temperature) of at least MO ⁵ S/m, such as at least 1-10 ⁶ S/m. Herein a conductivity of an insulated material may especially be equal to or smaller than l-lO ¹⁰ S/m, especially equal to or smaller than 1- 10 ¹³ S/m. Herein a ratio of an electrical conductivity of an isolating material (insulator) and an electrical conductivity of a conductive material (conductor) may especially be selected smaller than 1-10 ¹⁵ .

The foam layer may in embodiments also be used as building element, to which the lighting elements are added. For instance, because the foam layeris a self- supporting layer comprising the (solid state) light sources and the electrical wiring, hence then the lighting device does not require a (separate) support. Hence, in specific embodiments the foam layer is a self-supporting layer applied as a rigid building element. A self-supporting layer may support its own weight. Especially, it may not significantly deform under its own weight. Herein, in embodiments the self-supporting layer may especially self- supporting also in the presence of the electrical wiring and the one or more (solid state) light sources, and optionally other components associated thereto.

As indicated above, the lighting device may comprise a support, e.g. a support comprising a PCB, or the lighting device may not comprise a support. The former embodiment may allow e.g. easily adding a reflector and/or providing strength; the latter embodiment then is self-supporting, i.e. it does not significantly deform under its own weight due to gravity. Yet, a specific embodiment of the latter embodiment, wherein its shape can be adapted under exertion of additional forces other than gravity, may provide even more flexibility in use or even allow flexible lighting devices (though in specific embodiments the support may also be flexible, thereby in specific embodiments also allowing a flexible lighting device). Hence, in specific embodiments the lighting device may further comprise a first support, in specific embodiments especially configured to support the electrical wiring, wherein the first support comprises a first support face and a second support face, wherein the second support face is in contact with the first foam layer face, and wherein in further specific embodiments the second support face is reflective for at least part of the light source light. For instance, at least part of the second support face may be provided with a white coating or with a metallic coating. Note that additionally or alternatively, the first foam layer face may be provided with a reflective layer, such as a reflective coating.

In specific embodiments, the support comprises a second foam layer (see also above). In embodiments, such second foam layer may be produced, where after the electrical wiring and light sources are provided. For instance a wire grid with (solid state) light sources may be provided. This may be then be used as support for the formation of the foam layer. This may provide in embodiments a flexible lighting device. Further, adhesion of the foam layer to the second foam layer may be good. The foam may adhere to the support as in embodiments the foam may have adhesive properties and/or because the support and foam allow association via e.g. Van der Waals forces, which is known in the art. In embodiments, the support may comprise one or more coating facilitating elements to improve functional coupling of the foam layer to the support, which may be selected from the group consisting of an adhesive layer, surface roughness, and barb elements.

In embodiments, the support may be planar. In embodiments the support may be flexible. In embodiments, the support may comprise a textile.

In embodiments, the support may be one dimensionally curved. In embodiments the support may be two dimensionally curved. Hence, likewise, in embodiments the foam layer may be one dimensionally curved or two dimensionally curved, respectively. The support may be thermo-formed.

At one face of the foam, a support may be available. Alternatively or additionally, at another face a light transmissive window (“window”) may be available. Note that the light transmissive window may in specific embodiments also be configured as support. Especially, the light transmissive window may be available in embodiments wherein at or close to another face of the foam a reflective layer is available, thereby promoting light outcoupling via the light transmissive window. Hence, in embodiments the lighting device may further comprise a light transmissive window, wherein the light transmissive window comprises a first window face and a second window face, wherein the first window face is in contact with the second foam layer face, wherein in specific embodiments during operation of the lighting device at least part of the light source light emanates from the second window face. As will be indicated below, the window may also be used to control the height of the foam layer.

Especially, the light transmissive window is not a foam. Such light transmissive window may comprise one or more of the above-indicated polymeric materials (but essentially unfoamed). Also other light transmissive materials may be applied for the light transmissive window.

In embodiments, the window may be planar. In embodiments the window may be flexible. In embodiments, the window may be one dimensionally curved. In embodiments the window may be two dimensionally curved. Hence, likewise, in embodiments the foam layer may be one dimensionally curved or two dimensionally curved, respectively.

With the present invention, a single element may be provided comprising useful functions, like an element comprising the foam layer, the light source(s), and the wiring. Hence, in specific embodiments the lighting device comprises a lighting element, wherein the lighting element consists of the (solid state) light source(s), the electrical wiring, the foam layer enclosing (at least part of a plurality of) the (solid state) light source(s), and optionally one or more of (i) the first support (see also above) and (ii) the light transmissive window (see also above).

As indicated above, the foam comprises bubbles. The bubble size and the porosity may be controlled by controlled e.g. reaction time, concentration of foaming agents or blowing agents, the type of foaming agents or blowing agents, the type of polymeric material, as known in the art. In specific embodiments, the porosity may be selected from the range of 15-99%, such as selected from the range of 30-98%, like 50-98%, such as up to 95%, like up to about 90%. For instance, in embodiments the porosity may be in the range of about 70-95%. The higher the porosity, the more scattering. The porosity may be defined as the volume of the bubbles relative to the total volume. Hence, porosity or void fraction is a measure of the void (i.e. "empty") spaces in a material, and is a fraction of the volume of voids over the total volume, ranging in theory from larger than 0% to smaller than 100%. In view of the balance between savings in material, hence in weight reduction, i.e. preferably as much as possible, and on the other hand enough material to obtain sufficient mechanical strength and scattering of the foam layer and/or foam panel, a preferred range for the porosity of the foam appeared to be in the range of 85%-95%. When the foam layer and/or foam panel has sufficient mechanical strength, a basic lighting element may consist (essentially) of the solid state light sources, the electrical wiring electrically connecting the light sources and by which the lighting element is connectable to an external power source, and the foam layer/panel enclosing at least part of a plurality of the solid state light sources. The bubbles may have volume averaged bubble sized selected from the range of 50 pm - 5 mm. Especially, in embodiments the volume averaged bubble size is selected from the range of 0.02-5 mm, such as 0.1-5 mm, such as 0.5-3 mm. Hence, in embodiments the foam material has a porosity selected from the range of 50-98% and a volume averaged bubble size selected from the range of 50 pm - 5 mm. In specific embodiments, the volume averaged bubble size is selected from the range of at least 800 pm, such as over 1 mm.

In yet a further aspect, the invention also provides a method of producing a lighting device, which method may comprise providing a support with one or more light sources and providing the foam layer on such support. Especially, the method may comprise providing a second support a 2D array of one or more (solid state) light sources, wherein the one or more (solid state) light sources are configured to generate light source light, and (ii) electrical wiring electrically coupled to the one or more (solid state) light sources. The method may further comprise providing a layer comprising precursor of a foam material over the 2D array of one or more (solid state) light sources, and allowing the precursor of the foam material react to a foam layer during a foam formation time. Especially, the foam layer comprises the foam material. Further, in specific embodiments the foam material is transmissive for at least part of the light source light. Therefore, in embodiments the invention also provides a method of producing a lighting device comprising: (a) providing a second support a 2D array of solid state light sources, wherein the solid state light sources are configured to generate light source light, and (ii) electrical wiring electrically coupled to the solid state light sources; and (b) providing a layer comprising precursor of a foam material over the 2D array of solid state light sources, and allowing the precursor of the foam material react to a foam layer during a foam formation time, wherein the foam layer comprises the foam material, and wherein the foam material is transmissive for at least part of the light source light.

As indicated above, the method may comprise providing a second support.

This second support may be a support per se, such as for use in the foaming stage only, after which the foam including the light source(s) and wiring may be removed. For instance, this may be in the case of a wire grid with one or more light sources, especially a plurality of light sources. Such second support is essentially a temporary support. However, the second support may also comprise or be the first support. In such embodiments the foam and support are comprised by the lighting device. Hence, in embodiments the second support comprises a first support configured to support the electrical wiring, wherein the first support comprises a first support face and a second support face, wherein the second support face is in contact with the (precursor of a foam material and later with the thus formed) first foam layer face, and wherein the second support face is reflective for at least part of the light source light (see also above).

In embodiments, the second support may be planar. In embodiments the second support may be flexible. In embodiments, the second support may be one dimensionally curved. In embodiments the second support may be two dimensionally curved. Hence, likewise, in embodiments the foam layer may be one dimensionally curved or two dimensionally curved, respectively.

Further, the foam layer is provided which may be obtained by providing a layer comprising precursor of the foam material over the 2D array of solid state light sources, and allowing the precursor of the foam material react to a foam layer during a foam formation time.

The precursor material may in embodiments comprise monomers for forming the polymer. Further the precursor material may comprise a foaming agent. However, alternatively or additionally, other methods may be used to create to foam. For instance, in embodiments the polyurethane (precursor) may be blown onto the second support.

The precursor may (thus) in embodiments comprise the polymeric material (i.e. already (essentially) polymerized).

The phrase “allowing the precursor of the foam material react to a foam layer during a foam formation time” may also indicate “allowing the precursor of the foam material develop to a foam layer during a foam formation time”. Instead of the term “develop” in this phrase, also the term “rise” may be used.

In embodiments, monomeric ingredients are combined to form a hot liquid polyurethane, or other polymeric foamable material, and are passed down through a pipe into a nozzle head. Beneath the head may be a support. The nozzle jets a fine spray of hot liquid over the support, mixing with blasts of carbon dioxide (and/or other gas, such as N2) coming from another nozzle. This causes the polyurethane (or other polymeric foamable material) to expand, forming a foam strip. The foam is comprised of a large number of tiny gas bubbles trapped in the polyurethane (or other polymeric foamable material).

In embodiments, a process similar to conventional injection molding may be applied with the exception that a foaming agent, typically nitrogen gas, may be mixed with the melted polymer and injected into a mold at low pressures. During injection the mold is not completely filled or packed out with resin as it would be with high pressure molding. Immediately following injection the gas/polymer mixture is allowed to expand to pack out the mold and to create a density reduced, rigid, plastic part.

In embodiments, aerosol based solutions may be chosen. For instance, insulating foam sealant products are available, which are sometimes called one-component foam. With the two component insulation products, the chemicals that make up the foam are kept separated in different drums or containers until mixed. The one-component foam (e.g. “foam in a can”) product may have already been partly mixed and partly reacted. That may be one of the reasons why this product is widely available. Hence, the foam layer herein is especially obtainable via a low pressure foaming process. The term low pressure may refer to pressures at ambient pressure and especially lower than about 35 bar, such as in the range of 10-30 bar (1-3 MPa), or lower. Hence, in specific embodiments the foam layer and foam material, and similar terms, may herein also be indicated as “low-pressure foam layer” or “low-pressure foam material”, respectively.

Low-pressure foaming technologies are known in the art.

Especially, a precursor material is selected that leads to a foam material which is transmissive for at least part of the light source light (see also above).

The reaction time may especially be chosen such that the desired foam layer height (or thickness) is obtained. This may e.g. be (already) the case when the foam layer rises and reaches a counter element, such as a window. In this way the height may be controlled. Note that in specific embodiments even after reaching a specific height, the polymerization reaction may continue.

As indicated above, in embodiments the method may further comprising arranging a counter element on the layer comprising the precursor of the foam material before the end of the foam formation time. This may also include arranging a counter element over the second support, before or while the precursor is applied to the second support. Then, the foam may rise up to the counter element.

In embodiments, the counter element may be planar. In embodiments the counter element may be flexible. In embodiments, the counter element may be one dimensionally curved. In embodiments the counter element may be two dimensionally curved. Hence, likewise, in embodiments the foam layer may be one dimensionally curved or two dimensionally curved, respectively.

In specific embodiments of the method, either (i) subsequent to arranging the counter element and after subsequent at least part of the foam formation the counter element the method may further comprise removing the counter element and optionally arranging a light transmissive window on the thus formed layer, or (ii) the counter element comprises the light transmissive window. As indicated above, the light transmissive window is transmissive for at least part of the (visible) light source light.

As can be derived above, in specific embodiments the precursor of the foam material may be a precursor of a polyurethane foam or of a PC foam, or of a combination of a PC and a PU foam, especially (at least) a PU foam. However, as indicated above, other foams are not excluded.

In yet a further aspect, the invention also provides a luminaire comprising the lighting device as described herein (such as in embodiments obtainable according to the method as described herein). In yet further embodiments, the invention also provides a luminaire comprising a plurality of the lighting devices as described herein. In yet further specific embodiments, the invention provides a luminaire comprising a plurality of lighting devices (as described herein), wherein foam layers of adjacent lighting devices are in physical contact. This may especially be possible with the herein described rimless lighting devices. Hence, in embodiments the lighting device is a rimless lighting device.

The lighting device may be part of or may be applied in e.g. office lighting systems, household application systems, shop lighting systems, home lighting systems, accent lighting systems, spot lighting systems, theater lighting systems, fiber-optics application systems, projection systems, self-lit display systems, pixelated display systems, segmented display systems, warning sign systems, medical lighting application systems, indicator sign systems, decorative lighting systems, portable systems, automotive applications, (outdoor) road lighting systems, urban lighting systems, green house lighting systems, horticulture lighting, digital projection, or LCD backlighting.

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, and in which:

Figs la-le schematically depict some embodiments;

Figs. 2-3 schematically depict some further embodiments.

The schematic drawings are not necessarily to scale.

DETAILED DESCRIPTION OF THE EMBODIMENTS

Fig. 1 schematically depicts some aspects. It schematically shows some elements of the lighting device 1000, but in a way that several elements are shown separate. Other embodiments are schematically depicted in amongst others Figs lb-ld.

The lighting device 1000 comprises a 2D array 100 of (solid state) light sources 10. The (solid state) light sources 10 are configured to generate light source light 11. This may be white light or colored light. The lighting device 1000 further comprises electrical wiring 200 electrically coupled to the (solid state) light sources 10. Driver, ballast, a power source, and optionally further electrical components, are not depicted (but may also be comprised by the lighting device 1000. The lighting device 1000 further comprises a foam layer 300. The foam layer 300 may enclose at least part of a plurality of the solid state light sources 10 (see Figs lb-ld). The foam layer 300 comprises a foam material 305 that is transmissive for at least part of the light source light 11. Further, the foam layer 300 has a first foam layer face 301 and a second foam layer face 302. During operation of the lighting device 1000 at least part of the light source light 11 emanates from at least one of the first foam layer face 301 and the second foam layer face 302 (see also below in Figs lb-ld).

Figs la and lb schematically also depicts how the lighting device 1000 may be produced. This may amongst others on the basis of a method comprising: providing a second support 1400 a 2D array 100 of solid state light sources 10, wherein the solid state light sources 10 are configured to generate light source light 11, and electrical wiring 200 electrically coupled to the solid state light sources 10.

Further, the method may comprise: providing a layer 1300 comprising precursor 1305 of a foam material 305 over the 2D array 100 of solid state light sources 10, and allowing the precursor 1305 of the foam material 305 react/develop to a foam layer 300 during a foam formation time, wherein the foam layer 300 comprises the foam material 305, and wherein the foam material 305 comprises edge 307 and is transmissive for at least part of the light source light 11. The precursor material may in embodiments polymeric material that is provided with a gas, like CO2 and/or N2 or other gas which creates bubbles, due to the formation of voids (bubbles) in the polymeric material that encloses the gas. Other low- pressure processes for polymeric foam formation may also be applied.

The height (indicated also as first height; see Fig. lb lowest drawing) of the foam layer 300 may be defined by the first foam layer face 301 and the second foam layer face 302. The first height HI selected from the range of 0.5-50 mm.

The second support 1400 may comprises a first support 400 configured to support the electrical wiring 200, wherein the first support 400 comprises a first support face 301 and a second support face 302, wherein the second support face 302 is in contact with a first foam layer face 301, and wherein the second support face 302 is reflective for at least part of the light source light 11 (see also above). References 1401 and 1402 refer to the first face and second face of the second support, respectively.

The method may further comprise arranging a counter element 1500 on the layer 1300 comprising the precursor 1305 of the foam material 305 before the end of the foam formation time.

This counter element 1500 may stay, may be removed, or may be removed and replaced. Hence, the method may in embodiments further comprise arranging a counter element 1500 on the layer 1300 comprising the precursor 1305 of the foam material 305 before the end of the foam formation time, wherein either (i) subsequent to arranging the counter element 1500 and after subsequent at least part of the foam formation the counter element 1500 the method further comprises removing the counter element 1500 and optionally arranging a light transmissive window 500 on the thus formed layer, or (ii) the counter element 1500 comprises the light transmissive window 500. References 1501 and 1502 refer to the first face and second face of the counter element, respectively.

Fig. lb schematically depicts a plurality (three) of possible embodiments, including window 500 or not including window 500, and including support 400 or not including support 400. More embodiments are not excluded, but not drawn in this schematically drawing.

Hence, in embodiments the lighting device may further comprise a first support 400 configured to support the electrical wiring 200. The first support 400 may comprise a first support face 401 and a second support face 402. Further, the second support face 402 may thus be in contact with the first foam layer face 301. In specific embodiments, the second support face 402 may be reflective for at least part of the light source light 11.

Hence, also in embodiments the lighting device 1000 may further comprise a light transmissive window 500, wherein the light transmissive window 500 comprises a first window face 501 and a second window face 502. The first window face 501 may be in contact with the second foam layer face 302. In embodiments, during operation of the lighting device 1000 at least part of the light source light 11 emanates from the second window face 502 (see also Fig. lb).

Figs lb, Id and le (see further below), also schematically depict embodiments of a lighting element 1100 consisting (essentially) of the solid state light sources 10, the electrical wiring 200, the foam layer 300 enclosing at least part of a plurality of the solid state light sources 10, and optionally one or more of (i) the first support 400 and (ii) the light transmissive window 500.

As schematically depicted in amongst others Fig. lb, in embodiments at least part of the electrical wiring 200 is in physical contact with the foam layer 300 or is partly embedded in the foam layer 300.

The last drawing right below in Fig. lb is a schematically cross-section of the most right option of the three possible embodiments.

As indicated above, the foam layer 300 may in embodiments be a self- supporting layer.

Device light, which may essentially consist of light source light 11, is indicated with reference 1001. Fig. lc schematically depicts an embodiment of a luminaire 2 comprising a plurality of lighting devices 1000. However, a luminaire 2 may also comprise a single lighting device. Note that with the present invention the foam layers 300 of adjacent lighting devices 1000 may be in physical contact, as rimless design may be possible. Fig. Id schematically depicts an embodiment wherein coating facilitating elements 420 are used. These coating facilitating elements 420 may improve functional coupling of the foam layer 300 to the support 400. The coating facilitating elements 420 which may be selected from the group consisting of an adhesive layer, surface roughness (left part of the drawing), and barb elements (right part of the drawing; three barb elements are schematically depicted). Fig. le schematically depicts a cross-section of curved lighting device. The curvature may be ID or 2D.

Figs. 2a-2b schematically show an embodiment wherein the foam layer 300 is formed as luminaire or part of a luminaire 1000; more details can be found in the cross- section of part of the device in Fig. 2b. Light sources (not individually shown) may be available in different faces of the lighting device. Other functional components, like e.g. a driver, etc., may be configured in the open volume above the support 400.

The support may include LEDs mounted on it and may be folded into the correct shape. Then structural optical foam is applied to create a rigid (non-blocking) optical element. The image could be a quarter model or full model and different folding shapes could be created. The edge 307 folded inwards may create mechanical luminaire support. The angled surface from the support may be used to provide the desired spatial light distribution of device light 1001, 11.

Figs. 3a and 3b schematically depict yet a further embodiment, wherein the shape is even more free. Light sources (not individually shown) may be placed at several positions.

For instance, the support may be thermo-formed. Light sources may be added to the support, e.g. LED strips. Electronics could be placed in the hollow shapes of the luminaire.

It may be easy with the present invention to make volume products with limited tooling.

The term “plurality” refers to two or more.

The terms “substantially” or “essentially” herein, and similar terms, will be understood by the person skilled in the art. The terms “substantially” or “essentially” may also include embodiments with “entirely”, “completely”, “all”, etc. Hence, in embodiments the adjective substantially or essentially may also be removed. Where applicable, the term “substantially” or the term “essentially” may also relate to 90% or higher, such as 95% or higher, especially 99% or higher, even more especially 99.5% or higher, including 100%.

The term “comprise” includes also embodiments wherein the term “comprises” means “consists of’.

The term “and/or” especially relates to one or more of the items mentioned before and after “and/or”. For instance, a phrase “item 1 and/or item 2” and similar phrases may relate to one or more of item 1 and item 2. The term "comprising" may in an embodiment refer to "consisting of but may in another embodiment also refer to "containing at least the defined species and optionally one or more other species".

Furthermore, the terms first, second, third and the like in the description and in the claims, are used for distinguishing between similar elements and not necessarily for describing a sequential or chronological order. It is to be understood that the terms so used are interchangeable under appropriate circumstances and that the embodiments of the invention described herein are capable of operation in other sequences than described or illustrated herein.

The devices, apparatus, or systems may herein amongst others be described during operation. As will be clear to the person skilled in the art, the invention is not limited to methods of operation, or devices, apparatus, or systems in operation.

It should be noted that the above-mentioned embodiments illustrate rather than limit the invention, and that 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 "to comprise" and its conjugations does not exclude the presence of elements or steps other than those stated in a claim. Unless the context clearly requires otherwise, throughout the description and the claims, the words “comprise”, “comprising”, and the like are to be construed in an inclusive sense as opposed to an exclusive or exhaustive sense; that is to say, in the sense of “including, but not limited to”.

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 a device claim, or an apparatus claim, or a system 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.

The invention also provides a control system that may control the device, apparatus, or system, or that may execute the herein described method or process. Yet further, the invention also provides a computer program product, when running on a computer which is functionally coupled to or comprised by the device, apparatus, or system, controls one or more controllable elements of such device, apparatus, or system.

The invention further applies to a device, apparatus, or system comprising one or more of the characterizing features described in the description and/or shown in the attached drawings. The invention further pertains to a method or process comprising one or more of the characterizing features described in the description and/or shown in the attached drawings.

The various aspects discussed in this patent can be combined in order to provide additional advantages. Further, the person skilled in the art will understand that embodiments can be combined, and that also more than two embodiments can be combined. Furthermore, some of the features can form the basis for one or more divisional applications.