Folded to open heat sink for ultra small, recessed ceiling spots

Abstract

The invention provides a lighting arrangement (1) comprising a light generating device (100), a heat spreader (200), and a ceiling arrangement (301); wherein (I) the light generating device (100) comprises (i) a first device portion (120) comprising a first side (121) of the light generating device (100) and (ii) a second device portion (140) comprising a second side (141) of the light generating device (100); wherein the first device portion (120) comprises a heat dissipating surface (130); wherein the light generating device (100) is configured to emit device light (101) from the second side (141); (II) the heat spreader (200) comprises a thermally conductive material having a thermal conductivity of at least 150 W / m / K in-plane; (III) the ceiling arrangement (301) comprises (a) a ceiling board (310) and (b) a cavity (350), configured at a first ceiling board side (311); wherein the board (310) comprises a through-hole (360); (IV) the light generating device (100) is at least partly configured in the ceiling arrangement (301), wherein the first device portion (120) is at least partly configured in the cavity (350) and wherein the second device portion (140) is at least partly configured in the through-hole (360); wherein the light generating device (100) is configured for illuminating a space (500) arranged at a second ceiling board side (312) with the device light (101); and (V) the heat spreader (200) is configured in the cavity (350); and wherein the heat dissipating surface (130) and the heat spreader (200) are configured in thermal contact with each other.

Description

[0001] Folded to open heat sink for ultra small, recessed ceiling spots

[0002] FIELD OF THE INVENTION

[0003] The invention relates to a lighting arrangement. The invention further relates to a kit of parts comprising a light generating device and a heat spreader. The invention also relates to a method of installing a light generating device with a heat spreader in e.g. a ceiling arrangement.

[0004] BACKGROUND OF THE INVENTION

[0005] Small ceiling spots (or “downlights”) for recessed installation are known in the art. US10174891B1, for instance describes a recessed, adjustable LED downlight for shallow plenum installations. The fixture comprises a bottom plate, a circular base rotatable along an upper surface of the bottom plate, a heat sink enclosure secured to the upper surface of, and rotatable with, the circular base, and a bridge. The heat sink enclosure comprises a pair of fins on first opposite sides of the light source enclosure and a pair of tracks formed in second opposite sides of the heat sink enclosure between the pair of fins. The bridge, to which an LED module is secured, is affixed to the heat sink enclosure, whereby heat from the LED module is transferred to, and dissipated by, the bridge. The bridge is engaged with and pivotable along the pair of tracks in the heat sink enclosure.

[0006] SUMMARY OF THE INVENTION

[0007] There is a strong trend towards decreasing the size of recessed ceiling spots / downlights. However, the small size may limit the amount of heat they can dissipate in the ceilings. This may especially be true for canless designs in e.g., insulated ceilings (especially wherein insulating material can come in direct contact with the spot). Using prior art solutions (e.g., using a heatsink with fins) may limit the maximal output to about 400 lumen to obtain a desired cooling of a spot with a diameter of less than 2.5 inch. A standard heat sink may not be enough to cool a small light source (e.g. with a diameter of less than 2.5 inch) generating for instance a luminous flux of 1000 lumen (which may result in a thermal load of about 8 W). Cooling the spot below the ceiling and / or in the recess in the ceiling may be hard due to the small size of the spot. Moreover, also when applying a trim flange, the trim of a small spot may be rather small and may hardly dissipate heat to the ambient atmosphere. It appears that a thermal breakthrough may be needed before small spots with a high flux output may be installed in recessed ceilings. Such breakthrough may require an improved heat dissipation above a false ceiling (especially in the so-called plenum).

[0008] Hence, it is an aspect of the invention to provide an alternative lighting arrangement, which preferably further at least partly obviates one or more of above-described drawbacks. It is a further aspect of the invention to provide a kit of parts comprising a light generating device and a heat spreader, which preferably further at least partly obviates one or more of above-described drawbacks. The invention may further provide a method for installing a light generating device, which preferably further at least partly obviates 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.

[0009] According to a first aspect, the invention provides a lighting arrangement. The lighting arrangement may in embodiments comprise a light generating device. In embodiments, the lighting arrangement may further comprise a heat spreader. The lighting arrangement may in further embodiments comprise a construction arrangement. The light generating device may especially comprise a first device portion and a second device portion. In embodiments, the first device portion may comprise a first side of the light generating device. Further, especially, the second device portion may comprise a second side of the light generating device. The light generating device may in embodiments be configured to emit device light from the second side, especially during operation of the light generating device. The first side and the second side may especially be opposite sides of the light generating device. In further embodiments, the first device portion comprises a heat dissipating surface. In embodiments, the heat spreader may comprise a thermally conductive material. The thermally conductive material may in embodiments, for instance, have a thermal conductivity of at least 150 W / m / K (in-plane). The construction arrangement may in embodiments comprise a board and a cavity, (the cavity being) configured at a first board side (of the board). The cavity may in specific embodiments comprise an insulation material. The cavity may for instance be filled with an insulation material. In further embodiments, the board comprises a through-hole (especially from the first board side to a second board side). The first board side and the second board side especially comprise opposite sides of the board. In embodiments, the light generating device is (at least partly) configured in the construction arrangement. The first device portion may in embodiments at least partly be configured in the cavity. In specific embodiments, the first device portion may contact the insulation material. Further, the second device portion may in further embodiments at least partly be configured in the through-hole. The light generating device may especially be configured for illuminating a space, arranged at the second board side, with the device light. The space is in embodiment configured in a light receiving relationship with the second side (of the light generating device). In further embodiments, the heat spreader may be configured in the cavity. The heat dissipating surface and the heat spreader are further especially configured in thermal contact with each other.

[0010] To configure the heat spreader in the cavity (e.g., using the method of the invention) the heat spreader may in embodiments be provided into the cavity via the through- hole. The heat spreader may especially be collapsed or folded to move the heat spreader through the through-hole. After moving the heat spreader through the through-hole, the heat spreader may be unfolded or spread out (again) to enlarge the effective heat exchanging surface. The heat spreader may therefore in embodiments have a collapsed, folded, “furled” configuration and a spread-out, unfolded, “unfurled” configuration. Moreover, the heat spreader may in embodiments comprise folding lines, perforations, or e.g., creases or scores (weakened or depressed lines in the heat spreader) to facilitate folding and unfolding the heat spreader to switch between the furled configuration (A) and the unfurled configuration (B). Or differently worded, the heat spreader comprises a heat exchanging surface area comprising sub-surfaces with a respective heat exchanging surface sub-areas, wherein subsurfaces are arranged in a furled (or spiraled) configuration around the heat dissipating surface of the first device portion of the light generating device. In the context of this invention, the expression “furled configuration” is to be understood as the sub-surfaces to extend (more or less in a curved manner) essentially along the tangential direction partially next to each other and to overlap (in a projected view) in the radial direction, and optionally even abut each other in the radial direction. Thus, it is enabled that the heat spreader can assume in the collapsed configuration a relatively (very) compact shape with a relatively (very) small cross-sectional diameter. This has the advantage that the heat exchanging surface area has a relatively (very) large heat dissipating area, but yet that the heat spreader can be passed through a relatively (very) small opening in a (false) ceiling enabling the light generating device to be unobtrusively mountable in the (false) ceiling. A further advantage is that such an unobtrusive mounting of the light generating device is aesthetically attractive. In embodiments, a total size of the heat exchanging surface may correspond to a total size of an area of the first board side that may be covered by the heat spreader in the unfurled configuration.

[0011] Herein the term “folding line” may especially refer to a physical shape providing a bendable or foldable line or zone. The folding line may comprise a perforated line or e.g., a crease or a score (line). A total of the foldable lines may define a folding pattern. The folding pattern may especially be configured to ease spreading out of the heat spreader at the first board side. The folding pattern may further be configured for assisting in providing the thermal contact between the heat spreader and the heat dissipating surface (see also further below). In the furled configuration, the heat spreader may in embodiments be folded according to the folding pattern providing the collapsed heat spreader. In the unfurled configuration embodiments of the heat spreader may then be configured substantially flat after unfolding the heat spreader along the folding lines. It is noted that alternative embodiments of the heat spreader may not comprise folding lines. Furthermore, also not every folding pattern may be configured to support the provision of the thermal contact between the heat spreader and the heat dissipating surface.

[0012] Hence, in further embodiments, the heat spreader comprises folding lines (including perforated line and / or creases or scores) for facilitating (i) folding the heat spreader in a furled configuration, and (ii) unfolding the heat spreader in an unfurled configuration allowing to move the heat spreader in the furled configuration through the through-hole. The heat spreader (in the lighting arrangement) is especially configured unfolded in the unfurled configuration (in the cavity).

[0013] In embodiments, the light generating device may (at least partly) be configured in a ceiling. The light generating device may e.g., comprise a downlight, or a (recessed) ceiling spot. The construction arrangement may therefore in embodiments comprise (or be) a ceiling arrangement. In embodiments, the light generating device may (at least partly) be configured in the ceiling arrangement. In embodiments (comprising the ceiling arrangement), the term “board” may (thus) refer to a ceiling board. Moreover, the first board side may in embodiments comprise a first ceiling board side, and especially the second board side may comprise a second ceiling board side. Further, in embodiments, the cavity may be configured at the first ceiling board side (of the ceiling board). In further embodiments, the ceiling board may (thus) comprise the through-hole, especially from the first ceiling board side to the second ceiling board side). Hence, in embodiments, the invention provides a lighting arrangement comprising a light generating device, a heat spreader, and a construction arrangement (especially a ceiling arrangement); wherein: (a) the light generating device comprises (i) a first device portion comprising a first side of the light generating device and (ii) a second device portion comprising a second side of the light generating device; wherein the first device portion comprises a heat dissipating surface; wherein the light generating device is configured to emit device light from the second side (of the light generating device ) (especially during operation of the light generating device); (b) the heat spreader comprises a thermally conductive material having a thermal conductivity of at least 150 W / m / K (inplane); (c) the construction arrangement (especially in embodiments the ceiling arrangement) comprises (i) a (ceiling) board, and (ii) a cavity, configured at a first (ceiling) board side (of the (ceiling) board); wherein the (ceiling) board comprises a through-hole (from the first (ceiling) board side to a second (ceiling) board side; (d) the light generating device is (at least partly) configured in the construction arrangement (especially in the ceiling arrangement), wherein the first device portion is at least partly configured in the cavity and wherein the second device portion is at least partly configured in the through-hole; wherein the light generating device is configured for illuminating a space arranged at the second (ceiling) board side with the device light; and (e) the heat spreader is configured in the cavity; and wherein the heat dissipating surface and the heat spreader are configured in thermal contact with each other. In further embodiments, the cavity comprises an insulation material. The insulation material may in embodiments contact the first device portion.

[0014] With such lighting arrangement an improved heat dissipation in the cavity may be provided. Such lighting arrangement may be configured using small, recessed spots that may provide a high flux output while not becoming overheated. The light generating device may in embodiments have a size such as width or diameter of equal to or less than 2.5 inch, such as a size of equal to or less than 2 inch, like for instance a size of about 1 inch, or even smaller, while allowing to generate a luminous flux of over 500 lumen, such as selected from the range of 500 to 1000 lumen, or even higher. The light generating device may in embodiments be configured in an isolated ceiling or wall. Embodiments of the lighting arrangement may comprise a so-called “IC” rating, i.e., insulating material may be allowed to come in direct contact with the light generating device without the risk of combustion. Embodiments of high output small spot may be applied in high end residential and high-end commercial buildings. Compared to prior art solutions, the lighting arrangement may be thermally improved in embodiments as a result of the additional heat spreader. Hence, amongst others the invention provides in embodiments a folded to open heat sink for ultra small, recessed ceiling spots.

[0015] The lighting arrangement may in embodiments comprise a light generating device that is at least partly configured in a ceiling arrangement, especially wherein the first device portion of the light generating device is at least partly configured in the (ceiling) cavity. Such cavity may, e.g., comprise a plenum above the ceiling board. Additionally, or alternatively, the light generating device (or a further light generating device) may (at least partly) be configured in a wall, for instance as a recessed spot. In embodiments, the construction arrangement may (also) comprise a wall arrangement. The terms “board”, “first board side”, and second board side” may therefore in embodiments (also) refer to (or comprise) “a wall board”, “a first wall board side”, and “a second wall board side”, respectively (when referring to a construction arrangement comprising a wall arrangement). In embodiments, the cavity may be configured at the first wall board side (of the wall board). In further embodiments, the wall board may (thus) comprise the through-hole (especially from the first wall board side to the second wall board side). The wall cavity may for instance comprise a cavity in a hollow wall, or a cavity behind a falls wall. The (wall) board may in embodiments define a falls wall. In further embodiments, the term “ceiling” (or alternatively “wall”) may refer to a top side or shelf in a closet or cupboard, especially configured between a cavity and a space to be illuminated with the device light.

[0016] The term “construction arrangement” may thus especially refer to a ceiling arrangement. Additionally, or alternatively, the term may refer to a wall arrangement.

[0017] It is noted that herein, the lighting arrangement may be explained based on a construction arrangement as such. At other locations, the lighting arrangement may also be explained based on (a construction arrangement comprising) a ceiling arrangement. Moreover, if herein the term “ceiling arrangement” is used, it will be understood that in further embodiments, this term may be replaced by “wall arrangement”. Likewise, if one or more of the terms “ceiling board”, “first ceiling board side”, and “second ceiling board side”, are used, it will be understood that in alternative embodiments, these terms may be replaced by “wall board”, "first wall board side”, and “second wall board side”, respectively. In embodiments (comprising a ceiling arrangement and a wall arrangement, see further below) these terms may be added with the terms “wall board”, "first wall board side”, and “second wall board side”, respectively. For instance, the cavity may in embodiments be configured at the first ceiling board side and at the first wall board side, and especially a first light generating device may at least partly be configured through ceiling board and a further light generating device may at least partly be configured through the wall board.

[0018] In embodiments, the cavity may comprise an insulation material as described above. The insulation material may in specific embodiments contact the first device portion. In further embodiments, the insulation material may be configured at a non-zero distance (e.g. at a distance of at least 5 mm, such as at least 10 mm) from the first device portion.

[0019] In embodiments, the insulation material may comprise a “loose-fill and blown- in type of insulation material. Loose-fill and blown -in insulation may comprise (small) particles of fiber, foam, or other materials, which may especially conform to any space or cavity. Such insulation material may for instance comprise one or more of a cellulose fiber, fiberglass, mineral wool, such as rock wool, slag wool and glass wool. The insulation material may in specific embodiments comprise cellulose (insulation) fiber. The cellulose fiber may comprise cellulose fibers made from recycled cellulose-comprising materials. In further embodiments, the insulation material may comprise a blanket type of insulation material, e.g. comprising one or more of fiberglass, mineral wool, plastic fibers, and natural fibers.

[0020] The light generating device may in embodiments comprise a spot (light). The light generating device may especially comprise a down light. The light generating device may comprise a solid-state lighting (SSL) type of light source. The light generating device may for instance comprise one or more light-emitting diodes (LEDs). The term “light generating device” may in embodiments refer to a plurality of (different or the same) light generating devices (especially each being configured in thermal contact with a (respective) heat spreader). Furthermore, the term “construction arrangement” may refer to more than one construction arrangements. In embodiments, e.g., the construction arrangement may comprise a ceiling arrangement and a wall arrangement (both comprising one or more light generating devices). In other embodiments, the construction arrangement may comprise a plurality of ceiling arrangements. A first ceiling arrangement may e.g., comprise a horizontally configured ceiling arrangement (comprising a horizontally configured ceiling board) and a second ceiling arrangement may comprise a sloped ceiling arrangement (comprising a sloped or tilted ceiling board). Many other configurations are feasible falling under the claimed invention, as will be understood by the skilled person.

[0021] The light generating device may especially comprise the first device portion for configuring at least partly in the cavity. The light generating device further especially comprises the second device portion comprising the second side of the light generating device. In embodiments, the first device portion directly contacts the second device portion. The light generating device may in embodiments be defined by the first device portion and the second device portion. In further embodiments the first device portion may indirectly contact the second device portion via a further device portion configured between the first device portion and the second device portion. The second device portion is especially at least partly configured in the through-hole. During use of the light generating device, device light may be emitted from the second side. When the light generating device is configured in the construction arrangement, device light generated at the second side of the light generating device may travel from the light generating device into the space (at the side of the board opposite to the cavity). Herein, the ability to travel from the second side of the light generating device into the space is also indicated as “the space is configured in a light receiving relationship with the second side of the light generating device.

[0022] The term “space” may for instance relate to a (part ol) hospitality area, such as a restaurant, a hotel, a clinic, or a hospital, etc.. The term “space” may also relate to (a part of) an office, a department store, a warehouse, a cinema, a church, a theatre, a library, etc. However, the term “space” may also relate to (a part of) a working space, such as in a cabin or closet. The term “space” may also relate to (a part of) a working space, such as an office, a (production) plant, a power plant, etc. Especially, the term “space” may herein refer to an indoor space. In yet other embodiments, the term “space” may also relate to a toilet room or bathroom. In yet other embodiments, the term “space” may also relate to an elevator. In embodiments, the term “space” may also refer to a conference room, a school room, an indoor hallway, an indoor corridor, an indoor space in an elderly home, an indoor space in a nursing home, etc. In embodiments, the term “space” may refer to an indoor sport space, like a gym, a gymnastics hall, in indoor ball sport space, a ballet room, a swimming pool, a changing room, etc. In embodiments, the term “space” may refer to an (indoor) bar, an (indoor) disco, etc.

[0023] The light generating device may be fixed (immobilized) at the construction arrangement. Different solutions may be applied to secure the light generating device to the construction arrangement. In embodiments, for instance, the light generating device may be secured to the board of the board arrangement using a connection frame configured at the board. In further embodiments, the light generating device may comprise a retention spring element configured to secure the light generating device to the construction arrangement. The retention spring element may in embodiments provide a (spring) force in a direction opposite to gravitational forces. The retention spring element may in further embodiments provide a friction force between the construction arrangement and the light generating device preventing the light generating device to move based on gravity. The retention spring element may in in embodiments comprise one or more torsion springs. In specific embodiments, the retention spring is configured for resiliently forcing the light generating device in a direction away from the space. In yet further embodiments, the light generating device may be secured using a mechanical clamping system. The light generating device may especially be fixed at the construction arrangement using a mechanical clamping system and / or a spring system.

[0024] The heat dissipating surface is in embodiments configured for facilitating a heat transfer away from the light generating device (to the ambient). The heat dissipating surface is especially thermally conductive. The heat dissipating surface may in embodiments comprise one or more fins for extending the heat dissipating surface to enhance the heat transfer. In further advantageous embodiments, also the retention spring may be applied to dissipate heat. For instance, the retention spring may comprise an extended heat dissipating surface and / or an extended heat dissipating surface may be associated with the retention spring.

[0025] The extended heat dissipating surface may further be thermally connected to the heat dissipating surface. The thermal connection may in embodiments be a direct connection. Additionally, or alternatively, the extended heat dissipating surface may be (indirectly) thermally connected to the heat dissipating surface via the retention spring element). In embodiments, the extended heat dissipating surface may further be configured in thermal contact with the heat spreader. The thermal contact between the extended heat dissipating surface and the heat spreader may in embodiments be directly configured, Additionally, or alternatively, the thermal contact may be configured indirectly via the retention spring element. The retention spring element may for instance in embodiments be connected to the first device portion and provide the force in a direction away of the space when being configured at the first board side, especially having the heat spreader sandwiched between the first board side and the retention spring element. The extended heat dissipating surface may (also) comprise a thermally conductive material (such as also indicate below).

[0026] Hence, in embodiments, the lighting arrangement further comprises an extended heat dissipating surface, associated to the retention spring element, and thermally connected to the heat dissipating surface (especially directly, or indirectly via the retention spring element); and wherein the retention spring element is configured in thermal contact with the heat spreader (directly, or indirectly via the retention spring element). In embodiments, the second device portion of the light generating device may be completely configured in the through hole. In other embodiments, the light generating device may comprise a trim (flange) at the second side and the trim (flange) may be configured at the second board side (wherein the remainder of the second portion is configured in, or through, the through-hole. In yet further embodiments a part of the second device portion may extend from the second board side. In further embodiments, the light generating device may be configured to prevent or block a complete passage of the light generating device through the through-hole. The second device portion may for instance in embodiment comprise a (tapered) shape that provides a tight fit with the trough-hole. In further embodiments, the trim (flange) configured at the second side may block the passage through the through-hole. The trim (flange) may function as a blocking element for obstructing a movement of the light generating device in the direction away from the space.

[0027] Hence, the second device portion may in embodiments comprise a blocking element for obstructing the movement of the light generating device in the direction away from the space. The blocking element may in embodiments comprise a ring protruding from the second device portion. The ring may especially have a size (such as a width or a diameter) that is larger than an average size (width or diameter) of the light generating device along a length (from the first side to the second side) of the light generating device. The ring may be configured at the second side, like the trim (flange) described above. The ring may in further embodiments be configured remote (in a direction towards the first side) from the second side. The ring may comprise a continuous ring in embodiments. In further embodiments, the ring may be defined by a plurality of protruding elements. In yet further embodiments, the blocking element may comprise at least two protruding elements, such as pins, protruding from the second device portion. The protruding elements are especially configured at a same distance from the second side.

[0028] In specific embodiments the first device portion comprises a retention spring element configured for resiliently forcing the light generating device in a direction away from the space; wherein the second device portion comprises a blocking element for obstructing a movement of the light generating device in the direction away from the space, especially when the blocking element is configured in physical contact with the second ceiling board side of the ceiling board.

[0029] The heat spreader may in embodiments be a relevant aspect of the invention. The heat spreader may transfer heat generated by the light generating device away from the light generating device. The light generating device may be configured to generate at least two Watts of heat when generating light, such as at least three Watts of heat during operation. In embodiments, the light generating device may generate up to eight Watts of heat during operation (i.e., during generating light). The heat spreader is configured for dissipating at least part of the heat generated by the light generating device. In embodiments, for instance, the heat spreader may be configured for providing a heat dissipation of at least 2 W, such as at least 3 W, and in embodiments a heat dissipation of especially at least 5W.

[0030] The heat spreader may in embodiments have a sheet-like shape. The heat spreader may in embodiments comprise a foil, a sheet, or a film. The term “sheet-like shape” not necessarily refers to a complete flat sheet, but may for instance also refer to a shape comprising folds, wrinkles, curves, or bends (see further below). The term “sheet-like” may especially indicate that the heat spreader may comprise a plane of the heat spreader (which may thus comprise bends or wrinkles etc.). The term may further indicate that if a surface of the heat spreader is flattened (e.g. substantially all bend, folds, wrinkles, etc. are removed) that the dimensions of the surface in the plane (e.g. a largest width and a largest length or e.g. a diameter) are much larger than the size perpendicular to the plane or perpendicular to the surface (or a “thickness” of the heat spreader). In embodiments, the thickness of the heat spreader may for instance be less than 3 mm, even more especially less than 2 mm, such as equal to or less than 1 mm. In specific embodiments, the thickness of the heat spreader may be no more than 100 pm. The thickness of the heat spreader may in embodiments be selected from the range of 10-1000 pm, such as from the range of 10-500 pm, like from the range of 10-200 pm or from the range of 10-100 pm, and in embodiments from the range of 50-100 pm or from the range of 100-200 pm. In embodiments, the thickness of the heat spreader may in embodiments be selected from the range of at least 20 pm, like at least about 30 pm. The surface area of the flattened heat spreader (especially the area of one side of the heat spreader) may in embodiments define the heat exchanging surface of the heat spreader. In embodiments, the heat spreader may have a heat exchanging surface of at least 40 cm2, especially of at least 50 cm2, such as of at least 100 cm2. In further embodiments, the heat exchanging surface of the heat spreader is no more than 1000 cm2, like no more than 700 cm2, especially no more than 500 cm2, such as no more than 250 cm2.

[0031] The heat spreader may in embodiments comprise a thermally conductive material that may especially conduct heat in a direction within, or in, the plane of the heat spreader. The thermal conductivity described herein in relation to (the thermally conductive material ol) the heat spreader may especially refer to the in-plane thermal conductivity. The thermal conductivity is especially defined at room temperature. The thermal conductivity of the thermal conductive material is especially at least 150 W m’1-K’1, such as at least 200 W m^ K'1, especially at least 400 W m’1K’1. In embodiments, the thermal conductive material has a thermal conductivity of at least 750 W m’1K’1, like at least 1000 W nf'-K’1, such as selected from the range of 750 W m'^K'1to 5000 W m^ K'1. The thermally conductive material may in further specific embodiments have a thermal conductivity selected from the range of 150 W m’1K’1to 2500 W m’1K1, especially selected from the range of 750 W m'^K'1to 2500 W m’^K1, like selected from the range of 750 W m'^K'1to 1500 W m'^K1. In further embodiments, the thermally conductive material may have a thermal conductivity selected from the range of 2500 W m'^K'1to 5000 W m’1K1.

[0032] The (heat conductive material of the) heat spreader may in embodiments comprise for instance aluminum or copper. In further embodiments, (the heat conductive material of) the heat spreader may comprise graphite. Graphite may in embodiments comprise pyrolytic graphite. The heat spreader may comprise a (pyrolytic) graphite sheet. The heat spreader may in further embodiments comprise highly oriented pyrolytic graphite, for instance pyrolytic highly oriented graphite sheet (PGS) material. Additionally or alternatively, the heat conductive material of the heat spreader may comprise graphene (including composite materials comprising graphene). In further embodiments, the heat conductive material of the heat spreader may comprise a boron nitride silicone composite, such as comprising hexagonal boron nitride. In specific embodiments, the heat spreader comprises one or more of aluminum, copper, graphite, and graphene. The heat spreader may comprise a composite material comprising one or more of the materials described in relation to the (heat conductive) material of the heat spreader.

[0033] In further embodiments, the heat spreader comprises a sheet of one or more of aluminum, copper, graphite, and graphene. The heat spreader may especially comprise a sheet selected from the group consisting of an aluminum sheet, a copper sheet, a graphitecomprising sheet (i.e. a sheet comprising - or made of - graphite) and a graphene-comprising sheet (a sheet comprising - or made of - graphene). The sheet may in embodiments have a thickness selected from the range of 10 to 750 pm, such as selected from the range of 50 pm to 250 pm. By selecting the thickness, in embodiments, the thermal conductivity may be selected. The sheet may for instance in embodiments comprise a pyrolytic graphite sheet having a thickness of 100 pm, having an in-plane thermal conductivity of about 700 W in '•K'1. In other embodiments the sheet may comprise a pyrolytic graphite sheet having a thickness of 70 pm, having an in-plane thermal conductivity of about 1000 W m'1K’1. Using such sheet for the heat spreader, wherein the heat spreader comprises a heat exchanging surface of about 50 cm2may provide a heat dissipation of at least 3 W in embodiments.

[0034] The heat spreader may especially be connected to the first (ceiling) board side. The heat spreader may for instance be (physically) connected with a physical connector, such as a screw, a nail, or a staple. Additionally, or alternatively, the physical connector may comprise a tape, such as a double sided tape. The physical connector may in further embodiments comprise a hook and loop fastener, e.g., Velcro tape. In specific embodiments, the physical connector comprises a double-sided adhesive element. The physical connector may especially be selected for having a high thermal conductivity (through plane and / or on plane) facilitating a heat transfer from the heat spreader to the first board side. In yet further embodiments, the heat spreader may be (physically) connected to the first board side using a glue, especially having a high thermal conductivity.

[0035] In embodiments, the heat spreader is connected to the first (ceiling) board side via one or more of a physical connector, an adhesive material, and a double sided adhesive element.

[0036] The physical connector and / or the glue may have a dual function in embodiments. They may function as a (physical) connecting element. The physical connector and the glue may further function as a thermally conductive element. The heat spreader may physically contact the first board side. In further embodiments, the heat spreader may also thermally contact the first board side. The glue may comprise a thermally conductive glue, and especially may function as a thermally conductive element.

[0037] The term “thermally conductive element” used herein may relate to any element that may conduct heat. The thermally conductive element especially comprises or is made of thermally conductive material. The thermally conductive material may e.g., have a thermal conductivity of at least 10 W m^-K'1, such as at least 50 W m’1-K’1, especially at least 100 W m’1K’1. The thermally conductive material may comprise a metal, such as copper, aluminum, steel, iron, silver, lead, or an alloy of one or more (of these) metals. The thermally conductive element may in embodiments comprise a layer or a coating arranged configured at, or being part of, the element comprising the respective thermally conductive element. In further embodiments, the element comprising the thermally conductive element may be configured thermally conductive, and especially may at least partly be made of the thermally conductive material.

[0038] The term “thermal contact” indicates that an element can exchange thermal energy through the process of heat transfer with another element. The (first) element may e.g., comprise the heat dissipating surface of the light generating device and the other element may comprise the heat spreader. Based on the thermal contact between the two elements heat may be transferred from the light generating device to the heat spreader. Furthermore, the heat spreader may in embodiments transfer heat to the connecting element via a thermal contact between the heat spreader and the connecting element. Moreover, the connecting element may in embodiments further transfer heat to the first board side via a thermal contact between the connecting element and the first board side. In embodiments, thermal contact can be achieved by physical contact. In embodiments, thermal contact may be achieved via a thermally conductive material, such as a thermally conductive glue (or thermally conductive adhesive). Thermal contact may also be achieved between two elements when the two elements are arranged relative to each other at a distance of equal to or less than about 10 pm, though larger distances, such as up to 100 pm may be possible. The shorter the distance, the better the thermal contact. Especially, the distance is 10 pm or less, such as 5 pm or less. The distance may be the distance between two respective surfaces of the respective elements. The distance may be an average distance. For instance, the two elements may be in physical contact at one or more, such as a plurality of positions, but at one or more, especially a plurality of other positions, the elements are not in physical contact. For instance, this may be the case when one or both elements have a rough surface. Hence, in embodiments an average distance between the two elements (being in thermal contact with each other) may be 10 pm or less (though larger average distances may be possible, such as up to 100 pm).

[0039] The heat transfer may further be improved by increasing the area of contact between the two elements. For increasing the area of contact between the heat spreader and the heat generating device, the heat spreader may in embodiments comprise an edge or a rim configured for contacting the heat dissipating surface. Such edge or rim may especially be configured inclined to or perpendicular to the (largest portion / area ol) the plane of the heat spreader. The edge or rim may especially be configured substantially perpendicular to a plane of the first board side. The edge may for instance comprise a raised edge (raised relative to the remainder of the heat spreader). The edge may comprise a flexible edge (to increase the thermal contact). The edge may further comprise a notched edge to improve contacting the heat dissipating surface.

[0040] To further increase the contact between the heat spreader and the light generating device, the lighting arrangement may comprise means to force the heat spreader to the heat dissipating surface of the light generating device. In embodiments, the lighting arrangement may further comprise a clamping element configured to clamp the heat spreader against the heat dissipating surface. The clamping element may for instance comprise a spring element, e.g., a retaining spring. The clamping element may comprise a flexible clamp with the size (when clamping) larger than a size of the first device portion it has to surround. The clamping element may in further embodiments comprise a magnetic element, for instance a (especially partly opened) magnetic ring. The ring may be used to fix heat spreader to the heat dissipating surface. In further embodiments, the flexible clamp may comprise one or more (flexible) strips, such as metal strips.

[0041] In embodiments, the edge or rim may be configured at an edge or side of the heat spreader. The heat spreader may extend from the light generating device in a specific direction. In further embodiments, the heat spreader may be configured extending around the light generating device. The heat edge or rim of the heat spreader may in embodiments be configured at and around an opening in the heat spreader. The heat spreader opening may especially be configured as a central opening in the heat spreader. In embodiments the heat spreader opening may be configured for moving the first device portion of the light generating device through the opening (during installing the light generating device). The opening, especially the edge may further be configured for contacting the light generating device, especially the heat dissipating surface. The opening may especially provide a tight fit around the heat dissipating surface.

[0042] Hence, in embodiments, the heat spreader comprises a heat spreader opening configured around the first device portion; wherein the heat spreader at the heat spreader opening comprises an edge selected from one or more of (i) a raised edge, (ii) a flexible edge, and a notched edge, configured in thermal contact with the heat dissipating surface.

[0043] Herein, the term “thermal contact” may especially refer to an arrangement of elements that may provide athermal conductivity of at least about 10 W m'1K’1, such as at least 20 W-m’1-K’1, such as at least 50 W m K4. In embodiments, the term “thermal contact” may especially refer to an arrangement of elements that may provide a thermal conductivity of at least about 150 W m’1K’1, such as at least 170 W m'^K’1, especially at least 200 W m’1K’1. In embodiments, the term “thermal contact” may especially refer to an arrangement of elements that may provide a thermal conductivity of at least about 250 W m’ '•K , such as at least 300 W m^-K'1, especially at least 400 W m^-K'1. For instance, a heat spreader being configured in (physical) contact with the light generating device and in (physical) contact with a board or heat sink, may provide a thermal conductivity between the light generating device and the board of at least about 10 W m K4. The connected heat spreader may further especially be configured such that a total surface area of the board that is covered by the heat spreader is maximized (see also further below). When connected to the first board side optional bends, wrinkles, or folds in the heat spreader may be minimized for maximizing a heat dissipation of the heat spreader. To allow unfolding or unfurling of specific embodiments of the heat spreader, these heat spreaders preferably have a minimum mechanical strength. In specific embodiments, the heat spreader may for instance comprise a (sheet like) material with a mechanical strength of at least 10 MPa, especially at least 20 MPa, such as at least 30 MPa.

[0044] The lighting arrangement may have the feature that the edge of the heat spreader opening in the furled configuration (A) and in the unfurled configuration (B) essentially has a same size, i.e. the edge of the heat spreader opening essentially remains constant in size and shape when the heat spreader switches between the furled configuration (A) and the unfurled configuration (B). This is enabled by the feature that in the furled configuration the heat spreader comprising sub-surfaces comprising heat exchanging surface sub-areas that (preferably) abut each other in the radial direction, Dr, and (partially) extend along the tangential direction, Dt, next to each other and can unfold over the folding lines. In the unfurled configuration, B, the sub-surfaces of the heat-exchanging surface area are practically flat (or only slightly curved) and hardly or essentially do not overlap (in a projected view) in radial direction, but essentially are each fully exposed to maximise the heat dissipation capacity.

[0045] In a further aspect, the invention also provides a method for installing a light generating device (especially the light generating device described herein) with a heat spreader (especially the heat spreader described herein) in a construction arrangement as described herein. The method may in embodiments comprise providing the heat spreader in the cavity. In further embodiments, the method further comprises installing (at least part ol) the light generating device in the construction arrangement. In embodiments, the first device portion is at least partly configured in the cavity. In further embodiments, the second device portion is at least partly configured in the through-hole, especially for illuminating a space arranged at the second ceiling board side with the device light. In further embodiments, the method comprises providing the heat dissipating surface and the heat spreader in thermal contact with each other.

[0046] Hence, the invention provides in embodiments a method for installing the light generating device with the heat spreader in a construction arrangement (like in embodiments, in a ceiling arrangement), especially the construction arrangement (such as the ceiling arrangement and / or the wall arrangement) described herein, comprising (i) providing the heat spreader in the cavity; and (ii) installing the light generating device (at least partly) in the construction arrangement (like in the ceiling arrangement), wherein the first device portion is at least partly configured in the cavity and the second device portion is at least partly configured in the through-hole for illuminating a space arranged at the second (ceiling) board side with the device light; and (iii) providing the heat dissipating surface and the heat spreader in thermal contact with each other.

[0047] In further embodiments, the method comprises providing the though-hole in the board, especially from the second board side to the first board side (from the space to the cavity). The through-hole may especially comprise an opening that matches (in size and shape) the light generating device. An opening cross-sectional area (especially configured perpendicular to a shortest line connecting the first board side to the second board side may in embodiments for instance be a few percent (e.g. up to 10%) larger than a cross sectional area of the second device portion excluding the trim (flange) and a few percent smaller than the cross sectional area defined by the trim (flange).

[0048] In embodiments, the heat spreader comprises (i) a furled configuration (A) for providing the heat spreader through the through-hole from the second (ceiling) board side to the first (ceiling) board side and (ii) an unfurled configuration (B) for increasing a total heat dissipating capacity of the heat spreader (especially when being configured in thermal contact with the heat dissipating surface); and the method (further) comprises (ia) providing the heat spreader in the furled configuration (A) from the second (ceiling) board side to the first (ceiling) board side through the through-hole; (ib) changing the heat spreader from the furled configuration (A) to the unfurled configuration (B), and (optionally) (ic) connecting the heat spreader to the first (ceiling) board side.

[0049] In embodiments, changing the heat spreader from the furled configuration (A) to the unfurled configuration (B) may be done via the through-hole. Herein, this changing of the configuration from A to B may also indicated as “spreading out” the heat spreader. In embodiments, the heat spreader may be spread out using a spreader tool or “unfurling tool”. This may especially allow to (completely) unfurl heat spreaders with a large heat exchanging surface via a small through-hole.

[0050] Connecting the heat spreader to the first board side may in embodiments comprise physically (and thermally) contacting the first board side with the heat spreader using one or more of the physical connectors and glue described herein. It is noted that in embodiments, the unfurled heat spreader may (also) be removed from the board again (e.g. by peeling it off) when removing or changing the light generating device.

[0051] The invention provides in a further aspect a kit of parts comprising (i) a light generating device and (ii) a heat spreader. The light generating device of the kit of parts may especially comprise the light generating device as explained in relation to the lighting arrangement. Further, also the heat spreader of the kit of parts may comprise the heat spreader described in relation to the lighting arrangement. Hence, the light generating device (of the kit of parts) may be configured for providing the configuration of the light generating device in the lighting arrangement. Also the heat spreader (of the kit of parts) may be configured for providing the configuration of the heat spreader in the lighting arrangement. The light generating device is thus in embodiments configured for installing in the construction arrangement as defined herein. In specific embodiments, the light generating device is in configured for installing in the ceiling arrangement. Additionally, or alternatively, the light generating device may be configured for installing in the wall arrangement. The heat spreader may in embodiments comprise a thermally conductive material having a thermal conductivity of at least 150 W / m / K (in-plane).

[0052] In specific embodiments the heat spreader comprises (the) folding lines for facilitating (i) folding the heat spreader in a furled configuration (A), and (ii) unfolding the heat spreader in an unfurled configuration (B) allowing to move the heat spreader in the furled configuration (A) through the through-hole of the construction arrangement (like the ceiling arrangement). The heat spreader (of the kit) may especially be configured (folded or collapsed) in the furled configuration. This way, the heat spreader may easily be passed through the through-hole. In the unfurled configuration (being spread out) a size or surface area of the heat spreader may be significantly larger than the opening of the through-hole, see also above. In embodiments, for instance the through-hole may comprise an opening cross- sectional area (especially configured perpendicular to a shortest line connecting the first board side to the second board side). The opening cross-sectional area may in embodiments for instance be in the range of 1 to 35 cm2, especially in the range if 5 to 20 cm2. Further, the heat spreader in the unfurled configuration (B) may have a heat spreader heat exchanging surface area, especially being defined as a total surface at one side of the heat spreader. In embodiments a ratio of the heat spreader heat exchanging surface area to the opening cross- sectional area may at least be 10, such as at least 50. The ratio of the heat spreader heat exchanging surface area to the opening cross-sectional area may in embodiments be 100 at maximum, such as 75 at maximum. In further embodiments, said ratio may be smaller than ten, such as in the range of five to ten. In embodiments, the heat spreader heat exchanging surface area in the unfurled configuration may for instance be in the range of 50 to 1000 cm2.

[0053] The heat spreader may in further embodiments comprise a pre-shaped edge or a measure to provide the edge as described above. The edge may in embodiments e.g., be prearranged by the folding lines and / or the folding pattern described above. Additionally, or alternatively, the edge may be defined by a perimeter of the (central) opening in some of the embodiments. In embodiments, the perimeter may e.g., define notches.

[0054] In specific embodiments, the heat spreader in the unfurled configuration (B) may have the sheet-like shape, wherein the heat spreader comprises the heat spreader opening configured for moving the first device portion of the light generating device through the heat spreader opening during installation of the light generating device in the construction arrangement and especially (also) for providing the thermal contact with the heat dissipating surface. In further embodiments, the heat spreader at the heat spreader opening comprises an edge or preparations for an edge, wherein the edge is selected from one or more of (i) a raised edge, (ii) a flexible edge, and a notched edge, wherein the edge is for thermally contacting the heat dissipating surface.

[0055] As discussed above, the heat spreader may especially comprise folding lines to facilitate folding and unfolding of the heat spreader. The folding line may define a folding pattern to ease folding and especially unfolding the heat spreader. The folding pattern may further define a rim or edge of the heat spreader for thermally contacting the heat dissipating surface. The heat spreader may in embodiments be provided / configured using origami techniques. Origami techniques may be used to fold a sheet according to the folding lines provided on the sheet. It appeared that folding lines extending from edges of a heat spreader opening having a polygonal shape may advantageously be used to unfold the heat spreader and also to provide an edge that may provide a good thermal contact between the heat spreader and the heat dissipating surface. The folding lines may be configured extending form (any one ol) the comers (or vertices) of the polygon, wherein a first half of the folding lines are configured aligned with the sides of the polygon and the other half of the folding lines are configured such that each of said folding lines defines a predefined angle between the respective folding line and another folding line extending from the same comer of the polygon. The predefined angle may especially be selected based on a total number of sides of the polygon. The predefined angle may especially be equal to 180° divided by the total number of the sides of the polygon. The heat spreader may comprise a positive folding line and a negative folding line extending from each comer of the polygon. The terms “positive” and “negative” in relation to the folding lines especially indicates that these folding lines are folding lines at which the heat spreader in the furled configuration is folded in opposite directions. The positive and negative folding lines may also be known as “mountain folding lines” and “valley folding lines”. The (heat) spreader opening (the polygon) may especially be configured in the center of heat spreader.

[0056] In specific embodiments the heat spreader comprises n*2 folding lines, with n being an integer, wherein extremes of the n*2 folding lines at the heat spreader opening define a polygon shape at the heat spreader opening comprising n sides, wherein the n*2 folding lines comprise n positive folding lines and n negative folding lines, wherein any positive folding line is configured at an angle a of 180 / n degrees to a negative folding line, and wherein (i) any one of the positive folding lines is aligned with a respective sides of the polygonal shape or (ii) any one of the negative lines is aligned with a respective side of the polygonal shape. For n being equal to 6, this may result in a heat spreader comprising a (central) spreader opening will provide a hexagon.

[0057] In further embodiments, the heat spreader may have a starshade configuration (a configuration like used for the starshade) known from the “Exoplanet Program” of NASA. In further embodiments, the heat spreader may be folded according to a Miura folding pattern. The Miura fold refers to a folding technique that allows a flat surface, like a sheet of paper, to be compressed into a smaller area. It was named after its creator, Koryo Miura, a Japanese astrophysicist. The folding pattern of the Miura fold form a surface of parallelograms. In one direction, the folding lines he along straight lines, with each parallelogram forming a mirror reflection of its neighbor across each folding line. In the other direction, the folding lines zigzag, and each parallelogram is a translation of its neighbor across the folding line. Each of the zigzag paths of folding lines consists solely of mountain folding lines or of valley folding lines, with mountains alternating with valleys from one zigzag path to the next. Each of the straight paths of folding lines alternates between mountain and valley folds. The Miura fold is a form of rigid origami, meaning that the fold can be carried out by a continuous motion in which, at each step, each parallelogram is completely flat. This property allows it to be used to fold surfaces made of rigid materials.

[0058] The heat spreader may in embodiments comprise an origami folding pattern. Based on the origami folding pattern, unfurling of the heat spreader may be facilitated.

[0059] Herein, the term “polygon (shape)” is used. A polygon is essentially a two- dimensional figure that is described by a finite number of straight line segments named edges or sides. Herein the term “polygon” may especially refer to a convex polygon. Further, the polygon especially comprises a regular polygon. The polygon may e.g., be a square, a pentagon, a hexagon, a heptagon, an octagon, a nonagon, a decagon, etc., etc. The polygon may in embodiments comprise an / 7-gon. especially wherein n is at least 6, such as at least 8. In embodiments n is equal to or smaller than 50, especially equal to or smaller than 20, such as equal to or smaller than 12, such as 6< / 7<20. especially 6<«<16 such as 6<«<10. An / 7-gon comprises n edges or sides. Hence, the polygon(s) described herein may also especially comprise a number of edges equal to n.

[0060] In further embodiments, the kit of parts, further comprises the unfurling tool, especially for changing the heat spreader provided in the cavity from the furled configuration (A) to the unfurled configuration (B) via the through-hole.

[0061] In yet further embodiments, the kit of parts may comprise one or more connection elements described herein. The kit of parts may further also comprise a clamping element for clamping the heat spreader against the heat dissipating surface.

[0062] In yet a further aspect, the invention also provides a light generating system. The light generating system may in embodiments comprise the light generating device described herein. The light generating system may further especially comprise the heat spreader. In further embodiments, the heat spreader and the heat dissipating surface are configured in thermal contact with each other. In further embodiments, the light generating system may comprise a control system that may control the light generating device, and / or other elements of the light generating system. In further embodiments, the light generating system may comprise a user interface. The user interface may for instance be functionally coupled to the control system. The user interface may in embodiments be used to control one or more light generating devices.

[0063] In further embodiments, the light generating system may comprise the lighting arrangement described herein. Instead of the terms “lighting device” or “lighting system”, and similar terms, also the terms “light generating device” or “light generating system”, (and similar terms), may be applied. A lighting device or a lighting system may be configured to generate device light (or “lighting device light”) or system light (“or lighting system light”). As indicated above, the terms light and radiation may interchangeably be used.

[0064] The lighting device may comprise a light source. The device light may in embodiments comprise one or more of light source light and converted light source light (such as luminescent material light). BRIEF DESCRIPTION OF THE DRAWINGS

[0065] 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:

[0066] Fig.l schematically depicts an embodiment of the lighting arrangement; and Figs 2 to 5 depict some further aspects of the invention.

[0067] The schematic drawings are not necessarily to scale.

[0068] DETAILED DESCRIPTION OF THE EMBODIMENTS

[0069] Fig. 1 schematically depicts an embodiment of the lighting arrangement 1. The lighting arrangement 1 comprises a light generating device 100 and a construction arrangement 300. In the depicted embodiment, the construction arrangement 300 comprises (or be) a ceiling arrangement 301. The depicted light generating device 100 comprises a first device portion 120 and a second device portion 140. The first device portion 120 comprises the first side 121 and the second device portion 140 comprises the second side 141 of the light generating device 100. The second side 141 and to the first side 121 are configured at opposite sides of the light generating device 100. The first device portion 120 comprises a heat dissipating surface 130. In the depicted embodiment, the heat dissipating surface 130 is flat / smooth. In other embodiments (not depicted), the heat dissipating surface 130 may comprise a heat sink comprising fins.

[0070] The depicted ceiling arrangement 300,301 comprises a (ceiling) board 310 and a cavity 350. The cavity 350 is arranged at the first ceiling board side 311. The depicted cavity 350 may also be known as a plenum and may comprise insulation material in embodiments (not depicted in the figure). The light generating device 100 is configured in the through-hole 360 that is configured in the board 310 from the first board side 311 to the second board side 312. As such, the light generating device 100 is configured in the construction arrangement 300, with the first device portion 120 in the cavity 350 and the second device portion 140 in the through-hole 360.

[0071] The depicted light generating device 100 may also be known as a downright or recessed spot. The light generating device 100 is configured to emit device light 101 from the second side 141 during operation of the light generating device 100, as is schematically depicted by the lines 101 originating from the second side 141. The light generating device 100 is configured for illuminating the space 500 below the (ceiling) board 310 (at the second board side 312) with the device light 101. The space 500 is configured in a light receiving relationship with the second side 141.

[0072] The lighting arrangement 1 further comprises a heat spreader 200 configured in the cavity 350. The heat spreader 200 may support dissipation of heat (especially at least 3W) generated by the light generating device 100. Therefore, the light generating device 100 and the heat spreader 200 are configured in thermal contact with each other via the heat dissipating surface 130. The heat spreader 200 especially comprises a thermally conductive material. The thermal conductive material may have an in-plane thermal conductivity of at least 150 W / m / K. The thermal conductive material may for instance comprise one or more of aluminum, copper, graphite, such as pyrolytic graphite, graphene, and composites of graphene.

[0073] The heat spreader is preferably spread out in the cavity 350 to maximize its heat exchanging surface 265. This way the heat spreader may in embodiments have a heat exchanging surface 265 of at least 50 cm2. To keep the heat spreader in this spread-out or unfolded configuration, the heat spreader 200 may be connected to the first ceiling board side 311 with a connector 280 Such connector 280 may for instance comprise a physical connector and / or an adhesive material. The adhesive material may e.g., comprise glue or a double sided adhesive element such as tape) or a hook and loop fastener. Preferably the connector 280 is thermally conductive to facilitate heat dissipation via the board 310.

[0074] The schematically depicted embodiment of the heat spreader 200 in Fig. 1 (as well as the one depicted in Fig. 2) has a heat spreader opening 210 configured around the first device portion 120. The heat spreader 200 comprises an edge 211 at the heat spreader opening 210 in thermal contact with the heat dissipating surface 130. The depicted edge 211 is a raised edge, and may further e.g., be flexible and / or comprising notches. The heat spreader 200 is clamped against the heat dissipating surface 130 with a clamping element 270.

[0075] In the depicted embodiment, the light generating device 100 comprises a retention spring element 160 (especially two tension or torsion springs) connected to the first device portion 120 to (resiliently) force the light generating device 100 in a direction away from the space 500. To secure the light generating device in the construction arrangement 300, the light generating device 100 further comprises a blocking element 180 at the second device portion 140 for obstructing a movement of the light generating device 100 in the direction away from the space 500 at the moment that the blocking element 180 physically contacts the second board side 312. The lighting arrangement 1 of figure 1 also comprises an extended heat dissipating surface 165 associated to the retention spring element 160, as is verry schematically indicated. It is noted that the extended heat dissipating surface 165 is only partly visible in the given two dimensional figure. The extended heat dissipating surface 165 may have a third dimension perpendicular to the depicted two-dimensional lines. The extended dissipating surface 165 is connected to both of the retention springs 161 of the retention spring element 160. The springs 161 are configured at the first board side 311, wherein the head spreader 200 is sandwiched between the retention spring element 160 and the board 310. This way, the extended heat dissipating surface 165 is indirectly (via the retention spring element 160) thermally connected to the heat dissipating surface (130).

[0076] Fig. 2 very schematically depicts an embodiment of a heat spreader 200 configured in a cavity 350. The heat spreader 200 is configured in thermal contact with the heat dissipating surface 130 of a first device portion 120 of a light generating device 100. Here, the heat fins 131 on the heat dissipating surface are also visible. The heat spreader 200 comprises folding lines 250, such as performed lines, scores, or creases. The folding lines 250 are configured for facilitating folding the heat spreader 200 in a furled configuration A and for unfolding the heat spreader 200 in an unfurled configuration B (see also Fig. 3).

[0077] The depicted embodiment is an example of a heat spreader 200 comprising n*2 folding lines 250, with n being an integer (here n equals six, resulting in a hexagon), wherein extremes of the n*2 folding lines at the spreader opening 210 define a polygon shape (especially an / 7-gon) at the heat spreader opening 210 comprising n sides, wherein the n*2 folding lines 250 comprise n positive folding lines 251 (or mountain folding lines 251) and n negative folding lines 252 (or valley folding lines 252), wherein any positive folding line 251 is configured at an angle a of 180 / n degrees to a negative folding line 252. In the embodiment any one of the positive folding lines is aligned with a respective side of the polygonal shape. In further embodiments, the folding lines may be slightly curved. The depicted embodiment with slightly curved folding lines may provide a configuration resembling a starshade configuration.

[0078] The heat spreader 200 may especially be moved in the furled configuration A through the through-hole 360. In the lighting arrangement 1, the heat spreader 200 is especially configured unfolded in the unfurled configuration B. This way the heat spreader heat exchanging surface area 265 may be much larger in the unfurled configuration B than in the folded configuration A. It is noted that the term “heat spreader heat exchanging surface area” 265 especially refers to a total surface area of one side of sub-surfaces 265a, 265b, 265c (etcetera... ) of heat exchanging surface sub-areas of the heat spreader 200. A total size of the heat exchanging surface 265 may correspond to a total size of an area of the first board side 311 covered by the heat spreader 200. It especially refers to the effective heat exchange surface area which essentially may increase by flattening the heat spreader, e.g., by removing wrinkles and folds. Fig. 2 depicts an embodiment of the heat spreader 200 having a sheet-like shape in the unfurled configuration B.

[0079] The heat spreader of Fig. 2 is also depicted in Fig. 3, wherein the heat spreader 200 is (still partly) in the furled configuration A allowing it to be moved through a small through-hole 360 to install the heat spreader 200 in the cavity, e.g., using the method of the invention. As shown, the sub-surfaces 265a, 265b, 265c, ... , together forming the heat exchanging surface area, are arranged in a furled (or spiraled) configuration around the heat dissipating surface 130 of the first device portion 120 of the light generating device 100 enabling the sub-surfaces 265a, 265b, 265c, ... to overlap (in a projected view) in the radial direction, Dr,. Typically, the sub-surfaces 265a, 265b, 265c, ... partially extend next to each other in the tangential direction, Dt, and optionally abut each other in the radial direction, Dr, enabling the heatsink to assume in the collapsed configuration a relatively (very) compact shape with a relatively (very) small cross-sectional diameter. The depicted heat spreader 200 of Fig. 3 may be part of the kit of parts 2000 of the invention. Such kit 2000 may at least comprise a light generating device 100 and a heat spreader 200. The light generating device 100 is especially configured for installing in the construction arrangement 300 as defined in any one of the preceding claims. The heat spreader 200 of the kit of parts 2000 is especially configured to be moved through the through-hole and may embodiments comprise the folding lines 250 described above. In the kit of parts 2000, the heat spreader 200 is especially configured (folded) in the furled configuration A.

[0080] As indicated above, the folded configuration A may allow moving the heat spreader 200 through the through-hole and successively unfold to heat spreader to increase the (effective) heat spreader heat exchanging surface area 265. For instance, in embodiments, the through-hole 360 may comprise an opening cross-sectional area 365 and the heat spreader 200 in the unfurled configuration B may have a heat spreader heat exchanging surface area 265 that is at least ten times, such as at least 50 times larger than the opening cross-sectional area 365. The opening cross-sectional area is especially determined perpendicular to a shortest line connecting the first board side 311 to the second board side 312.

[0081] The heat spreader may next be unfolded. This may be done via the through- hole 360 with fingers or with a tool configured for changing the heat spreader 200 provided in the cavity 350 from the furled configuration A to the unfurled configuration B via the through-hole 360. In embodiments, the kit of parts 2000 may comprise the unfurling tool.

[0082] After unfolding the heat spreader 200 into the unfurled configuration B, the heat spreader may be connected to the first board side 311, see e.g., Fig. 1 showing the connections 280. Next the light generating device 100 may be installed in the construction arrangement 300. When installing the light generating device 100 the first device portion 120 is at least partly provided in the cavity 350 and the second device portion 140 is at least partly configured in the through-hole 360 for illuminating the space 500. Furthermore, installing may further comprise providing the heat dissipating surface 130 and the heat spreader 200 in thermal contact with each other.

[0083] In the embodiments of Figs. 2 and 3, the heat spreader 200 comprises a heat spreader opening 210 allowing to move the first device portion 120 of the light generating device 100 through the spreader opening 210. The opening 210 may especially match the size of the first device portion 120 and may e.g., comprise an edge 211 that may facilitate moving the first device portion 120 through the opening 210 as well as thermally contacting the heat dissipating surface 130 (when the light generating device 100 is installed). The edge 211 may in embodiments also be formed during moving the first device portion 120 through the heat spreader opening 210. The heat spreader 200 may e.g. comprise notches at the opening 210 that may form the edge 211. The heat spreader 200 may be flexible at the opening 210 resulting in a flexible edge 211 that may abut to the heat dissipating surface 130.

[0084] In Fig. 4, a further, especially more elongated embodiment of the heat spreader 200 is depicted in the furled configuration A and in the unfurled configuration B. In the furled configuration A, the heat spreader 200 may be moved through a through hole 360. Folding the depicted embodiment may for instance result in a width W that may be smaller than a diameter of the through-hole 360. The elongated heat spreader 200 may in embodiments comprise an edge 211 at a side of the heat spreader 200, as is indicated in the figure. That side may be connected to the heat dissipating surface 130 of the light generating device 100. In further embodiments, (also) the elongated heat spreader 200 may comprise a (central) opening 210 with an edge 211 to connect to the heat dissipating surface 130 as is explained in relation to Figs 2 and 3.

[0085] Fig. 5 schematically depicts an embodiment of a light generating system 1000 as described above. The light generating system 1000 comprises six light generating devices 100. Each light generating device 100 being thermally coupled to a heat spreader 200. Reference 701 indicates a user interface which may be functionally coupled with the control system 700 comprised by or functionally coupled to the light generating system 1000. Fig. 5 also schematically depicts an embodiment of a lighting arrangement 1 comprising the light generating system 1000. System light escaping from the light generating systemlOOO is indicated with reference 1001. System light 1001 may essentially consist of device light 101, and may in specific embodiments thus be device light 101. Reference 500 refers to a space, such as a room. References 300,301 refer to a construction arrangement / ceiling arrangement. Reference 350 refers to a cavity and reference 310 to a ceiling board; reference 1307 refers to a wall.

[0086] The term “plurality” refers to two or more. Furthermore, the terms “a plurality of’ and “a number of’ may be used interchangeably.

[0087] 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%. Moreover, the terms ’’about” and “approximately” 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%. For numerical values it is to be understood that the terms “substantially”, “essentially”, “about”, and “approximately” may also relate to the range of 90% - 110%, such as 95%-105%, especially 99%-101% of the values(s) it refers to.

[0088] The term “comprise” also includes embodiments wherein the term “comprises” means “consists of’.

[0089] 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".

[0090] 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.

[0091] The term “further embodiment” and similar terms may refer to an embodiment comprising the features of the previously discussed embodiment, but may also refer to an alternative embodiment.

[0092] 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.

[0093] In the claims, any reference signs placed between parentheses shall not be construed as limiting the claim.

[0094] 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”, “include”, “including”, “contain”, “containing” 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”.

[0095] The article "a" or "an" preceding an element does not exclude the presence of a plurality of such elements.

[0096] 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.

[0097] 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.

[0098] 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. Moreover, if a method or an embodiment of the method is described being executed in a device, apparatus, or system, it will be understood that the device, apparatus, or system is suitable for or configured for (executing) the method or the embodiment of the method, respectively. 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.

Claims

CLAIMS:

1. A lighting arrangement (1) comprising a light generating device (100), a heat spreader (200), and a ceiling arrangement (301); wherein: the light generating device (100) comprises (i) a first device portion (120) comprising a first side (121) of the light generating device (100) and (ii) a second device portion (140) comprising a second side (141) of the light generating device (100); wherein the first device portion (120) comprises a heat dissipating surface (130); wherein the light generating device (100) is configured to emit device light (101) from the second side (141); the heat spreader (200) comprises a thermally conductive material having a thermal conductivity of at least 150 W / m / K in-plane; the ceiling arrangement (301) comprises (a) a ceiling board (310) and (b) a cavity (350), configured at a first ceiling board side (311); wherein the ceiling board (310) comprises a through-hole (360); the light generating device (100) is at least partly configured in the ceiling arrangement (301), wherein the first device portion (120) is at least partly configured in the cavity (350) and wherein the second device portion (140) is at least partly configured in the through-hole (360); wherein the light generating device (100) is configured for illuminating a space (500) arranged at a second ceiling board side (312) with the device light (101); and the heat spreader (200) is configured in the cavity (350); and wherein the heat dissipating surface (130) and the heat spreader (200) are configured in thermal contact with each other, wherein the heat spreader (200) comprises folding lines (250) for facilitating (i) folding the heat spreader (200) in a furled configuration (A), and (ii) unfolding the heat spreader (200) in an unfurled configuration (B), allowing to move the heat spreader (2000) in the furled configuration (A) through the through-hole (360); wherein the heat spreader (200) is configured unfolded in the unfurled configuration (B) in the cavity (350).

2. The lighting arrangement (1) according to claim 1, wherein the heat spreader (200) is connected to the first ceiling board side (311) via one or more connectors (280)selected from the group of a physical connector, an adhesive material, and a hook and loop fastener.

3. The lighting arrangement (1) according to any one of the preceding claims, wherein the heat spreader (200) comprises one or more of aluminum, copper, graphite, and graphene.

4. The lighting arrangement (1) according to any one of the preceding claims, wherein the heat spreader (200) is configured for providing a heat dissipation of at least 3 W; wherein the heat spreader (200) has a heat exchanging surface (265) of at least 50 cm2.

5. The lighting arrangement (1) according to any one of the preceding claims, wherein the heat spreader (200) comprises a heat spreader opening (210) configured around the first device portion (120); wherein the heat spreader (200) at the heat spreader opening (210) comprises an edge (211), selected from one or more of (i) a raised edge, (ii) a flexible edge, and (iii) a notched edge, configured in thermal contact with the heat dissipating surface (130).

6. The lighting arrangement (1) according to claim 5, wherein the edge (211) of the heat spreader opening (210) in the furled configuration (A) and in the unfurled configuration (B) essentially has a same size.

7. The lighting arrangement (1) according to any one of the preceding claims, further comprising a clamping element (270) configured to clamp the heat spreader (200) against the heat dissipating surface (130).

8. The lighting arrangement (1) according to any one of the preceding claims, wherein the first device portion (120) comprises a retention spring element (160) configured for resiliently forcing the light generating device (100) in a direction away from the space (500); wherein the second device portion (140) comprises a blocking element (180) for obstructing a movement of the light generating device (100) in the direction away from the space (500) when the blocking element (180) is configured in physical contact with the second ceiling board side (312) of the ceiling board (310).

9. The lighting arrangement (1) according to claim 8, further comprising an extended heat dissipating surface (165), associated to the retention spring element (160), and thermally connected to the heat dissipating surface (130); and wherein the retention spring element (160) is configured in thermal contact with the heat spreader (200).

10. A kit of parts (2000) comprising (i) a light generating device (100) as defined in any one of the preceding claims and (ii) a heat spreader (200); wherein: the light generating device (100) is configured for installing in the ceiling arrangement (301) as defined in any one of the preceding claims; and the heat spreader (200) comprises a thermally conductive material having a thermal conductivity of at least 150 W / m / K in-plane; wherein the heat spreader (200) comprises folding lines (250) for facilitating (i) folding the heat spreader (200) in a furled configuration (A), and (ii) unfolding the heat spreader (200) in an unfurled configuration (B) allowing to move the heat spreader (2000) in the furled configuration (A) through the through-hole (360) of the ceiling arrangement (301).

11. The kit of parts (2000) according to claim 10, wherein the heat spreader (200) is configured in the furled configuration (A).

12. The kit of parts (2000) according to claim 11, wherein the through-hole (360) comprises an opening cross-sectional area (365); wherein the heat spreader (200) in the unfurled configuration (B) has a heat spreader heat exchanging surface area (265), wherein a ratio of the heat spreader heat exchanging surface area (265) to the opening cross-sectional area (365) is at least 10.

13. The kit of parts (2000) according to any one of the claims 10-12, wherein the heat spreader (200) in the unfurled configuration (B) has a sheet-like shape, wherein the heat spreader (200) comprises a heat spreader opening (210) configured for moving the first device portion (120) of the light generating device (100) through the spreader opening (210) during installation of the light generating device (100) in the ceiling arrangement (300) as defined in any one of the preceding claims 1-9, and for providing the thermal contact with the heat dissipating surface (130); wherein the heat spreader (200) at the heat spreader opening (210) comprises an edge (211) selected from one or more of (i) a raised edge, (ii) a flexible edge, and (iii) a notched edge, for thermally contacting the heat dissipating surface (130).

14. A method for installing a light generating device (100) with a heat spreader (200) in a ceiling arrangement (301) as defined in any one of claims 1-9; comprising: providing the heat spreader (200) in the cavity (350); and installing the light generating device (100) in the ceiling arrangement (301), wherein the first device portion (120) is at least partly configured in the cavity (350) and the second device portion (140) is at least partly configured in the through-hole (360) for illuminating a space (500) arranged at the second ceiling board side (312) with the device light (101); and providing the heat dissipating surface (130) and the heat spreader (200) in thermal contact with each other.

15. The method according to claim 14, wherein the heat spreader (200) comprises (i) a furled configuration (A) for providing the heat spreader (200) through the through-hole (360) from the second ceiling board side (312) to the first ceiling board side (311) and (ii) an unfurled configuration (B) for increasing a total heat dissipating capacity of the heat spreader (200); wherein the method comprises: providing the heat spreader (200) in the furled configuration (A) from the second ceiling board side (312) to the first ceiling board side (311) through the through-hole (360); changing the heat spreader (200) from the furled configuration (A) to the unfurled configuration (B) and connecting the heat spreader (200) to the first ceiling board side (311).

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