Field of invention

The invention relates to a lighting fixture for an installed suspended ceiling.

Background of invention

A suspended ceiling is a secondary ceiling mounted at a predefined distance below the main ceiling. Suspended ceilings are commonly used in both residential and commercial premises. The first patent on suspended ceilings, U. S. Patent No.

1 ,470,728, goes back to 1919. Reasons for installing a suspended ceiling relate to hiding building infrastructure such as piping, electrical wiring or ductwork, generally aesthetical reasons, humidity resistance, balance and control of acoustics. Suspended ceilings are also relatively cheap.

A typical suspended ceiling construction has a horizontal grid of metal bars located at a certain distance from the main ceiling. The grid is typically attached to the main ceiling by means of hangers, wires or additional metal bars. A well-known and commonly used solution for mounting the surface of the suspended ceiling is to use inverted T-shaped metal bars (T-bars) as grid bars. This shape allows square or rectangular, lightweight ceiling panels (ceiling tiles) to be placed in the cells in the horizontal grid, either dropped directly into the cells of the grid, or in some cases suspended on the grid such that the lower edge of the panels extend below the lower edge of the grid, typically in the range of 15-40 mm. There are also C-bar and wood bar based solutions. Lighting is often retrofitted into the suspended ceiling systems, typically by replacing some of the ceiling panels with lighting units. The size of the ceiling panels could be for example 600 mm x 600 mm, 600 mm x 1200 mm or 600 x 1800 mm.

A technology that has also gained popularity is LED (light-emitting diode) lightning, often in integrated solutions wherein the LED lightings are integrated in the ceiling, either as independent spotlights or several lights configured to form patterns as an assembly. Alternatively the LED lighting fixtures are mounted on the underside of the ceiling. For suspended ceilings that are not equipped with LED lightings and LED lightings are required, retrofitting of the LED lights is necessary. There are several problems with retrofitting lighting for suspended ceilings. One is that the bars or other load carrying parts of the grid arrangements have to be cut, modified or adjusted to create space and hold the lighting fixtures, in particular when a lighting fixture is placed such that it crosses boundaries between sections of the load carrying grid

arrangement. A further issue relates to the need for electrical work and wiring in the space between the main ceiling and the suspended ceiling is required. Alternatively the lighting fixture is placed directly on the underside of the suspended ceiling and attached to the T-bar grid. In this solution, however, the lighting fixture cannot be considered to be fully integrated in the plane, which is clearly desirable from an esthetical perspective, but merely placed on the underside of the suspended ceiling.

Summary of invention

The present disclosure relates to a lighting fixture for an installed suspended ceiling and a method for mounting one or more of said lighting fixtures. The lighting fixture is adapted to be retrofitted on the underside of load carrying parts of the suspended ceiling forming a grid arrangement. It should be noted that the definition of grid is a framework of crisscrossed or parallel bars i.e. the invention is applicable both on a grid wherein the load carrying parts are crisscrossed forming squares and/or rectangular shaped sections, or on a grid wherein the load carrying bars are parallel forming oblong sections. The lighting fixture is recessed into and/or between the ceiling panels such that the ceiling panels extend between the lighting fixture and the grid arrangement. A key aspect of the presently disclosed lighting fixture is that it can be mounted substantially without altering the load carrying structure of a suspended ceiling.

The presently disclosed invention can be applied to suspended ceilings with grid based solutions wherein the suspended ceiling panels extend vertically below the lower edge of the grid i.e. they hang down from the grid, typically 15-40 mm, sometimes with the intention to conceal the grid fully or partially. Since the ceiling panels extend below the grid, a horizontal plane of panels with a thickness in the range of 15-40 mm can be said to be free from grid parts. The inventors have realised that with modern lighting technology (based on e.g. LED or OLED) it is possible to recess thin lighting fixtures, e.g. an oblong lightweight aluminium profile capable of holding LED lighting, possibly crossing boundaries between sections of the load carrying grid arrangement, in the vertical space between the T-bar grid arrangement and the lower edge of the ceiling panels. In the present invention the lighting fixture is designed such that it can be easily mounted (e.g. clipped) directly on load carrying parts of the suspended ceiling (e.g. T- bars, C-bars or wood bars). The main advantage is that the lighting profile can be mounted without cutting, modifying or adjusting the grid, which has to be done in the solutions for recessed lighting fixtures that are known in the art, and still be fully recessed.

In summary, the presently disclosed invention makes it possible to install modern recessed lighting into a suspended ceiling very easily (e.g. by clipping the lighting fixtures onto the load carrying parts) without cutting, modifying or adjusting the load carrying parts of the grid, by using the vertical space between the T-bar grid arrangement and the lower edge of the ceiling panels.

The lighting fixtures may be mounted in any horizontal direction of the suspended ceiling and can be extended to abut the edges of the suspended ceiling (usually the walls of the room). By extending the lighting fixtures in a longitudinal direction, a system with any combined total length can be obtained. In such a system, abutted to the wall, it is possible to let the lighting fixtures carry all the necessary electrical wires. Electrical wiring in the space between the suspended ceiling and the main ceiling can be avoided. Hence, a further advantage with the present invention is that not only the recessed lighting fixture can be easily mounted on the suspended ceiling without altering the load carrying structure of a suspended ceiling, but also the electrical wiring

Description of drawings

Fig. 1 shows the cross section of an embodiment of the presently disclosed lighting fixture.

Fig. 2 shows a pair of reflectors.

Fig. 3 shows a louvre between the light source and the cover of the lower end of a lighting fixture.

Fig. 4 shows three different covers for the lower end of a lighting fixture.

Fig. 5 shows possible covers to be mounted on a lighting fixture to obtain different optical light effects.

Fig. 6 shows the cross section of an embodiment of the presently disclosed lighting fixture and the cross section of a ceiling panel in a suspended ceiling with an example of mounting clip to be clipped to a T-bar.

Fig. 7 shows the cross section of the T-bar in fig.6 and the lighting fixture in fig.6 from another angle. The lighting fixture is attached to the T-bar by means of a clip. Fig. 8 shows an example of a mounting clip.

Fig. 9 shows the cross section of a T-bar and an embodiment of the presently disclosed lighting fixture with a mounting clip strapped around the T-bar, the ceiling panels being suspended on the lighting fixture.

Fig. 10 shows the cross section of an embodiment of the presently disclosed lighting fixture and the cross section of a ceiling panel in a suspended ceiling with an example of a mounting clip to be screwed to a load carrying part of a suspended ceiling or hooked to the main ceiling.

Fig. 11 shows the lighting fixture in fig. 10 from another angle. The lighting fixture is suspended with a clip to a hanger to be hooked to the main ceiling.

Fig. 12 shows an example of a mounting clip to be screwed to a load carrying part of a suspended ceiling or hooked to the main ceiling.

Fig. 13 shows a mounting for suspending a ceiling panel on a lighting fixture.

Fig. 14 shows a mounting clip for suspending a lighting fixture onto load carrying parts of a suspended ceiling.

Fig. 15 shows a mounting clip suspending a lighting fixture onto an inverted T-bar.

Fig. 16 shows a lighting fixture, strapped onto an inverted T-bar, with a filler profile between the T-bar and the lighting fixture to maintain the lighting fixture at a distance from the load carrying part.

Fig. 17 shows the filler profile in fig. 16 from another angle.

Detailed description of the invention

The present disclosure relates to a lighting fixture for an installed suspended ceiling having ceiling panels, the lighting fixture having a maximum thickness of less than 40 mm and a maximum width of less than 200 mm, wherein the lighting fixture is adapted to be retrofitted on the underside of load carrying parts of the suspended ceiling, wherein the load carrying parts are T-bars forming a grid arrangement. The inventors have realised that by having a rather thin lighting fixture, the space between the load carrying parts of the suspended ceiling and the lower edge of the ceiling panels can be utilized for a recessed lighting fixture that can be retrofitted on load carrying parts of the suspended ceiling without cutting, modifying or adjusting the load carrying parts of the grid. In one embodiment the lighting fixture is configured to be recessed into gaps between ceiling panels of the suspended ceiling such that the ceiling panels are suspended between the lighting fixture and load carrying parts of the grid arrangement, or the ceiling panels are suspended between load carrying parts of the grid arrangement and abut the lighting fixture. The presently disclosed lighting fixture can be retrofitted on an installed suspended ceiling. The lighting fixture is mounted on the underside of the T-bars that are arranged in a grid arrangement. Since the lighting fixture is configured to be placed on the underside of the grid of inverted T-bars, the lighting fixtures can be extended horizontally, under the grid since the lighting fixture is placed on the underside of the existing suspended ceiling, across sections in the installed grid without having to remove or change parts in the existing grid.

In one embodiment the presently disclosed lighting fixture is configured such that the lower edge of the lighting fixture is substantially in level with the lower edge of the ceiling panels, which is explained in further detail in the two sections about thickness of the lighting fixture and positioning of the lighting fixture.

In a further embodiment the presently disclosed lighting fixture is having a maximum thickness of less than 60 mm, or less than 55 mm, or less than 50 mm, or less than 45 mm, or less than 40 mm, or less than 35 mm, or less than 30 mm, or less than 25 mm, or less than 20 mm, or less than 15 mm, or less than 10 mm.

In a further embodiment the presently disclosed lighting fixture is having a maximum width of less than 200 mm, or less than 190 mm, or less than 180 mm, or less than 170 mm, or less than 160 mm, or less than 150 mm, or less than 140 mm, or less than 130 mm, or less than 120 mm, or less than 1 10 mm, or less than 100 mm, or less than 90 mm, or less than 80 mm, or less than 70 mm, or less than 60 mm, or less than 50 mm. Load carrying constructions of suspended ceilings come in a variety of solutions; some of these are T-bar, C-bar and wood bar based solutions. In the T-bar based solutions, load carrying inverted T-bars, so-called main runners, are suspended at a

predetermined distance from the main roof, parallel with a predetermined fixed distance between the load carrying T-bars. Additional transversal inverted T-bars in the same horizontal plane are fixed to the load carrying bars, the assembly thereby forming a grid. Usually the ceiling panels in the suspended ceiling rest on the grid, thus usually demountable. Different solutions wherein parts of or all of the panels extend in the vertical direction from the load carrying parts are possible, wherein the bars are possibly, at least partially, concealed. These solutions could be visualised in that the panels hang down from the grid, typically in the range of a few millimetres to 40 millimetres. The reason for having such solutions may be to create a visual effect e.g. in that the grid is concealed.

In C-bar based solutions, the bars are fastened (e.g. screwed) in a fixed position at a predetermined distance from the main ceiling. In this solution the panels are screwed onto the C-bars or locked with a mounting, but as in the T-bar based solutions, the panels extend vertically, creating a layer of the panel below the grid. In C-bar based solutions the grid is always concealed and the panels are not demountable. In wood bar based solutions the same mounting principles of the panels as for the C-bars may be used.

The presently disclosed lighting fixture is suitable for solutions wherein parts of or all of the panels extend in the vertical direction from the load carrying parts of a suspended ceiling. In the presently disclosed invention, the lighting fixture for a suspended ceiling is adapted to be mounted on the underside of load carrying parts of the suspended ceiling, the load carrying parts forming a grid arrangement. The lighting fixture is configured to be recessed into gaps between the ceiling panels. In e.g. fig. 9 it can be seen how a lighting fixture 1 is mounted directly below a T-bar (cross section of lighting fixture and T-bar showed).

These gaps may be created in the original suspended ceiling by sliding the panels away from the area in which the lighting fixtures should be recessed. This scenario requires that lighting fixture is placed transversal to the load carrying bars of the suspended ceiling. The panels are slid towards the walls to create the space corresponding to the size of the lighting fixtures to be recessed. The panels abutting the walls may have to be adjusted/cut accordingly. If the panels cannot be slid as described, the gaps can be obtained by cutting the ceiling panels and removing parts of the ceiling panels, such that gaps between the ceiling panels are created

corresponding to the size of the lighting fixture. Cutting the panels is a task that can be done relatively easily by a craftsman since the panels are often made of soft, light material. If a new suspended ceiling is installed, the needed gaps can often be taken into account and planned for to avoid cutting of the panels. When the new suspended ceiling has been installed, the lighting fixture can be mounted without altering the load carrying structure of a suspended ceiling. The lighting fixture can preferably be mounted directly on load carrying parts of the suspended ceiling; further details about the mounting are available below.

The main advantage with the presently disclosed invention is that the lighting fixture(s) can be easily mounted on the underside of load carrying parts of an existing suspended ceiling without cutting, modifying or adjusting any load carrying parts of the grid and still have a solution in which the lighting fixture is fully recessed into the suspended ceiling. The lighting fixture according to present invention is independent from the suspended ceiling in the sense that it works for and can be mounted on any suspended ceiling having ceiling panels extending below the load carrying parts.

Because of the convenience and ease of the mounting of the lighting fixture it can also be considered to be used when installing a new suspended ceiling. Furthermore, the convenience and ease of the mounting of the lighting fixture makes it possible to replace lighting fixtures very easily e.g. if they are broken, or to upgrade the lighting. It is also possible to move the lighting fixtures to other sections of the suspended ceiling for lighting reasons or if an interior wall is to be placed where the lighting fixture is located.

The lighting fixture may be placed in any direction in the horizontal plane. Depending on whether the direction of the lighting fixture is parallel or transversal in relation to the load carrying bars, two situations have to be considered:

1 . If the lighting fixture is placed parallel to the load carrying bar, the panels that have been cut to fit the lighting fixture may lose their suspension to the load carrying bars. Therefore, in the present invention, these ceiling panels are suspended between the lighting fixture and load carrying parts of the grid arrangement. Fig. 9 shows an example of a lighting fixture placed parallel to a load carrying T-bar. Here it should be noted that the ceiling panels 8 have lost their original suspension to T-bar 10, and therefore, in this example, they are suspended on lighting fixture 1 .

2. If the lighting fixture is placed transversal to the load carrying bar, the side of the panels that are cut to fit the lighting fixture do not lose any suspension to the load carrying parts of the grid arrangement, thus they retain their original suspension between load carrying parts of the grid arrangement and abut the lighting fixture. Fig. 6 can serve as an example to illustrate a lighting fixture placed transversal to a T-bar 10 seen from the side. It should be noted that the ceiling panel does not need support from the side facing the lighting fixture, and thus only abuts the side wall 6 of the lighting fixture.

In order for the recessed lighting fixture to fit into the space between the lower edge of the vertically extending ceiling panels and the load carrying parts, there is a

requirement of maximum thickness of the lighting fixture, which depends on the construction of the suspended ceiling. This requirement is usually in the range of 10-40 mm, for example 10 mm, 1 1 mm, 12 mm, 13 mm, 14 mm, 15 mm, 16 mm, 17 mm, 18 mm, 19 mm, 20 mm, 22 mm, 24 mm, 25 mm, 26 mm, 28 mm, 30 mm, 32 mm, 34 mm, 36 mm, 38 mm or 40 mm, but could also be less than 10 mm, for example 1 mm, 2 mm, 3 mm, 4 mm, 5 mm, 6 mm, 7 mm, 8 mm or 9 mm, or more than 40 mm depending on the design of the suspended ceiling. Generally, less space between the lower edge of the vertically extending ceiling panels and the load carrying parts means more demanding requirements on the thickness of the lighting fixture. With the LED and OLED technology of today it is possible to meet these requirements on thickness and other requirements related to e.g. generated heat. Solutions capable of providing functional lighting with efficient heat dissipation are available. A material that can typically meet the requirements related to heat dissipation is aluminium; however, other materials can also be imagined for example plastics, such as polycarbonate (PC) or polymethylmethacrylate (PMMA). An example of the thickness requirement is illustrated in fig. 6. In this example the thickness 9, corresponding to the distance between the lower edge of T-bar 10 and the lower edge of ceiling panel 8, constitutes a limit for the thickness of the lighting fixture, if the lighting fixture should be fully recessed into the suspended ceiling.

An important aspect of the invention is that the lighting fixture is configured such that the lower edge of the lighting fixture is substantially in level with the lower edge of the ceiling panels. This is achieved by utilizing the space between the lower edge of the vertically extending ceiling panels and the load carrying parts. As can be seen in e.g. fig. 6 and fig. 9, the lighting fixture is recessed such that the underside of the lighting fixture forms a smooth plane with the underside of the neighbouring ceiling panels. "Substantially in level" in this context should be interpreted broadly as the lighting fixture being mounted such that a person observing the lighting fixture from a natural position in the room (e.g. standing on the floor or sitting on a chair) can be considered to have the visual impression that the lighting fixture and neighbouring ceiling panels form a substantially smooth plane. In practice this means that in a room where the ceiling is relatively close to the person observing it, e.g. 0.5-3 metres, a difference of only a few millimetres may be visible to the observer, whereas in e.g. an assembly hall, where the ceiling could be 10-15 metres from the observer, a greater difference between the levels could be still be regarded as smooth plane from the observer's position.

It is important to note that in the presently disclosed invention, the recessed lighting fixture described above can be achieved without cutting, modifying or adjusting any load carrying parts of the grid. In any other known recessed lighting fixture for suspended ceiling, whenever the lighting fixture crosses boundaries between sections of the load carrying grid arrangement, the bar has to be cut, modified, adapted or built around to achieve fully recessed lighting fixtures. In the present invention, the lighting fixture may be retrofitted without curing, modifying or adjusting the load carrying parts such that the lighting fixture crosses at least one boundary between sections of the load carrying grid arrangement. In other words, the lighting fixtures may extend horizontally, crossing load carrying parts of the suspended ceiling, i.e. extending over several sections of the grid, having the same cross section profile along the whole lighting fixture, and still be easily (e.g. clipped) mounted on the underside of load carrying parts of the suspended ceiling without cutting, modifying or adjusting any load carrying parts of the grid.

The lighting fixture according to the present invention can be used in the suspended ceiling solution based on inverted T-bars described above, but also in the solutions based on C-bars and wood bars. The mounting of the lighting fixture may vary between the different suspended ceiling solutions; these mounting variations are described in further detail below.

As explained, when the lighting fixture is placed parallel to the load carrying bar, the ceiling panels may have to be suspended on the lighting fixtures. Hence, one embodiment of the present invention further comprises at least one mounting configured to suspend the ceiling panels on the lighting fixture. For some configurations at least two mountings may be necessary. Different designs of such a mounting are imaginable. In one embodiment, refer to fig. 13, the mounting is configured to be mounted on the side of a ceiling panel facing the lighting fixture, having a horizontal lip configured to rest on the lighting fixture, thereby suspending the ceiling panel on the lighting fixture. In another embodiment, the bottom side of the lighting fixture is extended in the horizontal plane towards the ceiling panels, forming lips on which the ceiling panels rest.

The cross section of the lighting fixture may be inverted U-shaped, refer to e.g. fig. 1. U-shaped in this context should be interpreted as the shape of the original cross section of the lighting fixture without the additional cover 2 or diffusion foil 7 on the lower end, which can be seen as additional features to create optical light effects.

The lighting fixture is preferably made of a relatively light material such as

polycarbonate (PC), polymethylmethacrylate (PMMA) or a light metal such as aluminium. The reason for using a light material is that the load carrying parts of the suspended ceiling are designed to carry the ceiling panels with a certain margin. By using a material and design of the lighting fixture such that lighting fixture weighs less than 1 .5 kg/m, measured in the longitudinal direction of the lighting fixture, the load carrying parts of the suspended ceiling are capable of carrying both the ceiling panels and the lighting fixture according to the present invention. Light lighting fixtures can also be achieved by using thin, yet rigid, side walls of the lighting fixtures. The thickness of the material is typically less than 2 mm, but could also be 1 mm or as close as possible to 0 mm as long as the side walls are still rigid. Limiting the width of the lighting fixture is another way of making the lighting fixture light enough to be held by the load carrying parts. By limiting the width to less than 200 mm, it is possible to achieve a lighting fixture that can be held by the load carrying parts; however, it should be noted that with thinner and lighter lighting technologies it is imaginable to use lighting fixtures wider than 200 mm. Typically the range of a lighting fixture is in the range of 24-60 mm or 60-120 mm.

Since one overall objective with the presently disclosed invention is to provide recessed lighting easily mounted on a suspended ceiling, it is also important that the electrical wiring can be done easily. In many solutions known in the prior art, the electrical wiring typically has to be done somewhere in the space between the suspended ceiling and the main ceiling. This can be seen as an inconvenient solution, especially if the panels are not detachable (C-bar and wood bar solution). One aspect of the present invention relates to the possibility to let the lighting fixtures carry electrical wires. A further aspect of the presently disclosed system relates to the possibility to elongate the lighting fixture by adding and connecting other similar lighting fixtures. By extending the lighting fixtures in a longitudinal direction, a system with any combined total length can be obtained. The advantage with such a system is that it can make several lighting fixtures appear as one long lighting fixture. Furthermore, such a system enables for electrical wiring between the units. If the system is mounted such that is abuts a wall, electrical wiring from the wall into the first lighting fixture, and then further on to all other lighting fixtures in the system, is possible. This advantage can be considered to further ease the mounting a lighting system. In order to keep the lighting fixtures in fixed positions relative to each other, a clip such as the mounting clip in fig. 8 (identical to the mounting clip in fig. 6), without the part 12 intended to be clipped to the T-bar, may be placed such that approximately half of the clip is on one lighting fixture and

approximately half of the clip is one the lighting fixture connected to the first one.

The presently disclosed invention further comprises at least one mounting clip configured to attach the lighting fixture to the load carrying parts. A range of clips may be used to be able to attach the lighting fixture to the load carrying parts as smoothly as possible without cutting, modifying or adjusting any load carrying parts of the grid. For some embodiments of mounting clips, e.g. the mounting clip in fig. 7, at least two mounting clips are preferred in order to attach from both sides of the T-bar. When attaching the lighting fixture to an inverted T-bar, the inventors have realised that a convenient solution is to clip the lighting fixture onto the lower end of the T-bar; an example of this is shown in fig. 7. The clip may be made of a resilient or elastic material to ease the mounting as much as possible. This approach is typically used when the direction of the lighting fixture is transversal in relation to the T-bar. In the case when the direction of the lighting fixture is parallel in relation to the load carrying bar and the lighting fixture is mounted under the load carrying bar, one option is to use a mounting clip that is strapped around the upper end of the inverted T-bar, see e.g. fig. 9. This clip may also be made of a resilient or elastic material to ease the mounting. Another type of mounting clip, which may typically be used for C-bar or wood bar based solutions, is a mounting clip that can be screwed to load carrying parts, see e.g. fig. 12. A further option is a mounting clip, wherein the end attached to the load carrying parts is hooked to a load carrying part. If the lighting fixture is thinner than the available vertical space between the load carrying parts and the lower edge of the panels of the suspended ceiling, other types of mounting clips can be used in order to maintain the lower edge of the lighting fixture at the same level as the lower edge rest of the suspended ceiling. This can be achieved by having a mounting clip that holds the lighting fixture at a distance from the load carrying part corresponding to the difference between the thickness of the lighting fixture and the distance between the load carrying part and the lower edge of the panel. Such a solution for a lighting fixture transversal to the load carrying bar is showed in fig. 14.

Similarly, if the lighting fixture is placed under a T-bar in the same direction as the T- bar, an additional filler profile can be placed between the T-bar and the lighting fixture to maintain a distance from the load carrying part corresponding to the difference between the thickness of the lighting fixture and the distance between the load carrying part and the lower edge of the panel. Fig. 16 shows such a filler profile (1 ), which is placed between the T-bar 10 and the lighting fixture 1.

Since the described mounting clip attaches to both a load carrying part of the grid and the lighting fixture, the end attaching to the lighting fixture also needs to be described. This part corresponds to first part 1 1 of the mounting clip depicted in fig. 8. Fig. 6 shows how the mounting clip may be clipped onto the upper end of the lighting fixture. The clip may also, alternatively, be hooked around or screwed onto the upper end of the lighting fixture. A further solution on how to attach the lighting fixture to load carrying parts of the grid involves magnets attached on the upper side of the lighting fixture. If the load carrying parts are not magnetic themselves, magnetic elements may be placed on the load carrying parts to enable the use of the magnets attached on the upper side of the lighting fixture to hold the lighting fixture in a fixed position.

The lighting fixture may also comprise light sources, e.g. light-emitting diodes (LED) or organic light-emitting diodes (OLED). The light source(s) shall be placed inside the frames of the lighting fixture, i.e. it shall not cross the boundary that is the lower edge of the lighting fixture. In the presently disclosed invention the flexible length and width of the lighting fixture opens for different configurations of the light sources. The light sources may be placed with any distance between each other and organized in basically any pattern. Pattern 1 in fig. 5 is a pattern consisting of two parallel straight lines of light sources with equal distance between the light sources within each line. As described above the cross section of the lighting fixture may be inverted U-shaped. Such a configuration may comprise a cover mounted on the lower end of the lighting fixture such that the lower end of the lighting fixture is closed. Different covers may create different optical light effects. If the light source only should spread light from spots, the cover is made of an opaque material with openings for light sources in the lighting fixture. Other covers made of fully transparent materials, light diffusion materials or transparent, structured prism surfaces are also possible. This provides different light options for the present invention.

A further aspect of the present invention, relating to the convenience and ease of the mounting the lighting fixture and its independence from the suspended ceiling, is the possibility to attach or integrate one or more power supplies. The power supply can either be integrated inside the lighting fixture, or, alternatively, mounted on the backside (upper side) of the lighting fixture. The power supply could be e.g. clipped, screwed or taped to the lighting fixture.

A further aspect of the presently disclosed invention relates to a method for mounting one or more of the lighting fixtures described above. In the case where the ceiling panels are demountable, the method involves the steps of removing the ceiling panels in areas of the suspended ceiling where the lighting fixtures are to be mounted, attaching the lighting fixtures to one or more load carrying parts, installing electrical wiring connected through the lighting fixtures to an external power supply, cutting the removed ceiling panels to create gaps between the ceiling panels corresponding to the sizes of the lighting fixtures, placing the removed panels in their original position and attach or abut them to the lighting fixtures, thereby recessing the lighting fixtures into the gaps between the panels such that the lower edge of the lighting fixture is substantially in level with the lower edge of the ceiling panels. For a suspended ceiling wherein the ceiling panels are not demountable, or in which it is possible to move the ceiling panels away from the area intended for the lighting fixtures (this requires that the lighting fixture is placed transversal to the load carrying bars), there is an alternative method for mounting one or more of the lighting fixtures. The method for mounting one or more lighting fixtures according to the description above comprises the steps of cutting the ceiling panels to create gaps between the ceiling panels corresponding to the sizes of the lighting fixtures, or sliding neighbouring ceiling panels away from the area corresponding to the size of the lighting fixture, thereby creating gaps between the ceiling panels, attaching the lighting fixtures to one or more load carrying parts, and installing electrical wiring connected through the lighting fixtures to an external power supply. In the case where panels are slid towards the walls to create the space corresponding to the size of the lighting fixtures to be recessed, the panels abutting the walls may have to be adjusted/cut accordingly.

Examples

Fig. 1 shows the cross section of an embodiment of the presently disclosed lighting fixture. This inverted U-shaped lighting fixture has a light source 3 (and a second light source further to the right in the drawing), a pair of reflectors 4 (also shown in a separate drawing, fig. 2), a cover 2, a louvre 5 between the light source and the cover (also shown in a separate figure, fig. 3) and diffusion foil 7. The lighting fixture 1 is the shell that holds the construction together, typically made of light metal. It should be noted that the upper part of the lighting fixture is shaped so that a mounting clip easily can be clipped around the upper corners.

Figures 2-5 are more detailed drawings of some of the components in fig. 1 . Fig. 4 illustrates three different covers that are typically used in a lighting fixture: transparent (3), diffusive (2) and prismatic (1 ).

Fig. 6 shows the cross section of an embodiment of the presently disclosed lighting fixture 1 and the cross section of a ceiling panel 8 in a suspended ceiling with an example of mounting clip (comprising a first part 1 1 and a second part 12) to be clipped to a T-bar 10. In this example the lighting fixture 1 is transversal to the T-bar 10. In this drawing it can be seen how the lighting fixture is fully recessed into the suspended ceiling by utilizing the vertical space9 between the load carrying part (T-bar 10) of the suspended ceiling. 1 1 and 12 are the two parts of the mounting clip in this example, wherein the second part 12 is attached to the lighting fixture and the first part 1 1 is attached to T-bar 10. It should be noted that in this example the lighting fixture 1 is transversal to the T-bar 10, on which the panels hang, and therefore no suspension between the panel 8 and the lighting fixture is needed.

Fig. 7 shows the T-bar and lighting fixture in fig.6 from another angle. The purpose of this figure is to show an example of a clipping mechanism i.e. how the lighting fixture can be clipped to the T-bar 10 by means of a mounting clip having a first part 1 1 and a second part 12. Fig. 8 is a more detailed view of the mounting clip in fig. 7.

Fig. 9 shows the cross section of a T-bar 10 and an embodiment of the presently disclosed lighting fixture 1 with a mounting strap 13 strapped around the T-bar, the ceiling panels 8 being suspended on the lighting fixture. Since the ceiling panels 8 have lost their original suspension on the T-bar 10, the neighbouring ceiling panels 8 need support from the lighting fixture 1 . In this example the design supporting one of the the panels 8 is a mounting 14, which is attached to the panel 8 and rests on the lighting fixture 1 . Fig. 13 is a more detailed view of the mounting 14 in fig. 9. As can be seen it has horizontal inside lips 15 that can be inserted in the panel and an outside horizontal lip 16 configured to rest on the lighting fixture and thereby suspend the panel.

Fig. 10 shows the cross section of an embodiment of the presently disclosed lighting fixture and the cross section of a ceiling panel 8 in a suspended ceiling with an example of a mounting clip having a second part 12 to be screwed to a load carrying part of a suspended ceiling or hooked to the main ceiling. The mounting clip is similar to the mounting clip depicted in fig. 8, but has a hole 17 on a vertical surface, which is part of the mounting clip. The hole 17 can be used to screw the mounting clip onto load carrying parts of the suspended ceiling. Fig. 1 1 shows a similar embodiment of the presently disclosed lighting fixture, wherein the mounting clip is suspended on a hanger 18. Fig. 12 is a more detailed view of the mounting clip in fig. 10.

Fig. 14 shows an example of a detail of a mounting clip for suspending a lighting fixture onto load carrying parts of a suspended ceiling. This kind of mounting clip may be used if the lighting fixture is thinner than the available vertical space between the load carrying parts and the lower edge of the panels of the suspended ceiling. Fig. 15 shows how the mounting clip in fig. 14 can be used to suspend a lighting fixture onto an inverted T-bar and keep the lighting fixture at a distance from the inverted T-bar.

Fig. 16 shows a lighting fixture 1 strapped onto an inverted T-bar 10, with a filler profile 18 between the T-bar and the lighting fixture to maintain the lighting fixture at a distance from the load carrying part. In this solution, the filler profile 18 should have a thickness corresponding to the difference between the thickness of the lighting fixture and the distance 19 between the load carrying part and the lower edge of the panel. Fig. 17 shows the filler profile in fig. 16 from another angle. Further details of the invention

The invention will now be described in further detail with reference to the following items:

1 . A lighting fixture for a suspended ceiling (having ceiling panels), the lighting fixture having a maximum thickness of less than 40 mm and a maximum width of less than 200 mm, wherein the lighting fixture is adapted to be mounted on the underside of load carrying parts of the suspended ceiling, the load carrying parts forming a grid arrangement, and wherein the lighting fixture is configured to be recessed into gaps between ceiling panels of the suspended ceiling such that

the ceiling panels are suspended between the lighting fixture and load carrying parts of the grid arrangement, or

the ceiling panels are suspended between load carrying parts of the grid arrangement and abut the lighting fixture.

The lighting fixture according to any of the preceding items, configured such that the lower edge of the lighting fixture is substantially in level with the lower edge of the ceiling panels. 3. The lighting fixture according to any of the preceding items, wherein the load carrying parts are inverted T-bars.

The lighting fixture according to any of the preceding items, wherein the ceiling panels are suspended on the load carrying parts such that the lower edge of the panels extends vertically below the lower edge of the grid.

The lighting fixture according to any of the preceding items, wherein the ceiling panels are suspended on the load carrying parts such that the lower edge of the panels extends vertically below the lower edge of the grid, wherein the lower end of the panels are extended horizontally, at least partially concealing the load carrying parts.

6. The lighting fixture according to any of the preceding items, configured to be mounted such that the lighting fixture crosses at least one boundary between sections of the load carrying grid arrangement. The lighting fixture according to any of the preceding items, wherein the bottom side of the lighting fixture is extended in the horizontal plane towards the ceiling panels, forming lips on which the ceiling panels rest. The lighting fixture according to any of items 1 -6, further comprising at least one mounting configured to suspend the ceiling panels on the lighting fixture. The lighting fixture according to any of the preceding items, wherein the cross section of the lighting fixture is inverted U-shaped. The lighting fixture according to any of the preceding items, wherein said lighting fixture is made of a light material, selected from the group of plastics, such as polycarbonate (PC) or polymethylmethacrylate (PMMA), or aluminium. The lighting fixture according to any of the preceding items, wherein the side walls of the lighting fixture are thinner than 2 mm The lighting fixture according to any of the preceding items, configured to carry electrical wires. The lighting fixture according to any of the preceding items, wherein the lighting fixture is elongatable with a similar lighting fixture, configured to be extended in a longitudinal direction. The lighting fixture according to item 13, wherein the elongated lighting fixture is attached to another lighting fixture by means of a clip configured to keep the two lighting fixtures in a fixed position. The lighting fixture according to any of the preceding items, further comprising at least one mounting clip configured to attach the lighting fixture to the load carrying parts.

The lighting fixture according to item 15, wherein the load carrying parts are inverted T-bars. The lighting fixture according to any of items 15-16, wherein the part of the mounting clip attached to the lighting fixture is configured to be hooked around, screwed or clipped onto the upper end of the lighting fixture, and/or wherein the part of the mounting clip attached to the inverted T-bar is clipped onto the lower end of the inverted T-bar, and/or wherein the part of the mounting clip attached to the inverted T-bar is strapped around the upper end of the inverted T-bar. The lighting fixture according to any of items 15-17, wherein the part of the mounting clip attached to the load carrying parts is made of a resilient or elastic material. The lighting fixture according to any of items 15-18, wherein the mounting clip is screwed to load carrying parts. The lighting fixture according to any of the preceding items, further comprising a magnet attached on the upper side of the lighting fixture. The lighting fixture according to any of the preceding items, further comprising at least one light source attached to the lighting fixture. The lighting fixture according to item 21 , wherein the light sources are light- emitting diodes (LED). The lighting fixture according to item 21 , wherein the light sources are organic light-emitting diodes (OLED). The lighting fixture according to any of items 21 -23, wherein the light sources are placed independently of each other within the lighting fixture. The lighting fixture according to any of items 21 -24, wherein the light sources are placed to form patterns as an assembly.

The lighting fixture according to any of items 21 -25, further comprising a cover mounted on the lower end of the lighting fixture such that the lower end of the lighting fixture is closed. 27. The lighting fixture according to item 26, wherein parts of the cover, above which no light sources are placed, are made of an opaque material.

28. The lighting fixture according to item 26, wherein the cover is made of a

transparent material.

29. The lighting fixture according to item 26, wherein the cover is made of a light diffusion material. 30. The lighting fixture according to item 26, wherein the cover is a transparent, structured prism surface.

31 . The lighting fixture according to any of the preceding items, further comprising at least one power supply for the lighting fixture.

32. The lighting fixture according to item 31 , wherein the power supply is configured to be integrated in the lighting fixture or light source.

33. The lighting fixture according to item 31 , wherein the power supply is mounted on the backside of the lighting fixture.

34. The lighting fixture according to item 33, wherein the power supply is mounted on the backside of the lighting fixture by means of a mounting clip. 35. The lighting fixture according to any of the preceding items, wherein said

lighting fixture weighs less than 1 .5 kg/m, measured in the longitudinal direction of the lighting fixture.

36. A system comprising a plurality of lighting fixtures according to any of the

preceding items, wherein the lighting fixtures are connected to each other, forming a system of lighting fixtures with any combined total length.

37. Method for mounting one or more lighting fixtures according to any of items 1 - 35 in a suspended ceiling having ceiling panels suspended between load carrying parts, wherein the ceiling panels are demountable, the method comprising the steps of removing the ceiling panels in areas of the suspended ceiling where the lighting fixtures are to be mounted,

attaching the lighting fixtures to one or more load carrying parts, installing electrical wiring connected through the lighting fixtures to an external power supply,

cutting the removed ceiling panels to create gaps between the ceiling panels corresponding to the sizes of the lighting fixtures,

placing the removed panels in their original position and attach or abut them to the lighting fixtures, thereby recessing the lighting fixtures into the gaps between the panels such that the lower edge of the lighting fixture is substantially in level with the lower edge of the ceiling panels. Method for mounting one or more lighting fixtures according to any of items 1 - 35 in a suspended ceiling having ceiling panels suspended between load carrying parts, the method comprising the steps of

cutting the ceiling panels to create gaps between the ceiling panels corresponding to the sizes of the lighting fixtures, or sliding neighbouring ceiling panels away from the area corresponding to the size of the lighting fixture, thereby creating gaps between the ceiling panels,

- attaching the lighting fixtures to one or more load carrying parts,

installing electrical wiring connected through the lighting fixtures to an external power supply.