EP4705673A1 - Luminaire - Google Patents

Abstract

A luminaire (10), comprising: a plurality of lighting modules (12, 12'), each comprising a backside (14) and a plurality of light emitting diodes (16) adapted to emit LED light (18); and a back plate (20), the back plate comprising: a rear major surface (22a); a front major surface (22b) facing the backsides of the plurality of lighting modules; and a plurality of protrusions (26) on the front major surface of the back plate, wherein the plurality of protrusions of the back plate are in contact with the backsides of the plurality of lighting modules.

Description

LUMINAIRE

FIELD OF THE INVENTION

The present invention relates to an LED luminaire e.g. for ceiling office lighting.

BACKGROUND OF THE INVENTION

Luminaires, for example for ceiling office lighting, may comprise a plurality of light emitting diodes (LEDs) adapted to emit light. Luminaires may for example be panels or troffers that can be recessed in the ceiling.

SUMMARY OF THE INVENTION

It may be desired that a luminaire comprises multiple lighting modules each having LEDs, wherein each individual lighting module can be removed and re-installed easily. Challenges here include the alignment of the modules on the front side of the luminaire, thermal management related to the lighting modules, space needed for cable routing, and closing a t-grid system in an office ceiling.

It is an object of the present invention to overcome these problems, and to provide an improved luminaire.

According to a first aspect of the invention, this and other objects are achieved by a luminaire, comprising: a plurality of lighting modules, each comprising a backside and a plurality of light emitting diodes (LEDs) adapted to emit LED light; and a back plate, the back plate comprising: a rear major surface; a front major surface facing the backsides of the plurality of lighting modules; and a plurality of protrusions on the front major surface of the back plate, wherein the plurality of protrusions of the back plate are in (mechanical and/or thermal) contact with the backsides of the plurality of lighting modules.

The present invention is at least partly based on the understanding that the protrusions of the back plate may serve to align the lighting modules (in the height direction) when they are installed from the front side of the luminaire. The protrusions may also form useful internal spaces between the backsides of the lighting modules and the front surface of the backplate e.g. for cable routing. Furthermore, the protrusions also ensure thermal contact from the lighting modules towards the back plate of the luminaire.

In one embodiment, the plurality of protrusions are formed by corresponding dimples in the rear major surface. The dimples/protrusions may for example be formed by punching. Since the dimples (by definition) are closed and do not puncture the back plate, the dimpled back plate may seal a ceiling in which the luminaire may be recessed in case of fire. Furthermore, the dimples strengthen the back plate, by making it stiffer, which in turn facilitates alignment of the lighting modules.

In another embodiment, the plurality of protrusions are formed by a plurality of brackets fixed to the front major surface of the back plate. The brackets may for example be sheet metal struts/bridges spot welded to the front major surface of the back plate. By means of the brackets, the integrity of the back plate may be maintained for fire safety. The brackets also strengthen the back plate, by making it stiffer, which in turn facilitates alignment of the lighting modules.

Each of the protrusions may have a flat tip, which flat tip is parallel to the front major surface and mechanically contacts at least one of the backsides of the plurality of lighting module.

Said backside may be the backside of at least one LED board, such as dual parallel LED boards, of each lighting module, wherein the plurality of LEDs are mounted on an opposite front side of the at least one LED board. The at least one LED board may for example be at least one printed circuit board (PCB).

At least some of the plurality of protrusions may each contact the backsides of (exactly) two adjacent lighting modules. That is, two lighting modules could share one protrusion, this to guarantee front surface alignment between these lighting modules. This lowers the tolerance needed for the backplate.

The plurality of protrusions may be arranged in an array with a plurality of rows and columns on the front major surface, such as a 6x7 array or a 3x7 array.

The plurality of lighting modules may be aligned with said columns. The protrusions in the outermost columns along opposite edges of the back plate may each have a smaller contact area (e.g. smaller flat tip) and contact a single lighting module of said plurality of lighting modules. The protrusions in the columns between the outermost columns may each have a larger contacting area (e.g. larger flat tip), and contact dual lighting modules of said plurality of lighting modules (as discussed above). The larger contact areas may be elongated across the dual lighting modules. In this way, these protrusions can readily contact dual lighting modules in the elongated direction, but at the same time take up less room in the perpendicular direction (and make internal spaces larger, see further hereinbelow). The elongated larger contact areas may for example be stadium shaped, elliptical, or rectangular. The smaller contact area may for example be circular or square.

Internal spaces may be formed between the plurality of protrusions, wherein at least some of the internal spaces conveniently accommodate other components of the luminaire between the backsides of the lighting modules and the front major surface of the backplate.

The protrusions may be arranged in an array with a plurality of rows and columns on the front major surface, and the internal spaces between the protrusions may be interconnected in a direction along the rows of the array and in a direction along the columns of the array.

The above-mentioned elongated larger contact areas can make these internal spaces roomy in the perpendicular direction. The other components of the luminaire may comprise at least one of: cabling, means (e.g. torsion springs) for attaching the lighting modules to the back plate, and components (e.g. connectors) mounted on the backside of the lighting modules.

The center-to-center spacing between each adjacent two protrusions may be in the range of 80-300 mm, such as (approximately) 100 mm. Approximately 100 mm center- to-center spacing may ensure optimized thermal performance.

The height h of each protrusion (corresponding to the depth of the aforementioned dimples) may be in the range of 3-12 mm, such as (approximately) 8 mm. This to fit cables and connectors between the lighting modules and back plate.

The back plate can be made out of metal, specifically aluminum for better thermal conductivity. Alternatively, the back plate can be made of plastics or steel.

Each lighting module may further comprise a cup module including a plurality of reflector cups for the plurality of light emitting diodes. In this way, the luminaire may have only three main layers from front to back: 1. cup module(s), 2. LED board(s) with LEDs, and 3. back plate. This results in minimum material usage in modular systems.

One of the rows or columns (of protrusion) may comprise an elongated hole at least partly accommodating a driver of the luminaire. The plurality of lighting modules may be removably attached to the back plate, so that the lighting modules can be individually removed from the luminaire from the front side and replaced by a new or repaired lighting module. This improves the sustainability of the luminaire. It also allows for easy replacement of a lighting module when the luminaire is already installed in a closed ceiling.

The luminaire may be an office lighting luminaire, in particular a recessed office lighting luminaire, such as a panel. The luminaire may also be for linear lighting, suspended light, free floor standing, wall mount, etc.

It is noted that the invention relates to all possible combinations of features recited in the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

This and other aspects of the present invention will now be described in more detail, with reference to the appended drawings showing embodiments of the invention.

Fig. 1 is an exploded perspective view of a luminaire showing the rear major surface of the backplate of the luminaire according to an embodiment of the present invention with dimples.

Fig. 2 is an exploded perspective view of the luminaire in Fig. 1, here showing the front major surface of the backplate of the luminaire.

Fig. 3 is a top view of the backplate of the luminaire in Fig. 1.

Fig. 4a illustrates section A-A from Fig. 3, and

Fig. 4b is an enlargement from Fig. 4a.

Fig. 5a illustrates section B-B from Fig. 3, and

Fig. 5b is an enlargement from Fig. 5a.

Fig. 6 is a perspective view of a backplate of a luminaire according to another embodiment with brackets.

Fig. 7 is a front view of a linear luminaire according to an embodiment of the invention.

Fig. 8 is a front view of a frame-shaped luminaire according to an embodiment of the invention.

Like reference numerals refer to like elements throughout. DETAILED DESCRIPTION

The present invention will now be described more fully hereinafter with reference to the accompanying drawings, in which currently preferred embodiments of the invention are shown. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided for thoroughness and completeness, and fully convey the scope of the invention to the skilled person.

Figs. 1-2 show a luminaire 10 according to an embodiment of the present invention. The luminaire 10 may for example be an office lighting luminaire, in particular a recessed office lighting luminaire, such as a panel. The luminaire 10 may for example have an overall square shape, e.g. measuring 2' x 2' or 600x600 mm.

The luminaire 10 comprises a plurality of lighting modules 12, 12’. The lighting modules 12, 12‘ could also be referred to as light modules. The luminaire 10 may for example comprise six lighting modules 12, 12‘. Each lighting module 12, 12’ may be elongated, e.g. have a rectangular shape, for example measuring 86x572 mm. The lighting modules 12, 12’ may be arranged side by side in the luminaire 10. Alternatively, the lighting modules could be arranged as a light line/series arrangement (in a straight/linear luminaire; see Fig. 7), or as a square or rectangular frame (in a frame-shaped luminaire; see Fig. 8).

Each lighting module 12, 12’ comprises a backside 14, and a plurality of LEDs 16 adapted to emit LED light 18, for example white LED light 18. The backside 14 may be formed by the backsides of two parallel elongated LED boards 30 of each lighting module 12, 12’, wherein the LEDs 16 of each lighting module 12, 12’ may be mounted on front sides 32 of the two LED boards 30 (see Fig. 4b). Each lighting module 12, 12’ may for example comprise 4x16x2=128 LEDs.

Each lighting module 12, 12’ may further comprise a cup module 44 including a plurality of reflector cups 46 for the plurality of LEDs 16. Each lighting module 12, 12’ may for example comprise 16x2=32 reflector cups 46 (four LEDs 16 per cup 46). Each lighting module 12, 12’ may further comprise lenses/optics for the LEDs 16. Furthermore, the lighting modules 12, 12’ are preferably removably attached, so that the lighting modules 12, 12’ can be individually removed from the luminaire 10 from the front side and replaced by a new or repaired lighting module. This improves the sustainability of the luminaire 10.

The luminaire 10 further comprises a back plate 20. The back plate 20 may form, or at least form part of, a (luminaire) housing of the luminaire 10. The back plate 20 may be square, for example measuring 580x580 mm. The back plate 20 comprises a rear (major) surface 22a, and an opposite, front (major) surface 22b. The front major surface 22b faces the backsides 14 of the plurality of lighting modules 12, 12’. The back plate 20 can for example be made of aluminum.

In accordance with the embodiment in Figs. 1-2, the back plate 20 comprises a plurality of dimples 24 in the rear major surface 22a, wherein a back plate thickness t is defined between the rear major surface 22a and the front major surface 22b of the back plate 20, and wherein the dimples 24 have a depth d exceeding the back plate thickness, such that the dimples 24 form corresponding protrusions 26 on the front major surface 22b of the back plate 20. In other words, the (plurality of) protrusions 26 on the front major surface 22b of the back plate 20 are formed by the corresponding dimples 24 in the rear major surface 22a.

Furthermore, the protrusions 26 of the back plate 20 are in mechanical and/or thermal contact with the backsides 14 of the plurality of lighting module 12, 12’, see Figs. 4b and 5b. The contact may serve to mechanically align the lighting modules 12, 12’ in the height/thickness/depth direction (i.e. the vertical direction in Figs. 4b and 5b) when the lighting modules 12, 12’ are installed from the front side of the luminaire 10. The protrusions 26 may also ensure thermal contact from the lighting modules 12, 12’ towards the back plate 20 of the luminaire 10. To achieve good/sufficient contact, each of the protrusions 26 may have a flat tip 28a-b. The flat tip 28a-b may be parallel to the front major surface 22b of the back plate 20.

Turning to Fig. 3, the protrusions 26 (and corresponding dimples 24) may be arranged in an array with a plurality of rows 34 and columns 36, 36’, 36”. In Fig. 3, the array has six rows 34 and seven columns 36, 36’, 36” of protrusions 26, i.e. a 6x7 array. Also in Fig. 3, one column 36” comprises an elongated hole 48 partly accommodating a driver 50 for powering the plurality of LEDs 16. This column 36” only has two protrusions 26, as seen in Fig. 2.

The lighting modules 12, 12’ may be aligned with the columns 36, 36’, 36”. Specifically, the protrusions 26 in the outermost columns 36’ along opposite edges 38 of the back plate 20 may each have a smaller contact area (e.g. smaller flat tip 28a) and contact a single lighting module 12’, whereas the protrusions 26 in the columns 36, 36” between the outermost columns 36’ may each have a larger contacting area (e.g. larger flat tip 28b) and contact dual lighting modules 12. That is, some of the protrusions 16 may each contact the backsides 14 of exactly two adjacent (=parallel) lighting modules 12, 12’. As seen in Fig. 4b, each of these protrusions 16 with larger contacting area/flat tip 28b may contact the backside of the LED board 30 of one lighting module 12’ as well as the backside of the LED board 30 of an adjacent lighting module 12. On the other hand, the protrusions 16 with smaller contacting area/flat tip 28a only contact (the backside the other LED board 30 of) the lighting module 12’. So each lighting module 12, 12’ contacts the protrusions 26 in two adjacent columns 36, 36’, 36”, for improved stability and alignment.

The larger contact areas/flat tips 28b may be elongated across the dual lighting modules 12. The elongated larger contact areas/flat tips 28b may for example be stadium shaped, as in Fig. 3. The smaller contact areas/flat tips 28c may for example be circular, as in Fig. 3.

As seen for example in Figs. 4b and 5b, internal spaces 40 may be formed between the protrusions 16.

The protrusions 16 are arranged in an array with a plurality of rows 34 and columns 36, 36’, 36” on the front major surface 22b. The internal spaces 40 formed between the protrusions 16 are interconnected in a direction along the rows 34 of the array and in a direction along the columns 36, 36’, 36”of the array, thereby essentially forming a network of interconnected internal spaces 40 extending between the front major surface 22b of the back plate 20 and multiple lighting modules 12, 12’.

The aforementioned network of interconnected internal spaces 40 can be conveniently used to accommodate other components of the luminaire 10, especially components that are intended for multiple lighting modules 12, 12’.

As said, at least some of the internal spaces 40 (or, at least part of the network of interconnected internal spaces 40) may accommodate other components of the luminaire 10 between the backsides 14 of the lighting modules 12, 12’ and the front major surface 22b of the backplate 20.

In other words, the internal spaces 40 are defined by the sides of the protrusions 16, (non-contacting) portions of the backsides 14 of the lighting modules 12, 12’, and portions of the front major surface 22b apart from the protrusions.

The other components of the luminaire 10 may comprise at least one of: cabling, means for attaching the lighting modules 12, 12’ to the back plate 20, and components (e.g. connectors) mounted on the backside 14 of the lighting modules 12, 12’.

The means for attaching the lighting modules 12, 12’ to the back plate 20 may for example be torsion springs 42, specifically two torsion springs 42 per lighting module 12, 12’. One torsion spring 42 may be arranged towards one short end of the elongated lighting module 12, 12’, and the other torsion spring 42 may be arranged towards the other short end of the elongated lighting module 12, 12’. When the lighting modules 12, 12’ are attached to the back plate 20, legs of the torsion springs 42 are inserted though corresponding (small) openings 43 in the back plate 20. By using the torsion springs 42, no screws are needed for attaching the lighting modules 12, 12’ to the back plate 20.

In Fig. 4b, one can also see that internal spaces 40’ may formed between the protrusions 16 in the outermost columns 36’ and the edges 38 of the back plate 20. These internal spaces 40’ may be covered/closed by a rim 52 of the luminaire 10. The rim 52 is also shown in Fig. 2.

Returning to Fig. 3, the center-to-center spacing etc between each adjacent two protrusions 16 may be in the range of 80-300 mm, such as 100 mm. Approximately 100 mm center-to-center spacing may ensure optimized thermal performance. At or around 300mm, each column 36, 36’ may comprise three protrusions 26 (no more no less; resulting in a 3x7 array): one protrusion centered between the two torsion springs 42, one protrusion between one of the torsion springs 42 and its corresponding short end of the lighting module 12, 12’, and one protrusion between the other torsion spring 42 and its corresponding short end of the lighting module 12, 12’. Furthermore, the height h of each protrusion 16 may be in the range of 5-12 mm, such as 8 mm. The height h is illustrated in Figs. 4b and 5b.

Moving on to Fig. 6, Fig. 6 shows a backplate 20 of luminaire 10 according to another embodiment. Here, the protrusions 26 are formed by a plurality of brackets 54 fixed to the front major surface 22b of the back plate 20, and there are no dimples 24 in the rear major surface 22a of the back plate 20. The brackets 52 may for example be sheet metal struts/bridges spot welded to the front major surface 22b. Each bracket 52 may include a U- shape with a flat tip/bottom 28a-b for contacting the backplate 14, as well as legs for fixation to the front major surface 22b. As in the previous embodiment, some of the brackets 52 may be arranged to contact the backsides 14 of two adjacent lighting modules 12, 12’. Specifically, the brackets/protrusions 52/26 in the outermost columns 36’ may each have a smaller contact area (e.g. smaller flat bottom 28a) and contact a single lighting module, whereas the brackets/protrusions 52/26 in the columns 36, 36” between the outermost columns 36’ may each have a larger contacting area (e.g. larger flat bottom 28b) and contact dual lighting modules. The smaller contact area/flat bottom 28a may create more room, e.g. for a sensor or future luminaire upgrade.

Fig. 7 shows a linear luminaire 10 according to an embodiment of the present invention. In the linear luminaire 10, the lighting modules 12 are arranged as a light line/series arrangement. Some of the protrusions 26’ may each contact the backsides of two adjacent (=consecutive) lighting modules 12 in the series arrangement. Other protrusions 26” may act as side steps. Reference sign 56 denotes a cable meandering underneath the lighting modules 12 in the internal space formed between the protrusions 26, 26’, and 26”.

Fig. 8 shows a frame-shaped luminaire 10 according to an embodiment of the present invention. In the frame-shaped luminaire 10, for example four lighting modules 12 may be arranged as a square or rectangular frame. Some of the protrusions 26’ in the corners of the frame-shaped luminaire 10 may each contact the backsides of two adjacent lighting modules 12. Other protrusions 26” “just” serve to align the front surface. Each protrusions 26” may be centrally located along its lighting module 12.

The person skilled in the art realizes that the present invention by no means is limited to the preferred embodiments described above. On the contrary, many modifications and variations are possible within the scope of the appended claims. For example, at least one of the lighting modules in the luminaire 10 could be replaced by a similar modules, but without any LEDs/lighting functionality. Such a module could instead merely have an aesthetical function. In this way, a 6-lighting module luminaire could easily be converted to e.g. a 4- or 2-lighting module luminaire.

Additionally, variations to the disclosed embodiments can be understood and effected by the skilled person in practicing the claimed invention, from a study of the drawings, the disclosure, and the appended claims. In the claims, the word "comprising" does not exclude other elements or steps, and the indefinite article "a" or "an" does not exclude a plurality. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measured cannot be used to advantage.

Claims

CLAIMS:

1. A luminaire (10), comprising: a plurality of lighting modules (12, 12’), each comprising a backside (14) and a plurality of light emitting diodes, LEDs, (16); and a back plate (20), the back plate comprising:

- a rear major surface (22a);

- a front major surface (22b) facing the backsides of the plurality of lighting modules; and

- a plurality of protrusions (26) on the front major surface of the back plate, the plurality of protrusions being formed by corresponding dimples (24) in the rear major surface, or by a plurality of brackets (54) fixed to the front major surface of the back plate, wherein the plurality of protrusions of the back plate are in contact with the backsides of the plurality of lighting modules, wherein the plurality of protrusions is arranged in an array with a plurality of rows (34) and columns (36, 36’, 36”) on the front major surface, wherein internal spaces (40) are formed between said plurality of protrusions, the internal spaces (40) being interconnected in a direction along the rows (34) of the array and in a direction along the columns (36, 36’, 36”) of the array, and wherein at least some of the internal spaces accommodate other components (42) of the luminaire between the backsides of the lighting modules and the major front surface of the backplate.

2. A luminaire according to claim 1, wherein the internal spaces formed between the protrusions are interconnected in a direction along the rows of the array and in a direction along the columns of the array, thereby essentially forming a network of interconnected internal spaces extending between the front major surface of the back plate and multiple lighting modules.

3. A luminaire according to any one of the preceding claims, wherein the other components of the luminaire comprise at least one of cabling, means (42) for attaching the lighting modules to the back plate, and components mounted on the backside of the lighting modules.

4. A luminaire according to any one of the preceding claims, wherein each of the protrusions has a flat tip (28a-b), which flat tip is parallel to the front major surface and mechanically contacts at least one of the backsides of the plurality of lighting modules.

5. A luminaire according to any one of the preceding claims, wherein said backside is the backside of at least one LED board (30) of each lighting module, and wherein the plurality of LEDs are mounted on an opposite front side (32) of the at least one LED board.

6. A luminaire according to any one of the preceding claims, wherein at least some of the plurality of protrusions each contacts the backsides of two adjacent lighting modules.

7. A luminaire according to any one of the preceding claims, wherein the plurality of lighting modules (12, 12’) are aligned with said columns, wherein the protrusions in the outermost columns (36’) along opposite edges (38) of the back plate each has a smaller contact area (28a) and contacts a single lighting module (12’) of said plurality of lighting modules, and wherein the protrusions in the columns (36, 36”) between the outermost columns each has a larger contacting area (28b) and contacts dual lighting modules of said plurality of lighting modules.

8. A luminaire according to claim 7, wherein the larger contact areas (28b) are elongated across the dual lighting modules.

9. A luminaire to any one of the preceding claims, wherein the center-to-center spacing (etc) between each adjacent two protrusions is in the range of 80-300 mm.

10. A luminaire according to any one of the preceding claims, wherein the height (h) of each protrusion is in the range of 3-12 mm.

11. A luminaire according to any one of the preceding claims, wherein the back plate is made out of aluminum.

12. A luminaire according to any one of the preceding claims, wherein the luminaire is an office lighting luminaire.