Optical element and luminaire

Abstract

An optical element (30) for influencing the light of a light source (15) forms a louvre which is formed by a grid-like arrangement of several reflector cells (31), each of which forming a ring-like closed wall (32) with a reflective surface which extends from a light entry opening (33) of the associated reflector cell (31) to a light exit opening (34) of the reflector cell (31), wherein the light exit openings (34) of all the reflector cells (31) are substantially in a common first plane (I) and wherein the light entry opening (33) of at least one of the reflector cells (31) defines a second plane (II) which is inclined relative to the first plane (I) of the light exit openings (34).

Description

[0001] The present invention is directed to an optical element used with a louvre cell luminaire. In addition, the present invention is directed to a luminaire, in particular a recessed luminaire, which uses a louvre for a direct emission of light and in addition provides for an additional emission of light by means of a side coffer.

[0002] A luminaire with a corresponding light emission as mentioned above is for example known from European patent EP 1 255 950 B1. The light emission mechanism of this known luminaire is designed to achieve uniform light distribution and create various lighting effects while maintaining a sleek and low-profile appearance. The luminaire uses a tubular gas discharge lamp as the primary light source. Light from this lamp is directed downwards through a raster or grid composed of side reflectors and transverse lamellae, which helps to evenly distribute the light and reduce glare, making it particularly suitable for use in environments with computer workstations. Additionally, the luminaire incorporates one or more concavely curved reflectors positioned next to the lamp. These reflectors, along with at least one partially light-permeable diffuser arranged before the reflector, enclose at least one so-called light chamber on each side of the lamp. This arrangement ensures that light is evenly spread out, enhancing the luminaire's ability to illuminate a space without causing discomfort from direct glare.

[0003] Gas discharge lamps are now usually replaced by longitudinal arrays of LEDs. However, the resulting louvre cell luminaires are still very directional in terms of light distribution. The light source, now formed by an elongated PCB with multiple LEDs, is positioned within the cell and the cell geometry controls the distribution accordingly. In the case of recessed luminaires, this again results in dark / unlit chambers on either side of the louvre. If these need to be illuminated, then additional LEDs / PCBs are typically required or the overall height of the louvre is reduced, resulting in less control of the direct light.

[0004] Accordingly, the present invention aims to provide a solution that enables efficient control of direct light emission through a louvre, while at the same time allowing areas on one side of the louvre to be illuminated with little effort. In particular, the need for an additional light source that specifically illuminates the side coffers of a luminaire is to be avoided.

[0005] The above object is solved by an optical element as defined in independent claim 1. Preferred embodiments of the present invention are subject matter of the dependent claims.

[0006] The core innovation lies in the design of the individual reflector cells of the louvre that feature an asymmetrical top. This unique shape allows for controlled spillage of light into the side coffers, creating a graduated lighting effect. The degree of light diffusion into the side coffer is determined by the extent of asymmetry on the top of the louvre. The novelty of this approach lies in its departure from traditional methods that adjust the space between the printed circuit board (PCB) and the top of the louvre to allow light leakage into the side coffers. Such conventional techniques often result in light waste, as some of the light dissipates ineffectively between the louvres. By introducing asymmetrical tops to the louvres, the invention minimizes light waste and enhances the control over light distribution, leading to a more efficient and aesthetically pleasing lighting solution. This technical feature represents a significant improvement over existing lighting designs, offering both functional and energy-saving benefits.

[0007] Accordingly, the present invention provides an optical element for influencing the light of a light source, wherein the optical element is a louvre which is formed by a grid-like arrangement of several reflector cells, each of which forming a ring-like closed wall with a reflective surface which extends from a light entry opening of the associated reflector cell to a light exit opening of the reflector cell, wherein the light exit openings of all the reflector cells are substantially in a common first plane, and wherein the light entry opening of at least one of the reflector cells defines a second plane which is inclined relative to the first plane of the light exit openings.

[0008] Preferably, the inclination of the second plane relative to the first plane of the light exit openings is about 15° to 30°. It has been shown that this inclination value represents an optimum compromise with regard to the ratio between the light emitted directly via the louvre reflector cell and the light transmitted into an area next to the louvre, whereby this light can then be used for additional light emission.

[0009] According to a preferred embodiment of the invention, the reflector cells form at least one row, wherein the light entry openings of all the reflector cells of this row define a common second plane which is inclined with respect to the plane of the light exit openings. Accordingly, at least some of the reflective cells are organized into at least one row, with all light entry openings in this row angled with respect to first plane so as to allow a uniform light emission over the entire length of the row.

[0010] Furthermore, preferably the reflector cells form two adjacent rows, the reflector cells of each of the two rows being inclined together with respect to the first plane of the light exit openings. In this case, the louvre comprises two rows of reflector cells, the cells of each row being collectively inclined with respect to the first plane, thereby allowing nuanced light manipulation. In particular, the two rows of reflector cells are symmetrical with respect to each other, wherein preferably the two planes of the light entry openings are symmetrically inclined with respect to each other. This symmetrical design ensures a balanced light distribution, eliminating shadows or uneven lighting. This symmetry is crucial for achieving consistent illumination across a larger space, enhancing aesthetic and functional qualities of the luminaire.

[0011] According to another embodiment of the present invention, next to the row of reflector cells with inclined light entry openings or between two rows of reflector cells with inclined light entry openings, at least one further row of reflector cells is arranged, the light entry openings of which define a third plane parallel to the first plane defined by the light exit apertures. In this case, the light of a light source associated with a cell of this additional row is used only for a direct light emission allowing an improved illumination of a specific area under the luminaire.

[0012] Preferably, all the light exit openings have the same shape, the light exit openings preferably being rectangular, more preferably square. Accordingly, all light exit openings are uniformly shaped, preferably rectangular or square, which ensures a uniform light output and a uniform appearance of the louvre.

[0013] According to the present invention, also a luminaire is provided comprising a light source and an optical element associated with the light source as explained above, wherein the luminaire additionally has, next to the inventive optical element - from an area to be illuminated by the luminaire as viewed - a light emission area through which at least part of the light emitted by the light source is emitted.

[0014] Preferably, this light emission area comprises at least one partially translucent light emission element arranged next to the optical element. This translucent light-emitting element can be a diffuser element or another element that is specially designed to specifically influence the light emission. It is also possible that the light emission area comprises - in addition to the translucent light emission element or as an alternative thereof - a reflector which is arranged next to the light source and which is preferably concave, in particular concave curved.

[0015] The light source preferably comprises an arrangement of LED light sources, each LED light source being assigned to one of the reflector cells. This arrangement ensures the inventive optical element efficiently controls the emission of the light provided by the light source.

[0016] The luminaire according to the present invention preferably is a recessed luminaire with a housing accommodating all essential elements, in particular the light source, the optical element and the elements of the additional light emission area.

[0017] In the following, the present invention is discussed in more detail with respect to the accompanying drawings. Figure 1 shows a cross-sectional view of a recessed luminaire comprising the inventive louvre for direct light emission and two additional light emission portions on both sides of the louvre. Figure 2 shows an enlarged part of the cross-sectional view of figure 1. Figure 3 shows a perspective view of a portion of the inventive louvre. Figures 4a, 4b and 4c show the light emission side, a cross-sectional view and the light distribution curve of a recessed luminaire according to the prior art. Figures 5a, 5b and 5c show the light emission side, a cross-sectional view and the light distribution curve of a recessed luminaire according to a first embodiment of the present invention. Figures 6a, 6b and 6c show the light emission side, a cross-sectional view and the light distribution curve of a recessed luminaire according to a second embodiment of the present invention.

[0018] In the recessed ceiling luminaire shown in Fig. 1 and generally marked with the reference sign 100, the various components of the luminaire 100 are arranged inside a box-shaped luminaire housing 10 which, when the luminaire 100 is installed, is recessed in the ceiling of a room to be illuminated. The housing 10 may have laterally protruding edge strips 10a at its edge regions which, when the housing 10 is inserted into a mounting opening in the ceiling, can completely close the mounting opening. In addition, these edge strips 10a can also have or support brackets - not shown - which allow adaptation to the thickness of the ceiling and thus ensure that the luminaire housing 10 is always flush with the surrounding ceiling or a corresponding support structure.

[0019] Within the housing 10, there is a generally longitudinal arrangement of LEDs serving as the light source 15 for the luminaire 100 and extending through the center of the luminaire housing 10. The specific arrangement of the LEDs is adapted to the structure of the inventive optical element and will be explained in detail later. The light from these LEDs is emitted through the light exit aperture formed on the front or underside of the housing 10, the light being emitted via the inventive louvre 30 and additionally via two additional light emission areas 40 on either side of the louvre 30. In order to ensure that the light emitted by the LEDs is used completely and effectively for illumination, two wing-like reflectors 45 also may be provided, which extend on both sides of the light source 15 towards the edge region of the housing 10 and from two curved coffers. These reflectors 45 are designed to be particularly concave, preferably concavely curved, as this special shape allows a very uniform additional light emission. As an alternative to the embodiment shown in Figure 1, a single reflector could be used which completely covers the light sources 15 and extends on both sides of the housing 10.

[0020] Furthermore, it should be noted that as an alternative to the illustrated embodiment, in which the reflectors 45 are formed by independent components or components separate from the housing 10, it would also be conceivable to use at least part of the inner wall of the luminaire housing 10 as a reflector surface. To achieve the preferred concave-shaped reflector surface in this case as well, the housing 10 could, for example, be angled in its corner areas or have corresponding inserts to ultimately form a concave shape composed of several partial surfaces. However, it would also be possible to use the pure box structure of the housing 10 for the formation of the two coffers, which again would allow the additional light emission. A luminaire that makes use of this type of structure will be explained later in relation to Figure 6.

[0021] Before explaining the structure of the inventive louvre 30 in more detail, it should be mentioned that the luminaire housing 10 is preferably closed by an additional optical element 50 forming a transparent cover. Since it is desirable for the light emitted via the lateral light emission areas to be distributed uniformly and homogeneously, this optical element 50 is preferably made of a light-scattering material forming a diffuser 55 in front of the two coffers. In order to prevent dust or small insects from entering the interior of the luminaire 100, it is also possible for this optical element 50 to completely close the housing 10 and thus also cover the bottom of the louvre 30. In this case, the corresponding part of the optical element 50 could be made of a transparent material so as not to affect the light emission of the louvre 30. However, since light diffusion only affects directed light to a certain extent, the diffusing material could also extend over the entire extent of the optical element 50, while the light emitted via the central portion is still specifically directed due to the influence of the louvre 30. This solution may be considered advantageous as it provides a more uniform appearance of the luminaire 100 when the light source 15 is deactivated.

[0022] The luminaire 100 shown in Figure 1 is intended to have similar photometric properties to the luminaires known from the prior art described above. Accordingly, on the one hand, it should direct light, i.e. emit light in certain angular areas, whereby this part of the light is directed or focused by the louvre 30. On the other hand, light is to be emitted in a non-directional or diffuse manner via the two lateral light-emitting areas 40.

[0023] In contrast to known solutions, which require an additional light source for emitting light via the side areas, the luminaire 100 according to the present invention only makes use of a single light source arrangement. This simplification of the structure of the luminaire 100 is achieved by the louvre 30 according to the invention, which is described in more detail below.

[0024] Similar to known louvres, the louvre 30 according to the invention also comprises a plurality of reflector cells 31 arranged in a grid-like pattern. This arrangement is crucial for creating a structured path for the light that passes through and is influenced by the louvre 30. Light that is emitted in this form makes it possible, for example, to illuminate working places with high intensity and quality and to avoid disturbing reflections. In the embodiment shown in the figures, the cells 31 are arranged in two neighboring rows 31 1 and 31 2 (Figure 3 shows one of these rows) along the extension of the light source 15. However, as will be explained later, the arrangement of cells 31 also could form only one row or even more than two rows.

[0025] Each reflector cell 31 forms a ring-like, closed wall 32 which encircles the light, guiding it through the cell 31. The inner surface of these ring-like walls 32 is reflective to ensure that light is directed efficiently and losses are minimized. The inclination and / or curvature of the reflector walls 32 and the size of the reflector cells 31 can be adjusted in order to influence light in a way desired for the application. Nevertheless, preferably all cells 31 have a similar shape.

[0026] Each cell has light entry opening 33 where light enters and a light exit opening 34 where light exits. The arrangement of LED light sources preferably corresponds to the arrangement of the reflector cells 31. In other words, the light source 15 comprises again a grid-like arrangement of individual LEDs or LED clusters, where each LED / LED cluster is assigned to one of the cells 31 and is preferably located centrally above the corresponding cell 31. Accordingly, a significant proportion of the light from an LED / LED source enters the associated cell 31 via the corresponding light entry opening 33 and is directed by the reflective wall 32 before finally being emitted via the corresponding light exit opening 34. In order to ensure a uniform appearance of the louvre 30, the shape of all the light exit openings 34 is preferably identical, wherein the light exit openings 34 can be circular or oval, but in particular are rectangular, e.g. square. More importantly, all the light exit openings 34 are substantially in a common first plane I (see Figure 2) which is preferably parallel to the plane of the housing opening. This alignment is key to ensuring that light exits the louvre 30 in a uniform direction, which is important for creating a consistent lighting effect.

[0027] In the embodiment shown in the figures, the light entry openings 33 of the cells 31 of one row 31 1 , 31 2 also are in a common plane. However, unlike the louvres known in the art, this second plane II is now inclined with respect to the first plane I. In particular, as shown in Figure 2, the inclination of the second plane II is such that the height of the reflector wall facing the adjacent coffer of the luminaire 100 is lower than the height of the opposite reflector wall. In the shown embodiment of a symmetric luminaire, the openings 33 of the two rows 31 1 , 312 are inclined in opposite directions but at the same angle α relative to the first plane I.

[0028] This special structure of the reflector cells 31 ensures that, unlike known louvres with reflector cells that are symmetrical over their entire height, a certain amount of light provided by an LED / LED cluster does not enter the assigned reflector cell 31, but is directed to the side of the adjacent coffer. Whilst sufficient light is still directed through the cells 31 of the louvre 30 and can be used for an efficient so-called task lighting, the total amount of light entering the coffers is also sufficient to provide additional light emission via diffusers 50 without the need for additional light sources. This inventive solution, which takes advantage of the fact that LED light sources normally emit light over a wide area, makes it possible to simplify the structure of the luminaire 100 and the number of parts, while achieving similar optical effects in terms of light emission.

[0029] Obviously, the ratio between the light emitted by a reflector cell 31 and the light entering the adjacent coffer depends on the inclination of plane II. By choosing an appropriate angle α, this ratio can be adjusted to a desired value, preferably with α approximately between 15° and 30°.

[0030] The effect of the solution according to the invention can be seen from a comparison of Figures 4, 5 and 6, where Figure 4a shows the light emission side of a luminaire according to the prior art when switched on, Figure 4b shows a partial cross-section of the luminaire and Figure 4c shows the resulting light distribution. Figures 5 and 6 show corresponding illustrations for two luminaires with a louvre according to the present invention.

[0031] Figure 4a clearly shows that when a 'classic' louvre is used, with light entry openings parallel to the light exit openings, only a small amount of light is emitted via the side coffers, which appear almost dark when no additional light source is used. In contrast, the two luminaires according to the present invention appear clearly with both side coffers illuminated, resulting in a significantly improved appearance when the luminaire is activated. Figures 5 and 6 also show that it would be possible to dispense with the curved reflector 45 or coffer and use only the rectangular housing of the luminaire to provide additional side light emission. However, the use of a curved reflector surface results in a more homogeneous illumination of the additional light emission areas, which is usually preferred.

[0032] Accordingly, the use of the inventive louvre allows simplify the structure a luminaire wherein still excellent light emission capabilities are obtained.

[0033] Finally, some further developments of the inventive concept will be discussed. It is not necessary for the louvre to comprise two rows of reflector cells which are symmetrically formed as shown in the figures. In particular, the present invention also covers louvres having a single row of reflector cells with light entry openings inclined with respect to the light exit openings. Such a louvre could be used in luminaires having only one additional light emission area adjacent to the louvre.

[0034] On the other hand, it is also possible for the louvre to consist of more than two rows of reflector cells. In this case, it is preferable that only the cells of one or both side rows have light entry openings that are inclined with respect to the light exit openings, while the remaining cells have 'classic' cells with the light entry openings parallel to the light exit openings. These 'classic' cells are primarily used for direct light emission, with the one or two side rows again responsible for allowing some light to enter the corresponding additional light emission area(s). Accordingly, various adaptations of the invention are possible.

Claims

1. Optical element (30) for influencing the light of a light source (15), wherein the optical element (30) is a louvre which is formed by a grid-like arrangement of several reflector cells (31), each of which forming a ring-like closed wall (32) with a reflective surface which extends from a light entry opening (33) of the associated reflector cell (31) to a light exit opening (34) of the reflector cell (31), wherein the light exit openings (34) of all the reflector cells (31) are substantially in a common first plane (I), characterized in that the light entry opening (33) of at least one of the reflector cells (31) defines a second plane (II) which is inclined relative to the first plane (I) of the light exit openings (34).

2. Optical element according to claim 1, characterized in that the inclination of the second plane (II) relative to the first plane (I) of the light exit openings (34) is about 15° to 30°.

3. Optical element according to claim 1 or 2, characterized in that the reflector cells (31) form at least one row (311, 312), the light entry openings (33) of all the reflector cells (31) of this row (311, 312) defining a common second plane (II) which is inclined with respect to the plane (I) of the light exit openings (34).

4. Optical element according to claim 3, characterized in that the reflector cells (31) form two adjacent rows (311, 312), the reflector cells (31) of each of the two rows (311, 312) being inclined together with respect to the plane (I) of the light exit openings (34).

5. Optical element according to claim 4, characterized in that the two rows (311, 312) of reflector cells (31) are symmetrical with respect to each other, in particular the planes (II) of the light entry openings (33) are inclined with respect to each other.

6. Optical element according to any one of claims 2 to 5, characterized in that next to the row (311, 312) of reflector cells (31) with inclined light entry openings (33) or between two rows (311, 312) of reflector cells (31) with inclined light entry openings (33), at least one further row of reflector cells (31) is arranged, the light entry openings (33) of which defining a third plane parallel to the first plane (I) defined by the light exit openings (34).

7. Optical element according to any of the preceding claims, characterized in that all the light exit openings (34) have the same shape, the light exit openings (34) preferably being rectangular, more preferably square.

8. A luminaire (100) comprising a light source (15) and an optical element (30) associated with the light source (15) according to any of the preceding claims, wherein the luminaire (100) additionally has, next to the optical element (30) - from an area to be illuminated by the luminaire as viewed - a light emission area (50) through which at least part of the light emitted by the light source (15) is emitted.

9. Luminaire according to claim 8, characterized in that the light emission area (50) comprises at least one partially translucent light emission element (40) arranged next to the optical element (30).

10. Luminaire according to claim 8 or 9, characterized in that the light emission area (50) comprises a reflector (45) which is arranged next to the light source (15) and which is preferably concave, in particular concave curved.

11. Luminaire according to one of claims 8 to 10, characterized in that the lights source (15) comprises an arrangement of LED light sources, each LED light source being assigned to one of the reflector cells (31).

12. Luminaire according to one of claims 8 to 11, characterized in that the luminaire (100) is a recessed luminaire with a housing (10) accommodating the light source (15), the optical element (30) and the elements of the additional light emission area (50).

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