A light shaping element for a luminaire

Abstract

A light shaping element for shaping light emitted by a light source of a luminaire. The light shaping element comprises a plurality of slats, having a first side and a second side. The first side is configured to perform retroreflection of light received from the light source. The second side is configured to perform specular or diffusive reflection of light received from the light source.

Description

[0001] 2024PF80510

[0002] 1

[0003] A LIGHT SHAPING ELEMENT FOR A LUMINAIRE

[0004] FIELD OF THE INVENTION

[0005] The present invention relates to the field of lighting, and in particular to a light shaping element for a luminaire.

[0006] BACKGROUND OF THE INVENTION

[0007] There is an increasing reliance upon lighting systems, particularly for use in commercial and industrial environments. Although a wide variety of lighting systems are known, typical commercial lighting systems comprise of a grid of luminaires (e.g., panels, troffers, linear luminaires) with a fixed luminaire spacing. This layout is particularly useful for low-cost lighting systems, as all luminaires are structurally identical, and the installation is relatively straightforward.

[0008] More advanced lighting systems are known and available. Such lighting systems may include more specific or bespoke luminaires, which are designed to more efficiently or flexibly illuminate a space by controlling the direction in which light is emitted.

[0009] One advantage of such systems is the ability to reduce light emitted towards windows, thereby reducing light pollution from the environment in which the lighting system is positioned. More specifically, reducing the amount of light directed towards windows reduces a risk of light trespass, glare, adverse ecological impact, and / or skyglow at night.

[0010] However, low-cost lighting systems that comprise a grid of luminaires are indiscriminately as to which direction light is output. It would therefore be advantageous to facilitate control or configuration of light output directions for such luminaires, or a subset of such luminaires.

[0011] SUMMARY OF THE INVENTION

[0012] The invention is defined by the claims.

[0013] According to examples in accordance with an aspect of the invention, there is provided a light shaping element for a luminaire.

[0014] The light shaping element comprises a plurality of slats, wherein each slat comprises a first side, configured to perform retroreflection of received (output) light, and a2024PF80510

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[0016] second side configured to perform specular reflection and / or diffuse reflection of received (output) light.

[0017] The present disclosure provides a light shaping element that is able to provide an asymmetrical light distribution of light produced by a light source having a symmetrical light distribution with high efficiency. The light shaping element may, for instance, be used to reconfigure the light distribution of existing luminaires to avoid or reduce an amount of light that is emitted into undesirable regions (e.g., out of windows or upon walls), and maintain light within useful or usable environments.

[0018] In particular, the proposed light shaping elements reduces an amount of light emitted in directions away from the first side of the slats or towards the second side of the slats (i.e., regions faced by the first side of the slats) whilst maintaining an amount of light emitted in directions away from the second side of the slats or towards the first side of the slats (i.e., regions faced by the second side of the slats).

[0019] The use of a retroreflective side allows for the remixing or recycling of light that would otherwise be blocked by the slats, whilst still facilitating the attenuation of light emitted in directions away from the first side of the slats.

[0020] The light shaping element may be a retrofittable light shaping element for connection to or against a light source of a pre-existing luminaire.

[0021] In some examples, the plurality of slats extend substantially parallel to one another. This provides a more even or uniform intensity or luminous flux within the asymmetrical light distribution of light output by the luminaire.

[0022] In some examples, for each slat, the first side and the second side face away from one another. This approach advantageously improves the effect of the asymmetrical light distribution , making the mean shape of light and / or light spread more even or smooth. More particularly, this approach recognizes that different forms of lighting shaping or effect are demanded in opposing directions to achieve light shaping of the overall luminaire.

[0023] In some examples, for each slat, the first side and the second side extend substantially parallel to one another. This improves the smoothness of the asymmetrical light distribution produced by the luminaire.

[0024] In some examples, each slat, of the plurality of slats, lies in a same first plane. Moreover, in some examples, for each slat: the first side is substantially perpendicular to the first plane; and the second side is substantially perpendicular to the first plane.2024PF80510

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[0026] In some examples, for each slat, the second side is configured to specularly reflect no less than 80% of the received (output) light. This provides a highly efficient light shaping element with reduced absorption and / or scattering.

[0027] In some examples, a spacing between each of the plurality of slats is no less than 10 mm.

[0028] In preferred examples, a height of each slat is between 0.8 and 1.2 times the spacing between each of the plurality of slats. A ratio of height: spacing of around 1 (e.g., between 0.8 and 1.2) has been identified as achieved good evenness or smoothness of an asymmetrical light distribution.

[0029] More particularly, A height-spacing ratio of around 1 has been found to work well because, for a typical use-case scenario of a luminaire in a ceiling of an indoor environment, as this will function to block or redirect a majority of the light emitted by the light source towards a window. Typically light emitted (out of a window) by a conventional light source is light that is emitted at angles between around 20° / 30° from the vertical downward direction and 90°, i.e. horizontal light). A height-spacing ratio of around 1 will have minimal or negligible impact on the light that goes straight downward (within ~20 deg deviation from vertical), i.e., serves to illuminate the indoor environment. The skilled person will appreciate that the most advantageous height: spacing ratio may depend upon the specific use-case scenario. For instance, for a luminaire is relatively close to the wall (compared to a typical luminaire layout in the ceiling), a larger height: spacing ratio is preferred to also block light that is emitted at smaller angles with respect to the vertical. In situations, where the luminaire is relatively far from the window, a smaller height: spacing ratio works better for more efficient illumination of the indoor space.

[0030] In some examples, for each slat: the first side and the second side extend from a second plane to a third plane, wherein the third plane is parallel to the second plane; and the distance between the second plane and the third plane defines the height of the slat.

[0031] In some examples, a height of each slat is no less than 10 mm. Preferably, the plurality of slats comprises no fewer than five slats.

[0032] There is also provided a luminaire comprising: a light source configured to generate output light; and the light shaping element as previously disclosed, wherein the light shaping element is configured to receive the output light (also referred to as received light or received output light).

[0033] In some examples, the light source is configured to output light having a symmetric light distribution with respect to an optical axis; and the light shaping element is2024PF80510

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[0035] configured to reshape the symmetric light distribution to form an asymmetric light distribution.

[0036] This asymmetric light distribution is achieved through the differential treatment of light by the two sides of each slat. In particular, light incident on the retroreflective first side is reflected back towards the light source, e.g., for recycling or redirection. Light incident on the specular / diffuse reflective second side is redirected away from that side, maintaining illumination in light emitted in directions faced by the second side (i.e., parallel to directions towards the first side).

[0037] In preferred examples, the first side of each slat faces a same first direction and similarly, preferably the second side of each slat faces a same second direction (e.g., which second direction is opposite to the first direction). This functions to significantly reduce an amount of light by the luminaire towards the second direction, thereby providing an asymmetric light profile output from the luminaire.

[0038] This selective redirection and reflection of light results in a reduction of light intensity in the direction faced by the first side of the slats, while maintaining or possibly increasing light intensity in the direction faced by the second side. The overall effect is an asymmetric light distribution that can be tailored to specific lighting needs, such as reducing light trespass through windows or focusing illumination on particular areas of a space.

[0039] In some examples, the light source is configured to output the output light through a light exit window; and the light shaping element is positioned against or within the light exit window.

[0040] In some examples, the light exit window is substantially planar and, for each slat of the light shaping element, the first side and the second side extend substantially perpendicular to the light exit window.

[0041] These and other aspects of the invention will be apparent from and elucidated with reference to the embodiment s) described hereinafter.

[0042] BRIEF DESCRIPTION OF THE DRAWINGS

[0043] For a better understanding of the invention, and to show more clearly how it may be carried into effect, reference will now be made, by way of example only, to the accompanying drawings, in which:

[0044] Fig. 1 illustrates an existing luminaire;

[0045] Fig. 2 illustrates a luminaire with a proposed light shaping element;

[0046] Fig. 3 illustrates a slat for a proposed lighting shaping element;2024PF80510

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[0048] Fig. 4 illustrates the effect of the proposed light shaping element;

[0049] Fig. 5 illustrates the light distribution of an existing luminaire;

[0050] Fig. 6 illustrates the light distribution of a luminaire with a proposed light shaping element;

[0051] Fig. 7 illustrates the light distribution of an existing luminaire in a polar coordinate system;

[0052] Fig. 8 illustrates the light distribution of a luminaire with a proposed light shaping element in a polar co-ordinate system;

[0053] Fig. 9 provides a perspective view of a luminaire with a proposed light shaping element;

[0054] Fig. 10 provides a perspective view of another luminaire with a proposed light shaping element;

[0055] Figs. 11 and 12 illustrates a first retroreflector for use in a proposed light shaping element;

[0056] Figs. 13 and 14 illustrates a second retroreflector for use in a proposed light shaping element;

[0057] Figs. 15 A, 15B and 16 illustrate a specular reflector for use in a proposed light shaping element;

[0058] Figs. 17A, 17B and 18 illustrates a third retroreflector for use in a proposed light shaping element;

[0059] Fig. 19 illustrates an environment that employs luminaires with the proposed light shaping element; and

[0060] Fig. 20 illustrates another variant luminaire.

[0061] DETAILED DESCRIPTION OF THE EMBODIMENTS

[0062] The invention will be described with reference to the Figures.

[0063] It should be understood that the detailed description and specific examples, while indicating exemplary embodiments of the apparatus, systems and methods, are intended for purposes of illustration only and are not intended to limit the scope of the invention. These and other features, aspects, and advantages of the apparatus, systems and methods of the present invention will become better understood from the following description, appended claims, and accompanying drawings. It should be understood that the Figures are merely schematic and are not drawn to scale. It should also be understood that the2024PF80510

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[0065] same reference numerals are used throughout the Figures to indicate the same or similar parts.

[0066] The invention provides a light shaping element for shaping light emitted by a light source of a luminaire. The light shaping element comprises a plurality of slats, having a first side and a second side. The first side is configured to perform retroreflection of light received from the light source. The second side is configured to perform specular or diffusive reflection of light received from the light source.

[0067] The present disclosure proposes the concept of an add-on optical element, labelled a light shaping element, that can be mounted on or to the light emitting surface area of a light source. The light shaping element comprises multiple slats or plates that run (substantially) perpendicular to the window / wall surface. These slats have on a first side a retror effective coating / texture / structure, which sends the light back towards the light emitting surface of the luminaire, where it can be partially recycled. The second, other side of the slats are specular or (partially) diffuse reflective and redirect the light away from said other side.

[0068] The proposed light shaping element functions to define a luminaire with an asymmetric light distribution. In particular, more light is output by the luminaire in the directi on(s) that each second side of the slats face(s). Thus, control over the direction of light output by the luminaire with the proposed light shaping element can be achieved, through appropriate orientation of the second side of the slats.

[0069] One significant advantage of using retroreflection on one side of the slat or plate is improved optical efficiency whilst achieving asymmetric light distribution from the overall luminaire. For instance, if the retroreflective side was replaced with an optical absorber (like a black coating) an asymmetrical light distribution would also be achieved, but at the cost of optical efficiency. Replacing the retroreflective side with a specularly reflective side would not achieve the desired light asymmetry.

[0070] Figure 1 illustrates an existing luminaire for the sake of improved conceptual understanding. The luminaire 10 comprises a light source 15 configured to output light 16.

[0071] Suitable examples of light sources are well known in the art. For instance, the light source may comprise one or more lighting elements (e.g., one or more LED arrangements, halogen bulbs, fluorescent lamp or tubes and so on). The structure and operation of such light sources are well known, and are not detailed for the sake of conciseness.

[0072] The light source 15 may be configured to define a light exit window 18 through which light is emitted. The light exit window is preferably substantially planar, and2024PF80510

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[0074] may be defined by a surface (or aperture) through which light exits the light source and is emitted into the environment.

[0075] In particular, the light source 15 may emit light to have a substantially symmetrical and uniform distribution upon exiting the light exit window 18, e.g., having rotational symmetry about an optical axis OA that extends away from the light exit window and defines a central axis of the output light 16. However, this is not essential.

[0076] More particularly, the light source 15 may be configured to emit light having a droplet intensity shape, such as that formed by a conventional beam shaping plate.

[0077] Figure 2 illustrates a luminaire 20 comprising a proposed light shaping element 200. The luminaire, itself a proposed embodiment, also comprises the light source 15 as previously described.

[0078] The light shaping element 200 comprises a plurality of slats 210, also known as plates. The slats extend away from the light source 15. Each slat is embodied in a similar manner. As illustrated in Figure 2, the slats may extend substantially parallel to one another, but this is not essential.

[0079] The light shaping element is configured to receive the output light produced by the light source 15. The slats 210 are configured to receive at least some of the output light produced by the light source. As later described in detail, the slats are designed to reshape the received (output) light, e.g., resulting in the light output by the overall luminaire being asymmetrical (despite having a light source with a symmetrical light distribution). This is achieved through appropriate configuration of different sides of each slat.

[0080] It will be appreciated that, in practice, the light shaping element is mechanically coupled to the remainer of the luminaire, e.g., to the light source 15, and / or to a supporting element for the luminaire (e.g., a ceiling). In particular, the slats 210 of the light shaping element may be mechanically connected to each other by an outer frame 220.

[0081] In some examples, this outer frame can be mechanically secured to the supporting element of the luminaire (e.g., to one or more T-bars in a ceiling). This provides easy installation and a safe construction.

[0082] As another example, the outer frame 220 may be mechanically secured to the light source, e.g., fitted within or to the light exit window of the light source. This mechanical securing can be achieved by means of friction or through the use of dedicated securing mechanisms, such as screws, clipping mechanisms, bolts and so on.

[0083] The light shaping element 200 may be retrofittable to the light source 15, allowing for easy modification of existing lighting systems.2024PF80510

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[0085] Figure 3 provides an enlarged view of a slat 210 of the proposed light shaping element for improved contextual understanding. Each slat of the light shaping element may be embodied as hereafter described.

[0086] The slat 210 comprises a first side 310, configured to perform retroreflection of received light. In particular, the first side 310 may have a retroreflective coating, texture and / or structure configured to return light towards the light source. The returned light may be at least partially recycled and / or reflected (e.g., to be output in a different direction) by the light source.

[0087] It is emphasized that the retroreflection of received light by the first side 310 need only be in the plane(s) perpendicular to the light exit window, i.e., to redirect light towards the first light source. In some variants, the first side 310 may perform any form of reflection within a plane parallel to the light exit window (e.g., specular reflection, diffuse reflection or retroreflection).

[0088] The slat 210 also comprises a second side 320 configured to perform specular reflection and / or diffuse reflection of received light. By way of example, the second side 320 may be a mirror (i.e., a specular reflector) or diffuse reflector of light. The second side 320 functions to redirect light away from the second side, whilst still directing received light away from the light source.

[0089] It is emphasized that the specular and / or diffuse reflection of received light by the second side 320 need only be in the plane(s) parallel to the light exit window, i.e., to redirect received light away from the first light source. In some variants, the second side may perform any form of reflection within a plane parallel to the light exit window (e.g., specular reflection, diffuse reflection or retroreflection).

[0090] In particular, the second side 320 may comprise one or more specularly reflective surfaces (i.e. mirrors) and / or diffusely reflective surfaces that (in use) extend substantially perpendicular to the light exit window of the light source. This helps maintain an even distribution of light in directions faced by the second side of each slat.

[0091] Preferably, for each slat, the second side is configured to specularly reflect no less than 80% of the received light. This provides efficient reshaping of light received from the light source.

[0092] Suitable example mirrors include (e.g., polished) aluminum surfaces, plastic coated with aluminum by vapor deposition and / or specialized sheet material such as that available from Alanod ®.2024PF80510

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[0094] Other suitable specularly reflective structures for forming the second side are known to the skilled person, such as specular reflection by a dielectric material (e.g., PC, PMMA, glass) via one or more prismatic structures configured to perform total internal reflection of received light. A more detailed example of such a specularly reflective structure is provided later in this disclosure.

[0095] The proposed light shaping element provides a luminaire with a modified light distribution, compared to if the light shaping element is absent. More specifically, the proposed light shaping element contributes to the overall luminaire having an asymmetric light distribution.

[0096] In more detail, the first side of each slat functions to block light being directly emitted from the light source in a first set of directions. This light is instead returned to the light source for recycling. The second side of each slat functions to redirect light being emitted from the light source in a second set of directions to instead be emitted in a third set of directions, parallel to the first set of directions.

[0097] The overall functionality of the slats thereby reduces or attenuates the amount of light emitted in the second set of directions, whilst maintaining light emitted in the third (and therefore the first) set of directions. Thus, if the light source has a symmetrical light distribution, the slats functions to define an asymmetrical light distribution.

[0098] Put another way, more light is directed towards the direction(s) faced by the second side of each slat than towards the direction(s) faced by the first side of each slat. The retroreflectivity of each first side allows the light to be recirculated (e.g., rather than absorbed) to maintain good optical efficiency whilst modifying the shape of the light output by the light source.

[0099] By way of further explanation, if the first side of each slat was also specularly reflective, then there would be no significant effect on the overall shape of the light distribution of the luminaire. However, by performing retroreflection, the light can instead be returned to the light source recycled / reflected towards the second side of each slat.

[0100] It will be appreciated that the outsides of the outer(most) slats have no optical functionality, so they can have any color or texture to be more aesthetically attractive.

[0101] The first and second side of each slat may face away from one another. This increases a uniformity or evenness of the light intensity within the asymmetrical light distribution. In particular, this results in a more gradual change in light intensity across the asymmetrical distribution, reducing sudden or abrupt transitions that may otherwise create uneven or patchy illumination in the lit environment. To achieve a similar advantage, in some2024PF80510

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[0103] embodiments, for each slat, the first side and the second side extend substantially parallel to one another.

[0104] More specifically, in some examples, each slat 210, of the plurality of slats, lies in a first plane Pl. For each slat, the first side may be or extend substantially perpendicular to the first plane; and the second side may be or extend substantially perpendicular to the first plane.

[0105] Figure 4 conceptually illustrates the effect of the proposed light shaping element. For the purposes of Figure 4, it is assumed that the light output by the light source 15 (i.e., existing the light exit window) has a symmetrical light distribution.

[0106] In particular, the light 28 output by the overall luminaire is asymmetrical. This is a result of the specular reflection of light by the second side of each slat, which reduces an amount of light emitted in directions that the second side of each slat does not face. The retroreflection of the light from the first side of each slat functions to recycle light, which might otherwise be lost to absorption.

[0107] It will be appreciated that, in some examples, at least some of the light that is emitted by the light source is not incident upon any slat. This advantageously maintains a good illumination of an environment below the luminaire.

[0108] Referring to Figures 3 and 4, in some examples, the height h of each slat is no less than 10 mm. This provides a sufficient length of the slat to interact with light emitted by the light source to perform appropriate beam shaping.

[0109] In some examples, the height h of each slat is no greater than 200 mm, e.g., no greater than 100 mm. The greater the height of the slat, the more light is blocked by the slat. A maximum height h of 200 mm (or 100 mm) provides a good compromise between achieving beam shaping and avoiding or reducing a blocking of light.

[0110] In this context, the height of the slat is a dimension of the slat in a direction perpendicular to the light exit window. More particularly, for each slat: the first side and the second side may extend from a second plane P2 to a third plane P3, wherein the third plane is parallel to the second plane. The distance between the second plane and the third plane defines the height of the slat.

[0111] In some examples, the spacing d between each of the plurality of slats is no less than 10 mm. The spacing is a distance between adjacent slats, e.g., a distance within the first plane Pl previously disclosed.

[0112] The plurality of slats may be evenly or uniformly spaced, which is preferred for a light source having a symmetrical and uniform light distribution of light output2024PF80510

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[0114] therefrom. However, the proposed light shaping element may also be applied to luminaires with a non-uniform light output to achieve a similar effect, provided that each slat is symmetrically positioned with respect to each individual lighting element in the luminaire.

[0115] Preferably, the thickness of each slat (e.g., as measured in the first plane Pl) is small, to minimize or reduce optical losses. In preferred examples, the thickness t of each slat is no greater than a fifth (or more preferably a tenth) of the spacing d between each of the plurality of slats.

[0116] For the avoidance of doubt, it is noted that the size of the slats in the Figures is purely illustrative, and that (in practice) the relative thickness of the slats may be substantially smaller.

[0117] Figures 5, 6, 7 and 8 illustrate the results of a simulation of the proposed light shaping element for a simulated luminaire.

[0118] For the purposes of the simulation, the light source of the luminaire is modelled as a flat 60x60 cm2simulated light source with a luminous intensity distribution that is common for indoor commercial lighting panels, specifically: a typical droplet intensity shape that is formed by a conventional beam shaping plate.

[0119] For the purposes of this simulation, it is assumed that the first side of each slat comprises a near-ideal retroreflector and the second side of each slat is a near-ideal specular reflector. The plurality of slats are simulated as comprising 5 parallel slats that extend perpendicularly to a flat 60x60 cm2simulated light source. The slats are spaced apart by 150 mm and each have a height (e.g., in a direction perpendicular to that flat light source) of 150 mm.

[0120] The effect of the proposed light shaping element on the intensity distribution of the luminaire is shown in Figures 5 and 6.

[0121] Figure 5 illustrates 3 intensity slices 510, 520, 530 for light output by the flat simulated light source with no light shaping element. The intensity slices lie perpendicular to the flat light source and are angled with respect to one another, with a 45° angular separation (i.e., one intensity slice lies at 0°, a second at 45° and a third at 90°). As the light source provides a near-symmetrical light output, the intensity slices overlap one another and are difficult to distinguish from one another.

[0122] Figure 6 illustrates the same 3 intensity slices 610, 620, 630 for light output by the flat simulated light source with the proposed light shape element. A first intensity slice 610 lies parallel to each slat. A second intensity slice 620 lies at 45° to each slat. A third intensity slice 630 lies perpendicularly to each slat.2024PF80510

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[0124] As demonstrated in Figure 6, the presence of the proposed light shaping element results in an intensity cut off on one side of the non-parallel intensity slices. This is a result of the specular reflection by the second side of each slat. There is also some unintentional / undesirable intensity cut-off at the other side, caused by screening of specularly reflected light by neighboring slats.

[0125] Figures 7 and 8 illustrate the effect of the proposed light shaping element in a polar coordinate space.

[0126] Figure 7 illustrates 2 intensity slices 710, 720, in the polar coordinate space, for light output by the flat simulated light source with no light shaping element. The intensity slices lie perpendicular to the flat light source and to one another. As the light source provides a near-symmetrical light output, the intensity slices overlap one another and are difficult to distinguish from one another.

[0127] It is noted that the light emitted by the exemplary light source takes a droplet intensity shape, previously mentioned.

[0128] Figure 8 illustrates the same two intensity slices, in the polar coordinate space, for light output by the flat simulated light source with the light shaping element. The intensity slices lie perpendicular to the flat light source and to one another. A first intensity slice 810 lies parallel to each slat and a second intensity slice 820 lies perpendicular to each slat. As demonstrated in Figure 8, the presence of the proposed light shaping element results in an intensity cut off on one side of the intensity slice perpendicular to each slat.

[0129] To estimate the effectiveness of the louvers in the application, the above simulated intensity distribution is applied in a Dialux simulation of an open plan office with windows on one side. Each luminaire next to the windows includes the proposed light shaping element. The other luminaires have the known symmetric MLO beams. For the same lighting conditions in the office space, it has been identified that the spill light via the window(s) is reduced by 45% and that the window-side luminaires may be dimmed down by 13%, yielding an overall energy saving of 4% in this office.

[0130] It is noted that the height of each slat and the spacing(s) are merely exemplary. The effect of the proposed slats will be approximately the same if the aspect ratio (i.e., the ratio of height: spacing) is maintained.

[0131] More particularly, the spacing to height ratio of the slats determines the degree of asymmetry of the light emitted by the luminaire. A lower ratio gives more asymmetry, resulting in less spill light being emitted from one side of the luminaire. However, due to more interaction with the light, the efficiency of the modified luminaire (i.e., the luminaire2024PF80510

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[0133] with the light shaping element) will correspondingly drop. A smaller spacing to height ratio will thereby reduce the absorption by these louvres.

[0134] In preferred examples, the height of each slat is between 0.8 and 1.2 times the spacing between each of the plurality of slats. This provides a good ratio for achieving an asymmetrical light distribution of a luminaire with even or consistent luminous flux, particularly for a luminaire having a light source with a symmetrical light distribution.

[0135] In preferred examples, the first side of each slat faces a same first direction. Similarly, the second side of each slat may face a same second direction (e.g., which second direction is opposite to the first direction). This functions to significantly reduce an amount of light by the luminaire towards the second direction, thereby providing an asymmetric light profile output from the luminaire.

[0136] In other words, this approach results in less light being emitted out of one side of the luminaire.

[0137] Figure 9 provides a perspective view of a proposed luminaire 20. In this example, each slat 210 is a cuboidal slat that extend parallel to one another wherein the first side 310 of each slat 210 faces a same first direction, and the second side 320 of each slat 210 faces a same second direction, wherein the second direction is opposite to the first direction.

[0138] Figure 10 illustrates a perspective view of a variant luminaire 20B comprising a variant light shaping element. In this approach, each slat has a curved profile. The slats remain parallel to one another as the curve of the slats are parallel to one another. This demonstrates how alternative shaping of the light distribution of light emitted by the luminaire is achievable through alternative shaped slats.

[0139] Such shaping may, for instance, be particularly advantageous if employed in a luminaire positioned near a corner or curved wall.

[0140] Figures 11 and 12 illustrate an example of a suitable retroreflector 1100 as which each first side may be embodied. In other words, the first side of each slat may comprise the retroreflector 1100. Figure 11 provides a side view and Figure 12 provides a perspective view of a portion of the retroreflector.

[0141] The retroreflector 1100 is here created by a sawtooth shape with the teeth 1101 of the sawtooth shape (which form triangular prisms) being designed to reflect the light back where it originated. In particular, the surface of each tooth that faces the light exit window of the light source may be or comprise a specular reflective surface 1105. In this way, the sawtooth shape provides a pattern of specularly reflective mirrors that achieves the function of retroreflection.2024PF80510

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[0143] The teeth or triangular prisms extend parallel to the light exit window 18 of the light source.

[0144] The sawtooth shape functions to effectively increase the angle of incidence between any light rays incident upon the retroreflector towards the perpendicular. It is recognized that the performance of retroreflectors is improved at light angles of incidence at or close to perpendicular to the (retroreflecting) surface.

[0145] As previously mentioned, for improved retrofl ection, it is preferred that a light incident upon the teeth 1101 of the retroreflector is perpendicular to the incident surface.

[0146] It has been recognized that, in a scenario in which the retroreflector is a flat surface lying perpendicular to the light exit window of the light source, a peak intensity of light emitted by the light source will be incident at an angle of about 130° to this flat surface.

[0147] Accordingly, in some embodiments, it is preferred to configure the angle a of the specularly reflective surface of each tooth 1101, with respect to the perpendicular to the light exit housing (or the second side 320 of the slat) to be between 40° and 60° (e.g., 50° ± 5°, to account for minor errors in manufacturing).

[0148] Looking at figure 3, most light hits the surface at an angle of 130 degrees, where 180 degrees is perpendicular angle of incidence.

[0149] Figures 13 and 14 illustrates another example of a suitable retroreflector 1300, by each first side of the slats may be embodied. In other words, the first side of each slat may comprise the retroreflector 1300. Figure 13 provides a side view and Figure 14 provides a perspective view of a portion of the retroreflector.

[0150] The retroreflector is here created by a triangular ridge shape, comprising a series of triangular prisms forming teeth 1301 for performing retroreflection. The teeth or triangular prisms extend parallel to the light exit window 18 of the light source. At least the surface 1305 of each tooth that faces the light exit window of the light source may be a specularly reflective surface. This provides another form of pattern that achieves the function of retroreflection through appropriate positioning of specularly reflective surfaces.

[0151] In some embodiments, it is preferred to configure the angle a of the specularly reflective surface 1305 of each tooth 1301, with respect to the perpendicular to the light exit housing (or the second side 320 of the slat) to be between 40° and 60° (e.g., 50° ± 5°, to account for minor errors in manufacturing). This improves the retroreflection of the retroreflector.2024PF80510

[0152] 15

[0153] In some examples, the angle o of the surface 1306 of each tooth that faces away from the light exit window (non-facing surface 1306) is between 30° and 50° (e.g., 40° ± 5°, to account for minor errors in manufacturing).

[0154] Accordingly, the angle between the specularly reflective surface 1305 and the non-facing surface 1306 of each tooth 1301 may be around 90°, but this is not essential.

[0155] Preferably, the angle a is chosen such that the incident light is on average perpendicular to the specularly reflective surface. The angle sigma is preferably chosen such that the non-facing surface 1306 is in the shadow, e.g., such that no or negligible light emitted by the light source hits this surface.

[0156] When the sum of a+c =90°, there is advantageously an increased probability that the non-facing surface will lie parallel to the incoming light, i.e. any specular reflected light will still be more or less within the incoming beam. This improves the efficiency of the retroreflection and reduces a risk of undesirable light scatting. Taking a+c<90° increases a risk of scattering or non-ideal light reflection, because light that hits the non-facing surface may (undesirably) reflect in the wrong direction. A value of a+c>90° reduces a risk of light scattering (as less light will hit the non-facing surface). One drawback of this arrangement is that the prisms become more sharp and therefore more difficult / expensive to make.

[0157] It is noted that the retroreflector 1100 (Figures 11 and 12) is effectively the retroreflector 1300 (Figure 13) having an angle c of around 90° and an angle a of between 40° and 60° (e.g., 50° ± 5°, to account for minor errors in manufacturing).

[0158] It is noted that the angle of peak light incident upon the slats is dependent upon the distance (along the slat) from the light exit window of the light source. To take advantage of this, the value(s) of at least angle a (for each tooth) may have a position or distance dependent value. For instance, the value of the angle a may increase with increased distance from the light exit window. This improves the retro-reflectivity of the retroreflector.

[0159] If each slat is embodied to comprise a first side having a retroreflective surface formed by a pattern or arrangement of specularly reflective surfaces that achieves the function of retroreflection and the second side is configured to perform specular reflection of received light, then each slat can be produced by an extrusion process (e.g., a plastic extrusion process) followed by a coating with reflective material. This coating may, for instance, be performed by deposition of reflective material (e.g., aluminum) by a vacuum vapor deposition process or similar procedure. One advantage of this approach is that the underlying structure or material of the slat (e.g., plastic) itself has no direct interaction with2024PF80510

[0160] 16

[0161] light, it can be of low quality and any color, for example from a mixture of recycled waste plastic.

[0162] Aluminum coatings have a typical reflection of about 85%. Assuming a slat spacing-to-height ratio of 1 and a reflection of the luminaire of 90% of the retroreflected light from the slat, it is possible to achieve (with the proposed light shaping element) an optical efficiency of about 86% compared to that the bare light source (i.e., an unmodified luminaire).

[0163] Figures 15 A, 15B and 16 illustrates an example of a suitable specular reflector 1500. The second side of each slat may comprise this specular reflector. Figure 15A provides a top-down view (parallel to the light exit window and first plane), Figure 15B provides a side or cross-sectional view (perpendicular to the light exit window and first plane) and Figure 16 provides a perspective view.

[0164] In particular, to reduce absorption losses caused by metallic reflectors, the specular reflector 1500 may be formed by a transparent / translucent sheet having (e.g., triangular) prisms 1501 oriented vertically relative to the light exit window 18. In particular, the top angle 0 of each prism 1501 may be around 90 degrees facing away from the incident light.

[0165] This provides a specular reflector that makes use of total internal reflection to perform specular reflection in (at least) the plane perpendicular to the light exit window.

[0166] Examples of suitable prism foils are well known, e.g., for use in backlighting of LCD screens or the like, and are widely available with the mentioned top angles.

[0167] The reflection coefficient of this form of specular reflector is very high, because it relies upon total internal reflection. The remaining absorption loss is by the absorption of the foil, which is typically made of PET.

[0168] Another high-efficiency specular reflector is a dielectric mirror made of a multilayer foil with alternating layers with a different refractive index. One example product is the ESR (enhanced spectral reflector) developed by 3M, with a reflectivity of 98.5%. Using such a dielectric mirror for the second side of each slat thereby increases the overall efficiency of the luminaire.

[0169] Figures 17A, 17B and 18 illustrate another example of a suitable retroreflector 1700, by each first side of the slats may be embodied. Figure 17A provides a side view (perpendicular to the light exit window and first plane), Figure 17B provides a top-down view (perpendicular to the light exit window and first plane) and Figure 18 provides a perspective view. In this variant, the retroreflector relies upon the principle of total internal2024PF80510

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[0171] reflection to perform retroreflection, at least in the plane perpendicular to the light exit window.

[0172] The retroreflector is again created by a triangular ridge shape, comprising a series of triangular prisms forming 1701 for performing retroreflection. The teeth or triangular prisms extend parallel to the light exit window 18 of the light source, but face away from the direction(s) in which light is emitted from the light exit window.

[0173] The retroreflector may be formed from a transparent or translucent material, such as a dielectric (e.g., PET, PC, PMMA, glass) and the values for the angles a and c may be selected or designed such that the surface 1305 that receives light performs retroreflection of at least a portion of received light.

[0174] Each tooth 1701 comprise a first surface that faces toward the light exit window 18 and a second surface that faces away from the light exit window 18. Each first surface makes a non-zero angle with respect to the light exit window and each second surface makes another non-zero angle p with respect to the light exit window.

[0175] The value of angle may be around 15° (±5°) and the value of angle p may be around 75° (±5°).

[0176] This variant of the retroreflector design exploits the principle of total internal reflection to achieve retroreflection, rather than relying on specular reflection from metallic surfaces. It is well known that total internal reflection occurs when light traveling through a medium with a higher refractive index encounters an interface with a medium of lower refractive index at an angle greater than the critical angle. This phenomenon results in complete reflection of the light back into the original medium without any loss of energy.

[0177] In the illustrated example, the teeth of the retroreflector function as the medium with a higher refractive index, the interface is the first / second surface of the teeth and another medium (e.g., air) functions as the medium with a lower refractive index. Light transmits into the teeth, and undergoes total internal reflection as the interface formed by the first / second surface(s), providing a highly efficient retroreflecting mechanism.

[0178] Figure 19 illustrates an environment 1900 in which proposed embodiments may be employed.

[0179] The environment takes the form of a room comprising a wall with a plurality of windows 1911, 1912, 1913. The room also comprises a plurality of luminaires 1921, 1922, 1923, 1924, which are positioned in / on the ceiling of the room.2024PF80510

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[0181] A first subset 1931 of the luminaires are positioned more proximate to the windows than a second subset 1932 of the luminaires. If each luminaire were to emit light having a symmetrical distribution, then a substantial amount of light would be emitted The present disclosure provides a mechanism for reconfiguring the light distribution 1991 of some (or all) of the luminaires to be asymmetrical. In particular, at least the first subset of luminaires 1931 are each fitted with a proposed light shaping element. The second first side of each light shaping element is aligned to face the windows and the second side of each light shaping element is aligned to face away from the windows. This reduces the light intensity of light emitted by these luminaires towards the windows (as illustrated). This thereby reduces light leakage / wastage from the environment 1900 out of the windows 1911, 1912, 1913.

[0182] Moreover, in some examples, the intensity of light emitted by the light source of the first set of luminaires can be reduced whilst still maintaining a same overall luminous flux within the room. This is because less light is lost out of the windows. Thus, efficiency of the overall lighting system is improved.

[0183] Figure 20 illustrates a further variant of a luminaire 20C, which may be embodied as any previously disclosed luminaire with the additional component(s) hereafter described.

[0184] In this embodiment, the luminaire 20C further comprises a sensor or sensing arrangement 2010 configured to monitor a monitoring region 2015 of the environment.

[0185] The sensor is positioned or arranged, in conjunction with the light shaping element, such that the monitoring region does not intersect with the light shaping element. This improves the accuracy of the sensing performed by the sensor.

[0186] In some examples, the sensor 2010 is configured such that the direction of the monitoring region is away from the second side of each slat. This exploits the recognition that the first side of each slat is more likely to be positioned to face an edge of the room (e.g., the windows). Thus, the sensor is able to get a more open view of the room, and avoid monitoring edges of the room. More efficient monitoring is thereby achieved.

[0187] In some examples, the sensor 2010 is positioned on a side of the luminaire faced by the first side of each slat. This effectively positions the sensor towards a side of lower light illumination, e.g., where an edge of the environment is expected to be. This provides a more complete view of the environment.

[0188] The sensor may be any appropriate sensor for use with a luminaire, such as an occupancy sensor, an ambient light sensor, a movement sensor and so on.2024PF80510

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[0190] It will be appreciated that herein described luminaire may comprise control circuitry, driving circuitry, communication circuitry, sensing arrangements, one or more power connectors (for connecting the light source to a power source) and / or any other suitable electronic component. These are common components and / or elements of a luminaire, and are not described in detail for the sake of conciseness and because their operation or function is immaterial to the underlying concept of the present disclosure.

[0191] Variations to the disclosed embodiments can be understood and effected by those skilled in the art 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 measures cannot be used to advantage. If the term "adapted to" is used in the claims or description, it is noted the term "adapted to" is intended to be equivalent to the term "configured to". If the term "arrangement" is used in the claims or description, it is noted the term "arrangement" is intended to be equivalent to the term "system", and vice versa.

[0192] Any reference signs in the claims should not be construed as limiting the scope.

Claims

2024PF8051020CLAIMS:

1. A luminaire (20, 20B, 20C) comprising:a light source (15) configured to generate output light (16); and a light shaping element (200), wherein the light shaping element is configured to receive the output light,the light shaping element comprising:a plurality of slats (210), wherein each slat comprises a first side (310), configured to perform retroreflection of received light, and a second side (320) configured to perform specular reflection and / or diffuse reflection of received light.

2. The luminaire (20, 20B, 20C) of claim 1, wherein the plurality of slats extend substantially parallel to one another.

3. The luminaire (20, 20B, 20C) of claim 1 or 2, wherein, for each slat, the first side and the second side face away from one another.

4. The luminaire (20, 20B, 20C) of any one of claims 1 to 3, wherein, for each slat, the first side and the second side extend substantially parallel to one another.

5. The luminaire (20, 20B, 20C) of any one of claims 1 to 4, wherein:each slat, of the plurality of slats, lies in a first plane (Pl); and for each slat:the first side is substantially perpendicular to the first plane; and the second side is substantially perpendicular to the first plane.

6. The luminaire (20, 20B, 20C) of any one of claims 1 to 5, wherein, for each slat, the second side is configured to specularly reflect no less than 80% of the received light.

7. The luminaire (20, 20B, 20C) of any one of claims 1 to 6, wherein a spacing between each of the plurality of slats is no less than 10 mm.2024PF80510218. The luminaire (20, 20B, 20C) of any one of claims 1 to 7, wherein a height of each slat is between 0.8 and 1.2 times the spacing between each of the plurality of slats.

9. The luminaire (20, 20B, 20C) of claim 8, wherein for each slat:the first side and the second side extends from a second plane (P2) to a third plane (P3), wherein the third plane is parallel to the second plane; andthe distance between the second plane and the third plane defines the height of the slat.

10. The luminaire (20, 20B, 20C) of any one of claims 1 to 9, wherein the first side of each slat faces a same first direction and the second side of each slat faces a same second direction.

11. The luminaire (20, 20B, 20C) of any one of claims 1 to 10, wherein the second side comprises reflective structures of a dielectric material configured to perform total internal reflection of received light.

12. The luminaire (20, 20B, 20C) of claim 11, wherein the reflective structures of dielectric material comprise prismatic structures of one or more of PC, PMMA, and glass .

13. The luminaire (20, 20B, 20C) of any one of claims 1 to 12, wherein:the light source is configured to output light having a symmetric light distribution with respect to an optical axis; andthe light shaping element is configured to reshape the symmetric light distribution to form an asymmetric light distribution.

14. The luminaire (20, 20B, 20C) of any one of claims 1 to 13, wherein:the light source is configured to output the output light through a light exit window (18); andthe light shaping element (200) is positioned against or within the light exit window.2024PF805102215. The luminaire (20, 20B, 20C) of claim 14, wherein the light exit window (18) is substantially planar and, for each slat of the light shaping element, the first side and the second side extend substantially perpendicular to the light exit window.

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