Luminaire and lighting arrangement

A luminaire (100) comprising a chamber (110) comprising at least one light exit surface (112); an axial carrier (120) mounted in said chamber (110) on an axis (105), said axial carrier (120) carrying a plurality of solid state lighting elements (122) and being surrounded by the light exit surface (112); and a body (130) mounted around said axial carrier (120), said body (130) comprising a plurality of radially extending optical cells (140) each comprising an inlet (142) facing said axial carrier (120); an outlet (144) facing the light exit surface (112); and a plurality of reflective surfaces (146, 148) extending from said inlet (142) to said outlet (144); wherein at least one of the axial carrier (120) and the body (130) are rotatably mounted relative to said axis (105) and wherein the body (130) can be rotated relative to the axcial carrier (120) or vice versa.

CROSS REFERENCE TO PRIOR APPLICATIONS

This application is the U.S. National Phase application under 35 U.S.C. § 371 of International Application No. PCT/2015/052459, filed on Feb. 6, 2015, which claims the benefit of European Patent Application No. 14168762.4, filed on May 19, 2014, and Chinese Patent Application No. PCT/CN2014/000165, filed on Feb. 19, 2014. These applications are hereby incorporated by reference herein.

FIELD OF THE INVENTION

The present invention relates to a luminaire, in particular to a luminaire for illuminating an outdoor space in an urban environment such as a post-top luminaire.

The present invention further relates to a lighting arrangement including such a luminaire.

BACKGROUND OF THE INVENTION

Urban landscape lighting such as road lighting, street lighting, square lighting and so on is commonplace in many urban areas to provide illumination of such areas, which for instance is important for safety and security reasons. Many types of luminaires are used for urban landscape lighting, such as for instance post-top lighting, column lighting, bollard lighting and so on.

The functional lighting provided by such luminaries typically has to meet specific regulations in order to ensure that appropriate lighting levels are provided in a safe manner, e.g. by ensuring that glare levels produced by the luminaire are kept below defined thresholds.

Consequently, the design of such luminaires must be suitable to meet the aforementioned specific regulations. At the same time, because such luminaires are placed in urban environments, the appearance of such luminaires is important, for instance because the luminaire preferably has to blend into the environment in which it is placed. In other words, the luminaire preferably should be decorative whilst at the same time providing the required functional lighting in order to ensure that the luminaire is considered a welcome addition to the urban environment in which it is placed.

It has been recognized that the appearance of the luminaire in an urban landscape can be controlled not only by the appearance of the luminaire itself but also by shaping the luminous output of the luminaire. It is for instance is known to adjust the lighting pattern produced by a luminaire upon detection of a person in the vicinity of the luminaire. However, such dynamic variations of the lighting pattern may be beneficial for functional reasons but may not be considered aesthetically pleasing. In addition, the cost of such luminaires is significantly increased due to the requirement of motion detection sensors or the like and appropriate controllers responsive to such sensors that control the luminous output of the luminaire.

It is known per se to provide a lighting fixture that can create an aesthetically pleasing effect such as a kaleidoscopic effect. For instance, U.S. Pat. No. 5,711,598 A discloses a lamp device that includes a light emitting unit for emitting a light beam, a light filtering unit, first and second focusing lenses, and a total internal reflection unit. The light filtering unit has a rotatable glass-holding frame and a pair of flat glasses which are fixed opposedly to the glass-holding frame. A space is formed between the flat glasses to receive damping fluid in which a plurality of colored glass fragments are dispersed. The light filtering unit is positioned adjacent the light emitting unit so that the light beam from the light emitting unit can pass through the flat glasses and the colored glass fragments. The first and second focusing lenses are spaced opposedly from one another. The first focusing lens is positioned adjacent the light filtering unit. The total internal reflection unit is mounted between the first and second focusing lenses so that the light beam from the light filtering unit can be emitted through the first focusing lens, reflected by the total internal reflection unit, and emitted from the second focusing lens, thereby producing a kaleidoscopic light output.

However, such an arrangement is relatively complex and not particularly suitable in an urban lighting environment, for instance if a luminous output may have to be generated in a particular direction to meet functional lighting requirements.

EP2273185A1 discloses a light element with a light diverter which has a elongate carrier element, which is arranged along its peripheral around a longitudinal axis for supporting circuit carriers for light emitting diodes. The elongate carrier element has surface sections along its peripheral around the longitudinal axis. The light diverter has a plurality of segments. However, the light diverter is directly mounted to the elongate carrier element.

SUMMARY OF THE INVENTION

The present invention seeks to provide a luminaire that can create a dynamic aesthetic appearance and that optionally is suitable for use in an urban environment.

The present invention further seeks to provide a lighting arrangement including such a luminaire.

According to an aspect, there is provided a luminaire comprising a chamber comprising at least one light exit surface, an axial carrier mounted in said chamber on an axis, said axial carrier carrying a plurality of solid state lighting elements and being surrounded by the at least one light exit surface; and a body mounted around said axial carrier, said body comprising a plurality of radially extending optical cells each comprising an inlet facing said axial carrier, an outlet facing the at least one light exit surface and a plurality of reflective surfaces extending from said inlet to said outlet, wherein at least one of the axial carrier and the body are rotatably mounted relative to said axis.

By providing a luminaire that includes an axial arrangement of SSL elements and a body comprising a plurality of optical cells for reflecting the luminous output of the SSL elements wherein the body can be rotated relative to the axial carrier or vice versa, a dynamic kaleidoscopic effect can be generated in a relatively simple manner that can improve the appearance of the luminaire such as a post-top luminaire.

The optical cells may be arranged in at least one array, wherein the inlet of each optical cell is smaller than its outlet. The provision of such wedge-shaped optical cells in an array at least partially surrounding the axial carrier is a particularly suitable arrangement for providing such a kaleidoscopic effect.

In particular, the inlets may be dimensioned such that each inlet faces a subset of said plurality of said solid state lighting elements, said subset comprising at least two solid state lighting elements. By mixing the luminous output of multiple SSL elements in each optical cell, more complex kaleidoscopic effects may be generated by the luminaire. To this end, each optical cell may radially extend over a distance such that the plurality of reflective surfaces reflects incident light from said subset multiple times between said inlet and said outlet in order to establish effective superposition of the luminous output or images of the multiple SSL elements of said subset.

In an embodiment, the body comprises a plurality of said arrays in a stack to facilitate the generation of a particularly elaborate kaleidoscopic effect.

Each array may comprise N optical cells, N being a positive integer of at least 12, wherein each of said N optical cells comprises a first reflective side wall radially extending from the inlet to the outlet in a first direction; and a second reflective side wall radially extending from the inlet to the outlet in a second direction, wherein an angle between the first direction and the second direction is 360°/N. By selecting an angle between the first direction and the second direction of no more than 30°, it is ensured that each optical cell reflects the incident light of the one or more SSL elements multiple times, thereby providing the desired kaleidoscopic effect. Preferably, N is at least 24.

In an embodiment, at least some of the outlets comprise a diffusive cover. This allows for the kaleidoscopic effect to be projected onto the diffusive cover such that the kaleidoscopic effect can be observed when looking at the luminaire, whereas light passing through the diffusive cover and exiting the luminaire through the at least one light exit surface is diffused, such that a substantially homogeneous luminous output may be generated outside the luminaire. This is particularly relevant if the luminaire is a post-top luminaire for use in an urban environment, where the luminaire may be required to generate a functional luminous distribution that has to meet certain requirements.

In an embodiment, the plurality of reflective surfaces includes an upper reflective surface and a lower reflective surface that are angled downwardly in the direction from the inlet to the outlet of said optical cell. This ensures that the light generated by the SSL elements is angled downwardly in normal use of the luminaire, which for instance ensures that the luminaire may be used as a post-top luminaire.

The upper reflective surface and the lower reflective surface may be angled in a range from 15-60° relative to a plane normal to said axis to redirect the luminous output of the SSL elements in an appropriate direction.

The luminaire may further comprise an electromotor coupled to said body or axial carrier for rotating said body or axial carrier relative to said axis.

In an embodiment, the body is rotatable relative to the axial carrier, the luminaire further comprising a pair of annular bearings affixing the body to the axial carrier. This ensures that the body is securely mounted and allowed to freely rotate around the axial carrier.

The plurality of solid state lighting elements may comprise solid state lighting elements emitting different colours, wherein the respective inlets of different optical cells face solid state lighting elements emitting different colours. This for instance facilitates the generation of different colour patterns by different optical cells, which can enhance the kaleidoscopic effect created by the luminaire.

The SSL elements may be arranged on the axial carrier in any suitable pattern. A particularly suitable pattern is a linear pattern of said solid state lighting elements, wherein each line of said linear pattern extends parallel to said axis.

According to a further aspect, there is provided a lighting arrangement comprising the luminaire according to one of the aforementioned embodiments and a mounting post, wherein the luminaire is mounted on said mounting post. Such a lighting arrangement may for instance be used in an urban environment to create an aesthetically pleasing lighting arrangement that also may be capable to generate a required functional lighting pattern.

DETAILED DESCRIPTION OF THE EMBODIMENTS

FIG. 1schematically depicts a top view of an aspect of a luminaire100according to an embodiment of the present invention, whereasFIG. 2schematically depicts a cross-section of the luminaire100shown inFIG. 1. The luminaire100comprises a chamber110that is delimited by at least one light exit surface112. The number of light exit surfaces112is typically determined by the shape of the luminaire100; inFIG. 1the chamber110is delimited by four light exit surfaces112, i.e. the luminaire100has four sides. However, it should be understood that this is by way of non-limiting example only and that the luminaire100may have any suitable number of light exit surfaces112; e.g. a single light exit surface112in case of a cylindrical or frustoconical luminaire100, three light exit surfaces112in case of a triangular luminaire100, four or more light exit surfaces112in case of a more complex polyhedral luminaire100and so on. The light exit surfaces112may be made of any suitable material, such as glass or a suitable optical grade polymer such as polycarbonate (PC), polyethylene terephthalate (PET), poly(methyl methacrylate) (PMMA) and so on. In an embodiment, the light exit surfaces112are optically transmissive, e.g. are transparent, for instance having a transparency of more than 80% or even more than 90% if it is desirable that the multiple images of the SSL elements122generated by the internals of the chamber110are clearly visible from outside the luminaire100.

The chamber110houses an axial carrier120, which axial carrier120carries a plurality of solid state lighting (SSL) elements122. The SSL elements122may be arranged in any suitable pattern on the axial carrier120. In an embodiment, the axial carrier120carries a plurality of SSL elements122arranged in linear patterns, i.e. a plurality of lines of SSL elements122, with each line extending in parallel with a central axis105of the luminaire100. The axial carrier120typically is mounted on the central axis105. The SSL elements122may be light emitting diodes (LEDs). Any suitable LED, such as a LED having an organic or inorganic semiconductor layer, may be used as an SSL element122.

As will be explained in more detail later, the axial carrier120may carry SSL elements122that create respective luminous outputs of different color. The axial carrier120may be made of any suitable material, such as a thermally conductive material such that the axial carrier120can also act as a heat sink for the SSL elements122. For instance, the axial carrier120may be made of a suitable metal such as aluminium although other suitable materials will be immediately apparent to the person skilled in the art, such as other metals, metal alloys, e.g. aluminium alloys, ceramic materials, and so on.

The luminaire100further includes a body130mounted around the axial carrier120. The body130comprises a plurality of optical cells140each having an opening acting as an inlet142that faces the axial carrier120and the SSL elements122mounted thereon and an opening acting as an outlet144that faces the at least one light exit surface112of the luminaire100. Each optical cell140comprises a first pair of reflective surfaces146and a second pair of reflective surfaces148each extending between the inlet142and the outlet144of the optical cell140, wherein the first pair of reflective surfaces146defines the side surfaces of each optical cell140and the second pair of reflective surfaces148defines the top and bottom surface of each optical cell140. The body130is arranged to create a kaleidoscopic effect by replicating the image or luminous distribution produced by the SSL elements122multiple times and to direct the created kaleidoscopic effect towards a target area.

The body130may be made of a reflective material such that the reflective surfaces146and148form an integral part of the body130. Alternatively, the body130may be made of any other suitable material, e.g. a suitable plastic, wherein a reflective film covers the inner walls of each of the optical cells140in order to define the respective reflective surfaces146and148. A non-limiting example of a suitable reflective material is the MIRO product family provided by Alanod GmbH and Co. KG. Such a reflective material has a reflectivity in excess of 95% such that the majority of light generated by the SSL elements122that enters an optical cell140is produced as luminous output by the optical cell140despite the optical cell140reflecting the incident light several times on the reflective surfaces146,148to achieve the desired kaleidoscopic effect. Other suitable reflective films are known per se and will be apparent to the skilled person.

Each optical cell140radially extends from the axial carrier120towards the at least one light exit surface112, wherein a plurality of optical cells140may combine to form an annular array of optical cells140. Consequently, each optical cell140may have a wedge shape, i.e. taper outwardly in the direction of the at least one light exit surface112, such that the inlet142of each optical cell140is smaller than its outlet144.

In a particularly advantageous embodiment, the reflective side surfaces146of each cell in such an array are placed under an angle α relative to each other, wherein the angle α is chosen such that incident light originating from one or more of the SSL elements122entering an optical cell through its inlet142is reflected multiple times between the various reflective surfaces146,148of the optical cell140before the light exits the optical cell140through its outlet144. In other words, a first one of the reflective surfaces146extends from the inlet142to an outlet144in a first direction, whereas the other one of the reflective surfaces146extends from the inlet142to an outlet144in a second direction, with α being the angle between the first direction and the second direction. This ensures that the incident image originating from one or more of the SSL elements122is replicated and intermixed several times, thereby creating the desired kaleidoscopic effect.

Preferably, α≦30°. More preferably, α≦15°. In other words, for a body130comprising at least one array of N optical cells140, wherein N is a positive integer, N≧12 or more preferably N≧24 as the angle α is defined as 360°/N for an (annular) array comprising N identical optical cells140.

The body130may comprise a plurality of such arrays of optical cells140, which arrays may be stacked along the central axis105as shown inFIG. 2. The number of such arrays is not particularly critical and it suffices to say that the body130may comprise any suitable number of arrays of optical cells140in such a stack.

The body130may be rotatably mounted relative to the axial carrier120such that the body130can spin around the axial carrier120as shown by the arrows inFIG. 1. To this end, the body130may be mounted in any suitable manner inside the chamber110. For instance, the body130may be mounted to the axial carrier120using one or more ball bearings150such that the axial carrier120supports the body130whilst the body130can freely rotate around the axial carrier120, thereby creating a dynamic kaleidoscopic effect due to the fact that the orientation of the optical cells140relative to the SSL elements122changes over time, thereby changing the kaleidoscopic pattern generated by the optical cells140. It should be understood that the particular mounting arrangement shown inFIG. 1is by way of non-limiting example only and that the body130may be rotatably mounted inside the chamber110in any suitable manner. The luminaire100may further comprise an electromotor (not shown) for driving the rotation of the body130. As will be appreciated by the skilled person, the electromotor may be coupled to the body130in any suitable manner. As such coupling mechanisms are well-known per se, they will not be disclosed in further detail for the sake of brevity only.

Moreover, it should be realized that it is equally feasible to fixate the body130in the chamber110and provide a rotatable axial body120instead, which rotates around the central axis105in order to change the orientation of the SSL elements122relative to the optical cells140of the body130by way of rotation. In yet another embodiment, both the axial body120and the body130may be independently rotatable around the central axis105to provide the aforementioned dynamic kaleidoscopic effect.

In an embodiment, the luminaire100is a post-top luminaire for use in an urban environment, e.g. as a street lamp or the like. In such an embodiment, it may be desirable that the luminous output of the SSL elements122is redirected in a downward direction by the optical cells140in order to provide a luminous distribution in a ground-level area around the post-top luminaire. To this end, the second pair of reflective surfaces148of the optical cells140may be angled under an angle θ relative to a virtual plane115that is normal (i.e. oriented perpendicularly) to the central axis105of the luminaire100. In an embodiment, the angle θ may be chosen in a range of 15-60° in order to achieve a desired redirection of the luminous output produced by the SSL elements122.

In at least some embodiments, at least some of the outlets144may be covered by a diffusive cover such as a diffusive film (not shown) such that the kaleidoscopic effect is generated by the corresponding optical cell140on the diffusive cover. This is for instance advantageous in embodiments where the luminaire100has to produce functional lighting in addition to the desired kaleidoscopic aesthetic effect, for instance where the luminaire100is used as a post-top luminaire. The diffusive cover, e.g. the diffusive film, ensures that the light that exits the respective outlets144through the diffuser is diffused (mixed) such that a (substantially) homogeneous luminous output may be produced outside the luminaire100whilst producing a kaleidoscopic pattern inside the luminaire100as previously explained.

Consequently, the luminaire100may produce a functional luminous distribution in an area surrounding the luminaire whilst providing an aesthetic appearance to an observer directly observing the luminaire100. In this embodiment, preferably all the outlets144of the body130are covered by such a diffusive cover. Any suitable diffusive cover may be used, such as a translucent diffusive film, which may be made of any suitable translucent material, such as a polymer, e.g. PC, PET, PMMA or the like, which polymers can be manufactured as transparent or translucent optical grade polymers as is known per se to the skilled person.

At this point, it is noted that inFIG. 2each optical cell140is shown to be associated with a single SSL element122, i.e. receives incident light from a single SSL element122, for reasons of clarity only. It should be understood that in at least some embodiments, the inlet142of an optical cell140faces a multitude of SSL elements122as is shown by way of non-limiting example inFIG. 3, which schematically depicts a cross-section of an aspect of a luminaire100, particularly part of the axial carrier120carrying a plurality of SSL elements122and part of the body130(two arrays of optical cells140). Each of the optical cells140is associated with a number of SSL elements122on the axial carrier120, that is each inlet142faces a subset124of M SSL elements122, wherein M is a positive integer having a value of at least 2 (M≧2). InFIG. 3, M=4 by way of non-limiting example; it should be understood that each inlet142may face any suitable number of SSL elements122in order to achieve the desired kaleidoscopic effect, e.g. by creating overlapping images of the multiple SSL elements122in a single subset124through multiple reflections of said images inside the optical cell140as previously explained.FIG. 3further shows the upper and lower reflective surfaces148extending between the inlet142and the outlet144of the optical cells140.

In an embodiment, a subset124of SSL elements122may include SSL elements122that generate light of different colours such that the kaleidoscopic effect generated by the optical cell140associated with a subset124comprises a multitude of colours, which can be particularly aesthetically pleasing. Different subsets124may contain SSL elements122of different colours, that is different subsets124may produce different colour combinations such that upon rotation of the body130and/or the axial carrier128colour pattern is generated that varies as a result of said rotation. In other words, the luminaire100may comprise a plurality of subsets124of SSL elements122including a first subset124comprising P SSL elements122generating a first set of colours and a second subset122comprising Q SSL elements122generating a second set of colours, wherein P and Q each are positive integers that may be equal or different to each other and each have a value of at least 2, and wherein the first set is different to the second set. Preferably, P=Q.

FIG. 4schematically depicts a perspective bottom view andFIG. 5schematically depicts a perspective view of an annular body130comprising a stack of annular arrays of wedge-shaped optical cells140each extending between inlets142facing the aperture145of the annular body130and outlets144in the outer surface of the annular body130. The aperture145is dimensioned such that the axial body120including the SSL elements122fits inside the aperture145.

FIG. 6depicts a simulated luminous intensity distribution produced by the luminaire100at ground level when used as a post-top luminaire mounted at 3 m height. The wattage produced by the SSL elements122is about 36 W, and the angle θ is set to 30°. Each of the outlets144are covered by a diffusive film.FIG. 7depicts the simulated kaleidoscopic effect produced by this luminaire100on the diffusive cover over the outlets144. These simulations clearly demonstrate that a luminaire100according to embodiments of the present invention can be used as a post-top luminaire for urban landscape lighting, as the required functional luminous distribution can be produced at ground level as shown inFIG. 6, whilst at the same time producing an aesthetically pleasing lighting effect inside the luminaire100. It is however noted that it is equally feasible that the luminaire100is used to generate a kaleidoscopic effect only, in which case the diffusive film of the outlets144may be omitted as previously explained. Such a luminaire may be used in any suitable setting, e.g. as a decorative light source indoors or outdoors.

At this point, it is noted that in the previous figures the axial carrier120and the annular body130have been shown as having a circular circumference by way of non-limiting example only. It should be understood that the axial carrier120and/or the body130may have any suitably shaped circumference, e.g. a polyhedral circumference such as a hexagonal or octagonal circumference and so on. It should furthermore be understood that although the axial carrier120and the body132may have matching surface shapes, this is not essential.

A non-limiting example of a luminaire100comprising an axial carrier120having a different shape than the body130in the chamber110is shown inFIG. 8, which schematically depicts a top view of an aspect of such a luminaire100. The axial body120has an octagonal shape in which the SSL elements122are organised in a plurality of lines, with each line of SSL elements122mounted on one of the facets of the octagonal circumference of the axial carrier122. The body130may be an annular body comprising a circular circumference as previously described with the aid ofFIG. 1-5such that this body will not be described in detail again for the sake of brevity only.

Another non-limiting example of a luminaire100comprising an axial carrier120having a different shape than the body130in the chamber110is shown inFIG. 9, which schematically depicts a top view of an aspect of such a luminaire100. The axial carrier120has a circular circumference as previously described with the aid ofFIG. 1-5such that the axial carrier120will not be described in further detail for the sake of brevity only. In contrast, the body130has an octagonal shape such that a subset of the plurality of optical cells140defines one of the facets of the body130. More specifically, the inner octagonal surface of the body130is defined by the respective inlets142and the outer octagonal surface of the body130is defined by the respective outlets144, with the respective reflective surfaces of the optical cells140including the reflective side surfaces146extending from the inlets142to the outlets144as before.

The non-limiting examples shown inFIG. 8andFIG. 9are just a few examples of the many suitable shapes of the axial carrier120and the body130that are immediately apparent to the skilled person and it should be understood that any suitable shape of the axial carrier120and the body130may be contemplated in the context of the present invention.

FIG. 10schematically depicts a lighting arrangement according to an embodiment in which a luminaire100is mounted on a mounting post200. Such a mounting post may be made of any suitable material, e.g. a metal or metal alloy such as steel, and may for instance house the electrical cabling for connecting the luminaire100to a power supply. As will be readily understood by the skilled person, the mounting post200may be dimensioned such that the lighting arrangement including the luminaire100and the mounting post200complies with urban lighting requirements, e.g. that the luminaire100is positioned such that it generates a luminous distribution of required dimensions in an area such as a road, street, pavement, square, parking lot and so on.

InFIG. 10, the mounting post200is connected to a bottom portion of the luminaire100by way of non-limiting example. It will be immediately understood by the skilled person that the mounting post200may have any suitable shape, e.g. an inverted L-shape, and may be connected to any suitable portion of the luminaire100, e.g. a top portion of the luminaire100such that the luminaire is seen to dangle from the mounting post200. Many variations to such arrangements are available such that it suffices to say that the luminaire100may be attached in any suitable manner to any suitably shaped mounting post200.