Lighting device and luminaire comprising the lighting device

Abstract

Provided is a lighting device (100) having a lighting assembly (106, 108), and a tubular body (102, 104) formed by co-extrusion of a first material and a second material. The lighting assembly is arranged inside the tubular body and has a first, light-emitting side and a second, e.g. non-light-emitting, side facing away from the first, light-emitting side. The first material exhibits higher transmittance than the second material for light emitted by solid state lighting elements of the lighting assembly, and the second material exhibits higher reflectance for said light than the first material. The tubular body includes a light exit portion (102) formed from the first material and facing the first, light-emitting side of the lighting assembly, and a reflective portion (104) formed from the second material and facing the second side of the lighting assembly. Further provided is a luminaire having at least one of said lighting device, and a method of manufacturing the lighting device.

Description

[0001] 2024PF80396

[0002] 1

[0003] Lighting device and luminaire comprising the lighting device

[0004] FIELD OF THE INVENTION

[0005] The present invention relates to a lighting device comprising solid state lighting elements mounted inside a tubular body, and a luminaire comprising at least one of said lighting device.

[0006] BACKGROUND OF THE INVENTION

[0007] With a continuously growing population, it is becoming increasingly difficult to meet the world’s energy needs as well as to curb greenhouse gas emissions that are considered responsible for climate change phenomena. These concerns have triggered a drive towards more efficient use of electricity in an attempt to reduce energy consumption.

[0008] One such area of concern is lighting applications, in both domestic and commercial settings. There is a clear trend towards replacement of traditional energyinefficient light bulbs, such as incandescent or fluorescent light bulbs, with more energyefficient replacements. Indeed, in many jurisdictions the production and retailing of incandescent light bulbs has been outlawed, thus forcing consumers to buy energy-efficient alternatives, e.g. when replacing incandescent light bulbs.

[0009] A particularly promising alternative is provided by lighting devices comprising solid state lighting elements, which can produce a unit luminous output at a fraction of the energy cost of incandescent light bulbs. An example of such a solid state lighting element is a light emitting diode.

[0010] Such solid state lighting elements can be incorporated into various different types of lighting devices. One type of lighting device comprises a tubular body which houses the solid state lighting elements, so that the solid state lighting elements are arranged within an inner volume of the tubular body.

[0011] Whilst such tubular body-comprising lighting devices have various advantages, such as being able to replace traditional incandescent strip lights, challenges remain in terms of improving optical efficiency whilst enabling the lighting devices to be manufactured in a relatively straightforward, robust and cost-effective manner.2024PF80396

[0012] 2

[0013] It would, for instance, be desirable for such tubular body-comprising lighting devices to be fabricated in a way that is compatible with the growing development trend towards a circular economy, in which circular economy the so-called “end-of-life” for products is replaced with reducing, alternatively reusing, recycling and recovering materials in production, distribution and consumption processes. The aim of the circular economy is to achieve sustainable development, which implies creating environmental quality, economic prosperity and social equity, for the benefit of current and future generations.

[0014] SUMMARY OF THE INVENTION

[0015] The invention is defined by the claims.

[0016] According to examples in accordance with a first aspect of the present disclosure, there is provided a lighting device comprising: a tubular body formed by coextrusion of a first material and a second material; and a lighting assembly comprising solid state lighting elements, the lighting assembly being arranged inside the tubular body and having a first, light-emitting side and a second side that faces away from the first, light-emitting side, wherein the first material exhibits higher transmittance for light emitted by the solid state lighting elements than the second material, and the second material exhibits higher reflectance for said light than the first material, wherein the tubular body comprises: a light exit portion formed from the first material, wherein at least part of the light exit portion faces the first, lightemitting side of the lighting assembly such that light emitted by the solid state lighting elements is incident on the at least part of the light exit portion and passes through the first material to exit the tubular body; a reflective portion formed from the second material and arranged so that light inside the tubular body incident on the reflective portion is reflected by the second material, wherein at least part of the reflective portion faces the second side of the lighting assembly; two ribs provided on inner wall of the tubular body, wherein the ribs are adapted for delimiting a circumferential position for the lighting assembly, within the tubular body and between the two ribs; and two junctions at which the first material and the second material meet each other. In a cross-sectional view, the reflective portion between the two junctions is shorter than the circumferential position of the tubular body between the two ribs for the lighting assembly.

[0017] By co-extruding the first material and the second material to form the tubular body having the light exit portion formed from the higher transmittance but lower reflectance first material, and the reflective portion formed from the higher reflectance but lower transmittance second material, and arranging the light exit portion to face the first, light-2024PF80396

[0018] 3

[0019] emitting side of the lighting assembly and arranging the reflective portion to face the second side of the lighting assembly, the lighting device can benefit from enhanced optical efficiency whilst being relatively robust and straightforward to manufacture.

[0020] The enhanced optical efficiency may come from the reflective portion arranged at a back of the tubular body, so as to face the second side of the lighting assembly, reducing or avoiding loss of light in rearward directions, with the more transmissive light exit portion assisting light to exit the tubular body in desired frontward directions, so as to illuminate a space in which the lighting device is being used.

[0021] In particular, light that is directed towards the back of the tubular body may be re-directed by the second material towards a front of the tubular body, that faces the first, lightemitting side of the lighting assembly, where it can exit the tubular body by being transmitted through the first material of the light exit portion. This re-directed light may exit the light exit portion together with light emitted from the solid state lighting elements that is directly incident on the light exit portion.

[0022] Owing to the different optical functions of the light exit portion / first material and the reflective portion / second material, the first material can, for instance, comprise a different polymer composition to that of the second material.

[0023] For example, the second material may have a greater content of recycled polymer, such as recycled polycarbonate, compared to the first material. In some embodiments, the first material includes no recycled polymer, while the second material includes at least 80% by weight of recycled polymer, such as at least 80% by weight of recycled polycarbonate.

[0024] It is noted, for the avoidance of any doubt, that the term “tubular body” is not intended to be limited to any particular cross-sectional shape of the tubular body, and various different cross-sectional shapes can be contemplated, such as rectangular, e.g. square, U-shaped, e.g. with the curving portion of the U-shape being included in the light exit portion, circular, or elliptical.

[0025] In some embodiments, the second material has a reflectance of at least 90% as measured using a spectrophotometer according to reference standard CIE 015(2018). Such a minimum reflectance of the second material can enhance the lighting device’s optical efficiency. For illustration, simulations indicate that the second material having a reflectance of at least 90% can provide an optical efficiency greater than 94%, whereas the second material having a reflectance of, for instance, 70% to 80% can provide an optical efficiency between 86% and 90%.2024PF80396

[0026] 4

[0027] In some embodiments, the second material has a reflectance in the range of 90% to 100%.

[0028] Alternatively or additionally, the first material may have a transmittance of at least 90% as according to CIE S 025 / E:2015 and as described herein below. Such a minimum transmittance of the first material can enhance the lighting device’s optical efficiency, by allowing more light to exit the tubular body via the light exit portion.

[0029] In some embodiments, the first material has a reflectance in the range of 90% to 97%, such as 94% to 97%.

[0030] It is noted that when the first material is formed from a polycarbonate, e.g. a non-recycled polycarbonate, the first material may have a transmittance of 94% to 97%.

[0031] The first material and the second material may be joined to each other at a connecting region where the first material and the second material overlap with each other so that a first portion of the first material is adjacent to a second portion of the second material along a thickness dimension of the tubular body. By the first material and the second material overlapping with each other in this manner at the connecting region, more interface area may be provided between the first material and the second material compared to the scenario in which there is no such overlap (e.g. when an interface between the first material and the second material extends parallel with the thickness dimension). This greater interface area can, in turn, assist to enhance strength of connection between the first material and the second material.

[0032] It is noted that the thickness dimension can be regarded as a shortest distance, at the connecting region, from an interior surface of the tubular body to an exterior surface of the tubular body.

[0033] In some embodiments, at least part of, e.g. a majority of, the interface between the first material and the second material extends at an oblique angle relative to an axis along which the thickness dimension is defined.

[0034] Such an angled, in other words slanted, interface between the first and second materials may enhance optical efficiency relative to a scenario in which the interface extends parallel to the axis along which the thickness dimension is defined.

[0035] This may be due to the angled interface assisting out-coupling of light trapped within the light exit portion, with the out-coupling of such light at the angled interface causing the light to escape from the tubular body or else causing the light to pass back into the inside of the tubular body where it may subsequently pass through the light exit portion directly or following being reflected by the reflective portion.2024PF80396

[0036] 5

[0037] In some embodiments, the interface slopes away from a first region, at which first region the interface meets an exterior surface of the tubular body, towards a second region, at which second region the interface meets an interior surface of the tubular body.

[0038] In a first set of embodiments, the interface slopes in a direction that causes the first portion of the first material to be disposed between the interior surface and the interface, and the second portion of the second material to be disposed between the exterior surface and the interface.

[0039] In a second set of embodiments, the interface slopes in a direction that causes the first portion of the first material to be disposed between the exterior surface and the interface, and the second portion of the second material to be disposed between the interior surface and the interface.

[0040] Simulations indicate that the direction of sloping of the interface in the second set of embodiments may provide enhanced optical efficiency compared to the opposite direction of sloping in the first set of embodiments.

[0041] In some embodiments, the tubular body further comprises a third material arranged between the first material and the second material. In such embodiments, the third material may, for example, be arranged at the interface, e.g. the sloping interface, between the first material and the second material.

[0042] The third material may be optically transmissive but have a different refractive index compared to a first refractive index of the first material and a second refractive index of the second material.

[0043] Such a third material, for example a third material comprising polymethyl methacrylate (PMMA) and / or polytetrafluoroethylene (PTFE), may assist the out-coupling of light trapped within the light exit portion, by assisting reflection of this light between the first material and the second material.

[0044] In embodiments in which the third material is included in the tubular body, the tubular body may be formed by co-extrusion of the first material, the second material and the third material.

[0045] In other embodiments, the third material is omitted and the first material and the second material directly contact each other, e.g. are melted to each other, at the interface.

[0046] In some embodiments, the light exit portion extends between a first edge portion and a second edge portion, and the reflective portion extends between a first edge part and a second edge part, with the first edge portion being joined to the first edge part and the second2024PF80396

[0047] 6

[0048] edge portion being joined to the second edge part via said co-extrusion of the first material and the second material.

[0049] For example, the first edge portion may be melted directly to the first edge part and the second edge portion may be melted directly to the second edge part via said coextrusion of the first material and the second material.

[0050] In some embodiments, the first material comprises a first polymer composition, and the second material comprises a second polymer composition that is different, in terms of one or more polymer properties, from the first polymer composition. The second polymer composition may, for example, have a different, e.g. lower, molecular weight compared to the first polymer composition.

[0051] It is noted that the term “molecular weight” as used herein may refer to a weight average molecular weight.

[0052] Alternatively or additionally, the second polymer composition may have one or more different rheological properties compared to the first polymer composition.

[0053] In some embodiments, the first material comprises a first polycarbonate composition, and the second material comprises a second polycarbonate composition that is different, in terms of one or more polymer properties, from the first polycarbonate composition.

[0054] For example, the second polycarbonate composition may have a different, e.g. lower, molecular weight compared to the first polycarbonate composition.

[0055] In some embodiments, the second material comprises recycled polycarbonate. For example, the recycled polycarbonate included in the second material may have a lower molecular weight than polycarbonate, e.g. non-recycled (also referred to as “virgin”) polycarbonate, included in the first material.

[0056] It is noted at this point that the reflectance of the second material can be achieved in any suitable manner. In some embodiments, the second material comprises a metallic material, such as aluminum. In other embodiments, the second material comprises pigment particles for reflecting the light emitted by the solid state lighting elements. Such pigment particles can assist to provide the reflectance of the second material.

[0057] The reflectance exhibited by the second material may be diffuse reflectance, e.g. diffuse reflectance provided due, at least in part, to the pigment particles included in the second material. Alternatively or additionally, the second material may exhibit specular reflectance, for example specular reflectance provided by a polished surface of the above-mentioned metallic material, when such a metallic material is included in the second material.2024PF80396

[0058] 7

[0059] In some embodiments, the pigment particles comprise peptide particles. Such peptide particles, e.g. resulting from peptide powder being added during compounding of the second material, may assist the second material to exhibit both relatively high reflectance and relatively low absorbance of light.

[0060] According to examples in accordance with a second aspect of the present disclosure, there is provided a luminaire comprising at least one of the lighting device according to any of the embodiments described herein.

[0061] Such a luminaire may, for instance, comprise a holder in which the lighting device(s) may be detachably mounted. In other embodiments, the luminaire may be an apparatus into which the lighting device(s) is / are integrated, e.g. non-removably installed.

[0062] According to examples in accordance with a third aspect of the present disclosure, there is provided a method of manufacturing the lighting device according to any of the embodiments described herein, with the method comprising co-extruding the first material and the second material to form the tubular body.

[0063] These and other aspects of the invention will be apparent from and elucidated with reference to the embodiments described hereinafter.

[0064] BRIEF DESCRIPTION OF THE DRAWINGS

[0065] 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:

[0066] FIG. 1 provides a perspective view of a lighting device according to an example; FIG. 2 provides a cutaway view showing an interior of the lighting device shown in FIG. 1;

[0067] FIG. 3 provides a cross-sectional view of a lighting device according to another example;

[0068] FIG. 4 provides a cross-sectional view of a lighting device according to still another example;

[0069] FIG. 5 provides a cross-sectional view of a lighting device according to yet another example;

[0070] FIG. 6 provides an enlarged view of part of the lighting device shown in FIG.

[0071] 5;

[0072] FIG. 7 provides a cross-sectional view of a lighting device according to a further example;2024PF80396

[0073] 8

[0074] FIG. 8 provides an enlarged view of part of the lighting device shown in FIG.

[0075] 7;

[0076] FIG. 9 schematically depicts spectrophotometer test equipment for determining reflectance of a material;

[0077] FIG. 10 provides a graph of optical efficiency vs. material reflectivity for a lighting device according to an example; and

[0078] FIG. 11 schematically depicts steps of testing transmittance of a first material that forms a light exit portion of the lighting device.

[0079] DETAILED DESCRIPTION OF THE EMBODIMENTS

[0080] The invention will be described with reference to the Figures.

[0081] 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 the same reference numerals are used throughout the Figures to indicate the same or similar parts.

[0082] Provided is a lighting device having a lighting assembly, and a tubular body formed by co-extrusion of a first material and a second material. The lighting assembly is arranged inside the tubular body and has a first, light-emitting side and a second, e.g. non-light-emitting, side facing away from the first, light-emitting side. The first material exhibits higher transmittance than the second material for light emitted by solid state lighting elements of the lighting assembly, and the second material exhibits higher reflectance for said light than the first material. The tubular body includes a light exit portion formed from the first material and facing the first, light-emitting side of the lighting assembly, and a reflective portion formed from the second material and facing the second side of the lighting assembly.

[0083] Further provided is a luminaire having at least one of said lighting device, and a method of manufacturing the lighting device.

[0084] FIG. 1 provides a perspective view showing an exterior of a lighting device 100 according to an example. The lighting device 100 comprises a tubular body 102, 104. FIG. 2 provides a cutaway view showing an interior of the lighting device 100, and in particular a lighting assembly 106, 108 arranged inside the tubular body 102, 104.2024PF80396

[0085] 9

[0086] The lighting assembly 106, 108 comprises solid state lighting elements 106. The solid state lighting elements 106 may be light emitting diodes (LEDs), e.g. organic or inorganic LEDs. The solid state lighting elements 106 are arranged to emit light towards a light exit portion 102 of the tubular body 102, 104. Luminous surfaces of the solid state lighting elements 106 may emit light towards the light exit portion 102 of the tubular body 102, 104, which light exit portion 102 may act as a light exit surface.

[0087] To this end, the light exit portion 102 of the tubular body 102, 104 is formed from a first material, which first material permits the light emitted by the solid state lighting elements 106 to pass therethrough to exit the tubular body 102, 104, so as to illuminate a space in which the lighting device 100 is being used.

[0088] The first material may be transparent or translucent, e.g. clouded, so as to provide a diffuse lighting effect. The translucent first material can assist the lighting device 100 to provide a luminous output that resembles, for example, that provided by fluorescent tubes, since the translucent first material can help to blend the individual luminous outputs of the solid state lighting elements 106 with one another.

[0089] The first material, whether transparent or translucent, may comprise a polymer, such as polycarbonate, since such a polymer-comprising first material can be used in a coextrusion process to form the tubular body 102, 104, as described in more detail herein below. Alternatively the first material can comprise a glass.

[0090] As well as the solid state lighting elements 106, the lighting assembly 106, 108 may include one or more printed circuit boards 108 to which the solid state lighting elements 106 are mounted. The printed circuit board(s) 108 may, for instance, connect the solid state lighting elements 106 to one or more drivers included in the lighting device 100.

[0091] It is generally noted that the solid state lighting elements 106 may be distributed along a length of the tubular body 102, 104.

[0092] This may provide an elongated luminous output, which may be akin to the luminous output provided by, for instance, the fluorescent tubes.

[0093] The printed circuit board(s) 108 may, for example, extend along the length of the tubular body 102, 104 so that the solid state lighting elements 106 mounted thereto are distributed along the length of the tubular body 102, 104.

[0094] Referring to FIG. 2, the lighting assembly 106, 108 may be mounted on a carrier 110. The carrier 110 may, for example, act as a heat sink for dissipating heat produced by the solid state lighting elements 106 when emitting light. Accordingly, the carrier 110 may comprise a material having good heat conductive properties, e.g. a metallic material.2024PF80396

[0095] 10

[0096] Aluminum is particularly preferred as the metallic material as its pliability means that the carrier 110 can be easily formed, e.g. by extrusion, into its desired shape.

[0097] In embodiments in which the lighting assembly 106, 108 comprises the printed circuit board(s) 108, the printed circuit board(s) 108 may be secured to the carrier 110, for example using thermally conductive glue and / or adhesive strip(s).

[0098] Alternatively, the solid state lighting elements 106 may be mounted directly on the carrier 110, for instance, using thermally conductive glue and / or adhesive strip(s).

[0099] In some embodiments, and referring now to FIGs. 3 and 4, the carrier 110 comprises a central portion on which the lighting assembly 106, 108 is arranged, and one or more peripheral portions that connect the central portion to the tubular body 102, 104. For example, a pair of peripheral portions may connect the central portion to opposing portions of the interior surface 112 of the tubular body 102, 104. A pair of ribs (or protrusions) 111 on the inner wall of the tubular body 102, 104 delimit the circumferential position of the carrier 110.

[0100] In some embodiments, the lighting device 100 comprises a reflective layer 113, e.g. a reflective layer 113 in the form of a reflective film. Such a reflective layer 113, e.g. reflective film, may, for instance, be arranged on the carrier 110. The reflective layer 113 can assist to increase the amount of light generated by the solid state lighting elements 106 that exits the tubular body 102, 104 via the light exit portion 102.

[0101] Various alternative designs for the carrier 110 can be contemplated, and in some embodiments the solid state lighting elements 106 can be supported by the printed circuit board(s) 108 without there having to be a carrier to which the printed circuit board(s) 108 is / are mounted.

[0102] Referring again to FIG. 1, the lighting device 100 may comprise a first end cap 114 arranged to cap a first end of the tubular body 102, 104 and a second end cap 116 arranged to cap a second end of the tubular body 102, 104 that is opposite to the first end.

[0103] One or both of the end caps 114, 116 may support at least part of the driver(s) for controlling the solid state lighting elements 106.

[0104] Alternatively or additionally, one or both of the end caps 114, 116 may comprise one or more pins 118 for engaging with a socket of a luminaire (not shown). In this way, electrical power may be supplied to the lighting device 100. The pin-socket arrangement may further mean that the lighting device 100 is supported within the luminaire. Alternatively, the luminaire fitting may comprise at least one pin, and the lighting device 100 may comprise a socket for receiving the at least one pin. Such fittings are well-known to the skilled person and will not be further described herein for the sake of brevity only.2024PF80396

[0105] 11

[0106] It is noted that an inner volume of the lighting device 100 may be delimited by the tubular body 102, 104 and the end caps 114, 116, with the lighting assembly 106, 108 being arranged in the inner volume.

[0107] For example, the tubular body 102, 104 and the end caps 114, 116 may be connected to each other so as to hermetically seal the inner volume of the lighting device 100. This can assist to protect the solid state lighting elements 106 and / or circuitry for controlling the solid state lighting elements 106 from damage or degradation.

[0108] Alternatively or additionally, an inert gas, such as argon or neon, may be present in the inner volume. Such an inert gas can also assist to protect the solid state lighting elements 106 and / or circuitry from damage or degradation.

[0109] It is noted at this point that the tubular body 102, 104 may have any suitable cross-sectional shape, such as rectangular, e.g. square, U-shaped, e.g. with the curving portion of the U-shape being included in the light exit portion 102, circular (as shown in FIGs. 3 and 4), or elliptical.

[0110] Still referring to FIGs. 3 and 4, the lighting assembly 106, 108 has a first, lightemitting side 120, and a second side 122 facing away from the first, light-emitting side 120. Luminous surfaces of the solid state lighting elements 106 may be provided at the first, lightemitting side 120.

[0111] The second side 122 of the lighting assembly 106, 108 may not emit light. For example, the second side 122 of the lighting assembly 106, 108 may correspond to an underside, e.g. a carrier-facing side, of the printed circuit board(s) 108 at which no luminous surface is provided.

[0112] At least part of the light exit portion 102 of the tubular body 102, 104 faces the first, light-emitting side 120 of the lighting assembly 106, 108 such that light emitted by the solid state lighting elements 106 is incident on the at least part of the light exit portion 102 and passes through the first material to exit the tubular body 102, 104.

[0113] The tubular body 102, 104 further comprises a reflective portion 104 that is formed from a second material and is arranged so that light inside the tubular body 102, 104 incident on the reflective portion 104 is reflected by the second material. At least part of the reflective portion 104 faces the second side 122 of the lighting assembly 102, 104.

[0114] The first material that forms the light exit portion 102 exhibits higher transmittance for the light emitted by the solid state lighting elements 106 than the second material that forms the reflective portion 104. Moreover, the second material that forms the reflective portion 104 exhibits higher reflectance for the light emitted by the solid state lighting2024PF80396

[0115] 12

[0116] elements 106 than the first material. These different optical properties of the first material and the second material, together with how they are arranged in the tubular body 102, 104 of the lighting device 100 can provide enhanced optical efficiency.

[0117] The enhanced optical efficiency may come from the reflective portion 104 arranged at a back of the tubular body 102, 104, so as to face the second side 122 of the lighting assembly 106, 108, reducing or avoiding loss of light in rearward directions, with the more transmissive light exit portion 102 assisting light to exit the tubular body 102, 104 in desired frontward directions, so as to illuminate a space in which the lighting device 100 is being used.

[0118] In particular, light that is directed towards the back of the tubular body 102, 104 may be re-directed by the second material towards a front of the tubular body 102, 104, that faces the first, light-emitting side 120 of the lighting assembly 106, 108, where it can exit the tubular body 102, 104 by being transmitted through the first material of the light exit portion 102. This re-directed light may exit the light exit portion 102 together with light emitted from the solid state lighting elements 106 that is directly incident on the light exit portion 102.

[0119] According to light transmitting theory, light generated by the solid state lighting elements 106 may be transmitted outside the tubular body 102, 104, or may be refracted within the tubular body 102, 104, e.g. within the diffusive tubular body 102, 104. However, the light may be reflected from, rather than being absorbed at, the surface of the reflective portion 104. In this way, all, or at least substantially all, of the light generated by the solid state lighting elements 106 may be transmitted into the space being illuminated by the lighting device 100.

[0120] The reflectance of the second material can be achieved in any suitable manner. In some embodiments, the second material comprises a metallic material, such as aluminum. A surface, e.g. polished surface, of the metallic material can assist to provide the reflectance of the second material. In other embodiments, the second material comprises pigment particles for reflecting the light emitted by the solid state lighting elements 106. Such pigment particles can assist to provide the reflectance of the second material.

[0121] The reflectance exhibited by the second material may be diffuse reflectance, e.g. diffuse reflectance provided due, at least in part, to the pigment particles included in the second material. Specular reflectance may be provided by the above-mentioned polished surface of the metallic material, when such a metallic material is included in the second material.

[0122] In some embodiments, the pigment particles comprise peptide particles. Such peptide particles, e.g. resulting from peptide powder being added during compounding of the second material, may assist the second material to exhibit both relatively high reflectance and relatively low absorbance of light.2024PF80396

[0123] 13

[0124] It is noted that the second material may comprise at least one of a fire retardant and an anti-oxidizing agent. The fire retardant and / or the anti-oxidizing agent may, for instance, be included in the second material in addition to a polymer, e.g. polycarbonate, and the pigment particles.

[0125] Alternatively or additionally, the first material may, e.g. in addition to the polymer, e.g. polycarbonate, include at least one of a fire retardant and an anti-oxidizing agent.

[0126] Owing to the different optical functions of the light exit portion 102 / first material and the reflective portion 104 / second material, the first material can, for instance, comprise a different polymer composition to that of the second material. Due to the reflecting purpose of the second material, the second material can be beneficially made of more recycled polymer, e.g. recycled polycarbonate, than the first material.

[0127] In some embodiments, the first material comprises a first polymer composition, and the second material comprises a second polymer composition that is different, in terms of one or more polymer properties, from the first polymer composition. The second polymer composition may, for example, have a different, e.g. lower, molecular weight compared to the first polymer composition.

[0128] It is noted that the term “molecular weight” as used herein may refer to a weight average molecular weight.

[0129] Alternatively or additionally, the second polymer composition may have one or more different rheological properties compared to the first polymer composition.

[0130] In some embodiments, the first material comprises a first polycarbonate composition, and the second material comprises a second polycarbonate composition that is different, in terms of one or more polymer properties, from the first polycarbonate composition.

[0131] For example, the second polycarbonate composition may have a different, e.g. lower, molecular weight compared to the first polycarbonate composition.

[0132] In some embodiments, the second material comprises recycled polycarbonate. For example, the recycled polycarbonate included in the second material may have a lower molecular weight than polycarbonate, e.g. non-recycled (also referred to as “virgin”) polycarbonate, included in the first material.

[0133] In some embodiments, the first material includes no recycled polymer, while the second material includes at least 80% by weight of recycled polymer, such as at least 80% by weight of recycled polycarbonate.

[0134] In more general terms, the second material may have a greater content of recycled polymer, such as recycled polycarbonate, compared to the first material.2024PF80396

[0135] 14

[0136] It is noted that the recycled polymer mentioned herein may be post-consumer recycled (PCR) polymer, for example PCR polycarbonate.

[0137] It has been found that an optical efficiency of a tubular body 102, 104 whose second material is PCR polycarbonate can be comparable to when a second material in the form of a single color diffusive polycarbonate having higher transmittance is employed.

[0138] In a first non-limiting illustrative example, the reflective portion 104 of the tubular body 102, 104 comprises (i) a polycarbonate composition composed of 80% by weight of PCR polycarbonate and 20% by weight of non-recycled polycarbonate (with these percentages being by weight of the polycarbonate composition), (ii) peptide particles for reflecting the light emitted by the solid state lighting elements 106, (iii) an anti-oxidizing agent, and (iv) a fire retardant.

[0139] In a second non-limiting illustrative example, the light exit portion 102 of the tubular body 102, 104 comprises a diffusive, non-recycled, polycarbonate.

[0140] In a third non-limiting illustrative example, the reflective portion 104 of the first non-limiting illustrative example is included in the tubular body 102, 104 of the lighting device 100 together with the light exit portion 102 of the second non-limiting illustrative example.

[0141] In order to verify performance, a lighting device 100 according to the present disclosure was fabricated whose tubular body 102, 104 included a white reflective portion 104 according to the first non-limiting example, and a comparative lighting device was fabricated that differed from the lighting device 100 according to the present disclosure due to its rear portion (that faces the second side 122 of the lighting assembly 106, 108) being formed from clear / transparent PCR polycarbonate (exhibiting lower reflectance). The lighting device 100 whose tubular body 102, 104 included the white reflective portion 104 according to the first non-limiting example was found to have superior optical efficiency compared to the comparative lighting device.

[0142] It is generally noted that the reflecting purpose of the second material can mean that more recycled polymer, e.g. recycled polycarbonate, can be included in the second material than in the first material. For example, the second material can include 80% by weight or more of PCR polycarbonate

[0143] FIGs. 3 and 4 illustrate that the relative amounts of the first material constituting the light exit portion 102 and the second material constituting the reflective portion 104 can be varied. For example, FIG. 4 illustrates a height difference 124 between a first height 126 of a junction at which the first material and the second material meet each other (shown in FIG. 3) and a second height 128 of the junction in the case of the embodiment shown in FIG. 4.2024PF80396

[0144] 15

[0145] Reducing the amount of the second material relative to the first material, e.g. via the lower second height 128 shown in FIG. 4, can assist to increase optical efficiency (since the area of the light exit portion 102 may be enlarged), although reducing the relative amount of the second material can mean that the amount of recycled polymer, e.g. PCR polycarbonate, that is included in the tubular body 102, 104 is reduced.

[0146] Hence there may be a trade-off in terms of optical efficiency and amount of recycled polymer, e.g. PCR polycarbonate, that can be included in the tubular body 102, 104.

[0147] Purely for illustration, simulations indicate that the second height 128 being 2.0 mm lower than the first height 126 can increase optical efficiency by 0.5% but reduce the amount of recycled polymer, e.g. PCR polycarbonate, in the tubular body 102, 104 by 10%.

[0148] More generally, the tubular body 102, 104 is formed by co-extruding the first material and the second material. The co-extrusion is identifiable from the two different materials, in other words the first, more transmissive and less reflective, material and the second, more reflective and less transmissive, material, being combined in a single part.

[0149] Co-extruding the first material and the second material may offer a relatively straightforward and cost-effective way of realizing a robust tubular body 102, 104 having the optical efficiency benefits associated with the light exit portion 102 and the reflective portion 104.

[0150] In some embodiments, and still referring to FIGs. 3 and 4, the light exit portion 102 extends between a first edge portion 130 and a second edge portion 132, and the reflective portion 104 extends between a first edge part 134 and a second edge part 136, with the first edge portion 130 being joined to the first edge part 134 and the second edge portion 132 being joined to the second edge part 136 via said co-extrusion of the first material and the second material. For example, the first edge portion 130 may be melted directly to the first edge part 134 and the second edge portion 132 may be melted directly to the second edge part 136 via said co-extrusion of the first material and the second material.

[0151] In some embodiments, and referring now to FIGs. 5 to 8, the first material and the second material may be joined to each other at a connecting region 138 where the first material and the second material overlap with each other so that a first portion 140 of the first material is adjacent to a second portion 142 of the second material along a thickness dimension 144 of the tubular body 102, 104. By the first material and the second material overlapping with each other in this manner at the connecting region 138, more interface area may be provided between the first material and the second material compared to the scenario in which there is no such overlap (e.g. when an interface between the first material and the second2024PF80396

[0152] 16

[0153] material extends parallel with the thickness dimension 144). This greater interface area can, in turn, assist to enhance strength of connection between the first material and the second material.

[0154] It is noted that the thickness dimension 144 can be regarded as a shortest distance along an axis 146, at the connecting region 138, from the interior surface 112 of the tubular body 102, 104 to an exterior surface 148 of the tubular body 102, 104.

[0155] In some embodiments, and still referring to FIGs. 5 to 8, the first material and the second material are joined to each other at an interface 150, with at least part of, e.g. a majority of, the interface 150 extending at an oblique angle 152 relative to the axis 146 along which the thickness dimension 144 is defined.

[0156] Such an angled, in other words slanted, interface 150 between the first and second materials may enhance optical efficiency relative to a scenario in which the interface 150 extends parallel to the axis 146 along which the thickness dimension 144 is defined. This may be due to the angled interface 150 assisting out-coupling of light trapped within the light exit portion 102, with the out-coupling of such light at the angled interface causing the light to escape from the tubular body 102, 104 or else causing the light to pass back into the inside of the tubular body 102, 104 where it may subsequently pass through the light exit portion 102 directly or following being reflected by the reflective portion 104.

[0157] In some embodiments, and referring to FIGs. 6 and 8, the interface 150 slopes away from a first region 154, at which first region 154 the interface 150 meets the exterior surface 148 of the tubular body 102, 104, towards a second region 156, at which second region 156 the interface 150 meets the interior surface 112 of the tubular body 102, 104.

[0158] In a first set of embodiments, and referring to FIGs. 5 and 6, the interface 150 slopes in a direction that causes the first portion 140 of the first material to be disposed between the interior surface 112 and the interface 150, and the second portion 142 of the second material to be disposed between the exterior surface 148 and the interface 150.

[0159] In a second set of embodiments, and referring to FIGs. 7 and 8, the interface 150 slopes in a direction that causes the first portion 140 of the first material to be disposed between the exterior surface 148 and the interface 150, and the second portion 142 of the second material to be disposed between the interior surface 112 and the interface 150.

[0160] Simulations indicate that the direction of sloping of the interface 150 in the second set of embodiments may provide enhanced optical efficiency compared to the opposite direction of sloping in the first set of embodiments. Such simulations comparing the nonlimiting example shown in FIGs. 5 and 6 with the non-limiting example shown in FIGs. 7 and 8 indicated an optical efficiency of 94.9% in the case of the non-limiting example shown in2024PF80396

[0161] 17

[0162] FIGs. 7 and 8 and an optical efficiency of 94.6% in the case of the non-limiting example shown in FIGs. 5 and 6.

[0163] In some embodiments, the tubular body 102, 104 further comprises a third material arranged between the first material and the second material. In such embodiments, the third material may, for example, be arranged at the interface 150, e.g. the sloping interface 150, between the first material and the second material.

[0164] The third material may be optically transmissive but have a different refractive index compared to a first refractive index of the first material and a second refractive index of the second material.

[0165] Such a third material, for example a third material comprising polymethyl methacrylate (PMMA) and / or polytetrafluoroethylene (PTFE), may assist the out-coupling of light trapped within the light exit portion 102, by assisting reflection of this light between the first material and the second material.

[0166] In embodiments in which the third material is included in the tubular body 102, 104, the tubular body 102, 104 may be formed by co-extrusion of the first material, the second material and the third material.

[0167] In other embodiments, the third material is omitted and the first material and the second material directly contact each other, e.g. are melted to each other, at the interface 150.

[0168] In some embodiments, and referring now to FIG. 9, the second material has a reflectance of at least 90% as measured using a spectrophotometer 158 according to reference standard CIE 015 (2018). Such a minimum reflectance of the second material can enhance the lighting device’s 100 optical efficiency.

[0169] For illustration, and referring to the graph shown in FIG. 10, simulations indicate that the second material having / exhibiting a reflectance of at least 90% can provide an optical efficiency greater than 94% (see region 160 of the graph), whereas a reflectance of, for instance, 70% to 80% can provide an optical efficiency between 86% and 90% (see region 162 of the graph).

[0170] In some embodiments, the second material has a reflectance in the range of 90% to 100%.

[0171] Regarding the manner in which reflectance of the second material is determined, the spectrophotometer 158 equipment shown in FIG. 9 comprises a light source 164 in the form of a xenon lamp, for emitting the light used for the measurement into an integrating sphere 166, which integrating sphere 166 collects the light onto a sample 168 of the second material. The sample 168 is arranged so that the light reflected by the sample 168 passes through a lens2024PF80396

[0172] 18

[0173] 170 to reach a detector 172. The reflectance, in other words total reflectance, TR of the second material is calculated using the following equation: TR = Y / X * 100, where Y is the radiant flux of the reflected light detected by the detector 172 and X is the radiant flux emitted by the light source 164.

[0174] Regarding the geometry employed for the reflectance measurement, reference is made to the 8° geometry, specular component included (di: 8°) set out in section 6.4.1 of CIE 015 (2018).

[0175] Alternatively or additionally to the second material having a reflectance of at least 90%, the first material may have a transmittance of at least 90% using integrating sphere test equipment as according to CIE S 025 / E:2015. The left-hand pane of FIG. 11 is intended to represent a first step in which the flux, P, of the solid state lighting element 106 of the lighting assembly 106, 108 is measured by being placed in an integrating sphere. The right-hand pane of FIG. 11 represents measurement of the flux, Q, outside the tubular body 102, 104 when the lighting assembly 106, 108 is arranged in the tubular body 102, 104. The transmittance, in other words total transmittance, TT of the first material is calculated using the following equation: TT = Q / P * 100.

[0176] The first material having / exhibiting a minimum transmittance of 90% can mean that the lighting device 100 exhibits enhanced optical efficiency, by allowing more light to exit the tubular body 102, 104 via the light exit portion 102.

[0177] In some embodiments, the first material has a reflectance in the range of 90% to 97%, such as 94% to 97%.

[0178] It is noted that when the first material is formed from a polycarbonate, e.g. a non-recycled polycarbonate, the first material may have a transmittance of 94% to 97%.

[0179] At least one of the lighting device 100 according to any of the embodiments described herein may be included in a luminaire. The luminaire may comprise a holder for the lighting device 100, for example a ceiling light fitting, an armature for fitting underneath a cabinet or the like. Alternatively, the luminaire may be an apparatus into which the lighting device(s) 100 is / are integrated, e.g. a cooker hood or the like.

[0180] The present disclosure further provides a method of manufacturing the lighting device 100 according to any of the embodiments described herein, with the method comprising co-extruding the first material and the second material to form the tubular body 102, 104.

[0181] When made via co-extrusion, both materials preferentially have the same matrix and similar molecular weight in order to achieve stable extrusion and good interface strength.2024PF80396

[0182] 19

[0183] More generally, the first material and the second material, provided that they can be co-extruded and satisfy the relevant optical requirements (a more transmissive, less reflective first material in combination with a less transmissive, more reflective second material), can be of any suitable type. For example, the first material may be a first glass and the second material may be a second glass that is more reflective and less transmissive than the first glass. Alternatively, one of the first and second materials may be a polycarbonate composition and the other of the first and second materials may be a polycarbonate, a polyethylene or a polystyrene composition, or a combination thereof.

[0184] Particular mention is made of embodiments in which the first material comprises the first polymer composition, e.g. the first polycarbonate composition, and the second material comprises the second polymer composition, e.g. the second polycarbonate composition. For example, the second polycarbonate composition may comprise more recycled polycarbonate than the first polycarbonate composition, which first polycarbonate composition may, for instance, not include any recycled polycarbonate.

[0185] The co-extrusion may be implemented using a co-extrusion tooling composed of two cavities in a first step. The shapes of the two cavities correspond to those of two sections of the tubular body 102, 104, including the interface geometry of the first and second materials.

[0186] Various materials flow through the two cavities, and then flow to a combined cavity in a second step. The combined cavity is the same as the section of co-extruded tubular body 102, 104.

[0187] Thus, a desired interface geometry, e.g. the slanted interface 150, can be achieved by adjusting the co-extrusion tooling, including the slanted interface.

[0188] 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.

[0189] 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.

[0190] 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".

[0191] Any reference signs in the claims should not be construed as limiting the scope.

Claims

2024PF8039620CLAIMS:

1. A lighting device (100) comprising:a tubular body (102, 104) formed by co-extrusion of a first material and a second material; anda lighting assembly (106, 108) comprising solid state lighting elements (106), the lighting assembly being arranged inside the tubular body and having a first, light-emitting side (120) and a second side (122) that faces away from the first, light-emitting side, wherein the first material exhibits higher transmittance for light emitted by the solid state lighting elements than the second material, and the second material exhibits higher reflectance for said light than the first material, wherein the tubular body comprises:a light exit portion (102) formed from the first material, wherein at least part of the light exit portion faces the first, light-emitting side of the lighting assembly such that light emitted by the solid state lighting elements is incident on the at least part of the light exit portion and passes through the first material to exit the tubular body;a reflective portion (104) formed from the second material and arranged so that light inside the tubular body incident on the reflective portion is reflected by the second material, wherein at least part of the reflective portion faces the second side of the lighting assembly;two ribs (111) provided on inner wall of the tubular body (102, 104), wherein the ribs are adapted for delimiting a circumferential position for the lighting assembly (106, 108), within the tubular body (102, 104) and between the two ribs (111); andtwo junctions at which the first material and the second material meet each other;wherein in a cross-sectional view, the reflective portion (104) between the two junctions is shorter than the circumferential position of the tubular body between the two ribs for the lighting assembly;wherein the second material has a reflectance of at least 90% as measured using a spectrophotometer (158) according to reference standard CIE 015 (2018).2024PF80396212. The lighting device (100) according to claim 1, wherein the first material has a transmittance of at least 90% as according to CIE S 025 / E: 2015.

3. The lighting device (100) according to any one of claims 1 to 2, comprising a connecting region (138) at which the first material and the second material are joined to each other, wherein in the connecting region the first material and the second material overlap with each other so that a first portion (140) of the first material is adjacent to a second portion (142) of the second material along a thickness dimension (144) of the tubular body (102, 104).

4. The lighting device (100) according to claim 3, wherein the first material and the second material are joined to each other at an interface (150), at least part of the interface extending at an oblique angle (152) relative to an axis (146) along which the thickness dimension (144) is defined.

5. The lighting device (100) according to claim 4, wherein the interface (150) slopes away from a first region (154), at which first region the interface meets an exterior surface (148) of the tubular body (102, 104), towards a second region (156), at which second region the interface meets an interior surface (112) of the tubular body.

6. The lighting device (100) according to claim 5, wherein the interface (150) slopes in a direction that causes the first portion (140) of the first material to be disposed between the exterior surface (148) and the interface (150), and the second portion (142) of the second material to be disposed between the interior surface (112) and the interface.

7. The lighting device (100) according to any one of claims 1 to 6, wherein the tubular body (102, 104) further comprises a third material arranged between the first material and the second material, the tubular body being formed by co-extrusion of the first material, the second material and the third material, wherein the third material is optically transmissive but has a different refractive index compared to a first refractive index of the first material and a second refractive index of the second material.

8. The lighting device (100) according to any one of claims 1 to 7, wherein the first material comprises a first polymer composition, and the second material comprises a2024PF8039622second polymer composition that is different, in terms of one or more polymer properties, from the first polymer composition.

9. The lighting device (100) according to any one of claims 1 to 8, wherein the second material comprises recycled polycarbonate.

10. The lighting device (100) according to any one of claims 1 to 9, wherein the second material comprises pigment particles for reflecting the light emitted by the solid state lighting elements (106).

11. The lighting device (100) according to claim 10, wherein the pigment particles comprise peptide particles.

12. The lighting device (100) according to any one of claims 1 to 11, wherein the light exit portion (102) extends between a first edge portion (130) and a second edge portion (132), and the reflective portion (104) extends between a first edge part (134) and a second edge part (136), wherein the first edge portion is joined to the first edge part and the second edge portion is joined to the second edge part via said co-extrusion of the first material and the second material.

13. A luminaire comprising at least one of the lighting device (100) according to any one of claims 1 to 12.

14. A method of manufacturing the lighting device (100) according to any one of claims 1 to 12, the method comprising co-extruding the first material and the second material to form the tubular body (102, 104).

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