Producing a tubular housing for a lighting device

Abstract

A tubular housing and a method for making the tubular housing. The tubular housing is formed from a stack of layers that bounds an interior housing volume, thereby forming a sidewall for the tubular housing. The stack of layers comprises a reflective layer and at least one structurally supporting layer. The reflective layer is positioned between the interior housing volume and the at least one structurally supporting layer.

Description

[0001] Producing a tubular housing for a lighting device

[0002] FIELD OF THE INVENTION

[0003] The present invention relates to the field of lighting devices, and in particular to elongate lighting devices.

[0004] BACKGROUND OF THE INVENTION

[0005] There is an increasing reliance on artificial lighting in everyday life. Traditionally, lighting devices or luminaires for providing artificial light are formed of metallic or plastic components. In particular, it is extremely common for tubular housings and structural supports for lighting devices to be formed of metallic or plastic components. Disadvantageously, components made of such materials add significant weight to the lighting and are difficult to assemble (e.g., requiring screws and / or adhesive).

[0006] One proposed approach to reduce the environmental impact of a lighting device is to replace metallic or plastic tubular housings / supports with tubular housings / supports made from paper-derived material, such as cardboard or paperboard.

[0007] To make such devices, conventional processes consist of twining or winding several paper layers around a mold, followed by punching the paper layers to provide a paper tubular housing with a light exit window.

[0008] There is an ongoing desire to improve the process of making lighting devices, particularly those comprising components formed from environmentally friendly material such as paper-derived material.

[0009] US 20130033888A1 discloses a lighting device with an at least partly flexible sheet assembly which is rolled into a tube.

[0010] SUMMARY OF THE INVENTION

[0011] The invention is defined by the claims.

[0012] According to examples in accordance with an aspect of the invention, there is provided an elongate lighting device comprising a tubular housing and a light emitting element of, the (elongate) tubular housing extending along a first axis and comprising a side wall comprising a stack of layers. The stack of layers comprises a reflective layer stacked upon one or more structurally supporting layers. The stack of layers bound an interior housing volume in which the light emitting element is positioned; and the reflective layer faces the interior housing volume. The sidewall comprises one or more apertures through the stack of layers to define one or more light exit windows for the elongate lighting device.

[0013] The present disclosure thereby provides a tubular housing formed by disposing one or more structurally supportive layers on a layer of reflective material, the layers together defining an interior housing volume in which a light emitting element is to be positioned or placed. This increases an ease of assembling or manufacturing the tubular housing, e.g., by avoiding the need to perform a complex fitting process and / or size matching between a reflective element and a structural support. The proposed approach also reduces a risk of lighting defects.

[0014] The proposed approach effectively provides a mechanism for integrating a reflective layer into the structural support for the lighting device.

[0015] In some examples, at least one layer, preferably each layer, of the one or more structurally supporting layers is formed from cellulose fiber material. This embodiment significantly increases a recyclability and reduces an environmental impact of the tubular housing, e.g., by avoiding the use of one-use plastics and / or minimizing a use of metals.

[0016] There is also provided a lighting device comprising the tubular housing herein disclosed: and the light emitting element positioned within the interior housing volume.

[0017] In some examples, the reflective layer is a foil of aluminum or aluminum alloy. Metal foils don’t have fibers as cellulose fiber material, e.g., kraft paper, thus is unlike to cause rough edge when cutting the side wall of the tubular housing with a blade or punching it with a mold. Therefore, this foil not only increases the optical efficiency of the lighting device, but also eases the manufacture of the tubular housing by creating a smooth edge of the one or more apertures as light exit windows for the elongate lighting device.

[0018] In some examples, the reflective layer is adhered to the one or more structurally supportive layers, and when there are more than one layer of the one or more structurally supportive layers, such layers are adhered to each other to form the stack of layers.

[0019] There is also provided a method for producing a tubular housing for an elongate lighting device as described above , the method comprising: providing a mold defining a shape of an interior housing volume for the elongate lighting device; winding a reflective layer of flexible material about the mold; providing one or more structurally supporting layers about the reflective layer wound around the mold, to thereby create a stack of layers comprising the reflective layer and the one or more structurally supporting layers that bound the interior housing volume; disengaging the mold from the stack of layers to thereby produce the tubular housing; and cutting or punching one or more apertures through the stack of layers to define one or more light exit windows for the elongate lighting device.

[0020] The proposed method provides a technique for easy assembly and / or creation of the elongate tubular housing for the elongate lighting device. In particular, the use of a mold facilitates repeatable and reliable shaping of the reflective layer and the interior housing volume, for improved consistency in manufacturing. The proposed approach also facilitate ease of positioning or winding the layers of the stack of layers over one another, to provide a close coupling for improved structural support and stability.

[0021] In some examples, the mold has a non-rectangular cross-sectional shape in a first plane, wherein the first axis is normal to the first plane. Examples of suitable non- rectangular cross-sectional shapes include: a (e.g., isosceles) trapezoid or trapezium; a (e.g., isosceles) triangle; an arch shape; a semicircle and so on.

[0022] In some examples, the mold is moveable between a first configuration, in which the mold has a first shape, and a second configuration, in which the mold has a second shape, smaller than the first shape.

[0023] In such examples, the steps of winding the reflective layer and providing the one or more structurally supporting layers about the mold are performed when the mold is in the first configuration; and the step of disengaging the mold comprises: moving the mold from the first configuration to the second configuration; and extracting the mold from the interior housing volume.

[0024] This approach provides a technique for improving an ease of removing the mold from the tubular housing after production or creation of the tubular housing. By reducing a size of the mold before removal, a risk of damaging the interior of the tubular housing (particularly the reflective layer) is significantly reducing, thereby maintaining an efficiency of the reflective layer and reducing the risk of defects forming.

[0025] In some examples, the first shape has a greater size in a first plane, for which the first axis is normal to the first plane, than the second shape.

[0026] The mold may be collapsible so as to facilitate movement between the first configuration and the second configuration. By way of example, the mold may comprise two or more moving portions, a scissor mechanism and / or an inflatable bladder for facilitating the movement between the first and second configurations.

[0027] The method may further comprise adhering the reflective layer to the one or more structurally supporting layers. This reduces a risk of the reflective layer losing its shape and thereby affecting the optical efficiency and / or characteristics of the tubular housing for the lighting device.

[0028] In some examples, providing the one or more structurally supporting layers comprises winding a piece of structurally supporting material about the mold to form the one or more structurally supporting layers.

[0029] In preferred examples, winding the one or more structurally supporting layers may comprising performing the winding of the piece of structurally supporting material a plurality of times.

[0030] In preferred examples, the one or more structurally supporting layers comprises a plurality of structurally supporting layers. This significantly increases the structural support provide by the one or more structurally supporting layers, reducing a risk of the tubular housing deforming.

[0031] In some examples, the reflective layer and each of the one or more structurally supporting layers is formed from and / or using cellulose fiber material.

[0032] There is also proposed a method for producing an elongate lighting device as described above comprising performing any herein disclosed method; and after disengaging the mold from the stack of layers, inserting the light emitting element into the interior housing volume.

[0033] The method may further comprise comprising coupling the light emitting element to the reflective layer.

[0034] These and other aspects of the invention will be apparent from and elucidated with reference to the embodiment(s) described hereinafter.

[0035] BRIEF DESCRIPTION OF THE DRAWINGS

[0036] 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:

[0037] Figure 1 illustrates a tubular housing;

[0038] Figure 2 illustrates a portion of the tubular housing;

[0039] Figure 3 provides another view of the tubular housing;

[0040] Figure 4 illustrates a lighting device comprising the tubular housing;

[0041] Figure 5 provides another view of the lighting device; Figures 6 to 9 illustrate a technique for producing the tubular housing;

[0042] Figure 10 illustrates an alternative lighting device;

[0043] Figure 11 illustrates another alternative lighting device; and

[0044] Figure 12 illustrates yet another lighting device.

[0045] DETAILED DESCRIPTION OF THE EMBODIMENTS

[0046] The invention will be described with reference to the Figures.

[0047] 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.

[0048] The invention provides a tubular housing and a method for making the tubular housing. The tubular housing is formed from a stack of layers that bounds an interior housing volume, thereby forming a sidewall for the tubular housing. The stack of layers comprises a reflective layer and at least one structurally supporting layer. The reflective layer is positioned between the interior housing volume and the at least one structurally supporting layer.

[0049] Figure 1 provides a cross-sectional view of a tubular housing 100 for a light emitting element (not visible in Figure 1). The tubular housing 100 is formed from a stack of layers 110, 120 that enclose an interior housing volume 190. The light emitting element is, or will be, positioned within the interior housing volume 190.

[0050] The stack of layers 110, 120 comprises a reflective layer 110 that faces the interior housing volume 190.

[0051] The stack of layers also comprises one or more structurally supporting layers 120 that provide structural support to at least the reflective layer 110. Thus, the reflective layer 110 is disposed or positioned between the interior housing volume 190 and the one or more structurally supporting layers 120.

[0052] The stack of layers 110, 120 thereby provides or defines a sidewall for the tubular housing 100. The sidewall is the physical bounds of the interior housing volume in which the light emitting element is to be positioned. The tubular housing 100 may further comprise one or more apertures 150 that extend through the stack of layers 110, 120. Thus, each layer 110, 120 in the stack of layers (that bounds the interior housing volume 190) may comprise a respective aperture that, when stacked, create an aperture through the stack of layers 110, 120. The aperture(s) may, for instance, be formed by punching, cutting or otherwise forming a through-hole through the stack of layers 110, 120.

[0053] In preferred examples, if a thickness of the stack of layers varies at different positions around the interior housing volume (e g., resulting from an additional partial wrap by the reflective and / or structurally supporting layers), then the aperture 150 is preferably located at a location having the greatest thickness. This is illustrated in Figure 1.

[0054] The structurally supporting layer(s) 120 may be formed by a single piece of structurally supporting material that is wrapped or wound one or more times around the reflective layer 110. The winding or wrapping may terminate at a termination location 125, which may form a visible seam. In preferred examples, the aperture 150 may be positioned adjacent to this termination location 125 for reduce visibility of the termination location or seam to a viewer of the tubular housing.

[0055] In the illustrated example, the reflective layer 110 comprises only a single layer or winding. However, in practice, the reflective layer 110 may comprise one or more layers or windings (or, as explained below, a partial layer or winding) about the interior housing volume 190.

[0056] Although providing more than one reflective layer may be less materially efficient than use of a single layer without improving the reflective quality of the reflective layer(s) (e.g., as layers beyond the first layer will not perform reflection of light), such embodiments may be useful for ensuring that the entirety of the desired bounds of the interior housing volume 190 are wrapped with the reflective layer 110. This thereby builds in redundancy.

[0057] In some examples, the reflective layer 110 comprises a partial winding around the interior housing volume. This avoids the need to cut or otherwise form an aperture in the reflective layer.

[0058] More specifically, in the illustrated example, the stack of layers 110, 120 comprises a single reflective layer 110 and one and a half structurally supporting layers 120. Thus, the reflective layer 110 wraps or winds once completely around the interior housing volume. The one and a half structurally supporting layers 120 comprises a first structurally supporting layer 121 that wraps or covers the entirety of the reflective layer 110, and then a half structurally supporting layer that covers half of the first structurally supporting layer, i.e., partially wraps the first structurally supporting layer.

[0059] Of course, the tubular housing may comprise any (positive) number of structurally supporting layers that wrap or enclose the reflective layer 110. The greater the number of layers, the greater the structural support provided to the tubular housing. This is due to increased thickness of the structurally supporting layers.

[0060] Although previously described examples prepare the structurally supporting layer(s) by wrapping a single piece of structurally supporting material about the reflective layer, alternative approaches are considered. For instance, the structurally supporting layer(s) may be provided by wrapping two or more separate pieces of structurally supporting material about the reflective layer. As another example, the structurally supporting layer(s) may be provided by molding structurally supporting material to the reflective layer.

[0061] Figure 2 provides a cross-sectional view of a portion of the tubular housing 100. Figure 2 better illustrates the structural relationship between the layers 110, 120 of the stack of layers. In particular, Figure 2 illustrates how the structurally supporting layer(s) are positioned on top of the reflective layer(s), such that the reflective layer lies between the structurally supporting layer(s) and the interior housing volume 190.

[0062] Figure 3 provides a perspective view of the tubular housing 100.

[0063] As best illustrated in Figure 3, the tubular housing 100 is designed for an elongate lighting device. Accordingly, the tubular housing 100 is also elongate, e.g., to extend along a first axis Yi.

[0064] It will be apparent that the tube (of the tubular housing) is formed from the stack of layers, with the hollow interior of the tube being formed from the interior housing volume 190.

[0065] The tubular housing 100 may take any suitable cross-sectional shape. The cross- sectional shape is a shape of the tubular housing (and specifically of the interior housing volume) in a first plane pi orthogonal to the first axis Yi. Thus, the first axis Yi is normal to the first plane pi.

[0066] In this illustrated example, the tubular housing 100 has a rectangular cross- sectional shape. However, other examples will be apparent to the skilled person and may depend upon the specific use-case scenario for the tubular housing. Alternative examples of cross-sectional shapes are provided later in this disclosure.

[0067] Each layer of the stack of layers may be formed from or using cellulose fiber material. Cellulose fiber material (i.e., plant-derived fibers) is any material formed from cellulose fibers. It is well known how cellulose fibers can be derived from bark, wood, stems, leaves or any other part of a plant. This provides a tubular housing made of sustainable material, helping to reduce the carbon footprint of the manufacture of tubular housing for elongated lighting devices, such as luminaires. To further reduce the carbon footprint of the manufacture of tubular housing for elongated lighting device, the cellulose fiber material can be made of or partially made of recycled paper.

[0068] Approaches for forming a reflective layer formed from or using cellulose fiber material are readily apparent to the appropriately skilled person. By way of example, the reflective layer may be formed form a white cellulose fiber material (such as white paper), which is designed to reflect light in a diffusive manner. As another example, the reflective layer may be formed from a cellulose fiber material and then coated with a reflective material or coating, examples of which are well known in the art (e.g., metallic coatings such as aluminum or silver, or polymer-based reflective coatings).

[0069] Preferably, the thickness of each (reflective and / or structurally supportive layer) layer is no less than 0.1 mm, e.g., no less than 0.15 mm. This improves an ease of manufacturing and improves a stability of the tubular housing.

[0070] As a working example, the thickness of each reflective layer may be between 0.15 mm and 0.25 mm, e.g., between 0,175 mm and 0.225 mm. Similarly, the thickness of each structurally supportive layer may be between 0.25 mm and 0.75 mm, e.g., between 0.3 mm and 0.6 mm. The precise thickness of the layers may depend, for instance, on the particular use case scenario and / or availability of material.

[0071] In preferred examples, the number of structurally supporting layers is less than 20, e.g., less than 15. This reduces a material cost for producing the tubular housing 100.

[0072] In preferred examples, the number of structurally supporting layers is greater than 3, e g., 5 or more. This helps ensure sufficient strength for the tubular housing 100 to support the light emitting element(s), e.g., without the need of any additional mounts or supports.

[0073] As a working example, the number of structurally supporting layers may be between 5 and 10. This helps ensure that, for structurally supporting layers formed from cellulose fiber material and having a thickness of between 0.25 mm and 0.75 mm, that there is sufficient structural support for supporting the light emitting element(s), e.g., without the need for any additional mounts or supports.

[0074] Preferably, the reflective layer is separable from the one or more structurally supporting layers (e.g., if they are adhered together, they may be separable using adhesive remover, such as isopropyl). This improves a recyclability of the elongate lighting device, e.g., as it may be required to recycle layers of different material using different techniques or processes.

[0075] Figure 4 provides a cross-sectional view of an elongate lighting device 4 comprising a proposed tubular housing 100. Figure 5 provides a perspective view of the elongate lighting device 4.

[0076] The elongate lighting device further comprises a light emitting element 460. The light emitting element 460 is an elongate light emitting element and is positioned opposite the aperture(s) 150 formed in the tubular housing 100.

[0077] The elongate lighting device 4 may further comprise a mount 415. The mount may be configured to provide structural support to the light emitting element 460. The mount 415 may also comprise a corresponding mount aperture 416 that overlays or aligns with the aperture 150 of the tubular housing 100. The mount may be readily omitted in some examples.

[0078] In some examples, the mount 415 comprises a collimator, beam-shaper or reflector configured to control the direction of light emitted by the light emitting element 460. The shape of the mount 415 may therefore control or define the shape of a beam output by the elongate lighting device 4. In the illustrated example, the mount 415 takes the shape of a (portion of a) trapezoid. In such embodiments, the reflective layer 110 acts to improve the efficiency of the elongate lighting device, e.g., to reduce the absorption of stray light by the tubular housing.

[0079] The elongate lighting device may further comprise a light control layer 470, such as a diffuser, lens and / or other light filter (e.g., color filter) that covers the aperture. In particular, the diffuser may be positioned between the aperture and the light emitting element 460, such that light emitted by the light emitting layer undergoes diffusion, beam-shaping and / or filtering by the light control element 470.

[0080] The light control layer may comprise a planar sheet of material that is inserted into the tubular housing 100 to cover the aperture 150. Examples of suitable sheets of material for performing light control are well established in the art.

[0081] The present disclosure also provides a method or mechanism for producing the tubular housing previously disclosed.

[0082] Figures 6 to 9 illustrate the outcome of steps performed according to one proposed method for producing the tubular housing. It will be apparent that the proposed method is for producing a tubular housing for a light emitting element of an elongate lighting device that extends along a first axis. As illustrated in Figure 6, the method comprises providing a mold 600. The shape of the mold defines the shape of the interior housing volume for the elongate lighting device. The method also comprises a step of winding a reflective layer 110 (of flexible material) about the mold 600, e.g., partially or at least one time. In the illustrated example, the reflective layer is wrapped to form a single winding around the mold 600.

[0083] Subsequently, as illustrated in Figures 7 and 8, the method comprises providing one or more structurally supporting layers 120 about the reflective layer 110. This creates a stack of layers comprising the reflective layer and the one or more structurally supporting layers.

[0084] As illustrated in Figure 7, this step can be performed by winding a (single) piece of structurally supporting material about the reflective layer. The winding may be performed one or more times. In the illustrated example, the winding is performed one and a half times, to provide a full or complete wrap of the structurally supporting material about the reflective layer and one partial wrap.

[0085] As illustrated in Figure 8, the structurally supporting material may then be secured or adhered to form the stack of layers.

[0086] Similarly, the reflective layer 110 may be adhered to the structurally supporting layer(s). This can be performed, for instance, by applying adhesive to the reflective layer before providing the structurally supporting layer on top of the reflective layer. Of course, adhesive may also / otherwise be provided to the structurally supportive layer(s) before they provided on top of the reflective layer(s).

[0087] An alternative approach to providing the one or more structurally supporting layers is to, for instance, dispense a pulp around the reflective layer and then press, heat, dry or otherwise set the pulp so that it solidifies and forms the structurally supporting layer(s).

[0088] As illustrated in Figure 9, the method may then comprise or perform a step of disengaging the mold from the stack of layers to thereby produce the tubular housing for the light emitting element. More particularly, disengaging the mold may comprise removing or extracting the mold from the stack of layers.

[0089] Afterwards, the method may comprise or perform a step of cutting or punching one or more apertures 150 through the stack of layers to define one or more light exit windows for the elongate lighting device. The outcome of this step is also illustrated in Figure 9.

[0090] It has been identified that removal of the mold from the interior housing volume may be difficult, e g., if the reflective layer and / or structurally supporting layer(s) is / are tightly wound around the mold. To improve the ease of removing the mold from the interior housing volume, the mold may be moveable between a first configuration and a second configuration. The shape of the mold is smaller when in the second configuration than in the first configuration. More particularly, the shape of the mold in the (first) plane orthogonal to the (first) axis along which the elongate tubular housing extends may be smaller when in the second configuration than when in the first configuration.

[0091] Of course, the steps of winding the reflective layer and providing the one or more structurally supporting layers about the mold are performed when the mold is in the first configuration. Correspondingly, the step of disengaging the mold comprises moving the mold from the first configuration to the second configuration; and extracting the mold from the interior housing volume.

[0092] In one example, the mold is collapsible so as to facilitate the movement between the first configuration and the second configuration.

[0093] In particular, the mold may be formed from two portions that can be moved with respect to one another. A fixing mechanism (e.g., a screw or clamp) may fix the two portions to form the mold in the first configuration. When the fixing mechanism is released, the mold may fall, collapse such that the two portions intermesh with one another.

[0094] By way of example, one portion of the mold may comprise an elongate aperture or track through which a protrusion of the other portion of the mold may move. The protrusion may be fixed in a first position along the track so as to fix the mold in the first configuration. The protrusion may be moved to a second position along the track so as the move the mold to the second configuration (after being released from the first configuration).

[0095] Other appropriate arrangements or designs for facilitating the movement of a mold between the first and second configurations will be apparent to the skilled person, e.g., those that use one or more scissor mechanisms; inflatable bladders; and / or actuators.

[0096] It will be appreciated that there is also proposed a method for producing a lighting device comprising, performing any previously described method for producing an (elongate) tubular housing and; and after disengaging the mold from the stack of layers, inserting the light emitting element into the interior housing volume. This may produce the lighting device 4 illustrated in Figures 4 and 5.

[0097] As previously explained, the shape of the mold (used to create the tubular housing) defines the shape of the interior housing volume. In the scenario illustrated by Figures 6 to 9, the mold has a rectangular cross-sectional shape. Figure 10 illustrates an alternative lighting device 10 in which the mold used to produce the elongate tubular housing 1000 had a triangular cross-sectional shape.

[0098] The lighting device 10 may be produced using a similar technique to that previously described, and thereby comprises a tubular housing 1000 formed from a stack of layers, including a reflective layer 1010 and at least one structurally supporting layer 1020, that bounds an interior housing volume 1090. The shape of the interior housing volume 1090 is triangular (in a plane orthogonal to an axis in which the elongate tubular housing 1000 stretches).

[0099] The tubular housing 1000 further comprises an aperture 1050, a light control layer 1070 and two (elongate) light emitting element 1061, 1062.

[0100] Figure 11 illustrates another alternative lighting device 11 in which the mold used to produce the elongate tubular housing 1100 had a tunnel -like cross-sectional shape.

[0101] The lighting device 11 may be produced using a similar technique to that previously described, and thereby comprises a tubular housing 1100 formed from a stack of layers, including a reflective layer 1110 and at least one structurally supporting layer 1120, that bounds an interior housing volume 1190. The shape of the interior housing volume 1190 is triangular (in a plane orthogonal to an axis in which the elongate tubular housing 1100 stretches).

[0102] The tubular housing 1100 further comprises an aperture 1150, a light control layer 1170 and at least one light emitting element 1160.

[0103] Figure 12 illustrates yet another alternative lighting device 12 in which the mold used to produce the elongate tubular housing 1200 had a trapezium cross-sectional shape.

[0104] The lighting device 12 may be produced using a similar technique to that previously described, and thereby comprises a tubular housing 1200 formed from a stack of layers, including a reflective layer 1210 and at least one structurally supporting layer 1220, that bounds an interior housing volume 1290. The shape of the interior housing volume 1290 is triangular (in a plane orthogonal to an axis in which the elongate tubular housing 1200 stretches).

[0105] The tubular housing 1200 further comprises an aperture 1250, a light control layer 1270 and at least one light emitting element 1260.

[0106] In the context of the present disclosure, a reflective layer is a layer that is designed to reflect a majority, nearly all or all received light that is incident thereon. In particular, a reflective layer may be a layer that reflects no less than 60% of light incident thereon (from within the interior housing volume) across all angles at which light may be incident, preferably no less than 75%, more preferably no less than 90%, even more preferably no less than 98%.

[0107] 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.

[0108] 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.

[0109] 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.

[0110] Any reference signs in the claims should not be construed as limiting the scope.

Claims

CLAIMS:

1. An elongate lighting device (4, 10, 11, 12) comprising a tubular housing (100, 1000, 1100, 1200) and a light emitting element (460, 1060, 1160, 1260), the tubular housing extending along a first axis (Yl) and comprising a side wall comprising a stack of layers, wherein the stack of layers comprises a reflective layer (110, 1010, 1110, 1210) stacked upon one or more structurally supporting layers (120, 1020, 1120, 1220), wherein: the stack of layers bound an interior housing volume (190, 1090, 1190, 1290) in which the light emitting element is positioned; and the reflective layer faces the interior housing volume; wherein the sidewall comprises one or more apertures (150, 1050, 1150, 1250) through the stack of layers to define one or more light exit windows for the elongate lighting device; wherein at least one layer of the one or more structurally supporting layers (120, 1020, 1120, 1220) is formed from cellulose fiber material.

2. The elongate lighting device (4, 10, 11, 12) of claim 1, wherein each layer of the one or more structurally supporting layers (120, 1020, 1120, 1220) is formed from cellulose fiber material.

3. The elongate lighting device (4, 10, 11, 12) of claim 1, wherein the reflective layer is a foil of aluminum or aluminum alloy.

4. The elongate lighting device (4, 10, 11, 12) of claim 1, wherein the reflective layer (110, 1010, 1110, 1210) is adhered to the one or more structurally supportive layers, and when there are more than one layer of the one or more structurally supportive layers, such layers are adhered to each other to form the stack of layers.

5. A method for producing a tubular housing (100, 1000, 1100, 1200) for an elongate lighting device (4, 10, 11, 12) of any of claims 1 to 4, the method comprising:providing a mold (600) defining a shape of an interior housing volume (190, 1090, 1190, 1290) for the elongate lighting device; winding a reflective layer (110, 1010, 1110, 1210) of flexible material about the mold; providing one or more structurally supporting layers (120, 1020, 1120, 1220) about the reflective layer wound around the mold, to thereby create a stack of layers comprising the reflective layer and the one or more structurally supporting layers that bound the interior housing volume; disengaging the mold from the stack of layers to thereby produce the tubular housing; and cutting or punching one or more apertures (150, 1050, 1150, 1250) through the stack of layers to define one or more light exit windows for the elongate lighting device.

6. The method of claim 5, wherein the mold has a non-rectangular cross-sectional shape in a first plane (pi), wherein the first axis is normal to the first plane.

7. The method of any of claim 5 or 6, wherein the mold is moveable between a first configuration, in which the mold has a first shape, and a second configuration, in which the mold has a second shape, smaller than the first shape, wherein: the steps of winding the reflective layer and providing the one or more structurally supporting layers about the mold are performed when the mold is in the first configuration; and the step of disengaging the mold comprises: moving the mold from the first configuration to the second configuration; and extracting the mold from the interior housing volume.

8. The method of claim 7, wherein the first shape has a greater size in a first plane (pi), for which the first axis (Yi) is normal to the first plane, than the second shape.

9. The method of claim 7 or 8, wherein the mold is collapsible so as to facilitate movement between the first configuration and the second configuration.

10. The method of any of claims 5 to 9, further comprising adhering the reflective layer (110, 1010, 1110, 1210) to the one or more structurally supporting layers (120, 1020, 1120, 1220).

11. The method of any of claims 5 to 10, wherein providing the one or more structurally supporting layers comprises winding a piece of structurally supporting material about the mold to form the one or more structurally supporting layers.

12. The method of any of claims 5 to 11, wherein the one or more structurally supporting layers comprises a plurality of structurally supporting layers.

13. The method of any of claims 5 to 12, wherein the reflective layer and each of the one or more structurally supporting layers is formed from cellulose fiber material.

14. A method for producing an elongate lighting device (4, 10, 11, 12) of any of claims 1 to 4, comprising: performing the method of any of claims 4 to 13; and after disengaging the mold from the stack of layers, inserting a light emitting element (460, 1060, 1160, 1260) into the interior housing volume.

15. The method of claim 14, further comprising coupling the light emitting element to the reflective layer.

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