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Technical Field

The description relates to lighting devices.

One or more embodiments may refer to lighting devices employing electrically-powered light radiation sources such as solid-state sources, e.g. LED sources.

Technological Background

In various lighting technology applications (e.g. for highlighting exhibits - "accent lighting" - or for cove lighting) lighting devices may be employed which comprise flexible LED modules adapted to provide a diffused light with omnidirectional distribution, and/or, at least in some cases, to offer a protection against external agents such as dust or water, e.g. an IP degree protection.

Meeting such use requirements may prove a challenge .

For such purposes, for example, flexible modules may be used which provide IP protection and are equipped with top-emitting LEDs, together with electronic components arranged on one side of a Flexible Printed Circuit (FCP) .

The latter may be produced starting from a non- transparent base material (e.g. polyimide, PI) having on one side electrically conductive lines, e.g. of copper (Cu) or silver (Ag) , adapted to bring about electrical interconnection while also supporting heat transfer. Such electrically conductive lines may have a matt appearance and may be provided with solder resist layers which in turn may be matt or reflective. Two or more such LED modules may then be mounted onto different sides of one single mechanical support, or onto different supports, so as to obtain the desired radiation pattern. This solution may prove rather complex as regards installation, and on the whole the lighting device may not be as slim as it is supposed to be .

Another solution may envisage the use of e.g. IP protected flexible modules, featuring side-emitting LEDs (side LEDs) assembled on one side of a standard FPC . For example, the LEDs may be mounted so that two adjoining devices have the respective Light Emitting Surfaces (LESs) oriented in different directions. A drawback of such a solution may consist in the fact that, at least currently, side LEDs are available only in a rather narrow range of Correlated Color Temperature (CCT) , e.g. approximately from 2000°K to 6500°K.

Object and Summary

One or more embodiments aim at overcoming the previously outlined limitations.

According to one or more embodiments, said object may be achieved thanks to a method having the features set forth in the claims that follow.

One or more embodiments may also concern a corresponding lighting device.

The claims are an integral part of the technical teaching provided herein with reference to the embodiments .

In one or more embodiments, a (single) flexible LED module, e.g. employing standard top-emitting LEDs or Chip-Scale-Package (CSP) LEDs, enables the achievement of a wide range of colours and CCTs by being assembled onto a flexible printed circuit (e.g. FCP) which may be shaped in 3D, e.g. by wrapping it around a core or a winding spindle.

In one or more embodiments, a desired shape may be imparted to said assembly, so as to obtain an omnidirectional radiation distribution, the possibility being given of embedding said assembly into a 3D flexible structure, which may also contain diffusive particles and/or may act as a protection (e.g. IP protection) member.

Brief Description of the Figures

One or more embodiments will now be described, by way of non-limiting example only, with reference to the annexed Figures, wherein:

- Figure 1, comprising three parts respectively denoted as a) , b) and c) , exemplifies possible embodiments ,

Figure 2, comprising four parts respectively denoted as a) , b) , c) and d) , exemplifies possible embodiments,

Figure 3, comprising four parts respectively denoted as a) , b) , c) and d) , exemplifies possible embodiments ,

Figure 4, comprising four parts respectively denoted as a) , b) , c) and d) , exemplifies possible embodiments, and

- Figure 5, comprising two portions respectively denoted as a) and b) , exemplifies embodiments.

It will be appreciated that, for clarity and simplicity of illustration, the various Figures may not be drawn to the same scale.

Detailed Description

In the following description, numerous specific details are given in order to provide a thorough understanding of various exemplary embodiments. The embodiments may be practiced without one or several of the specific details, or with other methods, components, materials, etc. In other instances, well- known structures, materials, or operations are not shown or described in detail to avoid obscuring the various aspects of the embodiments.

Reference throughout this specification to "one embodiment" or "an embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment. Thus, the possible appearances of the phrases "in one embodiment" or "in an embodiment" in various places throughout this specification are not necessarily all referring exactly to the same embodiment. Furthermore, particular features, structures, or characteristics may be combined in any suitable manner in one or more embodiments.

The headings provided herein are given for convenience only, and therefore do not interpret the extent of protection or the scope of the embodiments.

In the Figures, reference 10 denotes a lighting module including a substrate 12 which may consist e.g. of an elongated, e.g. ribbon-like, Flexible Printed Circuit (FPC) .

In one or more embodiments, substrate 12 may carry electrically-powered light radiation sources, e.g. solid-state lighting sources such as LED sources 14.

Such ribbon-shaped modules (which are sometimes referred to as "flex" modules) are known in the art, which makes it unnecessary to provide herein a more detailed description thereof.

Portion b) of Figure 1 shows that, in one or more embodiments, a module 10 as shown in portion a) of the same Figure 1 may be wound in a helical shape around an axis X10, e.g. by wrapping it around an elongated core (spindle) 16, having e.g. a cylindrical or prism shape.

In one or more embodiments, core 16 may be flexible and/or have a convex regular base, i.e. may be a parallelepiped having a regular convex polyhedral base. The assembly thus formed may then be coupled with a tubular housing or shell 18, e.g. of a light- permeable (e.g. transparent), optionally flexible material .

Both core 16 and housing 18 may consist of a silicone material, which may simplify coupling via co- moulding or co-extrusion.

In one or more embodiments it is thus possible to obtain an elongate lighting device which, thanks to the arrangement of sources 14 (in the following, for brevity, we will mainly refer to LED sources) along a helical trajectory extending around axis X10, enables the achievement, in use, of an omnidirectional light emission distribution around axis X10.

This is due to the fact that lighting module 10 extends along axis X10 with an array of radiation sources 14 arranged thereon, which therefore may project light radiation radially outwardly of axis X10.

The elements shown in Figure 1, and specifically the finished lighting device exemplified in portion c) , may have an indefinite length and may be optionally cut to length depending on application needs, the possibility being given of associating, at the end of the thus-formed device, one or more electrical connectors and/or end caps, so as to impart protection (e.g. IP protection) features to the device as a whole.

In one or more embodiments, LEDs 14 may be top- emitting LEDs, optionally Chip-Scale-Package (CSP) LEDs, adapted to be assembled onto a standard FPC 12. The basic material of the circuit may be polyimide (PI) or a matt polyethylene naphtalate (PEN) with electrically conductive lines e.g. of copper (Cu) or silver (Ag) , the surface whereof may optionally be covered with highly reflective material, e.g. a white solder resist. In one or more embodiments, circuit 12 may be light-permeable (e.g. transparent) and may include a transparent basic material (e.g. polycarbonate, PC, polyethylene terephthalate, PEN) with optionally matt, silver- or copper-based electrically conductive lines.

In one or more embodiments, the electrically conductive lines may have a narrow section, and/or may be transparent conductive lines, e.g. based on Transparent Conductive Oxides (TCOs) or Transparent Conductive Inks (TCIs), with the optional application of a transparent solder resist.

To this end (and specifically, in order to prevent conductive lines from hampering the light radiation of sources 14), the use may be envisaged of screen printing or Liquid Photo Imageable (LPI) techniques on the side of substrate 12 carrying the electrically conductive lines.

In one or more embodiments, an adhesive material (e.g. a tape) may be applied onto the surface of circuit 12 opposed to the side which carries the LEDs 14 (and optional associated electronic components, which are not visible in the drawings) , so that module 10 may adhere to core 16 once it has been wound thereon .

In one or more embodiments, core 16 and/or housing

18 may embed fillers with thermal dissipation features (e.g based on A1N or BeO) , so as to favour the dissipation of heat generated by sources 14 in operation .

In one or more embodiments, core 16 and/or housing

18 may embed fillers with light dissipation features (e.g. A1 ₂ 0 ₃ particles), so as to favour a uniform emission of light radiation from the device.

In one or more embodiments, core 16 and/or shell 18 may be flexible. Figure 2 and the following Figures exemplify embodiments which may include parts or members similar or comparable to parts or members already described with reference to Figure 1. In the Figure 2 and the following Figures, such parts or members are denoted with the same reference numbers already used for Figure 1. For the sake of brevity a corresponding description will not be repeated herein.

In one or more embodiments as exemplified in Figure 2, the steps exemplified in parts a), b) and c) of Figure 2 involve the same operations described for Figure 1.

In one or more embodiments, as exemplified in Figure 2, the (e.g. adhesive) connection between module 10 and core 16 may be omitted. In this way, after the application/ forming of housing 18, the core or winding spindle 16 may be removed, therefore obtaining a lighting device as exemplified in part d) of Figure 2, wherein module 10, wrapped along a helical trajectory, is supported (only) by housing 18. Also in this case, housing 18 may be obtained via co-moulding or co- extrusion, so that sources 14 and circuit 12 are anchored to housing 18.

For example, in one or more embodiments as exemplified in Figure 2, core 16 may be formed and/or treated so that it exhibits low adherence features, both with respect to module 10 wrapped thereon and with respect to housing 18.

For example, in one or more embodiments, core 16 may be treated e.g. with a lubricating or non-stick material, so as to make the subsequent removal of core 16 easier (sequence of parts c) and d) of Figure 2) .

Again by way of example, in one or more embodiments, core 16 (which is destined to be removed) may comprise a rigid, e.g. metal, e.g. aluminium-based, material, which in itself exhibits low adherence properties with respect to the material of housing 18.

As regards both the choice of materials and other possible features (e.g. the application of connectors / end caps), the previous statements regarding the embodiments exemplified in Figure 1 also apply to the embodiments exemplified in Figure 21.

Generally similar observations may also apply to one or more embodiments as exemplified in Figure 3: in this case, in order to produce a circuit 12, a thermoformable material may be used so that, once it has been wound onto core or spindle 16, module 10 (circuit 12 with sources 14) may be subjected to a thermoforming treatment and may retain the helical shape also after the removal of core 16 (which comprises either a flexible or a rigid material: the previous statements regarding the embodiments exemplified in Figure 2 also apply to this situation) so as to be coupled with housing 18.

In one or more embodiments, in order to impart thermoformability to module 10, circuit 12 may comprise a material based on polyethylene terephthalate (PET) , polycarbonate (PC) or poly methyl acrilate (PMMA) , which may be subjected to thermoforming at temperatures of approximately 150°C - 180°C.

A comparison of parts d) of Figures 2 and 3 shows that, as in the embodiments exemplified in Figure 1, the presently exemplified embodiments comprise a lighting module 10 which extends along axis X10 with an array of radiation sources 14 arranged thereon, so as to project light radiation radially outwardly of axis X10.

Also in this case, as regards both the choice of materials and other possible features (e.g. the application of connectors / end caps), the previous statements regarding the embodiments exemplified in Figures 1 and 2 may also apply to the embodiments exemplified in Figure 3.

Figure 4 exemplifies embodiments wherein, instead of an elongate ribbon-like shape, module 10 may have a general laminar configuration, with a sheet substrate 12 and LEDs 14 arranged on substrate 12 in a bidimensional , e.g. matrix-shaped, array.

In one or more embodiments as exemplified in Figure 4, circuit 12 may comprise electrically conductive lines 12a, which may be formed via laser structuring techniques and which may make the winding of module 10 around core 16 easier.

In one or more embodiments, electrically conductive lines 12a may be meander-shaped (e.g. along paths comprising sinusoidal or semi-sinusoidal portions) in a geometry similar to e.g. coronary angioplasty stents. In one or more embodiments, after wrapping module 10 onto core 16, the production of the lighting device may proceed in the same ways as previously exemplified, i.e. by coupling housing 18, by optionally applying connectors / end caps, etc.

Figure 4 exemplifies embodiments which, except for the different shape of module 10, essentially correspond to the embodiments exemplified in Figure 1. It will be appreciated that the technical teachings represented in Figure 4 may also be applied to embodiments as exemplified in Figures 2 and 3.

In one or more embodiments, therefore, a laminar module 10 may be wrapped as exemplified in Figure 4 onto a core 16 which, instead of remaining in position as exemplified in Figure 4, is removed as exemplified in Figure 2, the module 10 being coupled with housing 18 so that it may be supported by the latter.

In the same way, the substrate 12 of a laminar module 10 as exemplified in Figure 4 may be comprised of a thermoformable material as exemplified in Figure 3, and thus module 10 is subjected to thermoforming and is coupled with housing 18 after the removal of core 16.

With the embodiments exemplified in Figure 4 (with the possible application thereto of the teachings of the embodiments exemplified in the previous Figures), the lighting module 10 may extend along axis X10 with an array of radiation sources 14 arranged thereon, so as to project light radiation radially outwardly of axis X10.

Also in this situation, as regards both the choice of materials and other possible features (e.g. the application of connectors / end caps), the previous statements regarding the embodiments exemplified in Figures 1 to 3 may also apply to the embodiments exemplified in Figure 4.

Figure 5 exemplifies embodiments wherein sources (e.g. LED sources) 14 may be mounted on both sides of a circuit (e.g. a FPC) 12, e.g. a double-layer circuit, the housing 18 being subsequently co-moulded or co- extruded onto module 10. In one or more embodiments, both surfaces of circuit 12 may feature electrically conductive lines which may be connected e.g. through so-called "vias" which bring about, e.g. after filling and capping treatments, the interconnection of both electrically conductive layers on the opposed surfaces of circuit 12.

By resorting to solutions also applicable to the embodiments of the previous Figures, electronic components may be soldered with a standard solder paste onto one side of circuit 12, and with a low-melt solder paste or with an electrically conductive adhesive material onto the other side of circuit 12, so that this subsequent operation does not impair the soldering effected on the first side of circuit 12.

One or more embodiments exemplified in Figure 5 may therefore involve, in the same way as the embodiments exemplified in the other Figures, the following operations:

- providing a lighting module 10 extending along an axis X10 with an array of electrically-powered light radiation sources (e.g. LEDs 14) arranged thereon, to project light radiation radially outwardly of said axis X10, and

- coupling, e.g. via co-moulding or co-extrusion, with said lighting module 10 having said light radiation sources 14 arranged thereon, a tubular housing 18 of light permeable material.

Without prejudice to the basic principles, the implementation details and the embodiments may vary, even appreciably, with respect to what has been described herein by way of non-limiting example only, without departing from the extent of protection.

The extent of protection is defined by the annexed claims .