WO2009068471A1

WO2009068471A1 - Lighting device

Info

Publication number: WO2009068471A1
Application number: PCT/EP2008/065929
Authority: WO
Inventors: Sergio Macchioni
Original assignee: Sergio Macchioni
Priority date: 2007-11-26
Filing date: 2008-11-20
Publication date: 2009-06-04
Also published as: ITVR20070172A1

Abstract

A lighting device (1), comprising an elongated body (2), which supports at least one light source (3) which comprises a plurality of LEDs mutually spaced along the direction of longitudinal extension of the body (2), and defining at least one reflective surface (4) for the light emitted by the light source (3), the reflective surface (4) having a concavity that is directed toward the at least one light source (3), heat dissipation means (5) being further provided which are arranged on the elongated body (2) on the opposite side with respect to the reflective surface (4).

Description

LIGHTING DEVICE Technical Field

The present invention relates to a lighting device.

Background Art Lighting devices that use LEDs as a light source are currently widely used.

Generally, such LEDs are accommodated within a supporting body, which forms a parabolic surface for reflecting and directing the light emitted by the light source. Such reflecting surfaces have, as mentioned, a substantially cylindrical parabolic shape and in some case are associated with linear lenses.

Disclosure of the Invention

The aim of the present invention is to provide a new lighting device. Within this aim, an object of the present invention is to provide a lighting device that offers highly practical assembly.

Another object of the invention is to provide a lighting device that has a competitive production cost, so that its use is advantageous also from an economical standpoint. Still another object of the present invention is to provide a lighting device that has a very simple structure and is highly durable.

This aim, as well as these and other objects that will become better apparent hereinafter, are achieved by a lighting device, characterized in that it comprises an elongated body, which supports at least one light source of the LED type and forms at least one reflective surface for the light emitted by said at least one light source of the LED type, said reflective surface having a concavity that is directed toward said at least one light source, heat dissipation means being further provided which are arranged on said elongated body on the opposite side with respect to said reflective surface. Brief Description of the Drawings

Further characteristics and advantages of the invention will become better apparent from the description of some preferred but not exclusive embodiments of a lighting device according to the invention, illustrated by way of non-limiting example in the accompanying drawings, wherein:

Figure 1 is an exploded perspective view of a spotlight that uses a lighting device according to the invention;

Figure 2 is a perspective view of the elongated body shown in Figure 1 ; Figure 3 is a side elevation view of the elongated body;

Figure 4 is another side elevation view of a variation of the elongated body.

In the exemplary embodiments that follow, individual characteristics, given in relation to specific examples, may actually be interchanged with other different characteristics that exist in other exemplary embodiments.

Moreover, it is noted that anything found to be already known during the patenting process is understood not to be claimed and to be the subject of a disclaimer.

Ways of carrying out the Invention With reference to the figures, a lighting device, generally designated by the reference numeral 1 , comprises an elongated body 2, which supports at least one light source 3.

The elongated body 2, in particular, forms at least one reflective surface 4 for the light emitted by the light source 3 : such reflective surface 4 has a concavity that is directed toward the light source 3.

Means 5 for dissipating the heat produced by the light source 3 are further provided and are arranged on the elongated body 2 on the opposite side with respect to the reflective surface 4.

As shown, it is particularly convenient for the dissipation means 5 to be provided monolithically with the reflective surface 4. According to a preferred embodiment, the light source 3 comprises a plurality of LEDs 3b, which are spaced one another along the direction of longitudinal extension of the elongated body 2 and are supported by a printed circuit 3 a. Advantageously, the elongated body 2 has a constant transverse cross-section, and for this reason it has been found that it is particularly convenient to provide the elongated body by means of the process for extruding a profile.

With particular reference to what is shown in Figure 2, the reflective surface 4 has a plane of symmetry that passes through the light source 3.

However (as shown in Figure 3), nothing prevents the reflective surface 4 from being constituted by two reflective portions 4a and 4b arranged asymmetrically with respect to a plane that passes through the light source 3. Conveniently, it is possible to deposit, especially at the reflective surface 4, fluorescent or phosphorescent molecules by using different methods and technologies of deposition, including sol gel technology, vacuum plasma technology, or atmospheric plasma technology.

Such molecules react to the radiation emitted by some LEDs (typically a radiation with a wavelength of approximately 465 run defined in the visible range as blue which, in white, is used to excite the phosphors and remains as invisible background radiation) generating other photons (in addition to the ones emitted by the phosphors excited by the light source) and accordingly determining a greater luminous flux. Of course, the use of other molecules that utilize the same principle (radiation/excitation) is not excluded.

Conveniently, the heat dissipation means 5 comprise a plurality of fins 6, which extend parallel to the direction of longitudinal extension of the elongated body 2. The elongated body 2 further forms a longitudinally elongated receptacle 2a for the light source 3 and more precisely for a supporting element for said light source.

In the specific case, the light source 3 is constituted by a flat board 3a (typically a printed circuit), which supports a plurality of mutually spaced LEDs 3b: in this particular case, the receptacle 2a is conveniently constituted by an elongated slot, in which it is possible to insert in a slider- like fashion the flat board 3 a, or is constituted by a flat abutment surface with which it is possible to couple, for example by way of the interposition of a layer of heat-conducting adhesive, the surface of the supporting element for the flat board 3a.

As an alternative, the flat board 3 a can be fixed by means of screws or also by applying a layer of heat-conducting paste of "pad" or of thermoconductive, bi-adhesive webs.

It is of course possible to provide other methods for fixing the light source 3, for example by using screws that can be coupled to holes provided by means of a machine tool.

In this regard, it has been found that it is particularly advantageous to use, as a supporting element, a sheet-like element made of metal (for example aluminum), on a first face of which the flat board 3a is deposited or generally coupled. The opposite face of the sheet-like element is instead coupled to the flat abutment surface or to the bottom surface of the receptacle 2a formed on the elongated body 2, so that the heat generated by the light source 3 (and in particular by the LEDs 3b) can migrate through the supporting body to be dissipated by the heat dissipation means 5 provided on the elongated body 2.

According to a practical example of use of the invention, shown in Figure 1 , closure bodies 7 may be fixed to the ends of the elongated body 2 by means of fixing screws 30.

The closure bodies 7 also have the task of retaining a closure panel 8 in a downward region. Fluorescent or phosphorescent molecules can be deposited also at the outer surface of the closure panel 8 (or likewise as fillers) within such panel and, as already explained earlier, behave in practice as additional photon sources. In this specific case, it has been observed experimentally that the presence of the fluorescent or phosphorescent molecules and the consequent generation of new photons "disturbs" (in a positive sense) the emission of the flux by the light source 3, attenuating in practice the dazzle effect determined by the use of light sources of the point-like type. Therefore, the block constituted by the elongated body 2 and by the closure bodies 7 can be associated with a supporting frame 20 provided with a containment slot 21.

At least two locking wings 24 rise in particular from the containment slot 21 and cooperate with spring-operated locking means 22, which are jointly connected to the closure bodies 7 by using screws 30.

The spring-operated locking means 22 have elastically yielding portions 23, which are designed to be retained by snap action by the upper edges of the respective locking wings 24.

In practice it has been found that the invention has achieved its intended aim and objects in all of its embodiments.

In practice, the materials used, as well as the contingent shapes and dimensions, may be any according to requirements.

Of course, in order to ensure effective dissipation of the heat produced by the light source 3 through the dissipation means 5, it is convenient for the elongated body 2 to be made of metal, for example aluminum.

However, nothing prevents the use of different materials, even of a polymeric type and therefore having a far lower production cost. In this case, it is essential to perform a surface treatment of the material for example by means of a method such as the one known commercially as "Cold Spray". This technique consists in "spraying" onto the surface to be treated, by using a particular gun or nozzle, a high-pressure jet of air at high temperature (approximately 800⁰C) so as to deposit nanostructured micromolecules of material (which in this case is a heat conductor). The advantage of this method (as well as of similar methods such as

"flame spraying" or "metalization") is to allow to use a base material (which is inexpensive) on which a layer of noble material is applied which has the required characteristics (for example copper in the region of dissipation and/ or aluminum in the regions affected by reflection). This treatment is particularly efficient, since the heat is distributed through the surface and not through the mass.

As an alternative the elongated body 2 can be manufactured by extrusion of polymeric material (that can be charged with thermoconductive material such as ceramic charges, metallic charges or nanotubes) and, in this particular case, the "Cold Spray" treatment would not be necessary, and by extrusion of white color ceramic material which has a good reflectivity coefficient.

Moreover, all the details may be replaced with other technically equivalent elements. The disclosures in Italian Patent Application no. VR2007A000172, from which this application claims priority, are incorporated herein by reference.

Where technical features mentioned in any claim are followed by reference signs, those reference signs have been included for the sole purpose of increasing the intelligibility of the claims and accordingly such reference signs do not have any limiting effect on the interpretation of each element identified by way of example by such reference signs.

Claims

1. A lighting device (1), characterized in that it comprises an elongated body (2), which supports at least one light source (3) which comprises a plurality of LEDs mutually spaced along the direction of longitudinal extension of said body (2), and forming at least one reflective surface (4) for the light emitted by said at least one light source (3), said reflective surface (4) having a concavity that is directed toward said at least one light source (3), heat dissipation means (5) being further provided which are arranged on said elongated body (2) on the opposite side with respect to said reflective surface (4).

2. The lighting device according to claim 1, characterized in that said elongated body (2) has a constant transverse cross-section.

3. The lighting device according to one or more of the preceding claims, characterized in that said reflective surface (4) has a plane of symmetry that passes through said at least one light source (3).

4. The lighting device according to one or more of the preceding claims, characterized in that said reflective surface (4) comprises two reflective portions (4a, 4b) arranged asymmetrically with respect to a plane that passes through said at least one light source (3).

5. The lighting device according to one or more of the preceding claims, characterized in that said heat dissipation means (5) comprise a plurality of fins (6) that extend parallel to said direction of longitudinal extension of said elongated body (2).

6. The lighting device according to one or more of the preceding claims, characterized in that said elongated body (2) comprises a profile.

7. The lighting device according to one or more of the preceding claims, characterized in that said elongated body (2) forms a longitudinally elongated receptacle (2a) for said at least one light source (3).

8. The lighting device according to one or more of the preceding claims, characterized in that said light source (3) comprises a plurality of LEDs, which are mutually spaced along the direction of longitudinal extension of said elongated body (2) and are supported by a printed circuit (3 a), said printed circuit being supported by a supporting element made of conducting material which can be coupled to a flat abutment surface formed on said elongated body (2) or to the bottom surface of said receptacle (2a).

9. The lighting device according to one or more of the preceding claims, characterized in that it comprises closure bodies (7), which can be associated with the longitudinal ends of said elongated body (2) by means of fixing screws (30).

10. The lighting device according to claim 9, characterized in that said closure bodies (7) are adapted to retain, in a downward region, a closure panel (8) of said light source (3).

1 1. The lighting device according to one or more of the preceding claims, characterized in that the block that comprises said elongated body (2) and said closure bodies (7) can be associated with a supporting frame (20) provided with a containment slot (21).

12. The lighting device according to claim 11, characterized in that at least two locking wings (24) rise from said containment slot (21) and are adapted to cooperate with spring-operated locking means (22) jointly connected to said closure bodies (7).

13. The lighting device according to claim 12, characterized in that said spring-operated locking means (22) have respective elastically yielding portions (23) that are designed to be retained with a snap action by the upper edges of the respective locking wings (24).

14. The lighting device according to one or more of the preceding claims, characterized in that it comprises, substantially at at least one portion of the reflective surface (4) and/or said closure body (7), a layer of fluorescent or phosphorescent molecules, which are adapted to react to the invisible radiation emitted by said light source (3) in order to generate photons and develop a more intense luminous flux.

15. The lighting device according to one or more of the preceding claims, characterized in that said elongated body (2) is made of a polymeric material which is covered by at least one layer of conducting material at the dissipation means (5) and by at least one layer of reflective material at said i at least one reflective surface (4).