WO2011080767A1

WO2011080767A1 - "lighting device"

Info

Publication number: WO2011080767A1
Application number: PCT/IT2009/000581
Authority: WO
Inventors: Flavio Turcatel
Original assignee: AR-KY Srl
Current assignee: AR-KY Srl
Priority date: 2009-12-28
Filing date: 2009-12-28
Publication date: 2011-07-07
Anticipated expiration: 2012-06-28

Abstract

The present invention refers to a lighting device (100) including a support (2) on which is fastened a printed circuit (3) provided with at least one light source (6) and at least one optical unit (4, 5) capable of splitting and reflecting/refracting the light given off by said light source, characterized in that said at least one optical unit includes at least one first optical element (4) provided with a first surface (10) turned toward said light source (6) and including a series of prisms (12) suitable for receiving said light, splitting it into light beams and aligning them substantially parallel along the axis (Y-Y) perpendicular to the plane of said first surface (10) and of a second surface (11 ) opposite said first surface and including concavities (21 ) suitable for refracting said light beams, thus obtaining an opening of the light cone emitted by said source (6), said optical unit including in addition a second optical element (5) provided with a first surface (24) turned toward said at least one first optical element (4) and including refractive elements (26) distributed transversally with respect to the longitudinal axis (A-A) of said at least one second optical element (5) in at least one peripheral portion (27), in which said refractive elements are in general cusp-shaped and are suitable to direct said light beams outwardly from the device, and in at least one central portion (28) including concavities (32, 33) suitable to further refract said light beams.

Description

"LIGHTING DEVICE"

DESCRIPTION

TECHNICAL FIELD OF INVENTION

The present invention refers to a lighting device including a printed circuit on which is anchored a light source of LED type and an optical unit placed at a fixed distance from said light source. In particular, the device is a lamp for street lighting, a headlight for vehicles or a lamp for lighting external or internal spaces such as, for example, homes, industrial or commercial establishments.

BACKGROUND OF INVENTION

In general, lighting devices, be they for street or internal lighting or for vehicles, have long been produced by making use of the collimating lens technology. Collimating lenses are positioned downstream of the light source and make it possible to cluster the individual light beams that irradiate in every direction from a light source to form substantially parallel beams of light perpendicular with respect to the plane of the source itself. A typical example of such lenses are the lenses of Fresnel type. In this manner, the lighting efficiency of the lamp can be advantageously increased, especially in situations in which the light must reach points that are far from its source and, at the same time, the lens maintains a limited thickness.

For what concerns street lighting lamps, that is, lamps installed on suitable light poles at a set height above street level and spaced for a predetermined distance along the side of the road, it is necessary to meet some regulatory provisions. In particular, in compliance with the most recent regulations, every street lamp must have a light beam wider than 120°. This angle is given by the ratio of height to interdistance of the lamps along the road. This ratio is normally 3.7; that is, for each metre in height of the lamp the distance between two adjacent lamps must be 3.7 metres.

The use of collimating lenses in the production of street lamps would therefore be considerably interesting due to the characteristics of compactness and lighting efficiency. Unfortunately, this type of lenses has a limit in the width of the light beam. In fact, it is well known that by accentuating the optical geometries it is also possible to achieve light beam widths greater than 120°, but with the marked inconvenience of drastically lowering the lighting efficiency of the light source. In other words, the ratio of the luminous flux before the passage through the lens with respect to the flux after the passage is very high.

To obviate this drawback, a proposed solution has been to direct the light sources with the corresponding lenses at different angles to avoid accentuating said optical geometries to the extreme and causing losses of efficiency. In particular, the lamps should have a lighting surface convexly curved downward, that is, toward the street, with light sources positioned along a circular arc.

This solution has considerable drawbacks. In the first place, the collimating lenses, as already explained, tend to concentrate the light beams and, therefore, can create dazzling effects.

In second place, at least in agreement with some regional regulations, such as those applied in the Italian region of Friuli Venezia Giulia, there must be no substantial light source above the lower light horizon from which the light is cast from a lamp. This condition is also called light pollution and occurs in fact with said street lamps. In fact, the convexity of the lighting surface presents, near the ends of the circular arc, light points positioned above the lower light horizon of the same lamp.

In addition, such convex arrangement of the light sources implies that the lenses and the relative printed circuits with the LEDs must be mounted on the lamp individually or in small groups and in any case as a unit. It follows that the production and the installation of the lamp are elaborate, with consequent high production costs. At the same time, this structure implies a greater risk of malfunctions caused by many electrical contacts, which make the assembly more delicate.

It has also been observed that the distribution of the illuminated area on the ground is uneven because there is a certain discontinuity between the different light sources.

Finally, the luminous flux on the ground is scattered due to the impossibility of directing it in a geometrical form such as to reproduce the road area to illuminate.

SUMMARY OF THE INVENTION

The technical problem at the basis of the present invention is therefore to devise a lighting device capable of obviating the drawbacks mentioned above.

This problem is solved by a lighting device having optical characteristics such as to obtain a luminous beam opening according to current requirements and/or regulations, optimal characteristics of homogeneity and efficiency of the same luminous beam, and a simplified structure that is easy to manufacture and reliable.

BRIEF DESCRIPTION OF THE FIGURES

The purpose of the present invention is therefore to provide a lighting device for streets, civil, industrial and commercial establishments, or for vehicles as covered by the enclosed claims.

Further characteristics and advantages of the present invention will become more evident from the following description of an embodiment given by way of non-limiting example with reference to the enclosed figures, in which:

- Figure 1 is a schematic axonometric projection partly in cross section of the optical and electronic component of the device of the invention;

- Figures 2A and 2B represent respectively an axonometric projection from below and one from above of first optical elements of the optical component of Figure 1 ;

- Figures 3A and 3B are respectively an axonometric projection from above and one from below of second optical elements of the optical component of Figure 1 ;

- Figure 4 is a schematic view, in partial lateral and enlarged cross section of the first and second optical elements of the optical component of the inventive device;

- Figure 5 is a schematic and enlarged view of a portion of lateral cross section of the optical and electronic component of Figure 1 ;

- Figure 6 is a schematic axonometric exploded projection of the device according to the invention.

DETAILED DESCRIPTION OF THE INVENTION

With reference to Figure 1 , reference number 1 represents in general the functional component of the lighting device of the present invention. This component 1 includes a support 2 on which is fastened a printed circuit 3, a plurality of first optical elements 4 and a plurality of second optical elements 5.

The support 2 is represented by a conventional, substantially flat plate provided with a surface on which the printed circuit 3 and said plurality of first optical elements 4 are fastened. The plate can be made of any suitable material conventionally used to support printed circuits. For example, it may be made of metal or plastic material, preferably a metal material provided with particular characteristics of dissipation of the heat generated by the light source, such as aluminium. Alternatively, a polymeric plastic material with a high thermal conductivity and heat resistance can be used for the purpose of heat dissipation.

The printed circuit or PCB (Printed Circuit Board) is of conventional type and includes light sources 6 electrically connected and fastened to said circuit. In addition, the circuit includes through holes 7 suitable to allow the fastening of said plurality of first optical elements 4 to the support 2.

Figures 2A and 2B schematically show a module 8 including said plurality of first optical elements 4. The module 8 represents nine optical elements 4 arranged so as to form a square in plan view. It is evident that such arrangement can vary according to the final dimensions of the lamp and, therefore, the number of elements per module can be larger or smaller. In each case, each module includes a first face 81 and a second face 82, with the first face corresponding to the face turned toward the light source and the second face corresponding to the face turned outwardly from the lamp, that is, in the direction of illumination.

Correspondingly, the first optical elements 4 display a first face 41 having a general appearance of concentric rings and a second face 42 having a generally chequered appearance.

Support spacing pins 9 extend from the second face 82 of the first optical elements 4. Such pins engage the corresponding above-mentioned through holes 7 of the printed circuit 3 so as to support the optical elements at a certain distance from said printed circuit. At the same time, the pins with said through holes also serve as centring elements for a correct installation on the printed circuit.

Figure 4 illustrates a schematic cross section along the longitudinal axis X- X of Figure 1 , with the first 4 and second 5 optical elements enlarged.

The first optical elements 4 have a first surface 10 turned toward the light sources 6, when in use, and a second surface opposite to the first one and thus turned in the direction of propagation of the light cone emitted by such light sources.

The first surface 10 is lined with a series or prisms 2 so as to create an optical geometry typical of a Fresnel lens. In particular, the prisms 12 are subdivided into a group 14 of intermediate prisms and a group 15 of peripheral prisms, while the central portion 13 of the optical element 4 or lens is substantially flat.

The group of intermediate prisms 14 includes first faces 16 and second faces 17 suitable to receive light from the source 6, separate it into beams of light 18 and refract/reflect said beams within the thickness of the lens 4 according to a preset angle referred to the Y-Y axis perpendicular to the plane of the lens itself. Said first faces 16 and second faces 17 are positioned so as to refract/reflect the greater part of the light beams in a manner substantially parallel to said Y-Y axis. For such purpose, preferably, the first face 16 is inclined with respect to the Y-Y axis at an angle between 45° and 85°, more preferably between 50° and 80°, while the second face 17 is inclined 170°-180°, preferably 175°-178°, with respect to the Y-Y axis. In addition, their height with respect to the substantially flat central portion 13 preferably increases in a centrifugal direction and is included between 0.1 mm and 0.5 mm.

The peripheral prisms 15 also include a first face 19 and a second face 20 suitable to receive the light beams 18 from the source 6 and to refract/reflect them within the thickness of the lens according to a further preset angle. In particular, they are such as to refract/reflect the greater part of the light beams in a manner substantially parallel to said Y-Y axis, always with respect to the Y- Y axis. For this purpose, preferably the first face 19 is inclined at an angle between 25° and 40°, more preferably between 30° and 35° with respect to said Y-Y axis, whereas the second face 20 is inclined at an angle between 170° and 180°, preferably between 175° and 178°. In addition, their height with respect to the central portion 13 decreases in a centrifugal direction and is included between 2 mm and 0.7 mm.

The pitch of each of said intermediate prisms 14 and peripheral prisms 15 may be included between 3 mm and 0,5 mm.

Contrariwise, the central portion 13 does not produce any substantial refraction or reflection of the light beams.

More generally, the above-described geometry of the first surface 10 of the lens 4 has been studied in such a manner as to collect the light from the source 6 and rectify the light beams 18 in a substantially perpendicular manner with respect to said Y-Y axis to transfer them with such orientation to the second surface 11.

The second surface 11 of the lens 4, always as shown in Figure 4 is, on the contrary, lined with concavities 21 turned toward the light sources 6 or, in other words, convexities turned in the direction of propagation of the light. The concavities in the cross section of Figure 4 appear as circular arcs whose radius may vary according to the angle of aperture of the light cone desired. In particular, the radius of curvature may be such as to receive the light beams 18 substantially perpendicular to the Y-Y axis, as previously explained, and to deflect them with respect to the same axis Y-Y by an angle included between 0° and ±35°.

It should be noted that the above-mentioned concavities may be spherical and therefore have the above-mentioned effect in both a longitudinal and a transversal direction with respect to the lighting device. Or else, depending on particular requirements or preferences, the concavities may have a transversal cross section different from the longitudinal one with respect to the longitudinal axis X-X of the device. In other words, the two cross sections may have different radiuses of curvature to obtain in one direction or in the other a different angle of refraction of the light. In this case, it is possible to have different deflections of the light beams in the longitudinal or transversal direction. For example, for street lighting lamps, it is necessary to have a greater opening of the light cone longitudinally to the street with respect to the transversal direction. Consequently, in the longitudinal cross section, the device 1 will have a second surface 11 provided with concavities that are more accentuated than the concavities of its transversal cross section.

The first optical elements 4 or lenses are made of vitreous or plastic material. Preferably, they are made of plastic material made by overinjection moulding using polymers such as for example polycarbonate or polymethylacrylate. The thickness of the lenses may vary from 3 mm to 4 mm overall, in which 1.5 mm to 2.5 mm, preferably 2 mm, are the core 22 of material and the rest is the sum of the depth of the prisms 10 and of the concavities 21 of the second surface 11 (Figure 5).

Further, the diameter of the first surface 10 of each lens 4 may range between 10 mm and 30 mm, and is preferably 26 mm.

The number of lenses per module as well as the number of modules may vary according to requirements or preferences. In particular, in the case of street lighting lamps it has been noted that to meet the most stringent regulations it is sufficient to have an array of lenses 4 arranged so as to form a flat plate or an array that includes from ten to sixty sources 6 and corresponding lenses. Obviously, in the case in which conditions require it, the number of lenses and/or modules can be increased or decreased. The modules may, in turn, include one or more piece-moulded lenses as previously explained so as to form modules that are preferably multiples of three. The shape of the plate or array of lenses as seen from above may be rectangular, as shown in Figure 1 , or it may be square or have other shapes as required by circumstances.

Advantageously, the lighting device 1 according to the present invention also includes second optical elements 5 or lenses.

In particular, these second optical elements 5 appear as a plate 23, shown as a whole in Figures 3A and 3B, generally flat and positioned so as to face and be parallel to the second surface 11 of said first optical elements 4 (Figure 1 ). In other words, the second optical elements 5 are positioned downstream with respect to the direction of the luminous flux emitted by the light source 6 and after the flux itself has crossed the first optical elements.

As is best shown in the cross section of Figure 4, said second optical elements 5 have a first surface 24 turned toward the first optical elements 4 and a second surface 25 opposite said first surface.

The first surface 24 is lined with refractive elements 26 distributed in at least two different types in different portions of the same surface. In fact, the refractive elements have characteristics that enable them to refract the light coming from said first elements or lenses 4 in a different manner depending on the portion of said surface involved. Preferably, as shown in Figure 3A, the surface 24 is divided into at least one peripheral portion 27 and at least one central portion 28.

Said at least one peripheral portion 27, as is best shown in Figure 4, has in its longitudinal cross section a surface lined with a series of said refractive elements having in general cusp shapes 29. The cusps have the function of collecting part of the light beams 18 coming from the first optical elements 4 and of deflecting them toward the periphery of the lighting device 1. As shown schematically in Figure 4, due to the geometry of the cusps, some light beams will in any case be deflected toward the centre of the device 1 , but most of them will undergo the above deflection toward the periphery. It should be noted that the cusps deflect the light beams up to a maximum of a further 30° with respect to the angle of incidence, that is, the angle at which they reach said cusps.

Said at least one central portion 28 includes concavities 31 turned in the direction of propagation of the light or, in other words, convexities toward the light source, which are preferably divided into first concavities 32 and second concavities 33 having radiuses of curvature that vary depending on their respective function. In particular, the first concavities 32 are positioned adjacent to the peripheral portion 27 and have an accentuated radius of curvature so as to have a general shape approaching the shape of the above-mentioned cusps. Conversely, the second concavities 33 are positioned in the actual central portion and have a more attenuated convexity. This differentiation has the advantage of achieving a greater effect of refraction and separation of the light toward the centre of the lighting device and a greater deflection of the light toward the periphery. In any case, the light beams leaving the central portion 28 will be further refracted by an angle of ±5° to ±20° with respect to the angle of incidence, that is the angle in which the light beam enters into said portion, while the light beams leaving the peripheral portion 27 will be further reflected at an angle up to 30° with respect to the angle of incidence.

Further, as shown schematically in Figure 3A, the surface 24 has the above refractive elements 26 arranged transversally with respect to the longitudinal axis A-A of the second optical element 5. In this manner, the light is split and refracted in light beams distributed along the A-A axis with the above angles of aperture.

The second surface 25 of the second optical elements 5 is flat, so as to not further modify the path of the light beams 18.

In agreement with a variant embodiment of the invention, it is also possible to modify the second surface 25 by providing it with cusps and/or convexities in all effects similar to the ones previously described but arranged longitudinally with respect to the A-A axis in order to split and refract the light into light beams transversally to said axis, depending on particular requirements or as preferred.

The second optical elements 5, like the first optical elements 4, are made of a vitreous or plastic material. Preferably, the material is a polymeric plastic like polymethyl methacrylate (PMMA) or polycarbonate. Further, the thickness may vary from 3 mm to 6 mm, 2 mm to 3 mm of which consist of the core, while the rest is made up by the height of the cusps or concavities.

The second optical elements 5 are then positioned at a certain distance from the first optical elements 4. Preferably, this distance is included between 10 mm and 20 mm, more preferably it is 15 mm.

As described heretofore, it is evident that the lighting device 1 of the present invention makes it possible to advantageously separate and refract the light coming from a light source, such as for example the light emitted by a LED which is very concentrated, in an area that may also be very wide, simplifying the structure of the optical component on a single plane and not on more planes, as is necessary with the devices of the known art.

In fact, it has been noted that by using LEDs of 1W as light sources in a matrix of thirty-six luminous elements 4 distributed in a rectangle measuring 100 mm x 400 mm, the lighting device 1 used as a street lamp positioned at a height of 8 m above the roadbed can project on the ground a light cone with a width larger than 120° with respect to the perpendicular that joins the centre of the lamp with the roadbed, as required by the most stringent regulations. In particular, the width obtained is 124°.

Further, it has been seen that the distribution of the light on the roadbed from a height of 8 m, for a device provided with thirty-six LEDs and with the optics as described above covers a surface measuring 30 m in length and 8 m in width without divergences at the margins, with gradual lessening in intensity and without discontinuities.

It is therefore evident that both the width of the light cone and the efficiency and the quality of the light have been optimized. With reference to Figure 6, the lighting device 100 of the invention includes, in addition, a case 34 suitable to house all the functional components of the device, that is, both the optical components and the electronic components, such as the printed circuit 3 and the power supplies (not shown), as well as the supports 2 for the electronic and the optical components. Preferably, the case 34 has a box-like shape and includes a series of thermal dispersion elements 35. Such elements may be represented by fins set at right angles to the body of the device. In addition, the case may have an edge 36 rimming the opening of the case provided with a seat 37 suitable to receive a corresponding gasket 38 to prevent the entrance of water or dust that could damage the electrical or electronic parts. A cover 39 closes said components and the optics in the box-like element. Preferably, the cover 39 consists of a generally flat portion represented by a plate of said second optical elements 5 and an edge 40 engaging with the above edge 36 of the case to close the same case.

Thus, the present invention brings with it numerous advantages. Firstly, the lighting device 100 is made up of a very simple structure in which the optical part consists of a first plurality of lenses 4 arranged on a single plane of limited thickness and of a second plurality of lenses 5 which are also arranged on a single plane of limited thickness and positioned parallel to and at a certain distance from said first plurality of lenses. It follows that the optical part can be made in a simple manner, as for example through the technology of moulding plastic material. At the same time, the whole resulting structure is one of reduced size.

Consequently, the technology at the base of the lighting device 100 is of high quality and reliable, and the production is considerably simplified and accelerated, so that from the economic point of- view the product offers a considerable advantage in terms of costs.

The positioning of the optics on a single plane also implies a positioning of the light sources on a single plane. This entails the complete absence of the above-mentioned occurrence of light pollution.

Further variants of the present system can be achieved by a person skilled in the art without departing from the scope of protection of the present invention as defined in the claims attached hereunder.

Claims

Lighting device (100) including a support (2) on which is fastened a printed circuit (3) provided with at least one light source (6) and at least one optical unit (4, 5) capable of splitting and reflecting/refracting the light emitted by said light source, characterized in that said at least one optical unit includes at least one first optical element (4) provided with a first surface (10) turned toward said light source (6) and including a series of prisms (12) suitable for receiving said light, splitting it into light beams and aligning them substantially parallel along the axis (Y-Y) perpendicular to the plane of said first surface (10) and of a second surface (11) opposite said first surface and including concavities (21 ) suitable for refracting said light beams, thus obtaining an opening of the light cone emitted by said source (6), said optical unit including in addition a second optical element (5) provided with a first surface (24) turned toward said at least one first optical element (4) and including refractive elements (26) distributed transversally with respect to the longitudinal axis (A-A) of said at least one second optical element (5) in at least one peripheral portion (27), in which said refractive elements are in general cusp-shaped and are suitable to direct said light beams outwardly from the device, and in at least one central portion (28) including concavities (32, 33) suitable to further refract said light beams.

Device (100) according to claim 1 , in which said at least one first (4) and said at least one second (5) optical elements are generally flat.

Device (100) according to claim 1 or 2, in which said concavities (21 ) of said second surface (11) of the at least one first optical element (4) are suitable for refracting said light beams (18) coming from said first surface (10) by an angle included between 0° and ±35° with respect to said axis (Y-Y).

4. Device (100) according to claim 3, in which said intermediate prisms (14) include first faces (16) inclined at an angle between 45° and 85° and second faces (17) inclined at an angle of 170°-180° with respect to the axis (Y-Y).

5. Device (100) according to claim 4, in which said intermediate prisms ( 4) are arranged concentrically to each other and have a height that increases in a centrifugal direction from 0.1 mm to 0.5 mm.

6. Device (100) according to claim 4 or 5, in which said peripheral prisms (15) include first faces (19) inclined at an angle included between 25° and 50° and second faces (20) inclined at an angle of 170°-180° with respect to the axis (Y-Y).

7. Device (100) according to claim 6, in which said peripheral prisms (15) are . arranged concentrically to each other and have a height that increases in a centrifugal direction from 0.7 mm to 2 mm.

8. Device (100) according to any one of claims 3 to 7, in which the pitch of each of said intermediate prisms (14) and peripheral prisms (15) is included between 0.5 mm and 3 mm.

9. Device (100) according to any one of claims 1 to 8, in which said concavities (21) of said second surface (11) of said at least one first optical element (4) have an identical or different progression in the longitudinal and transversal cross section.

10. Device (100) according to any one of claims 1 to 9, in which said concavities (32, 33) of the at least one second optical element (5) refract the light beams by an angle from ±5° to ±20° with respect to their angle of incidence.

11. Device (100) according to any one of claims 1 to 10, in which said cusps (29) of the at least one second optical element (5) refract the light beams at an angle up to 30° with respect to their angle of incidence.

12. Device (100) according to any one of claims 1 to 11 , in which said at least one second optical element (5) includes a second surface (25) opposite said first surface (24) having said concavities (32, 33) that extend longitudinally with respect to the axis (A-A).

13. Device (100) according to any one of claims 1 to 12, in which said at least one first optical element (4) has a thickness included between 3 mm and 4 mm and a diameter of the first surface (10) included between 10 mm and 30 mm and said at least one second optical element (5) has a thickness included between 3 mm and 6 mm.

14. Device (100) according to any one of claims 1 to 13, in which said at least one first (4) and one second (5) optical element are made of vitreous material or polymeric plastic selected from polycarbonate and polymethyl methacrylate.

15. Device (100) according to any one of claims 1 to 14, in which said at least one first (4) and second (5) optical element are positioned parallel to each other and at a distance included between 0 mm and 20 mm.

16. Device (100) according to any one of claims 1 to 15 as a street lighting lamp, a lamp for external illumination, for civil, commercial or industrial, establishments, or for vehicles.

17. Device (100) according to claim 16, including in addition a case (34) of box-like shape suitable for housing all the functional components of the device and including a series of thermal dispersion elements (35).

18. Device (100) according to claim 17, in which said case (34) has an edge (36) that rims the opening of the case provided with a seat (37) suitable to receive a corresponding gasket (38) to prevent the entrance of water or dust.

19. Device (100) according to claim 17 or 18, including a cover (39) that closes said functional components.

20. Device (100) according to claim 19, in which said cover (39) consists of a generally flat portion represented by a plate of said second optical elements (5) and an edge (40) that engages said edge (36) of the case (34) to close the same.