WO2009037720A1

WO2009037720A1 - Led illuminating device

Info

Publication number: WO2009037720A1
Application number: PCT/IT2007/000644
Authority: WO
Inventors: Franco Venturini
Original assignee: Wissen Lux S.P.A.
Priority date: 2007-09-17
Filing date: 2007-09-17
Publication date: 2009-03-26
Also published as: EP2191191A1; CA2699720A1

Abstract

A LED illuminating device comprising: a plurality of LEDs (10a-10e); an optical element (20) of a substantially planar extension and having a substantially flat first surface (21) facing said LEDs (10a-10e); and a second prism-like surface (22) opposite to said first surface (21), said LEDs (10a- 10e) being divided into groups (11a-11e) and disposed in such a manner that main lighting directions (Da-De) of LEDs belonging to the same group form equal angles with the first surface (21) of said optical element (20), and main lighting directions (Da-De) of LEDs belonging to different groups form different angles with the first surface (21) of said optical element (20).

Description

LED ILLUMINATING DEVICE

D e s c r i p t i o n

The present invention relates to a LED illuminating device .

More particularly, the invention relates to LED illuminating devices that are used in the lighting technical sector, i.e. for indoor lighting (in houses, offices, shops, warehouses, etc.) and outdoor lighting

(street lighting) .

It is known that in the concerned sector lighting apparatus are presently made available that make use of quartz-iodine lamps or semiconductor devices, such as

LEDs, that, due to the disadvantageous positioning of the light sources and/or the poor efficiency of the optical elements employed, supply quite insufficient illumination in terms of width of the lighted area or intensity of the light beam generated.

To obviate this drawback it is sometimes possible to increase the intensity of the generated light beams by correspondingly increasing the related energy consumption; this case too is clearly far away from an ideal situation or a situation characterised by an acceptable efficiency degree.

Accordingly, it is an aim of the present invention to provide a LED illuminating device enabling an acceptable illumination of areas of predetermined size with reduced energy consumption.

Another aim of the present invention is to make available a LED illuminating device capable of illuminating in a homogeneous and uniform manner.

A further aim of the invention is to provide a LED illuminating device having a simple and cheap structure and a reduced manufacturing complexity.

The foregoing and still further aims are substantially achieved by a LED illuminating ^'device having the features recited in the appended claims.

Further features and advantages will become more apparent from the detailed description of a preferred but not exclusive embodiment of the invention. This description is taken hereinafter with reference to the accompanying drawings, given by way of non-limiting example, in which:

- Fig. 1 diagrammatically shows a plan view of a device in accordance with the invention, with some- parts removed for a better view of others;

- Fig. 2 diagrammaticaliy shows a section view, taken along line II-II, of the device in Fig. 1;

- Fig. 3a diagrammatically shows a plan view of an element of the device of the invention; - Fig. 3b diagrammatically shows a perspective view to an enlarged scale of a detail seen in Fig. 3a;

- Fig. 4a shows an alternative embodiment of the element seen in Fig. 3a;

- Fig. 4b diagrammatically shows a perspective view to an enlarged scale of a detail in Fig. 4a;

- Fig. 5 is a diagrammatic plan view of a further embodiment of a device in accordance with the invention, with some parts removed for a better view of others; - Fig. 6 is a diagrammatic section, view, taken along line VI-VI, of the device in Fig. 5;

- Figs. 7 and 8 diagrammatically show part of the operation of the device in Fig. 1 and of a detail of same .

With reference to the drawings, a LED illuminating device in accordance with the present invention has been generally identified with reference numeral 1.

As above mentioned, device 1 can be used, depending on requirements, for indoor lighting, but also for illuminating areas in the open, for street lighting for example.

Device 1 'first of all comprises a plurality of LEDs 1Oa-IOe that, as better clarified in the following, are suitably disposed so as to obtain a satisfactory illumination in a predetermined area. LEDs 1Oa-IOe are associated with an optical element 20 of a substantially planar extension; practically, the optical element 20 can have a plate-like structure, with square or rectangular plan conformation.

Preferably, the optical element 20 is operatively associated with all LEDs 1Oa-IOe of device 1; in other words, the optical element 20 is employed for acting ■ on light beams generated by the different LEDs 1Oa-IOe and illuminating a predetermined area.

The optical element 20 has a substantially-flat first surface 21 facing LEDs 1Oa-IOe, and a second prism-like surface 22 opposite to the first surface 21.

Therefore, the light beams generated by LEDs 1Oa-IOe initially strike on the first surface 21 and are submitted in cascade to the action of the second surface 22 before reaching the area to be illuminated.

It is to be noted that in the present specification and the following claims, by prism-like surface it is intended any surface having one or more portions inclined to said first surface, so as to create refraction and/or reflection and/or diffraction and/or polarisation phenomena of light beams striking on the first surface 21.

In one embodiment, diagrammatically shown in Figs. 3a- 3b, the prism-like surface 22 portions consist of a succession of pairs of surfaces 22a inclined to the first surface 21, in which the inclined surfaces 22a. of the same pair converge away from the first surface 21; in more detail, the inclined surfaces 22a have the same longitudinal major extension direction, represented by X in Figs.^" 3a-3b.

Preferably, the angle formed by each pair of inclined converging surfaces 22a is included between 60° and 120°, preferably between 80° and 100°. For instance, this angle can be of 90°.

Preferably, the distance between the convergence line of the inclined surfaces 22a and the plane defined by the edges of -said^" surfaces 22a opposite to the convergence^' lines is included between 1.5 mm and 3 mm and is of 2 mm, for example.

Preferably, the distance between the first surface 21 and the plane defined by the edges of the surfaces 22a opposite to the convergence lines is included between 1.5 mm and 3 mm, and is of 2 mm, for example.

Practically, in the embodiment shown in Figs. 3a-3b, the prism-like surface has a zigzag course defined by said inclined surfaces 22a.

In another embodiment, diagrammatically shown in Figs. 4a-4b, the second surface 22 is defined ^'by a plurality of prismatic elements 22b disposed close to each other, each of which is defined by at least three side surfaces 22c inclined to the first surface 21 and converging, at a vertex 22d, away from the first surface 21.

Practically, in the embodiment in Figs. 4a-4b, the prism-like surface 22 can be defined by a plurality of right pyramids disposed close to each other and with a base parallel to the first surface 21.

The base of these pyramids can for instance have a square (as shown in Figs. 4a and 4b) or a hexagonal shape and preferably is in the form of a regular hexagon.

Preferably, the height of each pyramid is included between 1.5 mm and 2.5 mm, and is of 2 mm, for example.

Preferably, the distance between the pyramid base and the first surface 21 of the optical element 20 is included between 1.5 mm and 3 mm, and is of 2 mm, for example .

Preferably, the angle formed by each edge of said pyramid (not belonging to the pyramid base)^' with the base ^'surface of said pyramid is included between -40° and 50°, and is preferably, of 45°.

Preferably, the optical element 20 is at least partly transparent to the visible light, i.e. the light beams generated by LEDs 1Oa-IOe.

The optical element is advantageously made of fireproof material; it can be formed with polycarbonate, for example .

LEDs 1Oa-IOe are divided into groups lla-lle, and are such disposed that the main lighting directions Da-De of LEDs 1Oa-IOe belonging to the same group will form equal angles with the first surface 21 of the optical element 20, and the main lighting directions Da-De of LEDs 1Oa-IOe belonging to different groups will form different angles with the first surface 21 of the optical element 20.

By way of example, in Fig. 8 ■ it is shown that LEDs belonging to group lib have main lighting directions Dd forming an angle α with the first surface 21 of the optical element 20, while the main lighting directions Dd of LEDs belonging to group Hd form a different angle β with the same first surface 21.

Due to their arrangement, the different LEDs 1Oa-IOe can have ^'different distance from the first surface 21; at all events, the distance between each LED and the first surface 21 can be included between 1 cm and 5 cm, and preferably between 2 cm and 4 cm.

It will be noted that in the present context and in the following claims, by main lighting direction of a LED it is intended the symmetry axis of the light beam generated by said LED.

In fact, a LED 10 typically generates a light beam F having the shape of a cone (diagrammatically shown in Fig. 7), the vertex V of which is defined by said LED 10 itself; the main lighting direction D is therefore the straight line along which the geometric height of this cone is measured.

Preferably, the main lighting direction Da-De of different groups lla-lle converge away from said LEDs

1Oa-IOe towards said optical element 20, as diagrammatically shown in Fig. 8.

Preferably, the main lighting directions of any pair of LED groups converge on a point A (in the side view diagrammatically shown in Fig. 8 intersection between directions Db and De has been shown, by way of example) the orthogonal projection H of which on plane P in which the first surface 21 lies, falls inside the first surface 21 itself.

Should each group lla-lle of LEDs 1Oa-IOe be defined by a respective array 15a-15e of LEDs (as will be described in more detail later on) , point A in Fig. 8 in a three-dimensional picture represents a straight line orthogonal to the plane of the sheet on which Fig. 8 is drawn; in this case, the orthogonal projection of this straight line on plane P in which . the first surface 21 lies, falls at least partly inside the first surface 21.itself.

Advantageously, the inclination of the main lighting directions Da-De relative to the first surface 21 of the optical element 20 decreases away from a substantially central portion 23 of said optical element 20, at least along a rαoving-away direction AL parallel to the first surface 21.

In other words, the more moving-away from said central portion 23 occurs, the more the main lighting directions Da-De approach a condition of parallelism to the first surface 21.

The central portion 23 of the optical element 20 can be defined as the portion facing a symmetry centre or symmetry axis of the arrangement of LEDs 1Oa-IOe; the central portion 23 can also be defined as the portion facing a symmetry axis or centre of a mounting surface 30 to be better described in the following and with which LEDs 1Oa-IOe are in engagement.

In addition or as an alternative, the central portion 23 of the optical element 20 can be a symmetry centre or axis of the optical element 20 itself.

Should the central portion 23 of the optical element 20 be defined by a symmetry centre of the mounting surface 30 and/or of the optical element .20 and/or of the arrangement of LEDs 1Oa-IOe, the moving-away direction from this central portion can be defined by any straight line belonging to the first surface 21 of the optical element 20 and passing through this central portion 23 (or an orthogonal projection of said portion on the- first surface 21) .

Preferably, each LED belonging to a predetermined group and having a main lighting direction that is not orthogonal to the first surface 21 has a main lighting direction differing by an angle δ from the main lighting direction of the LEDs belonging to a group adjacent to said predetermined LED group; angle δ is preferably included between 15° and 25° and equal to 20°, for example.

By way of example, the distance between adjacent LED arrays can be included between 5 cm and 25 cm for example, and preferably between 6 cm and 10 cm.

Within the same array, adjacent LEDs can be separated by a distance included between 10 cm and 20 cm, preferably between 12 cm and 16 cm.

Should the central portion 23 of the optical element 20 be defined by a symmetry axis of the mounting surface

30 and/or of the optical element 20 and/or of the arrangement of LEDs 1Oa-IOe, the moving-away direction from this central portion 23 .can be defined by any straight line belonging to the first surface 21 or parallel _.thereto and transverse to said symmetry axis

(or to an orthogonal projection of said axis on the first surface 21) .

By way of example, denoted at S' in Fig. 1 is a symmetry axis of the arrangement of LEDs 1Oa-IOe that also appears to be the symmetry axis of the mounting surface 30 and the optical element 20.

In Fig. 5 the symmetry axis of the arrangement of LEDs l^'Oa-lOe that also appears to be the symmetry axis of the mounting surface 30 and the optical element 20 has been identified with S".

Preferably, each group lla-lle of LEDs 1Oa-IOe is mounted on a respective bearing surface 40a-40e. This means that LEDs 1Oa-IOe belonging to different groups are mounted on different bearing surfaces. In particular, through suitable arrangement and inclination of the bearing surfaces 40a-40e, the inclination of the main lighting directions Da-De relative to the first surface 21 is determined.

Each bearing surface 40a-40e can have a plate-like structure having a substantially rectangular conformation, seen in plan view, or, more generally, an elongated shape (Figs. 1 and 5) .

LEDs 1Oa-IOe are preferably aligned along the major extension direction W of the respective bearing surface 40a-40e.

Conveniently, each bearing surface 40a-40e relative to the first surface 21 of the optical element 20 has an inclination different from the inclination of at least another bearing surface 4Oa-40e.

In more detail, the inclination of the bearing surfaces 40a-40e increases on moving away from the substantially central portion 23 of the optical element 20, at least along one of the above defined moving-way directions.

As mentioned above, in the preferred embodiment each group lla-lle of LEDs 1Oa-IOe ^' is defined by a respective LED array 15a-15e, i.e. a series of LEDs aligned along a preferably straight line.

As shown by way of example in Figs. 2 and 5, the LED arrays 15a-15e are preferably parallel to each other.

In more detail, in the embodiment in Figs. 1 and 2, device 1 comprises a first LED array 15a defining a respective group of LEDs 11a. Each LED 10a of the first array 15a has a main lighting direction Da substantially orthogonal to the first surface 21 of the optical element 20.

^'Preferably, the main lighting directions Da of LEDs 10a belonging to said first array 15a all lie in the same plane. More generally, the main lighting direction Da-

De of LEDs belonging to the same group lla-lle preferably lie in the same plane.

Preferably, the LEDs 10a of the first array 15a are mounted on a respective first bearing surface 40a that is substantially parallel to the first surface 21 of the optical element 20.

The portion of optical element 20 facing the first LED array 15a can define said central portion 23 of the optical element 20 itself.

Device 1 further comprises a second and a third LED arrays 15b, 15c defining the second and third LED groups lib, lie, respectively.

The second and third LED arrays 15b, 15c are substantially parallel to the first LED array 15a and are disposed on opposite sides relative to the first LED array 15a.

The LEDs 10b of the second array 15B have main lighting directions D substantially symmetric to the main lighting directions D of the LEDs 10c of the third array 15c, relative to a predetermined plane Z. This predetermined plane Z is a plane orthogonal to the first surface 21 of the optical element 20 and passing through the first LED array 15a.

Device 1 further comprises a fourth and a fifth array 15d, 15e of LEDs 1Od, 1Oe defining the fourth and fifth LED groups Hd, He, respectively. The fourth and fifth arrays 15d, 15 are parallel to the first array 15a.

The fourth array 15d is in side by side relationship with the second array 15b and is positioned on the opposite side of the latter relative to the first array 15a. The fifth array 15e is in side by side relationship with the third array 15c and is positioned on the opposite side of the latter relative to the first array 15a.

The inclinations of the main lighting directions Dd, De of the LEDs 1Od, 1Oe belonging to the fourth and fifth LED arrays 15d, 15e are symmetric to said predetermined plane Z .

As diagrammatically shown in Fig. 2, the inclination of the main lighting directions Db, Dc, Dd, De of the LEDs belonging to the different LED groups Hb, Hc, Hd, He decreases on moving away from the first array 15a.

The embodiment diagrammatically shown in Figs. 5 and 6 has a structure similar to that described with reference to the embodiment in Figs. 1 and 2; the difference consists in that in the embodiment in Figs. 5 and 6 device 1 further comprises an auxiliary LED array 15f parallel to the first LED array 15a and in side by side relationship therewith. The LEDs 1Of of the auxiliary array 15f define a respective auxiliary LED group Hf. The LEDs 1Of of the auxiliary array 15f have main lighting directions Df substantially orthogonal to the first surface 21 of the optical element 20. Practically, the auxiliary LED array 15f is interposed between the first LED array 15a and the second LED array 15b. Alternatively, the auxiliary LED array 15f can be interposed between the first and third LED arrays, 15a and 15c respectively.

In the embodiment in Figs. 5 and 6 the plane relative to which the main lighting directions Db, Dc of LEDs 10b, 10c of the second and third arrays 15b, 15c are symmetric is an auxiliary plane ZA orthogonal to the first surface 21 of the optical element 20 and spaced apart the same distance from the first LED array 15a and auxiliary LED array 15f .

In both embodiments, the second and third LED arrays 15b, 15c are preferably mounted on a second and a third bearing surface 40b, 40c, respectively.

In particular, the second and third bearing surfaces 40b, 40c have inclinations, with respect to the first surface 21 of the optical element 20, that are_, substantially symmetric, either relative to said plane Z orthogonal . to the first surface 21 and passing through the first LED array 15a, or relative to said auxiliary plane ZA.

Generally, LEDs 1Oa-IOe are such disposed that, on surfaces to be illuminated, the area illuminated by each LED at least partly overlaps the area illuminated by the__^ adjacent LED/LEDs.

Should this illuminated area have a shape with a geometric centre, the LEDs are disposed in such a manner that the line confining the area illuminated by one LED passes through the geometric centre of the area illuminated by one or more adjacent LEDs.

Advantageously, as above mentioned, device 1 further comprises a mounting surface 30 on which LEDs 1Oa-IOe are mounted. In more detail, mounted on the mounting surface 30 are the bearing surfaces 40a-40e on which the LEDs of the different groups lla-lle are in turn mounted.

Conveniently, the mounting surface 30 is substantially parallel to the first surface 21 of the optical element 20. In more detail, the mounting surface 30 can be part of a box-shaped body 31 that, through engagement with the optical element 20, defines a closed space 32 in which LEDs 1Oa-IOe are contained.

The mounting surface 30 can be suitably designed for securing device 1 to the ceiling of a closed volume or room, for example, or to a suitable support structure.

Preferably, device 1 further comprises an electric feeding unit 50 to supply LEDs 10 with the necessary electric power for correct operation.

The feeding unit 50 can be associated with a control circuit 60 for selectively powering • said LEDs 1Oa-IOe; in more detail, the control circuit 60 can allow one or more LED groups lla-lle that are to be energised to be selected, while the LEDs belonging to other groups are kept de-energised.

Advantageously, powering of LEDs 1Oa-IOe is current- controlled.

In addition, the different LED groups are powered in parallel, so that a possible failure or malfunction of a LED or LED group does not impair correct powering of the LEDs belonging to other groups.

Preferably, the feeding unit 50 and/or control circuit 60 are mounted on said mounting surface 30.

In particular, the feeding unit 50 and/or control circuit 60 can be interposed between a pair of LED arrays, such as between the first array 15a and the auxiliary array 15f in the embodiment diagrammatically shown in Figs. 5 and 6.

It will be recognised that in the accompanying drawings the feeding unit 50 and control circuit 60 are represented as blocks external to the box-^-shaped body 31 for the sake of clarity; actually, as described above, both the feeding unit 50 and control circuit 60 can be housed in said closed space 32.

Preferably, the control circuit 60 is drivable by a user through one or more switches or similar command means, to establish which of said LED groups are to be powered.

The invention achieves important advantages.

First of all, the device in accordance with the invention enables an acceptable illumination of areas of predetermined size to be achieved with reduced energy consumption. In addition with the device of the invention a homogeneous and uniform illumination is obtained.

The invention also aims at providing a LED illuminating device having a simple .. and cheap structure with a reduced manufacturing complexity.

Claims

C L A I M S

1. A LED illuminating device, comprising: - a plurality of LEDs (1Oa-IOe) ; - an optical element (20) of a substantially planar extension and having a substantially flat first surface (21) -facing said LEDs (1Oa-IOe) and a second prism-like surface (22) opposite to said first surface (21), said LEDs (1Oa-IOe) being divided into groups (lla-lle) and disposed in such a manner that main lighting directions (Da-De) of LEDs belonging to the same group form substantially equal angles with the first surface (21) of said optical element (20), and main lighting directions (Da-De) of LEDs belonging to different groups form different angles with the first surface (21) of said optical element (22) .

2. A device as claimed in claim 1, wherein the main lighting directions (Da-De) of different groups converge on moving away from said LEDs (1Oa-IOe) towards said optical element (20) .

3. A device as claimed in claim 1 or 2, wherein the inclination, relative to the first surface (21) of said optical element (20), of said main lighting directions (Da-D3) decreases on moving away from a substantially central portion (23) of said optical element (20) at least along one moving-away direction (AL) parallel to said first surface (21) .

4. A device as claimed in anyone of the preceding claims, wherein each LED group (lla-lle) is mounted on a respective bearing surface (40a-40e) .

5. A device as claimed in the preceding claim, wherein each bearing surface (40a-40e) has an inclination relative to the first surface (21) of said optical element (20) , that is different from the inclination of at least another of said bearing surfaces.

6. A device as claimed in claim 4 or 5, wherein the inclination of said bearing surfaces (40) increases on moving away from a substantially central portion (23) of said optical element (20) , at least along one moving-away direction (AL) parallel to said first surface (21) .

7. A device as claimed in anyone of the preceding claims , wherein said second surface (22) is defined by a succession of pairs of inclined surfaces (22a) relative to the first surface (21) , the inclined surfaces (22a) of the same pair converging away from said first surface (21), said inclined surfaces (22a) having the same longitudinal major extension direction (W) .

8. A device as claimed in anyone of claims 1 to 6, wherein said second surface (22) is defined by a plurality of prismatic elements (22b) disposed close to each other, each of said prismatic elements (22b) being defined by at least three side surfaces (22c) that are inclined to said first surface (21) and converge on a respective vertex (22d), away from said first surface (21).

9. A device as claimed in anyone of the preceding claims, wherein each of said LED groups (lla-lle) is defined by a respective LED array (15a, 15e) .

10. A device as claimed in the preceding claim, wherein said LED arrays (15a-15e) are substantially parallel to each other.

11. A device as claimed in anyone of the preceding claims, wherein said LED groups comprise:

- at least one first LED array (15a) , each of said LEDs having a main lighting direction (Da) substantially orthogonal to said first surface (21) ;

- at least one second and one third LED arrays (15b, 15c) , substantially parallel to said first LED array

(15a) and disposed on opposite sides relative to said first LED array (15a), the LEDs (10b) of said second array (15b) having main lighting directions (Db) substantially symmetric to the main lighting directions (Dc) of the LEDs (10c) of said third array (15c) , relative to a plane (Z) orthogonal to the first surface

(21) and passing through the first LED array (15a) or to an auxiliary plane (ZA) parallel thereto.

12. A device as claimed in the preceding claim, wherein the LEDs (10a) of said first array (15a) are mounted on a first bearing surface (40a) that is substantially parallel to said first surface (21) .

13. A device as claimed in claim 11 or 12, wherein said second and third LED arrays (15b, 15c) are mounted on a second and a third bearing surface (40b, 40c) respectively, said surfaces having substantially symmetric inclinations either relative to a plane (Z) orthogonal to said first surface (21) and passing through said first LED array (15a) , or relative to an auxiliary plane (ZA) parallel thereto.

14. A device as claimed in anyone of claims 11 to 13, further comprising an auxiliary LED array (15f) that is substantially parallel to said first LED array (15a) , the LEDs (1Of) of said auxiliary array (15f) having main lighting directions (Df) substantially orthogonal to said first surface (21) .

15. A device as claimed in the preceding claim, wherein said auxiliary plane (ZA) is a plane orthogonal to the first surface (21) of the optical element (20) and spaced apart the same distance from the first LED array (15a) and the auxiliary LED array (15f).

16. A device as claimed in anyone of the preceding claims , wherein the main lighting directions (Da-De) of LEDs belonging to the same LED group lie in the same plane.

17. A device as claimed in anyone of the preceding claims , further comprising a mounting surface (30) on which said LEDs (1Oa-IOe) and preferably said bearing surfaces (40a-40e) are mounted.

18. A device as claimed in the preceding claim, wherein said mounting surface (30) is substantially parallel to the first surface (21) of said optical element (20) .

19. A device as claimed in claim 17 or 18, wherein said mounting surface (30) is part of a box-shaped body (31) in engagement with said optical element (20) for defining a closed space (32) in which said .LEDs (10a- • 1Oe) are contained.

20. A device as claimed in anyone of the preceding claims further comprising a feeding unit (50) to supply electric power to said LEDs 10 (1Oa-IOe) .

21. A device as claimed in the preceding claim, further comprising a control circuit (60) associated with said feeding^' unit (50) for selectively energising said LEDs (1Oa-IOe) .

22. A device as claimed in claim 20 or 21, wherein powering of said LEDs (1Oa-IOe) is current-controlled.

23. A device as claimed in anyone of the preceding claims, wherein a distance between said LEDs (1Oa-IOe) and said first surface (21) is included between 1 cm and 5 cm, preferably between 2 cm and 4 cm.

24. A device as claimed in anyone of the preceding claims, wherein at least each LED belonging to a predetermined group and having a main lighting direction that is not orthogonal to the first surface (21) has a main lighting direction differing by an angle (δ) from the main lighting direction of the LEDs belonging to .a group adjacent to said predetermined LED group, said angle (δ) being included between 15° and 25°.