WO2013061102A1

WO2013061102A1 - Illuminator for use in public lighting

Info

Publication number: WO2013061102A1
Application number: PCT/HU2012/000112
Authority: WO
Inventors: Zsolt Nagy; András SZALAI
Original assignee: Hungaro Lux Light Kft.
Priority date: 2011-10-28
Filing date: 2012-10-25
Publication date: 2013-05-02
Also published as: DE212012000192U1; HU4053U

Abstract

Illuminator for use in public lighting comprising LED devices (10) as light source, the LED devices (10) are mounted in printed circuit board (14) and have a light emitting end on the opposite side of the mounting. The light sources have a first plane (s) and perpendicular to it a second plane (0 with a respective first and second light emitting angle characteristic, the angle range of the first light emitting angle characteristic is wider than that of the second one. The illuminator has a weatherproof covering surface (13) in the direction of light emission, and the LED devices (10) are encompassed at least in the directions of light emission with a transparent dome-shaped covering (12) or covering portion (12') inserted in the weatherproof covering surface (13). Placed before the light emitting end of the LED devices (10) optical beam forming elements (11) having a double bulge are provided.

Description

ILLUMINATOR FOR USE IN PUBLIC LIGHTING The invention relates to an illuminator for use in public lighting comprising

LED devices as light source wherein the LED devices are mounted in a printed circuit board and have a light emitting end on the opposite side of the mounting. The light sources in the illuminator have a first plane and perpendicular to it a second plane with a respective first and second light emitting angle characteristic, wherein the angle range of the first light emitting angle characteristic is wider than that of the second light emitting angle characteristic. In the direction of light emission the illuminator is provided with a weatherproof covering surface, and the LED devices are encompassed at least in the directions of light emission with a transparent dome-shaped covering or covering portion inserted in the weatherproof covering surface.

Companies manufacturing illuminators seek for LED devices applicable for use in public lighting. There are known solutions in which the angle characteristic of light emission diverges in two planes perpendicular to each other. Generally, in order to effectuate the asymmetric angle characteristic, asymmetric lenses are placed before the LED devices. To provide the illuminator with a weatherproof covering surface, a flat sheet made of glass or plastic is placed before the LED devices.

A disadvantage of this solution is that production of asymmetric lenses is rather expensive, technical requirements during their installation are high, and the efficiency of light emission is decreased because of the additional optical transmission layer (lens). The disadvantage of the weatherproof plate beside the wide ranging angle characteristic required in certain ideal cases is that wider effective light emission cannot be achieved at certain range of angles because of the total reflection.

In other known solutions light emission in a wide range of angles is realized by bending the panel of the printed circuit board. Still in other solutions the LED devices are built in along differently directed axes. In both cases excessive investment of technology is required so they are expensive. In these solutions the symmetric characteristic being in the plane is only extended along one of the axes.

To eliminate the aforementioned disadvantages a solution is proposed in utility model HU 3796 in which the transparent, dome-shaped light emitting end of the individual LED devices is provided with a double bulge. Further, the individual LED devices are encompassed at least in the directions of light emission with a transparent, dome-shaped covering or covering portion fitted into the weatherproof covering surface.

This solution guarantees the required light distribution characteristic. However, to form the individual LED devices with a double-bulged end is expensive in respect of production technology (they must be produced together with the LEDs). Further, also for production technology reasons, relatively high light absorption is resulted due to the used material and its thickness.

The aim of the present invention is to improve the latter solution by decreasing the costs and the light absorption while the advantageous light distribution characteristic is maintained.

It has been realized that this aim can be achieved by providing the double bulge as a separate element instead of forming it at the end of the LED devices. Then it can be placed before the LED devices during assembly of the panels containing the LED devices. In this manner the optical part comprising the double bulge can be made of polycarbonate, advantageously thinned polycarbonate which is less light absorbing.

According to the above in case of the illuminator as described in the preamble separate optical beam forming elements (11) having a double bulge are placed before the light emitting end of the LED devices.

A detailed description of the illuminator for use in public lighting according to the invention will be described with reference to the accompanying drawings in which:

Figure 1 shows the cross-section of a portion of a known illuminator for use in public lighting;

Figure 2 is the side view of the end of a LED device used in the embodiment according to Figure 1 ; Figure 3 shows the end of a LED device used in the embodiment according to Figure 1 as viewed from above;

Figure 4 shows the cross-section of a portion of the illuminator for use in public lighting according to the invention; and

Figure 5 shows the cross-section of a portion of the illuminator according to the invention with the LED device cut at the middle.

In Figure 1 the cross-section of a portion of the illuminator according to utility model HU 3796 is shown. Here an arrangement containing LED devices 1 built in printed circuit board panel 4 usable in an illuminator can be seen. If necessary, a cooling surface 5 can be applied on the opposite side of printed circuit board panel 4. This can be any kind of known medium which can be connected to the metal elements without causing short circuit and is suitable for dissipating the developing heat.

In case of the embodiment of Figure 1 the panel of the printed circuit board 4 is flat, and the individual LED devices 1 are arranged in the direction of vertical axes parallel to each other. However, angle distribution of the emitted light along these directions is different in the plane of the Figure and in the plane perpendicular to it. This is because the LED device for controlled light emission is provided with a transparent dome-shaped end 7 in which a double bulge is formed as shown in Figure 2. This means that two convex surfaces 8 for example spherical or parabolic surfaces are formed which intersect each other. The top view of it can be seen in Figure 3.

In this embodiment LED device 1 emits light with asymmetric angle characteristic. In Figure 3 the top view of the two intersecting convex surfaces 8 is shown, which have a longitudinal first plane s as median plane and meet (intersect each other) in a second plane f representing a median plane perpendicular to the first one. In Figure 2 axes t1 and t2 in end 7 represent the centre lines of convex surfaces 8 which meet second plane f in a half aperture angle a.

The surface and beam forming optical element shown in Figures 2 and 3 are maintained in the present solution. However, in the solution according to the present invention production of the LED device and the beam forming element is separated. The latter is added during assembly of the illuminator. The main difference as compared to the known solutions is that the light source forms a separate piece independent from the optical beam forming element, thereby it can be made of a different material.

According to the present solution axes t1 and t2 advantageously but not necessarily intersect each other in the second plane f. If the curvature or the angle of inclination of convex surfaces 8 is different, this does not hold true. Further, it can be stated that it is not necessary for light emitting element 9 i.e. the semiconductor chip of the LED device to be in the point of intersection of axes t1 and t2 as it is shown in the embodiment of Figure 2. If the light emitting element 9 is positioned in a point downward or upward from the point of intersection then the first and the second light emitting angle characteristics are changed.

In Figure 4 a cross-section of an embodiment according to the present invention is shown in which LED devices 10 comprised in the illuminator are mounted in a printed circuit board 14 and have a light emitting end on the opposite side of the mounting. In our days this kind of LED devices 10 can be purchased easily. The light sources in the illuminator have a first plane s and perpendicular to it a second plane f with a respective first and second light emitting angle characteristic, wherein the angle range of the first light emitting angle characteristic is wider than the second light emitting angle characteristic. At least in the directions of light emission the LED devices 10 are encompassed by a transparent dome-shaped covering 12 or covering portion 12' inserted in the weatherproof covering surface 13. The individual coverings 12 or covering portions 12' are encompassed at least in the direction of light emission by the weatherproof covering surface 13. This covering surface 13 may be for example a transparent plate provided with dome-shaped protrusions over the LED devices 10. As it is shown in Figure 4 covering 12 and covering surface 13 may be formed as separate pieces, or covering surface 13 may be produced together with covering portions 12' forming an integral unit. The dome-shaped protrusions must be formed individually because e.g. if the weatherproof covering is provided as a transparent flat plate it would cause total reflection at a certain angle of incidence (approximately 60°) slightly depending on the refraction index of the glass or plastic material used for the plate. In case of usually used material wide ranging angles for lighting cannot be ensured easily, because light is reflected from the transparent covering due to the low angle of incidence, i.e. it does not emerge directly from the illuminator. This problem is eliminated by the present invention by providing the individual LED devices 10 with transparent weatherproof covering 12 or at least covering portion 12' respectively. These are dome-shaped coverings 12. The fact that the individual LED devices 10 are respectively encompassed by covering 12 does not mean that they must be formed as separate pieces. Covering portions 12' for more than one LED device may be formed in one piece together with the flat portion 13' of covering e.g. by using die-casting method. In the left part of Figure 4 two covering portions 12' formed in this manner are shown. The flat portion 13' of covering may be non-transparent. However, die-casting is easier if it is made from the same material. In certain cases the flat portion 13' may be omitted in certain parts of covering surface 13.

Beam forming is realized by placing separate optical beam forming elements 11 provided with a double bulge before the light emitting end of LED devices 10. These are not parts of LED devices 10, advantageously they are held in proper position by an element contained in the printed circuit board 4. Detailed description of it will be given with reference to the following Figure. Advantageously, the material of the optical beam forming elements 11 is crystalline, transparent polycarbonate. Light transmitting capacity of it is higher than that of the silicone of the same thickness which is customarily used for the material of the light emitting ends of LED devices 10. The surface of the optical beam forming elements 11 facing these ends may be formed as a flat lower boundary 18 or even a concave lower boundary 18' as illustrated in Figure 4. Advantageously, a carrier 15 or cooling surface is provided on the other side of printed circuit board 14.

Figure 5 shows a LED device 10 and its component parts according to Figure 4, but the plane of intersection is perpendicular to the previous one. Further, for the sake of clarity the double bulge is turned so that it can be viewed in its typical form. The legs 20 of a LED device 10 are attached e.g. soldered to printed circuit board 14. At the LED devices 10 a polycarbonate plate 16 is placed on printed circuit board 14, which is provided with apertures 7 for the protruding LED devices 10. Between the light emitting end of LED devices 10 and the lower boundary 18 of the separate optical beam forming elements 11 there is a gap 19. This is filled with air, or may be filled entirely or partly with a transparent silicone layer or some other light transmitting material. Polycarbonate plate 16 may be U- shaped as it is shown in Figure 5, in which the printed circuit board 14 can be accommodated. Preferably, the polycarbonate plate 16 and the polycarbonate optical beam forming elements 11 are die-cast in one piece.

Covering 12 may have several forms. In its simplest form it is shaped as a segment of a sphere made of a transparent material having a constant thickness. The segment of a sphere may be a hemisphere or a segment different from a hemisphere. Depending on the shape of the LED devices 10 as well as the required attainable angle characteristic of light emission, the outer covering may have a shape different from a sphere. It may be for example cylindrical or elliptical or parabolic.

The advantage of the present invention is that loss of light and also the manufacturing costs of illuminators used in public lighting are decreased.

Claims

1. Illuminator for use in public lighting comprising LED devices (10) as light source, said LED devices (10) are mounted in printed circuit board (14) and have a light emitting end on the opposite side of the mounting; the light sources in the illuminator have a first plane (s) and perpendicular to it a second plane (f) with a respective first and second light emitting angle characteristic, the angle range of the first light emitting angle characteristic is wider than that of the second light emitting angle characteristic; the illuminator is provided with a weatherproof covering surface (13) in the direction of light emission, and the LED devices (10) are encompassed at least in the directions of light emission with a transparent dome-shaped covering (12) or covering portion (12') inserted in the weatherproof covering surface (13), characterized in that separate optical beam forming elements (11) provided with a double bulge are placed before the light emitting end of said LED devices (10).

2. Illuminator according to claim 1 characterized in that the material of said optical beam forming element (11) is polycarbonate.

3. Illuminator according to claim 1 characterized in that the two axes (t1 , t2) of the double bulge of said optical beam forming element (11) fall in said first plane (s).

4. Illuminator according to claim 1 characterized in that said optical beam forming elements (11) are coupled to a polycarbonate plate (16) placed on said printed circuit board (14) and provided with apertures (17) at said LED devices (10), wherein a gap (19) is provided between the light emitting end of said LED devices (10) and the lower boundary (18, 18') of said separate optical beam forming elements (11).

5. Illuminator according to claim 4 characterized in that said gap (19) is at least partly filled with a silicone layer or some other light transmitting material.

6. Illuminator according to claim 1 characterized in that the double bulge of said optical beam forming elements (11) is formed from two convex surfaces (8) intersecting each other.

7. Illuminator according to claim 6 characterized in that said two intersecting convex surfaces (8) are two identical segments of a sphere.

8. Illuminator according to claim 4 characterized in that said optical beam forming elements (11) and said polycarbonate plate (16) are formed in one piece.

9. Illuminator according to any of claims 1-8 characterized in that said lower boundary (18) of said separate optical beam forming elements (11) is flat.

10. Illuminator according to any of claims 1-8 characterized in that said lower boundary (18') of said separate optical beam forming elements (11) is concave.