Field of the invention

The present patent application relates to high intensity airfield lighting system, e. g. a runway edge lighting system or a taxiway lighting system, comprising a main body, a dome securable to the main body, wherein the dome is designed for light transmission and at least partially transparent, at least one light unit covered by the dome and comprising at least one first lighting element fixed to a carrier of the light unit, at least one first optical element designed to receive light from the first lighting element and to emit the light received in a main light-exit direction, and a support for the at least one first optical element, and a heat sink for dissipating heat generated by the first lighting element.

In WO 2011/134984 A1 an airfield lighting system is disclosed which comprises a main body built to carry two light units on opposite sides of the body. Each light unit comprises at least one lighting element, a circuit broad for the lighting element and a heat sink built for dissipating heat generated by the light elements. The airfield lighting device is built to emit light in two opposite light-exit directions and utilizes light emitting diodes as light sources. It can be used as airfield runway edge, and, threshold and approach lighting system. Due to light emitting into two well defined light-exit directions the lighting system is not suitable for use as an omnidirectional airfield lighting system.

Summary of the invention

The problem to be solved in this invention is to provide an airfield lighting system which can be used to emit light in well-defined light-exit direction and as an

omnidirectional airfield lighting system. The lighting system should be built as modular lighting system in order to realize either one of the lighting functions but both of them. In order to solve the problem the lighting system is characterized in that at least one second lighting element and at least one second optical element are provided with the second optical element receiving the light of the second lighting element and emitting the light received at least semicircular within a light-exit plane.

The inventive lighting system has a very compact design which allows the realization of two different lighting functions. First, light emitted by the first lighting elements passes through the first optical elements and is emitted in a main light-exit direction allowing the lighting system to be used as runway edge lighting system, taxiway lighting system or the like. Second, light of the second lighting element is emitted into a light-exit plane allowing the lighting system to be used as omnidirectional lighting system as well. As one or both of the lighting functions can be realized within the lighting system it provides high degree of flexibility with respect to the field of application of the lighting system. The lighting system is built for the use of modern high power light emitting diodes. The heat sink provided dissipates heat generated by the lighting elements of the light unit.

In a preferred embodiment of the invention the at least one second lighting element is fixed to the heat sink and/or to the carrier of the light unit. Fixing the second lighting element to the heat sink allows sufficient heat dissipation. The heat sink used to dissipate heat generated by the first lighting element can also be used to dissipate heat generated by the second lighting element. Fixing the second lighting element of the carrier of the light unit allows a compact architecture of the light unit and makes assembly easy and fast. E. g. the carrier assembly could be done within a single production step as well as mounting of the assembled carrier to the heat sink.

Moreover, the effort for wiring the lighting elements is reduced.

According to a further embodiment of the invention an electronic circuit for powering and driving the first lighting element and/or the second lighting element is provided and mounted to the heat sink in such a way that heat generated by the electronic circuit is dissipated by the heat sink. Therefore, the heat sink is used to dissipate heat generated by both the lighting elements and the electronic circuit. This reduces cost and allows for an additional reduction of the size of the lighting system.

The heat sink may comprise of a first heat sink section carrying the light unit and a second heat sink section carrying the electronic circuit. By providing a heat sink with at least two heat sink sections each section can be individually designed with respect to the requirements of the light unit and the electronic circuit. E. g. the dissipating capacity of each heat sink section can be adjusted to the heat generated by the electronic circuit or the lighting elements.

According to a further embodiment of the invention the at least one second lighting element is in an elevated position with respect to the at least one first lighting element within an upright position of the lighting system. E. g. the second lighting element can be mounted on the top of the heat sink with the first lighting element been mounted underneath the second lighting element. The elevate position of the second lighting element allows good optical conditions for the omnidirectional lighting function while the position of the first lighting elements has no negative effect on the light emission in the main light-exit direction. Therefore, both lighting functions can be realized within one lighting system.

In an operating position of the lighting system the first heat sink section has a vertical orientation with the two opposed installation surfaces being arranged symmetrical to a vertical center axis of the first heat sink section while the second heat sink section is orientated horizontally. The electronic circuit is mounted to a bottom side of the horizontally orientated second heat sink section. The first heat sink section might be built as a wedge-shaped heat sink section with the second lighting element being mounted on two different sides of the tip of the wedge-shaped heat sink section and with the installation surfaces for the light units being built on two plain surfaces of the wedge. The wedge-shaped first heat sink section makes it easy to emit the light of the first lighting element to the main light-exit direction which is in an upgrade position with respect to the light-exit plane of the second lighting elements. At least two second lighting elements and corresponding second optical elements can be provided and arranged in such a way that light emitted by the second lighting elements and passed through the second optical elements completely is emitted into the light-exit plane. Advantageously the omnidirectional lighting function can be provided with as few as two second lighting elements which are in elevated position to the heat sink and/or the first lighting elements. The vertical distance of the second lighting elements should be small to allow good illumination of the light-exit plane. E. g. the vertical distance should be 5.0 cm or less, preferred 3.5 cm or less.

According to a further embodiment of the invention the main body is part of the heat sink. The integrative of the main body into the heat sink improves heat dissipation. E. g. the main body may provide cooling fins or the like to enlarge the outside surface. Moreover, a heat sink comprising the main body as well as the first heat sink section and the second heat sink section can be built as a single solid body in a cost efficient way, e. g. by casting.

According to a further embodiment of the invention the lighting system comprises a drainpipe and a hollow in the bottom section of the heat sink for draining off entrapped moisture. The drainpipe can be built as a siphon-shaped drainpipe. Providing the hollow and/or the drainpipe allows protection of the electronic circuit from getting into contact with moisture or the like. The electronic circuit may be built as a sealed electronic circuit in order to provide even better protection from moisture input.

Therefore, the lighting system has a moisture proof design with high reliability and improved durability. Even if the dome is damaged and water from outside can enter the lighting system failures can be prevented.

Moreover, a heater can be provides which is integrated into the electronic circuit in order to allow reliable function even at cold temperature and rough environmental conditions. The heater heats the heat sink in order to defreeze the functional components of the lighting system, e. g. the light units and the dome.

Further advantages of this invention are disclosed in the subclaims. Brief description of the drawings

The present invention will become more fully understood from the detailed description given hereinbelow and the accompanying drawings which are given by way of illustration only, and thus, are not limitive to the present invention.

In the drawings:

Fig. 1 shows a first embodiment of the inventive lighting system;

Fig. 2 shows an exploded view of the lighting system of fig. 1 ;

Fig. 3 shows an exploded view of a light unit of the lighting system of fig. 1 ;

Fig. 4 shows a section of view of the lighting system of fig. 1 ;

Fig. 5 shows a detailed view on a hollow and a drainpipe of the lighting system of fig. 1 ;

Fig. 6 shows a cross-sectional view on the lighting system of fig. 1 ; and Fig. 7 shows a second embodiment of the inventive lighting system. Detailed description of the drawings

A first embodiment of the inventive lighting system is shown in the fig. 1 to 6. The main components of the lighting system are a main body 1 , a dome 2, a fixing ring 3, two light units 4, an electronic circuit 5, an adapter plate 6 and a socket 7. The main body 1 is part of the heat sink 8 which also consists of a first heat sink section 9 carrying the two light units 4 and a second heat sink section 10 carrying the electronic circuit 5. Each light unit 4 comprises a carrier 11 carrying four light emitting diodes as first lighting elements 12, four first optical elements 13 and a support 14 for the first optical elements 13. The first lighting elements 12 are mounted to the carrier 11 of the light unit 4. The support 14 is also fixed to the carrier 11. The first optical elements 13 are arranged in such a way that light emitted by the first lighting elements 12 is received by the first optical elements 13 and emitted by the first optical elements 13 in a main light-exit direction 15 after passing the first optical elements 13.

The lighting units 4 are fixed to the first heat sink section 9 which is in a central position with respect to the main body 1 of the heat sink 8 and covered by the dome 2. The first heat sink section 9 is designed as a wedge-shaped heat-sink section 9 carrying the light units 4. With respect to the light units 4 two opposed plain surfaces of the wedge-shaped heat sink section 9 define two installation surfaces 16 which are in plain contact with the carrier 11 of the lighting units 4.

The carrier 11 also holds a connector plug 17 for connecting the light emitting diodes 12 and the electronic circuit 5 via cable 18.

Heat generated by the light units 4 is dissipated by the heat sink 8. Moreover, the heat sink 8 dissipates heat generated by the electronic circuit 5.

A second lighting element 19 and a second optical element 20 assigned to the second lighting element 19 is also fixed to the carrier 11. Light emitted by the second lighting element is received by the second optical element 20 and emitted primarily into a light- exit plane 21 which has horizontal orientation with the lighting system being in an vertical operating position. Light refracted by the second lighting element 19 allows the lighting system to realize an omnidirectional lighting function. A vertically spreading angle of the light emitted by the second optical element basically varies between -1 ⁰ and +16° with respect to the light-exit plane with a small portion of the light being emitted upwards. The horizontal spreading angle of the second optical element 20 varies from -95° to +95° with respect to a horizontal center axis 22 of the lighting system. In order to emit light into the whole light-exit plane 21 two second lighting elements 19 are provided on two opposed sides of the wedge-shaped first heat sink section 9. The second lighting elements 19 are located close to the tip 24 of the wedge-shaped heat sink section 9 and in an elevated position with respect to the tip 24 of the wedge- shaped heat sink section 9 and the first lighting elements 12 allowing the light emission without interference with the light units 4 or the heat sink 8. A horizontal distance of the two lighting elements 19 is less than 3.5 cm.

With the two light units 4 and the two second lighting elements 9 the lighting system provides two light functions. The light units 4 emit light into the main light-exit direction 15. The second lighting elements 19 emit light into the light-exit plane 21 allowing an omnidirectional lighting function to be realized. Depending on individual requirements on the airfield the modular design of the lighting systems allows to include both lighting functions or either one of them. Moreover, the main light-exit direction 15 can vary depending on the design of the light units 4. By changing the support 14 of the light unit 4 an angle 23 between the main light-exit direction 15 and the horizontal center axis 22 of the lighting system can be adopted. Typical light-exit angles 23 are 0°, 3.5° and 4.5°. The angles 23 are realized by varying the orientation of the first optical elements 13 within the support 14. Therefore, the main light-exit direction 15 can be chosen by changing the support 14 of the light unit 4 while all other elements (e. g. carrier 11 , first lighting element 12, first optical element 13, and connector plug 17) remain unchanged.

The dome 2 of the lighting system can be made of plastic or glass. It is at least partially transparent and allows light emitted by the lighting elements 12, 19 to pass through. It is realized without lenses or other optical elements.

The fixing ring 3 can be locked to the main body 1 without a tool. The fixing ring 3 and the main body 1 are connected by bayonet means. In order to avoid moisture draining into the lighting system a sealing 25 is provided between the main body 1 and the dome 2. The electronic circuit 5 is fixed to the second heat sink section 10 which has a mainly horizontal orientation. The electronic circuit 5 is mounted to a bottom side of the section heat sink section 10. The cable 18 connecting the light units 4 and the electronic circuit 5 passes through a slot 29 in the second heat sink section 10. The electronic circuit 5 is sealed with the sealing not been shown in the fig. 1 to 6.

Due to the rough environmental conditions on an airfield the ingress of moisture cannot be avoided completely. E. g. the dome can be damaged. Therefore, the mainly horizontal orientated second heat sink section 10 provides a hollow 26 allowing water to pass through. In order to make sure that water passing the hollow 26 does not damage the electronic circuit 5 a drainpipe 27 is provided. The drainpipe 27 is connected to the hollow 26. It is realized as a siphon-type drainpipe 27 with an opening 28 in an upward orientation facing the electronic circuit 5. If moisture enters the lighting system due to damages of the dome 2 or the like it passes through the hollow 26 and enters the drainpipe 27 without getting into contact to the electronic circuit 5.

The adapter plate 6 is designed to connect the heat sink 8 with a socket 7. The design of the adapter plate 6 allows water passing through the drainpipe 27 to exit the lighting system via an annular gap 30 built between the main body 1 and the adapter plate 6. Moreover, the adapter plate 6 allows the socket 7 to be connected to different types of main bodies 1 or heat sinks 8.

The optical elements 13, 20 are realized as lenses in an alternative embodiment of the invention which is not shown in the figures. Any other suitable refracting or reflecting optics could also be used to realize the optical elements 13, 20.

Fig. 7 shows a second embodiment of the invention with a slightly different design. A heat sink 8 is realized as a multipart heat sink 8. It comprises a first heat sink component 31 with a main body 1 and the horizontal orientated heat sink section 10. Furthermore, the heat sink 8 comprises two second heat sink components 32, carrying the light units 4. The two second heat sink components 32 are fixed to the first heat sink component 31 by means of screws. The second heat sink components 32 are in an upward position and have a vertical orientation. They are symmetrical arranged with respect to a vertical center axis 33 of the lighting system. The light units 4 are fixed to two opposed installation surfaces 16 of the second heat sink component 32. The second lighting elements 19 are mounted to a front edge 34 of the heat sink component 32. The electronic circuit 5 is mounted to a bottom side of the second heat sink section 10. A sealing 35 for the electronic circuit 5 is provided protecting the electronic circuit 5.

In both embodiments the light units 4 are realized as modular light units which are changeably mounted to the heat sink 8.

List of reference numbers

1 main body

2 dome

3 fixing ring

4 light unit

5 electronic circuit

6 adapter plate

7 socket

8 heat sink

9 first heat sink section

10 second heat sink section

11 carrier

12 first lighting element

13 first optical element

14 support

15 main light-exit direction

16 installation surface

17 connector plug

18 cable

19 second lighting element

20 second optical element

21 light-exit plane

22 horizontal center axis

23 angle

24 tip

25 sealing

26 hojlow

27 drainpipe

28 opening

29 slot

30 annular gap first heat sink component second heat sink component vertical center axis front edge

sealing